Sample records for zn-pb-ag deposit northern

  1. The Anarraaq Zn-Pb-Ag and barite deposit, northern Alaska: Evidence for replacement of carbonate by barite and sulfides

    Kelley, K.D.; Dumoulin, J.A.; Jennings, S.


    The Anarraaq deposit in northern Alaska consists of a barite body, estimated to be as much as 1 billion metric tons, and a Zn-Pb-Ag massive sulfide zone with an estimated resource of about 18 Mt at 18 percent Zn, 5.4 percent Pb, and 85 g/t Ag. The barite and sulfide minerals are hosted by the uppermost part of the Mississippian Kuna Formation (Ikalukrok unit) that consists of carbonaceous and siliceous mudstone or shale interbedded with carbonate. The amount of interbedded carbonate in the Anarraaq deposit is atypical of the district as a whole, comprising as much as one third of the section. The total thickness of the Ikalukrok unit is considerably greater in the area of the deposit (210 to almost 350 m) than to the north and south (maximum of 164 m). The mineralized zone at Anarraaq is lens shaped and has a relatively flat top and a convex base. It also ranges greatly in thickness, from a few meters to more than 100 m. Textures of some of the carbonate layers are distinctive, consisting of nodules within siliceous mudstone or layers interbedded with shale. Many of the layers contain calcitized sponge spicules or radiolarians in a carbonate matrix. Textures of barite and sulfide minerals mimic those of carbonate and provide unequivocal evidence that replacement of precursor carbonate was an important process. Barite and sulfide textures include either nodular, bladed grains of various sizes that resemble spicules (observed only with iron sulfides) or well-rounded forms that are replaced radiolarians. Mineralization at Anarraaq probably occurred in a fault-bounded Carboniferous basin during early diagenesis in the shallow subsurface. The shape and size of the mineralized body suggest that barite and sulfides replaced calcareous mass flow deposits in a submarine channel. The distribution of biogenic and/or early diagenetic silica may have served as impermeable barriers to the fluids, thereby focusing and controlling fluid flow through unreplaced carbonate layers

  2. Nature of hydrothermal fluids at the shale-hosted Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska

    Leach, David L.; Marsh, Erin E.; Emsbo, Poul; Rombach, Cameron; Kelley, Karen D.; Anthony, Michael W.


    The Red Dog Zn-Pb-Ag district in the western Brooks Range, northern Alaska, contains numerous shale-hosted Zn-Pb sulfide and barite deposits in organic-rich siliceous mudstone and shale, chert, and carbonate rocks of the Carboniferous Kuna Formation. The giant Red Dog shale-hosted deposits consist of a cluster of four orebodies (Main, Qanaiyaq, Aqqaluk, and Paalaaq) that lie within distinct thrust panels that offset a single ore deposit during the Mesozoic Brookian orogeny. These Zn-Pb-Ag-barite orebodies contain one of the world's largest reserves and resources of zinc.

  3. Structure and age of the Cerro de Pasco Cu-Zn-Pb-Ag deposit, Peru

    Cheney, E. S.


    The world-famous Cu-Zn-Pb-Ag deposit at Cerro de Pasco, Peru, consists of texturally massive pyrite, texturally massive sphalerite-galena-pyrite, and veins containing pyrite and enargite. Historically the deposit has been considered to be the hydrothermal product of the adjacent Miocene volcanic and intrusive complex (locally known as the “Vent”). However, both the texturally massive sulfides of the deposit and the pre-Miocene strata are cut by the Longitudinal fault, one of the largest faults in the district, but the Vent is not. Imbrication by the Longitudinal fault zone (duplex structures) has thickened the deposit so that it is amenable to open-pit mining. Dikes and pyrite-enargite veins pass from the Vent into the massive sulfides; fragments of massive pyrite occur in the Vent. Thus, no matter what their origin, the texturally massive sulfides are older and, therefore, genetically unrelated to the Vent.

  4. Geochronology of the western and central Brooks Range, Alaska: Implications for the geologic evolution of the Anarraaq and Red Dog Zn-Pb-Ag deposits

    Rombach, C.S.; Layer, P.W.


    A compilation of published geochronology of rocks and minerals from the western and central Brooks Range provides a framework for understanding the complex history of the Brooks Range and northern Alaska. A simplified timeline of events comprises (1) Devonian extension, (2) Mississippian extension and Zn-Pb-Ag mineralization, (3) a passive interval, (4) pre-Brooks Range orogeny rock-formation and thermal event, (5) inception of Brooks Range orogeny, (6) exhumation and the end of main-stage deformation, and (7) subsequent episodic deformation. This compilation is supplemented by new 40Ar/39Ar dates of white mica from the Anarraaq and Red Dog Zn-Pb-Ag (+ barite) deposits from the western Brooks Range. The deposits are hosted in black shale and carbonate rocks of the Late Mississippian-Early Pennsylvanian Kuna Formation. Quartz-pyrite-white mica grains in sedimentary rocks above the Anarraaq deposit yield an age of 195.0 ?? 2.0 Ma, and paragenetically late quartz-pyrite-white mica from the Main orebody at the Red Dog deposit has an age of 126.1 ?? 0.7 Ma. These white micas are much younger than the age of Zn-Pb-Ag mineralization at Red Dog (338 ?? 5.8 Ma Re-Os age of pyrite). The date for white mica from Anarraaq (???195 Ma) appears to be related to a large-scale thermal event in the region immediately before the inception of the Brooks Range orogeny. The white mica from the Red Dog deposit (???126 Ma) correlates with the later stages of the orogeny, a period of blueschist metamorphism, extension, and rapid exhumation, which varied with geographic location. These dates suggest that the Red Dog deposits underwent significant hydrothermal overprinting during multiple episodes of the Brooks Range orogeny. ?? 2004 by Economic Geology.

  5. The origin of skarn beds, Ryllshyttan Zn-Pb-Ag + magnetite deposit, Bergslagen, Sweden

    Jansson, Nils F.; Allen, Rodney L.


    Thin- to medium-bedded, stratiform calc-silicate deposits (banded skarns) are a peculiar, but important, component of the supracrustal successions in the Palaeoproterozoic Bergslagen mining district of central Sweden. They are referred to as "skarn-banded leptites" in the literature and are common in areas and at stratigraphic levels that contain iron oxide and base metal sulphide deposits. The stratigraphic hanging wall of the stratabound Ryllshyttan Zn-Pb-Ag + magnetite deposit at Garpenberg, contains approximately 100-150 m of interbedded aluminous skarn beds and rhyolitic ash-siltstones. The skarn beds are mineralogically variable and dominantly composed of grandite, spessartine, epidote, actinolite, quartz, clinopyroxene, and locally magnetite. Integrated field-mapping, and whole-rock lithogeochemical, microscopic and mineral chemical analyses suggest that the stratiform skarn beds are the products of at least two discrete hydrothermal events and subsequent metamorphism. The first event comprised accumulation in a quiescent subaqueous environment, below wave base, of calcareous and ferruginous sediments rich in Fe, Mn, Ca, and Mg. These chemical sediments were deposited concurrently with rhyolitic ash-silt sedimentation, thus forming a (now metamorphosed) laminated calcareous Fe formation with both a detrital rhyolitic component and rhyolitic siltstone interbeds. Positive Eu-anomalies and negative Ce-anomalies for normalized rare earth element analyses of skarn beds suggest that the iron may have been derived from exhalation of hot and reduced hydrothermal fluids, which upon mixing with more oxidized seawater, precipitated Fe oxides and/or carbonates that settled from suspension to the seafloor. The size of the positive Eu-anomalies of the chemical sediments are modified by the content of rhyolitic volcaniclastic material, which has a negative Eu anomaly, such that positive Eu-anomalies are only observed in skarn beds that possess a minor volcaniclastic

  6. Multistage hydrothermal silicification and Fe-Tl-As-Sb-Ge-REE enrichment in the Red Dog Zn-Pb-Ag district, northern Alaska: Geochemistry, origin, and exploration applications

    Slack, J.F.; Kelley, K.D.; Anderson, V.M.; Clark, J.L.; Ayuso, R.A.


    Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO2/Al2O3 and TiO2/Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* > 1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe, Ba, Eu, V, S, Co, Zn, Pb, Tl, As, Sb, and Ge at both Red Dog and Anarraaq, Si at Red Dog, and Sr, U, and Se at Anarraaq. Large depletions (>50%) are evident for Ca at both Red Dog and Anarraaq, for Mg, P, and Y at Red Dog, and for Na at Anarraaq. At both Red Dog and Anarraaq, wall-rock alteration removed calcite and minor dolomite during hydrothermal decarbonation reactions and introduced Si, Eu, and Ge during silicification. Sulfidation reactions deposited Fe, S, Co, Zn, Pb, Tl, As, and Sb; barite mineralization introduced Ba, S, and Sr. Light REE and U were mobilized locally. This alteration and mineralization occurred during Mississippi an hydrothermal events that predated the Middle Jurassic-Cretaceous Brookian orogeny. Early hydrothermal silicification at Red Dog took place prior to or during massive sulfide mineralization, on the basis of the dominantly planar nature of Zn-Pb veins, which suggests

  7. 40Ar/39Ar Dating of Zn-Pb-Ag Mineralization in the Northern Brooks Range, Alaska

    Werdon, Melanie B.; Layer, Paul W.; Newberry, Rainer J.


    The 40Ar/39Ar laser step-heating method potentially can be used to provide absolute ages for a number of formerly undatable, low-temperature ore deposits. This study demonstrates the use of this method by determining absolute ages for Zn-Pb-Ag sediment-hosted massive sulfide deposits and vein-breccia occurrences found throughout a 300-km-long, east-west-trending belt in the northern Brooks Range, Alaska. Massive sulfide deposits are hosted by Mississippian to Pennsylvanian(?) black carbonaceous shale, siliceous mudstone, and lesser chert and carbonate turbidites of the Kuna Formation (e.g., Red Dog, Anarraaq, Lik (Su), and Drenchwater). The vein-breccia occurrences (e.g., Husky, Story Creek, West Kivliktort Mountain, Vidlee, and Kady) are hosted by a deformed but only weakly metamorphosed package of Upper Devonian to Lower Mississippian mixed continental and marine clastic rocks (the Endicott Group) that stratigraphically underlie the Kuna Formation. The vein-breccias are mineralogically similar to, but not spatially associated with, known massive sulfide deposits. The region's largest shale-hosted massive sulfide deposit is Red Dog; it has reserves of 148 Mt grading 16.6 percent zinc, 4.5 percent lead, and 77 g of silver per tonne. Hydrothermally produced white mica in a whole-rock sample from a sulfide-bearing igneous sill within the Red Dog deposit yielded a plateau age of 314.5 Ma. The plateau age of this whole-rock sample records the time at which temperatures cooled below the argon closure temperature of the white mica and is interpreted to represent the minimum age limit for massive sulfide-related hydrothermal activity in the Red Dog deposit. Sulfide-bearing quartz veins at Drenchwater crosscut a hypabyssal intrusion with a maximum biotite age of 337.0 Ma. Despite relatively low sulfide deposition temperatures in the vein-breccia occurrences (162°-251°C), detrital white mica in sandstone immediately adjacent to large vein-breccia zones was partially to

  8. The Drenchwater deposit, Alaska: An example of a natural low pH environment resulting from weathering of an undisturbed shale-hosted Zn-Pb-Ag deposit

    Graham, G.E.; Kelley, K.D.


    The Drenchwater shale-hosted Zn-Pb-Ag deposit and the immediate vicinity, on the northern flank of the Brooks Range in north-central Alaska, is an ideal example of a naturally low pH system. The two drainages, Drenchwater and False Wager Creeks, which bound the deposit, differ in their acidity and metal contents. Moderately acidic waters with elevated concentrations of metals (pH ??? 4.3, Zn ??? 1400 ??g/L) in the Drenchwater Creek drainage basin are attributed to weathering of an exposed base-metal-rich massive sulfide occurrence. Stream sediment and water chemistry data collected from False Wager Creek suggest that an unexposed base-metal sulfide occurrence may account for the lower pH (2.7-3.1) and very metal-rich waters (up to 2600 ??g/L Zn, ??? 260 ??g/L Cu and ???89 ??g/L Tl) collected at least 2 km upstream of known mineralized exposures. These more acidic conditions produce jarosite, schwertmannite and Fe-hydroxides commonly associated with acid-mine drainage. The high metal concentrations in some water samples from both streams naturally exceed Alaska state regulatory limits for freshwater aquatic life, affirming the importance of establishing base-line conditions in the event of human land development. The studies at the Drenchwater deposit demonstrate that poor water quality can be generated through entirely natural weathering of base-metal occurrences, and, possibly unmineralized black shale.

  9. Reactive flow models of the Anarraaq Zn-Pb-Ag deposit, Red Dog district, Alaska

    Schardt, C.; Garven, G.; Kelley, K.D.; Leach, D.L.


    The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency). ?? Springer-Verlag 2008.

  10. Reactive flow models of the Anarraaq Zn-Pb-Ag deposit, Red Dog district, Alaska

    Schardt, Christian; Garven, Grant; Kelley, Karen D.; Leach, David L.


    The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200°C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS- source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency).

  11. Formation of the Wiesloch Mississippi Valley-type Zn-Pb-Ag deposit in the extensional setting of the Upper Rhinegraben, SW Germany

    Pfaff, Katharina; Hildebrandt, Ludwig H.; Leach, David L.; Jacob, Dorrit E.; Markl, Gregor


    The Mississippi Valley-type (MVT) Zn-Pb-Ag deposit in the Wiesloch area, Southwest Germany, is controlled by graben-related faults of the Upper Rhinegraben. Mineralization occurs as vein fillings and irregular replacement ore bodies consisting of sphalerite, banded sphalerite, galena, pyrite, sulfosalts (jordanite and geocronite), barite, and calcite in the Middle Triassic carbonate host rock. Combining paragenetic information, fluid inclusion investigations, stable isotope and mineral chemistry with thermodynamic modeling, we have derived a model for the formation of the Wiesloch deposit. This model involves fluid mixing between ascending hot brines (originating in the crystalline basement) with sedimentary formation waters. The ascending brines originally had a near-neutral pH (around 6) and intermediate oxidation state, reflecting equilibrium with granites and gneisses in the basement. During fluid ascent and cooling, the pH of the brine shifted towards more acidic (around 4) and the oxidation state increased to conditions above the hematite-magnetite buffer. These chemical characteristics contrast strongly with those of the pore and fracture fluid residing in the limestone aquifer, which had a pH between 8 and 9 in equilibrium with calcite and was rather reduced due to the presence of organic matter in the limestone. Mixing between these two fluids resulted in a strong decrease in the solubility of silver-bearing sphalerite and galena, and calcite. Besides Wiesloch, several Pb-Zn deposits are known along the Upper Rhinegraben, including hydrothermal vein-type deposits like Badenweiler and the Michael mine near Lahr. They all share the same fluid origin and formation process and only differ in details of their host rock and fluid cooling paths. The mechanism of fluid mixing also seems to be responsible for the formation of other MVT deposits in Europe (e.g., Reocin, Northern Spain; Treves, Southern France; and Cracow-Silesia, Poland), which show notable

  12. Formation of the Wiesloch Mississippi Valley-type Zn-Pb-Ag deposit in the extensional setting of the Upper Rhinegraben, SW Germany

    Pfaff, Katharina; Hildebrandt, Ludwig H.; Leach, David L.; Jacob, Dorrit E.; Markl, Gregor


    The Mississippi Valley-type (MVT) Zn-Pb-Ag deposit in the Wiesloch area, Southwest Germany, is controlled by graben-related faults of the Upper Rhinegraben. Mineralization occurs as vein fillings and irregular replacement ore bodies consisting of sphalerite, banded sphalerite, galena, pyrite, sulfosalts (jordanite and geocronite), barite, and calcite in the Middle Triassic carbonate host rock. Combining paragenetic information, fluid inclusion investigations, stable isotope and mineral chemistry with thermodynamic modeling, we have derived a model for the formation of the Wiesloch deposit. This model involves fluid mixing between ascending hot brines (originating in the crystalline basement) with sedimentary formation waters. The ascending brines originally had a near-neutral pH (around 6) and intermediate oxidation state, reflecting equilibrium with granites and gneisses in the basement. During fluid ascent and cooling, the pH of the brine shifted towards more acidic (around 4) and the oxidation state increased to conditions above the hematite-magnetite buffer. These chemical characteristics contrast strongly with those of the pore and fracture fluid residing in the limestone aquifer, which had a pH between 8 and 9 in equilibrium with calcite and was rather reduced due to the presence of organic matter in the limestone. Mixing between these two fluids resulted in a strong decrease in the solubility of silver-bearing sphalerite and galena, and calcite. Besides Wiesloch, several Pb-Zn deposits are known along the Upper Rhinegraben, including hydrothermal vein-type deposits like Badenweiler and the Michael mine near Lahr. They all share the same fluid origin and formation process and only differ in details of their host rock and fluid cooling paths. The mechanism of fluid mixing also seems to be responsible for the formation of other MVT deposits in Europe (e.g., Réocin, Northern Spain; Trèves, Southern France; and Cracow-Silesia, Poland), which show notable

  13. Paleozoic sedimentary rocks in the Red Dog Zn-Pb-Ag district and vicinity, western Brooks Range, Alaska: provenance, deposition, and metallogenic significance

    Slack, John F.; Dumoulin, Julie A.; Schmidt, J.M.; Young, L.E.; Rombach, Cameron


    Geochemical analyses of Paleozoic sedimentary rocks in the western Brooks Range reveal a complex evolutionary history for strata surrounding the large Zn-Pb-Ag deposits of the Red Dog district. Data for major elements, trace elements, and rare earth elements (REE) were obtained on 220 samples of unaltered and unmineralized siliciclastic rocks from the Upper Devonian-Lower Mississippian Endicott Group (Hunt Fork Shale, Noatak Sandstone, Kanayut Conglomerate, Kayak Shale), the overlying Carboniferous Lisburne Group (Kuna Formation, unnamed drowned shelf facies), and the Pennsylvanian-Permian Siksikpuk Formation. Major base metal sulfide deposits of the region are present only in the Kuna Formation, which in the Red Dog district comprises siliceous black shale and black chert, minor limestone (calcareous radiolarite), and sparse lithic turbidite and bedded siliceous rock. Gray and rare black shales of the Kayak Shale and common black shales of the Kuna Formation are anomalously low in iron (avg Fe/Ti = 6.25 and 6.34, respectively) relative to other Paleozoic shales in the region (9.58-10.6) and to average shales worldwide (10.1-10.5). In contrast, the bedded siliceous rocks contain appreciable hematite (avg Fe/Ti = 35.0) and high U/Ti and REE/Ti ratios that are interpreted to reflect low amounts of detrital material and a major Fe-rich eolian component.

  14. Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies

    Johnson, Craig A.; Dumoulin, Julie A.; Burruss, Robert A.; Slack, John F.


    Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-Ag ± barite deposits, which together constitute one of the largest zinc resources in the world. The isotopic and chemical proxies record a deep basin environment that became isolated from the open ocean, became increasingly reducing, and ultimately became euxinic. The basin was ventilated briefly and then became isolated again just prior to its demise as a discrete depocenter with the transition to the overlying Siksikpuk Formation. Ventilation corresponded approximately to the initiation of bedded barite deposition in the district, whereas the demise of the basin corresponded approximately to the formation of the massive sulfide deposits. The changes in basin circulation during deposition of the upper Kuna Formation may have had multiple immediate causes, but the underlying driver was probably extensional tectonic activity that also facilitated fluid flow beneath the basin floor. Although the formation of sediment-hosted sulfide deposits is generally favored by highly reducing conditions, the Zn-Pb deposits of the Red Dog district are not found in the major euxinic facies of the Kuna basin, nor did they form during the main period of euxinia. Rather, the deposits occur where strata were permeable to migrating fluids and where excess H2S was available beyond what was produced in situ by decomposition of local sedimentary organic matter. The known deposits formed mainly by replacement of calcareous strata that gained H2S from nearby highly carbonaceous beds (Anarraaq deposit) or by fracturing and vein formation in strata that produced excess H2S by reductive dissolution of

  15. Trace elements in Zn Pb Ag deposits and related stream sediments, Brooks Range Alaska, with implications for Tl as a pathfinder element

    Graham, G.E.; Kelley, K.D.; Slack, J.F.; Koenig, A.E.


    The Zn-Pb-Ag metallogenic province of the western and central Brooks Range, Alaska, contains two distinct but mineralogically similar deposit types: shale-hosted massive sulphide (SHMS) and smaller vein-breccia occurrences. Recent investigations of the Red Dog and Anarraaq SHMS deposits demonstrated that these deposits are characterized by high trace-element concentrations of As, Ge, Sb and Tl. This paper examines geochemistry of additional SHMS deposits (Drenchwater and Su-Lik) to determine which trace elements are ubiquitously elevated in all SHMS deposits. Data from several vein-breccia occurrences are also presented to see if trace-element concentrations can distinguish SHMS deposits from vein-breccia occurrences. Whole-rock geochemical data indicate that Tl is the most consistently and highly concentrated characteristic trace element in SHMS deposits relative to regional unmineralized rock samples. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analyses of pyrite and sphalerite indicate that Tl is concentrated in pyrite in SHMS. Stream sediment data from the Drenchwater and Su-Lik SHMS show that high Tl concentrations are more broadly distributed proximal to known or suspected mineralization than As, Sb, Zn and Pb anomalies. This broader distribution of Tl in whole-rock and particularly stream sediment samples increases the footprint of exposed and shallowly buried SHMS mineralization. High Tl concentrations also distinguish SHMS mineralization from the vein-breccia deposits, as the latter lack high concentrations of Tl but can otherwise have similar trace-element signatures to SHMS deposits. ?? 2009 AAG/Geological Society of London.

  16. Origin of the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Evidence from regional Pb and Sr isotope sources

    Ayuso, R.A.; Kelley, K.D.; Leach, D.L.; Young, L.E.; Slack, J.F.; Wandless, G.; Lyon, A.M.; Dillingham, J.L.


    Pb and Sr isotope data were obtained on the shale-hosted Zn-Pb-Ag Red Dog deposits (Qanaiyaq, Main, Aqqaluk, and Paalaaq), other shale-hosted deposits near Red Dog, and Zn-Pb-Ag sulfide and barite deposits in the western and central Brooks Range. The Red Dog deposits and other shale-hosted Zn-Pb-Ag deposits near Red Dog are hosted in the Mississippian Kuna Formation, which is underlain by a sequence of marine-deltaic clastic rocks of the Upper Devonian to Lower Mississippian Endicott Group. Ag-Pb-Zn vein-breccias are found in the Endicott Group. Galena formed during the main mineralization stages in the Red Dog deposits and from the Anarraaq and Wulik deposits have overlapping Pb isotope compositions in the range 206Pb/204Pb = 18.364 to 18.428, 207Pb/204Pb = 15.553 to 15.621, and 208Pb/204Pb = 38.083 to 38.323. Galena and sphalerite formed during the main ore-forming stages in the Red Dog deposits define a narrow field on standard uranogenic and thorogenic Pb isotope diagrams. Lead in sulfides of the Red Dog district is less radiogenic (238U/204Pb: ?? = 9.51-9.77) than is indicated by the average crustal lead evolution model (?? = 9.74), a difference consistent with a long history of evolution at low ratios of ?? before the Carboniferous. The homogeneous regional isotopic reservoir of Pb may indicate large-scale transport and leaching of minerals with various ?? ratios and Th/Pb ratios. Younger and genetically unrelated fluids did not significantly disturb the isotopic compositions of galena and sphalerite after the main mineralization event in the Red Dog district. Some pyrite shows evidence of minor Pb remobilization. The overall lead isotope homogeneity in the shale-hosted massive sulfide deposits is consistent with three types of control: a homogeneous regional source, mixing of lead during leaching of a thick sedimentary section and fluid transport, or mixing at the site of deposition. Isotopic variability of the hydrothermal fluids, as represented by galena

  17. Re-Os sulfide geochronology of the Red Dog sediment-hosted Zn-Pb-Ag deposit, Brooks Range, Alaska

    Morelli, R.M.; Creaser, R.A.; Selby, D.; Kelley, K.D.; Leach, D.L.; King, A.R.


    The Red Dog sediment-hosted deposit in the De Long Mountains of northern Alaska is the largest Zn producer in the world. Main stage mineralization is characterized by massive sulfide ore and crosscutting subvertical veins. Although the vein mineralization is clearly younger than the massive ore, the exact temporal relationship between the two is unclear. Re-Os geochronology of pyrite is used to determine the absolute age of main stage ore at Red Dog. A 10-point isochron on both massive and vein pyrite yields an age of 338.3 ?? 5.8 Ma and is interpreted to represent the age of main stage ore. The Re-Os data indicate that both massive and vein ore types are coeval within the resolution of the technique. Formation of the Red Dog deposit was associated with extension along a passive continental margin, and therefore the Re-Os age of main stage ore constrains the timing of rifting as well as the age of the host sedimentary rocks. Sphalerite from both massive and vein ore yields imprecise ages and shows a high degree of scatter compared to pyrite. We suggest that the Re-Os systematics of sphalerite can be disturbed and that this mineral is not reliable for Re-Os geochronology. ?? 2004 by Economic Geology.

  18. Sulfur and oxygen isotopic study of Paleozoic sediment-hosted Zn-Pb(-Ag-Au-Ba-F) deposits and associated hydrothermal alteration zones in the Nome Complex, Seward Peninsula, Alaska

    Shanks, W.C. Pat; Slack, John F.; Till, Alison B.; Thurston, Roland; Gemery-Hill, Pamela


    Results of sulfur and oxygen isotope studies of sedimentary exhalative (SEDEX) Zn-Pb(-Ag-Au-Ba-F) deposits hosted in metamorphosed Paleozoic clastic and carbonate rocks of the Nome Complex, Seward Peninsula, Alaska, are consistent with data for similar deposits worldwide. Stable isotopic studies of the Nome Complex are challenging because the rocks have undergone Mesozoic blueschist- and greenschist-facies metamorphism and deformation at temperatures estimated from 390–490 °C. Studies of sulfur and oxygen isotopes in other areas suggest that, in the absence of chemical and mineralogical evidence for metasomatism, the principal effect of metamorphism is re-equilibration between individual minerals at the temperature of metamorphism, which commonly leads to a narrowing of the overall range of isotope values for a suite of rocks, but generally does not significantly modify the average whole rock value for that suite. Sulfur isotope studies of the stratabound and locally stratiform sulfide lenses at the Aurora Creek-Christophosen deposit, which is of possible Late Devonian-early Carboniferous age, show a large range of δ34Ssulfide values from -9.7 to 39.4‰, suggesting multiple sulfur sources and possibly complex processes of sulfide formation that may include bacterial sulfate reduction, thermochemical sulfate reduction, and Rayleigh distillation. Low δ34S values probably represent bacterial sulfide minerals remobilized from the host metasedimentary rocks either during the original seafloor mineralization or are related to a Cretaceous mineralizing event that produced Au-vein and base-metal replacement deposits; the latter process is supported by Pb isotope data. The Wheeler North deposit is similar to Aurora Creek-Christophosen but does not have negative δ34S values. It also probably formed in an euxinic sub-basin.

  19. Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: Implications for Ore Formation

    Kelley, K.D.; Leach, D.L.; Johnson, C.A.; Clark, J.L.; Fayek, M.; Slack, J.F.; Anderson, V.M.; Ayuso, R.A.; Ridley, W.I.


    The Red Dog Zn-Pb deposits are hosted in organic-rich mudstone and shale of the Mississippian Kuna Formation. A complex mineralization history is defined by four sphalerite types or stages: (1) early brown sphalerite, (2) yellow-brown sphalerite, (3) red-brown sphalerite, and (4) late tan sphalerite. Stages 2 and 3 constitute the main ore-forming event and are volumetrically the most important. Sulfides in stages 1 and 2 were deposited with barite, whereas stage 3 largely replaces barite. Distinct chemical differences exist among the different stages of sphalerite. From early brown sphalerite to later yellow-brown sphalerite and red-brown sphalerite, Fe and Co content generally increase and Mn and Tl content generally decrease. Early brown sphalerite contains no more than 1.9 wt percent Fe and 63 ppm Co, with high Mn (up to 37 ppm) and Tl (126 ppm), whereas yellow-brown sphalerite and red-brown sphalerite contain high Fe (up to 7.3 wt %) and Co (up to 382 ppm), and low Mn (subsea-floor hydrothermal recrystallization and coarsening of preexisting barite; (3) open-space deposition of barite, red-brown sphalerite and other sulfides in veins and coeval replacement of barite; and (4) postore sulfide deposition, including the formation of late tan sphalerite breccias. Stage 1 mineralization took place in a low-temperature environment where fluids rich in Ba mixed with pore water or water-column sulfate to form barite, and metals combined with H2S derived from bacterial sulfate reduction to form sulfides. Higher temperatures and salinities and relatively oxidized ore-stage fluids (stages 2 and 3) compared with stage 1 were probably important controls on the abundances and relative amounts of metals in the fluids and the resulting sulfide chemistry. Textural observations and isotopic data show that preexisting barite was reductively dissolved, providing a source of H2S for sulfide mineral formation. In stage 3, the continued flow of hydrothermal fluids caused thermal

  20. Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-type Zn-Pb, sedimentary rock-hosted Stratiform Cu, and carbonate-hosted Polymetallic Deposits): A review: Chapter 12

    Marsh, Erin; Hitzman, Murray W.; Leach, David L.


    Some sediment-hosted base metal deposits, specifically the clastic-dominated (CD) Zn-Pb deposits, carbonate-hosted Mississippi Valley-type (MVT) deposits, sedimentary-rock hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, and Re. The generally poor data concerning trace element concentrations in these types of sediment-hosted ores suggest that there may be economically important concentrations of critical elements yet to be recognized.

  1. Fluids in distal Zn-Pb-Ag skarns: Evidence from El Mochito, Honduras

    Samson, I. M.; Williams-Jones, A. E.; Ault, K.; Gagnon, J. E.; Fryer, B. J.


    Zn-Pb-Ag mantos, chimneys, and skarns represent a spectrum of carbonate-hosted sulfide mineral deposits that have been collectively termed carbonate replacement deposits. Most such deposits cannot be related to plutons and, particularly for distal skarns, the role of magmatic versus other fluids (basinal brines and meteoric waters) has been uncertain. The El Mochito Zn-Pb-Ag deposit, Honduras, is an example of a large distal skarn, and comprises mantos and chimneys hosted mainly by limestones of the Early Cretaceous Tepemechin Formation. Previous isotopic studies indicate a magmatic source for the S and Pb and involvement of both magmatic and meteoric fluids in ore formation. The ore is hosted by garnet, magnetite, and pyroxene skarns, which developed sequentially from grandite- to andradite- to magnetite- and hedenbergite- rich skarns. Sphalerite and argentiferous galena occur interstitially to, or replace, the skarn minerals, with Fe- poor sphalerite (S1) principally associated with garnet skarn and Fe-rich (S2) sphalerite associated with pyroxene. Data from primary fluid inclusions show that the salinity of the mineralizing fluids decreased from ˜10-18 wt. % during the formation of garnet skarn and S1 sphalerite to ˜2-13 wt. % during pyroxene skarn formation and S2 sphalerite precipitation. Early, high-salinity fluids (˜33 wt. %) are represented by rare halite-saturated inclusions in garnet. Temperature increased from ˜ 365°C to ˜ 365°C from garnet/S1 sphalerite to pyroxene/S2 sphalerite, assuming a pressure of 500 bars. GC analyses indicate that the total concentrations of COv(2), CH4, and N2 were < 1 mole %. LA-ICPMS analyses were conducted mainly on inclusions in grandite and S1 sphalerite. The principal dissolved elements in the inclusions are Ca and Na, followed by K and Mn. The ore metals, Zn, Pb, and Ag, are present in high concentrations, with median values of 6000, 900, and 50 ppm, respectively. Element concentrations in fluid inclusions hosted

  2. Fluid Inclusions of Calcite and Sources of Ore-forming Fluids in the Huize Zn-Pb-(Ag-Ge) District, Yunnan, China

    HAN Runsheng; LIU Congqiang; HUANG Zhilong; MA Deyun; LI Yuan; HU Bin; MA Gengsheng; LEI Li


    The Huize Zn-Pb- (Ag-Ge) district is a typical representative of the well-known medium-to large-sized carbonate-hosted Zn-Pb- (Ag-Ge) deposits, occurring in the Sichuan-Yunnan-Guizhou Pb-Zn Ore-forming Zone.Generally, fluid inclusions within calcite, one of the major gangue minerals, are dominated by two kinds of small (1-10μm) inclusions including pure-liquid and liquid. The inclusions exist in concentrated groups along the crystal planes of the calcite. The ore-forming fluids containing Pb and Zn, which belong to the Na+-K+-Ca2+-C1--F--SO42- type, are characterized by temperatures of 164-221 ℃, medium salinity in 5-10.8 wt% NaCl, and medium pressure at 410xl0s to 661 x 10s Pa. The contents of Na+-K+ and Cl--F-, and ratios of Na+/K+-Cl-/F- in fluid inclusions present good linearity. The ratios of Na+/K+ (4.66-6.71) and C1-/F- (1 8.21-31.04) in the fluid inclusions of calcite are relatively high, while those of Na+/K+ (0.29-5.69) and Cl-/F- (5.00-26.0) in the inclusions of sphalerite and pyrite are relatively low. The ratio of Na+/K+increases in accord with those of C1-/F, which indicates that ore-forming fluid of deep source participates in the mineralization. The waters of fluid inclusions have δD values from -43.5‰ to -55.4‰ of calcite. The δ18Ov-sMow values of the ore-forming fluids, calculated values, range from 17.09‰ to 18.56‰ of calcite and 17.80‰ to 23.14‰ for dolomite.δ13 Cv-PDB values range from -1.94‰ to -3.31‰ for calcite and -3.35‰ to 0.85‰ for the ore-bearing dolomite. These data better demonstrate that the ore-forming fluids were mainly derived from metamorphic water and magmatic hot fluid, in relation to the metamorphism of the Kunyang Group in the basement and magmatic hydrothermalism. The deposit itself might have resulted from ascending cycles of ore-forming fluid, enriched in Pb and Zn. The Huize Zn-Pb- (Ag-Ge)deposits related to carbonate-hosted Zn-Pb sulphides.

  3. Timing of porphyry (Cu-Mo) and base metal (Zn-Pb-Ag-Cu) mineralisation in a magmatic-hydrothermal system—Morococha district, Peru

    Catchpole, Honza; Kouzmanov, Kalin; Bendezú, Aldo; Ovtcharova, Maria; Spikings, Richard; Stein, Holly; Fontboté, Lluís


    The Morococha district in central Peru is characterised by economically important Cordilleran polymetallic (Zn-Pb-Ag-Cu) vein and replacement bodies and the large Toromocho porphyry Cu-Mo deposit in its centre. U-Pb, Re-Os, and 40Ar/39Ar geochronology data for various porphyry-related hydrothermal mineralisation styles record a 3.5-Ma multi-stage history of magmatic-hydrothermal activity in the district. In the late Miocene, three individual magmatic-hydrothermal centres were active: the Codiciada, Toromocho, and Ticlio centres, each separated in time and space. The Codiciada centre is the oldest magmatic-hydrothermal system in the district and consists of a composite porphyry stock associated with anhydrous skarn and quartz-molybdenite veins. The hydrothermal events are recorded by a titanite U-Pb age at 9.3 ± 0.2 Ma and a molybdenite Re-Os age at 9.26 ± 0.03 Ma. These ages are indistinguishable from zircon U-Pb ages for porphyry intrusions of the composite stock and indicate a time span of 0.2 Ma for magmatic-hydrothermal activity. The small Ticlio magmatic-hydrothermal centre in the west of the district has a maximum duration of 0.3 Ma, ranging from porphyry emplacement to porphyry mineralisation at 8.04 ± 0.14 Ma (40Ar/39Ar muscovite cooling age). The Toromocho magmatic-hydrothermal centre has a minimum of five recorded porphyry intrusions that span a total of 1.3 Ma and is responsible for the formation of the giant Toromocho Cu-Mo deposit. At least two hydrothermal pulses are identified. Post-dating a first pulse of molybdenite mineralisation, wide-spread hydrous skarn covers an area of over 6 km2 and is recorded by five 40Ar/39Ar cooling ages at 7.2-6.8 Ma. These ages mark the end of the slowly cooling and long-lived Toromocho magmatic-hydrothermal centre soon after last magmatic activity at 7.26 ± 0.02 Ma. District-wide (50 km2) Cordilleran base metal vein and replacement bodies post-date the youngest recorded porphyry mineralisation event at Toromocho

  4. Dating of Mesoproterozoic metamorphism in the Mount Isa and George Fisher Zn-Pb-Cu-Ag deposits, Australia, by paleomagnetism

    Kawasaki, K.; Symons, D. T.


    The Mount Isa Zn-Pb-Cu-Ag and George Fisher Zn-Pb-Ag black-shale-hosted deposits in Queensland, Australia, are in carbonaceous and dolomitic shales of the ~1655 Ma Urquhart Formation of the Mount Isa Group that exhibit greenschist facies metamorphism. Both deposits give lead model ages of ~1655 Ma. Ar-Ar biotite and Re-Os ages for the Mount Isa copper ore are 1523±3 and 1372±4 Ma, respectively. Excluding modern hematite, paleomagnetic and rock magnetic analyses of 333 specimens (28 sites) isolate a stable characteristic remanent magnetization (ChRM) in single- and pseudosingle-domain pyrrhotite for the Zn-Pb-Ag ore specimens and in pyrrhotite and/or titanomagnetite for the Cu ore. A negative paleomagnetic fold test shows that the ChRM postdates D3 deformation of the ~1595 to 1500 Ma Isan orogeny, yielding a Mesoproterozoic paleopole at ~1505 Ma on the northern Australian apparent polar wander path. The ~1505 Ma age is similar to the ~1523 Ma Ar-Ar age and it provides a minimum age for ore genesis of both deposits, as well as the age for peak greenschist metamorphism during the Isan orogeny in the surrounding Mount Isa inlier.

  5. Jarosite versus Soluble Iron-Sulfate Formation and Their Role in Acid Mine Drainage Formation at the Pan de Azúcar Mine Tailings (Zn-Pb-Ag, NW Argentina

    Jesica Murray


    Full Text Available Secondary jarosite and water-soluble iron-sulfate minerals control the composition of acid mine waters formed by the oxidation of sulfide in tailings impoundments at the (Zn-Pb-Ag Pan de Azúcar mine located in the Pozuelos Lagoon Basin (semi-arid climate in Northwest (NW Argentina. In the primary zone of the tailings (9.5 wt % pyrite-marcasite precipitation of anglesite (PbSO4, wupatkite ((Co,Mg,NiAl2(SO44 and gypsum retain Pb, Co and Ca, while mainly Fe2+, Zn2+, Al3+, Mg2+, As3+/5+ and Cd2+ migrate downwards, forming a sulfate and metal-rich plume. In the oxidation zone, jarosite (MFe3(TO42(OH6 is the main secondary Fe3+ phase; its most suitable composition is M = K+, Na+, and Pb2+and TO4 = SO42−; AsO42−. During the dry season, iron-sulfate salts precipitate by capillary transport on the tailings and at the foot of DC2 (tailings impoundment DC2 tailings dam where an acid, Fe2+ rich plume outcrops. The most abundant compounds in the acid mine drainage (AMD are SO42−, Fe2+, Fe3+, Zn2+, Al3+, Mg2+, Cu2+, As3+/5+, Cd2+. These show peak concentrations at the beginning of the wet season, when the soluble salts and jarosite dissolve. The formation of soluble sulfate salts during the dry season and dilution during the wet season conform an annual cycle of rapid metals and acidity transference from the tailings to the downstream environment.

  6. Regional Fluid Flow and Basin Modeling in Northern Alaska

    Kelley, Karen D.


    INTRODUCTION The foothills of the Brooks Range contain an enormous accumulation of zinc (Zn) in the form of zinc sulfide and barium (Ba) in the form of barite in Carboniferous shale, chert, and mudstone. Most of the resources and reserves of Zn occur in the Red Dog deposit and others in the Red Dog district; these resources and reserves surpass those of most deposits worldwide in terms of size and grade. In addition to zinc and lead sulfides (which contain silver, Ag) and barite, correlative strata host phosphate deposits. Furthermore, prolific hydrocarbon source rocks of Carboniferous and Triassic to Early Jurassic age generated considerable amounts of petroleum that may have contributed to the world-class petroleum resources of the North Slope. Deposits of Zn-Pb-Ag or barite as large as those in the Brooks Range are very rare on a global basis and, accordingly, multiple coincident favorable factors must be invoked to explain their origins. To improve our understanding of these factors and to contribute to more effective assessments of resources in sedimentary basins of northern Alaska and throughout the world, the Mineral Resources Program and the Energy Resources Program of the U.S. Geological Survey (USGS) initiated a project that was aimed at understanding the petroleum maturation and mineralization history of parts of the Brooks Range that were previously poorly characterized. The project, titled ?Regional Fluid Flow and Basin Modeling in Northern Alaska,? was undertaken in collaboration with industry, academia, and other government agencies. This Circular contains papers that describe the results of the recently completed project. The studies that are highlighted in these papers have led to a better understanding of the following: *The complex sedimentary facies relationships and depositional settings and the geochemistry of the sedimentary rocks that host the deposits (sections 2 and 3). *The factors responsible for formation of the barite and zinc deposits

  7. A special issue devoted to gold deposits in northern Nevada: Part 2. Carlin-type Deposits

    Hofstra, Albert H.; John, David A.; Theodore, Ted G.


    This is the second of two special issues of Economic Geology devoted to gold deposits in northern Nevada. Readers interested in a general overview of these deposits, their economic significance, their context within the tectonic evolution of the region, and synoptic references on each gold deposit type are directed to the preface of the first special issue (John et al., 2003). Volume 98, issue 2, contains five papers that address regional aspects important to the genesis of gold deposits in northern Nevada and five papers that present detailed studies of epithermal deposits and districts. All of the regional papers are pertinent to Carlin-type gold deposits, because they address the age of mineralization (Arehart et al., 2003), origin and evolutionary history of the northwest-striking mineral belts that localize many deposits (Grauch et al., 2003), nature of the middle and lower crust below these mineral belts (Howard, 2003), district- to deposit-scale stream sediment and lithogeochemical anomalies (Theodore et al., 2003), and stratigraphy and structure of a district located along a northeast-striking lineament (Peters et al., 2003).

  8. Holocene tephra deposits in the northern Okinawa Trough


    The mineralogical and geochemical characteristics of sediments of Core CSH1, which was collected from the northern Okinawa Trough, indicate that large amounts of volcanic materials have deposited in the northern Okinawa Trough during the Holocene. On the basis of down-core variations in mineral and element contents of sediments, two layers in the uppermost section of Core CSH1 characterized by high quartz, Na2O, MnO, K2O, uranium contents and low contents of clay minerals, volatiles, Fe2O3, MgO, CaO and strontium, have been identified as the tephra deposits. Systematic grain-size measurements also suggest that sediments from the northern Okinawa Trough are made up of terrigenous materials and volcanic ashes with different proportion during the Holocene. The sediments of tephra layers in Core CSH1 show bi-modal patterns in grain-size distribution with modal grain-sizes of 74.3 and 7.81 μm,respectively. According to the radiocarbon dating on shells of zooplankton foraminifera, two tephra layers in Core CSH1, formed at 7 250 and 10 870 a BP (cal), approximately correspond to the K-Ah tephra [7 300 a BP (cal)] and the eruption of Kuju Volcano (12~10 ka BP), respectively.

  9. Geotechnical problems related with loess deposits in Northern France

    Delage, Pierre; Antoine, Pierre


    Special problems were encountered in some areas in Northern France where the high speed railways (TGV Nord) crossed some loess deposits that appeared to be specially sensitive to change in water content and susceptible to collapse. Numerous sinkholes appeared along some sections of the line following wet climatic periods. After a general geological and geotechnical presentation of loess deposits and collapse susceptibility, in which some tools of the mechanics of unsaturated soils are reconsidered with special application to loess collapsibility, this paper describes the results of a geotechnical study carried out on block samples of intact loess. Collapse susceptibility is examined in the light of microstructure observation. The dependence of collapse to water content changes is examined and the validity of various existing collapse criteria is investigated.

  10. Gigantic landslides versus glacial deposits: on origin of large hummock deposits in Alai Valley, Northern Pamir

    Reznichenko, Natalya


    As glaciers are sensitive to local climate, their moraines position and ages are used to infer past climates and glacier dynamics. These chronologies are only valid if all dated moraines are formed as the result of climatically driven advance and subsequent retreat. Hence, any accurate palaeoenvironmental reconstruction requires thorough identification of the landform genesis by complex approach including geomorphological, sedimentological and structural landform investigation. Here are presented the implication of such approach for the reconstruction of the mega-hummocky deposits formation both of glacial and landslide origin in the glaciated Alai Valley of the Northern Pamir with further discussion on these and similar deposits validity for palaeoclimatic reconstructions. The Tibetan Plateau valleys are the largest glaciated regions beyond the ice sheets with high potential to provide the best geological record of glacial chronologies and, however, with higher probabilities of the numerous rock avalanche deposits including those that were initially considered of glacial origin (Hewitt, 1999). The Alai Valley is the largest intermountain depression in the upper reaches of the Amudarja River basin that has captured numerous unidentified extensive hummocky deposits descending from the Zaalai Range of Northern Pamir, covering area in more than 800 km2. Such vast hummocky deposits are usually could be formed either: 1) glacially by rapid glacial retreat due to the climate signal or triggered a-climatically glacial changes, such as glacial surge or landslide impact, or 2) during the landslide emplacement. Combination of sediment tests on agglomerates forming only in rock avalanche material (Reznichenko et al., 2012) and detailed geomorphological and sedimentological descriptions of these deposits allowed reconstructing the glacial deposition in the Koman and Lenin glacial catchments with identification of two gigantic rock avalanches and their relation to this glacial

  11. Catastrophic debris avalanche deposit of Socompa volcano, northern Chile

    Francis, P. W.; Gardeweg, M.; Ramirez, C. F.; Rothery, D. A.


    Between 10,000 and 500 yr ago the Socompa volcano in northern Chile experienced a catastrophic collapse of a 70 deg sector of the original cone, causing a debris avalanche that descended nearly 3000 m vertically and traveled more than 35 km from the volcano. The deposits cover some 490 sq km and have a minimum volume of 15 cu km. Parts of the original cone slumped in a nearly coherent form and are now preserved as large blocks more than 400 m high. The primary avalanche traveled northwestward over sloping ground before coming to rest transiently, forming a prominent marginal ridge, and then slid away northeastward to form a secondary flow, overriding much of the primary avalanche deposit. Abundant, prismatic, jointed dacite blocks within the debris avalanche deposit and a thin, fine-grained pumiceous deposit beneath it suggest that the collapse was triggered by magmatic activity and may have been accompanied by a violent lateral blast. Collapse was followed by eruption of pumiceous pyroclastic flows and extrusion of voluminous dacite domes.

  12. Northern bobwhite and lead shot deposition in an upland habitat.

    Keel, M K; Davidson, W R; Doster, G L; Lewis, L A


    We estimated total lead shotshell pellets expended, resultant pellet availability near soil surface, and the frequency of pellet ingestion by northern bobwhites ( Colinus virginianus) attributable to nearly a quarter century of bobwhite hunting on a 202-ha upland habitat at Tall Timbers Research Station, Leon County, Florida. A total of 7776 shots were fired, resulting in the expenditure of approximately 4.5 million pellets (approximately 22519/ha). Sixteen of 235 (6.8%) soil samples collected in 1989 and 1992 contained one or two pellets. Soil samples indicated that approximately 7800 pellets/ha (about 35% of the projected 24-year deposition) were within 2.54 cm of the soil surface. Pellet ingestion by bobwhites was evaluated by examining 241 gizzards collected from 1989-92. Three bobwhites (1.3%) had ingested pellets ( x = 1.3 pellets). No instances of suspected lead poisoning were noted in bobwhites over the 24-year period. Sport hunting of wild bobwhite populations on upland habitats appears to produce a low potential for lead poisoning compared to lead deposition in association with waterfowl and dove hunting.

  13. Ammonia sources, transport, and deposition in northern Colorado

    Collett, J. L., Jr.; Benedict, K. B.; Li, Y.; Shao, Y.; Wentworth, G.; Sullivan, A.; Evanoski-Cole, A. R.; Bangs, E.; Murphy, J. G.; Schichtel, B. A.


    Expanded measurements of ammonia in northern Colorado are providing new insight into ammonia sources in the region, their spatial variability, and their contributions to reactive nitrogen deposition in sensitive regions such as Rocky Mountain National Park (RMNP). Regional ammonia concentrations have been examined through a combination of a passive ammonia monitoring network, through mobile measurements, and through an east-west transect of real-time ammonia monitors stretching from the agricultural source region of NE Colorado through the Rocky Mountain foothills west of the Front Range urban corridor, to Rocky Mountain National Park. Several years of ammonia observations in NE Colorado reveal considerable concentration variability, with the highest concentrations observed near animal feeding observations. Multi-year concentration increases have been observed at some locations and significant decreases at other locations, but most sites exhibit no significant long-term trends. Ammonia concentrations in RMNP are strongly influenced by episodic transport from ammonia-rich NE Colorado, but an imprtant influence is also observed from wildfire emissions. Local recylcing of boundary layer ammonia through formation and evaporation of dew also exerts a strong influence on local concentrations, a phenomenon that has received little prior attention.

  14. Wet and dry deposition of atmospheric nitrogen at ten sites in Northern China

    Y. P. Pan


    Full Text Available Emissions of reactive nitrogen (N species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three-year average of 60.6 kg N ha−1 yr−1. The deposition levels showed spatial and temporal variation in the range of 28.5–100.4 kg N ha−1 yr−1. Of the annual total deposition, 40% was deposited via precipitation, and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NO3 to N deposition was enhanced in certain urban and industrial areas. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. The results have three important implications. First, atmospheric N deposition in Northern China falls within the range of critical loads for temperate forests and grasslands, a threshold above which harmful ecological effects to specified parts of temperate ecosystems often

  15. Nitrogen deposition enhances carbon sequestration by plantations in northern China.

    Du, Zhihong; Wang, Wei; Zeng, Wenjing; Zeng, Hui


    Nitrogen (N) deposition and its ecological effects on forest ecosystems have received global attention. Plantations play an important role in mitigating climate change through assimilating atmospheric CO2. However, the mechanisms by which increasing N additions affect net ecosystem production (NEP) of plantations remain poorly understood. A field experiment was initialized in May 2009, which incorporated additions of four rates of N (control (no N addition), low-N (5 g N m⁻² yr⁻¹), medium-N (10 g N m⁻² yr⁻¹), and high-N (15 g N m⁻² yr⁻¹) at the Saihanba Forestry Center, Hebei Province, northern China, a locality that contains the largest area of plantations in China. Net primary production (NPP), soil respiration, and its autotrophic and heterotrophic components were measured. Plant tissue carbon (C) and N concentrations (including foliage, litter, and fine roots), microbial biomass, microbial community composition, extracellular enzyme activities, and soil pH were also measured. N addition significantly increased NPP, which was associated with increased litter N concentrations. Autotrophic respiration (AR) increased but heterotrophic respiration (HR) decreased in the high N compared with the medium N plots, although the HR in high and medium N plots did not significantly differ from that in the control. The increased AR may derive from mycorrhizal respiration and rhizospheric microbial respiration, not live root respiration, because fine root biomass and N concentrations showed no significant differences. Although the HR was significantly suppressed in the high-N plots, soil microbial biomass, composition, or activity of extracellular enzymes were not significantly changed. Reduced pH with fertilization also could not explain the pattern of HR. The reduction of HR may be related to altered microbial C use efficiency. NEP was significantly enhanced by N addition, from 149 to 426.6 g C m⁻² yr⁻¹. Short-term N addition may significantly enhance

  16. Saharan dust transport and deposition towards the Tropical Northern Atlantic

    K. Schepanski


    Full Text Available We present a study of Saharan dust export towards the tropical North Atlantic using the regional dust emission, transport and deposition model LM-MUSCAT. Horizontal and vertical distribution of dust optical thickness, concentration, and dry and wet deposition rates are used to describe seasonality of dust export and deposition towards the eastern Atlantic for three exemplary months in different seasons. Deposition rates strongly depend on the vertical dust distribution, which differs with seasons. Furthermore the contribution of dust originating from the Bodélé Depression to Saharan dust over the Atlantic is investigated. A maximum contribution of Bodélé dust transported towards the Cape Verde Islands is evident in winter when the Bodélé source area is most active and dominant with regard activation frequency and dust emission. Limitations of using satellite retrievals to estimate dust deposition are highlighted.

  17. Hydrothermal zebra dolomite in the Great Basin, Nevada--attributes and relation to Paleozoic stratigraphy, tectonics, and ore deposits

    Diehl, S.F.; Hofstra, A.H.; Koenig, A.E.; Emsbo, P.; Christiansen, W.; Johnson, Chad


    In other parts of the world, previous workers have shown that sparry dolomite in carbonate rocks may be produced by the generation and movement of hot basinal brines in response to arid paleoclimates and tectonism, and that some of these brines served as the transport medium for metals fixed in Mississippi Valley-type (MVT) and sedimentary exhalative (Sedex) deposits of Zn, Pb, Ag, Au, or barite. Numerous occurrences of hydrothermal zebra dolomite (HZD), comprised of alternating layers of dark replacement and light void-filling sparry or saddle dolomite, are present in Paleozoic platform and slope carbonate rocks on the eastern side of the Great Basin physiographic province. Locally, it is associated with mineral deposits of barite, Ag-Pb-Zn, and Au. In this paper the spatial distribution of HZD occurrences, their stratigraphic position, morphological characteristics, textures and zoning, and chemical and stable isotopic compositions were determined to improve understanding of their age, origin, and relation to dolostone, ore deposits, and the tectonic evolution of the Great Basin. In northern and central Nevada, HZD is coeval and cogenetic with Late Devonian and Early Mississippian Sedex Au, Zn, and barite deposits and may be related to Late Ordovician Sedex barite deposits. In southern Nevada and southwest California, it is cogenetic with small MVT Ag-Pb-Zn deposits in rocks as young as Early Mississippian. Over Paleozoic time, the Great Basin was at equatorial paleolatitudes with episodes of arid paleoclimates. Several occurrences of HZD are crosscut by Mesozoic or Cenozoic intrusions, and some host younger pluton-related polymetallic replacement and Carlin-type gold deposits. The distribution of HZD in space (carbonate platform, margin, and slope) and stratigraphy (Late Neoproterozoic Ediacaran-Mississippian) roughly parallels that of dolostone and both are prevalent in Devonian strata. Stratabound HZD is best developed in Ediacaran and Cambrian units, whereas

  18. Mineralogy of the Santa Fe Tin deposit, Bolivia

    Jiménez-Franco, Abigail; Alfonso, Pura; Canet, Carles; Garcia-Valles, Maite; Elvys Trujillo, Juan


    Santa Fe is a Sn-Zn-Pb-Ag ore deposit located in the Oruro district, Central Andean Tin Belt, Bolivia. Mineralization occurs in veins and disseminations. It is hosted in Silurian shales and greywackes. The sedimentary sequence is folded and unconformably covered by a volcanic complex of the Morococala Formation, mainly constituted by tuffs of Miocene age. A wide Nº40 shear zone and two systems of fracture are developed. A Nº40 fracture system, dipping 60ºW, which hosts Sn and Zn minerals, and other in the same direction but dipping 75ºE, which is related to Zn-Pb-Ag veins. The mineralization is associated to intrusive felsic magmatism. Although there are not intrusive rocks in Santa Fe, a dyke and the felsic San Pablo stock occur at a distance of about 10 km. In the present work we describe the geology and mineralogy of the Santa Fe deposit. X-ray diffraction, scanning electron microscopy and electron microprobe analyses were used to characterize the minerals. Veins are filled with quartz and an ore mineral assemblage of cassiterite, sulfides and sulfosalts. Cassiterite constitutes the earliest formed mineralization. Preliminar microprobe analyses indicate that it is nearly pure, with negligible contents in Nb and Ta. Rutile occurs as a late phase associated with a late generation of cassiterite. It forms thin neddle-like crystals. In addition, Sn is also present in sulfides as stannite, stannoidite and kësterite. Other sulfides are pyrrhotite, pyrite, arsenopyrite, galena, sphalerite, marchasite and argentite. Bismuthinite and berndite are found nin trace amounts. Sulfosalts include tetrahedrite, myarhyrite, boulangerite, jamesonite, franckeite, zinckenite, cilindrite and andorite. Associated with the mineralization, several phosphate minerals are found filling cavities and small fractures. The most abundant are monacite (Ce,La,Nd,Th)PO4 and plumbogummite (PbAl3(PO4)2(OH)5•(H2O)). Crandallite CaAl3(PO4)2(OH)5•(H2O) and vivianite (Fe3+(PO4)2•8(H2O)) also

  19. Biomass burning in eastern Europe during spring 2006 caused high deposition of ammonium in northern Fennoscandia

    Karlsson, Per Erik; Ferm, Martin; Pihl Karlsson, Gunilla


    High air concentrations of ammonium were detected at low and high altitude sites in Sweden, Finland and Norway during the spring 2006, coinciding with polluted air from biomass burning in eastern Europe passing over central and northern Fennoscandia. Unusually high values for throughfall deposition...

  20. Submarine fans and associated deposits in the lower Tertiary of Guipuzcoa (Northern Spain)

    Vliet, van A.


    The Lower Tertiary outcrop along the coast of Guipuzcoa, northern Spain, consists exclusively of deep-marine sediments, deposited in a narrow elongated (ESE-WNW) basin. The early Tertiary sedimentary history of this basin can be described in terms of three main phases:- a phase of predominantly (hem

  1. Geology and depositional environments of the Guadalupian rocks of the northern Del Norte Mountains, West Texas

    Rudine, S.F.; Wardlaw, B.R.; Rohr, D.M.; Grant, R.E.


    The Guadalupian rocks of the northern Del Norte Mountains were deposited in a foreland basin between land of the Marathon orogen and a carbonate shoal established on the geanticline separating the foreland basin from the Delaware basin. Deposition was alternately influenced by coarse clastic input from the orogen and carbonate shoal, which interrupted shallow basinal siltstone depletion. Relatively deeper-water deposition is characterized by carbonate input from the shoal, and relatively shallow-water deposition is characterized by sandstone input from the orogen. Deposition was in five general transgressive-regressive packages that include (1) the Road Canyon Formation and the first siltstone member and first sandstone member of the Word Formation, (2) the second siltstone member, Appel Ranch Member, and limy sandy siltstone member of the Word Formation, (3) the Vidrio Formation, (4) the lower and part of the middle members of the Altuda Formation, and (5) part of the middle and upper members of the Altuda Formation.

  2. Atmospheric wet and dry deposition of trace elements at 10 sites in Northern China

    Pan, Y. P.; Wang, Y. S.


    Atmospheric deposition is considered to be a major process that removes pollutants from the atmosphere and an important source of nutrients and contaminants for ecosystems. Trace elements (TEs), especially toxic metals deposited on plants and into soil or water, can cause substantial damage to the environment and human health due to their transfer and accumulation in food chains. Despite public concerns, quantitative knowledge of metal deposition from the atmosphere to ecosystems remains scarce. To advance our understanding of the spatiotemporal variations in the magnitudes, pathways, compositions and impacts of atmospherically deposited TEs, precipitation (rain and snow) and dry-deposited particles were collected simultaneously at 10 sites in Northern China from December 2007 to November 2010. The measurements showed that the wet and dry depositions of TEs in the target areas were orders of magnitude higher than previous observations within and outside China, generating great concern over the potential risks. The spatial distribution of the total (wet plus dry) deposition flux was consistent with that of the dry deposition, with a significant decrease from industrial and urban areas to suburban, agricultural and rural sites, while the wet deposition exhibited less spatial variation. In addition, the seasonal variation of wet deposition was also different from that of dry deposition, although they were both governed by the precipitation and emission patterns. For the majority of TEs that exist as coarse particles, dry deposition dominated the total flux at each site. This was not the case for potassium, nickel, arsenic, lead, zinc, cadmium, selenium, silver and thallium, for which the relative importance between wet and dry deposition fluxes varied by site. Whether wet deposition is the major atmospheric cleansing mechanism for the TEs depends on the size distribution of the particles. We found that atmospheric inputs of copper, lead, zinc, cadmium, arsenic and

  3. Spatial distribution and seasonal variations of atmospheric sulfur deposition over Northern China

    Pan, Y. P.; Wang, Y. S.; Tang, G. Q.; Wu, D.


    The increasing anthropogenic emissions of acidic compounds have induced acid deposition accompanied by acidification in the aquatic and terrestrial ecosystems worldwide. However, comprehensive assessment of spatial patterns and long-term trends of acid deposition in China remains a challenge due to a paucity of field-based measurement data, in particular for dry deposition. Here we quantify the sulfur (S) deposition on a regional scale via precipitation, particles and gases during a 3-yr observation campaign at ten selected sites in Northern China. Results show that the total S deposition flux in the target area ranged from 35.0 to 100.7 kg S ha-1 yr-1, categorized as high levels compared to those documented in Europe, North America, and East Asia. The ten-site, 3-yr average total S deposition was 64.8 kg S ha-1 yr-1, with 32% attributed to wet deposition, and the rest attributed to dry deposition. Compared with particulate sulfate, gaseous SO2 was the major contributor of dry-deposited S, contributing approximately 49% to the total flux. Wet deposition of sulfate showed pronounced seasonal variations with maximum in summer and minimum in winter, corresponding to precipitation patterns in Northern China. However, the spatial and inter-annual differences in the wet deposition were not significant, which were influenced by the precipitation amount, scavenging ratio and the concentrations of atmospheric S compounds. In contrast, the relatively large dry deposition of SO2 and sulfate during cold season, especially at industrial areas, was reasonably related to the local emissions from home heating. Although seasonal fluctuations were constant, clear spatial differences were observed in the total S deposition flux and higher values were also found in industrial areas with huge emissions of SO2. These findings indicate that human activity has dramatically altered the atmospheric S deposition and thus regional S cycles. To systematically illustrate the potential effects

  4. Characteristics of gold deposits in northern Sonora, Mexico: a preliminary report

    Silberman, M.L.; Giles, D.A.; Graubard, C.


    The complex geology of northern Sonora has a variety of environments suitable for gold mineralisation, and many of the gold prospects occur within or adjacent to the southwestern boundary of the megashear in Precambrian, Mesozoic and Tertiary rocks. The characteristics types of gold deposits have been delineated by reconnaissance field investigations of the authors. There are four main environments of lode gold deposits present in Sonora: epithermal veins and breccias; discontinuous quartz veins; structurally controlled Au; and carbonate sedimentary-hosted disseminated Au. -after Authors

  5. Geochemical Characteristics of the Sandstone—type Uranium Deposits in Northern Sichuan Province

    王旺章; 张筑凤


    Described in detail in this paper are the geochemical characteristics of the sandstone-type uranium deposits in northern Sichuan Province .Favorable and unfavor-able conditions for the enrichment of uranium are explored on the basis of the elemental abundances and ratios of U,Th and K determined by gamma-ray spectroscopy. Gamma-ray spectroscopic(U, Th and K) and XRF analyses(As, Ba) are helpful to distinguish U-bearing light-colored sandstones from U-barren light-colored ones and red sandstones (red claystone) from light-colored sandstones. Therefore, the favorable target area for prospecting the sandstone-type uranium deposits can be difined in northern Sichuan Province.

  6. Geochemistry and petrology of the most recent deposits from Cotopaxi volcano, Northern Volcanic Zone, Ecuador.


    Cotopaxi volcano is located in the Northern Volcanic Zone of the South American Andes. Pyroclastic deposits and lava flows from Cotopaxi comprise basaltic andesites, andesites and rhyolites that have erupted since 13 200 years BP. Nine rhyolite eruptions were produced in at least five separate events, punctuated by intermittent andesite eruptions. High La/Yb (>5) and 230Th excesses in the andesites are consistent with equilibration of magma with garnet-bearing lower crust or mantle, and numer...

  7. Unconformity-related uranium deposits, Athabasca area, Saskatchewan, and East Alligator Rivers area, Northern Territory, Australia

    Clark, L.A.; Burrill, G.H.R. (Saskatchewan Mining Development Corp., Saskatoon (Canada))


    Most unconformity-type uranium deposits in Saskatchewan occur within a few tens of metres above and/or below the basal unconformity of the 1.45 b.y. Athabasca Sandstone. Graphitic basement rocks coincident with post-Athabasca faulting or brecciation at or near the unconformity are important in localizing uranium deposits which form as tabular, ribbon-like bodies with grades averaging over 2 percent uranium and containing up to 50,000 tonnes U/sub 3/O/sub 8/. Some of these deposits have similar contents of nickel and arsenic. In the genetic model used to explain these deposits, traces of uranium were leached from the sandstone and basement rocks by oxidized formation waters. A thick clay regolith absorbed uranium from the solution, and the fixed uranium was reduced through an indirect reaction with graphite. The clay mineral surfaces were thus continuously cleared to allow further adsorption. Fluid convection was induced by topographic relief and/or crustal heating from radioactive decay, and would continue uranium deposition until all permeability was plugged by minerals. The East Alligator Rivers uranium deposits in Northern Territory, Australia occur within Middle Proterozoic quartz-chlorite and quartz-muscovite schists overlain by sandstone. Highest grades occur in silicified breccias where carbonate beds were leached out. Mineralization ages are both pre- and post-Kombolgie Sandstone, but, to date, no significant uranium mineralization has been found in the sandstone. There are many similarities with Saskatchewan deposits, but also important differences.

  8. [Effects of simulated nitrogen deposition on soil respiration in northern subtropical deciduous broad-leaved forest].

    Hu, Zheng-hua; Li, Han-mao; Yang, Yan-ping; Chen, Shu-tao; Li, Cen-zi; Shen, Shuang-he


    To investigate the effects of elevated nitrogen deposition on forest soil respiration, a simulated nitrogen deposition field experiment was conducted in northern subtropical deciduous broad-leave forest from April 2008 to April 2009. Nitrogen treatments included the control (no N addition, CK), low-N [50 kg x (hm2 x a)(-1), T(L)], medium-N [100 kg x (hm2 x a)(-1), T(M)], and high-N [150 kg x (hm2 x a)(-1), T(H)]. The respiration rates were measured by a static chamber-gas chromatograph method. Results showed that nitrogen deposition did not change the seasonal and daily variation patterns of soil respiration. Compared to the control, T(L), T(M) and T(H) treatments reduced soil annual average respiration rates by 8.51%, 9.74% and 11.24%, respectively. Meanwhile, T(L), T(M) and T(H) treatments decreased daily average soil respiration rates by 4.42%, 11.09% and 12.17%, respectively. Significant relationship was found between soil respiration rate and soil temperature. The Q10 (temperature sensitivity coefficients) for soil respiration of CK, T(L), T(M), and T(H) treatments were 2.53, 3.22, 2.64 and 2.92, respectively. Our findings suggested that nitrogen deposition reduced soil respiration, and increased soil respiration temperature sensitivity in northern subtropical deciduous broad-leave forest.

  9. Estimating total nitrogen deposition in agroecosystems in northern China during the wheat cropping season

    Christie; PETER; Fangmeier; ANDREAS


    Atmospheric nitrogen (N) deposition has been poorly documented in northern China, an intensive agricultural and industrial region with large emissions of NHx and NOy. To quantify N deposition, total airborne N deposition was determined at three agricultural sites using a manual integrated total nitrogen input (ITNI) system during growth of winter wheat (Triticum aestivum L.) and Italian ryegrass (Lolium multiflorum Lam.) from September 2005 to May 2006. Total estimated N deposition averaged 54.9 and 43.2 kg N/hm2 across the three sites when wheat was grown to flowering and maturing, respectively. The average value was 50.2 kg N/hm2 when ryegrass was the indicator plant. Both indicator species gave similar total airborne N input results. The intermediate level of N supplied resulted in the highest N deposition, and the ratio of N acquired from deposition to total N content of the whole system decreased with increasing N supply to the roots. The contribution of atmospheric N to the total N content of the wheat and ryegrass sand culture systems ranged from 10% to 24%.

  10. Late Cenozoic surficial deposits and valley evolution of unglaciated northern New Jersey

    Stanford, S.D.


    Multiple alluvial, colluvial, and eolian deposits in unglaciated northern New Jersey, and the eroded bedrock surfaces on which they rest, provide evidence of both long-term valley evolution driven by sustained eustatic baselevel lowering and short-term filling and excavation of valleys during glacial and interglacial climate cycles. The long-term changes occur over durations of 106 years, the short-term features evolve over durations of 104 to 105 years. Direct glacial effects, including blockage of valleys by glacial ice and sediment, and valley gradient reversals induced by crustal depression, are relatively sudden changes that account for several major Pleistocene drainage shifts. After deposition of the Beacon Hill fluvial gravel in the Late Miocene, lowering of sea level, perhaps in response to growth of the Antarctic ice sheet, led to almost complete dissection of the gravel. A suite of alluvial, colluvial, and eolian sediments was deposited in the dissected landscape. The fluvial Bridgeton Formation was deposited in the Raritan lowland, in the Amboy-Trenton lowland, and in the Delaware valley. Following southeastward diversion of the main Bridgeton river, perhaps during Late Pliocene or Early Pleistocene glaciation, northeastward drainage was established on the inactive Bridgeton fluvial plain. About 30 to 45 m of entrenchment followed, forming narrow, incised valleys within which Late Pleistocene deposits rest. This entrenchment may have occurred in response to lowered sea level caused by growth of ice sheets in the northern hemisphere. Under periglacial conditions in the Middle and Late Pleistocene, valleys were partially filled with alluvium and colluvium. During interglacials slopes were stabilized by vegetation and the alluvial and colluvial valley-fill was excavated by gullying, bank erosion, and spring sapping. During Illinoian and late Wisconsinan glaciation, the lower Raritan River was diverted when glacial deposits blocked its valley, and the

  11. Sedimentary features of tsunami backwash deposits in a shallow marine Miocene setting, Mejillones Peninsula, northern Chile

    Cantalamessa, Gino; Di Celma, Claudio


    Miocene shoreface sandstones in the Caleta Herradura half-graben, northern Chile, contain an exceptionally coarse deposit that, based on sedimentologic and stratigraphic features, is regarded as having been laid down during a tsunami event by non-cohesive and sediment-laden subaqueous density flows. Interpretations of the principal sediment-depositing mechanisms effective in the tsunami surges rely largely on field observations of deposit geometry and internal sedimentary characteristics. This example comprises two erosively based sedimentation units that were probably deposited by successive waves in the tsunami wave train. The Lower Unit consists of a clast-supported, polymodal, boulder-bearing breccia composed mostly of angular clasts and fewer well-rounded clasts. Framework components are mostly chaotic but may also exhibit either inverse-to-normal grading or crude normal grading. Laterally, changes in characters of depositional facies are common and abrupt. The sand-sized, bioclastic-rich matrix is poorly sorted and very similar to the underlying lower shoreface bioclastic sandstone, implying that soft sediments eroded at the lower erosional surface contributed to the tsunami deposit. The bulk of the Upper Unit is a poorly sorted, breccia-bearing sandstone. Pebbles and cobbles are scattered, massive or normally graded. Sporadic outsized boulders, emplaced as debris fall deposits, may occur along the erosional base. An array of signatures, such as unusually coarse grain size in comparison to the surrounding deposits, erosional bases, the mixed sources of sediments, multiple erosional and depositional events, normal size grading or massive texture, are all considered distinctive features of tsunamigenic deposits. Backwash deposition is indicated by the incorporation within the tsunami deposits of sediments derived from mixed sources, such as angular clasts from nearby subaerial settings, rounded clasts reworked from beach gravels, and bioclastic sand eroded from

  12. Correlation between distribution and shape of VMS deposits and regional deformation patterns, Skellefte district, northern Sweden

    Bauer, Tobias E.; Skyttä, Pietari; Hermansson, Tobias; Allen, Rodney L.; Weihed, Pär


    The Skellefte district in northern Sweden is host to abundant volcanogenic massive sulphide (VMS) deposits comprising pyritic, massive, semi-massive and disseminated Zn-Cu-Au ± Pb ores surrounded by disseminated pyrite and with or without stockwork mineralisation. The VMS deposits are associated with Palaeoproterozoic upper crustal extension (D1) that resulted in the development of normal faults and related transfer faults. The VMS ores formed as sub-seafloor replacement in both felsic volcaniclastic and sedimentary rocks and partly as exhalative deposits within the uppermost part of the volcanic stratigraphy. Subsequently, the district was subjected to deformation (D2) during crustal shortening. Comparing the distribution of VMS deposits with the regional fault pattern reveals a close spatial relationship of VMS deposits to the faults that formed during crustal extension (D1) utilising the syn-extensional faults as fluid conduits. Analysing the shape and orientation of VMS ore bodies shows how their deformation pattern mimics those of the hosting structures and results from the overprinting D2 deformation. Furthermore, regional structural transitions are imitated in the deformation patterns of the ore bodies. Plotting the aspect ratios of VMS ore bodies and the comparison with undeformed equivalents in the Hokuroko district, Japan allow an estimation of apparent strain and show correlation with the D2 deformation intensity of the certain structural domains. A comparison of the size of VMS deposits with their location shows that the smallest deposits are not related to known high-strain zones and the largest deposits are associated with regional-scale high-strain zones. The comparison of distribution and size with the pattern of high-strain zones provides an important tool for regional-scale mineral exploration in the Skellefte district, whereas the analysis of ore body shape and orientation can aid near-mine exploration activities.

  13. Magnetic properties related to hydrothermal alteration processes at the Escondida porphyry copper deposit, northern Chile

    Riveros, K.; Veloso, E.; Campos, E.; Menzies, A.; Véliz, W.


    Fluid-rock interaction related to the circulation of hydrothermal fluids can strongly modify the physicochemical properties of wall rocks in porphyry Cu deposits. These processes can also produce compositional and textural changes in ferromagnetic minerals, which can be quantified using magnetic methods. In the Escondida porphyry Cu deposit of northern Chile, each hydrothermally altered lithology is characterized by a discrete assemblage of Fe-Ti oxide minerals. These minerals have distinctive bulk magnetic susceptibility ( K bulk), temperature-dependent magnetic susceptibility, and magnetic hysteresis parameters. Selectively altered rocks (i.e., potassic and chloritic alteration types) exhibit the highest K bulk values (>3.93 × 10-3 SI units), and their hysteresis parameters indicate multidomain magnetic mineral behavior. This suggests that these rocks are composed of the coarsest magnetic grain sizes within the deposit. Optical analyses and susceptibility-temperature curves confirm that the magnetic signals in selectively altered rocks are mainly carried by secondary magnetite. In contrast, pervasively altered rocks (i.e., quartz-sericite and argillic alteration types) exhibit low K bulk values (hydrothermal alteration processes, Fe-Ti oxide minerals, and magnetic properties of the wall rock in the Escondida deposit. These magnetic methods can be considered a sensitive and efficient petrophysical tool for the identification and semi-quantification of alteration assemblages, and facilitating the recognition and mapping of discrete hydrothermal zones during exploration and operation of porphyry Cu deposits.

  14. A modified approach for estimating the aquatic critical load of acid deposition in northern Saskatchewan, Canada

    Whitfield, Colin J.; Mowat, Aidan C.; Scott, Kenneth A.; Watmough, Shaun A.


    Acid-sensitive ecosystems are found in northern Saskatchewan, which lies downwind of major sulphur (S) and nitrogen (N) emissions sources associated with the oil sands extraction industry. In order to protect these ecosystems against acidification, tolerance to acid deposition must be quantified. The suitability of the central empirical relationship used in the Steady-State Water Chemistry (SSWC) model to predict historical sulphate (SO4) concentrations was investigated, and an alternate approach for determining aquatic critical loads of acidity (CL(A)) was employed for the study lakes (n = 260). Critical loads of acidity were often low, with median values of 12-16 mmolc m-2 yr-1, with the lower value reflecting a region-specific limit for acid-neutralizing capacity identified in this study. Uncertain levels of atmospheric deposition in the region, however, are problematic for characterizing acidification risk. Accurate S and chloride (Cl) deposition are needed to identify catchment sources (and sinks) of these elements in the new approach for CL(A) calculation. Likewise, accurate depiction of atmospheric deposition levels can prove useful for evaluation of lake runoff estimates on which estimates of CL(A) are contingent. While CL(A) are low and exceedance may occur according to projected increases in S deposition in the near-term, S retention appears to be an important feature in many catchments and risk of acidification may be overstated should long-term S retention be occurring in peatlands.

  15. Textural features of Holocene perennial saline lake deposits of the Taoudenni Agorgott basin, northern Mali

    Mees, F.


    The Holocene salt lake deposits of the Taoudenni-Agorgott basin, northern Mali, mainly consist of sediments with a high glauberite (Na 2Ca(SO 4) 2) content. The remainder of the deposits largely consists of salt beds with a bloedite (Na 2Mg(SO 4) 2·4H 2O), thenardite (Na 2SO 4) or halite (NaCl) composition. A petrographical study of the deposits demonstrates that they formed in a perennial lake that experienced a gradual decrease in water depth. Textural features of the glauberite-dominated deposits are found to be related to water depth, through the control that this factor exerts on the sensitivity of the lake to changes in water supply and to short-term variations in evaporation rates. In this way, layering — due to variations in glauberite content and crystal size — is inferred to be typical of deposits that formed in shallow water, whereas unstratified deposits are the product of high lake level stages. Halite textures are found to be indicative of the place within the water column where crystal growth occurred (along the lake bottom or higher), which is mainly determined by water depth and partly by evaporation rates. The oldest halite beds are largely unaltered cumulate deposits, whereas the youngest layers developed exclusively through bottom growth. The basal part of one thick halite bed at a level between these two groups of halite layers developed by an alternation of both types of growth, in response to variations in evaporation rates. Variations in mineralogical composition between and within the salt beds that formed during the earliest periods with a higher salinity, up to the first stage with halite formation, record a change in lake water chemistry with time but they are in one instance also determined by an early diagenetic mineral transformation.

  16. Convergence in nitrogen deposition and cryptic isotopic variation across urban and agricultural valleys in northern Utah

    Hall, S. J.; Ogata, E. M.; Weintraub, S. R.; Baker, M. A.; Ehleringer, J. R.; Czimczik, C. I.; Bowling, D. R.


    The extent to which atmospheric nitrogen (N) deposition reflects land use differences and biogenic versus fossil fuel reactive N sources remains unclear yet represents a critical uncertainty in ecosystem N budgets. We compared N concentrations and isotopes in precipitation-event bulk (wet + dry) deposition across nearby valleys in northern Utah with contrasting land use (highly urban versus intensive agriculture/low-density urban). We predicted greater nitrate (NO3-) versus ammonium (NH4+) and higher δ15N of NO3- and NH4+ in urban valley sites. Contrary to expectations, annual N deposition (3.5-5.1 kg N ha-1 yr-1) and inorganic N concentrations were similar within and between valleys. Significant summertime decreases in δ15N of NO3- possibly reflected increasing biogenic emissions in the agricultural valley. Organic N was a relatively minor component of deposition ( 13%). Nearby paired wildland sites had similar bulk deposition N concentrations as the urban and agricultural sites. Weighted bulk deposition δ15N was similar to natural ecosystems (-0.6 ± 0.7‰). Fine atmospheric particulate matter (PM2.5) had consistently high values of bulk δ15N (15.6 ± 1.4‰), δ15N in NH4+ (22.5 ± 1.6‰), and NO3- (8.8 ± 0.7‰), consistent with equilibrium fractionation with gaseous species. The δ15N in bulk deposition NH4+ varied by more than 40‰, and spatial variation in δ15N within storms exceeded 10‰. Sporadically high values of δ15N were thus consistent with increased particulate N contributions as well as potential N source variation. Despite large differences in reactive N sources, urban and agricultural landscapes are not always strongly reflected in the composition and fluxes of local N deposition—an important consideration for regional-scale ecosystem models.

  17. A possible tsunami deposit around the Jurassic Cretaceous boundary in the Boulonnais area (northern France)

    Schnyder, Johann; Baudin, François; Deconinck, Jean-François


    An unusual succession of facies locally deposited around the Jurassic-Cretaceous boundary in the Boulonnais (northern France) is attributed to a tsunami event by comparison with recent tsunami deposits. This sedimentary succession includes basal erosion with reworked lithified blocks, soft-sediment deformations, an erosional conglomerate overlain by wood fragments and clays containing continental and marine fossils in one setting and conglomerate with mixed fauna in an other setting. The tsunami probably affected the coast of the Boulonnais area of the London-Brabant Massif. The origin of the event is unknown. It was most probably triggered by an earthquake, but other origins such as volcanic eruptions, a giant landslide, or even the impact of an extraterrestrial bolide into the ocean may also be considered.

  18. Pliocene mass failure deposits mistaken as submarine tsunami backwash sediments - An example from Hornitos, northern Chile

    Spiske, Michaela; Bahlburg, Heinrich; Weiss, Robert


    In this study we question the former interpretation of a shallow marine backwash tsunami origin of a conspicuous Pliocene coarse clastic unit at Hornitos, northern Chile, and instead argue for a debris flow origin for this unit. We exclude a relation to a tsunami in general and to the Eltanin impact in particular. The observed deposit at Hornitos was not generated either directly (impact-triggered tsunami) or indirectly (submarine mass flow caused by seismic shaking) by an impact. Re-calculation of the alleged impact tsunami including consideration of the Van Dorn effect shows that an impact in the Southern Ocean did not cause a significant tsunami at Hornitos. Impact-related seismic shaking was not able to trigger slides several thousands of kilometers away because the Eltanin event was a deep sea-impact that did not create a crater. Additionally, the biostratigraphic age of 5.1-2.8 Ma of the associated La Portada Formation is not concurrent with the newly established age of 2.511 ± 0.07 Ma for the Eltanin impact. Instead, we argue for an origin of the conspicuous unit at Hornitos as a debris flow deposit caused by an earthquake in the Andean subduction zone in northern Chile. Our re-interpretation considers the local synsedimentary tectonic background, a comparison to recent submarine tsunami sediments, and recent examples of mass wasting deposits along the Chilean margin. The increased uplift during the Pliocene caused oversteepening of the coastal scarp and entailed a contemporaneous higher frequency of seismic events that triggered slope failures and cliff collapses. The coarse clastic unit at Hornitos represents an extraordinary, potentially tsunami-generating mass wasting event that is intercalated with mass wasting deposits on a smaller scale.

  19. Atmospheric black carbon deposition and characterization of biomass burning tracers in a northern temperate forest

    Santos, F.; Fraser, M. P.; Bird, J. A.


    Aerosol black carbon (BC) is considered the second largest contributor to global warming after CO2, and is known to increase the atmosphere's temperature, decrease the albedo in snow/ice, and influence the properties and distribution of clouds. BC is thought to have a long mean residence time in soils, and its apparent stability may represent a significant stable sink for atmospheric CO2. Despite recent efforts to quantify BC in the environment, the quantification of BC deposition rates from the atmosphere to terrestrial ecosystems remains scarse. To better understand the contribution of atmospheric BC inputs to soils via dry deposition and its dominant emission sources, atmospheric fine particle (PM2.5) were collected at the University of Michigan Biological Station from July to September in 2010 and 2011. PM2.5 samples were analyzed for organic C, BC, and molecular markers including particulate sugars, carboxylic acids, n-alkanes, polycyclic aromatic hydrocarbons, and cholestane. Average atmospheric BC concentrations in northern Michigan were 0.048 ± 0.06 μg m-3 in summer 2010, and 0.049 ± 0.064 μg m-3 in summer 2011. Based on atmospheric concentrations, particulate deposition calculations, and documented soil BC, we conclude that atmospheric deposition is unlikely to comprise a significant input pathway for BC in northern forest ecosystem. The major organic tracers identified in fine particulates (e.g. levoglucosan and docosanoic acid) suggest that ambient PM2.5 concentrations were mainly influenced by biomass burning and epicuticular plant waxes. These results provide baseline data needed for future assessments of atmospheric BC in rural temperate forests.

  20. Zinc isotopes in sphalerite from base metal deposits in the Red Dog district, northern Alaska

    Kelley, K.D.; Wilkinson, J.J.; Chapman, J.B.; Crowther, H.L.; Weiss, D.J.


    Analyses of sphalerite samples from shale-hosted massive sulfide and stratigraphically underlying vein breccia deposits in the Red Dog district in northern Alaska show a range ??66Zn values from zero to 0.60 per mil. The lowest values are observed in the vein breccia deposits, and the stratigraphically overlying (but structurally displaced) shale-hosted massive sulfide deposits show a systematic trend of increasing ??66Zn values from south to north (Main-Aqqaluk-Paalaaq-Anarraaq). The ??66Zn values are inversely correlated with sphalerite Fe/Mn ratio and also tend to be higher in low Cu sphalerite, consistent with precipitation of lower ??66Zn sphalerite closer to the principal hydrothermal fluid conduits. The most likely control on isotopic variation is Rayleigh fractionation during sulfide precipitation, with lighter zinc isotopes preferentially incorporated in the earliest sphalerite to precipitate from ore fluids at deeper levels (vein breccias) and close to the principal fluid conduits in the orebodies, followed by precipitation of sulfides with higher ??66Zn values in shallower and/or more distal parts of the flow path. There is no systematic variation among the paragenetic stages of sphalerite from a single deposit, suggesting an isotopically homogeneous zinc source and consistent transport-deposition conditions and/or dissolution-reprecipitation of earlier sphalerite without significant fractionation. Decoupled Zn and S isotope compositions are best explained by mixing of separate metal- and sulfur-bearing fluids at the depositional site. The results confirm that Zn isotopes may be a useful tracer for distinguishing between the central and distal parts of large hydrothermal systems as previously suggested and could therefore be of use in exploration. ?? 2009 by Economic Geology.

  1. Two coarse pyroclastic flow deposits, northern Mono-Inyo Craters, CA

    Dennen, R. L.; Bursik, M. I.; Stokes, P. J.; Lagamba, M.; Fontanella, N.; Hintz, A. R.; Jayko, A. S.


    -out distance of the Panum BAF is smaller than previously reported. Thus, there are multiple, coarse pyroclastic flow-like deposits at the northern end of the Mono-Inyo Craters, reflecting multiple phases of dome destruction. The lower blast deposit is proposed to be a blast event predating the Panum eruption, possibly originating from Pumice Pit. The Panum BAF consists of three main facies, formed by three separate, sequential events. A debris avalanche deposited a train of jigsaw clasts along a narrow path, followed by a block and ash flow that spread material over a wider region. Finally, molten rhyolite was exposed by the earlier events, resulting in rapid foam expansion and creation of a bread crusted reticulite-bearing facies.

  2. Paleomagnetism of the Red Dog Zn-Pb massive sulfide deposit in northern Alaska

    Lewchuk, Michael T.; Leach, D.L.; Kelley, K.D.; Symons, David T. A.


    Paleomagnetic methods have isolated two ancient magnetizations in and around the Paleozoic shale-hosted Red Dog ore deposit in northern Alaska. A high-latitude, westerly magnetization carried by magnetite, termed characteristic remanent magnetization A, was found in rocks that have barite and/or substantial quartz replacement of barite. An intermediate- to low-latitude, southerly magnetization (characteristic remanent magnetization B) is carried by pyrrhotite and was found in rocks dominated by galena and sphalerite. The ages the two components are constrained by their relationship with geochemistry, radiometric age dating, and hypotheses for the Mesozoic tectonic history of the Brooks Range. Characteristic remanent magnetization A fails the fold test so it must postdate the end of Brookian orogenesis (??? 150 Ma). It is always found with replacement quartz that has a radiometric date (white mica from a vug, 39Ar/40Ar) of 126 Ma. The paleolatitude for characteristic remanent magnetization B is too shallow to be Mesozoic or younger, regardless of the model for the tectonic origin of northern Alaska, and must predate Brookian orogenesis. Geologic mapping suggests that most of the ore is syngenetic, formed at 330 to 340 Ma, and a radiometric date (Re-Os on pyrite) yields an age of 338 Ma. Since characteristic remanent magnetization B predates deformation, is found in mineralized rocks and is carried by pyrrhotite, it was probably acquired during the mineralizing process as well. The combined radiometric ages and paleomagnetic data sets can be best interpreted by assuming that northern Alaska was part of an accreted terrane that was translated northward by about 30?? into its current location relative to the rest of North America and then rotated counterclockwise by 50?? to 70??. This tectonic interpretation yields plausible magnetization ages for both characteristic remanent magnetization A and B. Geologic evidence, isotopic ages, and paleomagnetic data indicate

  3. Responses of surface ozone air quality to anthropogenic nitrogen deposition in the Northern Hemisphere

    Zhao, Yuanhong; Zhang, Lin; Tai, Amos P. K.; Chen, Youfan; Pan, Yuepeng


    Human activities have substantially increased atmospheric deposition of reactive nitrogen to the Earth's surface, inducing unintentional effects on ecosystems with complex environmental and climate consequences. One consequence remaining unexplored is how surface air quality might respond to the enhanced nitrogen deposition through surface-atmosphere exchange. Here we combine a chemical transport model (GEOS-Chem) and a global land model (Community Land Model, CLM) to address this issue with a focus on ozone pollution in the Northern Hemisphere. We consider three processes that are important for surface ozone and can be perturbed by the addition of atmospheric deposited nitrogen - namely, emissions of biogenic volatile organic compounds (VOCs), ozone dry deposition, and soil nitrogen oxide (NOx) emissions. We find that present-day anthropogenic nitrogen deposition (65 Tg N a-1 to the land), through enhancing plant growth (represented as increases in vegetation leaf area index, LAI, in the model), could increase surface ozone from increased biogenic VOC emissions (e.g., a 6.6 Tg increase in isoprene emission), but it could also decrease ozone due to higher ozone dry deposition velocities (up to 0.02-0.04 cm s-1 increases). Meanwhile, deposited anthropogenic nitrogen to soil enhances soil NOx emissions. The overall effect on summer mean surface ozone concentrations shows general increases over the globe (up to 1.5-2.3 ppbv over the western US and South Asia), except for some regions with high anthropogenic NOx emissions (0.5-1.0 ppbv decreases over the eastern US, western Europe, and North China). We compare the surface ozone changes with those driven by the past 20-year climate and historical land use changes. We find that the impacts from anthropogenic nitrogen deposition can be comparable to the climate- and land-use-driven surface ozone changes at regional scales and partly offset the surface ozone reductions due to land use changes reported in previous studies

  4. Deposition and early diagenesis of playa glauberite in the Karinga Creek drainage system, Northern Territory, Australia

    Arakel, A. V.; Cohen, A.


    Glauberite [Na 2Ca(SO 4) 2], in the form of discrete crystals, nodules and lenses, represents the second most common sulphate mineral type (after gypsum) in the chain of modern playa lakes located in the Karinga Creek drainage system, Northern Territory. These modern glauberite deposits exhibit textures and fabrics which reflect both syndeposition with gypsum within the playa phreatic zone, and early diagenetic replacement of host gypsite in the playa vadose zone. Because the distribution of hydrological zones in individual playa lakes vary significantly, the extent of glauberite facies development is highly irregular. Factors controlling glauberite deposition include the nature and extent of groundwater discharge from local and regional aquifers, playa surface evaporation rates, porewater geochemistry and the depth to basal aquicludes. Geochemical and petrographic evidence indicate that the paragenesis of sulphate minerals in the playa lakes of the study area is primarily dictated by the solubility of gypsum, which in turn reflects the extent of dilution and concentration of playa porewaters. On a regional scale, brine dilution and concentration can be related to seasonal and longer-term groundwater recharge-discharge patterns; but, on a local scale, the proximity to springs and ephemeral seepage creeks emanating from local calcrete aquifers is the dominating influence. Hence, a thorough knowledge of groundwater hydrodynamics, particularly the recharge-discharge pattern in playa-marginal areas, must be an essential part of any detailed assessment of the role of depositional and early diagenetic processes in the genesis of glauberite facies in similar arid drainage basins. The close relationship between glauberite facies development and the playa groundwater level has significant implications for interpretations of variation in the water table and other environmental conditions in the shallowing-upwards sequences of ancient lacustrine deposits. The presence of

  5. The alteration of glauberite in lacustrine deposits of the Taoudenni-Agorgott basin, northern Mali

    Mees, F.


    A profile studied within Holocene salt lake deposits of the Taoudenni-Agorgott basin, northern Mali, comprises a macroscopically unstratified surface layer containing calcium sulfate minerals. This interval has previously been interpreted as a depositional unit that formed under different conditions than the underlying glauberite-bearing layered deposits. The present micromorphological study of this layer demonstrates that it formed by an alteration of the glauberite-bearing primary deposits. The first stage in the alteration of the syndepositional salts was the incongruent dissolution of glauberite (Na 2Ca(SO 4) 2). This resulted in the formation of gypsum (CaSO 4·2H 2O), both as crystals that are part of microcrystalline aggregates with a xenotopic fabric and as larger anhedral and elongated prismatic crystals. The gypsum crystals were subsequently subjected to a dehydration, resulting in a topotactic replacement of this mineral by bassanite (2CaSO 4·H 2O) and anhydrite (CaSO 4). This replacement was characterized by a parallelism between the fibre axes of the dehydrated mineral phases and the [001] axis of the gypsum crystals. During later periods, the alteration products repeatedly underwent hydration and dehydration reactions and interactions with both more concentrated and dilute solutions, producing aggregates with gypsum, bassanite, anhydrite and secondary glauberite as constituents. Aggregates of acicular crystals with a possible eugsterite (Na 4Ca(SO 4( 3·2H 2O) composition also formed during this stage. In the part of the surface layer in which the alteration is most advanced, the evaporite minerals mainly occur in the form of large anhydrite nodules. The constituents of these aggregates are not exclusively the direct product of a dehydration of the large gypsum crystals from which the nodules were derived. The products of these different stages in the alteration of the primary deposits occur in separate depth intervals of the surface layer, which

  6. Composition and genesis of ferromanganese deposits from the northern South China Sea

    Zhong, Yi; Chen, Zhong; González, Francisco Javier; Hein, James R.; Zheng, Xufeng; Li, Gang; Luo, Yun; Mo, Aibin; Tian, Yuhang; Wang, Shuhong


    Marine ferromanganese (Fe-Mn) nodules and crusts are archives of past environmental conditions and potential mineral resources. Over the last 30 years, many have been discovered in the northern South China Sea (SCS). To determine the origin of the Fe-Mn deposits, a comprehensive laboratory analysis of physical properties, mineralogy and geochemistry was conducted on newly collected Fe-Mn nodule/crust samples. The results revealed that there are three types of Fe-Mn deposits: (1) Fe-rich nodules containing essentially goethite occur on the northeastern slope of the SCS, with high Fe, low Mn (Mn/Fe = 0.03) and low trace metals and rare earth elements concentrations; (2) Smooth Fe-Mn nodules and crusts composed of asbolane, todorokite and CFA occur along the northwestern marginal of the SCS that have similar Fe and Mn contents (Mn/Fe = 1.21), moderate trace metal enrichments, and a positive Ce anomaly; (3) Fe-Mn nodules and crusts composed of asbolane, todorokite and birnessite that occur in the central basin of the SCS have higher Mn and lower Fe contents (Mn/Fe = 1.45). This depositional pattern was associated with major changes in oceanographic conditions and tectonic regimes. The northeastern slope deposits occur in a contourite depositional system, are strongly enriched in Fe relative to Mn (average 38.7% and 0.96%, respectively), formed from the combination of hydrogenetic and diagenetic processes. We propose a new genetic model for Fe-Mn nodules, which formed through the oxidation of pyrite and pyrite-barite concretions that formed by rapid early diagenetic growth (average 3320 mm/Myr) on continental margins above the carbonate compensation depth, and dominated by hydrocarbon seep structures and strong erosive action of bottom currents along the northeastern slope. In contrast, the introduction of vigorous deep-water flow from the North Pacific promoted the slow growth (4-7 mm/Myr) of hydrogenetic Fe-Mn nodules and crusts along the northwestern margin. Finally

  7. Surface Water-Ice Deposits in the Northern Shadowed Regions of Ceres

    Platz, T.; Nathues, A.; Schorghofer, N.; Preusker, F.; Mazarico, E.; Schroeder, S. E.; Byrne, S.; Kneissl, T.; Schmedemann, N.; Combe, J.-P.; Schaefer, M.; Thangjam, G. S.; Hoffmann, M.; Gutierrez-Marques, P.; Landis, M. E.; Dietrich, W.; Ripken, J.; Matz, K. D.; Russell, C. T.


    Ceres, a dwarf planet located in the main asteroid belt, has a low bulk density, and models predict that a substantial amount of water ice is present in its mantle and outer shell. The Herschel telescope and the Dawn spacecraft have observed the release of water vapor from Ceres, and exposed water ice has been detected by Dawn on its surface at mid-latitudes. Water molecules from endogenic and exogenic sources can also be cold-trapped in permanent shadows at high latitudes, as happens on the Moon and Mercury. Here we present the first image-based survey of Ceres's northern permanent shadows and report the discovery of bright deposits in cold traps. We identify a minimum of 634 permanently shadowed craters. Bright deposits are detected on the floors of just 10 of these craters in multiscattered light. We spectroscopically identify one of the bright deposits as water ice. This detection strengthens the evidence that permanently shadowed areas have preserved water ice on airless planetary bodies.

  8. Gravity worms in the prospecting of epigenetic gold deposits: Example from the Northern Fennoscandian Shield

    Lahti, Ilkka; Nykänen, Vesa; Niiranen, Tero


    Mapping of mineralized geologic structures using geophysical potential field datasets has become an essential part of present-day exploration projects. Various geophysical processing and semiautomatic interpretation techniques have provided new tools into the field of conventional exploration process. Such is the multiscale edge detection or "worming-technique" introduced by Hornby et al., (1999). Worms are representations of the maxima of potential field horizontal gradients. They are calculated at different upward continuation levels providing an alternative view into potential field anomalies and geometry of the anomaly sources. In this work we use the worming-technique on the regional gravity dataset collected by the Geological Survey of Finland during the last four decades in the northern Finland. The dataset consists of more than 19 000 ground gravity observations covering an area of about 15000 km2 with an average site separation of 0.5 - 1 km. The study area covers the central part of the 2.4-2.0 Ga Central Lapland Greenstone belt (CLGB) which is one of the largest Proterozoic greenstone terrains in the world. The CLGB hosts numerous gold occurrences of varying type and size. The majority of the gold occurrences fall into the orogenic gold category but also Iron Oxide-Copper-Gold (IOCG) and paleoplacer types are known within the region (e.g. Eilu et al., 2007). Currently the largest known deposit in the area is the Suurikuusikko orogenic gold deposit with current resources exceeding 5 million ounces Au. The largest known gold resources in IOCG type deposit is in the Hannukainen deposit with ca. 200 000 ounces of gold. All the known orogenic gold and IOCG deposits in the CLGB show intimate spatial correlation to shear zones of varying scale. Processed gravity worms display striking spatial correlation with the known orogenic gold and IOCG deposits. In some cases the gold hosting shear zones are outlined by gravity worms either completely (Sirkka shear zone

  9. Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

    Sprovieri, Francesca; Pirrone, Nicola; Bencardino, Mariantonia; D'Amore, Francesco; Angot, Helene; Barbante, Carlo; Brunke, Ernst-Günther; Arcega-Cabrera, Flor; Cairns, Warren; Comero, Sara; Diéguez, María del Carmen; Dommergue, Aurélien; Ebinghaus, Ralf; Feng, Xin Bin; Fu, Xuewu; Garcia, Patricia Elizabeth; Gawlik, Bernd Manfred; Hageström, Ulla; Hansson, Katarina; Horvat, Milena; Kotnik, Jože; Labuschagne, Casper; Magand, Olivier; Martin, Lynwill; Mashyanov, Nikolay; Mkololo, Thumeka; Munthe, John; Obolkin, Vladimir; Ramirez Islas, Martha; Sena, Fabrizio; Somerset, Vernon; Spandow, Pia; Vardè, Massimiliano; Walters, Chavon; Wängberg, Ingvar; Weigelt, Andreas; Yang, Xu; Zhang, Hui


    The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.

  10. Geology and Metal Contents of the Ruttan volcanogenic massive sulfide deposit, northern Manitoba, Canada

    Barrie, C. Tucker.; Taylor, Craig; Ames, Doreen E.


    The Paleoproterozoic Ruttan Cu-Zn volcanogenic massive-sulfide (VMS) deposit is a large, relatively low grade, bimodal-siliciclastic type deposit in the Rusty Lake volcanic belt of northern Manitoba. The deposit contained over 82.8 million tonnes of massive sulfide, of which 55.7 million tonnes were mined from 1973 to 2002. The deposit consists of a series of moderately to steeply dipping, south-facing lenses that extend along strike at the surface for 1.1 km and to a depth of 1.0 km. These lenses occur within a steeply dipping, bimodal volcanic, volcaniclastic and siliciclastic sequence. In the immediate mine area, transitional calc-alkalic to high-silica (tholeiitic), felsic, and intermediate volcanic/volcaniclastic rocks of the Mine Sequence are host to, and intercalated with, the massive-sulfide lenses. Transitional tholeiitic to calc-alkalic basalt and andesite are present in the footwall sequence, approximately 500 m down-section from the ore horizon. The overlying rocks are predominantly fine-grained volcaniclastics and siliciclastics, but include polyfragmental agglomerate that contains mafic bombs and scoriaceous felsic fragments. Syn-depositional felsic and mafic dikes, sills, and apophyses are ubiquitous throughout the Mine Sequence, including the ore lenses, indicating continued, near-vent magmatism, and volcanism during ore formation. Fabrics in altered hostrocks have consistent, down-plunge stretching lineations to the SSE that suggest the deposit has been elongated by a factor of ~1.2-1.5; otherwise, the deposit is remarkably undeformed. Syn- and post-depositional faults in the mine area have relatively minor displacements up to tens of meters. Proximal (within 200 m) footwall rocks exhibit moderate to strong chloritization, characterized by the upper greenschist to lower amphibolite facies assemblages that include cordierite-almandine-andalusite-sillimanite-biotite ± staurolite ± anthophyllite ± talc, and local silicification. The proximal

  11. Assessment of ecotoxicological risks related to depositing dredged materials from canals in northern France on soil.

    Perrodin, Yves; Babut, Marc; Bedell, Jean-Philippe; Bray, Marc; Clement, Bernard; Delolme, Cécile; Devaux, Alain; Durrieu, Claude; Garric, Jeanne; Montuelle, Bernard


    The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil close to a canal and groundwater, and tested with sediment samples from canals in northern France. This framework includes two steps: a simplified risk assessment based on contaminant concentrations and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three related assumptions: (a) effects on plants (Lolium perenne L.), (b) effects on aquatic organisms (Escherichia coli, Pseudokirchneriella subcapitata, Ceriodaphnia dubia, and Xenopus laevis) and (c) effects on groundwater contamination. Several exposure conditions were tested using standardised bioassays. According to the specific dredged material tested, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitive. Several aspects of the assessment procedure must now be improved, in particular assessment endpoint design for risks to ecosystems (e.g., integration of pollutant bioaccumulation), bioassay protocols and column leaching test design.

  12. Permian to late Cenozoic evolution of northern Patagonia: Main tectonic events, magmatic activity, and depositional trends

    Uliana, M. A.; Biddle, K. T.

    The late Paleozoic to late Cenozoic evolution of northern Patagonia was influenced significantly by events that occurred while the area was part of the South American sector of Gondwanaland. Late Paleozoic to Middle Triassic subduction along the edge of the supercontinent formed a broad convergent-margin system that is the underpinning of northern Patagonia. Deformation (Gondwanidian orogeny) associated with the subduction is recognized in both the forearc and the convergent backarc areas. Regional extension, accompanied by bimodal volcanism, began in the Late Triassic and led to the formation of a number of north-northwest trending rift basins in Patagonia, which generally followed the Gondwanidian basement grain. Continued extension in the Jurassic and Early Cretaceous led to the opening of the Rocas Verdes marginal basin in southern Chile and, ultimately, to the opening of the South Atlantic Ocean. Once oceanic crust began to form, faulting and volcanism declined in Patagonia. During the late Early Cretaceous to the Late Cretaceous, sags over the rift basins coalesced to form a broad backarc basin behind the volcanic arc to the west. These sags are suggestive of thermally driven subsidence. Subsidence of the evolving Atlantic margin allowed extensive marine transgressions to take place from the east. The stratigraphic record of northern Patagonia reflects these events. The upper Paleozoic to upper Mesozoic sedimentary sequences were deposited in basins directly associated with convergent activity along the margin of Gondwanaland or in rift basins created during its breakup. Even though the Tertiary evolution of Patagonia was dominated by events along the western margin of South America, the patterns of sediment transport, thickness, and general shoreline position were still influenced by the locations of the Mesozoic rifts formed during the breakup of Gondwanaland.

  13. Reconstructing the Holocene depositional environments along the northern coast of Sfax (Tunisia): Mineralogical and sedimentological approaches

    Lamourou, Ali; Touir, Jamel; Fagel, Nathalie


    A sedimentological and mineralogical study of sedimentary cores allowed reconstructing the evolution of depositional environments along the Northern coast of Sfax (Tunisia). The aim of this research work is to identify the factors controlling the sedimentation from the Holocene to the Present time. Three 30-m sediment cores collected by drilling at 30 m water depth were analyzed for their color, magnetic susceptibility signal, grain size by laser diffraction, organic matter content by loss of ignition, carbonate content by calcimetry and mineralogy by X-ray diffraction on bulk powder and clay <2 μm. They broadly present the same sedimentological and mineralogical features. Microscopical observations of petrographic slides allowed identifying six main sedimentary facies. Bulk mineralogical assemblages comprised clay minerals, quartz, calcite, gypsum and K-feldspars were examined. Considerable change was observed in the carbonate content that mimicked the bioclaste abundance and diluted the detrital minerals (clay minerals, quartz and feldspars). The gypsum mainly occurred in the lower sedimentary columns (SC12 and SC9) and in the upper/middle of core SC6. The clay fraction was made of a mixture of kaolinite, illite, smectite and palygorskite with no clear variation through core depth. Both grain-size parameters and magnetic susceptibility profile showed a sharp transition in the upper 2-5 m of the sedimentological columns. Coarse, sandy to gravely sediments characterized by a low magnetic susceptibility signal were replaced by fine bioclastic-rich clayey sediments. The analysis of vertical succession of depositional facies revealed a fluvial depositional environment (coastal plain) basically marked by fluvial channels and inundation plains at the bottom of all cores. However, core-top sediments recorded a littoral marine environment with sand depositions rich in gastropods, lamellibranches and algæ. Depositional facies, sedimentological and mineralogical

  14. Potential links between porphyry copper deposits and exhumed metamorphic basement complexes in northern Chile

    Cooper, Frances; Docherty, Alistair; Perkins, Rebecca


    Porphyry copper deposits (PCDs) are typically associated with magmatic arcs in compressional subduction zone settings where thickened crust and fractionated calc-alkaline magmas produce favourable conditions for copper mineralisation. A classic example is the Eocene-Oligocene PCD belt of Chile, the world's leading copper producing country. In other parts of the world, older late Cretaceous to early Tertiary PCDs are found in regions of former subduction-related magmatism that have undergone subsequent post-orogenic crustal extension, such as the Basin and Range province of western North America, and the Eurasian Balkan-Carpathian-Dinaride belt. In the Basin and Range there is a striking correlation between the location of many PCDs and exhumed metamorphic core complexes (isolated remnants of the middle to lower crust exhumed during extensional normal faulting). This close spatial relationship raises questions about the links between the two. For example, are their exhumation histories related? Could the presence of impermeable metamorphic rocks at depth affect and localise mineralising fluids? In Chile there appears to be a similar spatial relationship between PCDs and isolated outcrops of exhumed metamorphic basement. In northern Chile, isolated exposures of high-grade metamorphic gneisses and amphibolites are thought to be exhumed remnants of the pre-subduction Proterozoic-Paleozoic continental margin of Gondwana [2], although little is known about when they were exhumed and by what mechanism. For example, the Limón Verde metamorphic complex, exhumed from a depth of ca. 50 km, is situated adjacent to Chuquicamata, the largest open pit copper mine in the world. In northernmost Chile, another metamorphic exposure, the Belén complex, sits close to the Dos Hermanos PCD, a small deposit that is not actively mined. Comprising garnet-bearing gneisses and amphibolites, the Belén is thought to have been exhumed from a depth of ca. 25 km, but when and how is unclear [3

  15. Lacustrine responses to decreasing wet mercury deposition rates: results from a case study in northern Minnesota

    Brigham, Mark E.; Sandheinrich, Mark B.; Gay, David A.; Maki, Ryan P.; Krabbenhoft, David P.; Wiener, James G.


    We present a case study comparing metrics of methylmercury (MeHg) contamination for four undeveloped lakes in Voyageurs National Park to wet atmospheric deposition of mercury (Hg), sulfate (SO4–2), and hydrogen ion (H+) in northern Minnesota. Annual wet Hg, SO4–2, and H+ deposition rates at two nearby precipitation monitoring sites indicate considerable decreases from 1998 to 2012 (mean decreases of 32, 48, and 66%, respectively). Consistent with decreases in the atmospheric pollutants, epilimnetic aqueous methylmercury (MeHgaq) and mercury in small yellow perch (Hgfish) decreased in two of four lakes (mean decreases of 46.5% and 34.5%, respectively, between 2001 and 2012). Counter to decreases in the atmospheric pollutants, MeHgaq increased by 85% in a third lake, whereas Hgfish increased by 80%. The fourth lake had two disturbances in its watershed during the study period (forest fire; changes in shoreline inundation due to beaver activity); this lake lacked overall trends in MeHgaq and Hgfish. The diverging responses among the study lakes exemplify the complexity of ecosystem responses to decreased loads of atmospheric pollutants.

  16. Late Pleistocene carnivores (Carnivora: Mammalia) from a cave sedimentary deposit in northern Brazil.

    Rodrigues, Shirlley; Avilla, Leonardo S; Soibelzon, Leopoldo H; Bernardes, Camila


    The Brazilian Quaternary terrestrial Carnivora are represented by the following families: Canidae, Felidae, Ursidae, Procyonidae Mephitidae and Mustelidae. Their recent evolutionary history in South America is associated with the uplift of the Panamanian Isthmus, and which enabled the Great American Biotic Interchange (GABI). Here we present new fossil records of Carnivora found in a cave in Aurora do Tocantins, Tocantins, northern Brazil. A stratigraphical controlled collection in the sedimentary deposit of the studied cave revealed a fossiliferous level where the following Carnivora taxa were present: Panthera onca, Leopardus sp., Galictis cuja, Procyon cancrivorus, Nasua nasua and Arctotherium wingei. Dating by Electron Spinning Resonance indicates that this assemblage was deposited during the Last Glacial Maximum (LGM), at least, 22.000 YBP. The weasel, G. cuja, is currently reported much further south than the record presented here. This may suggest that the environment around the cave was relatively drier during the LGM, with more open vegetation, and more moderate temperatures than the current Brazilian Cerrado.

  17. Late Pleistocene carnivores (Carnivora: Mammalia from a cave sedimentary deposit in northern Brazil



    Full Text Available The Brazilian Quaternary terrestrial Carnivora are represented by the following families: Canidae, Felidae, Ursidae, Procyonidae Mephitidae and Mustelidae. Their recent evolutionary history in South America is associated with the uplift of the Panamanian Isthmus, and which enabled the Great American Biotic Interchange (GABI. Here we present new fossil records of Carnivora found in a cave in Aurora do Tocantins, Tocantins, northern Brazil. A stratigraphical controlled collection in the sedimentary deposit of the studied cave revealed a fossiliferous level where the following Carnivora taxa were present: Panthera onca, Leopardus sp., Galictis cuja, Procyon cancrivorus, Nasua nasua and Arctotherium wingei. Dating by Electron Spinning Resonance indicates that this assemblage was deposited during the Last Glacial Maximum (LGM, at least, 22.000 YBP. The weasel, G. cuja, is currently reported much further south than the record presented here. This may suggest that the environment around the cave was relatively drier during the LGM, with more open vegetation, and more moderate temperatures than the current Brazilian Cerrado.

  18. Late Pleistocene carnivores (Carnivora: Mammalia) from a cave sedimentary deposit in northern Brazil.

    Rodrigues, Shirlley; Avilla, Leonardo S; Soibelzon, Leopoldo H; Bernardes, Camila


    The Brazilian Quaternary terrestrial Carnivora are represented by the following families: Canidae, Felidae, Ursidae, Procyonidae Mephitidae and Mustelidae. Their recent evolutionary history in South America is associated with the uplift of the Panamanian Isthmus, and which enabled the Great American Biotic Interchange (GABI). Here we present new fossil records of Carnivora found in a cave in Aurora do Tocantins, Tocantins, northern Brazil. A stratigraphical controlled collection in the sedimentary deposit of the studied cave revealed a fossiliferous level where the following Carnivora taxa were present: Panthera onca, Leopardus sp., Galictis cuja, Procyon cancrivorus, Nasua nasua and Arctotherium wingei. Dating by Electron Spinning Resonance indicates that this assemblage was deposited during the Last Glacial Maximum (LGM), at least, 22.000 YBP. The weasel, G. cuja, is currently reported much further south than the record presented here. This may suggest that the environment around the cave was relatively drier during the LGM, with more open vegetation, and more moderate temperatures than the current Brazilian Cerrado.

  19. Metals in bulk deposition and surface waters at two upland locations in northern England.

    Lawlor, A J; Tipping, E


    Concentrations of aluminium and minor metals (Mn, Ni, Cu, Zn, Sr, Cd, Ba, Pb) were measured in precipitation and surface water at two upland locations (Upper Duddon Valley, UDV; Great Dun Fell, GDF) in northern England for 1 year commencing April 1998. At both locations, the loads in bulk precipitation were at the lower ends of ranges reported for other rural and remote sites, for the period 1985-1995. The deposited metals were mostly in the dissolved form, and their concentrations tended to be greatest when rainfall volumes were low. The concentrations of Cu, Zn and Pb in deposition were correlated (r2 > or = 0.40) with concentrations of non-marine sulphate. Three streams, ranging in mean pH from 5.07 to 7.07, and with mean concentrations of dissolved organic carbon (DOC) waters at each location, and temporal variations in individual waters, can be explained qualitatively in terms of sorption to solid-phase soil organic matter and mineral surfaces, complexation and transport by DOC, and chemical weathering. The UDV catchments are sinks for Pb and sources of Al, Mn, Sr, Cd and Ba. The GDF catchments are sources of Al, Mn, Ni, Zn, Sr, Cd and Ba. Other metals measured at the two locations are approximately in balance. Comparison of metal:silicon ratios in the surface waters with values for silicate rocks indicates enrichment of Ni and Cu, and substantial enrichment of Zn, Cd and Pb. These enrichments, together with high metal deposition in the past, make it likely that concentrations of the metals in the surface waters are governed by release from catchment pools of atmospherically-deposited metal. The catchments appear to be responding on a time scale of decades, possibly centuries, to changes in metal deposition. For the more acid waters at UDV, the calculated free-ion concentrations of Al are similar to published LC50 values for acute toxicity towards fish. The free-ion concentrations of Ni, Cu, Zn and Cd in all the surface waters are one-to-four orders of

  20. The Pianosa Contourite Depositional System (Northern Tyrrhenian Sea): drift morphology and Plio-Quaternary stratigraphic evolution

    Miramontes Garcia, Elda; Cattaneo, Antonio; Jouet, Gwenael; Thereau, Estelle; Thomas, Yannick; Rovere, Marzia; Cauquil, Eric; Trincardi, Fabio


    The Pianosa Contourite Depositional System (CDS) is located in the Corsica Trough (Northern Tyrrhenian Sea), a confined basin dominated by mass transport and contour currents in the eastern flank and by turbidity currents in the western flank. The morphologic and stratigraphic characterisation of the Pianosa CDS is based on multibeam bathymetry, seismic reflection data (multi-channel high resolution mini GI gun, single-channel sparker and CHIRP), sediment cores and ADCP data. The Pianosa CDS is located at shallow to intermediate water depths (170 to 850 m water depth) and is formed under the influence of the Levantine Intermediate Water (LIW). It is 120 km long, has a maximum width of 10 km and is composed of different types of muddy sediment drifts: plastered drift, separated mounded drift, sigmoid drift and multicrested drift. The reduced tectonic activity in the Corsica Trough since the early Pliocene permits to recover a sedimentary record of the contourite depositional system that is only influenced by climate fluctuations. Contourites started to develop in the Middle-Late Pliocene, but their growth was enhanced since the Middle Pleistocene Transition (0.7-0.9 Ma). Although the general circulation of the LIW, flowing northwards in the Corsica Trough, remained active all along the history of the system, contourite drift formation changed, controlled by sediment influx and bottom current velocity. During periods of sea level fall, fast bottom currents often eroded the drift crest in the middle and upper slope. At that time the proximity of the coast to the shelf edge favoured the formation of bioclastic sand deposits winnowed by bottom currents. Higher sediment accumulation of mud in the drifts occurred during periods of fast bottom currents and high sediment availability (i.e. high activity of turbidity currents), coincident with periods of sea level low-stands. Condensed sections were formed during sea level high-stands, when bottom currents were more sluggish

  1. New data on OSL dating of Early Khalynian deposits of Northern Caspian

    Sychev, Nikita; Yanina, Tamara; Svitoch, Alexander; Kurbanov, Redzhep; Badyukova, Ekaterina


    Ponto-Caspian region is the key region the study of which can provide information about the paleogeographic history of the central Eurasia, particularly revealing the history of the East European Plain, the Caucasus and Central Asia. However, despite the long history of the study, today there is no accepted general stratigraphic scheme of the Caspian Sea. One of the most interesting and important stages of Late Pleistocene history of Caspian is Khalynian transgression which is divided into two major phases: early and ate. In the Caspian lowland Lower Khalynian stage are represented by a unique type of deposit - "chocolate clays". A distinctive feature of these sediments is widely distributed among Lower Khalynian deposits of Northern Caspian and the Volga region. All clay deposits are confined to the diverse origins of depression before-Khalynian relief. Chocolate clays formation consists of facies: mono-clay (typological), layered, sand- and silty-clay (Svitoch, Yanina, 1997). Determining the age of chocolate clays by optically stimulated luminescence (OSL) in our view will allow bettering the understanding of their genesis. Age of chocolate clays of Lower Volga was widely dated using the radiocarbon. However, the existing chronology is controversial, raises a number of issues, primarily due to the material of which are used for dating - thin shells of Caspian mollusks of the Didacna Eichw. genus, which are characterized by a significant isotopic exchange with the enclosing sediments (Arslanov, 2015). Lower Volga region is characterized by very complex geological structure of the Late Pleistocene deposits (alternating continental aeolian, alluvial and slope sediments with marine Caspian deposits of different age). There are many conflicting opinions, not only with respect to paleogeographic features of the area, but also to its precise chronology. The differences in opinion over the age of the individual stages of development of the Caspian Sea (transgressions and

  2. Reconstruction of the palaeoenvironment using biomarkers and clay mineralogy in loess deposits of northern Iran

    A. Shahriari


    Full Text Available Introduction: Knowledge about palaeoenviroment and palaeovegetation provides information about how vegetation reacts on climate fluctuations in the past, what will help understanding current and future developments caused by e.g. climate change. Northern Iranian Loess-Plateau forms a strongly dissected landscape with steeply sloping loess hills. This loess record reflects numerous cycles of climate change and landscape evolution for the Middle to Late Quaternary period. therefore, this study was done for reconstruction of palaeoenvironment (climate and vegetation in loess-palaeosol sequences in northern Iran. Therefore, this study aims at a preliminary reconstruction of palaeovegetation and palaeoenvironment, in loess-palaeosol sequences along a cliomosequnce in Northern Iran. Materials and Methods: Two loess-palaeosol sequences (Agh Band and Nowdeh sections were chosen in Golestan province, in northern Iran and step-wise profiles were prepared. Agh Band section is located in the western most part of the Northern Iranian loess plateau and has about 50 m thickness of loess deposits. Nowdeh loess-palaeosol sequence is located about 20 km southeast of Gonbad-e Kavus, in the vicinity of the Nowdeh River. Soil sampling was done in several field campaigns in spring 2012. More than 30cm of the surface deposits were removed in order to reach for undisturbed loess and palaeosols and one mixed sample was taken from each horizonA comparison of palaeosols with modern soils formed under known Holocene climatic conditions, which are derived from substrates with similar granulometric and mineralogical composition are suited for reconstructing past climate and environment. Hence, six modern soil profiles were prepared along the climosequnce and the vegetation cover changed from grassland in the dry area to dense shrub land and forest in the moist part of the ecological gradient. For reconstruction of palaeoenvironment (climate and vegetation some basic physico

  3. Isotopic Characteristics of Mesozoic Au-Ag Polymetallic Ore Deposits in Northern Hebei and Their Ore-Forming Materials Source

    王宝德; 牛树银; 孙爱群; 李红阳


    It has long been a controversy about the source of ore-forming materials of Au-Agpolymetallic deposits both in metallogenic theory and in ore-searching practice. In terms of alarge wealth of the isotopic statistics data from Indosinian-Yanshanian endogenic ore deposits innorthern Hebei (generally referring to the areas along the northern part of Taihang Mountainsand northern Hebei, the same below) , it is considered that the ore-forming materials came fromthe deep interior of the Earth, which had migrated through plumes to the Earth surface while ex-perienced multi-stage evolution and then emplaced progressively in favorable structural loci toform ores. Their isotope data show that 559 sulfur isotopic data from 40 ore deposits are, for themost part, within the range of - 5‰ - 5‰, with a high degree of homogenization, indicatingthat the sulfur is derived mainly from magma; 200 lead isotope data from 37 ore deposits indi-cate that the ore-forming materials are principally of mantle source though some crust-source ma-terial was involved; 96 oxygen, hydrogen and carbon isotope data from 34 ore deposits illustratethat the ore-forming fluids are dominated by magmatic water while other sources of water wouldbe involved. It may therefore be seen that the formation of endogenic deposits has nothing to dowith the strata.

  4. Colloid investigations of acid rock drainage solution from an abandoned Zn-Pb-Ag mine by ultrafiltration and PCS measurements

    Richter, W.; Zaenker, H.


    Acid rock drainage (ARD) solution from an abandoned ore mine was investigated by photon correlation spectroscopy, ultrafiltration and ICP-MS. A colloid concentration of about 1 g/L was found. The prevailing particle size was < 5 nm. (orig.)

  5. Radionuclide migration at the Koongarra uranium deposit, Northern Australia Lessons from the Alligator Rivers analogue project

    Payne, Timothy E.; Airey, Peter L.

    The Koongarra uranium deposit in Northern Australia provides a ‘natural analogue’ for processes that are of relevance for assessing the safety of radioactive waste disposal. In an international project extending over two decades, the Koongarra ore body was studied to increase the understanding of radionuclide migration and retention mechanisms that might occur in the vicinity of a geological repository. The research effort included extensive characterisation of the geological, hydrological and geochemical conditions at the site. Patterns of the distribution of radionuclides (predominantly members of the 238U decay chain, but also the rare isotopes 239Pu, 99Tc and 129I) were studied in both solid and groundwater phases. The project included detailed studies of uranium adsorption on mineral surfaces, and of subsequent processes that may lead to long-term uranium immobilisation. Numerous models for uranium migration were developed during the project. This paper provides a comprehensive review of the research at Koongarra, and assesses the value of the site for integrating the results of a complex series of laboratory, modelling and field studies. The insights gained from this review of the Koongarra project may assist in maximising the potential scientific benefit of future natural analogue studies.

  6. Chloritization and associated alteration at the Jabiluka unconformity-type uranium deposit, Northern Territory, Australia

    Nutt, Constance J.


    Jabiluka is the largest of four known uncomformity-type uranium deposits that are hosted by brecciated and altered metasedimentary rocks in the Pine Creek geosyncline, Northern Territory, Australia. The alteration zone at Jabiluka is dominated by chlorite, but also contains white mica, tourmaline and apatite; hematite is present, but only in minor amounts. Added quartz is mainly restricted to fractures and breccias. Chlorite, which formed during episodic fluid movement, partly to totally replaced all pre-existing minerals. Chloritized rocks are enriched in Mg, and depleted in K, Ca, Na and Si. Five types of chlorite are optically and chemically distinguishable in the rocks at Jabiluka. Chloritization is proposed as a mechanism that lowered the pH of the circulating fluid, and also caused significant loss of silica from the altered rocks. The proposed constraints on alteration, and presumably on at least part of the uranium mineralization, neither require nor preclude the existence of the unconformity as necessary for the formation of ore.

  7. Oligocene biogenic siliceous deposits on the slope of the northern South China Sea


    The abundance of radiolarian, diatom and sponge spicule and H4SiO4 in pore-waters increase abruptly at the boundary between Early and Late Oligocene (about 30-27.5 Ma) at Site 1148 of the northern South China Sea (SCS), indicating high biogenic silica accumulation during this time. At the same time (about 30-28 Ma), high biogenic silica deposition occurred in the cen tral equatorial Pacific. Comparison of the biogenic silica accumulation at Site 1148 of the SCS with that at Site 929 of the Atlantic verifies that the biogenic silica accumulation between the low lati tude Pacific and Atlantic oceans expresses the evident relationship of compensation during theOligocene. Biogenic silica accumulation decreased in the Atlantic, whereas it increased in the Pa cific at the boundary between the Early and Late Oligocene. It resulted from the formation and presence of North Atlantic deep water (NADW) in the Atlantic basin, indicating an intensive basin-basin fractionation. XRD analysis and SEM observation of the samples from Site 1148 demon strate that most of radiolarian, diatom and sponge spicule have suffered from dissolution and reprecipitation, suggested by the opal-A→opal-CT transformation. As a result of the transformation,porosity increased, but dry and bulk densities decreased, reflecting the consequence of diagenesis on the physical property of sediment.

  8. Carbonate cementation in the late glacial outwash and beach deposits in northern Estonia

    Maris Rattas


    Full Text Available The sedimentary environments, morphology and formation of carbonate cement in the late glacial glaciofluvial outwash and beach deposits in northern Estonia are discussed. Cementation is observed in well-drained, highly porous carbonaceous debris-rich gravel and sand-forming, resistant ledges in otherwise unconsolidated sediments. The cemented units occur as laterally continuous layers or as isolated lenticular patches with thicknesses from a few centimetres to 3 m. The cement is found in two main morphologies: (1 cement crusts or coatings around detrital grains and (2 massive cement almost entirely filling interparticle pores and intraparticle voids. It is exclusively composed of low-Mg calcite with angular equant to slightly elongated rhombohedral and scalenohedral or prismatic crystals, which indicate precipitation from meteoric or connate fresh surface (glacial lake water and/or near-surface groundwater under low to moderate supersaturation and flow conditions. The absence of organic structures within the cement suggests that cementation is essentially inorganic. The cement exhibits both meteoric vadose and phreatic features and most probably occurred close to the vadose–phreatic interface, where the conditions were transitional and/or fluctuating. Cementation has mainly taken place by CO2-degassing in response to fluctuations in groundwater level and flow conditions, controlled by the Baltic Ice Lake water level, and seasonal cold and/or dry climate conditions.

  9. Preliminary geological assessment of the Northern edge of ultimi lobe, Mars South Polar layered deposits

    Murray, B.; Koutnik, M.; Byrne, S.; Soderblom, L.; Herkenhoff, K.; Tanaka, K.L.


    We have examined the local base of the south polar layered deposits (SPLD) exposed in the bounding scarp near 72??-74??S, 215??- 230??W where there is a clear unconformable contact with older units. Sections of layering up to a kilometer thick were examined along the bounding scarp, permitting an estimate of the thinnest individual layers yet reported in the SPLD. Rhythmic layering is also present locally, suggesting a similarly rhythmic variation in environmental conditions and a recorded climate signal at least in some SPLD strata. Locally, angular unconformities may be present, as has been reported for the north polar layered deposits (NPLD) and may likewise imply intervals of subaerial erosion in the SPLD. The outcropping layers display a broad range of weathering styles and may reflect more diverse conditions of depositions, erosion, and diagenesis than might have been expected from simple aeolian depostion modulated only by astronomically driven climatic fluctuations. An unexpected finding of our study is the presence of locally abundant small pits close to the bounding scarp. These quasi-circular, negative, rimless features probably originated as impact craters and were modified to varying degrees by local endogenic processes, as well as locally variable blanketing. A nominal exposure age for the most heavily cratered region in our study area is about 2 million years, and the crater statistics appear consistent with those for the overall SPLD, although there are large uncertainties in the absolute ages implied by the crater size-frequency statistics, as in all martian crater ages. Another new finding is the presence of mass wasting features along the steepest portion of the retreating bounding scarp as well as a number of examples of brittle fracture, consistent with large-scale slumping along the bounding scarp and probably also ancient basal sliding. Both subhorizontal and high angle faults appear to be exposed in the bounding scarp, but the dips of the

  10. On the role of buoyancy force in the ore genesis of SEDEX deposits: Example from Northern Australia

    YANG JianWen; FENG ZuoHai; LUO XianRong; CHEN YuanRong


    Finite element modeling on a highly conceptualized 2-D model of fluid flow and heat transport is un-dertaken to simulate the paleo-hydrological system as if the Mount Ise deposits were being formed in the Mount Isa basin, Northern Australia, and to evaluate the potential of buoyancy force in driving ba-sin-scale fluid flow for the formation of sedimentary-exhalative (SEDEX) deposits. Our numerical case studies indicate that buoyancy-driven fluid flow is controlled mainly by the fault penetration depth and its spatial relation with the aquifer. Marine water recharges the basin via one fault and flows through the aquifer where it is heated from below. The heated metalliferous fluid discharges to the basin floor via the other fault. The venting fluid temperatures are computed to be in the range of 115 to 160℃, with fluid velocities of 2.6 to 4.1 m/year over a period of 1 Ma. These conditions are suitable for the formation of a Mount Isa-sized zinc deposit, provided a suitable chemical trap environment is present. Buoyancy force is therefore a viable driving mechanism for basin-scale ore-forming hydrothermal fluid migration, and it is strong enough to lead to the genesis of supergiant SEDEX deposits like the Mount Isa deposit, Northern Australia.

  11. Huge, CO2-charged debris-flow deposits and tectonic sagging in the northern plains of Mars

    Tanaka, K.L.; Banerdt, W.B.; Kargel, J.S.; Hoffman, N.


    The northern plains of Mars contain a vast deposit, covering one-sixth of the planet, that apparently resulted in extensive lithospheric deformation. The center of the deposit may be as much as 2-3 km thick. The deposit has lobate margins consistent with the flow of fluidized debris for hundreds to thousands of kilometers derived from highland and high-plains sources. The deposit surface lowers inward by ???900 m in places and is locally bordered by a bulge ???300 m high. Similar deformation accompanied development of Pleistocene ice sheets on Earth. The lack of burial of a large inlier of older terrain and the response time of the mantle to the loading require that the deposit was emplaced in <1000 yr, assuming that the deposit was originally flat. We account for what may have been the largest catastrophic erosional and/or depositional event in solar system history by invoking pore-filling subsurface CO2 as an active agent in the processes of source-rock collapse and debris flow.

  12. Siderite deposits in northern Italy: Early Permian to Early Triassic hydrothermalism in the Southern Alps

    Martin, Silvana; Toffolo, Luca; Moroni, Marilena; Montorfano, Carlo; Secco, Luciano; Agnini, Claudia; Nimis, Paolo; Tumiati, Simone


    We present a minero-petrographic, geochemical and geochronological study of siderite orebodies from different localities of the Southern Alps (northern Italy). Siderite occurs as veins cutting the Variscan basement and the overlying Lower Permian volcano-sedimentary cover (Collio Fm.), and as both veins and conformable stratabound orebodies in the Upper Permian (Verrucano Lombardo and Bellerophon Fms.) and Lower Triassic (Servino and Werfen Fms.) sedimentary sequences of the Lombardian and the Venetian Alps. All types of deposits show similar major- and rare-earth (REE)-element patterns, suggesting a common iron-mineralizing event. The compositions of coexisting siderite, Fe-rich dolomite and calcite suggest formation from hydrothermal fluids at relatively high temperature conditions (≥ 250 °C). Geochemical modelling, supported by REE analyses and by literature and new δ13C and δ18O isotopic data, suggests that fluids responsible for the formation of siderite in the Variscan basement and in the overlying Lower Permian cover were derived from dominant fresh water, which leached Fe and C from volcanic rocks (mainly rhyolites/rhyodacites) and organic carbon-bearing continental sediments. On the basis of U-Th-Pb microchemical dating of uraninite associated with siderite in the Val Vedello and Novazza deposits (Lombardian Alps), the onset of hydrothermalism is constrained to 275 ± 13 Ma (Early-Mid Permian), i.e., it was virtually contemporaneous to the plutonism and the volcanic-sedimentary cycle reported in the same area (Orobic Basin). The youngest iron-mineralizing event is represented by siderite veins and conformable orebodies hosted in Lower Triassic shallow-marine carbonatic successions. In this case, the siderite-forming fluids contained a seawater component, interacted with the underlying Permian successions and eventually replaced the marine carbonates at temperatures of ≥ 250 °C. The absence of siderite in younger rocks suggests an Early Triassic




    Full Text Available A Jurassic- Cretaceous carbonate succession crops out along the Zyghosti Rema, Kozani (Northern Greece. The substratum consists of the ophiolitic succession of the Vourinos Massif (Pelagonian Domain: serpentinites tectonically overlain by basalts, with thin lenses of radiolarian cherts of middle Bathonian age. The contact with the overlying Jurassic limestones is tectonic. Eight informal units have been distinguished within the Mesozoic limestones, from the base upwards. (A bioclastic, intraclastic and oolitic packstone (Callovian- Oxfordian. (B bioclastic packstone and coral boundstone (Oxfordian . (C bioclastic and oncoidal wackestone with Clypeina jurassica (Oxfordian- Upper Kimmeridgian. (D (Upper Kimmeridgian- Portlandian: oncoidal packstone and rudstone (facies D1; intraclastic and bioclastic grainstone and packstone (facies D2; neptunian dykes with intraclastic and bioclastic wackestone and packstone filling (facies D3; neptunian dykes with Fe-Mn rich laterite filling and with pink silty filling of early Late Cretaceous age. An unconformity surface, due to emersion and erosion of the platform during the latest Jurassic- Early Cretaceous, is overlain by (E intraclastic, bioclastic packstone and grainstone (Cenomanian. (F massive body of debrites with coral, echinoderm, algae and rudist large clasts (facies F1 (Cenomanian; turbiditic beds of bioclastic, intraclastic and lithoclastic rudstone and grainstone (facies F2. (G thin bedded bioclastic mudstone and wackestone with planktonic foraminifers and radiolarians, alternating with turbiditic beds of bioclastic, intraclastic packstone and rudstone and with conglomeratic levels and slumped beds of the previous turbidites (upper Santonian- lower Campanian. (H: bioclastic packstone with planktonic foraminifers (facies H1 (lower Campanian - ?Maastrichtian; amalgamated turbiditic beds of bioclastic wackestone and packstone with planktonic foraminifers (facies H2; turbiditic beds of bioclastic

  14. NKS NordRisk. Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Havskov Soerensen, J.; Baklanov, A.; Mahura, A. (Danish Meteorological Institute, Copenhagen (Denmark)); Lauritzen, Bent; Mikkelsen, Torben (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark))


    Within the NKS NordRisk project, 'Nuclear risk from atmospheric dispersion in Northern Europe', the NKS NordRisk Atlas has been developed. The atlas describes risks from hypothetical long-range atmospheric dispersion and deposition of radionuclides from selected nuclear risk sites in the Northern Hemisphere. A number of case studies of long-term long-range atmospheric transport and deposition of radionuclides has been developed, based on two years of meteorological data. Radionuclide concentrations in air and radionuclide depositions have been evaluated and examples of long-term averages of the dispersion and deposition and of the variability around these mean values are provided. (au)

  15. Lithologic controls on mineralization at the Lagunas Norte high-sulfidation epithermal gold deposit, northern Peru

    Cerpa, Luis M.; Bissig, Thomas; Kyser, Kurt; McEwan, Craig; Macassi, Arturo; Rios, Hugo W.


    The 13.1-Moz high-sulfidation epithermal gold deposit of Lagunas Norte, Alto Chicama District, northern Peru, is hosted in weakly metamorphosed quartzites of the Upper Jurassic to Lower Cretaceous Chimú Formation and in overlying Miocene volcanic rocks of dacitic to rhyolitic composition. The Dafne and Josefa diatremes crosscut the quartzites and are interpreted to be sources of the pyroclastic volcanic rocks. Hydrothermal activity was centered on the diatremes and four hydrothermal stages have been defined, three of which introduced Au ± Ag mineralization. The first hydrothermal stage is restricted to the quartzites of the Chimú Formation and is characterized by silice parda, a tan-colored aggregate of quartz-auriferous pyrite-rutile ± digenite infilling fractures and faults, partially replacing silty beds and forming cement of small hydraulic breccia bodies. The δ34S values for pyrite (1.7-2.2 ‰) and digenite (2.1 ‰) indicate a magmatic source for the sulfur. The second hydrothermal stage resulted in the emplacement of diatremes and the related volcanic rocks. The Dafne diatreme features a relatively impermeable core dominated by milled slate from the Chicama Formation, whereas the Josefa diatreme only contains Chimú Formation quartzite clasts. The third hydrothermal stage introduced the bulk of the mineralization and affected the volcanic rocks, the diatremes, and the Chimú Formation. In the volcanic rocks, classic high-sulfidation epithermal alteration zonation exhibiting vuggy quartz surrounded by a quartz-alunite and a quartz-alunite-kaolinite zone is observed. Company data suggest that gold is present in solid solution or micro inclusions in pyrite. In the quartzite, the alteration is subtle and is manifested by the presence of pyrophyllite or kaolinite in the silty beds, the former resulting from relatively high silica activities in the fluid. In the quartzite, gold mineralization is hosted in a fracture network filled with coarse alunite

  16. Could Poor Fens BE More Sensitive than Bogs to Elevated N Deposition in the Oil Sands Region of Northern Alberta?

    Wieder, R. K.; Vile, M. A.; Scott, K. D.


    Bogs and fens cover 29% of the 140,000 km2 Oil Sands Administrative Area (OSAA) in northern Alberta, a region characterized by quite low background N deposition (1-2 kg/ha/yr). However, development of the oil sands resource has led to increasing emission of nitrogen oxides, which are then returned to regional ecosystems as elevated atmospheric N deposition. Given the nutrient deficient nature of bogs and poor fens, elevated N deposition from oil sands development could potentially affect peatland ecosystem structure and function. To evaluate the ecosystem-level effects of N deposition, since 2011, we have experimentally applied N to a bog and a poor fen near Mariana Lakes, Alberta, located far enough from the OSAA to be unaffected by oil sands emissions. Treatments include simulated rainfall equivalent to N deposition of 0, 5, 10, 15, 20, and 25 kg/ha/yr, plus control plots receiving no added water (3 replicate plots per site per N treatment). Concentrations of NH4+-N, NO3- N, and DON at the top of the peatland water table did not increase with increasing N deposition, averaging 0.61, 0.09, and 1.07 mg/L, respectively, in the bog, and 0.53, 0.10, and 0.81 mg/L, respectively, in the poor fen. Ericaceous shrub abundance increased with increasing N deposition in both the bog and the poor fen, although plot-scale greenness (hand-held spectral measurement of the Normalized Difference Red Edge (NDRE) index) increased with N deposition in the poor fen, but not in the bog. Segmented regression indicated that in the poor fen, at N deposition above 14-16 kg/ha/yr, total microbial, bacterial, and fungal biomass in the top 5 cm of peat increased with N deposition, with no effect at lower N deposition. No effect of N deposition on microbial, bacterial, or fungal biomass was observed at 5-10 cm in the poor fen, or at either 0-5 or 5-10 cm in the bog. In the poor fen, microbial, bacterial, and fungal biomass increased with NDRE, but the effect was not significant in the bog

  17. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Smith Korsholm, Ulrik; Astrup, Poul; Lauritzen, Bent;

    The present atlas has been developed within the NKS/NordRisk-II project "Nuclear risk from atmospheric dispersion in Northern Europe". The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere...

  18. Thermal Evolution of Organic Matter and Secondary Hydrocarbon Generation from Upper Paleozoic Coal Deposits in Northern China


    The metamorphism and hydrocarbon generation from the Upper Paleozoic coal-bearing strata in Northern China have been widely studied by Chinese geologists since the 1990s.Based on a large amount of data of Ro values, combined with geological background, we have systematically analyzed the thermal evolutionary characteristics of organic matter and the stages of hydrocarbon generation from the Permo-Carboniferous coal deposits and discussed the condition of secondary hydrocarbon generation.The distribution range of secondary hydrocarbon generation in Northern China is thus determined.It is shown that the coal ranks of the Upper Paleozoic coal deposits are higher in the southern and western belts than those in the northern and eastern belts.Really significant secondary hydrocarbon generation is mainly related to the thermal evolution of organic matter during the Himalayan Period.Profitable areas for secondary hydrocarbon generation should be buried at 3000-4000 m up to the present.Maturity of the Permo-Carboniferous source rocks is not very high.It is suggested that the Bohai Bay depression is favourable for secondary hydrocarbon generation and has good oil and gas prospects.

  19. Simulated atmospheric N deposition alters fungal community composition and suppresses ligninolytic gene expression in a northern hardwood forest.

    Ivan P Edwards

    Full Text Available High levels of atmospheric nitrogen (N deposition may result in greater terrestrial carbon (C storage. In a northern hardwood ecosystem, exposure to over a decade of simulated N deposition increased C storage in soil by slowing litter decay rates, rather than increasing detrital inputs. To understand the mechanisms underlying this response, we focused on the saprotrophic fungal community residing in the forest floor and employed molecular genetic approaches to determine if the slower decomposition rates resulted from down-regulation of the transcription of key lignocellulolytic genes, by a change in fungal community composition, or by a combination of the two mechanisms. Our results indicate that across four Acer-dominated forest stands spanning a 500-km transect, community-scale expression of the cellulolytic gene cbhI under elevated N deposition did not differ significantly from that under ambient levels of N deposition. In contrast, expression of the ligninolytic gene lcc was significantly down-regulated by a factor of 2-4 fold relative to its expression under ambient N deposition. Fungal community composition was examined at the most southerly of the four sites, in which consistently lower levels of cbhI and lcc gene expression were observed over a two-year period. We recovered 19 basidiomycete and 28 ascomycete rDNA 28S operational taxonomic units; Athelia, Sistotrema, Ceratobasidium and Ceratosebacina taxa dominated the basidiomycete assemblage, and Leotiomycetes dominated the ascomycetes. Simulated N deposition increased the proportion of basidiomycete sequences recovered from forest floor, whereas the proportion of ascomycetes in the community was significantly lower under elevated N deposition. Our results suggest that chronic atmospheric N deposition may lower decomposition rates through a combination of reduced expression of ligninolytic genes such as lcc, and compositional changes in the fungal community.

  20. General geology, alteration, and iron deposits in the Palaeoproterozoic Misi region, northern Finland

    Tero Niiranen


    Full Text Available The Paleoproterozoic Misi region forms the northeastern part of the Peräpohja Schist Belt in northern Finland. The area comprises mafic volcanic and sedimentary rocks, differentiated gabbros, and late-orogenic granitoids. Three geochemically different mafic volcanic units were recognised: LREE-depleted amygdaloidal lavas, slightly LREE-enriched lavas, and mafic tuffs that have a flat REE pattern. Sedimentary rocks include arkosites, mica gneisses, dolomitic marbles, quartzites, tuffites, mica schists, calc-silicate rocks and graphite-bearing schists. Two types of gabbros wereidentified: one with a LREE-enriched pattern and another with flat REE pattern. The age of the former is according to Perttunen and Vaasjoki (2001 2117±4 Ma, whereas there is no age determination for the latter. The granitoid intrusions belong to the ca. 1800 Malate-orogenic group of the Central Lapland Granitoid Complex. The geochemistry and the stable isotope data on mafic lavas and dolomitic marbles show similarities with the mafic volcanic rocks and marbles of the lower part of the Kivalo group in the western part of Peräpohja Schist Belt. Peak metamorphic conditions in the region vary from upper-greenschist to upper-amphibolite facies. Three major stages of deformation were distinguished: N-S compressional D1 with ductile deformation, NE-SW compressional D2 with ductile to brittle-ductile deformation, and E-W compressional D3 with brittle deformation. Several magnetite occurrences are known in the region and four of those have been mined for iron. The ores are mainly composed of magnetite with minor haematite, pyrite, chalcopyrite and bornite. Besides iron, the ores contain small amounts of P, S and V aswell as trace amounts of Cu, Co, Te and Au. The magnetite bodies are hosted by skarnoids within the ca. 2220–2120 Ma dolomitic marble-quartzite sequence, and highly differentiated, intensely albitised, LREE-enriched gabbro. Multistage and -type alteration is

  1. Mineralogical and geochemical constraints on the genesis of the carbonate - Hosted Jebel Ghozlane Pb–Zn deposit, Nappe zone, Northern Tunisia

    Jemmali, Nejib; Souissi, Fouad; Carranza, Emmanuel John M.; Vennemann, Torsten W.


    The Pb–Zn deposit at Jebel Ghozlane, in the Nappe zone (northern Tunisia), is hosted by Triassic dolostones and Eocene limestones and is located along faults and a thrust-sheet boundary. The sulfide mineralization of the deposit consists mainly of galena and sphalerite and occurs as vein, stockwork,

  2. The distinction of submarine mass failure deposits from tsunami backwash deposits - an example from Hornitos, Northern Chile

    Spiske, M.; Bahlburg, H.; Weiss, R.


    Sedimentary features of onshore tsunami deposits were studied in great detail within the last decade. While the characteristics of such onshore deposits are well documented, the associated marine tsunami effects, such as sediment dispersion, re-deposition, and sediment bypassing during runup and backwash are scarcely reported. The knowledge of the appearance of submarine tsunami features is important, not only to understand the hydrodynamic processes involved, but also because pre-Quaternary sediments tend to be of marine origin when extending the geological record farther into the past. In this study we challenge the former interpretation of a backwash tsunami origin of a Pliocene coarse clast unit at Hornitos that was previously linked to the Eltanin impact tsunami. The respective unit contains several tens of meters long rock slabs and components from both the shallow marine basin and onshore environments, such as alluvial fans, beaches, cliffs and the local basement rocks. It is intercalated into breccia layers of smaller scale that represent the likewise energetic background sedimentation. The unit was most likely emplaced by a high-density flow with possible hydroplaning at its base and front. This is underlined by soft-sediment deformation and sand dykes. The comparison to recent submarine tsunami sediments shows that there are hardly any similarities, most notably because the unit at Hornitos was deposited en masse without any obvious trends. Our re-interpretation considers the local synsedimentary tectonic background and a comparison to recent submarine tsunami sediments caused by tsunamis with similar onshore wave heights. We show that a relation to the Eltanin impact can be excluded because enhanced models that include a shoaling effect as soon as the tsunami approaches shallow shelf regions prove that such an impact did not entail large onshore wave heights at Hornitos. Additionally, the biostratigraphic age of the La Portada formation is not

  3. Why "in dubio pro" tsunami deposits does not work: Two examples from northern Chile

    Bahlburg, Heinrich; Spiske, Michaela; Weiss, Robert


    The recognition of tsunami deposits in the geological record is hampered because there are no unique sedimentological criteria that clearly define tsunami sediments, and tsunami deposits have a very limited preservation potential. We present observations on two alleged tsunami deposits exposed at the Chilean coast north of Antofagasta, at Caleta Herradura and Hornitos, of Miocene and Plio-Pleistocene age, respectively. These we interpret to be in fact mass flow sediments unrelated to any kind of tsunami depositional process. At Caleta Herradura, Cantalamessa and Di Celma (2005) interpreted mass flow deposits arranged in a Lower and Upper Unit as the product shallow marine tsunami backwash. However, the deposits in question occur in a coeval graben as intercalations between shoreface deposits. Tracing the deposit across the downthrowing graben margin faults, we did not find any evidence of described "abrupt" lateral changes in depositional facies. When the Lower Unit is traced towards the graben margin it increases in thickness and the association to synsedimentary downthrowing faults becomes evident. The Upper Unit is described as being "distributed more widely than the Lower Unit and, where the Lower Unit is absent, it succeeds directly the lower shoreface deposits." We disagree. The Upper Unit tapers out eastward against the inclined upper depositional surface of the Lower Unit. We interpret the Lower Unit as a debris flow alluvial fan and fan delta deposit of the graben margin which was itself affected by synsedimentary downthrow activity. If the debris flow deposits are restored for the downthrows realized along the numerous faults, it becomes apparent that the alleged tsunami backwash deposit of the Lower Unit represents the distal part of a physically continuous coarse alluvial wedge thinning westward and towards the graben center. The Upper Unit represents a debris flow deposit at least the matrix of which was derived from marine sediments within the graben

  4. Ordovician sponges (Porifera and other silicifications from Baltica in Neogene and Pleistocene fluvial deposits of the Netherlands and northern Germany

    Rhebergen, Freek


    Full Text Available Fluvial deposits of Miocene to Early Pleistocene age in Germany and the Netherlands were laid down in the delta of the Eridanos River System, but the exact provenance of this material continues to be a subject of discussion. The aim of the present study is twofold. Firstly, a comparison of Ordovician sponges in these deposits with those from northern Estonia and the St Petersburg region (Russia demonstrates that these erratics originated from the drainage area of the Pra Neva, a tributary of the Eridanos. Secondly, the importance of Late Ordovician silicified boulders, which yield forms of preservation that are unknown in comparable fossils, preserved in situ, is outlined. Some recommendations for future studies are made.

  5. The role of bitumen in strata-bound copper deposit formation in the Copiapo area, Northern Chile

    Cisternas, M. Eugenia; Hermosilla, Juan


    In northern Chile, between 27 and 33°S, there are numerous deposits where residual petroleum is associated with Cu-(Ag) mineralisation (the most famous being El Soldado). All of these deposits are hosted by Lower Cretaceous volcanic or volcanoclastic facies along the axis of a former backarc basin. This close relationship suggests that the generation, migration and emplacement of hydrocarbons in the Cretaceous volcanic units is a regional process, associated with the evolution of the Cretaceous backarc basin and points to the importance of pyrobitumen as an exploration tool for similar Cu-(Ag) deposits. The present work analyses four small strata-bound copper deposits located along a north-south belt approximately 10 km east of Copiapó in northern Chile. These deposits are typically hosted by pyrobitumen-rich andesitic volcanic to volcanoclastic rocks intercalated with the marine carbonate Pabellón Formation, the youngest formation within the Chañarcillo Group. The strong genetic and spatial relationships between the pyrobitumen-rich lavas and the mineral deposits allow us to define this volcanic belt as the Ocoita-Pabellón Metallotect. Two hydrothermal events can be distinguished based on the mineralogical, textural, fluid inclusion and isotope data of ore and gangue and on the optical properties of residual petroleum. During the early event, petroleum was mobilised from the source rocks into the primary and secondary porosity of the lavas by Fe-rich hydrothermal fluids, which precipitated pyrite as an early sulphide phase. The second event is characterised by Cu-rich hydrothermal fluids, which induced three successive sub-stages of Cu-sulphide precipitation. The hydrothermal fluids chemically and thermally altered the first-stage bitumen, transforming it into pyrobitumen. The present work documents similarities between the Ocoita-Pabellón Metallotect and the El Soldado ore deposit and emphasises important differences. In the El Soldado host rocks, a

  6. Detailed 40Ar/39Ar dating of geologic events associated with the Mantos Blancos copper deposit, northern Chile

    Oliveros, Verónica; Féraud, Gilbert; Aguirre, Luis; Ramírez, Luis; Fornari, Michel; Palacios, Carlos; Parada, Miguel


    The 40Ar/39Ar geochronological method was applied to date magmatic and hydrothermal alteration events in the Mantos Blancos mining district in the Coastal Cordillera of northern Chile, allowing the distinction of two separate mineralization events. The Late Jurassic Mantos Blancos orebody, hosted in Jurassic volcanic rocks, is a magmatic-hydrothermal breccia-style Cu deposit. Two superimposed mineralization events have been recently proposed. The first event is accompanied by a phyllic hydrothermal alteration affecting a rhyolitic dome. The second mineralization event is related to the intrusion of bimodal stocks and sills inside the deposit. Because of the superposition of several magmatic and hydrothermal events, the obtained 40Ar/39Ar age data are complex; however, with a careful interpretation of the age spectra, it is possible to detect complex histories of successive emplacement, alteration, mineralization, and thermal resetting. The extrusion of Jurassic basic to intermediate volcanic rocks of the La Negra Formation is dated at 156.3 ± 1.4 Ma (2 σ) using plagioclase from an andesitic lava flow. The first mineralization event and associated phyllic alteration affecting the rhyolitic dome occurred around 155-156 Ma. A younger bimodal intrusive event, supposed to be equivalent to the bimodal stock and sill system inside the deposit, is probably responsible for the second mineralization event dated at ca. 142 Ma. Other low-temperature alteration events have been dated on sericitized plagioclase at ca. 145-146, 125, and 101 Ma. This is the first time that two distinct mineralization events have been documented from radiometric data for a copper deposit in the metallogenic belt of the Coastal Cordillera of northern Chile.

  7. Coastal plain and fluvial deposits in the tertiary of central and northern Spain

    Moechtar, H.


    The Ebro Basin represents purely fluvial deposition with a relatively high, but steady tectonic activity in relation to uplift of the Pyrenees and thrust fault activity. The cyclic pattern in the fluvial deposits can be attributed to Milankovitch related climatological changes. In the Loranca Basin

  8. Modelling impacts of climate and deposition changes on nitrogen fluxes in northern catchments of Norway and Finland

    Ø. Kaste


    Full Text Available The Integrated Nitrogen model for Catchments (INCA was applied to three upland catchments in Norway and Finland to assess the possible impacts of climate change and nitrogen (N deposition on concentrations and fluxes of N in streamwater in cold regions of Europe. The study sites cover gradients in climate and N deposition from the southern boreal Øygard Brook (2.6 km2 in SW Norway, via the southern/middle boreal Simojoki River (3610 km2 in northern Finland to the sub-arctic Dalelva Brook (3.2 km2 in northern Norway. The INCA scenario simulations included future N deposition scenarios (current legislation and maximum feasible reduction and climate scenarios for 2050 (ECHAM4/OPYC3; HadCM3 treated separately and in combination. As a result of climate change, the INCA model predicted markedly reduced duration and amounts of snow cover in all catchments. The occurrence of winter rainfall and melting periods was predicted to become more frequent so that more frequent floods in winter will to a large extent replace the regular snowmelt flood in spring. At the northernmost catchment, Dalelva, the predicted temperature increase might result in a doubling of the net mineralisation rate, thereby greatly increasing the amount of available inorganic N. At all catchments, the increased N supply was predicted to be largely balanced by a corresponding increase in N retention, and relatively small increases in NO3- leaching rates were predicted. This dynamic relationship is, however, strongly dependent on the temperature responses of the key N transformation processes modelled. A future reduction in N emissions and deposition, as agreed under current legislation, would have pronounced effects on concentrations of NO3- in streamwater at the southernmost catchment, Øygard, even following a climate change around 2050. At the more remote Dalelva and Simojoki catchments, the N emission reductions will be small compared to the internal N recycling processes, and

  9. Gold deposits of the northern margin of the North China craton: Multiple late Paleozoic-Mesozoic mineralizing events

    Hart, C.J.R.; Goldfarb, R.J.; Qiu, Y.; Snee, L.; Miller, L.D.; Miller, M.L.


    The northern margin of the North China craton is well-endowed with lode gold deposits hosting a resource of approximately 900 tonnes (t) of gold. The ???1,500-km-long region is characterized by east-trending blocks of metamorphosed Archean and Proterozoic strata that were episodically uplifted during Variscan, Indosinian, and Yanshanian deformational and magmatic events. At least 12 gold deposits from the Daqinshan, Yan-Liao (includes the Zhangjiakou, Yanshan, and Chifeng gold districts), and Changbaishan gold provinces contain resources of 20-100 t Au each. Most deposits are hosted in uplifted blocks of Precambrian metamorphic rocks, although felsic Paleozoic and Mesozoic plutons are typically proximal and host ???30% of the deposits. The lodes are characterized by sulfide-poor quartz veins in brittle structures with low base metal values and high Au:Ag ratios. Although phyllic alteration is most common, intensive alkali feldspar metasomatism characterizes the Wulashan, Dongping, and Zhongshangou deposits, but is apparently coeval with Variscan alkalic magmatism only at Wulashan. Stepwise 40Ar-39Ar geochronology on 16 samples from gangue and alteration phases, combined with unpublished SHRIMP U-Pb dates on associated granitoids, suggest that gold mineralizing events occured during Variscan, Indosinian, and Yanshanian orogenies at circa 350, 250, 200, 180, 150, and 129 Ma. However, widespread Permo-Triassic (???250 Ma) and Early Jurassic (???180 Ma) thermal events caused variable resetting of most of the white mica and K-feldspar argon spectra, as well as previously reported K-Ar determinations. Compiled and new stable isotope and fluid inclusion data show that most ??18O values for ore-stage veins range from 8 to 14???, indicating a fluid in equilibrium with the Precambrian metamorphic basement rocks; ??D values from fluid inclysions range widely from -64 to -154???, which is indicative of a local meteoric component in some veins; and highly variable ??34S data

  10. Organic geochemistry of Amynteo lignite deposit, northern Greece: a Multi-analytical approach

    Iordanidis, A.; Schwarzbauer, J.; Georgakopoulos, A.; Lagen, van B.


    Several lignite samples were collected from boreholes of the Amynteo opencast lignite mine, northern Greece. Organic geochemical characteristics were investigated with the help of various analytical techniques, comprising Gas Chromatography (GC) and Gas-chromatography-Mass Spectrometry (GC-MS), Four

  11. Deep water bottom current deposition in the northern South China Sea


    There are some active bottom currents on the northern continental slope of the South China Sea (SCS). Reflection seismic profiles show that the bottom current channels occur in the water depth range of 1000 to 2700 m,extending from the NE to the SW,leading to accumulation of discontinuous drifts with higher sedimentation rates on the eastern side of the channel. The stacking pattern of the layers sug-gests that these drifts propagated southwestward,following the direction of the bottom currents. One sedimentary drift to the southeast of the Dongsha Islands has the highest sedimentation rate of 97cm/ka in the last 12 ka. The sedimentary characteristics of the sediment layers indicate that these bottom currents are most likley caused by the water movement of a branch of the West Pacific Ocean Current,which enters the northern SCS via the Bashi Strait. Once formed,the bottom currents trans-port sediments along the northern slope of SCS southwestward and finally disappear into the central basin of the SCS. Due to the bottom current activity,the deep-sea sedimentary process in the northern SCS is complex.

  12. Atmospheric deposition of N, P and Fe to the Northern Indian Ocean: implications to C- and N-fixation.

    Srinivas, Bikkina; Sarin, M M


    This study presents the first data set on atmospheric input of N, P and Fe to the Northern Indian Ocean. Based on the chemical analysis of ambient aerosols, collected from the marine atmospheric boundary layer (MABL) during the continental outflow (January-April), we document that dry-deposition fluxes (μmolm(-2) d(-1)) of N (2-167), P (0.5-4.8) and Fe (0.02-1.2) to the Bay of Bengal are significantly higher compared to those over the Arabian Sea [N: 0.2-18.6; P: 0.3-0.9; Fe: 0.001-0.015]. Using atmospherically derived P and Fe, C-fixation (1.1 Pg yr(-1)) in the Bay of Bengal is dominated by anthropogenic sources. In contrast, C-fixation (0.03 Pg yr(-1)) in the Arabian Sea is limited by P and Fe. This is attributed to the poor fractional solubility of atmospheric mineral dust transported to the Arabian Sea. However, N-fixation by diazotrophs in the two oceanic regions is somewhat similar (0.5 Tg yr(-1)). Our estimate of N-deposition (0.2 Tg yr(-1)) to the Northern Indian Ocean is significantly lower compared to model results (~800-1200 mg-Nm(-2)yr(-1)≈5.7-8.6 Tg yr(-1) by Duce et al. (2008); ~4.1 Tg yr(-1) by Okin et al. (2011); ~0.8 Tg yr(-1) by Kanakidou et al. (2012)). An overestimate of N-deposition by models could arise due to inappropriate parameterization of temporal variability associated with the continental outflow spread over only four months.

  13. The role of the Antofagasta-Calama Lineament in ore deposit deformation in the Andes of northern Chile

    Palacios, Carlos; Ramírez, Luis E.; Townley, Brian; Solari, Marcelo; Guerra, Nelson


    During the Late Jurassic-Early Oligocene interval, widespread hydrothermal copper mineralization events occurred in association with the geological evolution of the southern segment of the central Andes, giving rise to four NS-trending metallogenic belts of eastward-decreasing age: Late Jurassic, Early Cretaceous, Late Paleocene-Early Eocene, and Late Eocene-Early Oligocene. The Antofagasta-Calama Lineament (ACL) consists of an important dextral strike-slip NE-trending fault system. Deformation along the ACL system is evidenced by a right-lateral displacement of the Late Paleocene-Early Eocene metallogenic belts. Furthermore, clockwise rotation of the Early Cretaceous Mantos Blancos copper deposit and the Late Paleocene Lomas Bayas porphyry copper occurred. In the Late Eocene-Early Oligocene metallogenic belt, a sigmoidal deflection and a clockwise rotation is observed in the ACL. The ACL is thought to have controlled the emplacement of Early Oligocene porphyry copper deposits (34-37 Ma; Toki, Genoveva, Quetena, and Opache), whereas it deflected the Late Eocene porphyry copper belt (41-44 Ma; Esperanza, Telégrafo, Centinela, and Polo Sur ore deposits). These observations suggest that right-lateral displacement of the ACL was active during the Early Oligocene. We propose that the described structural features need to be considered in future exploration programs within this extensively gravel-covered region of northern Chile.

  14. Prospecting for clay minerals within volcanic successions: Application of electrical resistivity tomography to characterise bentonite deposits in northern Sardinia (Italy)

    Longo, V.; Testone, V.; Oggiano, G.; Testa, A.


    Electrical resistivity tomography (ERT) is applied to prospect for and characterise a bentonitic clay deposit in northern Sardinia. Sardinian bentonites derived from the hydrothermal alteration of thick successions of pyroclastic flows and epiclastites are associated with the Oligo-Miocene calc-alkaline volcanic cycle. The alteration of these rocks is generally controlled by faults that control the local circulation of hydrothermal fluids. Two-dimensional ERT investigations were performed close to a faulted area to define the location, thickness and lateral continuity of the clayey body, and determine how it relates to faulting and stratigraphy. A line-based three-dimensional ERT data acquisition was carried out in a selected area to estimate the available clay reserves. The reliability of these resistivity models was assessed by comparison with local borehole data. Finally, the interpretation of the ERT results was optimised through synthetic modelling of the electrical resistivity imaging technique. The results define the extent and geometry of the bentonitic deposit with good accuracy and outline the scenarios where the ERT method may provide optimal results when prospecting for clay deposits.

  15. Mass transport deposits and processes in the north slope of the Xisha Trough, northern South China Sea

    QIN Zhiliang; WU Shiguo; WANG Dawei; LI Wei; GONG Shaojun; MI Lijun; SPENCE George


    Triple mass-transport deposits (MTDs) with areas of 625, 494 and 902 km2, respectively, have been identified on the north slope of the Xisha Trough, northern South China Sea margin. Based on high-resolution seismic reflection data and multi-beam bathymetric data, the Quaternary MTDs are characterized by typical geometric shapes and internal structures. Results of slope analysis showed that they are developed in a steep slope ranging from 5° to 35°. The head wall scarps of the MTDs arrived to 50 km in length (from headwall to termination). Their inner structures include well developed basal shear surface, growth faults, stepping lateral scarps, erosion grooves, and frontal thrust deformation. From seismic images, the central deepwater channel system of the Xisha Trough has been filled by interbedded channel-levee deposits and thick MTDs. Therefore, we inferred that the MTDs in the deepwater channel system could be dominated by far-travelled slope failure deposits even though there are local collapses of the trough walls. And then, we drew the two-dimensional process model and three-dimensional structure model diagram of the MTDs. Combined with the regional geological setting and previous studies, we discussed the trigger mechanisms of the triple MTDs.

  16. Pliocene and Quaternary Deposits in the Northern Part of the San Juan Basin in Southwestern Colorado and Northwestern New Mexico

    Scott, Glenn R.; Moore, David W.


    Unconsolidated late Cenozoic deposits in the northern part of the San Juan Basin range in age from late Pliocene to Holocene. Most of the deposits are alluvial gravel composed of resistant quartzite, sandstone, and igneous, metamorphic, and volcanic rocks derived from the uplifted central core of the San Juan Mountains 20-50 miles (32-80 kilometers) north of the basin. Alluvial deposits are most voluminous in the Animas Valley, but deposits of gravel of the same general age are present in the La Plata, Florida, Los Pinos, and Piedra River valleys as well. Alluvial gravel forms tabular deposits, generally about 20 feet (6 meters) thick, that are exposed beneath a sequence of terraces at many levels above the rivers. Gravel layers 360 feet (110 meters) or less above the Animas River are glacial outwash. The gravel layers begin at the south toes of end moraines and extend discontinuously downvalley at least 10-20 miles (16-32 kilometers). Farther south, distinction between outwash and nonglacial alluvium is problematical. Alluvial gravel beneath higher terraces does not grade to end moraines. Glacial till forms a series of end moraines at the north edge of the town of Durango. The oldest moraines are farthest downvalley, are higher above the river, and have more mature surficial soils than do moraines farther north. The two youngest moraines, the Animas City moraines, are interpreted to be Pinedale in age. They have narrow, ridgelike crests and form nearly unbroken arcs across the valley floor. Small segments of still more weathered moraines, the Spring Creek moraines, are 170-230 feet (52-70 meters) above the river and are 660-990 feet (200-300 meters) farther downvalley. The oldest moraines, the Durango moraines, are on the north end of the unnamed mesa on which Fort Lewis College is located. The base is about 180 feet (55 meters) above the river. These oldest moraines may be of Bull Lake age. Alluvial fans, pediment gravel, and landslides are scattered at several

  17. Upper Paleozoic glacigenic deposits of Gondwana: Stratigraphy and paleoenvironmental significance of a tillite succession in Northern Victoria Land (Antarctica)

    Cornamusini, Gianluca; Talarico, Franco M.; Cirilli, Simonetta; Spina, Amalia; Olivetti, Valerio; Woo, Jusun


    Late Paleozoic glacial deposits are widespread in Gondwana. In Antarctica the best outcrops occur in the Central Transantarctic Mountains, Ellsworth Mountains, Pensacola Mountains, and in Southern Victoria Land, whereas they are rare and very scattered in Northern Victoria Land, which represents a linkage sector with Tasmania and eastern Australia. The aim of the present research is to define the stratigraphic setting and the environmental interpretation of a poorly studied Lower Permian glacigenic succession located near Orr Glacier in the Lanterman Range in Northern Victoria Land. It has great importance because it represents the only significant glacigenic succession for this wide area, marking and defining time and modality of a glacial-postglacial transition during the early Permian, a critical time-interval in the paleoenvironmental evolution of southern Gondwana. This succession, named here as the Lanterman Formation, lies directly on to crystalline basement, and is overlain by a thick Permian fluvial succession (Takrouna Formation). The results provided by sedimentological facies analysis and palynological analysis, integrated with a limited petrographic characterization, show a correlation framework between two isolated successions, outlining their stratigraphic architecture and subdivided into a lower glacial portion and an upper postglacial portion. The former, Asselian in age, is dominated by diamictite, sandstone, mudstone with lonestones, and carbonate deposits, suggesting repeated advance and retreat of a terrestrial glacier, with facies associations indicating environmental changes from subglacial to glaciofluvial, to glaciolacustrine. The latter is dominated by lacustrine mudstone with decreasing lonestones upward, thin bedded sandstone, conglomerate and a thick fluvial sandstone and pebbly sandstone succession at the top, signalling the transition to a fluvial system through time. The overall dataset suggests that the late Paleozoic glacigenic

  18. Genesis of Middle Miocene Yellowstone hotspot-related bonanza epithermal Au-Ag deposits, Northern Great Basin, USA

    Saunders, J. A.; Unger, D. L.; Kamenov, G. D.; Fayek, M.; Hames, W. E.; Utterback, W. C.


    Epithermal deposits with bonanza Au-Ag veins in the northern Great Basin (NGB) are spatially and temporally associated with Middle Miocene bimodal volcanism that was related to a mantle plume that has now migrated to the Yellowstone National Park area. The Au-Ag deposits formed between 16.5 and 14 Ma, but exhibit different mineralogical compositions, the latter due to the nature of the country rocks hosting the deposits. Where host rocks were primarily of meta-sedimentary or granitic origin, adularia-rich gold mineralization formed. Where glassy rhyolitic country rocks host veins, colloidal silica textures and precious metal-colloid aggregation textures resulted. Where basalts are the country rocks, clay-rich mineralization (with silica minerals, adularia, and carbonate) developed. Oxygen isotope data from quartz (originally amorphous silica and gels) from super-high-grade banded ores from the Sleeper deposit show that ore-forming solutions had δ 18O values up to 10‰ heavier than mid-Miocene meteoric water. The geochemical signature of the ores (including their Se-rich nature) is interpreted here to reflect a mantle source for the “epithermal suite” elements (Au, Ag, Se, Te, As, Sb, Hg) and that signature is preserved to shallow crustal levels because of the similar volatility and aqueous geochemical behavior of the “epithermal suite” elements. A mantle source for the gold in the deposits is further supported by the Pb isotopic signature of the gold ores. Apparently the host rocks control the mineralization style and gangue mineralogy of ores. However, all deposits are considered to have derived precious metals and metalloids from mafic magmas related to the initial emergence of the Yellowstone hotspot. Basalt-derived volatiles and metal(loid)s are inferred to have been absorbed by meteoric-water-dominated geothermal systems heated by shallow rhyolitic magma chambers. Episodic discharge of volatiles and metal(loid)s from deep basaltic magmas mixed with

  19. Comparisons of measured and modelled ozone deposition to forests in northern Europe

    Touvinen, J. P.; Simpson, D.; Mikkelsen, Teis Nørgaard


    The performance of a new dry deposition module, developedfor the European-scale mapping and modelling of ozone flux to vegetation, was tested against micrometeorological ozone and water vapour flux measurements. The measurement data are for twoconiferous (Scots pine in Finland, Norway spruce in D...

  20. The Upper Devonian deposits in the northern part of Leon (Cantabrian Mountains, Northwestern Spain)

    Loevezijn, van G.B.S.; Raven, J.G.M.


    During the Late Devonian, deposition in the Cantabrian Mountains was largely controlled by movements along faults. By way of intermitting subsidence of the area south of the Sabero-Gordón line and the connected progradation of the coast during the Frasnian and early Famennian, three regressive seque

  1. Weathering Rind Age Assignment of Neoglacial Deposits in the Okstindan Mountains, Northern Norway

    Mahaney W. C.


    Full Text Available Previous soil stratigraphic analysis of soil morphogenesis in the Okstindan Mountains established a Late Neoglacial soil evolutionary sequence based on historically monitored and radio carbon-dated moraine positions over the last ~3.0 cal yr BP. Thus pedon evolution ranged from C/Cu→Ah/Cox/Cu→pedostratigraphic succession of Ah/C/Cu/Lb/ Cub/Ahb/Coxb/Cub pro files with a max i mum rind weathering time of ~1.0 kyr. Following successive re treat phases of Neoglacial ice, weathering rind development continued apace on moraines, each rind population recording weathering time fol lowing successive glacier still stands. The age of the youngest deposits falls within the period 1900-1910 AD, or the last 100 yrs, with variable moraine positions all documented by historical depictions of the position of the Austre Okstindan glacial lobe prior re treating to its present position. The next older group of deposits is considered to have been emplaced near the end of the LIA or around ~1800 AD, with time of rind development set at 200 yr, possibly older. The old est moraine set within the late Neoglacial sequence lies atop a pedostratigraphic column, the upper-most soil radio carbon dated at ~1.0 yr BP. Given the range of mean rind development across this thresh old of deposits, from 0.22 ±0.03 mm in the inner group, 0.66 ±0.07mm in the middle group, to 1.38 ±0.15 mm in the outer, older group, it is clear that finite measurements at several sites within a suite of deposits, some dated by radio carbon, can evenly discriminate be tween deposits in a glacial succession.

  2. Cap-shaped gastropods from Upper Jurassic and Lower Cretaceous deposits of northern East Siberia

    Guzhov, A. V.; Zakharov, V. A.


    Cap-shaped gastropods are first identified in Upper Jurassic and Lower Cretaceous sections of northern East Siberia. They belong to three new genera of the subclass Pectinibranchia ( Boreioconus gen. nov., Nixepileolus gen. nov., and Taimyroconus gen. nov.), which are identified at the species level ( B. bojarkensis sp. nov., N. depressus sp. nov., T. zakharovi sp. nov.), and several species with the open nomenclature. The genus Taimyroconus attributed to the family Calyptraeidae is considered as an ancestral form of the genus Crepidula. The stratigraphic position of each taxon is determined for several sections. The facies confinement, habitat conditions, and ethology of defined genera are considered with the analysis of their geographic distribution.

  3. Rainfall Deposition of Mercury and Other Trace Elements to the Northern Gulf of Mexico

    Krishnamurthy, N.; Landing, W. M.; Caffrey, J. M.


    Event-based (24-hour integrated) rainfall deposition of mercury, trace metals, and major ions has been monitored over the last 6 years at 3 inland locations and at a "Beach" site close to the coast over the past 2 years in the Pensacola Bay watershed to evaluate the temporal and spatial patterns in atmospheric wet deposition. Samples were analyzed for total mercury and a suite of 50 other trace elements. One goal of this project was to attempt to quantify the contribution of local emission sources to atmospheric deposition of mercury and other heavy metals. There were no significant differences in the rainfall Hg flux between the three inland sites or between nearby Mercury Deposition Network monitoring sites along the Gulf Coast. However, the inland sites saw Hg fluxes in the range of 20-46% greater than that of the Beach site for the year 2010 and two of the nearby MDN sites saw a range of 35-71% greater over the first half of 2010 compared to the Beach site. We seek to explain these differences for sites that are relatively close together geographically. Mercury deposition during the summer months is higher than other months due to higher concentrations in the rainfall and higher summer-time rainfall rates throughout the region. Multivariate statistical analysis was used to sort these trace elements into factors that represent potential sources that contribute to the rainfall chemistry. Four significant factors were identified: (1) crustal dust factor (Al, Ba, Co, Cs, Fe, Li, Si), (2) sea-salt factor (Cl, Na, Mg, Sr), (3) Cd/Zn factor (Cd, Cr, Zn, P), and (4) a "pollution" factor (acidity, nitrate, excess-sulfate, ammonia, As, Bi, Hg, Pb, Sb, Se, Sn). Using ratios of Hg to volatile trace elements and excess sulfate, we can estimate that 22-33% of the rainfall mercury fluxes could be the result of emissions from coal combustion in the region while factor analysis suggests slightly over 40%. However, we cannot definitively distinguish the impacts from local vs

  4. New insights into trace elements deposition in the snow packs at remote alpine glaciers in the northern Tibetan Plateau, China.

    Dong, Zhiwen; Kang, Shichang; Qin, Xiang; Li, Xiaofei; Qin, Dahe; Ren, Jiawen


    Trace element pollution resulting from anthropogenic emissions is evident throughout most of the atmosphere and has the potential to create environmental and health risks. In this study we investigated trace element deposition in the snowpacks at two different locations in the northern Tibetan Plateau, including the Laohugou (LHG) and the Tanggula (TGL) glacier basins, and its related atmospheric pollution information in these glacier areas, mainly focusing on 18 trace elements (Li, Be, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Nb, Mo, Cd, Sb, Cs, Ba, Tl, and Pb). The results clearly demonstrate that pronounced increases of both concentrations and crustal enrichment factors (EFs) are observed in the snowpack at the TGL glacier basin compared to that of the LHG glacier basin, with the highest EFs for Sb and Zn in the TGL basin, whereas with the highest EFs for Sb and Cd in the LHG basin. Compared with other studies in the Tibetan Plateau and surrounding regions, trace element concentration showed gradually decreasing trend from Himalayan regions (southern Tibetan Plateau) to the TGL basin (central Tibetan Plateau), and to the LHG basin (northern Tibetan Plateau), which probably implied the significant influence of atmospheric trace element transport from south Asia to the central Tibetan Plateau. Moreover, EF calculations at two sites showed that most of the heavy metals (e.g., Cu, Zn, Mo, Cd, Sb, and Pb) were from anthropogenic sources and some other elements (e.g., Li, Rb, and Ba) were mainly originated from crustal sources. MODIS atmospheric optical depth (AOD) fields derived using the Deep Blue algorithm and CALIOP/CALIPSO transect showed significant influence of atmospheric pollutant transport from south Asia to the Tibetan Plateau, which probably caused the increased concentrations and EFs of trace element deposition in the snowpack on the TGL glacier basin.

  5. Task 50 - deposition of lignites in the Fort Union Group and related strata of the northern Great Plains

    Hartman, J.H.; Roth, B.; Kihm, A.J.


    Late Cretaceous, Paleocene, and early Eocene geologic and paleontologic studies were undertaken in western North Dakota, eastern and south-central Montana, and northwestern and northeastern Wyoming. These study areas comprise the Williston, Bighorn, and Powder River Basins, all of which contain significant lignite resources. Research was undertaken in these basins because they have the best geologic sections and fossil record for the development of a chronostratigraphic (time-rock) framework for the correlation of lignite beds and other economic resources. A thorough understanding of the precise geologic age of the deposition of sediments permits a powerful means of interpreting the record of geologic events across the northern Great Plains. Such an understanding allows for rigorous interpretation of paleoenviromnents and estimates of resource potential and quality in this area of economically significant deposits. This work is part of ongoing research to document change in the composition of molluscan fossil faunas to provide a paleoenvironmentally sensitive independent means of interpreting time intervals of brief duration during the Late Cretaceous, Paleocene, and Eocene. This study focuses on the record of mollusks and, to a lesser extent, mammals in the (1) Hell Creek-Tullock Formations, which include the Cretaceous-Paleocene boundary, in the western portion of the Williston Basin, Montana; (2) uppermost Cretaceous, Paleocene, and lowermost Eocene strata in western North Dakota, which -includes the last interior seaway in North Dakota; (3) upper Paleocene and lowermost Eocene of the northern portion of the Bighorn Basin of south-central Montana and northwestern Wyoming; and (4) Powder River Basin of northeastern Wyoming and southeastern Montana. The geologic record provides different physical and paleontological information to aid in interpreting the geologic record through the study interval.

  6. Depositional setting and geochemistry of phosphorites and metalliferous black shales in the Carboniferous-Permian Lisburne Group, Northern Alaska

    Dumoulin, Julie A.; Slack, John F.; Whalen, Michael T.; Harris, Anita G.


    Phosphatic rocks are distributed widely in the Lisburne Group, a mainly Carboniferous carbonate succession that occurs throughout northern Alaska. New sedimentologic, paleontologic, and geochemical data presented here constrain the geographic and stratigraphic extent of these strata and their depositional and paleogeographic settings. Our findings support models that propose very high oxygen contents of the Permo-Carboniferous atmosphere and oceans, and those that suggest enhanced phosphogenesis in iron-limited sediments; our data also have implications for Carboniferous paleogeography of the Arctic. Lisburne Group phosphorites range from granular to nodular, are interbedded with black shale and lime mudstone rich in radiolarians and sponge spicules, and accumulated primarily in suboxic outer- to middle-ramp environments. Age constraints from conodonts, foraminifers, and goniatite cephalopods indicate that most are middle Late Mississippian (early Chesterian; early late Visean). Phosphorites form 2- to 40-cm-thick beds of sand- to pebble-sized phosphatic peloids, coated grains, and (or) bioclasts cemented by carbonate, silica, or phosphate that occur through an interval =12 m thick. High gamma-ray response through this interval suggests strongly condensed facies related to sediment starvation and development of phosphatic hardgrounds. Phosphorite textures, such as unconformity-bounded coated grains, record multiple episodes of phosphogenesis and sedimentary reworking. Sharp bed bases and local grading indicate considerable redeposition of phosphatic material into deeper water by storms and (or) gravity flows. Lisburne Group phosphorites contain up to 37 weight percent P2O5, 7.6 weight percent F, 1,030 ppm Y, 517 ppm La, and 166 ppm U. Shale-normalized rare earth element (REE) plots show uniformly large negative Ce anomalies Ce/Ce*=0.11 + or - 0.03) that are interpreted to reflect phosphate deposition in seawater that was greatly depleted in Ce due to increased

  7. Depositional environments of Laborcita Formation (Wolfcampian), northern Sacramento Mountains, New Mexico

    Fly, S.H. III


    Depositional environments that change dramatically over short lateral distances are represented by exposures of the Laborcita Formation. A siliclastic source area lay to the east and southeast, in the Pedernal Mountains. To the west, a shallow marine sea filled the orogrande basin. Alternating cycles of marine and nonmarine sedimentation resulted from fan-delta lobe shifting and eustatic sea level movements. In clear-water areas not affected by fan-deltaic sedimentation, deposits become increasingly calcareous. Various carbonate facies resulted from organisms adapting to changing environmental conditions. Mud-cracked algal mats, digitate algal stromatolites, and small phylloid red algal mounds and rhodoliths indicate deposition in shallow-water subtidal to supratidal settings. Large buildups (20 m thick) of phylloid green algae associated with abundant submarine cement occurred in a position near the edge of the narrow shelf. Widespread skeletal detritus beds overlie and extend hundreds of meters away from the massive buildups. Influx of terrigenous mud and silt in advance of a prograding fan-delta system terminated growth of the buildups. The next transgression is represented by a carbonate grainstone exhibiting characteristics of shallow-water marine, storm-dominated shelf bars. The shelf bars migrated in a northwest-southeast direction.

  8. Palaeoclimatic considerations of talus flatirons and aeolian deposits in Northern Fuerteventura volcanic island (Canary Islands, Spain)

    Gutiérrez-Elorza, Mateo; Lucha, Pedro; Gracia, F.-Javier; Desir, Gloria; Marín, Cinta; Petit-Maire, Nicole


    Fuerteventura volcanic island has been subject to considerable aeolian activity since the Late Pleistocene. The aeolian record includes inactive aeolian deposits with interbedded entisols, whose age by OSL dating ranges between 46 and 26 ky BP. The Corralejo active dune field, where sand sheets, nebkhas, coppice dunes, blowouts, barchans and transverse dunes have been described, constitutes a more recent Aeolian deposit. Here the age is about 14 ky BP. On Fuerteventura Island aeolian dust has been deposited on valleys and slopes. This last type of accumulation has been affected by gully incision, producing talus flatirons. Samples taken on the apex of these palaeo-slopes indicate an OSL age of 30 and 50 ky BP. A palaeoclimatic succession has been interpreted during which a prevailing arid period took place in OIS 4, with the accumulation of aeolian dust. A humid period occurred in OIS 2, during which slopes were dissected and formed talus flatirons. An arid period about 14 ky BP gave rise to the Corralejo dune field, which has continued until present with slight climatic oscillations.

  9. REE geochemical characteristics of the No. 302 uranium deposit in northern Guangdong, South China


    The No. 302 uranium deposit, located in Guangdong Province, is a typical granite-type uranium ore deposit. REE geochemical characteristics of the wall rocks, pitchblende, altered rocks, calcite and fluorite from this deposit have been systematically studied in this paper. The result showed that the alkali-metasomatic granites and other altered rocks have the same REE distribution patterns as Indosinian granites. It is indicated that the hydrothermal ore-forming solution had altered the Indosinian granites, and ore-forming materials may directly originate from the Indosinian granites. Calcite and fluorite of different stages are the products derived from the same source but different stages. The evolution and degassing of the mineralizing solution might induce LREE enrichment to varying degree. Mantle fluid and a large volume of mineralizer may be the crucial factors controlling uranium mineralization, and the hydrothermal solution with mineralizer played an important role in U transport and concentration. Meanwhile, the degassing of CO2 might promote U and REE precipitation.

  10. Trace elements in tourmalines from massive sulfide deposits and tourmalinites: Geochemical controls and exploration applications

    Griffin, W.L.; Slack, J.F.; Ramsden, A.R.; Win, T.T.; Ryan, C.G.


    Trace element contents of tourmalines from massive sulfide deposits and tourmalinites have been determined in situ by proton microprobe; >390 analyses were acquired from 32 polished thin sections. Concentrations of trace elements in the tourmalines vary widely, from zones are relatively homogeneous, suggesting that these trace elements are contained within the crystal structure of the tourmaline, and are not present in inclusions. The highest base metal contents are in ore-related tourmaline samples from Kidd Creek (Ontario), Broken Hill (Australia), and Sazare (Japan). Tourmaline data from these and many other massive sulfide deposits cluster by sample and display broadly linear trends on Zn vs. Fe plots, suggesting chemical control by temperature and hydrothermal and/or metamorphic fluid-mineral equilibria. Significant Ni occurs only in samples from the Kidd Creek Cu-Zn-Pb-Ag deposit, which is associated with a large footwall ultramafic body. An overall antithetic relationship between Zn and Ni probably reflects fluid source controls. Mn is correlated with Fe in tourmalines from barren associations, and possibly in some tourmalines associated with sulfide vein deposits. Sn increases systematically with Fe content irrespective of association; the highest values are found in schorls from granites. Other trace elements are generally uncorrelated with major element concentrations (e.g., Sr-Ca). Base metal proportions in the tourmalines show systematic patterns on ternary Cu-Pb-Zn diagrams that correlate well with the major commodity metals in the associated massive sulfide deposits. For example, data for tourmalines from Cu-Zn deposits (e.g., Ming mine, Newfoundland) fall mainly on the Cu-Zn join, whereas those from Pb-Zn deposits (e.g., Broken Hill, Australia) plot on the Pb-Zn join; no data fall on the Cu-Pb join, consistent with the lack of this metal association in massive sulfide deposits. The systematic relationship between base metal proportions in the

  11. Early Eocene volcanic ashes on Greifswalder Oie and their depositional environment, with an overview of coeval ash-bearing deposits in northern Germany and Denmark

    Obst, Karsten; Ansorge, Jörg; Matting, Sabine; Hüneke, Heiko


    Unconsolidated bentonites and carbonate-cemented volcanic ashes occur in northern Germany within the clay sequence of the Lamstedt and Schlieven Formations documented by several wells. Ash-bearing carbonate concretions (so-called cementstones) are also known from glacially transported rafts and erratic boulders on the Baltic Sea island Greifswalder Oie, representing the easternmost exposures of early Eocene sediments in the North Sea Basin. The ashes can be correlated with water-lain ashes of the Danish Fur and Ølst Formations (mo-clay) generated during the opening of the North Atlantic Ocean about 55 Ma ago. Two types of cementstones can be distinguished on the basis of the mineralogical composition, sedimentary features and fossil content. Greifswalder Oie type I contains a black, up to 12-cm-thick ash deposit that follows above two distinct thin grey ash layers. The major ash unit has a rather homogeneous lower part; only a very weak normal grading and faint lamination are discernible. In the upper part, however, intercalations with light mudstone, in part intensively bioturbated, together with parallel and cross-lamination suggest reworking of the ash in a shallow marine environment. Major and trace element compositions are used to correlate type I ashes with those of the Danish-positive series which represent rather uniform ferrobasalts of the Danish stage 4, probably related to the emergence of proto-Iceland. In contrast, type II ash comprises a single, normally graded, about 5-cm-thick layer of water-lain air-fall tuff, which is embedded in fine-grained sandstone to muddy siltstone. Type II ash is characterised by very high TiO2 but low MgO contents. Exceptional REE patterns with a pronounced positive Eu anomaly suggest intense leaching of the glass that hampers exact correlation with pyroclastic deposits within the North Atlantic Igneous Province.

  12. Gold deposit styles and placer gold characterisation in northern and east-central Madagascar

    Pitfield, Peter E. J; Styles, Michael T.; Taylor, Cliff D.; Key, Roger M.; Bauer,; Ralison, A


    Microchemical characterisation of bedrock and placer gold grains from six gold districts within the Archaean domains and intervening Neoproterozoic Anaboriana-Manampotsy belt of northern and east-central Madagascar show few opaque inclusions (e.g pyrrhotite, Bi tellurides) but wide range of Ag contents (40wt%). Some districts exhibit multiple source populations of grains. The ‘greenstone belt’ terranes have an orogenic gold signature locally with an intrusion-related to epithermal overprint. Proterozoic metasediments with felsic to ultramafic bodies yield dominantly intrusion-related gold. A high proportion of secondary gold (<0.5wt% Ag) is related to recycling of paleoplacers and erosion of post-Gondwana planation surfaces and indicates that some mesothermal gold systems were already partially to wholly removed by erosion by the PermoTriassic.

  13. The fate of water deposited in the low-lying northern plains

    Carr, M. H.


    Many large outflow channels terminate in the low-lying northern plains. If the outflow channels formed by running water, as appears likely, then standing bodies of water must have accumulated at the ends of the channels. Most of the observed channels, and hence the bodies of water, are post-Noachian. They formed after the period for which we have the most abundant evidence of climate change. While it has been speculated that the post-Noachian period has experienced large, episodic, climatic excursions, this paper takes the more conservative view that the climatic conditions on Mars, at least from mid-Hesperian onward, were mostly similar to the climatic conditions that prevail in the present epoch. Thus obliquity variations are taken into account, but massive climate changes induced by the floods are considered so improbable that they are ignored.

  14. An optical age chronology of Late Pleistocene fluvial deposits in the northern lower Mississippi valley

    Rittenour, Tammy M.; Goble, Ronald J.; Blum, Michael D.


    The lower Mississippi valley (LMV) contains many large braided channel belts that are preserved west of the Holocene floodplain. Previous efforts to establish geochronologic control on channel-belt construction have been hindered by the lack of organic material for radiocarbon dating. Luminescence techniques provide a burial date for the sediment itself and may prove useful in this context. Samples from three channel belts in the northern LMV were analyzed using the single aliquot-regenerative technique on 90-125 μm quartz. Optical ages (19.7-17.8, 16.1-15.0 and 12.5-12.1 ka) are consistent with geomorphic relationships and indicate that channel belts were formed in the late Pleistocene under glacial conditions. These optical ages provide the first detailed chronology of LMV channel-belt formation and are the first step towards developing a chronology for the entire LMV.

  15. Widespread loess-like deposit in the Martian northern lowlands identifies Middle Amazonian climate change

    Skinner, James A.; Tanaka, Kenneth L.; Thomas Platz,


    Consistently mappable units critical to distinguishing the style and interplay of geologic processes through time are sparse in the Martian lowlands. This study identifies a previously unmapped Middle Amazonian (ca. 1 Ga) unit (Middle Amazonian lowland unit, mAl) that postdates the Late Hesperian and Early Amazonian lowland plains by >2 b.y. The unit is regionally defined by subtle marginal scarps and slopes, has a mean thickness of 32 m, and extends >3.1 × 106 km2 between lat 35°N and 80°N. Pedestal-type craterforms and nested, arcuate ridges (thumbprint terrain) tend to occur adjacent to unit mAl outcrops, suggesting that current outcrops are vestiges of a more extensive deposit that previously covered ∼16 × 106 km2. Exposed layers, surface pits, and the draping of subjacent landforms allude to a sedimentary origin, perhaps as a loess-like deposit emplaced rhythmically through atmospheric fallout. We propose that unit mAl accumulated coevally with, and at the expense of, the erosion of the north polar basal units, identifying a major episode of Middle Amazonian climate-driven sedimentation in the lowlands. This work links ancient sedimentary processes to climate change that occurred well before those implied by current orbital and spin axis models.

  16. Fluvial depositional environment evolving into deltaic setting with marine influences in the buntsandstein of northern vosges (France)

    Gall, Jean-Claude

    The Buntsandstein in the Northern Vosges (France) originates mainly in an inland braidplain fluvial environment which passes in the upper part of the sequence into deltaic milieu in the coastal plain along the border of the sea, with the continental environment finally being drowned with the transgression of the shallow sea. The fluvial sedimentation is characterized by the presence of two facies throughout the Buntsandstein : channel facies and overbank plain facies. The channel facies comprises sandy and conglomeratic deposits forming within active streams by strong currents, whereas the overbank plain facies is built up of silty-clayey sandstones or silt/clay originating in stagnant water in abandoned watercourses, ponds, pools and puddles. The significance of particularly the floodplain sediments is subjected to considerable changes throughout the Buntsandstein sequence. There are all stages of transition between overbank plain deposits being only preserved in ghost-like facies as reworked clasts due to effective secondary removal of primarily occasionally formed suspension fines, and an abundance of autochthonous floodplain sediments in the depositional record resulting from favourable conditions of primary origin and secondary preservation. Reworked ventifacts within fluvial channel sediments testify to subordinate aeolian influences in the alluvial plain, with reasonable reworking, however, having removed all in situ traces of wind activity. Declining aridity of palaeoclimate towards the top is indicated by the appearance of violet horizon palaeosols in the Zone-Limite-Violette and the Couches intermédiaires being accompanied by Bröckelbank carbonate breccias originating from concentration of reworked fragments of pedogenic carbonate nodules. Biogenic traces are in the lower part of the sequence mainly present as Planolites burrows in the finer-grained sediments. Palaeosalinities as revealed from boron contents indicate progressively increasing

  17. NKS NordRisk II: Atlas of long-range atmospheric dispersion and deposition of radionuclides from selected risk sites in the Northern Hemisphere

    Smith Korsholm, U.; Havskov Soerensen, J. (Danish Meteorological Institute (DMI), Copenhagen (Denmark)); Astrup, P.; Lauritzen, B. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy. Radiation Research Div., Roskilde (Denmark))


    The present atlas has been developed within the NKS/NordRisk-II project 'Nuclear risk from atmospheric dispersion in Northern Europe'. The atlas describes risks from hypothetical long-range dispersion and deposition of radionuclides from 16 nuclear risk sites on the Northern Hemisphere. The atmospheric dispersion model calculations cover a period of 30 days following each release to ensure almost complete deposition of the dispersed material. The atlas contains maps showing the total deposition and time-integrated air concentration of Cs-137 and I-131 based on three years of meteorological data spanning the climate variability associated with the North Atlantic Oscillation, and corresponding time evolution of the ensemble mean atmospheric dispersion. (Author)

  18. Simulation of acid mine drainage generation around Küre VMS Deposits, Northern Turkey

    Demirel, Cansu; Kurt, Mehmet Ali; Çelik Balci, Nurgül


    experiments with mixed acidophiles at higher temperatures. Further depleted Fe(III) values coinciding with decreasing pH may point to precipitation of secondary phases (i.e. jarosite). This study revealed that the metals (Fe, Cu, Co and Zn) released during short term leaching of the ore (34 days) are generally caused by acid produced by dissolution reactions rather than oxidation. In the long term experiments a more complex biogeochemical reactions (oxidation and dissolution) take place in conjunction. Key words: Bioleaching, AMD, heavy metal release, environment, acidophilic bacteria, Küre copper ore deposits, volcanogenic massive sulfide deposits

  19. Tectono-metallogenetic evolution of the Fe-Cu deposit of Dominga, northern Chile

    Veloso, E.; Cembrano, J.; Arancibia, G.; Heuser, G.; Neira, S.; Siña, A.; Garrido, I.; Vermeesch, P.; Selby, D.


    The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinity among distinctive structural elements and Fe-Cu-rich paragenetic mineral assemblages. Deep seated, NE-to-E striking structural elements form a right-lateral duplex-like structural system (early structural system, ESS) that cuts a regionally extensive alteration (stage I) zone. The EES system served as a locus and as path for the emplacement of biotite-magnetite alteration/mineralization (stage IIa) as veins and Fe-bearing layers following altered volcano sedimentary strata. NW-striking actinolite-magnetite hydrothermal breccias, coeval with and part of the ESS, include apatite (stage IIb) crystallized at 127 ± 15 Ma (U-Pb, 2σ). The ESS was also the locus of subsequent alteration/mineralization represented by K-feldspar, epidote, and albite (stage IIIa) and Fe-Cu-rich (vermiculite-anhydrite-chalcopyrite, stage IIIb) mineral associations. Shallowly developed, NNE-striking, left-lateral structural elements defining the El Tofo Structural System (ETSS)—probably part of the Atacama Fault System—clearly crosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part of hydrothermal breccias of the ETSS, marking the transition from the ESS to ETSS. Molybdenite associated with alteration/mineralization stage IIIb yielded a Re-Os age of 127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut by left-lateral, NW- to E-striking shallowly developed structural elements (Intermediate Structural System, ISS) on which a hematite-calcite assemblage (stage IV) occurs mostly as infill material of veins and fault veins. The ISS is cut by N-striking, left-lateral, and shallowly developed structural elements (Late Structural System, LSS) showing no evidence of alteration/mineralization. Estimated strain and stress fields indicate an overall NW-trending shortening/compression and NE-trending stretching/tension strike-slip regime

  20. Tectono-metallogenetic evolution of the Fe-Cu deposit of Dominga, northern Chile

    Veloso, E.; Cembrano, J.; Arancibia, G.; Heuser, G.; Neira, S.; Siña, A.; Garrido, I.; Vermeesch, P.; Selby, D.


    The Dominga district in northern Chile (2082 Mt at 23.3 % Fe, 0.07 % Cu) shows a spatial and genetic affinity among distinctive structural elements and Fe-Cu-rich paragenetic mineral assemblages. Deep seated, NE-to-E striking structural elements form a right-lateral duplex-like structural system (early structural system, ESS) that cuts a regionally extensive alteration (stage I) zone. The EES system served as a locus and as path for the emplacement of biotite-magnetite alteration/mineralization (stage IIa) as veins and Fe-bearing layers following altered volcano sedimentary strata. NW-striking actinolite-magnetite hydrothermal breccias, coeval with and part of the ESS, include apatite (stage IIb) crystallized at 127 ± 15 Ma (U-Pb, 2σ). The ESS was also the locus of subsequent alteration/mineralization represented by K-feldspar, epidote, and albite (stage IIIa) and Fe-Cu-rich (vermiculite-anhydrite-chalcopyrite, stage IIIb) mineral associations. Shallowly developed, NNE-striking, left-lateral structural elements defining the El Tofo Structural System (ETSS)—probably part of the Atacama Fault System—clearly crosscut the ESS. Minerals associated with alteration/mineralization stage IIIb also occur as veins and as part of hydrothermal breccias of the ETSS, marking the transition from the ESS to ETSS. Molybdenite associated with alteration/mineralization stage IIIb yielded a Re-Os age of 127.1 ± 0.7 Ma (2σ). Both the ESS and ETSS were cut by left-lateral, NW- to E-striking shallowly developed structural elements (Intermediate Structural System, ISS) on which a hematite-calcite assemblage (stage IV) occurs mostly as infill material of veins and fault veins. The ISS is cut by N-striking, left-lateral, and shallowly developed structural elements (Late Structural System, LSS) showing no evidence of alteration/mineralization. Estimated strain and stress fields indicate an overall NW-trending shortening/compression and NE-trending stretching/tension strike-slip regime

  1. Predictive modeling of slope deposits and comparisons of two small areas in Northern Germany

    Shary, Peter A.; Sharaya, Larisa S.; Mitusov, Andrew V.


    Methods for correct quantitative comparison of several terrains are important in the development and use of quantitative landscape evolution models, and they need to introduce specific modeling parameters. We introduce such parameters and compare two small terrains with respect to the link slope-valley for the description of slope deposits (colluvium) in them. We show that colluvium accumulation in small areas cannot be described by linear models and thus introduce non-linear models. Two small areas, Perdoel (0.29 ha) and Bornhöved (3.2 ha), are studied. Slope deposits in the both are mainly in dry valleys, with a total thickness Mtotal up to 2.0 m in Perdoel and up to 1.2 m in Bornhöved. Parent materials are mainly Pleistocene sands aged 30 kyr BP. Exponential models of multiple regression that use a 1-m LiDAR DEM (digital elevation model) explained 70-93% of spatial variability in Mtotal. Parameters DH12 and DV12 of horizontal and vertical distances are introduced that permit to characterize and compare conditions of colluvium formation for various terrains. The study areas differ 3.7 times by the parameter DH12 that describes a horizontal distance from thalwegs at which Mtotal diminishes 2.72 times. DH12 is greater in Bornhöved (29.7 m) than in Perdoel (8.12 m). We relate this difference in DH12 to the distinction between types of the link slope-valley: a regional type if catchment area of a region outside a given small area plays an important role, and a local type when accumulation of colluvium from valley banks within a small area is of more importance. We argue that the link slope-valley is regional in Perdoel and local in Bornhöved. Peaks of colluvium thickness were found on thalwegs of three studied valleys by both direct measurements in a trench, and model surfaces of Mtotal. A hypothesis on the formation mechanism of such peaks is discussed. The parameter DV12 describes a vertical distance from a peak of colluvium thickness along valley bottom at

  2. Challenges for rescuing drill core from volcanogenic massive sulfide deposits in northern Wisconsin

    Stanley, V.; Schoephoester, P.; Lodge, R. W. D.


    Providing adequate physical care for unique lithologies can be a challenge for rock core repositories. The purpose of a repository is to preserve its collections such that they will be available and useful for current and future research. Preservation requires both documentation and physical care, including the state of the facility housing the collections, as specimens can be endangered by environmental factors. Digital documentation is a crucial first step in rescuing at-risk samples as it allows the collection to be monitored through time. Exploratory drill core from the Flambeau copper-gold mine in Ladysmith, WI was donated to the Wisconsin Geological and Natural History Survey (WGNHS). The collection includes over 4.7 km of irreplaceable core from 50 sites. The ore body is situated in the Ladysmith-Rhinelander Volcanic Complex, an Early Proterozoic greenstone belt that hosts at least 13 volcanogenic massive sulfide deposits (DeMatties, 1996), including Flambeau. Mineral assemblages include up to 50% sulfide minerals, mainly pyrite and marcasite (May and Dinkowitz, 1996). These lithologies present a unique preservation challenge - storage conditions must be temperature and humidity controlled to prevent pyrite oxidation (Newman 1998), which chemically and physically degrades the samples as well as labels, containers, and shelving. Once initiated, pyrite oxidation cannot be stopped or reversed, but may be stabilized (Howie, 1992). Although protecting these materials is a vital part of the WGNHS mission, climate-control modifications to the facility are cost-prohibitive. In order to rescue the samples, we documented the collection's present state. We developed and implemented a new database schema including IGSNs to improve metadata records, track samples, and link data. Although preservation of the physical samples remains a challenge, digital workflows and data management improvements will allow WGNHS to monitor the condition of these samples while also

  3. Geomorphology and sedimentary features, and temporal component-change of lahar deposits at the northern foot of Chokai volcano, NE Japan

    Minami, Y.; Ohba, T.; Kataoka, K.; Hayashi, S.


    Chokai volcano is an andesitic stratovolcano that collapsed to the north ca.2500 years ago. The post-collapse fan deposits are distributed in the northern foot of the volcano, and to reveal their depositional process in terms of modern sedimentology, we carried out the geological study includung digging survey, as well as geomorphological analysis, mineralogy, and 14C chronology. Consequently, the geological study revealed that the fan deposits consist of more than 16 units, which are debris flow, hyperconcentrated flow and streamflow deposits. We give hare general name lahar deposits for these deposits. The lahar deposits have a total thickness of 30 m, and overlie the 2.5-ka Kisakata debris avalanche deposit. The lahar deposits form a part of volcanic fan and volcaniclastic apron of Chokai volcano. In proximal areas (steep or moderate sloped areas), the lahar flowed down as debris flows, and in the distal area (horizontal area) the lahars transformed into hyperconcentrated flow or stream flows but partly arrived the area as debris flow. The hyperconcentrated flows or stream flows reached the horizontal area at least four times, supposed by AMS dating (the ages of some lahar deposits are 2200, 1500-1600, 1000-1200, and 100-200 yBP). The lahar deposits contain clasts of altered andesite, fresh andesite, mudstone and sandstone. Proportions of altered andesite clasts to total clasts decrease upwards in stratigraphic sequence. Matrices of the lower eight units are composed of grayish-blue clay, and are different from those of the upper eight units, composed of brownish yellow volcanic sand. The stratigraphic variation in matrix component is consistent with the change in matrix mineral assemblage, possibly reflecting changes in the source materials from Chokai volcano.

  4. ALS-based hummock size-distance relationship assessment of Mt Shasta debris avalanche deposit, Northern California, USA

    Tortini, Riccardo; Carn, Simon; van Wyk de Vries, Benjamin


    The failure of destabilized volcano flanks is a likely occurrence during the lifetime of a stratovolcano, generating large debris avalanches and drastically changing landforms around volcanoes. The significant hazards associated with these events in the Cascade range were demonstrated, for example, by the collapse of Mt St Helens (WA), which triggered its devastating explosive eruption in 1980. The rapid modification of the landforms due to these events makes it difficult to estimate the magnitude of prehistoric avalanches. However, the widespread preservation of hummocks along the course of rockslide-debris avalanches is highly significant for understanding the physical characteristics of these landslides. Mt Shasta is a 4,317 m high, snow-capped, steep-sloped stratovolcano located in Northern California. The current edifice began forming on the remnants of an ancestral Mt Shasta that collapsed ~300-380k years ago producing one of the largest debris avalanches known on Earth. The debris avalanche deposit (DAD) covers a surface of ~450 km2 across the Shasta valley, with an estimated volume of ~26 km3. We analyze ALS data on hummocks from the prehistoric Shasta valley DAD in northern California (USA) to derive the relationship between hummock size and distance from landslide source, and interpret the geomorphic significance of the intercept and slope coefficients of the observed functional relationships. Given the limited extent of the ALS survey (i.e. 40 km2), the high-resolution dataset is used for validation of the morphological parameters extracted from freely available, broader coverage DTMs such as the National Elevation Dataset (NED). The ALS dataset also permits the identification of subtle topographic features not apparent in the field or in coarser resolution datasets, including a previously unmapped fault, of crucial importance for both seismic and volcanic hazard assessment in volcanic areas. We present evidence from the Shasta DAD of neotectonic

  5. Biomarkers in a peat deposit in Northern Spain (Huelga de Bayas, Asturias) as proxy for climate variation.

    López-Días, V; Borrego, A G; Blanco, C G; Arboleya, M; López-Sáez, J A; López-Merino, L


    Peatlands are peculiar ecosystems in which well-adapted communities grow and develop, recording the variation in climate and hydrological conditions inland. In addition necromass is well preserved and therefore peatlands can be used as palaeo-archives for environmental variation. In this work a peat core of depth 60 cm dated at the bottom of the peat deposit as ca. 250cal AD from Huelga de Bayas (Asturias, Northern Spain) was studied to a resolution of 2-4 cm to investigate the evolution of the environmental conditions in the area. Samples were extracted with a dichloromethane/methanol ratio of 3:1 and studied by means of gas chromatography (GC) and mass spectrometry (GC-MS) in order to identify possible biomarkers of climatic variation during the period of peat formation. Lipid biomarker study allows the identification of periods in which Sphagnum or higher plants preferentially contributed to the peat profile. The absolute dating of the profile combined with the n-alkane record displayed five episodes of wetter conditions around ca. 250 cal AD (Roman Warm Period), 1080 and 1270 cal AD (Medieval Warm Period), 1460 cal AD (Little Ice Age) and 1920 cal AD (Recent warming), which are consistent with climate evolution in the region. Pentacyclic triterpenoids with hopane skeleton derived from microorganisms and with oleanane skeleton derived from higher plants were identified. The presence of their ketone and acetyl-derivatives, along with the presence of unstable hopane configurations indicates a low maturity of the peat profile. A tendency for the functionalised triterpenoids to decrease with depth was observed in the profile.

  6. Modeling spatial patterns of limits to production of deposit-feeders and ectothermic predators in the northern Bering Sea

    Lovvorn, James R.; Jacob, Ute; North, Christopher A.; Kolts, Jason M.; Grebmeier, Jacqueline M.; Cooper, Lee W.; Cui, Xuehua


    Network models can help generate testable predictions and more accurate projections of food web responses to environmental change. Such models depend on predator-prey interactions throughout the network. When a predator currently consumes all of its prey's production, the prey's biomass may change substantially with loss of the predator or invasion by others. Conversely, if production of deposit-feeding prey is limited by organic matter inputs, system response may be predictable from models of primary production. For sea floor communities of shallow Arctic seas, increased temperature could lead to invasion or loss of predators, while reduced sea ice or change in wind-driven currents could alter organic matter inputs. Based on field data and models for three different sectors of the northern Bering Sea, we found a number of cases where all of a prey's production was consumed but the taxa involved varied among sectors. These differences appeared not to result from numerical responses of predators to abundance of preferred prey. Rather, they appeared driven by stochastic variations in relative biomass among taxa, due largely to abiotic conditions that affect colonization and early post-larval survival. Oscillatory tendencies of top-down versus bottom-up interactions may augment these variations. Required inputs of settling microalgae exceeded existing estimates of annual primary production by 50%; thus, assessing limits to bottom-up control depends on better corrections of satellite estimates to account for production throughout the water column. Our results suggest that in this Arctic system, stochastic abiotic conditions outweigh deterministic species interactions in food web responses to a varying environment.

  7. Natural and anthropogenic influences on depositional architecture of the Ural Delta, Kazakhstan, northern Caspian Sea, during the past 70 years

    Scarelli, Frederico M.; Cantelli, Luigi; Barboza, Eduardo G.; Gabbianelli, Giovanni


    This paper focuses on the Ural Delta in the northern zone of the Caspian Sea, an area with particular characteristics, where intense influence from anthropogenic and natural factors exists, which acts on the fragile delta system. We built a database to integrate the data from the published sources, bathymetric survey, and recent images in the geographical information system (GIS) environment. The results were linked to the Caspian Sea level (CSL) curve, which had many variations, changing the Ural Delta system's dynamics and in its architecture. In addition, the anthropogenic changes contribute to shaping the actual Ural Delta architecture. Through the link between the results and CSL, we reconstructed an evolution model for the Ural Delta system for the last century and identified three different architectures for the Ural Delta, determined by the energy that acted on the system in the last century and by the anthropogenic changes. This work identifies six different delta phases, which are shaped by CSL changes during the last 70 years and by anthropogenic changes. The delta phases recognized are: i) a Lobate Delta phase, shaped during high CSL before 1935; ii) Natural Elongate Delta 1935-1950 formed during rapid CSL fall; iii) Anthropogenic Elongate Delta 1950-1966, formed during rapid CSL fall and after the Ural-Caspian Sea canal construction, which modified the sedimentary deposition on the delta; iv) Anthropogenic Elongate Delta 1966-1982 shaped during low CSL phase; v) Anthropogenic Elongate Delta 1982-1996 formed during a rapid CSL rise phase; and vi) Anthropogenic Elongate Delta 1996-2009 shaped during high CSL that represent the last phase and actual Ural Delta architecture.

  8. Geochemistry, Geochronology and Genesis of Gold Mineralization in Nurt of Northern Altay, Xinjiang:A Case Study on the Aketishikan Gold Deposit

    YUAN Feng; ZHOU Taofa; TAN Lugui; LUO Xianrong; YUE Shucang


    Gold deposits such as the Aketishikan, Togetobie, Tasbig-Kokeydlas, Kums and Hongshanzui gold deposits in the Nurt area in Altay of Xinjiang were found in Member 3 rhyolite tufflava, fragmental lava and ignimbrite of the Carboniferous Hongshanzui Group. Trace and rare earth elements, sulfur, lead, oxygen and hydrogen isotopes, and geochronological studies indicate that the ore-forming material was mostly supplied by the Carboniferous volcanic rocks through water-rock interaction under a low-to-moderate temperature, and the hydrothermal ore-forming fluid came from meteoric water with some magmatic water input evolved from the granitic magmas. Gold deposits in the Nurt area as well as in the northern Altay might form in multiple stages, and the Yanshanian mineralization period should be paid more attention besides the Variscan mineralization period.

  9. Metallogenic conditions and prospecting direction for Permian manganess deposits in Northern Guizhou%黔北二叠纪锰矿成矿条件与找矿方向



    黔北地区二叠纪锰矿是中国南方重要的沉积锰矿床类型,在贵州的锰矿资源中占有重要的地位.开展区内二叠纪锰矿成矿条件与找矿方向的研究与探讨,对锰矿勘查工作部署意义重大.文章拟从黔北成锰盆地的古地理环境、岩相特征、锰质来源和锰矿赋存规律4个方面,分析区内二叠纪锰矿成矿条件,在此基础上提出找矿方向并对资源前景预测.%The Permian manganese deposits in Northern Guizhou, a main aedimentary type manganese deposit in Southem Chi na, play an important role in manganese mineral resources of Guizhou. It is meaningful to study regional metallogenic condition of Per mian manganese deposit for exploration. In this paper, the author analyzed metallogenic conditions of Permian manganese deposits from four aspects, i. e. , the paleo - geographical environment of the basin in which manganese deposit developed, lithofacie8 characteris ticts, source of mangancse, and hosting regularity of manganese deposits, and then proposed the prospecting direction and forecasting potential resource.



    <正>20070291 Gong Ping (Northern Fujian Geological Party, Shaozou 354000) Discussion on Geological Characteristics and Control Factors of the Shimen Au-polymetallic Deposit in Zhenghe County, Fujian Province (Geology of Fujian, ISSN1001-3970, CN38-1080/P, 25(1), 2006, p.18-24, 2 illus., 2 tables, 1 ref.) Key words: gold deposits, polymetallic deposits, Fujian Province

  11. Source of boron in the Palokas gold deposit, northern Finland: evidence from boron isotopes and major element composition of tourmaline

    Ranta, Jukka-Pekka; Hanski, Eero; Cook, Nick; Lahaye, Yann


    The recently discovered Palokas gold deposit is part of the larger Rompas-Rajapalot gold-mineralized system located in the Paleoproterozoic Peräpohja Belt, northern Finland. Tourmaline is an important gangue mineral in the Palokas gold mineralization. It occurs as tourmalinite veins and as tourmaline crystals in sulfide-rich metasomatized gold-bearing rocks. In order to understand the origin of tourmaline in the gold-mineralized rocks, we have investigated the major element chemistry and boron isotope composition of tourmaline from three areas: (1) the Palokas gold mineralization, (2) a pegmatitic tourmaline granite, and (3) the evaporitic Petäjäskoski Formation. Based on textural evidence, tourmaline in gold mineralization is divided into two different types. Type 1 is located within the host rock and is cut by rock-forming anthophyllite crystals. Type 2 occurs in late veins and/or breccia zones consisting of approximately 80% tourmaline and 20% sulfides, commonly adjacent to quartz veins. All the studied tourmaline samples belong to the alkali-group tourmaline and can be classified as dravite and schorl. The δ11B values of the three localities lie in the same range, from 0 to -4‰. Tourmaline from the Au mineralization and from the Petäjäskoski Formation has similar compositional trends. Mg is the major substituent for Al; inferred low Fe3+/Fe2+ ratios and Na values (<0.8 atoms per formula unit (apfu)) of all tourmaline samples suggest that they precipitated from reduced, low-salinity fluids. Based on the similar chemical and boron isotope composition and the Re-Os age of molybdenite related to the tourmaline-sulfide-quartz veins, we propose that the tourmaline-forming process is a result of a single magmatic-hydrothermal event related to the extensive granite magmatism at around 1.79-1.77 Ga. Tourmaline was crystallized throughout the hydrothermal process, which resulted in the paragenetic variation between type 1 and type 2. The close association of

  12. Heavy mineral as a tool to refine the stratigraphy of kaolin deposits in the Rio Capim Area, Northern Brazil

    Ana M. Góes


    Full Text Available Studies of heavy minerals in kaolin deposits from the Ipixuna Formation in the Rio Capim area (Northern Brazil showed a mature to super mature assemblage dominated by zircon and tourmaline, and subordinately rutile, kyanite and staurolite. These minerals do not change much throughout the whole section; however, each kaolin unit displays a particular signature, defined by differences in the proportions of the whole assemblage of heavy minerals, as well as of their textural characteristics. This work revealed that the lower and upper kaolin units can be definitely considered as distinct depositional sequences. A higher proportion of opaque minerals and higher zircon values characterize the lower unit. The higher volumes of anhedric, rounded to sub-rounded grains of zircon and tourmaline in the upper unit suggests that this includes grains that were undergone to a higher degree of reworking. The increased volume of unaltered staurolite and kyanite in the upper unit leads to conclude that, even considering sediment reworking, a distinct source must be invoked. The results also show that the characteristics of the heavy mineral assemblage from the intermediate unit are comparable with those from the upper unit, which suggests they might record a same stratigraphic sequence.Estudos de minerais pesados provenientes em depósitos cauliníticos da Formação Ipixuna na região do rio Capim (Brasil revelaram uma mineralogia matura a supermatura, representada dominantemente por zircão e turmalina e, subordinadamente, rutilo, cianita e estaurolita. Os minerais encontrados não variam muito, entretanto cada unidade caulinítica apresenta uma assinatura particular definida por diferenças nasproporções entre os principais minerais, assim como em suas características texturais. Este trabalho demonstrou que asunidades de caulim soft (inferior e semi-flint (superior podem ser consideradas seqüências deposicionais distintas. As altas percentagens de opacos

  13. New insight into the origin of manganese oxide ore deposits in the Appalachian Valley and Ridge of northeastern Tennessee and northern Virginia, USA

    Carmichael, Sarah K.; Doctor, Daniel H.; Wilson, Crystal G.; Feierstein, Joshua; McAleer, Ryan


    Manganese oxide deposits have long been observed in association with carbonates within the Appalachian Mountains, but their origin has remained enigmatic for well over a century. Ore deposits of Mn oxides from several productive sites located in eastern Tennessee and northern Virginia display morphologies that include botryoidal and branching forms, massive nodules, breccia matrix cements, and fracture fills. The primary ore minerals include hollandite, cryptomelane, and romanèchite. Samples of Mn oxides from multiple localities in these regions were analyzed using electron microscopy, X-ray analysis, Fourier transform infrared spectroscopy, and trace and rare earth element (REE) geochemistry. The samples from eastern Tennessee have biological morphologies, contain residual biopolymers, and exhibit REE signatures that suggest the ore formation was due to supergene enrichment (likely coupled with microbial activity). In contrast, several northern Virginia ores hosted within quartz-sandstone breccias exhibit petrographic relations, mineral morphologies, and REE signatures indicating inorganic precipitation, and a likely hydrothermal origin with supergene overprinting. Nodular accumulations of Mn oxides within weathered alluvial deposits that occur close to breccia-hosted Mn deposits in Virginia show geochemical signatures that are distinct from the breccia matrices and appear to reflect remobilization of earlier-emplaced Mn and concentration within supergene traps. Based on the proximity of all of the productive ore deposits to mapped faults or other zones of deformation, we suggest that the primary source of all of the Mn may have been deep seated, and that Mn oxides with supergene and/or biological characteristics resulted from the local remobilization and concentration of this primary Mn.

  14. Comparison of Spheroidal Carbonaceous Particle Data with Modelled Atmospheric Black Carbon Concentration and Deposition and Air Mass Sources in Northern Europe, 1850–2010

    Meri Ruppel


    Full Text Available Spheroidal carbonaceous particles (SCP are a well-defined fraction of black carbon (BC, produced only by the incomplete combustion of fossil fuels such as coal and oil. Their past concentrations have been studied using environmental archives, but, additionally, historical trends of BC concentration and deposition can be estimated by modelling. These models are based on BC emission inventories, but actual measurements of BC concentration and deposition play an essential role in their evaluation and validation. We use the chemistry transport model OsloCTM2 to model historical time series of BC concentration and deposition from energy and industrial sources and compare these to sedimentary measurements of SCPs obtained from lake sediments in Northern Europe from 1850 to 2010. To determine the origin of SCPs we generated back trajectories of air masses to the study sites. Generally, trends of SCP deposition and modelled results agree reasonably well, showing rapidly increasing values from 1950, to a peak in 1980, and a decrease towards the present. Empirical SCP data show differences in deposition magnitude between the sites that are not captured by the model but which may be explained by different air mass transport patterns. The results highlight the need for numerous observational records to reliably validate model results.

  15. Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

    Sprovieri, F


    Full Text Available samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual...

  16. Miocene and early Pliocene epithermal gold-silver deposits in the northern Great Basin, western United States: Characteristics, distribution, and relationship to Magmatism

    John, D.A.


    Numerous important Miocene and early Pliocene epithermal Au-Ag deposits are present in the northern Great Basin. Most deposits are spatially and temporally related to two magmatic assemblages: bimodal basalt-rhyolite and western andesite. These magmatic assemblages are petrogenetic suites that reflect variations in tectonic environment of magma generation. The bimodal assemblage is a K-rich tholeiitic series formed during continental rifting. Rocks in the bimodal assemblage consist mostly of basalt to andesite and rhyolite compositions that generally contain anhydrous and reduced mineral assemblages (e.g., quartz + fayalite rhyolites). Eruptive forms include mafic lava flows, dikes, cinder and/or spatter cones, shield volcanoes, silicic flows, domes, and ash-flow calderas. Fe-Ti oxide barometry indicates oxygen fugacities between the magnetite-wustite and fayalite-magnetite-quartz oxygen buffers for this magmatic assemblage. The western andesite assemblage is a high K calc-alkaline series that formed a continental-margin are related to subduction of oceanic crust beneath the western coast of North America. In the northern Great Basin, most of the western andesite assemblage was erupted in the Walker Lane belt, a zone of transtension and strike-slip faulting. The western andesite assemblage consists of stratovolcanoes, dome fields, and subvolcanic plutons, mostly of andesite and dacite composition. Biotite and hornblende phenocrysts are abundant in these rocks. Oxygen fugacities of the western andesite assemblage magmas were between the nickel-nickel oxide and hematite-magnetite buffers, about two to four orders of magnitude greater than magmas of the bimodal assemblage. Numerous low-sulfidation Au-Ag deposits in the bimodal assemblage include deposits in the Midas (Ken Snyder), Sleeper, DeLamar, Mule Canyon, Buckhorn, National, Hog Ranch, Ivanhoe, and Jarbidge districts; high-sulfidation gold and porphyry copper-gold deposits are absent. Both high- and low

  17. Pleistocene terrace deposition related to tectonically controlled surface uplift: An example of the Kyrenia Range lineament in the northern part of Cyprus

    Palamakumbura, Romesh N.; Robertson, Alastair H. F.


    In this study, we consider how surface uplift of a narrow mountain range has interacted with glacial-related sea-level cyclicity and climatic change to produce a series of marine and non-marine terrace systems. The terrace deposits of the Kyrenia Range record rapid surface uplift of a long-lived tectonic lineament during the early Pleistocene, followed by continued surface uplift at a reduced rate during mid-late Pleistocene. Six terrace depositional systems are distinguished and correlated along the northern and southern flanks of the range, termed K0 to K5. The oldest and highest (K0 terrace system) is present only within the central part of the range. The K2-K5 terrace systems formed later, at sequentially lower levels away from the range. The earliest stage of surface uplift (K0 terrace system) comprises lacustrine carbonates interbedded with mass-flow facies (early Pleistocene?). The subsequent terrace system (K1) is made up of colluvial conglomerate and aeolian dune facies on both flanks of the range. The later terrace systems (K2 to K5) each begin with a basal marine deposit, interpreted as a marine transgression. Deltaic conglomerates prograded during inferred global interglacial stages. Overlying aeolian dune facies represent marine regressions, probably related to global glacial stages. Each terrace depositional system was uplifted and preserved, followed by subsequent deposits at progressively lower topographic levels. Climatic variation during interglacial-glacial cycles and autocyclic processes also exerted an influence on deposition, particularly on short-period fluvial and aeolian deposition.

  18. Stratigraphic sections, depositional environments, and metal content of the upper part of the Middle Pennsylvanian Minturn Formation, Northern Sangre De Cristo Range, Custer and Saguache counties, Colorado

    Clark, R.F.; Walz, D.M.


    The calcareous upper part of the 2,000-meter-thick Middle Pennsylvanian Minturn Formation (Lindsey and others, 1985) in the northern Sangre de Cristo Range is a key stratigraphic interval for correlating rocks and mapping the structure of the range. The stratigraphy of this complex and heretofore poorly known interval is reported here in order to provide a basis for correlation among the structural blocks in the range. Inferred depositional environments of the upper part of the Minturn Formation are described briefly.

  19. Catchment and in-stream influences on iron-deposit chemistry, algal-bacterial biomass and invertebrate richness in upland streams, Northern Ireland.

    Macintosh, Katrina Ann; Griffiths, David


    The density and composition of upland stream bed iron-deposits is affected by physical, chemical and biological processes. The basic chemical processes producing ochre deposits are well known. Mobilisation of iron and manganese is influenced by bedrock weathering, the presence of acidic and/or reducing conditions and the concentration of dissolved organic carbon. Ferromanganese-depositing bacteria are significant biogenic agents and can cause/enhance the deposition of metals in streams as (hydr)oxides. Metal concentrations from stream waters in two geological blocks in Northern Ireland were compared to determine the contributions of catchment characteristics and in-stream conditions. One block is composed of metamorphosed schist and unconsolidated glacial drift, with peat or peaty podzol (mainly humic) soils, while the other block consists of tertiary basalt with brown earth and gley soils. Water samples were collected from 52 stream sites and analysed for iron, manganese and aluminium as well as a range of other chemical determinands known to affect metal solubility. Stone deposit material was analysed for metal concentrations, organic matter content and epilithic algae, chlorophyll a concentration. Invertebrates were collected by area-standardised kick samples and animals identified to family and numbers counted. Higher conductivities and concentrations of bicarbonate, alkalinity, calcium and magnesium occurred on basalt than on schist. Despite higher iron and manganese oxide concentrations in basalt-derived non-humic soils, stream water concentrations were much lower and stone deposit concentrations only one third of those occurring on schist overlain by humic soils. Peat-generated acidity and the limited acid neutralising capacity of base-poor metamorphosed schist has resulted in elevated concentrations of metals and ochre deposit in surface waters. Algal biomass was determined by catchment level factors whereas in-stream conditions affected bacterial biomass

  20. Topographic and depositional signature of old anthropic lakes in northern part of the Moldavian Plateau (NE Romania)

    Ciprian Margarint, Mihai; Niculita, Mihai; Nemeth, Alexandra; Cristea, Ionut


    The role of humans and theirs social activities in reshaping earth surface is obvious in many places of the world. Anthropic fingerprints on Earth's surface morphology are recognizable by theirs topographic and depositional signatures that can cause considerable changes in geomorphological organization of the landscape, with direct consequences on Earth surface processes. Anthropic dams and their associated sediments represent recent archives that record environmental changes. They can provide substantial data to reconstruct general models in geomorphic evolution of hydrologic catchments and the identification of extreme meteorological events and sediment fluxes. Also, geochemical tracers provide us relevant indicators about climatic patterns and local condition of sedimentation processes. Until quite recently, the identification and counting the old lakes have been carried out mostly by studying different old maps and less by analyzing their fingerprints on the Earth surface. Considered a real revolution in geomorphology, the high-resolution LiDAR data allow us nowadays a more precise recognition of minor landforms, their extent and cross-relationships, as well as to discover surface features that have escaped the attention before. Furthermore, by using Electrical Resistivity Tomography techniques, the 3D extension of the sediments can be revealed. Anthropic lakes are one of the most particular hydrological anthropic features of the landscape in the northern part of the Moldavian Plateau (Eastern Carpathian lowland). The need for water supply, have forced the inhabitants to build dams of various sizes along the entire river network. Over the time, many dams were abandoned, while others have been relocated with an impressive dynamic at historical time scale. For more than 3000 sq km we have carried out an accurate inventory of abandoned dams using LIDAR imagery. Taking into consideration the last appearance of the lakes on the old maps, they were classified: pre

  1. Sedimentation of the basal Kombolgie Formation (Upper Precambrian-Carpentarian) Northern Territory, Australia: possible significance in the genesis of the underlying Alligator Rivers unconformity-type uranium deposits

    Ojakangas, R.W.


    The 1400 to 1500 My old Kombolgie Formation of the MacArthur Basin of the Northern Territory overlies or has overlain unconformity-type uranium deposits including Jabiluka, Ranger, Koongarra, Nabarlek and the small deposits of the South Alligator River Valley. A brief study of the basal portion of the formation showed it to consist entirely of mature conglomerates and quartzose sandstones. Analysis of the bedding types (planar cross beds, trough cross beds and parallel beds) and other sedimentary structures (mainly ripple marks and parting lineation) fit a braided alluvial plain model. A paleocurrent study utilizing about 400 measurements from nine localities located along the westward-facing 250 kilometer-long erosional escarpment of the Arnhem Land Plateau showed the dominant paleocurrent trend to be from west and northwest towards the east and southeast, with local divergence. The data and interpretation presented are relevant to the supergene model of uranium deposition at the unconformity, for they add to the suggestion that additional uranium deposits similar to Jabiluka Two may underlie the Kombolgie Formation eastward from the present escarpment.

  2. Critical loads of acidity for 90,000 lakes in northern Saskatchewan: A novel approach for mapping regional sensitivity to acidic deposition

    Cathcart, H.; Aherne, J.; Jeffries, D. S.; Scott, K. A.


    Atmospheric emissions of sulphur dioxide (SO2) from large point sources are the primary concern for acidic deposition in western Canada, particularly in the Athabasca Oil Sands Region (AOSR) where prevailing winds may potentially carry SO2 over acid-sensitive lakes in northern Saskatchewan. A novel catchment-scale regression kriging approach was used to assess regional sensitivity and critical loads of acidity for the total lake population of northern Saskatchewan (89,947 lakes). Lake catchments were delineated using Thiessen polygons, and surface water chemistry was predicted for sensitivity indicators (calcium, pH, alkalinity, and acid neutralizing capacity). Critical loads were calculated with the steady state water chemistry model using regression-kriged base cations, sulphate, and dissolved organic carbon concentrations modelled from surface water observations (n > 800) and digital landscape-scale characteristics, e.g., climate, soil, vegetation, landcover, and geology maps. A large region (>13,726 km2) of two or more indicators of acid sensitivity (pH acid neutralizing capacity, alkalinity, calcium acidic deposition in excess of their critical loads and many of them may be at risk of ecosystem damage owing to their sensitivity.

  3. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  4. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  5. The Pre-historical Eruption of Volcanoes Near a Capital-city: Inferred From Tephra Deposits in the Taipei Basin, northern Taiwan

    Chen, C.; Lin, C.


    The volcanic pyroclastic flows, lahars and/or ashes derived from volcanic eruptions are a serious threat of human lives and regional economies, especially in the densely populated area. In case, more than two million populations in the capital-city Taipei, northern Taiwan just live in the vicinity of the Tatun Volcanic Group (TVG), how to make effective and reliable volcanic hazard mitigation is absolutely mandatory. Volcano is a pretty complex system. Hazard mitigation can be achieved only by applying numerous techniques. Understanding the recent eruptive history will be the most important information for prediction the future activity of eruption. After 1995, the Center Geological Survey of Ministry of Economic Affair handled to drill more than 20 wells in the Taipei basin to investigate the subsurface geology of basin. These continuous core samples offered the best materials to investigate if any volcanic ashes had deposited in the basin. The young juvenile volcanic ashes V pumice tuff were firstly identified in the two cores of the Kuantu well (KT- 1) and the Shihlin well (SL-1 in the late Pleistocene Sunshan formation. According to the radiocarbon (C-14) ages of core samples (Lin et al, 1998, Shieh, 2001), the time of this tephra deposit was extrapolated around 18.6 kyrs C-14 B.P.. Respecting, this tephra would like to be temperately named as the 18 kyrs Taipei Tuff (18 KTT). These air-fall ash deposits found in the core directly demonstrated that there had been re-active in the TVG in the recent time. More notable thing is that there are three historical records of submarine eruptions in northern offshore Taiwan, then, a program of the volcanic hazard reduction should be seriously considered around the capital city-Taipei.




    Full Text Available The Upper Valdarno Basin, one of the most investigated Neogene–Quaternary basins of the Northern Apennines, developed during three main phases, as testified by the occurrence of three unconformity-bounded stratigraphic units (UBSUs in the basin infill. Despite numerous studies having been carried out, biochronological, paleoecological and stratigraphical issues in the lower portion of the Montevarchi Synthem (second phase have yet to be understood. Sandy deposits (Montecarlo Sand and Silt Unit, stratigraphically located in this portion of the Montevarchi Synthem, are the focus of this multidisciplinary study. These deposits conformably overlie sandy fluvio-eolian sediments and are, in turn, capped by fluvio-palustrine deposits through a progressive unconformity. Facies analysis suggest a sandy flood-basin environment for these deposits, characterised by variations in water discharge and flood event energy. Mollusc and fish remains, pointing to quiet or slow-moving shallow waters, have been affected by transport processes before final burial in overbank areas. Fish remains of the primary marine family Mugilids highlight a connection between the basin and the sea that was previously only supposed. Small mammal remains, referred to the rodent Mimomys polonicus, are coherent with a water-rich environment. Cyclic variations in shell content and sedimentological characteristics testify to the occurrence of short-term climatic oscillations during this warming phase. This study fits with paleomagnetic and radiometric datings and mammal biochronology, in indicating that the Montecarlo Sand and Silt Unit belongs to a time interval preceding the Reunion paleomagnetic event. The depositional evolution of the Montecarlo Unit was driven by climatic change from arid to humid conditions, related to a global increase in temperature that occurred between 2.4 and 2.2 Ma.

  7. A Comparison of Carlin-type Gold Deposits: Guizhou Province, Golden Triangle, Southwest China, and Northern Nevada, USA%A Comparison of Carlin-type Gold Deposits:Guizhou Province,Golden Triangle,Southwest China,and Northern Nevada,USA

    Jean S.CLINE; John L.MUNTEAN; Xuexiang GU; Yong XIA


    Several Au deposits in Guizhou Province,southwest China,described as being similar to the highly productive Carlin-type gold deposits in northern Nevada,USA,were examined to identify similarities and differences between the two districts.Samples were collected along transects from lowto high-grade rock,where possible,and from stockpiles at the Shuiyindong,Zimudang,Taipingdong,Yata and Jinfeng (formerly Lannigou) deposits.Methods used to examine ore and alteration minerals included hand-sample description; reflectance spectroscopy using an ASD Terraspec spectrometer;analyses of hand samples by carbonate staining with Alizaren red and potassium ferricyanide;transmitted and reflected light petrography; chemical analyses,mineral identification,and imaging using a JEOL JSM-5610 scanning electron microscope; and quantitative chemical analyses using a JEOL JXA-8900 electron probe microanalyzer.Geochemical analyses of hand samples for 52 elements were done by ALS Chemex.Results indicate both similarities and differences between the two districts.Both districts have similar geologic histories,and deposits at both locations appear to have formed as a result of similar tectonic events,though the district in southwest China lacks evidence of coeval felsic igneous activity;however,the ore-stage minerals and the fluids that produced the minerals and deposits have some significant differences.The Nevada deposits were dominated by fluid-rock reaction in which host rock Fe was sulfidized to form Au-bearing pyrite.Although ore fluids sulfidized host rock Fe in the Guizhou deposits,the timing of Fe metasomatism is unknown,so whether the deposits formed in response to sulfidation or pyritization is unclear.Fluid-rock reaction between an acidic,aqueous fluid and highly reactive calcareous rocks in Nevada caused extensive decarbonatization of host rocks,jasperoid replacement of carbonate minerals,and alteration of silty rock components to illite and kaolinite.In Guizhou,CO2-bearing ore

  8. {sup 210}Pb dating of sediments from the central and the northern Adriatic Sea: The deposition and preservation of sedimentary organic carbon

    Hamilton, T.; Fowler, S.; Miquel, J.C.; La Rosa, J.


    A central goal of the ELNA project is to assess the carbon assimilation capacity of the Northern Adriatic Sea. This requires fundamental quantitative information on budgets and sinks of organic carbon. Any change in carbon production in the water column should be reflected in the underlying sediments. Moreover, the fraction of particulate organic carbon reaching the sea floor which is subsequently preserved in the sediment will be strongly coupled to sediment accumulation and mixing. In this study a series of box cores were collected in order to characterize a hypothetical eutrophication gradient extending from the Po River outflow region in the north down to the shallow meso-Adriatic depression (Jabuka Pit). The main tasks assigned to IAEA-MEL were to provide {sup 210}Pb derived sedimentation and dry-mass accumulation rates and to examine the possible correlations between sedimentary processes, the deposition and preservation of sedimentary organic carbon and pelagic primary productivity.

  9. {sup 210}Pb dating of sediments from the central and northern Adriatic Sea: deposition and preservation of sedimentary organic carbon

    Hamilton, T. F., LLNL


    Lead-210 ({sup 21O}Pb) and organic C depth distribution profiles in sediments from the northern and central Adriatic Sea were measured as part of the EEC funded project on Eutrophic Limits of the Northern Adriatic (ELNA). {sup 210}Pb derived mass-accumulation rates decrease southward from between 0.15 and 0.2 g cm{sup -2}y{sup -1} close to the Po River outflow (> 24 m, water depth) to less than 0.04 g cm{sup -2}y{sup -1} in the Jabuka Pit (246 m, water depth) in the central Adriatic Sea. The mass- accumulation rates obtained in the Jabuka Pit correspond to mean sedimentation rates of about 0.03 cm y{sup -1} (ref. porosity = 0.5) and fall between 5 to 20 times lower than rates found for north Adriatic shelf cores. Estimated sedimentation rates are considered as upper limits because of the possible effects of bioturbation and physical disturbance on the {sup 21O}Pb sedimentary record but are consistent with data from previous work. Rates of sediment accumulation and carbon burial appear to be strongly influenced by the transport of fluvial materials from land and transport of fine-grained particles. First-order estimates of organic C burial rates into surface sediment ranged from 1 to 0.028 mMol cm{sup -2}y{sup -1} between the Po delta and the Jabuka Pit regions, respectively. We estimate that a maximum of 50% of organic C preserved in surface sediment may be derived from biological production in the overlying water column.

  10. Contrasting alluvial architecture of Late Pleistocene and Holocene deposits along a 120-km transect from the central Po Plain (northern Italy)

    Campo, Bruno; Amorosi, Alessandro; Bruno, Luigi


    High-resolution investigation of a ~ 120-km-long transect along the course of the modern Po River, northern Italy, revealed marked changes in alluvial architecture across the Pleistocene-Holocene boundary. Along the whole transect, a 20- to 30-m thick sheet-like succession of Late Pleistocene fluvial sands is invariably overlain by silt and clay deposits, with isolated fluvial bodies of Holocene age (architecture: well-drained floodplain deposits are transitional at distal locations to increasingly organic, poorly drained floodplain to swamp facies associations. Thick paludal facies extend continuously up to 60 km landward of the Holocene maximum marine ingression, about 90 km from the modern shoreline. Based on 28 radiocarbon dates, the abrupt change in lithofacies and channel stacking pattern occurred at the transition from the last glacial period to the present interglacial, under conditions of rapid sea-level rise. The architectural change from amalgamated, Late Pleistocene sand bodies to overlying, mud-dominated Holocene units represent an example of chronologically well-constrained fluvial response to combined climate and relative sea-level change. The overall aggradational stacking pattern of individual channel-belt sand bodies indicates that high subsidence rates continuously created accommodation in the Po Basin, even during phases of falling sea level and lowstand.

  11. Eolian deposits of the southwestern margin of the Botucatú paleoerg: Reconstruction of the Gondwana landscape in Central Northern Argentina

    Peri, V. Gisel; Naipauer, Maximiliano; Pimentel, Marcio; Barcelona, Hernan


    The Mesozoic Botucatú paleoerg at the southwestern margin of Gondwana includes a succession of eolian dunes cross-strata which are presently exposed in Otumpa Hills (Central Northern Argentina). Here, the architectural facies, petrology, and provenance of those rocks were studied in order to investigate depositional environments and paleoclimates. The stratigraphic sequence included basal eolian two-dimensional crescentic dunes (Slp) overlain by three-dimensional crescentic dunes of smaller scale (Smt). These were correlated with the Upper Member Rivera of the Tacuarembó Formation (Uruguay), or its equivalent in Brazil, the Botucatú Formation. These outcrops partially mark the southwestern margin of the Botucatú paleoerg along the Chaco-Paraná Basin boundary. The paleocurrents from the W, NW, and SW and the U-Pb ages of detrital zircons indicate a main Pampean cratonic and secondary Andean magmatic arc (180 Ma) source. A detrital zircon of 180 Ma by U-Pb limits a maximum depositional age at 180 Ma (Toarcian) for facies Slp. Upwards, the phreatic silcrete and calcrete indicate semiarid conditions during the Paleocene, which are correlated with the Queguay Formation of Uruguay. A saprolite paleoweathering profile, recording wet tropical-hyper-tropical climate at the Early Eocene and representing the Gondwana landscape and climate conditions, crowns the sequence. This study represents the first provenance and surface texture analysis of minerals from the Botucatú paleoerg and was instrumental to unravel past environmental and sedimentary conditions.




    Full Text Available Seep-carbonates are generally related to hydrocarbon seepage on continental margins. Modern cold seeps are abundant in actively deforming tectonic settings, suggesting that tectonics is one of the major controlling factor on fluid emissions. Hydrocarbon seepages areconsidered major geological sources of atmospheric methane, one of the most important green-house gases, and have also been related to climate changes. However, the interplaybetween tectonics and climate change in forcing seepage is not clearly understood. Miocene seep-carbonates, formed in a collisional settingsuch as that ofthe Salsomaggiore area of the Northern Apennines(Italy, provide an opportunitytoassess accumulation and release of methane in response to tectonics and climate change along a convergent margin. Thestudiedseep-carbonatesarerelated to fluid emissions of various intensities coeval with tectonic pulses.Newplanktonic foraminiferal biostratigraphic datareveals thatdepositionof these seep-carbonatesislate Serravallian-early Tortonian in age and partiallycoeval with the Miller’s global cooling event Mi 5 (as used below. These seep-carbonates were deposited in two stages with different seepage modes. During the first stage, local tectonic pulses at the onset of the Mi5 event may have producedslow seepage, whereas during the second stage regional tectonics and more extreme climatic conditions (coolest peak of Mi5 event may have resulted inafast and more intense seepage as suggested by increasing occurrence of chaotic facies. In the Salsomaggiore Ridge, tectonics and the Mi5 cooling event actively concurredtothe deposition of seep-carbonates in both stages.

  13. Depositional and provenance record of the Paleogene transition from foreland to hinterland basin evolution during Andean orogenesis, northern Middle Magdalena Valley Basin, Colombia

    Moreno, Christopher J.; Horton, Brian K.; Caballero, Victor; Mora, Andrés; Parra, Mauricio; Sierra, Jair


    The Central Cordillera and Eastern Cordillera of the northern Andes form the topographic flanks of the north-trending Magdalena Valley Basin. Constraining the growth of these ranges and intervening basin has implications for Andean shortening and the transformation from a foreland to hinterland basin configuration. We present sedimentological, paleocurrent, and sandstone petrographic results from Cenozoic type localities to provide insights into the tectonic history of the northern Middle Magdalena Valley Basin of Colombia. In the Nuevo Mundo Syncline, the mid-Paleocene transition from marine to nonmarine deposystems of the Lisama Formation corresponds with a paleocurrent shift from northward to eastward transport. These changes match detrital geochronological evidence for a contemporaneous shift from cratonic (Amazonian) to orogenic (Andean) provenance, suggesting initial shortening-related uplift of the Central Cordillera and foreland basin generation in the Magdalena Valley by mid-Paleocene time. Subsequent establishment of a meandering fluvial system is recorded in lower-middle Eocene strata of the lower La Paz Formation. Eastward paleocurrents in mid-Paleocene through uppermost Eocene fluvial deposits indicate a continuous influence of western sediment source areas. However, at the upper middle Eocene (˜40 Ma) boundary between the lower and upper La Paz Formation, sandstone compositions show a drastic decrease in lithic content, particularly lithic volcanic fragments. This change is accompanied by a facies shift from mixed channel and overbank facies to thick, amalgamated braided fluvial deposits of possible fluvial megafans, reflecting changes in both the composition and proximity of western sediment sources. We attribute these modifications to the growing influence of exhumed La Cira-Infantas paleohighs in the axial Magdalena Valley, features presently buried beneath upper Eocene-Quaternary basin fill along the western flank of the Nuevo Mundo Syncline. In

  14. 3D representation of geochemical data, the corresponding alteration and associated REE mobility at the Ranger uranium deposit, Northern Territory, Australia

    Fisher, Louise A.; Cleverley, James S.; Pownceby, Mark; MacRae, Colin


    Interrogation and 3D visualisation of multiple multi-element data sets collected at the Ranger 1 No. 3 uranium mine, in the Northern Territory of Australia, show a distinct and large-scale chemical zonation around the ore body. A central zone of Mg alteration, dominated by extensive clinochlore alteration, overprints a biotite-muscovite-K-feldspar assemblage which shows increasing loss of Na, Ba and Ca moving towards the ore body. Manipulation of pre-existing geochemical data and integration of new data collected from targeted `niche' samples make it possible to recognise chemical architecture within the system and identify potential fluid conduits. New trace element and rare earth element (REE) data show strong fractionation associated with the zoned alteration around the deposit and with fault planes that intersect and bound the deposit. Within the most altered portion of the system, isocon analysis indicates addition of elements including Mg, S, Cu, Au and Ni and removal of elements including Ca, K, Ba and Na within a zone of damage associated with ore precipitation. In the more distal parts of the system, processes of alteration and replacement associated with the mineralising system can be recognised. REE element data show enrichment in HREE centred about a characteristic peak in Dy in the high-grade ore zone while LREEs are enriched in the outermost portions of the system. The patterns recognised in 3D in zoning of geochemical groups and contoured S, K and Mg abundance and the observed REE patterns suggest a fluid flow regime in which fluids were predominately migrating upwards during ore deposition within the core of the ore system.

  15. Effects of sand burial on dew deposition on moss soil crust in a revegetated area of the Tennger Desert, Northern China

    Jia, Rong-liang; Li, Xin-rong; Liu, Li-chao; Pan, Yan-xia; Gao, Yan-hong; Wei, Yong-ping


    Sand burial and dew deposition are two fundamental phenomena profoundly influencing biological soil crusts in desert areas. However, little information is available regarding the effects of sand burial on dew deposition on biological soil crusts in desert ecosystems. In this study, we evaluated the effects of sand burial at depths of 0 (control), 0.5, 1, 2 and 4 mm on dew formation and evaporation of three dominant moss crusts in a revegetated area of the Tengger Desert (Northern China) in 2010. The results revealed that sand burial significantly decreased the amount of dew deposited on the three moss crust types by acting as a semi-insulator retarding the dew formation and evaporation rates. The changes in surface temperature cannot fully explain the variations of the formation and evaporation rates of dew by moss crusts buried by sand. The extension of dew retention time was reflected by the higher dew ratios (the ratio of dew amount at a certain time to the maximum value in a daily course) in the daytime, and may to some extent have acted as compensatory mechanisms that diminished the negative effects of the reduction of dew amount induced by sand burial of moss crusts. The resistances to reduction of dewfall caused by sand burial among the three moss crusts were also compared and it was found that Bryum argenteum crust showed the highest tolerance, followed by crusts dominated by Didymodon vinealis and Syntrichia caninervis. This sequence corresponds well with the successional order of the three moss crusts in the revegetated area, thereby suggesting that resistance to reduction of dewfall may act as one mechanism by which sand burial drives the succession of moss crusts in desert ecosystems. This side effect of dew reduction induced by sand burial on biological soil crusts should be considered in future ecosystem construction and management of desert area.

  16. Discovery of laterally extensive drape of siliciclastic silt in the Northern Calcareous Alps, Austria: Late-glacial to ?early Holocene aeolian deposition.

    Gild, Charlotte; Geitner, Clemens; Haas, Jean Nicolas; Sanders, Diethard


    Field surveys in the Northern Calcareous Alps (NCA, a nappe stack of Triassic carbonate rocks) revealed a drape, or drapes, typically 20-40 cm in thickness of siliciclastic silt over extensive landscape areas, from valley floors to LGM (Last Glacial Maximum) nunataks. The drape veneers substrates ranging from country rocks to diverse post-LGM deposits - the latter with depositional and/or erosional topographies. The drape mostly is overlain by vegetated organic material and, in turn, tops inactive/abandoned post-LGM successions of fluvial (including kame terrace), alluvial fan, scree slope, LGM basal till, and rock-avalanche origin. The drape extends over kilometers at least (limit of field investigation in specific areas), up to LGM nunatak plateaus. Deposystems (e.g., scree slopes, alluvial fans) on carbonate-rocky terrain that remained active until the Holocene are not topped by the drape; a level of siliciclastic silt, however, was spotted within a few of these successions. The possibility that several levels of silt are intercalated within or top post-glacial deposits cannot be excluded at present; the large lateral extent and the stratigraphic position, however, suggest that at least most locations pertain to a single widespread level (with that reservation, we prefer to speak in singular of the drape). Over the inspected area (~ 90 x 20 km), the drape consists mainly of silt-sized grains of quartz, feldspars, micas, and amphiboles; at a few sites, calci- or dolosilt are admixed. Most of the grains are angular to subrounded, some grains show features of corrosion. Preliminary palynological analyses of this silt - seven locations from LGM nunataks to kame terrace and alluvial fans - suggest vegetation types that, together, may be assigned to palaeoclimates ranging from the late-glacial (Younger Dryas?) to the middle Holocene. A few of the pollen spectra appear to record sparse vegetation cover allowing for enhanced aeolian deposition, but other spectra (e

  17. Sedimentological and sequence stratigraphic analysis of Carboniferous deposits in western Libya: Recording the sedimentary response of the northern Gondwana margin to climate and sea-level changes

    Fröhlich, Sebastian; Petitpierre, Laurent; Redfern, Jonathan; Grech, Paul; Bodin, Stéphane; Lang, Simon


    Detailed sedimentological and sequence stratigraphic analysis of Carboniferous (Tournaisian to Moscovian) strata exposed in the north-western Murzuq Basin and southern Ghadames Basin, western Libya, provides new insights into the sedimentary response of the northern Gondwana margin to climate and sea-level change. The Lower Carboniferous Marar and Assedjefar Formations can be divided into five depositional sequences of 3rd order. In total 27 facies types are defined, grouped into four facies associations: offshore shales, shallow marine clastics, fluvial sandstones and marine carbonates. The bulk of the Lower Carboniferous interval is dominated by an alternation of offshore shales and shallow marine clastics, which were deposited during the transgressive and highstand systems tracts. The clastic deposits mostly consist of laterally persistent coarsening and thickening upward cycles with a common succession from basal hummocky cross-stratified sandstones to ripple-laminated sandstones, capped by multidirectional cross-stratified sandstones. Within the lowstand systems tracts, lenticular sandbodies have been identified, which vary in thickness from 1.5 m (ca. 40 m wide) to 50 m (ca. 1.5 km wide). These are interpreted to be fluvial channel complexes based on their geometry, erosive base, and presence of thick stacked sandstones with unidirectional planar and trough cross-bedding, the absence of bioturbation and occurrence of land plant fragments. These channel complexes mostly cut down into offshore shales, and are interpreted to be bound at the base by sequence boundaries. Palaeogeographic maps generated for each lowstand system show the location and palaeoflow direction of these fluvial channel complexes. They are interpreted to represent large incised valleys filled with thick fluvial sandstones. Their identification and distribution indicates repeated exposure of large areas of western Libya, most-likely controlled by major eustatic sea-level changes. The

  18. High and Low Temperature Gold Mineralizations in the Fe–Cu–Zn Sulfide Deposits of Corchia Ophiolite, Northern Italian Apennine

    Zaccarini Federica


    Full Text Available Gold has been found in the Cyprus-type volcanogenic massive sulfide ore (VMS deposits of Corchia ophiolite (Parma province, Italy in the Cantiere Donnini, Speranza and Pozzo mining sites. At Cantiere Donnini and Speranza, the mineralization occurs at the contact between pillow lava and sedimentary rocks. The Pozzo mineralization is hosted by a serpentinite. Concentrations of gold up to 3070 ppb have been reported for the Cantiere Donnini and up to 6295 ppb in the Pozzo mine. According to the field relationships, gold composition, mineralogical assemblage and sulfur isotope data, we can conclude that two different types of gold mineralization have been recognized in the Corchia ophiolite: (1 formed at low temperature in submarine environment (Cantiere Donnini and Speranza and (2 formed at high temperature in the oceanic mantle (Pozzo by segregation of an immiscible sulfide liquid.

  19. Modern processes of palynomorph deposition at lakes of the northern region of the Rio de Janeiro State, Brazil

    Cynthia F.P. da Luz


    Full Text Available Palynological analysis of pollen, Pteridophyta spores and algae deposited in the superficial sediments at Lagoa de Cima and Lagoa do Campelo Lakes, located in the north of Rio de Janeiro state, was used to determine the spatial variation of the palynomorphs deposition. A total of 67 pollen types were identified at Lagoa de Cima, with an expressive contribution of regional arboreous taxa, hydrophytes and ruderal plants of the pastureland. The depositional pattern of palynomorphs depends on the fluvial leakage, the proximity of the local sedimentation to the inlet of the Imbé and Urubu Rivers and the bathymetry of lake bottom. The highest concentrations of palynomorphs were observed in the decentralized and less deeper area, without the interference of the northeastern wind. At Lagoa do Campelo, a total of 58 pollen types were identified, among which the majority of the pollen grains came from hydrophytes, with the highest concentrations found along the northeastern shore. The southeastern shore showed high percentages of pollen and spores with degraded exine and mechanical damage, due to the transport through the lakeby the currents caused by the wind, confirmed by the depositional trend of damaged palinomorphs along the same direction as the prevailing winds.A análise palinológica de grãos de pólen, esporos de Pteridophyta e algas depositados nos sedimentos superficiais da Lagoa de Cima e Lagoa do Campelo, norte do Rio de Janeiro, foi usada para a avaliação da variação espacial de deposição dos palinomorfos. Um total de 67 tipos polínicos foi identificado na Lagoa de Cima, com expressiva contribuição de taxons arbóreos regionais, plantas hidrófitas e ruderais de pastagens. O padrão deposicional dos palinomorfos está sujeito às vazões fluviais, à proximidade do local de sedimentação em relação à desembocadura dos rios Imbé e Urubu e à batimetria do leito da lagoa. As maiores concentrações de palinomorfos foram

  20. Distribution of chemical elements in calc-alkaline igneous rocks, soils, sediments and tailings deposits in northern central Chile

    Oyarzún, Jorge; Oyarzun, Roberto; Lillo, Javier; Higueras, Pablo; Maturana, Hugo; Oyarzún, Ricardo


    This study follows the paths of 32 chemical elements in the arid to semi-arid realm of the western Andes, between 27° and 33° S, a region hosting important ore deposits and mining operations. The study encompasses igneous rocks, soils, river and stream sediments, and tailings deposits. The chemical elements have been grouped according to the Goldschmidt classification, and their concentrations in each compartment are confronted with their expected contents for different rock types based on geochemical affinities and the geologic and metallogenic setting. Also, the element behavior during rock weathering and fluvial transport is here interpreted in terms of the ionic potentials and solubility products. The results highlight the similarity between the chemical composition of the andesites and that of the average Continental Crust, except for the higher V and Mn contents of the former, and their depletion in Mg, Ni, and Cr. The geochemical behavior of the elements in the different compartments (rocks, soils, sediments and tailings) is highly consistent with the mobility expected from their ionic potentials, their sulfates and carbonates solubility products, and their affinities for Fe and Mn hydroxides. From an environmental perspective, the low solubility of Cu, Zn, and Pb due to climatic, chemical, and mineralogical factors reduces the pollution risks related to their high to extremely high contents in source materials (e.g., rocks, altered zones, tailings). Besides, the complex oxyanions of arsenic get bound by colloidal particles of Fe-hydroxides and oxyhydroxides (e.g., goethite), thus becoming incorporated to the fine sediment fraction in the stream sediments.

  1. Quantitative dating of Pleistocene terrace deposits of the Kyrenia Range, northern Cyprus: implications for timing, rates of uplift and driving mechanisms in an incipient collision zone

    Palamakumbura, Romesh; Robertson, Alastair; Kinnaird, Tim; van Calsteren, Peter; Kroon, Dick; Tait, Jenny


    The Kyrenia Range is a narrow E-W trending mountain range up to c. 180 km long by up to ca. 20 km wide, which is located Cyprus. To help understand the tectonic processes driving the uplift of the Kyrenia Range several quantitative techniques have been used to date uplift-related terrace deposits exposed on the northern flank of the range. Uranium-series disequilibrium (U-series) dating provides ages of 127, 131 and 242 ka from solitary coral in shallow-marine deposits of the lowest terraces, whereas optically stimulated luminescence (OSL) dating gives ages of 53 and 76 ka from coastal aeolianite deposits. Prior to major tectonic uplift a shallow-marine carbonate-depositing sea existed in the vicinity of the Kyrenia Range. Some of the youngest pre-uplift marine carbonates yielded a reversed magnetic polarity, which constrains them as older than the last palaeomagnetic reversal (0.78 Ma). The combined evidence suggests that marine environments persisted into the Early Pleistocene, prior to major surface uplift of the Kyrenia Range lineament, which appears to have climaxed in the Mid-Pleistocene. The inferred uplift rates of the Kyrenia Range lineament range from >1.2 mm/yr during the Mid-Pleistocene to Cyprus, which is in keeping with the model of regional-scale collision of the Eratosthenes Seamount with the Cyprus trench. The uplift of the Kyrenia Range lineament took place directly adjacent to the southern margin of the much larger Anatolian orogenic plateau, which was also mainly uplifted during the Pleistocene. The timing and processes involved in the uplift of the Kyrenia Range lineament are relevant to long-term processes of continental accretion and plateau uplift. On a longer timescale, the uplift of the Kyrenia Range in an incipient collisional setting can be seen as a step towards final accretion into a larger Anatolian orogenic plateau as collision intensifies. Terranes similar to the Kyrenia Range lineament may therefore exist embedded within the

  2. Integration of 2D and 3D reflection seismic data with deep boreholes in the Kevitsa Ni-Cu-PGE deposit, northern Finland

    Koivisto, Emilia; Malehmir, Alireza; Voipio, Teemu; Wijns, Chris


    Kevitsa is a large disseminated sulphide Ni-Cu-PGE deposit hosted by the Kevitsa mafic-ultramafic intrusion in northern Finland and dated as about 2.06 Ga old. The Geological Survey of Finland first discovered the Kevitsa deposit in 1987. Open pit mining by Kevitsa Mining Oy/First Quantum Minerals Ltd. commenced in June 2012. The final pit depth is planned to be 550-600 m. The estimated ore reserves of the Kevitsa intrusion are about 240 million tones (using a nickel cut-off grade of 0.1%). The expected life-of-mine is 20-30 years. More than 400 hundred holes have been drilled in the Kevitsa area, but most are concentrated close to the known deposit and do not provide a comprehensive understanding of the extent of the intrusion. The basal contact of the intrusion is penetrated by only about 30 drill holes, most of which are shallow. A better knowledge of the geometry of the intrusion would provide a framework for near-mine and deep exploration in the area. An exact knowledge on the basal contact of the intrusion would also provide an exploration target for the contact-type mineralization that is often more massive and richer in Ni-Cu. In December 2007, a series of 2D reflection seismic profiles was acquired in the Kevitsa area. It consisted of four connected survey lines between 6 and 11 km long. In 2010, the initial positive results of the 2D seismic survey led Kevitsa Mining Oy/First Quantum Minerals Ltd. to initiate a 3D reflection seismic survey. The 3D seismic survey is limited to the closer vicinity of the known deposit, while the 2D seismic survey was designed to provide a more regional view of the Kevitsa intrusive complex. The main aims of the 2D and 3D seismic surveys were to delineate the shape and extent of the ore-bearing Kevitsa intrusion and the geometry of some of the host rock and surrounding units, and extract information about the larger-scale structures and structures important for mine-planning purposes. The 2D and 3D seismic data were used to

  3. Potential of natural gamma-ray spectrometry for mapping and environmental monitoring of black-sand beach deposits on the northern coast of Sinai, Egypt.

    Aboelkhair, Hatem; Zaaeimah, Mostafa


    The concentrations and distributions of naturally occurring radioactive materials were studied with the aim of detecting and mapping radioactive anomalies as well as monitoring the environment for black-sand beach deposits in Northern Sinai, Egypt. For this purpose, ground gamma-ray spectrometric surveys were conducted using a portable GS-512 spectrometer, with an NaI (Tl) detector, on an area 77.5 km(2) in surface area located between the cities of Rafah and Elareish on the Mediterranean Sea coast. The results revealed that the black-sand beach deposits could be differentiated according to their total-count (TC) radioactivity into five normally distributed interpreted radiometric lithologic (IRL) units denoted by U1, U2, U3, U4 and U5. The computed characteristic TC radiometric statistics of these five IRL units range from 4.67  to 9.96 Ur for their individual arithmetic means. The computed arithmetic means for the three radioelements K, eU and eTh reach 0.46 %, 2.25 and 6.17 ppm, respectively for the whole study area. Monitoring the environmental effects of radioelement concentrations on the study area showed that the mean natural equivalent radiation dose rate from the terrestrial gamma-radiation of the whole area attains 0.33 mSv y(-1). This average value remains on the safe side and within the maximum permissible safe radiation dose (radioactive dose generated mainly by monazite and zircon minerals, two of the main constituents of black sands.

  4. Ages and sources of components of Zn-Pb, Cu, precious metal, and platinum group element deposits in the goodsprings district, clark county, Nevada

    Vikre, P.; Browne, Q.J.; Fleck, R.; Hofstra, A.; Wooden, J.


    The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ?? precious metal-platinum group element (PGE) deposits, and gold ?? silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ??500 km2 although the distribution of all deposits has been laterally condensed by late Mesozoic crustal contraction. Zinc, Pb, and Cu production from about 90 deposits was ??160,000 metric tons (t) (Zn > Pb >> Cu), 2.1 million ounces (Moz) Ag, 0.09 Moz Au, and small amounts of PGEs-Co, V, Hg, Sb, Ni, Mo, Mn, Ir, and U-were also recovered. Zinc-dominant carbonate replacement deposits (Zn > Pb; Ag ?? Cu) resemble Mississippi Valley Type (MVT) Zn-Pb deposits in that they occur in karst and fault breccias in Mississippian limestone where the southern margin of the regional late Paleozoic foreland basin adjoins Proterozoic crystalline rocks of the craton. They consist of calcite, dolomite, sphalerite, and galena with variably positive S isotope compositions (??34S values range from 2.5-13%), and highly radiogenic Pb isotope compositions (206Pb/204Pb >19), typical of MVT deposits above crystalline Precambrian basement. These deposits may have formed when southward flow of saline fluids, derived from basinal and older sedimentary rocks, encountered thinner strata and pinch-outs against the craton, forcing fluid mixing and mineral precipitation in karst and fault breccias. Lead-dominant carbonate replacement deposits (Pb > Zn, Ag ?? Cu ?? Au) occur among other deposit types, often near porphyritic intrusions. They generally contain higher concentrations of precious metals than zinc-dominant deposits and relatively abundant iron oxides after pyrite. They share characteristics with copper ?? precious metal- PGE and gold ?? silver deposits including fine-grained quartz replacement of carbonate minerals in

  5. Spatial and temporal variability of (7)Be and (210)Pb wet deposition during four successive monsoon storms in a catchment of northern Laos.

    Gourdin, E; Evrard, O; Huon, S; Reyss, J-L; Ribolzi, O; Bariac, T; Sengtaheuanghoung, O; Ayrault, S


    Fallout radionuclides (7)Be and (210)Pb have been identified as potentially relevant temporal tracers for studying soil particles dynamics (surface vs. subsurface sources contribution; remobilization of in-channel sediment) during erosive events in river catchments. An increasing number of studies compared (7)Be: (210)Pb activity ratio in rainwater and sediment to estimate percentages of freshly eroded particles. However, the lack of data regarding the spatial and temporal variability of radionuclide wet deposition during individual storms has been identified as one of the main gaps in these estimates. In order to determine these key parameters, rainwater samples were collected at three stations during four storms that occurred at the beginning of the monsoon (June 2013) in the Houay Xon mountainous catchment in northern Laos. Rainwater (7)Be and (210)Pb activities measured using very low background hyperpure Germanium detectors ranged from 0.05 to 1.72 Bq L(-1) and 0.02 to 0.26 Bq L(-1), respectively. Water δ(18)O were determined on the same samples. Total rainfall amount of the four sampled storms ranged from 4.8 to 26.4 mm (51 mm in total) at the time-fractionated collection point. Corresponding cumulative (7)Be and (210)Pb wet depositions during the sampling period were 17.6 and 2.9 Bq m(-2), respectively. The (7)Be: (210)Pb activity ratio varied (1) in space from 6 to 9 for daily deposition and (2) in time from 3 to 12 for samples successively collected. Intra-event evolution of rainwater (7)Be and (210)Pb activities as well as δ(18)O highlighted the progressive depletion of local infra-cloud atmosphere radionuclide stock with time (washout), which remains consistent with a Raleigh-type distillation process for water vapour. Intra-storm ratio increasing with time showed the increasing contribution of rainout scavenging. Implications of such variability for soil particle labelling and erosion studies are briefly discussed and recommendations are formulated



    <正>20090243 Chen Zhibin (Hebei Institute of Geological Survey, Shijiazhuang 050081, China) Ore-Controlling Factors of the Beichagoumen Ag-Polymetallic Deposits in Northern Hebei Province (Geological Survey and Research, ISSN1672-4135, CN12-1353/P, 31(1), 2008, p.1-5, 3 illus., 10 refs.)

  7. Outcrop analogue study of Permocarboniferous geothermal sandstone reservoir formations (northern Upper Rhine Graben, Germany): impact of mineral content, depositional environment and diagenesis on petrophysical properties

    Aretz, Achim; Bär, Kristian; Götz, Annette E.; Sass, Ingo


    The Permocarboniferous siliciclastic formations represent the largest hydrothermal reservoir in the northern Upper Rhine Graben in SW Germany and have so far been investigated in large-scale studies only. The Cenozoic Upper Rhine Graben crosses the Permocarboniferous Saar-Nahe Basin, a Variscan intramontane molasse basin. Due to the subsidence in this graben structure, the top of the up to 2-km-thick Permocarboniferous is located at a depth of 600-2900 m and is overlain by Tertiary and Quaternary sediments. At this depth, the reservoir temperatures exceed 150 °C, which are sufficient for geothermal electricity generation with binary power plants. To further assess the potential of this geothermal reservoir, detailed information on thermophysical and hydraulic properties of the different lithostratigraphical units and their depositional environment is essential. Here, we present an integrated study of outcrop analogues and drill core material. In total, 850 outcrop samples were analyzed, measuring porosity, permeability, thermal conductivity and thermal diffusivity. Furthermore, 62 plugs were taken from drillings that encountered or intersected the Permocarboniferous at depths between 1800 and 2900 m. Petrographic analysis of 155 thin sections of outcrop samples and samples taken from reservoir depth was conducted to quantify the mineral composition, sorting and rounding of grains and the kind of cementation. Its influence on porosity, permeability, the degree of compaction and illitization was quantified. Three parameters influencing the reservoir properties of the Permocarboniferous were detected. The strongest and most destructive influence on reservoir quality is related to late diagenetic processes. An illitic and kaolinitic cementation and impregnation of bitumina document CO2- and CH4-rich acidic pore water conditions, which are interpreted as fluids that migrated along a hydraulic contact from an underlying Carboniferous hydrocarbon source rock. Migrating

  8. Depositional settings, correlation, and age carboniferous rocks in the western Brooks Range, Alaska

    Dumoulin, J.A.; Harris, A.G.; Blome, C.D.; Young, L.E.


    The Kuna Formation (Lisburne Group) in northwest Alaska hosts the Red Dog and other Zn-Pb-Ag massive sulfide deposits in the Red Dog district. New studies of the sedimentology and paleontology of the Lisburne Group constrain the setting, age, and thermal history of these deposits. In the western and west-central Brooks Range, the Lisburne Group includes both deep- and shallow-water sedimentary facies and local volcanic rocks that are exposed in a series of thrust sheets or allochthons. Deep-water facies in the Red Dog area (i.e., the Kuna Formation and related rocks) are found chiefly in the Endicott Mountains and structurally higher Picnic Creek allochthons. In the Red Dog plate of the Endicott Mountains allochthon, the Kuna consists of at least 122 m of thinly interbedded calcareous shale, calcareous spiculite, and bioclastic supportstone (Kivalina unit) overlain by 30 to 240 m of siliceous shale, mudstone, calcareous radiolarite, and calcareous lithic turbidite (Ikalukrok unit). The Ikalukrok unit in the Red Dog plate hosts all massive sulfide deposits in the area. It is notably carbonaceous, is generally finely laminated, and contains siliceous sponge spicules and radiolarians. The Kuna Formation in the Key Creek plate of the Endicott Mountains allochthon (60-110 m) resembles the Ikalukrok unit but is unmineralized and has thinner carbonate layers that are mainly organic-rich dolostone. Correlative strata in the Picnic Creek allochthon include less shale and mudstone and more carbonate (mostly calcareous spiculite). Conodonts and radiolarians indicate an age range of Osagean to early Chesterian (late Early to Late Mississippian) for the Kuna in the Red Dog area. Sedimentologic, faunal, and geochemical data imply that most of the Kuna formed in slope and basin settings characterized by anoxic or dysoxic bottom water and by local high productivity. Shallow-water facies of th e Lisburne Group in the Red Dog area are present locally in the Endicott Mountains

  9. Investigation of the Impact of Stone Bunds on Erosion and Deposition Processes combining Conventional and Tracer Methodology in the Gumara Maksegnit Watershed, Northern Highlands of Ethiopia

    Obereder, Eva Maria; Wakolbinger, Stefanie; Guzmán, Gema; Strohmeier, Stefan; Demelash, Nigus; Gomez, José Alfonso; Klik, Andreas


    Ethiopia is one of the poorest countries of the word, with over 85 % of total population dependent from agriculture. Massive deforestation in the past and missing soil and water conservation (SWC) measures cause severe soil erosion problems in the northern highlands of Ethiopia. Different SWC methods are supposed to prevent ongoing land degradation, which is triggered by rainfall driven soil erosion in the Ethiopian agricultural lands. Common technologies for soil and water conservation are stone bunds, which reduce surface runoff and sediment loss. In June 2015 two field experiments were set up in the Gumara-Maksegnit watershed in Northern Ethiopia. The objective of this study was to evaluate the impact of graded stone bunds on surface runoff and sediment yield by using conventional and tracing approaches. Three consecutive runoff plots of 20 x 4 m length and width, respectively were established along the maximum slope direction. Each one was separated to the downstream one by a stone bund. The experimental setup allowed the measurement of surface runoff along each stone bund and the measurement of overflow over the lowest stone bund. To assess the pathway and the spatial distribution of the sediments a different tracer (Magnetite, Hematite and Goethite) was applied in a 40 cm wide strip at the top of each one of the plots. The second tracer experiment was conducted on the same hillslope. It consisted of a 20 m long hillslope without borders in which a 4 m long and 40 cm wide Magnetite strip was placed at the top. At the end of August 2015 soil samples of 0-2 cm depth were taken in a 1.5 x 1.5 m grid within the area of the hillslope. Soil samples parallel to the stone bund (above and underneath) were taken along 16 m to assess the soil movement/deposition. Tracer concentrations of soil and sediment samples in both trials were analysed. Runoff and sediment were collected in weekly intervals from July to September. Runoff and erosion data, as well as the evaluation

  10. Evidence for large-magnitude, post-Eocene extension in the northern Shoshone Range, Nevada, and its implications for Carlin-type gold deposits in the lower plate of the Roberts Mountains allochthon

    Colgan, Joseph P.; Henry, Christopher D.; John, David A.


    The northern Shoshone and Toiyabe Ranges in north-central Nevada expose numerous areas of mineralized Paleozoic rock, including major Carlin-type gold deposits at Pipeline and Cortez. Paleozoic rocks in these areas were previously interpreted to have undergone negligible postmineralization extension and tilting, but here we present new data that suggest major post-Eocene extension along west-dipping normal faults. Tertiary rocks in the northern Shoshone Range crop out in two W-NW–trending belts that locally overlie and intrude highly deformed Lower Paleozoic rocks of the Roberts Mountains allochthon. Tertiary exposures in the more extensive, northern belt were interpreted as subvertical breccia pipes (intrusions), but new field data indicate that these “pipes” consist of a 35.8 Ma densely welded dacitic ash flow tuff (informally named the tuff of Mount Lewis) interbedded with sandstones and coarse volcaniclastic deposits. Both tuff and sedimentary rocks strike N-S and dip 30° to 70° E; the steeply dipping compaction foliation in the tuffs was interpreted as subvertical flow foliation in breccia pipes. The southern belt along Mill Creek, previously mapped as undivided welded tuff, includes the tuff of Cove mine (34.4 Ma) and unit B of the Bates Mountain Tuff (30.6 Ma). These tuffs dip 30° to 50° east, suggesting that their west-dipping contacts with underlying Paleozoic rocks (previously mapped as depositional) are normal faults. Tertiary rocks in both belts were deposited on Paleozoic basement and none appear to be breccia pipes. We infer that their present east tilt is due to extension on west-dipping normal faults. Some of these faults may be the northern strands of middle Miocene (ca. 16 Ma) faults that cut and tilted the 34.0 Ma Caetano caldera ~40° east in the central Shoshone Range (

  11. Source and evolution of ore-forming hydrothermal fluids in the northern Iberian Pyrite Belt massive sulphide deposits (SW Spain): evidence from fluid inclusions and stable isotopes

    Sánchez-España, Javier; Velasco, Francisco; Boyce, Adrian J.; Fallick, Anthony E.


    A fluid inclusion and stable isotopic study has been undertaken on some massive sulphide deposits (Aguas Teñidas Este, Concepción, San Miguel, San Telmo and Cueva de la Mora) located in the northern Iberian Pyrite Belt. The isotopic analyses were mainly performed on quartz, chlorite, carbonate and whole rock samples from the stockworks and altered footwall zones of the deposits, and also on some fluid inclusion waters. Homogenization temperatures of fluid inclusions in quartz mostly range from 120 to 280 °C. Salinity of most fluid inclusions ranges from 2 to 14 wt% NaCl equiv. A few cases with Th=80-110 °C and salinity of 16-24 wt% NaCl equiv., have been also recognized. In addition, fluid inclusions from the Soloviejo Mn-Fe-jaspers (160-190 °C and ≈6 wt% NaCl equiv.) and some Late to Post-Hercynian quartz veins (130-270 °C and ≈4 wt% NaCl equiv.) were also studied. Isotopic results indicate that fluids in equilibrium with measured quartz (δ18Ofluid ≈-2 to 4‰), chlorites (δ18Ofluid ≈8-14‰, δDfluid ≈-45 to -27‰), whole rocks (δ18Ofluid ≈4-7‰, δDfluid ≈-15 to -10‰), and carbonates (δ18Oankerite ≈14.5-16‰, δ13Cfluid =-11 to -5‰) evolved isotopically during the lifetime of the hydrothermal systems, following a waxing/waning cycle at different temperatures and water/rock ratios. The results (fluid inclusions, δ18O, δD and δ13C values) point to a highly evolved seawater, along with a variable (but significant) contribution of other fluid reservoirs such as magmatic and/or deep metamorphic waters, as the most probable sources for the ore-forming fluids. These fluids interacted with the underlying volcanic and sedimentary rocks during convective circulation through the upper crust.

  12. Time relationships between volcanism-plutonism-alteration-mineralization in Cu-stratabound ore deposits from the Michilla mining district, northern Chile: a 40Ar/39Ar geochronological approach

    Oliveros, Verónica; Tristá-Aguilera, Dania; Féraud, Gilbert; Morata, Diego; Aguirre, Luis; Kojima, Shoji; Ferraris, Fernando


    The Michilla mining district comprises one of the most important stratabound and breccia-style copper deposits of the Coastal Cordillera of northern Chile, hosted by the Middle Jurassic volcanic rocks of the La Negra Formation. 40Ar/39Ar analyses carried out on igneous and alteration minerals from volcanic and plutonic rocks in the district allow a chronological sequence of several magmatic and alteration events of the district to be established. The first event was the extrusion of a thick lava series of the La Negra Formation, dated at 159.9 ± 1.0 Ma (2 σ) from the upper part of the series. A contemporaneous intrusion is dated at 159.6 ± 1.1 Ma, and later intrusive events are dated at 145.5 ± 2.8 and 137.4 ± 1.1 Ma, respectively. Analyzed alteration minerals such as adularia, sericite, and actinolite apparently give valid 40Ar/39Ar plateau and miniplateau ages. They indicate the occurrence of several alteration events at ca. 160-163, 154-157, 143-148, and 135-137 Ma. The first alteration event, being partly contemporaneous with volcanic and plutonic rocks, was probably produced in a high thermal gradient environment. The later events may be related either to a regional low-grade hydrothermal alteration/metamorphism process or to plutonic intrusions. The Cu mineralization of the Michilla district is robustly bracketed between 163.6 ± 1.9 and 137.4 ± 1.1 Ma, corresponding to dating of actinolite coexisting with early-stage chalcocite and a postmineralization barren dyke, respectively. More precisely, the association of small intrusives (a dated stock from the Michilla district) with Cu mineralization in the region strongly suggests that the main Michilla ore deposit is related to a magmatic/hydrothermal event that occurred between 157.4 ± 3.6 and 163.5 ± 1.9 Ma, contemporaneous or shortly after the extrusion of the volcanic sequence. This age is in agreement with the Re-Os age of 159 ± 16 Ma obtained from the mineralization itself (Tristá-Aguilera et al

  13. The Chineysky gabbronorite-anorthosite layered massif (NorthernTransbaikalia, Russia): its structure, Fe-Ti-V and Cu-PGE deposits, and parental magma composition

    Gongalsky, Bronislav I.; Krivolutskaya, Nadezhda A.; Ariskin, Alexey A.; Nikolaev, George S.


    The 1858 ± 17 Ma Chineysky layered anorthosite-gabbronorite massif is located in the southern part of the Siberian platform, within the Kodaro-Udokan metallogenic province of Northern Transbaikalia. The Chineysky Massif outcrops over approximately 130 km2 and contains Russia's largest V ore resources, hosted within titanomagnetite-rich layers, concentrated in the Magnitny and Etyrko deposits. The titanomagnetite ore reserves were estimated at 2 billion tons with 30 % Fe and 10 % TiO2 on average. In addition, two large Cu-PGE deposits—Rudny and Kontactovy—are hosted in the contact rocks between the intrusion and the sandstone floor rocks. A distinctive feature of the Chineysky sulfide ore is their Cu-enriched composition with much lesser amounts of nickel and cobalt (Cu/Ni/Co 76:7:1). The sulfide ore contains up to 355 ppm PGE and 30 ppm Au + Ag. Three types of sulfide mineralization have been distinguished: (1) endo-contact disseminated sulfides within gabbronorite, (2) exo-contact impregnations in sandstone, and (3) veins of massive sulfides in the exo-contact sandstone. The ore consists predominantly of chalcopyrite, with less abundant pentlandite, pyrrhotite, Co-Ni arsenides and sulfoarsenides, linneite-group minerals, sphalerite, cubanite, and millerite. In addition, many rare minerals were recognized in the ores, including PGM (sperrylite, michenerite, merenskyite, etc.). Using the latest version of the COMAGMAT-5 program, the parental magma temperature ( 1150 °C), its composition ( 55 wt.% SiO2, 5.8 % MgO), and the most primitive olivine (Fo77) and plagioclase (An69) compositions were calculated. According to the model, titanomagnetite starts to crystallize at T < 1133 °C (fO2 = NNO + 0.5), triggering sulfide liquid immiscibility when the silicate magma had 0.15 to 0.1 wt.% S.

  14. Depositional architecture and evolution of inner shelf to shelf edge delta systems since the Late Oliocene and their respone to the tectonic and sea level change, Pear River Mouth Basin, northern South China Sea

    Lin, Changsong; Zhang, Zhongtao; liu, Jingyan; Jiang, Jing


    The Pear River Mouth Basin is located in the northern continent margin of the South China Sea. Since the Late Oligocene, the long-term active fluvial systems (Paleo-Zhujiang) from the western basin margin bebouched into the northern continental margin of the South China Sea and formed widespread deltaic deposits in various depositional geomorphologies and tectonic settings. Based of integral analysys of abundant seismic, well logging and drilling core data, Depositional architecture and evolution of these delta systems and their respone to the tectonic and sea level change are documented in the study. There are two basic types of the delta systems which have been recognized: inner shelf delta deposited in shallow water enviroments and the outer shelf or shelf-edge delta systems occurred in deep water settings. The paleowater depths of these delta systems are around 30 to 80m (inner shelf delta) and 400-1000m (shelf-edge delta) estimated from the thickness (decompaction) of the delta front sequences. The study shows that the inner shelf delta systems are characterized by relatively thin delta forests (20-40m), numereous stacked distributary channel fills, relative coarse river mouth bar deposits and thin distal delta front or distal bar and prodelta deposits. In contrast, the outer shelf or shelf edge delta systems are characteristic of thick (300-800m) and steep (4-60) of deltaic clinoforms, which commonly display in 3D seismic profiles as "S" shape reflection. Large scale soft-sediment deformation structures, slump or debris flow deposits consisting mainly of soft-sediment deformed beds, blocks of sandstones and siltstones or mudstones widely developed in the delta front deposits. The shelf edge delta systems are typically associated with sandy turbidite fan deposits along the prodelta slopes, which may shift basinwards as the progradation of the delta systems. The delta systems underwent several regional cycles of evolution from inner shelf deltas to shelf edge

  15. Floodplain deposits, channel changes and riverbank stratigraphy of the Mekong River area at the 14th-Century city of Chiang Saen, Northern Thailand

    Wood, Spencer H.; Ziegler, Alan D.; Bundarnsin, Tharaporn


    Riverbank stratigraphy and paleochannel patterns of the Mekong River at Chiang Saen provide a geoarchaeological framework to explore for evidence of Neolithic, Bronze-age, AD 5th Century Yonok and AD 14-16th Century Lan Na Cultures. Typical bank stratigraphy charted on the Thailand side is imbricate cobble gravel overlain by 5-10 m of reddish-brown sandy silt. The silt section is composed chiefly of 1/2 to 2-m thick layers of massive silt without paleosols interpreted as near-channel floodplain and gently-inclined levee deposits laid down by episodic, infrequent, large floods. The surface soil is dark-brown clay loam (pottery shards and charcoal of Lan Na time. Brick ruins of 14-16th Century Buddhist temples are crumbling into the river at Chiang Saen Noi, and formerly did so at Chiang Saen until banks were stabilized by rock walls. Bank retreat from river erosion has been > 20 m since Lan Na time, and has exposed a silt-filled moat. A radiocarbon age of 1475 cal yr AD was obtained from charcoal at the bottom of the moat, beneath 5.6 m of silt. Lag material from erosion of the silt banks contains Neolithic and Bronze Age artifacts out of stratigraphic context, as well as ceramics and bricks of Lan Na age. These artifacts as well Neolithic artifacts obtained from a 1972 excavation near the mouth of the Kham River indicate long human habitation of this riverbank area. In northern Thailand the Mekong is mostly in a bedrock canyon, but shifting topography along the active strike-slip Mae Chan fault has formed the upstream 2-5-km wide floodplain at Chiang Saen, and downstream has diverted the river into a broad S-shaped loop in the otherwise straight course of the river. A 1.7-Ma basalt within the bedrock channel 45-km downstream of Chiang Saen indicates little vertical incision by the river. Satellite images show former channels in the Chiang Saen area, meander-point-bar scrolls (radii of curvature > 1.2 km), and floodplain edges as arcuate cuts of similar curvature

  16. Morphologies and depositional/erosional controls on evolution of Pliocene-Pleistocene carbonate platforms: Northern Carnarvon Basin, Northwest Shelf of Australia

    Goktas, P.; Austin, J. A.; Fulthorpe, C. S.; Gallagher, S. J.


    The detailed morphologies, evolution and termination of latest Neogene tropical carbonate platforms in the Northern Carnarvon Basin (NCB), on the passive margin of the Northwest Shelf (NWS) of Australia, defined based upon mapping using 3D seismic images, reveal the history of local/regional oceanographic processes, fluctuations in relative sea-level and changing climate. Cool-water carbonate deposition, dominant during the early-middle Miocene, was followed by a siliciclastic influx, which prograded across the NWS beginning in the late-middle Miocene, during a period of long-term global sea-level fall. The resulting prograding clinoform sets, interpreted as delta lobes, created relict topographic highs following Pliocene termination of the siliciclastic influx. These highs constituted multiple favorable shallow-water environments for subsequent photozoan carbonate production. Resultant platform carbonate development, in addition to being a response to cessation of siliciclastic influx and the existence of suitable shallow-water substrate, was also influenced by development of the warm-water Leeuwin Current (LC), flowing southwestward along this margin. Four flat-topped platforms are mapped; each platform top is a sequence boundary defined by reflection onlap above and truncation below. Successive platforms migrated southwestward through time, along margin strike. All platforms exhibit predominantly progradational seismic geometries. Mapped tops are ≥10 km wide. Seismic evidence of karst on three of four platform tops, e.g., v-shaped troughs up to 50 m deep and ~1 km wide, and broader basins with areas up to 20 km2, suggests episodic subaerial exposure that may have contributed to platform demise. Platform 4, the most recent, is unique in having interpreted biohermal build-ups superimposed on the progradational platform base. The base of these interpreted patch reefs now lies at a water depth of ~153 m; therefore, we suggest that these reefs developed post

  17. 2.8-Ma ash-flow caldera at Chegem River in the northern Caucasus Mountains (Russia), contemporaneous granites, and associated ore deposits

    Lipman, P.W.; Bogatikov, O.A.; Tsvetkov, A.A.; Gazis, C.; Gurbanov, A.G.; Hon, K.; Koronovsky, N.V.; Kovalenko, V.I.; Marchev, P.


    , and associated aplitic phases have textural features of Climax-type molybdenite porphyries in the western USA. Similar 40Ar/39Ar ages, mineral chemistry, and bulk-rock compositions indicate that the Chegem Tuff, intracaldera intrusion, and Eldjurta Granite are all parts of a large magmatic system that broadly resembles the middle Tertiary Questa caldera system and associated Mo deposits in northern New Mexico, USA. Because of their young age and superb three-dimensional exposures, rocks of the Chegem-Tirniauz region offer exceptional opportunities for detailed study of caldera structures, compositional gradients in volcanic rocks relative to cogenetic granites, and the thermal and fluid-flow history of a large young upper-crustal magmatic system. ?? 1993.

  18. GIS analysis of vulnerability to acidic deposition of soils in a region of the Northern Appennines; Uso di tecniche GIS per lo studio della sensibilita` alle deposizioni acide dei suoli di una area dell`Appennino piacentino e parmense

    Vincini, Massimo [Piacenza, Univ. Cattolica del Sacro Cuore (Italy). Lab. Centralizzato Radioisotopi; Solinas, Chiara [Piacenza, Univ. Cattolica del Sacro Cuore (Italy). Fac. di Agraria. Istituto di Entomologia e Patologia Vegetale


    A study on the vulnerability to acidic depositions of the soils of forested ecosystems is conducted by GIS analysis in a region of the Northern Appennines. On the basis of soil pH and yearly precipitation the yearly soil intake of H{sup +} from unpolluted rain (pH 5.6) is calculated by Henderson-Hasselbach equation. The area of possible vulnerability to strong acidic anions such as SO{sub 4}{sup 2-} (soil pH {<=} 5.8 and lime content {<=} 0.5 %) is related to yearly precipitation in order to show the extension and the localization of forested ecosystems whose soils are more likely affected by base leaching as a long-term consequence of acidic depositions.

  19. Hydrothermal, biogenic, and seawater components in metalliferous black shales of the Brooks Range, Alaska: Synsedimentary metal enrichment in a carbonate ramp setting

    Slack, John F.; Selby, David; Dumoulin, Julie A.


    Trace element and Os isotope data for Lisburne Group metalliferous black shales of Middle Mississippian (early Chesterian) age in the Brooks Range of northern Alaska suggest that metals were sourced chiefly from local seawater (including biogenic detritus) but also from externally derived hydrothermal fluids. These black shales are interbedded with phosphorites and limestones in sequences 3 to 35 m thick; deposition occurred mainly on a carbonate ramp during intermittent upwelling under varying redox conditions, from suboxic to anoxic to sulfidic. Deposition of the black shales at ~335 Ma was broadly contemporaneous with sulfide mineralization in the Red Dog and Drenchwater Zn-Pb-Ag deposits, which formed in a distal marginal basin.Relative to the composition of average black shale, the metalliferous black shales (n = 29) display large average enrichment factors (>10) for Zn (10.1), Cd (11.0), and Ag (20.1). Small enrichments (>2–metals.Average authigenic (detrital-free) contents of Mo, V, U, Ni, Cu, Cd, Pb, Ge, Re, Se, As, Sb, Tl, Pd, and Au show enrichment factors of 4.3 × 103 to 1.2 × 106 relative to modern seawater. Such moderate enrichments, which are common in other metalliferous black shales, suggest wholly marine sources (seawater and biogenic material) for these metals, given similar trends for enrichment factors in organic-rich sediments of modern upwelling zones on the Namibian, Peruvian, and Chilean shelves. The largest enrichment factors for Zn and Ag are much higher (1.4 × 107 and 2.9 × 107, respectively), consistent with an appreciable hydrothermal component. Other metals such as Cu, Pb, and Tl that are concentrated in several black shale samples, and are locally abundant in the Red Dog and Drenchwater Zn-Pb-Ag deposits, may have a partly hydrothermal origin but this cannot be fully established with the available data. Enrichments in Cr (up to 7.8 × 106) are attributed to marine and not hydrothermal processes. The presence in some samples

  20. Influence of Late Paleozoic Gondwana glaciations on the depositional evolution of the northern Pangean shelf, North Greenland, Svalbard and the Barents Sea

    Stemmerik, Lars


    fluctuations linked to the 100 k.y. Milankovitch cycle. The stratigraphic distribution of subaerial exposure surfaces indicates that during Late Carboniferous-Early Permian time, the northern Pangea shelf repeatedly changed from being a shallow subtropical carbonate platform to a vast subaerially exposed...

  1. Problems of borehole drilling, prospecting and mining the gas deposits in the northern Kavkaza and Uzbekistan. Voprosi bureniia skvazhin, razvedki i razrabotki gazovykh mestorozhdenii severnogo kavkaza i uzbbekistana


    The scientific aspect of borehole drilling, prospecting and mining the fields in the northern Kavkaz during the period when a decline in gas production exists are given together with predictions on the presence of certain structures that are favorable for finding oil and gas in the Uzbekistan SSR. An analysis of gas field mining in the regions and various stages are also given.

  2. Geochemical and stable isotopic data on barren and mineralized drill core in the Devonian Popovich Formation, Screamer sector of the Betze-Post gold deposit, northern Carlin trend, Nevada

    Christiansen, William D.; Hofstra, Albert H.; Zohar, Pamela B.; Tousignant, Gilles


    The Devonian Popovich Formation is the major host for Carlin-type gold deposits in the northern Carlin trend of Nevada. The Popovich is composed of gray to black, thin-bedded, calcareous to dolomitic mudstone and limestone deposited near the carbonate platform margin. Carlin-type gold deposits are Eocene, disseminated, auriferous pyrite deposits characterized by acid leaching, sulfidation, and silicification that are typically hosted in Paleozoic calcareous sedimentary rocks exposed in windows through siliceous sedimentary rocks of the Roberts Mountains allochthon. The Carlin trend currently is the largest gold producer in the United States. The Screamer ore zone is a tabular body on the periphery of the huge Betze-Post gold deposit. Screamer is a good place to study both the original lithogeochemistry of the Popovich Formation and the effects of subsequent alteration and mineralization because it is below the level of supergene oxidation, mostly outside the contact metamorphic aureole of the Jurassic Goldstrike stock, has small, high-grade ore zones along fractures and Jurassic dikes, and has intervening areas with lower grade mineralization and barren rock. In 1997, prior to mining at Screamer, drill core intervals from barren and mineralized Popovich Formation were selected for geochemical and stable isotope analysis. The 332, five-foot core samples analyzed are from five holes separated by as much as 2000 feet (600 meters). The samples extend from the base of the Wispy unit up through the Planar and Soft sediment deformation units into the lower part of the upper Mud unit of the Popovich Formation.

  3. Facies transition and depositional architecture of the Late Eocene tide-dominated delta in northern coast of Birket Qarun, Fayum, Egypt

    Abdel-Fattah, Zaki A.


    Late Eocene successions in the Fayum Depression display notable facies transition from open-marine to brackish-marine realms. Stratigraphic and sedimentologic characteristics of the depositional facies are integrated with ichnological data for the recognition of four facies associations (FA1 to FA4). The transition from open-marine sandstones (FA1) to the brackish-marine deposits (FA2) heralds a transgressive - regressive dislocation. The shallowing- and coarsening-upward progradation from the basal prodelta mudstone-dominated facies (FA2a) to deltafront heterolithics (FA2b) and sandstone facies (FA2c) are overlain by finning-upward delta plain deposits which are expressed by the delta plain mudstone (FA2d) and erosive-based distributary channel fills (FA4). Prodelta/deltfront deposits of FA2 are arranged in thinning- and coarsening-upward parasequences which are stacked in a shallowing-upward progressive cycle. Shallow-marine fossiliferous sandstones (FA3) mark the basal part of each parasequence. Stratigraphic and depositional architectures reflect a tide-dominated delta rather than an estuarine and incised valley (IV) model. This can be evinced by the progressive facies architecture, absence of basal regional incision or a subaerial unconformity and the stratigraphic position above a maximum flooding surface (MFS), in addition to the presence of multiple tidally-influenced distributary channels. Stratigraphic and depositional characteristics of the suggested model resemble those of modern tide-dominated deltaic systems. Accordingly, this model contributes to our understanding of the depositional models for analogous brackish-marine environments, particularly tide-dominated deltas in the rock record.

  4. Internal structure and depositional environment of Late Carboniferous mounds from the San Emiliano Formation, Cármenes Syncline, Cantabrian Mountains, Northern Spain


    Well-exposed mounds are common in limestone of the Late Carboniferous San Emiliano Formation, Cantabrian Mountains (Northern Spain). They occur as obvious primary topographic features. Careful study of the mound intervals and surrounding strata revealed the internal structures of mounds and the factors controlling their growth. The substrate (2–3 m) of the mounds consists of greyish to reddish, bedded oolitic and oncolithic packstone and grainstone. Crinoids, fragments of the alga Epimastopor...

  5. Lagerstroemia L. from the middle Miocene Siwalik deposits, northern India: Implication for Cenozoic range shifts of the genus and the family Lythraceae

    Gaurav Srivastava; Rajan Gaur; R C Mehrotra


    Fossil leaves of Lagerstroemia (Lythraceae) are described from the Siwalik deposits (middle Miocene) of Kathgodam, Uttarakhand, India. The fossil records of the Lythraceae indicate its worldwide distribution in the Cenozoic. The family had its widest distribution during the Miocene but became less widespread during the Pliocene, followed by range expansion during the Quaternary. The present leaf fossil, along with the previous fossil records of Lagerstroemia, indicates that the genus followed the same pattern of expansion and retraction as the entire family Lythraceae suggesting that both the genus and the family adapted in similar ways. The fossil plant assemblage from the Lower Siwalik deposits indicates warm and humid climate with plenty of rainfall in the region during the depositional period.

  6. Electrical and well log study of the Plio-Quaternary deposits of the southern part of the Rharb Basin, northern Morocco

    El Bouhaddioui, Mohamed; Mridekh, Abdelaziz; Kili, Malika; El Mansouri, Bouabid; El Gasmi, El Houssine; Magrane, Bouchaib


    The Rharb Basin is located in the NW of Morocco. It is the onshore extension of a lager offshore basin between Kenitra and Moulay Bousselham. The Rharb plain (properly called) extends over an area of 4200 Km2 between two very different structural entities: the unstable Rif domain in the NE and the East and the ''relatively stable'' Meseta domain in the south. The distribution of Pliocene-Quaternary deposits under this plain is complex and was controlled by both tectonics and climatic factors. The main objective of the present work is to define the spatiotemporal evolution of these deposits in the onshore part of the basin and to make a comparison with a sequence analysis defined, for equivalent deposits in the offshore basin, by a previous work. The proposed model allows thus to characterize the geometry of these deposits in the extension of continental shelf under the present day onshore basin, and to explain there is genesis in terms of interactions between eustatic sea level fluctuations, tectonics and sedimentary rates at the mouths of paleo-rivers that had drained the Rharb plain during Pliocene to Quaternary Times.

  7. Cascadia Tsunami Deposit Database

    Peters, Robert; Jaffe, Bruce; Gelfenbaum, Guy; Peterson, Curt


    The Cascadia Tsunami Deposit Database contains data on the location and sedimentological properties of tsunami deposits found along the Cascadia margin. Data have been compiled from 52 studies, documenting 59 sites from northern California to Vancouver Island, British Columbia that contain known or potential tsunami deposits. Bibliographical references are provided for all sites included in the database. Cascadia tsunami deposits are usually seen as anomalous sand layers in coastal marsh or lake sediments. The studies cited in the database use numerous criteria based on sedimentary characteristics to distinguish tsunami deposits from sand layers deposited by other processes, such as river flooding and storm surges. Several studies cited in the database contain evidence for more than one tsunami at a site. Data categories include age, thickness, layering, grainsize, and other sedimentological characteristics of Cascadia tsunami deposits. The database documents the variability observed in tsunami deposits found along the Cascadia margin.

  8. Depositional framework and regional correlation of pre-Carboniferous metacarbonate rocks of the Snowden Mountain area, central Brooks Range, Northern Alaska

    Dumoulin, J.A.; Harris, A.G.


    This report describes lithofacies, conodont biostratigraphy and biofacies, and depositional environments of Proterozoic(?) through Devonian metacarbonate rocks in the Snowden Mountain area. These rocks are correlated with successions on the Seward Peninsula and across the Brooks Range. Lithologic and paleobiogeographic data suggest that these successions formed along a single continental margin which had faunal exchange with both North America and Siberia, rather than on a series of discrete platforms juxtaposed by later tectonic events.

  9. Microbial Mn(IV) and Fe(III) reduction in northern Barents Sea sediments under different conditions of ice cover and organic carbon deposition

    Nickel, Maren; Vandieken, Verona; Brüchert, Volker;


    reduction occurred simultaneously, and sulfate reduction dominated at 3-12 cm. Oxygen consumption rates (1.9 and 3.7 mmol m-2 d-1) and anaerobic CO2 production rates (1.3 and 6.4 mmol m-2 d-1) of both stations were similar to rates from open-ocean sediments farther north in the Barents Sea but lower......Carbon oxidation rates and pathways were determined in two sediments at latitude 75° and 77°N southeast of Svalbard in the northern Barents Sea. Seasonal ice cover restricts primary production to few months a year, which determines the sedimentation rate of organic material to the seafloor. At one...

  10. Basement influences on dolomite-hosted vertical sedimentary intrusions in marine erg-margin deposits from the Pennsylvanian of Northern Wyoming (USA)

    Blanchard, Sébastien; Frank, Tracy D.; Fielding, Christopher R.


    Understanding soft-sediment deformation structures and their triggers can help in assessing the influence of tectonics, climate, and diagenesis on the stratigraphic record. Such features commonly record processes that would not otherwise be preserved. The description of soft-sediment deformation in Pennsylvanian deposits of the western United States, characterized by orbitally driven alternations between eolian sandstones, marine dolomites, and shales, has been limited to contorted cross-beds. We document discordant, sheet-like sedimentary intrusions in three marine intervals over a 45-km-wide area. Intrusions consist of very well to moderately cemented, very fine to fine-grained quartz sandstone. Body widths range from 5 to 50 cm, and heights up to 2 m. The orientations of 103 vertical bodies were measured. Based on upward- and downward-tapering, and the presence of deformed, microfractured fragments of host rocks, these intrusions are interpreted to result from seismically induced fluidization of water-saturated sands. Their sheet-like morphology indicates injection through fractures. Two predominant directions (WNW-ESE and N-S) were recognized and interpreted as pre-injection fracture sets. Folding of surrounding layers around the intrusions suggests negligible compaction prior to injection, indicating penecontemporaneous or shallow burial fluidization. The intraplate location of Wyoming implies that seismicity did not originate at a plate boundary. The area within which intrusions are found is crossed by a zone characterized by localized development of thick eolian stories at the top of the formation, interpreted to reflect the rejuvenation of a basement lineament. The seismically active character of lineaments may explain overpressure and fluidization, substantiating the notion that Precambrian structures repeatedly affected Phanerozoic sedimentation. Similar intrusive features may be wrongly identified or overlooked in deposits of arid environments, but their

  11. Multi-approach study (preliminary essays) to understand the paleoenvironmental and paleoclimatic conditions related to the genesis of exotic Cu-deposits, northern Chile

    Fernandez Mort, A.; Riquelme, R.; Cabezas, A.; Muñoz, S.; Pizarro, H.


    Late Cenozoic (10 Ma) secondary Cu-sulfides and, eventually, exotic Cu-deposits are considerably common within the Atacama Desert. These deposits are supposed to have a strong relationship with the paleoenvironmental and paleoclimatic conditions from that time. A study of the Tesoro Basin attempts to understand these connections using two proxies: clay mineral analysis and magnetic properties. Results obtained from both techniques are compared and related to the stratigraphic record previously determined in this area. Three main geological units are distinguished: Zanja perimetral gravels, Quebrada Los Arrieros gravels and Quebrada Los Arrieros fine-grained deposits. Clay mineral analysis results (fig. 1) help to confirm the paleoenvironmental meaning of the different facies associations located in the Quebrada Los Arrieros gravels. Variations in smectite, kaosmectite and illite contents can be explained as changes in the ability of being transported and selected in the sedimentary system. A priori, smectite crystals are smaller and form low-density agglomerates. They are probably able to be in suspension for a relatively longer time than the other clay minerals. Thus, some kind of preferential selection is expected during transportation of (detrital) clays. The magnetic properties (fig. 2) are the key to understanding the hydrologic variations through time in the Quebrada Los Arrieros fine-grained deposits. Correlation between magnetic properties and facies associations suggest that the hydrologic regime controls the amount of detrital minerals vs. neoformed ferromagnetic minerals. Higher values of magnetic susceptibility are correlated to strata with finer particles, which are interpreted as the result of higher water table periods. These results, combined with the stratigraphic record and the different paleosols observed, suggest a trend of formation commencing with a relatively humid period that progressively changes to a period of dessication. It remains

  12. 闽北果园生态系统大气氮湿沉降研究%Study on Wet Deposition of Atmospheric Nitrogen in Orchard Ecosystem of Northern Fujian

    刘尔平; 刘桂生; 雷俊杰


    研究了2011年3月至2012年2月期间闽北果园生态系统中大气氮素湿沉降浓度、沉降量的变化规律.结果表明:监测期间降水中总氮(TN)、无机氮(TIN)、溶解有机氮(DON)、铵态氮(NH4+-N)和硝态氮(N03- -N)的平均浓度分别为2.11、1.07、1.04、0.65和0.42 mg/L.湿沉降氮量有明显的季节性变化,春、夏季高,秋、冬季低.TN年沉降量为23.19 kg/hm2,其中NH4+ -N、NO3--N和DON年沉降量分别占TN年沉降量的30.60%、20.02%和49.38%.%The wet - deposition concentration and amount of atmospheric nitrogen in the orchard ecosystem of northern Fujian province were studied from May, 2011 to February, 2012. The results indicated that the average concentration of total nitrogen (TN) , total inorganic nitrogen (TIN) , dissolved organic nitrogen ( DON) , ammonium nitrogen ( NH4 - N) and nitrate nitrogen ( NO3 -N ) in the rainwater during monitoring was 2.11, 1. 07, 1.04, 0. 65 and 0.42 mg/L, respectively. The amount of nitrogen wet - deposition had an obvious seasonal change, and it was high in spring and summer, low in autumn and winter. Annual TN wet - deposition amount was 23. 19 kg/hm2 , and the annual wet - deposition amount of NH4 + - N, NO3 - N and DON accounted for 30. 60% , 20.02% and 49. 38% of the annual TN wet -deposition amount, respectively.

  13. The transtensional offshore portion of the northern San Andreas fault: Fault zone geometry, late Pleistocene to Holocene sediment deposition, shallow deformation patterns, and asymmetric basin growth

    Beeson, Jeffrey W.; Johnson, Samuel Y.; Goldfinger, Chris


    We mapped an ~120 km offshore portion of the northern San Andreas fault (SAF) between Point Arena and Point Delgada using closely spaced seismic reflection profiles (1605 km), high-resolution multibeam bathymetry (~1600 km2), and marine magnetic data. This new data set documents SAF location and continuity, associated tectonic geomorphology, shallow stratigraphy, and deformation. Variable deformation patterns in the generally narrow (∼1 km wide) fault zone are largely associated with fault trend and with transtensional and transpressional fault bends.We divide this unique transtensional portion of the offshore SAF into six sections along and adjacent to the SAF based on fault trend, deformation styles, seismic stratigraphy, and seafloor bathymetry. In the southern region of the study area, the SAF includes a 10-km-long zone characterized by two active parallel fault strands. Slip transfer and long-term straightening of the fault trace in this zone are likely leading to transfer of a slice of the Pacific plate to the North American plate. The SAF in the northern region of the survey area passes through two sharp fault bends (∼9°, right stepping, and ∼8°, left stepping), resulting in both an asymmetric lazy Z–shape sedimentary basin (Noyo basin) and an uplifted rocky shoal (Tolo Bank). Seismic stratigraphic sequences and unconformities within the Noyo basin correlate with the previous 4 major Quaternary sea-level lowstands and record basin tilting of ∼0.6°/100 k.y. Migration of the basin depocenter indicates a lateral slip rate on the SAF of 10–19 mm/yr for the past 350 k.y.Data collected west of the SAF on the south flank of Cape Mendocino are inconsistent with the presence of an offshore fault strand that connects the SAF with the Mendocino Triple Junction. Instead, we suggest that the SAF previously mapped onshore at Point Delgada continues onshore northward and transitions to the King Range thrust.

  14. Prediction of Exploration Target Areas for GEM Deposits in Mogok Stone Tract, Northern Myanmar by Integrating Remote Sensing and Geoscience Data

    Oo, Tin Ko


    The Mogok Stone Tract area has long been known for world famous finest ruby since 1597. The Mogok area lies in northern Myanmar and is located at about 205.99km northeast from Mandalay, the second largest city of Myanmar. The Mogok Group of metasedimentary rocks is divided into four units: (1) Wabyudaung Marble, (2) Ayenyeinchantha Calc-silicate, (3) Gwebin Quartzite, and (4) Kabe Gneiss. Igneous rocks in the Mogok area are classified into two units: (1) Kabaing Granite and (2) Pingutaung Leucogranite. The Mogok area has a complex structure involving several folds and faults. Using marbles and calc-silicates as marker horizons, a series of anticline and syncline can be identified such as Mogok syncline, Ongaing anticline, Bawpadan syncline, and Kyatpyin anticline. All the foldings show a low-angle plunge to the south. The main precious stones of the Mogok area are ruby and sapphire; and the other important semi-precious stones are spinel, topaz, peridot, garnet, apatite, beryl, tourmaline (rubellite), quartz, diopside, fluorite, and enstatite. Geological and remote sensing data are processed to extract the indicative features of gem mineralized areas: lithology, structure, and hydrothermal alteration. Density slice version of Landsat ETM band ratios 5/7 is used to map clay alterations. Filtering Landsat ETM band 5 by using edge detection filter is applied for lineament mapping. Spatial integration of various geoscience and remote sensing data sets such as geological maps, Landsat ETM images, and the location map of gem mines show the distribution of alteration zones associated with the gem mineralization in the study area. Geographic Information System (GIS) model has been designed and implemented by ARCVIEW software package based on the overlay of lithologic, lineament, and alteration vector maps. This process has resulted in delineation of most promising areas of probable gem mineralized zones as on the output map.

  15. Geochronological, stable isotopes and fluid inclusion constraints for a premetamorphic development of the intrusive-hosted Björkdal Au deposit, northern Sweden

    Billström, K.; Broman, C.; Jonsson, E.; Recio, C.; Boyce, A. J.; Torssander, P.


    The Björkdal gold deposit, bound to a quartz vein system which is mainly hosted by a quartz-monzodioritic intrusion, is situated at the easternmost part of the 1.9 Ga Skellefte base metal district in the Fennoscandian shield. Three fluid stages may be distinguished, referred to as a “barren” stage, a main gold stage, and a remobilization stage, respectively. From oxygen and hydrogen isotope evidence, it is argued that fluids of different origins (magmatic and surface waters) penetrated the ore zone at the inferred stages, but regional metamorphic fluids appear essentially only to have redistributed elements. Early quartz veining took place during a pre-metamorphic stage at ca. 1.88 Ga, as evidenced by unradiogenic galena data and an Sm-Nd scheelite errorchron of 1,915 ± 32 Ma (MSWD = 0.25). Temporarily, the main ore-forming stage was closely related to the first barren stage and took place during a major uplift event close to 1.88 Ga. Although other source rocks cannot be totally ruled out, available isotope data (O, S, Sr and Pb) are seemingly consistent with the view that these elements, and by inference other ore elements, were derived from the host intrusion.

  16. Contrasting isotopic signatures between anthropogenic and geogenic Zn and evidence for post-depositional fractionation processes in smelter-impacted soils from Northern France

    Juillot, Farid; Maréchal, Chloe; Morin, Guillaume; Jouvin, Delphine; Cacaly, Sylvain; Telouk, Philipe; Benedetti, Marc F.; Ildefonse, Philippe; Sutton, Steve; Guyot, François; Brown, Gordon E., Jr.


    Zinc isotopes have been studied along two smelter-impacted soil profiles sampled near one of the largest Pb and Zn processing plants in Europe located in northern France, about 50 km south of Lille. Mean δ 66Zn values along these two soil profiles range from +0.22 ± 0.17‰ (2 σ) to +0.34 ± 0.17‰ (2 σ) at the lowest horizons and from +0.38 ± 0.45‰ (2 σ) to +0.76 ± 0.14‰ (2 σ) near the surface. The δ 66Zn values in the lowest horizons of the soils are interpreted as being representative of the local geochemical background (mean value +0.31 ± 0.38‰), whereas heavier δ 66Zn values near the surface of the two soils are related to anthropogenic Zn. This anthropogenic Zn occurs in the form of franklinite (ZnFe 2O 4)-bearing slag grains originating from processing wastes at the smelter site and exhibiting δ 66Zn values of +0.81 ± 0.20‰ (2 σ). The presence of franklinite is indicated by EXAFS analysis of the topsoil samples from both soil profiles as well as by micro-XANES analysis of the surface horizon of a third smelter-impacted soil from a distant site. These results indicate that naturally occurring Zn and smelter-derived Zn exhibit significantly different δ 66Zn values, which suggests that zinc isotopes can be used to distinguish between geogenic and anthropogenic sources of Zn in smelter-impacted soils. In addition to a possible influence of additional past sources of light Zn (likely Zn-sulfides and Zn-sulfates directly emitted by the smelter), the light δ 66Zn values in the surface horizons compared to smelter-derived slag materials are interpreted as resulting mainly from fractionation processes associated with biotic and/or abiotic pedological processes (Zn-bearing mineral precipitation, Zn complexation by organic matter, and plant uptake of Zn). This conclusion emphasizes the need for additional Zn isotopic studies before being able to use Zn isotopes to trace sources and pathways of this element in surface environments.

  17. Lead and sulfur isotopes of Guarn Halfaya and Bou Grine deposits associated to salt dome cap rocks (Diapirs zone, Northern Tunisia): sources of metals and genetic model

    Jemmali, N.; Souissi, F.; Carranza, E. J. M.; Vennemann, T. W.


    The Pb-Zn ores districts at Guarn Halfaya and Bou Grine are hosted mainly by the dolostones in the contact breccias between Triassic and Upper Cretaceous and by Upper Cretaceous limestones. The mineralization occurs as lenticular, impregnations, substitutions, replacements, stratiform, vein, dissemination, and stockwork. A complex polymetallic sulfide assemblage typifies the main ore stage, dominated by sphalerite and galena, pyrite with minor chalcopyrite, arsenopyrite, and sulfosalt (grey copper). Limestone, barite and celestite dominate the gangue, with lesser calcite. Barite and celestite intergrown with main ore-stage sulfides of Oum Edeboua has δ34S values of 12.7 to 15.0 ‰, consistent with the derivation of sulfate from Triassic evaporites form the study area (12.8reduction (TSR) of Triassic sulfates at depth. However, the presence of bacterial relics suggests involvement of bacterially-mediated sulfate reduction (BSR). The lead isotope composition is homogeneous with 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratio ranging between from 18.723 to 18.783, 15.667 to 15.685, and 38.806 to 38.889, respectively, and plot between the upper crust and orogene curves of Zartman and Doe (1981) which imply involvement of a well-mixed multi-source reservoir of Pb at depth. The syn-diagenetic mineralization in the Bahloul Formation and the calculate of model age suggest a Late Cretaceous age, correspond to a NE-SW to ENE-WSS regional extensional tectonic events, which likely favored migration of mineralizing fluids and eventual deposition at Guarn Halfaya and Bou Grine.

  18. Lead isotope study of Zn-Pb ore deposits associated with the Basque-Cantabrian basin and Paleozoic basement, Northern Spain

    Velasco, F.; Pesquera, A.; Herrero, J. M.


    A total of forty-three galena samples from syngenetic and epigenetic Pb-Zn mineralizations emplaced in the Lower Cretaceous Basque-Cantabrian basin and Paleozoic basement of the Cinco Villas massif in the western Pyrenees, have been analyzed for Pb-isotopic composition. Galena from sedex mineralizations hosted in Carboniferous clastic rocks in the Cinco Villas massif display an homogeneous lead isotopic signature (206Pb/2044Pb ≈ 18.43, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.69) suggesting a single lead reservoir. These values are slightly more radiogenic than lead from other European Hercynian deposits, possibly reflecting the influence of a more evolved upper crustal source. Underlying Paleozoic sediments are proposed as lead source for the Cinco Villas massif ores. Analyses from twenty-six galena samples from the four strata-bound ore districts hosted in Mesozoic rocks reveal the existence of two populations regarding their lead isotopic composition. Galena from the western Santander districts (e.g., Reocin) is characterized by more radiogenic isotope values (206Pb/204Pb ≈ 18.74, 207Pb/204Pb ≈ 15.67, 208Pb/ 204Pb ≈ 38.73) than those from the central and eastern districts (Troya-Legorreta, Central and Western Vizcaya, 206Pb/204Pb ≈ 18.59, 207Pb/204Pb ≈ 15.66, 208Pb/ 204Pb ≈ 38.73). In all districts, the most likely source for these mineralizations was the thick sequence of Lower Cretaceous clastic sediments. The existence of two separate lead isotopic populations could be the result of regional difference in the composition of the basement rocks and the clastic sediments derived of it or different evolution histories. In both sub-basins, isotopic ratios indicate an increase in crustal influence as the age of the ores decreases.

  19. Geochronology, geochemistry, and Sr-Nd-Pb-Hf isotopes of the Zhunsujihua granitoid intrusions associated with the molybdenum deposit, northern Inner Mongolia, China: implications for petrogenesis and tectonic setting

    Zhang, Xiaojun; Lentz, David R.; Yao, Chunliang; Liu, Rui; Yang, Zhen; Mei, Yanxiong; Fan, Xianwang; Huang, Fei; Qin, Ying; Zhang, Kun; Zhang, Zhenfei


    The Zhunsujihua porphyry molybdenum deposit, located in northern Inner Mongolia of China that belongs to Central-Asian Orogenic Belt (CAOB), is the only Mo deposit formed in the late Carboniferous in this area so far. Its mineralization is mainly restricted to the Zhunsujihua granitoid intrusions, which are composed of the main granodiorite (GD) and crosscutting, virtually coeval minor syn-ore leucogranite (LG) and diorite porphyry (DP) dykes. LA-ICP-MS zircon U-Pb dating yields crystallization ages of 300.0 ± 2.0, 299.3 ± 2.0, and 299.0 ± 2.6 Ma for the GD, LG, and DP, respectively. The major and trace element lithogeochemical data show that the GD and LG are metaluminous to weakly peraluminous, high-K calc-alkaline series with I-type granite characteristics, strongly oxidized, with low concentrations of Ba, Nb, Sr, P, and Ti and elevated K and Rb contents, indicating typical arc magmatic features. The LG is a product derived by extensive fractional crystallization of a parental magma similar to the GD as evident from the lower Eu/Eu*, Nb/Ta, Zr/Hf, and T Zr. The moderately altered DP exhibits high concentrations of K, Rb, Cs, LREE, Y, and low Sr/Y, with a positive ɛ Nd (300 Ma), which indicates a mantle or juvenile source associated with an arc setting. The Sr-Nd-Hf isotope data show low I Sr (0.70406-0.70461) and moderate ɛ Nd (300 Ma) (-0.9 to 1.5) for the GD and LG, and relatively high ɛ Hf (300 Ma) values (-3.6 to +11.2) for the GD, suggesting the magma mainly originated from the juvenile lower crust that was derived from depleted mantle, with a minor component of ancient continental crust. Lead isotope data have characteristics of a lower crust source with minor contamination by upper crustal material. Combined with previous research, the Zhunsujihua granitoid intrusions developed in an intracontinental volcanic arc (Uliastai) associated with northward subduction of the Paleo-Asian Ocean plate during late Carboniferous to early Permian; this suggests

  20. 新疆喀拉通克铜镍矿地震资料噪声分析与压制%Analysis and suppression of seismic data noise in the Kalatongke copper-nickel deposit,northern Xinjiang

    张保卫; 王小江; 张凯


    金属矿地震勘探中原始数据的信噪比较低,多种干扰波混杂在地震记录中,严重影响了金属矿地震资料的成像质量。因此,选择有效的去噪方法是提高资料品质的关键。以新疆喀拉通克铜镍金属矿区地震资料处理为基础,在FOCUS5.4处理软件平台下采用多方法联合去噪技术压制单频波、声波、面波以及机械振动等干扰。通过模块测试和参数调试,找到适合该金属矿区的去噪方法技术。经过去噪处理,大幅提高了金属矿地震资料的信噪比。%The signal⁃to⁃noise ratio ( SNR) of raw data from seismic exploration in the metallic deposit is very low,and various sorts of interference waves are mixed in the record,which seriously influences the quality of image formation for mineral seismic data.Therefore, an effective method of de⁃noising is the key to improving data quality.Based on seismic⁃data processing of the Kalatongke copper⁃nickel deposit in northern Xinjiang,the authors adopted multi⁃method combinational de⁃noising of FOCUS5. 4 software to suppress mono⁃fre⁃quency noise,acoustic interference, surface wave and mechanical oscillating interference. Based on module experiment and parameter test,the authors found noise removal methods which are adapted to the contact mineral zone.This de⁃noising processing improves greatly SNR of mineral seismic data.

  1. Late Cryogenian-Ediacaran history of the Arabian-Nubian Shield: A review of depositional, plutonic, structural, and tectonic events in the closing stages of the northern East African Orogen

    Johnson, P. R.; Andresen, A.; Collins, A. S.; Fowler, A. R.; Fritz, H.; Ghebreab, W.; Kusky, T.; Stern, R. J.


    During the late Cryogenian-Ediacaran (650-542 Ma), the Arabian-Nubian Shield (ANS) underwent final assembly and accretion to the Saharan Metacraton concurrent with the assembly of eastern and western Gondwana. At the end of the Precambrian it lay at one end of the East African Orogen, with its northern margin (present coordinates) forming a low-relief stable shelf facing an open ocean; to the south the ANS transitioned into the Mozambique Belt. The geologic history of the ANS during this period provides insight into the closing developmental stages of one of the world's largest accretionary orogens. Following a 680-640 Ma orogenic event reflecting amalgamation of a core grouping of island-arc terranes (the proto-Arabian-Nubian Shield; pANS), the region underwent extensive exhumation, erosion, and subsidence. Depositional basins formed in the northern and eastern pANS, with those in the east below sea level and connected to an ocean. Periodic basin closure and formation of new basins in other parts of the ANS followed. Many basins were filled by terrestrial, molasse-type sediments interfingering with subordinate to predominant amounts of volcanic rocks. Magmatism was extensive throughout the period, initially characterized by tonalite-trondhjemite-granodiorite (TTG) and granite (monzogranite, syenogranite), but also characterized, from ˜610 Ma on, by increasing amounts of alkali-feldspar granite and alkali granite. The plutons are largely undeformed, except where cut by brittle-ductile shear zones. The magma sources of the late Cryogenian-Ediacaran granitoids were dominated by juvenile crust and(or) depleted mantle and magmas mostly originated in anorogenic, post-collisional, commonly extensional, settings. They were derived by melting and fractionation of anhydrous high-grade metamorphosed lower crust, mafic- to intermediate calc-alkaline crust, and(or) subduction-modified mantle wedges associated with slab break-off or delamination. By ˜630 Ma, the region was


    inertia, water balance, physiological strength, and susceptibility to predation between adults .... Judd PW and Rose FL 1977 Aspects of the thermal biology of the Texas tortoise ... pctrdolis lmheoeki) and their conservation in northern Tanzania.

  3. Geochronology Research and Its Significance for Mo-W Polymetallic Deposit of Dabao Mountain in Northern Guangdong province%粤北大宝山钼钨多金属矿床年代学研究及其意义

    杜国民; 梅玉萍; 蔡红; 罗俊华


    Through the precise dating measuring of the pyrite and quartz minerals in different types of Mo-W polymetallic deposits in Dabao mountain, northern Guangdong province with Rb-Sr isochron method, the age of the pyrite in laminated ores is yielded 168±5Ma (95% reliability), the age of quartz minerals in quartz-molybdenite veins is yielded 164±3 Ma (95% reliability), and the age of quartz minerals in pyrite- quartz lodes is yielded 162±4 Ma (95% reliability) respectively. The results showed that the Cu-Pb-Zn ores and the Mo-W minerals of Dabao polymetallic deposit were formed at 168 - 162 Ma. The results also agreed with former studies that the pyrrhotite minerals formation time was between 165±1 Ma by Re-Os dating method. In consideration of the obviously coupled relationships of the formation time and space between the Cu-Pb-Zn and Mo-W minerals and the secondary dacite and granodiorite porphyry, it showed that the min- eralization of the deposit was related to the early magmatic activities of Yanshan movement in these areas.%本文对大宝山钼钨多金属矿床中不同类型矿石中黄铁矿及石英矿物用Rb-Sr等时线法进行了精细测定,分别获得层纹状矿石中黄铁矿的年龄为168±5Ma(95%可信度),辉钼矿石英脉中石英矿物年龄为164+3Ma(95%可信度)和黄铁矿石英脉中石英矿物年龄为162±4Ma(95%可信度),测定结果表明,大宝山铝钨多金属矿床铜铅锌和钼钨成矿阶段形成的时间在168~162Ma之间。本研究所获得的结果也与前人所获得的层状铜铅锌矿石和脉状矿石中辉钼矿的Re-Os模式年龄为165+1Ma一致。鉴于铜铅锌和钼钨矿床在形成时间和空间上与次英安斑岩和花岗闪长斑岩具有明显的耦合关系,据此表明,其成矿作用主要与区内燕山早期岩浆活动有关。

  4. U-Pb, Re-Os, and 40Ar/39Ar geochronology of the Nambija Au-skarn and Pangui porphyry Cu deposits, Ecuador: implications for the Jurassic metallogenic belt of the Northern Andes

    Chiaradia, Massimo; Vallance, Jean; Fontboté, Lluis; Stein, Holly; Schaltegger, Urs; Coder, Joshua; Richards, Jeremy; Villeneuve, Mike; Gendall, Ian


    New U-Pb, Re-Os, and 40Ar/39Ar dates are presented for magmatic and hydrothermal mineral phases in skarn- and porphyry-related ores from the Nambija and Pangui districts of the Subandean zone, southeastern Ecuador. Nambija has been one of the main gold-producing centers of Ecuador since the 1980s due to exceptionally high-grade ores (average 15 g/t, but frequently up to 300 g/t Au). Pangui is a recently discovered porphyry Cu-Mo district. The geology of the Subandean zone in southeastern Ecuador is dominated by the I-type, subduction-related, Jurassic Zamora batholith, which intrudes Triassic volcanosedimentary rocks. The Zamora batholith is in turn cut by porphyritic stocks, which are commonly associated with skarn formation and/or porphyry-style mineralization. High precision U-Pb and Re-Os ages for porphyritic stocks (U-Pb, zircon), associated prograde skarn (U-Pb, hydrothermal titanite), and retrograde stage skarn (Re-Os, molybdenite from veins postdating gold deposition) of the Nambija district are all indistinguishable from each other within error (145 Ma) and indicate a Late Jurassic age for the gold mineralization. Previously, gold mineralization at Nambija was considered to be Early Tertiary based on K-Ar ages obtained on various hydrothermal minerals. The new Jurassic age for the Nambija district is slightly younger than the 40Ar/39Ar and Re-Os ages for magmatic-hydrothermal minerals from the Pangui district, which range between 157 and 152 Ma. Mineralization at Nambija and Pangui is associated with porphyritic stocks that represent the last known episodes of a long-lived Jurassic arc magmatism (˜190 to 145 Ma). A Jurassic age for mineralization at Nambija and Pangui suggests that the Northern Andean Jurassic metallogenic belt, which starts in Colombia at 3° N, extends down to 5° S in Ecuador. It also adds a new mineralization style (Au-skarn) to the metal endowment of this belt.

  5. The Paleozoic tectonic evolution and metallogenesis of the northern margin of East Junggar, Central Asia Orogenic Belt: Geochronological and geochemical constraints from igneous rocks of the Qiaoxiahala Fe-Cu deposit

    Liang, Pei; Chen, Huayong; Hollings, Pete; Xiao, Bing; Wu, Chao; Bao, Zhiwei; Cai, Keda


    The East Junggar terrane (NW China) is an important constituent of the Central Asian Orogenic Belt (CAOB). From the Devonian to Permian, regional magmatism evolved from mainly calc-alkaline (I-type) to alkaline (A-type). The Qiaoxiahala Fe-Cu deposit, located in the Late Paleozoic Dulate island arc (northern margin of the East Junggar), is hosted in the volcanic rocks of the Middle Devonian Beitashan Formation. Two magmatic stages were identified in the deposit, the Qiaoxiahala diorite porphyry (380 ± 4.0 Ma) and a younger aplite (331 ± 3.1 Ma). The (high-K) calc-alkaline Beitashan Formation basaltic rocks are characterized by LILE and LREE enrichments and HFSE depletions, pointing to a subduction-related affinity. The high Mg# (42-75), elevated Ce/Th and Ba/Th, depleted Nb, positive εNd(t) (6.6), low (87Sr/86Sr)i (0.7037) and MORB-like Pb isotope characters all suggest an origin involving partial melting of a MORB-like depleted mantle wedge (metasomatized by slab-derived fluids) with little evidence of crustal contamination. The calc-alkaline (I-type) diorite porphyry, characterized by LILE and LREE enrichments and HFSE depletions, may have formed from fractional crystallization of the basaltic rocks, with its parental magma derived from the same depleted mantle wedge. The negative εHf(t) (-8.26), Hf model age (TDMC) of 1406 Ma and the presence of inherited zircons (ca. 470 and 506 Ma) indicate that the diorite has assimilated older crustal material. The alkaline, metaluminous (A-type) aplite is characterized by HFSE enrichment and depletions in Sr, P and Ti, distinct from the basaltic rocks and diorite porphyry at Qiaoxiahala. The low Mg# (35-38), positive Zr and Hf, positive εHf(t) (4.77-9.75) and εNd(t) (6.85-6.86) and low T2DM (538-520 Ma) suggest a juvenile lower crustal source due to partial melting of basaltic lower crust as a result of underplating of mantle-derived melts and accompanied by magma mixing. The tectonic evolution of the Paleozoic East

  6. The world-class Howard's Pass SEDEX Zn-Pb district, Selwyn Basin, Yukon. Part I: trace element compositions of pyrite record input of hydrothermal, diagenetic, and metamorphic fluids to mineralization

    Gadd, Michael G.; Layton-Matthews, Daniel; Peter, Jan M.; Paradis, Suzanne J.


    The Howard's Pass district, located in Yukon Territory, comprises 14 Zn-Pb sedimentary exhalative (SEDEX) deposits that collectively contain approximately 400.7 Mt grading at 4.5 % Zn and 1.5 % Pb. Sulfide mineralization is hosted in carbonaceous and calcareous to siliceous mudstones. Pyrite is a minor but ubiquitous component. Detailed petrographic analyses reveal that pyrite has a complex and protracted growth history, and multiple generations of pyrite are preserved in single grains. Combined electron probe microanalysis (EPMA) and laser ablation-inductively coupled mass plasma-mass spectrometry (LA-ICP-MS) of paragenetically complex pyrite reveal minor and trace element zonation that mimic textural features. These data provide information on the relative timing and cation content of depositional (i.e., ambient marine), hydrothermal, and metamorphic fluids. These data also identify a suite of nonore elements (Mn, As, Ag, Sb, and Tl) associated with the Zn-Pb mineralizing hydrothermal fluids. Lithogeochemical data and statistical results corroborate the microanalytical findings. These elements are associated with both syngenetic to earliest diagenetic pyrite and later diagenetic pyrite overgrowths, suggesting that SEDEX mineralization was not only the product of hydrothermal precipitates that settled on the seafloor, but also dense metalliferous brine also settled on, and percolated through, unconsolidated carbonaceous muds and precipitated metals. This genetic model is similar to that proposed for the Paleoproterozoic HYC Zn-Pb-Ag SEDEX deposit in northern Australia, and it is likely that common processes and ambient conditions led to the formation and preservation of both of these large SEDEX districts.

  7. Long-Term Simulated Atmospheric Nitrogen Deposition Alters Leaf and Fine Root Decomposition

    Atmospheric nitrogen deposition has been suggested to increase forest carbon sequestration across much of the Northern Hemisphere; slower organic matter decomposition could contribute to this increase. At four sugar maple (Acer saccharum)-dominated northern hardwood forests, we p...



    <正>20102406 Chen Gang(China University of Geosciences,Beijing 100083,China);Li Fengming Discussion on Geological Characteristics and Genesis of Yuquanshan Graphite Deposit of Xinjiang(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,27(4),2009,p.325-329,4 illus.,4 tables,5 refs.)Key words:graphite deposit,XinjiangYuquanshan graphite deposit of Xinjiang occurs in mica-quartz schist of Xingeer Information which belongs to Xinditate Group of Lower Pt in Kuluketage Block of Tarim paleo-continent,and experiences two mineralizing periods of

  9. Stability of fine-grained TT-OSL and post-IR IRSL signals from a i>c.> 1 Ma sequence of aeolian and lacustrine deposits from the Nihewan Basin (northern China)

    Liu, Jinfeng; Murray, Andrew Sean; Buylaert, Jan-Pieter;


    We tested the suitability of the fine-grained quartz (4–11 μm) Optical Stimulated Luminescence (OSL) and thermally-transferred OSL (TT-OSL), and the fine-grained polymineral (4–11 μm) post-infrared IRSL (post-IR IRSL or pIRIR) signals for dating samples from aeolian-lacustrine deposits from the X...

  10. High-resolution bathymetry as a primary exploration tool for seafloor massive sulfide deposits - lessons learned from exploration on the Mid-Atlantic and Juan de Fuca Ridges, and northern Lau Basin

    Jamieson, J. W.; Clague, D. A.; Petersen, S.; Yeo, I. A.; Escartin, J.; Kwasnitschka, T.


    High-resolution, autonomous underwater vehicle (AUV)-derived multibeam bathymetry is increasingly being used as an exploration tool for delineating the size and extent of hydrothermal vent fields and associated seafloor massive sulfide deposits. However, because of the limited amount of seafloor that can be surveyed during a single dive, and the challenges associated with distinguishing hydrothermal chimneys and mounds from other volcanic and tectonic features using solely bathymetric data, AUV mapping surveys have largely been employed as a secondary exploration tool once hydrothermal sites have been discovered using other exploration methods such as plume, self-potential and TV surveys, or ROV and submersible dives. Visual ground-truthing is often required to attain an acceptable level of confidence in the hydrothermal origin of features identified in AUV-derived bathymetry. Here, we present examples of high-resolution bathymetric surveys of vent fields from a variety of tectonic environments, including slow- and intermediate-rate mid-ocean ridges, oceanic core complexes and back arc basins. Results illustrate the diversity of sulfide deposit morphologies, and the challenges associated with identifying hydrothermal features in different tectonic environments. We present a developing set of criteria that can be used to distinguish hydrothermal deposits in bathymetric data, and how AUV surveys can be used either on their own or in conjunction with other exploration techniques as a primary exploration tool.

  11. Tectonostratigraphy and depositional history of the Neoproterozoic volcano-sedimentary sequences in Kid area, southeastern Sinai, Egypt: Implications for intra-arc to foreland basin in the northern Arabian-Nubian Shield

    Khalaf, E. A.; Obeid, M. A.


    This paper presents a stratigraphic and sedimentary study of Neoproterozoic successions of the South Sinai, at the northernmost segment of the Arabian-Nubian Shield (ANS), including the Kid complex. This complex is composed predominantly of thick volcano-sedimentary successions representing different depositional and tectonic environments, followed by four deformational phases including folding and brittle faults (D1-D4). The whole Kid area is divisible from north to south into the lower, middle, and upper rock sequences. The higher metamorphic grade and extensive deformational styles of the lower sequence distinguishes them from the middle and upper sequences. Principal lithofacies in the lower sequence include thrust-imbricated tectonic slice of metasediments and metavolcanics, whereas the middle and upper sequences are made up of clastic sediments, intermediate-felsic lavas, volcaniclastics, and dike swarms. Two distinct Paleo- depositional environments are observed: deep-marine and alluvial fan regime. The former occurred mainly during the lower sequence, whereas the latter developed during the other two sequences. These alternations of depositional conditions in the volcano-sedimentary deposits suggest that the Kid area may have formed under a transitional climate regime fluctuating gradually from warm and dry to warm and humid conditions. Geochemical and petrographical data, in conjunction with field relationships, suggest that the investigated volcano-sedimentary rocks were built from detritus derived from a wide range of sources, ranging from Paleoproterozoic to Neoproterozoic continental crust. Deposition within the ancient Kid basin reflects a complete basin cycle from rifting and passive margin development, to intra-arc and foreland basin development and, finally, basin closure. The early phase of basin evolution is similar to various basins in the Taupo volcanics, whereas the later phases are similar to the Cordilleran-type foreland basin. The



    <正>20140876 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550025,China);Yang Ruidong Study on the Strontium Isotopic Composition of Large Devonian Barite Deposits from Zhenning,Guizhou Province(Geochimica,



    <正>20122457 Cai Jianshe ( Fujian Institute of Geological Survey and Drawing,Fuzhou 350011,China ) On the Geologic Characteristics and Genesis of the Longtangsi Fluorite Deposit in Pucheng County,Fujian Province ( Geology of Fujian,ISSN1001-3970,CN35-1080 / P,30 ( 4 ), 2011,p.301-306,3illus.,1table,6 refs.,with English abstract ) Key words:fluorspar deposit,Fujian Province

  14. Geological Characteristics and Prospecting Potential of the Copper and Zinc Ore Deposits in the Sinian and Cambrian Systems of the Northern Daba Shan%北大巴山震旦寒武系中铜锌矿特征及找矿前景

    龚银杰; 邹先武; 崔森; 夏杰; 张遵遵; 刘小龙; 刘劲松


    北大巴山属南秦岭造山带,在震旦-寒武纪形成一套以深水滞流盆地相为主的硅质炭质碎屑岩夹碳酸盐岩沉积.自开展地质大调查工作以来,该区域发现大量的铜锌矿点.根据矿体赋存位置、成因及矿石类型,铜锌矿可分为韧性剪切带型、石英脉型及岩浆岩接触变质型三种类型.通过对区内铜锌矿成矿规律的总结及成矿条件的分析,认为北大巴山具有良好的矿源层、完善的输导系统、丰富的储矿空间,因而具有较大的找矿潜力.指出深大断裂带附近的庄子沟组中碳酸盐岩为有利的赋矿部位.%The northern Daba Shan is part of the South Qinling orogenic belt, where deposited a set of siliceous - carbonaceous clastic rocks interbed-ded with carbonate sediments dominated by deep stagnant basin facies formed in the Sinian - Cambrian epoch. Previous exploration has discovered a large number of copper and zinc mineral occurrences or ore deposits, which are classified into the ductile shear zone type, quartz vein type and magmatic rocks contact metamorphic type according to the occurrence location, genesis of ore - bodies and types of the ores. Studies on the metallogenic conditions and regularities of these copper and zinc ore deposits suggest that the northern Daba Shan owns good source beds,perfect transporting and conducting systems and rich ore - storage space,indicating its large prospecting potential. It is pointed out that the of Zhuangzigou Fm. carbonate rocks adjacent to the deep and large faults are favorable ore - bearing loci.



    <正>20110947 Chen Xinglong(Guizhou Bureau of Nonferrous Metal and Nuclear Geology,Guiyang 550005,China);Gong Heqiang Endowment Factors and Development & Utilization Strategy of Bauxite Resource in North Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(2),2010,p.106-110,6 refs.,with English abstract)Key words:bauxite deposit,Guizhou Province20110948 Dang Yanxia(Mineral Resource & Reservoir Evaluation Center,Urumiq 830000,China);Fan Wenjun Geological Features and a Primary Study of Metallogenesis of the Wucaiwang Zeolite Deposit,Fuyun County(Xinjiang Geology,ISSN1000-8845,CN65-1092/P,28(2),2010,p.167-170,2 illus.,1 table,5 refs.)Key words:zeolite deposit,Xinjiang Nearly all zeolite deposits in the world result from low-temperature-alteration of glass-bearing volcanic rocks.The southern slope of the Kalamali Mountain is one of the regions where medium to acid volcanics are major lithological type,thus it is a preferred area to look for zeolite deposit.The Wucaiwang zeolite ore district consists of mainly acid volcanic-clastic rocks.



    <正>20091594 Bao Yafan(The Third Geologic Survey of Jilin Province,Siping 136000,China);Liu Yanjun Relations between Bashenerxi Granite,West Dongkunlun and Baiganhu Tungsten-Tin Deposit(Jilin Geology,ISSN1001-2427,CN22-1099/P,27(3),2008,p.56-59,67,5 illus.,2 tables,7 refs.,with English abstract)Key words:tungsten ores,tin ores,monzogranite,Kunlun Mountains20091595 Chen Fuwen(Yichang Institute of Geology and Mineral Resources,China Geological Survey,Yichang 443003,China);Dai Pingyun Metallogenetic and Isotopic Chronological Study on the Shenjiaya Gold Deposit in Xuefeng Mountains,Hunan Province(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,82(7),2008,p.906-911,3 illus.,2 tables,30 refs.)Key words:gold ores,HunanThe Shenjiaya gold deposit is a representative one

  17. A 20-year simulated climatology of global dust aerosol deposition.

    Zheng, Yu; Zhao, Tianliang; Che, Huizheng; Liu, Yu; Han, Yongxiang; Liu, Chong; Xiong, Jie; Liu, Jianhui; Zhou, Yike


    Based on a 20-year (1991-2010) simulation of dust aerosol deposition with the global climate model CAM5.1 (Community Atmosphere Model, version 5.1), the spatial and temporal variations of dust aerosol deposition were analyzed using climate statistical methods. The results indicated that the annual amount of global dust aerosol deposition was approximately 1161±31Mt, with a decreasing trend, and its interannual variation range of 2.70% over 1991-2010. The 20-year average ratio of global dust dry to wet depositions was 1.12, with interannual variation of 2.24%, showing the quantity of dry deposition of dust aerosol was greater than dust wet deposition. High dry deposition was centered over continental deserts and surrounding regions, while wet deposition was a dominant deposition process over the North Atlantic, North Pacific and northern Indian Ocean. Furthermore, both dry and wet deposition presented a zonal distribution. To examine the regional changes of dust aerosol deposition on land and sea areas, we chose the North Atlantic, Eurasia, northern Indian Ocean, North Pacific and Australia to analyze the interannual and seasonal variations of dust deposition and dry-to-wet deposition ratio. The deposition amounts of each region showed interannual fluctuations with the largest variation range at around 26.96% in the northern Indian Ocean area, followed by the North Pacific (16.47%), Australia (9.76%), North Atlantic (9.43%) and Eurasia (6.03%). The northern Indian Ocean also had the greatest amplitude of interannual variation in dry-to-wet deposition ratio, at 22.41%, followed by the North Atlantic (9.69%), Australia (6.82%), North Pacific (6.31%) and Eurasia (4.36%). Dust aerosol presented a seasonal cycle, with typically strong deposition in spring and summer and weak deposition in autumn and winter. The dust deposition over the northern Indian Ocean exhibited the greatest seasonal change range at about 118.00%, while the North Atlantic showed the lowest seasonal



    <正>20111705 An Junbo(Team 603,Bureau of Nonferrous Metals Geological Exploration of Jilin Province,Hunchun 133300,China);Xu Renjie Geological Features and Ore Genesis of Baishilazi Scheelite Deposit in Yanbian Area(Jilin Geology,ISSN1001-2427,CN22-1099/P,29(3),2010,p.39-43,2 illus.,2 tables,7 refs.)Key words:tungsten ores,Jilin ProvinceThe Baishilazi scheelite deposit is located in contacting zone between the marble of the Late Palaeozoic Qinglongcun Group and the Hercynian biotite granite.The vein and lenticular major ore body is obviously controlled by NE-extending faults and con

  19. Miospores from the Frasnian-Famennian Boundary deposits in Eastern Europe (the Pripyat Depression, Belarus and the Timan-Pechora Province, Russia) and comparison with Western Europe (Northern France).

    Obukhovskaya; Avkhimovitch; Streel; Loboziak


    A zonal subdivision of the Frasnian-Famennian transitional deposits in the Pripyat Depression and Timan-Pechora Province, based on a detailed palynological study, has been completed. The data obtained on miospores and conodonts from the Timan-Pechora Province enable a correlation to be made with the Standard Conodont Zonation. The lateral extent of the palynozones in Eastern Europe and the correlation with Western Europe are discussed. The following previously published new combinations are validated: Auroraspora speciosa (Naumova) Obukhovskaya, comb. nov., Corbulispora viminea (Nekriata) Obukhovskaya and Nekriata, comb. nov., Cristatisporites imperpetuus (Sennova) Obukhovskaya, comb. nov., Cymbosporites acanthaceus (Kedo) Obukhovskaya, comb. nov., Grandispora subsuta (Nazarenko) Obukhovskaya, comb. nov., and Verrucosisporites evlanensis (Naumova) Obukhovskaya, comb. nov.



    <正>20131565 Cai Lianyou(No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China);Weng Wangfei Geological Characteristics and Genesis Analysis of Guocun Navajoite Deposit in South Anhui Province(Mineral Resources and Geology,



    <正>20102341 Bao Peisheng(Institute of Geology,Chinese Academy of Geological Science,Beijing 100037,China)Further Discussion on the Genesis of the Podiform Chromite Deposits in the Ophiolites-Questioning about the Rock:Melt Interaction Metallogeny(Geological Bulletin of China,ISSN1671-2552,CN11-4648/P,28(12),2009,p.1741-1761



    <正>20131601 Gao Junbo(College of Resources and Environmental Engineering,Guizhou University,Guiyang 550003,China);Yang Ruidong Hydrothermal Venting-Flowing Sedimentation Characteristics of Devonian Barite Deposits from Leji,Zhenning County,Guizhou Province(Acta Sedimentologica Sinica,ISSN1000-0550,CN62-1038/P,30(3),

  3. Tectonic setting and metallogenesis of volcanogenic massive sulfide deposits in the Bonnifield Mining District, Northern Alaska Range: Chapter B in Recent U.S. Geological Survey studies in the Tintina Gold Province, Alaska, United States, and Yukon, Canada--results of a 5-year project

    Dusel-Bacon, Cynthia; Aleinikoff, John N.; Premo, Wayne R.; Paradis, Suzanne; Lohr-Schmidt, Ilana; Gough, Larry P.; Day, Warren C.


    This paper summarizes the results of field and laboratory investigations, including whole-rock geochemistry and radiogenic isotopes, of outcrop and drill core samples from volcanogenic massive sulfide (VMS) deposits and associated metaigneous rocks in the Wood River area of the Bonnifield mining district, northern Alaska Range (see fig. 1 of Editors’ Preface and Overview). U-Pb zircon igneous crystallization ages from felsic rocks indicate a prolonged period of Late Devonian to Early Mississippian (373±3 to 357±4 million years before present, or Ma) magmatism. This magmatism occurred in a basinal setting along the ancient Pacific margin of North America. The siliceous and carbonaceous compositions of metasedimentary rocks, Precambrian model ages based on U-Pb dating of zircon and neodymium ages, and for some units, radiogenic neodymium isotopic compositions and whole-rock trace-element ratios similar to those of continental crust are evidence for this setting. Red Mountain (also known as Dry Creek) and WTF, two of the largest VMS deposits, are hosted in peralkaline metarhyolite of the Mystic Creek Member of the Totatlanika Schist. The Mystic Creek Member is distinctive in having high concentrations of high-field-strength elements (HFSE) and rare-earth elements (REE), indicative of formation in a within-plate (extensional) setting. Mystic Creek metarhyolite is associated with alkalic, within-plate basalt of the Chute Creek Member; neodymium isotopic data indicate an enriched mantle component for both members of this bimodal (rhyolite-basalt) suite. Anderson Mountain, the other significant VMS deposit, is hosted by the Wood River assemblage. Metaigneous rocks in the Wood River assemblage span a wide compositional range, including andesitic rocks, which are characteristic of arc volcanism. Our data suggest that the Mystic Creek Member likely formed in an extensional, back-arc basin that was associated with an outboard continental-margin volcanic arc that included

  4. River response to climate and sea level changes during the Late Saalian/Early Eemian in northern Poland – a case study of meandering river deposits in the Chłapowo cliff section

    Moskalewicz Damian


    Full Text Available Fluvial sediments in the Chłapowo cliff section were studied in order to reconstruct their palaeoflow conditions and stratigraphical position. Lithofacies, textural and palaeohydraulic analyses as well as luminescence dating were performed so as to achieve the aim of study. Sedimentary successions were identified as a record of point bar cycles. The fluvial environment probably functioned during the latest Saalian, shortly after the retreat of the Scandinavian Ice Sheet. Discharge outflow was directed to the northwest. The river used the older fluvioglacial valley and probably was directly connected to the Eem Sea. Good preservation and strong aggradation of point-bar cycles were related to a rapid relative base level rise. The meandering river sediments recognised showed responses to climate and sea level changes as illustrated by stratigraphical, morphological and sedimentological features of the strata described. The present study also revealed several insights into proper interpretation of meandering fluvial successions, in which the most important were: specific lithofacies assemblage of GSt (St, Sp → Sl → SFrc → Fm (SFr and related architectural elements: channel/sandy bedforms CH/SB → lateral accretion deposits LA → floodplain fines with crevasse splays FF (CS; upward-fining grain size and decreasing content of denser heavy minerals; estimated low-energy flow regime with a mean depth of 1.6–3.3 m, a Froude number of 0.2–0.4 and a sinuosity of 1.5.

  5. Early millet use in northern China

    Yang, Xiaoyan; Wan, Zhiwei; Perry, Linda; Lu, Houyuan; WANG Qiang; Zhao, Chaohong; Li, Jun; Xie, Fei; Yu, Jincheng; Cui, Tianxing; WANG Tao; Li, Mingqi; Ge, Quansheng


    It is generally understood that foxtail millet and broomcorn millet were initially domesticated in Northern China where they eventually became the dominant plant food crops. The rarity of older archaeological sites and archaeobotanical work in the region, however, renders both the origins of these plants and their processes of domestication poorly understood. Here we present ancient starch grain assemblages recovered from cultural deposits, including carbonized residues adhering to an early p...

  6. Atmospheric nitrogen deposition in world biodiversity hotspots: the need for a greater global perspective in assessing N deposition impacts

    Phoenix, G.K.; Hicks, W.K.; Cinderby, S.; Kuylenstierna, J.C.I.; Stock, W.D.; Dentener, F.J.; Giller, K.E.; Austin, A.T.; Lefroy, R.D.B.; Gimeno, B.S.; Ashmore, M.R.; Ineson, P.


    Increased atmospheric nitrogen (N) deposition is known to reduce plant diversity in natural and semi-natural ecosystems, yet our understanding of these impacts comes almost entirely from studies in northern Europe and North America. Currently, we lack an understanding of the threat of N deposition t

  7. 苏北废黄河三角洲岸线变迁与海岸冲淤动态遥感监测%Remote Sensing Based Dynamic Monitoring of Coastline Change and Coastal Erosion and Deposition of the Abandoned Yellow River Delta in Northern Area of Jiangsu Province

    王志一; 徐素宁; 姜艳辉; 梅军军; 吕铁硬


      近几十年来,我国的砂质、淤泥质海岸正呈现侵蚀加剧的演变趋向。随着卫星遥感数据在光谱、时间和空间分辨率方面的不断提高,海岸侵蚀和淤积监测具备了精度越来越高的数据源。在前人研究的基础上,以废黄河三角洲海岸为研究对象,利用遥感技术和野外实地调查对海岸岸线变迁及冲淤动态进行了研究。研究表明:遥感技术在岸线变迁、侵蚀淤积监测和预测方面具有其他技术无可比拟的优势,在海岸带地质环境监测中的应用已成为具有实用价值的技术。%The sandy and silty coast in China has shown an increasing trend of erosion in recent years. The improvement of spec2 tral, temporal, and spatial resolut ion of the satellite remote sensing data has provided the high2accuracy remote sensing data sources for the monitoring of the coastal erosion and deposition. Base on t he previous studies, the remot e sensing technique and filed survey were used to investigate t he coastline change and coastal erosion and deposition of the abandoned Yel ow River Del2 ta in the northern area of Jiangsu province. The results showed that t he remote sensing technique has the unparal eled advanta2 ges for monitoring and predict ing the coastline changes and coastal erosion and deposition compared w ith other technologies, and it has pract ical significance for monit oring the coastal geological environment .



    <正>20122389 Cai Lianyou ( No.332 Geological Team,Bureau of Geology and Mineral Resources Exploration of Anhui Province,Huangshan 245000,China );Weng Wangfei Geologic Characteristic and Ore-Control Factors of the Nanshan W-Mo Polymetallic Ore Deposit in South Anhui Province ( Geological Survey and Research,ISSN1672-4135,CN12-1353 / P,34 ( 4 ), 2011,p.290-298,3 illus.,1table,14refs. ) Key words:tungsten ores,molybdenum ores,ore guide of prospecting,Anhui Province



    <正>20110165 Chen Jiawei(The 3rd Geological Team,Henan Bureau of Geology and Mineral Resources,Xinyang 464000,China)Ore Control Conditions and Genetic Model for the Bodaoling Ag-Au Deposit in Guangshan,Henan Province(Acta Geologica Sichuan,ISSN1006-0995,CN51-1273/P,30(1),2010,p.28-30,5 illus.,1 ref.,with English abstract)Key words:gold ores,Henan Province20110166 Chen Mingquan(Geological Team 306,Yunnan Bureau of Nonferrous Geology,Kunming 650216,Ch

  10. Characteristics of Alteration and Mineralization in the Sharang Pophyry Molybdenum Deposit in the Northern Margin of Gangdese and Comparison with Typical Porphyry Molybdenum Deposits in the World%冈底斯北缘沙让斑岩钼矿蚀变矿化特征及与典型斑岩钼矿床的对比

    赵俊兴; 秦克章; 李光明; 李金祥


    The large-scale Sharang porphyry molybdenum deposit, as the firstly discovered single molybdenum porphyry-type deposit in the Cangdese metallogenic belt, formed in the main-stage of India-Asia continental collision with distinct characteristics of alteration and mineralization. The alteration types include potassic-silicate alteration ( K-feldspathization and biotitization), chlorite-epidote alteration, silicification, phyllic alteration (quartz-seri-cite-pyrite alteration) and argillic alteration (mainly Kaolinitization and illite - hydromuscovitization, always overlapping the silicic zone and phyllic zone). The main characteristics of mineralization, most founded in the ore district, are molybdenite-bearing vein, stockwork quartz+molybdenite±sulfide (other gangue minerals) vein, and ribbon-textured quartz+molybdenite±pyrite vein. Less disseminated mineralization, pure molybdenite veinlets and spotted mineralized matrix in the magmatic-hydrothermal breccias are observed in the Sharang area. As the phyllic zone and argillic zone are both main alteration types in the field study of Sharang, low erosion level of this porphyry deposit suggests great potential for the exploration. Additionally, several world-wide, typical porphyry molybdenum deposits are selected for the comparison and discussion of their characteristics of alteration and mineralization in this paper. It is concluded that both of potassic-silicate alteration and phyllic alteration have the major tight connection with mineralization in the most porphyry molybdenum deposits, and some alteration zones consist of fluorine-bearing minerals, such as the topaz zone in Henderson and fluorite-bearing zone in Donggou. The comparisons also indicate that the geometries of orebodies in most porphyry molybdenum deposits have been found as layers of coating ore -shell (or called inverted-cup) in the top of ore-forming intrusion. Among the orebodies, the main patterns of mineralization are stockwork and ribbon

  11. Fertilization of Northern Hardwoods

    R. Lea; D.G. Brockway


    Northern hardwoods grow over a considerable range of climatic and edaphic conditions and exhibit a wide range in productivity.Many northern hardwood forests are capable of high production relative to other forest types, but are often slow to reach maximum productivity because of low nutrient availability.Altering the patterns of biomass accumulation so that managers...



    <正>20111761 Chen Hua(115 Geological Party,Guizhou Bureau of Geology and Mineral Exploration & Development,Guiyang 551400,China);Deng Chao Analysis on the Metallogenic Environment of Maochang Bauxite in Guizhou Province(Guizhou Geology,ISSN1000-5943,CN52-1059/P,27(3),2010,p.198-201,2 illus.,1 table,8 refs.)Key words:bauxite deposit,Guizhou Province By long time physical and chemical process,the carbonate rock after Central Guizhou uplidft,becomes red clay,after further weathering,the red clay decomposed into the oxide,hydroxide of Al and Fe,in the dissolution hole and depression,it concentrates primary fragmentary tight and earthy karst bauxite ore.Because the variation of landform,it decomposes and cracks again,affords the material source

  13. Northern Dimension: Participant Strategies

    Busygina Irina


    Full Text Available This article is devoted to the “Northern Dimension” initiative of the EU which also includes North-West Russia, Norway and Iceland. It is noted that the “Northern Dimension” in the theoretical perspective can be considered as part of strategic multi-level interactions between member-states of the EU and Russia. On this basis, the authors analyze implications and effects of the strategic interdependence of all the EU-Russia relation levels.

  14. Lithogenic fluxes to the northern Indian Ocean - An overview

    Ramaswamy, V.

    Lithogenic fluxes to the northern Indian Ocean, measurEd. by time-series sediment traps, exhibit a strong seasonality with the bulk of the material (40 to 80 %) being deposited during the southwest monsoon period. This seasonality is more pronounced...

  15. Deposit model for volcanogenic uranium deposits

    Breit, George N.; Hall, Susan M.


    Volcanism is a major contributor to the formation of important uranium deposits both close to centers of eruption and more distal as a result of deposition of ash with leachable uranium. Hydrothermal fluids that are driven by magmatic heat proximal to some volcanic centers directly form some deposits. These fluids leach uranium from U-bearing silicic volcanic rocks and concentrate it at sites of deposition within veins, stockworks, breccias, volcaniclastic rocks, and lacustrine caldera sediments. The volcanogenic uranium deposit model presented here summarizes attributes of those deposits and follows the focus of the International Atomic Energy Agency caldera-hosted uranium deposit model. Although inferred by some to have a volcanic component to their origin, iron oxide-copper-gold deposits with economically recoverable uranium contents are not considered in this model.

  16. insurgents in Northern Uganda

    and the rebel movements in northern Uganda, see Human Rights Watch 2003, and ... of Uganda enacted an Amnesty Act in 2000, and to date more than ten thousand ..... Amnesty Certificate, and then in theory, a package.20 In the case of former .... [H]uman rights obligations are contracted on an international level.

  17. Northern blotting analysis

    Josefsen, Knud; Nielsen, Henrik


    Northern blotting analysis is a classical method for analysis of the size and steady-state level of a specific RNA in a complex sample. In short, the RNA is size-fractionated by gel electrophoresis and transferred by blotting onto a membrane to which the RNA is covalently bound. Then, the membran...

  18. Northern blotting analysis

    Josefsen, Knud; Nielsen, Henrik


    is analysed by hybridization to one or more specific probes that are labelled for subsequent detection. Northern blotting is relatively simple to perform, inexpensive, and not plagued by artefacts. Recent developments of hybridization membranes and buffers have resulted in increased sensitivity closing...

  19. 1990 Northern, Iran Images

    National Oceanic and Atmospheric Administration, Department of Commerce — A magnitude 7.7 earthquake occurred in the Gilan Province between the towns of Rudbar and Manjil in northern Iran on Thursday, June 21, 1990 (June 20 at 21:00 GMT)....

  20. Neotectonics in the northern equatorial Brazilian margin

    Rossetti, Dilce F.; Souza, Lena S. B.; Prado, Renato; Elis, Vagner R.


    An increasing volume of publications has addressed the role of tectonics in inland areas of northern Brazil during the Neogene and Quaternary, despite its location in a passive margin. Hence, northern South America plate in this time interval might have not been as passive as usually regarded. This proposal needs further support, particularly including field data. In this work, we applied an integrated approach to reveal tectonic structures in Miocene and late Quaternary strata in a coastal area of the Amazonas lowland. The investigation, undertaken in Marajó Island, mouth of the Amazonas River, consisted of shallow sub-surface geophysical data including vertical electric sounding and ground penetrating radar. These methods were combined with morphostructural analysis and sedimentological/stratigraphic data from shallow cores and a few outcrops. The results revealed two stratigraphic units, a lower one with Miocene age, and an upper one of Late Pleistocene-Holocene age. An abundance of faults and folds were recorded in the Miocene deposits and, to a minor extent, in overlying Late Pleistocene-Holocene strata. In addition to characterize these structures, we discuss their origin, considering three potential mechanisms: Andean tectonics, gravity tectonics related to sediment loading in the Amazon Fan, and rifting at the continental margin. Amongst these hypotheses, the most likely is that the faults and folds recorded in Marajó Island reflect tectonics associated with the history of continental rifting that gave rise to the South Atlantic Ocean. This study supports sediment deposition influenced by transpression and transtension associated with strike-slip divergence along the northern Equatorial Brazilian margin in the Miocene and Late Pleistocene-Holocene. This work records tectonic evidence only for the uppermost few ten of meters of this sedimentary succession. However, available geological data indicate a thickness of up to 6 km, which is remarkably thick for

  1. New nickel-uranium-arsenic mineral species from the oxidation zone of the Belorechenskoye deposit, Northern Caucasus, Russia. Pt. II. Dymkovite, Ni(UO{sub 2}){sub 2}(As{sup 3+}O{sub 3}){sub 2}.7H{sub 2}O, a seelite-related arsenite

    Pekov, Igor V.; Bryzgalov, Igor A. [Moscow State Univ. (Russian Federation). Faculty of Geology; Levitskiy, Viktor V. [Russian Minerals Co., Moscow (Russian Federation); Krivovichev, Sergey V.; Zolotarev, Andrey A. [St Petersburg State Univ. (Russian Federation). Faculty of Geology; Chukanov, Nikita V. [Institute of Problems of Chemical Physics, Chernogolovka, Moscow (Russian Federation); Zadov, Aleksandr E. [NPP ' ' Teplokhim' ' , Moscow (Russian Federation)


    A new arsenite mineral species dymkovite, ideally Ni(UO{sub 2}){sub 2}(As{sup 3+}O{sub 3}){sub 2}.7H{sub 2}O (IMA no. 2010-087), was found at the Belorechenskoye deposit, Adygea Republic, Northern Caucasus, Russia. It is a supergene mineral associated with rauchite, annabergite, and goethite in cavities of a dolomite vein with primary uraninite (pitchblende), nickeline, and gersdorffite. Dymkovite forms longprismatic, lath-shaped to acicular crystals (≤0.5 mm long, ≤0.05 mm thick), which are elongated along [010]. They are combined in sprays or open-work, chaotic groups up to 1.5 mm across; crusts up to 2 x 2 mm{sup 2} and up to 0.05-mm-thick also occur. Dymkovite crystals are transparent and bright yellow, whereas crusts are translucent and light yellow to light greenish-yellow. The luster is vitreous. The mineral is brittle, the Mohs' hardness is ca. 3. Cleavage was not observed. D{sub calc} is 3.806 g cm{sup -3}. Dymkovite is optically biaxial (-), α = 1.625(2), β = 1.735(5), γ = 1.745(3), 2V{sub meas} = 20(10) , 2V{sub calc.} = 32 . Dispersion is strong, r > v. Pleochroism is strong: X = very pale yellowish-green, Y ∼ Z = light greenish yellow. In the IR spectrum, bands of As{sup 3+}O{sub 3} anions are strong, whereas bands of As{sup 5+}O{sub 4} anions are very weak. The average chemical composition (electron microprobe) is (in wt%): MgO = 1.11, FeO = 0.24, NiO = 5.40, ZnO = 0.23, As{sub 2}O{sub 3} = 19.57, P{sub 2}O{sub 5} = 0.58, UO{sub 3} = 59.43, H{sub 2}O{sub calc} = 13.44, total = 100.00. The empirical formula, calculated on the basis of 17 O apfu, is: (Ni{sub 0.69}Mg{sub 0.26}Fe{sub 0.03}Zn{sub 0.03}){sub Σ1.01} U{sub 1.97}(As{sup 3+}{sub 1.88}P{sub 0.08}){sub Σ1.96}O{sub 9.94}.7.06H{sub 2}O. Dymkovite is monoclinic, space group C2/m, a = 17.99(3), b = 7.033(7), c = 6.633(9) Aa, β = 99.62(11) , V = 827(3) Aa{sup 3}, Z = 2. The crystal structure was refined from single-crystal X-ray diffraction data (R{sub 1} = 0.063). The structure is

  2. Estimating the frequency of volcanic ash clouds over northern Europe

    Watson, E. J.; Swindles, G. T.; Savov, I. P.; Lawson, I. T.; Connor, C. B.; Wilson, J. A.


    Fine ash produced during explosive volcanic eruptions can be dispersed over a vast area, where it poses a threat to aviation, human health and infrastructure. Here, we focus on northern Europe, which lies in the principal transport direction for volcanic ash from Iceland, one of the most active volcanic regions in the world. We interrogate existing and newly produced geological and written records of past ash fallout over northern Europe in the last 1000 years and estimate the mean return (repose) interval of a volcanic ash cloud over the region to be 44 ± 7 years. We compare tephra records from mainland northern Europe, Great Britain, Ireland and the Faroe Islands, with records of proximal Icelandic volcanism and suggest that an Icelandic eruption with a Volcanic Explosivity Index rating (VEI) ≥ 4 and a silicic magma composition presents the greatest risk of producing volcanic ash that can reach northern Europe. None of the ash clouds in the European record which have a known source eruption are linked to a source eruption with VEI < 4. Our results suggest that ash clouds are more common over northern Europe than previously proposed and indicate the continued threat of ash deposition across northern Europe from eruptions of both Icelandic and North American volcanoes.

  3. Evolution of ore deposits on terrestrial planets

    Burns, R. G.


    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars

  4. Evolution of ore deposits on terrestrial planets

    Burns, R. G.


    Ore deposits on terrestrial planets materialized after core formation, mantle evolution, crustal development, interactions of surface rocks with the hydrosphere and atmosphere, and, where life exists on a planet, the involvement of biological activity. Core formation removed most of the siderophilic and chalcophilic elements, leaving mantles depleted in many of the strategic and noble metals relative to their chondritic abundances. Basaltic magma derived from partial melting of the mantle transported to the surface several metals contained in immiscible silicate and sulfide melts. Magmatic ore deposits were formed during cooling, fractional crystallization and density stratification from the basaltic melts. Such ore deposits found in earth's Archean rocks were probably generated during early histories of all terrestrial planets and may be the only types of igneous ores on Mars. Where plate tectonic activity was prevalent on a terrestrial planet, temporal evolution of ore deposits took place. Repetitive episodes of subduction modified the chemical compositions of the crust and upper mantles, leading to porphyry copper and molybdenum ores in calc-alkaline igneous rocks and granite-hosted tin and tungsten deposits. Such plate tectonic-induced mineralization in relatively young igneous rocks on earth may also have produced hydrothermal ore deposits on Venus in addition to the massive sulfide and cumulate chromite ores associated with Venusian mafic igneous rock. Sedimentary ore deposits resulting from mechanical and chemical weathering in reducing atmospheres in Archean earth included placer deposits (e.g., uraninite, gold, pyrite ores). Chromite, ilmenite, and other dense unreactive minerals could also be present on channel floors and in valley networks on Mars, while banded iron formations might underlie the Martian northern plains regions. As oxygen evolved in earth's atmosphere, so too did oxide ores. By analogy, gossans above sulfide ores probably occur on Mars

  5. Global assessment of nitrogen deposition effects on terrestrial plant diversity: a synthesis

    Bobbink, R.; Hicks, K.; Galloway, J.; Spranger, T.; Alkemade, R.; Ashmore, M.R.; Bustamante, M.; Cinderby, S.; Davidson, E.; Dentener, F.; Emmett, B.; Erisman, J.W.; Fenn, M.; Gilliam, F.; Nordin, A.; Pardo, L.; Vries, de W.


    Atmospheric nitrogen (N) deposition is a recognized threat to plant diversity in temperate and northern parts of Europe and North America. This paper assesses evidence from field experiments for N deposition effects and thresholds for terrestrial plant diversity protection across a latitudinal range

  6. Cobalt Deposits of China:Classification, Distribution and Major Advances

    FENG Chengyou; ZHANG Dequan


    The important strategic metal cobalt has diverse uses and the majority of world cobalt deposits have been found in China. The deposits can be classified into four types, i.e., magmatic Ni-Cu-Co sulfide deposits, hydrothermal and volcanogenic cobalt polymetallic deposits, strata-bound Cu-Co deposits hosted by sedimentary rocks and lateritic Ni-Co deposits, of which the former two types are the most important. There are six principal metallogenic epochs and seven important metallogenic belts according to their distribution and tectonic position. Although cobalt generally occurs in nickel-copper, copper and iron deposits as an associated metal, great developments in exploration for independent cobalt deposits have happened in China, and, in recent years, many independent deposits with different elementary assemblages and different genetic types have been discovered in the eastem part of the northern margin of the North China platform, the Central Orogenic Belt of China, western Jiangxi and northeastern Hunan. In addition, it is inferred that the Kunlun-Qinling Orogenic Belt has great potential for further exploration of new types of independent cobalt deposits.

  7. Volatile components and C-H-O isotopic compositions of Proterozoic Damiao Fe-Ti-P oxide deposit in the northern margin of the North China Craton%华北克拉通北缘元古宙大庙Fe-Ti-P矿床的挥发份组成和C-H-O同位素研究

    邢长明; 陈伟; 王焰; 赵太平


    The-1.74Ga Damiao massif-type anorthosite complex in the northern margin of the North China Craton hosts a large Fe-Ti-P oxide deposit. Volatiles that were trapped in magnetite, apatite and plagioclase of massive Fe-Ti ore, massive Fe-Ti-P ore and disseminated ore were measured by step heating mass spectrometer at three releasing temperature intervals 200 ~ 400℃ , 400 - 800℃ and 800 ~ 12001 to obtain major components and C-H-0 isotopic composition. Four types of fluid were identified from the volatiles:(1) metamorphic fluid released from plagioclase at 800 ~ 1200℃ temperature interval, mainly composed of H2O, N2 + CO and CO2;(2) mantle-derived fluid released from plagioclase at 400 ~800℃ temperature interval, mainly composed of H2, H2O, CH4 and CO2;(3) surface water released from magnetite at 400 ~800℃ temperature interval, mainly composed of H2O, CO2, SO2 and H2S; and(4) secondary fluid released from minerals at 200 ~400℃ temperature interval, mainly composed of H2O and CO2.Magnetite in both massive Fe-Ti ore and massive Fe-Ti-P ore contains high contents of H2O and CO2, indicating a relatively oxidized condition due to concentration of early-formed fluids and surface water at late stage of magma fractionation sequence, whereas plagioclase in disseminated ore contains abundant H2 and CH4, indicating a relative reduced. It is proposed that the parental magma from which the Damiao anorthosite complex formed may have fractionated under a relatively reduced condition at the beginning. The mantle fluids and surface water may have been involved in the later stage of the magma fractionation and fractioned to increase the oxygen fugacity of the magmas, which in turn, triggered the accumulation of magnetite and apatite to form the Damiao Fe-Ti-P oxide deposit.%华北克拉通北缘~1.74Ga大庙斜长岩杂岩体赋含有大型Fe-Ti-P矿床.采用分步加热质谱法分别测定了块状Fe-Ti矿石、块状Fe-Ti-P矿石和浸染状矿石中磁铁矿、磷灰

  8. Biomimetic thin film deposition

    Rieke, P. C.; Campbell, A. A.; Tarasevich, B. J.; Fryxell, G. E.; Bentjen, S. B.


    Surfaces derivatized with organic functional groups were used to promote the deposition of thin films of inorganic minerals. These derivatized surfaces were designed to mimic the nucleation proteins that control mineral deposition during formation of bone, shell, and other hard tissues in living organisms. By the use of derivatized substrates control was obtained over the phase of mineral deposited, the orientation of the crystal lattice and the location of deposition. These features are of considerable importance in many technically important thin films, coatings, and composite materials. Methods of derivatizing surfaces are considered and examples of controlled mineral deposition are presented.

  9. Bauxite Deposits in China



    Bauxite deposits in China,rangin in age from Late Paleozoic to Cenozoic ,are distributed mainly in Shanxi,Shandong Henan,Guizhou,Guangxi and Yunnan.Based on stratigraphic relations they can be clas-sified as 6 types:inter-system marine,inter-system continental,intra-system marine,intra-system continent-tal,weathering lateritic and weathering accumulation types.But in terms of depositional environments,only four types are distinguished,I.e.the marine deposits,continental deposits,lateritic deposits and weath-ering-accumulation deposits.These deposits have been formed in two steps:firstly,the depression of paraplatform or front basin margins in paleocontinents and secondly,the development of littoral-lagoons on the eroded surface of karstified carbonate bedrocks.The aluminum may have been derived from the carbonate rocks with which the ores are associated,or from adjacent aluminosilicate rocks.

  10. Structure of the Red Dog District, western Brooks Range, Alaska

    de Vera, Jean-Pierre P.; McClay, K. R.


    The Red Dog district of the western Brooks Range of northern Alaska, which includes the sediment-hosted Zn-Pb-Ag ± Ba deposits at Red Dog, Su-Lik, and Anarraaq, contains one of the world's largest reserves of zinc. This paper presents a new model for the structural development of the area and shows that understanding the structure is crucial for future exploration efforts and new mineral discoveries in the district. In the Red Dog district, a telescoped Late Devonian through Jurassic continental passive margin is exposed in a series of subhorizontally stacked, internally imbricated, and regionally folded thrust sheets. These sheets were emplaced during the Middle Jurassic to Late Cretaceous Brookian orogeny and subsequently were uplifted by late tectonic activity in the Tertiary. The thrust sheet stack comprises seven tectonostratigraphically distinct allochthonous sheets, three of which have been subject to regional and detailed structural analysis. The lowermost of these is the Endicott Mountains allochthon, which is overlain by the structurally higher Picnic Creek and Kelly River allochthons. Each individual allochthon is itself internally imbricated into a series of tectonostratigraphically coherent and distinct thrust plates and subplates. This structural style gives rise to duplex development and imbrication at a range of scales, from a few meters to tens of kilometers. The variable mechanical properties of the lithologic units of the ancient passive margin resulted in changes in structural styles and scales of structures across allochthon boundaries. Structural mapping and analysis of the district indicate a dominant northwest to west-northwest direction of regional tectonic transport. Local north to north-northeast transport of thrust sheets is interpreted to reflect the influence of underlying lateral and/or oblique ramps, which may have been controlled by inherited basin margin structures. Some thrust-sheet stacking patterns suggest out

  11. Gold and gold working in Late Bronze Age Northern Greece

    Vavelidis, M.; Andreou, S.


    Numerous objects of gold displaying an impressive variety of types and manufacturing techniques are known from the Late Bronze Age (LBA) contexts of Mycenaean Greece, but very little is known about the origin and processing of gold during the second millennium b.c. Ancient literature and recent research indicate that northern Greece is probably the richest gold-bearing region in Greece, and yet, very little evidence exists regarding the exploitation of its deposits and the production as well as use of gold in the area during prehistory. The unusual find of a group of small stone crucibles at the prehistoric settlement of Thessaloniki Toumba, one with visible traces of gold melting, proves local production and offers a rare opportunity to examine the process of on-site gold working. Furthermore, the comparison of the chemical composition of prehistoric artefacts from two settlements with those of gold deposits in their immediate areas supports the local extraction of gold and opens up the prospect for some of the Mycenaean gold to have originated in northern Greece. The scarcity of gold items in northern Greek LBA contexts may not represent the actual amount of gold produced and consumed, but could be a result of the local social attitudes towards the circulation and deposition of artefacts from precious metals.

  12. Seismicity in Northern Germany

    Bischoff, Monika; Gestermann, Nicolai; Plenefisch, Thomas; Bönnemann, Christian


    Northern Germany is a region of low tectonic activity, where only few and low-magnitude earthquakes occur. The driving tectonic processes are not well-understood up to now. In addition, seismic events during the last decade concentrated at the borders of the natural gas fields. The source depths of these events are shallow and in the depth range of the gas reservoirs. Based on these observations a causal relationship between seismicity near gas fields and the gas production is likely. The strongest of these earthquake had a magnitude of 4.5 and occurred near Rotenburg in 2004. Also smaller seismic events were considerably felt by the public and stimulated the discussion on the underlying processes. The latest seismic event occurred near Langwedel on 22nd November 2012 and had a magnitude of 2.8. Understanding the causes of the seismicity in Northern Germany is crucial for a thorough evaluation. Therefore the Seismological Service of Lower Saxony (NED) was established at the State Office for Mining, Energy and Geology (LBEG) of Lower Saxony in January 2013. Its main task is the monitoring and evaluation of the seismicity in Lower Saxony and adjacent areas. Scientific and technical questions are addressed in close cooperation with the Seismological Central Observatory (SZO) at the Federal Institute for Geosciences and Natural Resources (BGR). The seismological situation of Northern Germany will be presented. Possible causes of seismicity are introduced. Rare seismic events at greater depths are distributed over the whole region and probably are purely tectonic whereas events in the vicinity of natural gas fields are probably related to gas production. Improving the detection threshold of seismic events in Northern Germany is necessary for providing a better statistical basis for further analyses answering these questions. As a first step the existing seismic network will be densified over the next few years. The first borehole station was installed near Rethem by BGR

  13. Northern Pintail Telemetry [ds231

    California Department of Resources — Using radio-telemetry, female northern pintail (Anas acuta) survival, distribution, and movements during late August-March in Central California were determined...

  14. Late Holocene geomorphic record of fire in ponderosa pine and mixed-conifer forests, Kendrick Mountain, northern Arizona, USA

    Sara E. Jenkins; Carolyn Hull Sieg; Diana E. Anderson; Darrell S. Kaufman; Philip A. Pearthree


    Long-term fire history reconstructions enhance our understanding of fire behaviour and associated geomorphic hazards in forested ecosystems. We used 14C ages on charcoal from fire-induced debris-flow deposits to date prehistoric fires on Kendrick Mountain, northern Arizona, USA. Fire-related debris-flow sedimentation dominates Holocene fan deposition in the study area...

  15. Shedding of ash deposits

    Zbogar, Ana; Frandsen, Flemming; Jensen, Peter Arendt;


    Ash deposits formed during fuel thermal conversion and located on furnace walls and on convective pass tubes, may seriously inhibit the transfer of heat to the working fluid and hence reduce the overall process efficiency. Combustion of biomass causes formation of large quantities of troublesome...... ash deposits which contain significant concentrations of alkali, and earth-alkali metals. The specific composition of biomass deposits give different characteristics as compared to coal ash deposits, i.e. different physical significance of the deposition mechanisms, lower melting temperatures, etc....... Low melting temperatures make straw ashes especially troublesome, since their stickiness is higher at lower temperatures, compared to coal ashes. Increased stickiness will eventually lead to a higher collection efficiency of incoming ash particles, meaning that the deposit may grow even faster...

  16. ElectroSpark Deposition


    ElectroSpark Deposition Hard Chrome Alternatives Team Joint Cadmium Alternatives Team Canadian Hard Chrome Alternatives Team Joint Group on Pollution...00-2007 to 00-00-2007 4. TITLE AND SUBTITLE ElectroSpark Deposition 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S...Processes, Inc. ElectroSpark Deposition (ESD) Results of Materials Testing and Technology Insertion January 25, 2007 Advanced Surfaces And Processes, Inc. 3

  17. Fertilization in northern forests

    Hedwall, Per Ola; Gong, Peichen; Ingerslev, Morten


    resources into food, health and industrial products and energy. Fertilization in Sweden and Finland is currently practiced by extensive fertilization regimens where nitrogen fertilizers are applied once, or up to three times, during a rotation period, mainly in mature forest. This type of fertilization......Forests of northern ecosystems respond slowly to management activities and the possibilities to increase the growth in a short-term perspective and meet swift increases in society's demand for biomass are small. An exception among the silvicultural measures is fertilization which can be applied...... in combination with present management systems and, almost instantly, enhances forest productivity. There may, however, be both economic and environmental constraints to large-scale applications of fertilizers in forest. Here we review the literature concerning biomass production of forests under different...

  18. Glyphosate in northern ecosystems.

    Helander, Marjo; Saloniemi, Irma; Saikkonen, Kari


    Glyphosate is the main nonselective, systemic herbicide used against a wide range of weeds. Its worldwide use has expanded because of extensive use of certain agricultural practices such as no-till cropping, and widespread application of glyphosate-resistant genetically modified crops. Glyphosate has a reputation of being nontoxic to animals and rapidly inactivated in soils. However, recent evidence has cast doubts on its safety. Glyphosate may be retained and transported in soils, and there may be cascading effects on nontarget organisms. These processes may be especially detrimental in northern ecosystems because they are characterized by long biologically inactive winters and short growing seasons. In this opinion article, we discuss the potential ecological, environmental and agricultural risks of intensive glyphosate use in boreal regions.

  19. Atmospheric removal of PM2.5 by man-made Three Northern Regions Shelter Forest in Northern China estimated using satellite retrieved PM2.5 concentration.

    Zhang, Xiaodong; Du, Jiao; Huang, Tao; Zhang, Leiming; Gao, Hong; Zhao, Yuan; Ma, Jianmin


    Atmospheric removal of PM2.5 by the Three Northern Regions Shelter Forest (TNRSF) - the so called Green Great Wall (GGW) in northern China through dry deposition process was estimated using a bulk big-leaf model and a vegetation collection model. Decadal trend of PM2.5 dry deposition flux from 1999 to 2010 was calculated from modeled dry deposition velocity and air concentration retrieved from the satellite remote sensing. Dry deposition velocities of PM2.5 calculated using the two deposition models increased in many places of the TNRSF over the last decade due to increasing vegetation coverage of the TNRSF. Both increasing deposition velocity due to forest expansion and PM2.5 atmospheric level contributed to the increasing deposition flux of PM2.5. The highest atmospheric deposition flux of PM2.5 was found in the Central-north region covering Beijing-Tianjin-Hebei area, followed by the Northwestern and the Northeastern regions of the TNRSF. While greater collection of PM2.5 by vegetation was identified in the Northeastern region of the TNRSF due to higher forest coverage over this region, the most significant incline of the PM2.5 atmospheric removal due to vegetation collection was discerned in the Central-north region because of the most rapid increase in the vegetation coverage in this region. A total mass of 2.85×10(7)t PM2.5 was estimated to be removed from the atmosphere through dry deposition process over the TNRSF from 1999 to 2010. The two deposition models simulated similar magnitude and spatial patterns of PM2.5 dry deposition fluxes. Our results suggest that the TNRSF plays a moderate role in PM2.5 uptake, but enhances PM2.5 atmospheric removal by 30% in 2010 than in 1980.

  20. MAPLE deposition of nanomaterials

    Caricato, A.P., E-mail: [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Arima, V.; Catalano, M. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Cesaria, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Cozzoli, P.D. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Martino, M. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Taurino, A.; Rella, R. [Institute for Microelectronics and Microsystems, IMM-CNR, Via Monteroni, I-73100 Lecce (Italy); Scarfiello, R. [National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy); Tunno, T. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); Zacheo, A. [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Via Arnesano, I-73100 Lecce (Italy); National Nanotechnology Laboratory (NNL), CNR Istituto Nanoscienze, c/o Distretto Tecnologico, Via Arnesano n. 16, I-73100 Lecce (Italy)


    The matrix-assisted pulsed laser evaporation (MAPLE) has been recently exploited for depositing films of nanomaterials by combining the advantages of colloidal inorganic nanoparticles and laser-based techniques. MAPLE-deposition of nanomaterials meeting applicative purposes demands their peculiar properties to be taken into account while planning depositions to guarantee a congruent transfer (in terms of crystal structure and geometric features) and explain the deposition outcome. In particular, since nanofluids can enhance thermal conductivity with respect to conventional fluids, laser-induced heating can induce different ablation thermal regimes as compared to the MAPLE-treatment of soft materials. Moreover, nanoparticles exhibit lower melting temperatures and can experience pre-melting phenomena as compared to their bulk counterparts, which could easily induce shape and or crystal phase modification of the material to be deposited even at very low fluences. In this complex scenario, this review paper focuses on examples of MAPLE-depositions of size and shape controlled nanoparticles for different applications highlights advantages and challenges of the MAPLE-technique. The influence of the deposition parameters on the physical mechanisms which govern the deposition process is discussed.

  1. Sedimentology and chemostratigraphy of a Valanginian carbonate succession from the Baja Guajira Basin, northern Colombia

    Silva-Tamayo, Juan Carlos; Ramirez, Catalina; Lara, Mario; Sial,Alcides Nobrega; Trujillo, David; Salazar, Edward


    ABSTRACT: The Kesima Member of the Palanz Formation constitutes the first record of Cretaceous marine sedimentation along the Baja Guajira Basin, northern Colombia. Sedimentologic and petrographic analyses suggest a deposition along a coral reef dominated rimmed carbonate platform. 87Sr/86Sr values between 0.707350 and 0.707400 suggest a Valanginian (136 - 132 Ma) depositional age for the Kesima Member. A positive anomaly on the δ13C values of ~2.2‰ suggests that this rimmed carbon...

  2. Solid on liquid deposition

    Charmet, J., E-mail: jerome.charmet@he-arc.c [Institut des Microtechnologies Appliquees ARC, HES-SO Arc, Eplatures-Grise 17, 2300 La Chaux-de-Fonds (Switzerland); Banakh, O.; Laux, E.; Graf, B.; Dias, F.; Dunand, A.; Keppner, H. [Institut des Microtechnologies Appliquees ARC, HES-SO Arc, Eplatures-Grise 17, 2300 La Chaux-de-Fonds (Switzerland); Gorodyska, G.; Textor, M. [BioInterface group, ETHZ, Wolfgang-Pauli-Strasse 10, ETH Hoenggerberg HCI H 525 8093 Zuerich (Switzerland); Noell, W.; Rooij, N.F. de [Ecole Polytechnique Federale de Lausanne, Institute of Microengineering, Sensors, Actuators and Microsystems laboratory, Rue Jaquet Droz 1, 2000 Neuchatel (Switzerland); Neels, A.; Dadras, M.; Dommann, A.; Knapp, H. [Centre Suisse d' Electronique et de Microtechnique SA, Rue Jacquet-Droz 1, 2002 Neuchatel (Switzerland); Borter, Ch.; Benkhaira, M. [COMELEC SA, Rue de la Paix 129, 2300 La Chaux-de-Fonds (Switzerland)


    A process for the deposition of a solid layer onto a liquid is presented. The polymer poly-di-chloro-para-xylylene, also known as Parylene C, was grown on low vapour pressure liquids using the conventional low pressure chemical vapour deposition process. A reactor was built and a process developed to enable the deposition of Parylene C at atmospheric pressure over high vapour pressure liquids. It was used to deposit Parylene C over water among others. In all cases Parylene C encapsulated the liquid without influencing its initial shape. The results presented here show also that the Parylene C properties are not affected by its growth on liquid templates and the roughness of the Parylene C surface in contact with the liquid during the deposition is extremely low.

  3. Biomimetic thin film deposition

    Rieke, P.R.; Graff, G.E.; Campbell, A.A.; Bunker, B.C.; Baskaran, S.; Song, L.; Tarasevich, B.J.; Fryxell, G.E.


    Biological mineral deposition for the formation of bone, mollusk shell and other hard tissues provides materials scientists with illustrative materials processing strategies. This presentation will review the key features of biomineralization and how these features can be of technical importance. We have adapted existing knowledge of biomineralization to develop a unique method of depositing inorganic thin films and coating. Our approach to thin film deposition is to modify substrate surfaces to imitate the proteins found in nature that are responsible for controlling mineral deposition. These biomimetic surfaces control the nucleation and growth of the mineral from a supersaturated aqueous solution. This has many processing advantages including simple processing equipment, environmentally benign reagents, uniform coating of highly complex shapes, and enhanced adherence of coating. Many different types of metal oxide, hydroxide, sulfide and phosphate materials with useful mechanical, optical, electronic and biomedical properties can be deposited.

  4. Tsunami Deposit Data Base

    Keating, B. H.; Wanink, M.


    A digital database has been established describing tsunami deposits around the world (3 phases; 15 months). The projects involved the review and tabulation of data derived from books, catalogs, journals, preprints, citations and abstracts (currently 1000 references), into a database designed to provide a comprehensive review of the types of tsunami deposits, their geographic distribution and location, sedimentary characteristics, fossil content, age, preservation, run-up, wave height and inundation observations, etc. (34 parameters). The tsunami occurrences can be divided into many subjects, e.g., Volcanogenic (N=375), Seismites (N=49), Co-seismic (N=258), K/T Boundary Impact-triggered debris flows (N=97), Landslides (N=43), etc. Numerous publications compare tsunami deposits to storm deposits (N=38), or analyze the origin of megaboulders (N=22). Tsunami deposits occur throughout geologic time (Pre-Cambrian to present day), and because of plate tectonics, they occur along plate margins (primarily subduction zones) as well as interior to plates. In addition, they occur in epi-continental seas, fjords, etc. Few publications describe depositional processes. Deposits generated by tsunamis occur in multiple environments such as the marine, fresh water, and subaerial. Common characteristics of tsunami deposits include: 1) Deposition of thin sand sheets (can be normal, massive, inversely graded, chaotic or bimodal). 2) Erosional: basal uncomformity, mud balls, rip-up clasts, reworked fossils produced by scouring. 3) Lithology: Stacks of couplets reflecting marine incursions (often sands) into fresh water or subaerial environments (mud, soil, peat). 4) Fossil: Couplets reflects marine fossils, fresh water fossils or a mixed assemblage. 5) Geomorphology: The sand sheets taper landward and can rise in elevation. 6) Deformation: syn-depositional (soft sediments) and intraformational (stiff sediments).

  5. Increasing aeolian dust deposition to snowpacks in the Rocky Mountains inferred from snowpack, wet deposition, and aerosol chemistry

    Clow, David W.; Williams, Mark W.; Schuster, Paul F.


    Mountain snowpacks are a vital natural resource for ∼1.5 billion people in the northern Hemisphere, helping to meet human and ecological demand for water in excess of that provided by summer rain. Springtime warming and aeolian dust deposition accelerate snowmelt, increasing the risk of water shortages during late summer, when demand is greatest. While climate networks provide data that can be used to evaluate the effect of warming on snowpack resources, there are no established regional networks for monitoring aeolian dust deposition to snow. In this study, we test the hypothesis that chemistry of snow, wet deposition, and aerosols can be used as a surrogate for dust deposition to snow. We then analyze spatial patterns and temporal trends in inferred springtime dust deposition to snow across the Rocky Mountains, USA, for 1993-2014. Geochemical evidence, including strong correlations (r2 ≥ 0.94) between Ca2+, alkalinity, and dust concentrations in snow deposited during dust events, indicate that carbonate minerals in dust impart a strong chemical signature that can be used to track dust deposition to snow. Spatial patterns in chemistry of snow, wet deposition, and aerosols indicate that dust deposition increases from north to south in the Rocky Mountains, and temporal trends indicate that winter/spring dust deposition increased by 81% in the southern Rockies during 1993-2014. Using a multivariate modeling approach, we determined that increases in dust deposition and decreases in springtime snowfall combined to accelerate snowmelt timing in the southern Rockies by approximately 7-18 days between 1993 and 2014. Previous studies have shown that aeolian dust emissions may have doubled globally during the 20th century, possibly due to drought and land-use change. Climate projections for increased aridity in the southwestern U.S., northern Africa, and other mid-latitude regions of the northern Hemisphere suggest that aeolian dust emissions may continue to increase

  6. Lithostratigraphical analysis in northern Sinus Meridiani, Mars.

    Baioni, D.; Sgavetti, M.; Tampella, G.; Wezel, F. C.


    In the Terra Meridiani- Arabia Terra region of Mars, layered rock units with a range of stratal patterns have been widely reported in the literature, and the record of the spectral signatures indicative of hydrate minerals suggests the existence of aqueous activity in at least some of the stratigraphic units. . In this work we investigated the area in the northern region of Sinus Meridiani located between 2°N to 3°N latitude and 2°W to 1°E longitude, using multiple remote sensing data sets to identify, characterize in detail, and understand the origin and evolution of the selected units in this region of Mars. MOLA and HiRISE data were used in combination to classify and correlate surface units recorded in distinct stratigraphic logs, based on planimetric configuration, topography, morphological and litho-facies characteristics. In particular, detailed analyses were focused on the layered units discovered in the walls of two impact craters located at a distance of about 100 km to each other within the study area. The stratigraphic interval analysed here corresponds to the upper part of the well known "light-toned layered deposits" identified by several authors. Distinct competent layers are observed in the internal slopes of both craters. Our observations indicate that the lithostratigraphic sections can be divided in three units. The lower unit consists of very thick bodies of light-toned bouldery breccia deposits. In the HiRISE images these white-coloured beds are composed of irregularly-shaped, white nodules which are either isolated or coalescent, distributed between bedding planes. The middle unit mainly consists of alternating thin strong layers and thicker sequences of relatively weak layers, horizontally bedded. The strong, competent layers maintain steeper erosional profiles and play a major role in controlling the overall shape and geomorphology of the wall slopes. The upper unit can be traced laterally in the surrounding ground level, displaying mesa

  7. Aquifer Properties in Hepokangas, Northern Finland

    Pihlaja, M. Sc.


    Hepokangas study area is located in northern Finland, app. 60 km north-east of the city of Oulu. It consists of an esker ridge which ranges in elevation from 95 to 105 m.a.s.l. Consequently, all Quaternary deposits in the area have been influenced by erosional and depositional processes during two Baltic Sea stages (Ancylus Lake and Littorina Sea). Therefore, raised beaches are found on the esker slopes and fine grained sediments on the lowlands. The studied aquifer, the Hepokangas esker is part of an discontinuous chain of eskers which, in total, is about 100 km long and is elongated from north-west to south-east. The direction indicates that the esker was deposited by the melt waters during the latest phase of Weichselian glaciation. The primary part of the esker is located in the western segment of the area and a delta-like expansion of an esker is in the eastern part of the study area . Level of the ground water table (GWT) was measured at 14 ground water pipes which were located in varying parts of the Hepokangas formation. Ground penetrating radar (GPR) surveys were conducted on the primary part of the esker in order to determine internal structures and estimate permeability of the formation. Ground water flow directions were interpreted based on these measurements. The GWT varies from 91.91 to 97.98 m.a.s.l. Since the Hepokangas formation is surrounded by mires the height of the GWT decreased towards them. There was a water pumping station on the primary part of the formation, but no clear effect to the GWT could be seen to be caused by that. From the GPR results, some locations of the coarse grain sediments with high permeability were found.

  8. Structural characteristics of chalcopyrite from a Cu(Au) ore deposit in the Carajas Mineral Province, Brazil

    Aparecida Ribeiro, Andreza; Quintao Lima, Diana; Anderson Duarte, Helio; Murad, Enver [ICEx, UFMG, Departamento de Quimica (Brazil); Pereira, Marcio Cesar, E-mail: [Universidade Federal dos Vales do Jequitinhonha e Mucuri, Instituto de Ciencia e Tecnologia (Brazil); Tadeu de Freitas Suita, Marcos [UFOP, Departamento de Geologia (Brazil); Ardisson, Jose Domingos [Centro de Desenvolvimento da Tecnologia Nuclear (Brazil); Fabris, Jose Domingos [Universidade Federal dos Vales do Jequitinhonha e Mucuri, UFVJM (Brazil)


    Moessbauer spectra and X-ray diffraction data show a chalcopyrite from the Cristalino Cu(Au) deposit in the Carajas Mineral Province in northern Brazil to consist of a single, tetragonal phase. This is in stark contrast to a previously described chalcopyrite from the Camaqua copper mine in southern Brazil, obviously reflecting differences in mineral (and thus ore deposit) genesis.

  9. Northern Fur Seal Food Habits

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains food habits samples, usually scats, collected opportunistically on northern fur seal rookeries and haulouts in Alaska from 1987 to present....

  10. Flight tracks, Northern California TRACON

    National Aeronautics and Space Administration — This dataset contains the records of all the flights in the Northern California TRACON. The data was provided by the aircraft noise abatement office...

  11. Podiform chromite deposits

    U.S. Geological Survey, Department of the Interior — Location and characteristics of 1,124 individual mineral deposits of this type, with grade and tonnage models for chromium as well as several related elements.

  12. Speleothem (Cave Deposit) Data

    National Oceanic and Atmospheric Administration, Department of Commerce — Records of past temperature, precipitation, and other aspects of climate derived from mineral deposits found in caves. Parameter keywords describe what was measured...

  13. Alluvial Deposits in Iowa

    Iowa State University GIS Support and Research Facility — This coverage maps alluvial deposits throughout Iowa. This generally would include areas of alluvial soils associated with modern streams that are identified on...

  14. Modeled Wet Nitrate Deposition

    U.S. Environmental Protection Agency — Modeled data on nitrate wet deposition was obtained from Dr. Jeff Grimm at Penn State Univ. Nitrate wet depostion causes acidification and eutrophication of surface...

  15. Chemically deposited tin sulphide

    Akkari, A., E-mail: anis.akkari@ies.univ-montp2.f [Laboratoire de Physique de la Matiere Condensee, Faculte des Sciences de Tunis El Manar, Tunisie 2092 (Tunisia); Institut d' Electronique du Sud, Unite Mixte de Recherche 5214 UM2-CNRS (ST2i), Universite Montpellier 2, Place Eugene Bataillon, CC 082, 34095 Montpellier Cedex 5 (France); Guasch, C. [Institut d' Electronique du Sud, Unite Mixte de Recherche 5214 UM2-CNRS (ST2i), Universite Montpellier 2, Place Eugene Bataillon, CC 082, 34095 Montpellier Cedex 5 (France); Kamoun-Turki, N. [Laboratoire de Physique de la Matiere Condensee, Faculte des Sciences de Tunis El Manar, Tunisie 2092 (Tunisia)


    SnS thin films were deposited on glass substrates after multi-deposition runs by chemical bath deposition from aqueous solution containing 30 ml triethanolamine (TEA) (C{sub 6}H{sub 15}NO{sub 3}) (50%), 10 ml thioacetamide (CH{sub 3}CSNH{sub 2}), 8 ml ammonia (NH{sub 3}) solution and 10 ml of Sn{sup 2+}(0.1 M). These films were characterised with X-ray diffraction (XRD), with scanning electron microscopy, and with spectrophotometric measurements. The obtained thin films exhibit the zinc blend structure, the crystallinity seems to be improved as the film thickness increases and the band gap energy is found to be about 1.76 eV for film prepared after six depositions runs.

  16. Mosses as an integrating tool for monitoring PAH atmospheric deposition: comparison with total deposition and evaluation of bioconcentration factors. A year-long case-study.

    Foan, Louise; Domercq, Maria; Bermejo, Raúl; Santamaría, Jesús Miguel; Simon, Valérie


    Polycyclic aromatic hydrocarbon (PAH) atmospheric deposition was evaluated at a remote site in Northern Spain using moss biomonitoring with Hylocomium splendens (Hedw.) Schimp., and by measuring the total deposition fluxes of PAHs. The year-long study allowed seasonal variations of PAH content in mosses to be observed, and these followed a similar trend to those of PAH fluxes in total deposition. Generally, atmospheric deposition of PAHs is greater in winter than in summer, due to more PAH emissions from domestic heating, less photoreactivity of the compounds, and intense leaching of the atmosphere by wet deposition. However, fractionation of these molecules between the environmental compartments occurs: PAH fluxes in total deposition and PAH concentrations in mosses are correlated with their solubility (r=0.852, pPAH fluxes can be estimated with moss biomonitoring data if the bioconcentration or 'enriching' factors are known.

  17. Electrospark deposition coatings

    Sheely, W. F.


    Hard surfacing for wear resistant and low-friction coatings has been improved by means of advances in the computer controls in electronic circuitry of the electrospark deposition (ESD) process. coatings of nearly any electrically conductive metal alloy or cermet can be deposited on conductive materials. Thickness is usually two mils or less, but can be as high as 10 mils. ESD coatings can quadrupole cutting tool life.

  18. Gemstone deposits of Serbia

    Miladinović, Zoran; Simić, Vladimir; Jelenković, Rade; Ilić, Miloje


    Gemstone minerals in Serbia have never been regarded as an interesting and significant resource. Nevertheless, more than 150 deposits and occurrences have been recorded and some of them preliminarily explored in the last 50 years. The majority of deposits and occurrences are located within the Serbo-Macedonian metallogenic province and the most significant metallogenic units at the existing level of knowledge are the Fruska Gora ore district, Cer ore district, Sumadija metallogenic zone, Kopaonik metallogenic zone and Lece-Halkidiki metallogenic zone. The most important genetic type of deposits is hydrothermal, particularly in case of serpentinite/peridotite as host/parent rock. Placer deposits are also economically important. The dominant gemstones are silica minerals: chalcedony (Chrysoprase, carnelian, bluish chalcedony etc.), jasper (picture, landscape, red etc.), common opal (dendritic, green, milky white etc.), silica masses (undivided), and quartz (rock crystal, amethyst etc.). Beside silica minerals significant gemstones in Serbia include also beryl (aquamarine), garnet (almandine and pyrope), tourmaline, fluorite, rhodochrosite, carbonate-silica breccia, carbonate-silica onyx, silicified wood, howlite, serpentinite, marble onyx, and kyanite. This paper aims to present an overview of Serbian gemstone deposits and occurrences and their position based on a simplified gemstone metallogenic map of Serbia, as well as genetic-industrial classification of gemstone deposits and gemstone varieties.

  19. Gemstone deposits of Serbia

    Miladinović Zoran


    Full Text Available Gemstone minerals in Serbia have never been regarded as an interesting and significant resource. Nevertheless, more than 150 deposits and occurrences have been recorded and some of them preliminarily explored in the last 50 years. The majority of deposits and occurrences are located within the Serbo-Macedonian metallogenic province and the most significant metallogenic units at the existing level of knowledge are the Fruska Gora ore district, Cer ore district, Sumadija metallogenic zone, Kopaonik metallogenic zone and Lece-Halkidiki metallogenic zone. The most important genetic type of deposits is hydrothermal, particularly in case of serpentinite/peridotite as host/parent rock. Placer deposits are also economically important. The dominant gemstones are silica minerals: chalcedony (Chrysoprase, carnelian, bluish chalcedony etc., jasper (picture, landscape, red etc., common opal (dendritic, green, milky white etc., silica masses (undivided, and quartz (rock crystal, amethyst etc.. Beside silica minerals significant gemstones in Serbia include also beryl (aquamarine, garnet (almandine and pyrope, tourmaline, fluorite, rhodochrosite, carbonate-silica breccia, carbonate-silica onyx, silicified wood, howlite, serpentinite, marble onyx, and kyanite. This paper aims to present an overview of Serbian gemstone deposits and occurrences and their position based on a simplified gemstone metallogenic map of Serbia, as well as genetic-industrial classification of gemstone deposits and gemstone varieties.

  20. Classification of Broken Hill-Type Pb-Zn-Ag Deposits: A Refinement

    Spry, P. G.; Teale, G. S.; Steadman, J. A.


    Broken Hill Hill-type Pb-Zn-Ag (BHT) deposits constitute some of the largest ore deposits in the world. The Broken Hill deposit is the largest accumulation of Pb, Zn, and Ag on Earth and the Cannington deposit is currently the largest silver deposit. Characteristic features of BHT deposits include: 1. high Pb+Zn+Ag values with Pb > Zn; 2. Metamorphism to amphibolite-granulite facies; 3. Paleo-to Mesoprotoerozoic clastic metasedimentary host rocks; 4. Sulfides that are spatially associated with bimodal (felsic and mafic) volcanic rocks, and stratabound gahnite- and garnet-bearing rocks and iron formations, 5. Stacked orebodies with characteristic Pb:Zn:Ag ratios and skarn-like Fe-Mn-Ca-F gangue assemblages, and the presence of Cu, Au, Bi, As, and Sb; and 6. Sulfur-poor assemblages. Broken Hill (Australia) has a prominent footwall feeder zone whereas other BHT deposits have less obvious alteration zones (footwall garnet spotting and stratabound alteration haloes). Deposits previously regarded in the literature as BHT deposits are Broken Hill, Cannington, Oonagalabie, Menninie Dam, and Pegmont (Australia), Broken Hill, Swartberg, Big Syncline, and Gamsberg (South Africa), Zinkgruvan (Sweden), Sullivan, Cottonbelt, and Foster River (Canada), and Boquira (Brazil). Of these deposits, only the Broken Hill (Australia, South Africa), Pinnacles, Cannington, Pegmont, and Swartberg deposits are BHT deposits. Another BHT deposit includes the Green Parrot deposit, Jervois Ranges (Northern Territory). The Foster River, Gamsberg, and Sullivan deposits are considered to be "SEDEX deposits with BHT affinities", and the Oonagalabie, Green Mountain (Colorado), and Zinkgruvan are "VMS deposits with BHT affinities". In the Broken Hill area (Australia), Corruga-type Pb-Zn-Ag deposits occur in calc-silicate rocks and possess some BHT characteristics; the Big Syncline, Cottonbelt, Menninie Dam, and Saxberget deposits are Corruga-type deposits. SEDEX deposits with BHT affinities, VMS

  1. Origin of Harmattan dust settled in Northern Ghana – Long transported or local dust?

    Lyngsie, Gry; Awadzi, Theodore W; Breuning-Madsen, Henrik


    compositions of the bulk dust samples. Traces of minerals in the clay fraction of the Harmattan period dust may have their origin in the Bodélé Depression or other saline environments. The Harmattan dust deposited in Ghana shows only little resemblance to dust from the Chad basin and with Harmattan dust...... deposited in Niger. This study therefore suggests that the dust deposited during the Harmattan period in northern Ghana is not under significant influence of sediments from the Bodélé Depression. Similarity in the mineral and elemental composition of the dust from both the Harmattan and Monsoon periods...

  2. Does urban vegetation mitigate air pollution in northern conditions?

    Setälä, Heikki; Viippola, Viljami; Rantalainen, Anna-Lea; Pennanen, Arto; Yli-Pelkonen, Vesa


    It is generally accepted that urban vegetation improves air quality and thereby enhances the well-being of citizens. However, empirical evidence on the potential of urban trees to mitigate air pollution is meager, particularly in northern climates with a short growing season. We studied the ability of urban park/forest vegetation to remove air pollutants (NO2, anthropogenic VOCs and particle deposition) using passive samplers in two Finnish cities. Concentrations of each pollutant in August (summer; leaf-period) and March (winter, leaf-free period) were slightly but often insignificantly lower under tree canopies than in adjacent open areas, suggesting that the role of foliage in removing air pollutants is insignificant. Furthermore, vegetation-related environmental variables (canopy closure, number and size of trees, density of understorey vegetation) did not explain the variation in pollution concentrations. Our results suggest that the ability of urban vegetation to remove air pollutants is minor in northern climates.

  3. Late Pleistocene echimyid rodents (Rodentia, Hystricognathi) from northern Brazil.

    Ferreira, Thais M F; Olivares, Adriana Itati; Kerber, Leonardo; Dutra, Rodrigo P; Avilla, Leonardo S


    Echimyidae (spiny rats, tree rats and the coypu) is the most diverse family of extant South American hystricognath rodents (caviomorphs). Today, they live in tropical forests (Amazonian, coastal and Andean forests), occasionally in more open xeric habitats in the Cerrado and Caatinga of northern South America, and open areas across the southern portion of the continent (Myocastor). The Quaternary fossil record of this family remains poorly studied. Here, we describe the fossil echimyids found in karst deposits from southern Tocantins, northern Brazil. The analyzed specimens are assigned to Thrichomys sp., Makalata cf. didelphoides and Proechimys sp. This is the first time that a fossil of Makalata is reported. The Pleistocene record of echimyids from this area is represented by fragmentary remains, which hinders their determination at specific levels. The data reported here contributes to the understanding of the ancient diversity of rodents of this region, evidenced until now in other groups, such as the artiodactyls, cingulates, carnivores, marsupials, and squamate reptiles.

  4. Uranium ore prospecting and exploration with a special view to sedimentary deposits, illustrated by the example of the Muellenbach deposit. [Federal Republic of Germany

    Mueller, H.


    The Muellenbach deposit near Baden-Baden (northern Black Forest) is used as an example to illustrate the prospecting and exploration methods of Messrs. Saarberg-Interplan which includes: airborne measurements, carborne measurements, Ru measurements near the ground, drills to detect ground anomalies, borehole logging, photosurveys, geochemistry, geophysical surface prospecting, mining exploration, radiation protection.

  5. Geology and hydrogeology of northern Guam

    Barner, W.L. [ICF Kaiser Engineers, Inc., Pittsburgh, PA (United States)


    Recent site characterization activities on the northern portion of the island of Guam have provided data challenging the perception of expected rapid flow within the karst ground water system. The main water bearing formations consist of Tertiary and Quaternary age coralline reef limestones of the Barrigada and Mariana formations. The Barrigada formation lies on top of the underlying Tertiary aged volcanics, and the younger Mariana formation overlies and onlaps the Barrigada formation as a vertical and transgressional facies, changing from a deep to a shallow water depositional sequence. Rain water rapidly infiltrates through the limestone recharging the fresh water aquifer. Conditions that affect the occurrence and extent of the fresh water aquifer are: tidal fluctuations, storm surges, stratigraphic settings, and karstification of the limestone. Evidence from boreholes drilled inland and near the coast suggest karstification has occurred between the phreatic and vadose zone at a depth of approximately 150 meters below ground surface, and within the transition zone between the fresh and salt water interface, near sea level. Although one might expect a rapid flow system in this karst aquifer, non-flashy responses on water levels in wells, and current results from a dye tracing study, suggest ground water movement is indicative of diffuse porous flow. However, flow velocity within the vadose zone has been found to be several times that occurring within the aquifer and it is very difficult to predict the direction of movement. Andersen Air Force Base, located on the northern portion of the island of Guam, has been operating since World War II after re-capturing the island from the Japanese in 1944. In the intervening years, sanitary and industrial wastes have been disposed in various trenches, borrow pits, quarries, and sinkholes. Potential ground water degradation may result if hazardous substances, in the form of leachate, are released from these disposal areas.

  6. Pulsed laser deposition: Prospects for commercial deposition of epitaxial films

    Muenchausen, R.E.


    Pulsed laser deposition (PLD) is a physical vapor deposition (PVD) technique for the deposition of thin films. The vapor source is induced by the flash evaporation that occurs when a laser pulse of sufficient intensity (about 100 MW/cm{sup 2}) is absorbed by a target. In this paper the author briefly defines pulsed laser deposition, current applications, research directed at gaining a better understanding of the pulsed laser deposition process, and suggests some future directions to enable commercial applications.

  7. Geological evolution of the Neoproterozoic Bemarivo Belt, northern Madagascar

    Thomas, Ronald J.; De Waele, B.; Schofield, D.I.; Goodenough, K.M.; Horstwood, M.; Tucker, R.; Bauer, W.; Annells, R.; Howard, K. J.; Walsh, G.; Rabarimanana, M.; Rafahatelo, J.-M.; Ralison, A.V.; Randriamananjara, T.


    The broadly east-west trending, Late Neoproterozoic Bemarivo Belt in northern Madagascar has been re-surveyed at 1:100 000 scale as part of a large multi-disciplinary World Bank-sponsored project. The work included acquisition of 14 U-Pb zircon dates and whole-rock major and trace element geochemical data of representative rocks. The belt has previously been modelled as a juvenile Neoproterozoic arc and our findings broadly support that model. The integrated datasets indicate that the Bemarivo Belt is separated by a major ductile shear zone into northern and southern "terranes", each with different lithostratigraphy and ages. However, both formed as Neoproterozoic arc/marginal basin assemblages that were translated southwards over the north-south trending domains of "cratonic" Madagascar, during the main collisional phase of the East African Orogeny at ca. 540 Ma. The older, southern terrane consists of a sequence of high-grade paragneisses (Sahantaha Group), which were derived from a Palaeoproterozoic source and formed a marginal sequence to the Archaean cratons to the south. These rocks are intruded by an extensive suite of arc-generated metamorphosed plutonic rocks, known as the Antsirabe Nord Suite. Four samples from this suite yielded U-Pb SHRIMP ages at ca. 750 Ma. The northern terrane consists of three groups of metamorphosed supracrustal rocks, including a possible Archaean sequence (Betsiaka Group: maximum depositional age approximately 2477 Ma) and two volcano-sedimentary sequences (high-grade Milanoa Group: maximum depositional age approximately 750 Ma; low grade Daraina Group: extrusive age = 720-740 Ma). These supracrustal rocks are intruded by another suite of arc-generated metamorphosed plutonic rocks, known as the Manambato Suite, 4 samples of which gave U-Pb SHRIMP ages between 705 and 718 Ma. Whole-rock geochemical data confirm the calc-alkaline, arc-related nature of the plutonic rocks. The volcanic rocks of the Daraina and Milanoa groups also

  8. Triassic rift-related sedimentary basins in northern Chile (24° 29°S)

    Suarez, M.; Bell, C. M.


    Triassic rocks in northern Chile (latitude 24°-29°S) include marine and continental rift-related sedimentary deposits, associated with basaltic, andesitic, and silicic volcanic rocks. Five main successions include the deposits of two marine basins (Profeta and San Félix) separated by three continental basins (Cifuncho, La Ternera, and La Coipa). The marine strata include turbidites and debris flow deposits interpreted as coarse-grained fan-delta sediments. The continental sediments include lacustrine fan delta, open lake, braided river, alluvial fan, and sabkha deposits. The widespread fan-delta systems (both marine and lacustrine), together with abrupt lateral and vertical facies discontinuities and large-scale depositional cycles, are indicative of rift-controlled sedimentation. The associated magmatic activity indicates that this rifting was the product of subduction-related extension or strike-slip movement on the active plate margin. Triassic rifting was followed in Late Triassic to Early Jurassic times by widespread thermotectonic subsidence.

  9. Magma ascent, fragmentation and depositional characteristics of "dry" maar volcanoes: Similarities with vent-facies kimberlite deposits

    Berghuijs, Jaap F.; Mattsson, Hannes B.


    Several maar craters within the Lake Natron-Engaruka monogenetic volcanic field (LNE-MVF) of northern Tanzania show compelling evidence for magmatic fragmentation and dry deposition. This is in contradiction of the common belief that most maars are formed through the explosive interaction between ascending magma and ground- or surface water. We here present a detailed study on the eruptive and depositional characteristics of the Loolmurwak and Eledoi maar volcanoes, two of the largest craters in the LNE-MVF, focusing on high-resolution stratigraphy, sedimentology, grain size distribution, pyroclast textures and morphologies, bulk geochemistry and mineral chemistry. At both maars, ejected material has been emplaced by a combination of pyroclastic surges and fallout. Indicators of phreatomagmatic fragmentation and wet deposition, such as impact sags, accretionary lapilli, vesiculated tuffs and plastering against obstacles, are absent in the deposits. Juvenile material predominantly occurs as fluidal-shaped vesicular melt droplets and contains no glass shards produced by the breakage of bubble walls. The Eledoi deposits comprise a large amount of inversely graded beds and lenses, which result from grain flow in a dry depositional environment. Preferential deposition of fine material toward the northern side of its crater can be related to effective wind winnowing in a dry eruption plume. This large variety of observations testifies to the dominance of magmatic fragmentation as well as dry deposition at the Loolmurwak and Eledoi maars, which is in line with what has been found for other structures in the LNE-MVF but contrasts with current ideas on maar formation. We infer that a volatile-rich, olivine melilitic magma was formed by small amounts of partial melting at upper mantle depths. With minimum average ascent rates of 5.3 m s- 1 for Loolmurwak and 26.2 m s- 1 for Eledoi, this magma rapidly moved toward the surface and exsolved a substantial amount of volatiles

  10. Reactive polymer fused deposition manufacturing

    Kunc, Vlastimil; Rios, Orlando; Love, Lonnie J.; Duty, Chad E.; Johs, Alexander


    Methods and compositions for additive manufacturing that include reactive or thermosetting polymers, such as urethanes and epoxies. The polymers are melted, partially cross-linked prior to the depositing, deposited to form a component object, solidified, and fully cross-linked. These polymers form networks of chemical bonds that span the deposited layers. Application of a directional electromagnetic field can be applied to aromatic polymers after deposition to align the polymers for improved bonding between the deposited layers.

  11. U-Pb (LA-ICP-MS of detrital zircon and whole rock Nd and geochemical constraints on the provenance, depositional age and tectonic setting of the metasedimentary Piriá Basin, northern Brazil: implications for the evolution of the Gurupi Belt

    Elem Cristina dos Santos Lopes

    Full Text Available ABSTRACT: The Piriá Basin (Piriá Formation is a hemi-graben shaped basin that developed over Precambrian rocks of the Gurupi Belt. The lithological content comprises four interfingered lithofacies: (1 arkose and greywacke with pelite layers, (2 laminated siltstones and pelites, (3 arkose with hummocky stratification, and (4 oligomictic conglomerate. This sequence was formed in alluvial fans (conglomerate, and fluvial systems (arkose, greywacke, siltstones and pelites that were established and evolved during the migration of the subsidence. The sedimentary sequence underwent anquimetamorphism and very weak tectonic deformation. U-Pb analyses of detrital zircon set the maximum depositional age at 591 Ma and indicate several sediment sources, that range in age from the Neoproterozoic to the Archean. The main sources are from the Rhyacian, which is the main period of continental crust formation in the São Luís cratonic fragment and the basement of the Gurupi Belt. Neoproterozoic sources were important in the eastern segment of the basin. Ages from unknown sources in the region so far have also been recorded. Combined, the U-Pb zircon data, the whole-rock geochemical and Sm-Nd results, and the petrographic information revealed proximal felsic to intermediate provenance, in addition to recycled sedimentary sources. As a whole, our data suggest that the Piriá Formation was deposited in a post-orogenic basin related to the final stage of evolution of the Brasiliano cycle of orogenies, which built up the Gurupi Belt.

  12. Shamanistic practice in Northern Nepal

    Toni Schmid


    Full Text Available The Sherpas—in Tibetan śar-pa or "men of the east"—live mainly in Northern Nepal, in the Darjeeling district, in India and Northern Sikkim, in the regions bordering on Tibet, and on the southern slopes of the Himalayas. The Sherpas are of Tibetan stock. Among the Tibetan racial groups two religions can be broadly distinguished. One is a form of Buddhism, usually called Lamaism. The other religion is called in the Lhasa pronunciation Bon. Among the Sherpas both the religion and its priests are called "bombo", spelt: bongo.

  13. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

    Harmens, H., E-mail: [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Norris, D.A., E-mail: [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Cooper, D.M., E-mail: [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, G., E-mail: [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Steinnes, E., E-mail: [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Kubin, E., E-mail: [Finnish Forest Research Institute, Kirkkosaarentie 7, 91500 Muhos (Finland); Thoeni, L., E-mail: [FUB-Research Group for Environmental Monitoring, Alte Jonastrasse 83, 8640 Rapperswil (Switzerland); Aboal, J.R., E-mail: [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Alber, R., E-mail: [Environmental Agency of Bolzano, 39055 Laives (Italy); Carballeira, A., E-mail: [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Coskun, M., E-mail: [Canakkale Onsekiz Mart University, Faculty of Medicine, Department of Medical Biology, 17100 Canakkale (Turkey); De Temmerman, L., E-mail: [Veterinary and Agrochemical Research Centre, Tervuren (Belgium); Frolova, M., E-mail: [Latvian Environment, Geology and Meteorology Agency, Riga (Latvia); Gonzalez-Miqueo, L., E-mail: [Univ. of Navarra, Irunlarrea No 1, 31008 Pamplona (Spain)


    In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations ({>=}1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r{sup 2} = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: > Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. > Moss concentrations were compared with EMEP modelled nitrogen deposition. > The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha{sup -1} y{sup -1}. > Linear relationships were found with measured nitrogen deposition in some countries. > Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

  14. Lode-gold mineralization in the Tanami region, northern Australia

    Huston, David L.; Vandenberg, Leon; Wygralak, Andrew S.; Mernagh, Terrence P.; Bagas, Leon; Crispe, Andrew; Lambeck, Alexis; Cross, Andrew; Fraser, Geoff; Williams, Nick; Worden, Kurt; Meixner, Tony; Goleby, Bruce; Jones, Leonie; Lyons, Pat; Maidment, David


    The Tanami region of northern Australia has emerged over the last two decades as the largest gold-producing region in the Northern Territory. Gold is hosted by epigenetic quartz veins in sedimentary and mafic rocks, and by sulfide-rich replacement zones within iron formation. Although limited, geochronological data suggest that most mineralization occurred at about 1,805-1,790 Ma, during a period of extensive granite intrusion, although structural relationships suggest that some deposits predate this period. There are three main goldfields in the Tanami region: the Dead Bullock Soak goldfield, which hosts the world-class Callie deposit; The Granites goldfield; and the Tanami goldfield. In the Dead Bullock Soak goldfield, deposits are hosted by carbonaceous siltstone and iron formation where a late (D5) structural corridor intersects an early F1 anticlinorium. In The Granites goldfield, deposits are hosted by highly sheared iron formation and are interpreted to predate D5. The Tanami goldfield consists of a large number of small, mostly basalt-hosted deposits that probably formed at a high structural level during D5. The D5 structures that host most deposits formed in a convergent structural regime with σ 1 oriented between E-W and ENE-WSW. Structures active during D5 include NE-trending oblique thrust (dextral) faults and ESE-trending (sinistral) faults that curve into N- to NNW-trending reverse faults localized in supracrustal belts between and around granite complexes. Granite intrusions also locally perturbed the stress field, possibly localizing structures and deposits. Forward modeling and preliminary interpretations of reflection seismic data indicate that all faults extend into the mid-crust. In areas characterized by the N- to NW-trending faults, orebodies also tend to be N- to NW-trending, localized in dilational jogs or in fractured, competent rock units. In areas characterized by ESE-trending faults, the orebodies and veins tend to strike broadly east

  15. A plate tectonic-paleoceanographic hypothesis for Cretaceous source rocks and cherts of northern South America

    Villamil, T.; Arango, C. (Univ. of Colorado, Boulder, CO (United States))


    New paleocontinental reconstructions show a northern migration of the South American Plate with respect to the paleoequator from the Jurassic to the Late Cretaceous. This movement caused the northern margin of South America to migrate from a position south to a position north of the paleoequator. Ekman transport generated net surface water movement towards the south during times when northern South America was south of the paleoequator. This situation favored downwelling and prevented Jurassic and earliest Cretaceous marine source rocks from being deposited. When northern South America was north of the paleoequator Ekman transport forced net water movement to the north favoring upwelling, paleoproductivity, and the deposition of one of the best marine source rocks known (the La Luna, Villeta, and equivalents). This plate tectonic paleoceanographic hypothesis explains the origin of hydrocarbons in northern South America. The stratigraphic record reflects this increase in paleoproductivity through time. This can be observed in facies (non-calcareous shales to calcareous shales to siliceous shales and finally to bedded cherts) and in changing planktic communities which were initially dominated by healthy calcareous foraminifer assemblages, followed by stressed foraminifer populations and finally by radiolarians. Total organic carbon and source rock quality were affected by this long term increase in paleoproductivity but also, and more markedly, by a punctuated sequence stratigraphic record dominated by low- frequency changes in relative sea level. The magnitude of transgressive episodes caused by rise in sea level determined the extent of source rock intervals and indirectly the content of organic carbon.

  16. A plate tectonic-paleoceanographic hypothesis for Cretaceous source rocks and cherts of northern South America

    Villamil, T.; Arango, C. [Univ. of Colorado, Boulder, CO (United States)


    New paleocontinental reconstructions show a northern migration of the South American Plate with respect to the paleoequator from the Jurassic to the Late Cretaceous. This movement caused the northern margin of South America to migrate from a position south to a position north of the paleoequator. Ekman transport generated net surface water movement towards the south during times when northern South America was south of the paleoequator. This situation favored downwelling and prevented Jurassic and earliest Cretaceous marine source rocks from being deposited. When northern South America was north of the paleoequator Ekman transport forced net water movement to the north favoring upwelling, paleoproductivity, and the deposition of one of the best marine source rocks known (the La Luna, Villeta, and equivalents). This plate tectonic paleoceanographic hypothesis explains the origin of hydrocarbons in northern South America. The stratigraphic record reflects this increase in paleoproductivity through time. This can be observed in facies (non-calcareous shales to calcareous shales to siliceous shales and finally to bedded cherts) and in changing planktic communities which were initially dominated by healthy calcareous foraminifer assemblages, followed by stressed foraminifer populations and finally by radiolarians. Total organic carbon and source rock quality were affected by this long term increase in paleoproductivity but also, and more markedly, by a punctuated sequence stratigraphic record dominated by low- frequency changes in relative sea level. The magnitude of transgressive episodes caused by rise in sea level determined the extent of source rock intervals and indirectly the content of organic carbon.

  17. Mise en évidence de déformations en faille inverse avec ruptures de surface cosismiques dans des dépôts colluviaux würmiens du versant nord du mont Ventoux (Provence occidentale, France)Evidence of reverse faulting and coseismic surface ruptures in Würm colluvial deposits from the Mt Ventoux northern slope (Western Provence, France)

    Dutour, Alain; Philip, Hervé; Jaurand, Erwan; Combes, Philippe

    In western Provence (France), brittle deformation of Quaternary age occurring in the vicinity of the Nı̂mes and Durance faults has been linked to palaeoseisms of significant magnitude. Our new observations made on the southern rim of the Tertiary Malaucène Basin, in the continuation of a thrust to the north of Mt Ventoux, present evidence for reverse faulting deformation in deposits of a Würm colluvial fan. The analysis of a trench section provides clear evidence for: (1) the development of two successive surface ruptures and degradation of associated scarps during the Mid-Upper Würm, and, (2) the continuation of the reverse fault within the Oligocene basement. These tectonic events were associated with earthquakes of at least 6 in magnitude. To cite this article: A. Dutour et al., C. R. Geoscience 334 (2002) 849-856.

  18. A Journey To Northern Europe


    <正>A tourism promotion launched by Northern European countries was held in Shanghai on February 24. Representatives from the tourism authorities in Denmark, Norway and Sweden introduced their special tourism resources to their Chinese counterparts, expressing their strong desire to expand tourism business in the Chinese market.According to the memorandum of understanding signed

  19. Granitoid intrusions and related deposits

    孟良义; 李绪俊


    Taking the Bainaimiao copper and gold deposits, Inner Mongolia and the Wushan copper deposits, Jiangxi Province as examples, a discussion is devoted to the relationship between the granitoid intrusions and related deposits from different lines of evidence: the spatial distribution, country rocks and alteration of the deposits, trace element contents and vertical zoning of elements in deposits, the metallogenic preference of granitoid intrusions, the metallogenic models and stable isotopic geology. It is concluded that the ore-bearing fluids mainly come from granitoid magmas and granitoid intrusions are closely associated with the related deposits in space.

  20. Dispersal of collectors in different-facial Zadonsko-Yeletskiy deposits of the Pripyatskiy trough

    Demidovich, L.A.; Nazarova, N.V.


    Features are examined of dispersal of rock-collectors in different-facial deposits of the lower and upper Zadonskiy sublevels, as well as in the Yeletskiy level of the Devonian in the Pripyatskiy trough. It has been established that rock-collectors in the northern part of the Pripyatskiy trough are associated with organogenic reconstructions.

  1. Stratigraphy Konkian-Sarmatian deposits in the south of Ukraine by molluscs (Middle - Upper Miocene

    Staryn D.A.


    Full Text Available The results of study marine bivalve and gastropod from konkian-sarmatian deposits of the Southern Ukraine are gave. Their lateral and vertical distribution is studied. Local stratigraphic schemes for the Northern Black Sea region,Flat Crimea and Kerch peninsula.

  2. Predicting soil erosion and deposition effects on plant establishment: A key to increasing restoration success

    Soil erosion and deposition can result in significant modification of the soil profile, including changes in soil surface texture and structure. A series of field studies and modeling exercises are currently being completed at the USDA-ARS Jornada Experimental Range, located in the northern Chihuahu...

  3. A review of mineral systems and associated tectonic settings of northern Xinjiang, NW China

    Franco Pirajno


    Full Text Available In this paper we present a review of mineral systems in northern Xinjiang, NW China, focussing on the Tianshan, West and East Junggar and Altay orogenic belts, all of which are part of the greater Central Asian Orogenic Belt (CAOB. The CAOB is a complex collage of ancient microcontinents, island arcs, oceanic plateaux and oceanic plates, which were amalgamated and accreted in Early Palaeozoic to Early Permian times. The establishment of the CAOB collage was followed by strike-slip movements and affected by intraplate magmatism, linked to mantle plume activity, best exemplified by the 250 Ma Siberian Traps and the 280 Ma Tarim event. In northern Xinjiang, there are numerous and economically important mineral systems. In this contribution we describe a selection of representative mineral deposits, including subduction-related porphyry and epithermal deposits, volcanogenic massive sulphides and skarn systems. Shear zone-hosted Au lodes may have first formed as intrusion-related and subsequently re-worked during strike-slip deformation. Intraplate magmatism led to the emplacement of concentrically zoned (Alaskan-style mafic–ultramafic intrusions, many of which host orthomagmatic sulphide deposits. A huge belt of pegmatites in the Altay orogen, locally hosts world-class rare metal deposits. Roll-front, sandstone-hosted U mineralisation completes the rich mineral endowment of the northern Xinjiang terranes.

  4. 20 CFR 703.306 - Kinds of negotiable securities that may be deposited; conditions of deposit; acceptance of deposits.


    ... the Act in the amount fixed by the Office under the regulations in this part shall deposit any... deposited; conditions of deposit; acceptance of deposits. 703.306 Section 703.306 Employees' Benefits... negotiable securities that may be deposited; conditions of deposit; acceptance of deposits. A self-insurer or...

  5. Tectonic deposition of mercury in the Almadén district, Las Cuevas deposit, Spain

    Jébrak, M.; Hernandez, A.


    The Las Cuevas mercury deposit is located in the northern part of the Almadén district, Ciudad Real, Spain. It displays characteristic epigenetic features. A reinterpretation of the geological context of the deposit and a detailed structural analysis indicate that the host rocks at Las Cuevas belong to the same stratigraphic units that host the old Almadén mine, but that they experienced a different tectonic evolution. Two types of ore are distinguished at Las Cuevas: (1) hydraulic breccias in a black quartzite, identical to the San Francisco horizon of the Almadén mine. This ore has been interpreted as syngenetic and is associated with an alkaline explosive volcanic event; and (2) a stockwork composed of horizontal subcritical tension cracks which developed along the contact between black shales and volcanic rocks in the hinge of a drag fold, and which is associated with advanced argillic alteration. Mobilization of mercury from type 1 to type 2 ore was related to a local inversion of the stress field associated with an increase of permeability by self-sealing, which probably occurred during uplift. Las Cuevas is representative of a whole class of mercury deposits hosted within basement rocks.

  6. Inkjet deposited circuit components

    Bidoki, S. M.; Nouri, J.; Heidari, A. A.


    All-printed electronics as a means of achieving ultra-low-cost electronic circuits has attracted great interest in recent years. Inkjet printing is one of the most promising techniques by which the circuit components can be ultimately drawn (i.e. printed) onto the substrate in one step. Here, the inkjet printing technique was used to chemically deposit silver nanoparticles (10-200 nm) simply by ejection of silver nitrate and reducing solutions onto different substrates such as paper, PET plastic film and textile fabrics. The silver patterns were tested for their functionality to work as circuit components like conductor, resistor, capacitor and inductor. Different levels of conductivity were achieved simply by changing the printing sequence, inks ratio and concentration. The highest level of conductivity achieved by an office thermal inkjet printer (300 dpi) was 5.54 × 105 S m-1 on paper. Inkjet deposited capacitors could exhibit a capacitance of more than 1.5 nF (parallel plate 45 × 45 mm2) and induction coils displayed an inductance of around 400 µH (planar coil 10 cm in diameter). Comparison of electronic performance of inkjet deposited components to the performance of conventionally etched items makes the technique highly promising for fabricating different printed electronic devices.

  7. Market Discipline and Deposit Insurance



    The paper examines Russian banks’ household deposit interest rates for the transition period of setting up the deposit insurance system. Monthly observations of Russian banks’ interest rates and balance sheets are used in a fixed effects panel data model. It is shown market discipline has been significantly diminished after switching to the deposit insurance.

  8. Offshore northern Europe, the challenges

    Bergseth, S. [Statoil, Stavenger (Norway)


    This paper relates to challenges of the offshore activity in the North Sea. It is appropriate to address these challenges in the context of generating values through efficient management of resources, markets, safety and technology, as the challenges lie therein. The petroleum industry is built to turn natural resources into market value, assuring broad benefits to stake holders and shareholders. In the following, the challenges facing the industry the industry offshore Northern Europe is examined on this background

  9. Mitigating Radicalism in Northern Nigeria


    laborers and traders from the south settled into can- tonments in most major northern cities. The effect of these sabon gari (“strangers’ quarters” in...result of Peace Club programs. Adults from different ethnic groups now invite each other to child naming ceremonies, weddings, and funerals, which...conventions, establishing standards for charities, and increased international cooperation. In Bangladesh , the government works through the country’s

  10. The deep structure of a sea-floor hydrothermal deposit

    Zierenberg, R.A.; Fouquet, Y.; Miller, D.J.; Bahr, J.M.; Baker, P.A.; Bjerkgard, T.; Brunner, C.A.; Duckworth, R.C.; Gable, R.; Gieskes, J.; Goodfellow, W.D.; Groschel-Becker, H. M.; Guerin, G.; Ishibashi, J.; Iturrino, G.; James, R.H.; Lackschewitz, K.S.; Marquez, L.L.; Nehlig, P.; Peter, J.M.; Rigsby, C.A.; Schultheiss, P.; Shanks, Wayne C.; Simoneit, B.R.T.; Summit, M.; Teagle, D.A.H.; Urbat, M.; Zuffa, G.G.


    Hydrothermal circulation at the crests of mid-ocean ridges plays an important role in transferring heat from the interior of the Earth. A consequence of this hydrothermal circulation is the formation of metallic ore bodies known as volcanic-associated massive sulphide deposits. Such deposits, preserved on land, were important sources of copper for ancient civilizations and continue to provide a significant source of base metals (for example, copper and zinc). Here we present results from Ocean Drilling Program Leg 169, which drilled through a massive sulphide deposit on the northern Juan de Fuca spreading centre and penetrated the hydrothermal feeder zone through which the metal-rich fluids reached the sea floor. We found that the style of feeder-zone mineralization changes with depth in response to changes in the pore pressure of the hydrothermal fluids and discovered a stratified zone of high-grade copper-rich replacement mineralization below the massive sulphide deposit. This copper-rich zone represents a type of mineralization not previously observed below sea-floor deposits, and may provide new targets for land-based mineral exploration.

  11. Geothermal resources of the northern gulf of Mexico basin

    Jones, P.H.


    Published geothermal gradient maps for the northern Gulf of Mexico basin indicate little or no potential for the development of geothermal resources. Results of deep drilling, from 4000 to 7000 meters or more, during the past decade however, define very sharp increases in geothermal gradient which are associated with the occurrence of abnormally high interstitial fluid pressure (geopressure). Bounded by regional growth faults along the landward margin of the Gulf Basin, the geopressured zone extends some 1300 km from the Rio Grande (at the boundary between the United States and Mexico) to the mouth of the Mississippi river. Gulfward, it extends to an unknown distance across the Continental Shelf. Within geopressured deposits, geothermal gradients range upwards to 100 ??C/km, being greatest within and immediately below the depth interval in which the maximum pressure gradient change occurs. The 120 ??C isogeotherm ranges from about 2500 to 5000 m below sea level, and conforms in a general way with depth of occurrence of the top of the geopressured zone. Measured geostatic ratios range upward to 0.97; the maximum observed temperature is 273 ??C, at a depth of 5859 m. Dehydration of montmorillonite, which comprises 60 to 80 percent of clay deposited in the northern Gulf Basin during the Neogene, occurs at depths where temperature exceeds about 80 ??C, and is generally complete at depths where temperature exceeds 120 ??C. This process converts intracrystalline and bound water to free pore water, the volume produced being roughly equivalent to half the volume of montmorillonite so altered. Produced water is fresh, and has low viscosity and density. Sand-bed aquifers of deltaic, longshore, or marine origin form excellent avenues for drainage of geopressured deposits by wells, each of which may yield 10,000 m3 or more of superheated water per day from reservoirs having pressures up to 1000 bars at depths greater than 5000 m. ?? 1971.

  12. Database of recent tsunami deposits

    Peters, Robert; Jaffe, Bruce E.


    This report describes a database of sedimentary characteristics of tsunami deposits derived from published accounts of tsunami deposit investigations conducted shortly after the occurrence of a tsunami. The database contains 228 entries, each entry containing data from up to 71 categories. It includes data from 51 publications covering 15 tsunamis distributed between 16 countries. The database encompasses a wide range of depositional settings including tropical islands, beaches, coastal plains, river banks, agricultural fields, and urban environments. It includes data from both local tsunamis and teletsunamis. The data are valuable for interpreting prehistorical, historical, and modern tsunami deposits, and for the development of criteria to identify tsunami deposits in the geologic record.

  13. Acidic deposition ("acid rain")

    Schreiber, R. Kent; LaRoe, Edward T.; Farris, Gaye S.; Puckett, Catherine E.; Doran, Peter D.; Mac, Michael J.


    Acidic deposition, or "acid rain," describes any form of precipitation, including rain, snow, and fog, with a pH of 5.5 or below (Note: pH values below 7 are acidic; vinegar has a pH of 3). It often results when the acidity of normal precipitation is increased by sulfates and nitrates that are emitted into the atmosphere from burning fossil fuels. This form of airborne contamination is considered harmful, both directly and indirectly, to a host of plant and animal species.Although acid rain can fall virtually anywhere, ecological damages in environmentally sensitive areas downwind of industrial and urban emissions are a major concern. This includes areas that have a reduced capacity to neutralize acid inputs because of low alkalinity soils and areas that contain species with a low tolerance to acid conditions. To determine the distribution of acidic deposition and evaluate its biological effects, research and monitoring are being conducted by the federal government with support from states, universities, and private industry.            The national extent of the acid rain problem has been estimated by sampling water from 3,000 lakes and 500 streams (Irving 1991), representing more than 28,000 lakes and 56,000 stream reaches with a total of 200,000 km (125,000 mi). Some particularly sensitive areas, such as the Adirondack Mountain region, have been more intensively sampled and the biota examined in detail for effects from acidity.         To identify trends in aquatic ecosystems, present and historical survey data on water chemistry and associated biota are compared. In lakes, the chemical and biological history and pH trends may be inferred or reconstructed in some cases by examining assemblages of fossil diatoms and aquatic invertebrates in the sediment layers. In terrestrial ecosystems, vegetation damage is surveyed and effects of acidic deposition to plants and animals are determined from laboratory and field exposure experiments. Natural

  14. Modeling and mapping of atmospheric mercury deposition in adirondack park, new york.

    Xue Yu

    Full Text Available The Adirondacks of New York State, USA is a region that is sensitive to atmospheric mercury (Hg deposition. In this study, we estimated atmospheric Hg deposition to the Adirondacks using a new scheme that combined numerical modeling and limited experimental data. The majority of the land cover in the Adirondacks is forested with 47% of the total area deciduous, 20% coniferous and 10% mixed. We used litterfall plus throughfall deposition as the total atmospheric Hg deposition to coniferous and deciduous forests during the leaf-on period, and wet Hg deposition plus modeled atmospheric dry Hg deposition as the total Hg deposition to the deciduous forest during the leaf-off period and for the non-forested areas year-around. To estimate atmospheric dry Hg deposition we used the Big Leaf model. The average atmospheric Hg deposition to the Adirondacks was estimated as 17.4 [Formula: see text]g m[Formula: see text] yr[Formula: see text] with a range of -3.7-46.0 [Formula: see text]g m[Formula: see text] yr[Formula: see text]. Atmospheric Hg dry deposition (370 kg yr[Formula: see text] was found to be more important than wet deposition (210 kg yr[Formula: see text] to the entire Adirondacks (2.4 million ha. The spatial pattern showed a large variation in atmospheric Hg deposition with scattered areas in the eastern Adirondacks having total Hg deposition greater than 30 μg m(-2 yr(-1, while the southwestern and the northern areas received Hg deposition ranging from 25-30 μg m(-2 yr(-1.

  15. Physical properties and petrologic description of rock samples from an IOCG mineralized area in the northern Fennoscandian Shield, Sweden

    Sandrin, Alessandro; Edfelt, Å.; Waight, Tod Earle


    The Tjårrojåkka Fe-Cu prospect in northern Sweden is considered an example of a Fe-oxide Cu-Au (IOCG) deposit and is hosted in metamorphosed Paleoproterozoic volcanic and intrusive rocks. Rock samples from 24 outcrops were collected for petrophysical analysis (magnetic susceptibility, remanent...

  16. A new fossil-lagerstätte from the lower eocene of lessini mountains (northern Italy): A multidisciplinary approach

    Giusberti, L.; Bannikov, A.; Boscolo Galazzo, F.; Fornaciari, E.; Frieling, J.; Luciani, V.; Papazzoni, C.A.; Roghi, G.; Schouten, S.; Sluijs, A.; Bosellini, F.R.; Zorzin, R.


    Hemipelagic dark limestones within calciturbiditic deposits at Monte Solane in the western Lessini Mountains of northern Italy yield a fish fauna dominated by stomiiforms. A minor component of the fossil assemblage is represented by a macroalgal non-calcareous flora associated with rarer terrestrial

  17. Origin of the tertiary red beds in the Northern part of the Duero Basin (Spain), II. Composition and genesis

    Mabesoone, J.M.


    In this second paper the red beds outcropping in the northern part of the Duero basin have been treated regarding their mineral and pebble composition, chemical parameters, and surface textures of quartz sand grains, taking as basis the results reported in the first paper. These deposits originate f

  18. Comparisons of soil nitrogen mass balances for an ombrotrophic bog and a minerotrophic fen in northern Minnesota

    Brian H. Hill; Terri M. Jicha; LaRae L.P. Lehto; Colleen M. Elonen; Stephen D. Sebestyen; Randy Kolka


    Wecompared nitrogen (N) storage and flux in soils froman ombrotrophic bogwith that of a minerotrophic fen to quantify the differences in N cycling between these two peatlands types in northernMinnesota (USA). Precipitation, atmospheric deposition, and bog and fen outflowswere analyzed for nitrogen species. Upland and peatland soil sampleswere analyzed for N content,...

  19. Origin of the tertiary red beds in the Northern part of the Duero Basin (Spain), II. Composition and genesis

    Mabesoone, J.M.


    In this second paper the red beds outcropping in the northern part of the Duero basin have been treated regarding their mineral and pebble composition, chemical parameters, and surface textures of quartz sand grains, taking as basis the results reported in the first paper. These deposits originate f

  20. Dry and wet deposition of polycyclic aromatic hydrocarbons and comparison with typical media in urban system of Shanghai, China

    Wang, Qing; Liu, Min; Li, Ye; Liu, Yankun; Li, Shuwen; Ge, Rongrong


    Polycyclic aromatic hydrocarbons (PAHs) were studied in dry and wet deposition samples collected at urban and suburban sites of Shanghai, China from April 2014 to April 2015. Average wet deposition fluxes of PAHs were higher than dry deposition (62.6 ± 41.5 vs. 26.9 ± 14.4 μg/m2/day). However, dry deposition removed more PAHs than wet deposition (69% vs. 31%) due to much shorter durations of wet deposition. The highest dry and wet deposition fluxes were in fall and winter, respectively. The highest amount of dry deposition was in fall and the highest of wet deposition was in summer. The contribution of wet deposition to total deposited PAHs in Shanghai, East China was higher than that in northern China and lower than that in southern China. The difference can be explained by both precipitation amount and removal efficiency (washout ratio). Average dry deposition velocity and washout ratio of particle-associated PAHs were 5.2 cm/s and 5.8 × 104, respectively. Four sources of deposited PAHs were unraveled by positive matrix factorization (PMF) model: traffic, coal combustion, coking and volatilization, contributing 28.7%, 24.6%, 23.7% and 23.0%, respectively. More contribution of traffic and less coal combustion and volatilization were found at urban than at suburban site. As the connection between aerosol and surface soil, deposition had a different PAH composition from those in the two sides, containing more low MW PAHs. That arose the concern that dry deposition velocity and particle washout ratio could be overestimated if coarse particulate matter was excluded from the calculation. Although deposition has been considered as the predominant pathway of PAHs to urban surface system, the PAH composition in street dust differed drastically from that in deposition. This indicated that other sources (e.g. traffic) in urban system could have a greater contribution to PAHs than it had been identified in deposition samples.

  1. Glacial and Quaternary geology of the northern Yellowstone area, Montana and Wyoming

    Pierce, Kenneth L.; Licciardi, Joseph M.; Krause, Teresa R.; Whitlock, Cathy


    This field guide focuses on the glacial geology and paleoecology beginning in the Paradise Valley and progressing southward into northern Yellowstone National Park. During the last (Pinedale) glaciation, the northern Yellowstone outlet glacier flowed out of Yellowstone Park and down the Yellowstone River Valley into the Paradise Valley. The field trip will traverse the following Pinedale glacial sequence: (1) deposition of the Eightmile terminal moraines and outwash 16.5 ± 1.4 10Be ka in the Paradise Valley; (2) glacial recession of ~8 km and deposition of the Chico moraines and outwash 16.1 ± 1.7 10Be ka; (3) glacial recession of 45 km to near the northern Yellowstone boundary and moraine deposition during the Deckard Flats readjustment 14.2 ± 1.2 10Be ka; and (4) glacial recession of ~37 km and deposition of the Junction Butte moraines 15.2 ± 1.3 10Be ka (this age is a little too old based on the stratigraphic sequence). Yellowstone's northern range of sagebrush-grasslands and bison, elk, wolf, and bear inhabitants is founded on glacial moraines, sub-glacial till, and outwash deposited during the last glaciation. Floods released from glacially dammed lakes and a landslide-dammed lake punctuate this record. The glacial geologic reconstruction was evaluated by calculation of basal shear stress, and yielded the following values for flow pattern in plan view: strongly converging—1.21 ± 0.12 bars (n = 15); nearly uniform—1.04 ± 0.16 bars (n = 11); and strongly diverging—0.84 ± 0.14 bars (n = 16). Reconstructed mass balance yielded accumulation and ablation each of ~3 km3/yr, with glacial movement near the equilibrium line altitude dominated by basal sliding. Pollen and charcoal records from three lakes in northern Yellowstone provide information on the postglacial vegetation and fire history. Following glacial retreat, sparsely vegetated landscapes were colonized first by spruce parkland and then by closed subalpine forests. Regional fire activity

  2. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars

    Grotzinger, J.P.; Gupta, S.; Malin, M.C.; Rubin, D.M.; Schieber, J.; Siebach, K.; Sumner, D.Y.; Stack, K.M.; Vasavada, A.R.; Arvidson, R.E.; Calef, F.; Edgar, Lauren; Fischer, W.F.; Grant, J.A.; Griffes, J.L.; Kah, L.C.; Lamb, M.P.; Lewis, K.W.; Mangold, N.; Minitti, M.E.; Palucis, M.C.; Rice, M.; Williams, R.M.E.; Yingst, R.A.; Blake, D.; Blaney, D.; Conrad, P.; Crisp, J.A.; Dietrich, W.E.; Dromart, G.; Edgett, K.S.; Ewing, R.C.; Gellert, R.; Hurowitz, J.A.; Kocurek, G.; Mahaffy, P.G.; McBride, M.J.; McLennan, S.M.; Mischna, M.A.; Ming, D.; Milliken, R.E.; Newsom, H.; Oehler, D.; Parker, T.J.; Vaniman, D.; Wiens, R.C.; Wilson, S.A.


    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

  3. Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars.

    Grotzinger, J P; Gupta, S; Malin, M C; Rubin, D M; Schieber, J; Siebach, K; Sumner, D Y; Stack, K M; Vasavada, A R; Arvidson, R E; Calef, F; Edgar, L; Fischer, W F; Grant, J A; Griffes, J; Kah, L C; Lamb, M P; Lewis, K W; Mangold, N; Minitti, M E; Palucis, M; Rice, M; Williams, R M E; Yingst, R A; Blake, D; Blaney, D; Conrad, P; Crisp, J; Dietrich, W E; Dromart, G; Edgett, K S; Ewing, R C; Gellert, R; Hurowitz, J A; Kocurek, G; Mahaffy, P; McBride, M J; McLennan, S M; Mischna, M; Ming, D; Milliken, R; Newsom, H; Oehler, D; Parker, T J; Vaniman, D; Wiens, R C; Wilson, S A


    The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

  4. Dust deposition and ambient PM10 concentration in northwest China: spatial and temporal variability

    Zhang, Xiao-Xiao; Sharratt, Brenton; Chen, Xi; Wang, Zi-Fa; Liu, Lian-You; Guo, Yu-Hong; Li, Jie; Chen, Huan-Sheng; Yang, Wen-Yi


    Eolian dust transport and deposition are important geophysical processes which influence global bio-geochemical cycles. Currently, reliable deposition data are scarce in central and east Asia. Located at the boundary of central and east Asia, Xinjiang Province of northwestern China has long played a strategic role in cultural and economic trade between Asia and Europe. In this paper, we investigated the spatial distribution and temporal variation in dust deposition and ambient PM10 (particulate matter in aerodynamic diameter ≤ 10 µm) concentration from 2000 to 2013 in Xinjiang Province. This variation was assessed using environmental monitoring records from 14 stations in the province. Over the 14 years, annual average dust deposition across stations in the province ranged from 255.7 to 421.4 t km-2. Annual dust deposition was greater in southern Xinjiang (663.6 t km-2) than northern (147.8 t km-2) and eastern Xinjiang (194.9 t km-2). Annual average PM10 concentration across stations in the province varied from 100 to 196 µg m-3 and was 70, 115 and 239 µg m-3 in northern, eastern and southern Xinjiang, respectively. The highest annual dust deposition (1394.1 t km-2) and ambient PM10 concentration (352 µg m-3) were observed in Hotan, which is located in southern Xinjiang and at the southern boundary of the Taklamakan Desert. Dust deposition was more intense during the spring and summer than other seasons. PM10 was the main air pollutant that significantly influenced regional air quality. Annual average dust deposition increased logarithmically with ambient PM10 concentration (R2 ≥ 0.81). While the annual average dust storm frequency remained unchanged from 2000 to 2013, there was a positive relationship between dust storm days and dust deposition and PM10 concentration across stations. This study suggests that sand storms are a major factor affecting the temporal variability and spatial distribution of dust deposition in northwest China.

  5. Pteridophyta collected in Northern Nigeria and Northern Cameroon

    Jan kornaś


    Full Text Available 25 species of Pteridophyta were collected in Northern Nigeria (mainly the Lake Chad Basin and the Mandara Mts. and in the neighbouring parts of Cameroon. 11 of them have not been recorded previously from this area: Isoetes schweinfurthii A. Br. in Bak., Selaginella tenerrima A. Br. ex Kuhn, Ophioglossum gomenzianum Welw. ex A. Br., Marsilea coromandeliana Willd., M. distorta A. Br., M. nubica A. Br., M. subterranea Lepr. ex A. Br., Azolla africana Desv., Ceratopteris richardii Brogn., Adiantum capillus-veneris Linn., and Actiniopleris semiflabellata Pic. Ser.

  6. 新疆准噶尔北缘玉勒肯哈腊苏铜(钼)矿床流体包裹体和稳定同位素研究%Fluid inclusion and stable isotope study of Yulekenhalasu copper-(molybdenum) deposit in northern margin of Junggar, Xinjiang

    杨富全; 刘国仁; 秦纪华; 张志欣; 刘振江; 张立武; 魏广智; 刘锋; 耿新霞


    玉勒肯哈腊苏中型斑岩型铜(钼)矿主要赋存在闪长玢岩中,有少量矿化产在北塔山组火山岩及似斑状黑云母石英二长岩中.矿化呈细脉状、细脉-浸染状和浸染状.围岩蚀变主要为钾化、硅化、绢云母化、石膏化、磁铁矿化、绿泥石化、绿帘石化.矿床的形成经历了斑岩期、剪切变形期和表生期,铜和钼矿化主要形成于斑岩期的硫化物-钾硅酸盐阶段和辉钼矿阶段.石英和方解石中的流体包裹体可划分为H2 O-NaCl型和H2O-CO2(±CH4 /N2)-NaCl型.硫化物-钾硅酸盐阶段的成矿温度为141~500℃,主要集中在200~340℃;流体的ω(NaCleq)为2.96%~14.97%;流体的密度为0.60~ 0.98 g/cm3.碳酸盐阶段的流体以中-低温度(140~320℃)和低盐度[ω(NaCleq)为2.74%~10.61%]为特征.硫化物的δ34S值集中于-4.5‰~0.1‰,峰值为-3.5‰,表明硫来自深源岩浆.石英和方解石的δ18OSMOW值为9.1‰~13.2‰oo,δ18OH2O值为2.05‰~6.28‰,δD值为-120‰~ 97‰,表明主成矿阶段的成矿流体主要是岩浆水,混合有大气降水;碳酸盐阶段的流体主要为大气降水,混合有岩浆水.成矿时代为中泥盆世[(373.9±2.2 Ma)],成矿作用与闪长玢岩的侵入有关.温度和压力的降低导致流体沸腾,同时,水-岩交换反应、流体成分的改变等在铜钼成矿过程中起着主导作用.%The Yulekenhalasu medium-size porphyry copper-(molybdenum) deposit occurs in the diorite porphyry, with some mineralization also observed in the porphyroid biotite quartz monzonite and volcanic rocks of the Beitashan Formation. Mineralization occurs as veinlets, veinlet-disseminations and stockworks. Wall-rock altera tion is well developed, and mainly comprises K-feldspathization, biotitization, quartzification, sericitization, magnetitization, gypsification, chloritization, and epidotization. According to cutting relationships of the ore veins, mineral assemblages, paragenetic

  7. Diagenesis, provenance and depositional environments of the Bunter Sandstone Formation

    Olivarius, Mette; Weibel, Rikke; Friis, Henrik

    The Bunter Sandstone Formation in the northern North German Basin has large geothermal potential with high porosity and permeability (generally >15% and >100 mD, respectively) and with pore fluid temperatures that are adequate for geothermal energy production (c. 55–60˚C). A combined investigation...... of diagenesis, provenance and depositional environments is used to identify the reservoir rocks that possess the best quality. This is accomplished by integrating various methods including: seismic reflection data, sedimentological description of cores, mineral quantification by point counting, measurement...

  8. The Zeolite Deposit of Hekimhan in the Malatya Basin

    Önal, Mehmet; Depci, Tolga; Ceylan, Cigdem; Kizilkaya, Nilgun


    Zeolite deposits in the Malatya Basin which is formed of the Yüksekova Group were investigated in the present study. The zeolites were occurred in the two layers: the lower zeolite layer and the upper zeolite layer of the Sankiz Formation of Campanian-Maastrichtian age within the flysch like sediments at Hekimhan in the northern part of the Malatya Basin. Characterization studies of the zeolite samples were done by XRF, XRD and SEM images and the results showed that the main structures of the zeolites were clinoptilolite-(Cs), heulandite and calcite and the geological occurrences of zeolite is in marine environments.

  9. FDIC Summary of Deposits (SOD) Download File

    Federal Deposit Insurance Corporation — The FDIC's Summary of Deposits (SOD) download file contains deposit data for branches and offices of all FDIC-insured institutions. The Federal Deposit Insurance...

  10. Glacier ice in rock glaciers: a case study in the Vanoise Massif, Northern French Alps

    S. Monnier; C. Camerlynck; F. Rejiba; Kinnard, C.; Galibert, P.-Y.


    We investigated the Sachette rock glacier, Vanoise Massif, Northern French Alps, using former equilibrium line altitude reconstruction from glacial deposits, aerial photograph analysis, and ground-penetrating radar (GPR). The rock glacier is a young (probably 0.15–0.16 m ns−1) and reflectors having a dipping-syncline structure, typical of true glaciers. Consequently, the rock glacier structure is described as being constituted of ...

  11. Acid deposition in Asia: Emissions, deposition, and ecosystem effects

    Duan, Lei; Yu, Qian; Zhang, Qiang; Wang, Zifa; Pan, Yuepeng; Larssen, Thorjørn; Tang, Jie; Mulder, Jan


    We review and synthesize the current state of knowledge regarding acid deposition and its environmental effects across Asia. The extent and magnitude of acid deposition in Asia became apparent only about one decade after this issue was well described in Europe and North America. In addition to the temperate zone, much of eastern and southern Asia is situated in the tropics and subtropics, climate zones hitherto little studied with respect to the effects of high loads of acid deposition. Surface waters across Asia are generally not sensitive to the effects of acid deposition, whereas soils in some regions are sensitive to acidification due to low mineral weathering. However, soil acidification was largely neutralized by such processes as base cation deposition, nitrate (NO3-) denitrification, and sulfate (SO42-) adsorption. Accompanying the decrease in S deposition in recent years, N deposition is of increasing concern in Asia. The acidifying effect of N deposition may be more important than S deposition in well drained tropical/subtropical soils due to high SO42- adsorption. The risk of regional soil acidification is a major threat in Eastern Asia, indicated by critical load exceedance in large areas.

  12. The Northern Manitoba Mining Academy

    Alexandre, Paul


    The Northern Manitoba Mining Academy (NMMA, is a new educational institution located in Flin Flon, Manitoba. It is associated with the University College of the North and is specifically intended to serve the needs of the Northern Manitoban communities with regards to job creation by providing training in a variety of mining, construction, and exploration related areas. NMMA's mission is to provide innovative and responsible solutions for the creation of a knowledgeable, skilled, and sustainable workforce within a vibrant, mineral-rich resource industry. It facilitates strategic training initiatives and research activities in order to strengthen the social, economic, and environmental benefits of a robust mining and resources sector. In terms of education, NMMA offers its own programs, mostly short courses in health and safety, courses organized by the University College of the North (wilderness safety, prospecting, and exploration), and courses organized in association with provincial Industries-Based Safety Programs and Associations (a variety of construction-related trades). However, the programming is not limited to those courses already on the syllabus: the Academy operates on open-doors policy and welcomes people with their unique and diverse needs; it prides itself in its ability to tailor or create specific on-demand courses and deliver them locally in the North. The Northern Manitoba Mining Academy also provides access to its world-class facilities for field-based undergraduate courses, as well as graduate students and researchers doing field work. Full sample preparation facilities are offered to students and scientists in all natural and environmental sciences.

  13. Some characteristics of electrospark deposition

    Lesnjak, A. [Q-Techna, Krsko (Sierra Leone); Tusek, J. [Faculty of Mechanical Engineering, Ljubljana (Sierra Leone)


    The paper deals with some characteristics of electrospark deposition. A relevant device and the process are described, the material transfer is shown schematically, and the average droplet mass, the thickness of deposited layer, and the layer roughness are determined. Two types of substrate (tool steel, austenitic stainless steel), two types of shielding gas, (Ar, He), and three types of filler material, (WC, TiC, Stellite 6) were used. With some deposit, chemical analyses of deposit surfaces were performed and with some others through-thickness chemical analyses. Among the final conclusions the most important one is that the addition of a shielding gas results in a considerable increase in deposit quality. The device manufacturer, however, recommends deposition without the addition of a shielding gas. (orig.)

  14. Structural characteristics of chalcopyrite from a Cu(Au) ore deposit in the Carajás Mineral Province, Brazil

    Ribeiro, Andreza Aparecida; Lima, Diana Quintão; Duarte, Hélio Anderson; Murad, Enver; Pereira, Márcio César; de Freitas Suita, Marcos Tadeu; Ardisson, José Domingos; Fabris, José Domingos


    Mössbauer spectra and X-ray diffraction data show a chalcopyrite from the Cristalino Cu(Au) deposit in the Carajás Mineral Province in northern Brazil to consist of a single, tetragonal phase. This is in stark contrast to a previously described chalcopyrite from the Camaquã copper mine in southern Brazil, obviously reflecting differences in mineral (and thus ore deposit) genesis.

  15. The deposit size frequency method for estimating undiscovered uranium deposits

    McCammon, R.B.; Finch, W.I.


    The deposit size frequency (DSF) method has been developed as a generalization of the method that was used in the National Uranium Resource Evaluation (NURE) program to estimate the uranium endowment of the United States. The DSF method overcomes difficulties encountered during the NURE program when geologists were asked to provide subjective estimates of (1) the endowed fraction of an area judged favorable (factor F) for the occurrence of undiscovered uranium deposits and (2) the tons of endowed rock per unit area (factor T) within the endowed fraction of the favorable area. Because the magnitudes of factors F and T were unfamiliar to nearly all of the geologists, most geologists responded by estimating the number of undiscovered deposits likely to occur within the favorable area and the average size of these deposits. The DSF method combines factors F and T into a single factor (F??T) that represents the tons of endowed rock per unit area of the undiscovered deposits within the favorable area. Factor F??T, provided by the geologist, is the estimated number of undiscovered deposits per unit area in each of a number of specified deposit-size classes. The number of deposit-size classes and the size interval of each class are based on the data collected from the deposits in known (control) areas. The DSF method affords greater latitude in making subjective estimates than the NURE method and emphasizes more of the everyday experience of exploration geologists. Using the DSF method, new assessments have been made for the "young, organic-rich" surficial uranium deposits in Washington and idaho and for the solution-collapse breccia pipe uranium deposits in the Grand Canyon region in Arizona and adjacent Utah. ?? 1993 Oxford University Press.

  16. Momentum Deposition in Curvilinear Coordinates

    Cleveland, Mathew Allen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Lowrie, Robert Byron [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rockefeller, Gabriel M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Thompson, Kelly Glen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Wollaber, Allan Benton [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    The momentum imparted into a material by thermal radiation deposition is an important physical process in astrophysics and inertial confinement fusion (ICF) simulations. In recent work we presented a new method of evaluating momentum deposition that relies on the combination of a time-averaged approximation and a numerical integration scheme. This approach robustly and efficiently evaluates the momentum deposition in spherical geometry. Future work will look to extend this approach to 2D cylindrical geometries.

  17. Northern Manitoba, northern Saskatchewan, and the Saskatchewan River Delta: Waterfowl production survey: 2000

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the Waterfowl Production and Habitat Survey for northern Manitoba, northern Saskatchewan, and the Saskatchewan River Delta during 2000. The...

  18. Waterfowl production survey: Northern Saskatchewan, northern Manitoba, Saskatchewan River Delta: July 10-22, 1973

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the Waterfowl Production and Habitat Survey for northern Saskatchewan, northern Manitoba, and the Saskatchewan River Delta during 1973. The...

  19. Waterfowl breeding population survey: Northern Saskatchewan, northern Manitoba and western Ontario: May-June 1959

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the Waterfowl Breeding Population and Habitat Survey for northern Saskatchewan, northern Manitoba, and western Ontario during 1959. The...

  20. Northern Manitoba, northern Saskatchewan, and the Saskatchewan River Delta: Waterfowl production survey: 1993

    US Fish and Wildlife Service, Department of the Interior — This report summarizes the Waterfowl Production and Habitat Survey for northern Manitoba, northern Saskatchewan, and the Saskatchewan River Delta during 1993. The...

  1. Giant Reed Distribution - Northern California [ds333

    California Department of Resources — The Arundo Distribution layer is a compilation of Arundo donax observations in northern and central California, obtained from several sources, including Arundo...

  2. Northern Alaska Landscape/Permafrost GIS Data

    Arctic Landscape Conservation Cooperative — This data set represents an updated Ecological Subsection Map for Northern Alaska. This update includes permafrost mapping to include the following new layers:...

  3. Northern pipelines : challenges and needs

    Dean, D.; Brownie, D. [ProLog Canada Inc., Calgary, AB (Canada); Fafara, R. [TransCanada PipeLines Ltd., Calgary, AB (Canada)


    Working Group 10 presented experiences acquired from the operation of pipeline systems in a northern environment. There are currently 3 pipelines operating north of 60, notably the Shiha gas pipeline near Fort Liard, the Ikhil gas pipeline in Inuvik and the Norman Wells oil pipeline. Each has its unique commissioning, operating and maintenance challenges, as well as specific training and logistical support requirements for the use of in-line inspection tools and other forms of integrity assessment. The effectiveness of cathodic protection systems in a permafrost northern environment was also discussed. It was noted that the delay of the Mackenzie Gas Pipeline Project by two to three years due to joint regulatory review may lead to resource constraints for the project as well as competition for already scarce human resources. The issue of a potential timing conflict with the Alaskan Pipeline Project was also addressed as well as land use issues for routing of supply roads. Integrity monitoring and assessment issues were outlined with reference to pipe soil interaction monitoring in discontinuous permafrost; south facing denuded slope stability; base lining projects; and reclamation issues. It was noted that automatic welding and inspection will increase productivity, while reducing the need for manual labour. In response to anticipated training needs, companies are planning to involve and train Aboriginal labour and will provide camp living conditions that will attract labour. tabs., figs.

  4. Isotopic composition of sulfate accumulations, Northern Calcareous Alps, Austria

    Bojar, Ana-Voica; Halas, Stanislaw; Bojar, Hans-Peter; Trembaczowski, Andrzej


    The Eastern Alps are characterised by the presence of three main tectonic units, such as the Lower, Middle and Upper Austroalpine, which overlie the Penninicum (Tollmann, 1977). The Upper Austroalpine unit consists of the Northern Calcareous Alps (NCA) overlying the Greywacke zone and corresponding to the Graz Paleozoic, Murau Paleozoic and the Gurktal Nappe. Evaporitic rocks are lacking in the later ones. The Northern Calcareous Alps are a detached fold and thrust belt. The sedimentation started in the Late Carboniferous or Early Permian, the age of the youngest sediments being Eocene. The NCA are divided into the Bajuvaric, Tirolic and Juvavic nappe complexes. The evaporitic Haselgebirge Formation occurs in connection with the Juvavic nappe complex at the base of the Tirolic units (Leitner et al., 2013). The Haselgebirge Formation consists mainly of salt, shales, gypsum and anhydrite and includes the oldest sediments of the NCA. The age of the Haselgebirge Formation, established by using spors and geochronological data, is Permian to Lower Triassic. For the Northern Calcareous Alps, the mineralogy of sulphate accumulations consists mainly of gypsum and anhydrite and subordonates of carbonates. The carbonates as magnesite, dolomite and calcite can be found either as singular crystals or as small accumulations within the hosting gypsum. Sulfides (sphalerite, galena, pyrite), sulfarsenides (enargite, baumhauerite) and native sulphur enrichments are known from several deposits (Kirchner, 1987; Postl, 1990). The investigated samples were selected from various gypsum and halite rich deposits of the Northern Calcareous Alps. A total of over 20 samples were investigated, and both oxygen and sulfur isotopic composition were determined for anhydrite, gyps, polyhalite, blödite and langbeinite. The sulfur isotopic values vary between 10.1 to 14 ‰ (CDT), with three values higher than 14 ‰. The Oxygen isotopic values show a range from 9 to 23 ‰ (SMOW). The sulfur

  5. Enhanced nitrogen deposition over China

    Liu, Xuejun; Zhang, Ying; Han, Wenxuan; Tang, Aohan; Shen, Jianlin; Cui, Zhenling; Christie, Peter; Zhang, Fusuo [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Vitousek, Peter [Department of Biology, Stanford University, Stanford, California 94305 (United States); Erisman, Jan Willem [VU University Amsterdam, 1081 HV Amsterdam (Netherlands); Goulding, Keith [The Sustainable Soils and Grassland Systems Department, Rothamsted Research, Harpenden AL5 2JQ (United Kingdom); Fangmeier, Andreas [Institute of Landscape and Plant Ecology, University of Hohenheim, 70593 Stuttgart (Germany)


    China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen. These emissions result in the deposition of atmospheric nitrogen (N) in terrestrial and aquatic ecosystems, with implications for human and ecosystem health, greenhouse gas balances and biological diversity. However, information on the magnitude and environmental impact of N deposition in China is limited. Here we use nationwide data sets on bulk N deposition, plant foliar N and crop N uptake (from long-term unfertilized soils) to evaluate N deposition dynamics and their effect on ecosystems across China between 1980 and 2010. We find that the average annual bulk deposition of N increased by approximately 8 kilograms of nitrogen per hectare (P < 0.001) between the 1980s (13.2 kilograms of nitrogen per hectare) and the 2000s (21.1 kilograms of nitrogen per hectare). Nitrogen deposition rates in the industrialized and agriculturally intensified regions of China are as high as the peak levels of deposition in northwestern Europe in the 1980s, before the introduction of mitigation measures. Nitrogen from ammonium (NH4+) is the dominant form of N in bulk deposition, but the rate of increase is largest for deposition of N from nitrate (NO3-), in agreement with decreased ratios of NH3 to NOx emissions since 1980. We also find that the impact of N deposition on Chinese ecosystems includes significantly increased plant foliar N concentrations in natural and semi-natural (that is, non-agricultural) ecosystems and increased crop N uptake from long-term-unfertilized croplands. China and other economies are facing a continuing challenge to reduce emissions of reactive nitrogen, N deposition and their negative effects on human health and the environment.

  6. The geology of the Florida land-pebble phosphate deposits

    Cathcart, J.B.; Blade, L.V.; Davidson, D.F.; Ketner, K.B.


    The land-pebble phosphate district is on the Gulf Coastal Plain of Florida. The phosphate deposits are in the Bone Valley formation, dated Pliocene by most writers. These strata overlie the Miocene Hawthorn formation and are overlain by consolidated sands 3 to 20 feet thick. The minable phosphate deposits, called “matrix” in the district, range from a featheredge to about 50 feet in thickness and consist of phosphatic pellets and nodules, quartz sand, and montmorillonitic clay in about equal proportions. Locally the matrix displays cross-bedding and horizontal laminations, but elsewhere it is structureless. The phosphorite particles, composed largely of carbonate-fluorapatite, range in diameter from less than 0.1 mm to about 60 cm and in P2O5 content from 30 to 36 percent. Coarse-pebble deposits, containing 30 to 34 percent P2O5 are found mainly on basement highs; and fine-pebble deposits, containing 32 to 36 percent P2O5 are, are found in basement lows. Deposits in the northern part of the field contain more phosphate particles and their P2O5 content is higher than those in the southern part. The upper part of the phosphatic strata is leached to an advanced degree and consists of quartz sand and clay-sized particules of pseudowavellite and wavellite. The leached zone ranges in thickness from a featheredge to 60 feet. The origin of the land-pebble deposits is incompletely known. Possible modes of origin are a residuum of Miocene age, or a reworked residuum of Pliocene or Quaternary age.

  7. Assessment of metallic mineral resources in the Humboldt River Basin, Northern Nevada, with a section on Platinum-Group-Element (PGE) Potential of the Humboldt Mafic Complex

    Wallace, Alan R.; Ludington, Steve; Mihalasky, Mark J.; Peters, Stephen G.; Theodore, Ted G.; Ponce, David A.; John, David A.; and Berger, Byron R.; Zientek, Michael L.; Sidder, Gary B.; Zierenberg, Robert A.


    The Humboldt River Basin is an arid to semiarid, internally drained basin that covers approximately 43,000 km2 in northern Nevada. The basin contains a wide variety of metallic and nonmetallic mineral deposits and occurrences, and, at various times, the area has been one of the Nation's leading or important producers of gold, silver, copper, mercury, and tungsten. Nevada currently (2003) is the third largest producer of gold in the world and the largest producer of silver in the United States. Current exploration for additional mineral deposits focuses on many areas in northern Nevada, including the Humboldt River Basin.

  8. Nitrogen deposition in a southern hemisphere biodiversity hotspot within and surrounding Cape Town, South Africa

    Angstmann, J. L.; Hall, S.; February, E.; West, A. G.; Allsopp, N.; Bond, W.


    Anthropogenic nitrogen (N) emissions have increased dramatically since the agricultural and industrial revolutions leading to N deposition in the northern hemisphere that is estimated to be an order of magnitude greater than preindustrial fluxes. N deposition rates of 5-15 kg N ha-1 yr-1 in Europe and N. America decrease plant species diversity, increase invasive species, and lead to eutrophication of surface waters. The southern hemisphere is home to over 50% of the world's biodiversity hotspots, including the 90,000 km2 Cape Floristic Region which houses 9,030 vascular plant species, 69% of which are endemic. However, to date, N deposition rates in the southern hemisphere are highly uncertain, with global models of N deposition based upon sparse datasets at best. Many terrestrial systems, such as fynbos shrublands, are adapted to low N availability and exhibit high species diversity and endemism, rendering them susceptible to ecological changes from N deposition. In this research, we quantified the spatial and temporal distribution of wet and dry N deposition across 30 protected fynbos ecosystems within the urban airshed of Cape Town, South Africa. We predicted that 1) total inorganic N deposition varies predictably along the urban-rural gradient (highest near the city centre), 2) N deposition varies seasonally, with higher fluxes in the winter months when atmospheric stability causes a build-up of N gases in and around the city, and 3) total inorganic N deposition will exceed the critical load of 10-15 kg N ha-1 yr-1 for Mediterranean shrublands, past which negative ecosystem effects have been shown to occur. Estimates of N deposition based on NO2 concentrations within the city suggest that total N deposition ranges from 8-13 kg N ha-1 yr-1 . However, we show that N deposition measured by ion-exchange resin collectors is far less than expected, averaging less than 2 kg N ha-1 yr-1 (range 0.5 - 5.5 kg N ha-1 yr-1 ), and is is dominated by NO3-, suggesting

  9. Sources of metallogenic materials for Mayuan Pb-Zn deposit on northern margin of Yangtze Plate: Evidence from C, O, H, S, Pb and Sr isotope geochemistry%扬子陆块北缘马元铅锌矿床成矿物质来源探讨:来自C、O、H、S、Pb、Sr同位素地球化学的证据

    刘淑文; 刘玲芳; 高永宝; 戈晓红; 郑绪忠; 张海东; 王亮


    The newly-discovered Mayuan Pb-Zn deposit occurs in bedded and stratoid forms and lies in a structural zone of dolomite breccias in the Sinian Dengying Formation on the northern margin of Yangtze landmass. C, O, H, S, Pb and Sr isotope geochemistry was analyzed in this paper in order to understand comprehensively the source of the ore metals and ore fluids. The results show that δ13CpDB values of the hydrothermal gangue minerals calcite and dolomite are -4.24‰~0.93‰, δ 18OSMOW are 15.92‰~23.24 ‰ indicating that the CO2 in the ore-forming fluid was derived from the dissolution of Sinian carbonates. The δ ^SV-CDT values of sulfides are 12.94‰~ 19.4‰ and the δ34 values of barite are 32.2δ~33.48‰ suggesting that the sulfur should be derived from the in-situ thermochemical reduction of sulfates from the sedimentary strata. The206Pb/2O4Pb, 207Pb/ 204Pb and 208Pb/^Pb values of the ores are in the range of 17.62~18.02, 15.49~15.63 and 37.57-38.35 respectively, and the normal Pb model ages are 418 ~ 662 Ma, so the ore metals were likely derived from the Sinian- Silurian strata. The δDp1 values of fluid inclusions in quartz display a range from - 92‰ to - 113‰ and the δ18OH2O o values calculated from 818O quartz values range from 6.03‰ to 12.73‰, if their formation temperature was 200℃ . These data indicate that the ore fluid was likely meteoric water or resulted from the reaction of organic matter with fluids from other sources, such as sea water and mixing water. The initial 87Sr/86Sr values of the ore-forming fluid are 0.70967~0.71146, higher than87Sr/86Sr values (0.70890~0.70945) of the host rock Sinian dolomite, implying that the ore-forming fluid probably migrated through the basement and the Paleozoic formation, and experienced water-rock reaction and isotope exchange between the ore fluid and the shale, clastic rocks and mudstones which had high 87Sr/86Sr values.%呈层状、似层状产于震旦系灯影组角砾状

  10. Mineral chemistry and isotope geochemistry of pyrite from the Heilangou gold deposit, Jiaodong Peninsula, Eastern China

    Yutong Yan; Na Zhang; Shengrong Li; Yongsheng Li


    The Heilangou gold deposit is located in the northern QixiaePenglai gold belt, which is one amongst the three large gold belts in the eastern Shandong Province (Jiaodong Peninsula). The ore body has formed within the Guojialing granite. In this study, we report the mineral chemistry of pyrite, as well as the S, Pb, and HeO isotope data of the Heilangou gold deposit. The chemical composition of pyrite in the Heilangou gold deposit indicates that the associated gold deposit is a typical magmatic hydrothermal one. The geochemical signatures and crystal structure of pyrite show that the ore-forming materials have been derived from the crust. The S isotope data of the pyrites from Heilangou show an overall range from 5.5 to 7.8&and an average of 6.7&. The S isotope data in this deposit are similar to those from the deposits in the Jiaodong gold belt. The Pb and S isotope variations are small in the Heilangou gold deposit. The 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb ratios are 17.4653e17.5958, 15.5105e15.5746 and 38.0749e38.4361, respec-tively. These data plot between the lower crust and the orogenic belt. The Pb isotope data in the Heilangou gold deposit are similar to those in the Linglong gold deposit. From the Qixia gold area (the Liukou and Majiayao gold deposits) to the MupingeRushan gold belt (Rushan gold deposit) to the ZhaoeYe gold belt (the Linglong, Sanshandao and Jiaojia gold deposits), the 206Pb/204Pb ratios progressively increase. The DeO isotope data obtained from quartz separates suggest that the ore-forming fluid was similar to a mixture of magmatic and meteoric waters. These results suggest that the ore-forming elements were primarily from source fluids derived from the lower crust.

  11. Variable temperature semiconductor film deposition

    Li, Xiaonan; Sheldon, Peter


    A method of depositing a semiconductor material on a substrate. The method sequentially comprises (a) providing the semiconductor material in a depositable state such as a vapor for deposition on the substrate; (b) depositing the semiconductor material on the substrate while heating the substrate to a first temperature sufficient to cause the semiconductor material to form a first film layer having a first grain size; (c) continually depositing the semiconductor material on the substrate while cooling the substrate to a second temperature sufficient to cause the semiconductor material to form a second film layer deposited on the first film layer and having a second grain size smaller than the first grain size; and (d) raising the substrate temperature, while either continuing or not continuing to deposit semiconductor material to form a third film layer, to thereby anneal the film layers into a single layer having favorable efficiency characteristics in photovoltaic applications. A preferred semiconductor material is cadmium telluride deposited on a glass/tin oxide substrate already having thereon a film layer of cadmium sulfide.

  12. A Micrometeorological Perspective on Deposition

    Jensen, Niels Otto


    An expression for the dry deposition velocity is given in terms of constant flux layer scaling. Numerical values of upper bounds on the deposition velocity is given for a typical situation. Some remarks are then offered on the relative merits of various ways in which the combined diffusion...

  13. A remote coal deposit revisited

    Bojesen-Kofoed, Jørgen A.; Kalkreuth, Wolfgang; Petersen, Henrik I.


    In 1908, members of the “Danmark Expedition” discovered a coal deposit in a very remote area in western Germania Land, close to the margin of the inland ice in northeast Greenland. The deposit was, however, neither sampled nor described, and was revisited in 2009 for the first time since its disc...

  14. Liquefier Dynamics in Fused Deposition

    Bellini, Anna; Guceri, Selcuk; Bertoldi, Maurizio


    Layered manufacturing (LM) is an evolution of rapid prototyping (RP) technology whereby a part is built in layers. Fused deposition modeling (FDM) is a particular LM technique in which each section is fabricated through vector style deposition of building blocks, called roads, which...

  15. Deposition and Resuspension of Particles

    Lengweiler, P.; Nielsen, Peter V.; Moser, A.

    A new experimental set-up to investigate the physical process of dust deposition and resuspension on and from surfaces is introduced. Dust deposition can reduce the airBorne dust concentration considerably. As a basis for developing methods to eliminate dust related problems in rooms, there is a ...

  16. Geotechnical Description of Mineral Deposits

    Sasvári Tibor


    Full Text Available Performing various mineral deposits extraction methods requires thorough knowledge of the rock masses` geomechanical parameters. In the geotechnical description of mineral deposits there is proposed a methodical approarch at the collection, registration, and evaluation of rock masses` geological properties for geotechnics being applied within the mining industry.

  17. Early Paleozoic paleogeography of the northern Gondwana margin: new evidence for Ordovician-Silurian glaciation

    Semtner, A.-K.; Klitzsch, E.


    During the Early Paleozoic, transgressions and the distribution of sedimentary facies on the northern Gondwana margin were controlled by a regional NNW-SSE to almost north-south striking structural relief. In Early Silurian times, a eustatic highstand enabled the sea to reach its maximum southward extent. The counterclockwise rotation of Gondwana during the Cambrian and Early Ordovician caused the northern Gondwana margin to shift from intertropical to southern polar latitudes in Ordovician times. Glacial and periglacial deposits are reported from many localities in Morocco, Algeria, Niger, Libya, Chad, Sudan, Jordan and Saudi Arabia. The Late Ordovician glaciation phase was followed by a period of a major glacioeustatic sea-level rise in the Early Silurian due to the retreat of the ice-cap. As a consequence of the decreasing water circulation in the basin centers (Central Arabia, Murzuk- and Ghadames basins), highly bituminous euxinic shales were deposited. These shales are considered to be the main source rock of Paleozoic oil and gas deposits in parts of Saudi Arabia, Libya and Algeria. The following regression in the southern parts of the Early Silurian sea was probably caused by a second glacial advance, which was mainly restricted to areas in Chad, Sudan and Niger. Evidence for glacial activity and fluvioglacial sedimentation is available from rocks overlying the basal Silurian shale in north-east Chad and north-west Sudan. The Early Silurian ice advance is considered to be responsible for the termination of euxinic shale deposition in the basin centers.

  18. Late Quaternary environments, vegetation and agriculture in northern New Zealand

    Horrocks, M.; Nichol, S. L.; Augustinus, P. C.; Barber, I. G.


    A sedimentological and plant microfossil history of the Late Quaternary is preserved in two sediment cores from early Polynesian ditch systems on southern Aupouri Peninsula. The study places human activities into a geomorphological and ecological context and allows comparison of natural and anthropogenic effects on two different geological settings: a floodplain and a relatively closed peat swamp. The data fill part of the current gap in the environmental record from northern New Zealand, namely MIS 3 (57k-26k yr BP). There is evidence for an increase in fire frequency in the region after 40k 14C yr BP, suggesting a shift to drier (and cooler) conditions. Pollen records show that conifer-hardwood forest dominated by podocarps (especially Dacrydium) prevailed prior to Polynesian arrival and deforestation within the last millennium, with Fuscopsora insignificant throughout. Both cores show sections with gaps in deposition or preservation, possible flood-stripping of peat during the pre-Holocene and mechanical disturbance by early Polynesians. The identification of prehistoric starch grains and other microremains of introduced Colocasia esculenta (taro) in both cores supports indirect evidence that the ditch systems of far northern New Zealand were used for the extensive cultivation of this crop. Copyright

  19. The Russian Northern Fleet. Sources of radioactive contamination

    Nilsen, T. [Bellona Foundation, Oslo (Norway); Kudrik, I. [Bellona Foundation Branch Office, Murmansk (Russian Federation); Nikitin, A. [Scientific Production Association ``Typhoon``, Obninsk (Russian Federation)


    The report describes the problems that the Russian Northern Fleet is experiencing with its nuclear powered vessels and with the storage of spent fuel and other nuclear wastes that the operation of these vessels generates. One of the most serious problems is the lack of regional storage and treatment facilities for radioactive waste. This waste is now deposited haphazardly throughout the various navy yards and bases. The establishment of a regional storage facility for spent fuel, radioactive reactor components, and liquid and solid nuclear waste is a necessary precondition for carrying out the decommissioning of nuclear submarines in an environmentally viable manner. A recurrent theme in the report is the lack of civilian control over the different Northern Fleet nuclear facilities. This leads to a disregard of international recommendations with regard to the handling of nuclear waste. Considerable effort has been made to provide comprehensive references in the report, making it clear that the authors sources of information have been open. By presenting this information the authors hope to contribute to increased insight and consequently to help realize necessary national and international measures. 93 refs.

  20. Late Pleistocene echimyid rodents (Rodentia, Hystricognathi from northern Brazil



    Full Text Available ABSTRACT Echimyidae (spiny rats, tree rats and the coypu is the most diverse family of extant South American hystricognath rodents (caviomorphs. Today, they live in tropical forests (Amazonian, coastal and Andean forests, occasionally in more open xeric habitats in the Cerrado and Caatinga of northern South America, and open areas across the southern portion of the continent (Myocastor. The Quaternary fossil record of this family remains poorly studied. Here, we describe the fossil echimyids found in karst deposits from southern Tocantins, northern Brazil. The analyzed specimens are assigned to Thrichomys sp., Makalata cf. didelphoides and Proechimys sp. This is the first time that a fossil of Makalata is reported. The Pleistocene record of echimyids from this area is represented by fragmentary remains, which hinders their determination at specific levels. The data reported here contributes to the understanding of the ancient diversity of rodents of this region, evidenced until now in other groups, such as the artiodactyls, cingulates, carnivores, marsupials, and squamate reptiles.

  1. Environmental overview of geothermal development: northern Nevada

    Slemmons, D.B.; Stroh, J.M.; Whitney, R.A. (eds.)


    Regional environmental problems and issues associated with geothermal development in northern Nevada are studied to facilitate environmental assessment of potential geothermal resources. The various issues discussed are: environmental geology, seismicity of northern Nevada, hydrology and water quality, air quality, Nevada ecosystems, noise effects, socio-economic impacts, and cultural resources and archeological values. (MHR)

  2. The Alcoholism Situation in a Northern City

    Martynov, M. Iu.; Martynova, D. Iu.


    Alcohol abuse in Russia has been increasing in recent years, especially in northern regions, as has the incidence of alcohol-related disease rates. A survey was conducted in Surgut (the Khanty-Mansi autonomous okrug) that determined the factors lending to the prevalence of alcohol abuse among the population of the northern city and assessed the…

  3. Rock avalanches clusters along the northern Chile coastal scarp

    Crosta, G. B.; Hermanns, R. L.; Dehls, J.; Lari, S.; Sepulveda, S.


    Rock avalanche clusters can be relevant indicators of the evolution of specific regions. They can be used to define: the type and intensity of triggering events, their recurrence and potential probability of occurrence, the progressive damage of the rock mass, the mechanisms of transport and deposition, as well as the environmental conditions at the time of occurrence. This paper tackles these subjects by analyzing two main clusters of rock avalanches (each event between 0.6 and 30 Mm3), separated by few kilometers and located along the coastal scarp of Northern Chile, south of Iquique. It lies, hence, within a seismic area characterized by a long seismic gap that ended on April 1st, 2014 with a Mw 8.2 earthquake. The scar position, high along the coastal cliff, supports seismic triggering for these clusters. The deposits' relative positions are used to obtain the sequence of rock avalanching events for each cluster. The progressive decrease of volume in the sequence of rock avalanches forming each cluster fits well the theoretical models for successive slope failures. These sequences seem to agree with those derived by dating the deposits with ages spanning between 4 kyr and 60 kyr. An average uplift rate of 0.2 mm/yr in the last 40 kyr is estimated for the coastal plain giving a further constraint to the rock avalanche deposition considering the absence of reworking of the deposits. Volume estimates and datings allow the estimation of an erosion rate contribution of about 0.098-0.112 mm km- 2 yr- 1 which is well comparable to values presented in the literature for earthquake induced landslides. We have carried out numerical modeling in order to analyze the mobility of the rock avalanches and examine the environmental conditions that controlled the runout. In doing so, we have considered the sequence of individual rock avalanches within the specific clusters, thus including in the models the confining effect caused by the presence of previous deposits. Bingham

  4. 20 CFR 703.207 - Kinds of negotiable securities that may be deposited; conditions of deposit; acceptance of deposits.


    ... amount fixed by the Office under the regulations in this part shall deposit any negotiable securities... deposited; conditions of deposit; acceptance of deposits. 703.207 Section 703.207 Employees' Benefits... AND RELATED STATUTES INSURANCE REGULATIONS Insurance Carrier Security Deposit Requirements § 703.207...

  5. Northern Security and Global Politics

    declining unipolarity - with a geopolitical shift to Asia, a reduced role for Europe in United States policy, and a more assertive Russia - will have on regional Nordic-Baltic security. Second, it takes a closer look at how the regional actors respond to these changes in their strategic environment...... to the increased international interest for the northern part of Europe: climate change resulting in ice melting in Greenland and the Arctic, and new resources and shipping routes opening up across the polar basin foremost among them. The world is no longer "unipolar" and not yet "multipolar," but perhaps "post....... This book will be of much interest to students of Nordic and Baltic politics, international security, foreign policy and IR....


    B. Theilen-Willige


    Full Text Available Based on LANDSAT ETM and Digital Elevation Model (DEM data derived by the Shuttle Radar Topography Mission (SRTM, 2000 of the coastal areas of Northern Venezuela were investigated in order to detect traces of earlier tsunami events. Digital image processing methods used to enhance LANDSAT ETM imageries and to produce morphometric maps (such as hillshade, slope, minimum and maximum curvature maps based on the SRTM DEM data contribute to the detection of morphologic traces that might be related to catastrophic tsunami events. These maps combined with various geodata such as seismotectonic data in a GIS environment allow the delineation of coastal regions with potential tsunami risk. The LANDSAT ETM imageries merged with digitally processed and enhanced SRTM data clearly indicate areas that might be prone by flooding in case of catastrophic tsunami events.




    Full Text Available The existence of Ra 226 is proved and measured by radiom emanation-method in waters and food products of North , North West and North – East of Iran. A total of 126 water, 249 food and 22 air samples have been examined. The concertration of Ra 226 in waters found to be 0.01 to 1.104 Pci/1 and in food products from 0.01 to Pci/gr. Ash.The amount found in due ranges from 0.003 to 0.227 Pci/m 3.It is concluded that the presence of higher than normal activity in some parts of Northern Iran is due to radiationanomalies in subsurface strata, where these mineral waters pass. Further investigattions are recommended.

  8. Succulent Euphorbias or northern Madagascar

    Rauh, Werner


    Full Text Available A survey is given or the Euphorbia species occurring in northern Madagascar. The systematic groups which shaw no affinities with African-Indian Euphorbia species. are discussed. One new combination: Euphorbia aureo-vindiflora (Rauh Rauh is proposed.

    Es presenta una revisió de les espècies suculentes del gènere Euphorbia L del nord de Madagascar. Es discuteixen els grups sistemàtics que no mostren afinitat amb les espècies indo-africanes d'Euphorbia. Es proposa una nova combinació: Euphorbia aureo-vitidiftora (Rauh Rauh.

  9. Anthropogenic N deposition slows decay by favoring bacterial metabolism: Insights from metagenomic analyses

    Zachary B. Freedman


    Full Text Available Litter decomposition is an enzymatically-complex process that is mediated by a diverse assemblage of saprophytic microorganisms. It is a globally important biogeochemical process that can be suppressed by anthropogenic N deposition. In a northern hardwood forest ecosystem located in Michigan, USA, 20 years of experimentally increased atmospheric N deposition has reduced forest floor decay and increased soil C storage. Here, we paired extracellular enzyme assays with shotgun metagenomics to assess if anthropogenic N deposition has altered the functional potential of microbial communities inhabiting decaying forest floor. Experimental N deposition significantly reduced the activity of extracellular enzymes mediating plant cell wall decay, which occurred concurrently with changes in the relative abundance of metagenomic functional gene pathways mediating the metabolism of carbohydrates, aromatic compounds, as well as microbial respiration. Moreover, experimental N deposition increased the relative abundance of 50 of the 60 gene pathways, the majority of which were associated with saprotrophic bacteria. Conversely, the relative abundance and composition of fungal genes mediating the metabolism of plant litter was not affected by experimental N deposition. Future rates of atmospheric N deposition have favored saprotrophic soil bacteria, whereas the metabolic potential of saprotrophic fungi appears resilient to this agent of environmental change. Results presented here provide evidence that changes in the functional capacity of saprotrophic soil microorganisms mediate how anthropogenic N deposition increases C storage in soil.

  10. Landscape-scale analysis of wetland sediment deposition from four tropical cyclone events.

    Andrew W Tweel

    Full Text Available Hurricanes Katrina, Rita, Gustav, and Ike deposited large quantities of sediment on coastal wetlands after making landfall in the northern Gulf of Mexico. We sampled sediments deposited on the wetland surface throughout the entire Louisiana and Texas depositional surfaces of Hurricanes Katrina, Rita, Gustav, and the Louisiana portion of Hurricane Ike. We used spatial interpolation to model the total amount and spatial distribution of inorganic sediment deposition from each storm. The sediment deposition on coastal wetlands was an estimated 68, 48, and 21 million metric tons from Hurricanes Katrina, Rita, and Gustav, respectively. The spatial distribution decreased in a similar manner with distance from the coast for all hurricanes, but the relationship with distance from the storm track was more variable between events. The southeast-facing Breton Sound estuary had significant storm-derived sediment deposition west of the storm track, whereas sediment deposition along the south-facing coastline occurred primarily east of the storm track. Sediment organic content, bulk density, and grain size also decreased significantly with distance from the coast, but were also more variable with respect to distance from the track. On average, eighty percent of the mineral deposition occurred within 20 km from the coast, and 58% was within 50 km of the track. These results highlight an important link between tropical cyclone events and coastal wetland sedimentation, and are useful in identifying a more complete sediment budget for coastal wetland soils.

  11. Landscape-scale analysis of wetland sediment deposition from four tropical cyclone events.

    Tweel, Andrew W; Turner, R Eugene


    Hurricanes Katrina, Rita, Gustav, and Ike deposited large quantities of sediment on coastal wetlands after making landfall in the northern Gulf of Mexico. We sampled sediments deposited on the wetland surface throughout the entire Louisiana and Texas depositional surfaces of Hurricanes Katrina, Rita, Gustav, and the Louisiana portion of Hurricane Ike. We used spatial interpolation to model the total amount and spatial distribution of inorganic sediment deposition from each storm. The sediment deposition on coastal wetlands was an estimated 68, 48, and 21 million metric tons from Hurricanes Katrina, Rita, and Gustav, respectively. The spatial distribution decreased in a similar manner with distance from the coast for all hurricanes, but the relationship with distance from the storm track was more variable between events. The southeast-facing Breton Sound estuary had significant storm-derived sediment deposition west of the storm track, whereas sediment deposition along the south-facing coastline occurred primarily east of the storm track. Sediment organic content, bulk density, and grain size also decreased significantly with distance from the coast, but were also more variable with respect to distance from the track. On average, eighty percent of the mineral deposition occurred within 20 km from the coast, and 58% was within 50 km of the track. These results highlight an important link between tropical cyclone events and coastal wetland sedimentation, and are useful in identifying a more complete sediment budget for coastal wetland soils.

  12. Wet deposition of mercury in the U.S. and Canada, 1996-2005: Results and analysis of the NADP mercury deposition network (MDN)

    Prestbo, Eric M.; Gay, David A.

    One of the most critical measurements needed to understand the biogeochemical cycle of mercury, and to verify atmospheric models, is the rate of mercury wet-deposition. The Mercury Deposition Network (MDN) operates sites across North America to monitor total mercury in wet-deposition. MDN's primary goal is to provide both spatial and temporal continental-scale observations of mercury wet-deposition fluxes to support researchers, modelers, policy-makers and the public interest. MDN represents the only continental-scale mercury deposition database with a >10-year record of continuous values. This study provides analysis and interpretation of MDN observations at 10 years (1996-2005) with an emphasis on investigating whether rigorous, statistically-significant temporal trends and spatial patterns were present and where they occurred. Wet deposition of mercury ranges from more than 25 μg m -2 yr in south Florida to less than 3 μg m -2 yr in northern California. Volume-weighted total mercury concentrations are statistically different between defined regions overall (Southeast ≈ Midwest > Ohio River > Northeast), with the highest in Florida, Minnesota, and several Southwest locations (10-16 ng L -1). Total mercury wet-deposition is significantly different between defined regions (Southeast > Ohio River > Midwest > Northeast). Mercury deposition is strongly seasonal in eastern North America. The average mercury concentration is about two times higher in summer than in winter, and the average deposition is approximately more than three times greater in summer than in winter. Forty-eight sites with validated datasets of five years or more were tested for trends using the non-parametric seasonal Kendall trend test. Significant decreasing mercury wet-deposition concentration trends were found at about half of the sites, particularly across Pennsylvania and extending up through the Northeast.

  13. Magmatic sulfide-rich nickel-copper deposits related to picrite and (or) tholeiitic basalt dike-sill complexes-A preliminary deposit model

    Schulz, Klaus J.; Chandler, Val W.; Nicholson, Suzanne W.; Piatak, Nadine M.; Seal, Robert R., II; Woodruff, Laurel G.; Zientek, Michael L.


    Magmatic sulfide deposits containing nickel (Ni) and copper (Cu), with or without (?) platinum-group elements (PGEs), account for approximately 60 percent of the world's Ni production and are active exploration targets in the United States and elsewhere. On the basis of their principal metal production, magmatic sulfide deposits in mafic rocks can be divided into two major types: those that are sulfide-rich, typically with 10 to 90 percent sulfide minerals, and have economic value primarily because of their Ni and Cu contents; and those that are sulfide-poor, typically with 0.5 to 5 percent sulfide minerals, and are exploited principally for PGE. Because the purpose of this deposit model is to facilitate the assessment for undiscovered, potentially economic magmatic Ni-Cu?PGE sulfide deposits in the United States, it addresses only those deposits of economic significance that are likely to occur in the United States on the basis of known geology. Thus, this model focuses on deposits hosted by small- to medium-sized mafic and (or) ultramafic dikes and sills that are related to picrite and tholeiitic basalt magmatic systems generally emplaced in continental settings as a component of large igneous provinces (LIPs). World-class examples (those containing greater than 1 million tons Ni) of this deposit type include deposits at Noril'sk-Talnakh (Russia), Jinchuan (China), Pechenga (Russia), Voisey's Bay (Canada), and Kabanga (Tanzania). In the United States, this deposit type is represented by the Eagle deposit in northern Michigan, currently under development by Kennecott Minerals.

  14. Modelling the long-term soil response to atmospheric deposition at intensively monitored forest plots in Europe

    Reinds, G.J.; Posch, M.; Vries, de W.


    The dynamic soil chemistry model SMART was applied to 121 intensive forest monitoring plots (mainly located in western and northern Europe) for which both element input (deposition) and element concentrations in the soil solution were available. After calibration of poorly known parameters, the mode

  15. The Montesbelos mass-flow (southern Amazonian craton, Brazil): a Paleoproterozoic volcanic debris avalanche deposit?

    Roverato, M.


    The present contribution documents the extremely well-preserved Paleoproterozoic architecture of the Montesbelos breccia (named here for the first time), which is interpreted as a rare example of a subaerial paleoproterozoic (>1.85 Ga) granular-dominated mass-flow deposit, few of which are recorded in the literature. Montesbelos deposit is part of the andesitic Sobreiro Formation located in the São Felix do Xingu region, southern Amazonian craton, northern Brazil. The large volume, high variability of textural features, presence of broken clasts, angular low sphericity fragments, mono- to heterolithic character, and the size of the outcrops point to a volcanic debris avalanche flow. Fluviatile sandy material and debris flows are associated with the deposit as a result of post-depositional reworking processes.

  16. Atrazine and terbutryn degradation in deposits from groundwater environment within the boreal region in Lahti, Finland.

    Talja, K Marja; Kaukonen, Sanna; Kilpi-Koski, Johanna; Malin, Ismo; Kairesalo, Timo; Romantschuk, Martin; Tuominen, Jari; Kontro, Merja H


    The degradation of pesticides atrazine and terbutryn was investigated under aerobic and anaerobic conditions in the northern boreal region subsurface deposits and sterilized controls from the depths of 6.3-21.0 m below the surface and 1.2-16.9 m below the groundwater table. During 1.3-1.7 years of laboratory incubation, atrazine degradation under aerobic conditions varied from rapid (half-live 38 days) to no degradation. Anaerobically, atrazine half-lives were 430-829 days. Organic matter, nitrogen, and lead in deposits correlated positively with the atrazine concentration in groundwater. Aerobic and anaerobic terbutryn half-lives were 193-644 and 266-400 days, respectively. Microbial aerobic atrazine and terbutryn degradation was confirmed in the deep deposits near the water table. Under aerobic conditions, the high amounts of Cr, Mn, Ni, and Zn in deposits decreased the chemical degradation of terbutryn.

  17. Trend of heavy metal and sulphur deposition in Finland from the 1980`s to 1990`s

    Kubin, E.; Lippo, H. [Forest Research Inst., Muhos (Finland)


    The moss technique to survey atmospheric heavy metal deposition was developed in Sweden in the late 1960`s. The surveys has extended from regional and national basis to cover all the Nordic countries in 1985, to northern Europe in 1990 and to a large part of Europe in 1990-92. National reports have also been published in many countries. The Forest Research Institute established a network of 3009 secret permanent monitoring sites all over the country in 1985 and 1986 for forest inventory and for monitoring the situation and changes in the forests. One essential part has been to study the effects of air pollution - including heavy metal and sulphur deposition on forests. Deposition has been monitored by collecting bioindicators and analysing the element concentrations. The purpose of this report is to show the trend of the heavy metal and sulphur deposition from the 1980`s to 1990`s and in addition to produce information about the emission sources. (author)

  18. Climate indexes of phytoliths from Homo erectus' cave deposits in Nanjing

    WANG Weiming; LIU Jinling; ZHOU Xiaodan


    A study on phytoliths and their climate indexes is carried out from Homo erectus' cave deposits in Hulu Cave, Nanjing. Evidence shows that phytolith assemblages of the cave deposits are dominated by the cold resistant types with a lower warm index, reflecting an overall cold inclined climate. This possibly connects the cave deposits with glacial climate to a great extent, which is in accordance with the northern fauna revealed by fossil mammals and temperate climate indicated by pollen assemblages. According to the distributional state of the phytoliths and their climate indexes on 4 profiles in the cave, it is revealed that profiles Ⅰ and Ⅱ display certain cold/warm, and dry/wet fluctuations; profile Ⅲ shows a humid and cold condition with the highest humility in the cave deposits; while profile Ⅳ indicates a possible quick accumulating process because of its stable climate indexes except for its bottom and top.

  19. Paleontology and paleoecology of guano deposits in Mammoth Cave, Kentucky, USA

    Widga, Chris; Colburn, Mona


    Bat guano deposits are common in the Mammoth Cave system (Kentucky, USA). Paleontological remains associated with these deposits are important records of local landscape changes. Recent excavations in the cave suggest that vertebrate remains in most of these deposits are dominated by Chiroptera. Although no extinct fauna were identified, the presence of a large roost of Tadarida brasiliensis in the Chief City section is beyond the northern extent of its current range suggesting that this deposit dates to an undetermined interglacial period. Stable isotope analyses of Tadarida-associated guano indicate a C3 prey signature characteristic of forested habitat. This was unexpected since this species is typically associated with open environments. Further ecomorphological analysis of wing shape trends in interglacial, Holocene, and historic-aged assemblages indicate that interglacial faunas are dominated by fast-flying, open-space taxa (T. brasiliensis) while late Holocene and Historic assemblages contain more taxa that utilized closed forest or forest gaps.


    Michael Volk; Cem Sarica


    As oil and gas production moves to deeper and colder water, subsea multiphase production systems become critical for economic feasibility. It will also become increasingly imperative to adequately identify the conditions for paraffin precipitation and predict paraffin deposition rates to optimize the design and operation of these multiphase production systems. Although several oil companies have paraffin deposition predictive capabilities for single-phase oil flow, these predictive capabilities are not suitable for the multiphase flow conditions encountered in most flowlines and wellbores. For deepwater applications in the Gulf of Mexico, it is likely that multiphase production streams consisting of crude oil, produced water and gas will be transported in a single multiphase pipeline to minimize capital cost and complexity at the mudline. Existing single-phase (crude oil) paraffin deposition predictive tools are clearly inadequate to accurately design these pipelines because they do not account for the second and third phases, namely, produced water and gas. The objective of this program is to utilize the current test facilities at The University of Tulsa, as well as member company expertise, to accomplish the following: enhance our understanding of paraffin deposition in single and two-phase (gas-oil) flows; conduct focused experiments to better understand various aspects of deposition physics; and, utilize knowledge gained from experimental modeling studies to enhance the computer programs developed in the previous JIP for predicting paraffin deposition in single and two-phase flow environments. These refined computer models will then be tested against field data from member company pipelines. The following deliverables are scheduled during the first three projects of the program: (1) Single-Phase Studies, with three different black oils, which will yield an enhanced computer code for predicting paraffin deposition in deepwater and surface pipelines. (2) Two

  1. Glacial atmospheric phosphorus deposition

    Kjær, Helle Astrid; Dallmayr, Remi; Gabrieli, Jacopo; Goto-Azuma, Kumiko; Hirabayashi, Motohiro; Svensson, Anders; Vallelonga, Paul


    Phosphorus in the atmosphere is poorly studied and thus not much is known about atmospheric phosphorus and phosphate transport and deposition changes over time, though it is well known that phosphorus can be a source of long-range nutrient transport, e.g. Saharan dust transported to the tropical forests of Brazil. In glacial times it has been speculated that transport of phosphorus from exposed shelves would increase the ocean productivity by wash out. However whether the exposed shelf would also increase the atmospheric load to more remote places has not been investigated. Polar ice cores offer a unique opportunity to study the atmospheric transport of aerosols on various timescales, from glacial-interglacial periods to recent anthropogenic influences. We have for the first time determined the atmospheric transport of phosphorus to the Arctic by means of ice core analysis. Both total and dissolved reactive phosphorus were measured to investigate current and past atmospheric transport of phosphorus to the Arctic. Results show that glacial cold stadials had increased atmospheric total phosphorus mass loads of 70 times higher than in the past century, while DRP was only increased by a factor of 14. In the recent period we find evidence of a phosphorus increase over the past 50 yrs in ice cores close to human occupation likely correlated to forest fires. References: Kjær, Helle Astrid, et al. "Continuous flow analysis method for determination of dissolved reactive phosphorus in ice cores." Environmental science & technology 47.21 (2013): 12325-12332. Kjær, Helle Astrid, et al. "Greenland ice cores constrain glacial atmospheric fluxes of phosphorus." Journal of Geophysical Research: Atmospheres120.20 (2015).

  2. Gas seepage in the Northern Adriatic Sea

    Matilde Ferrante, Giulia; Donda, Federica; Volpi, Valentina; Tinivella, Umberta


    In the Northern Adriatic Sea, the occurrence of gas seepage has been widely documented. However, the origin of seeping gas was not clearly constrained. Geophysical data with different scale of resolution, i.e. multichannel seismic profiles, CHIRP and morpho-bathymetry data collected in 2009 and 2014 by OGS reveal that several the gas-enriched fluid vents are deeply rooted. In fact, the entire Plio-Quaternary succession is characterized by widespread seismic anomalies represented by wipe-out zones and interpreted as gas chimneys. They commonly root at the base of the Pliocene sequence but also within the Paleogene succession, where they appear to be associated to deep-seated, Mesozoic-to-Paleogene faults. These chimneys originate and terminate at different stratigraphic levels; they also commonly reach the seafloor, where rock outcrops interpreted as authigenic carbonate deposits have been recognized. In places, gas is then capable to escape in the water column as shown by numerous gas flares. On going studies are addressed to: 1. re-examining the structural setting of the study area, in order to verify a possible structural control on chimney distribution and gas migration; 2. performing geochemical analysis on gas which have been sampled in some key emission points; 3. a quantitative analysis of some selected boreholes well logs (made available through the public VidePi database ( aimed to estimate the amount of gas present in sediments. This work presents the preliminary results regarding the latter aspect of our research. In a first instance, for each selected borehole the geophysical logs have been digitized. This procedure consists in a manual picking of curves, in a set system of reference. Static corrections for vertical offset are made at this stage. Logs are then divided by type and converted in common scales, amplifications and units. Every log is resampled in order to cut high frequencies not useful in the comparison with seismic data

  3. Geological classification of coal deposits

    Bretsnaidr, P.


    A new classification of coal deposits developed by the author is evaluated. The classification considers only selected factors which characterize a coal deposit. Each factor is described by a number of points ranging from 0 to 10. Geologic structure (deposits with one or more seams or with seam groups) is described using from 1 to 10 points. Secondary deformation of a coal deposit (e.g. tectonics) and hydrogeology (aquifers, filtration properties, etc.) are described using a 10 point scale. Coal seam structure (with or without partings) is characterized using 1 to 5 points. Coal seam thickness and its stability (4 thickness classes from 0.4 to 1.0 m, 1 to 3 m, 3 to 10 m and above 10 m) is described using 0 to 5 points. Coal seam quality (ash content, calorific value and coking properties) is described using 0 to 5 points. Other factors are characterized using a 10 point scale. Use of this deposit classification is explained using four examples: the Merkur surface mine (uncomplicated conditions), the Nosek surface mine (relatively complicated conditions), the Slany deposit (with complicated conditions) and the Jan Sverma deposit (with extremely complicated conditions).

  4. Stratabound and vein-type Pb-Zn mineralization at Las Canas, Chanarcillo Group, northern Chile; fluid inclusion microthermometry, and sulfur and lead isotope constraints

    Lieben, François Claude Serge; Moritz, Robert; Fontboté, Lluis; Chiaradia, Massimo


    The Las Canas stratabound Pb-Zn deposit, in northern Chile, is hosted by the Lower Cretaceous back-arc marine carbonate and subordinate andesitic volcanic and volcaniclastic rocks of the Chanarcillo Group, one hundred meters above a thick pile of magmatic arc-related basaltic to andesitic lavas of the Bandurrias Formation. The deposit is not obviously related to local intrusive rocks, which include an Upper Cretaceous granodiorite batholith and dacite dikes emplaced along normal faults. Strat...

  5. Maastrichtian-Early Eocene litho-biostratigraphy and palægeography of the northern Gulf of Suez region, Egypt

    Scheibner, C.; Marzouk, A. M.; Kuss, J.


    The Maastrichtian-Lower Eocene sediments on both sides of the northern Gulf of Suez can be subdivided into eight formal formations (including one group) and one informal formation that are described in detail. These lithostratigraphic units reflect three different environmental regimes of deposition or non-deposition. The first regime is characterised by uplift and erosion or non-deposition resulting mostly from the uplift of the Northern Galala/Wadi Araba structure, a branch of the Syrian Arc Foldbelt. The shallow water carbonate platform and slope deposits of the Late Campanian-Maastrichtian St Anthony Formation and the Paleocene-Lower Eocene Southern Galala and Garra Formations represent the second regime and are found north and south of the Northern Galala/Wadi Araba High. The third regime is represented by basinal chalks, marls and shales of the Maastrichtian Sudr Formation and of the Paleocene-Eocene Dakhla, Tarawan and Esna Formations, the Dakhla/Tarawan/Esna informal formation and the Thebes Group. The distribution and lateral interfingering of the above mentioned environmental regimes reflect different vertical movements, changing basin morphology, sea level changes and progradation of shallow water sediments and is illustrated on 11 palæogeographic maps.

  6. Sea-level related resedimentation processes on the northern slope of Little Bahama Bank (Middle Pleistocene to Holocene)

    Lantzsch, H.; Roth, S.; Reijmer, J.J.G.


    Middle Pleistocene to Holocene sediment variations observed in a 26 metre long core taken during a cruise of the RV Marion Dufresne are presented. Core MD992202 was retrieved from the northern slope of Little Bahama Bank and provides an excellent example for sedimentation processes in a mid-slope....... These glacial to interglacial differences in mineralogy, grain-size distribution and organic content clearly show the impact of climatically controlled sea-level fluctuations on the sedimentation patterns of the northern slope of Little Bahama Bank. The coarser deposits (ii) occur mainly at the transitions from...

  7. 78 FR 11604 - Deposit Insurance Regulations; Definition of Insured Deposit


    ... States banks often operate foreign branches to provide banking, foreign currency, and payment services to... required to repay a deposit in a foreign branch if it cannot do so because of ``war, insurrection, or civil...

  8. TSUNAMI_DEPOSITS - Tsunami Deposits at Seaside, Oregon

    U.S. Geological Survey, Department of the Interior — This data set is a point shapefile representing tsunami deposits within the Seaside, Oregon region obtained by Brooke Fiedorowicz and Curt Peterson in 1997 and Bruce...

  9. 76 FR 21265 - Interest on Deposits; Deposit Insurance Coverage


    ... in the subject line of the message. Mail: Robert E. Feldman, Executive Secretary, Attention: Comments... Deposit Insurance Corporation. Robert E. Feldman, Executive Secretary. BILLING CODE 6714-01-P...

  10. TSUNAMI_DEPOSITS - Tsunami Deposits at Seaside, Oregon

    U.S. Geological Survey, Department of the Interior — This data set is a point shapefile representing tsunami deposits within the Seaside, Oregon region obtained by Brooke Fiedorowicz and Curt Peterson in 1997 and Bruce...

  11. Middle Cretaceous dinosaur assemblages from northern Brazil and northern Africa and their implications for northern Gondwanan composition

    Candeiro, Carlos Roberto A.


    Dinosaurs are one of the most dominant groups in Cretaceous reptilian faunas. A summary of their record in northern Brazil and northern Africa during the middle of the Cretaceous Period (Aptian-Cenomanian) is presented here. Dinosaurs are represented by 32 species (three ornithischians, six sauropods and 23 theropods) from Brazil, Egypt, Lybia, Morocco, Niger, Sudan and Tunisia. These dinosaur assemblages provide fundamental data about distribution and composition of sauropods and theropods in northern Gondwana during the middle of the Cretaceous Period and confirm these assemblages to be among the most important dinosaur faunas in the north Gondwana areas.

  12. Lime-mud layers in high-energy tidal channels: a record of hurricane deposition

    Shinn, E.A.; Steinen, R.P.; Dill, R.F.; Major, R.


    During or immediately following the transit of Hurricane Andrew (August 23-24, 1992) across the northern part of the Great Bahama Bank, thin laminated beds of carbonate mud were deposited in high-energy subtidal channels (4 m depth) through the ooid shoals of south Cat Cay and Joulters Cays. Thicker, more cohesive (and therefore older) mud beds and angular mud fragments associated with ooids from Joulters Cays have similar characteristics but lack fresh plant fragments. We infer that these older beds were similarly deposited and thus record the passage of previous hurricanes or tropical storms. -from Authors

  13. Geology, Geochemistry and Minerogenesis of the Shijuligou Zinc-Copper Deposit in Gansu, China

    LI Wenyuan; DENG Jun; GAO Yongbao; GUO Zhouping; ZHANG Zhaowei; SONG Zhongbao


    The Shijuligou deposit was separated by an arcuate ductile shear zone cross the center of the deposit region, resulting in the difference between the southern and northern ore bodies. The lead (Pb) isotopic data of ores of the Shijuligou copper deposit have averages of ~(206)Pb/~(204)Pb, ~(207)Pb/~(204)Pb, and ~(208)Pb/~(204)Pb in 17.634, 15.444, and 37.312, respectively. It has been shown that ore-forming metals originated from intrusive and extrusive rocks in the upper part of ophiolites. The sulfur isotopic data of pyrite and chalcopyrite in the northern part change from +7.61‰ to +8.09‰ and +4.95‰ to +8.88‰ in the southern part. Isotopes of δ~(18)O in the Shijuligou copper deposit are between +11.1‰ and +18.6‰, with the calculated δ~(18)O_(H_2O) at +0.65‰. It is suggested that the mineralized fluid is a mixture of magma fluid, meteorological water, and seawater through circulating and leaching metals from the volcanic rocks. The zircon uranium-lead (U-Pb) dating of gabbro is 457.9±1.2 Ma, and the lower crossing age of the discordant and concordia curves of pyroxene spilite of zircon is 454±15 Ma. It is indicated that the Shijuligou deposit formed in a new ocean crust (ophiolite) of the back-arc basin in the late Ordovician. Mineralization should occur in the intermittence period after strong volcanic activity, and the age should be the late Ordovician. Moreover, the mineralization of ophiolite-hosted massive sulfide deposits in the ancient orogenic belt of the late Ordovician in the northern Qilian Mountains was controlled by the primary fault/fracture, with the forming of a metallogenic hydrothermai system by a mixture of volcanic magma fluid and seawater, which circularly leached the metaliogenic metals from the volcanic rocks, resulting in their accumulation. The ore bodies were transformed with morphology and metallogeuic elements. Jasperoid is an important sign for prospecting such deposits. There were many island arcs in the continent of

  14. Atmospheric deposition 2000. NOVA 2003; Atmosfaerisk deposition 2000. NOVA 2003

    Ellermann, T.; Hertel, O.; Hovmand, M.F.; Kemp, K.; Skjoeth, C.A.


    This report presents measurements and calculations from the atmospheric part of NOVA 2003 and covers results for 2000. It summarises the main results concerning concentrations and depositions of nitrogen, phosphorus and sulphur compounds related to eutrophication and acidification. Depositions of atmospheric compounds to Danish marine waters as well as land surface are presented. Measurements: In 2000 the monitoring program consisted of eight stations where wet deposition of ammonium, nitrate, phosphate (semi quantitatively) and sulphate were measured using bulk precipitation samplers. Six of the stations had in addition measurements of atmospheric content of A, nitrogen, phosphorus, and sulphur compounds in gas and particulate phase carried out by use of filter pack samplers. Filters were analysed at the National Environmental Research Institute. Furthermore nitrogen dioxide were measured using nitrogen dioxide filter samplers and monitors. Model calculations: The measurements in the monitoring program were supplemented with model calculations of concentrations and depositions of nitrogen and sulphur compounds to Danish land surface, marine waters, fjords and bays using the ACDEP model (Atmospheric Chemistry and Deposition). The model is a so-called trajectory model and simulates the physical and chemical processes in the atmosphere using meteorological and emission data as input. The advantage of combining measurements with model calculations is that the strengths of both methods is obtained. Conclusions concerning: 1) actual concentration levels at the monitoring stations, 2) deposition at the monitoring stations, 3) seasonal variations and 4) long term trends in concentrations and depositions are mainly based on the direct measurements. These are furthermore used to validate the results of the model calculations. Calculations and conclusions concerning: 1) depositions to land surface and to the individual marine water, 2) contributions from different emission


    Branko Crnković


    Full Text Available The geology, petrographycal composition and properties of dimension stone deposits in Croatia are described. Dimension stone deposits in the conception of mobilistic view of the genesis and structure of Dinarides, as well as after stratigraphic units, are considered. Valuation of the dimension stones of the active quarries is exposed. The marketable categories of dimension stone in Croatia are different varietes of limestones and calcareous clastites, primarly of Cretaceous age, and to lesser degree of Jurassic and Paleogene. The greatest part of deposits is concentrated in the Adriatic carbonate platform or Adriaticum.

  16. Particle deposition in ventilation ducts

    Sippola, Mark Raymond [Univ. of California, Berkeley, CA (United States)


    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 μm were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on the

  17. Particle deposition in ventilation ducts

    Sippola, Mark R.


    Exposure to airborne particles is detrimental to human health and indoor exposures dominate total exposures for most people. The accidental or intentional release of aerosolized chemical and biological agents within or near a building can lead to exposures of building occupants to hazardous agents and costly building remediation. Particle deposition in heating, ventilation and air-conditioning (HVAC) systems may significantly influence exposures to particles indoors, diminish HVAC performance and lead to secondary pollutant release within buildings. This dissertation advances the understanding of particle behavior in HVAC systems and the fates of indoor particles by means of experiments and modeling. Laboratory experiments were conducted to quantify particle deposition rates in horizontal ventilation ducts using real HVAC materials. Particle deposition experiments were conducted in steel and internally insulated ducts at air speeds typically found in ventilation ducts, 2-9 m/s. Behaviors of monodisperse particles with diameters in the size range 1-16 {micro}m were investigated. Deposition rates were measured in straight ducts with a fully developed turbulent flow profile, straight ducts with a developing turbulent flow profile, in duct bends and at S-connector pieces located at duct junctions. In straight ducts with fully developed turbulence, experiments showed deposition rates to be highest at duct floors, intermediate at duct walls, and lowest at duct ceilings. Deposition rates to a given surface increased with an increase in particle size or air speed. Deposition was much higher in internally insulated ducts than in uninsulated steel ducts. In most cases, deposition in straight ducts with developing turbulence, in duct bends and at S-connectors at duct junctions was higher than in straight ducts with fully developed turbulence. Measured deposition rates were generally higher than predicted by published models. A model incorporating empirical equations based on



    <正>20082280 An Fang(School of Earth and Space Sciences,Peking University,Beijing 100871,China);Zhu Yongfeng Studies on Geology and Geochemistry of Alteration- Type Ore in Hatu Gold Deposit(Western Junggar),Xinjiang,NW China(Mineral Deposits,ISSN0258—7106,CN11—1965/ P,26(6),2007,p.621—633,7 illus.,2 tables,48 refs.,with English abstract) Key words:gold deposits,Junggar Basin 20082281 An Guobao(No.212 Geological Party,Gansu Bureau of Nuclear Geology,

  19. Northern European long term climate archives

    Hohl, Veronica [Stockholm Univ. (Sweden)


    The Swedish Nuclear Fuel and Waste Management Company is responsible for the management and disposal of Sweden's radioactive waste. It is intended to deposit the spent nuclear fuel in a deep geological repository. This repository shall keep the radiotoxic material separated from humans and the environment for extended periods, from decades to millennia and possibly to geological timescales. During this time perspective climate induced changes such as shore-level displacement and evolution of permafrost and ice sheets are expected to occur which may affect the repository. The possible occurrence, extent and duration of these long-term changes, are therefore of interest when considering the assessment of repository performance and safety. The main climate parameters determining both surface and subsurface conditions are temperature and precipitation. As a result of the last advance of the Weichselian ice sheet only few geological archives exist, which contain information on past climatic conditions in Sweden before c 16,000 years BP. The purpose of this literature review is to compile and evaluate available information from Scandinavian, Northern and Central European geological archives, which record climatic conditions during the Weichselian time period. The compilation provides paleotemperature data sets, which may be used to explore the possible evolution of periglacial permafrost in Sweden. This report is a synopsis of 22 publications detailing climatic and environmental changes during the Weichselian time period in Northwestern Europe based on quantified paleotemperature records. Some of the data is presented as temperature curves which were digitised specifically for this report. The time range covered by the different publications varies considerably. Only few authors dealt with the whole Weichselian period and the majority cover only a few thousand years. This however is not considered to influence the reliability of the archives. The reason for the

  20. A naturally-occurring 'cold earth' spot in Northern China.

    Niu, Fujun; Cheng, Guodong; Niu, Yonghong; Zhang, Mingyi; Luo, Jing; Lin, Zhanju


    Permafrost is determined to a large extent by the Earth's surface temperature, therefore it distributes mainly in high altitude and latitude regions. However, stable, warm (about -1 °C) permafrost occurs within a scree slope in northern China that is more than 600 km south of the southernmost limit of latitudinal permafrost on the Eurasian Continent. It is at an elevation of only 900 m above sea level (ASL). The area has a mean annual air temperature (MAAT) of 6 to 8 °C. Thermal processes of the scree slope, investigated through field monitoring and numerical simulation, showed that the permafrost is caused by winter air convection within the porous rock deposits and is stable as air convection does not occur in summer time. The deposit is covered by a 30-cm-thick peaty soil layer dated (carbon C-14) to between 1,000 to 1,600 years ago. The layer also contributes to the permafrost's existence due to the peat's thermal conductivity offset when frozen and thawed. The existence of permafrost under such warm climatic conditions confirms the effectiveness of using crushed rock layer as basement or slope cover to protect the warm permafrost subgrade of the recently-constructed Qinghai-Tibet Railway (QTR), even under the predicted climate warming conditions.

  1. Auriferous Quartz Veins from the Dongping Gold Deposit,NW Hebei Province and Metallogenesis—Fluid Inclusion Rb—Sr Isochron Evidence

    莫测辉; 王秀璋; 等


    The Dongping gold deposit,situated on the northern margin of the North China Platform,is a composite deposit composed of auriferous quartz vein-type and altered rock-type ore bodies.It is hosted in the inner contact zone of an alkaline intrusion which was intruded in to Archean metamorphic rocks and was formed not later than the Hercynian period.Auriferous quartz veins of the deposit are dated with the fluid inclusion Rb-Sr isochron method at 103±4Ma ,indicating that the gold deposit was formed in the Yenshanian period,86Sr/86Sr source tracing shows the ore-forming materials came dominantly from alkaline intrusions.These results combined with other isotope and REE data,suggest that the Dongping gold deposit is not a traditiolal magmatic hydrothermal deposit,but a reworked hydrothermal deposit related to heated and evolved meteoric water.

  2. Glacially induced stresses in sedimentary rocks of northern Poland

    Trzeciak, Maciej; Dąbrowski, Marcin


    During the Pleistocene large continental ice sheets developed in Scandinavia and North America. Ice-loading caused bending of the lithosphere and outward flow in the mantle. Glacial loading is one of the most prominent tectono-mechanical event in the geological history of northern Poland. The Pomeranian region was subjected several times to a load equivalent of more than 1 km of rocks, which led to severe increase in both vertical and horizontal stresses in the upper crustal rocks. During deglaciation a rapid decrease in vertical stress is observed, which leads to destabilization of the crust - most recent postglacial faults scarps in northern Sweden indicate glacially induced earthquakes of magnitude ~Mw8. The presence of the ice-sheet altered as well the near-surface thermal structure - thermal gradient inversion is still observable in NW Poland. The glacially related processes might have left an important mark in the sedimentary cover of northern Poland, especially with regard to fracture reopening, changes in stress state, and damage development. In the present study, we model lithospheric bending caused by glacial load, but our point of interest lies in the overlying sediments. Typical glacial isostatic studies model the response of (visco-) elastic lithosphere over viscoelastic or viscous asthenosphere subjected to external loads. In our model, we introduce viscoelastic sedimentary layers at the top of this stack and examine the stress relaxation patterns therein. As a case study for our modelling, we used geological profiles from northern Poland, near locality of Wejherowo, which are considered to have unconventional gas potential. The Paleozoic profile of this area is dominated by almost 1 km thick Silurian-Ordovician shale deposits, which are interbedded with thin and strong limestone layers. This sequence is underlain by Cambrian shales and sandstones, and finally at ~3 km depth - Precambrian crystalline rocks. Above the Silurian there are approximately

  3. Comment on "The Southern Ocean biological response to aeolian iron deposition".

    Boyd, Philip W; Mackie, Douglas


    Cassar et al. (Reports, 24 August 2007, p. 1067) proposed that aerosol-iron input enhances Southern Ocean export production. Their conclusion critically depends upon aerosol-iron modeling simulations not validated with iron-deposition data and dust dissolution rates based on Northern Hemisphere atmospheric chemical conditions (low pH). This diminishes the relevance of their findings and demonstrates that applying such models to this region is premature.

  4. Nitrogen deposition contributes to soil acidification in tropical ecosystems.

    Lu, Xiankai; Mao, Qinggong; Gilliam, Frank S; Luo, Yiqi; Mo, Jiangming


    Elevated anthropogenic nitrogen (N) deposition has greatly altered terrestrial ecosystem functioning, threatening ecosystem health via acidification and eutrophication in temperate and boreal forests across the northern hemisphere. However, response of forest soil acidification to N deposition has been less studied in humid tropics compared to other forest types. This study was designed to explore impacts of long-term N deposition on soil acidification processes in tropical forests. We have established a long-term N-deposition experiment in an N-rich lowland tropical forest of Southern China since 2002 with N addition as NH4 NO3 of 0, 50, 100 and 150 kg N ha(-1)  yr(-1) . We measured soil acidification status and element leaching in soil drainage solution after 6-year N addition. Results showed that our study site has been experiencing serious soil acidification and was quite acid-sensitive showing high acidification (pH(H2O) soil profiles. Long-term N addition significantly accelerated soil acidification, leading to depleted base cations and decreased BS, and further lowered ANC. However, N addition did not alter exchangeable Al(3+) , but increased cation exchange capacity (CEC). Nitrogen addition-induced increase in SOC is suggested to contribute to both higher CEC and lower pH. We further found that increased N addition greatly decreased soil solution pH at 20 cm depth, but not at 40 cm. Furthermore, there was no evidence that Al(3+) was leaching out from the deeper soils. These unique responses in tropical climate likely resulted from: exchangeable H(+) dominating changes of soil cation pool, an exhausted base cation pool, N-addition stimulating SOC production, and N saturation. Our results suggest that long-term N addition can contribute measurably to soil acidification, and that shortage of Ca and Mg should receive more attention than soil exchangeable Al in tropical forests with elevated N deposition in the future.

  5. Quaternary deposits in the Serra da Capivara National Park and surrounding area, Southeastern Piauí state, Brazil

    Kenitiro Suguio


    Full Text Available Serra da Capivara National Park and surrounding areas in Southeastern Piau State (Brazil were subjected to morphostratigraphical, sedimentological, and geochronological studies about superficial deposits in order to interpret quaternary paleoenvironmental events. The following sedimentary deposits associated with morphostructural units were identified: colluvial fans at Serra Branca Valley and Structural Staircases, and eluvial-colluvial deposits at Reverse of the Cuesta. There are also colluvial and alluvial deposits outside Serra da Capivara National Park. Many colluvial and alluvial deposits are contemporaneous and indicate a semiarid climate. According to luminescence dating (thermoluminescence and optically stimulated luminescence, the present landscape evolution began around 436 51.5 ka when the Piau River deposited clayey sediments. From 296.55 46.95 ka to 116.3 19.52 ka, the fluvial channel likely exhibited a braided pattern and deposited sand and gravel bars. Penecontemporaneous sands and muds with ages ranging from 202.75 32.81 ka, 135 16.4 ka to 117 14.5 ka were deposited on Serra da Capivara National Park hillslopes. A colluviation episode occurred between 84.7 13.4 ka to 76.2 9.35 ka, which lacks correlatable alluvial deposits. In the Northern hemisphere last glacial maximum, the colluviation and alluviation processes intensified. These depositional processes likely occurred between 15.8 1.9 and 10.35 1.76 ka, during the Holocene-Pleistocene transition.

  6. Atomic layer deposition for semiconductors

    Hwang, Cheol Seong


    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  7. The zeolite deposits of Greece

    Stamatakis, M.G.; Hall, A.; Hein, J.R.


    Zeolites are present in altered pyroclastic rocks at many localities in Greece, and large deposits of potential economic interest are present in three areas: (1) the Evros region of the province of Thrace in the north-eastern part of the Greek mainland; (2) the islands of Kimolos and Poliegos in the western Aegean; and (3) the island of Samos in the eastern Aegean Sea. The deposits in Thrace are of Eocene-Oligocene age and are rich in heulandite and/or clinoptilolite. Those of Kimolos and Poliegos are mainly Quaternary and are rich in mordenite. Those of Samos are Miocene, and are rich in clinoptilolite and/or analcime. The deposits in Thrace are believed to have formed in an open hydrological system by the action of meteoric water, and those of the western Aegean islands in a similar way but under conditions of high heat flow, whereas the deposits in Samos were formed in a saline-alkaline lake.

  8. Bajada de rahue, province of neuquen, Argentina: an interstadial deposit in northern Patagonia

    Markgraf, Vera; Bradbury, J.P.; Fernandez, J.


    Pollen and diatom analyses of a radiocarbon dated lacustrine section in the temperate Andean region of Argentina (Rahue, Province Neuquen) suggest interglacial type climatic conditions between 27,000 and 33,000 yr B.P., with environments that resemble the modern conditions at the locality. This finding correlates with a woodland record from central Chile, interpreted as reflecting conditions substantially warmer and drier prior to 27,000 yr B.P. than during the following full-glacial period. It also appears to relate to the global paleoclimatic scheme derived from deep-sea records, suggesting interhemispheric synchroneity of such broad-scale palaeoclimatic phases. ?? 1986.

  9. Electrospark deposition for die repair

    J. Tušek


    Full Text Available The electrospark deposition is a process for surfacing of hard metal alloys, e.g. carbides and stellites, on the surfaces of new or old machine elements. In this process, a high current is conducted through an oscillating electrode and a substrate for a very short period of time. In the paper, the process is described and the thickness of deposited layer, chemical composition, dilution rate and the layer roughness are determined.

  10. Electrospark deposition for die repair

    J. Tušek; Kosec, L.; Lešnjak, A.; T. Muhič


    The electrospark deposition is a process for surfacing of hard metal alloys, e.g. carbides and stellites, on the surfaces of new or old machine elements. In this process, a high current is conducted through an oscillating electrode and a substrate for a very short period of time. In the paper, the process is described and the thickness of deposited layer, chemical composition, dilution rate and the layer roughness are determined.

  11. Thin Film Deposition Techniques (PVD)

    Steinbeiss, E.

    The most interesting materials for spin electronic devices are thin films of magnetic transition metals and magnetic perovskites, mainly the doped La-manganites [1] as well as several oxides and metals for passivating and contacting the magnetic films. The most suitable methods for the preparation of such films are the physical vapor deposition methods (PVD). Therefore this report will be restricted to these deposition methods.

  12. Submarine glaciated landscapes of central and northern British Columbia, Canada

    Shaw, John; Lintern, Gwyn


    Recent systematic multibeam sonar mapping and ground-truthing surveys in the fjords and coastal waters of central and northern British Columbia, Canada, provide information on glacial processes associated with the Cordilleran Ice Sheet, and also on postglacial processes that have strongly modified the glacial terrain. During the last glacial maximum, ice covered the Coast Range, except for nunataks. Convergent streamlined glacial landforms in the Strait of Georgia testify to a strong flow of ice towards the southeast, between Vancouver Island and the mainland. During ice retreat, thick deposits of acoustically stratified glaciomarine mud were deposited in glacially over deepened basins. Retreat through the Douglas Channel fjord system was punctuated by still stands, resulting in a series of submarine moraines. Postglacial processes have created a suite of landforms that mask the primary glacial terrain: 1) Fjord floors host thick deposits of acoustically transparent postglacial mud with highly variable distribution: banks up to 80-m thick are commonly adjacent to erosional zones with glaciomarine mud exposed at the seafloor; 2) In this region of high precipitation and snowpack melt, numerous cone-shaped Holocene fan deltas developed on the fjord sidewalls transport coarse sediment to the fjord floors. Larger deltas are developed at fjord heads, notably at Kitimat and Kildala; 3) Submarine slope failures in this tectonically active area have resulted in a suite of mass transport deposits on sidewalls and fjord floors. The very large submarine slope failures at Camano Sound and KitKat Inlet occurred on the steep, rear facets of large transverse moraines, and involved the failure of glaciomarine sediment that moved into deeper basins, perhaps as a retrogressive failure. The ages of these events are unknown, although the presence of postglacial mud in the slide scar at Caamano suggests that the event at that location occurred in the late glacial or early Holocene. Also

  13. Evolution of Irruputuncu volcano, Central Andes, northern Chile

    Rodríguez, I.; Roche, O.; Moune, S.; Aguilera, F.; Campos, E.; Pizarro, M.


    The Irruputuncu is an active volcano located in northern Chile within the Central Andean Volcanic Zone (CAVZ) and that has produced andesitic to trachy-andesitic magmas over the last ˜258 ± 49 ka. We report petrographical and geochemical data, new geochronological ages and for the first time a detailed geological map representing the eruptive products generated by the Irruputuncu volcano. The detailed study on the volcanic products allows us to establish a temporal evolution of the edifice. We propose that the Irruputuncu volcanic history can be divided in two stages, both dominated by effusive activity: Irruputuncu I and II. The oldest identified products that mark the beginning of Irruputuncu I are small-volume pyroclastic flow deposits generated during an explosive phase that may have been triggered by magma injection as suggested by mingling features in the clasts. This event was followed by generation of large lava flows and the edifice grew until destabilization of its SW flank through the generation of a debris avalanche, which ended Irruputuncu I. New effusive activity generated lavas flows to the NW at the beginning of Irruputuncu II. In the meantime, lava domes that grew in the summit were destabilized, as shown by two well-preserved block-and-ash flow deposits. The first phase of dome collapse, in particular, generated highly mobile pyroclastic flows that propagated up to ˜8 km from their source on gentle slopes as low as 11° in distal areas. The actual activity is characterized by deposition of sulfur and permanent gas emissions, producing a gas plume that reaches 200 m above the crater. The maximum volume of this volcanic system is of ˜4 km3, being one of the smallest active volcano of Central Andes.

  14. Reflection seismic imaging of shallow aquifers in Milano (northern Italy)

    Francese, R.; Zaja, A.; Giudici, M.; Schmitt, D.


    A high resolution P-wave seismic reflection survey was conducted in the Lambro park within the city of Milano (northern Italy). The objective of the survey was to image structure and stratigraphy of shallow late tertiary and quaternary deposits. This information is necessary to develop a comprehensive 3D hydrological model of the fresh water aquifers where the municipality drilled several production wells. The expected complexity of the acoustic framework and the urban environment with its complications created a challenging test site for the reflection technique. The aquifer system was targeted with a 2-D high resolution seismic reflection survey to outline its vertical and lateral dimensions to a depth of 150-200 m and to estimate some petrophysical properties of the depositional units. A 0.8-km CMP seismic line, with 1-m station spacing, was deployed to collect reflection data. The recording geometry was a 240-channel split spread array, with 6-m shot separation, resulting in a maximum of 20-fold dataset. A single 40-Hz geophone at each station location detected the incoming signals. Field records exhibit clear reflections although the signal to noise ratio is poor because of strong surface waves and severe disturbances from the nearby highway. Optimized FK and KL transforms were used to attenuate these coherent noises and to enhance the primary reflections from the main horizons. The data analysis was also assisted by forward modeling to guide the selection of the processing parameters. The seismic data have a good correlation thourhgout the section and most of the acoustic units show flat bedding. The boundaries of the three major depositional units are clearly resolved by the seismic images. The stacked section clearly indicates that reflection technique provides a powerful method to characterize aquifers, even in a very noisy environment like the urban areas.

  15. Northern Prairie Wildlife Research Center



    The Northern Prairie Wildlife Research Center (NPWRC) conducts integrated research to fulfill the Department of the Interior's responsibilities to the Nation's natural resources. Located on 600 acres along the James River Valley near Jamestown, North Dakota, the NPWRC develops and disseminates scientific information needed to understand, conserve, and wisely manage the Nation's biological resources. Research emphasis is primarily on midcontinental plant and animal species and ecosystems of the United States. During the center's 40-year history, its scientists have earned an international reputation for leadership and expertise on the biology of waterfowl and grassland birds, wetland ecology and classification, mammalian behavior and ecology, grassland ecosystems, and application of statistics and geographic information systems. To address current science challenges, NPWRC scientists collaborate with researchers from other U.S. Geological Survey centers and disciplines (Biology, Geography, Geology, and Water) and with biologists and managers in the Department of the Interior (DOI), other Federal agencies, State agencies, universities, and nongovernmental organizations. Expanding upon its scientific expertise and leadership, the NPWRC is moving in new directions, including invasive plant species, restoration of native habitats, carbon sequestration and marketing, and ungulate management on DOI lands.

  16. The ungulates of northern China

    Wu Jia-yan


    Full Text Available Presently, thirty five species of ungulates occur in northern China. Some species are threatened or endangered. There are three species of Equidae (E. przewalskii, E. hemionus, E. kiang, one of Suidae (Sus scrofa, one of Camelidae (Camelus bactrianus, 14 species of Cervidae (with the genera Moschus, Elaphus, Cervus, Elaphurus, Alces, Rangifer, Capreolus and 16 species of Bovidae (within the genera Bos, Gazella, Procapra, Pantholops, Saiga, Nemorhaedus, Capricornis, Budorcas, Capra, Pseudois, Ovis. They inhabit different biotopes, i.e. temperate mountain forest and steppe, temperate desert and semi-desert, and vast alpine ranges. Ungulate fossils are widespread in China evidencing that Asia was an evolutionary centre for some ungulates. Although new data have been gathered through research efforts in China since 1949 it is a fact that some ungulate species have suffered serious population set-backs and some have become endangered or even extinct. Detailed studies of ungulate populations and protection of habitats are now most important future research needs.

  17. Bread ovens in Northern Oretania

    García Huerta, Rosario


    Full Text Available This paper intends to bring to light an unusual type of domestic structure in the northern Oretania, namely the ovens used for the production of bread. The study of their distribution, as well as their dimensions and constructive features, indicates they are more complex structures, with collective or communal characters. At the same time, it gives us some knowledge of the internal organization of the main oritanian oppidas.

    Este artículo pretende dar a conocer un tipo de estructura doméstica poco habitual en la Oretania septentrional, como son los hornos destinados a la producción de pan. El análisis de su distribución, así como sus dimensiones y características constructivas, revela que se trata de estructuras más complejas, de carácter colectivo o comunal, lo que permite aproximarnos al conocimiento de la articulación interna de los principales oppida oretanos.

  18. Hydrochemistry (major and trace elements of Lake Malawi (Nyasa, Tanzanian Northern Basin: local versus global considerations

    P. Branchu


    Full Text Available This paper presents the first inventory of dissolved minor and trace element (F, Al, Fe, Mn, Ba, Cd, Cr, Cu, Pb, Mo, Bi, Sr, Zn concentrations in Lake Malawi, the second largest African lake. Sampling was carried out during 1993 dry season in the northern part of the lake. Trace metal concentrations were measured, together with Ca, Mg, Na, K, Cl, SO4, Alkalinity and Si, along three profiles in the lake northern extremity, in five tributaries and two on-land hydrothermal springs. Water profiles show similar elemental distributions and concentrations that are influenced by lake physical-chemical stratification. Stratification, assessed using temperature, conductivity, Si and Mn profiles, is characterised by two boundaries: the thermocline (70–90 m and the oxicline (150–190 m. Elemental water concentrations are discussed using simple covariance analyse. Epilimnetic concentrations and distribution are also influenced by atmospheric deposition and river diving. Comparison of dissolved concentrations for potentially polluting elements with World Health Organisation Guidelines and those reported for other East African lakes shows that this reservoir is uncontaminated despite an increasing human stress. Major element behaviour is assessed through a 3 boxes model. In this model Cl and K are conservative elements whereas Si is removed from the solution by diatom productivity and sedimentation. Ca, Na, Mg and alkalinity show low reactivity. Evaporation is one of the controlling factors of lake element concentration that superimposes on the watershed control. Hydrothermal activity, not evidenced in the lake, controls the chemistry of one of the main northern tributary. Chemical comparison between Northern rivers and other tributaries characterises the geographical and geological specificity of studied northern watershed. Moreover the lake annual chemical budget shows that northern watershed generates the main elemental input to the lake

  19. Mineralogy, geochemistry and origin of Zafarabad iron deposit based on REE and trace elements of magnetite

    Mehrdad Barati


    Full Text Available Zafarabad iron deposit is located northwest of Divandareh, in the northern margin of Sanandaj-Sirjan plutonic-metamorphic zone. The deposit is in lentoid to tubular shape, within a shear zone and occrrued in host rocks of calc-schist and limestone. Magnetite with massive, cataclastic and replacement textures are the main phases, while pyrite and other sulfide minerals are found. Major and trace elements are measured by ICP-MS and ICP-AES methods. Based on some ratios of trace elements in the ore samples and (Ti+V vs. Cal+Al+Mn and Ti+V vs. Ni/(Cr+Mn diagrams which are used for classification of iron deposit types, Zafarabad iron deposit fall in the range of skarn deposits. Spider diagrams show a steady decline from LREE to HREE elements with Eu (mean value of 0.06 ppm and Ce (mean value of 0.94 ppm negative anomalies. Comparing the distribution patterns of REE for the Zafarabad magnetites with those of various types of iron deposits shows that the REE pattern for Zafarabad is similar to these deposits. Analysis of calculated parameters for REE shows that the hydrothermal fluids responsible for mineralization are mainly of magmatic origin through fractionation and crystallization processes of a deep iron rich fluid phase and its emplacement within the carbonate rocks, forming iron skarn.

  20. The Cultural Clash in Northern Ireland

    Oliver Brennan; Gerald M Cattaro


      This paper sets out to demonstrate that the religious, political, and socio-economic elements of the conflict in Northern Ireland should be considered as manifestations of a basic cultural divide...

  1. Region 6 Northern Leopard Frog Information

    US Fish and Wildlife Service, Department of the Interior — This document contains a collection of completed questionnaires and related additional data regarding the status review of the northern leopard frog. On July 1,...

  2. Biological processes of the northern Indian Ocean

    Madhupratap, M.; Parulekar, A.H.

    Physical processes such as wind-driven coastal run-off during the monsoons and convective overturning of surface waters due to winter cooling bring in nutrients into the euphotic zone and enhance primary productivity of the northern Indian Ocean...

  3. Earthquake Damage, Northern Iran, June 21, 1990

    National Oceanic and Atmospheric Administration, Department of Commerce — A magnitude 7.7 earthquake occurred in the Gilan Province between the towns of Rudbar and Manjil in northern Iran on Thursday, June 21, 1990. The event, the largest...

  4. Ecological Subsections for Northern Alaska, 2012 update

    Arctic Landscape Conservation Cooperative — This data set represents an updated Ecological Subsection Map for Northern Alaska. This 2012 revision focused on completing the incompletely mapped portion of the...

  5. Northern Pintail - Flight Path Telemetry [ds117

    California Department of Resources — North-south flight paths of radio-tagged female northern pintails were monitored in a section of Highway 152 near Los Banos, California during 4 and 11 November and...

  6. Permafrost Soils Database for Northern Alaska 2014

    Arctic Landscape Conservation Cooperative — This database contains soil and permafrost stratigraphy for northern Alaska compiled from numerous project data files and reports. The Access Database has main data...

  7. Faith-based humanitarianism in northern Myanmar

    Edward Benson


    Full Text Available The response of faith-based organisations to displacement in northern Myanmar has been remarkable but sustaining an open and collaborative relationship with the international community remains an ongoing challenge.

  8. CNMI Northern Island Bottomfish System (NIBS)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Commonwealth of the Northern Mariana Islands (CNMI), Division of Fish and Wildlife (DFW) conducted a market sampling program that existed for a few years back in...

  9. Northern California 6 arc-second DEM

    National Oceanic and Atmospheric Administration, Department of Commerce — The 6-second Northern California Elevation Grid provides bathymetric data in ASCII raster format of 6-second resolution in geographic coordinates. This grid is...

  10. Northern California 36 arc-second DEM

    National Oceanic and Atmospheric Administration, Department of Commerce — The 36-second Northern California Elevation Grid provides bathymetric data in ASCII raster format of 36-second resolution in geographic coordinates. This grid is...

  11. Deprivation, HIV and AIDS in Northern Uganda

    Key Words: HIV & AIDS, Deprivation, Susceptibility, Vulnerability, Deaths, IDP camps, .... Uganda Peoples Defence Forces (UPDF), the Police and Local Defense .... on-going, northern Uganda is only included in the Rural Finance Service ...

  12. Setting of and mixed carbonate-siliciclastic facies associated with Holocene nearshore sabellid worm reefs, northern Belize

    Mazzullo, S.J.; Burke, C.D.; Dunn, R.K.; bischoff, W.D. (Wichita State Univ., KS (USA))


    Communities of sabellid worms (Polychaeta) in northern Belize (mouth of Northern River Lagoon) occur as areally discontinuous, unlithified patch reefs cresting positive features on an irregular depositional topography of Holocene and older sediments. They are found in nearshore marine, moderate energy, tidally influenced environments (intertidal to 60-cm depths) of normal salinity (36%) adjoining subtidal deposits. These colonies, as much as 30 cm thick, are composed of dense thickets of agglutinating worm tubes (1.0 mm diameter, 3.0 cm long) that trap and bind sand to silt-size bioclastic debris and micrite. Worm population density in these communities averages 30 tubes/cm{sup 2}. The antecedent depositional topography beneath the worm reefs and subjacent to adjoining Holocene deposits is characterized by ridges oriented normal to the present shoreline. These ridges are held up by pre-Holocene (latest Pleistocene ) terrigenous sands of probably fluvial distributary origin, occurring at approximately 2.0 m in the subsurface. The overlying Holocene deposits on these ridges are 2.0 m thick and consist of a general upward-coarsening section of terrigenous sandy, carbonate sandy muds to muddy sands punctuated by mangrove peats and capped by the worm reefs. Low areas on the antecedent topography are presently the sites of deposition of deeper subtidal (1.0 m), muddy carbonate sands with some admixed, reworked terrigenous sand. The Holocene section records drowning due to recent (approximately 6 Ka) transgression of the older, lowstand distributary sands on the northern Belize shelf. This mixed carbonate-siliciclastic section and the worm reefs presently are being reshaped and modified by littoral processes.

  13. The rock resources of the Northern Emirates

    Mitchell, Clive; Styles, Michael


    The Rock Resources of the Northern Emirates The United Arab Emirates (UAE) has vast resources of limestone and hard rock in the northern Emirates. These are currently exploited by quarrying companies to produce construction aggregate and raw material for the manufacture of cement, with a small amount being used to produce rock wool, dimension stone and mineral filler. The demand by industry for higher value mineral products that could be produced from these resources is mostly met by impor...

  14. War and reconstruction in northern Mozambique


    The article discusses some of the economic effects of war in northern Mozambique. It indicates how the historical and structural features of the economy of northern Mozambique restricted post-war reconstruction and post-war poverty alleviation. These features include the dominance of only a few cash crops for export, the absence of much rural trading, poor communication infrastructure, and weak political and state institutions. The specific nature of the internal war further weakened the stat...

  15. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    van Bentum, E.C.; Reichart, G.J.; Sinninghe Damsté, J.S.


    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The delta C-13 records of phytane and lycopane confirmed the stratigraphic position of the posi

  16. Organic matter provenance, palaeoproductivity and bottom water anoxia during the Cenomanian/Turonian oceanic anoxic event in the Newfoundland Basin (northern proto North Atlantic Ocean)

    Bentum, E.C. van; Reichart, G.-J.; Sinninghe Damsté, J.S.


    Free and sulfur-bound biomarkers in sediments deposited in the northern proto North Atlantic (Newfoundland Basin, ODP Site 1276) during the Cenomanian-Turonian oceanic anoxic event 2 (OAE-2) were studied. The δ 13C records of phytane and lycopane confirmed the stratigraphic position of the positive

  17. Origin of the tertiary red beds in the Northern part of the Duero Basin (Spain). I. Grain size, roundness, and sphericity

    Mabesoone, J.M.


    Red sediments of Tertiary age crop out alongside the southern border of the Cantabrian Mountains in the northern part of the Duero basin. They consist mainly of conglomerates with quartzite pebbles, sandstones, and sandy, loamy, and marly deposits, all with a deep red colour. Detailed analyses were

  18. Ecoenzymatic stoichiometry and microbial processing of organic matter in northern bogs and fens reveals a common P-limitation between peatland types

    Brian H. Hill; Colleen M. Elonen; Terri M. Jicha; Randall K. Kolka; LaRae L.P. Lehto; Stephen D. Sebestyen; Lindsey R. Seifert-Monson


    We compared carbon (C), nitrogen (N), and phosphorus (P) concentrations in atmospheric deposition, runoff, and soils with microbial respiration [dehydrogenase (DHA)] and ecoenzyme activity (EEA) in an ombrotrophic bog and a minerotrophic fen to investigate the environmental drivers of biogeochemical cycling in peatlands at the Marcell Experimental Forest in northern...

  19. Were they all giants? Perspectives on late Holocene plate-boundary earthquakes at the northern end of the Cascadia subduction zone

    Hutchinson, Ian; Clague, John


    The relative magnitude of plate-boundary earthquakes at the northern end of the Cascadia subduction zone was assessed from the temporal concordance between the ages of coseismically buried late Holocene soils in southwest Washington, their counterparts in central and southern Cascadia, offshore turbidites, and paleoseismic deposits on the west coast of Vancouver Island. Only three of the seven buried soils in southwest Washington that can be reliably traced as buried soils or paleotsunami deposits in the coastal lowlands of south-central and southern Cascadia have well-dated counterparts in northern Cascadia. The three wide-ranging events date from Cascadia earthquakes Y (∼250 cal BP), U (∼1260 cal BP), and N (∼2520 cal BP). All three likely ruptured the entire plate margin, and therefore potentially qualify as ;giants; (Mw ≥ 9). Deposits that may derive from tsunamis generated by earthquakes S (∼1570 cal BP), L (∼2870 cal BP) and J (∼3360 cal BP) can also be found in northern Cascadia, but the ages of these deposits are not yet well-enough constrained to determine whether they are coeval with their southern counterparts. Earthquake W (∼850 cal BP), appears to be present in the northern Cascadia paleoseismic record, but yields considerably older ages than in central Cascadia, and may be missing from southernmost Cascadia. The onshore record of an offshore turbidite (T2) displays a similar spatio-temporal pattern to that of earthquake W.

  20. Geochemistry and depositional environments of Paleocene-Eocene phosphorites: Metlaoui Group, Tunisia

    Garnit, Hechmi; Bouhlel, Salah; Jarvis, Ian


    The Late Paleocene-Early Eocene phosphorites of the Metlaoui Group in Tunisia are a world-class phosphate resource. We review the characteristics of phosphorites deposited in three areas: the Northern Basins; Eastern Basins; and Gafsa-Metlaoui Basin. Comprehensive new bulk rock elemental data are presented, together with complementary mineralogical and mineral chemical results. Carbonate fluorapatite (francolite) constitutes the dominant mineral phase in the deposits. Phosphorite samples are enriched in Cd, Sr, U, rare-earth elements and Y, together with environmentally diagnostic trace elements that provide detrital (Cr, Zr), productivity (Cu, Ni, Zn) and redox (Mo, V) proxies. Suboxic bottom-water conditions predominated, with suboxic to anoxic porewaters accompanying francolite precipitation. Phosphorite deposition occurred under increasingly arid climate conditions, accompanying global Paleocene-Eocene warming. The Northern Basins show the strongest Tethys Ocean influence, with surface seawater rare-earth element signatures consistently developed in the phosphorites. Bed-scale compositional variation indicates relatively unstable environmental conditions and episodes of sediment redeposition, with varying detrital supply and a relatively wet local climate. Glauconitic facies in the Northern Basins and the more isolated evaporite-associated phosphorites in the dryer Eastern Basins display the greatest diagenetic influences. The phosphorite - organic-rich marl - diatom-bearing porcelanite facies association in the Gafsa-Metlaoui Basin represents the classic coastal upwelling trinity. Modified Tethyan waters occurred within the Basin during phosphorite deposition, with decreasing marine productivity from NW to SE evidenced by systematically falling enrichment factors for Cu, Ni, Cd and Zn in the phosphorites. Productivity declined in concert with increasing basin isolation during the deposition of the commercial phosphorite beds in the latest Paleocene to earliest

  1. Energy deposition of thermal tides

    Becker, E.


    The main role of vertically propagating waves in the general circulation is to transfer pseudo momentum from the region of generation to the region of wave breaking. The most prominent examples in atmospheric dynamics are planetary Rossby waves forced in the troposphere, which drive a poleward residual circulation in the winter stratosphere, and mesoscale gravity waves with tropospheric origin, which drive a summer-to-winter-pole circulation in the mesopasue region. In addition, the role of energy deposition by gravity waves has long been recognized to contribute substantially to the energy budget above the stratopause. In atmospheric circulation models, gravity waves are usually parameterized. Their energy deposition can be computed along with the momentum deposition and the turbulent diffusivity associated with wave breaking. In particular, the energy deposition is expressed in terms of secondary moments of the parameterized waves. Therefore, one is tempted to assume that the energy deposition of waves that are resolved in circulation models, e.g., Rossby waves and thermal tides, is automatically taken into account. This assumption is, however, flawed. We show that the energy deposition by resolved waves corresponds to the shear production (frictional heating) of the subgrid-scale turbulence model by which these waves are damped. Computational results from an atmospheric circulation model with energetically consistent treatment of momentum diffusion and frictional heating show that the energy deposition of thermal tides is substantial above the mesopause. This effect is either incomplete or even ignored in conventional atmospheric models that resolve the mesopause region. An idealized sensitivity experiment furthermore shows that thermal tides lead to a significant downward shift of gravity-wave breaking in the upper mesosphere.

  2. Changes in faunal and vegetation communities along a soil calcium gradient in northern hardwood forests

    Beier, Colin M.; Woods, Anne M.; Hotopp, Kenneth P.; Gibbs, James P.; Mitchell, Myron J.; Dovciak, Martin; Leopold, Donald J.; Lawrence, Gregory B.; Page, Blair D.


    Depletion of Ca from forest soils due to acidic deposition has had potentially pervasive effects on forest communities, but these impacts remain largely unknown. Because snails, salamanders, and plants play essential roles in the Ca cycle of northern hardwood forests, we hypothesized that their community diversity, abundance, and structure would vary with differences in biotic Ca availability. To test this hypothesis, we sampled 12 upland hardwood forests representing a soil Ca gradient in the Adirondack Mountains, New York (USA), where chronic deposition has resulted in acidified soils but where areas of well-buffered soils remain Ca rich due to parent materials. Along the gradient of increasing soil [Ca2+], we observed increasing trends in snail community richness and abundance, live biomass of redback salamanders (Plethodon cinereus (Green, 1818)), and canopy tree basal area. Salamander communities were dominated by mountain dusky salamanders (Desmognathus ochrophaeus Cope, 1859) at Ca-poor sites and changed continuously along the Ca gradient to become dominated by redback salamanders at the Ca-rich sites. Several known calciphilic species of snails and plants were found only at the highest-Ca sites. Our results indicated that Ca availability, which is shaped by geology and acidic deposition inputs, influences northern hardwood forest ecosystems at multiple trophic levels, although the underlying mechanisms require further study.

  3. Characterization of clay from northern of Morocco for their industrial application

    El Ouahabi, Meriam; Fagel, Nathalie


    Clays are a natural resource used for millennia. Currently applications such as industrial minerals are diversified. In this context, our goal is to estimate the potential of the many clay deposits in northern of Morocco. The choice of this region is justified by the particular abundance of clay deposits used to manufacture building materials (brick, ceramic and refractories) and pottery. This study focuses on the mineralogical, chemical and geotechnical characterization tests carried out on Tangier-Tetouan and Meknes clays from northern of Morocco. The suitability of raw clay material from those regions in order to produce ceramic and brick has not been tested yet. The results revealed that the studied samples are diversified, kaolinite and illite (Tetouan clay) and kaolinite and illite and smectite and vermiculite (Tangier and Meknes clay) based materials. There were no major differences in grain-size distribution, whereas Meknes clay was more plastic than Tetouan-Tangier clay. The cation exchange capacity show that Meknes and Tangier clay were more important than Tetouan clay. Specific surface area and thermal analaysis complete this caracterization. It was found that almost all technological properties of the Meknes clay deposit are led to the manufacture of ceramic floor tile, and Tetouan-Tangier clay provide opportunities to making brick and ceramic floor. The Tetouan-Tangier and Meknes clay are a potential ceramic raw material for growing Morrocan ceramic tile and brick industries.

  4. Observation- and model-based estimates of particulate dry nitrogen deposition to the oceans

    Baker, Alex R.; Kanakidou, Maria; Altieri, Katye E.; Daskalakis, Nikos; Okin, Gregory S.; Myriokefalitakis, Stelios; Dentener, Frank; Uematsu, Mitsuo; Sarin, Manmohan M.; Duce, Robert A.; Galloway, James N.; Keene, William C.; Singh, Arvind; Zamora, Lauren; Lamarque, Jean-Francois; Hsu, Shih-Chieh; Rohekar, Shital S.; Prospero, Joseph M.


    Anthropogenic nitrogen (N) emissions to the atmosphere have increased significantly the deposition of nitrate (NO3-) and ammonium (NH4+) to the surface waters of the open ocean, with potential impacts on marine productivity and the global carbon cycle. Global-scale understanding of the impacts of N deposition to the oceans is reliant on our ability to produce and validate models of nitrogen emission, atmospheric chemistry, transport and deposition. In this work, ˜ 2900 observations of aerosol NO3- and NH4+ concentrations, acquired from sampling aboard ships in the period 1995-2012, are used to assess the performance of modelled N concentration and deposition fields over the remote ocean. Three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) were selected, in which the density and distribution of observational data were considered sufficient to provide effective comparison to model products. All of these study regions are affected by transport and deposition of mineral dust, which alters the deposition of N, due to uptake of nitrogen oxides (NOx) on mineral surfaces. Assessment of the impacts of atmospheric N deposition on the ocean requires atmospheric chemical transport models to report deposition fluxes; however, these fluxes cannot be measured over the ocean. Modelling studies such as the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), which only report deposition flux, are therefore very difficult to validate for dry deposition. Here, the available observational data were averaged over a 5° × 5° grid and compared to ACCMIP dry deposition fluxes (ModDep) of oxidised N (NOy) and reduced N (NHx) and to the following parameters from the Tracer Model 4 of the Environmental Chemical Processes Laboratory (TM4): ModDep for NOy, NHx and particulate NO3- and NH4+, and surface-level particulate NO3- and NH4+ concentrations. As a model ensemble, ACCMIP can be expected to be more robust than

  5. Regional surficial geochemistry of the northern Great Basin

    Ludington, S.; Folger, H.; Kotlyar, B.; Mossotti, V.G.; Coombs, M.J.; Hildenbrand, T.G.


    The regional distribution of arsenic and 20 other elements in stream-sediment samples in northern Nevada and southeastern Oregon was studied in order to gain new insights about the geologic framework and patterns of hydrothermal mineralization in the area. Data were used from 10,261 samples that were originally collected during the National Uranium Resource Evaluation (NURE) Hydrogeochemical and Stream Sediment Reconnaissance (HSSR) program in the 1970s. The data are available as U.S. Geological Survey Open-File Report 02-0227. The data were analyzed using traditional dot maps and interpolation between data points to construct high-resolution raster images, which were correlated with geographic and geologic information using a geographic information system (GIS). Wavelength filters were also used to deconvolute the geochemical images into various textural components, in order to study features with dimensions of a few kilometers to dimensions of hundreds of kilometers. The distribution of arsenic, antimony, gold, and silver is different from distributions of the other elements in that they show a distinctive high background in the southeast part of the area, generally in areas underlain by the pre-Mesozoic craton. Arsenic is an extremely mobile element and can be used to delineate structures that served as conduits for the circulation of metal-bearing fluids. It was used to delineate large crustal structures and is particularly good for delineation of the Battle Mountain-Eureka mineral trend and the Steens lineament, which corresponds to a post-Miocene fault zone. Arsenic distribution patterns also delineated the Black Rock structural boundary, northwest of which the basement apparently consists entirely of Miocene and younger crust. Arsenic is also useful to locate district-sized hydrothermal systems an d clusters of systems. Most important types of hydrothermal mineral deposit in the northern Great Basin appear to be strongly associated with arsenic; this is less

  6. Potential nitrogen critical loads for northern Great Plains grassland vegetation

    Symstad, Amy J.; Smith, Anine T.; Newton, Wesley E.; Knapp, Alan K.


    The National Park Service is concerned that increasing atmospheric nitrogen deposition caused by fossil fuel combustion and agricultural activities could adversely affect the northern Great Plains (NGP) ecosystems in its trust. The critical load concept facilitates communication between scientists and policy makers or land managers by translating the complex effects of air pollution on ecosystems into concrete numbers that can be used to inform air quality targets. A critical load is the exposure level below which significant harmful effects on sensitive elements of the environment do not occur. A recent review of the literature suggested that the nitrogen critical load for Great Plains vegetation is 10-25 kg N/ha/yr. For comparison, current atmospheric nitrogen deposition in NGP National Park Service (NPS) units ranges from ~4 kg N/ha/yr in the west to ~13 kg N/ha/yr in the east. The suggested critical load, however, was derived from studies far outside of the NGP, and from experiments investigating nitrogen loads substantially higher than current atmospheric deposition in the region.Therefore, to better determine the nitrogen critical load for sensitive elements in NGP parks, we conducted a four-year field experiment in three northern Great Plains vegetation types at Badlands and Wind Cave National Parks. The vegetation types were chosen because of their importance in NGP parks, their expected sensitivity to nitrogen addition, and to span a range of natural fertility. In the experiment, we added nitrogen at rates ranging from below current atmospheric deposition (2.5 kg N/ha/yr) to far above those levels but commensurate with earlier experiments (100 kg N/ha/yr). We measured the response of a variety of vegetation and soil characteristics shown to be sensitive to nitrogen addition in other studies, including plant biomass production, plant tissue nitrogen concentration, plant species richness and composition, non-native species abundance, and soil inorganic

  7. Isotopic evidence on multiple sources of nitrogen in the northern Jiulong River, Southeast China

    Cao, Wenzhi; Huang, Zheng; Zhai, Weidong; Li, Ying; Hong, Huasheng


    Riverine export accounts for a large portion of estuarine and coastal nutrients and could lead to severe eutrophication. However, nitrogen (N) sources at the catchment scale remain unclear because of spatial and temporal variations. The stable isotope of 15N, which has been proven to be effective in deducing sources and testing biogeochemical behaviours, is applied in this study to explore multiple sources of riverine N and their nutrient concentrations in the northern section of Jiulong River catchment seasonally. Results show that drastic seasonal variation in external nitrate sources occurs in the river; manure and sewage dominate during base flows, whereas organic N in soil and atmospheric deposition dominate during storm flows. The external sources change throughout the year depending on the environmental conditions. Furthermore, riverine nitrate import in the northern Jiulong River is dominated by an external process because of the increasing NO3- - δ15N value accompanied by an increasing NO3- -N concentration (p management and eutrophication reversal.

  8. Peat bogs in northern Alberta, Canada reveal decades of declining atmospheric Pb contamination

    Shotyk, William; Appleby, Peter G.; Bicalho, Beatriz; Davies, Lauren; Froese, Duane; Grant-Weaver, Iain; Krachler, Michael; Magnan, Gabriel; Mullan-Boudreau, Gillian; Noernberg, Tommy; Pelletier, Rick; Shannon, Bob; Bellen, Simon; Zaccone, Claudio


    Peat cores were collected from six bogs in northern Alberta to reconstruct changes in the atmospheric deposition of Pb, a valuable tracer of human activities. In each profile, the maximum Pb enrichment is found well below the surface. Radiometric age dating using three independent approaches (14C measurements of plant macrofossils combined with the atmospheric bomb pulse curve, plus 210Pb confirmed using the fallout radionuclides 137Cs and 241Am) showed that Pb contamination has been in decline for decades. Today, the surface layers of these bogs are comparable in composition to the "cleanest" peat samples ever found in the Northern Hemisphere, from a Swiss bog ~ 6000 to 9000 years old. The lack of contemporary Pb contamination in the Alberta bogs is testimony to successful international efforts of the past decades to reduce anthropogenic emissions of this potentially toxic metal to the atmosphere.

  9. Relative water level change in the intracoastal zone of Belgium and northern France over the last 2500 years

    S. Louwye; Declercq, E.


    Water level positions during the Subatlantic in the coastal plain of Belgium and Northern France are assessed by means of indicators such as tidal levees, upper tidal flat deposits and mature salt marshes. The indicators are evaluated for the reconstruction of local mean high water and local mean spring high water levels in the intracoastal zone. No significant altitude difference is observed between the indicators genetically related to the Dunkerque II inundation phase, i.e. before the land...

  10. Holocene cemented beach deposits in Belize

    Gischler, Eberhard; Lomando, Anthony J.


    Two types of cemented beach deposits occur on reef islands off the coast of Belize. These are (1) intertidal beachrock that is dominantly cemented by marine aragonite and high-magnesium-calcite cements, and (2) supratidal cayrock that is cemented mainly by vadose low-magnesium-calcite cements. Besides differences in position relative to present sea level and resulting early diagenesic features, beachrock and cayrock can be distinguished on the basis of differences in composition, texture, geographical position, and age. Whereas the composition of beachrock is similar to that of the adjacent marginal reef sediments, cayrock is enriched in benthic foraminifera. Intertidal beachrock is moderately to well sorted and well cemented, while supratidal cayrock is very well sorted, poorly cemented and friable. Beachrock occurs preferentially on windward beaches of sand-shingle Gays on the middle and southern barrier reefs and on the isolated platforms Glovers and Lighthouse Reefs. Cayrock only occurs on larger mangrove-sand Gays of the isolated platforms Turneffe Islands, Lighthouse Reef, and the northern barrier reef. 14C-dating of ten whole-rock and mollusk shell samples produced calibrated dates between AD 345 and AD 1435 for beachrock and between BC 1085 and AD 1190 for cayrock. The large-scale distribution of beachrock in Belize supports the contention that physical processes such as water agitation rather than biological processes control beachrock formation and distribution. Only on windward sides of cays that are close to the reef crest, where large amounts of seawater flush the beaches, considerable amounts of cements can be precipitated to produce beachrock. Cayrock forms due to cementation in the vadose zone and is only preserved on larger, stable mangrove-sand cays.

  11. A Radon Progeny Deposition Model

    Guiseppe, V E; Hime, A; Rielage, K; Westerdale, S


    The next generation low-background detectors operating underground aim for unprecedented low levels of radioactive backgrounds. Although the radioactive decays of airborne radon (particularly Rn-222) and its subsequent progeny present in an experiment are potential backgrounds, also problematic is the deposition of radon progeny on detector materials. Exposure to radon at any stage of assembly of an experiment can result in surface contamination by progeny supported by the long half life (22 y) of Pb-210 on sensitive locations of a detector. An understanding of the potential surface contamination from deposition will enable requirements of radon-reduced air and clean room environments for the assembly of low background experiments. It is known that there are a number of environmental factors that govern the deposition of progeny onto surfaces. However, existing models have not explored the impact of some environmental factors important for low background experiments. A test stand has been constructed to depos...

  12. Combustion iron distribution and deposition

    Luo, Chao; Mahowald, N.; Bond, T.; Chuang, P. Y.; Artaxo, P.; Siefert, R.; Chen, Y.; Schauer, J.


    Iron is hypothesized to be an important micronutrient for ocean biota, thus modulating carbon dioxide uptake by the ocean biological pump. Studies have assumed that atmospheric deposition of iron to the open ocean is predominantly from mineral aerosols. For the first time we model the source, transport, and deposition of iron from combustion sources. Iron is produced in small quantities during fossil fuel burning, incinerator use, and biomass burning. The sources of combustion iron are concentrated in the industrialized regions and biomass burning regions, largely in the tropics. Model results suggest that combustion iron can represent up to 50% of the total iron deposited, but over open ocean regions it is usually less than 5% of the total iron, with the highest values (ocean biogeochemistry the bioavailability of the iron is important, and this is often estimated by the fraction which is soluble (Fe(II)). Previous studies have argued that atmospheric processing of the relatively insoluble Fe(III) occurs to make it more soluble (Fe(II)). Modeled estimates of soluble iron amounts based solely on atmospheric processing as simulated here cannot match the variability in daily averaged in situ concentration measurements in Korea, which is located close to both combustion and dust sources. The best match to the observations is that there are substantial direct emissions of soluble iron from combustion processes. If we assume observed soluble Fe/black carbon ratios in Korea are representative of the whole globe, we obtain the result that deposition of soluble iron from combustion contributes 20-100% of the soluble iron deposition over many ocean regions. This implies that more work should be done refining the emissions and deposition of combustion sources of soluble iron globally.


    Cem Sarica; Michael Volk


    As oil and gas production moves to deeper and colder water, subsea multiphase production systems become critical for economic feasibility. It will also become increasingly imperative to adequately identify the conditions for paraffin precipitation and predict paraffin deposition rates to optimize the design and operation of these multi-phase production systems. Although several oil companies have paraffin deposition predictive capabilities for single-phase oil flow, these predictive capabilities are not suitable for the multiphase flow conditions encountered in most flowlines and wellbores. For deepwater applications in the Gulf of Mexico, it is likely that multiphase production streams consisting of crude oil, produced water and gas will be transported in a single multiphase pipeline to minimize capital cost and complexity at the mudline. Existing single-phase (crude oil) paraffin deposition predictive tools are clearly inadequate to accurately design these pipelines, because they do not account for the second and third phases, namely, produced water and gas. The objective of this program is to utilize the current test facilities at The University of Tulsa, as well as member company expertise, to accomplish the following: enhance our understanding of paraffin deposition in single and two-phase (gas-oil) flows; conduct focused experiments to better understand various aspects of deposition physics; and, utilize knowledge gained from experimental modeling studies to enhance the computer programs developed in the previous JIP for predicting paraffin deposition in single and two-phase flow environments. These refined computer models will then be tested against field data from member company pipelines.

  14. Nanofriction properties of molecular deposition films

    王强斌; 高芒来; 张嗣伟


    The nanofriction properties of Au substrate and monolayer molecular deposition film and multilayer molecular deposition films on Au substrate and the molecular deposition films modified with alkyl-terminal molecule have been investigated by using an atomic force microscope. It is concluded that ( i ) the deposition of molecular deposition films on Au substrate and the modification of alkyl-terminal molecule to the molecular deposition films can reduce the frictional force; (ii) the molecular deposition films with the same terminal exhibit similar nanofriction properties, which has nothing to do with the molecular chain-length and the layer number; (iii) the unstable nanofriction properties of molecular deposition films are contributed to the active terminal of the molecular deposition film, which can be eliminated by decorating the active molecular deposition film with alkyl-terminal molecule, moreover, the decoration of alkyl-terminal molecule can lower the frictional force conspicuously; (iv) the relat

  15. Viral diseases of northern ungulates

    K. Frölich


    Full Text Available This paper describes viral diseases reported in northern ungulates and those that are a potential threat to these species. The following diseases are discussed: bovine viral diarrhoea/mucosal disease (BVD/MD, alphaherpesvirus infections, malignant catarrhal fever (MCF, poxvirus infections, parainfluenza type 3 virus infection, Alvsborg disease, foot-and-mouth disease, epizootic haemorrhage disease of deer and bluetongue disease, rabies, respiratory syncytial virus infection, adenovirus infection, hog-cholera, Aujeszky's disease and equine herpesvirus infections. There are no significant differences in antibody prevalence to BVDV among deer in habitats with high, intermediate and low density of cattle. In addition, sequence analysis from the BVDV isolated from roe deer (Capreolus capreolus showed that this strain was unique within BVDV group I. Distinct BVDV strains might circulate in free-ranging roe deer populations in Germany and virus transmission may be independent of domestic livestock. Similar results have been obtained in a serological survey of alpha-herpesviruses in deer in Germany. Malignant catarrhal fever was studied in fallow deer (Cervus dama in Germany: the seroprevalence and positive PCR results detected in sheep originating from the same area as the antibody-positive deer might indicate that sheep are the main reservoir animals. Contagious ecthyma (CE is a common disease in domestic sheep and goats caused by the orf virus. CE has been diagnosed in Rocky Mountain bighorn sheep (Ovis canadensis, mountain goats (Oreamnos americanus, Dall sheep (Ovis dalli, chamois (Rupkapra rupi-capra, muskox {Ovibos moschatus and reindeer (Rangifer tarandus. Most parainfluenza type 3 virus infections are mild or clinically undetectable. Serological surveys in wildlife have been successfully conducted in many species. In 1985, a new disease was identified in Swedish moose (Alces alces, designated as Alvsborg disease. This wasting syndrome probably

  16. Analysing the Cenozoic depositional record

    Goledowski, Bartosz; Clausen, O.R.; Nielsen, S.B.

    It is well known that sediment deposition in the North Sea and on the Norwegian Shelf varied significantly during the Cenozoic as a consequence of varying erosion rate mainly in Western Scandinavia, in Scotland and in the Alps. Recent results have demonstrated that a causal relationship exists...... of variations in erosion rates. Here we present the rationale behind the project, the data available and some preliminary results. The dense seismic and well coverage in the area makes it possible to estimate the rate of deposition of matrix mass. Assuming that sediment storage is not important, this provides...

  17. Shallow stratigraphy and paleolandscapes offshore from the Northern Channel Islands

    Maloney, J. M.; Braje, T.; Gusick, A. E.; Ho, B.; Ball, D.


    New high-resolution Chirp and sidescan sonar data collected on the shelf offshore from the Northern Channel Islands image patterns of sediment distribution since the last glacial maximum (LGM), extensive faulting and deformation, and submerged paleolandscapes that may contain archaeological resources. During the last glacial maximum, the four Northern Channel Islands in the Southern California Bight formed an extensive landmass known as Santarosae. Sea-level transgression since the LGM has inundated over 70% of Santarosae, submerging the shelf around the modern islands. The islands are traversed by numerous faults that extend offshore and marine terraces are observed both onshore and offshore. This area is an ideal landscape to investigate the relationships between sediment supply, eustasy, and tectonics in controlling sediment distribution on continental shelves. Furthermore, the presence of Paleocoastal archaeological sites on the islands suggests that similar sites may be present on the submerged shelf. The new data reveal faulting and deformation associated with the Santa Rosa and Santa Cruz fault zones. Both faults offset acoustic horizons below a regional unconformity interpreted as the transgressive surface. Sediment thickness is variable above the transgressive surface and bedform spatial patterns imaged in the sidescan sonar do not appear to correlate with sediment thickness or depth. In Chirp data, we interpret several filled paleochannels extending across the shelf, some of which appear fault controlled. Along with possible estuarine deposits imaged near the modern submarine canyon, these paleolandforms would have been important resources for people living on Santarosae and may contain archaeological resources. Overall, these data elucidate effects of sea level transgression and patterns of sediment distribution on islands located along an active margin.

  18. Mechanisms controlling soil carbon sequestration under atmospheric nitrogen deposition

    R.L. Sinsabaugh; D.R. Zak; D.L. Moorhead


    Increased atmospheric nitrogen (N) deposition can alter the processing and storage of organic carbon in soils. In 2000, we began studying the effects of simulated atmospheric N deposition on soil carbon dynamics in three types of northern temperate forest that occur across a wide geographic range in the Upper Great Lakes region. These ecosystems range from 100% oak in the overstory (black oak-white oak ecosystem; BOWO) to 0% overstory oak (sugar maple-basswood; SMBW) and include the sugar maple-red oak ecosystem (SMRO) that has intermediate oak abundance. The leaf litter biochemistry of these ecosystems range from highly lignified litter (BOWO) to litter of low lignin content (SMBW). We selected three replicate stands of each ecosystem type and established three plots in each stand. Each plot was randomly assigned one of three levels of N deposition (0, 30 & 80 kg N ha-1 y-1) imposed by adding NaNO3 in six equal increments applied over the growing season. Through experiments ranging from the molecular to the ecosystem scales, we produced a conceptual framework that describes the biogeochemistry of soil carbon storage in N-saturated ecosystems as the product of interactions between the composition of plant litter, the composition of the soil microbial community and the expression of extracellular enzyme activities. A key finding is that atmospheric N deposition can increase or decrease the soil C storage by modifying the expression of extracellular enzymes by soil microbial communities. The critical interactions within this conceptual framework have been incorporated into a new class of simulations called guild decomposition models.

  19. Bank deposits, notions and features of accounting

    Georgeta MELNIC


    Full Text Available Bank deposits are the main method of raising capital and short-term available savings. The opening and using of the bank deposits is the main function of banks. In 2004 the Deposit Guarantee Fund was set up in the Republic of Moldova of Deposit Guarantee Fund and for the first time there was established a guaranteed bank minimum in case of bank insolvency which is currently 6,000 lei for the deposit of each natural person.

  20. One new species of the genus Belisana Thorell, 1898 (Araneae, Pholcidae from northern Vietnam

    Dinh-Sac Pham


    Full Text Available One new species Belisana denticulata sp. n. (♂ is reported from northern Vietnam based on material collected by fogging the forest canopy. This species resembles B. scharffi Huber, 2005, but can be distinguished by relatively long distance between proximal parts of proximo-lateral apophysis and distal apophysis on male chelicerae, by presence of a nearly saddle-shaped prolateral sclerite on procursus, and by different shape of retrolateral membranous flap on procursus. Type specimens are deposited in the Vietnam Academy of Science and Technology in Hanoi.

  1. Integrated diagnostics of northern gas pipelines; Diagnostic integre des gazoducs septentrionaux

    Volsky, E.; Dedikov, E.; Ananenkov, A.; Salchov, Z.; Yakupov, Z. [Joint-Stock Company, Gazprom (Russian Federation)


    The main part of gas joint - stock company 'Gazprom' extracts from the northern deposits, which are situated in the permafrost zone. Ensuring of gas transporting pipeline's safety operation is a very complex and priority problem. On the basis of usage of this complex of methods the problem to ensure the safety operation is solved systematically: gas-mine - plant IV - derivation pipelines (condensate pipeline Yamburg Novy Urengoy, gas pipeline IV - GCS with negative temperature of transported products) taking into account 'co-ordination' dynamics of changes in pipeline GTS and technological modes of equipment operation. All researches was executed on the high professional level. (authors)

  2. Climatic variability, plant phenology, and northern ungulates

    Post, E.; Stenseth, N.C. [Univ. of Oslo (Norway)


    Models of climate change predict that global temperatures and precipitation will increase within the next century, with the most pronounced changes occurring in northern latitudes and during winter. A large-scale atmospheric phenomenon, the North Atlantic Oscillation (NAO), is a strong determinant of both interannual variation and decadal trends in temperatures and precipitation during winter in northern latitudes, and its recent persistence in one extreme phase may be a substantial component of increases in global temperatures. Hence, the authors investigated the influences of large-scale climatic variability on plant phenology and ungulate population ecology by incorporating the NAO in statistical analyses of previously published data on: (1) the timing of flowering by plants in Norway, and (2) phenotypic and demographic variation in populations of northern ungulates. The authors analyzed 137 time series on plant phenology for 13 species of plants in Norway spanning up to 50 yr and 39 time series on phenotypic and demographic traits of 7 species of northern ungulates from 16 populations in North America and northern Europe spanning up to 30 yr.

  3. Trends in nitrogen deposition and leaching in acid-sensitive streams in Europe

    R. F. Wright


    Full Text Available Long-term records of nitrogen in deposition and streamwater were analysed at 30 sites covering major acid sensitive regions in Europe. Large regions of Europe have received high inputs of inorganic nitrogen for the past 20 - 30 years, with an approximate 20% decline in central and northern Europe during the late 1990s. Nitrate concentrations in streamwaters are related to the amount of N deposition. All sites with less than 10 kgN ha-1 yr-1 deposition have low concentrations of nitrate in streamwater, whereas all sites receiving > 25 kgN ha-1 yr-1 have elevated concentrations. Very few of the sites exhibit significant trends in nitrate concentrations; similar analyses on other datasets also show few significant trends. Nitrogen saturation is thus a process requiring many decades, at least at levels of N deposition typical for Europe. Declines in nitrate concentrations at a few sites may reflect recent declines in N deposition. The overall lack of significant trends in nitrate concentrations in streams in Europe may be the result of two opposing factors. Continued high deposition of nitrogen (above the 10 kgN ha-1 yr-1 threshold should tend to increase N saturation and give increased nitrate concentrations in run-off, whereas the decline in N deposition over the past 5 – 10 years in large parts of Europe should give decreased nitrate concentrations in run-off. Short and long-term variations in climate affect nitrate concentrations in streamwater and, thus, contribute "noise" which masks long-term trends. Empirical data for geographic pattern and long-term trends in response of surface waters to changes in N deposition set the premises for predicting future contributions of nitrate to acidification of soils and surface waters. Quantification of processes governing nitrogen retention and loss in semi-natural terrestrial ecosystems is a scientific challenge of increasing importance. Keywords: Europe, acid deposition, nitrogen, saturation, recovery

  4. Advanced deposition model for thermal activated chemical vapor deposition

    Cai, Dang

    Thermal Activated Chemical Vapor Deposition (TACVD) is defined as the formation of a stable solid product on a heated substrate surface from chemical reactions and/or dissociation of gaseous reactants in an activated environment. It has become an essential process for producing solid film, bulk material, coating, fibers, powders and monolithic components. Global market of CVD products has reached multi billions dollars for each year. In the recent years CVD process has been extensively used to manufacture semiconductors and other electronic components such as polysilicon, AlN and GaN. Extensive research effort has been directed to improve deposition quality and throughput. To obtain fast and high quality deposition, operational conditions such as temperature, pressure, fluid velocity and species concentration and geometry conditions such as source-substrate distance need to be well controlled in a CVD system. This thesis will focus on design of CVD processes through understanding the transport and reaction phenomena in the growth reactor. Since the in situ monitor is almost impossible for CVD reactor, many industrial resources have been expended to determine the optimum design by semi-empirical methods and trial-and-error procedures. This approach has allowed the achievement of improvements in the deposition sequence, but begins to show its limitations, as this method cannot always fulfill the more and more stringent specifications of the industry. To resolve this problem, numerical simulation is widely used in studying the growth techniques. The difficulty of numerical simulation of TACVD crystal growth process lies in the simulation of gas phase and surface reactions, especially the latter one, due to the fact that very limited kinetic information is available in the open literature. In this thesis, an advanced deposition model was developed to study the multi-component fluid flow, homogeneous gas phase reactions inside the reactor chamber, heterogeneous surface

  5. Systems for Guaranteeing Bank Deposits

    Florin Untaru


    The advent of the financial crisis and the latest event that occurred in Cyprus bring new light to how states intervene when commercial banks are facing the risk of bankruptcy. While until now institutions had a clear traditional role to protect depositors, currently there is a trend to transfer damage to companies and individuals that hold deposits.

  6. Chemical-vapor-deposition reactor

    Chern, S.


    Reactor utilizes multiple stacked trays compactly arranged in paths of horizontally channeled reactant gas streams. Design allows faster and more efficient deposits of film on substrates, and reduces gas and energy consumption. Lack of dead spots that trap reactive gases reduces reactor purge time.

  7. Electro-spark deposition technology

    Johnson, R.N. [Pacific Northwest National Lab., Richland, WA (United States)


    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated critical to the life and economy of the advanced fossil energy systems as the higher temperatures and corrosive environments exceed the limits of known structural materials to accommodate the service conditions. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. A new development is the demonstration of advanced aluminide-based ESD coatings for erosion and wear applications. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that yields an order of magnitude increase in deposition rates and achievable coating thicknesses. Achieving this regime has required the development of advanced ESD electronic capabilities. Development is now focused on further improvements in deposition rates, system reliability when operating at process extremes, and economic competitiveness.

  8. Nitrogen deposition and terrestrial biodiversity

    Christopher M. Clark; Yongfei Bai; William D. Bowman; Jane M. Cowles; Mark E. Fenn; Frank S. Gilliam; Gareth K. Phoenix; Ilyas Siddique; Carly J. Stevens; Harald U. Sverdrup; Heather L. Throop


    Nitrogen deposition, along with habitat losses and climate change, has been identified as a primary threat to biodiversity worldwide (Butchart et al., 2010; MEA, 2005; Sala et al., 2000). The source of this stressor to natural systems is generally twofold: burning of fossil fuels and the use of fertilizers in modern intensive agriculture. Each of these human...



    <正>20082329 Chen Wang(China University of Geosciences,Beijing 100083,China) Control Factors on Distribution of Carboniferous Bauxite Deposits in Western Henan Province (Geotectonica et Metallogenia,ISSN1001—1552,CN44—1595/P,31(4),2007,p.452—456,1 illus.,10 refs.) Key words:bauxite,mineralization con- trols,Henan Province

  10. Titania Deposition on PMR-15

    Meador, Mary B.; Sutter, James K.; Pizem, Hillel; Gershevitz, Olga; Goffer, Yossi; Frimer, Aryeh A.; Sukenik, Chaim N.; Sampathkumaran, Uma; Milhet, Xavier; McIlwain, Alan


    The formation, degree of crystallinity and adherence of dense titania (TiO2) thin film coatings on a high-temperature polyimide resin (PMR-15) can be influenced by the chemical composition of the polymer surface. Furthermore, solution deposition conditions can be adjusted to provide additional control over the morphology and crystallinity of the titania films. Recipes for solution-based titania deposition that used a slowly-hydrolyzing titanium fluoride salt in the presence of boric acid as a fluoride scavenger allowed growth of films up to 750 nm thick in 22 h. By adjusting solution pH and temperature, either amorphous titania or oriented crystalline anatase films could be formed. Surface sulfonate groups enhance the adhesion of solution-deposited oxide thin film coatings. While most sulfonation procedures severely damaged the PMR-15 surface, the use of chlorosulfonic acid followed by hydrolysis of the installed chlorosulfonyl groups provided effective surface sulfonation without significant surface damage. In some cases, the oxide deposition solution caused partial hydrolysis of the polymer surface, which itself was sufficient to allow adhesion of the titania film through chelation of titanium ions by exposed benzoic acid groups on the polymer surface.

  11. Simple Chemical Vapor Deposition Experiment

    Pedersen, Henrik


    Chemical vapor deposition (CVD) is a process commonly used for the synthesis of thin films for several important technological applications, for example, microelectronics, hard coatings, and smart windows. Unfortunately, the complexity and prohibitive cost of CVD equipment makes it seldom available for undergraduate chemistry students. Here, a…

  12. Deposition and Resuspension of Particles

    Lengweiler, P.; Nielsen, Peter V.; Moser, A.

    To investigate the physical process of deposition and resuspension of particles in the indoor environment, scale experiments are used and a sampling method is established. The influences of surface orientation and turbulence and velocity of the air on the dust load on a surface are analysed....

  13. Soot Deposit Properties in Practical Flames

    Preciado, Ignacio [University of Utah; Eddings, Eric G. [University of Utah; Sarofim, Adel F. [University of Utah; Dinwiddie, Ralph Barton [ORNL; Porter, Wallace D [ORNL; Lance, Michael J [ORNL


    Soot deposition from hydrocarbon flames was investigated in order to evaluate the evolution of the deposits during the transient process of heating an object that starts with a cold metal surface that is exposed to a flame. The study focused on the fire/metal surface interface and the critical issues associated with the specification of the thermal boundaries at this interface, which include the deposition of soot on the metal surface, the chemical and physical properties of the soot deposits and their subsequent effect on heat transfer to the metal surface. A laboratory-scale device (metallic plates attached to a water-cooled sampling probe) was designed for studying soot deposition in a laminar ethylene-air premixed flame. The metallic plates facilitate the evaluation of the deposition rates and deposit characteristics such as deposit thickness, bulk density, PAH content, deposit morphology, and thermal properties, under both water-cooled and uncooled conditions. Additionally, a non-intrusive Laser Flash Technique (in which the morphology of the deposit is not modified) was used to estimate experimental thermal conductivity values for soot deposits as a function of deposition temperature (water-cooled and uncooled experiments), location within the flame and chemical characteristics of the deposits. Important differences between water-cooled and uncooled surfaces were observed. Thermophoresis dominated the soot deposition process and enhanced higher deposition rates for the water-cooled experiments. Cooler surface temperatures resulted in the inclusion of increased amounts of condensable hydrocarbons in the soot deposit. The greater presence of condensable material promoted decreased deposit thicknesses, larger deposit densities, different deposit morphologies, and higher thermal conductivities.

  14. Summertime surface O3 behavior and deposition to tundra in the Alaskan Arctic

    Van Dam, Brie; Helmig, Detlev; Doskey, Paul V.; Oltmans, Samuel J.


    Atmospheric turbulence quantities, boundary layer ozone (O3) levels, and O3 deposition to the tundra surface were investigated at Toolik Lake, AK, during the 2011 summer season. Beginning immediately after snowmelt, a diurnal cycle of O3 in the atmospheric surface layer developed with daytime O3 maxima, and minima during low-light hours, resulting in a mean amplitude of 13 ppbv. This diurnal O3 cycle is far larger than observed at other high Arctic locations during the snow-free season. During the snow-free months of June, July, and August, O3 deposition velocities were ˜3 to 5 times faster than during May, when snow covered the ground most of the month. The overall mean O3 deposition velocity between June and August was 0.10 cm s-1. The month of June had the highest diurnal variation, with a median O3 deposition velocity of 0.2 cm s-1 during the daytime and 0.08 cm s-1 during low-light conditions. These values are slightly lower than previously reported summertime deposition velocities in northern latitudes over tundra or fen. O3 loss during low-light periods was attributed to a combination of surface deposition to the tundra and stable boundary layer conditions. We also hypothesize that emissions of reactive biogenic volatile organic compounds into the shallow boundary layer may contribute to nighttime O3 loss.

  15. Reconstruction and analysis of cesium-137 fallout deposition patterns in the Marshall Islands

    Whitcomb, Robert Cleckley, Jr.

    Estimates of 137Cs deposition due to fallout originating from nuclear weapons testing in the Marshall Islands have been made for several locations in the Marshall Islands. These retrospective estimates were based primarily on historical exposure rate and gummed film measurements. The methods used to reconstruct these deposition estimates are specific for six of the Pacific tests. These methods are also similar to those used in the National Cancer Institute study for reconstructing 131I deposition from the Nevada Test Site. Reconstructed cumulative deposition estimates are validated against contemporary measurements of 137Cs concentration in soil. This validation work also includes an accounting for estimated global fallout contributions. These validations show that the overall geometric bias in predicted-to-observed (P/O) ratios is 1.0 (indicating excellent agreement). The 5th and 95th percentile range of this distribution is 0.35--2.95. The P/O ratios for estimates using historical gummed film measurements tend to slightly over-predict more than estimates using exposure rate measurements. The methods produce reasonable estimates of deposition confirming that radioactive fallout occurred at atolls further south of the four northern atolls recognized by the Department of Energy as being affected by fallout. The deposition estimate methods, supported by the very good agreement between estimates and measurements, suggest that these methods can be used for other weapons testing fallout radionuclides with confidence.

  16. Phenological controls on inter-annual variability in ozone dry deposition velocity

    Clifton, Olivia; Fiore, Arlene; Munger, J. William; Shevliakova, Elena; Horowitz, Larry; Malyshev, Sergey; Griffin, Kevin


    Our understanding of ozone removal by northern mid-latitude temperate deciduous forests is largely based on short-term observational studies, and thus year-to-year variations of this sink have received little attention. The specific pathways for ozone dry deposition include stomatal uptake and other non-stomatal processes that are poorly understood. Given the importance of ozone dry deposition to model accurately the tropospheric ozone budget and regional air quality, an improved mechanistic understanding of this ozone sink is needed. We investigate here the physical and biological controls on inter-annual variations in seasonal and diurnal cycles of ozone dry deposition velocity using nine years of hourly observations of eddy covariance ozone flux and concentration measurements at Harvard Forest, a northern mid-latitude temperate deciduous forest. We also use coincident eddy covariance water vapor flux and sensible heat flux and other micrometeorological measurements to infer stomatal conductance in order to separate the impacts of stomatal versus non-stomatal pathways on ozone deposition. There is a difference of approximately a factor of two between minimum and maximum monthly daytime mean ozone dry deposition velocities at Harvard Forest. The highest summertime mean ozone dry deposition velocities occur during 1998 and 1999 (0.72 cm/s), and similar seasonal and diurnal cycles occur in both years. The similar dry deposition velocities during these two years, however, may reflect compensation between different processes as mean daytime summertime stomatal conductance during 1998 is roughly 1.5 times higher than for 1999, suggesting large year-to-year variations in non-stomatal as well as stomatal uptake of ozone. We partition the onset and decline of the growing season each year into different periods using spring and fall phenology observations at Harvard Forest. Combining the dry deposition velocities across years during each phenological period, we find that

  17. Human occupation of northern Australia by 65,000 years ago.

    Clarkson, Chris; Jacobs, Zenobia; Marwick, Ben; Fullagar, Richard; Wallis, Lynley; Smith, Mike; Roberts, Richard G; Hayes, Elspeth; Lowe, Kelsey; Carah, Xavier; Florin, S Anna; McNeil, Jessica; Cox, Delyth; Arnold, Lee J; Hua, Quan; Huntley, Jillian; Brand, Helen E A; Manne, Tiina; Fairbairn, Andrew; Shulmeister, James; Lyle, Lindsey; Salinas, Makiah; Page, Mara; Connell, Kate; Park, Gayoung; Norman, Kasih; Murphy, Tessa; Pardoe, Colin


    The time of arrival of people in Australia is an unresolved question. It is relevant to debates about when modern humans first dispersed out of Africa and when their descendants incorporated genetic material from Neanderthals, Denisovans and possibly other hominins. Humans have also been implicated in the extinction of Australia's megafauna. Here we report the results of new excavations conducted at Madjedbebe, a rock shelter in northern Australia. Artefacts in primary depositional context are concentrated in three dense bands, with the stratigraphic integrity of the deposit demonstrated by artefact refits and by optical dating and other analyses of the sediments. Human occupation began around 65,000 years ago, with a distinctive stone tool assemblage including grinding stones, ground ochres, reflective additives and ground-edge hatchet heads. This evidence sets a new minimum age for the arrival of humans in Australia, the dispersal of modern humans out of Africa, and the subsequent interactions of modern humans with Neanderthals and Denisovans.

  18. Relations globales entre sédimentation de black shales océaniques et dépôts subséquents de phosphates. L'exemple du Crétacé moyen-supérieur de l'Atlantique centre et nord et du Crétacé supérieur-Eocène de la bordure ouest et nord du bouclier Africano-arabe Global Relations Between the Sedimentation of Oceanic Black Shales and Subsequent Phosphate Deposits. Example of the Middle-Upper Cretaceous in the Central and Northern Atlantic and of the Upper Cretaceous-Eocene on the Western and Northern Edges of the African-Arabian Shield

    Busson G.


    contrepartie en phosphore. Les deux phénomènes apparaissent parfaitement complémentaires et ils s'éclairent mutuellement : le phosphore aurait été capitalisé dans les mers à black shales euxiniques de l'Atlantique; puis, lors de l'établissement des premières circulations, il aurait été recyclé sur les plates-formes épicontinentales bordant l'est de cet océan. La discussion porte sur l'ajustement chronologique des deux phénomènes et sur l'interprétation des phosphates téthysiens (Europe, Proche-Orient, etc. dans la perspective des mécanismes proposés. Loin des explications unifactorielles, on souligne la conjonction de facteurs responsables de ce phénomène phosphaté ainsi que de son âge et de ses modalités d'expression. On a global scale, the large-scale accumulations of sedimentary phosphorites seem to be irregularly distributed in time. The ones from the Upper Cretaceous- Eocene on the western and northern edges of the African-Arabian shield are quantitatively exceptional and are interesting because of the ideas they suggest as to a global mechanism. First of all, some present-day oceanographic data are emphasized - movement of phosphate-containing material towards and inside the ocean, distribution of phosphates in oceanic water masses and especially in euxinic waters. The several theories formely proposed to explain the episodic nature of phosphate sedimentation are reviewed and criticized (Strakhov, Fischer, Arthur, Sheldon, etc. . Then the breakdown by countries of the amounts of phosphates deposited in part of the Mesogean and Atlantic realms is given. This causes us to focus our attention on the Moroccan phosphates which are by far the most abundant and are situated in a key position. Nevertheless, it is recalled that the dual latitudinal evolution in the Cretaceous and Paleogene, from the north towards the south in the present northern hemisphere, and from the south towards the north in the present southern hemisphere, makes purely latitudinal

  19. Atmospheric deposition of polycyclic aromatic hydrocarbons (PAHs) in Shanghai: the spatio-temporal variation and source identification

    Cheng, Chen; Bi, Chunjuan; Wang, Dongqi; Yu, Zhongjie; Chen, Zhenlou


    This study investigated the dry and wet deposition fluxes of atmospheric polycyclic aromatic hydrocarbons (PAHs) in Shanghai, China. The flux sources were traced based on composition and spatio-temporal variation. The results show that wet deposition concentrations of PAHs ranged from 0.07 to 0.67 mg·L-1 and were correlated with temperature (PPAHs concentrations ranged from 3.60-92.15 mg·L-1 and were higher in winter and spring than in summer and autumn. The annual PAH average fluxes were 0.631 mg·m-2·d-1 and 4.06 mg·m-2·d-1 for wet and dry deposition, respectively. The highest wet deposition of PAH fluxes was observed in summer, while dry deposition fluxes were higher in winter and spring. Atmospheric PAHs were deposited as dry deposition in spring and winter, yet wet deposition was the dominant pathway during summer. Total atmospheric PAH fluxes were higher in the northern areas than in the southern areas of Shanghai, and were also observed to be higher in winter and spring. Annual deposition of atmospheric PAHs was about 10.8 t in across all of Shanghai. Wet deposition of PAHs was primarily composed of two, three, or four rings, while dry deposition of PAHs was composed of four, five, or six rings. The atmospheric PAHs, composed of four, five, or six rings, primarily existed in the form of particulates. Coal combustion and vehicle emissions were the dominant sources of PAH in the observed area of downtown Shanghai. In suburban areas, industrial pollution, from sources such as coke oven, incinerator, and oil fired power plant, was as significant as vehicle emissions in contributing to the deposition of PAHs.

  20. Geology and recognition criteria for veinlike uranium deposits of the lower to middle Proterozoic unconformity and strata-related types. Final report

    Dahlkamp, F.J.; Adams, S.S.


    The discovery of the Rabbit Lake deposit, Saskatchewan, in 1968 and the East Alligator Rivers district, Northern Territory, Australia, in 1970 established the Lower-Middle Proterozoic veinlike-type deposits as one of the major types of uranium deposits. The term veinlike is used in order to distinguish it from the classical magmatic-hydrothermal vein or veintype deposits. The veinlike deposits account for between a quarter and a third of the Western World's proven uranium reserves. Lower-Middle Proterozoic veinlike deposits, as discussed in this report include several subtypes of deposits, which have some significantly different geologic characteristics. These various subtypes appear to have formed from various combinations of geologic processes ranging from synsedimentary ur