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Sample records for cenozoic ocean silica

  1. Late Cenozoic Paleoceanography of the Central Arctic Ocean

    International Nuclear Information System (INIS)

    The Arctic Ocean is the smallest and perhaps least accessible of the worlds oceans. It occupies only 26% of the global ocean area, and less than 10% of its volume. However, it exerts a disproportionately large influence on the global climate system through a complex set of positive and negative feedback mechanisms directly or indirectly related to terrestrial ice and snow cover and sea ice. Increasingly, the northern high latitude cryosphere is seen as an exceptionally fragile part of the global climate system, a fact exemplified by observed reductions in sea ice extent during the past decades [2]. The paleoceanographic evolution of the Arctic Ocean can provide important insights into the physical forcing mechanisms that affect the form, intensity and permanence of ice in the high Arctic, and its sensitivity to these mechanisms in vastly different climate states of the past. However, marine records capturing the late Cenozoic paleoceanography of the Arctic are limited - most notably because only a single deep borehole exists from the central parts of this Ocean. This paper reviews the principal late Cenozoic (Neogene/Quaternary) results from the Arctic Coring Expedition to the Lomonosov Ridge and in light of recent data and observations on modern sea ice, outlines emerging questions related to three main themes: 1) the establishment of the 'modern' Arctic Ocean and the opening of the Fram Strait 2) the inception of perennial sea ice 3) The Quaternary intensification of Northern Hemisphere glaciations.

  2. ACEX: A First Look at Arctic Ocean Cenozoic History

    Science.gov (United States)

    Moran, K.; Backman, J.

    2004-12-01

    The first Integrated Ocean Drilling Program mission specificplatform expedition (ACEX - Arctic Coring Expedition) drilled and recovered core from five holes at four sites through Cenozoic sediments draping the crest of the Lomonosov Ridge in the central Arctic Ocean. Coring continued into the underlying Cretaceous sedimentary bedrock. Sites are located only a few nautical miles apart along a single seismic line (AWI-91090), showing an identical and coherent Cenozoic seismostratigraphy. Preliminary results from shipboard investigations of core-catcher-based bio- and lithostratigraphy, pore water analyses and core logger data describe a thick (~160 m) middle Miocene through Pleistocene sequence that shows large amplitude, cyclic variability in the density, magnetic susceptibility and acoustic velocity of the sediments. Sediments are largely carbonate free. Pleistocene sedimentation rates are close to 3 cm/ka, whereas Pliocene sediments are by-and-large missing. A sharp change in physical properties at ~200 m defines the transition into a 200+ m thick Paleogene sequence that is initially dominated by large numbers of dinoflagellate cysts. The early Miocene, Oligocene and late Eocene appear to be largely missing in a hiatus. However, a 32 m thick interval separates the overlying middle Miocene from the underlying middle Eocene and presumably preserves some of the early Neogene and late Paleogene sections. Dinoflagellate cysts, diatoms, ebridians and silicoflagellates are common to abundant in the middle Eocene section, which bottoms in a spectacular layer showing massive occurrences of glochidia and massulae (megaspores) of the freshwater hydropterid fern Azolla (duckweed) at the early/middle Eocene boundary (~306 m), suggesting strongly reduced surface water salinity or perhaps even a brief episode of fresh water conditions at the surface. Biosilica is not present prior to the late early Eocene (~320 m). The (sub-) tropical dinoflagellate species Apectodinium augustum

  3. Silica burp in the Eocene ocean

    Science.gov (United States)

    McGowran, Brian

    1989-09-01

    The Eocene was a time of greatly increased silica accumulation in the ocean, and the peak was in the early middle Eocene at about 50 Ma. The responsible geohistorical configuration included the following elements: extensive volcanism about 4 m.y. earlier, as part of the Chron 24 plate reorganization; early Eocene warming, with deep weathering to high latitudes and accumulation of the released silica in a sluggish ocean; and sharp cooling in the earliest middle Eocene, stimulating oceanic upwelling and biosilicification. It is possible, on the evidence of carbon and oxygen isotopic patterns, that the trigger for the exhalation of silica was a reverse greenhouse effect.

  4. History of oceanic front development in the New Zealand sector of the Southern Ocean during the Cenozoic: a synthesis

    International Nuclear Information System (INIS)

    The New Zealand sector of the Southern Ocean (NZSSO) has opened about the Indian-Pacific spreading ridge throughout the Cenozoic. Today the NZSSO is characterised by broad zonal belts of antarctic (cold), subantarctic (cool), and subtropical (warm) surface-water masses separated by prominent oceanic fronts: the Subtropical Front (STF) c. 43 degrees S, Subantarctic Front (SAF) c. 50 degrees S, and Antarctic Polar Front (AAPF) c. 60 degrees S. Despite a meagre database, the broad pattern of Cenozoic evolution of these fronts is reviewed from the results of Deep Sea Drilling Project-based studies of sediment facies, microfossil assemblages and diversity, and stable isotope records, as well as from evidence in onland New Zealand Cenozoic sequences. Results are depicted schematically on seven paleogeographic maps covering the NZSSO at 10 m.y. intervals through the Cenozoic. During the Paleocene and most of the Eocene (65-35 Ma), the entire NZSSO was under the influence of warm to cool subtropical waters, with no detectable oceanic fronts. In the latest Eocene (c. 35 Ma), a proto-STF is shown separating subantarctic and subtropical waters offshore from Antarctica, near 65 degrees S paleolatitude. During the earliest Oligocene, this front was displaced northwards by development of an AAPF following major global cooling and biotic turnover associated with ice sheet expansion to sea level on East Antarctica. Early Oligocene full opening (c. 31 Ma) of the Tasmanian gateway initiated vigorous proto-circum-Antarctic flow of cold/cool waters, possibly through a West Antarctic seaway linking the southern Pacific and Atlantic Oceans, including detached northwards 'jetting' onto the New Zealand plateau where condensation and unconformity development was widespread in cool-water carbonate facies. Since this time, a broad tripartite division of antarctic, subantarctic, and subtropical waters has existed in the NZSSO, including possible development of a proto-SAF within the

  5. Cenozoic Seawater Sr/Ca ratios: Implications for coral reef development through ocean de-acidification

    Science.gov (United States)

    Sosdian, S. M.; Grossman, E. L.; Lear, C. H.; Tao, K.; Rosenthal, Y.

    2010-12-01

    Records of seawater chemistry help constrain the temporal variation in geochemical processes that impact the global carbon cycle and global climate across Earth’s history. To date, various attempts to reconstruct Cenozoic seawater Sr/Ca ratios have produced markedly different results, with estimated Paleogene seawater Sr/Ca ranging from ~50% higher than today to 70% lower. We reconstruct seawater Sr/Ca using Eocene to Pliocene fossil mollusks collected from US Gulf Coast (Mississippi, Alabama, and Florida). We use Conus spp. and Turritella, taxa for which the Sr/Ca distribution coefficients have been determined as a function of temperature in modern specimens [1, 2]. Specimens were serially sampled perpendicular to growth to produce seasonal records of Sr/Ca. Fossil Conus shells show pronounced seasonal Sr/Ca cycles with a strong inverse correlation between Sr/Ca and δ18O, similar to those observed in modern specimens [1]. The fossil Turritella also show similar Sr/Ca cyclicity as modern specimens [2]. We calculate seawater Sr/Ca ratios using our Sr/Ca record, modern Sr/Ca-temperature calibrations for Conus and Turritella [1, 2], and a paleotemperature record based on oxygen isotopes from the same samples [3]. Seawater Sr/Ca increased from ~11.5 to 13.9 mmol/mol between the mid-Eocene (42 Ma) and early Oligocene (33 Ma) and decreased substantially from the mid-Miocene (11 mmol/mol) to the Pliocene (9 mmol/mol) and modern (8.5 mmol/mol). A mass balance model of variations in seawater Sr concentrations suggests a long-term decrease through the Neogene, which we attribute to a significant increase in the proportion of aragonite versus calcite deposition in shallow waters. The largest change is coincident with the proliferation of coral reefs, which occurred after the calcite-aragonite sea transition, and was likely ultimately driven by ocean de-acidification. [1] Sosdian et al. (2006) Geochemistry, Geophysics, Geosystems (G3) 7, Q11023, doi:10.1029/2005GC001233; [2

  6. The morphostructure of the atlantic ocean floor its development in the meso-cenozoic

    CERN Document Server

    Litvin, V M

    1984-01-01

    The study of the topography and structure of the ocean floor is one of the most important stages in ascertaining the geological structure and history of development of the Earth's oceanic crust. This, in its turn, provides a means for purposeful, scientifically-substantiated prospecting, exploration and development of the mineral resources of the ocean. The Atlantic Ocean has been geologically and geophysically studied to a great extent and many years of investigating its floor have revealed the laws governing the structure of the major forms of its submarine relief (e. g. , the continental shelf, the continental slope, the transition zones, the ocean bed, and the Mid-Oceanic Ridge). The basic features of the Earth's oceanic crust structure, anomalous geophysical fields, and the thickness and structure of its sedimentary cover have also been studied. Based on the investigations of the Atlantic Ocean floor and its surrounding continents, the presently prevalent concept of new global tectonics has appeared. A g...

  7. The relationship between the growth process of the ferromanganese crusts in the Pacific seamount and Cenozoic ocean evolvement

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Base on the Os isotope stratigraphy together with the empirical growth rate models using Co concentrations, the growth ages of the ferromanganese crusts MHD79 and MP3D10 distributed in the seamount of Pacific are confirmed. Through the contrast and research on the previous achievements including ODP Leg 144 and the crusts CD29-2, N5E-06 and N1-15 of the seamount of the Central Pacific, the uniform five growth and growth hiatus periods of them are found, and closely related to the Cenozoic ocean evolvement process. In the Paleocene Carbon Isotope Maximum (PCIM), the rise of the global ocean productivity promoted the growth of the seamount crust; the first growth hiatus (I) of the ferromanganese crust finished. In the Paleocene-Eocene Thermal Maximum (PETM), though the vertical exchange of seawater was weakened, the strong terrestrial chemical weathering led to the input of a great amount of the terrigenous nutrients, which made the bioproductivity rise, so there were no crust hiatuses. During 52-50 Ma, the Early Eocene Optimum Climate (EECO), the two poles were warm, the latitudinal temperature gradient was small, the wind-driven sea circulation and upwelling activity were weak, the terrestrial weathering was also weakened, the open ocean bioproductivity decreased, and the ferromanganese crust had growth hiatus again (II). From early Middle Eocene-Late Eocene, Oligocene, it was a long-term gradually cooling process, the strengthening of the sea circulation and upwelling led to a rise of bioproductivity, and increase of the content of the hydrogenous element Fe, Mn and Co and the biogenous element Cu, Zn, so that was the most favorable stage for the growth of ferromanganese crust (growth periods III and IV) in the studied area. The hiatus III corresponded with the Eocene-Oligocene boundary, is inferred to relate with the global climate transformation, celestial body impact event in the Eocene-Oligocene transition. From the early to the middle Miocene, a large

  8. The relationship between the growth process of the ferromanganese crusts in the Pacific seamount and Cenozoic ocean evolvement

    Institute of Scientific and Technical Information of China (English)

    DING Xuan; GAO LianFeng; FANG NianQiao; QU Wendun; LIU Jian; LI JiangShan

    2009-01-01

    Base on the Os Isotope stratigraphy together with the empirical growth rate models using Co concentrations, the growth ages of the ferromanganese crusts MHD79 and MP3D10 distributed in the seamount of Pacific are confirmed. Through the contrast and research on the previous achievements including ODP Leg 144 and the crusts CD29-2, N5E-06 and N1-15 of the seamount of the Central Pacific,the uniform five growth and growth hiatus periods of them are found, and closely related to the Cenozoic ocean evolvement process. In the Paleocene Carbon Isotope Maximum (PClM), the rise of the global ocean productivity promoted the growth of the seamount crust; the first growth hiatus (Ⅰ) of the ferromanganese crust finished. In the Paleocene-Eocene Thermal Maximum (PETM), though the vertical exchange of seawater was weakened, the strong terrestrial chemical weathering led to the input of a great amount of the terrigenous nutrients, which made the bioproductivity rise, so there were no crust hiatuses. During 52-50 Me, the Early Eocene Optimum Climate (EECO), the two poles were warm, the latitudinal temperature gradient was small, the wind-driven sea circulation and upwelling activity were weak, the terrestrial weathering was also weakened, the open ocean bioproductivity decreased, and the ferromanganese crust had growth hiatus again (Ⅱ). From early Middle Eocene-Late Eocene, Oligocene,it was a long-term gradually cooling process, the strengthening of the sea circulation and upweUing led to a rise of bioproductivity, and increase of the content of the hydrogenous element Fe, Mn and Co and the biogenous element Cu, Zn, so that was the most favorable stage for the growth of ferromanganese crust (growth periods Ⅲ and IV) in the studied area. The hiatus Ⅲ corresponded with the Eocene-Oligocene boundary, is inferred to relate with the global climate transformation, celestial body impact event in the Eocene-Oligocene transition. From the early to the middle Miocene, a large

  9. Deep-ocean record of major late Cenozoic rhyolitic eruptions from New Zealand

    International Nuclear Information System (INIS)

    A 12 m.y. record of large rhyolitic eruptions from the Coromandel (CVZ) and Taupo (TVZ) volcanic zones of New Zealand is contained in cores retrieved by Leg 181 of the Ocean Drilling Program. Site 1124, located 670 km from the TVZ, has a maximum of 134 macroscopic tephra layers with a total thickness of 13.18 m. These units, along with between 7 and 63 tephras from 3 other sites, were dated by a combination of magnetostratigraphy, biostratigraphy, isothermal plateau fission track determinations, and geochemical correlation with onshore tephra deposits. Additional time control for the last 3 m.y. came from an orbitally tuned, benthic, oxygen isotope profile for Site 1123. Results extend the incomplete terrestrial record of volcanism by placing the first major rhyolitic eruption in the CVZ at c. 12 Ma, c. 1.6-1 m.y. earlier than previously known. Tephras became thicker and more frequent from the late Miocene into the Quaternary - a trend that probably reflected (1) more frequent and intense volcanism and (2) reduced distances between sources and depositional sites on the evolving Australian/Pacific plate system. The passage from CVZ to Quaternary TVZ occurred without a major hiatus in activity, suggesting the transition was gradational. The ensuing TVZ volcanism was more continuous than known previously from the onshore geology. Ash dispersal was primarily eastward, highlighting the dominance of westerly winds since the middle Miocene. Nevertheless, variations in dispersal patterns suggest periodic changes in wind direction/speed and/or ejection of ash beyond the Roaring Forties. (author). 72 refs., 14 figs., 6 tabs

  10. Selectivity of silica species in ocean observed from seasonal and local changes

    Science.gov (United States)

    Tanaka, Miho; Takahashi, Kazuya; Nemoto, Masao; Horimoto, Naho

    2013-03-01

    Silicic acids, derived from SiO2 (silica), have several chemical forms in solution. Silica is a nutrient for diatoms, which are phytoplankton in oceans. Silica species can be used as a tracer to examine the behavior of silica in nature. The speciation for silica by FAB-MS (fast atom bombardment mass spectrometry) has been carried out for seawater samples from Tokyo Bay and Sagami Bay to investigate the seasonal and locational changes of the depth profiles of silica species. The species, [Si(OH)2O2Na+]-, [Si2(OH)5O2]- ([dimer]-), [Si2(OH)4O3Na+]-, [Si(OH)7O5-] ([cyclic tetramer]-), [Si4(OH)6O6Na+]-, [Si(OH)9O]- ([linear tetramer]-) and [Si4(OH)8O5Na+]- were mainly identified by FAB-MS. The seasonal and locational changes and the reproducibility of depth profiles of silica species were determined from October 2001 to July 2002. The depth profile of the ratio of linear tetramer to cyclic tetramer reflects the activity of diatoms, implying that the linear tetramer is the preferred "food" for diatoms. In particular, the depth profile for the ratio of linear tetramer to cyclic tetramer exhibits a critical changes that depend on the season. Furthermore, the depth profiles for the samples from Sagami Bay (open ocean) indicate that seawater is easily exchanged by ocean currents (the Japan Current). Thus, silica speciation by FAB-MS can give us a new tracer indicating the characteristics of the seawater budget, which change with depth, season and ocean locality.

  11. New aero-gravity results from the Arctic: Linking the latest Cretaceous-early Cenozoic plate kinematics of the North Atlantic and Arctic Ocean

    DEFF Research Database (Denmark)

    Døssing, Arne; Hopper, J.R.; Olesen, Arne Vestergaard;

    2013-01-01

    The tectonic history of the Arctic Ocean remains poorly resolved and highly controversial. Details regarding break up of the Lomonosov Ridge from the Barents-Kara shelf margins and the establishment of seafloor spreading in the Cenozoic Eurasia Basin are unresolved. Significantly, the plate...... tectonic evolution of the Mesozoic Amerasia Basin is essentially unknown. The Arctic Ocean north of Greenland is at a critical juncture that formed at the locus of a Mesozoic three-plate setting between the Lomonosov Ridge, Greenland, and North America. In addition, the area is close to the European plate......, resulting in complicated interactions between all these areas that are difficult to resolve. In 2009, the 550,000 km2 LOMGRAV aero-geophysical survey produced the first collocated gravity and magnetic measurements over the area, significantly increasing the data coverage. We present an interpretation of a...

  12. Recycling of oceanic crust from a stagnant slab in the mantle transition zone: Evidence from Cenozoic continental basalts in Zhejiang Province, SE China

    Science.gov (United States)

    Li, Yan-Qing; Ma, Chang-Qian; Robinson, Paul T.; Zhou, Qin; Liu, Ming-Liang

    2015-08-01

    Cenozoic continental basalts from Zhejiang Province, southeast China are tholeiitic to weakly alkalic in composition, with moderate MgO contents (6-11 wt.%) and an average Mg# of 62. They display typical OIB-like trace element features, including enrichment in most incompatible elements, both LILE and LREE, and negative K, Pb, Zr, Hf anomalies. In particular, they are characterized by high Fe/Mn (73 ± 5), La/Yb (19 ± 6) and Nb/Ta (18.8 ± 0.4) ratios, which can be attributed to the presence of residual clinopyroxene, garnet and rutile in the mantle source. Based on these minerals, the following hybrid source rocks are hypothesized: garnet pyroxenite/eclogite and peridotite. Clinopyroxene-liquid thermobarometry indicates clinopyroxene crystallization temperatures of > 1257 °C. This is higher than the assumed temperature at the base of the sub-continental lithospheric mantle (SCLM) (~ 1220 °C) beneath Zhejiang, thus the magmas were presumably derived from the asthenosphere. Some typical geochemical features such as negative K, Pb anomalies, positive Ba, Sr, Nb, Ta anomalies and the extremely high Os isotopic signatures, suggest participation of EM-like mantle sources, indicative of ancient subducted oceanic crust. (87Sr/86Sr)i (0.7037-0.7046) and 143Nd/144Nd (0.512832-0.512990) isotope ratios point to the presence of mixed components in the source region, i.e., DMM, EM1 and EM2. Recent seismic tomographic images of the mantle beneath Zhejiang suggest the presence of a subducted slab of oceanic lithosphere in the transition zone. Based on the combined geophysical and geochemical evidence, we propose that the major source of the Zhejiang basaltic magmas was the ancient subducted oceanic slab in the transition zone with an EM-like signature. The other magma sources include depleted asthenospheric peridotite possessing a DMM-like signature. The dynamics of this upwelling hybrid magma was apparently related to westward subduction of the Pacific plate underneath the

  13. An atmosphere-ocean GCM modelling study of the climate response to changing Arctic seaways in the early Cenozoic.

    Science.gov (United States)

    Roberts, C. D.; Legrande, A. N.; Tripati, A. K.

    2008-12-01

    The report of fossil Azolla (a freshwater aquatic fern) in sediments from the Lomonosov Ridge suggests low salinity conditions occurred in the Arctic Ocean in the early Eocene. Restricted passages between the Arctic Ocean and the surrounding oceans are hypothesized to have caused this Arctic freshening. We investigate this scenario using a water-isotope enabled atmosphere-ocean general circulation model with Eocene boundary conditions including 4xCO2, 7xCH4, altered bathymetry and topography, and an estimated distribution of Eocene vegetational types. In one experiment, oceanic exchange between the Arctic Ocean and other ocean basins was restricted to two shallow (~250 m) seaways, one in the North Atlantic, the Greenland-Norwegian seaway, and the second connecting the Arctic Ocean with the Tethys Ocean, the Turgai Straits. In the restricted configuration, the Greenland-Norwegian seaway was closed and exchange through the Turgai Straits was limited to a depth of ~60 m. The simulations suggest that the severe restriction of Arctic seaways in the early Eocene may have been sufficient to freshen Arctic Ocean surface waters, conducive to Azolla blooms. When exchange with the Arctic Ocean is limited, salinities in the upper several hundred meters of the water column decrease by ~10 psu. In some regions, surface salinity is within 2-3 psu of the reported maximum modern conditions tolerated by Azolla (~5 psu). In the restricted scenario, salt is stored preferentially in the North Atlantic and Tethys oceans, resulting in enhanced meridional overturning, increased poleward heat transport in the North Atlantic western boundary current, and warming of surface and intermediate waters in the North Atlantic by several degrees. Increased sensible and latent heat fluxes from the North Atlantic Ocean, combined with a reduction in cloud albedo, also lead to an increase in surface air temperature of over much of North America, Greenland and Eurasia. Our work is consistent with

  14. Silicon pool dynamics and biogenic silica export in the Southern Ocean inferred from Si-isotopes

    Directory of Open Access Journals (Sweden)

    F. Fripiat

    2011-09-01

    Full Text Available Silicon isotopic signatures (δ30Si of water column silicic acid (Si(OH4 were measured in the Southern Ocean, along a meridional transect from South Africa (Subtropical Zone down to 57° S (northern Weddell Gyre. This provides the first reported data of a summer transect across the whole Antarctic Circumpolar Current (ACC. δ30Si variations are large in the upper 1000 m, reflecting the effect of the silica pump superimposed upon meridional water transfer across the ACC: the transport of Antarctic surface waters northward by a net Ekman drift and their convergence and mixing with warmer upper-ocean Si-depleted waters to the north. Using Si isotopic signatures, we determine different mixing interfaces: the Antarctic Surface Water (AASW, the Antarctic Intermediate Water (AAIW, and thermoclines in the low latitude areas. The residual silicic acid concentrations of end-members control the δ30Si alteration of the mixing products and with the exception of AASW, all mixing interfaces have a highly Si-depleted mixed layer end-member. These processes deplete the silicic acid AASW concentration northward, across the different interfaces, without significantly changing the AASW δ30Si composition. By comparing our new results with a previous study in the Australian sector we show that during the circumpolar transport of the ACC eastward, the δ30Si composition of the silicic acid pools is getting slightly, but significantly lighter from the Atlantic to the Australian sectors. This results either from the dissolution of biogenic silica in the deeper layers and/or from an isopycnal mixing with the deep water masses in the different oceanic basins: North Atlantic Deep Water in the Atlantic, and Indian Ocean deep water in the Indo-Australian sector. This isotopic trend is further transmitted to the subsurface waters, representing mixing interfaces between the surface and deeper layers.

  15. Continental erosion and the Cenozoic rise of marine diatoms

    Science.gov (United States)

    Cermeño, Pedro; Falkowski, Paul G.; Romero, Oscar E.; Schaller, Morgan F.; Vallina, Sergio M.

    2015-04-01

    Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid relative to other siliceous plankton such as radiolarians, which evolved by reducing the weight of their silica test. Here we use a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, we calculate changes in the input flux of silicic acid to the oceans. Our results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 My and suggest an increase in the strength and efficiency of the oceanic biological pump over this period.

  16. Biogenic silica and organic carbon in sediments from the Pacific sector of the Southern Ocean

    International Nuclear Information System (INIS)

    Four cores, collected during the 1995/96 Italian Antarctic cruise and located north and south of the Polar Front, provided both qualitative and quantitative information about changes of the sediment settings driven by climate changes. Biogenic silica and organic carbon flux variations and sedimentological analyses allow us to make inferences about the fluctuation of the Polar Front during the last climate cycles: the records of our cores Anta96-1 and Anta96-16 account for fluctuations of the Polar Front of at least 5 degrees with respect to the present position, with a concomitant movement of the Marginal Ice Zone. The very low accumulation rates at the study sites are probably due to the scarce availability of micronutrients. In the area south of the Polar Front, sediment accumulation, after a decrease, appears constant during the last 250,000 yr. A subdivision in glacial/interglacial stages has been proposed, which permits the identification of the warm stage 11, which is particularly important in the Southern Ocean. (author). 13 refs., 5 figs

  17. Silica-poor, mafic alkaline lavas from ocean islands and continents: Petrogenetic constraints from major elements

    Indian Academy of Sciences (India)

    Shantanu Keshav; Gudmundur H Gudfinnsson

    2004-12-01

    Strongly silica-poor (ne-normative), mafic alkaline lavas generally represented by olivine nephelinites, nephelinites, melilitites, and olivine melilitites have erupted at various locations during Earth’s history. On the basis of bulk-rock Mg#, high concentrations of Na2O, TiO2, and K2O, and trace element geochemistry, it has been suggested that these lavas represent low-degree melts that have undergone little crystal fractionation en route to the surface. Many of these lavas also carry highpressure mantle material in the form of harzburgite, spinel lherzolite, and variants of websterite xenoliths, and rare garnet-bearing xenoliths. However, phenocryst phases instead indicate that these magmas cooled to variable extents during their passage. We note subtle, yet important, differences in terms of CaO, Al2O3, CaO/Al2O3, and CaO/MgO. High-pressure experimental melting studies in CMAS-CO3 (3–8GPa) and natural lherzolitic systems (3GPa) demonstrate that at an isobar increasing leads to a moderate decrease in CaO + MgO, whereas CaO/MgO and CaO/Al2O3 sharply decrease. Relatively high CaO/Al2O3 indicates melting in the presence of garnet (≥ 85km). Studies also demonstrate that CO2-bearing lherzolitic systems, when compared with anhydrous ones, also have higher CaO content in the coexisting melt at a given and . Comparison of the bulk-rock major-element chemistry of silica-poor, mafic alkaline lavas with experimentally determined high-pressure melts indicates that melting of anhydrous mantle lherzolite or garnet pyroxenite is not able to explain many of the major element systematics of the lavas. However, high-pressure partial melts of carbonated lherzolite have the right major element trends. Among ocean islands, lavas from Samoa and Hawaii are perhaps the products of very low degree of partial melting. Lavas from Gran Canaria and Polynesia represent products of more advanced partial melting. On continents, lavas from South Africa and certain localities in

  18. Biogenic silica in space and time in sediments of Central Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Pattan, J.N.; Gupta, S.M.; Mudholkar, A.V.; Parthiban, G.

    silica (30-35%) in the surface sediments from 11 degrees to 13 degrees S, may be due to higher productivity and better preservation of siliceous tests. The lowest biogenic silica at approximately 100 to 140 x 10 sup(3) y BP is suppressed with higher...

  19. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    Science.gov (United States)

    Lazarus, David; Barron, John; Renaudie, Johan; Diver, Patrick; Türke, Andreas

    2014-01-01

    Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂(18)O (climate) and carbon cycle records (∂(13)C, and 20-0 Ma pCO2). Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p.9, detrended r>.6, all prisk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls. PMID:24465441

  20. Spreading of water masses and regeneration of silica and sup(226)Ra in the Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    DileepKumar, M.; Yuan-Hui, Li

    The magnitudes of silica and sup(226) RA inputs to water (through particle regeneration, in situ, and from sediments) and the validity of observed Si and sup(226) Ra as tracers of water masses and advective processes were examined in the Indian...

  1. Cenozoic planktonic marine diatom diversity and correlation to climate change.

    Directory of Open Access Journals (Sweden)

    David Lazarus

    Full Text Available Marine planktonic diatoms export carbon to the deep ocean, playing a key role in the global carbon cycle. Although commonly thought to have diversified over the Cenozoic as global oceans cooled, only two conflicting quantitative reconstructions exist, both from the Neptune deep-sea microfossil occurrences database. Total diversity shows Cenozoic increase but is sample size biased; conventional subsampling shows little net change. We calculate diversity from a separately compiled new diatom species range catalog, and recalculate Neptune subsampled-in-bin diversity using new methods to correct for increasing Cenozoic geographic endemism and decreasing Cenozoic evenness. We find coherent, substantial Cenozoic diversification in both datasets. Many living cold water species, including species important for export productivity, originate only in the latest Miocene or younger. We make a first quantitative comparison of diatom diversity to the global Cenozoic benthic ∂(18O (climate and carbon cycle records (∂(13C, and 20-0 Ma pCO2. Warmer climates are strongly correlated with lower diatom diversity (raw: rho = .92, p.9, detrended r>.6, all p<.001, but only weakly over the earlier Cenozoic, suggesting increasingly strong linkage of diatom and climate evolution in the Neogene. Our results suggest that many living marine planktonic diatom species may be at risk of extinction in future warm oceans, with an unknown but potentially substantial negative impact on the ocean biologic pump and oceanic carbon sequestration. We cannot however extrapolate our my-scale correlations with generic climate proxies to anthropogenic time-scales of warming without additional species-specific information on proximate ecologic controls.

  2. Paleocene initiation of cenozoic uplift in Norway

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, S.B.; Paulsen, G.E.; Hansen, D.L.; Gemmer, L.; Clausen, O.R.; Jacobsen, B.H.; Balling, N.; Huuse, M.; Gallagher, K.

    2003-12-01

    The timing of Cenozoic surface uplift in NW Europe relies on the assumption that the sedimentary response in basins is synchronous with tectonic processes in the source areas. However, many of the phenomena commonly used to infer recent uplift may as well be a consequence of climate change and sea-level fall. The timing of surface uplift therefore remains unconstrained from the sedimentary record alone, and it becomes necessary to consider the constraints imposed by physically and geologically plausible tectonic mechanisms, which have a causal relation to an initiating agent. The gradual reversal of the regional stress field following the break-up produced minor perturbations to the thermal subsidence on the Norwegian Shelf and in the North Sea. Pulses of increased compression cannot be the cause of Cenozoic land surface uplift and accelerated Neogene basin subsidence. Virtually deformation-free regional vertical movements could have been caused by changes in the density column of the lithosphere and asthenosphere following the emplacement of the Iceland plume. A transient uplift component was produced as the plume displaced denser asthenosphere at the base of the lithosphere. This component decayed as the plume material cooled. Permanent uplift as a result of igneous underplating occurred in areas of a thin lithosphere (some Palaeozoic and Mesozoic basins) or for lithosphere under extension at the time of plume emplacement (the ocean-continent boundary). In areas of a thicker lithosphere (East Greenland, Scotland and Norway) plume emplacement may have triggered a Rayleigh-Taylor instability, causing partial lithospheric delamination and associated transient surface uplift at a decreasing rate throughout Cenozoic time. A possible uplift history for the adjacent land areas hence reads: initial transient surface uplift around the break-up time at 53 Ma caused by plume emplacement, and permanent tectonic uplift caused by lithospheric delamination and associated

  3. Early cenozoic differentiation of polar marine faunas.

    Directory of Open Access Journals (Sweden)

    J Alistair Crame

    Full Text Available The widespread assumption that the origin of polar marine faunas is linked to the onset of major global cooling in the Late Eocene-Early Oligocene is being increasingly challenged. The Antarctic fossil record in particular is suggesting that some modern Southern Ocean taxa may have Early Eocene or even Paleocene origins, i.e. well within the Early Cenozoic greenhouse world. A global analysis of one of the largest marine clades at the present day, the Neogastropoda, indicates that not only is there a decrease in the number of species from the tropics to the poles but also a decrease in the evenness of their distribution. A small number of neogastropod families with predominantly generalist trophic strategies at both poles points to the key role of seasonality in structuring the highest latitude marine assemblages. A distinct latitudinal gradient in seasonality is temperature-invariant and would have operated through periods of global warmth such as the Early Cenozoic. To test this concept a second global analysis was undertaken of earliest Cenozoic (Paleocene neogastropods and this does indeed show a certain degree of faunal differentiation at both poles. The Buccinidae, s.l. is especially well developed at this time, and this is a major generalist taxon at the present day. There is an element of asymmetry associated with this development of Paleocene polar faunas in that those in the south are more strongly differentiated than their northern counterparts; this can in turn be linked to the already substantial isolation of the southern high latitudes. The key role of seasonality in the formation of polar marine faunas has implications for contemporary ecosystem structure and stability.

  4. A Kungurian Oceanic Upwelling on Yangtze Platform:Evidenced byδ13Corg and Authigenic Silica in the Lower Chihsia Formation of Enshi Section in South China

    Institute of Scientific and Technical Information of China (English)

    Hao Yu; Hengye Wei

    2015-01-01

    The Late Paleozoic Ice Age across Carboniferous and Permian had a significant impact on the Kungurian (Upper Cisuralian series of Permian) Chihsia Formation in South China. This re-sulted in a unique interval with features such as the lack of reef in Chihsian limestone, widespread stinkstone and nodular/bedded chert. The Chihsia limestone (Kungurian stage) deposited during a time of cooling was resulted from oceanic upwelling. Here we present evidence for this upwelling using sev-eral geochemical analyses: bulk organic carbon isotope, biomarker molecular geochemical data, and authigenic silica of the stinkstone member in the lower Chihsia Formation of the Kuangurian stage from the Enshi Section in western Hubei Province, South China. The lower part of the stinkstone member shows a rapid organic carbon isotope excursion with a-3‰shift triggered by the upwelling of 13C-depleted bottom water. The concurrent rapid increasing of authigenic silica content resulted from the enhanced supply of dissolved silica in the upwelling water mass. This upwelling at the Enshi Section also led to relative high TOC content, accounting for the widespread stinkstone in the lower Chihsia Formation during the Kungurian stage in Permian.

  5. The Cenozoic Tectonic History of the Calabrian Orogen, Southern Italy

    OpenAIRE

    Shimabukuro, David Haruo

    2011-01-01

    The Cenozoic accretionary wedge of Calabria, Southern Italy, consists of several units of continental and oceanic affinity accreted beneath the former continental margin of the Sardinia-Corsica block. Each of these units bears the imprint of blueschist-facies metamorphism, indicating that it has been subducted to high-pressure/low-temperature conditions during the Alpine Orogeny. Structurally higher units, having been accreted first, record the early metamorphic history of the orogen; lower...

  6. Four hundred million years of silica biomineralization in land plants

    OpenAIRE

    Trembath-Reichert, Elizabeth; Wilson, Jonathan Paul; McGlynn, Shawn E.; Fischer, Woodward W.

    2015-01-01

    Biomineralization plays a fundamental role in the global silicon cycle. Grasses are known to mobilize significant quantities of Si in the form of silica biominerals and dominate the terrestrial realm today, but they have relatively recent origins and only rose to taxonomic and ecological prominence within the Cenozoic Era. This raises questions regarding when and how the biological silica cycle evolved. To address these questions, we examined silica abundances of extant members of early-diver...

  7. Petrogenesis of Late Cenozoic basalts from North Hainan Island: Constraints from melt inclusions and their host olivines

    Science.gov (United States)

    Liu, Jian-Qiang; Ren, Zhong-Yuan; Nichols, Alexander R. L.; Song, Mao-Shuang; Qian, Sheng-Ping; Zhang, Yan; Zhao, Pei-Pei

    2015-03-01

    Melt inclusions and their host olivines in basaltic lavas provide important information about the nature of their mantle source. We present the first analyzed chemical data of olivine-hosted melt inclusions in Cenozoic basalts from the North Hainan Island and report the discovery of both tholeiitic and alkalic melt inclusions in a single rock sample. Cenozoic basalts from the Hainan Island are predominantly tholeiites with only small amounts of alkali basalts. There is a much broader compositional variation in melt inclusions than whole rocks. Compared to partial melts of mantle peridotite, the Hainan basalts have lower CaO, Na2O/TiO2, CaO/Al2O3 and Co/Fe, and higher TiO2, FeO∗, Fe/Mn, Zn/Fe and Zn/Mn. The olivine phenocrysts from the Hainan basalts contain lower Ca and Mn, and higher Ni and Fe/Mn than those of olivines crystallized from partial melts of peridotite. Projections from or towards olivine into the plane CS-MS-A for melt inclusions and whole rocks with MgO >7.5 wt% imply that the residual minerals in the source of the tholeiites are mainly clinopyroxene and garnet, possibly with some orthopyroxene, while in the source of the alkali basalts they are dominated by clinopyroxene and garnet. This indicates that a pyroxenite component could serve as the source lithology of the Hainan basalts. The OIB-like trace element compositions, with Ba, Sr, Nb and Ta positive anomalies, and Th and U negative anomalies, of the Hainan basalts suggest that a recycled oceanic crust component was involved in the source of the Hainan basalts. Based on a CMAS projection of primary magma compositions of the whole rocks and melt inclusions, we infer that a stage-2 silica-deficient pyroxenite derived from melt-peridotite reaction or mechanical mixing between recycled oceanic crust and peridotite can serve as the source lithology. Partial melts derived from such a source can match the overall compositions of the Hainan basalts better than those of MORB-eclogite and fertile

  8. Application of sediment core modelling to interpreting the glacial-interglacial record of Southern Ocean silica cycling

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2007-07-01

    Full Text Available Sediments from the Southern Ocean reveal a meridional divide in biogeochemical cycling response to the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front in the Atlantic sector of the Southern Ocean, biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties provides an important model validation target for testing hypotheses of glacial-interglacial change against, particularly for understanding the causes of the concurrent variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand climates of the past by means of the mechanistic simulation of marine sediment core records. I find that a close match between model-predicted and observed down-core changes in sedimentary opal content can be achieved when changes in seasonal sea-ice extent are imposed, whereas the predicted sedimentary response to iron fertilization on its own is not consistent with sedimentary observations. The results of this sediment record model-data comparison supports previous inferences that the changing cryosphere is the primary driver of the striking features exhibited by the paleoceanographic record of this region.

  9. Uranium and thorium in Cenozoic basaltods of Kamchatka

    International Nuclear Information System (INIS)

    Regularities in distribution of radioactive elements (RAE) in basaltoids of Kamchatka have been analyzed. The RAE concentration in samples was determined by γ-spectrometric method. The results compared with the instrumental neutron-activation analysis data are found to be in agreement. Results of evaluating the average contents of U, Th and roch-forming elements in ce-- nozoic basaltoids are presented. The radiogeochemical data enable to associate the origin of the Kamchatka Cenozoic basaltoids with both fractional melting of the upper mantle depleted of radioactive elements and the development of magmatic chambers in submerged blocks of the Pre-Cretaceous melanocratic basement the composition of which is close to oceanic tholeiite

  10. Cenozoic Uplift, Erosion and Dynamic Support of Madagascar

    Science.gov (United States)

    Stephenson, Simon; White, Nicky

    2016-04-01

    The physiography of Madagascar is characterised by high-elevation but low-relief topography; 42% of the landscape is above 500 m in elevation. Eocene (marine) nummulitic (marine) limestones at elevations of ˜400 m above sea level and newly dated, emergent 125 ka coral reefs suggest that Madagascar has experienced differential vertical motions during Cenozoic times. Malagasy rivers are often deeply incised and contain steepened reaches, implying that they have responded to changes in regional uplift rate. However, low temperature thermochronology and 10Be derived erosion rates suggest that both Cenozoic and Recent average denudation rates have been low. Extensive laterite-capped, low-relief surfaces also suggest that there have been long periods of tectonic quiescence. In contrast, the modern landscape is characterised by erosional gullies (i.e. lavaka), with very high local erosion rates. To bridge the gap between this disparate evidence, we inverted 2566 longitudinal river profiles using a damped non-negative, least-squares linear inversion to determine the history of regional uplift. We used a simplified version of the stream power erosional law. River profiles were extracted from the 3 arc-second Shuttle Radar Topography Mission (SRTM) digital elevation model. Calibration of the stream power erosional law is based upon Cenozoic limestones and new radiometrically dated marine terraces. The residual misfit between observed and calculated river profiles is small. Results suggest that Malagasy topography grew diachronously by 1-2 km over the last 15-20 Ma. Calculated uplift and denudation are consistent with independent observations. Thus drainage networks contain coherent signals that record regional uplift. The resultant waves of incision are the principal trigger for modern erosional processes. Admittance calculations, the history of basaltic volcanism and nearby oceanic residual age-depth measurements all suggest that as much as 0.8 - 1.1 km of Cenozoic uplift

  11. Dynamic topography and the Cenozoic carbonate compensation depth

    Science.gov (United States)

    Campbell, S. M.; Moucha, R.; Raymo, M. E.; Derry, L. A.

    2015-12-01

    The carbonate compensation depth (CCD), the ocean depth at which the calcium carbonate accumulation rate goes to zero, can provide valuable insight into climatic and weathering conditions over the Cenozoic. The paleoposition of the CCD can be inferred from sediment core data. As the carbonate accumulation rate decreases linearly with depth between the lysocline and CCD, the CCD can be calculated using a linear regression on multiple sediment cores with known carbonate accumulation rates and paleodepths. It is therefore vital to have well-constrained estimates of paleodepths. Paleodepths are typically calculated using models of thermal subsidence and sediment loading and compaction. However, viscous convection-related stresses in the mantle can warp the ocean floor by hundreds of meters over broad regions and can also vary significantly over millions of years. This contribution to paleobathymetry, termed dynamic topography, can be calculated by modeling mantle flow backwards in time. Herein, we demonstrate the effect dynamic topography has on the inference of the late Cenozoic CCD with an example from the equatorial Pacific, considering sites from IODP Expeditions 320/321. The equatorial Pacific, given its large size and high productivity, is closely tied to the global carbon cycle. Accordingly, long-term changes in the equatorial Pacific CCD can be considered to reflect global changes in weathering fluxes and the carbon cycle, in addition to more regional changes in productivity and thermohaline circulation. We find that, when the dynamic topography contribution to bathymetry is accounted for, the equatorial Pacific CCD is calculated to be appreciably shallower at 30 Ma than previous estimates would suggest, implying a greater deepening of the Pacific CCD over the late Cenozoic.

  12. Algal constraints on the Cenozoic history of atmospheric CO2?

    Directory of Open Access Journals (Sweden)

    R. E. M. Rickaby

    2007-01-01

    Full Text Available An urgent question for future climate, in light of increased burning of fossil fuels, is the temperature sensitivity of the climate system to atmospheric carbon dioxide (pCO2. To date, no direct proxy for past levels of pCO2 exists beyond the reach of the polar ice core records. We propose a new methodology for placing an upper constraint on pCO2 over the Cenozoic based on the living geological record. Specifically, our premise is that the contrasting calcification tolerance of various extant species of coccolithophore to raised pCO2 reflects an "evolutionary memory" of past atmospheric composition. The different times of first emergence of each morphospecies allows an upper constraint of past pCO2 to be placed on Cenozoic timeslices. Further, our hypothesis has implications for the response of marine calcifiers to ocean acidification. Geologically "ancient" species, which have survived large changes in ocean chemistry, are likely more resilient to predicted acidification.

  13. Cenozoic carbon cycle imbalances and a variable weathering feedback

    Science.gov (United States)

    Caves, Jeremy K.; Jost, Adam B.; Lau, Kimberly V.; Maher, Kate

    2016-09-01

    The long-term stability of Earth's climate and the recovery of the ocean-atmosphere system after carbon cycle perturbations are often attributed to a stabilizing negative feedback between silicate weathering and climate. However, evidence for the operation of this feedback over million-year timescales and in response to tectonic and long-term climatic change remains scarce. For example, the past 50 million years of the Cenozoic Era are characterized by long-term cooling and declining atmospheric CO2 (pCO2). During this interval, constant or decreasing carbon fluxes from the solid Earth to the atmosphere suggest that stable or decreasing weathering fluxes are needed to balance the carbon cycle. In contrast, marine isotopic proxies of weathering (i.e., 87Sr/86Sr, δ7 Li , and 187Os/188Os) are interpreted to reflect increasing weathering fluxes. Here, we evaluate the existence of a negative feedback by reconstructing the imbalance in the carbon cycle during the Cenozoic using the surface inventories of carbon and alkalinity. Only a sustained 0.25-0.5% increase in silicate weathering is necessary to explain the long-term decline in pCO2 over the Cenozoic. We propose that the long-term decrease in pCO2 is due to an increase in the strength of the silicate weathering feedback (i.e., the constant of proportionality between the silicate weathering flux and climate), rather than an increase in the weathering flux. This increase in the feedback strength, which mirrors the marine isotope proxies, occurs as transient, 1 million year timescales remains invariant to match the long-term inputs of carbon. Over the Cenozoic, this results in stable long-term weathering fluxes even as pCO2 decreases. We attribute increasing feedback strength to a change in the type and reactivity of rock in the weathering zone, which collectively has increased the reactivity of the surface of the Earth. Increasing feedback strength through the Cenozoic reconciles mass balance in the carbon cycle with

  14. Analysing the Cenozoic depositional record

    DEFF Research Database (Denmark)

    Goledowski, Bartosz; Clausen, O.R.; Nielsen, S.B.

    between the global climate record (oxygen isotopes) and lithology variations on the Eocene-Oligocene transition in the eastern North Sea. Due to the strongly limited time resolution of low temperature thermochronology, the Cenozoic sedimentary record potentially provides the most detailed history of...... lower limit to erosion rate in source areas of the respective sedimentary bodies. The lower limit arises because some erosional products are transported out of the mapped area, and some erosion is caused by chemical dissolution. The development of the source areas will be modelled using surface process...... models. The matrix mass deposition history will be compared with the paleoclimate record (e.g. oxygen isotope curves) to see if the previously observed correlation in the eastern North Sea can be extended to other ages and locations.  ...

  15. Cenozoic Methane-Seep Faunas of the Caribbean Region.

    Directory of Open Access Journals (Sweden)

    Steffen Kiel

    Full Text Available We report new examples of Cenozoic cold-seep communities from Colombia, Cuba, the Dominican Republic, Trinidad, and Venezuela, and attempt to improve the stratigraphic dating of Cenozoic Caribbean seep communities using strontium isotope stratigraphy. Two seep faunas are distinguished in Barbados: the late Eocene mudstone-hosted 'Joes River fauna' consists mainly of large lucinid bivalves and tall abyssochrysoid gastropods, and the early Miocene carbonate-hosted 'Bath Cliffs fauna' containing the vesicomyid Pleurophopsis, the mytilid Bathymodiolus and small gastropods. Two new Oligocene seep communities from the Sinú River basin in Colombia consist of lucinid bivalves including Elongatolucina, thyasirid and solemyid bivalves, and Pleurophopsis. A new early Miocene seep community from Cuba includes Pleurophopsis and the large lucinid Meganodontia. Strontium isotope stratigraphy suggests an Eocene age for the Cuban Elmira asphalt mine seep community, making it the oldest in the Caribbean region. A new basal Pliocene seep fauna from the Dominican Republic is characterized by the large lucinid Anodontia (Pegophysema. In Trinidad we distinguish two types of seep faunas: the mudstone-hosted Godineau River fauna consisting mainly of lucinid bivalves, and the limestone-hosted Freeman's Bay fauna consisting chiefly of Pleurophopsis, Bathymodiolus, and small gastropods; they are all dated as late Miocene. Four new seep communities of Oligocene to Miocene age are reported from Venezuela. They consist mainly of large globular lucinid bivalves including Meganodontia, and moderately sized vesicomyid bivalves. After the late Miocene many large and typical 'Cenozoic' lucinid genera disappeared from the Caribbean seeps and are today known only from the central Indo-Pacific Ocean. We speculate that the increasingly oligotrophic conditions in the Caribbean Sea after the closure of the Isthmus of Panama in the Pliocene may have been unfavorable for such large

  16. Nevada Thickness of Cenozoic Deposits

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study of gravity data from Nevada is part of a statewide analysis of mineral resources. The main objective of the gravity study were: 1) to infer the structure...

  17. North Chilean forearc tectonics and cenozoic plate kinematics

    Science.gov (United States)

    Buddin, Tim S.; Stimpson, Ian G.; Williams, Graham D.

    1993-04-01

    The continental forearc of northern Chile has been subjected to contemporaneous extension and compression. Here, cross-sections constructed across the forearc are presented which show that since initial shortening, deformation of the forearc has occurred in two tectonically distinct areas. These inner and outer forearc areas are separated by the strain discontinuity of the Atacama fault system and the tectonically neutral Central Depression. The outer forearc, the Coastal Cordillera, exhibits extensional tectonics, with large (up to 300 m) normal fault scarps preserved. These faults cut the earlier thrusts responsible for the elevation of Jurassic rocks at the coast above their regional elevation. The normal faults have been re-activated, displacing Quaternary salt deposits in the Salar Grande. This re-activation of the basement faults is probably due to the subduction of anomalously thick oceanic crust, producing an isostatic imbalance in the outer forearc. In the inner forearc, cross-sections through the Sierra del Medio and Cordillera de Domeyko show that structures of the Pre-Cordillera are best explained by a thick-skinned thrust system, with localized thin-skinned tectonics controlled by evaporite detachment horizons. Current forearc deformation features indicate a strong degree of correlation between subduction zone geometry and forearc tectonics. The timing of Cenozoic tectonism also fits well with established plate motion parameters, and the spatial and temporal variation in the state of stress of the forearc shows a close relationship throughout the Cenozoic to the plate kinematics and morphology of the subducting Nazca plate.

  18. Cenozoic evolution of Neotethys and implications for the causes of plate motions

    OpenAIRE

    McQuarrie, N.; J. M. Stock; Verdel, C.; B. P. Wernicke

    2003-01-01

    Africa-North America-Eurasia plate circuit rotations, combined with Red Sea rotations and new estimates of crustal shortening in Iran define the Cenozoic history of the Neotethyan ocean between Arabia and Eurasia. The new constraints indicate that Arabia-Eurasia convergence has been fairly constant at 2 to 3 cm/yr since 56 Ma with slowing of Africa-Eurasia motion to

  19. A universal driver of macroevolutionary change in the size of marine phytoplankton over the Cenozoic

    OpenAIRE

    Finkel, Z. V.; Sebbo, J.; Feist-Burkhardt, S.; Irwin, A. J.; Katz, M. E.; Schofield, O. M. E.; Young, J. R.; Falkowski, P G

    2007-01-01

    The size structure of phytoplankton assemblages strongly influences energy transfer through the food web and carbon cycling in the ocean. We determined the macroevolutionary trajectory in the median size of dinoflagellate cysts to compare with the macroevolutionary size change in other plankton groups. We found the median size of the dinoflagellate cysts generally decreases through the Cenozoic. Diatoms exhibit an extremely similar pattern in their median size over time, even though species d...

  20. Cenozoic back-arc magmatism of the southern extra-Andean Patagonia (44° 30' - 52° S: A review of geochemical data and geodynamic interpretations

    Directory of Open Access Journals (Sweden)

    M. D'Orazio

    2004-12-01

    Full Text Available Huge amounts of basaltic s.l. lavas were persistently erupted along the eastern side of the Andean Cordillera, throughout Cenozoic time, forming extensive plateaus, hundreds of monogenetic scoria cones and other volcanic structures in a continental back-arc setting. The igneous products exposed in the southern sector of the extra-Andean Patagonia (44° 30' - 52° S are dominantly mafic with minor slightly evolved compositions and rare highly differentiated products. The many published chemical analyses of these rocks, indicate that the mafic lavas range from strongly silica - undersaturated basanites to oversaturated basaltic andesites, and that most of the lavas have a typical within-plate geochemical signature. However, a number of lavas, generally erupted in the western-central sectors of Patagonia, are characterized by different distributions of the incompatible elements with high LILE/HFSE and LREE/HFSE ratios. The REE distribution modelling suggests a low degree of melting of a deep (> 70 km garnet-bearing source for the alkaline magmas, and a higher degree of melting of the same source, or an even higher degree of melting of an enriched source, for the subalkaline magmas. The available Sr-Nd-Pb isotope compositions clearly attest to a major geographic variation: the southernmost lavas have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios with respect to those erupted to the north. On the whole, the Sr-Nd-Pb isotope compositions of the southern Patagonia lavas fall within the typical range of within-plate continental magmas; in addition the Pb isotope ratios fall in the range of the Southern Hemisphere Dupal Pb isotope anomaly. The geochemical variations of the southern Patagonia lavas are discussed in terms of different geochemical components: depleted and enriched sub-slab asthenosphere, enriched continental lithospheric mantle, continental crust and subducted materials. The geodynamic significance is interpreted with in the

  1. Characteristics and geological significance of olivine xenocrysts in Cenozoic volcanic rocks from western Qinling

    Institute of Scientific and Technical Information of China (English)

    SU Benxun; ZHANG Hongfu; XIAO Yan; ZHAO Xinmiao

    2006-01-01

    Cenozoic volcanic rocks from the Haoti, Dangchang County of the western Qinling Mountains, contain a few clearlyzoned olivines. These olivines are relatively big in grain sizes and usually have cracks or broken features. Their cores have similar compositions (Mg# = 90.4- 91.0) to those for the peridotitic xenoliths entrained in host volcanic rocks and their rims are close to the compositions of olivine phenocrysts (Mg# = 85.5 81.9). The CaO contents in these zoned olivines are lower than 0.1%. These features demonstrate that the clearly zoned olivines are xenocrysts and disaggregated from mantle peridotites. The zoned texture was the result of the interaction between the olivine and host magma. Available data show that the volcanic rocks would have been derived from the mantle source metasomatized by subducted hydrathermally-altered oceanic crust. The formation of these Cenozoic volcanic rocks was perhaps related to the rapid uplift of the Tibetan Plateau.

  2. Climate vs. tectonic induced variations in Cenozoic sediment supply from western Scandinavia

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.

    , faulting), tectonic disturbance related to ocean opening could be responsible for deposition of thick Paleocene wedges along the western coast of Norway. During subsequent Cenozoic periods domal structures in the Norwegian shelf are a proof for mild and protracted compression. However, depositional......) changed the erosional regime in western Scandinavia from fluvial (inefficient in tectonically stable settings, almost regardless of the amount of precipitation) to glacial. Glacial erosion is much more effective and is apparently able to outpace tectonic processes responsible for development of high...... topography. Therefore, a hypothesis of climate control on erosion and deposition during the Cenozoic history of western Scandinavia and adjacent sedimentary basins emerges. This theory is further supported by higher sediment input and pronounced progradation patterns of the Molo Formation (deposited during...

  3. Silica nephropathy.

    Science.gov (United States)

    Ghahramani, N

    2010-07-01

    Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2) is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600-7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents. PMID:23022796

  4. Silica Nephropathy

    Directory of Open Access Journals (Sweden)

    N Ghahramani

    2010-06-01

    Full Text Available Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2 is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600–7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

  5. The origin of Cenozoic magmatism of Libya

    Science.gov (United States)

    Stuart, Finlay; Masoud, Abdelmoniem; Mark, Darren

    2014-05-01

    Cenozoic volcanic provinces cover 66,000 km2 of Libya. The main fields are aligned NNW-SSE where NE-SW trending structural features intersect the main regional uplift structures. They form some of the largest volcanic provinces in North Africa yet despite their size and relative accessibility they have been not studied in detail. We are engaged in a new study of the geochemistry (major-trace elements, REE, Sr-Nd-Pb isotopes) and geochronology (40Ar/39Ar and cosmogenic 3He) of basalts of the four main Cenozoic volcanic provinces (Garian, Jabal Al Hasawinah, Jabal As Sawda and Jabal Al Haruj) in order to elucidate the nature and origin of the volcanism. The volcanic fields are dominated by basaltic flows, with small volumes of phonolites present at Garian and Jabal Al Hasawinah. Basalt piles rarely exceed a few 10s metres thick and the presence of NW-SE trending dykes on the periphery of most fields implies that existing flows probably represent the latest phase of a protracted volcanic history in each region. The basalts tend to be alkali to mildly alkali. Compositional variation is dominated by fractional crystalisation with little indication of crustal contamination. Trace element and REE support an origin in 5 to 15 % melts of heterogeneous sub-lithosphere mantle. Nd and Sr isotopic composition of the Garian and Jabal Al Haruj basalts (0.5128-0.51294 and 0.703-0.704) overlap the Cenozoic volcanism of southern Italy characterized by Etna and Pantelleria. This is typical of the common European asthenosphere mantle reservoir, and lacks the influence of enriched mantle present in other North African Cenozoic basalt provinces. There has been no systematic change in the location of volcanism with time that is indicative of plate movement over a fixed mantle hotspot. The major pulse of basaltic volcanism in the northern (Garian) and southern (Jabal Al Haruj) provinces overlap in time (6-1 Ma,) while Jabal Al Hasawinah and Jabal As Sawda basalts were erupted

  6. A synthesis of Cenozoic sedimentation in the North Sea

    DEFF Research Database (Denmark)

    Anell, Ingrid Anna Margareta; Thybo, Hans; Rasmussen, E.S.

    2012-01-01

    sediment influx into the North Sea during the Cenozoic is more complex than previously suggested clockwise rotation from early northwestern to late southern sources. The Shetland Platform supplied sediment continuously, although at varying rates, until the latest Cenozoic. Sedimentation around Norway...... changed from early Cenozoic influx from the southwestern margin, to almost exclusively from the southern margin in the Oligocene and from all of southern Norway in the latest Cenozoic. Thick Eocene deposits in the Central Graben are sourced mainly from a western and a likely southern source, indicating...

  7. Four hundred million years of silica biomineralization in land plants

    Science.gov (United States)

    Trembath-Reichert, Elizabeth; Wilson, Jonathan Paul; McGlynn, Shawn E.; Fischer, Woodward W.

    2015-04-01

    Biomineralization plays a fundamental role in the global silicon cycle. Grasses are known to mobilize significant quantities of Si in the form of silica biominerals and dominate the terrestrial realm today, but they have relatively recent origins and only rose to taxonomic and ecological prominence within the Cenozoic Era. This raises questions regarding when and how the biological silica cycle evolved. To address these questions, we examined silica abundances of extant members of early-diverging land plant clades, which show that silica biomineralization is widespread across terrestrial plant linages. Particularly high silica abundances are observed in lycophytes and early-diverging ferns. However, silica biomineralization is rare within later-evolving gymnosperms, implying a complex evolutionary history within the seed plants. Electron microscopy and X-ray spectroscopy show that the most common silica-mineralized tissues include the vascular system, epidermal cells, and stomata, which is consistent with the hypothesis that biomineralization in plants is frequently coupled to transpiration. Furthermore, sequence, phylogenetic, and structural analysis of nodulin 26-like intrinsic proteins from diverse plant genomes points to a plastic and ancient capacity for silica accumulation within terrestrial plants. The integration of these two comparative biology approaches demonstrates that silica biomineralization has been an important process for land plants over the course of their >400 My evolutionary history.

  8. Late Cretaceous and Cenozoic exhumation history of the Malay Peninsula

    Science.gov (United States)

    François, Thomas; Daanen, Twan; Matenco, Liviu; Willingshofer, Ernst; van der Wal, Jorien

    2015-04-01

    The evolution of Peninsular Malaysia up to the collisional period in the Triassic is well described but the evolution since the collision between Indochina and the Sukhothai Arc in Triassic times is less well described in the literature. The processes affecting Peninsular Malaysia during the Jurassic up to current day times have to explain the emplacement multiple intrusions (the Stong Complex, and the Kemahang granite), the Jurassic/Cretaceous onland basins, the Cenozoic offshore basins, and the asymmetric extension, which caused the exhumation of Taku Schists dome. The orogenic period in Permo-Triassic times, which also formed the Bentong-Raub suture zone, resulted in thickening of the continental crust of current day Peninsular Malaysia due to the collision of the Indochina continental block and the Sukhothai Arc, and is related to the subduction of oceanic crust once present between these continental blocks. The Jurassic/Cretaceous is a period of extension, resulting in the onland Jurassic/Cretaceous basins, synchronous melting of the crust, resulting in the emplacement Stong Complex and the Kemahang granite and thinning of the continental crust on the scale of the Peninsular, followed by uplift of the Peninsular. Different models can explain these observations: continental root removal, oceanic slab detachment, or slab delamination. These models all describe the melting of the lower crust due to asthenospheric upwelling, resulting in uplift and subsequent extension either due to mantle convective movements or gravitational instabilities related to uplift. The Cenozoic period is dominated by extension and rapid exhumation in the area as documented by low temperature thermocrological ages The extension in this period is most likely related to the subduction, which resumed at 45 Ma, of the Australian plate beneath the Eurasian plate after it terminated in Cretaceous times due to the collision of an Australian microcontinental fragment with the Sunda margin in the

  9. Cenozoic Mineralization in China, as a Key to Past Mineralization and a Clue to Future Prospecting

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Many Cenozoic metal deposits have been found during the past decade. Among them, the Fuwan Ag deposit in Guangdong is the largest Ag deposit in China. Besides, the largest Cu deposit of China in Yulong, Tibet, the largest Pb-Zn deposit of China in Jinding, Yunnan, and the largest Au deposit of China in Jinguashi,Taiwan, were also formed in the Cenozoic. Why so many important "present" deposits formed during such a short period of geological history is the key problem. The major reason is that different tectonic settings control different kinds of magmatic activity and mineralization at the same time. In southwestern China, porphyry-type Cu deposits such as Yulong were formed during the early stage of the Himalayan orogeny, sediment-hosted Pb-Zn deposits such as Jinding were formed within intermontane basins related to deep faults, and carbonatite-related deposits such as the Maoniuping REE deposit and alkalic magmatic rock-related deposits such as the Beiya Au deposit originated from the mantle source. In southeastern China, the Fuwan Ag deposit was related to continental rifting which was triggered by the mantle plume. In Taiwan, the Jinguashi Au deposit was formed during the subduction process of an oceanic plate beneath a continental plate. Besides, the features such as the diversification, inheritance, large size, deep source of metals and fluids of the Cenozoic (Present or Recent ) mineralization can be used as a key to the search for past deposits.

  10. Construction of the seawater 87Sr/86Sr curve for the Cenozoic and Cretaceous: supporting data

    International Nuclear Information System (INIS)

    We present the data used to construct the Cenozoic and Cretaceous portion of the Phanerozoic curve of seawater 87Sr/86Sr that had been given in summary form by W.H. Burke and coworkers. All Cenozoic samples (128) and 22 Cretaceous samples are foram-nannofossil oozes and limestones from DSDP cores distributed among 13 sites in the Atlantic, Pacific and Indian Oceans, and the Caribbean Sea. Non-DSDP Cretaceous samples (126) include limestone, anhydrite and phosphate samples from North America, Europe and Asia. Determination of the 87Sr/86Sr value of seawater at particular times in the past is based on comparison of ratios derived from coeval marine samples from widely separated geographic areas. The general configuration of the Cenozoic and Cretaceous curve appears to be strongly influenced by the history of plate interactions and sea-floor spreading. Specific rises and falls in the 87Sr/86Sr of seawater, however, may be caused by a variety of factors such as variation in lithologic composition of the crust exposed to weathering, configuration and topographic relief of continents, volcanic activity, rate of sea-floor spreading, extent of continental inundation by epeiric seas, and variations in both climate and paleo-oceanographic conditions. Many or all of these factors are probably related to global tectonic processes, yet their combined effect on the temporal variation of seawater 87Sr/86Sr can complicate a direct plate-tectonic interpretation for portions of the seawater curve. (Auth.)

  11. Late Palaeozoic to Cenozoic Evolution of the Black Sea-Southern Eastern Europe Region: A View from the Russian Platform

    OpenAIRE

    NIKISHIN, ANATOLY M.; Ziegler, Peter A

    2012-01-01

    A synthesis of the Late Palaeozoic to Cenozoic evolution of the Black Sea region and the southern parts of the East European Platform (EEP) is presented. During Carboniferous to Early Permian times the Cordillera-type Euxinus Orogen evolved along the southern margin of the EEP in response to progressive closure of the Rheic and Palaeotethys oceans and the accretion of Gondwana-derived continental terranes. Permian development of the north-dipping Palaeotethys subduction system along the south...

  12. Cenozoic stratigraphy of the Sahara, Northern Africa

    Science.gov (United States)

    Swezey, Christopher S.

    2009-01-01

    This paper presents an overview of the Cenozoic stratigraphic record in the Sahara, and shows that the strata display some remarkably similar characteristics across much of the region. In fact, some lithologies of certain ages are exceptionally widespread and persistent, and many of the changes from one lithology to another appear to have been relatively synchronous across the Sahara. The general stratigraphic succession is that of a transition from early Cenozoic carbonate strata to late Cenozoic siliciclastic strata. This transition in lithology coincides with a long-term eustatic fall in sea level since the middle Cretaceous and with a global climate transition from a Late Cretaceous–Early Eocene “warm mode” to a Late Eocene–Quaternary “cool mode”. Much of the shorter-term stratigraphic variability in the Sahara (and even the regional unconformities) also can be correlated with specific changes in sea level, climate, and tectonic activity during the Cenozoic. Specifically, Paleocene and Eocene carbonate strata and phosphate are suggestive of a warm and humid climate, whereas latest Eocene evaporitic strata (and an end-Eocene regional unconformity) are correlated with a eustatic fall in sea level, the build-up of ice in Antarctica, and the appearance of relatively arid climates in the Sahara. The absence of Oligocene strata throughout much of the Sahara is attributed to the effects of generally low eustatic sea level during the Oligocene and tectonic uplift in certain areas during the Late Eocene and Oligocene. Miocene sandstone and conglomerate are attributed to the effects of continued tectonic uplift around the Sahara, generally low eustatic sea level, and enough rainfall to support the development of extensive fluvial systems. Middle–Upper Miocene carbonate strata accumulated in northern Libya in response to a eustatic rise in sea level, whereas Upper Miocene mudstone accumulated along the south side of the Atlas Mountains because uplift of the

  13. Emplacement of Antarctic ice sheet mass affects circumpolar ocean flow

    NARCIS (Netherlands)

    Rugenstein, M.; Stocchi, P.; van der Heydt, A.; Brinkhuis, H.

    2014-01-01

    During the Cenozoic the Antarctic continent experienced large fluctuations in ice-sheet volume. We investigate the effects of Glacial Isostatic Adjustment (GIA) on Southern Ocean circulation for the first continental scale glaciation of Antarctica (~ 34 Myr) by combining solid Earth and ocean dynami

  14. Cenozoic intracontinental deformation of the Kopeh Dagh Belt, Northeastern Iran

    Science.gov (United States)

    Chu, Yang; Wan, Bo; Chen, Ling; Talebian, Morteza

    2016-04-01

    Compressional intracontinental orogens represent large tectonic zones far from plate boundaries. Since intracontinental mountain belts cannot be framed in the conventional plate tectonics theory, several hypotheses have been proposed to account for the formations of these mountain belts. The far-field effect of collision/subduction at plate margins is now well accepted for the origin and evolution of the intracontinental crust thickening, as exemplified by the Miocene tectonics of central Asia. In northern Iran, the Binalud-Alborz mountain belt witnessed the Triassic tectonothermal events (Cimmerian orogeny), which are interpreted as the result of the Paleotethys Ocean closure between the Eurasia and Central Iran blocks. The Kopeh Dagh Belt, located to the north of the Binalud-Alborz Belt, has experienced two significant tectonic phases: (1) Jurassic to Eocene rifting with more than 7 km of sediments; and (2) Late Eocene-Early Oligocene to Quaternary continuous compression. Due to the high seismicity, deformation associated with earthquakes has received more and more attention; however, the deformation pattern and architecture of this range remain poorly understood. Detailed field observations on the Cenozoic deformation indicate that the Kopeh Dagh Belt can be divided into a western zone and an eastern zone, separated by a series of dextral strike-slip faults, i.e. the Bakharden-Quchan Fault System. The eastern zone characterized by km-scale box-fold structures, associated with southwest-dipping reverse faults and top-to-the NE kinematics. In contrast, the western zone shows top-to-the SW kinematics, and the deformation intensifies from NE to SW. In the northern part of this zone, large-scale asymmetrical anticlines exhibit SW-directed vergence with subordinate thrusts and folds, whereas symmetrical anticlines are observed in the southern part. In regard to its tectonic feature, the Kopeh Dagh Belt is a typical Cenozoic intracontinental belt without ophiolites or

  15. Origin of low δ26Mg Cenozoic basalts from South China Block and their geodynamic implications

    Science.gov (United States)

    Huang, Jian; Li, Shu-Guang; Xiao, Yilin; Ke, Shan; Li, Wang-Ye; Tian, Ye

    2015-09-01

    Origin of low δ26Mg basalts is a controversial subject and has been attributed to interaction of isotopically light carbonatitic melts derived from a subducted oceanic slab with the mantle (Yang et al., 2012), or alternatively, to accumulation of isotopically light ilmenite (FeTiO3) in their mantle source (Sedaghatpour et al., 2013). To study the origin of low δ26Mg basalts and evaluate whether Mg isotope ratios of basalts can be used to trace deeply recycled carbon, high-precision major and trace element and Mg isotopic analyses on the Cenozoic alkaline and tholeiitic basalts from the South China Block (SCB), eastern China have been carried out in this study. The basalts show light Mg isotopic compositions, with δ26Mg ranging from -0.60 to -0.35. The relatively low TiO2 contents (eclogite transformed from carbonate-bearing oceanic crust during plate subduction. As only the Pacific slab has an influence on both the North China Block (NCB) and SCB, our results together with the study of Yang et al. (2012) demonstrate that the recycled carbonatitic melts might have originated from the stagnant Pacific slab beneath East Asia in the Cretaceous and Cenozoic and that a widespread carbonated upper mantle exists beneath eastern China, which may serve as the main source for the <110 Ma basalts in this area. Thus, our study demonstrates that Mg isotope ratios of basalts are a powerful tool to trace deeply recycled carbon.

  16. The Cenozoic Volcanoes in Northeast China

    Institute of Scientific and Technical Information of China (English)

    LIU Jiaqi; HAN Jingtai; GUO Zhengfu

    2002-01-01

    There are more than 600 Cenozoic volcanic cones and craters with abeut 50 000 km2of lava flows in northeast China, which formed many volcanic clusters and shown the features of the continental rift - type volcanoes. Most volcanic activities in this area, especially in the east part of Songliao graben, were usually controlled by rifts and faults with the main direction of NE / NNE in parallel and become younger from the central graben towards its both sides, especially to the east continental margin. It is revealed that the volcanism occurred in northeast China was as strong as that occurred in Japan during the Miocene and the Quaternary. The Quaternary basalt that is usually distributed along river valley is called "valley basalt"while Neogene basalt usually distributed in the top of mounts is called "high position basalt". These volcanoes and volcanic rocks are usually composed of alkaline basalts with ultramafic inclusions, except Changbaishan volcano that is built by trachyte and pantellerite.

  17. Application of sediment core modelling to understanding climates of the past: An example from glacial-interglacial changes in Southern Ocean silica cycling

    Directory of Open Access Journals (Sweden)

    A. Ridgwell

    2006-12-01

    Full Text Available Paleoceanographic evidence from the Southern Ocean reveals an apparent stark meridional divide in biogeochemical dynamics associated with the glacial-interglacial cycles of the late Neogene. South of the present-day position of the Antarctic Polar Front biogenic opal is generally much more abundant in sediments during interglacials compared to glacials. To the north, an anti-phased relationship is observed, with maximum opal abundance instead occurring during glacials. This antagonistic response of sedimentary properties is an important model validation target for testing hypotheses of glacial-interglacial change, particularly with respect to understanding the causes of the variability in atmospheric CO2. Here, I illustrate a time-dependent modelling approach to helping understand past climatic change by means of the generation of synthetic sediment core records. I find a close match between model-predicted and observed down-core changes in sedimentary opal content is achieved when changes in seasonal sea-ice extent is imposed, suggesting that the cryosphere is probably the primary driver of the striking features exhibited by the paleoceanographic record of this region.

  18. Declining sensitivity of the carbonate compensation depth to sea level during the Cenozoic

    Science.gov (United States)

    Armstrong McKay, David I.; Tyrrell, Toby; Wilson, Paul A.

    2016-04-01

    Over the course of the Cenozoic the global carbonate compensation depth (CCD), the depth in the ocean below which carbonate deposited on the seafloor is not preserved, has shifted from a relatively shallow average position (~3000 to 3500 m in the equatorial Pacific) in the Palaeocene to a relatively deep position (~4600 m in the equatorial Pacific) today. Various hypotheses have been proposed to explain this shift, including increased input of terrestrial weathering products to the ocean, decreased bottom-water corrosivity due to increased ocean ventilation, and the decline of shelf carbonates leading to carbonate burial shifting to the deep ocean (known as 'shelf-basin carbonate burial fractionation'). Here we build on earlier attempts to quantify the impacts of carbonate burial fractionation on the CCD by analysing global hypsometric and carbonate burial data and determining the relationship between sea level, shelf carbonate burial extent, and the CCD. We show that if carbonate burial rates remain constant across the Cenozoic then carbonate burial fractionation can explain between 550 and 800 m of the long-term ~1600 m CCD deepening in the equatorial Pacific, ~430 m of which occurring across the Eocene-Oligocene Transition (EOT) ~34 million years ago when the CCD permanently deepened by ~500 m. This finding indicates that other processes dominated CCD change before and after the EOT and during events such as the Mid-Eocene Climatic Optimum (MECO), but a higher resolution global CCD record is required to better constrain the global magnitude of CCD change during these times. We find that the sensitivity of the CCD to sea level change was at its greatest prior to the EOT and then declined by approximately half due to the loss of extensive carbonate platforms at the end of the Eocene and the intersection of the CCD with large tracts of the abyssal plain.

  19. Mechanisms of Cenozoic deformation in the Bohai Basin, Northeast China: Physical modelling and discussions

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The Bohai Basin is a Cenozoic petroliferous extensional basin in China and has apparent geometrical and kinematic similarities with the other Meso-Cenozoic extensional basins located along the eastern margin of Eurasian Plate. However, the deformation mechanisms of the basin are still in dispute. Physcial modelling referring to the Huanghua Depression, located in the central part of the Bohai Basin was conducted employing four sets of planar sandbox experimental models with different extension directions. Only experimental results of the model with N-S extension show good structural similarity with the depression. The results also indicate that complex variations of fault strike in a rift basin are not necessarily the results of complex kinematic mechanisms or polyphase deformation. Based on comparison of experimental results with the actual structures and the good structural similarity between Huanghua Depression and the whole Bohai Basin, it is concluded that the Bohai Basin was formed by the N-S extension. The strike slip deformation along the NNE-trending border faults of the basin resulted from the N-S extension and played the role of lateral transformation for the N-S extension. In addition, according to the apparent geometrical and kinematic similarities among the Bohai Basin and other Meso-Cenozoic extensional basins located along the eastern margin of the Eurasian Plate, it is proposed that: (1) this "N-S extension" model provides a better kinematic interpretation for the formation of Bohai Basin and the other adjacent basins located along the eastern margin of the Eurasian Plate; and (2) the N-S extension was probably the effect of the "slab window" formed by the subduction of the nearly E-W trending oceanic ridge between the Kula and Pacific Plates. The "slab window" effect can also provide reasonable explanations for the phenomena that initial rifting ages of basins become progressively younger westwards along the eastern margin of the Eurasian Plate

  20. Reconstructing geographical boundary conditions for palaeoclimate modelling during the Cenozoic

    Science.gov (United States)

    Baatsen, Michiel; van Hinsbergen, Douwe J. J.; von der Heydt, Anna S.; Dijkstra, Henk A.; Sluijs, Appy; Abels, Hemmo A.; Bijl, Peter K.

    2016-08-01

    Studies on the palaeoclimate and palaeoceanography using numerical model simulations may be considerably dependent on the implemented geographical reconstruction. Because building the palaeogeographic datasets for these models is often a time-consuming and elaborate exercise, palaeoclimate models frequently use reconstructions in which the latest state-of-the-art plate tectonic reconstructions, palaeotopography and -bathymetry, or vegetation have not yet been incorporated. In this paper, we therefore provide a new method to efficiently generate a global geographical reconstruction for the middle-late Eocene. The generalised procedure is also reusable to create reconstructions for other time slices within the Cenozoic, suitable for palaeoclimate modelling. We use a plate-tectonic model to make global masks containing the distribution of land, continental shelves, shallow basins and deep ocean. The use of depth-age relationships for oceanic crust together with adjusted present-day topography gives a first estimate of the global geography at a chosen time frame. This estimate subsequently needs manual editing of areas where existing geological data indicate that the altimetry has changed significantly over time. Certain generic changes (e.g. lowering mountain ranges) can be made relatively easily by defining a set of masks while other features may require a more specific treatment. Since the discussion regarding many of these regions is still ongoing, it is crucial to make it easy for changes to be incorporated without having to redo the entire procedure. In this manner, a complete reconstruction can be made that suffices as a boundary condition for numerical models with a limited effort. This facilitates the interaction between experts in geology and palaeoclimate modelling, keeping reconstructions up to date and improving the consistency between different studies. Moreover, it facilitates model inter-comparison studies and sensitivity tests regarding certain

  1. CENOZOIC VOLCANISM AND GEOTHERMAL RESOURCES IN NORTHEAST CHINA

    Institute of Scientific and Technical Information of China (English)

    WANG; Xi-kui

    2001-01-01

    [1]CHEN Pan-qin. 1992. The Core Project of International Research of Global Changes (1) [M]. Beijing: Atmosphere Publishing House, 70. (in Chinese)[2]Committee of National Natural Science Foundation of China, 1995. Geography Science[M]. Beinjing: Science Press,105. (in Chinese)[3]HUMHREY J D, FERRING C R , 1994. Stable isotopic evidence for latest pleistocene and central Holocene climatic change in north Texas[J]. Quaternary Research, 41:200-213.[4]GUAN You-zhi, LI Zhi-zhong, 1994. The distribution of geochemical elementin and paleoclimate in the Holocene sediment, northern part of Taklimakan desert[J]. Arid Land Geography, 17(3): 19-26. (in Chinese)[5]LIJia-lin, 1988. Guide to Geochemstry[M]. Lanzhou: Lanzhou University Press, 88-92. (in Chinese)[6]LIU Yin-jun, 1984. Element Geochemistry[M]. Beijing: Science Press. (in Chinese)[7]OLDFIELD F, 1991. Environmental Magnetism-a personal prospective[J]. Quaternary Science Review, 10:73-85.[8]SUN Xiang-jun, DU Nai-qiu, WEN Chen-yu et al., 1994, Paleovegetation and paleoenvironment of Mamas Lake, Xinjiang,N. W. China, during the last 14000 years[J]. Quaternary Sciences, 3:239-247. (in Chinese)[9]WU Jin-lu, 1997. Composition of the stable authigenic isotope of carbonate of RM core and its paleoclimatic implication in Tibetan plateau[J]. Scientia Geographica Sinica, 17(1):18 - 22. (in Chinese)[10]YIN Ze-sheng, YANG Yi-chou, WANG Shou-chun, 1993.Holocence environmental changes and Human being' s civilization in arid northwestern China[A]. In: ZHANG Lan-sheng(ed. ). Research on Living Environmental Changes in China During Historic Period[C]. Beijing: Ocean Press,260-283. (in Chinese)[11]YAO Tan-dong, SHI Ya-feng, THOMPSON L G et al., 1992.Climatic changes of Holocene reflected in the ice core from Dunde[A]. In: SHI Ya-feng. The Climates and Environments of Holocenc Megathermal in China[C]. Beijing: China Ocean Press, 206-210. (in Chinese)[12]YAO Tan-dong, YANG Zhi-hong, JIAO

  2. CENOZOIC VOLCANISM AND GEOTHERMAL RESOURCES IN NORTHEAST CHINA

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper is concentrated on Cenozoic volcanism and geothermal resources in Northeast China. There are a lot of Cenozoic volcanoes, a large area of volcanic rocks, a large number of active faults and rich geothermal resources in Northeast China. The time and space characteristics of Cenozoic volcanism and the space distribution characters of hot springs and high geothermal flux regions in Northeast China are described and discussed on the basis of geological, geothermal, drilling and volcanological data. It is revealed that the hot springs and high geothermal flux regions are re lated to the Cenozoic volcanism, rifting and faulting in Northeast China. It is especially emphasized that the hot springs and high geothermal anomaly areas are controlled by active deep faults. It is proposed that the Cenozoic volcanism re gions, rift basins, active fault belts, activated plate suture zones and large earthquake occurrence points are the best areas for prospecting geothermal resources. The geothermal resources in younger volcanic zones are richer than those in older volcanic belts. The hot springs and active or activated faults might be a very good clue for looking for geothermal resources.

  3. Relating Cenozoic North Sea sediments to topography in southern Norway:

    DEFF Research Database (Denmark)

    Anell, Ingrid Anna Margareta; Thybo, Hans; Stratford, Wanda Rose

    2010-01-01

    sources for progradational influx of clastic sediments from Scotland, the Shetland platform and, to a lesser degree, southwestern Norway. The Eocene sedimentation pattern was similar to the Palaeocene, with lower rates of accumulation associated with flooding and tectonic quiescence. Sediment influx from...... the Shetland platform continued throughout the Cenozoic while supply from southern Norway increased markedly around the Eocene–Oligocene, coeval with the greenhouse–icehouse transition. Mass balance calculations of sediment and eroded rock volumes suggest that while some topography along the western...... margin of Norway may be pre-Cenozoic, significant uplift of the main Paleic surface in southern Norway occurred around the early Oligocene. Sedimentation rates were almost ten-fold higher than the Cenozoic average in the Plio-Pleistocene, slightly higher than the global average. Mass balance calculations...

  4. Constraining silica diagenesis in methane-seep deposits

    Science.gov (United States)

    Smrzka, Daniel; Kraemer, Stephan; Zwicker, Jennifer; Birgel, Daniel; Fischer, David; Kasten, Sabine; Goedert, James; Peckmann, Jörn

    2015-04-01

    Silicified fossils and silicified early diagenetic carbonate minerals as well as authigenic silica phases are common in ancient seep limestones. Silicification of calcareous fossils facilitates the preservation of even fine details and is therefore of great interest to paleontologists, permitting a reliable taxonomic identification of the chemosynthesis-based taxa that lived at ancient hydrocarbon seeps. Four methane-seep limestones of Paleozoic, Mesozoic, and Cenozoic age with abundant silica phases are compared in this study; one, an Eocene seep deposit on the north shore of the Columbia River at Knappton, western Washington State, USA, is described for the first time. Its lithology and fabrics, negative δ13Ccarbonate values as low as -27.6‰, and 13C-depleted biomarkers of archaea involved in the anaerobic oxidation of methane (AOM) reveal that the carbonate rock formed at a methane seep. The background sediments of the studied Phanerozoic seep limestones contain abundant siliceous microfossils, radiolarian tests in case of the Late Carboniferous Dwyka Group deposits from Namibia and the Late Triassic Graylock Butte deposits from eastern Oregon (USA), diatom frustules in case of the Eocene Knappton limestone and an Oligocene seep deposit from the Lincoln Creek Formation (western Washington State, USA). These microfossils are regarded as the source of dissolved silica, causing silicification and silica precipitation. All seep limestones used in this study are characterized by very similar paragenetic sequences. Silicified fossils include brachiopods and worm tubes, silica cements include microquartz, fibrous microcrystalline silica, and megaquartz. The silica cements formed after the AOM-derived cements ceased to precipitate but before equant calcite spar formed. Numerical experiments using the computer code PHREEQC were conducted to test the hypothesis that (1) AOM increases the pH of pore waters and that (2) this pH increase subsequently mobilizes biogenic

  5. Long-term stability of global erosion rates and weathering during late-Cenozoic cooling.

    Science.gov (United States)

    Willenbring, Jane K; von Blanckenburg, Friedhelm

    2010-05-13

    Over geologic timescales, CO(2) is emitted from the Earth's interior and is removed from the atmosphere by silicate rock weathering and organic carbon burial. This balance is thought to have stabilized greenhouse conditions within a range that ensured habitable conditions. Changes in this balance have been attributed to changes in topographic relief, where varying rates of continental rock weathering and erosion are superimposed on fluctuations in organic carbon burial. Geological strata provide an indirect yet imperfectly preserved record of this change through changing rates of sedimentation. Widespread observations of a recent (0-5-Myr) fourfold increase in global sedimentation rates require a global mechanism to explain them. Accelerated uplift and global cooling have been given as possible causes, but because of the links between rates of erosion and the correlated rate of weathering, an increase in the drawdown of CO(2) that is predicted to follow may be the cause of global climate change instead. However, globally, rates of uplift cannot increase everywhere in the way that apparent sedimentation rates do. Moreover, proxy records of past atmospheric CO(2) provide no evidence for this large reduction in recent CO(2) concentrations. Here we question whether this increase in global weathering and erosion actually occurred and whether the apparent increase in the sedimentation rate is due to observational biases in the sedimentary record. As evidence, we recast the ocean dissolved (10)Be/(9)Be isotope system as a weathering proxy spanning the past approximately 12 Myr (ref. 14). This proxy indicates stable weathering fluxes during the late-Cenozoic era. The sum of these observations shows neither clear evidence for increased erosion nor clear evidence for a pulse in weathered material to the ocean. We conclude that processes different from an increase in denudation caused Cenozoic global cooling, and that global cooling had no profound effect on spatially and

  6. Silica in Protoplanetary Disks

    CERN Document Server

    Sargent, B A; Tayrien, C; McClure, M K; Li, A; Basu, A R; Manoj, P; Watson, D M; Bohac, C J; Furlan, E; Kim, K H; Green, J D; Sloan, G C

    2008-01-01

    Mid-infrared spectra of a few T Tauri stars (TTS) taken with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope show prominent narrow emission features indicating silica (crystalline silicon dioxide). Silica is not a major constituent of the interstellar medium; therefore, any silica present in the circumstellar protoplanetary disks of TTS must be largely the result of processing of primitive dust material in the disks surrouding these stars. We model the silica emission features in our spectra using the opacities of various polymorphs of silica and their amorphous versions computed from earth-based laboratory measurements. This modeling indicates that the two polymorphs of silica, tridymite and cristobalite, which form at successively higher temperatures and low pressures, are the dominant forms of silica in the TTS of our sample. These high temperature, low pressure polymorphs of silica present in protoplanetary disks are consistent with a grain composed mostly of tridymite named Ada found...

  7. Meso-Cenozoic basin evolution in northern Korean Peninsula

    Institute of Scientific and Technical Information of China (English)

    PAK Hyon Uk; LYANG To Jun; LIU Yongjiang; HYON Yun Su; KIM Gyong Chol

    2009-01-01

    In the Korean Peninsula the Meso-Cenozoic basins were mainly formed due to fault block and block movement. The Mesozoic fracture structures correspond basically to modern large rivers in direction. Such faults were usually developed to rift and formed lake-type tectonic basin, such as the Amrokgang-, Taedonggang-, Ryesonggang-, Hochongang-, Jangphari-, Susongchon-, Pujon-, and Nampho basins. The Mesozoic strata are considered to be divided into the Lower Jurassic Taedong System, Upper Jurassic Jasong System, Upper Jurassic- -early Lower Cretaceous Taebo System, and the Upper Cretaceous- -Paleocene (Chonjaebong, Hongwon, Jaedok Series). The Cenozoic block movement succeeded the Mesozoic fault block movement. The Kilju-Myongchon Graben and Tumangang Basin, etc, are the basins related to the fault zones developed from the Oligocene to Miocene. In addition, the Tertiary basins were formed in many areas in the Miocene (e.g. Sinhung, Oro, Hamhung, Yonghung, Anbyon, Cholwon, etc). The Cenozoic sedimentation occurred mainly from the late Oligocene to Miocene. The Kilju-Myongchon Graben was the fore deep connected to the sea and the basins inclined in the Chugaryong Fault Zone are intramountain basins. Therefore, coal-bearing beds and clastic rocks in the intramountain basins and rare marine strata and terrigenous clastic rocks are main sedimentary sequences in the Cenozoic.

  8. Paleomagnetic results from Cenozoic volcanics of Lusatia, NW Bohemian Massif

    Czech Academy of Sciences Publication Activity Database

    Schnabl, Petr; Cajz, Vladimír; Tietz, O.; Buechner, J.; Suhr, P.; Pécskay, Z.; Čížková, Kristýna

    s. l: American Geophysical Union, 2013. [AGU Meeting of the Americas. 14.05.2013-17.05.2013, Cancun] Institutional support: RVO:67985831 Keywords : paleomagnetism * Cenozoic * volcanics Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://moa.agu.org/2013/eposters/eposter/gp33a-03/

  9. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Science.gov (United States)

    2013-03-06

    ... AGENCY Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl Sodium... the registration review of cyromazine, silica silicates (silica dioxide and silica gel), glufosinate..., consistent with the notice published in the Federal Register of August 17, 2012, (77 FR 49792)...

  10. Investigating Late Cenozoic Mantle Dynamics beneath Yellowstone

    Science.gov (United States)

    Zhou, Q.; Liu, L.

    2015-12-01

    Recent tomography models (Sigloch, 2011; Schmandt & Lin, 2014) reveal unprecedented details of the mantle structure beneath the United States (U.S.). Prominent slow seismic anomalies below Yellowstone, traditionally interpreted as due to a mantle plume, are restricted to depths either shallower than 200 km or between 500 and 1000 km, but a continuation to greater depth is missing. Compared to fast seismic anomalies, which are usually interpreted as slabs or delaminated lithosphere, origin of deep slow seismic anomalies, especially those in the vicinity of subduction zones, is more enigmatic. As a consequence, both the dynamics and evolution of these slow anomalies remain poorly understood. To investigate the origin and evolution of the Yellowstone slow anomaly during the past 20 Myr, we construct a 4D inverse mantle convection model with a hybrid data assimilation scheme. On the one hand, we use the adjoint method to recover the past evolution of mantle seismic structures beyond the subduction zones. On the other hand, we use a high-resolution forward model to simulate the subduction of the oceanic (i.e., Farallon) plate. During the adjoint iterations, features from these two approaches are blended together at a depth of ~200 km below the subduction zone. In practice, we convert fast and slow seismic anomalies to effective positive and negative density heterogeneities. Our preliminary results indicate that at 20 Ma, the present-day shallow slow anomalies beneath the western U.S. were located inside the oceanic asthenosphere, which subsequently entered the mantle wedge, through the segmented Farallon slab. The eastward encroachment of the slow anomaly largely followed the Yellowstone hotspot track migration. The present deep mantle Yellowstone slow anomaly originated at shallower depths (i.e. transition zone), and was then translated down to the lower mantle accompanying the sinking fast anomalies. The temporal evolution of the slow anomalies suggests that the deep

  11. Sediment budget of cratons: insights from West Africa over the Cenozoic

    Science.gov (United States)

    Jean-Louis, G.; Chardon, D.; Rouby, D.; Beauvais, A.

    2015-12-01

    The sediment load of rivers constitutes the material that builds the stratigraphic successions found from continental margins to the deep ocean. Measure of this flux is relevant to understanding continental controls on denudation, riverine transport and basin filling. An increasing number of sediment yield measures is available but whether these modern values can be extrapolated at geological timescales for large watersheds is still questioned. One reason is the lack of long-term data. Here, we present a sediment budget for Sub-Saharan West Africa over the Cenozoic to compare with the modern rates. The denudation of this cratonic area is constrained using three regional lateritic paleo-landsurfaces that formed during periods of enhanced weathering since the Paleocene-Eocene greenhouse peak. The 3D interpolation of these surfaces allowed building three successive denudation maps for the 45-24, 24-11 and 11-0 Ma intervals together with reconstructions of the paleo-drainage. The regional distribution of erosion suggests the influence of lithospheric deformation, concentrated around a southern marginal upwarp and eastern hotspot swells. The export of large-scale drainages was calculated by converting denudated volumes into sediment fluxes using the porosity and density of lateritic regolith. Exported volumes calculated for the Niger watershed fall within the same range as the Cenozoic clastic accumulations of the Niger delta. Comparisons also show that modern fluxes can be an order of magnitude above the long-term fluxes for moderately large watersheds but that modern and long-term yields are similar for the largest watersheds (e.g. Niger, Volta, Senegal). These results suggest that the export of very large cratonic watersheds is independent of the measurement timescale and that their modern yields can be extrapolated at long-timescale. Finally, it allows assessing the relative contribution of cratons, i.e. non-active orogenic areas, to the global sediment budgets at

  12. Cenozoic magmatism in the northern continental margin of the South China Sea: evidence from seismic profiles

    Science.gov (United States)

    Zhang, Qiao; Wu, Shiguo; Dong, Dongdong

    2016-06-01

    Igneous rocks in the northern margin of the South China Sea (SCS) have been identified via high resolution multi-channel seismic data in addition to other geophysical and drilling well data. This study identified intrusive and extrusive structures including seamounts and buried volcanoes, and their seismic characteristics. Intrusive features consist of piercement and implicit-piercement type structures, indicating different energy input associated with diapir formation. Extrusive structures are divided into flat-topped and conical-topped seamounts. Three main criteria (the overlying strata, the contact relationship and sills) were used to distinguish between intrusive rocks and buried volcanos. Three criteria are also used to estimate the timing of igneous rock formation: the contact relationship, the overlying sedimentary thickness and seismic reflection characteristics. These criteria are applied to recognize and distinguish between three periods of Cenozoic magmatism in the northern margin of the SCS: before seafloor spreading (Paleocene and Eocene), during seafloor spreading (Early Oligocene-Mid Miocene) and after cessation of seafloor spreading (Mid Miocene-Recent). Among them, greater attention is given to the extensive magmatism since 5.5 Ma, which is present throughout nearly all of the study area, making it a significant event in the SCS. Almost all of the Cenozoic igneous rocks were located below the 1500 m bathymetric contour. In contrast with the wide distribution of igneous rocks in the volcanic rifted margin, igneous rocks in the syn-rift stage of the northern margin of the SCS are extremely sporadic, and they could only be found in the southern Pearl River Mouth basin and NW sub-sea basin. The ocean-continent transition of the northern SCS exhibits high-angle listric faults, concentrated on the seaward side of the magmatic zone, and a sharply decreased crust, with little influence from a mantle plume. These observations provide further evidence to

  13. Late-Paleozoic emplacement and Meso-Cenozoic reactivation of the southern Kazakhstan granitoid basement

    Science.gov (United States)

    De Pelsmaeker, Elien; Glorie, Stijn; Buslov, Mikhail M.; Zhimulev, Fedor I.; Poujol, Marc; Korobkin, Valeriy V.; Vanhaecke, Frank; Vetrov, Evgeny V.; De Grave, Johan

    2015-11-01

    The Ili-Balkhash Basin in southeastern Kazakhstan is located at the junction of the actively deforming mountain ranges of western Junggar and the Tien Shan, and is therefore part of the southwestern Central Asian Orogenic Belt. The basement of the Ili-Balkhash area consists of an assemblage of mainly Precambrian microcontinental fragments, magmatic arcs and accretionary complexes. Eight magmatic basement samples (granitoids and tuffs) from the Ili-Balkhash area were dated with zircon U-Pb LA-ICP-MS and yield Carboniferous to late Permian (~ 350-260 Ma) crystallization ages. These ages are interpreted as reflecting the transition from subduction to (post-) collisional magmatism, related to the closure of the Junggar-Balkhash Ocean during the Carboniferous-early Permian and hence, to the final late Paleozoic accretion history of the ancestral Central Asian Orogenic Belt. Apatite fission track (AFT) dating of 14 basement samples (gneiss, granitoids and volcanic tuffs) mainly provides Cretaceous cooling ages. Thermal history modeling based on the AFT data reveals that several intracontinental tectonic reactivation episodes affected the studied basement during the late Mesozoic and Cenozoic. Late Mesozoic reactivation and associated basement exhumation is interpreted as distant effects of the Cimmerian collisions at the southern Eurasian margin and possibly of the Mongol-Okhotsk Orogeny in SE Siberia during the Jurassic-Cretaceous. Following tectonic stability during the Paleogene, inherited basement structures were reactivated during the Neogene (constrained by Miocene AFT ages of ~ 17-10 Ma). This late Cenozoic reactivation is interpreted as the far-field response of the India-Eurasia collision and reflects the onset of modern mountain building and denudation in southeast Kazakhstan, which seems to be at least partially controlled by the inherited basement architecture.

  14. Report on ICDP workshop CONOSC (COring the NOrth Sea Cenozoic)

    Science.gov (United States)

    Westerhoff, Wim; Donders, Timme; Luthi, Stefan

    2016-08-01

    ICDP workshop COring the NOrth Sea Cenozoic focused on the scientific objectives and the technical aspects of drilling and sampling. Some 55 participants attended the meeting, ranging from climate scientists, drilling engineers, and geophysicists to stratigraphers and public outreach experts. Discussion on the proposed research sharpened the main research lines and led to working groups and the necessary technical details to compile a full proposal that was submitted in January 2016.

  15. Recurrent Cenozoic volcanic activity in the Bohemian Massif (Czech Republic)

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Dostal, J.; Adamovič, Jiří; Jelínek, E.; Špaček, Petr; Hegner, E.; Balogh, K.

    2011-01-01

    Roč. 123, 1/4 (2011), s. 133-144. ISSN 0024-4937 R&D Projects: GA AV ČR(CZ) IAA300130902; GA ČR(CZ) GA205/09/1170 Institutional research plan: CEZ:AV0Z30130516; CEZ:AV0Z30120515 Keywords : Bohemian Massif * Cenozoic * alkaline volcanism * paleostress fields * rift * mantle Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.246, year: 2011

  16. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions on the...... microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  17. Influence of organics and silica on Fe(II) oxidation rates and cell-mineral aggregate formation by the green-sulfur Fe(II)-oxidizing bacterium Chlorobium ferrooxidans KoFox - Implications for Fe(II) oxidation in ancient oceans

    Science.gov (United States)

    Gauger, Tina; Byrne, James M.; Konhauser, Kurt O.; Obst, Martin; Crowe, Sean; Kappler, Andreas

    2016-06-01

    Most studies on microbial phototrophic Fe(II) oxidation (photoferrotrophy) have focused on purple bacteria, but recent evidence points to the importance of green-sulfur bacteria (GSB). Their recovery from modern ferruginous environments suggests that these photoferrotrophs can offer insights into how their ancient counterparts grew in Archean oceans at the time of banded iron formation (BIF) deposition. It is unknown, however, how Fe(II) oxidation rates, cell-mineral aggregate formation, and Fe-mineralogy vary under environmental conditions reminiscent of the geological past. To address this, we studied the Fe(II)-oxidizer Chlorobium ferrooxidans KoFox, a GSB living in co-culture with the heterotrophic Geospirillum strain KoFum. We investigated the mineralogy of Fe(III) metabolic products at low/high light intensity, and in the presence of dissolved silica and/or fumarate. Silica and fumarate influenced the crystallinity and particle size of the produced Fe(III) minerals. The presence of silica also enhanced Fe(II) oxidation rates, especially at high light intensities, potentially by lowering Fe(II)-toxicity to the cells. Electron microscopic imaging showed no encrustation of either KoFox or KoFum cells with Fe(III)-minerals, though weak associations were observed suggesting co-sedimentation of Fe(III) with at least some biomass via these aggregates, which could support diagenetic Fe(III)-reduction. Given that GSB are presumably one of the most ancient photosynthetic organisms, and pre-date cyanobacteria, our findings, on the one hand, strengthen arguments for photoferrotrophic activity as a likely mechanism for BIF deposition on a predominantly anoxic early Earth, but, on the other hand, also suggest that preservation of remnants of Fe(II)-oxidizing GSB as microfossils in the rock record is unlikely.

  18. Effect of vegetation on the Late Miocene ocean circulation

    Directory of Open Access Journals (Sweden)

    G. Lohmann

    2006-08-01

    Full Text Available A weak and shallow thermohaline circulation in the North Atlantic Ocean is related to an open Central American gateway and exchange with fresh Pacific waters. We estimate the effect of vegetation on the ocean general circulation using the atmospheric circulation model simulations for the Late Miocene climate. Caused by an increase in net evaporation in the Miocene North Atlantic, the North Atlantic water becomes more saline which enhances the overturning circulation and thus the northward heat transport. This effect reveals a potentially important feedback between the ocean circulation, the hydrological cycle and the land surface cover for Cenozoic climate evolution.

  19. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia.

    Science.gov (United States)

    van Hinsbergen, Douwe J J; Lippert, Peter C; Dupont-Nivet, Guillaume; McQuarrie, Nadine; Doubrovine, Pavel V; Spakman, Wim; Torsvik, Trond H

    2012-05-15

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India-Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 ± 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. Here we show that the discrepancy between the convergence and the shortening can be explained by subduction of highly extended continental and oceanic Indian lithosphere within the Himalaya between approximately 50 and 25 Ma. Paleomagnetic data show that this extended continental and oceanic "Greater India" promontory resulted from 2,675 ± 700 km of North-South extension between 120 and 70 Ma, accommodated between the Tibetan Himalaya and cratonic India. We suggest that the approximately 50 Ma "India"-Asia collision was a collision of a Tibetan-Himalayan microcontinent with Asia, followed by subduction of the largely oceanic Greater India Basin along a subduction zone at the location of the Greater Himalaya. The "hard" India-Asia collision with thicker and contiguous Indian continental lithosphere occurred around 25-20 Ma. This hard collision is coincident with far-field deformation in central Asia and rapid exhumation of Greater Himalaya crystalline rocks, and may be linked to intensification of the Asian monsoon system. This two-stage collision between India and Asia is also reflected in the deep mantle remnants of subduction imaged with seismic tomography. PMID:22547792

  20. Silica Refractory Bricks

    Institute of Scientific and Technical Information of China (English)

    Yu Lingyan; Peng Xigao

    2011-01-01

    @@ 1.Scope This standard specifies the classification,technical requirements,test methods,quality appraisal procedures,packing,marking,transportation,storage,and quality certificate of silica refractory bricks.This standard is applicable to silica refractory bricks with single weight≤40 kg.

  1. Crystalline Silica Primer

    Science.gov (United States)

    Staff- Branch of Industrial Minerals

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  2. Silica, Silicosis, and Autoimmunity.

    Science.gov (United States)

    Pollard, Kenneth Michael

    2016-01-01

    Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response, which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements, suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, and autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However, numerous questions remain unanswered. PMID:27014276

  3. Silica, Silicosis and Autoimmunity.

    Directory of Open Access Journals (Sweden)

    Kenneth Michael Pollard

    2016-03-01

    Full Text Available Inhalation of dust containing crystalline silica is associated with a number of acute and chronic diseases including systemic autoimmune diseases. Evidence for the link with autoimmune disease comes from epidemiological studies linking occupational exposure to crystalline silica dust with the systemic autoimmune diseases SLE, SSc and RA. Although little is known regarding the mechanism by which silica exposure leads to systemic autoimmune disease, there is a voluminous literature on silica exposure and silicosis that may help identify immune processes that precede development of autoimmunity. The pathophysiology of silicosis consists of deposition of silica particles in the alveoli of the lung. Ingestion of these particles by macrophages initiates an inflammatory response which stimulates fibroblasts to proliferate and produce collagen. Silica particles are encased by collagen leading to fibrosis and the nodular lesions characteristic of the disease. The steps in the development of silicosis, including acute and chronic inflammation and fibrosis, have different molecular and cellular requirements suggesting that silica-induced inflammation and fibrosis may be mechanistically separate. Significantly, it is unclear whether silica-induced inflammation and fibrosis contribute similarly to the development of autoimmunity. Nonetheless, the findings from human and animal model studies are consistent with an autoimmune pathogenesis that begins with activation of the innate immune system leading to proinflammatory cytokine production, pulmonary inflammation leading to activation of adaptive immunity, breaking of tolerance, autoantibodies and tissue damage. The variable frequency of these immunological features following silica exposure suggests substantial genetic involvement and gene/environment interaction in silica-induced autoimmunity. However numerous questions remain unanswered.

  4. Cenozoic sequence stratigraphy in the eastern North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Michelsen, O.; Thomsen, E.; Danielsen, M.; Heilmann-Clausen, C.; Jordt, H.; Laursen, G.V.

    1995-05-01

    The Cenozoic evolution of the epicontinental North Sea Basin is described on the basis of sequence stratigraphy, comprising analyses of seismic sections, petrophysical logs, and biostratigraphic studies of foraminifera, dinoflagellates, and calcareous nannofossils. Stratigraphic, palaeogeographic, and palaeoecological information from the Danish onshore area is integrated in the study. The deposits are subdivided into 21 sequences, which groups into seven informal major units. The sequence boundaries are identified by differences in seismic facies and by seismic onlap, toplap, and truncation features. The maximum flooding surface is placed at an internal downlap surface which correlates with high values on the gamma ray log. The source of sediments and the direction of sediment transport changed several times during the Cenozoic. Transport was mainly from the north during the Late Paleocene and Early Eocene, from the west during the Middle and Late Eocene, and from the north and northwest during the Oligocene to quaternary. The depocenters of the seven major units are generally located marginally, probably adjoining the source areas. There is only minor evidence for changes in subsidence rates in the basin. A constant rate is assumed from the Paleocene to the mid Middle Miocene. For the remaining part of the Cenozoic and increased rate is indicated. A tentative relative sea-level curve for the North Sea Basin is proposed. The overall trends of the curve are broadly comparable with the global sea-level curve of Haq et al. Discrepancies may be caused by differences in the biostratigraphic calibrations. The most pronounced Oligocene sea-level fall is dated ot the latest Oligocene. (au) (83 refs.)

  5. Early Cenozoic Multiple Thrust in the Tibetan Plateau

    Directory of Open Access Journals (Sweden)

    Zhenhan Wu

    2013-01-01

    Full Text Available Recently completed regional geological mapping at a scale of 1 : 250,000 or larger across all of the Tibetan Plateau coupled with deep seismic surveys reveals for the first time a comprehensive depiction of the major early Cenozoic thrust systems resulting from the northward subduction of the Indian Continental Plate. These systems define a series of overlapping north-dipping thrust sheets that thickened the Tibetan crust and lead to the rise of the plateau. The few south-dipping thrusts present apparently developed within a sheet when the back moved faster than the toe. Many of the thrusts are shown to extend to the middle-lower crustal depths by seismic data. The regional thrust systems are the Main Central, Renbu-Zedong, Gangdese, Central Gangdese, North Gangdese, Bangoin-Nujiang, Qiangtang, Hohxil, and South Kunlun Thrusts. The minimal southward displacements of the South Kunlun, Hohxil, South Qiangtang, and Central Gangdese Thrusts are estimated to be 30 km, 25 km, 150 km and 50 km, respectively. Deep thrusting began in the Himalaya-Tibetan region soon after India-Eurasia continental collision and led to crustal thickening and subsequent uplift of the Tibetan Plateau during Late Eocene-Early Miocene when the systems were mainly active. The major thrust systems ceased moving in Early Miocene and many were soon covered by lacustrine strata. This activity succeeded in the late Cenozoic to crustal extension and strike-slip movement in the central Tibetan Plateau. The revelation of the full array of the early Cenozoic thrust systems provides a much more complete understanding of the tectonic framework of the Tibetan Plateau.

  6. Spreading of the ocean floor: Undeformed sediments in the peru-chile trench

    Science.gov (United States)

    Scholl, D. W.; Von Huene, R.; Ridlon, J.B.

    1968-01-01

    None of the expected stratigraphic and structural effects of a spreading sea floor have been imposed on the sedimentary fill of the Peru-Chile Trench. During at least the last several million years, and perhaps during much of the Cenozoic, the trench has not been affected by an oceanic crust thrusting under the continent.

  7. Radiometric age of Cenozoic volcanism and paleomagnetic research

    Czech Academy of Sciences Publication Activity Database

    Cajz, Vladimír; Schnabl, Petr; Radoň, M.

    [Praha]: Česká geologická společnost, 2011 - (Verner, K.; Buriánek, D.; Budil, P.). s. 24-24 ISBN 978-80-87487-00-6. [Otevřený kongres České geologické společnosti a Slovenskej geologickej spoločnosti /2./. 21.09.2011-25.09.2011, Monínec] Institutional research plan: CEZ:AV0Z30130516 Keywords : volcanism * paleomagnetism * Cenozoic Subject RIV: DB - Geology ; Mineralogy http://www.geologickykongres.eu/OGK11/abstrakty/OGK11_24.pdf

  8. Temporal evolution of island arc magmatism: geochronology, petrology et geochemistry of mesozoic and cenozoic magmatic rocks from Sumatra (Indonesia)

    International Nuclear Information System (INIS)

    Sumatra island (Western Indonesia) belongs to the Sunda magmatic arc, which results from the subduction of the Indian ocean plate beneath the margin of the Eurasiatic continental block. Plutonic and volcanic rocks of Mesozoic and Cenozoic ages are very abundant in Sumatra, where they mainly outcrop in a NNW-SSE trending, 1,650 km-long stripe in the western part of the island. The spatial and temporal distributions of magmatic rocks in Sumatra were not previously investigated in detail. We have performed 175 40K-40Ar datings on bulk rocks and minerals separated from samples which have also been analysed for major and trace elements by ICP-AES. These results allow to discuss the distribution of magmatic events in space of a long subduction period on the chemical composition of the Sunda arc mantle wedge. (author)

  9. Thermal state of the Roer Valley Graben, part of the European Cenozoic Rift System

    NARCIS (Netherlands)

    Luijendijk, E.; Voorde, M. ter; Balen, R. van; Verweij, H.; Simmelink, E.

    2011-01-01

    We performed a detailed analysis of the thermal state of the Cenozoic Roer Valley Graben, the north-western branch of the European Cenozoic Rift System, based on a new set of temperature data. We developed a numerical technique for correcting bottom hole temperatures, including an evaluation of the

  10. First paleomagnetic results from Cenozoic volcanics of Lusatian region, Saxony/Bohemia

    Czech Academy of Sciences Publication Activity Database

    Cajz, Vladimír; Schnabl, Petr; Büchner, J.; Tietz, O.; Suhr, P.; Pécskay, Z.; Čížková, Kristýna; Šlechta, Stanislav

    Prague: Czech Geological Survey ; Senckenberg museum of natural History Görlitz, 2013 - (Büchner, J.; Rapprich, V.; Tietz, O.). s. 189-190 ISBN 978-80-7075-806-9. [Basalt 2013: Cenozoic magmatism in Central Europe. 24.04.2013-28.04.2013, Görlitz] Institutional support: RVO:67985831 Keywords : Cenozoic * paleomagnetism * Lusation region Subject RIV: DB - Geology ; Mineralogy

  11. New antifouling silica hydrogel.

    Science.gov (United States)

    Beltrán-Osuna, Ángela A; Cao, Bin; Cheng, Gang; Jana, Sadhan C; Espe, Matthew P; Lama, Bimala

    2012-06-26

    In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel. PMID:22607091

  12. Environmental rock-magnetism of Cenozoic red clay in the South Pacific Gyre

    Science.gov (United States)

    Shimono, Takaya; Yamazaki, Toshitsugu

    2016-04-01

    Nonfossiliferous red clay can be used for elucidating long-range environmental changes, although such studies were limited so far because of the difficulty in precise age estimation and extremely low sedimentation rates. We conducted an environmental rock-magnetic study of Cenozoic red clay at the Integrated Ocean Drilling Program Site U1365 in the South Pacific Gyre. Magnetostratigraphy could be established only above ˜6 m below the seafloor (mbsf) (˜5 Ma). Below ˜6 mbsf, the ages of the cores were transferred from the published ages of nearby Deep Sea Drilling Project Site 596, which is based mainly on a constant Cobalt flux model, by intercore correlation using magnetic susceptibility and rare earth element content variation patterns. Rock-magnetic analyses including first-order reversal curve diagrams, the ratio of anhysteretic remanent magnetization susceptibility to saturation isothermal remanent magnetization (SIRM), and IRM component analyses revealed that magnetic minerals consist mainly of biogenic magnetite and terrigenous maghemite, and that the proportion of the terrigenous component increased since ˜23 Ma. We consider that the increase reflects a growth of eolian dust flux associated with a northward shift of Australia and the site to an arid region of the middle latitudes. The increase of the terrigenous component accelerated after ˜5 Ma, which may be associated with a further growth of the Antarctic glaciation at that time. This is coeval with the onset of the preservation of magnetostratigraphy, suggesting that the primary remanent magnetization is carried by the terrigenous component.

  13. Cenozoic Tectonic Activity of the "Passive" North America Margin: Evidence for Cenozoic Activity on Mesozoic or Paleozoic Faults

    Science.gov (United States)

    Nedorub, O. I.; Knapp, C. C.

    2012-12-01

    The tectonic history of the Eastern North American Margin (ENAM) incorporates two cycles of continental assembly, multiple pulses of orogeny, rifting, and post-rift geodynamic evolution. This is reflected in the heterogeneous lithosphere of the ENAM which contains fault structures originated in Paleozoic to Mesozoic eras. The South Georgia Rift basin is probably the largest Mesozoic graben within its boundaries that is associated with the breakup of Pangea. It is composed of smaller sub-basins which appear to be bounded by high-angle normal faults, some of which may have been inverted in late Cretaceous and Cenozoic eras. Paleozoic structures may have been reactivated in Cenozoic time as well. The ENAM is characterized by N-NE maximum horizontal compressive stress direction. This maximum compressional stress field is sub-parallel to the strike of the Atlantic Coast province fault systems. Camden, Augusta, Allendale, and Pen Branch faults are four of the many such reactivated faults along the southern part of ENAM. These faults are now buried under the 0-400 m of loosely consolidated Cretaceous and Cenozoic age sediments and thus are either only partially mapped or currently not recognized. Some of the objectives of this study are to map the subsurface expression and geometry of these faults and to investigate the post Cretaceous deformation and possible causes of fault reactivation on a passive margin. This study employs an integrated geophysical approach to investigate the upper 200 m of identified locations of the above mentioned faults. 2-D high-resolution shallow seismic reflection and refraction methods, gravity surveys, GPR, 2-D electrical resistivity and well data are used for analyses and interpretation. Preliminary results suggest that Camden fault shows signs of Cenozoic reactivation through an approximately 30 m offset NW side up mainly along a steeply dipping fault zone in the basal contact of Coastal Plain sediments with the Carolina Piedmont. Drill

  14. Measuring biogenic silica in marine sediments and suspended matter

    Science.gov (United States)

    DeMaster, David J.

    Measuring the biogenic silica content of marine sediments and suspended matter is essential for a variety of geochemical, biological, and sedimentological studies. Biota forming siliceous skeletal material account for as much as one third of the primary productivity in the ocean [Lisitzin, 1972] and a significant portion (2 to 70% by weight) of open-ocean sediments. Biogenic silica measurements reveal important information concerning the bulk chemistry of suspended material or sediment and are essential in any type of silica flux study in the water column or seabed. Analyses of this biogenic phase in marine plankton are useful in characterizing the basic types of biota present and in comparing the distributions of particulate and dissolved silicate when evaluating nutrient dynamics [Nelson and Smith, 1986]. In the marine environment, diatoms, radiolaria, sponges, and silicoflagellates are the common types of siliceous biota.

  15. Mesozoic and Cenozoic formations uraniferous activity. Chapter 3

    International Nuclear Information System (INIS)

    The main features of geological structure and history of forming Mesozoic and Cenozoic structure and formations complexes are given. Forming of Mesozoic-Cenozoic Depressive structures had been going on under the condition of infiltrations regime of artesian basins with forming of regional ground and stratum oxidation zones in Zhalpak and Paleogenic sediments which are including uranium deposits belonging to four uranium ore formation. The main raw materials base and extraction of uranium by in-situ leaching method are connected with deposits of epigenetic uranium-ore formation of regional stratum oxidation zones. There are most important deposits: Maikuduk, Inkai, Zhalpak, Uvanas, Suluchekenskoe, Koldzatskoe, Nizhneilyiskoe. All deposits are described according to same plan: stratigraphy, tectonic structure, hydrogeology, hydrochemics, uranium mineralization, morphology of deposits, mineral compound of ores, geologic characteristics of ores, genetics. Except uranium, the main deposit component, there is an information about the accompanied elements: rhenium, selenium, rare-earth ones, industrial concentration of which are in competitions with the same elements extracted from ores

  16. Hot Spot Induced Cenozoic Volcanism in the Upper Rajang Valley, Sarawak - Is Borneo Rifting?

    Science.gov (United States)

    Taib, N.

    2010-12-01

    The Upper Rajang Valley covers a large area in the northern interior of the island of Borneo, in the Malaysian state of Sarawak . It is underlain by the Cretaceous to Late Eocene deep to shallow marine sediments of the Rajang Group. Within this area are several Cenozoic volcanic edifices, which to date have been sparsely studied. Two distinct episodes of volcanism are recognized - the first, dated early Eocene, consists of K-rich basalts, and is represented by the Bukit Mersing volcanics, which were erupted conformably onto deep water turbidites of the Rajang Group. The second, far more extensive, is dated Pliocene to Quaternary, and is bimodal, consisting mainly of early dacite and rhyodacite tuffs, with a smaller amount of later basalt, forming several volcanic plateaus and massifs (Hose Mountains, Usun Apau, Linau-Balui, Nieuwenhuis Mountains and others). They lie unconformably over pre-Miocene sediments, the Linau-Balui basalts having been erupted onto Quaternary river terraces. Mantle-normalized REE and incompatible trace element spider plots reveal that the Bukit Mersing basalts have geochemical affinity with Oceanic Island Basalts (OIB) and rift basalts, being enriched in LREEs and Most Incompatible Elements, and no Eu anomaly. Preliminary trace element data for several basalt samples from Usun Apau also show Oceanic Island/Rift affinity. Bimodal volcanism is most often associated with rift environments. Efforts are being made to radiometrically date the volcanics, in part to determine the possibility of future eruptions. The Upper Rajang Valley is remote, covered in tropical rainforest and is very sparsely populated. At this time, there is no information concerning signs of imminent volcanism, such as hot springs and microseismicity.

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

    Science.gov (United States)

    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.

  18. Cenozoic vegetation, climate changes and hominid evolution in tropical Africa

    Science.gov (United States)

    Bonnefille, Raymonde

    2010-07-01

    This paper reviews information on past vegetation of tropical Africa during the Cenozoic, focused upon the last 10 Ma, a time spanning hominid record in Central and East Africa. Summary of palaeobotanical data collected at terrestrial sites are compared with new results on the long term evolution of the continental vegetation zones documented from marine pollen record of two deep sea cores recovered from the Atlantic and Indian Oceans. Section 2 includes a summary of modern distribution of vegetation belts in the African continent and a synthesis of the results of both macrobotanical (fossil wood, leaves and fruits) and microbotanical (mainly pollen) studies presented according to time scale and geographical location. The main features emphasized by the palaeobotanical results are 1) seasonal vegetation and climate documented as soon as the Eocene in Tanzania 2) well diversified forests existing in northern West Ethiopia during the Oligocene 3) high temporal and spatial variabilities of forests composition during the Miocene when deciduous Legume woodland was documented in Ethiopia whereas wetter evergreen forests existed in Western Kenya 4) lack of evidence for an evergreen forest belt, continuous from Western Congo to East Africa. Section 3 presents new original pollen data recovered from a long core in the Gulf of Aden documenting large scale past vegetation changes in East Africa during the last 11 Ma. These results are discussed in comparison with a summarized long pollen sequence previously published from a marine core offshore the Niger delta. This comparison illustrates variations in geographical distribution of large vegetation zone at the continental scale, through time. In Section 4, vegetation changes registered during the last 10 Ma are discussed in relation with the results of isotopic studies and an updated presentation of hominids evolution in Africa. Several changes are shown in the marine records. An expansion of savanna/grassland is shown at 10

  19. What Is Crystalline Silica?

    Science.gov (United States)

    ... 1926.55, 1910.1000). OSHA also requires hazard communication training for workers exposed to crystalline silica, and ... identify, reduce, and eliminate health hazards associated with occupational ... safety and health? OSHA has various publications, standards, technical ...

  20. Cellulose-silica aerogels.

    Science.gov (United States)

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. PMID:25817671

  1. Cenozoic volcanism and lithospheric tectonic evolution in Qiangtang area, northern Qinghai-Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    CHI; Xiaoguo; LI; Cai; JIN; Wei

    2005-01-01

    Following the collision between the Indian and Eurasian plates, the Cenozoic volcanic activities are rather frequent in the Qiangtang area of northern Qinghai-Tibet Plateau. They can be divided into four series: alkaline basalt series, high-K calc-alkaline series, shoshonitic series and peralkaline potassic-ultrapotassic series. Geochemical data suggest that the magma sources of Cenozoic volcanic rocks have transferred from spinel Iherzolite mantle in the early stage to garnet peridotite enriched mantle (EM2) in the later stage. The high Mg# number and extremely high Cr-Ni-Co abundance of high-K calc-alkaline and shoshonitic series andesites in the Qiangtang area indicate that the primary magma might be derived from subduction of continent lithosphere from the Lhasa block. Incompatible element ratios of La/Rb, Zr/Rb, Rb/Nb, K/Nb,Pb/La and K/La of peralkaline potassic-ultrapotassic series lavas in northern Qinghai-Tibet Plateau are lower than island arc volcanic rocks and higher than and similar to oceanic island basalts. This signature indicates that the primary magma derive from a paleo-mantle wedge interfused by fluids derived from asthenosphere and/or subducted mantle lithosphere. But the above element ratios of ultrapotassic lavas in southern Tibet and ultrapotassic lamprophyres in eastern Tibet are higher than and similar to island arc volcanic rocks, which means that the primary magma sources contained a large quantity of crust contaminant from fluids and/or melts derived from subducted continent lithosphere. The studies result supports that the indian continental .lithosphere has underthrust beneath Tibet to about the middle of the plateau, and Eurasian (Qaidam basin) mantle lithosphere has underthrust beneath the Qiangtang area of northern Tibet Plateau. In the paper we demonstrate further that the pulsing cycles of potassic-ultrapotassic volcanism of the Qinghai-Tibet Plateau result from an asthenospher pulsing upwelling caused by the intraplate subduction

  2. The Algerian Margin: an Example of a Reactivation in Compression of a Complex Cenozoic Passive Margin

    Science.gov (United States)

    Domzig, A.; Deverchere, J.; Yelles, K.; Govers, R.; Wortel, R.; Petit, C.; Cataneo, A.; Kherroubi, A.; Teams, M.

    2007-12-01

    The Western Mediterranean underwent a complex Cenozoic history involving subduction of the Tethys Ocean as well as subduction roll-back and associated opening of back-arc basins. During the Oligo-Miocene, the subduction roll-back to the south led to the collision of the Kabylies into the African plate, but subduction continued towards west, causing the Alboran slab to migrate towards the Gibraltar Arc. Northern Africa is at the southern border of this system and is therefore a major study area in the context of slow convergent plates to study the reactivation in compression of a Cenozoic passive margin but also the records of past geodynamic processes. This work aims to characterize the multi-scale structure of the offshore Algerian margin, based on the MARADJA'03 and MARADJA2/SAMRA'05 cruises data (multibeam bathymetry, seismic-reflection, side-scan sonar, backscattering, CHIRP, gravimetry). Tectonic (geomorphology, folds, faults) records reveal large recent and active structures as well as the geological inheritance of the margin. In western Algeria, slab roll-back is likely to have been accompanied by lithospheric tearing (STEP fault) as it has been modelled at a regional scale (Govers and Wortel, 2005): we provide first evidence for the presence of such structure(s) offshore Algeria. The geodynamical conditions have now changed, and we are facing new types of structures. Two main tectonic styles are identified: reverse to the centre and east; and strike-slip to the west. In Central Algeria, the compressional structures are active blind thrusts (Plio-Quaternary) verging to the north (opposite to pre-existing features) expressed as asymmetrical folds, sub-perpendicular to the convergence direction and often en echelon. These faults may all trigger M=6-7.5 earthquakes (e.g. Khair al Din fault near Algiers). Among them, the fault associated with the 2003 Boumerdes event (Mw=6.8) would continue to the surface by flats and ramps creating piggy-back basins or

  3. Impact of changes in river fluxes of silica on the global marine silicon cycle: a model comparison

    Directory of Open Access Journals (Sweden)

    C. Y. Bernard

    2010-02-01

    Full Text Available The availability of dissolved silica (Si in the ocean provides a major control on the growth of siliceous phytoplankton. Diatoms in particular account for a large proportion of oceanic primary production. The original source of the silica is rock weathering, followed by transport of dissolved and biogenic silica to the coastal zone. This model study aims at assessing the sensitivity of the global marine silicon cycle to variations in the river input of silica on timescales ranging from several centuries to millennia. We compare the performance of a box model for the marine silicon cycle to that of a global biogeochemical ocean general circulation model (HAMOCC2 and 5. Results indicate that the average global ocean response to changes in river input of silica is comparable in the models on time scales up to 150 kyrs. While the trends in export production and opal burial are the same, the box model shows a delayed response to the imposed perturbations compared to the general circulation model. Results of both models confirm the important role of the continental margins as a sink for silica at the global scale. Our work also demonstrates that the effects of changes in riverine dissolved silica on ocean biogeochemistry depend on the availability of the other nutrients such as nitrogen, phosphorus and iron. The model results suggest that the effects of reduced silica inputs due to river damming are particularly pronounced in the Gulf of Bengal, Gulf of Mexico and the Amazon plume where they negatively affect opal production. While general circulation models are indispensable when assessing the spatial variation in opal export production and biogenic Si burial in the ocean, this study demonstrates that box models provide a good alternative when studying the average global ocean response to perturbations of the oceanic silica cycle (especially on longer time scales.

  4. Eolian evidence from the Chinese Loess Plateau: the onset of the Late Cenozoic Great Glaciation in the Northern Hemisphere and Qinghai-Xizang Plateau uplift forcing

    Institute of Scientific and Technical Information of China (English)

    安芷生; 王苏民; 吴锡浩; 陈明扬; 孙东怀; 刘秀铭; 王富葆; 李力; 孙有斌; 周卫健; 周杰; 刘晓东; 鹿化煜; 张云翔; 董光荣; 强小科

    1999-01-01

    On the basis of a newly-constructed record of magnetic susceptibility (SUS) and the depositional rate change of eolian loess-red clay sequences in the last 7.2 Ma BP from the Loess Plateau, together with a comparison of a record of δ18O values from the equatorial East Pacific Ocean and eolian Quartz flux variations from the North Pacific Ocean, the evolutionary process of the Late Cenozoic Great Glaciation in the Northern Hemisphere can be divided into three stages: the arrival stage around 7.2—3.4 Ma BP, the initial stage at about 3.4—2.6 Ma BP, and the Great Ice Age since 2.6 Ma BP. The evolution of the East Asian monsoon is characterized by paired winter and summer monsoons, and it is basically composed of the initial stage of weak winter and summer monsoons, the transitional stage of simuhaneous increase in intensity of winter and summer monsoons, and the prevailing stage of strong winter and weak summer monsoons, or weak winter and strong summer monsoons. The Late Cenozoic global tectonic upl

  5. Patterns of Cenozoic sediment flux from western Scandinavia

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.

    2012-01-01

    tectonism, climate and climate change. Western Scandinavia, the northern British Isles and the Faeroe-Shetland Platform were significant sediment sources during the Paleocene, which is well founded in tectonic causes related to the opening of the North Atlantic. From the Eocene and onward, variations in the...... sediment flux from western Scandinavia correlate better with climate and climate change. During the Eocene, sediment production was low. From the late Eocene onward, increased seasonality may have contributed to stimulating the sediment flux. Significant climatic cooling episodes correlate with Oligocene......The significance of variations in the sediment flux from western Scandinavia during the Cenozoic has been a matter of debate for decades. Here we compile the sediment flux using seismic data, boreholes and results from other publications and discuss the relative importance of causal agents such as...

  6. The 13 million year Cenozoic pulse of the Earth

    Science.gov (United States)

    Chen, Jiasheng; Kravchinsky, Vadim A.; Liu, Xiuming

    2015-12-01

    The geomagnetic polarity reversal rate changes radically from very low to extremely high. Such process indicates fundamental changes in the Earth's core reorganization and core-mantle boundary heat flow fluctuations. However, we still do not know how critical such changes are to surface geology and climate processes. Our analysis of the geomagnetic reversal frequency, oxygen isotope record, and tectonic plate subduction rate, which are indicators of the changes in the heat flux at the core mantle boundary, climate and plate tectonic activity, shows that all these changes indicate similar rhythms on million years' timescale in the Cenozoic Era occurring with the common fundamental periodicity of ∼13 Myr during most of the time. The periodicity is disrupted only during the last 20 Myr. Such periodic behavior suggests that large scale climate and tectonic changes at the Earth's surface are closely connected with the million year timescale cyclical reorganization of the Earth's interior.

  7. Modern and Cenozoic records of magnesium behaviour from foraminiferal Mg isotopes

    Directory of Open Access Journals (Sweden)

    P. A. E. Pogge von Strandmann

    2014-05-01

    Full Text Available Magnesium is an element critically involved in the carbon cycle, because weathering of Ca–Mg silicates removes atmospheric CO2 into rivers, and formation of Ca–Mg carbonates in the oceans removes carbon from the ocean–atmosphere system. Hence the Mg cycle holds the potential to provide valuable insights into Cenozoic climate-system history, and the shift during this time from a greenhouse to icehouse state. We present Mg isotope ratios for the past 40 Myr using planktic foraminifers as an archive. Modern foraminifera, which discriminate against elemental and isotopically heavy Mg during calcification, show no correlation between the Mg isotope composition (δ26Mg and temperature, Mg / Ca or other parameters such as carbonate saturation (Δ CO3. However, inter-species isotopic differences imply that only well-calibrated single species should be used for reconstruction of past seawater. Seawater δ26Mg inferred from the foraminiferal record decreased from ~ 0‰ at 15 Ma, to −0.83‰ at the present day, which coincides with increases in seawater lithium and oxygen isotope ratios. It strongly suggests that neither Mg concentrations nor isotope ratios are at steady-state in modern oceans, given its ~ 10 Myr residence time. From these data, we have developed a dynamic box model to understand and constrain changes in Mg sources to the oceans (rivers and Mg sinks (dolomitisation and hydrothermal alteration. Our estimates of seawater Mg concentrations through time are similar to those independently determined by pore waters and fluid inclusions. Modelling suggests that dolomite formation and the riverine Mg flux are the primary controls on the δ26Mg of seawater, while hydrothermal Mg removal and the δ26Mg of rivers are more minor controls. Using riverine flux and isotope ratios inferred from the 87Sr / 86Sr record, the modelled Mg removal by dolomite formation shows minima in the Oligocene and at the present day (with decreasing trends from 15

  8. Silica in alkaline brines

    Science.gov (United States)

    Jones, B.F.; Rettig, S.L.; Eugster, H.P.

    1967-01-01

    Analysis of sodium carbonate-bicarbonate brines from closed basins in volcanic terranes of Oregon and Kenya reveals silica contents of up to 2700 parts per million at pH's higher than 10. These high concentrations of SiO 2 can be attributed to reaction of waters with silicates, and subsequent evaporative concentration accompanied by a rise in pH. Supersaturation with respect to amorphous silica may occur and persist for brines that are out of contact with silicate muds and undersaturated with respect to trona; correlation of SiO2 with concentration of Na and total CO2 support this interpretation. Addition of moredilute waters to alkaline brines may lower the pH and cause inorganic precipitation of substantial amounts of silica.

  9. Significant Biogenic Silica Retention from Reverse Weathering in Non-deltaic Sediments

    Science.gov (United States)

    Krause, J. W.; Larson, A. M.; Darrow, E. S.; Carmichael, R. H.

    2014-12-01

    Coastal biogeochemical processes exert important controls on the net delivery of silicon to the ocean. Reverse weathering of biogenic silica by authigenic transformation has been suggested to be an important processes for silicon retention in coastal sediments. Many reported sediment biogenic silica measurements may underestimate this authigenically-transformed fraction; for example, the incorporation of metal hydroxides with the biogenic silica matrix suppresses the ability to distinguish it from mineral silica when using a traditional alkaline leach. Most studies demonstrating the importance of reverse weathering on biogenic silica have examined deltaic sediments in river dominated systems (e.g. Mississippi, Amazon), but this has not been examined in sediments which lack strong fluvial input. Using sediment cores from the outside the Mississippi River plume, we adapted a method which lessens the interference of metal hydroxides on biogenic silica by using an initial acid leach. The addition of this step increased the measured biogenic silica up to five-fold above that detected using a traditional alkaline digestion method. The magnitude of authigenically-altered biogenic silica in these cores was significant, representing a majority of the sediment biogenic silica pool at most depths. These findings confirm the importance of reverse-weathered biogenic silica as a mechanism for silicon retention and suggest the significance of this process may be more widespread.

  10. Geochemistry of cenozoic basaltic rocks from Shandong province and its implication for mantle process in North China

    International Nuclear Information System (INIS)

    Cenozoic (Miocene to Pleistocene) basaltic rocks found in Shandong province of northern China include tholeiite, olivine tholeiite and alkali basalt. We present major, trace and rare earth elements data of these basalts and together with Sr-Nd isotopic data in the literatures to discuss the petrogenesis of these basalts. The basalts from Penglai area have higher K, Na and P and incompatible elements, but lower Ca, Mg and compatible elements contents than those from Changle area of Shandong province. Spidergrams indicate that Cenozoic basalts from Shandong province have geochemical characteristics similar to those of ocean island basalts (OIB) with slight positive Nb anomaly. The negative Ba, Rb and K anomalies found in the alkali basalts suggest the presence of residual phlogopite in the mantle source, indicating a metasomatic event occurred before the partial melting. The 143Nd/144Nd vs. 87Sr/86Sr plot suggested that basalts from Shandong province can be produced by MORB and EM-I components mixing. We propose that the EM-I type lithospheric mantle may have been produced by the recent H2O-CO2 -fluids metasomatism and the fluids may be derived from dehydration of the subducted slab. Based on Shaw's equation, the basalts from eastern and central Shandong province have undergone different degrees of particle melting from the mantle source. Degrees of partial melting and chemical composition of basalts from Shandong province suggest that the lithosphere has thickened progressively since the Miocene. On the basis of Ar-Ar ages of this study and the fractional crystallization model proposed by Brooks and Nielsen (1982), we suggest that basalts from Changle and Penglai areas belong to different magmatic systems which have undergone fractional crystallization and evolved progressively to produce other types of basalts. (author)

  11. Types of Cenozoic Mollusca from Java in the Martin Collection of Naturalis

    NARCIS (Netherlands)

    Leloux, J.; Wesselingh, F.P.

    2009-01-01

    An updated type catalogue of the Martin Collection (fossil Mollusca, predominantly from the Cenozoic of Java, Indonesia) is presented. Type specimen data, updated locality data, and illustrations are given.

  12. Cenozoic tectonics of the Tuz Gölü Basin (Central Anatolian Plateau, Turkey)

    OpenAIRE

    FERNÁNDEZ-BLANCO, David; BERTOTTI, Giovanni; ÇİNER, T. Attila

    2013-01-01

    We present a new 3D geologic model for the architecture and Cenozoic tectonic evolution of the Tuz Gölü Basin, a major sedimentary basin in the Central Anatolian orogenic plateau. This model is grounded on 7 depth-converted seismic reflection profiles in combination with the analysis of backstripped subsidence curves, isochore maps, and a palinspastically restored cross-section. Two stages of basin formation are detected during Cenozoic times. During the Palaeogene, around 2 km of basement su...

  13. Late Cenozoic fluvial dynamics of the River Tana, Kenya, an uplift dominated record

    Science.gov (United States)

    Veldkamp, A.; Buis, E.; Wijbrans, J. R.; Olago, D. O.; Boshoven, E. H.; Marée, M.; van den Berg van Saparoea, R. M.

    2007-11-01

    The Late Cenozoic development of the River Tana in Kenya has been reconstructed for its central reach near its confluence with the River Mutonga, which drains the Mount Kenya region. Age control for this system has been provided by K-Ar and Ar-Ar dating. Between 3.21 and 2.65 Ma a major updoming occurred, in relation to the formation of the Kenyan rift valley. The tilting related to this doming has been reconstructed from lava flows that preserve former river gradients. Linear projection of these trends to the current rift valley rim suggests a net updoming of the eastern Gregory Rift valley by at least ∼1 km during 3.21-2.65 Ma. In contrast, since 2.65 Ma the Tana system has been mainly subject to relatively minor epeirogenic uplift. Changing climatic conditions combined with continuing uplift yielded a typical staircase of strath terraces with at least 10 distinct levels. A more detailed reconstruction of the incision rates since 215 ka has been made, by correlating mineralogically fingerprinted volcaniclastic Tana deposits with dated tephras in a lake record. These volcaniclastic sediments were deposited during glacial periods, contemporaneous with lahars. The reconstructed incision rates for the three youngest terraces are ∼0.1-0.2 mm a-1, thus considerably faster than the overall average rate of valley incision since the Mid-Pliocene, of 0.06 mm a-1. A plausible uplift history has been reconstructed using the estimated ages of the Tana terraces and marine terraces on the Indian Ocean coastline. The result suggests an increase in the rate of incision by the River Tana at ∼0.9 Ma, an observation typical in most European river terrace staircases. The reconstructed Late Quaternary development of Tana valley indicates that a similar Quaternary uplift mechanism has operated in both Europe and East Kenya, suggesting a globally applicable process.

  14. Variations in sediment transport at the central Argentine continental margin during the Cenozoic

    Science.gov (United States)

    Gruetzner, Jens; Uenzelmann-Neben, Gabriele; Franke, Dieter

    2012-10-01

    The construction of the sedimentary cover at most passive continental margins includes gravitational downslope transport and along-slope contourite deposition, which are controlled by tectonics, climate and oceanography. At the eastern continental margin of Argentina the history of deposition and erosion is intimately linked to the evolution of the South Atlantic and its water masses. Here we present a detailed seismic investigation of the mixed depositional system located between 41°S and 45°S. The study provides a northward complement to prior investigations from the southern Argentine margin and together with these may be used as background information for future ocean drilling in the region. Prominent features in our seismic cross sections are submarine canyons, mass wasting deposits, contourite channels, and sediment drifts. Four major seismic units above regional reflector PLe (˜65 Ma) are separated by distinct unconformities of regional extent. Using a dense grid of reflection seismic profiles, we mapped the depocenter geometries of the seismic units and derived a chronology of the depositional processes during the Cenozoic. While the Paleocene/Eocene (˜65-34 Ma) is characterized by hemipelagic sedimentation under relatively sluggish bottom water conditions, strong Antarctic bottom water (AABW) circulation led to widespread erosion on the slope and growth of a detached sediment drift during the Oligocene and early Miocene (˜34-17 Ma). After deposition of an aggradational seismic unit interpreted to represent the Mid-Miocene climatic optimum (˜17-14 Ma), gravitational downslope sediment transport increased during the middle to late Miocene (˜14-6 Ma) possibly related to tectonic uplift in South America. The Pliocene to Holocene unit (<˜6 Ma) is very heterogeneous and formed by interactions of downslope and along-slope sediment transport processes as indicated by the evolution of canyons, slope plastered drifts and channels.

  15. Fossil Cenozoic crassatelline bivalves from Peru: New species and generic insights

    Directory of Open Access Journals (Sweden)

    Thomas J. DeVries

    2016-08-01

    Full Text Available Discoveries of new fossil Cenozoic crassatellines in Peru provide a new phylogenetic perspective on “large” Neogene genera, in which four lineages are considered to have arisen independently from different Paleogene Crassatella ancestors. Latest Oligocene and early Miocene species of the new genus Tilicrassatella gen. nov.―T. ponderosa, T. torrens sp. nov., and T. sanmartini sp. nov. from the East Pisco Basin―probably evolved from the late Eocene species, Crassatella rafaeli sp. nov., which itself differed in significant respects from slightly older species of the East Pisco Basin, C. neorhynchus and C. pedroi sp. nov. The paciphilic genus, Hybolophus, is raised to full generic status. Added to its ranks are the East Pisco Miocene species H. maleficae sp. nov., H. terrestris sp. nov., and the oldest species of the genus, the late Eocene or Oligocene H. disenum sp. nov. from the Talara Basin of northern Peru. Kalolophus gen. nov., encompassing circum-Caribbean fossil species, the extant species, K. speciosus, and the trans-isthmus species, K. antillarum, appears to have evolved from the early Oligocene Floridian species, Crassatella portelli sp. nov. The genus Marvacrassatella is a western Atlantic Miocene lineage most likely descended from Kalolophus. The genus Eucrassatella is restricted to Australian and New Zealand taxa. The Eocene New Zealand species, Spissatella media, is transferred to Eucrassatella and deemed a candidate for the most recent common ancestor of younger Eucrassatella and all Spissatella species. In the southern Pacific Ocean, the circum-Caribbean region, and tropical western America, crassatelline lineages developed one or more of the following characters: large resilifers, smooth ventral margins, and an extended left anterior cardinal tooth. Some of these late Paleogene convergent character changes might have countered increased shear forces exerted on the crassatelline valves while burrowing into finer-grained and

  16. Production of silica aerogel

    International Nuclear Information System (INIS)

    A production facility for silica aerogel has been set up in Lund. Aerogel is now produced in large quantities with the refractive indices of 1.03 and 1.05. The standard block size is 18 x 18 x 3 cm3. (Auth.)

  17. Effect of Vegetation on the Late Miocene Ocean Circulation

    Directory of Open Access Journals (Sweden)

    Gerrit Lohmann

    2015-11-01

    Full Text Available We examine the role of the vegetation cover and the associated hydrological cycle on the deep ocean circulation during the Late Miocene (~10 million years ago. In our simulations, an open Central American gateway and exchange with fresh Pacific waters leads to a weak and shallow thermohaline circulation in the North Atlantic Ocean which is consistent with most other modeling studies for this time period. Here, we estimate the effect of a changed vegetation cover on the ocean general circulation using atmospheric circulation model simulations for the late Miocene climate with 353 ppmv CO2 level. The Late Miocene land surface cover reduces the albedo, the net evaporation in the North Atlantic catchment is affected and the North Atlantic water becomes more saline leading to a more vigorous North Atlantic Deep Water circulation. These effects reveal potentially important feedbacks between the ocean circulation, the hydrological cycle and the land surface cover for Cenozoic climate evolution.

  18. Seepage carbonate mounds in Cenozoic sedimentary sequences from the Las Minas Basin, SE Spain

    Science.gov (United States)

    Pozo, M.; Calvo, J. P.; Scopelliti, G.; González-Acebrón, L.

    2016-04-01

    A number of carbonate mounds composed of indurate, strongly folded and/or brecciated calcite and dolomite beds occur interstratified in Cenozoic sedimentary sequences from the Las Minas Basin. Part of the fabric of the rock forming the carbonate mounds is composed of laminated to banded dolostone similar to the host rock but showing contrasted lithification. Moreover, the carbonate deposits of the mounds display aggrading neomorphism of dolomite, partial replacement of dolomite by calcite, calcite cementation, and extensive silicification, locally resulting in box-work fabric. Eight main lithofacies were distinguished in the carbonate mound deposits. In some lithofacies, chert is present as both microcrystalline to fibro-radial quartz and opal, the latter occurring mainly as cement whereas the former replace the carbonate and infill voids. Yet one of the carbonate mounds shows distinctive petrography and geochemical features thus suggesting a distinctive growth pattern. The carbon isotope compositions of calcite from the mound samples range from - 11.56 to - 5.15 δ‰ whilst dolomite is depleted in 13C, with values of - 12.38 to 3.02 δ‰. Oxygen isotopic compositions vary from - 9.42 to - 4.64 δ‰ for calcite and between - 6.68 and 8.19 δ‰ for dolomite. Carbonate in the mounds shows significant enrichment in Co, Cr, Ni and Pb content, especially in the strongly deformed (F-2-2 lithofacies) and brecciated carbonate (F-4). The carbonate deposits show depletion in REE and Y in contrast to that determined in lutite. The formation of the carbonate mounds was related to local artesian seepage thermal water flows of moderate to relative high temperatures. Pressure differences between the low permeability host rock and the circulating fluids accounted for dilational fracturing and brecciation of the host sediment packages, which combined with precipitation of new carbonate and silica mineral phases. Locally, some carbonate mounds developed where groundwater

  19. Cenozoic vertical motions of the western continental margin of Peninsular India

    Science.gov (United States)

    Richards, Fred; Hoggard, Mark; White, Nicky

    2016-04-01

    Despite the cessation of rifting at ˜65 Ma and its remoteness from active convergence, the topography of Peninsular India is dominated by a dramatic, high-elevation escarpment along its western margin: the Western Ghats (˜1 - 1.5 km amsl). Inland of the escarpment, South Indian topography exhibits a long-wavelength (>1000 km), low-angle (˜0.1°) eastward tilt down to the Krishna-Godavari and Cauvery deltas on the eastern continental margin. Offshore, oceanic residual depth measurements show an identical long-wavelength asymmetry from highs of +1 km in the Arabian Sea to lows of -1.2 km in the Bay of Bengal. Strong evidence from margin stratigraphy, dated palaeosurfaces, thermochronology, cosmogenic nuclides and marine terraces combine to suggest that, following a period of relative quiescence from 50 Ma - 25 Ma, the present-day topography evolved in response to Neogene uplift and erosion along the western Indian margin. By jointly inverting 530 longitudinal river profiles for uplift rate and calibrating our inversions against these geological constraints, we successfully place this Cenozoic landscape evolution into a more complete spatio-temporal framework. The results demonstrate slow growth of the eastward tilt from 50 Ma - 25 Ma (≤0.02 mm a‑1), preceding a phase of increasingly rapid development - initiating in the south - from 25 Ma onwards (≤0.2 mm a‑1). The onset of rapid uplift pre-dates the initial intensification of the Indian monsoon by >15 Ma, suggesting that rock uplift and not climate change is primarily responsible for the modern-day relief of the peninsula. Previous studies have aimed to explain this topographic evolution by invoking flexural isostatic mechanisms involving denudation, sediment loading and/or underplating. However, seismological constraints show that South Indian topography deviates significantly from crustal isostatic expectations, while the 9.8‑2.2+3.8 km effective elastic thickness of the region generates ˜125 km

  20. Geochemically tracking provenance changes in marine sediment from the South Pacific Gyre throughout the Cenozoic

    Science.gov (United States)

    Dunlea, A. G.; Murray, R. W.; Sauvage, J.; Spivack, A. J.; Harris, R. N.; D'Hondt, S. L.

    2012-12-01

    The South Pacific Gyre (SPG), characterized by extremely slow sedimentation rates, is the world's largest oceanic desert. The little eolian dust from continents in the Southern Hemisphere must traverse great distances to reach the SPG, and the ultra-oligotrophic waters minimize the biogenic flux of sediment to the seafloor. However sparse, the pelagic sediment that is ultimately found on the seafloor retains a chemical record that can be used to trace its origin. Using cores from Integrated Ocean Drilling Program Expedition 329, we trace downcore fluctuations in major, trace, and rare earth element (REE) composition and flux to yield clues to the geological, chemical, and biological evolution of the SPG throughout the Cenozoic. The shipboard scientific party generally described the completely oxic, brown pelagic clays recovered during Exp. 329 as zeolitic metalliferous clay. The homogenous, very fine-grained nature of these sediments speaks to the challenges we face in resolving eolian detrital material ("dust"), fine-grained ash (commonly altered), and authigenic aluminosilicates from one another. Based on ICP-ES and ICP-MS analyses followed by multivariate statistical treatments, we are developing chemical records from a number of sites located throughout the SPG. Building on earlier work at DSDP Site 596 (Zhou and Kyte, 1992, Paleocean., 7, 441-465), and based on backtrack paths from 100 Ma forward, we are working to construct a regionally and temporally continuous paleoclimatological history of the SPG. Preliminary La-Th-Sc concentrations from Sites U1367, U1368, and U1369 show a distinct authigenic influence, but several refractory elements retain their original provenance signature. Sediment ages are constrained using a constant-Co model, based on the geochemically similar work that Zhou and Kyte (1992) performed in the SPG. REE concentrations normalized to post-archean average shale (PAAS) reveal a negative Ce anomaly that becomes more pronounced closer to

  1. Late Cenozoic volcanism in central Myanmar: Geochemical characteristics and geodynamic significance

    Science.gov (United States)

    Lee, Hao-Yang; Chung, Sun-Lin; Yang, Hsiao-Ming

    2016-02-01

    Late Cenozoic volcanism occurred in the central Myanmar basin, a region that is marked by the existence of the dextral Sagaing fault linking the eastern Himalayan Syntaxis to the north and the Andaman Sea to the south. Here we report new geochemical data of volcanic rocks from Monywa, Mt. Popa and Singu areas erupting in two distinct stages, i.e., mid-Miocene and Quaternary, respectively. While calc-alkaline rocks showing arc-like geochemical features are abundant, an apparent change in magma composition is observed between these two stages. The mid-Miocene rocks are mainly dominated by intermediate compositions (SiO2 = 53-61 wt.%) and typical of high-K calc-alkaline nature. They exhibit uniform Sr and Nd isotopic ratios (ISr ≈ ~ 0.705; εNd(T) = + 2.7 to + 1.6), suggesting a juvenile mantle origin related to the subduction of Indian oceanic lithosphere beneath this part of Asia. The Quaternary rocks consist mainly of basalts that, however, show variations in geochemical features. Three suites in this stage are observed: (1) calc-alkaline suite (basalts and basaltic andesites from Monywa and Mt. Popa: SiO2 = 48-56 wt.%; ISr = 0.704 to 0.705; εNd(T) = + 3.1 to + 2.1), originating from partial melting of a "remnant" juvenile mantle wedge, (2) alkali basalt suite I (basanites from Monywa: SiO2 ≈ 45 wt.%; MgO = 10-12 wt.%; K2O ≈ 2.0 wt.%; ISr = 0.704 to 0.705; εNd(T) ≈ + 3.6), interpreted as the product of small-degree melting from an amphibole lherzolite in the lithospheric mantle, and (3) alkali basalt suite II (trachybasalts from Singu: SiO2 ≈ 51 wt.%; K2O = 2.6-3.5 wt.%; ISr ≈ 0.706; εNd(T) = + 1.6 to + 0.9), interpreted as the product of partial melting from the asthenosphere. All processes of magma generation were related to the India-Asia collision that caused regional plate reorganization, a transition from oblique subduction to dextral movement in the Miocene, and subsequent "rollback" of the subducted Indian oceanic lithosphere in the

  2. Trace Element Geochemistry of Cenozoic Volcanic Rocks in Shandong Province

    Institute of Scientific and Technical Information of China (English)

    陈道公; 李彬贤; 等

    1989-01-01

    The Cenozoic volcanic rock of Shandong Province are mainly alkalic and strongly alkalic basaltic rocks.The Contents of major and trace elements including transitional,incompatible and rare-earth elements were determined.The chemical characterisitics of major and trace elements indicate that these basaltic rocks were derived from a mantle source and probably represent a primary magma,I,e.,unmodifiecd partical melts of mantle peridotite in terms of Mg values,correlatione between P2O5 and Ce,Sr,Ni and Rb concentrations,mantle xenoliths,etc.The abundances of trace elements vary systematically from west to east.The compatible transition elements such as Co,Ni,and Cr show a remarkable depletion,whereas the incompatible and rare-earth elements are abundant as viewed from the chondrite-nor-malized patterns.The chemical composition and correlation are consistent with the tectonic setting.According to the batch and fractional partial melting theory,the trace element contents of Shandong volcanic rocks can be calculated from the two-component mixing model.

  3. Successor Characteristics of the Mesozoic and Cenozoic Songliao Basins

    Institute of Scientific and Technical Information of China (English)

    LI Zhongquan; Timothy KUSKY; YING Danlin; GUO Xiaoyu; LI Hongkui

    2008-01-01

    The Songliao basin is a complex successor basin that was initiated in the Mesozoic and experienced multiple periods of reactivation. Based on seismic and drilling data, as well as regional geologic research, we suggest that the Songliao basin contains several different successor basins resting on top of Carboniferous-Permian folded strata forming the basement to the Songliao basin. These basins include the Triassic-Mid Jurassic Paleo-foreland basin, the Late Jurassic-Early Cretaceous downfaulted basin, and an early Cretaceous depressed basin (since the Denglouku Group). This paper presents a systematic study of the basin-mountain interactions, and reveals that there are different types of prototype basin at different geologic times. These prototype basins sequentially superimposed and formed the large Songliao basin. Discovery of the Triassic-early Middle Jurassic paleo-foreland basin fills a Triassic-early Middle Jurassic gap in the geologic history of the Songliao basin. The paleoforeland basin, downfaulted basin, and depressed thermal subsidence basin all together represent the whole Mesozoic-Cenozoic geologic history and deformation of the Songliao basin. Discovery of the Triassic-early Middle Jurassic paleo-foreland basin plays an important role both for deep natural gas exploration and the study of basin-mountain coupling in north China and eastern China in general. This example gives dramatic evidence that we should give much more attention to the polyphase tectonic evolution of related basins for the next phase of exploration and study.

  4. Late Cenozoic sedimentary and tectonic history of south Buton, Indonesia

    Science.gov (United States)

    Fortuin, A. R.; De Smet, M. E. M.; Hadiwasastra, S.; Van Marle, L. J.; Troelstra, S. R.; Tjokrosapoetro, S.

    A description and interpretation are given of the Upper Cenozoic sedimentary record of south Buton. Various sections and outcrops were studied and sampled for their microfossil content, to provide age and paleobathymetrical data. Together with information from the literature, these data from the base for a geohistory analysis to evaluate the vertical motions. Deposition started some 11 Ma ago, after the main deformation of the island, which was related to the collision of a microplate carrying Buton, with the southeast arm of Sulawesi. Coarse and fine terrigenous debris accumulated in a rapidly subsiding foreland basin; subsidence may have exceeded 100 cm/ka. When the rate of subsidence decreased a late Miocene-early Pliocene period of quiet pelagic sedimentation followed. From the late Pliocene onwards (around 3.5 Ma BP) an overall uplift took place, with rates between 30-120 cm/ka. This drastic change is explained by the collision of Buton with a submerged microcontinent that presently forms the Tukang Besi platform, situated southeast of Buton, which interaction resulted in wrench type tectonics and a clockwise rotation of over 60° for south Buton.

  5. Mid Cenozoic freshwater wetlands of the Sunda region

    Directory of Open Access Journals (Sweden)

    Robert J. Morley

    2013-08-01

    Full Text Available The Sunda region was the scene of widespread rifting during the mid-Cenozoic, resulting in the development of numerous large lake-filled rifts, analogous in scale to the rift valley system of East Africa. The Tonle Sap in Cambodia forms the closest modern analogue for these lakes in the Southeast Asian region. Many of the palaeolakes were long lived, continuing uninterrupted as open lakes for several millions of years during the Oligocene. Smaller rift systems infilled with fluvial sediments, but the larger ones remained as lakes, and with Late Oligocene subsidence, were transformed by brackish, and in the earliest Miocene, by marine incursion, into large inland seas. These seas reached their greatest extent at the time of the mid Miocene thermal maximum. This paper describes the development and eventual demise of these lakes following marine transgression, and, based on their rich content of pollen and spores, illustrates the variety of fresh and brackish water swamp communities which developed around their margins. The marginal swamps can be divided into: i seasonally inundated swamps, mainly during the Oligocene, characterised by Barringtonia, Lagerstroemia and grasses/sedges; ii fern swamps and iii from the Late Oligocene onward alluvial swamps, often characterised by Pandanus; and iv peat swamps. The latter can be differentiated into kerapah peat swamps, first occurring during the Oligocene, and basinal peat swamps, becoming widespread from the Early Miocene onward.

  6. A first-order global model of Late Cenozoic climatic change: Orbital forcing as a pacemaker of the ice ages

    Science.gov (United States)

    Saltzman, Barry

    1992-01-01

    The development of a theory of the evolution of the climate of the earth over millions of years can be subdivided into three fundamental, nested, problems: (1) to establish by equilibrium climate models (e.g., general circulation models) the diagnostic relations, valid at any time, between the fast-response climate variables (i.e., the 'weather statistics') and both the prescribed external radiative forcing and the prescribed distribution of the slow response variables (e.g., the ice sheets and shelves, the deep ocean state, and the atmospheric CO2 concentration); (2) to construct, by an essentially inductive process, a model of the time-dependent evolution of the slow-response climatic variables over time scales longer than the damping times of these variables but shorter than the time scale of tectonic changes in the boundary conditions (e.g., altered geography and elevation of the continents, slow outgassing, and weathering) and ultra-slow astronomical changes such as in the solar radiative output; and (3) to determine the nature of these ultra-slow processes and their effects on the evolution of the equilibrium state of the climatic system about which the above time-dependent variations occur. All three problems are discussed in the context of the theory of the Quaternary climate, which will be incomplete unless it is embedded in a more general theory for the fuller Cenozoic that can accommodate the onset of the ice-age fluctuations. We construct a simple mathematical model for the Late Cenozoic climatic changes based on the hypothesis that forced and free variations of the concentration of atmospheric greenhouse gases (notably CO2), coupled with changes in the deep ocean state and ice mass, under the additional 'pacemaking' influence of earth-orbital forcing, are primary determinants of the climate state over this period. Our goal is to illustrate how a single model governing both very long term variations and higher frequency oscillatory variations in the

  7. Aniline incorporated silica nanobubbles

    Indian Academy of Sciences (India)

    M J Rosemary; V Suryanarayanan; Ian Maclaren; T Pradeep

    2006-09-01

    We report the synthesis of stearate functionalized nanobubbles of SiO2 with a few aniline molecules inside, represented as C6H5NH2@SiO2@stearate, exhibiting fluorescence with red-shifted emission. Stearic acid functionalization allows the materials to be handled just as free molecules, for dissolution, precipitation, storage etc. The methodology adopted involves adsorption of aniline on the surface of gold nanoparticles with subsequent growth of a silica shell through monolayers, followed by the selective removal of the metal core either using sodium cyanide or by a new reaction involving halocarbons. The material is stable and can be stored for extended periods without loss of fluorescence. Spectroscopic and voltammetric properties of the system were studied in order to understand the interaction of aniline with the shell as well as the monolayer, whilst transmission electron microscopy has been used to study the silica shell.

  8. running ocean

    Directory of Open Access Journals (Sweden)

    Lokenath Debnath

    1978-01-01

    Full Text Available A theory is presented of the generation and propagation of the two and the three dimensional tsunamis in a shallow running ocean due to the action of an arbitrary ocean floor or ocean surface disturbance. Integral solutions for both two and three dimensional problems are obtained by using the generalized Fourier and Laplace transforms. An asymptotic analysis is carried out for the investigation of the principal features of the free surface elevation. It is found that the propagation of the tsunamis depends on the relative magnitude of the given speed of the running ocean and the wave speed of the shallow ocean. When the speed of the running ocean is less than the speed of the shallow ocean wave, both the two and the three dimensional free surface elevation represent the generation and propagation of surface waves which decay asymptotically as t−12 for the two dimensional case and as t−1 for the three dimensional tsunamis. Several important features of the solution are discussed in some detail. As an application of the general theory, some physically realistic ocean floor disturbances are included in this paper.

  9. Ocean technology

    Digital Repository Service at National Institute of Oceanography (India)

    Peshwe, V.B.

    stream_size 2 stream_content_type text/plain stream_name Voices_Oceans_1996_113.pdf.txt stream_source_info Voices_Oceans_1996_113.pdf.txt Content-Encoding ISO-8859-1 Content-Type text/plain; charset=ISO-8859-1 ...

  10. Genesis of the Madang Cenozoic sodic alkaline basalt in the eastern margin of the Tibetan Plateau and its continental dynamic implications

    Institute of Scientific and Technical Information of China (English)

    LAI; ShaoCong; ZHANG; GuoWei; LI; YongFei; QIN; JiangFeng

    2007-01-01

    The Madang Cenozoic sodic alkaline basalt occurred in the eastern margin of the Tibetan Plateau, where is a key tectonic transform region of Tibet, North China, and Yangtze blocks. The basalts are characterized by the variation in SiO2=42%―51%, Na2O/K2O>4, belonging to the sodic alkaline basalt series. The rocks are enriched in Ba, Th, Nb, Ta, relative to a slight depletion in K, Rb in the trace and rare earth element (REE) spider diagrams that are similar to the typical oceanic island alkaline basalt. The Sr-Nd-Pb isotopic compositions suggest that they are derived from a mixed mantle reservoir. The western Qinling-Songpan tectonic region was controlled by Tibet, North China and Yangtze blocks since Cenozoic, therefore, the region was in the stage of the substance converge from the mantle to upper crust, producing a mixed mantle reservoir in the studied area. The Madang basalts occurred in the specific tectonic background, they result from partial melting of a mixed asthenospheric mantle reservoir in the western Qinling-Songpan tectonic node.

  11. 21 CFR 582.1711 - Silica aerogel.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Silica aerogel. 582.1711 Section 582.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  12. 21 CFR 182.1711 - Silica aerogel.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Silica aerogel. 182.1711 Section 182.1711 Food and....1711 Silica aerogel. (a) Product. Silica aerogel as a finely powdered microcellular silica foam having a minimum silica content of 89.5 percent. (b) (c) Limitations, restrictions, or explanation....

  13. Terrestrial ecosystems and the global biogeochemical silica cycle

    Science.gov (United States)

    Conley, Daniel J.

    2002-12-01

    Most research on the global Si cycle has focused nearly exclusively on weathering or the oceanic Si cycle and has not explored the complexity of the terrestrial biogeochemical cycle. The global biogeochemical Si cycle is of great interest because of its impact on global CO2 concentrations through the combined processes of weathering of silicate minerals and transfer of CO2 from the atmosphere to the lithosphere. A sizable pool of Si is contained as accumulations of amorphous silica, or biogenic silica (BSi), in living tissues of growing plants, known as phytoliths, and, after decomposition of organic material, as remains in the soil. The annual fixation of phytolith silica ranges from 60-200 Tmol yr-1 and rivals that fixed in the oceanic biogeochemical cycle (240 Tmol yr-1). Internal recycling of the phytolith pool is intense with riverine fluxes of dissolved silicate to the oceans buffered by the terrestrial biogeochemical Si cycle, challenging the ability of weathering models to predict rates of weathering and consequently, changes in global climate. Consideration must be given to the influence of the terrestrial BSi pool on variations in the global biogeochemical Si cycle over geologic time and the influence man has had on modifying both the terrestrial and aquatic biogeochemical cycles.

  14. Late Cenozoic structure and stratigraphy of south-central Washington

    International Nuclear Information System (INIS)

    The structural framework of the Columbia Basin began developing before Columbia River Basalt Group (CRBG) volcanism. Prior to 17.5 Ma, the eastern part of the basin was a relatively stable area, with a basement of Paleozoic and older crystalline rock. The western part was an area of subsidence in which large volumes of sediment and volcanic rocks accumulated. Concurrent with eruption of the CRBG, anticlinal ridges of the Yakima Fold Belt (YFB) were growing under north-south compression. Topographic expression of these features was later masked by the large volume of CRBG basalt flowing west from fissures in the eastern Columbia Basin. The folds continued to develop after cessation of volcanism, leading to as much as 1,000 m of structural relief in the past 10 million years. Post-CRBG evolution of the Columbia Basin is recorded principally in folding and faulting in the YFB and sediments deposited in the basins. The accompanying tectonism resulted in lateral migration of major depositional systems into subsiding structural lows. Although known late Cenozoic faults are on anticlinal ridges, earthquake focal mechanisms and contemporary strain measurements indicate most stress release is occurring in the synclinal areas under north-south compression. There is no obvious correlation between focal mechanisms for earthquakes whose foci are in the CRBG and the location of known faults. High in situ stress values help to explain the occurrence of microseismicity in the Columbia Basin but not the pattern. Microseismicity appears to occur in unaltered fresh basalt. Faulted basalt associated with the YFB is highly brecciated and commonly altered to clay. The high stress, abundance of ground water in confined aquifers of the CRBG, and altered basalt in fault zones suggest that the frontal faults on the anticlinal ridges probably have some aseismic deformation. 85 refs

  15. 中国及邻区中新生代大型大陆扩张盆地及其造山作用(续)%Meso-Cenozoic great continental spreading basins and their orogeny of China and adjacent regions

    Institute of Scientific and Technical Information of China (English)

    郭福祥

    2001-01-01

    Characteristics and nature of the Meso-Cenozoic great continental spreading basins in China and adjacent regions depend on the relative positions of the allied adjacent oceans. Intracontinental,epicontinental and marginal basins were respectively developed from the inland to the Meso-Cenozoic Tethys coast and Northwest Pacific coast,each having three series. These series are symmetrically arranged in feather-form.The general thrend is that the closer they are to the coasts,the stronger their activity,and the newer their evolutionary generations. The basins were in a spreading state and belonged to geotectonic spreading units possessing orogeny in their devolopment period. They play a decisive role in mould-making of orogenic belt in detailed morphology and become the orogenic “mighty pillar” of mould-making.The Meso-Cenozoic orogeny of China and adjacent regions can be divided into three kinds:orogeny of continental spreading basin,orogeny of oceanic spreading basin and composite orogeny of oceanic-continental basin.

  16. Aeromagnetic search for Cenozoic magmatism over the Admiralty Mountains Block (East Antarctica)

    Science.gov (United States)

    Armadillo; E.; Ferraccioli, F.; Zunino, A.; Bozzo, E.; Rocchi, S.; Armienti, P.

    2007-01-01

    Cenozoic magmatic rocks of the Transantarctic Mountains provide an important window on the tectonic and magmatic processes of the West Antarctic Rift System. Previous aeromagnetic investigations in northern Victoria Land have delineated Cenozoic volcanic and intrusive complexes assigned to the McMurdo Volcanic Group and Meander Intrusives over the Transantarctic Mountains. We present a new aeromagnetic anomaly map for the region north of the Mariner Glacier to study the extent and spatial distribution of these Cenozoic rocks over the previously unexplored Admiralty Mountains. The new map shows that the Meander Intrusives are restricted to the coastal region between the Malta Plateau and the Daniell Peninsula. However, the McMurdo Volcanic Group rocks extend further inland, and may delineate a hitherto unrecognised volcano-tectonic rift zone, extending as far north as the Trafalgar Glacier.

  17. Ocean Color

    Data.gov (United States)

    National Aeronautics and Space Administration — Satellite-derived Ocean Color Data sets from historical and currently operational NASA and International Satellite missions including the NASA Coastal Zone Color...

  18. Gel-silica science

    International Nuclear Information System (INIS)

    Sol-gel techniques can be used to produce two new types of optical silicas, termed Type V for the full density material and Type VI for the optically transparent porous material. This paper summarizes the processing differences between these six types of commercial silicas. The primary emphasis of this paper is to discuss the scientific basis for the processing of Types V and VI optical silica. First, however, the use of sol-gel processing of other systems will be briefly reviewed. The controlled hydrolysis of alkoxides has also been used to produce submicrometer TiO2, doped TiO2 (17), ZrO2 (18), doped ZrO2 (18), doped SiO2 (19), SrTiO3 (20), and corderite (20) powders. Emulsions have been employed to produce spherical powders of mixed cation oxides, such as yttrium aluminum garnets (YAG) and many other systems (20). Sol-gel powder processes have also been applied to fissile elements (21) where spray form sols UO2, and rigid gel spheres of UO-PuO2 are formed during passage through a column of heated liquid. Both crystalline and vitreous ceramic fibers have been prepared using the sol-gel method. Compositions include TiO2-SiO2 and ZrO2-SiO2 glass fibers (22), high purity SiO2 waveguide fibers (23), Al2O3, ZrO2, ThO2, MgO, TiO2, ZrSiO4, 3AlO3-2SiO2 fibers (24). Sol-gel derived alumina grains are important commercial products (25)

  19. Stabilization of large drainage basins over geological time scales: Cenozoic West Africa, hot spot swell growth, and the Niger River

    Science.gov (United States)

    Chardon, Dominique; Grimaud, Jean-Louis; Rouby, Delphine; Beauvais, Anicet; Christophoul, Frédéric

    2016-03-01

    Reconstructing the evolving geometry of large river catchments over geological time scales is crucial to constraining yields to sedimentary basins. In the case of Africa, it should further help deciphering the response of large cratonic sediment routing systems to Cenozoic growth of the basin-and-swell topography of the continent. Mapping of dated and regionally correlated lateritic paleolandscape remnants complemented by onshore sedimentological archives allows the reconstruction of two physiographic configurations of West Africa in the Paleogene. Those reconstructions show that the geometry of the drainage is stabilized by the late early Oligocene (29 Ma) and probably by the end of the Eocene (34 Ma), allowing to effectively link the inland morphoclimatic record to offshore sedimentation since that time, particularly in the case of the Niger catchment—delta system. Mid-Eocene paleogeography reveals the antiquity of the Senegambia catchment back to at least 45 Ma and suggests that a marginal upwarp forming a continental divide preexisted early Oligocene connection of the Niger and Volta catchments to the Equatorial Atlantic Ocean. Such a drainage rearrangement was primarily enhanced by the topographic growth of the Hoggar hot spot swell and caused a stratigraphic turnover along the Equatorial margin of West Africa.

  20. The Cenozoic geological evolution of the Central and Northern North Sea based on seismic sequence stratigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Jordt, Henrik

    1996-03-01

    This thesis represents scientific results from seismic sequence stratigraphic investigations. These investigations and results are integrated into an ongoing mineralogical study of the Cenozoic deposits. the main results from this mineralogical study are presented and discussed. The seismic investigations have provided boundary conditions for a forward modelling study of the Cenozoic depositional history. Results from the forward modelling are presented as they emphasise the influence of tectonics on sequence development. The tectonic motions described were important for the formation of the large oil and gas fields in the North Sea.

  1. The origin of Cenozoic basalts from central Inner Mongolia, East China: The consequence of recent mantle metasomatism genetically associated with seismically observed paleo-Pacific slab in the mantle transition zone

    Science.gov (United States)

    Guo, Pengyuan; Niu, Yaoling; Sun, Pu; Ye, Lei; Liu, Jinju; Zhang, Yu; Feng, Yue-xing; Zhao, Jian-xin

    2016-01-01

    We present new major element, trace element and Sr-Nd-Hf isotope data on Cenozoic basalts from central Inner Mongolia (CIM) in eastern China to study the origin of the incompatible-element enriched component in these basalts by testing whether or not the paleo-Pacific plate lying in the mantle transition zone beneath eastern China is the immediate cause. The Cenozoic CIM basalts have a large variation in major element, trace element and isotope compositions. Fractional crystallization of olivine and clinopyroxene can readily explain much of the major element compositional variation, while trace element and isotope ratio variation largely reflect source heterogeneities and source histories. The variably low 87Sr/86Sr, high εNd, high εHf and elevated ratios of high field strength element over large ion lithophile element (HFSE/LILE, e.g., Nb/U, Nb/La) indicate that the CIM basalts are of asthenospheric origin, which is characterized by mixing between DMM and EM1. However, the CIM basalts are enriched in incompatible elements and enriched in the progressively more incompatible elements (e.g., variably high [La/Sm]N = 1.66-3.38), suggesting that the magma source(s) must have been enriched prior to the major episode of the magmatism. Participation of subducted ocean crust in the mantle source region of these basalts is recognized, but cannot be the major source material because the subducted ocean crust is expectedly too depleted in incompatible elements (e.g., [La/Sm]N ≪ 1) to produce magmas highly enriched in incompatible elements with [La/Sm]N ≫ 1. With the new data, we consider that low mass fraction (low-F) melt metasomatism in the seismic low velocity zone (LVZ) beneath eastern China as the most likely process to generate incompatible-element enriched source(s) for mantle melts parental to the Cenozoic CIM basalts. The low-F metasomatic agent most likely resulted from dehydration melting of the transition-zone paleo-Pacific slab, which has been taking place

  2. Present-day climatic equivalents of European Cenozoic climates

    Science.gov (United States)

    Utescher, Torsten; Mosbrugger, Volker; Ivanov, Dimiter; Dilcher, David L.

    2009-07-01

    Recently, continental climate evolution in Central Europe over the last 45 Ma has been reconstructed from the palaeobotanical record using a Nearest Living Relative methodology (Coexistence Approach; CA). The reconstructed climate curves document in detail the transition from almost tropical conditions in the Mid-Eocene to a temperate climate at the Pliocene/Pleistocene transition. The observed climatic shifts are primarily expressed as non-proportional changes of the different variables taken into account. In the present study a published palaeoclimate data set for a total of 42 macrofloras complemented by new calculations is used as base to analyse the climatic space in which a fossil flora existed. To define these spaces CA intervals calculated for 3 temperature (mean annual temperature, cold and warm month mean) and 3 precipitation variables (mean annual precipitation, mean monthly precipitation of the driest and of the wettest month) are combined. Using a global gridded climatology (10' resolution), this climate space is then utilized to identify Recent climate analogues with respect to the variables regarded. For 18 macrofloras climatic analogue regions with respect to 6 variables are identified on the globe. For 16 macrofloras, analogues exist when three temperature parameters and mean annual precipitation are regarded. No Recent equivalents are found in 8 cases. This corroborates the assumption of the temporary existence of non-analogue climates in the Cenozoic. As shown by multivariate statistics the observed anomalies with respect to present-day conditions basically refer to high winter temperatures. Deploying a GIS, the Recent climate analogues can be presented as sets of grid cells for each flora that can be mapped on a globe. Once identified, these regions can be merged with adequate thematic layers to assess additional proxy data for the palaeofloras. To exemplify the procedure Koeppen climate type, numbers of days with ground frost, as well as

  3. Late Cenozoic stress field distribution in Biga Peninsula, NW Turkey

    Science.gov (United States)

    Ozden, S.; Bekler, T.; Tutkun, S. Z.; Kurcer, A.; Ates, O.; Bekler, F. N.; Kalafat, D.

    2009-04-01

    Biga Peninsula is a seismically active region both in instrumental and historical period in NW Turkey. In this part, middle and southern branches of North Anatolian Fault are represented by Etili, Can-Biga, Yenice-Gonen, Manyas-Danisment, Lapseki, Sinekci, Terzialan, Dogruca, Uluabat, Edincik, Pazarkoy-Hamdibey-Kalkim, Edremit, Yigitler, Sarikoy-Inova, Troia and Karabiga Faults. All of these faults are responsible of the seismic activity in Biga Peninsula. Historical earthquakes happened in 29, 155, 170, 543, 620, 1440, 1737, 1855, 1865 and 1875. Furthermore, as for instrumental period, Saros Gulf-Murefte earthquakes (M:7.3 and M:6.3) in 1912, Erdek Gulf (M:6.4) and Can-Biga (M:6.3) in 1935, Edremit Gulf-Ayvaci k (M:6.8) in 1944, Yenice-Gonen (M:7.2) in 1953, Gonen (M:5.8) in 1964, Edremit-Baki rcay (M:5.5) in 1971, Biga (M:5.8) in 1983, Kusgolu-Manyas (M:5.2) and Bandirma (M:5.0) in 2006. In this study, we determined the Late Cenozoic stress field distribution and present-day tectonic regimes both fault-slip data (by 253 fault planes) and earthquake focal mechanism solutions (by 58 earthquakes) were investigated by the inversion methods. The results indicate that a transtensional stress regime is dominant with a NW-SE to WNW-ESE directed compression (1) and NE-SW to ENE-WSW directed extension (3), which yielded a NE-SW, ENE-WSW and also E-W trending strike-slip faulting faults with a normal component. While a transtensional tectonic regime has an active component in Biga Peninsula, a local and consistent transpressional tectonic regime were determined along an E-W trending narrow zone in the northern part of the Biga Peninsula also. The tectonic regime and stress field is resulted from interactions both continental collision of Eurasian/Anatolian/Arabian plate in the east and subduction processes (roll back and/or slab-pull) of the African plate along the Cyprus and Hellenic arc in the Mediterranean region.

  4. Shallow gas in Cenozoic sediments of the Southern North Sea

    Science.gov (United States)

    Trampe, Anna F.; Lutz, Rüdiger; Franke, Dieter; Thöle, Hauke; Arfai, Jashar

    2013-04-01

    Shallow petroleum systems in the southern North Sea are known for several decades but they were not actively explored for a long time. In recent years these unconventional shallow petroleum systems are studied in greater detail and one shallow gas field (A-12) is in production in the Netherlands. Additionally, oil was encountered in Miocene sandstones in the southern Danish North Sea (Lille John well) just north of the Danish-German border. Seismic amplitude anomalies are an indication for hydrocarbons in sediments. Therefore we have mapped the occurrence of seismic amplitude anomalies in the German North Sea based on more than 25.000 km of 2D seismic data and around 4.000 km2 of 3D seismic data. Amplitude anomalies are ubiquitous phenomena in the study area. These anomalies are not only caused by hydrocarbons but also by changing lithologies e.g. peat or fluid migration. Therefore several classes of seismic anomalies, e.g. bright spots, chimneys, blanking areas and velocity pull-down were mapped. Examples for these classes were studied with AVO (amplitude variation with offset) analyses to verify the existence or non-existence of gas in the sediments. Shallow gas can be produced and transported through the dense pipeline grid of the southern and central North Sea or it could be burned offshore close to wind parks in small power plants and the electric energy then transported through the existing power connections of the wind parks. Thus enabling a continuous energy supply during calm wind periods. This study is carried out within the framework of the project "Geoscientific Potential of the German North Sea (GPDN)" in which the Cenozoic sedimentary system was mapped in great detail. A detailed model of delta evolution (Baltic river system) was developed which serves as a structural framework. The studied interval is time equivalent to the Utsira formation which is used offshore Norway for sequestration of CO2. These different possibilities of using or exploiting

  5. Paleoenvironmental reconstruction of the late Cenozoic Qaidam Basin, China

    Science.gov (United States)

    Zhang, C.; Wang, Y.; Li, Q.; Wang, X.; Deng, T.; Tseng, Z. J.; Takeuchi, G.; Xie, G.; Xu, Y.

    2011-12-01

    Reconstruction of paleoenvironments in the Tibetan region is important to understanding the linkage between tectonic force and climate change. Here we report new isotope data from the Qaidam Basin, China, which is located on the northeastern Tibetan Plateau, including stable C and O isotope analyses of a wide variety of late Cenozoic mammalian tooth enamel samples (including deer, giraffe, horse, rhino, and elephant), and O isotope compositions of phosphate (δ18Op) in fish bone samples. Mammalian tooth enamel δ13C values, when combined with fossil assemblage and other geological evidence, indicate that the Qaidam Basin was warmer and more humid during the late Miocene and early Pliocene, and that there was lush C3 vegetation with significant C4 components at that time, although the C4 plants were not consistently utilized. In contrast, the modern Qaidam Basin is dominated by C3 plants. Fish bone δ18Op values showed statistically significant enrichment from the Tuxi-Shengou-Naoge interval (late Miocene) to the Yahu interval (early Pliocene) and from the Yahu interval to the present day. This most likely reflects increases in the δ18O of lake water over time, as a result of increased aridification of the Qaidam Basin. Assuming that mammals drank exclusively from the lake, temperatures were calculated from average δ18Op values and average δ18Ow derived from large mammal tooth enamel δ18O. Temperatures were also estimated from δ18Op and δ18Ow estimated from co-ocurring large mammal tooth enamel δ18O. The temperature estimates were all lower than the average temperature of the modern Qinghai Lake surface water during the summer, and mostly too low to be reasonable, indicating that the fish and the large mammals were not in equilibrium with the same water. Assuming the relationship between salinity and δ18Ow observed for the modern Qinghai Lake and its surrounding lakes and ponds applied in the past, we calculated the paleosalinities of lake waters to be ~0 to

  6. Cenozoic extensional tectonics of the Western Anatolia Extended Terrane, Turkey

    International Nuclear Information System (INIS)

    The Western Anatolia Extended Terrane in Turkey is located on the eastern side of the Aegean Extended Terrane and contains one of the largest metamorphic core complexes in the world, the Menderes massif. It has experienced a series of continental collisions from the Late Cretaceous to the Eocene during the formation of the Izmir-Ankara-Erzincan suture zone. Based our field work and monazite ages, we suggest that the north-directed postcollisional Cenozoic extension in the region is the product of three consecutive stages, triggered by three different mechanisms. The first stage was initiated about 30 Ma ago, in the Oligocene by the Orogenic Collapse the thermally weakened continental crust along the north-dipping Southwest Anatolian shear zone. The shear zone was formed as an extensional simple-shear zone with listric geometry at depth and exhibits predominantly normal-slip along its southwestern end. But, it becomes a high-angle oblique-slip shear zone along its northeastern termination. Evidence for the presence of the shear zone includes (1) the dominant top to the north-northeast shear sense indicators throughout the Menderes massif, such as stretching lineations trending N10E to N30E; and (2) a series of Oligocene extensional basins located adjacent to the shear zone that contain only carbonate and ophiolitic rock fragments, but no high grade metamorphic rock fragments. During this stage, erosion and extensional unroofing brought high-grade metamorphic rocks of the Central Menderes massif to the surface by the early Miocene. The second stage of the extension was triggered by subduction roll-back and associated back-arc extension in the early Miocene and produced the north-dipping Alasehir and the south-dipping Bueyuek Menderes detachments of the central Menderes massif and the north-dipping Simav detachment of the northern Menderes massif. The detachments control the Miocene sedimentation in the Alasehir, Bueyuek Menderes, and Simav grabens, containing high

  7. Electrochemically Formed Porous Silica

    Directory of Open Access Journals (Sweden)

    Jean-Noël Chazalviel

    2011-04-01

    Full Text Available Controlled electrochemical formation of porous silica can be realized in dilute aqueous, neutral-pH, fluoride medium. Formation of a porous film is initiated by sweeping the potential applied to silicon to values higher than 20 V. Film formation, reaching a steady state, may be pursued in a wide range of potentials, including lower potentials. The origin of a threshold potential for porous film initiation has been explained quantitatively. All of the films appear mesoporous. Films grown at high potentials exhibit a variety of macrostructures superimposed on the mesoporosity. These macrostructures result from selective dissolution of silica induced by local pH lowering due to oxygen evolution. Films grown at potentials lower than 15 V appear uniform on the micrometer scale. However, all of the films also exhibit a stratified structure on the scale of a few tens of nanometres. This periodic structure can be traced back to the oscillatory behavior observed during the electrochemical dissolution of silicon in fluoride medium. It suggests that periodic breaking of the growing film may be responsible for this morphology.

  8. Silica aerogel Cherenkov counter

    International Nuclear Information System (INIS)

    A practical method for making silica aerogel Cherenkov counters has been developed at KEK, and some tests were performed to evaluate the performance of the counters. The method for making silica aerogel with refractive index between 1.01 and 1.06 is explained in detail. Chemical reaction with methanol, pressure and temperature conditions, and the structure of the autoclave are described together with the whole process. About 20 l aerogel is now produced per week at KEK. The dimensions of the aerogel module is 200 x 100 x 300 mm3. The aerogel with refractive index larger than 1.06 is produced from the aerogel with refractive index 1.06 by heating it up to about 900 deg C. The refractive index can be controlled by the temperature and duration of heating. Refractive index in relation to these conditions is listed in a table. However, the dispersion of the index is about ten times as large as that for the aerogel with lower index (<1.06). The wave length dependence of the transmission length of light for the aerogel was measured and compared with other data obtained at various laboratories. The performance of the counter was evaluated through the experiment with π beam. Average number of photoelectrons gathered is plotted in relation to momentum. It is deduced from the experiment that the saturation thickness of the aerogel is about 10 cm. Two examples of the practical use of the aerogel counter at KEK are also shortly described. (Aoki, K.)

  9. The terrestrial silica pump.

    Science.gov (United States)

    Carey, Joanna C; Fulweiler, Robinson W

    2012-01-01

    Silicon (Si) cycling controls atmospheric CO(2) concentrations and thus, the global climate, through three well-recognized means: chemical weathering of mineral silicates, occlusion of carbon (C) to soil phytoliths, and the oceanic biological Si pump. In the latter, oceanic diatoms directly sequester 25.8 Gton C yr(-1), accounting for 43% of the total oceanic net primary production (NPP). However, another important link between C and Si cycling remains largely ignored, specifically the role of Si in terrestrial NPP. Here we show that 55% of terrestrial NPP (33 Gton C yr(-1)) is due to active Si-accumulating vegetation, on par with the amount of C sequestered annually via marine diatoms. Our results suggest that similar to oceanic diatoms, the biological Si cycle of land plants also controls atmospheric CO(2) levels. In addition, we provide the first estimates of Si fixed in terrestrial vegetation by major global biome type, highlighting the ecosystems of most dynamic Si fixation. Projected global land use change will convert forests to agricultural lands, increasing the fixation of Si by land plants, and the magnitude of the terrestrial Si pump. PMID:23300825

  10. The terrestrial silica pump.

    Directory of Open Access Journals (Sweden)

    Joanna C Carey

    Full Text Available Silicon (Si cycling controls atmospheric CO(2 concentrations and thus, the global climate, through three well-recognized means: chemical weathering of mineral silicates, occlusion of carbon (C to soil phytoliths, and the oceanic biological Si pump. In the latter, oceanic diatoms directly sequester 25.8 Gton C yr(-1, accounting for 43% of the total oceanic net primary production (NPP. However, another important link between C and Si cycling remains largely ignored, specifically the role of Si in terrestrial NPP. Here we show that 55% of terrestrial NPP (33 Gton C yr(-1 is due to active Si-accumulating vegetation, on par with the amount of C sequestered annually via marine diatoms. Our results suggest that similar to oceanic diatoms, the biological Si cycle of land plants also controls atmospheric CO(2 levels. In addition, we provide the first estimates of Si fixed in terrestrial vegetation by major global biome type, highlighting the ecosystems of most dynamic Si fixation. Projected global land use change will convert forests to agricultural lands, increasing the fixation of Si by land plants, and the magnitude of the terrestrial Si pump.

  11. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    Directory of Open Access Journals (Sweden)

    Carolin C. Lechner

    2015-08-01

    Full Text Available Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typically occur as complex posttranslationally modified variants and are directly involved in the silica deposition process in diatoms. However, even in vitro silaffin-based peptides alone, with and without posttranslational modifications, can efficiently mediate biomimetic silica precipitation leading to silica material with different properties as well as with encapsulated cargo molecules of a large size range. In this review, the biomineralization process of silica in diatoms is summarized with a specific focus on silaffins and their in vitro silica precipitation properties. Applications in the area of bio- and nanotechnology as well as in diagnostics and therapy are discussed.

  12. Heterogeneous lithospheric mantle metasomatism in the eastern North China Craton: He-Ar isotopes in peridotite xenoliths from Cenozoic basalts

    Science.gov (United States)

    Tang, Huayun; Matsumoto, Takuya; Zheng, Jianping; Czuppon, György; Yu, Chunmei; Miyakawa, Chie; Ping, Xianquan

    2014-02-01

    The abundances and isotopic compositions of Helium and Argon have been analyzed in a suite of fresh spinel peridotite xenoliths in Cenozoic basalts from the eastern North China Craton (NCC) by step-wise heating experiments, to investigate the nature of noble gas reservoirs in the subcontinental lithospheric mantle beneath this region. The xenoliths include one harzburgite collected from Hebi in the interior of the NCC, two lherzolites from Hannuoba at the northern margin of the craton, and three lherzolites from Shanwang and Nushan on the eastern margin. 3He/4He ratios in most of the xenoliths are similar to those of mid-ocean ridge basalts (MORB) or slightly lower (2-10.5 Ra, where Ra is the 3He/4He ratio of the atmosphere), suggesting mixing of MORB-like and radiogenic components. One olivine separate from Nushan has a helium value of 25.3 Ra, probably suggesting cosmogenic 3He addition. The 40Ar/36Ar ratios vary from atmospheric value (296) to 1625, significantly lower than the MORB value. Available data of the peridotite xenoliths indicate the He and Ar isotopic systematics of the mantle reservoirs beneath the NCC can be interpreted as mixtures of at least three end-members including MORB-like, radiogenic and atmospheric components. We suggest that the MORB-like noble gases were derived from the underlying asthenosphere during mantle upwelling, whereas the radiogenic and recycled components probably were incorporated into the lithospheric mantle during circum-craton subduction of oceanic crust. Available data suggest that the MORB-like fluids are better preserved in the interior of the NCC, whereas the radiogenic ones are more prevalent at the margins. The Paleo-Asian ocean subduction system probably was responsible for the enriched and recycled noble gas signatures on the northern margin of the craton, while the Pacific subduction system could account for the observed He-Ar isotopic signatures beneath the eastern part. Therefore, integration of helium and

  13. Oceans Past

    DEFF Research Database (Denmark)

    Based on research for the History of Marine Animal Populations project, Oceans Past examines the complex relationship our forebears had with the sea and the animals that inhabit it. It presents eleven studies ranging from fisheries and invasive species to offshore technology and the study of marine...... environmental history, bringing together the perspectives of historians and marine scientists to enhance understanding of ocean management of the past, present and future. In doing so, it also highlights the influence that changes in marine ecosystems have upon the politics, welfare and culture of human...

  14. Cenozoic alkaline volcanic rocks with carbonatite affinity in the Bohemian Massif: Their sources and magma generation

    Czech Academy of Sciences Publication Activity Database

    Ulrych, Jaromír; Štěpánková-Svobodová, Jana

    2014-01-01

    Roč. 46, 1/2 (2014), s. 45-58. ISSN 0369-2086 R&D Projects: GA AV ČR(CZ) IAA300130902 Institutional support: RVO:67985831 Keywords : alkaline volcanic rocks * melilitic rocks * carbonatite s * magma generation * metasomatism * Cenozoic * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy

  15. Late Cenozoic History of the Genus Micromys (Mammalia, Rodentia) in Central Europe

    Czech Academy of Sciences Publication Activity Database

    Horáček, I.; Knitlová, M.; Wagner, Jan; Kordos, L.; Nadachowski, A.

    2013-01-01

    Roč. 8, č. 5 (2013), e62498. E-ISSN 1932-6203 R&D Projects: GA ČR GA205/09/0184 Institutional support: RVO:67985831 Keywords : Mammalia * Rodentia * Genus Micromys * Late Cenozoic Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.534, year: 2013

  16. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia

    NARCIS (Netherlands)

    Hinsbergen, D.J.J. van; Lippert, P.C.; Dupont-Nivet, G.; McQuarrie, N.; Doubrovine, P.V.; Spakman, W.; Torsvik, T.H.

    2012-01-01

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India–Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. S

  17. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia

    NARCIS (Netherlands)

    van Hinsbergen, D.J.J.; Lippert, P.; Dupont-Nivet, G.; McQuarrie, N.; Doubrovine, P.V.; Spakman, W.; Torsvik, T.H.

    2013-01-01

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India–Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. S

  18. From mantle roots to surface eruptions: Cenozoic and Mesozoic continental basaltic magmatism

    Czech Academy of Sciences Publication Activity Database

    Kämpf, H.; Németh, K.; Puziewicz, J.; Mrlina, Jan; Geissler, W.H.

    2015-01-01

    Roč. 104, č. 8 (2015), s. 1909-1912. ISSN 1437-3254 Institutional support: RVO:67985530 Keywords : continental basaltic volcanism * BASALT 2013 conference * Cenozoic * Mesozoic Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 2.093, year: 2014

  19. The Amazonian Craton and its influence on past fluvial systems (Mesozoic-Cenozoic, Amazonia)

    NARCIS (Netherlands)

    C. Hoorn; M. Roddaz; R. Dino; E. Soares; C. Uba; D. Ochoa-Lozano; R. Mapes

    2010-01-01

    The Amazonian Craton is an old geological feature of Archaean/Proterozoic age that has determined the character of fluvial systems in Amazonia throughout most of its past. This situation radically changed during the Cenozoic, when uplift of the Andes reshaped the relief and drainage patterns of nort

  20. Biogenic nanostructured silica

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Silicon is by far the most abundant element in the earth crust and also is an essential element for higher plants, yet its biology and mechanisms in plant tolerance of biotic and abiotic stresses are poorly understood. Based on the molecular mechanisms of the biosilicification in marine organisms such as diatoms and sponges, the cell wall template-mediated self-assembly of nanostructured silica in marine organisms and higher plants as well as the related organic molecules are discussed. Understanding of the templating and structure-directed effects of silicon-processing organic molecules not only offers the clue for synthesizing silicon-based materials, but also helps to recognize the anomaly of silicon in plant biology.

  1. Silica aerogel core waveguide.

    Science.gov (United States)

    Grogan, M D W; Leon-Saval, S G; England, R; Birks, T A

    2010-10-11

    We have selectively filled the core of hollow photonic crystal fibre with silica aerogel. Light is guided in the aerogel core, with a measured attenuation of 0.2 dB/cm at 1540 nm comparable to that of bulk aerogel. The structure guides light by different mechanisms depending on the wavelength. At long wavelengths the effective index of the microstructured cladding is below the aerogel index of 1.045 and guidance is by total internal reflection. At short wavelengths, where the effective cladding index exceeds 1.045, a photonic bandgap can guide the light instead. There is a small region of crossover, where both index- and bandgap-guided modes were simultaneously observed. PMID:20941148

  2. Reconstructions of subducted ocean floor along the Andes: a framework for assessing Magmatic and Ore Deposit History

    Science.gov (United States)

    Sdrolias, M.; Müller, R.

    2006-05-01

    The South American-Antarctic margin has been characterised by numerous episodes of volcanic arc activity and ore deposit formation throughout much of the Mesozoic and Cenozoic. Although its Cenozoic subduction history is relatively well known, placing the Mesozoic arc-related volcanics and the emplacement of ore bodies in their plate tectonic context remains poorly constrained. We use a merged moving hotspot (Late Cretaceous- present) and palaeomagnetic /fixed hotspot (Early Cretaceous) reference frame, coupled with reconstructed spreading histories of the Pacific, Phoenix and Farallon plates to understand the convergence history of the South American and Antarctic margins. We compute the age-area distribution of oceanic lithosphere through time, including subducting oceanic lithosphere and estimate convergence rates along the margin. Additionally, we map the location and migration of spreading ridges along the margin and relate this to processes on the overriding plate. The South American-Antarctic margin in the late Jurassic-early Cretaceous was dominated by rapid convergence, the subduction of relatively young oceanic lithosphere (Rocas Verdes" in southern South America. The speed of subduction increased again along the South American-Antarctic margin at ~105 Ma after another change in tectonic regime. Newly created crust from the Farallon-Phoenix ridge continued to be subducted along southern South America until the cessation of the Farallon-Phoenix ridge in the latest Cretaceous / beginning of the Cenozoic. The age of the subducting oceanic lithosphere along the South American-Antarctic margin has increased steadily through time.

  3. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRINKING WATER OF ANIMALS Listing of Specific Substances Affirmed as GRAS § 584.700 Hydrophobic silicas. (a) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No....

  4. Late Cenozoic sedimentation in Pilot Knob Valley, California

    Science.gov (United States)

    Rittase, W. M.; Walker, J. D.; Kirby, E.; Andrew, J.; Wan, E.

    2012-12-01

    In Pilot Knob Valley (PKV), active inversion of a Pliocene-mid Pleistocene basin presents the opportunity to understand the spatial and temporal development of an enigmatic basin astride a major transform boundary in California. Here, a ~1000-m-thick package of exposed Late Cenozoic strata has been uplifted and tilted to the northeast. Based on new age and provenance data, we adopt the name Pilot Knob formation (PKfm) to describe much of these exposed rocks north of the Garlock fault (GF) and east of Christmas Canyon gate. Post-Miocene development of PKV is strongly influenced by the sinistral GF, the newly identified Marine Gate fault (MGF) and dextral Eastern California shear zone. The PKfm consists of three lithofacies members, from base to top: (1) rocks derived from Eagle Crags to the south; (2) Randsburg Wash lacustrine rocks; and (3) an upper member derived from the Slate Range. Tephrochronologic data from four PKfm ash samples brackets deposition of lacustrine Randsburg Wash Member rocks between 3.7-3.1 Ma and lacustrine rocks of the Slate Range Member between 1.2-0.6 Ma. A fifth tephrochronologic sample from lacustrine-distal alluvial sediments south of the GF near Christmas Canyon brackets deposition of a possible PKfm facies at ~3.1 Ma. A 3-stage tectonic model for northern PKV explains changing provenance patterns. Prior to ~3.1 Ma, the western PKV paleo-low lay north of the current GF adjacent to the southern Slate Range and connected to Searles Valley. The MGF cuts adjacent to the southern face of the Slate Range and southern Searles Valley with up to 7.5 km of sinistral oblique-normal slip between ~5-2.5 Ma. Eagle Crags fanglomerate deposition may continue after 3.7 Ma west of the Randsburg Wash-Searles Valley spillway, but these rocks have been eroded away. By ~3.7 Ma, northward progradation of Eagle Crags fanglomerate waned and lacustrine sediments were deposited north of the GF and east of the Randsburg Wash-Searles Valley spillway. At ~3.1 Ma

  5. Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

    Science.gov (United States)

    Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

    2010-01-01

    Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the

  6. Vertical-axis rotations determined from paleomagnetism of Mesozoic and Cenozoic strata of the Bolivian Andes

    Science.gov (United States)

    Richards, David R.; Butler, Robert F.; Sempere, Thierry

    2004-07-01

    Thermal demagnetization and principal component analysis allowed determination of characteristic remanent magnetization (ChRM) directions from 256 sites at 22 localities in Mesozoic and Cenozoic sedimentary strata of the Bolivian Altiplano and Eastern Cordillera. An inclination-only fold test of site-mean ChRM directions from Cenozoic units (principally the Santa Lucía Formation) indicates optimum unfolding at 97.1% unfolding, consistent with a primary origin for the ChRM. For Mesozoic strata, optimum unfolding occurred at 89.2%, perhaps indicating secondary remagnetization at some locations. For Cenozoic units, comparison of locality-mean directions with expected paleomagnetic directions indicates vertical-axis rotations from 33° counterclockwise to 24° clockwise. Euler pole analysis of along-strike variation in crustal shortening within the Subandean and Interandean zones indicates 18° clockwise rotation south of the axis of curvature of the Bolivian Andes and 6° counterclockwise rotation northwest of the axis during the past 10 m.y. Along-strike variation of shortening within the Eastern Cordillera indicates 8° clockwise rotation south of the axis and 8° counterclockwise rotation northwest of the axis from 35 to 10 Ma. These vertical-axis rotations produced by along-strike variations in crustal shortening during development of the Bolivian fold-thrust belt agree well with observed rotations determined from paleomagnetism of Cenozoic rocks in the Eastern Cordillera and in the Subandean and Interandean zones. However, local rotations are required to account for complex rotations in the Cochabamba Basin and within the Altiplano. The curvature of the Bolivian Andes has been progressively enhanced during Cenozoic fold-thrust belt deformation.

  7. A Cenozoic record of the equatorial Pacific carbonate compensation depth

    Digital Repository Service at National Institute of Oceanography (India)

    Palike, H.; Lyle, M.W.; Nishi, H.; Raffi, I.; Ridgwell, A.; Gamage, K.; Klaus, A.; Acton, G.; Anderson, L.; Backman, J.; Baldauf, J.; Beltran, C.; Bohaty, S.M.; Bown, P.; Busch, W.; Channell, J.E.T.; Chun, C.O.J.; Delaney, M.; Dewangan, P.; et al.

    14 3ZH, UK 2 Department of Oceanography, Texas A&M University, College Station TX 77840-3146, USA. 3 The Center for Academic Resources and Archives, Tohoku University Museum, Tohoku University, Aramaki Aza Aoba 6-3, Aoba-ku, Sendai, 980-8578, Japan..., Bristol BS8 1SS, UK. 6 Integrated Ocean Drilling Program, Texas A&M University, 1000 Discovery Drive, College Station TX 77845-9547, USA. 7 Department of Geology, University of California, Davis, One Shields Avenue, Davis CA 95616, USA. 8 Department...

  8. Silaffins in Silica Biomineralization and Biomimetic Silica Precipitation

    OpenAIRE

    Lechner, Carolin C.; Becker, Christian F. W.

    2015-01-01

    Biomineralization processes leading to complex solid structures of inorganic material in biological systems are constantly gaining attention in biotechnology and biomedical research. An outstanding example for biomineral morphogenesis is the formation of highly elaborate, nano-patterned silica shells by diatoms. Among the organic macromolecules that have been closely linked to the tightly controlled precipitation of silica in diatoms, silaffins play an extraordinary role. These peptides typic...

  9. The silica cycle in a Northeast Pacific fjord; the role of biological resuspension

    Science.gov (United States)

    Katz, Timor; Yahel, Gitai; Tunnicliffe, Verena; Herut, Barak; Whitney, Frank; Snelgrove, Paul V. R.; Lazar, Boaz

    2016-09-01

    This study is a quantitative assessment of the role fish-induced bio-resuspension plays in the silica cycle of coastal waters. We used new, published and archived oceanographic data to construct a comprehensive silica budget for Saanich Inlet (Vancouver Island, Canada), a highly productive Northeast Pacific fjord, where siliceous diatoms dominate primary productivity. Anoxia in the deep water of the inlet persists during most of the year, precluding animal life, whereas abundant groundfish continuously rework and resuspend bottom sediments in the shallower, oxygenated margins. This resuspension transfers settled biogenic silica fragments from the sediment, where they are immersed in porewater that is rich with dissolved silica, to the overlying water, where the much lower concentrations accelerate their dissolution rate. The budget shows that Saanich Inlet sediments constitute a sink for approximately 250 × 106 mol Si y-1. Most of this Si enters the inlet in advected, siliceous phytoplankton. Sediment resuspension by groundfish in the oxygenated margins of Saanich Inlet generates about 50% of the total flux of dissolved silica from the inlet seafloor. This resuspension also facilitates a massive transport of biogenic silica from the margins to the anoxic basin, where approximately 90% of all the biogenic silica is buried. The excess dissolution caused by fish activity reduces the burial efficiency of biogenic silica in the entire inlet sediments by about 20%. This case study emphasizes the link between the silica cycle and groundfish activity. Based on this study and because biological resuspension occurs in most regions of the ocean, we recommend that it will be taken into account when budgeting the silica cycle, and potentially other geochemical cycles, in marine environments.

  10. Importance of particle formation to reconstructed water column biogenic silica fluxes

    NARCIS (Netherlands)

    Moriceau, B.; Gallinari, M.; Soetaert, K.E.R.; Ragueneau, O.

    2007-01-01

    The particles sinking out of the ocean's surface layer are made up of a mixture of living and dead algal cells, fecal pellets, and aggregates, while the parameters used to describe the behavior of biogenic silica (bSiO2) in today's models are experimentally determined on freely suspended diatoms (FC

  11. Ocean energies

    International Nuclear Information System (INIS)

    This timely volume provides a comprehensive review of current technology for all ocean energies. It opens with an analysis of ocean thermal energy conversion (OTEC), with and without the use of an intermediate fluid. The historical and economic background is reviewed, and the geographical areas in which this energy could be utilized are pinpointed. The production of hydrogen as a side product, and environmental consequences of OTEC plants are considered. The competitiveness of OTEC with conventional sources of energy is analysed. Optimisation, current research and development potential are also examined. Separate chapters provide a detailed examination of other ocean energy sources. The possible harnessing of solar ponds, ocean currents, and power derived from salinity differences is considered. There is a fascinating study of marine winds, and the question of using the ocean tides as a source of energy is examined, focussing on a number of tidal power plant projects, including data gathered from China, Australia, Great Britain, Korea and the USSR. Wave energy extraction has excited recent interest and activity, with a number of experimental pilot plants being built in northern Europe. This topic is discussed at length in view of its greater chance of implementation. Finally, geothermal and biomass energy are considered, and an assessment of their future is given. The authors also distinguished between energy schemes which might be valuable in less-industrialized regions of the world, but uneconomical in the developed countries. A large number of illustrations support the text. This book will be of particular interest to energy economists, engineers, geologists and oceanographers, and to environmentalists and environmental engineers

  12. Effect of volatiles erupted from Mesozoic and Cenozoic volcanic activities on paleo-environmental changes in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Based on the determination of composition of volcanic volatiles and petrologic estimation of the total mass of volatiles erupted,we showed important advances in the study of the impact of Mesozoic and Cenozoic volcanic activities on paleo-environmental changes in China.The volcanic activities include western Liaoning and Zhangjiakou Mesozoic intermediate-acidic explosive eruptions,southern Tibet and Shanwang Cenozoic volcanism,and Mt.Changbai volcanic eruption around one thousand years ago.The paper predominantly discusses the earth's surface temperature changes,ozone depletion,acidic rain formation and mass mortalities of vertebrate induced by the Mesozoic and Cenozoic volcanism in China.

  13. Silica Brick for Coke Oven

    Institute of Scientific and Technical Information of China (English)

    Wang Jing

    2007-01-01

    @@ 1 Scope This standard specifies the classification,specification,test method,quality appraisal procedure,labeling,packing,transportation,storage and quality certification of silica brick for coke oven.

  14. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.;

    2004-01-01

    scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from a...... viscoclastic rubber to a plastic fluid and from a plastic fluid to a viscoelastic liquid are shifted to more elevated temperatures when silica is added to the triblock copolymer gel. (C) 2004 Elsevier Ltd. All rights reserved.......The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order to...

  15. Functionalized silica materials for electrocatalysis

    Indian Academy of Sciences (India)

    Vellaichamy Ganesan

    2015-02-01

    Electrocatalysis is an important phenomenon which is utilized in metal–air batteries, fuel cells, electrochemical sensors, etc. To increase the efficiency of the electrocatalytic process and to increase the electrochemical accessibility of the immobilized electrocatalysts, functionalized and non-functionalized mesoporous organo-silica (MCM41-type-materials) are used in this study. These materials possess several suitable properties to be durable catalysts and/or catalyst supports. Owing to the uniform dispersion of electrocatalysts (metal complex and/or metal nanoparticles (NPs)) on the functionalized and non-functionalized silica, an enormous increase in the redox current is observed. Long range channels of silica materials with pore diameter of 15–100 Å allowed metal NPs to accommodate in a specified manner in addition to other catalysts. The usefulness of MCM-41-type silica in increasing the efficiency of electrocatalysisis demonstrated by selecting oxygen, carbon dioxide and nitrite reduction reactions as examples

  16. Magnetic silica colloids for catalysis

    OpenAIRE

    Claesson, E.M.; Mehendale, N.C.; Klein Gebbink, R. J. M.; van Koten, G; Philipse, A. P.

    2007-01-01

    Monodisperse magnetizable colloidal silica particles in a stable dispersion have been functionalized with a homogeneous catalyst: a PCP–pincer Pd-complex. In a proof-of-principle experiment we demonstrate the catalytic activity of the colloids in a C–C bond formation reaction. Advantages of the magnetic silica carriers are the large surface-to-volume ratio and the easy recovery by magnetic separation. After magnetic separation, the catalyst-loaded particles are readily redispersed for further...

  17. The Cretaceous and Cenozoic tectonic evolution of Southeast Asia

    Science.gov (United States)

    Zahirovic, S.; Seton, M.; Müller, R. D.

    2014-04-01

    Tectonic reconstructions of Southeast Asia have given rise to numerous controversies that include the accretionary history of Sundaland and the enigmatic tectonic origin of the proto-South China Sea. We assimilate a diversity of geological and geophysical observations into a new regional plate model, coupled to a global model, to address these debates. Our approach takes into account terrane suturing and accretion histories, the location of subducted slabs imaged in mantle tomography in order to constrain the evolution of regional subduction zones, as well as plausible absolute and relative plate velocities and tectonic driving mechanisms. We propose a scenario of rifting from northern Gondwana in the latest Jurassic, driven by northward slab pull from north-dipping subduction of Tethyan crust beneath Eurasia, to detach East Java, Mangkalihat, southeast Borneo and West Sulawesi blocks that collided with a Tethyan intra-oceanic subduction zone in the mid-Cretaceous and subsequently accreted to the Sunda margin (i.e., southwest Borneo core) in the Late Cretaceous. In accounting for the evolution of plate boundaries, we propose that the Philippine Sea plate originated on the periphery of Tethyan crust forming this northward conveyor. We implement a revised model for the Tethyan intra-oceanic subduction zones to reconcile convergence rates, changes in volcanism and the obduction of ophiolites. In our model the northward margin of Greater India collides with the Kohistan-Ladakh intra-oceanic arc at ∼53 Ma, followed by continent-continent collision closing the Shyok and Indus-Tsangpo suture zones between ∼42 and 34 Ma. We also account for the back-arc opening of the proto-South China Sea from ∼65 Ma, consistent with extension along east Asia and the formation of supra-subduction zone ophiolites presently found on the island of Mindoro. The related rifting likely detached the Semitau continental fragment from South China, which accreted to northern Borneo in the mid

  18. Meso-Cenozoic tectonics of the Central Kyrgyz Tien Shan (Central Asia), based on apatite fission track thermochronology.

    OpenAIRE

    Glorie, Stijn

    2008-01-01

    Apatite fission track thermochronology on the Kyrgyz Tien Shan basement revealed a polyphased thermal history of the study-area. We interpret the Mesozoic and Cenozoic cooling-events as periods of tectonic reactivation.

  19. The Ocean World Enceladus

    Science.gov (United States)

    Spilker, Linda J.; Cable, Morgan

    2016-06-01

    Does life exist elsewhere in our solar system? This key question has been a major motivator for our exploration beyond Earth. Life as we know it requires liquid water, organic chemistry and energy. As Cassini discoveries have shown, all of these key ingredients appear to exist on Saturn’s tiny moon Enceladus, making it a possible habitat for life.NASA’s Cassini spacecraft arrived at Saturn in July 2004 and began making incredible findings in the Saturn system. Some of the most striking discoveries involved Enceladus. Only 300 miles in diameter, a huge plume of water ice and water vapor is erupting from a liquid water reservoir under Enceladus’ south pole. Jets and curtains of icy material shoot skyward from a series of four linear fractures nicknamed “tiger stripes”. Over the course of the next decade, Cassini repeatedly flew close to Enceladus and directly sampled its icy plume seven times. Cassini’s sensitive instruments discovered complex organic molecules, salts and silicates in the plume indicating that the water is in contact with a rocky core. We now know that the liquid reservoir underneath Enceladus’ icy crust is not a regional sea but a global, subsurface ocean. The ocean is salty, much like our own seas. Excess heat originates from the narrow tiger stripes and tiny silica nanograins in the plume provide evidence for hydrothermal activity on Enceladus’ seafloor. Similar hydrothermal systems on Earth support rich communities of life that contain organisms as large as tubeworms and crabs.With each discovery, Enceladus becomes an increasingly enticing astrobiology target. Could life exist in Enceladus’ ocean? A future mission may answer this question. Cassini was never meant to be a sea-faring mission, and while its instruments have helped answer important questions about the habitability of Enceladus, the question of whether life exists will require a more specialized set of instruments and a targeted mission. Enceladus’ lofting of free

  20. Geochemistry of ultramafic xenoliths in Cenozoic alkali basalts from Jiangsu province, eastern China and their geological implication

    Indian Academy of Sciences (India)

    Shao-Wei Huang; Yung-Tan Lee; Ju-Chin Chen; Kung-Suan Ho; Meng-Lung Lin; Yen-Tsui Hu; Ren-Yi Huang

    2013-06-01

    Twelve ultramafic xenoliths in Cenozoic alkali basalts from Jiangsu province, eastern China have been analyzed for major, trace, Sr–Nd isotopic composition and mineral chemical compositions and the origin of these ultramafic xenoliths is discussed based on the geochemical constraints. Based on classification norms, the ultramafic xenoliths in the present study belong to type I xenolith. The Fo-values of the ultramafic xenoliths range from 90.18 to 92.18. The ultramafic xenoliths have higher MgO content, but lower Al2O3, TiO2, CaO and Na2O contents than those of primitive mantle, indicating that they represent residues formed by different degrees of partial melting from the upper mantle. The enrichment of Rb, Ba, U, Nb, K, La, Ce, Sr, P and Zr of ultramafic xenoliths found in Jiangsu province, eastern China may be related to the CO2–H2O-fluids metasomatism. On the basis of Sr–Nd isotopic ratios, we suggest that the lithospheric mantle beneath the study area mostly belongs to depleted-type mantle but with slightly enriched signatures, indicating the heterogeneous characteristics in the mantle source and the influence of different degrees of fluids-metasomatism on the mantle composition. The equilibrium P–T conditions of the spinel lherzolite xenoliths are: T = 913 ∼1045°C, P = 13 ∼22 kb corresponding to depths of 45–83 km. The P–T conditions suggest that the geothermal gradient of the upper mantle beneath the study area is approximately similar to oceanic geotherm which may be caused by asthenosphere upwelling. We suggested that lithospheric mantle thinning accompanied by asthenosphere upwelling has occurred and a newly accreted and cooled asthenospheric mantle may exist beneath the study area.

  1. The dynamics of Eastern Mediterranean Meso-Cenozoic tectonics: insights from three-dimensional models of free-subduction

    Science.gov (United States)

    Capitanio, Fabio A.

    2013-04-01

    The closure of the Tethys and the collision of Arabian continent in the Eastern Mediterranean are associated with large deformation in the Eurasian plate, as the Aegean Sea opening and the Anatolian extrusion. Tomographic imaging and reconstructions show that entrainment of heterogeneous lithosphere, from oceanic to continental, slab detachments and lithospheric tearing occurred during subduction. Modelling such processes by means of three-dimensional numerical methods allows testing the impact these regional features have on the force balance at convergent margins and their evolution. The models show that differential retreat along the trench is a consequence of along-trench slab buoyancy gradients, resulting from the entrainment of variably buoyant lithospheres. When slab buoyancy gradients increase, stresses are accommodated at shallow depth, within the deforming upper plate. The localisation of large stress in the upper plate, above the plastic limit, forms a new plate margin at large distance in the continent interiors. The bounding newly formed and the convergent margins allow the lateral extrusion of a large rigid block of lithosphere in between and strong velocity gradients. Internal deformation within the extruding block occurs when lithospheric tears disrupt the slab coherence, and the trench segments. This quantitative model presented illustrates a novel mechanism of plate margins formation and continental tectonics in time, and is here tested against the Eastern Mediterranean tectonics. The models reproduce the Meso-Cenozoic evolution of the margin, from the Aegean trench retreat to the formation of the North Anatolian Fault, and yields motions that are strikingly compatible with present-day geodetic observable. The models allow speculations on the present-day state of stress of the area and deformation within the Anatolian block. Albeit simplified, these models elucidate the controls of deep subduction processes on the tectonics of the Aegean Sea and

  2. Monitoring Ocean Carbon and Ocean Acidification

    OpenAIRE

    Tanhua, Toste; Orr, James C.; Lorenzoni, Laura; Hansson, Lina

    2015-01-01

    As atmospheric CO2 continues to increase, more and more CO2 enters the ocean, which reduces pH (pH is a measure of acidity, the lower the pH, the more acidic the liquid) in a process referred to as ocean acidification. Declines in surface ocean pH due to ocean acidification are already detectable and accelerating.

  3. Late Cenozoic sedimentary process and its response to the slip history of the central Altyn Tagh fault, NW China

    Institute of Scientific and Technical Information of China (English)

    陈正乐; 张岳桥; 陈宣华; 王小凤; A.S.Ramon; W.B.Zack

    2001-01-01

    The ENE-striking Altyn Tagh fault (ATF), extending along the northern edge of the Tibetan Plateau, is one of the major important strike-slip faults, and has been known as one of the key areas to debate the eastward extrusion and crustral shortening models of the Tibetan Plateau during and after India-Asia collision. This paper mainly presents new evidence of Late Cenozoic sedimentary process to reconstruct the slip history of the ATF during the Late Cenozoic. Field measurements and laboratory analyses of the sedimentary characteristics in the Late Cenozoic basins in the central Altyn Tagh fault suggest that Late Cenozoic sedimentary sequence should be divided into three units according to facies changes. The paleo-topography reconstruction shows that the sedimentation in these basins was tightly related with the fault, indicating that the ATF has experienced at least three stages of strike slipping in the Late Cenozoic. New geological data from the Late Cenozoic sedimentary basins and the formation of th

  4. Cenozoic Volcanism and Intraplate Subduction at the Northern Margin of the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    邓万明

    1991-01-01

    Developed in the Mt.Kunlun orogenic belt at the northern margin of the Tibetan Plateau is an active Cenozoic volcanic zone which is more than 1000km in length and some ten to hundred kilometers in width.It extends east-westwards and is roughly parallet to the strike of Mt.Kunlun.The Cenozoic volcanic rocks are divided into the northern(N-)and southern(S-)subzones.Eruptions of volcanic lavas in the S-subzone are related to an initial rift zone within the north Qiangtang terrane,but the volcanic rocks in the N-subzone are relatively close to the contact zone between the Mt.Kunlun and the Tarim terrane.The space-time distribution,petrological and geochemical features can be explained by a model of southward intraplate subduction of the Tarim terrane.

  5. LATE CREATACEOUS-CENOZOIC SEDIMENTS OF THE BAIKAL RIFT BASIN AND CHANGING NATURAL CONDITIONS

    Directory of Open Access Journals (Sweden)

    Viktor D. Mats

    2015-09-01

    Full Text Available The late Cretaceous-Cenozoic sediments of fossil soils and weathering crusts of the Baikal rift have been subject to long-term studies. Based on our research results, it is possible to distinguish the following litho-stratigraphic complexes which are related to particular stages of the rift development: the late Cretaceous–early Oligocene (crypto-rift Arheo-baikalian, the late Oligocene–early Pliocene (ecto-rift early orogenic Pra-baikalian, and the late Pliocene-Quaternary (ecto-rift late orogenic Pra-baikalian – Baikalian complexes. Changes of weathering modes (Cretaceous-quarter, soil formation (Miocene-quarter and differences of precipitation by vertical and lateral stratigraphy are analysed with regard to specific features of climate, tectonics and facial conditions of sedimentation. Tectonic phases are defined in the Cenozoic period of the Pribaikalie.

  6. Climate vs. tectonic induced variations in Cenozoic sediment supply from western Scandinavia

    DEFF Research Database (Denmark)

    Gołędowski, Bartosz; Nielsen, S.B.; Clausen, O.R.

    on a particular rudimentary understanding of the Davisian cyclic landscape evolution model, which does not consider the occurrence of flexural isostasy or glacial buzzsaw processes. Observations of small scale sedimentary structures of ambiguous origin and activity of salt-related structures is not evidence...... for this hypothesised large-scale uplift [13]. Furthermore, there is little if any evidence for onshore Cenozoic tectonic activity, which is also not constrained by fission track dating [2, 14-20]. Climate variations during Cenozoic times are constrained by oxygen isotope values in benthic foraminifera [21...... by extensive vegetation cover as little bedrock is exposed and soils are well-developed. In case of climate cooling the tree limit lowers, exposing more bedrock for erosion. Furthermore, the erosional regime changes dramatically in the presence of alpine glaciers and cirques and when periglacial processes...

  7. The Norwegian Danish Basin: A key to understanding the Cenozoic in the eastern North Sea

    Science.gov (United States)

    Rasmussen, Thomas L.; Clausen, Ole R.; Andresen, Katrine J.; Goledowski, Bartosz

    2015-04-01

    The Danish part of Norwegian-Danish Basin, which constitutes the eastern part of the North Sea Basin, has been the key area for sequence stratigraphic subdivision and analysis of the Cenozoic succession since the mid 1990's. Widespread 3D seismic data, in the central parts of the North Sea Basin, as well as more scattered 3D seismic data in the Danish part of the Norwegian-Danish Basin, have given a more detailed understanding of the sequences and indicate that climate is tenable for the origin of Cenozoic sequence boundaries. The previous sequence stratigraphic interpretations have been an integrated part of an ongoing debate concerning vertical movements of the Fennoscandian shield versus the impact of climate and erosion. A newly accessed coherent regional 2D and reprocessed 3D seismic data set, in the Norwegian part of the Norwegian-Danish Basin, constitute the database for a new sequence stratigraphic analysis of the entire area. The objective of the new study is to test previous subdivisions and introduce a coherent 3D sequence stratigraphic analysis and depositional model for the entire Norwegian-Danish Basin. This analysis is necessary to get out of the stalemate with the uplift discussion. The study shows that the original subdivision by Michelsen et al. (1995, 1998) stands. However, revision of few a sequence boundaries may have to be adjusted due to new biostratigraphic information published. Furthermore, high-angle clinoforms and geomorphological transport complexes observed in the Danish North Sea Basin can be traced into the Norwegian sector. This together with the recognition of several other high-angle clinoform complexes, and their associated seismic facies distribution maps and thickness-maps, enhances the level of detail and constrains the previous published paleogeographic reconstructions of the Cenozoic. The geometry of the Cenozoic infill, in the Norwegian part of the Norwegian-Danish Basin, is here interpreted to be controlled by relative sea

  8. Late Cenozoic deformation of the Gavrovo and Ionian zones in NW Peloponnesos (Western Greece)

    OpenAIRE

    S. Tsaila-Monopoli; O. Aximniotou; S. Sotiropoulos; E. Kamberis; C. Ioakim

    2000-01-01

    The structural deformation of Mesozoic-Tertiary sediments of the Ionian and Gavrovo zones in NW Peloponnesos is related to the propagation of a fold-thrust system during the Cenozoic. The sediments of the Gavrovo zone have been deformed by high angle reverse faulting generating an imbricate fan. Skolis mountain represents the Gavrovo thrust front. The detachment occurred in the underlying flysch of the Ionian zone. The Ionian zone has also been affected by shortening above a detachment horizo...

  9. Biogeochemistry of silica in Devils Lake: Implications for diatom preservation

    Science.gov (United States)

    Lent, R.M.; Lyons, B.

    2001-01-01

    Diatom-salinity records from sediment cores have been used to construct climate records of saline-lake basins. In many cases, this has been done without thorough understanding of the preservation potential of the diatoms in the sediments through time. The purpose of this study was to determine the biogeochemistry of silica in Devils Lake and evaluate the potential effects of silica cycling on diatom preservation. During the period of record, 1867-1999, lake levels have fluctuated from 427 m above sea level in 1940 to 441.1 m above sea level in 1999. The biogeochemistry of silica in Devils Lake is dominated by internal cycling. During the early 1990s when lake levels were relatively high, about 94% of the biogenic silica (BSi) produced in Devils Lake was recycled in the water column before burial. About 42% of the BSi that was incorporated in bottom sediments was dissolved and diffused back into the lake, and the remaining 58% was buried. Therefore, the BSi accumulation rate was about 3% of the BSi assimilation rate. Generally, the results obtained from this study are similar to those obtained from studies of the biogeochemistry of silica in large oligotrophic lakes and the open ocean where most of the BSi produced is recycled in surface water. During the mid 1960s when lake levels were relatively low, BSi assimilation and water-column dissolution rates were much higher than when lake levels were high. The BSi assimilation rate was as much as three times higher during low lake levels. Even with the much higher BSi assimilation rate, the BSi accumulation rate was about three times lower because the BSi water-column dissolution rate was more than 99% of the BSi assimilation rate compared to 94% during high lake levels. Variations in the biogeochemistry of silica with lake level have important implications for paleolimnologic studies. Increased BSi water-column dissolution during decreasing lake levels may alter the diatom-salinity record by selectively removing the

  10. Biogeographical consequences of Cenozoic tectonic events within East Asian margins: a case study of Hynobius biogeography.

    Directory of Open Access Journals (Sweden)

    Jun Li

    Full Text Available Few studies have explored the role of Cenozoic tectonic evolution in shaping patterns and processes of extant animal distributions within East Asian margins. We select Hynobius salamanders (Amphibia: Hynobiidae as a model to examine biogeographical consequences of Cenozoic tectonic events within East Asian margins. First, we use GenBank molecular data to reconstruct phylogenetic interrelationships of Hynobius by bayesian and maximum likelihood analyses. Second, we estimate the divergence time using the bayesian relaxed clock approach and infer dispersal/vicariance histories under the 'dispersal-extinction-cladogenesis' model. Finally, we test whether evolutionary history and biogeographical processes of Hynobius should coincide with the predictions of two major hypotheses (the 'vicariance'/'out of southwestern Japan' hypothesis. The resulting phylogeny confirmed Hynobius as a monophyletic group, which could be divided into nine major clades associated with six geographical areas. Our results show that: (1 the most recent common ancestor of Hynobius was distributed in southwestern Japan and Hokkaido Island, (2 a sister taxon relationship between Hynobius retardatus and all remaining species was the results of a vicariance event between Hokkaido Island and southwestern Japan in the Middle Eocene, (3 ancestral Hynobius in southwestern Japan dispersed into the Taiwan Island, central China, 'Korean Peninsula and northeastern China' as well as northeastern Honshu during the Late Eocene-Late Miocene. Our findings suggest that Cenozoic tectonic evolution plays an important role in shaping disjunctive distributions of extant Hynobius within East Asian margins.

  11. Cenozoic Volcanism in South China Sea and Its Vicinity and South China Sea Spreading

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The rock series, rock types and Sr-Nd isotopic dating of the Cenozoic volcanic rocks in the South China Sea are similar to those in its vicinity. On the basis of the spreading age of the South China Sea, the Cenozoic volcanic rocks are divided into three stages: the pre-spreading stage, the spreading stage and the post-spreading stage. The deep process characteristics of the asthenosphere and lithosphere may be inferred from the study on primary basaltic magma. The top layers of the asthenosphere both in the spreading stage and in the pre-spreading stage are closer to the earth surface than that in the post-spreading stage. From the pre-spreading stage to the spreading stage, the top layer of the asthenosphere decreased in depth, while the amount of interstitial partial melts increased. The evolution of the primary basaltic magma shows a progressive evolution sequence of the rifting volcanism and a faster lithospheric spreading velocity. From the spreading stage to the post-spreading stage, the top layer of the asthenosphere gradually increased in depth, but the amount of interstitial partial melts decreased. The evolution of primary basaltic magma shows a retrogressive evolution sequence of the rifting volcanism and a gradual decrease in the lithospheric spreading velocity. The depth recognized by the study on the Cenozoic volcanism demonstrates the deep environment for the formation and evolution of the South China Sea.

  12. Cenozoic Antarctic DiatomWare/BugCam: An aid for research and teaching

    Science.gov (United States)

    Wise, S.W.; Olney, M.; Covington, J.M.; Egerton, V.M.; Jiang, S.; Ramdeen, D.K.; Kulhanek S.; Schrader, H.; Sims, P.A.; Wood, A.S.; Davis, A.; Davenport, D.R.; Doepler, N.; Falcon, W.; Lopez, C.; Pressley, T.; Swedberg, O.L.; Harwood, D.M.

    2007-01-01

    Cenozoic Antarctic DiatomWare/BugCam© is an interactive, icon-driven digital-image database/software package that displays over 500 illustrated Cenozoic Antarctic diatom taxa along with original descriptions (including over 100 generic and 20 family-group descriptions). This digital catalog is designed primarily for use by micropaleontologists working in the field (at sea or on the Antarctic continent) where hard-copy literature resources are limited. This new package will also be useful for classroom/lab teaching as well as for any paleontologists making or refining taxonomic identifications at the microscope. The database (Cenozoic Antarctic DiatomWare) is displayed via a custom software program (BugCam) written in Visual Basic for use on PCs running Windows 95 or later operating systems. BugCam is a flexible image display program that utilizes an intuitive thumbnail “tree” structure for navigation through the database. The data are stored on Micrsosoft EXCEL spread sheets, hence no separate relational database program is necessary to run the package

  13. Metallogenic systems related to Mesozoic and Cenozoic granitoids in South China

    Institute of Scientific and Technical Information of China (English)

    HUA; Renmin; (华仁民); CHEN; Peirong; (陈培荣); ZHANG; Wenlan; (张文兰); LIU; Xiaodong; (刘晓东); LU; Jianjun; (陆建军); LIN; Jinfu; (林锦富); YAO; Junming; (姚军明); QI; Huawen; (戚华文); ZHANG; Zhanshi; (张展适); GU; Shengyan; (顾晟彦)

    2003-01-01

    Large scale mineralizations of nonferrous, precious, and rare metals took place in South China in Mesozoic and Cenozoic Eras, which were mostly closely related with granitic magmatisms of different sources and features. Four metallogenic systems related to Mesozoic and Cenozoic granitoids are put forward in this paper. They are: (i) the porphyry-epithermal copper-gold system related to calc-alkaline volcanic-intrusive magmatism, (ii) rare metal (mainly W, Sn, Ta, Nb, etc) metallogenic system related with continental crust re-melting type granitoids, (iii) copper and polymetallic metallogenic system related with intra-plate high potassium calc-alkaline and shoshonitic magmatism, and (iv) Au-Cu and REE metallogenic system related to A-type granites. The main characteristics of these systems are briefly discussed. These Mesozoic and Cenozoic granitoids of different sources were the products of different periods of lithosphere evolution in that area under different tectonic-dynamic environments. Fundamentally speaking, however, the granitoids and related metallogeneses are the results of mantle-crust interactions under a tensile tectonic environment in South China.

  14. Silica Aerogel: Synthesis and Applications

    International Nuclear Information System (INIS)

    Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air), hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized from molecular precursors by sol-gel processing. Special drying techniques must be applied to replace the pore liquid with air while maintaining the solid network. Supercritical drying is most common; however, recently developed methods allow removal of the liquid at atmospheric pressure after chemical modification of the inner surface of the gels, leaving only a porous silica network filled with air. Therefore, by considering the surprising properties of aerogels, the present review addresses synthesis of silica aerogels by the sol-gel method, as well as drying techniques and applications in current industrial development and scientific research.

  15. Silica Aerogel: Synthesis and Applications

    Directory of Open Access Journals (Sweden)

    Jyoti L. Gurav

    2010-01-01

    Full Text Available Silica aerogels have drawn a lot of interest both in science and technology because of their low bulk density (up to 95% of their volume is air, hydrophobicity, low thermal conductivity, high surface area, and optical transparency. Aerogels are synthesized from molecular precursors by sol-gel processing. Special drying techniques must be applied to replace the pore liquid with air while maintaining the solid network. Supercritical drying is most common; however, recently developed methods allow removal of the liquid at atmospheric pressure after chemical modification of the inner surface of the gels, leaving only a porous silica network filled with air. Therefore, by considering the surprising properties of aerogels, the present review addresses synthesis of silica aerogels by the sol-gel method, as well as drying techniques and applications in current industrial development and scientific research.

  16. Synthesis and Characterization of Bimodal Mesoporous Silica

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaofang; GUO Cuili; WANG Xiaoli; WU Yuanyuan

    2012-01-01

    Mesoporous silica with controllable bimodal pore size distribution was synthesized with cetyltrimethylammonium bromide (CTAB) as chemical template for small mesopores and silica gel as physical template for large mesopores.The structure of synthesized samples were characterized by Fourier transform infrared (FT-IR) spectroscopy,X-ray diffraction (XRD),scanning electron microscopy (SEM),transmission electron microscopy (TEM) and N2 adsorption-desorption measurements.The experimental results show that bimodal mesoporous silica consists of small mesopores of about 3 nm and large mesopores of about 45 nm.The small mesopores which were formed on the external surface and pore walls of the silica gel had similar characters with those of MCM-41,while large mesopores were inherited from parent silica gel material.The pore size distribution of the synthesized silica can be adjusted by changing the relative content of TEOS and silica gel or the feeding sequence of silica gel and NH4OH.

  17. Physisorbed Water on Silica at Mars Temperatures

    Science.gov (United States)

    Sutter, B.; Sriwatanapongse, W.; Quinn, R.; Klug, C.; Zent, A.

    2002-01-01

    The usefulness of nuclear magnetic resonance spectroscopy in probing water interactions on silica at Mars temperatures is discussed. Results indicate that two types of water occur with silica at Mars temperatures. Additional information is contained in the original extended abstract.

  18. Cenozoic tectono-geomorphological growth of the SW Chinese Tian Shan: insight from AFT and detrital zircon U-Pb data

    OpenAIRE

    Jia, Yingying; Fu, Bihong; Jolivet, Marc; Zheng, Shuo

    2015-01-01

    As a unique example of the intracontinental mountain building, the Cenozoic deformation of the Tian Shan has been widely studied. The onset of Cenozoic exhumation of the SW Chinese Tian Shan was constrained at the Oligocene-Miocene boundary. However, the Cenozoic tectono-geomorphological growth process of the SW Chinese Tian Shan and adjacent piedmont basins remains a challenge. In this study, we carried out the geological mapping of satellite images and field investigations together with the...

  19. Constraining the vertical surface motions of the Hampshire Basin, south England During the Cenozoic

    Science.gov (United States)

    Smith, Philip; England, Richard; Zalasiewicz, Jan

    2016-04-01

    The potential effect of rising sea level on the UK has received considerable attention in recent years. However, the ongoing long-term changes in surface topography of the UK driven by regional tectonics and the mechanisms responsible are not fully understood. It is thought that glacial loading/unloading is the primary influence. However, this is inconsistent with present-day vertical surface motions recorded from Continuous Global Positioning Stations (CGPS) across the UK. The lateral variations in the present day motions are too complex to be explained by glacial isostatic rebound. We are investigating the hypothesis that the vertical motions of SE England also reflect the long term tectonic history by backstripping the Cenozoic geological record. So far the Paleogene stratigraphic record of the Hampshire basin in southern England has been investigated and using a series of deep boreholes that reach the chalk basement, a 2-D backstripping method has been applied. Subsidence analysis of cliff sections and boreholes reveal the Hampshire Basin was tectonically subsiding at a steady rate from 56.5Ma and any major periods of uplift and denudation to the present day state must have occurred from the mid Oligocene onwards. At this time the northern and western regions of the UK were believed to be uplifting as evidenced by heavy mineral transport directionns and sediment drainage patterns. A rapid increase in tectonic subsidence from 42Ma recorded by the three Isle of Wight sections in close proximity to an existing Variscan fault, thought to reactivate as a thrust during the Cenozoic, suggests a compressional stress regime in this region. The stress pattern observed from the tectonic subsidence data and evidence from drainage patterns supports a model in which the UK was uplifting in the north and west while the south east was subsiding. As this pattern is similar to the present day vertical surface motions and pre-dates glaciation, we propose glacial unloading as a

  20. Did high Neo-Tethys subduction rates contribute to early Cenozoic warming?

    Directory of Open Access Journals (Sweden)

    G. Hoareau

    2015-07-01

    Full Text Available The 58–51 Ma interval was characterized by a long-term increase of global temperatures (+4 to +6 °C up to the Early Eocene Climate Optimum (EECO, 52.9–50.7 Ma, the warmest interval of the Cenozoic. It was recently suggested that sustained high atmospheric pCO2, controlling warm early Cenozoic climate, may have been released during Neo-Tethys closure through the subduction of large amounts of pelagic carbonates and their recycling as CO2 at arc volcanoes ("carbonate subduction factory". To analyze the impact of Neo-Tethys closure on early Cenozoic warming, we have modeled the volume of subducted sediments and the amount of CO2 emitted at active arc volcanoes along the northern Tethys margin. The impact of calculated CO2 fluxes on global temperature during the early Cenozoic have then been tested using a climate carbon cycle model (GEOCLIM. We first show that CO2 production may have reached up to 1.55 × 1018 mol Ma−1 specifically during the EECO, ~ 4 to 37 % higher that the modern global volcanic CO2 output, owing to a dramatic India–Asia plate convergence increase. In addition to the background CO2 degassing, the subduction of thick Greater Indian continental margin carbonate sediments at ~ 55–50 Ma may also have led to additional CO2 production of 3.35 × 1018 mol Ma−1 during the EECO, making a total of 85 % of the global volcanic CO2 outgassed. However, climate modelling demonstrates that timing of maximum CO2 release only partially fit with the EECO, and that corresponding maximum pCO2 values (750 ppm and surface warming (+2 °C do not reach values inferred from geochemical proxies, a result consistent with conclusions arise from modelling based on other published CO2 fluxes. These results demonstrate that CO2 derived from decarbonation of Neo-Tethyan lithosphere may have possibly contributed to, but certainly cannot account alone for early Cenozoic warming, including the EECO. Other commonly cited sources of excess CO2 such as

  1. Variations in Cenozoic seawater uranium reconstructed from well preserved aragonitic fossil corals

    Science.gov (United States)

    Gothmann, A. O.; Higgins, J. A.; Bender, M. L.; Stolarski, J.; Adkins, J. F.; McKeon, R. E.; Farley, K. A.; Wang, X.; Planavsky, N.

    2015-12-01

    U/Ca ratios were measured in a subset (n ≈ 30) of well preserved scleractinian fossil corals previously described by Gothmann et al. (2015) in order to investigate Cenozoic changes in seawater [U]. He/U dating studies and measurements of 234U/238U and δ238/235U provide constraints on fossil coral U preservation. He/U ages also demonstrate the ability of well preserved coral aragonite to retain most of its radiogenic He over million year timescales. We find that fossil coral U/Ca has increased by a factor of ~4 between the Early Cenozoic and today. This number is calculated from the change in seawater [Ca2+] implied by brine inclusions and other proxies, and the assumption that the U/Ca in shallow water corals equals the seawater ratio. The change cannot be attributed to a dependence of coral U uptake on seawater pH or [CO32-] (e.g., Inoue et al., 2011), which would lead to a decrease in U/Ca going forward in time. Instead, we suggest that seawater [U] has increased since the Early Cenozoic. Possible explanations for the inferred change include: (1) a small decrease in uranium uptake in suboxic and anoxic sediments over the Cenozoic, (2) a decrease in the rate of low-temperature hydrothermal alteration, and associated U uptake, over the Cenozoic, and (3) a decrease in U removal from seawater resulting from an increase in UO2-CO3 complexation, as originally suggested by Broecker (1971). References: Broecker, W. S. (1971) A Kinetic Model for the Chemical Composition of Sea Water. Quaternary Research, 1, 188-207. Gothmann, A.M., Stolarski, J., Adkins, J.F., Dennis, K.J., Schrag, D.P., Schoene, B., Bender, M.L. (2015) Fossil corals as an archive of secular variations in seawater chemistry. Geochimica et Cosmochimica Acta, 160, 188-208. Inoue, M., Suwa, R., Suzuki, A., Sakai, K., and Kawahata, H., (2011) Effects of seawater pH on growth and skeletal U/Ca ratios of Acropora digitifera coral polyps. Geophysical Research Letters 38, 12801-12804.

  2. Polyurethane reinforced by silica and silica filled with polyurethane

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Špírková, Milena; Poreba, Rafal

    Prague : Institute of Macromolecular Chemistry AS CR, 2015. L9. ISBN 978-80-85009-83-5. [Workshop "Career in Polymers" /7./. 03.07.2015, Prague] R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane water dispersion * polycarbonate macrodiol * colloidal silica Subject RIV: CD - Macromolecular Chemistry

  3. Planet Ocean

    Science.gov (United States)

    Afonso, Isabel

    2014-05-01

    A more adequate name for Planet Earth could be Planet Ocean, seeing that ocean water covers more than seventy percent of the planet's surface and plays a fundamental role in the survival of almost all living species. Actually, oceans are aqueous solutions of extraordinary importance due to its direct implications in the current living conditions of our planet and its potential role on the continuity of life as well, as long as we know how to respect the limits of its immense but finite capacities. We may therefore state that natural aqueous solutions are excellent contexts for the approach and further understanding of many important chemical concepts, whether they be of chemical equilibrium, acid-base reactions, solubility and oxidation-reduction reactions. The topic of the 2014 edition of GIFT ('Our Changing Planet') will explore some of the recent complex changes of our environment, subjects that have been lately included in Chemistry teaching programs. This is particularly relevant on high school programs, with themes such as 'Earth Atmosphere: radiation, matter and structure', 'From Atmosphere to the Ocean: solutions on Earth and to Earth', 'Spring Waters and Public Water Supply: Water acidity and alkalinity'. These are the subjects that I want to develop on my school project with my pupils. Geographically, our school is located near the sea in a region where a stream flows into the sea. Besides that, our school water comes from a borehole which shows that the quality of the water we use is of significant importance. This project will establish and implement several procedures that, supported by physical and chemical analysis, will monitor the quality of water - not only the water used in our school, but also the surrounding waters (stream and beach water). The samples will be collected in the borehole of the school, in the stream near the school and in the beach of Carcavelos. Several physical-chemical characteristics related to the quality of the water will

  4. Poling of Planar Silica Waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Kristensen, Martin; Jensen, Jesper Bo

    1999-01-01

    UV-written planar silica waveguides are poled using two different poling techniques, thermal poling and UV-poling. Thermal poling induces an electro-optic coefficient of 0.067 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. The induced electro-optic effect shows a linear dependence...

  5. Ocean Uses: Hawaii (PROUA)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Pacific Regional Ocean Uses Atlas (PROUA) Project is an innovative partnership between NOAA and the Bureau of Ocean Energy Management (BOEM) designed to...

  6. Silica-Coated Liposomes for Insulin Delivery

    Directory of Open Access Journals (Sweden)

    Neelam Dwivedi

    2010-01-01

    Full Text Available Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evident from Confocal Micro-Raman spectroscopy. Silica coat enhances the stability of insulin-loaded delivery vehicles. In vivo study shows that these silica coated formulations were biologically active in reducing glucose levels.

  7. Silica Pigments for Glossy Ink Jet Media

    Institute of Scientific and Technical Information of China (English)

    Sun Qi; Michael R. Sestrick; Yoshi Sugimoto; William A. Welsh

    2004-01-01

    Silica is a versatile pigment for ink jet media. Micronized silica gel is the worldwide standard for high performance matte ink jet media. For glossy ink jet media, several different forms of silica are widely used. Submicron silica gel dispersions, with either anionic or cationic surfaces, can be employed in either absorptive basecoat layers or in the glossy ink receptive top layer. Colloidal silica, with a variety of particle sizes and surface modifications, is utilized extensively in glossy top layers. It will show how various silica pigments can be utilized in glossy ink receptive coatings, both in cast based glossy media and RC based glossy media. Several novel silica pigments will be examined by relating the physical properties of the pigments and the formula variables to the print quality of the ink jet media.

  8. Radiation curing of silica for silica-rubber composites

    International Nuclear Information System (INIS)

    The functional modification of silica samples based on the reaction of '' grafting '' of polybutadiene oligomers carried out by gamma-irradiation in the presence of air at room temperature has been investigated. The yield of grafted PB reaches a maximum at doses of about 30 kGy, then decreases as a consequence of the oxidative degradation. The reaction is accompanied by the build up of carbonyls and peroxides up to 0.1 moles/kg and it leads to a rapid consumption of the double bonds concentration as determined by both FTIR and Raman spectroscopy. The results of the EPR analysis are diagnostic of a mechanism of immobilization of the oligomer based on cross-linking of polybutadiene which is initiated by the SiO2 radiolytic species. Depending on the nature of the SiO2 species, the mechanism of initiation leads to immobilized PB either really grafted to the silica surface or simply physically absorbed. (authors)

  9. Silicon isotope fractionation during silica precipitation from aqueous solutions: Experimental and field evidence (Utrecht Studies in Earth Sciences 048)

    NARCIS (Netherlands)

    Geilert, S.

    2013-01-01

    Climate conditions during Earth’s earliest history were very different from today. Knowledge about this issue is crucial for understanding the development of life on our planet. Billions of years ago, silica-rich rocks formed on the ocean floor, and a small volume is still preserved in surface expos

  10. Cenozoic stratigraphy and geologic history of the Tucson Basin, Pima County, Arizona

    Science.gov (United States)

    Anderson, S.R.

    1987-01-01

    This report was prepared as part of a geohydrologic study of the Tucson basin conducted by the U.S. Geological Survey in cooperation with the city of Tucson. Geologic data from more than 500 water supply and test wells were analyzed to define characteristics of the basin sediments that may affect the potential for land subsidence induced by groundwater withdrawal. The Tucson basin is a structural depression within the Basin and Range physiographic province. The basin is 1,000 sq mi in units area and trends north to northwest. Three Cenozoic stratigraphic unit--the Pantano Formation of Oligocene age, the Tinaja beds (informal usage) of Miocene and Pliocene age, and the Fort Lowell Formation of Pleistocene age--fill the basin. The Tinaja beds include lower, middle, and upper unconformable units. A thin veneer of stream alluvium of late Quaternary age overlies the Fort Lowell Formation. The Pantano Formation and the lower Tinaja beds accumulated during a time of widespread continental sedimentation, volcanism, plutonism, uplift, and complex faulting and tilting of rock units that began during the Oligocene and continued until the middle Miocene. Overlying sediments of the middle and upper Tinaja beds were deposited in response to two subsequent episodes of post-12-million-year block faulting, the latter of which was accompanied by renewed uplift. The Fort Lowell Formation accumulated during the Quaternary development of modern through-flowing the maturation of the drainage. The composite Cenozoic stratigraphic section of the Tucson basin is at least 20,000 ft thick. The steeply tilted to flat-lying section is composed of indurated to unconsolidated clastic sediments, evaporites, and volcanic rocks that are lithologically and structurally complex. The lithology and structures of the section was greatly affected by the uplift and exhumation of adjacent metamorphic core-complex rocks. Similar Cenozoic geologic relations have been identified in other parts of southern

  11. Late Cenozoic volcanism, geochronology, and structure of the Coso Range, Inyo County, California

    Energy Technology Data Exchange (ETDEWEB)

    Duffield, W.A.; Bacon, C.R.; Dalrymple, G.B.

    1980-05-10

    The Coso Range lies at the west edge of the Great Basin, adjacent to the southern part of the Sierra Nevada. A basement complex of pre-Cenozoic plutonic and metamorphic rocks is partly buried by approx.35 km/sup 3/ of late Cenozoic volcanic rocks that were erupted during two periods, as defined by K-Ar dating: (1) 4.0--2.5 m.y., approx.31 km/sup 3/ of basalt, rhyodacite, dacite, andesite, and rhyolite, in descending order of abundance, and (2) < or =1.1 m.y., nearly equal amounts of basalt and rhyolite, most of the rhyolite being < or =0.3 m.y. old. Vents for the volcanic rocks of the younger period are localized on and near a horst of basement rocks within a concavity defined by the distribution of vents of the older period. The alignment of many vents and the presence of a considerable number of roughly north-trending normal faults of late Cenozoic age reflect basin and range tectonics dominated by roughly east-west lithospheric extension. Fumaroles, intermittently active thermal springs, and associated altered rocks occur within and immediately east of the central part of the field of Quaternary rhyolite, in an area characterized by various geophysical anomalies that are evidently related to an active hot-water geothermal system. This system apparently is heated by a reservoir of silicic magma at > or =8-km depth, itself produced and sustained through partial melting of crustal rocks by thermal energy contained in mantle-derived basaltic magma that intrudes the crust in repsonse to lithospheric extension.

  12. Late Cenozoic fire enhancement response to aridification in mid-latitude Asia: Evidence from microcharcoal records

    Science.gov (United States)

    Miao, Yunfa; Fang, Xiaomin; Song, Chunhui; Yan, Xiaoli; Zhang, Ping; Meng, Qingquan; Li, Fang; Wu, Fuli; Yang, Shengli; Kang, Shuyuan; Wang, Yuanping

    2016-05-01

    Fire provides an important indicator of paleoclimatic change. However, little information relating to late Cenozoic fire history has been gathered in mid-latitude Asia (including Inner Asia and East Asia), a key region for understanding the development of the arid-monsoon climate system as well as the driving forces behind it. Here we first report the records of microcharcoal concentrations (MC) covering the Holocene (10-0 ka) and late Pleistocene (0.8-0 Ma), which we use to analyze the fire activity patterns at an orbital time scale; then we compile the late Cenozoic MC record to investigate the long-term fire history by analyzing four cores from the Yangtze River Delta (YRD) area, East Asia (representing 8-0 Ma) and three sites in Inner Asia (representing 18-2 Ma). The results show that the (i) MC remained higher during the relatively dry late Holocene/glacial stages than that during the humid middle Holocene/interglacial stages at individual sites; (ii) MC increased with time in both Inner Asia and East Asia after 18 and 8 Ma, respectively; and (iii) MC always remained higher in the dry Inner Asia than in the contemporaneous wet East Asia. All these characteristics imply that late Cenozoic fire occurrence in mid-latitude Asia experienced a gradual increasing trend along with the global temperature/ice volume change, and indicates a continuous aridification trend across mid-latitude Asia. The global cooling, rather than the Tibetan Plateau uplift, might have played a key role in this observed trend.

  13. Discovery of Enclaves from Cenozoic Pulu Volcanic Rocks in West Kunlun Mountains and Its Geological Implications

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In this paper, we present the occurrence and mineral components of the enclaves firstly discovered in the Cenozoic Pulu volcanic rocks in west Kunlun Mountains, and propose that the enclave is accumulated by fractional crystallization within high-level magma chamber. In addition, the chemical compositions of its primary magma are calculated. The calculated compositions are similar to those of the Kangxiwa volcanic rocks that belong to the same volcanic belt in the Pulu volcanic region, suggesting their origin from the same source region. However, the temperatures and oxygen fugacity of magmas at high-level magma chamber decreased along with fractional crystallization.

  14. Greater India Basin Hypothesis and A Two-Stage Cenozoic Collision Between India and Asia

    OpenAIRE

    D. J. J. van Hinsbergen; Lippert, P.C.; Dupont-Nivet, G.; McQuarrie, N.; Doubrovine, P. V.; Spakman, W.; T. H. Torsvik

    2013-01-01

    Cenozoic convergence between the Indian and Asian plates produced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India–Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 ± 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. ...

  15. Signatures of downgoing plate-buoyancy driven subduction in Cenozoic plate motions

    Science.gov (United States)

    Goes, S.; Capitanio, F. A.; Morra, G.; Seton, M.; Giardini, D.

    2011-01-01

    The dynamics of plate tectonics are strongly related to those of subduction. To obtain a better understanding of the driving forces of subduction, we compare relations between Cenozoic subduction motions at major trenches with the trends expected for the simplest form of subduction. i.e., free subduction, driven solely by the buoyancy of the downgoing plate. In models with an Earth-like plate stiffness (corresponding to a plate-mantle viscosity contrast of 2-3 orders of magnitude), free plates subduct by a combination of downgoing plate motion and trench retreat, while the slab is draped and folded on top of the upper-lower mantle viscosity transition. In these models, the slabs sink according to their Stokes' velocities. Observed downgoing-plate motion-plate-age trends are compatible with >80% of the Cenozoic slabs sinking according to their upper-mantle Stokes' velocity, i.e., subducting-plate motion is largely driven by upper-mantle slab pull. Only in a few cases, do young plates move at velocities that require a higher driving force (possibly supplied by lower-mantle-slab induced flow). About 80% of the Cenozoic trenches retreat, with retreat accounting for about 10% of the total convergence. The few advancing trench sections are likely affected by regional factors. The low trench motions are likely encouraged by low asthenospheric drag (equivalent to that for effective asthenospheric viscosity 2-3 orders below the upper-mantle average), and low lithospheric strength (effective bending viscosity ˜2 orders of magnitude above the upper-mantle average). Total Cenozoic trench motions are often very oblique to the direction of downgoing-plate motion (mean angle of 73°). This indicates that other forces than slab buoyancy exert the main control on upper-plate/trench motion. However, the component of trench retreat in the direction of downgoing plate motion (≈ slab pull) correlates with downgoing-plate motion, and this component of retreat generally does not

  16. Review of the upper Cenozoic stratigraphy overlying the Columbia River Basalt Group in western Idaho

    International Nuclear Information System (INIS)

    This report is a synthesis of information currently available on the rocks that stratigraphically overlie the Columbia River Basalt Group in Idaho. The primary objective is to furnish a brief but comprehensive review of the literature available on upper Cenozoic rocks in western Idaho and to discuss their general stratigraphic relationships. This study also reviews the derivation of the present stratigraphy and notes weaknesses in our present understanding of the geology and the stratigraphy. This report was prepared in support of a study to evaluate the feasibility of nuclear waste storage in the Columbia River Basalt Group of the Pasco Basin, Washington

  17. Long-term Stability of Global Erosion Rates and Weathering Fluxes during late Cenozoic Cooling

    OpenAIRE

    Willenbring, J.K.; Friedhelm von Blanckenburg

    2009-01-01

    Over geologic timescales, removal of atmospheric CO2 by weathering of silicate rocks balances CO2 input from the Earth´s interior. The coincidence of global cooling and the rise of mountain belts during the late Cenozoic has led geologists to suggest feedbacks between these two events. A centerpiece of t5his hypothesis was partially founded on observations of a young (0-5 My) 4-fold increase in global sedimentation rates, which seemed like a clear proxy for increased denudation and uplift of ...

  18. MESOZOIC-CENOZOIC INVERSION OFTHE TURPAN-HAMI BASIN, NORTHWEST CHINA

    Institute of Scientific and Technical Information of China (English)

    CaoDaiyong; QianGuangmo; ZhangPengfei; MeiMeitang; JinKuili; TangYuegang

    1996-01-01

    The Turpan-Hami basin, rich in coal and petroleum, is a superimposedbasin of three types basins in different tectonic environments. This coal, oil and gasbasin has undergone a complex tectonic-sedimentary evolution, in which two important stages were the negative inversion from a foredeep to a extensional basin duringEarly Mesozoic and the positive inversion to a thrust foreland basin in Late MesozoicEarly Cenozoic. The early normal faults residues are recognized with the addition oftectonic-sedimentary analysis to confirm the basin extension during Jurassic time andits tectonic inversion subsequently.

  19. Wrench-Slip Reversals and Structural Inversions: Cenozoic Slide-Rule Tectonics in Sundaland

    OpenAIRE

    Tjia, H.D.

    2014-01-01

    DOI: 10.17014/ijog.v1i1.174Most of continental Southeast Asia, that is, Sundaland and Indosinia, achieved a relative tectonic stability by the beginning of the Cenozoic. Since then a strong tectonic activity in Sundaland has been restricted to existing regional fault zones and to regional slow, vertical crustal movements elsewhere that produced small to very large sedimentary basins. On the other hand, regional deformation of Indosinia as a consequence of ductile shearing has continued into t...

  20. New Eocene damselflies and first Cenozoic damsel-dragonfly of the isophlebiopteran lineage (Insecta: Odonata).

    Science.gov (United States)

    Garrouste, Romain; Nel, André

    2015-01-01

    The study of a new specimen of Petrolestes hendersoni from the Eocene Green Formation allows a more precise description of the enigmatic damselfly and the diagnosis of the Petrolestini. Petrolestes messelensis sp. nov. is described from the Eocene Messel Formation in Germany, extending the distribution of the Petrolestini to the European Eocene. The new damsel-dragonfly family Pseudostenolestidae is described for the new genus and species Pseudostenolestes bechlyi, from the Eocene Messel Formation. It is the first Cenozoic representative of the Mesozoic clade Isophlebioptera. PMID:26624314

  1. Temporal evolution of island arc magmatism: geochronology, petrology et geochemistry of mesozoic and cenozoic magmatic rocks from Sumatra (Indonesia); Evolution temporelle du magmatisme d`arc insulaire: geochronologie, petrologie et geochimie des magmatismes mesozoiques et cenozoiques de Sumatra (Indonesie)

    Energy Technology Data Exchange (ETDEWEB)

    Sutanto

    1997-07-07

    Sumatra island (Western Indonesia) belongs to the Sunda magmatic arc, which results from the subduction of the Indian ocean plate beneath the margin of the Eurasiatic continental block. Plutonic and volcanic rocks of Mesozoic and Cenozoic ages are very abundant in Sumatra, where they mainly outcrop in a NNW-SSE trending, 1,650 km-long stripe in the western part of the island. The spatial and temporal distributions of magmatic rocks in Sumatra were not previously investigated in detail. We have performed 175 {sup 40}K-{sup 40}Ar datings on bulk rocks and minerals separated from samples which have also been analysed for major and trace elements by ICP-AES. These results allow to discuss the distribution of magmatic events in space of a long subduction period on the chemical composition of the Sunda arc mantle wedge. (author)

  2. 温盐环流反转及其对新生代气候的影响%TRANSITION OF THERMOHALINE CIRCULATION MODES AND ITS IMPACT ON CENOZOIC CLIMATE

    Institute of Scientific and Technical Information of China (English)

    张仲石; 王会军; 郭正堂

    2009-01-01

    温盐环流是由海水温度、盐度差异驱动的全球洋流循环系统.在气候系统中,它对全球热量输送起到了十分重要的作用.在亚轨道尺度(千年时间尺度)上,温盐环流的改变导致了一系列快速的气候变化,因此备受关注.在构造时间尺度(百万年时间尺度)上,古海洋记录和数值模拟揭示出,温盐环流的反转对新生代气候也产生了非常显著的影响.在新生代,温盐环流由"南大洋深层水主控型"向"北大西洋深层水主控型"反转.这一反转改变了全球的热量输送,使得南半球强烈变冷,并有町能导致南极东部永久冰盖的形成.在这一反转事件中,热带海道的作用更加重要.%The thermohaline circulation(THC)is a large-scale ocean circulation driven by global density gradients created by surface heat and freshwater fluxes. It plays an important role in the globale heat transport. Changes of the circulation have large impacts on the Earth climate. They cause a series of abrupt climate variations on the sub-orbital time scale, I. E., the millennial scale. Thus, the thermohaline circulation receives much concern. Here, based on paleoceanographic evidence and numeral modeling, we show that the thermohaline circulation also affect the climate markedly on the tectonic time scale,I, e., the million-year scale. In the Cenozoic,the thermohaline circulation reversed from the southern ocean deep water(SODW) dominated mode to the North Atlantic deep water(NADW) dominated mode,though the time of this reversal is still under debates. Some evidence reveals that the NADW formation was active during a period of the late Early Miocene and dominated ocean circulation after about 15Ma,while the earliest evidence of the NADW formation has been found in deep sea cores of the Early Oligocene age. The recent modeling study simulated the transition of thermohaline circulation from the SODW to the NADW dominated mode. The simulation indicates that the

  3. Silica aerogel and space astrophysics

    International Nuclear Information System (INIS)

    Silica aerogels have been produced in large and transparent blocks for space astrophysics experiments since the beginning of the 1970's. They were used in cosmic ray experiments on board balloons by the Saclay group. A new space venture where aerogel Cerenkov radiators will play a decisive role is currently being prepared by a large collaboration of European and US Institutes. It will be part of the so-called International Solar Polar Mission (ISPM) which will explore the heliosphere over the full range of solar latitudes from the ecliptic (equatorial) plane to the magnetic poles of the sun. Comments on properties and long term behaviour of silica aerogel cerenkov radiators in space environment are given

  4. Trends, Rhythms, and Aberrations in Global Climate during the Cenozoic: The Interplay between Tectonic and Orbital forcing (Milutin Milankovic Medal Lecture)

    Science.gov (United States)

    Zachos, James C.

    2016-04-01

    Prior to the mid-nineties much of our understanding of early Neogene and Paleogene climate was based on relatively low-resolution reconstructions. As a consequence, under-sampled periodic climate variability appeared as noise in global records (i.e., stacks), limiting our ability to fully evaluate mechanisms of past climate change. Efforts to address this limitation began in earnest with Ocean Drilling Program Leg 154, one of the first to successfully recover high-quality stratigraphically complete and relatively expanded successions of Paleogene pelagic sediments, allowing for astronomical tuning and the development of detailed paleoclimatic records extending back into the Oligocene. The strategies implemented during this Leg to locate, recover, and tune Paleogene sequences were adapted by subsequent ODP/IODP expeditions, ultimately contributing to the development of high-resolution astronomically-tuned climate records extending back to the Cretaceous. The collective contributions of these expeditions provided the necessary framework for characterizing climate variability on orbital time scales throughout the Cenozoic, including the major transitions and aberrations, the Oligocene-Miocene (O/M), Eocene-Oligocene Transition (EOT), and the Paleocene-Eocene Thermal Maximum (PETM). In this presentation I will review the most recent advances in reconstructing past climates on orbital time scales, and how these advances are altering our understanding of the triggering mechanisms for these major climate transitions, and discuss how the interplay between tectonic processes and orbital forcing as well as physical and geochemical feedbacks contributed to drive the more rapid and extreme aberrations.

  5. Gain functionalization of silica microresonators.

    Science.gov (United States)

    Yang, Lan; Vahala, K J

    2003-04-15

    Erbium-doped solgel films are applied to the surface of silica microspheres to create low-threshold microactivity lasers. This gain functionalization can be applied by use of a number of different dopants, thereby extending the wavelength range of this class of device. Also, by varying the doping concentration and thickness of the applied solgel layer, one can vary the laser dynamics so that both continuous-wave and pulsating modes of operation are possible. PMID:12703910

  6. Middle Miocene ice sheet dynamics, deep-sea temperatures, and carbon cycling: A Southern Ocean perspective

    OpenAIRE

    Shevenell, A. E.; J. P. Kennett; Lea, D. W.

    2008-01-01

    Relative contributions of ice volume and temperature change to the global similar to 1 parts per thousand delta O-18 increase at similar to 14 Ma are required for understanding feedbacks involved in this major Cenozoic climate transition. A 3-ma benthic foraminifer Mg/Ca record of Southern Ocean temperatures across the middle Miocene climate transition reveals similar to 2 +/- 2 degrees C cooling (14.2-13.8 Ma), indicating that similar to 70% of the increase relates to ice growth. Seawater de...

  7. O, Sr and Nd isotopic constraints on Cenozoic granitoids of Northwestern Anatolia, Turkey: Enrichment by subduction zone fluids

    Science.gov (United States)

    Yücel-Öztürk, Yeşim

    2016-05-01

    The oxygen and strontium isotope compositions of Cenozoic granitoids cropping out in the İzmir-Ankara-Erzincan suture zone help constrain the petrological evolution of magmatism in northwest Anatolia. The magmatism was mostly widespread between late Eocene (∼37 Ma) and the middle Miocene (∼14-15 Ma), and is represented by volcanic and plutonic rocks of orogenic affinity, of which Ezine, Eğrigöz, Çataldağ and Kozak are the largest Tertiary granitic plutons exposed in northwest Anatolia. They vary from granite to granodiorite, and are subalkaline, belonging to the high-K calc-alkaline I-type granite series. All these characteristics, combined with major, trace element geochemical data as well as mineralogical and textural evidence, reveal that the Oligocene-Miocene granitoids of NW Anatolia are comparable with volcanic arc granites, formed in a transitional oceanic to continental collisional tectonic setting, from a hybrid source, having crustal and mantle components that underwent further interaction with the upper crust. These plutons have initial 87Sr/86Sr ratios of 0.7072-0.7094, and εNd(t) values ranging from -3.48 to -1.20. These characteristics also indicate that a crustal component played an important role in the petrogenesis of NW Anatolian Oligocene-Miocene granitoids. The moderately evolved Ezine, Eğrigöz, Çataldağ and Kozak granitoids, have δ18O values that are consistent with those of normal I-type granites (6-10‰), but the δ18O relationships among minerals of samples collected from the intrusive contacts which are closest to mineralized zones, indicate a major influence of hydrothermal processes under subsolidus conditions. The oxygen isotope systematics of the samples from these plutons result from the activity of high-δ18O fluids (magmatic water), with major involvement of low-δ18O fluids (meteoric water) evident, near the edge zone of these plutons. This is most evident in δ18O quartz-feldspar pairs from these granitoids, which

  8. Diets and environments of late Cenozoic mammals in the Qaidam Basin, Tibetan Plateau: Evidence from stable isotopes

    Science.gov (United States)

    Zhang, Chunfu; Wang, Yang; Li, Qiang; Wang, Xiaoming; Deng, Tao; Tseng, Zhijie J.; Takeuchi, Gary T.; Xie, Gangpu; Xu, Yingfeng

    2012-06-01

    The timing history and driving mechanisms of C4 expansion and Tibetan uplift are hotly debated issues. Paleoenvironmental evidence from within the Tibetan Plateau is essential to help resolve these issues. Here we report results of stable C and O isotope analyses of tooth enamel samples from a variety of late Cenozoic mammals, including deer, giraffe, horse, rhino, and elephant, from the Qaidam Basin in the northeastern Tibetan Plateau. The enamel-δ13C values are rhino (CD0722, with δ13C values up to -4.1‰). If the Qaidam Basin was as arid as today in the Mio-Pliocene, these data would indicate that the majority of the animals had C3 diets and only a few individuals (besides the exceptional rhino CD0722) may have consumed some C4 plants. Based on geological evidence, however, the Qaidam Basin was probably warmer and more humid during the late Miocene and early Pliocene than today. Thus, these δ13C values likely indicate that many individuals had significant dietary intakes of C4 plants, and the Qaidam Basin had more C4 plants in the late Miocene and early Pliocene than today. Moreover, the Qaidam Basin likely had much denser vegetation at those times in order to support such large mammals as rhinos and elephants. While the δ18O values did not increase monotonously with time, the range of variation seems to have increased considerably since the early Pliocene, indicating increased aridification in the basin. The mean δ18O values of large mammals and those reconstructed for local meteoric waters display a significant negative shift in the late Miocene, consistent with the marine δ18O record which shows a cooling trend in the same period. Taken together, the isotope data suggest a warmer, wetter, and perhaps lower Qaidam Basin during the late Miocene and early Pliocene. Increased aridification after the early Pliocene is likely due to a combined effect of regional tectonism, which resulted in a more effective barrier preventing moisture from the Indian Ocean

  9. Estimating the contribution of the authigenic mineral component to the long-term reactive silica accumulation on the western shelf of the Mississippi River Delta

    Science.gov (United States)

    Presti, Massimo; Michalopoulos, Panagiotis

    2008-04-01

    Previous studies have shown how biogenic silica particles undergo conversion to aluminosilicate phases in large tropical deltaic systems, thus affecting the world ocean budget of major seawater cations. This study tackles the important question of the silica budget in the coastal zone of the Mississippi River Delta, providing evidence for the role of biogenic silica diagenesis in this subtropical system from direct examination of individual diatom particles, sediment leachates and pore-water composition. The estimated reactive silica stored in the study area (5990 km 2) is based on operational leaches that account for altered biogenic silica particles and other authigenic aluminosilicate phases in addition to fresh biogenic silica. Early diagenesis of silica in the delta front occurs mainly where more siliceous material is deposited. An inner-shelf area, where hypoxic conditions are found, significantly contributes to the formation of authigenic products of Si alteration. Data suggest that the limiting factor of silica alteration processes is the availability of detrital phases such as Al and Fe. The estimated total reactive silica accumulation in the study area is 1.45×10 10 mol Si year -1, representing ˜2.2% of the long-term bulk sediment accumulation. On the basis of a conservative appraisal, the authigenic mineral components account for ˜40% of the long-term reactive silica storage. This study shows that non-tropical deltaic systems are significantly more important sinks of silica than previously thought and that, where conditions are favourable, a consistent portion of reactive silica not leaving the shelf is stored within the delta in the form of authigenic components.

  10. Non-occupational exposure to silica dust

    Directory of Open Access Journals (Sweden)

    L J Bhagia

    2012-01-01

    Full Text Available Occupational exposure to silica occurs at workplaces in factories like quartz crushing facilities (silica flour milling, agate, ceramic, slate pencil, glass, stone quarries and mines, etc., Non-occupational exposure to silica dust can be from industrial sources in the vicinity of the industry as well as non-industrial sources. Recently, public concern regarding non-occupational or ambient exposure to crystalline silica has emerged making it important to gather information available on non-occupational exposures to silica dust and non-occupational silicosis. This paper reviews various non-occupational exposures reported in literature including some studies by the author. Methodology used in assessment of non-occupational exposures, standards for non-occupational exposures to silica dust and indirect estimation of cumulative risk % are also discussed.

  11. Preparation of polystyrene/silica nanocomposites by radical copolymerization of styrene with silica macromonomer

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    A two-stage process has been developed to generate the silica-based macromonomer through surface-modification of silica with polymerizable vinyl groups. The silica surfaces were treated with excess 2,4-toluene diisocynate (TDI), after which the residual isocyanate groups were converted into polymerizable vinyl groups by reaction with hydroxypropylacrylate (HPA). Thus, polystyrene/silica nanocomposites were prepared by conventional radical copolymerization of styrene with silica macromonomer. The main effecting factors, such as ratios of styrene to the macromonomer, together with polymerization time on the copolymerization were studied in detail. FTIR, DSC and TGA were utilized to characterize the nanocomposites. Experimental results revealed that the silica nanoparticles act as cross-linking points in the polystytene/silica nanocomposites, and the glass transition temperatures of the nanocomposites are higher than that of the corresponding pure polystyrene. The glass transition temperatures of nanocomposites increased with the increasing of silica contents, which were further ascertained by DSC.

  12. K—Ar Geochronology and Evolution of Cenozoic Volcanic Rocks in Eastrn China

    Institute of Scientific and Technical Information of China (English)

    王慧芬; 杨学昌; 等

    1989-01-01

    Cenozoic volcanic rocks widespread in eastern China constitute an important part of the circum-Pacific volcanic belt.This paper presents more than 150K-Ar dates and a great deal of petrochemical analysis data from the Cenozoic volcanic rocks distributed in Tengchong,China's southeast coast,Shandong,Hebei,Nei Monggol and Northeast China.An integrated study shows that ubiquitous but uneven volcanic activities prevailed from the Eogene to the Holocene,characterized as being multi-eqisodic and multicycled.For example,in the Paleocene(67-58Ma),Eocene(57-37.5Ma),Miocene(22-18,16-19Ma),Pliocene(8-3Ma),and Early Pleistocene-Middle Pleistocene(1.2-0.5Ma) there were upsurges of volcanism,while in the Oligocene there was a repose period.In space,the older Eogene volcanic rocks are distributed within the region or in the central part of the NE-NNE-striking fault depression,while the younger Neogene and Quaternary volcanic rocks are distributed in the eastern and western parts.Petrologically,they belong essentially to tholeiite-series and alkali-series basalts,with alkalinity in the rocks increasing from old to youg.The above regularities are controlled by both global plate movement and regional inherent tectonic pattern.

  13. Meso-Cenozoic evolution of the Tuareg Shield (Algeria, Sahara): insights from new thermochronological data

    Science.gov (United States)

    Rougier, Sylvain; Missenard, Yves; Gautheron, Cécile; Barbarand, Jocelyn; Zeyen, Hermann; Pinna, Rosella; Liégeois, Jean-Paul; Bonin, Bernard; Ouabadi, Aziouz; El-Messaoud Derder, Mohammed; Frizon de Lamotte, Dominique; Kettouche, Djouher

    2013-04-01

    In North Africa, Meso-Cenozoic large scale topographic swells, such as Hoggar, Tibesti or Darfur domes, are superimposed to a Paleozoic arch and basin morphology which characterizes this region. Although these topographic highs are associated to Cenozoic intraplate volcanism, their development remains poorly constrained, both from temporal and spatial points of view. This study is focused on the Tuareg Shield bulge, a topographic high where Precambrian rocks, exposed over 500000 km², can reach 2400 m above sea level (Atakor district, Hoggar, South Algeria). While presumed Cretaceous sedimentary remnants, resting unconformably over the basement, suggest a possible stage of weak topography during the Mesozoic, current high topography is emphasized by time-temperature history were performed. As previously deduced from apatite (U-Th)/He analyzes, these modelings show that samples underwent a heating to at least 80°C before their Late Eocene exhumation. Moreover, they also indicate that samples underwent another cooling stage during Lower Cretaceous, prior to Upper Cretaceous/Paleogene heating. We interpret these results as an evidence of a large-scale subsidence stage after the Cretaceous and until the Eocene, which allowed the deposition of a 1.5 to 3 km thick sedimentary cover and a heating at ~80°C of the currently outcropping basement. During the Eocene, the establishment of a thermal anomaly beneath the Tuareg Shield lithosphere resulted in erosion of the major part of this cover and, since 35 Ma, the development of intraplate volcanism.

  14. On tectonic movement in the South China Sea during the Cenozoic

    Institute of Scientific and Technical Information of China (English)

    LIN Changsong; CHU Fengyou; GAO Jinyao; TAN Yonghua

    2009-01-01

    The tectonic movement taking place at the end of Cretaceous and the beginning of Cenozoic had opened the Ce-nozoic phase of polycyclic tectonic movements, then the whole crust of the South China Sea had been mainly subjected to the regional stress field of tectonic tension, which was characterized by rifting depression. Seven times of regional tectonic movement and sedimentation had been assembled into a geological development history of polycyclic oscillation. Especially, the tectonic movements were strongly intensified at the end of Cretacious and the beginning of Paleagene, between Late Eocene and Mid-Oligocene, during Mid- and Late Miocene. These three times of tectonic movement had built the most important regional tectonic interfaces in the South China Sea. Crust movements of the South China Sea were the result and epitome of interaction of the Eurasia, Pacific and Indo-Australia plates, that is, they were introduced by polycyclic changes of directions, rates and strengths of lithospheric movements and asthenospheric flows across the Pacific and Indo-Australia plates.

  15. The uplifting process of the Bogda Mountain during the Cenozoic and its tectonic implication

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The Tianshan Mountains have undergone its initial orogeny, extension adjusting and re-orogeny since the Late Paleozoic. The re-orogeny and uplifting process of the orogeny in the Mesozoic and Cenozoic are two of most important events in the geological evolution of Euro-Asian continent, which resulted in the formation of the present range-and-basin pattern in topography of the Tianshan Mountains and its adjacent areas. Thermochronology results by the method of fission-track dating of apatite suggest three obvious uplifting stages of the Bogad Mountain Chain re-orogeny during the Cenozoic, i.e. 5.6-19 Ma, 20-30 Ma, and 42-47 Ma. The strongest uplifting stage of the mountain is the second one at 20 -30 Ma, when the mountain uplifted as a whole, and the beginning of re-orogeny was no less than 65 Ma. Furthermore, our studies also show that the uplifting types of the mountain are variable in the dif-ferent time periods, including uplifting of mountain as a whole and differential uplifting. The apparently diversified uplifting processes of the mountain chain are characterized by the migration (or transfor-mation) of the uplifting direction of the mountain from west to east and from north to south, and the main process of mountain extending is from north to south.

  16. The uplifting process of the Bogda Mountain during the Cenozoic and its tectonic implication

    Institute of Scientific and Technical Information of China (English)

    WANG ZongXiu; LI Tao; ZHANG Jin; LIU YongQing; MA ZongJin

    2008-01-01

    Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China The Tianshan Mountains have undergone its initial orogeny, extension adjusting and re-orogeny since the Late Paleozoic. The re-orogeny and uplifting process of the orogeny in the Mesozoic and Cenozoic are two of most important events in the geological evolution of Euro-Asian continent, which resulted in the formation of the present range-and-basin pattern in topography of the Tianshan Mountains and its adjacent areas. Thermochronology results by the method of fission-track dating of apatite suggest three obvious uplifting stages of the Bogad Mountain Chain re-orogeny during the Cenozoic, i.e. 5.6-19 Ma, 20-30 Ma, and 42-47 Ma. The strongest uplifting stage of the mountain is the second one at 20-30 Ma, when the mountain uplifted as a whole, and the beginning of re-orogeny was no less than 65Ma. Furthermore, our studies also show that the uplifting types of the mountain are variable in the different time periods, including uplifting of mountain as a whole and differential uplifting. The apparently diversified uplifting processes of the mountain chain are characterized by the migration (or transformation) of the uplifting direction of the mountain from west to east and from north to south, and the main process of mountain extending is from north to south.

  17. Progress and outlook of uranium exploration in meso-cenozoic basins in north China

    International Nuclear Information System (INIS)

    Through the efforts in last decades on the research of geology setting and regional assessment for uranium exploration in the Meso-Cenozoic basins in North China, rich accomplishment have been gotten in metallogenic theory, temporal and spatial distribution pattern, zone division, Classification, mineralization of different type, ore-controlling factors, metallogenic model, principle of valuation and prognostication, exploration criteria and great breakthrough in the prospecting of key areas. However, the extensive territory make the effort limited only to some region, the exploration level is fairly lower in the whole country, and there is wide space for uranium exploration. The further exploration should be basically guided by 'highlighting the exploration of key areas, strengthening the evaluation of regional potential and accelerating the implementation of new reserve bases' and persisted in principle of 'deployment with different level and execution according to region' and oriented with different types of deposit by 'wholly evaluation and systematic exploration'. By deploying the new effort frame in large base exploration, regional evaluation and solving the important geological and geophysical problem, we can put forward the uranium exploration in Meso-Cenozoic basins in North China. (author)

  18. Late cenozoic magmatism in the South Patagonian batholith: SHRIMP U-Pb zircon age evidence

    International Nuclear Information System (INIS)

    The North Patagonian Batholith (NPB) has a zonal age pattern which includes a well defined belt of Miocene and Mio-Pliocene plutons in its central portion (Pankhurst et al., 1999) which are spatially, and probably genetically related to the Liquine-Ofqui Fault Zone. Previous geochronological studies in the Southern Patagonian Batholith (SPB), as summarized by Bruce et al. (1991), have yielded 9 late Cenozoic K-Ar or Ar-Ar ages out of a total of 116 age determinations. None of these young ages correspond to U-Pb determinations on zircons, and some of the young ages correspond to satellite plutons east of the SPB proper, such as the Torres del Paine intrusion. In this paper we present the first late Cenozoic SHRIMP U-Pb zircon ages in the area of the SPB. The morphology of the analysed zircon crystals is described and leads to some inferences on the methodology and on the geological interpretation of the obtained ages (au)

  19. Cenozoic back-arc magmatism of the southern extra-Andean Patagonia (44° 30' - 52° S: A review of geochemical data and geodynamic interpretations Magmatismo de retroarco cenozoico de la Patagonia extra-andina austral (44° 30' - 52° S: Una revisión de los datos geoquímicos e interpretaciones geodinámicas

    Directory of Open Access Journals (Sweden)

    M. D'Orazio

    2004-12-01

    Full Text Available Huge amounts of basaltic s.l. lavas were persistently erupted along the eastern side of the Andean Cordillera, throughout Cenozoic time, forming extensive plateaus, hundreds of monogenetic scoria cones and other volcanic structures in a continental back-arc setting. The igneous products exposed in the southern sector of the extra-Andean Patagonia (44° 30' - 52° S are dominantly mafic with minor slightly evolved compositions and rare highly differentiated products. The many published chemical analyses of these rocks, indicate that the mafic lavas range from strongly silica - undersaturated basanites to oversaturated basaltic andesites, and that most of the lavas have a typical within-plate geochemical signature. However, a number of lavas, generally erupted in the western-central sectors of Patagonia, are characterized by different distributions of the incompatible elements with high LILE/HFSE and LREE/HFSE ratios. The REE distribution modelling suggests a low degree of melting of a deep (> 70 km garnet-bearing source for the alkaline magmas, and a higher degree of melting of the same source, or an even higher degree of melting of an enriched source, for the subalkaline magmas. The available Sr-Nd-Pb isotope compositions clearly attest to a major geographic variation: the southernmost lavas have lower 87Sr/86Sr and higher 143Nd/144Nd and 206Pb/204Pb ratios with respect to those erupted to the north. On the whole, the Sr-Nd-Pb isotope compositions of the southern Patagonia lavas fall within the typical range of within-plate continental magmas; in addition the Pb isotope ratios fall in the range of the Southern Hemisphere Dupal Pb isotope anomaly. The geochemical variations of the southern Patagonia lavas are discussed in terms of different geochemical components: depleted and enriched sub-slab asthenosphere, enriched continental lithospheric mantle, continental crust and subducted materials. The geodynamic significance is interpreted with in the

  20. Silica-based cationic bilayers as immunoadjuvants

    OpenAIRE

    Carmona-Ribeiro Ana M; da Costa Maria; Faquim-Mauro Eliana; Santana Mariana RA; Lincopan Nilton

    2009-01-01

    Abstract Background Silica particles cationized by dioctadecyldimethylammonium bromide (DODAB) bilayer were previously described. This work shows the efficiency of these particulates for antigen adsorption and presentation to the immune system and proves the concept that silica-based cationic bilayers exhibit better performance than alum regarding colloid stability and cellular immune responses for vaccine design. Results Firstly, the silica/DODAB assembly was characterized at 1 mM NaCl, pH 6...

  1. Mesoporous Silica from Rice Husk Ash

    OpenAIRE

    V.R. Shelke; S.S. Bhagade; S.A. Mandavgane

    2011-01-01

    Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as a concrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc. Sodium silicate is produced by reacting rice hull ash (RHA) with aqueous NaOH and silica is precipitated from the sodium silicate by acidification. In the present work, conversion of about 90% of silica contained in RHA into sodium silicate was achieved in an open system at temperatures...

  2. Process for preparing polymer reinforced silica aerogels

    Science.gov (United States)

    Meador, Mary Ann B. (Inventor); Capadona, Lynn A. (Inventor)

    2011-01-01

    Process for preparing polymer-reinforced silica aerogels which comprises a one-pot reaction of at least one alkoxy silane in the presence of effective amounts of a polymer precursor to obtain a silica reaction product, the reaction product is gelled and subsequently subjected to conditions that promotes polymerization of the precursor and then supercritically dried to obtain the polymer-reinforced monolithic silica aerogels.

  3. Influence of Silica Fume on Normal Concrete

    OpenAIRE

    Debabrata Pradhan

    2013-01-01

    The incorporation of silica fume into the normal concrete is a routine one in the present days to produce the tailor made high strength and high performance concrete. The design parameters are increasing with the incorporation of silica fume in conventional concrete and the mix proportioning is becoming complex. The main objective of this paper has been made to investigate the different mechanical properties like compressive strength, compacting factor, slump of concrete incorporating silica ...

  4. Studying ocean acidification in the Arctic Ocean

    Science.gov (United States)

    Robbins, Lisa

    2012-01-01

    The U.S. Geological Survey (USGS) partnership with the U.S. Coast Guard Ice Breaker Healey and its United Nations Convention Law of the Sea (UNCLOS) cruises has produced new synoptic data from samples collected in the Arctic Ocean and insights into the patterns and extent of ocean acidification. This framework of foundational geochemical information will help inform our understanding of potential risks to Arctic resources due to ocean acidification.

  5. Evidence for the Mesozoic and Cenozoic Evolution of the Lithosphere in the Trans-European Suture Zone from Surface Wave Tomography

    Science.gov (United States)

    Meier, Thomas; Soomro, Riaz; Lebedev, Sergei; Weidle, Christian; Viereck, Lothar; Behrmann, Jan; Cristiano, Luigia; Hanemann, Ricarda

    2016-04-01

    The Trans-European Suture Zone marks the transition between the East European Craton and Phanerozoic central Europe. Subduction of the Thor ocean and collision of Avalonia resulted in a Caledonian terrane assemblage that has been strongly affected by Permian volcanism, sedimentation in Post-Permian basins and recently by Cenozoic inversion tectonics. Whereas the structure of the crust in the area has been extensively studied by Deep Seismic Soundings, properties of the subcontinental mantle lithosphere are less well known. Surface waves are well suited to study the structure of the lithosphere and the sublithospheric mantle being mainly sensitive to the S-wave velocity structure at those depths. It has been shown before that the Tornquist-Teisseyre Zone representing the boundary to the East-European Craton in the southwest of the Trans-European Suture Zone is associated with a sharp transition between thick cratonic lithosphere in the northeast and thinner lithosphere to the southwest. Here we present results of a tomographic surface wave study based on automated broad-band measurements of average inter-station Rayleigh wave phase velocities providing higher resolution especially at lithospheric depths. All available broad-band recordings including data of temporary deployments like the TOR and PASSEQ experiments have been processed. At shorter periods phase velocities are sensitive to the sedimentary basins providing a 3D image of average shear-wave velocities. At intermediate periods differences in the crustal thickness and the structure of the uppermost mantle in the regions of the North German Basin and the Polish Basin become obvious. The latter is characterized by larger crustal thickness and rather low sub-Moho S-wave velocities. Also, lithospheric thickness varies along the Trans-European Suture Zone. In the region of the Sorgenfrei-Tornquist Zone a rather gradual decrease of lithospheric thickness towards central Europe is observed, whereas a shallow

  6. Hydrophobic transition in porous amorphous silica

    International Nuclear Information System (INIS)

    Realistic models of amorphous silica surfaces with different silanol densities are built using Monte Carlo annealing. Water-silica interfaces are characterized by their energy interaction maps, adsorption isotherms, self-diffusion coefficients, and Poiseuille flows. A hydrophilic to hydrophobic transition appears as the surface becomes purely siliceous. These results imply significant consequences for the description of surfaces. First, realistic models are required for amorphous silica interfaces. Second, experimental amorphous silica hydrophilicity is attributed to charged or uncharged defects, and not to amorphousness. In addition, auto irradiation in nuclear waste glass releases hydrogen atoms from silanol groups and can induce such a transition. (authors)

  7. Airborne silica levels in an urban area

    International Nuclear Information System (INIS)

    In order to evaluate the exposure levels of the general population we studied the concentrations of silica particles in the inhalable particulate fraction (PM10) in different meteorological-climate periods in an urban area of Rome. In order to determine the concentration and the granulometric spectrum of silica particles, PM10 sampled by a cascade impactor was analysed by X-ray diffractometry (XRD) and by scanning electron microscopy equipped with a thin-window system for X-ray microanalysis (SEM/EDX). Over the period September 2004-October 2005 the abundance of silica particles as evaluated by SEM/EDX ranged from 1.6 to 10.4% of the total PM10 particulate, with a weight concentration of free crystalline silica, evaluated by XRD, in the range 0.25-2.87 μg/m3. The mean diameter of silica particles ranged from 0.3 to 10.5 μm, with more than 87% of particles having a diameter of less than 2.5 μm. The correlations between SEM/EDX and XRD data seem to suggest that the airborne silica particles in the urban location studied were mainly in the form crystalline silica. A strong relationship was found between the meteorological-climate conditions and the concentration level of free crystalline silica. This result suggests that the Southern winds from the Sahara desert carry an important amount of silica particles into Mediterranean Europe

  8. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  9. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm;

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  10. Future scientific drilling in the Arctic Ocean: Key objectives, areas, and strategies

    Science.gov (United States)

    Stein, R.; Coakley, B.; Mikkelsen, N.; O'Regan, M.; Ruppel, C.

    2012-04-01

    In spite of the critical role of the Arctic Ocean in climate evolution, our understanding of the short- and long-term paleoceanographic and paleoclimatic history through late Mesozoic-Cenozoic times, as well as its plate-tectonic evolution, remains behind that from the other world's oceans. This lack of knowledge is mainly caused by the major technological/logistic problems in reaching this permanently ice-covered region with normal research vessels and in retrieving long and undisturbed sediment cores. With the Arctic Coring Expedition - ACEX (or IODP Expedition 302), the first Mission Specific Platform (MSP) expedition within IODP, a new era in Arctic research began (Backman, Moran, Mayer, McInroy et al., 2006). ACEX proved that, with an intensive ice-management strategy, successful scientific drilling in the permanently ice-covered central Arctic Ocean is possible. ACEX is certainly a milestone in Arctic Ocean research, but - of course - further drilling activities are needed in this poorly studied ocean. Furthermore, despite the success of ACEX fundamental questions related to the long- and short-term climate history of the Arctic Ocean during Mesozoic-Cenozoic times remain unanswered. This is partly due to poor core recovery during ACEX and, especially, because of a major mid-Cenozoic hiatus in this single record. Since ACEX, a series of workshops were held to develop a scientific drilling strategy for investigating the tectonic and paleoceanographic history of the Arctic Ocean and its role in influencing the global climate system: - "Arctic Ocean History: From Speculation to Reality" (Bremerhaven/Germany, November 2008); - "Overcoming barriers to Arctic Ocean scientific drilling: the site survey challenge" (Copenhagen/Denmark, November 2011); - Circum-Arctic shelf/upper continental slope scientific drilling workshop on "Catching Climate Change in Progress" (San Francisco/USA, December 2011); - "Coordinated Scientific Drilling in the Beaufort Sea: Addressing

  11. HEALTH EFFECTS OF INHALED CRYSTALLINE AND AMORPHOUS SILICA

    Science.gov (United States)

    Recently, public concern regarding nonoccupational or ambient silica exposure, mainly to crystalline silica, has emerged making it important to evaluate background and ambient concentrations. Ambient emissions of silica rarely are estimated or measured in air pollution studies of...

  12. Catalogue of the Mesozoic and Cenozoic holotypes in the collection of plant fossils in the Nationaal Natuurhistorisch Museum, Leiden

    NARCIS (Netherlands)

    Konijnenburg-van Cittert, van J.H.A.; Waveren, van I.M.; Jonckers, J.B.

    2004-01-01

    This is an inventory of the Mesozoic and Cenozoic type material in the original palaeobotanical collections of the Nationaal Natuurhistorisch Museum, Leiden, The Netherlands. In total 60 holotypes are documented and one is noted as missing from the collections. One new combination is made (Cinnamomu

  13. Elastic properties of silica-silica continuous fibre-reinforced, ceramic matrix composites

    International Nuclear Information System (INIS)

    Ambient and elevated temperature elastic properties of silica-silica ceramic fibre-reinforced, ceramic-matrix composites (silica-silica CFCCs), obtained using resonance beam technique, have been reported and discussed. The composite exhibits in-plane isotropy and through-thickness anisotropy in the elastic properties at ambient temperatures and increasing elastic moduli with increasing test temperature. The latter results are attributable to the change in the nature of atomic bonding of the silica material up to about 1173 K and further increase in moduli with temperature is due to the combined effects of devitrification and densification due to sintering

  14. Late cenozoic tectonic and geomorphic evolution of the Patagonian Andes between 42oS and 52oS, southern Chile assessed using fission-track thermochronology

    International Nuclear Information System (INIS)

    Fission-track (FT) analysis has been applied in the Patagonian Andes of southern Chile to assess the late Cenozoic geomorphic and tectonic response of the overriding plate to subduction of the Chile rise active oceanic spreading centre (Thomson et al., 2001). The timing and nature of tectonic uplift and denudation along the southern parts of the major transpression intra-arc Liquine-Ofqui fault (LOF) system have also been investigated (Thomson, 2001, submitted). Results from 130 FT ages (72 zircon and 58 apatite ages) and 39 apatite track length measurements reveal initiation of rapid cooling and denudation at ca. 30 Ma at the western margin of southern continental South America. This was followed by a ca. 200km eastward migration of the locus of maximum denudation to the position of the present day topographic divide between ca. 30 Ma and ca. 12 to 10 Ma. East of the Andean divide less than 3 km of denudation has occurred since the Late Cretaceous. Enhanced denudation is interpreted to be the result of increased tectonic uplift driven by a large increase in convergence rates at ca. 28 to 26 Ma that triggered orographically enhanced precipitation on the west-side of the Patagonian Andes allowing increased erosion by fluvial incision and mass transport processes. The eastward migration of the locus of maximum denudation can be related to either coeval eastward migration of the retro-arc deformation front, the effects of subduction erosion in the overriding plate at the Peru-Chile trench or shallowing of the angle of subduction. Away from the influence of the LOF the process of spreading centre subduction and collision itself coincides with an overall slow-down in denudation rates in the overriding plate most likely caused by a major reduction in the main tectonic force driving tectonic uplift in the upper plate to subduction. In contrast to the Andes south of ca. 46oS, increased cooling and denudation related to transpression induced rock uplift and erosion along

  15. Nanoscale control of silica particle formation via silk-silica fusion proteins for bone regeneration.

    Science.gov (United States)

    Mieszawska, Aneta J; Nadkarni, Lauren D; Perry, Carole C; Kaplan, David L

    2010-10-26

    The biomimetic design of silk/silica fusion proteins was carried out, combining the self assembling domains of spider dragline silk (Nephila clavipes) and silaffin derived R5 peptide of Cylindrotheca fusiformis that is responsible for silica mineralization. Genetic engineering was used to generate the protein-based biomaterials incorporating the physical properties of both components. With genetic control over the nanodomain sizes and chemistry, as well as modification of synthetic conditions for silica formation, controlled mineralized silk films with different silica morphologies and distributions were successfully generated; generating 3D porous networks, clustered silica nanoparticles (SNPs), or single SNPs. Silk serves as the organic scaffolding to control the material stability and multiprocessing makes silk/silica biomaterials suitable for different tissue regenerative applications. The influence of these new silk-silica composite systems on osteogenesis was evaluated with human mesenchymal stem cells (hMSCs) subjected to osteogenic differentiation. hMSCs adhered, proliferated, and differentiated towards osteogenic lineages on the silk/silica films. The presence of the silica in the silk films influenced osteogenic gene expression, with the upregulation of alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen type 1 (Col 1) markers. Evidence for early bone formation as calcium deposits was observed on silk films with silica. These results indicate the potential utility of these new silk/silica systems towards bone regeneration. PMID:20976116

  16. Biomimetic silica encapsultation of living cells

    Science.gov (United States)

    Jaroch, David Benjamin

    Living cells perform complex chemical processes on size and time scales that artificial systems cannot match. Cells respond dynamically to their environment, acting as biological sensors, factories, and drug delivery devices. To facilitate the use of living systems in engineered constructs, we have developed several new approaches to create stable protective microenvironments by forming bioinspired cell-membrane-specific silica-based encapsulants. These include vapor phase deposition of silica gels, use of endogenous membrane proteins and polysaccharides as a site for silica nucleation and polycondensation in a saturated environment, and protein templated ordered silica shell formation. We demonstrate silica layer formation at the surface of pluripotent stem-like cells, bacterial biofilms, and primary murine and human pancreatic islets. Materials are characterized by AFM, SEM and EDS. Viability assays confirm cell survival, and metabolite flux measurements demonstrate normal function and no major diffusion limitations. Real time PCR mRNA analysis indicates encapsulated islets express normal levels of genetic markers for β-cells and insulin production. The silica glass encapsulant produces a secondary bone like calcium phosphate mineral layer upon exposure to media. Such bioactive materials can improve device integration with surrounding tissue upon implantation. Given the favorable insulin response, bioactivity, and long-term viability observed in silica-coated islets, we are currently testing the encapsulant's ability to prevent immune system recognition of foreign transplants for the treatment of diabetes. Such hybrid silica-cellular constructs have a wide range of industrial, environmental, and medical applications.

  17. Active and passive silica waveguide integration

    DEFF Research Database (Denmark)

    Hübner, Jörg; Guldberg-Kjær, Søren Andreas

    2001-01-01

    circuits in existing and future networks without affecting the power budget of the system. Silica on silicon technology offers a unique possibility to selectively dope sections of the integrated circuit with erbium where amplification is desired. Some techniques for active/passive integration are reviewed...... and a silica on silicon based approach is discussed in more detail....

  18. Refractive index dispersion law of silica aerogel

    International Nuclear Information System (INIS)

    This paper presents measurements of the refractive index of a hygroscopic silica aerogel block at several wavelengths. The measurements, performed with a monochromator, have been compared with different parameterisations for n(λ), in order to determine the best chromaticity law for the aerogel. This is an important input for design and operation of RICH detectors with silica aerogel radiator. (orig.)

  19. Performance of silica aerogel threshold Cerenkov counters

    International Nuclear Information System (INIS)

    Results from a series of test beam measurements are presented for a two-cell silica aerogel Cerenkov counter system. The main achievement is the detection of 13±1 photoelectrons in a full-sized n=1.008 silica aerogel cell which is read out with a fine mesh photomultiplier in different magnetic fields up to 1.35T. (orig.)

  20. Structure of random porous materials: Silica aerogel

    International Nuclear Information System (INIS)

    Using small-angle x-ray scattering, we show that porous silica aerogel has a fractal backbone structure. The observed structure is traced to the underlying chemical (polymerization) and physical (colloid aggregation) growth processes. Comparison of scattering curves for aerogel with silica aggregates confirms this interpretation

  1. Ocean Uses: California

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This Ocean Uses Atlas Project is an innovative partnership between NOAA's National Marine Protected Areas Center and Marine Conservation Biology Institute. The...

  2. California Ocean Uses Atlas

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset is a result of the California Ocean Uses Atlas Project: a collaboration between NOAA's National Marine Protected Areas Center and Marine Conservation...

  3. Ocean Acidification Product Suite

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Scientists within the ACCRETE (Acidification, Climate, and Coral Reef Ecosystems Team) Lab of AOML_s Ocean Chemistry and Ecosystems Division (OCED) have constructed...

  4. Ocean Sediment Thickness Contours

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ocean sediment thickness contours in 200 meter intervals for water depths ranging from 0 - 18,000 meters. These contours were derived from a global sediment...

  5. Ocean acoustic reverberation tomography.

    Science.gov (United States)

    Dunn, Robert A

    2015-12-01

    Seismic wide-angle imaging using ship-towed acoustic sources and networks of ocean bottom seismographs is a common technique for exploring earth structure beneath the oceans. In these studies, the recorded data are dominated by acoustic waves propagating as reverberations in the water column. For surveys with a small receiver spacing (e.g., tomography, is developed that uses the travel times of direct and reflected waves to image ocean acoustic structure. Reverberation tomography offers an alternative approach for determining the structure of the oceans and advancing the understanding of ocean heat content and mixing processes. The technique has the potential for revealing small-scale ocean thermal structure over the entire vertical height of the water column and along long survey profiles or across three-dimensional volumes of the ocean. For realistic experimental geometries and data noise levels, the method can produce images of ocean sound speed on a smaller scale than traditional acoustic tomography. PMID:26723303

  6. FABRICATION AND CHARACTERATION OF NANOPOROUS SILICA FILM

    Institute of Scientific and Technical Information of China (English)

    殷明志; 张良莹; 姚熹

    2003-01-01

    Colloidal silica sol is formed by a novel hydrolyzing procedure of tetraethyl-orthosilicate(TEOS) catalyzing with NH3*H2O in aqueous mediums. Glycerol, combining with the hydrolyzed intermediates of TEOS, controls growing of the silica particles; poly(vinyl-vinyl alcohol makes the colloidal silica sol with polymeric structure and spinning, thermal strain makes the gel silica film changed into a nanoporous structure with diameter ranging 50-150 nm. Morphologies of the nanoporous silica film have been characterized; the porosities (%) is 32-64; the average dielectric constant at 1MHz region is 2.0 and 2.1; the thermal conductivity is less than 0.8. Chemical mechanism of the sol-gel process is discussed.

  7. The Pozzolanic reaction of silica fume

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2012-01-01

    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the...... present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy of...... activation of the pozzolanic reaction of silica fume is estimated. The results show that the pozzolanic reaction of silica fume has notable differences from Portland cement hydration....

  8. Raman spectrum and structure of silica aerogel

    International Nuclear Information System (INIS)

    Raman spectra have been obtained from silica aerogel, a porous low-density material having grain sizes near 70 A. The Raman spectra are qualitatively similar to those from fused silica, thus indicating that the aerogel is amorphous. However, a greatly intensified peak (relative to ordinary fused silica) occurs near 478 cm-1 and is assigned to small rings, e.g., six (3-SiO) or eight (4-SiO) membered. Such rings may be more important in the aerogel than in fused silica, but the observed absence of the 600 cm-1 ring peak indicates that only one ring type, e.g., eight membered, is predominant. Other marked frequency and intensity changes in the Si--O--Si bending and Si--O stretching region, compared to fused silica, were also observed

  9. Mesozoic-Cenozoic thermal history of Turpan-Hami Basin: apatite fission track constraints

    Institute of Scientific and Technical Information of China (English)

    ZHU Wenbin; WAN Jinglin; SHU Liangshu; SUN Yan; GUO Jichun; WANG Feng

    2005-01-01

    Apatite fission track dating is carried out on nine samples collected from the central part (Lianmuqin section) and from both northern and southern margins of Turpan-Hami Basin. The fission-track ages of seven Jurassic samples are distinctly younger than depositional ages. In contrast, the fission-track ages of two Cretaceous samples are older than, or as old as depositional ages. These observations indicate that the Jurassic samples have been annealed or partially annealed, whereas the Cretaceous samples have not been annealed.The further thermal modelling results show that Turpan-Hami Basin experienced a Late Cretaceous period (120-100 Ma) of tectonic uplift with rapid cooling and exhumation of sediments. The samples underwent a Cenozoic period of reburial and re-heating and were exhumed again at 10-8 Ma.

  10. ESR dating of late Cenozoic molassic deposits in the Jiuxi Basin

    Institute of Scientific and Technical Information of China (English)

    史正涛; 业渝光; 赵志军; 方小敏; 李吉均

    2001-01-01

    In the Hexi Corridor, foreland depression at the north periphery of the Tibetan Plateau, late Cenozoic sediments can be divided into the lacustrine to deltaic Red Bed. The unconformably overlying coarse fan-conglomerate was shed from the northern plateau. This remarkable alternation of sedimentary environment and discontinuity reflect intensive rise of the plateau. Moreover, this suite of coarse molasses is divided into two formations as the Yumen conglomerate and the Jiuquan Gravel by another angular discontinuity. Tentatively, we applied ESR dating on this suite of molassic deposits at the Laojunmiao Section in the Jiuxi Basin, west of the Hexi Corridor, which shows that the bottom of the Yumen conglomerate and the Jiuquan Gravel are about 3.4 and 0.9 Ma respectively, indicating that the northern plateau at least experienced two intensive tectonic movements at about 3.5 and 0.9 Ma.

  11. Thermal structure research on cenozoic in Songliao basin and Daxinganling Mountain

    International Nuclear Information System (INIS)

    Thermal history simulation of Apatite Fission Track shows the thermal structure history in Cenozoic and the relationship between Songliao Basin and Daxinganling Mountain. Uplift of Daxinganling reveals its act character; its velocity shows 5 decreasing phases and 4 increasing ones. Although basin evolvement is quite complex, it behaved as three uplifts and two sedimentations. It is considered here that the relationship between Songliao Basin and Daxinganling includes three styles and 4 phases, that is, basin uplifted with mountain during 65.5-50 Ma; basin subsided while mountain uplifted slowly and basin uplifted rapidly while mountain uplifted rapidly during 50-36 Ma; basin subsided slowly while mountain uplifted slowly and basin subsided rapidly while mountain uplifted rapidly during 36-5.83 Ma; the latest phase was the same with the first one. (authors)

  12. Structural Evolution of the Eastern Margin of Eurasia in Late Mesozoic and Cenozoic

    Institute of Scientific and Technical Information of China (English)

    A. P. Sorokin; T. V. Artyomenko

    2003-01-01

    This paper features the structural evolution of the eastern margin of Eurasia in Late Mesozoic and Cenozoic.It is characterized by three stages of development: the riftogenic stage (Jurassic-Early Cretaceous), the platform stage (Late Cretaceous) and the neotectonic one (Paleogene-Quarternary). The boundaries between these stages are distinctly fixed by the geological time limits of planetary range. It is demonstrated that the riftogenic and neotectonic stages were characterized by a high degree of geodynamic activity, and the platform one by a decrease in contrast of tectonic movements. The main river net was formed in the Early Cretaceous and in the Neogene. It experienced a serious reconstruction accompanied by the formation of the Amur River valley being similar to the modem one.

  13. Ocean, Spreading Centre

    Digital Repository Service at National Institute of Oceanography (India)

    Krishna, K.S.

    the lithospheric plates on either side in order to accommodate newly accreted crust. Many of the oceanic ridges in the world oceans have been abandoned in the geologic past and led to resume the activity elsewhere either in the intra-oceanic or intracontinental...

  14. MESMO 2: a mechanistic marine silica cycle and coupling to a simple terrestrial scheme

    Directory of Open Access Journals (Sweden)

    K. Matsumoto

    2012-09-01

    Full Text Available Here we describe the second version of Minnesota Earth System Model for Ocean biogeochemistry (MESMO 2, an earth system model of intermediate complexity, which consists of a dynamical ocean, dynamic-thermodynamic sea ice, and energy moisture balanced atmosphere. The new version has more realistic land ice masks and is driven by seasonal winds. A major aim in version 2 is representing the marine silica cycle mechanistically in order to investigate climate-carbon feedbacks involving diatoms, a critically important class of phytoplankton in terms of carbon export production. This is achieved in part by including iron, on which phytoplankton uptake of silicic acid depends. Also, MESMO 2 is coupled to an existing terrestrial model, which allows for the exchange of carbon, water, and energy between land and the atmosphere. The coupled model, called MESMO 2E, is appropriate for more complete earth system simulations. The new version was calibrated with the goal of preserving reasonable interior ocean ventilation and various biological production rates in the ocean and land, while simulating key features of the marine silica cycle.

  15. Anthropogenic impact on amorphous silica pools in temperate soils

    Science.gov (United States)

    Clymans, W.; Struyf, E.; Govers, G.; Vandevenne, F.; Conley, D. J.

    2011-08-01

    Human land use changes perturb biogeochemical silica (Si) cycling in terrestrial ecosystems. This directly affects Si mobilisation and Si storage and influences Si export from the continents, although the magnitude of the impact is unknown. A major reason for our lack of understanding is that very little information exists on how land use affects amorphous silica (ASi) storage in soils. We have quantified and compared total alkali-extracted (PSia) and easily soluble (PSie) Si pools at four sites along a gradient of anthropogenic disturbance in southern Sweden. Land use clearly affects ASi pools and their distribution. Total PSia and PSie for a continuous forested site at Siggaboda Nature Reserve (66 900 ± 22 800 kg SiO2 ha-1 and 952 ± 16 kg SiO2 ha-1) are significantly higher than disturbed land use types from the Råshult Culture Reserve including arable land (28 800 ± 7200 kg SiO2 ha-1 and 239 ± 91 kg SiO2 ha-1), pasture sites (27 300 ± 5980 kg SiO2 ha-1 and 370 ± 129 kg SiO2 ha-1) and grazed forest (23 600 ± 6370 kg SiO2 ha-1 and 346 ± 123 kg SiO2 ha-1). Vertical PSia and PSie profiles show significant (p export of 1.1 ± 0.8 Tmol Si yr-1 from the soil reservoir to aquatic ecosystems. This is ca. 20 % to the global land-ocean Si flux carried by rivers. It is necessary to update this estimate in future studies, incorporating differences in pedology, geology and climatology over temperate regions, but data are currently not sufficient. Yet, our results emphasize the importance of human activities for Si cycling in soils and for the land-ocean Si flux.

  16. Disentangling Topographic and Climatic Change during the Late Cretaceous and Cenozoic in the Western US Cordillera

    Science.gov (United States)

    Snell, K. E.; Eiler, J. M.; Wernicke, B. P.; Peppe, D. J.; Fox, D. L.; Fetrow, A. C.; Passey, B. H.

    2014-12-01

    A diverse suite of tectonic and climatic drivers influenced the topographic evolution of the western USA Cordillera. Despite years of study, considerable uncertainty remains about fundamentals of this evolution, such as the timing and magnitude of maximum average elevations for the different physiographic provinces; the drivers and topographic effects of different episodes of extension during the Cenozoic; and the relative relief of peaks and intermontane basins within the Cordillera at different times and in different places. Numerous tectonic models have been developed to explain the evolution of the Cordillera, and understanding these details is key for distinguishing between these different models. In addition, the topographic changes in the Cordillera have important implications for regional and local climate of the western US at different times in the past, and may drive important differences in local climatic responses to global climate changes through the Cenozoic. The majority of the tools that currently exist for quantitatively reconstructing changes in topography through time and space rely on paleoclimate proxy data. Thus it is also important to be able to disentangle climatic change from elevation change in terrestrial paleoclimate records. To address some of these outstanding questions, we have generated and compiled paleotemperature estimates from the Late Cretaceous through the Miocene of the western US. In this presentation, we will focus on the latest installment of the project, which utilizes Oligocene paleotemperature records from central Utah and South Dakota and Miocene-Holocene paleotemperature records from Kansas. The data are dominantly composed of mean annual temperature estimates from leaf margin analysis and summer temperature estimates from carbonate clumped isotope thermometry. We will discuss how these data compare to temperature data from the Paleogene from the western US, what general trends exist within all the data and how these

  17. Origin of the Adventure Subglacial Trench linked to Cenozoic extension in the East Antarctic Craton

    Science.gov (United States)

    Cianfarra, P.; Salvini, F.

    2016-02-01

    The Antarctic plate occupies a unique geodynamic setting being mostly surrounded by divergent or transform margins. Major intracontinental basins and highlands characterize its bedrock, buried under the 34 Ma East Antarctic Ice Sheet (EAIS). Their formation atop of the cratonic lithosphere in the interior of East Antarctica remains a major open question. Post-Mesozoic intraplate extensional tectonic activity has been proposed for their development and is supported by this work. Here we focus on the Adventure Subglacial Trench (AST) whose origin is poorly constrained and controversial, as currently available geophysical models suggest either extensional or compressional tectonic origin. The AST is an over 250-km-long, 60-km-wide subglacial trough, elongated in the NNW-SSE direction adjacent to the westernmost flank of the Wilkes Subglacial Basin, and is parallel to regional scale alignments of magnetic and gravimetric anomalies. Geophysical campaigns allowed better definition of the AST physiography showing its typical half-graben geometry. The rounded morphology of the western flank of the AST was simulated through tectonic numerical modelling. We consider the subglacial landscape to primarily reflect a preserved relict of the tectonic processes affecting the interior of East Antarctica in the Cenozoic, due to the negligible erosion/deposition capability of the EAIS. The bedrock morphology was replicated through the activity of the listric Adventure Fault, characterized by a basal detachment at the base of the crust (34 km) and a vertical displacement of 2.5 km. This length suggests its regional/crustal importance. The predicted displacement is interpreted either as a newly formed fault or as the partial reactivation of a weaker zone along a major Precambrian crustal-scale tectonic boundary. The extensional regime in the AST is part of a more extensive 800-km long intraplate corridor characterized by nearly along-strike extension in Cenozoic times with a left

  18. Cenozoic Source-to-Sink of the African margin of the Equatorial Atlantic

    Science.gov (United States)

    Rouby, Delphine; Chardon, Dominique; Huyghe, Damien; Guillocheau, François; Robin, Cecile; Loparev, Artiom; Ye, Jing; Dall'Asta, Massimo; Grimaud, Jean-Louis

    2016-04-01

    The objective of the Transform Source to Sink Project (TS2P) is to link the dynamics of the erosion of the West African Craton to the offshore sedimentary basins of the African margin of the Equatorial Atlantic at geological time scales. This margin, alternating transform and oblique segments from Guinea to Nigeria, shows a strong structural variability in the margin width, continental geology and relief, drainage networks and subsidence/accumulation patterns. We analyzed this system combining onshore geology and geomorphology as well as offshore sub-surface data. Mapping and regional correlation of dated lateritic paleo-landscape remnants allows us to reconstruct two physiographic configurations of West Africa during the Cenozoic. We corrected those reconstitutions from flexural isostasy related to the subsequent erosion. These geometries show that the present-day drainage organization stabilized by at least 29 Myrs ago (probably by 34 Myr) revealing the antiquity of the Senegambia, Niger and Volta catchments toward the Atlantic as well as of the marginal upwarp currently forming a continental divide. The drainage rearrangement that lead to this drainage organization was primarily enhanced by the topographic growth of the Hoggar swell and caused a major stratigraphic turnover along the Equatorial margin of West Africa. Elevation differences between paleo-landscape remnants give access to the spatial and temporal distribution of denudation for 3 time-increments since 45 Myrs. From this, we estimate the volumes of sediments and associated lithologies exported by the West African Craton toward different segments of the margin, taking into account the type of eroded bedrock and the successive drainage reorganizations. We compare these data to Cenozoic accumulation histories in the basins and discuss their stratigraphic expression according to the type of margin segment they are preserved in.

  19. The late Mesozoic-Cenozoic tectonic evolution of the South China Sea: A petrologic perspective

    Science.gov (United States)

    Yan, Quanshu; Shi, Xuefa; Castillo, Paterno R.

    2014-05-01

    This paper presents a review of available petrological, geochonological and geochemical data for late Mesozoic to Recent igneous rocks in the South China Sea (SCS) and adjacent regions and a discussion of their petrogeneses and tectonic implications. The integration of these data with available geophysical and other geologic information led to the following tectono-magmatic model for the evolution of the SCS region. The geochemical characteristics of late Mesozoic granitic rocks in the Pearl River Mouth Basin (PRMB), micro-blocks in the SCS, the offshore continental shelf and Dalat zone in southern Vietnam, and the Schwaner Mountains in West Kalimantan, Borneo indicate that these are mainly I-type granites plus a small amount of S-type granites in the PRMB. These granitoids were formed in a continental arc tectonic setting, consistent with the ideas proposed by Holloway (1982) and Taylor and Hayes (1980, 1983), that there existed an Andean-type volcanic arc during later Mesozoic era in the SCS region. The geochonological and geochemical characteristics of the volcanics indicate an early period of bimodal volcanism (60-43 Ma or 32 Ma) at the northern margin of the SCS, followed by a period of relatively passive style volcanism during Cenozoic seafloor spreading (37 or 30-16 Ma) within the SCS, and post-spreading volcanism (tholeiitic series at 17-8 Ma, followed by alkali series from 8 Ma to present) in the entire SCS region. The geodynamic setting of the earlier volcanics was an extensional regime, which resulted from the collision between India and Eurasian plates since the earliest Cenozoic, and that of the post-spreading volcanics may be related to mantle plume magmatism in Hainan Island. In addition, the nascent Hainan plume may have played a significant role in the extension along the northern margin and seafloor spreading in the SCS.

  20. Tectonic implications of space-time patterns of Cenozoic magmatism in the western United States

    Science.gov (United States)

    Snyder, W.S.; Dickinson, W.R.; Silberman, M.L.

    1976-01-01

    Locations of 2,100 radiometrically dated igneous rocks were plotted on a series of 20 maps, each representing an interval within the period 80 m.y. B.P. to present. Derivative maps showing the distributions in space and time of dated granitic intrusive rocks, silicic lavas and domes, ash-flow tuffs, andesitic-dacitic rocks, and basalts depict well the two main petrogenetic assemblages noted previously by others: (1) mainly intermediate andesitic-dacitic suites, including associated granitic intrusive rocks, silicic extrusive rocks, and minor basaltic lavas, are interpreted as reflecting plate interactions related to subduction along the continental margin; and (2) bimodal suites, dominantly basaltic but with minor silicic extrusive rocks, are interpreted as reflecting extensional tectonics. Space-time distribution of the two assemblages suggests that magmatic arcs extended continously parallel to the continental margin from Canada to Mexico in latest Mesozoic and in Oligocene times. An early Cenozoic null in magmatism in the Great Basin may delineate the region where subduction was arrested temporarily by development of the proto-San Andreas fault as a transform in coastal California or, alternatively, may reflect complex subsurface configurations of subducted plates. The late Cenozoic transition from subduction-related magmatism to extention-related basaltic volcanism in the southern Cordillera occurred at different times in different areas in harmony with current concepts about the migration of the Mendocino triple junction as the modern San Andreas transform fault was formed. The plots also reveal the existence of several discrete magmatic loci where igneous activity of various kinds was characteristically more intense and long-lived than elsewhere. ?? 1976.

  1. NOAA's Tropical Atmosphere Ocean Project

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Realtime El Nino and La Nina data from the tropical Pacific Ocean is provided by the Tropical Atmosphere Ocean / Triangle Trans-Ocean buoy network (TAO/TRITON) of...

  2. From School of Rock to Building Core Knowledge: Teaching about Cenozoic climate change with data and case studies from the primary literature

    Science.gov (United States)

    Leckie, R. M.; St John, K. K.; Jones, M. H.; Pound, K. S.; Krissek, L. A.; Peart, L. W.

    2011-12-01

    The School of Rock (SoR) began in 2005 as a pilot geoscience professional development program for K-12 teachers and informal educators aboard the JOIDES Resolution (JR). Since then, the highly successful SoR program, sponsored by the Consortium for Ocean Leadership's Deep Earth Academy, has conducted on-shore professional development at the Integrated Ocean Drilling Program (IODP) core repository in College Station, TX, and on the JR. The success of the SoR program stems from the natural synergy that develops between research scientists and educators when their combined pedagogical skills and scientific knowledge are used to uncover a wealth of scientific ocean drilling discoveries and research findings. Educators are challenged with authentic inquiry based on sediment archives; these lessons from the past are then made transferable to the general public and to classrooms through the creation of age-appropriate student-active learning materials (http://www.oceanleadership.org/education/deep-earth-academy/educators/classroom-activities/). This science made accessible approach was the basis for a successful NSF Course Curriculum and Laboratory Improvement (CCLI) proposal to develop teaching materials for use at the college level. Our Building Core Knowledge project resulted in a series of 14 linked, yet independent, inquiry-based exercise modules around the theme of Reconstructing Earth's Climate History. All of the exercises build upon authentic data from peer reviewed scientific publications. These multiple part modules cover fundamental paleoclimate principles, tools and proxies, and Cenozoic case studies. It is important to teach students how we know what we know. For example, paleoclimate records must be systematically described, ages must be determined, and indirect evidence (i.e., proxies) of past climate must be analyzed. Much like the work of a detective, geoscientists and paleoclimatologists reconstruct what happened in the past, and when and how it

  3. Regional Ocean Data Assimilation

    Science.gov (United States)

    Edwards, Christopher A.; Moore, Andrew M.; Hoteit, Ibrahim; Cornuelle, Bruce D.

    2015-01-01

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  4. Regional Ocean Data Assimilation

    KAUST Repository

    Edwards, Christopher A.

    2015-01-03

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  5. Computational Ocean Acoustics

    CERN Document Server

    Jensen, Finn B; Porter, Michael B; Schmidt, Henrik

    2011-01-01

    Since the mid-1970s, the computer has played an increasingly pivotal role in the field of ocean acoustics. Faster and less expensive than actual ocean experiments, and capable of accommodating the full complexity of the acoustic problem, numerical models are now standard research tools in ocean laboratories. The progress made in computational ocean acoustics over the last thirty years is summed up in this authoritative and innovatively illustrated new text. Written by some of the field's pioneers, all Fellows of the Acoustical Society of America, Computational Ocean Acoustics presents the latest numerical techniques for solving the wave equation in heterogeneous fluid–solid media. The authors discuss various computational schemes in detail, emphasizing the importance of theoretical foundations that lead directly to numerical implementations for real ocean environments. To further clarify the presentation, the fundamental propagation features of the techniques are illustrated in color. Computational Ocean A...

  6. Metal-silica sol-gel materials

    Science.gov (United States)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  7. Tectonically restricted deep-ocean circulation at the end of the Cretaceous greenhouse

    Science.gov (United States)

    Voigt, Silke; Jung, Claudia; Friedrich, Oliver; Frank, Martin; Teschner, Claudia; Hoffman, Julia

    2013-04-01

    The evolution of global ocean circulation towards deep-water production in the high southern latitudes is thought to have been closely linked to the transition from extreme mid-Cretaceous warmth to the cooler Cenozoic climate. The relative influences of climate cooling and the opening and closure of oceanic gateways on the mode of deep-ocean circulation are, however, still unresolved. Here we reconstruct intermediate- to deep-water circulation for the latest Cretaceous based on new high-resolution radiogenic neodymium (Nd) isotope data from several sites and for different water depths in the South Atlantic, Southern Ocean, and proto-Indian Ocean. Our new late Campanian to Maastrichtian data documents the presence of markedly different intermediate water Nd-isotopic compositions in the South Atlantic and Southern Ocean suggesting the presence of multiple, local water sources at nearly every site and a circulation system that was fundamentally different from the modern. In particular, a water mass with a highly radiogenic Nd isotope signature most likely originating from intense hotspot-related volcanic activity bathed the crest of Walvis Ridge between 71 and 69 Ma, which formed a barrier that prevented deep-water exchange between the Southern Ocean and the North Atlantic basins. The narrow geometry of the Atlantic Ocean together with tight to closed connections towards the Tethys and the Pacific Ocean limited volumetrically substantial deep-water exchange and promoted a local mode of deep oceanic convection in the Atlantic. Available Nd isotope data from the North Atlantic indicate the prevalence of different water masses in the abyssal plains and support a mode of ocean circulation that was maintained by down- and upwelling in various meso-scale eddies as proposed by Hay (2011, Sedim. Geol. 235, 5-26). Climatic cooling and the opening of gateways between 83-78 Ma may have initiated SCW formation in the southern hemisphere oceans. However, SCW formation did not

  8. TRIMETHYLSILYLATED SILICA AS RHEOLOGY MODIFIER FOR SILICONE RESINS

    Institute of Scientific and Technical Information of China (English)

    Wei Huang; Ying Huang; Yunzhao Yu

    2000-01-01

    Trimethylsilylated silica was synthesized through hydrolytic condensation of tetraethoxysilane followed by trimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. It turned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylated silica of medium particle size shows the strongest tendency of forming physical network in the resin.

  9. Fused Silica and Other Transparent Window Materials

    Science.gov (United States)

    Salem, Jon

    2016-01-01

    Several transparent ceramics, such as spinel and AlONs are now being produced in sufficient large areas to be used in space craft window applications. The work horse transparent material for space missions from Apollo to the International Space Station has been fused silica due in part to its low coefficient of expansion and optical quality. Despite its successful use, fused silica exhibits anomalies in its crack growth behavior, depending on environmental preconditioning and surface damage. This presentation will compare recent optical ceramics to fused silica and discuss sources of variation in slow crack growth behavior.

  10. Silica Microcapsules Prepared by Interfacial Reaction Methods

    Institute of Scientific and Technical Information of China (English)

    M; Fujiwara; K; Shiokawa; Y; Nakahara

    2007-01-01

    1 Results Silica spherical particles with hollow structure are directly prepared by interfacial reaction methods using W/O/W emulsion (schematic diagram in Fig.1)[1].Fig.1 Silica microcapsule formationThe mixing of W/O emulsion consisting of sodium silicate solution (inner water phase) and n-hexane solution (oil phase) to outer water phase dissolving NH4HCO3 or other salts affords silica microcapsules.The critical feature of this method is the direct formation of hollow structure.Therefore,the core com...

  11. Study of silica sorbents by SANS

    International Nuclear Information System (INIS)

    Silica gels under study are materials intended for use as the packing sorbents in liquid chromatography (LC), namely in gel permeation chromatography (GPC). The quality of silica for LC should meet strict physical and chemical parameters. Especially in GPC is very important to know pore size and pore shape because they control the whole process of chromatographic separation. Pore size and thickness of pore wall can be measured by various methods. SANS technique is a nondestructive method providing an average information about a large number of scattering object in our case about objects (pore or wall) in silica and their shape. (author)

  12. Progress in flotation de-silica

    Institute of Scientific and Technical Information of China (English)

    胡岳华

    2003-01-01

    Flotation de-silica from the diasporic-bauxite is one of the key basic research projects. It aimed to reveal the scientific mechanism between the crystal structure and surface properties, structure-properties of effective flotation reagent as well as the solution chemistry of flotation and interfacial interactions in the flotation system of diaspore and aluminosilicate minerals. It will underlay the new technology of reverse-flotation de-silica. The technology is important to enhance the mass ratio of Al2O3 to SiO2, decreasing the silica content and energy consumption in producing aluminum oxide and economically utilizing the diasporic-bauxite in China.

  13. Fluorine-Based DRIE of Fused Silica

    Science.gov (United States)

    Yee, Karl; Shcheglov, Kirill; Li, Jian; Choi, Daniel

    2007-01-01

    A process of deep reactive-ion etching (DRIE) using a fluorine-based gas mixture enhanced by induction-coupled plasma (ICP) has been demonstrated to be effective in forming high-aspect-ratio three-dimensional patterns in fused silica. The patterns are defined in part by an etch mask in the form of a thick, high-quality aluminum film. The process was developed to satisfy a need to fabricate high-aspect-ratio fused-silica resonators for vibratory microgyroscopes, and could be used to satisfy similar requirements for fabricating other fused-silica components.

  14. Behaviour of colloidal silicas during uniaxial compaction

    OpenAIRE

    Ehrburger, Françoise; Lahaye, Jacques

    1989-01-01

    The pressure P transmitted by colloidal silica samples during low speed uniaxial compaction, is measured as a function of the volume fraction f of solid. In the case of pyrogenic silicas, two domains are evidenced. A first one below f ~ 0.065, is characterized by a percolation type behaviour P ~ (f - fc)k. For higher volume fractions (second domain) P scales as the void volume Vp, P ~ (Vp)- α with α ~ 3. It appears that the behaviour of the precipitated silica is very different. The P(f) curv...

  15. Silica aerogel radiators for bunch length measurements

    International Nuclear Information System (INIS)

    Cherenkov radiators based on silica aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen (PITZ). The energy range of those electrons is 4-5 MeV. In this paper, the time resolution defined by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown that silica aerogel gives the possibility to reach a time resolution of about 0.1 ps for high photon intensities and a time resolution of about 0.02 ps can be obtained for thin silica aerogel radiators

  16. Aggregation/dispersion of ultrafine silica in flotagent solution

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The aggregation/dispersion of ultrafine particles is of interest for both fundamental and practical perspective. These behaviors of ultrafine silica in flotagent solution and the heter-coagulation of silica and alumina were examined using particle size analyzer, electrokinetic potential, contact angle measurements. The flotation reagents have a pronounced effect on the aggregation or dispersion behaviors of ultrafine silica suspensions. Collector dodecylamine chloride renders silica surfaces hydrophobic and the aggregation between silica particles takes place. Modifier tripolyphosphate makes the silica surface completely hydrophilic and enhances the stability of silica suspension. These experimental results can be explained based on the extended DLVO theory by considering polar interfacial interaction between particle surfaces.

  17. Amorphous silica from rice husk at various temperatures

    International Nuclear Information System (INIS)

    Rice husk is being used as a source of energy in many heat generating system because of its high calorific value and its availability in many rice producing areas. Rice husk contains approximately 20% silica which is presented in hydrated form. This hydrated silica can be retrieved as amorphous silica under controlled thermal conditions. Uncontrolled burning of rice husk produces crystalline silica which is not reactive silica but can be used as filler in many applications. Amorphous silica is reactive silica which has better market value due to its reactive nature in process industry. The present study deals with the production of amorphous silica at various temperatures from rice husk. Various ashes were prepared in tube furnace by changing the burning temperatures for fixed time intervals and analyzed by XRD. It has been observed that for two hours calculation's of rice husk renders mostly amorphous silica at 650 degree C where as at higher temperatures crystalline silica was obtained. (author)

  18. Nanometer Sized Silver Particles Embedded Silica Particles—Spray Method

    OpenAIRE

    Karunagaran B; Nimma Elizabeth R.; Gnana kumar G; Nahm KeeSuk

    2009-01-01

    Abstract Spherical shaped, nanometer to micro meter sized silica particles were prepared in a homogeneous nature by spray technique. Silver nanoparticles were produced over the surface of the silica grains in a harmonized manner. The size of silver and silica particles was effectively controlled by the precursors and catalysts. The electrostatic repulsion among the silica spheres and the electro static attraction between silica spheres and silver particles make the synchronized structure of t...

  19. Structural changes in precipitated silica induced by external forces

    OpenAIRE

    Schneider, G. J.; Göritz, D.

    2011-01-01

    The morphology of pure precipitated silica, silica filled in polydimethylsiloxane rubber, and silica filled in styrene butadiene rubber was studied by means of small-angle X-ray scattering experiments. The silica at a length scale of a few nanometers consists of primary particles, which form aggregates, and clusters with aggregates as basic units. It is evidenced that the aggregate branching, represented by the mass fractal dimension, and the aggregate diameter are different if pure silica an...

  20. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    International Nuclear Information System (INIS)

    Highlights: • Substantiate the ring open reaction between Si-OH of silica and epoxy groups of ENR. • ENR can act as a bridge between NR and silica to enhance the interfacial interaction. • As a modifier, ENR gets the potential to be used in the tread of green tire for improving the wet skid resistance apparently. - Abstract: The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress–strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature

  1. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tiwen [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Jia, Zhixin, E-mail: zxjia@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Yuanfang; Jia, Demin [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Peng, Zheng [Agricultural Product Processing Research Institute, Chinese Academy of Tropical Agriculture Sciences, Zhanjiang 524001 (China)

    2015-02-15

    Highlights: • Substantiate the ring open reaction between Si-OH of silica and epoxy groups of ENR. • ENR can act as a bridge between NR and silica to enhance the interfacial interaction. • As a modifier, ENR gets the potential to be used in the tread of green tire for improving the wet skid resistance apparently. - Abstract: The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress–strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  2. Geochemical Characteristics of the Cenozoic Volcanic Rocks in Central Qiangtang, Tibet: Relation with the Uplift of the Qinghai Tibet Plateau

    Institute of Scientific and Technical Information of China (English)

    TAN Fuwen; PAN Guitang; XU Qiang

    2001-01-01

    The Cenozoic volcanic rocks in central Qiangtang are tectonically outcropped in the transitional area where crust of the Qinghai-Tibet Plateau thins northwards and the Passion's ratios of the crust increases abnormally northwards. Of all Cenozoic volcanic rocks of northern Tibet, the volcanic rocks in Qiangtang area is the oldest one with ages from 44.1±1.0 Ma to 32.6±0.8 Ma. Petrological and geochemical studies of the volcanic rocks in central Qiangtang suggest they formed in the extension environment of post collision-orogeny and were the product of mixture of magmas from crust and mantle. The uplift of the northern plateau is closely related to decoupling of mantle lithosphere,crustal extension and thinning as well as volcanism. Therefore, it is inferred that the main uplift of the northern plateau began from about 40 Ma ago.

  3. Investigating Cenozoic climate change in tectonically active regions with a high-resolution atmospheric general circulation model (ECHAM5)

    Science.gov (United States)

    Mutz, Sebastian; Ehlers, Todd; Li, Jingmin; Werner, Martin; Stepanek, Christian; Lohmann, Gerrit

    2016-04-01

    Studies of Cenozoic palaeo-climates contribute to our understanding of contemporary climate change by providing insight into analogues such as the Pliocene (PLIO), and by evaluation of GCM (General Circulation Models) performance using the Mid-Holocene (MH) and the Last Glacial Maximum (LGM). Furthermore, climate is a factor to be considered in the evolution of ecology, landscapes and mountains, and in the reconstruction of erosion histories. In this study, we use high-resolution (T159) ECHAM5 simulations to investigate pre-industrial (PI) and the the above mentioned palaeo-climates for four tectonically active regions: Alaska (St. Elias Range), the US Northwest Pacific (Cascade Range), western South America (Andes) and parts of Asia (Himalaya-Tibet). The PI climate simulation is an AMIP (Atmospheric Model Intercomparison Project) style ECHAM5 experiment, whereas MH and LGM simulation are based on simulations conducted at the Alfred Wegner Institute, Bremerhaven. Sea surface boundary conditions for MH were taken from coupled atmosphere-ocean model simulations (Wei and Lohmann, 2012; Zhang et al, 2013) and sea surface temperatures and sea ice concentration for the LGM are based on GLAMAP project reconstructions (Schäfer-Neth and Paul, 2003). Boundary conditions for the PLIO simulation are taken from the PRISM (Pliocene Research, Interpretation and Synoptic Mapping) project and the employed PLIO vegetation boundary condition is created by means of the transfer procedure for the PRISM vegetation reconstruction to the JSBACH plant functional types as described by Stepanek and Lohmann (2012). For each of the investigated areas and time slices, the regional simulated climates are described by means of cluster analyses based on the variability of precipitation, 2m air temperature and the intra-annual amplitude of the values. Results indicate the largest differences to a PI climate are observed for LGM and PLIO climates in the form of widespread cooling and warming

  4. Mesozoic extension and Cenozoic contraction in an intraplate setting (Maestrat basin, Iberian Chain, E Spain)

    Science.gov (United States)

    Nebot Miralles, M.; Guimerà Roso, J.

    2013-12-01

    The Iberian Chain, located in the eastern Iberian Peninsula, is a fold-and-thrust belt developed during the Cenozoic, because of the contractional inversion of the Mesozoic Iberian Rift System. The extension in the Iberian Chain took place in two major rifting cycles (late Permian to late Triassic and late Oxfordian to late Albian) followed by episodes of lower rifting activity (early and middle Jurassic, and late Albian to Maastrichtian). The Maestrat basin (containing up to 6.5 km of Mesozoic sediments) is one of the most subsident basins during the late Oxfordian to late Albian cycle. A system of listric extensional faults, which involve the basement, bounded the basin, and also divided it into minor sub-basins, containing different thicknesses of the Mesozoic sedimentary fill. An E-W-trending, N-verging, fold-and-thrust belt developed in the northern boundary of the basin, as the result of the Cenozoic inversion. This belt involved the Mesozoic cover in the northern -foreland- areas, with a detachment level located within the Triassic: in the Middle Muschelkalk (Middle Triassic) and Keuper (Upper Triassic), both formed by lutites and evaporites. Southwards, the thrust-system also involved the Variscan basement. A study of the region containing the transition between the thin-skinned and the thick-skinned areas is presented, based on seismic profiles, oil-exploration wells and field data. A progressive northward thickening of Jurassic and lower Cretaceous units, related to a S-dipping listric extensional fault located to the N, can be observed both in the field and the seismic profiles. In the Triassic rocks, depositional thickness variations in the Middle Muschelkalk unit are observed, related to sub-vertical faults active during the Triassic rifting. Salt anticlines, pillows and welds are also observed in the Middle Muschelkalk. These halocynetic structures developed during the Keuper, as it is deduced from the onlap geometries of the Keuper seismic reflectors

  5. Anomalous enthalpy relaxation in vitreous silica

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2015-01-01

    scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....

  6. Cathodoluminescence microcharacterization of ballen silica in impactites

    International Nuclear Information System (INIS)

    The ballen silica shows fairly weak (faint) CL with homogeneous feature in its grain exhibiting almost same spectral pattern with two broad band peaks at around 390 and 650 nm, which might be assigned to self-trapped excitons (STE) or an intrinsic and nonbridging oxygen hole centers (NBOHC), respectively, recognized in amorphous and crystalline silica. In addition, ballen silica from Lappajaervi crater shows bright and heterogeneous CL with a broad band centered at around 410 nm, presumably attributed to [AlO4/M+]0 centers or self-trapped excitons (STE). Micro-Raman and micro-XRD analyses show that fairly homogeneous CL part is α-quartz and heterogeneous CL part is composed of α-cristobalite and α-quartz. These indicate that ballen silica could be formed in the quenching process from relatively high temperature.

  7. Characterization of zirconized silica supports for HPLC

    International Nuclear Information System (INIS)

    The preparation and characterization of zirconized silica has been investigated. The material was prepared via the reaction of silica with zirconium tetrabutoxide, optimized by a central composite design and response surface methodology. The new material was characterized by nitrogen adsorption-desorption investigations (BET/BJH) showing specific surface areas adequate for use as a chromatographic support. DRUVS, FTIR, XPS, XAS, XRF and SEM methods also were used to characterize the new material. It was shown that silica networks were not significantly modified with the introduction of zirconium. Surface analyses show that there is appreciable element enrichment at the surface, while significant changes in binding energies of Zr 3d, Si 2p, and O 1s have been detected. The above observations indicate that Si-O-Zr bonds were formed, with zirconium grafted onto the silica surface, yielding a support suitable for HPLC

  8. Nanoparticle-doped radioluminescent silica optical fibers

    Science.gov (United States)

    Mrazek, J.; Nikl, M.; Kasik, I.; Podrazky, O.; Aubrecht, J.; Beitlerova, A.

    2014-05-01

    This contribution deals with the preparation and characterization of the silica optical fibers doped by nanocrystalline zinc silicate. The sol-gel approach was employed to prepare colloidal solution of zinc silicate precursors. Prepared sol was thermally treated to form nanocrystalline zinc silicate disperzed inside amorphous silica matrix or soaked inside the porous silica frit deposed inside the silica substrate tube which was collapsed into preform and drawn into optical fiber. Single mode optical fiber with the core diameter 15 μm and outer diamer 125 μm was prepared. Optical and waveguiding properties of the fiber were analyzed. Concentration of the zinc silicate in the fiber was 0.93 at. %. Radioluminescence properties of nanocrystalline zinc silicate powder and of the prepared optical fiber were investigated. The nanoparticle doped samples appear a emission maximum at 390 nm.

  9. Anisotropic silica mesostructures for DNA encapsulation

    Indian Academy of Sciences (India)

    Aparna Ganguly; Ashok K Ganguli

    2013-04-01

    The encapsulation of biomolecules in inert meso or nanostructures is an important step towards controlling drug delivery agents. Mesoporous silica nanoparticles (MSN) are of immense importance owing to their high surface area, large pore size, uniform particle size and chemical inertness. Reverse micellar method with CTAB as the surfactant has been used to synthesize anisotropic mesoporous silica materials. We have used the anisotropic silica nanostructures for DNA encapsulation studies and observed a loading capacity of ∼8 g mg-1 of the sample. On functionalizing the pores of silica with amine group, the amount of DNA loaded on the rods decreases which is due to a reduction in the pore size upon grafting of amine groups.

  10. Silica Brick for Hot Blast Stove

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ 1 Scope This standard specifies the glossary and definition, marking, shape and dimension, technical requirements, test method, quality appraisal procedure, packing, label, transportation, storage and quality certification of silica brick for hot blast stove.

  11. Procedure to prepare transparent silica gels

    Science.gov (United States)

    Barber, Patrick G. (Inventor); Simpson, Norman R. (Inventor)

    1987-01-01

    This invention relates to the production of silica gels and in particular to a process for the preparation of silica gels which can be used as a crystal growth medium that simulates the convectionless environment of space to produce structurally perfect crystals. Modern utilizations of substances in electronics, such as radio transmitters and high frequency microphones, often require single crystals with controlled purity and structural perfection. The near convectionless environment of silica gel suppresses nucleation, thereby reducing the competitive nature of crystal growth. This competition limits the size and perfection of the crystal; and it is obviously desirable to suppress nucleation until, ideally, only one crystal grows in a predetermined location. A silica gel is not a completely convectionless environment like outer space, but is the closest known environment to that of outer space that can be created on Earth.

  12. Silica precipitation with synthetic silaffin peptides.

    Science.gov (United States)

    Wieneke, Ralph; Bernecker, Anja; Riedel, Radostan; Sumper, Manfred; Steinem, Claudia; Geyer, Armin

    2011-08-01

    Silaffins are highly charged proteins which are one of the major contributing compounds that are thought to be responsible for the formation of the hierarchically structured silica-based cell walls of diatoms. Here we describe the synthesis of an oligo-propyleneamine substituted lysine derivative and its incorporation into the KXXK peptide motif occurring repeatedly in silaffins. N(ε)-alkylation of lysine was achieved by a Mitsunobu reaction to obtain a protected lysine derivative which is convenient for solid phase peptide synthesis. Quantitative silica precipitation experiments together with structural information about the precipitated silica structures gained by scanning electron microscopy revealed a dependence of the amount and form of the silica precipitates on the peptide structure. PMID:21674108

  13. Femtosecond laser micromachining of fused silica molds.

    Science.gov (United States)

    Madani-Grasset, Frédéric; Bellouard, Yves

    2010-10-11

    The use of low-energy femtosecond laser beam combined with chemical etching has been proven to be an efficient method to fabricate three-dimensional structures in fused silica. For high-volume application, this technology--like other serial processes--suffers from a moderate production rate. Here, we show that femtosecond laser can also be employed to fabricate silica molds and other patterned surfaces, including surfaces with high aspect ratio features (> 10). Through appropriate tailoring of silica's surface property and subsequent creation of, for instance, simple elastomeric molding, new opportunities for the indirect 3D, multi-scale spatial characterization of deep laser-fabricated microstructures come along. We demonstrate that those moldings are characterized by a high fidelity (down to the nanometer scale) to the silica mold. These results further advance the applicability of femtosecond laser processing to glass. PMID:20941083

  14. Silica aerogel films formation on silicon surfaces

    International Nuclear Information System (INIS)

    A new technique of formation of thin charged silica aerogel films upon a Si surface is suggested. Degree of porosity of the synthesized films is estimated. Their composition and charge state of the dielectric-semiconductor system are studied

  15. Cenozoic foreland-basin evolution in the northern Andes : insights from thermochronology and basin analysis in the Eastern Cordillera, Colombia

    OpenAIRE

    Parra, Mauricio

    2009-01-01

    The modern foreland basin straddling the eastern margin of the Andean orogen is the prime example of a retro-arc foreland basin system adjacent to a subduction orogen. While widely studied in the central and southern Andes, the spatial and temporal evolution of the Cenozoic foreland basin system in the northern Andes has received considerably less attention. This is in part due to the complex geodynamic boundary conditions, such as the oblique subduction and accretion of the Caribbean plates ...

  16. Cenozoic Mammals and Climate Change: The Contrast between Coarse-Scale versus High-Resolution Studies Explained by Species Sorting

    OpenAIRE

    Donald Prothero

    2012-01-01

    Many paleontologists have noticed the broadly similar patterns between the changes in Cenozoic mammalian diversity and taxonomic dominance and climate changes. Yet detailed studies of fossil population samples with fine-scale temporal resolution during episodes of climate change like the Eocene-Oligocene transition in the White River Group, and the late Pleistocene at Rancho La Brea tar pits, demonstrates that most fossil mammal species are static and show no significant microevolutionary res...

  17. Discussion on the characteristics of Meso-Cenozoic U-productive basins in northern China and their prospecting direction

    International Nuclear Information System (INIS)

    Based on the study of sedimentary evolution characteristics of main sedimentary basins and combined with characteristics of known uranium-productive basins in northern China, and the analysis on airborne geophysical survey data, the principles for selecting prospecting and target area have been set up. And the prospecting direction for uranium in Meso-Cenozoic basins of northern China has been proposed through a preliminary analysis. (authors)

  18. Stabilization of large drainage basins over geological time scales : Cenozoic West Africa, hot spot swell growth, and the Niger River

    OpenAIRE

    Chardon, Dominique; Grimaud, J. L.; Rouby, D.; BEAUVAIS, Anicet; Christophoul, F.

    2016-01-01

    Reconstructing the evolving geometry of large river catchments over geological time scales is crucial to constraining yields to sedimentary basins. In the case of Africa, it should further help deciphering the response of large cratonic sediment routing systems to Cenozoic growth of the basin-and-swell topography of the continent. Mapping of dated and regionally correlated lateritic paleolandscape remnants complemented by onshore sedimentological archives allows the reconstruction...

  19. The Ajo Mining District, Pima County, Arizona--Evidence for Middle Cenozoic Detachment Faulting, Plutonism, Volcanism, and Hydrothermal Alteration

    Science.gov (United States)

    Cox, Dennis P.; Force, Eric R.; Wilkinson, William H.; More, Syver W.; Rivera, John S.; Wooden, Joseph L.

    2006-01-01

    Introduction: The Ajo porphyry copper deposit and surrounding Upper Cretaceous rocks have been separated from their plutonic source and rotated by detachment faulting. Overlying middle Cenozoic sedimentary and volcanic rocks have been tilted and show evidence for two periods of rotation. Following these rotations, a granitic stock (23.7?0.2 Ma) intruded basement rocks west of the Ajo deposit. This stock was uplifted 2.5 km to expose deep-seated Na-Ca alteration.

  20. Silica Transport and Cementation in Quartz Aggregates

    Science.gov (United States)

    Pebble, C.; Farver, J.; Onasch, C.; Winslow, D.

    2008-12-01

    Silica transport and cementation in quartz aggregates have been experimentally investigated. Starting materials include a natural quartz arenite (Pocono sandstone), sized clasts of synthetic quartz, and sized grains of disaggregated natural sandstones. Experimental charges consisted of amorphous silica powder (~25 mg), AlCl3 powder (~3 mg), 25 wt% NaCl brine solution (~20 mg), and the starting material (~150 mg). The charges were weld-sealed in gold capsules and run in cold-seal pressure vessels at 300°C to 600°C at 150 MPa confining pressure for up to 4 weeks. Detailed calibrations of the furnaces indicate the maximum temperature variation across the length of the sample charges (3-7mm) was vacuum impregnated with epoxy containing a blue dye and sawn in half along the long axis of the sample charge. The nature and amount of silica transport and cementation in the samples was determined by a combination of Cathodoluminescence (CL), Light Microscopy (LM), and Scanning Electron Microscopy (SEM). Photomosaics of the samples were collected and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement was easily recognized from the quartz grains by the difference in luminescence. The experiments indicate that the presence of amorphous silica results in rapid silica cementation in quartz aggregates (e.g., up to 12% cement by volume in 4 weeks at 450°C). The amount of cementation is a function of substrate type, time, temperature, and ionic strength of the brine. The rate of silica transport through the length of the experimental charge appears to be limited by the silica solubility and its rapid depletion by cementation. Although most of the cement was derived from the amorphous silica, evidence for local dissolution-precipitation was observed. The experiments demonstrate that the mobility of silica, and consequent precipitation of cement, does not require a temperature or pressure gradient as is commonly assumed. Rather

  1. The Southern Ocean Observing System

    OpenAIRE

    Rintoul, Stephen R.; Meredith, Michael P.; Schofield, Oscar; Newman, Louise

    2012-01-01

    The Southern Ocean includes the only latitude band where the ocean circles the earth unobstructed by continental boundaries. This accident of geography has profound consequences for global ocean circulation, biogeochemical cycles, and climate. The Southern Ocean connects the ocean basins and links the shallow and deep limbs of the overturning circulation (Rintoul et al., 2001). The ocean's capacity to moderate the pace of climate change is therefore influenced strongly by the Southern Ocean's...

  2. UK silica sand resources for fracking

    OpenAIRE

    Mitchell, Clive

    2013-01-01

    UK silica sand resources for fracking Clive Mitchell, Industrial Minerals Specialist, British Geological Survey, Keyworth, Nottingham, NG12 5GG Email: Silica sand is high purity quartz sand that is mainly used for glass production, as foundry sand, in horticulture, leisure and other industrial uses. One specialist use is as a ‘proppant’ to enhance oil and gas recovery. This presentation will focus on this application, particularly for shale gas recovery where it is mo...

  3. Silica sand resources in the Netherlands

    OpenAIRE

    van der Meulen, M.J.; Westerhoff, W.E.; Menkovic, A.; Gruijters, S.H.L.L.; Dubelaar, C.W.; Maljers, D.

    2009-01-01

    Silica sand, (almost) pure quartz sand, is a valuable and scarce mineral resource within the shallow Dutch subsurface. High-grade deposits are exploited in the southeastemmost part of the country, as raw material for the glass, ceramic, chemical and other process industries. Dutch land-use policy requires that scarce mineral resources (including silica sand) are taken into consideration in spatial planning and when preparing for largescale engineering or construction works. For this purpose, ...

  4. Direct liquid crystal templating of mesoporous silica

    OpenAIRE

    Gordon-Smith, Tobias James

    2003-01-01

    The work described in this thesis is concerned with the development of ordered mesoporous silicas by direct templating from lyotropic liquid crystal phases of the surfactants Pluronic PI23, Pluronic F127, CTAB and Brij 78. The factors affecting the regularity, morphology, pore diameter and wall thickness of the templated mesoporous silicas were examined by exploring the reaction composition space and plotting the structural properties on TMOS/surfactant/water ternary diagrams. ...

  5. Use of silica aerogel in Cherenkov counters

    International Nuclear Information System (INIS)

    Silica aerogel has been widely used as a radiator for Cherenkov detectors. The review is devoted to the consideration of various aspects concerning aerogel: its production methods, optical and physical properties, including transparency, absorption, and scattering lengths, the number of photoelectrons and also factors affecting the accuracy of particle identification. The use of silica aerogel in various threshold Cherenkov counters as BELLE (KEK), TASSO (DESY), KEDR (VEPP-4M) is described

  6. Silica Aerogel Captures Cosmic Dust Intact

    Science.gov (United States)

    Tsou, P.

    1994-01-01

    The mesostructure of silica aerogel resembles stings of grapes, ranging in size from 10 to 100 angstrom. This fine mesostructure transmits nearly 90 percent of incident light in the visible, while providing sufficiently gentle dissipation of the kinetric energy of hypervelocity cosmic dust particles to permit their intact capture. We introduced silica aerogel in 1987 as capture medium to take advantage of its low density, fine mesostruicture and most importantly, its transparency, allowing optical location of captured micron sized particles.

  7. Tests of a silica aerogel Cherenkov counter

    International Nuclear Information System (INIS)

    A Cherenkov counter with silica aerogel of refractive index 1.06 as radiator has been constructed and tested. The Cherenkov light produced in 9 cm thick silica aerogel was detected with four 5''-photomultipliers through a 162 cm long air light guide. The photoelectron yield for a 1 GeV/c pion beam was found to be 6 and uniform over a sensitive area of 40 x 30 cm2. (orig.)

  8. Optical shock waves in silica aerogel.

    Science.gov (United States)

    Gentilini, S; Ghajeri, F; Ghofraniha, N; Di Falco, A; Conti, C

    2014-01-27

    Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels. PMID:24515173

  9. Cenozoic exhumation history of Sulu terrane: Implications from (U-Th)/He thermochrology

    Science.gov (United States)

    Wu, Lin; Monié, Patrick; Wang, Fei; Lin, Wei; Ji, Wenbin; Bonno, Michael; Münch, Philippe; Wang, Qingchen

    2016-03-01

    The Qinling-Dabie-Sulu orogen is the most prominent Phanerozoic orogenic belt in China. The discovery of ultra-high pressure (UHP) minerals in zircon inclusions suggests that the crust was subducted to deeper than 120 km into the mantle and then exhumed to shallow crustal. Recently, low temperature thermochronology has been applied to constrain the final exhumation of Dabie Shan, while there are few studies describing the Cenozoic exhumation history of the Sulu belt. Here we report some (U-Th)/He ages for various lithologies from Sulu Orogenic belt and its northern part-Jiaobei terrane. The single grain He ages range between 18 and 154 Ma, and most of the samples having large intra-sample age scattering. Several reasons such as invisible U/Th-rich inclusions, grain size effect, slow cooling rate, and zonation of parent nuclide or radiation damage effect may account for this dispersion. For all samples, the pattern of the single grain age data exhibits a peak at ~ 45 Ma which is consistent with the borehole fission-track age pattern in adjacent Hefei Basin. Both (U-Th)/He and fission track ages of the Sulu area suggest an enhanced exhumation/cooling in Early-Middle Eocene in the southern part of Tan-Lu fault zone. This enhanced cooling event coincides with rapid subsidence of North China Basin and rapid uplift of its surrounding reliefs, which indicates basin-mountain coupling. This Eocene event is widespread in central China and could be far-field consequence of India-Asia collision. The convergence rate between Pacific Plate and Eurasia decreased substantially during early Tertiary and reached a minimum in Eocene (~ 30-40 mm/yr) while at the same time the collision between India and Asia was completed. Therefore, the Cenozoic exhumation history of the Sulu Orogenic Belt was a combined result of far-field effect of India-Asia collision and declined subduction rate of the Pacific Plate under Eurasia.

  10. Cenozoic intraplate volcanism in Mongolia; if not a mantle plume then what?

    Science.gov (United States)

    Barry, T. L.; Saunders, A. D.; Kempton, P. D.

    2003-04-01

    Diffuse, small-volume basaltic volcanism has occurred throughout Mongolia for the past 30 My. This region provides an excellent opportunity to study intraplate volcanism because it is clearly on continental crust and far removed from the effects of subduction-related processes. Although magma has been erupted onto 45 km thick crust, there appears to be very little crustal contamination (Barry et al., 2003). The volcanism also provides an important link between the basaltic volcanism to the north around the Baikal rift zone, which has often been related to a mantle plume and Cenozoic basaltic volcanism that infills extensional grabens within NE China. Very clear chemical similarities within all the Baikal-Mongolia-NE China Cenozoic basalts exists (Barry &Kent, 1998) suggesting that the mantle source region beneath this vast area may be the same. Therefore, one general model should be able to explain all the volcanism. Trace element, REE and isotopic modeling of Mongolian basalt compositions indicate that the melts most likely formed within the lowermost lithospheric mantle from recently metasomatised lithosphere. There is no evidence for high heat flow within the mantle (Khutorskoy &Yarmolyuk, 1989), but geophysical studies infer anomalously dense material to be present at the base of the lithospheric mantle (Petit et al., 2002) which is coincident with a low velocity zone at ~200 km depth (Villaseñor et al., 2001). However, there does not appear to be anomalous low velocity material within the asthenospheric mantle. Geochemistry of the basalts give no positive indication for the presence of an underlying mantle plume. Conversely, whilst localized extensional tectonics may have aided the extrusion of basaltic melts, the small amount of extension cannot account for the generation of the basalts (McKenzie &Bickle, 1988). Lacking evidence for a high heat flux mantle plume, we may suggest the presence of a thermal anomaly, i.e. additional heat within the asthenosphere

  11. Mesozoic-Cenozoic Reconstruction of the East Gobi Fault Zone, Southern Mongolia

    Science.gov (United States)

    Heumann, M. J.; Johnson, C. L.; Webb, L. E.; Taylor, J. P.

    2009-12-01

    We present reconstructions based on multifaceted sedimentary basin and structural analyses that constrain the timing and character of intracontinental deformation observed in Mesozoic rift sub-basins (Unegt and Zuunbayan) and Permian deposystems (Bulgan Uul and Nomgon) along the East Gobi Fault Zone (EGFZ), southeastern Mongolia. The rocks studied throughout the EGFZ record nearly 300 million years of history including final closure of the paleo Tethys Sea during the Permian, Late Triassic sinistral shearing, Jurassic transpression followed by rift initiation, Early Cretaceous rifting, mid-Cretaceous basin inversion, and early Cenozoic left-lateral strike-slip faulting. Integrated studies of detrital zircon geochronology, field mapping and 2-D seismic survey fault-generation interpretation are critical to unraveling deformational events recorded in the pre-, syn-, and post-rift sedimentary units of these sub-basins. These efforts also shed light on paleogeographic reconstructions for the south Gobi following closure of the paleo Tethys Sea and docking of the North China block in the late Permian. Extensive detrital zircon analyses on 23 sandstone units used as piercing points along the EGFZ to indicate roughly 270 km of total sinistral offset has occurred along the EGFZ since the Late Permian, approximately 90 km of which has occurred since the mid Cretaceous. Therefore ~180 km of left-lateral offset along the EGFZ has occurred in the Triassic and Jurassic periods of deformation and have implications for published tectonic models. Fault generation maps produced from proprietary 2-D seismic reflection surveys, and correlation to outcrop, suggest the localized partitioning of deformation throughout the basins with time, often focusing along basin-bounding faults. Reinterpretation of the available seismic data highlights areas north (e.g., Har Hotol locality) of the main North Zuunbayan strike-slip fault (the NZB fault), which show a strikingly different deformational

  12. Mesozoic and Cenozoic exhumation history of the SW Iberian Variscides inferred from low-temperature thermochronology

    Science.gov (United States)

    Vázquez-Vílchez, Mercedes; Jabaloy-Sánchez, Antonio; Azor, Antonio; Stuart, Finlay; Persano, Cristina; Alonso-Chaves, Francisco M.; Martín-Parra, Luis Miguel; Matas, Jerónimo; García-Navarro, Encarnación

    2015-11-01

    The post-Paleozoic tectonothermal evolution of the SW Iberian Variscides is poorly known mainly due to the scarce low-temperature geochronological data available. We have obtained new apatite fission-tracks and apatite (U-Th)/He ages to constrain the Mesozoic and Cenozoic tectonic evolution of this portion of the Iberian Massif located just north of the Betic-Rif Alpine orogen. We have obtained nine apatite fission-track ages on samples from Variscan and pre-Variscan granitoids. These ages range from 174.4 (± 10.8) to 54.1 (± 4.9) Ma, with mean track lengths between 10.3 and 13.9 μm. We have also performed 5 (U-Th)/He datings on some of the same samples, obtaining ages between 74.6 (± 1.6) and 18.5 (± 1.4) Ma. Time-temperature path modeling of these low-temperature geochronological data leads us to envisage four post-Paleozoic tectonically controlled exhumation episodes in the SW Iberian Variscides. Three of these episodes occurred in Mesozoic times (Middle Triassic to Early Jurassic, Early Cretaceous, and Late Cretaceous) at rates of ≈ 1.1 to 2.5 °C Ma- 1, separated by periods with almost no cooling. We relate these Mesozoic cooling events to the formation of important marginal reliefs during the rifting and opening of the central and northern Atlantic realm. The fourth exhumation episode occurred in Cenozoic times at rates of ≈ 3.2 to 3.6 °C Ma- 1, being only recorded in samples next to faults with topographic escarpments. These samples cooled below 80 °C at ≈ 20 Ma at rates of 3-13 °C Ma- 1 due to roughly N-S oriented compressional stresses affecting the whole Iberian plate, which, in the particular case of SW Iberia, reactivated some of the previous Late Paleozoic thrusts.

  13. Pacific Plate slab pull and intraplate deformation in the early Cenozoic

    Directory of Open Access Journals (Sweden)

    N. P. Butterworth

    2014-01-01

    Full Text Available Large tectonic plates are known to be susceptible to internal deformation, leading to a range of phenomena including intraplate volcanism. However, the space and time dependence of intraplate deformation and its relationship with changing plate boundary configurations, subducting slab geometries, and absolute plate motion is poorly understood. We utilise a buoyancy driven Stokes flow solver, BEM-Earth, to investigate the contribution of subducting slabs through time on Pacific Plate motion and plate-scale deformation, and how this is linked to intraplate volcanism. We produce a series of geodynamic models from 62 to 42 Ma in which the plates are driven by the attached subducting slabs and mantle drag/suction forces. We compare our modelled intraplate deformation history with those types of intraplate volcanism that lack a clear age progression. Our models suggest that changes in Cenozoic subduction zone topology caused intraplate deformation to trigger volcanism along several linear seafloor structures, mostly by reactivation of existing seamount chains, but occasionally creating new volcanic chains on crust weakened by fracture zones and extinct ridges. Around 55 Ma subduction of the Pacific-Izanagi ridge reconfigured the major tectonic forces acting on the plate by replacing ridge push with slab pull along its north-western perimeter, causing lithospheric extension along pre-existing weaknesses. Large scale deformation observed in the models coincides with the seamount chains of Hawaii, Louisville, Tokelau, and Gilbert during our modelled time period of 62 to 42 Ma. We suggest that extensional stresses between 72 and 52 Ma are the likely cause of large parts of the formation of the Gilbert chain and that localised extension between 62 and 42 Ma could cause late-stage volcanism along the Musicians Volcanic Ridges. Our models demonstrate that early Cenozoic changes in Pacific plate driving forces only cause relatively minor changes in Pacific

  14. The Miocene mammal Necrolestes demonstrates the survival of a Mesozoic nontherian lineage into the late Cenozoic of South America

    Science.gov (United States)

    Rougier, Guillermo W.; Wible, John R.; Beck, Robin M. D.; Apesteguía, Sebastian

    2012-12-01

    The early Miocene mammal Necrolestes patagonensis from Patagonia, Argentina, was described in 1891 as the only known extinct placental "insectivore" from South America (SA). Since then, and despite the discovery of additional well-preserved material, the systematic status of Necrolestes has remained in flux, with earlier studies leaning toward placental affinities and more recent ones endorsing either therian or specifically metatherian relationships. We have further prepared the best-preserved specimens of Necrolestes and compared them with newly discovered nontribosphenic Mesozoic mammals from Argentina; based on this, we conclude that Necrolestes is related neither to marsupials nor placentals but is a late-surviving member of the recently recognized nontherian clade Meridiolestida, which is currently known only from SA. This conclusion is supported by a morphological phylogenetic analysis that includes a broad sampling of therian and nontherian taxa and that places Necrolestes within Meridiolestida. Thus, Necrolestes is a remnant of the highly endemic Mesozoic fauna of nontribosphenic mammals in SA and extends the known record of meridiolestidans by almost 45 million years. Together with other likely relictual mammals from earlier in the Cenozoic of SA and Antarctica, Necrolestes demonstrates the ecological diversity of mammals and the mosaic pattern of fauna replacement in SA during the Cenozoic. In contrast to northern continents, the Cenozoic faunal history of SA was characterized by a long period of interaction between endemic mammalian lineages of Mesozoic origin and metatherian and eutherian lineages that probably dispersed to SA during the latest Cretaceous or earliest Paleocene.

  15. Magnetostratigraphy of syntectonic growth strata and implications for the late Cenozoic deformation in the Baicheng Depression, Southern Tian Shan

    Science.gov (United States)

    Zhang, Zhiliang; Sun, Jimin; Tian, Zhonghua; Gong, Zhijun

    2016-03-01

    The collision between India and Eurasia in the Cenozoic has caused a series of intracontinental deformation in the foreland basins of Tian Shan, but there are debates about the timing of tectonic deformation and the relationship between tectonic uplift and sediment accumulation in the foreland basins. Based on the magnetostratigraphy of growth strata in the Baicheng Depression, Southern Tian Shan, we suggest that an episode of crustal shortening in the late Cenozoic evidenced by syntectonic growth strata in the Kelasu-Yiqikelike structural belt (KYSB) initiated at ∼5.3 Ma, since then the sedimentation rate accelerated abruptly and coarse molasse deposits accumulated. Combined with the results of growth strata on both flanks of Tian Shan and the fact that the Xiyu Formation on the southern limb of the Kasangtuokai Anticline was involved into the growth strata, we conclude that the period from ∼7-5 Ma to the early Pleistocene was one of the important episodes of intracontinental deformation in the foreland basins of Tian Shan, as a response to the Cenozoic collision between India and Eurasia.

  16. Cenozoic coupled basin-mountain and prospecting direction for sandstone-type uranium deposits in western Yunnan

    International Nuclear Information System (INIS)

    The initial forming time of Cenozoic basins in western Yunnan is at 14 Ma or so, it was coupling in the later period tectonic activity time of Lushui-Ruili arc dextral strike-slip fault belt in the eastern fringe and Nabang dextral strike-slip fault belt in the western fringe of Tengchong microplate. The evolution of Cenozoic basins is divided into two stages of sedimentary basin and reformed basin, the former was coupling in the strike-slip tectonic activity of orogen, and formed strike-slip basins, the latter was closely related with the uplift of the whole basins, and formed residual basins. It is considered that there exists two sorts of Cenozoic basins, and they are different in sedimentary evolution, volcanic activity and geographic sight etc., the metallogenic conditions of sandstone-type uranium deposits are also different. The most favourable basins for prospecting sandstone-type uranium deposits are those basins that keeps on uplifting in reformed basin stages, exists volcanic activity and deep incised low mountain-hill-river valley terraces in northern Tengchong area. (authors)

  17. Complex coacervation between colloidal silica and polyacrylamide

    International Nuclear Information System (INIS)

    Complex coacervation introduced by gamma-ray induced polymerization of acrylamide in colloidal silica was studied. The complex coaservate was formed by polymerization of acrylamide dissolved in a colloidal silica and methanol mixture. Complex coacervation (two-phase separation of the mixture) was observed only when the concentration of methanol was between 33 and 41 percent by volume, and the concentration of colloidal silica did not affect it. Although two phase separation was not influenced by pH change, the content of polyacrylamide was bigger in the equilibrated solution in acidic regions. It was, however, bigger in the complex coacervate at neutral and in alkaline regions. The content of polyacrylamide was also calculated from the particle diameter of complex coacervate measured by small angle X-ray scattering, and the result was well coincided with the analytical result. The stability of the complex coacervate against the addition of salts was better than that of the untreated colloidal silica. The rate of electrophoretic transport of the complex coacervate was also lower than that of the colloidal silica. From these observation it was concluded that the hydrophobic colloidal silica particles were protected by the surrounding hydrophilic polyacrylamide. (author)

  18. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    S.A. Mandavgane

    2010-12-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as aconcrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc.Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitatedfrom the sodium silicate by acidification. In the present work, conversion of about 90% of silica containedin RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The resultsshowed that silica obtained from RHA is mesoporous, has a large surface area and small particle size.Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usuallycontains carbon particles. Activated carbon embedded on silica has been prepared using the carbon alreadypresent in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67

  19. Microporous Silica Based Membranes for Desalination

    Directory of Open Access Journals (Sweden)

    João C. Diniz da Costa

    2012-09-01

    Full Text Available This review provides a global overview of microporous silica based membranes for desalination via pervaporation with a focus on membrane synthesis and processing, transport mechanisms and current state of the art membrane performance. Most importantly, the recent development and novel concepts for improving the hydro-stability and separating performance of silica membranes for desalination are critically examined. Research into silica based membranes for desalination has focussed on three primary methods for improving the hydro-stability. These include incorporating carbon templates into the microporous silica both as surfactants and hybrid organic-inorganic structures and incorporation of metal oxide nanoparticles into the silica matrix. The literature examined identified that only metal oxide silica membranes have demonstrated high salt rejections under a variety of feed concentrations, reasonable fluxes and unaltered performance over long-term operation. As this is an embryonic field of research several target areas for researchers were discussed including further improvement of the membrane materials, but also regarding the necessity of integrating waste or solar heat sources into the final process design to ensure cost competitiveness with conventional reverse osmosis processes.

  20. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    V.R. Shelke

    2011-01-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as a concrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc. Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitated from the sodium silicate by acidification. In the present work, conversion of about 90% of silica contained in RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The results showed that silica obtained from RHA is mesoporous, has a large surface area and small particle size. Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usually contains carbon particles. Activated carbon embedded on silica has been prepared using the carbon already present in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67][DOI: http://dx.doi.org/10.9767/bcrec.5.2.793.63-67

  1. Influence of Silica Fume on Normal Concrete

    Directory of Open Access Journals (Sweden)

    Debabrata Pradhan

    2013-09-01

    Full Text Available The incorporation of silica fume into the normal concrete is a routine one in the present days to produce the tailor made high strength and high performance concrete. The design parameters are increasing with the incorporation of silica fume in conventional concrete and the mix proportioning is becoming complex. The main objective of this paper has been made to investigate the different mechanical properties like compressive strength, compacting factor, slump of concrete incorporating silica fume. In this present paper 5 (five mix of concrete incorporating silica fume are cast to perform experiments. These experiments were carried out by replacing cement with different percentages of silica fume at a single constant water-cementitious materials ratio keeping other mix design variables constant. The silica fume was replaced by 0%, 5%, 10%, 15% and 20% for water-cementitious materials (w/cm ratio for 0.40. For all mixes compressive strengths were determined at 24 hours, 7 and 28 days for 100 mm and 150 mm cubes. Other properties like compacting factor and slump were also determined for five mixes of concrete.

  2. International Search for Life in Ocean Worlds

    Science.gov (United States)

    Sherwood, B.

    2015-12-01

    We now know that our solar system contains diverse "ocean worlds." One has abundant surface water and life; another had significant surface water in the distant past and has drawn significant exploration attention; several contain large amounts of water beneath ice shells; and several others evince unexpected, diverse transient or dynamic water-related processes. In this century, humanity will explore these worlds, searching for life beyond Earth and seeking thereby to understand the limits of habitability. Of our ocean worlds, Enceladus presents a unique combination of attributes: large reservoir of subsurface water already known to contain salts, organics, and silica nanoparticles originating from hydrothermal activity; and able to be sampled via a plume predictably expressed into space. These special circumstances immediately tag Enceladus as a key destination for potential missions to search for evidence of non-Earth life, and lead to a range of potential mission concepts: for orbital reconnaissance; in situ and returned-sample analysis of plume and surface-fallback material; and direct sulcus, vent, cavern, and ocean exploration. Each mission type can address a unique set of science questions, and would require a unique set of capabilities, most of which are not yet developed. Both the questions and the capability developments can be sequenced into a programmatic precedence network, the realization of which requires international cooperation. Three factors make this true: exploring remote oceans autonomously will cost a lot; the Outer Space Treaty governs planetary protection; and discovery of non-Earth life is an epochal human imperative. Results of current planning will be presented in AGU session 8599: how ocean-world science questions and capability requirements can be parsed into programmatically acceptable mission increments; how one mission proposed into the Discovery program in 2015 would take the next step on this path; the Decadal calendar of

  3. Our Changing Oceans: All about Ocean Acidification

    International Nuclear Information System (INIS)

    The consequences of ocean acidification are global in scale. More research into ocean acidification and its consequences is needed. It is already known, for example, that there are regional differences in the vulnerability of fisheries to acidification. The combination of other factors, such as global warming, the destruction of habitats, overfishing and pollution, need to be taken into account when developing strategies to increase the marine environment’s resilience. Among steps that can be taken to reduce the impact is better protection of marine coastal ecosystems, such as mangrove swamps and seagrass meadows, which will help protect fisheries. This recommendation was one of the conclusions of a three-day workshop attended by economists and scientists and organized by the IAEA and the Centre Scientifique de Monaco in November 2012. In their recommendations the workshop also stressed that the impact of increasing ocean acidity must be taken into account in the management of fisheries, particularly where seafood is a main dietary source

  4. Transport of colloidal silica in unsaturated sand: Effect of charging properties of sand and silica particles.

    Science.gov (United States)

    Fujita, Yosuke; Kobayashi, Motoyoshi

    2016-07-01

    We have studied the transport of colloidal silica in various degrees of a water-saturated Toyoura sand column, because silica particles are widely used as catalyst carriers and abrasive agents, and their toxicity is reported recently. Since water-silica, water-sand, and air-water interfaces have pH-dependent negative charges, the magnitude of surface charge was controlled by changing the solution pH. The results show that, at high pH conditions (pH 7.4), the deposition of colloidal silica to the sand surface is interrupted and the silica concentration at the column outlet immediately reaches the input concentration in saturated conditions. In addition, the relative concentration of silica at the column outlet only slightly decreases to 0.9 with decreasing degrees of water saturation to 38%, because silica particles are trapped in straining regions in the soil pore and air-water interface. On the other hand, at pH 5 conditions (low pH), where sand and colloid have less charge, reduced repulsive forces result in colloidal silica attaching onto the sand in saturated conditions. The deposition amount of silica particles remarkably increases with decreasing degrees of water saturation to 37%, which is explained by more particles being retained in the sand column associated with the air-water interface. In conclusion, at higher pH, the mobility of silica particles is high, and the air-water interface is inactive for the deposition of silica. On the other hand, at low pH, the deposition amount increases with decreasing water saturation, and the particle transport is inhibited. PMID:27045635

  5. Effects of silica sol on bentonite

    International Nuclear Information System (INIS)

    Document available in extended abstract form only. Compacted bentonite will be used in Sweden as an engineered barrier in the disposal of nuclear waste, mainly due to bentonites sorption and swelling capacity, where the latter property is warranted in order to seal possible future intersecting fractures. However during the actual construction and deposition period other grouting agents must be used in order to seal already existing fractures. In Sweden Silica sol is currently being investigated in situ at Aespoe Hard Rock Laboratory as a fine fracture (< 100 μm) grouting agent by injection. During this period, there is a plausible risk of Silica sol coming into contact with bentonite. The effect of Silica sol, either in colloidal form or as a gel, on the chemical and physical properties of bentonite has not been properly addressed and has to be further investigated. The Silica sol (Meyco MP320, EKA Chemicals) consists of amorphous SiO2 particles, average size approximately 20 nm. Due to the small particle size Silica sol can penetrate and seal finer fractures than more coarse grouting agents commonly used. Upon injection NaCl (approx 0.3 M) is used as a gel accelerator, leading to a hydrological barrier in the form of a ductile gel after < 1 hour, which then hardens with time (months) increasing its strength significantly, depending on water content, ionic strength and temperature. Upon aggregation, either due to high ionic strength or drying, the silica colloids aggregate seemingly irreversible forming siloxane bonds by condensation of the silanol surface groups. These silanol groups can react at the montmorillonite edges in a similar way. In a worst case scenario the Silica sol would act as an inorganic glue, creating a pillared montmorillonite or modify the edges of the clay particles. Such effects would irreversibly reduce the overall swelling capacity of the affected bentonite. An experimental program has been developed to characterize the Silica sol

  6. Blue ocean strategy.

    Science.gov (United States)

    Kim, W Chan; Mauborgne, Renée

    2004-10-01

    Despite a long-term decline in the circus industry, Cirque du Soleil profitably increased revenue 22-fold over the last ten years by reinventing the circus. Rather than competing within the confines of the existing industry or trying to steal customers from rivals, Cirque developed uncontested market space that made the competition irrelevant. Cirque created what the authors call a blue ocean, a previously unknown market space. In blue oceans, demand is created rather than fought over. There is ample opportunity for growth that is both profitable and rapid. In red oceans--that is, in all the industries already existing--companies compete by grabbing for a greater share of limited demand. As the market space gets more crowded, prospects for profits and growth decline. Products turn into commodities, and increasing competition turns the water bloody. There are two ways to create blue oceans. One is to launch completely new industries, as eBay did with online auctions. But it's much more common for a blue ocean to be created from within a red ocean when a company expands the boundaries of an existing industry. In studying more than 150 blue ocean creations in over 30 industries, the authors observed that the traditional units of strategic analysis--company and industry--are of limited use in explaining how and why blue oceans are created. The most appropriate unit of analysis is the strategic move, the set of managerial actions and decisions involved in making a major market-creating business offering. Creating blue oceans builds brands. So powerful is blue ocean strategy, in fact, that a blue ocean strategic move can create brand equity that lasts for decades. PMID:15559577

  7. Major element, REE, and Pb, Nd and Sr isotopic geochemistry of Cenozoic volcanic rocks of eastern China: implications for their origin from suboceanic-type mantle reservoirs

    Science.gov (United States)

    Basu, A.R.; Wang, Junwen; Huang, Wankang; Xie, Guanghong; Tatsumoto, M.

    1991-01-01

    Major- and rare-earth-element (REE) concentrations and UThPb, SmNd, and RbSr isotope systematics are reported for Cenozoic volcanic rocks from northeastern and eastern China. These volcanic rocks, characteristically lacking the calc-alkaline suite of orogenic belts, were emplaced in a rift system which formed in response to the subduction of the western Pacific plate beneath the eastern Asiatic continental margin. The rocks sampled range from basanite and alkali olivine basalt, through olivine tholeiite and quartz tholeiite, to potassic basalts, alkali trachytes, pantellerite, and limburgite. These rock suites represent the volcanic centers of Datong, Hanobar, Kuandian, Changbaishan and Wudalianchi in northeastern China, and Mingxi in the Fujian Province of eastern China. The major-element and REE geochemistry is characteristic of each volcanic suite broadly evolving through cogenetic magmatic processes. Some of the outstanding features of the isotopic correlation arrays are as follows: (1) NdSr shows an anticorrelation within the field of ocean island basalts, extending from the MORB end-member to an enriched, time-averaged high Rb Sr and Nd Sr end-member (EM1), (2) SrPb also shows an anticorrelation, similar to that of Hawaiian and walvis Ridge basalts, (3) NdPb shows a positive correlation, and (4) the 207Pb 204Pb vs 206Pb 204Pb plot shows linear arrays parallel to the general trend (NHRL) for MORB on both sides of the geochron, although in the 208Pb 204Pb vs 206Pb 204Pb plot the linear array is significantly displaced above the NHRL in a pattern similar to that of the oceanic island basalts that show the Dupal signatures. In all isotope correlation patterns, the data arrays define two different mantle components-a MORB-like component and an enriched mantle component. The isotopic data presented here clearly demonstrate the existence of Dupal compositions in the sources of the continental volcanic rocks of eastern China. We suggest that the subcontinental mantle

  8. Geochemical Characteristics of Cenozoic Jining Basalts of the Western North China Craton: Evidence for the Role of the Lower Crust, Lithosphere, and Asthenosphere in Petrogenesis

    Directory of Open Access Journals (Sweden)

    Kung-Suan Ho

    2011-01-01

    Full Text Available The Jining volcanic field located in the southern margin of the Mongolian plateau and the western North China Block consists of four rock types: quartz tholeiite, olivine tholeiite, alkali olivine basalt and basanite. These rocks have a wide range of K-Ar ages from ~36 to < 0.2 Ma. The early volcanism was voluminous and dominated by flood-type fissure eruptions of tholeiites, whereas the later phase was represented by sparse eruptions of basanitic lavas. Thirty-six samples analyzed in this study show a wide range in SiO2 contents from 44% ~ 54%. They all are sodium-rich and high-Ti basalts that, however, show marked isotopic variations between two end-members: (1 tholeiites that have higher 87Sr/86Sr of 0.7048 ~ 0.7052, and lower _ of -0.8 to -2.4 and Pb isotope ratios (206Pb/204Pb of 16.9 ~ 17.2, 207Pb/204Pb of 15.3 ~ 15.4 and 208Pb/204Pb of 37.1 ~ 37.7; and (2 basanites that have lower 87Sr/86Sr of 0.7035 ~ 0.7044, and higher _ of +1.3 to +4.9 and Pb isotope ratios (206Pb/204Pb of 17.7 ~ 18.0, 207Pb/204Pb of 15.4 ~ 15.5 and 208Pb/204Pb of 37.8 ~ 38.2. Alkali olivine basalt that occurs as a subordinate rock type is geochemically similar to the basanites, but isotopically similar to the tholeiites, characterized by the highest 87Sr/86Sr ratio among the three basaltic suites, coupled with a low Nb/U value (~33. In Sr-Nd-Pb isotopic plots, the tholeiites extend toward the EM1 (i.e., enriched mantle type 1 component, whereas the basanites trend toward the Indian Ocean mid-ocean ridge basalt (MORB field. Adopting the _ model by Morris and Hart (1983, we suggest that the Oligocene tholeiites were generated by high degree melting of an ascended asthenospheric mantle that was contaminated with a large amount of EM1-type continental lithospheric material during the early Cenozoic. On the other hand, the late Tertiary and Quaternary basanites may have originated predominantly from a depleted asthenosphere component with small but variable degrees of

  9. Silica ecosystem for synergistic biotransformation

    Science.gov (United States)

    Mutlu, Baris R.; Sakkos, Jonathan K.; Yeom, Sujin; Wackett, Lawrence P.; Aksan, Alptekin

    2016-06-01

    Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system.

  10. Time series analysis of Cenozoic era sea level and paleotemperature data

    Science.gov (United States)

    Rosenfield, George H.; Huffman, Tod E.

    1983-01-01

    A statistical analysis of Cenozoic era sea level and paleotemperature data was performed to determine the cycles of each data set and the correspondence between them. Accordingly, each of the four time series were first analyzed independently in the univariate mode of a spectral analysis. The two basic data sets were then analyzed in a paired cross-spectral analysis. The prominent periodic cycles remaining in the data sets after linear trend removal, were: sea level surface from seismic stratigraphy--9.6 million years, updated version of sea level surface from seismic stratigraphy--9.5 million years, continental paleotemperatures from paleobotanical interpretations--9.6 million years, and marine paleotemperatures from foraminiferal isotopic data--12.7 million years. The cross-correlation properties between the data sets of continental paleotemperatures from paleobotanical interpretations and sea level surface from seismic stratigraphy at the common prominent period of 9.6 million years were: (1) The squared coherency value which measures cross correlation between the two data sets has the value 0.30, and (2) the amount by which the continental paleotemperatures from paleobotanical interpretations data lags the sea level surface from seismic stratigraphy data is 2.70 million years.

  11. Late Cenozoic Tectonic Deformation in the Dongsha Islands and Adjacent Sea Area

    Institute of Scientific and Technical Information of China (English)

    WU Shiguo(吴时国); LIU Zhan(刘展); WANG Wanyin(王万银); GUO Junhua(郭军华); T. Lüdmann; H. K. Wong

    2003-01-01

    Dongsha Island and the adjacent sea area locate at the northern continental margin of the South China Sea (SCS), and is connected to the east by the Manila Trench. Analyses of seismic stratigraphy and gravity, magnetic and drilling wells data led to the discovery of three post-fault sequences (V, VI, VII). Extensive tectonic uplift, magma activity and erosion occurred in Dongsha Island and the adjacent area, where most of the faults in the northeastern SCS were still active during Pliocene and Quaternary. Two groups of faults trending NEE and NW were developed during Late Cenozoic. We conclude that three important tectonic movements, especially Dongsha movement (4.4-5.2 Ma) and Liuhua movement (1.4-1.89 Ma), controlled the structural framework in the Dongsha rise; whose deformation in the east is stronger than that in the west and whose stress field variation suggests that the tectonic uplift in the study area contributed to magmato-tectonic events correlated to the main collision phases between the East China and Taiwan 5-3 and 3-0 Ma ago.

  12. Book Review: Late Cenozoic Climate Change in Asia: Loess, Monsoon and Monsoon-arid Environment Evolution

    Science.gov (United States)

    Clemens, Steven C.

    2015-01-01

    Loess-Paleosol deposits drape >500,000 km2 of eastern China, spanning environments from the humid, monsoon-influenced regions near the coast to the arid, westerlies-dominated regions inland. Sections, up to hundreds of meters thick, are exposed in deeply incised river valleys and can be accessed as well by drilling. Combined, the high sedimentation rates and extensive geographic coverage make these sections unique among global terrestrial sediment archives. The Chinese loess-paleosol sequences, and the arid interior regions to the northwest, record diverse aspects of geologic and environmental change ranging from the tectonic evolution of the Tibetan Plateau (106 year time scale) through glacial-interglacial scale changes in global ice volume and greenhouse gasses (105 year time scale) on down through the orbital (104 years) to millennial and centennial scale events (103-102 year) relevant to the underpinnings of human interactions with changing environmental pressures. 'Late Cenozoic Climate Chang in Asia: Loess, Monsoon and Monsoon-arid Environment Evolution' is a timely contribution that synthesizes findings derived from the extensive work in these areas, places the findings in the broader context of global climate change and helps to define avenues for future research.

  13. High=porosity Cenozoic carbonate rocks of South Florida: progressive loss of porosity with depth

    Science.gov (United States)

    Halley, Robert B.; Schmoker, James W.

    1983-01-01

    Porosity measurements by borehole gravity meter in subsurface Cenozoic carbonates of South Florida reveal an extremely porous mass of limestone and dolomite which is transitional in total pore volume between typical porosity values for modern carbonate sediments and ancient carbonate rocks. A persistent decrease of porosity with depth, similar to that of chalks of the Gulf Coast, occurs in these rocks. Carbonate strata with less than 20% porosity are absent from the rocks studied here. Aquifers and aquicludes cannot be distinguished on the basis of porosity. Aquifers are not exceptionally porous when compared to other Tertiary carbonate rocks in South Florida. Permeability in these strata is governed more by the spacial distribution of pore space and matrix than by total volume of porosity present. Dolomite is as porous as, or slightly less porous than, limestones in these rocks. This observation places limits on any model proposed for dolomitization and suggests that dolomitization does not take place by a simple ion-for-ion replacement of magnesium for calcium. Dolomitization may be selective for less porous limestone, or it may involve the incorporation of significant amounts of carbonate as well as magnesium into the rock. The great volume of pore space in these rocks serves to highlight the inefficiency of early diagenesis in reducing carbonate porosity and to emphasize the importance of later porosity reduction which occurs during the burial or late near-surface history of limestones and dolomites.

  14. Fission track dating of the Cenozoic uplift in Mabian area, southern Sichuan Province, China

    Institute of Scientific and Technical Information of China (English)

    AN YanFen; HAN ZhuJun; WAN JingLin

    2008-01-01

    The apparent ages of samples are obtained from fission track dating of apatite samples collected from the fault zones in Mabian area, southern Sichuan Province.In addition, thermal history is simulated from the obtained data by applying AFTSolve Program, to acquire the thermal evolution history of the samples.The result shows that tectonically the Mabian area was relatively stable between 25 and 3 Ma, compared to the inner parts and other marginal areas of the Tibetan Plateau.The studied area had little response to the rapid uplift events that occurred for several times in the Tibetan Plateau during 25-3 Ma.The latest thermal event related to the activity of the Lidian fault zone (about 8 Ma) is later than that of the Ebian fault zone (18-15 Ma ) to the west, indicating to some extent that the evolution of fault activity in the Mabian area has migrated from west to east.The latest extensive tectonic uplift occurred since about 3 Ma.As compared with the Xianshuihe fault zone, the Mabian area is closer to the eastern margin of the plateau, while the time of fast cooling event in this area is later than that in the southeast segment of the Xianshuihe fault zone (3.6-3.46 Ma).It appears to support the assumption of episodic uplift and stepwise outward extension of the eastern boundary of the Tibetan Plateau in late Cenozoic.

  15. Mongolian plateau: Evidence for a late Cenozoic mantle plume under central Asia

    Science.gov (United States)

    Windley, Brian F.; Allen, Mark B.

    1993-04-01

    The 2500 x 700 km Mongolian plateau (average elevation 2000 m) is situated between the Altai orogen and the Siberian craton and occupies much of Mongolia and Transbaikalia in Russia. The plateau is characterized by (1) basin and range topography and two major domes(Hentai, 600 x 300 km, and Hangai, 800 x 550 km), where altitudes reach 3905 m; (2) lithosphere that is thinner than adjacent areas (minimum ˜50 km); (3) elevated heat flow (up to 120 mW/m2); (4) dominantly alkaline basaltic volcanism in the form of cones, lava fields, and volcanic plateaus mostly of Miocene-Quaternary age, and (5) rifts, including Baikal (main evolution in the Pliocene-Quaternary), Tunka (Oligocene-early Miocene), and Hobsogol (Pliocene-Quaternary). Existing models explain these features in terms of diapiric upwelling of a mantle asthenolith below the main rifts and/or as a long-distance effect of the India-Asia collision. We propose that the late Cenozoic uplift of the whole Mongolian plateau and associated rifting, magmatism, high heat flow, and lithospherec thinning are not externally driven by the India-Asia collision, but are the expression of the interaction of a mantle plume with overlying lithosphere. Some rifts link and interact with major strike-slip faults, such as the Bolnai. Such faults may be the major expression of the India-Asia collision in this region.

  16. Detrital thermochronology of the Alaska Range: Exhumation during Cenozoic subduction and translation

    Science.gov (United States)

    Lease, R. O.; Haeussler, P. J.; O'Sullivan, P. B.

    2014-12-01

    Detrital thermochronology of modern river sands from the Alaska Range quantifies the timing, extent, and magnitude of regional exhumation during Cenozoic subduction and translation along the southern Alaska margin. This detrital approach provides an effective way to quantify regional exhumation in remote areas like Alaska, where sampling bedrock and acquiring exhumation data for large areas requires tremendous effort. We present apatite and zircon fission track (FT) and zircon U/Pb ages from 13 catchments that span 450 km east to west along the Alaska Range. Zircon U/Pb ages indicate a dominant igneous first-cycle source that comprises >90% of most age distributions, even in areas where igneous outcrop comprises local structures. In addition, most catchments display a 25-20 Ma peak that indicates regional exhumation concurrent with the onset of Yakutat flat slab subduction along the southern Alaska margin. Finally, some catchments display a 50-45 Ma peak that suggests localized exhumation during and after spreading ridge subduction along the southern Alaska margin. To estimate age-elevation relationships in each catchment, we employ recent Bayesian inverse modeling of cooling ages and hypsometries. We demonstrate the utility of this technique for the Ruth and Kahiltna catchments draining Denali, where new detrital data, as well as a previous bedrock vertical transect, both suggest a 7-6 Ma onset of rapid erosion.

  17. First fossil evidence of Connaraceae R. Br. from Indian Cenozoic and its phytogeographical significance

    Indian Academy of Sciences (India)

    Mahasin Ali Khan; Subir Bera

    2016-07-01

    Fossil leaflet impression described here as a new species Rourea miocaudata sp. nov., showing close resemblance with the modern leaflets of Rourea caudata Planch. (Connaraceae R. Br.), has been recorded from the lower part of the Siwalik sediments (Dafla Formation, middle–upper Miocene) exposed at the road-cutting section of Pinjoli area in West Kameng district, Arunachal Pradesh. The importantmorphological characters of the fossil are its narrow elliptic leaflet, cuneate base, long caudate apex, entire margin, eucamptodromous to brochidodromous secondary veins, presence of intersecondary veins, percurrent and reticulate tertiary veins and orthogonally reticulate quaternary veins. This is the first authentic record of the occurrence of leaflet comparable to R. caudata of Connaraceae from the Cenozoic sediments of India and abroad. At present R. caudata does not grow in India and is restricted only in southeast Asia especially in China and Myanmar. This taxon probably migrated to these southeast Asian regions after lower Siwalik sedimentation (middle–upper Miocene) due to climatic change causedby post-Miocene orogenic movement of the Himalaya. The recovery of this species and other earlierdescribed evergreen taxa from the same formation, suggests the existence of a tropical, warm and humid climatic conditions during the depositional period.

  18. First fossil evidence of Connaraceae R. Br. from Indian Cenozoic and its phytogeographical significance

    Science.gov (United States)

    Khan, Mahasin Ali; Bera, Subir

    2016-07-01

    Fossil leaflet impression described here as a new species Rourea miocaudata sp. nov., showing close resemblance with the modern leaflets of Rourea caudata Planch. (Connaraceae R. Br.), has been recorded from the lower part of the Siwalik sediments (Dafla Formation, middle-upper Miocene) exposed at the road-cutting section of Pinjoli area in West Kameng district, Arunachal Pradesh. The important morphological characters of the fossil are its narrow elliptic leaflet, cuneate base, long caudate apex, entire margin, eucamptodromous to brochidodromous secondary veins, presence of intersecondary veins, percurrent and reticulate tertiary veins and orthogonally reticulate quaternary veins. This is the first authentic record of the occurrence of leaflet comparable to R. caudata of Connaraceae from the Cenozoic sediments of India and abroad. At present R. caudata does not grow in India and is restricted only in southeast Asia especially in China and Myanmar. This taxon probably migrated to these southeast Asian regions after lower Siwalik sedimentation (middle-upper Miocene) due to climatic change caused by post-Miocene orogenic movement of the Himalaya. The recovery of this species and other earlier-described evergreen taxa from the same formation, suggests the existence of a tropical, warm and humid climatic conditions during the depositional period.

  19. Cenozoic pulsed deformation history of northeastern Tibetan Plateau reconstructed from fission-track thermochronology

    Science.gov (United States)

    Wang, Xiuxi; Song, Chunhui; Zattin, Massimiliano; He, Pengju; Song, Ai; Li, Jijun; Wang, Qiangqiang

    2016-03-01

    The synorogenic basin deposits and bedrocks of their source terranes within and along the Tibetan Plateau contain fundamental information regarding the spatiotemporal evolution of the largest orogenic plateau on Earth. The Guide-Xining region is located on the northeastern portion of the Tibet and its Eocene-early Pleistocene basin succession is well preserved. By integrating apatite fission-track thermochronology from sedimentary and basement samples, with heavy minerals and paleocurrent data, we decipher an almost complete sequence of exhumation and depositional events during the Cenozoic. Our data indicates that the initial deformation along the Guide-Xining region occurred since the Eocene, with the reorganization of the regional tectonomorphology and the formation of a broad basin. Thereafter, this single large basin was disrupted by multiple episodes of exhumation and deformation. Our study illuminate that the multiple-stage active processes (occurred at 49-42, 36-32, 23-19, 16-13 and 8-4 Ma) work together to produce the current NE Tibetan Plateau.

  20. Glass melt inclusion in clinopyroxene from Linqu Cenozoic basalt, Shandong Province, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hongfu; Eizo Nakamura; ZHANG Jin; Ishikawa Akira

    2006-01-01

    Cenozoic basalts from the Linqu County, Shandong Province, China entrain some clinopyroxene crystals, of which many contain abundant glass melt inclusions. These melt inclusions are extremely irregular in shape with most grain sizes in a range of 10-50 μm and coexist with low-Mg# olivines, labradorites and Ca-rich potassium feldspars. In-situ major and trace element analyses show that the glass melt inclusions are high in alkalis (Na2O+K2O > 10 wt%), SiO2 (>54 wt%), CaO and FeO (>4 wt%), but low in MgO (Mg# < 20), and have LREE enrichments ((Ce/Yb)cn = 11.6-16.4) and apparently positive Eu anomalies (Eu/Eu*>2), thus having phonolitic compositions. The compositional features of clinopyroxene crystals, glass melt inclusions and their coexistent minerals suggest that these melt inclusions were exotic melts in clinopyroxenes trapped prior to their entrainment in the host basalt. The discovery of these melt inclusions provides a new approach to further investigating the evolution of Meso- zoic lithospheric mantle beneath the southeastern North China Craton.

  1. Thermochronological constraints on two pulses of Cenozoic high-K magmatism in eastern Tibet

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The previously published U-Pb and 40Ar/39Ar ages and our 21 newly-obtained 40Ar/39Ar ages suggest that the Cenozoic magmatism in eastern Tibet and Indochina occurred in two episodes, each with distinctive geochemical signatures, at (40-28) Ma and (16-0) Ma. The older rocks are localized along the major strike-slip faults such as the Jinsha-Red River fault system and erupted synchronously with transpression. The younger rocks are widely distributed in rift basins and coeval with the east-west extension of Tibet and eastern Asia. Combining with their geochemical data, we consider that the earlier magmatic phase was generated by continental subduction, while the later volcanic phase was caused by decompression melting of a recently meta- somatically-altered, depleted mantle source. The magmatic gap between the two igneous pulses represents an important geodynamic transition in the evolution of eastern Tibet, from the processes controlled mainly by crustal deformation to those largely dominated by mantle tectonics.

  2. Late Cenozoic deformation of the Gavrovo and Ionian zones in NW Peloponnesos (Western Greece

    Directory of Open Access Journals (Sweden)

    S. Tsaila-Monopoli

    2000-06-01

    Full Text Available The structural deformation of Mesozoic-Tertiary sediments of the Ionian and Gavrovo zones in NW Peloponnesos is related to the propagation of a fold-thrust system during the Cenozoic. The sediments of the Gavrovo zone have been deformed by high angle reverse faulting generating an imbricate fan. Skolis mountain represents the Gavrovo thrust front. The detachment occurred in the underlying flysch of the Ionian zone. The Ionian zone has also been affected by shortening above a detachment horizon situated in the lower horizons of Triassic evaporites. The main compressional structure of the Ionian zone is a broad anticline revealed by a seismic survey west of Skolis mountain. The Gavrovo-sheet emplacement caused the downthrow and bending of the eastern part of the Ionian zone followed by halokinesis of Triassic evaporites to the west. Post-compressional normal faulting has predominated since the Pliocene, resulting in the formation of the Kato Achaia and Simopoulo basins in the peripheral area of Skolis mountain. Diapirs of Triassic evaporites occur in the mentioned basins that complicate the tectonic pattern in front of the Skolis thrust.

  3. Late cenozoic deformation of the Gavrovo and Ionian zones in NW Peloponnesos (Western Greece)

    Energy Technology Data Exchange (ETDEWEB)

    Kamberis, E.; Sotiropoulos, S.; Aximniotou, O. [Hellenic Petroleum, Exploration and Exploitation of Hydrocarbons Division, Maroussi, Athens (Greece); Tsaila-Monopoli, S. [Patras Univ., Patras (Greece). Dept. of Geology; Ioakim, C. [Institute of Geological and Mineral Explorations, Athens (Greece)

    2000-10-01

    The structural deformation of Mesozoic-Tertiary sediments of the Ionian and Gavrovo zones in NW Peloponnesos is related to the propagation of a fold-thrust system during the Cenozoic. The sediments of the Gavrovo zone have been deformed by high angle reverse faulting generating an imbricate fan. Skolis mountain represents the Gavrovo thrust front. The detachment occurred in the underlying flysch of the Ionian zone. The Ionian zone has also been affected by shortening above a detachment horizon situated in the lower horizons of Triassic evaporites. The main compressional structure of the Ionian zone is a broad anticline revealed by a seismic survey west of Skolis mountain. The Gavrovo-sheet emplacement caused the downthrow and bending of the eastern part of the Ionian zone followed by halokinesis of Triassic evaporites to the west. Post-compressional normal faulting has predominated since the Pliocene, resulting in the formation of the Kato Achaia and Simopoulo basins in the peripheral area of Skolis mountain. Diapirs of Triassic evaporites occur in the mentioned basins that complicate the tectonic pattern in front of the Skolis thrust.

  4. The Cenozoic mantle magmatism and motion of lithosphere on the north margin of the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    罗照华; 肖序常; 曹永清; 莫宣学; 苏尚国; 邓晋福; 张文会

    2001-01-01

    Geodynamic properties and evolution of the lithosphere on the north margin of the Tibetan Plateau are recently hot topics to geoscientists in the world. Have the northern plates been subducting underneath the Plateau? It is still an unsolved problem. One of the keys to solving this problem is to understand the genetic processes of Cenozoic magmas on the north margin of the Tibetan Plateau. However, there is no enough evidence supporting the subduction model. In contrast, a series of evidence indicates that collision-induced huge shearing faults and large-scale crust shortening played a main role in lithosphere motion on the north margin of the Tibetan Plateau. The mantle-derived igneous rocks strictly distribute at the intersections of large strike-slip faults on the north margin of the Plateau. Generation of magmas may be related to local exten-sional condition induced by strike-slipping faults, which lead to lithosphere gravitational instability and collapse, as well as upwelling of the deep hot materi

  5. Deep Mechanical Background for the Cenozoic Volcanism in the Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    Xiong Xiong; Wang Jiye; Teng Jiwen

    2005-01-01

    The principle prerequisite for the formation of a volcano is the generation of a channel for magma transportation. There is little research on the deep mechanical mechanism for the formation of a magma transportation channel in the Tibetan plateau.Based on the subcrustal mantle convection-generated stress field inversed by gravity anomalies, together with its relationship to the Cenozoic volcanism in the plateau, and the mechanism of crustal fracture formation, as well as the numerical results of the evolution of mantle convection beneath the plateau, this paper investigates the deep mechanical mechanism for the formation of a magma transportation channel in the Tibetan plateau. There are two significant extensional convection-generated stress zones beneath the plateau, in which the volcanic rocks in the central and northern parts of the plateau are distributed. The Linzizong volcanism in southern Tibet correlates the upwelling mantle flow prior to the India-Asia collision or during the early stage of the collision. The magnitude of the stress is ~100 MPa, which is the same order of force that causes crustal fractures. The evidence implies that the mantle convection-generated stress is one of the principle causes of crustal fractures, and furthermore, the formation of the magma transportation channel in the Tibetan plateau.

  6. Cenozoic rejuvenation events of Massif Central topography (France): Insights from cosmogenic denudation rates and river profiles

    Science.gov (United States)

    Olivetti, Valerio; Godard, Vincent; Bellier, Olivier

    2016-06-01

    The French Massif Central is a part of the Hercynian orogenic belt that currently exhibits anomalously high topography. The Alpine orogenesis, which deeply marked Western European topography, involved only marginally the Massif Central, where Cenozoic faulting and short-wavelength crustal deformation is limited to the Oligocene rifting. For this reason the French Massif Central is a key site to study short- and long-term topographic response in a framework of slow tectonic activity. In particular the origin of the Massif Central topography is a topical issue still debated, where the role of mantle upwelling is invoked by different authors. Here we present a landscape analysis using denudation rates derived from basin-averaged cosmogenic nuclide concentrations coupled with longitudinal river profile analysis. This analysis allows us to recognize that the topography of the French Massif Central is not fully equilibrated with the present base level and in transient state. Our data highlight the coexistence of out-of-equilibrium river profiles, incised valleys, and low cosmogenically derived denudation rates ranging between 40 mm/kyr and 80 mm/kyr. Addressing this apparent inconsistency requires investigating the parameters that may govern erosion processes under conditions of reduced active tectonics. The spatial distribution of denudation rates coupled with topography analysis enabled us to trace the signal of the long-term uplift history and to propose a chronology for the uplift evolution of the French Massif Central.

  7. Magmatic zoning of Late Cenozoic volcanism in Central Mongolia: Relation with the mantle plume

    Science.gov (United States)

    Kudryashova, E. A.; Yarmolyuk, V. V.; Kozlovsky, A. M.; Savatenkov, V. M.

    2010-05-01

    The concentric zonal structure of the Late Cenozoic volcanism areal in Central Mongolia which is situated on the territory of the Khangai vault has been educed. The central part of the structure conforms to the axial part of the vault and is presented with volcanic fields of the Watershed graben and newest valley flows. The peripheral zone is presented with volcanic fields located along the vault frame (Taryat graben, Lake Valley graben, and grabens of the Orkhon-Selenga interfluve). The structural zoning of the areal comports with the substantial zoning of volcanism products. The rocks of the central part have isotopic (Sr, Nd, Pb) and geochemical characteristics conforming to the most primitive (like PREMA) compositions of mantle sources of magmatism. Magmatism sources in the peripheral zone of the volcanic areal, besides the PREMA mantle, contained a substance of enriched mantle like EMI. The character of substantial and structural zoning of volcanism is caused by the influence of the mantle plume on the Central Asia lithosphere. According to geophysical and isotopic-geochemical data, this plume had a lower mantle nature.

  8. Groundfish overfishing, diatom decline, and the marine silica cycle: Lessons from Saanich Inlet, Canada, and the Baltic Sea cod crash

    Science.gov (United States)

    Katz, Timor; Yahel, Gitai; Yahel, Ruthy; Tunnicliffe, Verena; Herut, Barak; Snelgrove, Paul; Crusius, John; Lazar, Boaz

    2009-12-01

    In this study, we link groundfish activity to the marine silica cycle and suggest that the drastic mid-1980s crash of the Baltic Sea cod (Gadus morhua) population triggered a cascade of events leading to decrease in dissolved silica (DSi) and diatom abundance in the water. We suggest that this seemingly unrelated sequence of events was caused by a marked decline in sediment resuspension associated with reduced groundfish activity resulting from the cod crash. In a study in Saanich Inlet, British Columbia, Canada, we discovered that, by resuspending bottom sediments, groundfish triple DSi fluxes from the sediments and reduce silica accumulation therein. Using these findings and the available oceanographic and environmental data from the Baltic Sea, we estimate that overfishing and recruitment failure of Baltic cod reduced by 20% the DSi supply from bottom sediments to the surface water leading to a decline in the diatom population in the Baltic Sea. The major importance of the marginal ocean in the marine silica cycle and the associated high population density of groundfish suggest that groundfish play a major role in the silica cycle. We postulate that dwindling groundfish populations caused by anthropogenic perturbations, e.g., overfishing and bottom water anoxia, may cause shifts in marine phytoplankton communities.

  9. Effect of Mineral Admixtures on Alkali-Silica Reaction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chengzhi; WANG Aiqin

    2008-01-01

    The influence of silica fume,slag and fly ash on alkali-silica reaction under the condition of 70℃ is studied.The results show that silica,slag and fly ash may inhibit alkali-silica reaction only under suitable content.When the content is less than 10%,silica fume does not markedly influence the expansion of alkali-silica reaction.When the content is 15%-20%,silica fume only may delay the expansion of alkali-silica reaction.When the content is 30%-70%,slag may only delay the expansion of alkali-silica reaction,but cannot inhibit the expansion of alkali-silica reaction.When the content is 10%,fly ash does not markedly influence the expansion of alkali-silica reaction.When the content is 20%-30%,fly ash may only delay the expansion of alkali-silica reaction,but cannot inhibit the expansion of alkali-silica reaction.When the content is over 50%,it is possible that fly ash can inhibit effectively alkali-silica reaction.

  10. The Management of Silica in Los Alamos National Laboratory Tap Water - A Study of Silica Solubility

    Energy Technology Data Exchange (ETDEWEB)

    Wohlberg, C.; Worland, V.P.; Kozubal, M.A.; Erickson, G.F.; Jacobson, H.M.; McCarthy, K.T.

    1999-07-01

    Well water at Los Alamos National Laboratory (LANL) has a silica (SiO{sub 2}) content of 60 to 100 mg/L, with 4 mg/L of magnesium, 13 mg/L calcium and lesser concentrations of other ions. On evaporation in cooling towers, when the silica concentration reaches 150 to 220 mg/L, silica deposits on heat transfer surfaces. When the high silica well water is used in the reprocessing of plutonium, silica remains in solution at the end of the process and creates a problem of removal from the effluent prior to discharge or evaporation. The work described in this Report is divided into two major parts. The first part describes the behavior of silica when the water is evaporated at various conditions of pH and in the presence of different classes of anions: inorganic and organic. In the second part of this work it was found that precipitation (floccing) of silica was a function of solution pH and mole ratio of metal to silica.

  11. Indian Ocean Rim Cooperation

    DEFF Research Database (Denmark)

    Wippel, Steffen

    Since the mid-1990s, the Indian Ocean has been experiencing increasing economic cooperation among its rim states. Middle Eastern countries, too, participate in the work of the Indian Ocean Rim Association, which received new impetus in the course of the current decade. Notably Oman is a very active...

  12. Communicating Ocean Acidification

    Science.gov (United States)

    Pope, Aaron; Selna, Elizabeth

    2013-01-01

    Participation in a study circle through the National Network of Ocean and Climate Change Interpretation (NNOCCI) project enabled staff at the California Academy of Sciences to effectively engage visitors on climate change and ocean acidification topics. Strategic framing tactics were used as staff revised the scripted Coral Reef Dive program,…

  13. Global Ocean Phytoplankton

    Science.gov (United States)

    Franz, B. A.; Behrenfeld, M. J.; Siegel, D. A.; Werdell, P. J.

    2014-01-01

    Marine phytoplankton are responsible for roughly half the net primary production (NPP) on Earth, fixing atmospheric CO2 into food that fuels global ocean ecosystems and drives the ocean's biogeochemical cycles. Phytoplankton growth is highly sensitive to variations in ocean physical properties, such as upper ocean stratification and light availability within this mixed layer. Satellite ocean color sensors, such as the Sea-viewing Wide Field-of-view Sensor (SeaWiFS; McClain 2009) and Moderate Resolution Imaging Spectroradiometer (MODIS; Esaias 1998), provide observations of sufficient frequency and geographic coverage to globally monitor physically-driven changes in phytoplankton distributions. In practice, ocean color sensors retrieve the spectral distribution of visible solar radiation reflected upward from beneath the ocean surface, which can then be related to changes in the photosynthetic phytoplankton pigment, chlorophyll- a (Chla; measured in mg m-3). Here, global Chla data for 2013 are evaluated within the context of the 16-year continuous record provided through the combined observations of SeaWiFS (1997-2010) and MODIS on Aqua (MODISA; 2002-present). Ocean color measurements from the recently launched Visible and Infrared Imaging Radiometer Suite (VIIRS; 2011-present) are also considered, but results suggest that the temporal calibration of the VIIRS sensor is not yet sufficiently stable for quantitative global change studies. All MODISA (version 2013.1), SeaWiFS (version 2010.0), and VIIRS (version 2013.1) data presented here were produced by NASA using consistent Chla algorithms.

  14. Global spatial distribution of natural riverine silica inputs to the coastal zone

    Directory of Open Access Journals (Sweden)

    H. H. Dürr

    2011-03-01

    Full Text Available Silica, SiO2, in dissolved (DSi and particulate (PSi form, is both a major product of continental weathering as well as an essential nutrient in terrestrial and aquatic systems. Here we present estimates of the spatial distribution of riverine silica fluxes under natural conditions, i.e. without human influence, to ~140 segments of the global coastal zone. Focussing on the construction of the DSi budget, natural DSi concentration is multiplied with discharge of rivers for each segment for documented basins and segments. Segments with no documentation available are estimated using clustered information based mainly on considerations of local lithology, climate, and lake retention. We approximate fluxes of particulate silica in various forms (PSi from fluxes of suspended matter, calculated from existing models. Results have been established for silica fluxes, concentrations and yields for drainage basins of the different continents, oceans basins as well as coastal segment basins. For the continental surfaces actually draining into the oceans (exorheic regions, representing 114.7 million (M km2, 371 M t y−1 of DSi and 8835 M t y−1 of PSi are transported, corresponding to a mean concentration of 9.5 mg l−1 and 226 mg l−1, and to a mean yield of 3.3 t km−2 y−1 and 77 t km−2 y−1, respectively. DSi yields exceeding 6.6 t km−2 y−1, i.e. >2× the global average, represent 17.4% of the global continental ice-free exorheic area but correspond to 56.0% of DSi fluxes. Pacific catchments hold most of the hyper-active areas (>5× global average, suggesting a close connection between tectonic activity and DSi fluxes resulting from silicate weathering. The macro-filters of regional and marginal seas intercept 33% and 46% of the total dissolved and particulate silica fluxes. The mass of DSi received from rivers

  15. Ocean General Circulation Models

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jin-Ho; Ma, Po-Lun

    2012-09-30

    1. Definition of Subject The purpose of this text is to provide an introduction to aspects of oceanic general circulation models (OGCMs), an important component of Climate System or Earth System Model (ESM). The role of the ocean in ESMs is described in Chapter XX (EDITOR: PLEASE FIND THE COUPLED CLIMATE or EARTH SYSTEM MODELING CHAPTERS). The emerging need for understanding the Earth’s climate system and especially projecting its future evolution has encouraged scientists to explore the dynamical, physical, and biogeochemical processes in the ocean. Understanding the role of these processes in the climate system is an interesting and challenging scientific subject. For example, a research question how much extra heat or CO2 generated by anthropogenic activities can be stored in the deep ocean is not only scientifically interesting but also important in projecting future climate of the earth. Thus, OGCMs have been developed and applied to investigate the various oceanic processes and their role in the climate system.

  16. Ocean acidification postcards

    Science.gov (United States)

    Schreppel, Heather A.; Cimitile, Matthew J.

    2011-01-01

    The U.S. Geological Survey (USGS) is conducting research on ocean acidification in polar, temperate, subtropical, and tropical regions including the Arctic, West Florida Shelf, and the Caribbean. Project activities include field assessment, experimental laboratory studies, and evaluation of existing data. The USGS is participating in international and interagency working groups to develop research strategies to increase understanding of the global implications of ocean acidification. Research strategies include new approaches for seawater chemistry observation and modeling, assessment of physiological effects on organisms, changes in marine ecosystem structure, new technologies, and information resources. These postcards highlight ongoing USGS research efforts in ocean acidification and carbon cycling in marine and coastal ecosystems in three different regions: polar, temperate, and tropical. To learn more about ocean acidification visit: http://coastal.er.usgs.gov/ocean-acidification/.

  17. Late Mesozoic-Cenozoic intraplate magmatism in Central Asia and its relation with mantle diapirism: Evidence from the South Khangai volcanic region, Mongolia

    Science.gov (United States)

    Yarmolyuk, Vladimir V.; Kudryashova, Ekaterina A.; Kozlovsky, Alexander M.; Lebedev, Vladimir A.; Savatenkov, Valery M.

    2015-11-01

    The South Khangai volcanic region (SKVR) comprises fields of Late Mesozoic-Cenozoic volcanic rocks scattered over southern and central Mongolia. Evolution of the region from the Late Jurassic to the Late Cenozoic includes 13 successive igneous episodes that are more or less evenly distributed in time. Major patterns in the distribution of different-aged volcanic complexes were controlled by a systematic temporal migration of volcanic centers over the region. The total length of their trajectory exceeds 1600 km. Principle characteristics of local magmatism are determined. The composition of igneous rocks varies from basanites to rhyolites (predominantly, high-K rocks), with geochemistry close to that of OIB. The rock composition, however, underwent transformations in the Mesozoic-Cenozoic. Rejuvenation of mafic rocks is accompanied by decrease in the contents of HREE and increase of Nb and Ta. According to isotope data, the SKVR magmatic melts were derived from three isotope sources that differed in the Sr, Nd, and Pb isotopic compositions and successively alternated in time. In the Early Cretaceous, the predominant source composition was controlled by interaction of the EMII- and PREMA-type mantle materials. The PREMA-type mantle material dominated quantitatively in the Late Cretaceous and initial Early Cenozoic. From the latest Early Cenozoic to Late Cenozoic, the magma source also contained the EMI-type material along with the PREMA-type. The structural fabric, rock composition, major evolutionary pattern, and inner structure of SKVR generally comply with the criteria used to distinguish the mantle plume-related regions. Analogous features can be seen in other regions of recent volcanism in Central Asia (South Baikal, Udokan, Vitim, and Tok Stanovik). The structural autonomy of these regions suggests that distribution of the Late Mesozoic-Cenozoic volcanism in Central Asia was controlled by a group of relatively small hot finger-type mantle plumes associated with

  18. OW CCMP ocean surface wind

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Cross-Calibrated Multi-Platform (CCMP) Ocean Surface Wind Vector Analyses (Atlas et al., 2011) provide a consistent, gap-free long-term time-series of ocean...

  19. Evidence for at Least Two Different Sources of Asian Dust to the Northwest Pacific Ocean Since the Eocene

    Science.gov (United States)

    Scudder, R.; Murray, R. W.; Zheng, H.; Tada, R.

    2014-12-01

    Atmospheric dust records in ice cores and marine sediment provide important information regarding global climate, tectonics, and ocean-atmospheric interactions over many different timescales. In particular, marine records from the northwest Pacific are of critical importance to our understanding of the development of the Asian Monsoon, the onset of Northern Hemisphere Glaciation, and other important climatic features. Changes in dust sources have been documented over short timescales related to monsoonal dynamics; however, studies over much longer timescales commonly consider canonical "Chinese Loess" as the sole source of Asian dust. Here we present a new marine record from Ocean Drilling Program Site 1149 that indicates the clear presence of at least two different sources of Asian dust over the past 60 Ma. Using a multi-elemental geochemical and statistical approach we have resolved two disparate eolian dust inputs to Site 1149, in addition to two different ash sources. The first dust source appears to be Chinese Loess (CL); whereas, the second dust source is compositionally distinct from CL and is similar in composition to general Upper Continental Crust. These two sources show contrasting accumulation patterns through the Cenozoic. Our results confirm previous studies that show the CL source increasing in importance over the past 8 Ma. Further, our data show that the second eolian input from Asia decreases in importance from 60 Ma to ~22 Ma. This second dust source shows variability throughout the Cenozoic that can be related to major climatic events and terrestrial climate records from China, yet ceases to be important younger than ~22 Ma. The time period from ~25-20 Ma, therefore, appears to represent a fundamental transition in the hydrologic behavior of the Asian interior. That there are two important dust sources through the Cenozoic, rather than just the single "Chinese Loess", offers new opportunities for inferring the climate and tectonic evolution of

  20. Chemical, time series and other data collected in the South Pacific Ocean on the MELVILLE cruises PS02_2002 and COOK19MV as part of the SOFEX project from 2002-01-29 to 2002-02-20 (NODC Accession 0086464)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Thorium 234, POC and biogenic silica from the 2002 SOFeX project South Patch experiment dates: 29 January 2002 to 20 February 2002 (20020129-20020220) location: N:...

  1. Silica-Rich Soil in Gusev Crater

    Science.gov (United States)

    2007-01-01

    NASA's Mars Exploration Rover Spirit has found a patch of bright-toned soil so rich in silica that scientists propose water must have been involved in concentrating it. The silica-rich patch, informally named 'Gertrude Weise' after a player in the All-American Girls Professional Baseball League, was exposed when Spirit drove over it during the 1,150th Martian day, or sol, of Spirit's Mars surface mission (March 29, 2007). One of Spirit's six wheels no longer rotates, so it leaves a deep track as it drags through soil. Most patches of disturbed, bright soil that Spirit had investigated previously are rich in sulfur, but this one has very little sulfur and is about 90 percent silica. Spirit's panoramic camera imaged the bright patch through various filters on Sol 1,158 (April 6). This approximately true-color image combines images taken through three different filters. The track of disturbed soil is roughly 20 centimeters (8 inches) wide. Spirit's miniature thermal emission spectrometer, which can assess a target's mineral composition from a distance, examined the Gertrude Weise patch on Sol 1,172 (April 20). The indications it found for silica in the overturned soil prompted a decision to drive Spirit close enough to touch the soil with the alpha particle X-ray spectrometer, a chemical analyzer at the end of Spirit's robotic arm. The alpha particle X-ray spectrometer collected data about this target on sols 1,189 and 1,190 (May 8 and May 9) and produced the finding of approximately 90 percent silica. Silica is silicon dioxide. On Earth, it commonly occurs as the crystalline mineral quartz and is the main ingredient in window glass. The Martian silica at Gertrude Weise is non-crystalline, with no detectable quartz. In most cases, water is required to produce such a concentrated deposit of silica, according to members of the rover science team. One possible origin for the silica could have been interaction of soil with acidic steam produced by volcanic activity

  2. Silica-Rich Soil Found by Spirit

    Science.gov (United States)

    2007-01-01

    NASA's Mars Exploration Rover Spirit has found a patch of bright-toned soil so rich in silica that scientists propose water must have been involved in concentrating it. The silica-rich patch, informally named 'Gertrude Weise' after a player in the All-American Girls Professional Baseball League, was exposed when Spirit drove over it during the 1,150th Martian day, or sol, of Spirit's Mars surface mission (March 29, 2007). One of Spirit's six wheels no longer rotates, so it leaves a deep track as it drags through soil. Most patches of disturbed, bright soil that Spirit had investigated previously are rich in sulfur, but this one has very little sulfur and is about 90 percent silica. This image is a approximately true-color composite of three images taken through different filters by Spirit's panoramic camera on Sol 1,187 (May 6). The track of disturbed soil is roughly 20 centimeters (8 inches) wide. Spirit's miniature thermal emission spectrometer, which can assess a target's mineral composition from a distance, examined the Gertrude Weise patch on Sol 1,172 (April 20). The indications it found for silica in the overturned soil prompted a decision to drive Spirit close enough to touch the soil with the alpha particle X-ray spectrometer, a chemical analyzer at the end of Spirit's robotic arm. The alpha particle X-ray spectrometer collected data about this target on sols 1,189 and 1,190 (May 8 and May 9) and produced the finding of approximately 90 percent silica. Silica is silicon dioxide. On Earth, it commonly occurs as the crystalline mineral quartz and is the main ingredient in window glass. The Martian silica at Gertrude Weise is non-crystalline, with no detectable quartz. In most cases, water is required to produce such a concentrated deposit of silica, according to members of the rover science team. One possible origin for the silica could have been interaction of soil with acidic steam produced by volcanic activity. Another could have been from water in a hot

  3. Property of three-dimensional silica composites

    Institute of Scientific and Technical Information of China (English)

    Guangyao Jia; Zhimeng Guo

    2007-01-01

    Silica fibers-reinforced,fused silica composites were fabricated with repeated vacuum-assisted liquid-phase infiltration.The mechanical properties,thermal properties,and ablative properties of the samples were evaluated.The effect of the silica fiber content and treatment temperature on the flexural strength of the three-dimensional SiO2 (3-D SiO2) composites also was investigated.The SiO2composites show good mechanical properties and excellent ablative performance.The flexural strength increases with an increase in silica fiber content,and decreases with an increase in treatment temperature.When the volume fraction of the silica fiber is 50vo1% and the treatment temperature is 700 ℃,the flexural strength of the composites reaches a maximum value of 78 MPa.By adding cyclohexanone surfactant,the infiltration property can be largely improved,resulting in the density of SiO2 composites increasing up to 1.65g/cm3.The fracture surfaces of the flexural specimens observed using SEM,show that the pseudoplasticity and the toughening mechanisms of the composites are caused by absorption of a lot of energy by interface debonding and fiber pulling out.

  4. Simulating the modern δ30Si distribution in the oceans and in marine sediments

    Science.gov (United States)

    Gao, S.; Wolf-Gladrow, D. A.; Völker, C.

    2016-02-01

    The δ30Si of biogenic silica (δ30SiBSi) in marine sediments is a promising proxy for the reconstruction of silicic acid utilization by diatoms in the geological past. The application of this proxy, however, requires an understanding of the modern δ30Si distributions and their controlling mechanisms. Here we present results from a modern climate simulation with a coupled ocean-sediment model that includes a prognostic formulation of biogenic silica production with concurrent silicon isotopic fractionation. In agreement with previous studies, biological fractionation combined with physical transport and mixing determines the oceanic distribution of simulated δ30Si. A new finding is a distinct seasonal cycle of δ30Si in the surface ocean, which is inversely related to that of silicic acid concentration and mixed layer depth. We also provide the first simulation results of sedimentary δ30Si, which reveal that (1) the δ30SiBSi distribution in the surface sediment reflects the exported δ30SiBSi signal from the euphotic zone and (2) the dissolution of biogenic silica in the sediment acts as a source of relatively light δ30Si into the bottom waters of the polar oceans, while it is a source of heavier δ30Si to the subtropical South Atlantic and South Pacific.

  5. Ocean Science Educator Award

    Science.gov (United States)

    The Office of Naval Research announces a program to identify and support academic ocean scientists (“Educators”) who have a distinguished record of educating high-quality doctoral and/or postdoctoral students and who will, under this program, draw postdoctoral scientists from other disciplines into the ocean sciences. Named “Educators” must be U.S. citizens with research and training experience in the ocean sciences and must have a current research and teaching position at a U.S. institution that confers doctoral degrees in ocean sciences.Participation is sought from U.S. institutions that confer doctoral degrees in one or more areas of ocean sciences; show a viable plan to identify, attract, and train, in the ocean sciences, U.S. citizen post-docs (Fellows) from other disciplines; and can show institutional commitment to ocean science education at the doctoral level. Three awards will be made via grants to institutions for a period of 3 years at $75,000 per year (at least $65,000 of these funds are intended for direct support of Fellows).

  6. The optical constants of quartz, vitreous silica and neutron-irradiated vitreous silica. I

    International Nuclear Information System (INIS)

    The infrared reflectivity of three forms of silica, α-quartz, vitreous silica and neutron-irradiated vitreous silica (approximately 2.7 x 1020 neutrons cm-2) has been measured from 400-2000 cm-1. These data have been analysed by a Kramers-Kronig transform to give the real and imaginary parts of the complex dielectric constant. Considerable care has been taken to identify and minimize errors arising in the measurements of the reflectivity spectra and in the subsequent analysis. Data are presented for the optical constants, oscillator frequencies, band strengths and halfwidths of each band. The spectra for vitreous silica and neutron-irradiated silica show two regions of absorption which are not present in the crystalline form - a strong band is observed near 950 cm-1 and a broad band from 600-800 cm-1. A difference spectrum obtained by subtracting the spectrum of the imaginary part of the dielectric contrast for vitreous silica from the corresponding data for neutron-irradiated silica reveals more detailed structure in the form of a weak but sharp band at 620 cm-1. Interpretation of these results is contained in a companion paper. (Auth.)

  7. Silica-titania composite aerogel photocatalysts by chemical liquid deposition of titania onto nanoporous silica scaffolds.

    Science.gov (United States)

    Zu, Guoqing; Shen, Jun; Wang, Wenqin; Zou, Liping; Lian, Ya; Zhang, Zhihua

    2015-03-11

    Silica-titania composite aerogels were synthesized by chemical liquid deposition of titania onto nanoporous silica scaffolds. This novel deposition process was based on chemisorption of partially hydrolyzed titanium alkoxides from solution onto silica nanoparticle surfaces and subsequent hydrolysis and condensation to afford titania nanoparticles on the silica surface. The titania is homogeneously distributed in the silica-titania composite aerogels, and the titania content can be effectively controlled by regulating the deposition cycles. The resultant composite aerogel with 15 deposition cycles possessed a high specific surface area (SSA) of 425 m(2)/g, a small particle size of 5-14 nm, and a large pore volume and pore size of 2.41 cm(3)/g and 18.1 nm, respectively, after heat treatment at 600 °C and showed high photocatalytic activity in the photodegradation of methylene blue under UV-light irradiation. Its photocatalytic activity highly depends on the deposition cycles and heat treatment. The combination of small particle size, high SSA, and enhanced crystallinity after heat treatment at 600 °C contributes to the excellent photocatalytic property of the silica-titania composite aerogel. The higher SSAs compared to those of the reported titania aerogels (silica-titania aerogels promising candidates as photocatalysts. PMID:25664480

  8. Active faults paragenesis and the state of crustal stresses in the Late Cenozoic in Central Mongolia

    Directory of Open Access Journals (Sweden)

    V. A. Sankov

    2015-12-01

    Full Text Available Active faults of the Hangay-Hentiy tectonic saddle region in Central Mongolia are studied by space images interpretation, relief analysis, structural methods and tectonic stress reconstruction. The study results show that faults activation during the Late Cenozoic stage was selective, and a cluster pattern of active faults is typical for the study region. Morphological and genetic types and the kinematics of faults in the Hangay-Hentiy saddle region are related the direction of the ancient inherited structural heterogeneities. Latitudinal and WNW trending faults are left lateral strike-slips with reverse or thrust component (Dzhargalantgol and North Burd faults. NW trending faults are reverse faults or thrusts with left lateral horizontal component. NNW trending faults have right lateral horizontal component. The horizontal component of the displacements, as a rule, exceeds the vertical one. Brittle deformations in fault zones do not conform with the Pliocene and, for the most part, Pleistocene topography. With some caution it may be concluded that the last phase of revitalization of strike slip and reverse movements along the faults commenced in the Late Pleistocene. NE trending disjunctives are normal faults distributed mainly within the Hangay uplift. Their features are more early activation within the Late Cenozoic and the lack of relation to large linear structures of the previous tectonic stages. According to the stress tensor reconstructions of the last phase of deformation in zones of active faults of the Hangay-Hentiy saddle using data on tectonic fractures and fault displacements, it is revealed that conditions of compression and strike-slip with NNE direction of the axis of maximum compression were dominant. Stress tensors of extensional type with NNW direction of minimum compression are reconstructed for the Orkhon graben. It is concluded that the activation of faults in Central Mongolia in the Pleistocene-Holocene, as well as

  9. Cenozoic calcretes from the Teruel Graben, Spain: microstructure, stable isotope geochemistry and environmental significance

    Science.gov (United States)

    Alonso-Zarza, A. M.; Arenas, C.

    2004-05-01

    In the Teruel Graben (northeast Spain), laminar and nodular calcretes formed in a variety of Cenozoic deposits, ranging in age from Palaeogene to Pleistocene. These calcretes developed in a relatively small area under the influence of the same highlands. Consequently, differences in their microstructure and isotopic composition (C and O) must be related to differences in host rock, climate, vegetation and duration of development. Nine profiles developed in different sedimentary settings, from proximal areas to lacustrine environments, were studied to determine whether the microstructure and stable isotope composition changed during the Cenozoic. These characteristics might be used as indicators of the prevailing climate and vegetation, and reveal any changes that occurred during this time. Most of the laminar calcretes studied are compound profiles that formed on hard substrates (e.g., Jurassic limestones) or coarse detrital deposits (e.g., Palaeogene, Pliocene and Plio-Pleistocene sandstones and conglomerates). These profiles formed in proximal areas of the basin and also in fluvial terraces. Microstructures include biogenic features such as alveolar septal structures, root tubes, calcified root cells and calcified organic filaments. Underside coatings of micrite and fibrous vadose cements are common around gravel clasts. On the other side, spherulites are only preserved at the very top of the youngest calcretes. Nodular calcretes developed on fine detrital substrates (e.g., on Palaeogene, Miocene and Pliocene red mudstones and sandy mudstones of distal alluvial and floodplain environments), and in some places grade vertically into palustrine limestones. The nodules consist of micrite and were elongated vertically, show desiccation cracks and mottling, micritic coatings, some alveolar septal structures, and root traces. Microcodium of type 1 occurs in both laminar and nodular calcretes, but only in those of Palaeogene age, while calcified root cells ( Microcodium

  10. Influence of Nano Silica on Alkyd Films

    DEFF Research Database (Denmark)

    Nikolic, Miroslav

    . The present work centers on the reinforcement of alkyd binders emulsified in water and used in exterior wood coatings with nano silica. Raman spectroscopy was used throughout the study to maintain the reproducibility of results as it was found that colloidal nano silica can increase or decrease the speed...... of alkyd curing affecting the tested mechanical properties. Hydrophilic, colloidal nano silica was seen to have limited effect in improving the mechanical properties due to problems in properly dispersing and attaining good surface interactions with the hydrophobic alkyd polymer. Efforts in increasing...... the interactions with the alkyd polymer while keeping the nano filler stable in the water phase did not show further improvements of mechanical properties. The best results in respect to mechanical properties, as measured under static and dynamic loading, were obtained with the use of hexamethyldisilazane treated...

  11. Functional Films from Silica/Polymer Nanoparticles

    Directory of Open Access Journals (Sweden)

    Tânia Ribeiro

    2014-05-01

    Full Text Available High performance functional coatings, based on hybrid organic/inorganic materials, are being developed to combine the polymer flexibility and ease of processing with the mechanical properties and versatility of inorganic materials. By incorporating silica nanoparticles (SiNPs in the polymeric matrices, it is possible to obtain hybrid polymer films with increased tensile strength and impact resistance, without decreasing the flexural properties of the polymer matrix. The SiNPs can further be used as carriers to impart other functionalities (optical, etc. to the hybrid films. By using polymer-coated SiNPs, it is possible to reduce particle aggregation in the films and, thus, achieve more homogeneous distributions of the inorganic components and, therefore, better properties. On the other hand, by coating polymer particles with silica, one can create hierarchically structured materials, for example to obtain superhydrophobic coatings. In this review, we will cover the latest developments in films prepared from hybrid polymer/silica functional systems.

  12. Superhydrophobic silica surfaces: fabrication and stability

    International Nuclear Information System (INIS)

    We report a simple method to make hybrid or pure silica micropatterns at the surface of a substrate based on the combination of sol–gel process and nano-imprint lithography. The silica patterns can be easily designed during the photolithographic step and functionalized with a vapor phase deposition of fluorosilane molecules to obtain superhydrophobic surfaces. Benefiting from the properties of silica, our superhydrophobic patterns can withstand elevated temperatures and show interesting optical properties. These surfaces can be used for thermal transfer applications or microfluidic devices for example to limit noise in fluorescence measurements for biological applications. In connection to the fabrication of superhydrophobic surfaces, the organization of patterns (period of grating) and height of patterns were tested, and the stability of the Cassie–Baxter state studied. The transition can be described on a wide range of tested parameters by the sliding threshold where the control of side wall angle of patterns and chemistry of surface is essential. (paper)

  13. Fused silica windows for solar receiver applications

    Science.gov (United States)

    Hertel, Johannes; Uhlig, Ralf; Söhn, Matthias; Schenk, Christian; Helsch, Gundula; Bornhöft, Hansjörg

    2016-05-01

    A comprehensive study of optical and mechanical properties of quartz glass (fused silica) with regard to application in high temperature solar receivers is presented. The dependence of rupture strength on different surface conditions as well as high temperature is analyzed, focussing particularly on damage by devitrification and sandblasting. The influence of typical types of contamination in combination with thermal cycling on the optical properties of fused silica is determined. Cleaning methods are compared regarding effectiveness on contamination-induced degradation for samples with and without antireflective coating. The FEM-aided design of different types of receiver windows and their support structure is presented. A large-scale production process has been developed for producing fused silica dome shaped windows (pressurized window) up to a diameter of 816 mm. Prototypes were successfully pressure-tested in a test bench and certified according to the European Pressure Vessel Directive.

  14. Petrogenesis of Cenozoic Potassic Volcanic Rocks in the Nangqên Basin

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The Nangqên basin is one of the Tertiary pull-apart basins situated in the east of the Qiangtang block. Similar to the adjacent Dengqên basin and Baxoi basin, there occurred a series of potassic volcanic and sub-volcanic rocks, ranging from basic, intermediate to intermediate-acid in lithology. Based on the study of petrology, mineralogy and geochemistry, including REEs, trace elements, isotopic elements and chronology, the authors concluded that the Cenozoic potassic volcanic rocks in the Nangqên basin were formed in the post-collisional intraplate tectonic settings. The relations between the basic, intermediate and intermediate-acid rocks are neither differentiation nor evolution, but instead the geochemical variability is mainly attributable to the different partial melting degrees of the mantle sources formed at depths of 50(80 km. The sources of the potassic rocks are enriched metasomatic mantle that has experienced multiple mixing of components mainly derived from the crust. The recycling model can be described as follows: after they had subducted to the mantle wedge, the crust-derived rocks were metasomatized with the mantle materials. In view of the fact that the ratio of crust-derived rocks increases by the age of volcanism, it can be concluded that the sources of the potassic rocks moved upwards progressively with time. The underplating of small scattered magmas upwelling from the asthenosphere may have induced partial melting of the sources of the volcanic rocks in some pull-apart basins in the Hengduanshan area and the intense tectonic movements of large-scale strike-slip belts provided conduits for the ascending melts.

  15. Cenozoic subsurface stratigraphy and structure of the Salar de Atacama Basin, northern Chile

    Science.gov (United States)

    Jordan, T. E.; Mpodozis, C.; Muñoz, N.; Blanco, N.; Pananont, P.; Gardeweg, M.

    2007-02-01

    Sequence mapping of industry seismic lines and their correlation to exposed stratigraphic formations enable a description of the evolution of the nonmarine Salar de Atacama Basin. This major tectonic basin, located in the present-day forearc of the northern Chilean Andes, was first defined topographically by late Cretaceous inversion of the Jurassic-early Cretaceous extensional Tarapacá backarc Basin. Inversion led to both the uplift of the Cordillera de Domeyko and subsidence of the Salar de Atacama Basin along its eastern flank. The basin evolved from a continental backarc in the Cretaceous and Paleogene to a forearc tectonic setting during the Neogene. The principal causes of basin-scale tectonic subsidence include late Cretaceous and earliest Paleocene shortening and Oligocene-early Miocene localized extension. The basin was not completely filled by late Cretaceous (Purilactis Group, sequence G) and Paleocene (sequence H) strata, and its empty space persisted through the Cenozoic. Eocene deformation caused long-wavelength rotation of a deeply weathered surface, generating an erosional unconformity across which coarse clastic strata accumulated (sequence J). Oligocene-early Miocene normal faulting, perhaps in a transtensional environment, repositioned the western basin margin and localized hangingwall subsidence, leading to the accumulation of thousands of meters of evaporitic strata (sequence K, Paciencia Group). By the close of the early Miocene, shortening resumed, first uplifting the intrabasinal Cordillera de la Sal and later generating Pliocene blind reverse faults within the topographically lowest part of the basin. Unequal deposition and tilting across the nascent Cordillera de la Sal induced diapirism of the Paciencia Group halite. In combination, inherited accommodation space and new tectonic subsidence, plus local salt-withdrawal subsidence, shaped the distribution of Upper Miocene-Recent ignimbrites, evaporites, and clastics (sequence M and Vilama

  16. Wrench-Slip Reversals and Structural Inversions: Cenozoic Slide-Rule Tectonics in Sundaland

    Directory of Open Access Journals (Sweden)

    H.D. Tjia

    2014-07-01

    Full Text Available DOI: 10.17014/ijog.v1i1.174Most of continental Southeast Asia, that is, Sundaland and Indosinia, achieved a relative tectonic stability by the beginning of the Cenozoic. Since then a strong tectonic activity in Sundaland has been restricted to existing regional fault zones and to regional slow, vertical crustal movements elsewhere that produced small to very large sedimentary basins. On the other hand, regional deformation of Indosinia as a consequence of ductile shearing has continued into the Paleogene. Since the Oligocene, the northern part of Sundaland and Indosinia have been extruded differentially towards southeast along the Red River, Wang Chao (or Mae Ping, or Tonle Sap, and Three Pagodas - Axial Malay fault zones. The initial cause has been attributed to hard collision between Subplate India with Megaplate Eurasia. Plate dynamics in the region have changed substantially since Mid-Miocene as to force wrench-slip reversals along the major fault zones in Sundaland as well as in Indosinia. Concomitant structural inversions are demonstrated on seismic sections. In the core of Sundaland, earlier transtensional wrenching was succeeded by transpressive strike-slip faulting that on major faults of the Malay Basin manifested in reversals of sense. From the Hinge-line fault eastward, the transtensional left wrench slip was succeeded by transpressional dextral slip, while in the region to its west the wrench-slip kinematics was an earlier transtensional right slip followed by transpressional left slip. In the Strait of Malacca and eastern margin of Sumatra, right-lateral wrenching in the Neogene has been common. In certain places it could be established a wrench-slip of transtensional character in Oligocene-Early Miocene, and the transpressional wrench movement occurred mainly during the Middle to Late Miocene. The remarkable coincidence of termination of spreading of the South China Basin in Langhian, and that of the West Philippine and Caroline

  17. Geochemical Records of Mantle Processes in Mantle Xenoliths from Three Cenozoic Basaltic Volcanoes in Eastern China

    Institute of Scientific and Technical Information of China (English)

    LIU Congqiang; HUANG Zhilong; XIE Guanghong; MASUSDA Akimasa

    2004-01-01

    Rare earth element (REE) contents, and Sr and Nd isotopic compositions were measured for three suites of mantle xenoliths from the Kuandian, Hannuoba and Huinan volcanoes in the north of the Sino-Korean Platform. From the correlations of Yb contents with Al/Si and Ca/Si ratios, the peridotites are considered to be the residues of partial melting of the primitive mantle. The chondrite-normalized REE compositions are diverse, varying from strongly LREE-depleted to LREE-enriched,with various types of REE patterns. Metasomatic alteration by small-volume silicate melts, of mantle peridotites previously variably depleted due to fractional melting in the spinel peridotite field, can account for the diversity of REE patterns. The Sr/Ba versus La/Ba correlation indicates that the metasomatic agent was enriched in Ba over Sr and La, suggestive of its volatilerich signature and an origin by fluid-triggered melting in an ancient subduction zone. The Sr and Nd isotopic compositions of these xenoliths, even from a single locality, vary widely, covering those of Cenozoic basalts in eastern China. The depleted end of the Sr-Nd isotope correlation is characterized by clearly higher 143Nd/144Nd and a broader range of 87Sr/86Sr compared to MORB. The low-143Nd/144Nd and high-87Sr/86Sr data distribution at the other end of data array suggests the existence of two enriched mantle components, like EM1 and EM2. The correlations between 143Nd/44Nd and 147Sm/N4Nd ratios in these xenoliths suggest at least two mantle metasomatic events, i.e. events at 0.6-1.0 Ga and 280-400 Ma ago.

  18. Meso-Cenozoic Source-to-Sink analysis of the African margin of the Equatorial Atlantic

    Science.gov (United States)

    Chardon, Dominique; Rouby, Delphine; Huyghe, Damien; Ye, Jing; Guillocheau, François; Robin, Cécile; Dall'Asta, Massimo; Brown, Roderick; Webster, David

    2015-04-01

    The Transform Source to Sink Project (TS2P) objective is to link the evolution of the offshore sedimentary basins of the African margin of the Equatorial Atlantic and their source areas on the West African Craton. The margin consists in alternating transform and oblique margin portions from Guinea, in the West, to Nigeria, in the East. Such a longitudinal structural variability is associated with variation in the margin width, continental geology and relief, drainage networks and subsidence/accumulation patterns that we analyzed using offshore seismic data and onshore geology and geomorphology. We compare syn- to post rift offshore geometry and long-term stratigraphic history of each of the margin segments. Transform faults appear to play a major role in shaping Early Cretaceous syn-rift basin architectures. Immediate post-rift Late Cretaceous sedimentary wedges record a transgression and are affected by the reactivation of some of transform faults. We produced A new type of inland paleogeographic maps for key periods since the end of the Triassic, allowing delineation of intracratonic basins having accumulated material issued from erosion of the marginal upwarps that have grown since break-up along the margin. We use offshore and onshore basin analysis to estimate sediment accumulation and integrate it in a source-to-sink analysis where Mesozoic onshore denudation will be estimated by low-temperature thermochronology. Cenozoic erosion and drainage history of the continental domain have been reconstructed from the spatial analysis of dated and regionally correlated geomorphic markers. The stationary drainage configuration of the onshore domain since 30 Ma offers the opportunity to correlate the detailed onshore morphoclimatic record based on the sequence of lateritic paleolandsurfaces to offshore stratigraphy, eustasy and global climatic proxies since the Oligocene. Within this framework, we simulate quantitative solute / solid erosional fluxes based on the

  19. The Cenozoic volcanic province of Tibesti (Sahara of Chad): major units, chronology, and structural features

    Science.gov (United States)

    Deniel, C.; Vincent, P. M.; Beauvilain, A.; Gourgaud, A.

    2015-09-01

    Using both field relationships and some absolute ages, the sequence of volcanic units in the Cenozoic Tibesti Volcanic Province (TVP) (Chad) is established as follows: (1) plateau volcanism, between at least 17 and 8 Ma, consisting of flood basalts and silicic lava plugs, with intercalated ignimbritic sheets in the upper basalt succession increasing in amount upwards. Ages decrease from NE to SW, following the migration of the small NW-SE flexures concentrating the feeding dike swarms; (2) Late Miocene large central composite volcanoes exhibiting diverse and original structures. Some of them (Tarso Toon, Ehi Oyé, and Tarso Yéga) are located along a major NNE fault, representing the main tectonic direction in Tibesti since Precambrian times; (3) construction of three large ignimbritic volcanoes, associated with significant updoming of the basement, ending with the collapse of large calderas: Voon (about 5-7 Ma), Emi Koussi (2.4-1.33 Ma), and Yirrigué (0.43 Ma); (4) basaltic activity, starting at about 5-7 Ma, and essentially consisting of cinder cones and associated lava flows (Tarso Tôh, Tarso Ahon, and Tarso Emi Chi); and (5) final volcanic activity represented by post-Yirrigué caldera activity in the Tarso Toussidé Volcanic Complex, and especially Ehi Toussidé (the only active volcano in Tibesti), plus Ehi Timi and Ehi Mousgou volcanoes, similar to Ehi Toussidé. The two tectonic directions controlling some volcanic features of the province correspond to the major old lithospheric structures delimiting the volcanic province, namely, the great NW-SE Tassilian flexure to the SW and a major NE-NNE fault zone to the E. Unusual conditions of uplift and erosion in the TVP enable exceptional exposure of the internal structure of its volcanoes.

  20. Weathering by tree root-associating fungi diminishes under simulated Cenozoic atmospheric CO2 decline

    Directory of Open Access Journals (Sweden)

    J. Quirk

    2013-10-01

    Full Text Available Trees dominate terrestrial biotic weathering of silicate minerals by converting solar energy into chemical energy that fuels roots and their ubiquitous nutrient-mobilising fungal symbionts. These biological activities regulate atmospheric CO2 ([CO2]a over geologic timescales by driving calcium and magnesium fluvial ion export and marine carbonate formation, but the important stabilising feedbacks between [CO2]a and biotic weathering anticipated by geochemical carbon cycle models remain untested. We report experimental evidence for a negative feedback across a declining Cenozoic [CO2]a range from 1500 ppm to 200 ppm, whereby low [CO2]a curtails mineral surface alteration via trenching and etch pitting by arbuscular mycorrhizal (AM and ectomycorrhizal (EM fungal partners of tree roots. Optical profile imaging using vertical scanning interferometry reveals changes in nanoscale surface topography consistent with a dual mode of attack involving delamination and trenching by AM and EM fungal hyphae on phyllosilicate mineral flakes. This is consistent with field observations of micropores in feldspar, hornblende and basalt, purportedly caused by EM fungi, but with little confirmatory evidence. Integrating these findings into a process-based biotic weathering model revealed that low [CO2]a effectively acts as a "carbon starvation" brake, causing a three-fold drop in tree-driven fungal weathering fluxes of calcium and magnesium from silicate rock grains as [CO2]a falls from 1500 ppm to 200 ppm. The feedback is regulated through the action of low [CO2]a on host tree productivity and provides empirical evidence for the role of [CO2]a starvation in diminishing the contribution of trees and mycorrhizal fungi to rates of biological weathering. More broadly, diminished tree-driven weathering under declining [CO2]a may provide an important contributory mechanism stabilising Earth's [CO2]a minimum over the past 24 million years.

  1. Origin and geodynamic setting of Late Cenozoic granitoids in Sulawesi, Indonesia

    Science.gov (United States)

    Maulana, Adi; Imai, Akira; Van Leeuwen, Theo; Watanabe, Koichiro; Yonezu, Kotaro; Nakano, Takanori; Boyce, Adrian; Page, Laurence; Schersten, Anders

    2016-07-01

    Late Cenozoic granitoids are widespread in a 1600 km long belt forming the Western and Northern Sulawesi tectono-magmatic provinces. They can be divided into three rock series: shoshonitic (HK), high-K felsic calc-alkaline (CAK), and normal calc-alkaline to tholeiitic (CA-TH). Representative samples collected from eleven plutons, which were subjected to petrography, major element, trace element, Sr, Nd, Pb isotope and whole-rock δ18O analyses, are all I-type and metaluminous to weakly peraluminous. The occurrence of the two K-rich series is restricted to Western Sulawesi, where they formed in an extensional, post-subduction tectonic setting with astenospheric upwelling providing thermal perturbation and adiabatic decompression. Two parental magma sources are proposed: enriched mantle or lower crustal equivalent for HK magmas, and Triassic igneous rocks in a Gondwana-derived fragment thrust beneath the cental and northern parts of Western Sulawesi for CAK magmas. The latter interpretation is based on striking similarities in radiogenic isotope and trace element signatures. CA-TH granitoids are found mostly in Northern Sulawesi. Partial melting of lower-middle crust amphibolites in an active subduction environment is the proposed origin of these rocks. Fractional crystallization and crustal contamination have played a significant role in magma petrogenesis, particularly in the case of the HK and CAK series. Contamination by organic carbon-bearing sedimentary rocks of the HK and CAK granitoids in the central part of Western Sulawesi is suggested by their ilmenite-series (reduced) character. The CAK granitoids further to the north and CA-TH granitoids in Northern Sulawesi are typical magnetite-series (oxidized). This may explain differences in mineralization styles in the two regions.

  2. Late Cenozoic crustal extension and magmatism, southern Death Valley region, California

    Science.gov (United States)

    Calzia, J.P.; Rämö, O.T.

    2000-01-01

    The late Cenozoic geologic history of the southern Death Valley region is characterized by coeval crustal extension and magamatism. Crustal extension is accommodated by numerous listric and planar normal faults as well as right- and left-lateral strike slip faults. The normal faults sip 30°-50° near the surface and flatten and merge leozoic miogeoclinal rocks; the strike-slip faults act as tear faults between crustal blocks that have extended at different times and at different rates. Crustal extension began 13.4-13.1 Ma and migrated northwestward with time; undeformed basalt flows and lacustrine deposits suggest that extension stopped in this region (but continued north of the Death Valley graben) between 5 and 7 Ma. Estimates of crustal extension in this region vary from 30-50 percent to more than 100 percent. Magmatic rocks syntectonic with crustal extension in the southern Death Valley region include 12.4-6.4 Ma granitic rocks as well as bimodal 14.0-4.0 Ma volcanic rocks. Geochemical and isotopic evidence suggest that the granitic rocks get younger and less alkalic from south to north; the volcanic rocks become more mafic with less evidence of crustal interaction as they get younger. The close spatial and temporal relation between crustal extension and magmatism suggest a genetic and probably a dynamic relation between these geologic processes. We propose a rectonic-magmatic model that requires heat to be transported into the crust by mantle-derived mafic magmas. These magmas pond at lithologic or rheologic boundaries, begin the crystallize, and partially melt the surrounding crustal rocks. With time, the thermally weakened crust is extended (given a regional extensional stress field) concurrent with granitic magmatism and bimodal volcanism.

  3. Meso-Cenozoic Tectono-Thermal Evolution History in Bohai Bay Basin, North China

    Institute of Scientific and Technical Information of China (English)

    Yinhui Zuo; Nansheng Qiu; Jiawei Li; Qingqing Hao; Xiongqi Pang; Zhongying Zhao; Qi Zhu

    2015-01-01

    The thermal history of sedimentary basins is a key factor for hydrocarbon accumula-tion and resource assessment, and is critical in the exploration of lithospheric tectono-thermal evo-lution. In this paper, the Cenozoic thermal histories of nearly 200 wells and the Mesozoic thermal histories of 15 wells are modeled based on the vitrinite reflectance and apatite fission track data in Bohai Bay Basin, North China. The results show that the basin experienced Early Cretaceous and Paleogene heat flow peaks, which reveals two strong rift tectonic movements that occurred in the Cretaceous and the Paleogene in the basin, respectively. The thermal evolution history in Bohai Bay Basin can be divided into five stages including (1) the low and stable heat flow stage from the Trias-sic to the Jurassic, with the heat flow of 53 to 58 mW/m2;(2) the first heat flow peak from the Early Cretaceous to the middle of the Late Cretaceous, with a maximum heat flow of 81 to 87 mW/m2;(3) the first post-rift thermal subsidence stage from the middle of the Late Cretaceous to the Paleocene, with the heat flow of 65 to 74 mW/m2 at the end of the Cretaceous; (4) the second heat flow peak from the Eocene to the Oligocene, with a maximum heat flow of 81 to 88 mW/m2;and (5) the second thermal subsidence stage from the Neogene to present, with an average heat flow of 64 mW/m2.

  4. Adsorption of mercury ions by mercapto-functionalized amorphous silica

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Quintanilla, Damian; Hierro, Isabel del; Fajardo, Mariano; Sierra, Isabel [Universidad Rey Juan Carlos, Departamento de Tecnologia Quimica y Ambiental, E.S.C.E.T, Mostoles, Madrid (Spain); Carrillo-Hermosilla, Fernando [Universidad de Castilla-La Mancha, Departamento de Quimica Inorganica, Organica y Bioquimica, Facultad de Quimicas, Ciudad Real (Spain)

    2006-02-01

    Amorphous silicas have been functionalized by two different methods. In the heterogeneous route the silylating agent, 3-chloropropyltriethoxysilane, was initially immobilized onto the silica surface to give the chlorinated silica Cl-Sil. In a second reaction, multifunctionalized N,S donor compounds were incorporated to obtain the functionalized silicas, which are denoted as L-Sil-Het (where L=mercaptothiazoline, mercaptopyridine or mercaptobenzothiazole). In the homogeneous route, the functionalization was achieved through a one-step reaction between the silica and an organic ligand containing the chelating functions; this gave the modified silicas denoted as L-Sil-Hom. The functionalized silicas were characterized by elemental analysis, IR spectroscopy and thermogravimetry. These materials were employed as adsorbents for mercury cations from aqueous and acetone solutions at room temperature. The results indicate that, in all cases, mercury adsorption was higher in the modified silicas prepared by the homogeneous method. (orig.)

  5. Stimuli-responsive polyaniline coated silica microspheres and their electrorheology

    Science.gov (United States)

    Park, Dae Eun; Choi, Hyoung Jin; Vu, Cuong Manh

    2016-05-01

    Silica/polyaniline (PANI) core–shell structured microspheres were synthesized by coating the surface of silica micro-beads with PANI and applied as a candidate inorganic/polymer composite electrorheological (ER) material. The silica micro-beads were initially modified using N-[(3-trimethoxysilyl)-propyl] aniline to activate an aniline functional group on the silica surface for a better PANI coating. The morphology of the PANI coating on the silica surface was examined by scanning electron microscopy and the silica/PANI core–shell structure was confirmed by transmission electron microscopy. The chemical structure of the particles was confirmed by Fourier transform infrared spectroscopy. Rotational rheometry was performed to confirm the difference in the ER properties between pure silica and silica/PANI microsphere-based ER fluids when dispersed in silicone oil.

  6. Ocean Dumping Control Regulations

    International Nuclear Information System (INIS)

    These Regulations were made further to the Ocean Dumping Control Act which provides for restrictions in dumping operations. The Regulations contain model applications for permits to dump or load a series of materials. (NEA)

  7. Ocean iron fertilization

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.; Smetacek, V.

    In 2009 and 2010, an Indo-German scientific expedition dusted the ocean with iron to stimulate the biological pump that captures atmosphereic carbon dioxide. Two onboard scientists tell the story of this controversial project. Besides raising...

  8. Loggerhead oceanic stage duration

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This study involves analysis of skeletal growth marks in humerus bones of 246 juvenile loggerhead sea turtles (Caretta caretta) stranded dead along the Atlantic US...

  9. Adsorption of Cadmium By Silica Chitosan

    OpenAIRE

    Moftah Ali; Ani Mulyasuryani; Akhmad Sabarudin

    2013-01-01

    The adsorption process depends on initial concentration of Cd2+ and ratio of  chitosan in adsorbent. The present study deals with the competitive adsorption of Cd2+ ion onto silica graft with chitosan. Batch adsorption experiments were performed at five different initial Cd2+ concentrations (5, 10, 15, 20 and 25 ppm), on five different proportion from silica to chitosan (100%, 95%, 85%, 75% and 65%) as adsorbent at pH 5. In the recovery process, the high recovery at 0.5 mg and observed the re...

  10. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  11. Silica nanoporous membranes and their applications

    Science.gov (United States)

    Khabibullin, Amir

    This thesis describes the development of novel silica and hybrid nanoporous membranes. Nanoporous membranes are widely used in various applications. This thesis focuses on their potential applications in the energy area, such as fuel cells and lithium batteries, and in separations and ultrafiltration. We use silica colloidal spheres and polymer-modified silica spheres to prepare the membranes in a time-, cost- and material-efficient manner. First, we prepared novel silica nanoporous membranes by pressing silica colloidal spheres followed by sintering. The pore size, the thickness, and the area of the membrane are precisely controlled by experiment parameters. The resulting membranes are mechanically and thermally durable, crack-free, and capable of size-selective transport. Next, to demonstrate the utility of the pressed membranes, described above, the proton-conductive pore-filled silica colloidal membranes were prepared and the fuel cells were constructed using these membranes. We modified these membranes by filling the membrane pores with surface-attached proton-conductive polymer brushes and prepared membrane-electrode assemblies to test fuel cell performance. We studied the proton conductivity and fuel cell performance as a function of the amount of sulfonic groups in the membrane. We also prepared and characterized reversible hybrid nanoporous membranes, self-assembled from solution containing polymer-modified silica colloidal spheres. Here we applied the new concept of noncovalent membranes, where the material is held together via noncovalent interactions of polymer brushes. This enables so-called reversible assembly of the membranes, in which membrane can be assembled in one solvent and dissolved in other. This approach provides advantages in recycling and reusing of the material. This work is one of the first of its kind and it opens a whole new area of research on reversible membranes made of polymer-modified nanoparticles. Finally, we applied our

  12. Refractive index engineering in silica glass

    DEFF Research Database (Denmark)

    Kristensen, Martin

    2003-01-01

    The thesis covers research performed durint the last eight years by the author in collaboration with members of his group within the field of UV-written gratings and poling of silica-based materials. The subjects cover several steps on the value chain from basic physics and chemistry via component...... patented and part of it is already used for component production. Chapter 6 describes research on poling. The aim of poling silica is to obtain non-linear optical properties. Two methods have been applied. The first is negative poling where the glass properties are only slightly modified, in particular by...

  13. Study on pure silica core optical fibers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    An optimal refractive index profile of pure silica core optical fiber (PSCF) was de- signed, in combination with the characters of the modified chemical vapor deposi- tion (MCVD) process. Techniques of preform fabrication by a new furnace round heating MCVD process and fiber drawing process were reviewed. Difficulties in doping fluorine in silica, widening the depressed-index cladding and maintaining the index of fiber core were discussed. Methods used to overcome these difficulties were given at the same time. Additionally, the optimal refractive index profiles of PSCF were presented.

  14. Tailoring the radiation hardness of fused silica

    International Nuclear Information System (INIS)

    The degradation of optical transmission of two types of Heraeus Suprasil synthetic fused silica after exposure to ionising radiation was investigated with regard to usage as a DIRC radiator. These studies led to the discovery of defect mechanisms that are well known for UV laser irradiation also being present for ionising radiation. The dependence of the optical degradation on interstitial hydrogen, as predicted by existing defect models, could be verified. This leads to an improved understanding of the radiation damage processes and allows to specify the composition of synthetic fused silica according to experimental requirements especially in terms of radiation load.

  15. Measurement of muonium emission from silica aerogel

    CERN Document Server

    Bakule, P; Contreras, D; Esashi, M; Fujiwara, Y; Fukao, Y; Hirota, S; Iinuma, H; Ishida, K; Iwasaki, M; Kakurai, T; Kanda, S; Kawai, H; Kawamura, N; Marshall, G M; Masuda, H; Matsuda, Y; Mibe, T; Miyake, Y; Okada, S; Olchanski, K; Olin, A; Onishi, H; Saito, N; Shimomura, K; Strasser, P; Tabata, M; Tomono, D; Ueno, K; Yokoyama, K; Yoshida, S

    2013-01-01

    Emission of muonium ($\\mu^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.

  16. Silica aerogel Cerenkov detectors for particle identification

    International Nuclear Information System (INIS)

    We present light yield measurements of silica aerogel Cerenkov detectors with photomultiplier readout, showing the light yield dependence of pure and wavelength-shifter-doped silica aerogel on block size using both cosmic muons and electrons from a 106Ru source. We present studies of fluorescent fibers and single photon avalanche diodes, including measurements of attenuation lengths and emission spectra of fibers versus wavelength and tests with a single photon avalanche diode. We show results of the response of a single photon avalanche diode to different light sources. Finally, we discuss a new readout scheme using avalanche photodiodes

  17. LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model

    Directory of Open Access Journals (Sweden)

    R. E. Zeebe

    2011-06-01

    Full Text Available The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

  18. Precision dicing and micromilling of silica for photonics

    OpenAIRE

    Carpenter, Lewis G.

    2013-01-01

    This thesis focuses on the development of precision dicing and micromilling machining techniques for silica photonic applications. Comparison is given between the studied and conventional techniques for machining silica, such as photolithography and etching, laser machining, etc.. Precision dicing was used to create low loss input/output facets in the silica-on-silicon platform. It was demonstrated that ductile type dicing can produce facets in a silica-on-silicon substrate with a smooth,...

  19. Modified monolithic silica capillary for preconcentration of catecholamines

    Institute of Scientific and Technical Information of China (English)

    Wei Chang; Tusyo-shi Komazu

    2009-01-01

    Preconcentration of catecholamines by the modified monolithic silica in the capillary was investigated in this study. In order to achieve a microchip-based method for determining catecholamines in the saliva, the monolithic silica was fabricated in the capillary and the monolithic silica was chemically modified by on-column reaction with phenylboronate. Different modified methods were compared. The concentration conditions were optimized. This study indicates the applicability of the modified monolithic silica capillary when it was used to concentrate catecholamines.

  20. Synthesis of Various Silica Nanoparticles for Foam Stability

    International Nuclear Information System (INIS)

    The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

  1. Synthesis of Various Silica Nanoparticles for Foam Stability

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles.

  2. Wind Generated Ocean Waves

    DEFF Research Database (Denmark)

    Frigaard, Peter

    2001-01-01

    Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)......Book review: I. R. Young, Elsevier Ocean Engineering Series, Vol 2. Elsevier Science, Oxford, UK, 1999, 306 pages, hardbound, ISBN 0-08-043317-0, Dfl. 275,00 (US$ 139.50)...

  3. Ocean microbial metagenomics

    Science.gov (United States)

    Kerkhof, Lee J.; Goodman, Robert M.

    2009-09-01

    Technology for accessing the genomic DNA of microorganisms, directly from environmental samples without prior cultivation, has opened new vistas to understanding microbial diversity and functions. Especially as applied to soils and the oceans, environments on Earth where microbial diversity is vast, metagenomics and its emergent approaches have the power to transform rapidly our understanding of environmental microbiology. Here we explore select recent applications of the metagenomic suite to ocean microbiology.

  4. Continental deformation accommodated by non-rigid passive bookshelf faulting: An example from the Cenozoic tectonic development of northern Tibet

    Science.gov (United States)

    Zuza, Andrew V.; Yin, An

    2016-05-01

    Collision-induced continental deformation commonly involves complex interactions between strike-slip faulting and off-fault deformation, yet this relationship has rarely been quantified. In northern Tibet, Cenozoic deformation is expressed by the development of the > 1000-km-long east-striking left-slip Kunlun, Qinling, and Haiyuan faults. Each have a maximum slip in the central fault segment exceeding 10s to ~ 100 km but a much smaller slip magnitude (~plate-like rigid-body motion and flow-like distributed deformation end-member models for continental tectonics. Here we propose a non-rigid bookshelf-fault model for the Cenozoic tectonic development of northern Tibet. Our model, quantitatively relating discrete left-slip faulting to distributed off-fault deformation during regional clockwise rotation, explains several puzzling features, including the: (1) clockwise rotation of east-striking left-slip faults against the northeast-striking left-slip Altyn Tagh fault along the northwestern margin of the Tibetan Plateau, (2) alternating fault-parallel extension and shortening in the off-fault regions, and (3) eastward-tapering map-view geometries of the Qimen Tagh, Qaidam, and Qilian Shan thrust belts that link with the three major left-slip faults in northern Tibet. We refer to this specific non-rigid bookshelf-fault system as a passive bookshelf-fault system because the rotating bookshelf panels are detached from the rigid bounding domains. As a consequence, the wallrock of the strike-slip faults deforms to accommodate both the clockwise rotation of the left-slip faults and off-fault strain that arises at the fault ends. An important implication of our model is that the style and magnitude of Cenozoic deformation in northern Tibet vary considerably in the east-west direction. Thus, any single north-south cross section and its kinematic reconstruction through the region do not properly quantify the complex deformational processes of plateau formation.

  5. Flexible ocean upwelling pipe

    Science.gov (United States)

    Person, Abraham

    1980-01-01

    In an ocean thermal energy conversion facility, a cold water riser pipe is releasably supported at its upper end by the hull of the floating facility. The pipe is substantially vertical and has its lower end far below the hull above the ocean floor. The pipe is defined essentially entirely of a material which has a modulus of elasticity substantially less than that of steel, e.g., high density polyethylene, so that the pipe is flexible and compliant to rather than resistant to applied bending moments. The position of the lower end of the pipe relative to the hull is stabilized by a weight suspended below the lower end of the pipe on a flexible line. The pipe, apart from the weight, is positively buoyant. If support of the upper end of the pipe is released, the pipe sinks to the ocean floor, but is not damaged as the length of the line between the pipe and the weight is sufficient to allow the buoyant pipe to come to a stop within the line length after the weight contacts the ocean floor, and thereafter to float submerged above the ocean floor while moored to the ocean floor by the weight. The upper end of the pipe, while supported by the hull, communicates to a sump in the hull in which the water level is maintained below the ambient water level. The sump volume is sufficient to keep the pipe full during heaving of the hull, thereby preventing collapse of the pipe.

  6. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  7. Impacts of Ocean Acidification

    Energy Technology Data Exchange (ETDEWEB)

    Bijma, Jelle (Alfred Wegener Inst., D-27570 Bremerhaven (Germany)) (and others)

    2009-08-15

    There is growing scientific evidence that, as a result of increasing anthropogenic carbon dioxide (CO{sub 2}) emissions, absorption of CO{sub 2} by the oceans has already noticeably increased the average oceanic acidity from pre-industrial levels. This global threat requires a global response. According to the Intergovernmental Panel on Climate Change (IPCC), continuing CO{sub 2} emissions in line with current trends could make the oceans up to 150% more acidic by 2100 than they were at the beginning of the Anthropocene. Acidification decreases the ability of the ocean to absorb additional atmospheric CO{sub 2}, which implies that future CO{sub 2} emissions are likely to lead to more rapid global warming. Ocean acidification is also problematic because of its negative effects on marine ecosystems, especially marine calcifying organisms, and marine resources and services upon which human societies largely depend such as energy, water, and fisheries. For example, it is predicted that by 2100 around 70% of all cold-water corals, especially those in the higher latitudes, will live in waters undersaturated in carbonate due to ocean acidification. Recent research indicates that ocean acidification might also result in increasing levels of jellyfish in some marine ecosystems. Aside from direct effects, ocean acidification together with other global change-induced impacts such as marine and coastal pollution and the introduction of invasive alien species are likely to result in more fragile marine ecosystems, making them more vulnerable to other environmental impacts resulting from, for example, coastal deforestation and widescale fisheries. The Marine Board-ESF Position Paper on the Impacts of Climate Change on the European Marine and Coastal Environment - Ecosystems indicated that presenting ocean acidification issues to policy makers is a key issue and challenge. Indeed, as the consequences of ocean acidification are expected to emerge rapidly and drastically, but are

  8. Technical Note: Silica stable isotopes and silicification in a carnivorous sponge Asbestopluma sp.

    Science.gov (United States)

    Hendry, K. R.; Swann, G. E. A.; Leng, M. J.; Sloane, H. J.; Goodwin, C.; Berman, J.; Maldonado, M.

    2015-06-01

    The stable isotope composition of benthic sponge spicule silica is a potential source of palaeoceanographic information about past deep seawater chemistry. The silicon isotope composition of spicules has been shown to relate to the silicic acid concentration of ambient water, although existing calibrations do exhibit a degree of scatter in the relationship. Less is known about how the oxygen isotope composition of sponge spicule silica relates to environmental conditions during growth. Here, we investigate the vital effects on silica, silicon and oxygen isotope composition in a carnivorous sponge, Asbestopluma sp., from the Southern Ocean. We find significant variations in silicon and oxygen isotopic composition within the specimen that are related to unusual spicule silicification. The largest variation in both isotope systems was associated with the differential distribution of an unconventional, hypersilicified spicule type (desma) along the sponge body. The absence an internal canal in the desmas suggests an unconventional silicification pattern leading to an unusually heavy isotope signature. Additional internal variability derives from a systematic offset between the peripheral skeleton of the body having systematically a higher isotopic composition than the internal skeleton. A simplified silicon isotope fractionation model, in which desmas were excluded, suggests that the lack of a system for seawater pumping in carnivorous sponges favours a low replenishment of dissolved silicon within the internal tissues, causing kinetic fractionation during silicification that impacts the isotope signature of the internal skeleton. Analysis of multiple spicules should be carried out to "average out" any artefacts in order to produce more robust downcore measurements.

  9. Simple ocean carbon cycle models

    Energy Technology Data Exchange (ETDEWEB)

    Caldeira, K. [Lawrence Livermore National Lab., CA (United States); Hoffert, M.I. [New York Univ., NY (United States). Dept. of Earth System Sciences; Siegenthaler, U. [Bern Univ. (Switzerland). Inst. fuer Physik

    1994-02-01

    Simple ocean carbon cycle models can be used to calculate the rate at which the oceans are likely to absorb CO{sub 2} from the atmosphere. For problems involving steady-state ocean circulation, well calibrated ocean models produce results that are very similar to results obtained using general circulation models. Hence, simple ocean carbon cycle models may be appropriate for use in studies in which the time or expense of running large scale general circulation models would be prohibitive. Simple ocean models have the advantage of being based on a small number of explicit assumptions. The simplicity of these ocean models facilitates the understanding of model results.

  10. Inversion of Gravity Data to Define the Pre-Cenozoic Surface and Regional Structures Possibly Influencing Groundwater Flow in the Rainier Mesa Region, Nye County, Nevada.

    Energy Technology Data Exchange (ETDEWEB)

    Thomas G. Hildenbrand; Geoffrey A. Phelps; Edward A. Mankinen

    2006-09-21

    A three-dimensional inversion of gravity data from the Rainier Mesa area and surrounding regions reveals a topographically complex pre-Cenozoic basement surface. This model of the depth to pre-Cenozoic basement rocks is intended for use in a 3D hydrogeologic model being constructed for the Rainier Mesa area. Prior to this study, our knowledge of the depth to pre-Cenozoic basement rocks was based on a regional model, applicable to general studies of the greater Nevada Test Site area but inappropriate for higher resolution modeling of ground-water flow across the Rainier Mesa area. The new model incorporates several changes that lead to significant improvements over the previous regional view. First, the addition of constraining wells, encountering old volcanic rocks lying above but near pre-Cenozoic basement, prevents modeled basement from being too shallow. Second, an extensive literature and well data search has led to an increased understanding of the change of rock density with depth in the vicinity of Rainier Mesa. The third, and most important change, relates to the application of several depth-density relationships in the study area instead of a single generalized relationship, thereby improving the overall model fit. In general, the pre-Cenozoic basement surface deepens in the western part of the study area, delineating collapses within the Silent Canyon and Timber Mountain caldera complexes, and shallows in the east in the Eleana Range and Yucca Flat regions, where basement crops out. In the Rainier Mesa study area, basement is generally shallow (< 1 km). The new model identifies previously unrecognized structures within the pre-Cenozoic basement that may influence ground-water flow, such as a shallow basement ridge related to an inferred fault extending northward from Rainier Mesa into Kawich Valley.

  11. Characterization of vanadium/silica and copper/silica aerogel catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Owens, L.; Tillotson, T.M.; Hair, L.M. [Lawrence Livermore National Lab., CA (United States). Chemistry and Materials Science Dept.

    1995-09-01

    Vanadium/silica and copper/silica aerogels have been prepared using the sol-gel method followed by CO{sub 2} exchange and supercritical extraction. Structural properties of samples supercritically dried, oxidized and used in reactions studies conducted with a feed representing the average composition of automobile exhaust from a lean burn engine were investigated using laser Raman spectroscopy and temperature-programmed reduction. No evidence of crystalline V{sub 2}O{sub 5} was found for the vanadium/silica aerogel, freshly extracted, oxidized or following exposure to reaction conditions using these techniques. However, results obtained for the copper/silica sample indicate that changes in the structure of the copper species had occurred as the sample was oxidized and exposed to reaction conditions.

  12. Optical properties of polyimide/silica nanocomposite

    International Nuclear Information System (INIS)

    The optical properties of thin films of polyimide/silica nanocomposites prepared via sol-gel process were investigated as a function of nanosilica particles content. Absorption and reflectance spectra were collected by a spectrophotometer giving UV-radiation of wavelength range 200-800 nm. The optical data obtained were analyzed in terms of absorption formula for non-crystalline materials. The calculated values of the optical energy gap and the width of the energy tails of the localized states exhibited silica concentration dependence. The direct optical energy gap for neat polyimide is about 1.95 eV, and decreases to a value of 1.8 eV for nanocomposite of 25 wt% nanosilica content. It was found that the calculated refractive index and dielectric constants of nanocomposites increase with silica particles content. The overall dependence of the optical and dielectrical constants on silica content in polyimide matrix is argued on the basis of the observed morphology and overlap of the localized energy sates of different color centers. The EMT model was fitted to the observed dielectric data.

  13. Optical recording in copper-silica nanocomposite

    Science.gov (United States)

    Dmitruk, Igor; Blonskiy, Ivan; Korenyuk, Petro; Kadan, Viktor; Zubrilin, Mykola; Dmytruk, Andriy; Yeshchenko, Oleg; Alexeenko, Alexandr; Kotko, Andriy

    2014-05-01

    The application of field enhancement effect, which takes place when light, interacts with surface plasmon, for optical recording has been suggested. Copper-silica nanocomposite demonstrates possibility of optical writing and erasing under irradiation by second harmonic (400 nm) and fundamental wavelength (800 nm) of femtosecond titanium-sapphire laser, respectively.

  14. Optical properties of polyimide/silica nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Tommalieh, M.J. [Physics Department, University of Jordan Amman (Jordan); Zihlif, A.M., E-mail: adzh@ju.edu.j [Physics Department, University of Jordan Amman (Jordan)

    2010-12-01

    The optical properties of thin films of polyimide/silica nanocomposites prepared via sol-gel process were investigated as a function of nanosilica particles content. Absorption and reflectance spectra were collected by a spectrophotometer giving UV-radiation of wavelength range 200-800 nm. The optical data obtained were analyzed in terms of absorption formula for non-crystalline materials. The calculated values of the optical energy gap and the width of the energy tails of the localized states exhibited silica concentration dependence. The direct optical energy gap for neat polyimide is about 1.95 eV, and decreases to a value of 1.8 eV for nanocomposite of 25 wt% nanosilica content. It was found that the calculated refractive index and dielectric constants of nanocomposites increase with silica particles content. The overall dependence of the optical and dielectrical constants on silica content in polyimide matrix is argued on the basis of the observed morphology and overlap of the localized energy sates of different color centers. The EMT model was fitted to the observed dielectric data.

  15. Optical recording in copper–silica nanocomposite

    Energy Technology Data Exchange (ETDEWEB)

    Dmitruk, Igor, E-mail: igor_dmitruk@univ.kiev.ua [Femtosecond Laser Complex, Institute of Physics, National Academy of Sciences of Ukraine, 46 Prospect Nauky, 03028 Kyiv (Ukraine); Faculty of Physics, Taras Shevchenko National University of Kyiv, 60 Volodymyrska Street, 01601 Kyiv (Ukraine); Blonskiy, Ivan; Korenyuk, Petro; Kadan, Viktor; Zubrilin, Mykola; Dmytruk, Andriy [Femtosecond Laser Complex, Institute of Physics, National Academy of Sciences of Ukraine, 46 Prospect Nauky, 03028 Kyiv (Ukraine); Yeshchenko, Oleg [Faculty of Physics, Taras Shevchenko National University of Kyiv, 60 Volodymyrska Street, 01601 Kyiv (Ukraine); Alexeenko, Alexandr [P. O. Sukhoi State Technical University of Gomel, 48, Pr.Octiabria, 246746 Gomel (Belarus); Kotko, Andriy [I. M. Frantsevich Institute for Problems of Materials Science, 3, Krzhizhanovsky Str., 03680 Kyiv (Ukraine)

    2014-05-01

    The application of field enhancement effect, which takes place when light, interacts with surface plasmon, for optical recording has been suggested. Copper–silica nanocomposite demonstrates possibility of optical writing and erasing under irradiation by second harmonic (400 nm) and fundamental wavelength (800 nm) of femtosecond titanium–sapphire laser, respectively.

  16. A cost effective approach to silica reduction

    International Nuclear Information System (INIS)

    Silica, in and of itself is a relatively inocuous substance which provides no hazard to the environment, nor to plant systems which remain at ambient temperatures. However, when system temperatures and pressures are increased during power production, silica can combine with cations to form a zeolite layer on fuel assemblies, eventually creating the potential for fuel failures which lead to higher activity releases to the environment, increased production of radwaste, and greater potential for radioactive contamination thereby increasing plant radiation levels. Because of these potential problems maintaining minimum levels of silica in plant systems that are in contact with the fuel is essential. Removal of silica from systems can be accomplished through several means. Ion exchange resin may be used, however, proper conditions must exist for this to be effective. Draining and refilling of tanks provides marginally effective relief, provided no other chemical, such as boron, would need to be replaced and the radwaste system is capable of processing the waste generated. The two most effective means for systems which must maintain some chemical constituency are the bleed and feed and reverse osmosis (RO) processes

  17. Bioluminescent Bioreporters Encapsulated in Silica Gel

    Czech Academy of Sciences Publication Activity Database

    Kuncová, Gabriela; Trögl, J.; Demnerová, K.; Ripp, S.; Sayler, G. S.

    -: -, 2008, O08-2 - 1-O08-2 - 4. [XVI International Conference on Bioencapsulation. Dublin (IE), 04.09.2008-06.09.2008] Institutional research plan: CEZ:AV0Z40720504 Keywords : bioluminescent bioreporter * silica gel * biosensor Subject RIV: CE - Biochemistry

  18. Kinetics of silica-phase transitions

    International Nuclear Information System (INIS)

    In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain

  19. Photo darkening of rare earth doped silica

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    2011-01-01

    The photo darkening (PD) absorption spectra from unseeded amplifier operation (by 915 nm pumping) of ytterbium/aluminum and codoped silica fibers is after prolonged operation observed to develop a characteristic line at 2.6 eV (477 nm). This line is proposed to be due to inter center excitation...

  20. Nanoporous silica membranes with high hydrothermal stability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Magnacca, Giualiana; Yue, Yuanzheng

    Despite the use of sol-gel derived nanoporous silica membranes in substitution of traditional separation processes is expected leading to vast energy savings, their intrinsic poor steam-stability hampers their application at an industrial level. Transition metal ions can be used as dopant to...

  1. Poling of planar silica-based waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Leistiko, Otto

    2000-01-01

    Planar silica-based waveguides were electrically poled at elevated temperatures and cooled with the field still applied. This procedure induced second-order nonlinear effects in the waveguides. Systematic studies of the dependence of the induced linear electro-optic effect on polilng temperature...

  2. MIXED CATIONIC TEMPLATES CONTROLLING ORDERED SILICA MORPHOLOGY

    Czech Academy of Sciences Publication Activity Database

    Putz, A.-M.; Ianasi, C.; Almásy, L.; Dudás, Z.; Len, A.; Székely, K. N.; Plocek, Jiří; Sfarloaga, P.; Săcărescu, L.; Savii, C.

    Novi Sad : Faculty of Technology, 2015 - (Srdić, V.). s. 51-51 ISBN 978-86-6253-049-3. [Conference for Young Scientists in Ceramics (Students' Meeting /101/ - SM-2015 and ESR Workshop COST MP1208. 21.10.2015-24.10.2015, Novi Sad] Institutional support: RVO:61388980 Keywords : MCM-41 type silica particles Subject RIV: CA - Inorganic Chemistry

  3. Cyclic olefin copolymer-silica nanocomposites foams

    Czech Academy of Sciences Publication Activity Database

    Pegoretti, A.; Dorigato, A.; Biani, A.; Šlouf, Miroslav

    2016-01-01

    Roč. 51, č. 8 (2016), s. 3907-3916. ISSN 0022-2461 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : cyclic olefin copolymer * nanocomposites * silica Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.371, year: 2014

  4. Polarization conversion in a silica microsphere

    OpenAIRE

    Bianucci, Pablo; Fietz, Chris; Robertson, John W.; Shvets, Gennady; Shih, Chih-Kang

    2007-01-01

    We experimentally demonstrate controlled polarization-selective phenomena in a whispering gallery mode resonator. We observed efficient ($\\approx 75 %$) polarization conversion of light in a silica microsphere coupled to a tapered optical fiber with proper optimization of the polarization of the propagating light. A simple model treating the microsphere as a ring resonator provides a good fit to the observed behavior.

  5. Significant Silica Solubility in Geothermal Steam

    Energy Technology Data Exchange (ETDEWEB)

    James, Russell

    1986-01-21

    Although it is widely believed that silica solubility in low pressure (5 to 10 bar) geothermal steam is negligible, when one takes into account steam flows exceeding 10 million tonnes a year--at Wairakei, for instance--it is found that the amount transmitted in the vapor has the potential to give significant deposits on turbine nozzles and blades. A 150 MWe power station, when based on flows from a hot water reservoir at (a) 250 C or (b) 315 C, and with separator pressures of 6 bar, is found to carry about 100 and 200 kg/year respectively in the steam phase. In the case of a similar sized station exploiting a dry steam reservoir such as The Geysers, equivalent silica flows are obtained, dissolved in steam and carried as dust--the latter as solid particles precipitating from the vapor en route from source to turbine, and not preexisting in the formations as is commonly considered. Choking or coating of subterranean rock near such dry steam wells due to exsolving silica, may be the principal cause of declining steam discharge under production. Silica from completely dry or superheated steam can also seal the cap and sides of steam reservoirs when expanding below the criticus temperature (236 C) in a way previously thought possible only by hot water or wet steam.

  6. Metal doped hybrid silica membranes for separation

    NARCIS (Netherlands)

    Ru, Yanfei

    2014-01-01

    The present study describes the e ect of di erent factors such as the type of dopants and the percentage of dopants on the stability and permeance of membranes. Di erent dopants such as zirconia, yttrium were used to produce organic-inorganic hybrid silica membranes. During the programme, zirconia d

  7. Silica sand resources in the Netherlands

    NARCIS (Netherlands)

    Meulen, M.J. van der; Westerhoff, W.E.; Menkovic, A.; Gruijters, S.H.L.L.; Dubelaar, C.W.; Maljers, D.

    2009-01-01

    Silica sand, (almost) pure quartz sand, is a valuable and scarce mineral resource within the shallow Dutch subsurface. High-grade deposits are exploited in the southeastemmost part of the country, as raw material for the glass, ceramic, chemical and other process industries. Dutch land-use policy re

  8. Tapered fibers embedded in silica aerogel.

    Science.gov (United States)

    Xiao, Limin; Grogan, Michael D W; Leon-Saval, Sergio G; Williams, Rhys; England, Richard; Wadsworth, Willam J; Birks, Tim A

    2009-09-15

    We have embedded thin tapered fibers (with diameters down to 1 microm) in silica aerogel with low loss. The aerogel is rigid but behaves refractively like air, protecting the taper without disturbing light propagation along it. This enables a new class of fiber devices exploiting volume evanescent interactions with the aerogel itself or with dopants or gases in the pores. PMID:19756084

  9. Test of a silica aerogel Cerenkov counter

    CERN Document Server

    Basile, M; Cifarelli, L; Genovese, F; Giusti, P; Massam, Thomas; Massera, F; Palmonari, F; Romeo, G C; Valenti, G; Zichichi, A

    1977-01-01

    The authors have been able to produce samples of silica aerogels. The results of a systematic study of a sample with 4.5 cm diameter and 1.8 cm thickness and refractive index n=1.029+or-0.002 are reported. (5 refs).

  10. Growth of hydroxyapatite nanoparticles on silica gels.

    Science.gov (United States)

    Rivera-Muñoz, E M; Huirache-Acuña, R; Velázquez, R; Alonso-Núñez, G; Eguía-Eguía, S

    2011-06-01

    Synthetic, hydroxyapatite nanoparticles were grown on the surface of silica gels. The synthesis of those nanoparticles was obtained by immersing silica gels in a simulated body fluid (SBF) at 37 degrees C. The SBF was replaced every week to keep constant the Ca and P ion concentration and subsequent growth of hydroxyapatite was evaluated after 1-6 weeks of total soaking time in SBF. Hydroxyapatite nanoparticles were observed by scanning electron microscopy (SEM) on the surface of silica gel samples and confirmed by energy dispersive X-ray spectroscopy (EDS), Fourier Transform Infra Red Spectroscopy (FTIR) and powder X-ray Diffractometry (XRD) analysis. These particles show a regular shape and uniform size every week, keeping within the nanoscale always. Both the size and morphology of hydroxyapatite nanoparticles obtained are the result of the use of different chemical additives in the synthesis of silica gels, since they affect the liquid-to-solid interface, and the growth could correspond to a diffusion limited aggregation (DLA) process. A more detailed analysis, with higher magnifications, showed that hydroxyapatite nanoparticles are not solid spheres, showing a branched texture and their size depends on the scale and resolution of the measure instrument. PMID:21770224

  11. Immunological Effects of Silica and Asbestos

    Institute of Scientific and Technical Information of China (English)

    Takemi Otsuki; Fuminori Hyodoh; Ayako Ueki; Yasumitsu Nishimura; Megumi Maeda; Shuko Murakami; Hiroaki Hayashi; Yoshie Miura; Masayasu Kusaka; Takashi Nakano; Kazuya Fukuoka; Takumi Kishimoto

    2007-01-01

    Silicosis patients (SILs) and patients who have been exposed to asbestos develop not only respiratory diseases but also certain immunological disorders. In particular, SIL sometimes complicates autoimmune diseases such as systemic scleroderma, rheumatoid arthritis (known as Caplan syndrome), and systemic lupus erythematoses. In addition, malignant complications such as lung cancer and malignant mesothelioma often occurr in patients exposed to asbestos, and may be involved in the reduction of tumor immunity. Although silica-induced disorders of autoimmunity have been explained as adjuvant-type effects of silica, more precise analyses are needed and should reflect the recent progress in immunomolecular findings. A brief summary of our investigations related to the immunological effects of silica/asbestos is presented. Recent advances in immunomolecular studies led to detailed analyses of the immunological effects of asbestos and silica. Both affect immuno-competent cells and these effects may be associated with the pathophysiological development of complications in silicosis and asbestos-exposed patients such as the occurrence of autoimmune disorders and malignant tumors, respectively. In addition,immunological analyses may lead to the development of new clinical tools for the modification of the pathophysiological aspects of diseases such as the regulation of autoimmunity or tumor immunity using cellmediated therapies, various cytokines, and molecule-targeting therapies. In particular, as the incidence of asbestosrelated malignancies is increasing and such malignancies have been a medical and social problem since the summer of 2005 in Japan, efforts should be focused on developing a cure for these diseases to eliminate nationwide anxiety.

  12. Adsorption of Cadmium By Silica Chitosan

    Directory of Open Access Journals (Sweden)

    Moftah Ali

    2013-03-01

    Full Text Available The adsorption process depends on initial concentration of Cd2+ and ratio of  chitosan in adsorbent. The present study deals with the competitive adsorption of Cd2+ ion onto silica graft with chitosan. Batch adsorption experiments were performed at five different initial Cd2+ concentrations (5, 10, 15, 20 and 25 ppm, on five different proportion from silica to chitosan (100%, 95%, 85%, 75% and 65% as adsorbent at pH 5. In the recovery process, the high recovery at 0.5 mg and observed the recovery decrease with increasing the initial concentration of Cd2+, and the low recovery at 0.25 mg from Cd2+. In this study, the adsorption capacity of Cd2+ in regard to the ratio of silica and chitosan hybrid adsorbents are examined in detail. The aim of this study to explore effects of initial concentrations of Cd2+, and the ratio of silica to chitosan on the adsorption and recovery of Cd2+.

  13. Health hazards due to the inhalation of amorphous silica.

    Science.gov (United States)

    Merget, R; Bauer, T; Küpper, H U; Philippou, S; Bauer, H D; Breitstadt, R; Bruening, T

    2002-01-01

    Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic ("thermal" or "fumed") silica, and (3) chemically or physically modified silica. According to the different physicochemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or emphysema cannot be excluded. There is no study

  14. Health hazards due to the inhalation of amorphous silica

    International Nuclear Information System (INIS)

    Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or emphysema cannot be excluded. There is no

  15. Mass transfer in the oceanic lithosphere: Serpentinization is not isochemical

    Science.gov (United States)

    Malvoisin, Benjamin

    2015-11-01

    Whereas the serpentinization reaction leads to stark differences in the physical properties of mantle rocks at mid-ocean ridges, the chemical changes associated with this reaction are thought to be restricted to the addition of water and the generation of hydrogen ("isochemical" reaction). Here, I compile a geochemical dataset of serpentinized peridotites at mid-ocean ridges evidencing that a decrease by up to 11% of the MgO/SiO2 ratio is associated with serpentinization. This MgO/SiO2 decrease is consistent with the calculated distribution of Mg in the minerals since, during isochemical serpentinization, ∼10% of the Mg should be contained in brucite, an Mg-hydroxide not commonly observed in serpentinized peridotites, which are typically composed of serpentine (Mg3Si2O5(OH)4) and magnetite (Fe3O4). This latter mineralogical assemblage and a decrease of the MgO/SiO2 ratio were only reproduced in numerical models of peridotite reacting with fluids containing aqueous silica at fluid to rock (F/R) ratios greater than 20. At higher F/R ratios, talc (Mg3Si4O10(OH)2) was found to be stable, in agreement with observations in extremely altered samples found at mid-ocean ridges. The potential sources for aqueous silica in the fluid are the alteration of mafic units intruding mantle rocks at slow-spreading ridges. The mineralogical and chemical changes associated with SiO2 gain during serpentinization at mid-ocean ridges will have consequences on abiotic hydrogen production, contribute to a volume increase of 50% and decrease water incorporation during serpentinization by more than 10% compared to "isochemical" serpentinization. These changes will also increase the depth at which fluids are released by dehydration reactions in subduction zones by more than 20 km.

  16. Ocean Physicochemistry versus Climate Change

    OpenAIRE

    Góralski, Bogdan

    2014-01-01

    It is the dwindling ocean productivity which leaves dissolved carbon dioxide in the seawater. Its solubility is diminished by the rise in ocean water temperature (by one degree Celsius since 1910, according to IPCC). Excess carbon dioxide is emitted into the atmosphere, while its growing concentration in seawater leads to ocean acidification. Ocean acidification leading to lowering pH of surface ocean water remains an unsolved problem of science. My today’s lecture will mark an attempt at ...

  17. 76 FR 31235 - Safety Zone; Ocean City Air Show, Atlantic Ocean, Ocean City, MD

    Science.gov (United States)

    2011-05-31

    ... Ocean City, Maryland. (b) Definition: For purposes of enforcement of this section, Captain of the Port... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Ocean City Air Show, Atlantic Ocean, Ocean City, MD AGENCY: Coast Guard, DHS. ACTION: Temporary Final rule. SUMMARY: The Coast Guard...

  18. Two Cenozoic tectonic events of N-S and E-W extension in the Lhasa Terrane: Evidence from geology and geochronology

    Science.gov (United States)

    Huang, Feng; Xu, Ji-Feng; Chen, Jian-Lin; Wu, Jian-Bin; Zeng, Yun-Chuan; Xiong, Qiu-Wei; Chen, Xue-Feng; Yu, Hong-Xia

    2016-02-01

    Cenozoic active structures in the Tibetan Plateau are mainly regional N-S trending extensional faults and grabens, and E-W trending extensional tracks that are related to the transition from syn- to post-collision between India and Asia. E-W trending tracks are parallel to the direction of Neo-Tethyan oceanic convergence and consist of extensional volcanic-sedimentary basins and magmatic dykes in the southern Lhasa Terrane, Tibet. N-S trending tracks comprise faults and grabens, which are widely developed in Tibet. It remains unknown how and when the geodynamic transition from E-W to N-S trending tectonic tracks occurred. This study describes both E-W and N-S trending tectonic tracks identified at Dazi area of southern Lhasa Terrane, where E-W trending mafic dykes intruded a granitoid and late-stage N-S trending felsic dykes cut across E-W trending mafic dykes. Zircons from four granitoid samples yield consistent crystallization ages of ca. 60 Ma and positive εHf(t) values (~+ 9). An altered dioritic vein, which cuts the mafic dykes, yields an age of ca. 53 Ma. These new dating results indicate that E-W trending dykes, which formed due to regional N-S extension, were emplaced between 60 and 53 Ma. In addition, two N-S trending monzonitic porphyritic dykes, which cut the mafic dykes, yield U-Pb zircon ages of ca. 17 Ma with moderate positive εHf(t) values (+ 3 to + 9.6), as well as a NNE-SSW trending quartz monzonitic dyke, which cuts all other types of dykes, yields U-Pb ages of ca. 13 Ma. This suggests that E-W extension took place between 17 and 13 Ma. These results, in combination with existing age data for Gangdese granitoids and mafic magmatism, indicate the occurrence of two major extensional events at 60-53 Ma and 17-13 Ma. In turn, this implies that the transition from E-W to N-S trending tectonic and the onset of E-W extension occurred at ca. 17 Ma or slightly earlier. Paleocene granitoids have geochemical characteristics that are indicative of both

  19. Investigation on Production and Markets of Silica Bricks in China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhongqi; CHU Guosheng; WANG Tiezheng; PAN Shangxin

    2003-01-01

    The annual output of China' s silica brick amounts up to over 300 thousand tons, which accounts for more than 70% of the total output of silica bricks in the world.Besides satisfying domestic markets, China's silica bricks have been exported to many countries and regions such as Japan, USA etc. In this paper, the situation of silica bricks production, technology, sales and exporting have been described. Also suggestions on improvement of silica bricks quality and exporting, corporation with foreign partners have been put forward in order to win larger market share both at home and abroad.

  20. Investigation on Production and Markets of Silica Bricks in China

    Institute of Scientific and Technical Information of China (English)

    ZHANGZhongqi; CHUGuosheng; WANGTiezheng; PANShangxin

    2003-01-01

    The annual output of China's silica brick amounts up to over 300 thousand tons, which accounts for more than 70% of the total oupout of silica bricks in the world. Besides satisfying domestic markets, China's silica bricks have been exported to many countries and retions such as Japan, USA etc. In this paper, the situation of silica bricks production, technology, sales and exporting have been described. Also suggestions on improvement of silica bricks quality and exporting, corporation with foreign partners have been put forward in order to win larger market share both aat home and abroad.

  1. Waveguiding properties and applications of silica nanowires in various environments

    Institute of Scientific and Technical Information of China (English)

    SUI Cheng-hua; WU Ping-hui; ZHAO Pan

    2009-01-01

    Waveguiding properties of silica nanowires in various environments are studied by solving the eigenvalue equations of a circular cross-section waveguide numerically in cylindrical coordinates. The single-mode condition, propagation constants, poynting vector and power distribution inside and outside silica nanowire are calculated. The results show that silica nanowires in water, compared with silica nanowires in air, have higher fraction of the evanescent fields. Due to the sensiti-vity to surrounding environment, silica nanowires are very suitable for sensing elements, which can be used to implement a single-mode fiber optic evanescent wave sensing element of highly sensitive and accurate measurement.

  2. Process for Preparing Epoxy-Reinforced Silica Aerogels

    Science.gov (United States)

    Meador, Mary Ann B (Inventor)

    2016-01-01

    One-pot reaction process for preparing epoxy-reinforced monolithic silica aerogels comprising the reaction of at least one silicon compound selected from the group consisting of alkoxysilanes, orthosilicates and combination thereof in any ratio with effective amounts of an epoxy monomer and an aminoalkoxy silane to obtain an epoxy monomer-silica sol in solution, subsequently preparing an epoxy-monomer silica gel from said silica sol solution followed by initiating polymerization of the epoxy monomer to obtain the epoxy-reinforced monolithic silica aerogel.

  3. New views on the Late Cenozoic tectonic history of northern Colombia

    Science.gov (United States)

    Maurin, T.; Stéphan, J. F.; Mercier de Lépinay, B.; Dhont, D.

    2012-04-01

    The Late Cenozoic strain field in northern Colombia is often described as resulting from both the continuous subduction of the Caribbean plate, ongoing since Late Cretaceous at least, and the tectonic escape of the North Andean Block, starting in early Pliocene. Pieces of evidence from geological field work, interpretation of multichannel seismic reflection profiles, section restoration, seismotectonic data and analysis of satellite images allowed us to precise the timing and mode of interaction for these two main tectonic processes in northern Colombia during the last 5 Ma. This work was part of the GIRCAR project (Groupement Industrie-Recherche CARaïbes), funded by TOTAL S.A.. The San Jacinto fold and thrust belt is usually known as the older part of an accretionary wedge related to the Caribbean subduction. We argue that this fold belt is actually a left-lateral transpressive belt, active since Pliocene time, that reuse older structures formed during an older accretionary episode. This left-lateral transpressive fold belt may be interpreted as the western boundary of the North Andean Block escaping northward. The Sinu wedge, known as the offshore Plio-Quaternary part of the accretionary wedge, accommodates less than 3 mm/yr of convergence. This shortening is at least partly compensated internally by a number of contemporaneous normal faults. The morphology of the Sinu wedge is more likely the one of a gravity collapse, affecting the whole sedimentary pile, towards the deep Colombian basin. Additionally, the Late Miocene to Holocene Magdalena fan, deposited along the northwestern margin of Colombia, above the subduction zone, remains undeformed even after being abandoned. Also, GPS data demonstrate that no shortening is to be expected at present across the subduction zone. Finally, no significant earthquakes was recorded between 0 and 30 km along the subduction zone. These observations can be well reconciled by postulating that the deformation, along the

  4. A chilling perspective on Greenland's early Cenozoic climate from coupled Hf-Nd isotopes

    Science.gov (United States)

    Scher, H. D.; Bizimis, M.; Buckley, W. P., Jr.; Duggan, B.; Bohaty, S. M.; Wilson, P. A.

    2015-12-01

    The prevailing view of northern hemisphere glaciation has been of ice sheets forming on Greenland after 2.7 Ma, with iceberg rafting as early as 15 Ma. This view is incompatible with recent results from global climate/ice sheet models that predict northern hemisphere glaciation only after CO2 falls below ~280 ppmv (occurring at 25 Ma) and with recent sediment evidence for Arctic iceberg rafting as early as the middle Eocene. However, the amount of northern hemisphere ice represented by these sediments is ambiguous and global ice budget calculations for the early Cenozoic are controversial. Here we use coupled Hf-Nd isotopes of oxyhydroxides in sediments from the upper Eocene to lower Oligocene section in ODP Site U1411 (Newfoundland Ridge) to determine when the circum-North Atlantic came under the influence of a mechanical weathering regime. Leached oxyhydroxide Hf-Nd isotopes are an indicator of weathering intensity because mechanical weathering by ice sheets mobilizes the zircon-bound Hf reservoir in the crust, which has extreme unradiogenic eHf values. Chemical weathering produces a distinct seawater array on Hf-Nd diagrams, while seawater exposed to the products of mechanical weathering plot on divergent arrays closer to the Terrestrial Array. Hf-Nd isotopes of Site U1411 leachates are grouped in a near vertical trend between the seawater and terrestrial global reference arrays. Within this group there are four distinct arrays that can be delineated by age. Samples that are late Eocene in age fall along an array that is slightly divergent from the seawater array. The aspect of the Hf-Nd isotope data changes permanently after the first step of the EOT, falling along arrays that are systematically offset in the direction of the terrestrial arrays. The steepest array, most proximal to the terrestrial array, is comprised of samples deposited between 33.7 and 32.2 Ma. These results indicate a circum-North Atlantic weathering regime appeared in the earliest Oligocene.

  5. Improving the Ginkgo CO2 barometer: Implications for the early Cenozoic atmosphere

    Science.gov (United States)

    Barclay, Richard S.; Wing, Scott L.

    2016-04-01

    Stomatal properties of fossil Ginkgo have been used widely to infer the atmospheric concentration of CO2 in the geological past (paleo-pCO2). Many of these estimates of paleo-pCO2 have relied on the inverse correlation between pCO2 and stomatal index (SI - the proportion of epidermal cells that are stomata) observed in recent Ginkgo biloba, and therefore depend on the accuracy of this relationship. The SI - pCO2 relationship in G. biloba has not been well documented, however. Here we present new measurements of SI for leaves of G. biloba that grew under pCO2 from 290 to 430 ppm. We prepared and imaged all specimens using a consistent procedure and photo-documented each count. As in prior studies, we found a significant inverse relationship between SI and pCO2, however, the relationship is more linear, has a shallower slope, and a lower correlation coefficient than previously reported. We examined leaves of G. biloba grown under pCO2 of 1500 ppm, but found they had highly variable SI and a large proportion of malformed stomata. We also measured stomatal dimensions, stomatal density, and the carbon isotope composition of G. biloba leaves in order to test a mechanistic model for inferring pCO2. This model overestimated observed pCO2, performing less well than the SI method between 290 and 430 ppm. We used our revised SI-pCO2 response curve, and new observations of selected fossils, to estimate late Cretaceous and Cenozoic pCO2 from fossil Ginkgo adiantoides. All but one of the new estimates is below 800 ppm, and together they show little long-term change in pCO2 or relation to global temperature. The low Paleogene pCO2 levels indicated by the Ginkgo SI proxy are not consistent with the high pCO2 inferred by some climate and carbon cycle models. We cannot currently resolve the discrepancy, but greater agreement between proxy data and models may come from a better understanding of the stomatal response of G. biloba to elevated pCO2, better counts and measurements of

  6. The oceanic sediment barrier

    International Nuclear Information System (INIS)

    Burial within the sediments of the deep ocean floor is one of the options that have been proposed for the disposal of high-level radioactive waste. An international research programme is in progress to determine whether oceanic sediments have the requisite properties for this purpose. After summarizing the salient features of this programme, the paper focuses on the Great Meteor East study area in the Northeast Atlantic, where most oceanographic effort has been concentrated. The geological geochemical and geotechnical properties of the sediments in the area are discussed. Measurements designed to determine the rate of pore water movement through the sediment column are described. Our understanding of the chemistry of both the solid and pore-water phases of the sediment are outlined, emphasizing the control that redox conditions have on the mobility of, for example, naturally occurring manganese and uranium. The burial of instrumented free-fall penetrators to depths of 30 m beneath the ocean floor is described, modelling one of the methods by which waste might be emplaced. Finally, the nature of this oceanic environment is compared with geological environments on land and attention is drawn to the gaps in our knowledge that must be filled before oceanic burial can be regarded as an acceptable disposal option. (author)

  7. Determination of picomolar beryllium levels in seawater with inductively coupled plasma mass spectrometry following silica-gel preconcentration

    International Nuclear Information System (INIS)

    Highlights: • We developesd the simplest and robust SPE method for ultra low picomolar level beryllium in seawater. • Just silica gel column can quantitatively adsorb beryllium in neutral pH condition containing natural seawater. • EDTA solution can eliminate seawater matrixes retaining Be in the column, which optimize to ICP-MS detemination. • Accurate and precise Be data have been obtained for natural seawater from North Pacific Ocean. - Abstract: A robust and rapid method for the determination of natural levels of beryllium (Be) in seawater was developed to facilitate mapping Be concentrations in the ocean. A solid-phase extraction method using a silica gel column was applied for preconcentration and purification of Be in seawater prior to determination of Be concentrations with inductively coupled plasma mass spectrometry (ICP-MS). Be was quantitatively adsorbed onto silica gel from solutions with pH values ranging from 6.3 to 9, including natural seawater. The chelating agent ethylenediamine tetraacetic acid was used to remove other ions in the seawater matrix (Na, Mg, and Ca) that interfere with the ICP-MS analysis. The reproducibility of the method was 3% based on triplicate analyses of natural seawater samples, and the detection limit was 0.4 pmol kg−1 for 250 mL of seawater, which is sufficient for the analysis of seawater in the open ocean. The method was then used to determine the vertical profile of Be in the eastern North Pacific Ocean, which was found to be a recycled-type profile in which the Be concentration increased with depth from the surface (7.2 pmol kg−1 at <200 m) to deep water (29.2 pmol kg−1 from 3500 m to the bottom)

  8. Determination of picomolar beryllium levels in seawater with inductively coupled plasma mass spectrometry following silica-gel preconcentration

    Energy Technology Data Exchange (ETDEWEB)

    Tazoe, Hirofumi, E-mail: tazoe@cc.hirosaki-u.ac.jp [Department of Radiation Chemistry, Institute of Radiation Emergency Mediation, Hirosaki University, 66-1 Hon-cho, Hirosaki, Aomori 036-8564 (Japan); College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan); Yamagata, Takeyasu [College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan); Obata, Hajime [Atmosphere and Ocean Research Institute, The Tokyo University, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8564 (Japan); Nagai, Hisao [College of Humanities and Sciences, Nihon University, 3-25-40, Sakurajosui, Setagaya-ku, Tokyo 156-8550 (Japan)

    2014-12-10

    Highlights: • We developesd the simplest and robust SPE method for ultra low picomolar level beryllium in seawater. • Just silica gel column can quantitatively adsorb beryllium in neutral pH condition containing natural seawater. • EDTA solution can eliminate seawater matrixes retaining Be in the column, which optimize to ICP-MS detemination. • Accurate and precise Be data have been obtained for natural seawater from North Pacific Ocean. - Abstract: A robust and rapid method for the determination of natural levels of beryllium (Be) in seawater was developed to facilitate mapping Be concentrations in the ocean. A solid-phase extraction method using a silica gel column was applied for preconcentration and purification of Be in seawater prior to determination of Be concentrations with inductively coupled plasma mass spectrometry (ICP-MS). Be was quantitatively adsorbed onto silica gel from solutions with pH values ranging from 6.3 to 9, including natural seawater. The chelating agent ethylenediamine tetraacetic acid was used to remove other ions in the seawater matrix (Na, Mg, and Ca) that interfere with the ICP-MS analysis. The reproducibility of the method was 3% based on triplicate analyses of natural seawater samples, and the detection limit was 0.4 pmol kg{sup −1} for 250 mL of seawater, which is sufficient for the analysis of seawater in the open ocean. The method was then used to determine the vertical profile of Be in the eastern North Pacific Ocean, which was found to be a recycled-type profile in which the Be concentration increased with depth from the surface (7.2 pmol kg{sup −1} at <200 m) to deep water (29.2 pmol kg{sup −1} from 3500 m to the bottom)

  9. Meso-Cenozoic tectonic evolution and uranium potential evaluations of basins in Beishan-Gansu corridor region

    International Nuclear Information System (INIS)

    Beishan-Gansu Corridor region is located at the intersection of the plates of Tarim, North China, Kazakhstan, Siberia and Qaidam. During the Meso-Cenozoic, the region experienced movements of Indo-sinian, Yanshanian, Sichuanian, North China, Himalayan and Neotectonic, and over 20 medium-small size superimposed continental basins were formed. On the basis of analyzing the tectonic stress field, sediment-filling and structure-deformation; the general trending of tectonic evolution in the Meso-Cenozoic is summarized as three-time compressional uplifting and two-time extensional down-faulting. The different evolution of basins under the above mentioned setting can be divided into six stages according to characteristics of filled sediment. The sand bodies developed in down-faulted basins are favorable for uranium ore-formation as they are formed under humid paleoclimates, and rich in reducing matter. Therefore, the Lower-Middle Jurassic is selected as the main target horizon for sandstone-hosted uranium deposit, and the Lower Cretaceous as the minor one. Although the tectonic reactivation of the target horizon after its deposition was generally strong, the slopes formed in some basins could be favorable for the infiltration of uranium-and oxygen-bearing groundwater into sand bodies and form uranium deposits. According to the favorable sand bodies and tectonic reactivation, the northern parts of Chaoshui and Bayingobi basins are regarded as potential regions which are worthy of further exploration. (authors)

  10. Water Vapor Effects on Silica-Forming Ceramics

    Science.gov (United States)

    Opila, E. J.; Greenbauer-Seng, L. (Technical Monitor)

    2000-01-01

    Silica-forming ceramics such as SiC and Si3N4 are proposed for applications in combustion environments. These environments contain water vapor as a product of combustion. Oxidation of silica-formers is more rapid in water vapor than in oxygen. Parabolic oxidation rates increase with the water vapor partial pressure with a power law exponent value close to one. Molecular water vapor is therefore the mobile species in silica. Rapid oxidation rates and large amounts of gases generated during the oxidation reaction in high water vapor pressures may result in bubble formation in the silica and nonprotective scale formation. It is also shown that silica reacts with water vapor to form Si(OH)4(g). Silica volatility has been modeled using a laminar flow boundary layer controlled reaction equation. Silica volatility depends on the partial pressure of water vapor, the total pressure, and the gas velocity. Simultaneous oxidation and volatilization reactions have been modeled with paralinear kinetics.

  11. Preparation and Characterization of Silica-Enoxil Nanobiocomposites

    Science.gov (United States)

    Kuzema, Pavlo O.; Laguta, Iryna V.; Stavinskaya, Oksana N.; Kazakova, Olga A.; Borysenko, Mykola V.; Lupaşcu, Tudor

    2016-02-01

    Silica-Enoxil nanobiocomposites with 13 %w of Enoxil were prepared either by mechanical mixing of corresponding powders or by sorptive modification of fumed silica powder with aqueous Enoxil solution under fluidized bed conditions. The interaction of fumed silica with Enoxil and the properties of silica-Enoxil composites have been investigated using IR spectroscopy, thermogravimetric analysis, and quantum chemistry methods, as well as by means of water absorption, Enoxil desorption, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. It has been shown that the main biomolecules of Enoxil composition interact with silica involving their hydroxyl groups and surface silanol groups. The water absorption of silica-Enoxil nanocomposites was found to be less than that for the individual components. The Enoxil biomolecules are readily and completely desorbed from silica surface into water, and the antioxidant activity of desorbed Enoxil is practically the same as that for the just dissolved one.

  12. Preparation and Characterization of Silica-Enoxil Nanobiocomposites.

    Science.gov (United States)

    Kuzema, Pavlo O; Laguta, Iryna V; Stavinskaya, Oksana N; Kazakova, Olga A; Borysenko, Mykola V; Lupaşcu, Tudor

    2016-12-01

    Silica-Enoxil nanobiocomposites with 13 %w of Enoxil were prepared either by mechanical mixing of corresponding powders or by sorptive modification of fumed silica powder with aqueous Enoxil solution under fluidized bed conditions. The interaction of fumed silica with Enoxil and the properties of silica-Enoxil composites have been investigated using IR spectroscopy, thermogravimetric analysis, and quantum chemistry methods, as well as by means of water absorption, Enoxil desorption, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. It has been shown that the main biomolecules of Enoxil composition interact with silica involving their hydroxyl groups and surface silanol groups. The water absorption of silica-Enoxil nanocomposites was found to be less than that for the individual components. The Enoxil biomolecules are readily and completely desorbed from silica surface into water, and the antioxidant activity of desorbed Enoxil is practically the same as that for the just dissolved one. PMID:26847694

  13. Indian Ocean Traffic: Introduction

    Directory of Open Access Journals (Sweden)

    Lola Sharon Davidson

    2012-06-01

    Full Text Available Like the Mediterranean, the Indian Ocean has been a privileged site of cross-cultural contact since ancient times. In this special issue, our contributors track disparate movements of people and ideas around the Indian Ocean region and explore the cultural implications of these contacts and their role in processes that we would come to call transnationalization and globalisation. The nation is a relatively recent phenomenon anywhere on the globe, and in many countries around the Indian Ocean it was a product of colonisation and independence. So the processes of exchange, migration and cultural influence going on there for many centuries were mostly based on the economics of goods and trade routes, rather than on national identity and state policy.

  14. Ocean energy systems

    Science.gov (United States)

    1984-04-01

    The Johns Hopkins University Applied Physics Laboratory is engaged in developing ocean thermal energy conversion (OTEC) systems that are to provide synthetic fuels or an energy intensive product such as ammonia or aluminum. The work also includes assessment and design concepts for hybrid plants, such as geothermal-OTEC plants. The laboratory also has a technical advisory role with respect to DOE/DOET's management of the preliminary design activity of an industry team headed by Ocean Thermal Corporation that is designing an OTEC pilot plant that could be built in shallow water off the shore of Oahu, Hawaii. In addition, the Laboratory is now taking part in a program to evaluate and test the pneumatic wave energy conversion system, an ocean energy device consisting of a turbine that is air driven as a result of wave action in a chamber.

  15. Eastern Pacific Ocean Conference

    Science.gov (United States)

    The promotion of interaction among investigators of all oceanographic disciplines studying the eastern Pacific Ocean was the goal of the 1990 Eastern Pacific Ocean Conference (EPOC), held October 17-19 on the snow-covered slopes of Mt. Hood, Oreg. Thirty oceanographers representing all disciplines attended.Dick Barber, Duke University Marine Lab, Beaufort, N.C., chaired a session on the eastern equatorial Pacific Ocean, emphasizing issues related to biological activity. Steve Ramp of the Naval Postgraduate School in Montery, Calif., chaired a session on recent results from northern and central California experiments. On October 19, following an early morning earthquake, a business meeting and discussions regarding a collaboration in future experiments were held.

  16. LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

    Directory of Open Access Journals (Sweden)

    R. E. Zeebe

    2012-01-01

    Full Text Available The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

  17. Near coastal ocean attributes of salmon - Ocean Survival of Salmonids

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A study to evaluate the role of changing ocean conditions on growth and survival of juvenile salmon from the Columbia River basin as they enter the Columbia River...

  18. On the origin of pseudoleucite from Cenozoic phonolite dykes from Loučná/Böhmisch Wiesenthal, Krušné hory/Erzgebirge Mts., Bohemia

    Czech Academy of Sciences Publication Activity Database

    Pivec, Edvín; Ulrych, Jaromír; Langrová, Anna

    2004-01-01

    Roč. 179, č. 3 (2004), s. 221-238. ISSN 0028-3649 R&D Projects: GA AV ČR(CZ) IAA3048201 Keywords : pseudoleucite * phonolite * tinguaite * dyke * mineralogy * petrology * Cenozoic * Krušné hory/Erzgebirge Mts. * Bohemian Massif Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.430, year: 2004

  19. Study on the relationships between the structural evolution and sandstone-type uranium mineralization in mesozoic era and cenozoic era in the northern of Chaidam basin

    International Nuclear Information System (INIS)

    By detailed expounding the characteristics of the Mesozoic and Cenozoic structural evolution in northern of Chaidam basin, the author inquires into its relationships with the sandstone-type uranium mineralization, analyzes the prospect of forming uranium deposit, and thinks that the Mesozoic and Cenozoic strata are mainly controlled by the tectonic role of the later Yanshan movement and the later Cenozoic era. The north-west palaeo-structural slope belt is formed in the later Cretacous Epoch that is favorable for developing palaeo-interlayer oxidized zone. After the slightly extensional role of the oldest Tertiary and the early Plioeene, the middle and lower Jurassic were buried, and the block-imbricated slope belts are formed in the tectonic movement of the later Cenozoic, which are favorable for developing recent interlayer oxidized zone. According to drilling, it has the conditions for forming palaeo-recent interlayer oxidized zone sandstone-type uranium deposit at the northern of Chaidam basin. Finally, the author lays his finger on the prospecting of uranium. (authors)

  20. Clouds over Open Ocean

    Science.gov (United States)

    1981-01-01

    The heavy concentration of these cirrocumulus and nimbostratus clouds over open ocean - location unknown, indicate that a heavy downpouring of rain is occuring on the Earth's surface below. Towering anvils, seen rising high above the base cloud cover and casting long shadows, also indicate high winds and possible tornado activity.

  1. Fukushima and the ocean

    Science.gov (United States)

    Buesseler, Ken

    2013-04-01

    The triple disaster of the March 11, 2011 earthquake, tsunami, and subsequent radiation releases at Fukushima Dai-ichi were unprecedented events for the ocean and society. The earthquake was the fourth largest ever recorded; the tsunami resulted in over 20,000 dead or missing and destroyed entire towns; and the radiation releases from the Fukushima Dai-ichi nuclear power plants created the largest accidental release of man-made radionuclides to the oceans in history— a release that continues to this day. Compared to monitoring on land, studies of the ocean are far fewer, yet the area impacted and quantity delivered- 80% of all radioactivity released- is far greater. For oceanographers, this presents a challenge of unprecedented scope and complexity: to understand exactly how these events played out, how radiation continues to move through the marine system (including important seafood items), and, in turn, how best to communicate scientific findings that will inform public policy decisions far into the future. This presentation will provide an overview of the sources and fate of radionuclides released from Fukushima to the ocean. An emphasis will be given on the sources of cesium, its transport in waters, and fluxes associated with sinking particles and accumulation in sediments.

  2. Enhanced ocean observational capability

    Energy Technology Data Exchange (ETDEWEB)

    Volpe, A M; Esser, B K

    2000-01-10

    Coastal oceans are vital to world health and sustenance. Technology that enables new observations has always been the driver of discovery in ocean sciences. In this context, we describe the first at sea deployment and operation of an inductively coupled plasma mass spectrometer (ICPMS) for continuous measurement of trace elements in seawater. The purpose of these experiments was to demonstrate that an ICPMS could be operated in a corrosive and high vibration environment with no degradation in performance. Significant advances occurred this past year due to ship time provided by Scripps Institution of Oceanography (UCSD), as well as that funded through this project. Evaluation at sea involved performance testing and characterization of several real-time seawater analysis modes. We show that mass spectrometers can rapidly, precisely and accurately determine ultratrace metal concentrations in seawater, thus allowing high-resolution mapping of large areas of surface seawater. This analytical capability represents a significant advance toward real-time observation and understanding of water mass chemistry in dynamic coastal environments. In addition, a joint LLNL-SIO workshop was convened to define and design new technologies for ocean observation. Finally, collaborative efforts were initiated with atmospheric scientists at LLNL to identify realistic coastal ocean and river simulation models to support real-time analysis and modeling of hazardous material releases in coastal waterways.

  3. Investigating Ocean Pollution.

    Science.gov (United States)

    LeBeau, Sue

    1998-01-01

    Describes a fifth-grade class project to investigate two major forms of ocean pollution: plastics and oil. Students work in groups and read, discuss, speculate, offer opinions, and participate in activities such as keeping a plastics journal, testing the biodegradability of plastics, and simulating oil spills. Activities culminate in…

  4. Ocean Dumping Control Act

    International Nuclear Information System (INIS)

    This Act provides for the control of dumping of wastes and other substances in the ocean in accordance with the London Convention of 1972 on Prevention of Marine Pollution by the Dumping of Wastes and other Matter to which Canada is a Party. Radioactive wastes are included in the prohibited and restricted substances. (NEA)

  5. An Ocean of Possibilities

    Science.gov (United States)

    Williams, Doug

    2010-01-01

    For more than one hundred years teachers have paddled beside the great ocean of mathematical adventure. Between them they have taught millions of young people. A few have dived in and kept swimming, some have lingered on the shore playing in pools, but most have dipped their toes in and run like heck in the other direction never to return. There…

  6. Enhanced Ocean Scatterometry

    NARCIS (Netherlands)

    Fois, F.

    2015-01-01

    An ocean scatterometer is an active microwave instrument which is designed to determine the normalized radar cross section (NRCS) of the sea surface. Scatterometers transmit pulses towards the sea surface and measure the reflected energy. The primary objective of spaceborne scatterometers is to meas

  7. Ocean Thermal Energy.

    Science.gov (United States)

    Berkovsky, Boris

    1987-01-01

    Describes Ocean Thermal Energy Conservation (OTEC) as a method for exploiting the temperature difference between warm surface waters of the sea and its cold depths. Argues for full-scale demonstrations of the technique for producing energy for coastal regions. (TW)

  8. The Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    by satellite-derived ocean color images (Banse and English, 2000; Wiggert et al., 2005, and references therein). Fertilization of comparable magnitude also occurs along the west coast of India, albeit within a much narrower coastal belt (Fig. 14.3F; Jayakumar...

  9. Assembly of functional gold nanoparticle on silica microsphere.

    Science.gov (United States)

    Wang, Hsuan-Lan; Lee, Fu-Cheng; Tang, Tse-Yu; Zhou, Chenguang; Tsai, De-Hao

    2016-05-01

    We demonstrate a controlled synthesis of silica microsphere with the surface-decorated functional gold nanoparticles. Surface of silica microsphere was modified by 3-aminopropypltriethoxysilane and 3-aminopropyldimethylethoxysilane to generate a positive electric field, by which the gold nanoparticles with the negative charges (unconjugated, thiolated polyethylene glycol functionalized with the traceable packing density and conformation) were able to be attracted to the silica microsphere. Results show that both the molecular conjugation on gold nanoparticle and the uniformity in the amino-silanization of silica microsphere influenced the loading and the homogeneity of gold nanoparticles on silica microsphere. The 3-aminopropyldimethylethoxysilane-functionalized silica microsphere provided an uniform field to attract gold nanoparticles. Increasing the ethanol content in aminosilane solution significantly improved the homogeneity and the loading of gold nanoparticles on the surface of silica microsphere. For the gold nanoparticle, increasing the molecular mass of polyethylene glycol yielded a greater homogeneity but a lower loading on silica microsphere. Bovine serum albumin induced the desorption of gold nanoparticles from silica microsphere, where the extent of desorption was suppressed by the presence of high-molecular mass polyethylene glycol on gold nanoparticles. This work provides the fundamental understanding for the synthesis of gold nanoparticle-silica microsphere constructs useful to the applications in chemo-radioactive therapeutics. PMID:26874272

  10. Ocean Ridges and Oxygen

    Science.gov (United States)

    Langmuir, C. H.

    2014-12-01

    The history of oxygen and the fluxes and feedbacks that lead to its evolution through time remain poorly constrained. It is not clear whether oxygen has had discrete steady state levels at different times in Earth's history, or whether oxygen evolution is more progressive, with trigger points that lead to discrete changes in markers such as mass independent sulfur isotopes. Whatever this history may have been, ocean ridges play an important and poorly recognized part in the overall mass balance of oxidants and reductants that contribute to electron mass balance and the oxygen budget. One example is the current steady state O2 in the atmosphere. The carbon isotope data suggest that the fraction of carbon has increased in the Phanerozoic, and CO2 outgassing followed by organic matter burial should continually supply more O2 to the surface reservoirs. Why is O2 not then increasing? A traditional answer to this question would relate to variations in the fraction of burial of organic matter, but this fraction appears to have been relatively high throughout the Phanerozoic. Furthermore, subduction of carbon in the 1/5 organic/carbonate proportions would contribute further to an increasingly oxidized surface. What is needed is a flux of oxidized material out of the system. One solution would be a modern oxidized flux to the mantle. The current outgassing flux of CO2 is ~3.4*1012 moles per year. If 20% of that becomes stored organic carbon, that is a flux of .68*1012 moles per year of reduced carbon. The current flux of oxidized iron in subducting ocean crust is ~2*1012 moles per year of O2 equivalents, based on the Fe3+/Fe2+ ratios in old ocean crust compared to fresh basalts at the ridge axis. This flux more than accounts for the incremental oxidizing power produced by modern life. It also suggests a possible feedback through oxygenation of the ocean. A reduced deep ocean would inhibit oxidation of ocean crust, in which case there would be no subduction flux of oxidized

  11. Adsorption of bacteriocins by ingestible silica compounds.

    Science.gov (United States)

    Wan, J; Gordon, J; Hickey, M W; Mawson, R F; Coventry, M J

    1996-08-01

    Bacteriocins including nisin, pediocin PO2, brevicin 286 and piscicolin 126 were adsorbed from culture supernates by various food-grade porous silica anti-caking agents and the food colourant, titanium dioxide. All the porous silica (calcium silicate or silicon dioxide) materials showed substantial capacity in adsorbing bacteriocin activities from the culture supernate and biological activity was recovered in the adsorbents. In contrast, the food colourant titanium dioxide adsorbed most of the bacteriocin activity from the supernate, with minimal biological activity retained in the adsorbent. Experiments with piscicolin 126 showed that optimum adsorption could be achieved with Micro-Cel E within 30 min, independent of the supernate pH (2.0-10.0). Piscicolin activity of up to 5 x 10(7) AU g(-1) of Micro-Cel E was obtained after adsorption from culture supernates and the adsorbed piscicolin demonstrated substantial biological activity against Listeria monocytogenes in both broth and a milk growth medium. PMID:8926221

  12. Carbon nanomaterials in silica aerogel matrices

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Christopher E [Los Alamos National Laboratory; Chavez, Manuel E [Los Alamos National Laboratory; Duque, Juan G [Los Alamos National Laboratory; Gupta, Gautam [Los Alamos National Laboratory; Doorn, Stephen K [Los Alamos National Laboratory; Dattelbaum, Andrew M [Los Alamos National Laboratory; Obrey, Kimberly A D [Los Alamos National Laboratory

    2010-01-01

    Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.

  13. Novel bioactive materials: silica aerogel and hybrid silica aerogel/pseudo wollastonite

    Energy Technology Data Exchange (ETDEWEB)

    Resendiz-Hernandez, P. J.; Cortes-Hernandez, D. a.; Saldivar-Ramirez, M. M. G.; Acuna-gutierrez, I. O.; Flores-Valdes, A.; Torres-rincon, S.; Mendez-Nonell, J.

    2014-07-01

    Silica aerogel and hybrid silica aerogel/pseudo wollastonite materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS) using also methanol (MeOH) and pseudo wollastonite particles. The gels obtained were dried using a novel process based on an ambient pressure drying. Hexane and hexamethyl-disilazane (HMDZ) were the solvents used to chemically modify the surface. In order to assess bioactivity, aerogels, without and with pseudowollastonite particles, were immersed in simulated body fluid (SBF) for 7 and 14 days. The hybrid silica aerogel/pseudo wollastonite showed a higher bioactivity than that observed for the single silica aerogel. However, as in both cases a lower bioactivity was observed, a biomimetic method was also used to improve it. In this particular method, samples of both materials were immersed in SBF for 7 days followed by their immersion in a more concentrated solution (1.5 SBF) for 14 days. A thick and homogeneous bonelike apatite layer was formed on the biomimetically treated materials. Thus, bioactivity was successfully improved even on the aerogel with no pseudowollastonite particles. As expected, the hybrid silica aerogel/pseudowollastonite particles showed a higher bioactivity. (Author)

  14. Adsorption of Polyether Block Copolymers at Silica-Water and Silica-Ethylammonium Nitrate Interfaces.

    Science.gov (United States)

    Chen, Zhengfei; Kobayashi, Yumi; Webber, Grant B; Ueno, Kazuhide; Watanabe, Masayoshi; Warr, Gregory G; Atkin, Rob

    2015-06-30

    Atomic force microscope (AFM) force curves and images are used to characterize the adsorbed layer structure formed by a series of diblock copolymers with solvophilic poly(ethylene oxide) (PEO) and solvophobic poly(ethyl glycidyl ether) (PEGE) blocks at silica-water and silica-ethylammoniun nitrate (EAN, a room temperature ionic liquid (IL)) interfaces. The diblock polyethers examined are EGE109EO54, EGE113EO115, and EGE104EO178. These experiments reveal how adsorbed layer structure varies as the length of the EO block varies while the EGE block length is kept approximately constant; water is a better solvent for PEO than EAN, so higher curvature structures are found at the interface of silica with water than with EAN. At silica-water interfaces, EGE109EO54 forms a bilayer and EGE113EO115 forms elongated aggregates, while a well-ordered array of spheres is present for EGE104EO178. EGE109EO54 does not adsorb at the silica-EAN interface because the EO chain is too short to compete with the ethylammonium cation for surface adsorption sites. However, EGE113EO115 and EGE104EO178 do adsorb and form a bilayer and elongated aggregates, respectively. PMID:26039658

  15. Novel bioactive materials: silica aerogel and hybrid silica aerogel/pseudo wollastonite

    International Nuclear Information System (INIS)

    Silica aerogel and hybrid silica aerogel/pseudo wollastonite materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS) using also methanol (MeOH) and pseudo wollastonite particles. The gels obtained were dried using a novel process based on an ambient pressure drying. Hexane and hexamethyl-disilazane (HMDZ) were the solvents used to chemically modify the surface. In order to assess bioactivity, aerogels, without and with pseudowollastonite particles, were immersed in simulated body fluid (SBF) for 7 and 14 days. The hybrid silica aerogel/pseudo wollastonite showed a higher bioactivity than that observed for the single silica aerogel. However, as in both cases a lower bioactivity was observed, a biomimetic method was also used to improve it. In this particular method, samples of both materials were immersed in SBF for 7 days followed by their immersion in a more concentrated solution (1.5 SBF) for 14 days. A thick and homogeneous bonelike apatite layer was formed on the biomimetically treated materials. Thus, bioactivity was successfully improved even on the aerogel with no pseudowollastonite particles. As expected, the hybrid silica aerogel/pseudowollastonite particles showed a higher bioactivity. (Author)

  16. A unique coral biomineralization pattern has resisted 40 million years of major ocean chemistry change

    Science.gov (United States)

    Stolarski, Jarosław; Bosellini, Francesca R.; Wallace, Carden C.; Gothmann, Anne M.; Mazur, Maciej; Domart-Coulon, Isabelle; Gutner-Hoch, Eldad; Neuser, Rolf D.; Levy, Oren; Shemesh, Aldo; Meibom, Anders

    2016-06-01

    Today coral reefs are threatened by changes to seawater conditions associated with rapid anthropogenic global climate change. Yet, since the Cenozoic, these organisms have experienced major fluctuations in atmospheric CO2 levels (from greenhouse conditions of high pCO2 in the Eocene to low pCO2 ice-house conditions in the Oligocene-Miocene) and a dramatically changing ocean Mg/Ca ratio. Here we show that the most diverse, widespread, and abundant reef-building coral genus Acropora (20 morphological groups and 150 living species) has not only survived these environmental changes, but has maintained its distinct skeletal biomineralization pattern for at least 40 My: Well-preserved fossil Acropora skeletons from the Eocene, Oligocene, and Miocene show ultra-structures indistinguishable from those of extant representatives of the genus and their aragonitic skeleton Mg/Ca ratios trace the inferred ocean Mg/Ca ratio precisely since the Eocene. Therefore, among marine biogenic carbonate fossils, well-preserved acroporid skeletons represent material with very high potential for reconstruction of ancient ocean chemistry.

  17. A unique coral biomineralization pattern has resisted 40 million years of major ocean chemistry change

    Science.gov (United States)

    Stolarski, Jarosław; Bosellini, Francesca R.; Wallace, Carden C.; Gothmann, Anne M.; Mazur, Maciej; Domart-Coulon, Isabelle; Gutner-Hoch, Eldad; Neuser, Rolf D.; Levy, Oren; Shemesh, Aldo; Meibom, Anders

    2016-01-01

    Today coral reefs are threatened by changes to seawater conditions associated with rapid anthropogenic global climate change. Yet, since the Cenozoic, these organisms have experienced major fluctuations in atmospheric CO2 levels (from greenhouse conditions of high pCO2 in the Eocene to low pCO2 ice-house conditions in the Oligocene-Miocene) and a dramatically changing ocean Mg/Ca ratio. Here we show that the most diverse, widespread, and abundant reef-building coral genus Acropora (20 morphological groups and 150 living species) has not only survived these environmental changes, but has maintained its distinct skeletal biomineralization pattern for at least 40 My: Well-preserved fossil Acropora skeletons from the Eocene, Oligocene, and Miocene show ultra-structures indistinguishable from those of extant representatives of the genus and their aragonitic skeleton Mg/Ca ratios trace the inferred ocean Mg/Ca ratio precisely since the Eocene. Therefore, among marine biogenic carbonate fossils, well-preserved acroporid skeletons represent material with very high potential for reconstruction of ancient ocean chemistry. PMID:27302371

  18. Lithium isotopes in foraminifera shells as a novel proxy for the ocean dissolved inorganic carbon (DIC)

    Science.gov (United States)

    Vigier, Nathalie; Rollion-Bard, Claire; Levenson, Yaël; Erez, Jonathan

    2015-01-01

    Past ocean pH and pCO2 are critical parameters for establishing relationships between Earth's climate and the carbon cycle. Previous pCO2 estimates are associated with large uncertainties and are debated. In this study, laboratory cultures of the foraminiferan genus Amphistegina were performed in order to examine the possible factors that control the Li isotope composition (δ7Li) of their shells. δ7Li is insensitive to temperature and pH variations but correlates positively with the Dissolved Inorganic Carbon (DIC) of seawater. Li/Ca ratio in the shells shows negative correlation with δ7Li, consistent with published data for planktonic foraminifera from core tops and from short periods during the Cenozoic. We propose that the sensitivity of δ7Li and Li/Ca ratio to DIC is a biological phenomenon and is related to biomineralization mechanisms in foraminifera. We used the published foraminiferal δ7Li records, and our experimental results, to determine the paleo-ocean DIC and pH for the last glacial-interglacial cycle. The results are consistent with published estimates of pH and pCO2 based on boron isotopes and ice cores. We suggest Li and its isotopes may serve as a new complementary proxy for the paleo-ocean carbonate chemistry.

  19. Stretched pulse Yb3+:silica fibre laser

    OpenAIRE

    Cautaerts, V.; Richardson, D.J.; Paschotta, R.; Hanna, D.C.

    1997-01-01

    We report what we believe to be the first results on short-pulse generation in Yb3+:silica fiber. By applying the stretched pulse technique in a unidirectional, polarization-switch Yb3+ fiber laser incorporating a prism-based dispersive delay line, we obtain self-start mode locking and 100pJ pulses that can be compressed to give clean chirp-free

  20. Crystallization of hollow mesoporous silica nanoparticles.

    Science.gov (United States)

    Drisko, Glenna L; Carretero-Genevrier, Adrian; Perrot, Alexandre; Gich, Martí; Gàzquez, Jaume; Rodriguez-Carvajal, Juan; Favre, Luc; Grosso, David; Boissière, Cédric; Sanchez, Clément

    2015-03-11

    Complex 3D macrostructured nanoparticles are transformed from amorphous silica into pure polycrystalline α-quartz using catalytic quantities of alkaline earth metals as devitrifying agent. Walls as thin as 10 nm could be crystallized without losing the architecture of the particles. The roles of cation size and the mol% of the incorporated devitrifying agent in crystallization behavior are studied, with Mg(2+), Ca(2+), Sr(2+) and Ba(2+) all producing pure α-quartz under certain conditions. PMID:25503642