WorldWideScience
1

Permian Basin as a radioactive waste repository  

International Nuclear Information System (INIS)

The Permian Basin comprises portions of many structural basins in which halite was deposited close together aerially during the Permian Period of time. It contains at least five areas where salt beds within a formation cumulatively total greater than 200 feet, and are overlain by between 1,000 and 5,000 feet of strata: the Colorado-Kansas, Kansas, Oklahoma-Texas, Clovis and Carlsbad areas. A few other areas within the Permian Basin may contain salt beds collectively greater than 200 feet thick. The Carlsbad area contains a great thickness of salt and covers a very large area. For the Clovis and Oklahoma-Texas areas there is little data available for the Texas portions. The Kansas area has the only halite mines with rooms comparable to those of the proposed waste repository facility. There is little data available for the Colorado-Kansas area, especially for the Colorado portion. The Permian Basin major tectonic elements were formed before deposition of Permian salt beds, and only minor igneous activity and possible fault movement is along the periphery. The greatest seismic activity is associated with the Nemaha Ridge along the northeast side of the Permian Basin, and there is no proven movement, only a suggestion of movement in the form of lineaments to have caused earthquakes. All of the Permian Basin is in zone 1 of Coffman and Cloud (1970) where only distant earthquakes may cause damage to structures; therefore, ground rupture is not anticipated in the Permian Basture is not anticipated in the Permian Basin during the time that the radioactive waste is dangerous

2

Exploratory shaft conceptual design report: Permian Basin  

International Nuclear Information System (INIS)

This conceptual design report summarizes the conceptualized design for an exploratory shaft facility at a representative site in the Permian Basin locatd in the western part of Texas. Conceptualized designs for other possible locations (Paradox Basin in Utah and Gulf Interior Region salt domes in Louisiana and Mississippi) are summarized in separate reports. The purpose of the exploratory shaft facility is to provide access to the reference repository horizon to permit in situ testing of the salt. The in situ testing is necessary to verify repository salt design parameters, evaluate isotropy and homogeneity of the salt, and provide a demonstration of the constructability and confirmation of the design to gain access to the repository. The fundamental purpose of this conceptual design report is to assure the feasibility of the exploratory shaft project and to develop a reliable cost estimate and realistic schedule. Because a site has not been selected and site-specific subsurface data are not available, it has been necessary to make certain assumptions in order to develop a conceptual design for an exploratory shaft facility in salt. As more definitive information becomes available to support the design process, adjustments in the projected schedule and estimated costs will be required

3

Thermal conductivity of Permian Basin embedded salt at elevated pressure  

International Nuclear Information System (INIS)

The authors report on the results of measurements of thermal conductivity made on five core samples of bedded rock salt from the Permian Basin in Texas. This work was done in line with the premise that rock salt formations are among the leading contenders as sites for nuclear waste disposal

4

Injection technology increases oil recovery at Permian Basin  

Energy Technology Data Exchange (ETDEWEB)

This article provided a brief overview of the positive field results of the Powerwave injection technology at an oil field in the Permian Basin. The patented injection technology uses pulses of fluid pressure to create momentary elastic flexure of the pore structure to improve the flow of fluids in sedimentary soils and fractured rock, thereby optimizing the performance of chemical enhanced oil recovery technologies, liquid carbon dioxide injection, water injection, and surfactant/polymer flooding to effectively increase oil recovery. In the example of the West Texas waterflood, the Powerwave technology generated an overall production increase of nearly 50 percent. The significant improvements in production and the increased profitability that resulted from the installation of the Powerwave equipment are expected generate interest in the technology from other operators seeking to maximize oil recovery in their fields. The Edmonton-based company is actively pursuing other contracts in the Permian Basin. 1 fig., 1 ref.

Anon.

2010-09-15

5

Structure of the Anayet Permian basin (Axial Zone, Central Pyrenees)  

Science.gov (United States)

The Anayet Permian basin was generated by strike-slip tectonics that opened subsident basins with pull-apart geometries in the western Spanish Axial Zone (between the Aragon and Tena valleys). A continental succession of Permian age, that represents the first post-variscan deposits in the area, fills the basin and covers discordantly Devonian to Carboniferous limestones, sandstones and slates. Permian deposits have been classically divided in four main detrital groups, with three basic volcanic episodes interbedded (Gisbert, 1984, Bixel, 1987): the Grey Unit (50-120 m, Estefanian to Kungurian) with slates, conglomerates, tobaceous slates, coal and pyroclastic deposits, the Transition Unit (50 m maximum) showing grey and red sandstones and lutites with oolitic limestones intercalated, the Lower Red Unit (250 m) composed of cross-bedded red sandstones and andesitic volcanic rocks at the top, and finally the Upper Red Unit (400 m minimum, top eroded) formed by three fining up megasequences of carbonates, red sandstones and lutites with lacustrine carbonates intercalated and alkali basalts at the top. Increasingly older rocks are found towards the western part of the basin, where its depocenter is located. South-vergent angular folds deform the Permian sedimentary succession. Fold axes are N115 °E-trending, almost horizontal and are characterized by a remarkably constant orientation. Folds exhibit a long limb dipping slightly to the north and a short vertical limb, occasionally reversed. In the Anayet basin four main folds, with a wavelength of 400 m, can be distinguished, two anticlines and two synclines, with minor folds associated. Related to the angular folds an axial plane foliation, E-trending and dipping 40 to 60° to the north, is developed in the lutites. The more competent rocks, conglomerates and breccias, only locally show a spaced fracture cleavage. No main thrusts have been detected in Permian rocks. However, minor scale decollements, usually low angle to bedding-parallel, have been identified along low-dipping limbs of the folds. They can be recognized due to the high colour contrast between the red-coloured Permian beds and the concentration of calcite veins in the decollements. The development of the structures above described has to be linked to the Alpine compressional tectonics. This interpretation is supported by the good correlation in geometry and orientation between the structures observed in the Permian basin and in southernmost areas of the South Pyrenean Zone, where the deformation is imprinted in Cretaceous to Tertiary rocks. In this regard, the southern border of the Anayet basin, at least in the western part, can be interpreted as a normal fault reactivated as a high-angle reverse fault during the positive inversion tectonics induced by the Alpine Orogeny. Bixel, F., 1987. Le volcanisme stephano-permien des Pyrenees petrographie, mineralogie, geochimie. Cuadernos de Geología Ibérica 11, 41-55. Gisbert, J., 1984. Las molasas tardihercínicas del Pirineo, in: Geología de España. Libro Jubilar de J. M. Ríos, Comba, J.A. (Ed.), IGME, Madrid, 168-186.

Rodriguez, L.; Cuevas, J.; Tubía, J. M.

2012-04-01

6

The Central European Permian Basins; Rheological and structural controls on basin history and on inter-basin connectivity  

Science.gov (United States)

We analyse the relative importance of the major crustal-scale fault zones and crustal architecture in controlling basin formation, deformation and the structural connections between basins. The North and South Permian Basins of Central Europe are usually defined by the extend of Rotliegend sedimentary and volcanic units and not by a common tectonic origin or development. Instead, the sub-basins that together form the Permian Basins are each controlled by different structural and/or rheological controls that are inherited from Early Paleozoïc and older geodynamic processes, they are even located in different crustal/lithospheric domains. The North Permian basin is located on Baltic crust that was thinned during Late Proterozoïc - Early Paleozoïc times. South of the Thor suture, the South Permian basin and its sub-basins are located on Avalonian crust (Southern North Sea and North German Basins) and on the transition of East European cratonic and Avalonian crust (Polish Through). The size of crustal domains and of the faults that govern basin formation requires a regional-scale to assess their impact on basins and sub-basins. In the case of the Permian Basins this encompasses East Avalonia and surroundings, roughly speaking the area north of the Variscan Rheïc suture, east of the Atlantic and southwest of the Teisseyre-Tornquist line. This approach sheds light on the effects of long lived differences in crustal fabric which are responsible for spatial heterogeneity in stress and strain magnitudes and zonations of fracturing, burial history and temperature history. The focus on understanding the geomechanical control of large crustal-scale fault structures will provide the constraints and geometrical and compositional input for local models of stress and strain. Considering their fundamentally different structural and rheological controls, the Permian (sub)basins have a remarkably common history of subsidence and inversion, suggesting a more or less continuous link between them. Post-Variscan, Late Carboniferous-Early Permian wrench tectonics is the oldest and main identified cause for regional basin formation in Central Europe. This relatively short-lived tectonic regime cannot explain the observed common history of subsidence of the Permian Basins during the 200 My that followed. Our analysis demonstrates that transfer faults that both follow and cross rheological transitions and inherited fault zones continued to be active after the early Permian. We therefore suggests that crustal-scale transfer faults may be the missing link that explains the common subsidence history of basins with a fundamentally different crustal architecture and structural history.

Smit, Jeroen; Van Wees, Jan-Diederik; Cloetingh, Sierd

2014-05-01

7

Feasibility study of heavy oil recovery in the Permian Basin (Texas and New Mexico)  

International Nuclear Information System (INIS)

This report is one of a series of publications assessing the feasibility of increasing domestic heavy oil production. Each report covers select areas of the United States. The Permian Basin of West Texas and Southeastern New Mexico is made up of the Midland, Delaware, Val Verde, and Kerr Basins; the Northwestern, Eastern, and Southern shelves; the Central Basin Platform, and the Sheffield Channel. The present day Permian Basin was one sedimentary basin until uplift and subsidence occurred during Pennsylvanian and early Permian Age to create the configuration of the basins, shelves, and platform of today. The basin has been a major light oil producing area served by an extensive pipeline network connected to refineries designed to process light sweet and limited sour crude oil. Limited resources of heavy oil (10'' to 20'' API gravity) occurs in both carbonate and sandstone reservoirs of Permian and Cretaceous Age. The largest cumulative heavy oil production comes from fluvial sandstones of the Cretaceous Trinity Group. Permian heavy oil is principally paraffinic and thus commands a higher price than asphaltic California heavy oil. Heavy oil in deeper reservoirs has solution gas and low viscosity and thus can be produced by primary and by waterflooding. Because of the nature of the resource, the Permian Basin should not be considered a major heavy oil producing area

8

Inversion tectonics in the Anayet Permian basin (Axial Zone, Central Pyrenees)  

Science.gov (United States)

During Permian times the Pyrenees were characterized by extensional tectonics that opened subsident basins with pull-apart geometries. The Anayet Permian basin crops out in the western Spanish Axial Zone between the Aragon and Tena valleys. It is WNW-trending and it is filled by a continental Permian succession that represents the first post-variscan deposits in the area. Permian deposits rest discordantly over Devonian to Carboniferous limestones, sandstones and slates. In the Anayet basin, Permian deposits have been classically divided in four main detrital groups, mainly composed of sandstones and conglomerates, with three basic volcanic episodes interbedded (Gisbert, 1984, Bixel, 1987). Due to the lithological characteristics of the Permian rocks in this region, there are almost no accurate age constraints for these units. A detailed structural study of the area, including mapping and balanced cross-sections, shows increasingly older rocks to the west of the Anayet basin. Moreover, it can be deduced a mean slope of around 11 % to the west for the basin. These data confirm that the basin depocenter was located to the west and that the Anayet basin was partitioned by N10 °E-trending normal faults. Although the contacts between the Permian and the Devono-Carboniferous rocks are covered by quaternary deposits in most of its extent, a fault contact can also be recognized. The fault contact is a 3 m thick shear zone oriented N120 ° E and dipping 60° to the North. It develops breccias, fault gouges and sigmoidal S-C tectonites indicating a reverse motion. The contact places Permian slates and sandstones over Carboniferous limestones and is almost parallel to the alpine cleavage deforming Permian rocks. The slope of the contact together with the presence of younger rocks in the hangingwall of the reverse fault points out that the original contact was a normal fault reactivated as a high-angle reverse fault during the positive inversion tectonics induced by the Alpine Orogeny. The high dip of the contact produced a buttressing effect during the alpine compression that concentrated the deformation near the fault zone and generated the cleavage of the hangingwall. Moreover, the higher abundance of fractures and calcite veins near the contact in the Carboniferous limestones of the footwall can be interpreted as an incipient stage to the formation of a short-cut-fault related with the buttressing effect. This process can explain the uncommon thickness of the fault zone, if we compare it with other alpine thrusts in this region. The structural features described above support the interpretation of the southern limit of the Anayet Permian basin as a normal fault originated during the Permian rifting and inverted during the compressional tectonics due to the Alpine Orogeny. Bixel, F., 1987. Le volcanisme stephano-permien des pyrenees petrographie, mineralogie, geochimie. Cuadernos de Geología Ibérica 11, 41-55. Gisbert, J., 1984. Las molasas tardihercínicas del Pirineo, in: Geología de España. Libro Jubilar de J. M. Ríos, Comba, J.A. (Ed.). IGME, Madrid, 168-186.

Rodriguez, L.; Cuevas, J.; Tubía, J. M.

2012-04-01

9

Geology and Permian coal resources of the Irwin Terrace, Perth Basin, Western Australia  

Energy Technology Data Exchange (ETDEWEB)

Potentially economic coal seams of the Permian Irwin River Coalfield cover approximately 170 kms of the Irwin Terrace on the east flank of the north Perth Basin. Mapping, drilling and gravity interpretation reveal outcropping coals that plunge to 400 m in a weakly folded half graben that strikes north-northwest. This post-depositional extensional structure contains an interpreted 1700 m of generally southeasterly dipping permian siliciclastic rocks preserved as a consequence of left-lateral shear in transtensional setting. Refined Permian rock stratigraphy is integrated with biostratigraphic palynomorph zones. Sediment ages span Carboniferous to Early Tatarian in the Late Permian. The coals are Aktastinian and correlate with the basal coal beds in the Collie Basin, south Perth Basin, and Karoo Basin of South Africa. A possible lacuna, spanning the Kungurian Nd Ufimian Stages, exists at the unconformity between the Wagina Sandstone and the underlying Carynginia Formation. Vitrinite reflectance indicates the Early Permian coal was buried to depths of 2.7-4.3 km in an interior sag basin between 4.3 and 5.8 km deep. Gravity modelling in the Irwin River Coalfield area shows that depth to basement varies from a maximum of 1700 m in the northern part to under 300 m in the south. Given the pre-existing mapped position of the Darling Fault, it is necessary to invoke a low density body immediately east of the fault and then a higher density body farther to the east in the models of traverses G1, G2, and G3. The low density body immediately east of the Darling Fault can be explained best as the result of shearing associated with the proto Darling Fault.(author). 26 figs, 2 plates, refs.

Le Blanc Smith, G.; Mory, A.J.; Lasky, R.P

1995-09-01

10

Selection of nuclear waste repository sites in the Permian Basin  

International Nuclear Information System (INIS)

Since late 1977, the US Department of Energy (DOE) has been conducting environmental and geologic studies in order to identify potential sites for the disposal of high-level nuclear waste from commercial reactors. The DOE proposes to bury the waste deep underground in conventionally-mined repositories located in stable geologic deposits such as salt formations. Geologic, environmental, and socioeconomic studies led to the identification of two potentially suitable repository sites in the Permian bedded salt formation of west Texas. Detailed multi-disciplinary studies will be required to confirm the ability of these sites to isolate the high-level nuclear waste from the human environment for a period of 10,000 years in an environmentally sound manner. This report provides a description and discussion of the multi-step site selection process that identified the two 9 square mile (23 square kilometer) sites from the 80,000 square mile (26,000 square kilometer) Permian salt formation

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Permian and Triassic microfloral assemblages from the Blue Nile Basin, central Ethiopia  

Science.gov (United States)

Palynological investigation was carried out on surface samples from up to 400 m thick continental siliciclastic sediments, here referred to as “Fincha Sandstone”, in the Blue Nile Basin, central Ethiopia. One hundred sixty species were identified from 15 productive samples collected along a continuous road-cut exposure. Six informal palynological assemblage zones have been identified. These assemblage zones, in ascending order, are: “Central Ethiopian Permian Assemblage Zone - CEPAZ I”, earliest Permian (Asselian-Sakmarian); “CEPAZ II”, late Early Permian (Artinskian-Kungurian); CEPAZ III - Late Permian (Kazanian-Tatarian); “CETAZ IV”, Lower Triassic (Olenekian Induan); “CETAZ V”, Middle Triassic (Anisian Ladinian); “CETAZ VI”, Late Triassic (Carnian Norian). Tentative age ranges proposed herein are compared with faunally calibrated palynological zones in Gondwana. The overall composition and vertical distribution of miospores throughout the studied section reveals a wide variation both qualitatively and quantitatively. The high frequency of monosaccate pollen in CEPAZ I may reflect a Glossopterid-dominated upland flora in the earliest Permian. The succeeding zone is dominated by straite/taeniate disaccate pollen and polyplicates, suggesting a notable increase in diversity of glossopterids. The decline in the diversity of taeniate disaccate pollen and the concomitant rise in abundance of non-taeniate disaccates in CEPAZ III may suggest the decline in Glossopteris diversity, though no additional evidence is available to equate this change with End-Permian extinction. More diverse and dominant non-taeniate, disaccate, seed fern pollen assignable to FalcisporitesAlisporites in CETAZ IV may represent an earliest Triassic recovery flora. The introduction of new disaccate forms with thick, rigid sacci, such as Staurosaccites and Cuneatisporites, in CETAZ V and VI may indicate the emergence of new gymnospermous plants that might have favourably adapted to coastal plain wetland environments with the return of humid conditions in the Middle to early Late Triassic. The present data constitute the first paleontologically substantiated record for the existence of Permian strata in the Blue Nile Basin. The new results allow for the first time a reliable biostratigraphic subdivision of the central Ethiopia Karoo and its correlation with coeval strata of adjacent regions in Gondwana. From a phytogeographic point of view, the overall microfloral evidence is in support of the position of central Ethiopia occupying the northern part of the southern Gondwana palynofloral province. In view of palaeoecological and paleoclimatic conditions, the microfloral change from the base to the top of the studied section may indicate a response to shifting climatic belts from warm- and cool-temparate climate in the earliest Permian to progressively drier seasonal conditions at successively higher palaeolatitudes during the Late Permian to Middle Triassic.

Dawit, Enkurie L.

2014-11-01

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The flora of Early Permian coal measures from the Parana Basin in Brazil: A review  

International Nuclear Information System (INIS)

This paper presents an updated overview integrating both previous and newly published data on the most important floras found associated with Early Permian coal seams in the Parana Basin, Brazil. These floras occur within the Rio Bonito Formation and correspond to the Gondwana ''Glossopteris Flora.'' For this review, five floras are selected, in ascending stratigraphic order: the ''Sao Joao do Triunfo,'' ''Figueira,'' ''Quiteria,'' ''Morro do Papaleo'' and ''Irapua Bed'' floras. They are the best-known floras of the basin in terms of taxonomic composition, paleoecology and environments of deposition. An early-mid Sakmarian to earliest Artinskian age is indicated for the Rio Bonito Formation based on absolute radiometric and relative biostratigraphic ages. Integration of available information about the selected floras allows evaluation of taphonomic and paleoecological factors to provide a more comprehensive understanding of the Early Permian floral record in the Parana Basin. The variation observed in both the taxonomic composition of individual floras and in the frequency of occurrence of different plant groups is due to the broad range of environmental/edaphic conditions that prevailed in the many different depositional settings represented in the Rio Bonito Formation. A more precise age determination obtained for the plant-bearing deposits permits the establishment of a more confident correlation between the Early Permian floral succession in the Parana Basin and oloral succession in the Parana Basin and other Early Permian floral successions in other basins. The Sakmarian global warming favored the appearance of pecopterid and sphenopterid ferns amongst the spore-producing plants, and the glossopterids amongst the pollen-producing plants. (author)

13

Assessment of potential unconventional Carboniferous-Permian gas resources of the Liaohe Basin eastern uplift, Liaoning Province, China, 2011  

Science.gov (United States)

The U.S. Geological Survey estimated a mean of 448 billion cubic feet of potential technically recoverable unconventional natural gas in Carboniferous and Permian coal-bearing strata in the eastern uplift of the Liaohe Basin, Liaoning Province, China.

Pollastro, Richard M.; Potter, Christopher J.; Schenk, Christopher J.; Charpentier, Ronald R.; Cook, Troy A.; Klett, Timothy R.; Kirschbaum, Mark A.

2012-01-01

14

78 FR 16569 - Iowa Pacific Holdings, LLC, Permian Basin Railways, and San Luis & Rio Grande Railroad-Corporate...  

Science.gov (United States)

...and Monterey Bay Railway Company; and (7) West Texas & Lubbock Railway. \\2\\ See Iowa Pac. Holdings, LLC & Permian Basin Rys.--Control Exemption--Cape Rail, Inc. & Mass. Coastal R.R., FD 35684 (STB served October 26,...

2013-03-15

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Development of the Permian-Triassic sequence in the basin Fringe area, southern Netherlands  

Energy Technology Data Exchange (ETDEWEB)

Geological studies in the fringe area of the southern Permian basin led to new insights in the distribution and development of the Permian-Triassic sequence. During the Permian, the fringe area formed a platform, attached to the London-Brabant Massif, while during the Triassic it is characterized by strongly subsiding half grabens. In the southern Netherlands, Rotliegende sandstones and conglomerates have a much wider distribution than previously recognized. The Rotliegende deposits are capped by claystones and carbonates of the Upper Permian Zechstein. In the offshore, an important feeder system of clastics from the London-Brabant Massif was active during deposition of the Rotliegende and the Zechstein. In course of time, the location of major sandstone deposition shifted westward. Deposition of the Triassic Buntsandstein was controlled by the development of a large feeder system, which transported clastics from the Vosges northward, through the Roer Valley Graben and West netherlands Basin into the Off Holland Low. This system was responsible for the deposition of the economically important sheet sandstones of the Volpriehausen, Detfurth, Hardegsen, and Solling formations. A regional unconformity occurs below the Solling Formation. The sandstones are capped by claystones, evaporites, and sandstones of the Rot Formation. During deposition of the Muschelkalk, the differences in subsidence decreased and shallow marine sediments are interbedded with evaporites. Several unconformities occur within the Keuper. In the previous half grabens in the southern Netherlands, the Keuper is incomplete, which may be indicative for a possible reversal of the tectonic movements during this period.

Geluk, M.; Van Doorn, D.; Plomp, A.; Duin, E. (Geological Survey of the Netherlands, Haarlem (Netherlands))

1993-09-01

16

The flora of Early Permian coal measures from the Parana Basin in Brazil: A review  

Energy Technology Data Exchange (ETDEWEB)

This paper presents an updated overview integrating both previous and newly published data on the most important floras found associated with Early Permian coal seams in the Parana Basin, Brazil. These floras occur within the Rio Bonito Formation and correspond to the Gondwana ''Glossopteris Flora.'' For this review, five floras are selected, in ascending stratigraphic order: the ''Sao Joao do Triunfo,'' ''Figueira,'' ''Quiteria,'' ''Morro do Papaleo'' and ''Irapua Bed'' floras. They are the best-known floras of the basin in terms of taxonomic composition, paleoecology and environments of deposition. An early-mid Sakmarian to earliest Artinskian age is indicated for the Rio Bonito Formation based on absolute radiometric and relative biostratigraphic ages. Integration of available information about the selected floras allows evaluation of taphonomic and paleoecological factors to provide a more comprehensive understanding of the Early Permian floral record in the Parana Basin. The variation observed in both the taxonomic composition of individual floras and in the frequency of occurrence of different plant groups is due to the broad range of environmental/edaphic conditions that prevailed in the many different depositional settings represented in the Rio Bonito Formation. A more precise age determination obtained for the plant-bearing deposits permits the establishment of a more confident correlation between the Early Permian floral succession in the Parana Basin and other Early Permian floral successions in other basins. The Sakmarian global warming favored the appearance of pecopterid and sphenopterid ferns amongst the spore-producing plants, and the glossopterids amongst the pollen-producing plants. (author)

Iannuzzi, Roberto [Centro de Investigacoes do Gondwana, Instituto de Geociencias, Universidade Federal do Rio Grande do Sul, Av. Bento Goncalves, 9500, Porto Alegre, RS, 91.509-900 (Brazil)

2010-08-01

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Carbon Capture and Storage in the Permian Basin, a Regional Technology Transfer and Training Program  

Energy Technology Data Exchange (ETDEWEB)

The Permian Basin Carbon Capture, Utilization and Storage (CCUS) Training Center was one of seven regional centers formed in 2009 under the American Recovery and Reinvestment Act of 2009 and managed by the Department of Energy. Based in the Permian Basin, it is focused on the utilization of CO2 Enhanced Oil Recovery (EOR) projects for the long term storage of CO2 while producing a domestic oil and revenue stream. It delivers training to students, oil and gas professionals, regulators, environmental and academia through a robust web site, newsletter, tech alerts, webinars, self-paced online courses, one day workshops, and two day high level forums. While course material prominently features all aspects of the capture, transportation and EOR utilization of CO2, the audience focus is represented by its high level forums where selected graduate students with an interest in CCUS interact with Industry experts and in-house workshops for the regulatory community.

Rychel, Dwight

2013-09-30

18

Volcanic relicts in the permian-filled deposits of the Lodeve basin: metallogenic occurrences  

International Nuclear Information System (INIS)

Petrographical and mineralogical studies of the various lithological Permian facies of the uraniferous Lodeve basin show evidence of volcanic activity, as witnesses by the existence of pumices, shards, perlites particularly in sedimentary formations of the Upper Thuringian where volcanism has not been described so far. Major and trace chemistry of the most inert elements contributing towards alteration and diagenesis confirm the volcanic contribution to the sedimentation

19

Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa  

OpenAIRE

Dicynodonts are an extinct group of herbivorous non-mammalian therapsids (‘mammal-like’ reptiles) that are widely known from terrestrial Permo-Triassic strata throughout Pangaea. Dicynodont fossil remains are common within the Late Permian Beaufort Group of the Karoo Basin in South Africa. A large, partially articulated dicynodont skeleton recovered from the TropidostomaAssemblage Zone is taphonomically important in having an unusual disarticulation pattern, bone surface punctures and a b...

Nicholas Fordyce; Mr Roger Smith; Anusuya Chinsamy

2012-01-01

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Charcoal remains from a tonstein layer in the Faxinal Coalfield, Lower Permian, southern Paraná Basin, Brazil  

OpenAIRE

Fossil charcoal has been discovered in the Faxinal Coalfield, Early Permian, Rio Bonito Formation, in the southernmost portion of the Paraná Basin, Brazil. Three types of pycnoxylic gymnosperm woods recovered from a single tonstein layer are described and confirm the occurrence of paleowildfire in this area. A decrease of the charcoal concentration from the base to the top within the tonstein layer indicates that the amount of fuel declined during the deposition probably due to the consumpti...

André Jasper; Dieter Uhl; Margot Guerra-Sommer; Abu Hamad, Abdalla M. B.; Machado, Neli T. G.

2011-01-01

21

Late Permian-early Middle Triassic back-arc basin development in West Qinling, China  

Science.gov (United States)

The Late Permian-early Middle Triassic strata of the northern West Qinling area, northeastern Tibetan Plateau, are composed of sediment gravity flow deposits. Detailed sedimentary facies analysis indicates these strata were deposited in three successive deep-marine environments. The Late Permian-early Early Triassic strata of the Maomaolong Formation and the lowest part of the Longwuhe Formation define a NW-SE trending proximal slope environment. Facies of the Early Triassic strata composing the middle and upper Longwuhe Formation are consistent with deposition in a base-of-slope apron environment, whereas facies of the Middle Triassic Anisian age Gulangdi Formation are more closely associated with a base-of-slope fan depositional environment. The lithofacies and the spatial-temporal changes in paleocurrent data from these strata suggest the opening of a continental margin back-arc basin system during Late Permian to early Middle Triassic time in the northern West Qinling. U-Pb zircon ages for geochemically varied igneous rocks with diabasic through granitic compositions intruded into these deep-marine strata range from 250 to 234 Ma. These observations are consistent with extensional back-arc basin development and rifting between the Permian-Triassic Eastern Kunlun arc and North China block during the continent-continent collision and underthrusting of the South China block northward beneath the Qinling terrane of the North China block. Deep-marine sedimentation ended in the northern West Qinling by the Middle Triassic Ladinian age, but started in the southern West Qinling and Songpan-Ganzi to the south. We attribute these observations to southward directed rollback of Paleo-Tethys oceanic lithosphere, continued attenuation of the West Qinling on the upper plate, local post-rift isostatic compensation in the northern West Qinling area, and continued opening of a back-arc basin in the southern West Qinling and Songpan-Ganzi. Rollback and back-arc basin development during Late Permian to early Middle Triassic time in the West Qinling area explains: the truncated map pattern of the Eastern Kunlun arc, the age difference of deep-marine sediment gravity flow deposits between the Late Permian-early Middle Triassic northern West Qinling and the late Middle Triassic-Late Triassic southern West Qinling and Songpan-Ganzi, and the discontinuous trace of ophiolitic rocks associated with the Anyemaqen-Kunlun suture.

Li, Lin; Meng, Qingren; Pullen, Alex; Garzione, Carmala N.; Wu, Guoli; Wang, Yanling; Ma, Shouxian; Duan, Liang

2014-06-01

22

Schematic designs for penetration seals for a repository in the Permian Basin  

International Nuclear Information System (INIS)

The isolation of radioactive wastes in geologic repositories requires that human-made penetrations such as shafts, tunnels, or boreholes are adequately sealed. This report describes schematic seal designs for a repository in bedded salt referenced to the stratigraphy of the Permian Basin. The designs are presented for extensive peer review and will be updated as conceptual designs if the Permian Basin is selected as a candidate repository site. The principal material used in the seal system in the repository-level rooms and tunnels is crushed salt obtained from excavating the repository. It is anticipated that crushed salt will consolidate in response to closure of the repository rooms, to the degree that mechanical and hydrologic properties will eventually match those of undisturbed, intact salt. For Permian Basin Unit 4 salt, analyses indicate that this process will require approximately 700 years for a seal located at the base of one of the repository shafts (where there is little increase in temperature due to waste emplacement) and approximately 200 years for a seal located in a main passageway within the repository. These analyses are based on uncertain laboratory data regarding intact salt creep rates and crushed salt consolidation characteristics, and must be regarded as preliminary. Bulkheads composed of concrete, as well as bentonite-rich earth fill, are also included in the seal system as components which will have low permeability during the period requirelow permeability during the period required for salt consolidation

23

Permian continental basins in the Southern Alps (Italy) and peri-mediterranean correlations  

Science.gov (United States)

The Late Carboniferous to Permian continental successions of the Southern Alps can be subdivided into two main tectono-sedimentary Cycles, separated by a marked unconformity sealing a Middle Permian time gap, generally estimated at over 10 Ma. The lower cycle (1), between the Variscan crystalline basement and the Early Permian, is mainly characterised by fluvio-lacustrine and volcanic deposits of calc-alkaline acidic-to-intermediate composition, which range up to a maximum thickness of more than 2,000 m. The upper cycle (2), which is devoid of volcanics, is mostly dominated through the Mid?-Late Permian by alluvial sedimentation which covered the previous basins and the surrounding highs, giving rise to the subaerial Verrucano Lombardo-Val Gardena (Gröden) red-beds, up to about 800 m thick. The palaeontological record from the terrigenous deposits of both the above cycles consists mainly of macro- and microfloras and tetrapod footprints. The age of the continental deposits is widely discussed because of the poor chronological significance of a large number of fossils which do not allow reliable datings; however, some sections are also controlled by radiometric calibrations. The comparison with some selected continental successions in southern Europe allows to determine their evolution and set up correlations. A marked stratigraphic gap shows everywhere between the above-mentioned Cycles 1 and 2. As in the Southern Alps, the gap reaches the greatest extent during the Mid-Permian, near the Illawarra Reversal geomagnetic event (265 Ma). In western Europe, however, such as in Provence and Sardinia, the discussed gap persists upwardly to Late Permian and Early Triassic or slightly younger times, i.e. to the onset of the "Alpine sedimentary Cycle", even though in northeastern Spain (Iberian Ranges, Balearic Islands) this gap results clearly interrupted by late Guadalupian-Lopingian deposits. The above two major tectonosedimentary cycles reflect, in our view, two main geodynamic events that affected the southern Europe after the Variscan orogenesis: the Late Carboniferous-Early Permian transformation of the Gondwana-Eurasia collisional margin into a diffuse dextral transform margin and the Middle-Late Permian opening of the Neotethys Ocean, with the onset of a generalised extensional tectonic regime and the progressive westward marine ingression.

Cassinis, Giuseppe; Perotti, Cesare R.; Ronchi, Ausonio

2012-01-01

24

Phreatomagmatic Pipes of the Tunguska basin (Siberia): Improvement of End-Permian Mass Extinction Model  

Science.gov (United States)

Formation of the Siberian Traps Large Igneous Province is regarded as key phenomena responsible for the end-Permian mass extinction. Extinct event was accelerating due to release of enormous amount of gases throughout numerous basalt pipes, originated from contact aureoles of dolerite sills intruded into Tunguska Basin. Tunguska sedimentary basin consists of Precambrian and Paleozoic evaporites, carbonates and terrigenous rocks including Late Paleozoic coal-bearing strata. Precambrian and early Paleozoic oil source rocks contain numerous high potential oil and gas fields. Paleozoic evaporites contain rock and potassium salts deposits of commercial grade. Tunguska Basin evaporites are considered as a regional seal for the mineralizing brines. Permian-Triassic volcaniclastic rocks overlie this sequence and intrusive rocks have the numerous evidences of magma-sediment interaction result in basalt pipes formation. Compilation of available Russian literature gives us a chance to make a conclusion that hundreds of basalt pipes occur in the Tunguska Basin. The basalt pipes cross over all known dolerite intrusions and are filled with breccias of magmatic, volcaniclastic and sedimentary rocks altered to varying extents. Pipes from the Tunguska Basin south have a phreatomagmatic origin that is supported by ubiquitous occurrence of altered sedimentary clasts and volcaniclastic lapilli, corroded by brine during initial stages of magma-evaporite (brine) interaction. Corroded lapilli rimmed by diopside, chlorine-bearing hornblende, apatite and magnetite. Our recent study of magnetite-rich coarse lapilli tuffs revealed the garnet lapilli rimmed with magnetite cemented by altered clay groundmass enriched by native metals (Cu, Sn, Zn). This result corroborates our hypothesis about magnetite formation during initial stage of magma-sediment-brine interaction. We suggest that these observations could shed light on end-Permian aerosol flux originated from basalt pipes and could provide new information for improvement of our model.

Polozov, Alexander; Svensen, Henrik; Planke, Sverre; Jerram, Dougal

2014-05-01

25

No Abrupt Changes in redox conditions associated with the end-Permian marine ecosystem collapse in the east Greenland basin.  

DEFF Research Database (Denmark)

Multiple observations have revealed that environmental disturbances may have been linked to the end-Permian mass extinction and delayed biotic recovery. Biogeochemical constraints on the temporal and spatial changes of oceanic redox chemistry during the Permian–Triassic interval are essential to evaluate global significance of previous hypotheses and to improve our understanding of extinction and recovery processes. To investigate redox ocean chemistry change associated with the end-Permian extinction and subsequent delayed biotic recovery, we examine framboidal pyrites as well as sulfur isotopic compositions of pyrites from the East Greenland Basin. The size distributions of framboidal pyrites in sediments from a continuous section across the Permian–Triassic boundary reveal that sulfidic conditions in water columns were established about 0.7 m above the extinction event in the East Greenland Basin. Our detailed examination of framboidal pyrites challenges a leading hypothesis that euxinia in the photic zonecaused the end-Permian ecosystem collapse. We identify several positive and negative S-isotopic shifts before and after the extinction event and demonstrate that a positive S-isotopic shift is not indicative of an abrupt change of redox chemistry in water columns, in contrast to previous claims. The integration of isotope and framboidal pyrite data provides a nearly continuous record of ocean chemistry evolution and new insights into the end-Permian extinction and delayed biotic recovery in the East Greenland Basin.

Nielsen, Jesper K.; Shen, Y

2010-01-01

26

Regional summary and recommended study areas for the Texas Panhandle portion of the Permian Basin  

International Nuclear Information System (INIS)

This report summarizes the regional geologic and environmental characterizations that have been completed for the Permian region of study, and describes the procedure used to identify study areas for the next phase of investigation. The factors evaluated in the Permian region fall into three broad areas: health and safety, environmental and socioeconomic, and engineering and economic considerations. Health and safety considerations included salt depth and thickness, faults, seismic activity, groundwater, salt dissolution, energy and mineral resources, presence of boreholes, and interactive land uses. Salt depth and thickness was the key health and safety factor, and when mapped, provded to be a discriminator. The evaluation of environmental and socioeconomic conditions focused primarily on the presence of urban areas and on designated land uses such as parks, wildlife areas, and historic sites. Engineering and economic considerations centered primarily on salt depth, which was already evaluated in the health and safety area. The Palo Duro and Dalhart basins are recommended for future studies on the basis of geology. In these two basins, salt depth and thickness appear promising, and there is less likelihood of past or future oil and gas exploratory holes. Environmental and socioeconomic factors did not preclude any of the basins from further study. 66 references, 16 figures, 2 tables

27

A sulfur and strontium isotopic investigation of Lower Permian anhydrite, Palo Duro Basin, Texas, U.S.A  

International Nuclear Information System (INIS)

Lower Permian Wolfcamp and Wichita carbonates and anhydrites, Palo Duro Basin, Texas Panhandle, record a change from a normal marine evaporite depositional environment. Isotopic compositions of S and Sr in anhydrite were determined to investigate the age of Wolfcamp and Wichita strata and the paragenesis of eight anhydrite forms. Bedded nodular mosaic (Wichita) and replacive nodular (Wolfcamp) anhydrites have S and Sr isotopic compositions that record precipitation from Early Permian (Wolfcampian to Leonardian) seawater. Silicified nodular, coarsely crystalline nodular, fossil-filling, and vein-filling anhydrites have enriched S isotopic compositions relative to Permian seawater, whereas euhedral and anhedral replacive anhydrites have depleted S. The Sr isotopic composition of most anhydrite forms indicates an Early Permain marine origin, however, Sr in anhydrite veins is slightly radiogenic compared to Permian seawater. The Sr isotopic composition of bedded nodular mosaic anhydrite indicates a Leonardian seawater source of material. (author)

28

Generation and expulsion of oils from Permian coals of the Sydney Basin, Australia  

Energy Technology Data Exchange (ETDEWEB)

Organic geochemical and petrological assessment of coals/coaly shales and fine grained sediments, coupled with organic geochemical analyses of oil samples, all from Permo-Triassic sections of the Southern Sydney Basin (Australia), have enabled identification of the source for the widely distributed oil shows and oil seeps in this region. The Permian coals have higher hydrogen indices, higher liptinite contents, and much higher total organic matter extract yields than the fine grained sediments. A variety of source specific parameters obtained from n-alkanes, regular isoprenoids, terpanes, steranes and diasteranes indicate that the oil shows and seeps were generated and expelled predominantly from higher plant derived organic matter deposited in oxic environments. The source and maturity related biomarkers and aromatic hydrocarbon distributions of the oils are similar to those of the coals. The oil-coal relationship also is demonstrated by similarities in the carbon isotopic composition of the total oils, coal extracts, and their individual n-alkanes. Extracts from the Permo-Triassic fine grained sediments, on the other hand, have organic geochemical signatures indicative of mixed terrestrial and prokaryotic organic matter deposited in suboxic environments, which are significantly different from both the oils and coal extracts. The molecular signatures indicating the presence of prokaryotic organic matter in some of the coal extracts and oils may be due to thin sections of possibly calcareous lithologies interbedded within the coal measures. The genetic relationship between the oils and coals provides new evidence for the generation and expulsion of oils from the Permian coals and raises the possibility for commercial oil accumulations in the Permian and Early Triassic sandstones, potentially in the deeper offshore part of the Sydney Basin.

Ahmed, M.; Volk, H.; George, S.C.; Faiz, M.; Stalker, L. [CSIRO Petrology, Sydney, NSW (Australia)

2009-07-15

29

Cyclic sedimentation in the shallow marine Upper Permian Kennedy Group, Carnarvon Basin, Western Australia  

Science.gov (United States)

The Upper Permian Kennedy Group of the Carnarvon Basin, Western Australia, was deposited while the Merlinleigh Sub-basin was undergoing thermal subsidence, and the global climate was warming from the Carboniferous-Permian glaciation to the Mesozoic Greenhouse conditions. The Kennedy Group comprises siliciclastic sedimentary rocks, dominated by sandstones in the lower part, with coarsening-up cycles from mudstones to very coarse sandstones and granule conglomerates in the upper part. Cycles were observed and logged in the field, and although many types of cycles were found, three main motifs describe most of the cycles. Cycle motifs are defined based on the dominance of the various facies: Mooka motif cycles are dominated by fine-grained and bioturbated facies (interpreted as deposition during relative sea-level highstand) with only thin laminated or cross-bedded sandstones (interpreted as deposited during relative sea-level fall); Binthalya motif cycles are dominated by laminated and cross-bedded sandstones; and Coolkilya motif cycles consist of alternating laminated and bioturbated beds. A hierarchy of cycles was observed in the field, and this correlated well with spectral analysis of logged parameters. Spectral analysis of section log data and data sets corrected for the effects of compaction and sedimentation rates detected regular cyclicity. Geochronology of the Kennedy Group is not well enough constrained to allow the cycle periods in time to be calculated, but ratios of the different scale cycle thicknesses correlate well with ratios of the Milankovitch orbital cycles that have been calculated for the Permian. The presence of regular cyclicity and even bed thicknesses across large distances are not consistent with tectonic or autocyclic models of cycle formation. The cycles are more likely to have been caused by fluctuating eustatic sea levels, perhaps enhanced by changing amounts or seasonality of precipitation. Both sea levels and climatic fluctuations would ultimately be controlled by the Milankovitch orbital cycles.

Lever, Helen

2004-11-01

30

Leaiid conchostracans from the uppermost Permian strata of the Paraná Basin, Brazil: Chronostratigraphic and paleobiogeographic implications  

Science.gov (United States)

Conchostracan fossils are abundant and relatively diversified in the Rio do Rasto Formation (Passa Dois Group, Paraná Basin, southern Brazil), but leaiids (' Leaia pruvosti' [Reed, F.R.C., 1929. Novos Phyllopodos Fósseis do Brasil. Boletim do Serviço Geológico e Mineralógico do Brasil 34, 2-16]) were previously found at only one locality of the formation in the northern Santa Catarina State. New specimens of the Family Leaiidae, collected from two outcrops in central Paraná State near the top of the formation, stimulated a revision of related taxa. Both the new and the previously known leaiids are herein assigned to Hemicycloleaia mitchelli [Etheridge Jr., R., 1892. On Leaia mitchelli Etheridge. Proceedings of the Linnean Society of New South Wales 7, 307-310] based on the presence of three carinae and subovate shape. This species was originally recorded in the upper Tatarian (Wuchiapingian, Late Permian) of Sydney Basin, eastern Australia and therefore corroborates the interpretation that the leaiid bearing strata of the Rio do Rasto Formation cannot be younger than Permian. H. mitchelli possibly was one of the most widespread, eurytopic and conservative Late Paleozoic conchostracans of Gondwana (although records from Africa, India and Antarctica must still be confirmed) and it was also found in the Tatarian of Russia. The sudden disappearance of leaiids after their apparent success is consistent with the hypothesis about the biotic crisis around the Permo-Triassic boundary.

Ferreira-Oliveira, Luis Gustavo; Rohn, Rosemarie

2010-03-01

31

Assessment of undiscovered copper resources associated with the Permian Kupferschiefer, Southern Permian Basin, Europe: Chapter U in Global mineral resource assessment  

Science.gov (United States)

This study synthesizes available information and estimates the location and quantity of undiscovered copper associated with a late Permian bituminous shale, the Kupferschiefer, of the Southern Permian Basin in Europe. The purpose of this study is to (1) delineate permissive areas (tracts) where undiscovered reduced-facies sediment-hosted stratabound copper deposits could occur within 2.5 kilometers of the surface, (2) provide a database of known reduced-facies-type sediment-hosted stratabound copper deposits and significant prospects, and (3) provide probabilistic estimates of amounts of undiscovered copper that could be present within each tract. This assessment is a contribution to a global assessment conducted by the U.S. Geological Survey (USGS).

Zientek, Michael L.; Oszczepalski, S?awomir; Parks, Heather L.; Bliss, James D.; Borg, Gregor; Box, Stephen E.; Denning, Paul D.; Hayes, Timothy S.; Spieth, Volker; Taylor, Cliff D.

2015-01-01

32

Compilation of data for thermomechanical analyses of four potential salt repositories. [Paradox Basin, Permian Basin, Richton Dome, Vacherie Dome  

Energy Technology Data Exchange (ETDEWEB)

This report includes a collection and summarization of the data which are necessary to perform thermomechanical analyses of four potential salt repository sites: Paradox Basin, Utah; Permian Basin, Texas; Richton Dome, Mississippi; and Vacherie Dome, Louisiana. Thermal, mechanical, and hydrogeological material properties are presented so that the numerical analyses can be subdivided into three geometric regions: canister, disposal room, and repository site. Data are presented for the salt formations, the surrounding geological units, and for human-made materials placed in the repository such as the nuclear waste and its protective steel liner. Wherever possible, site-specific data are used which have been determined from laboratory testing of drill core or from interpretation of geophysical logs. Although much effort has been made to obtain the most appropriate data, there are deficiencies because some of the required site-specific data are either not available or are inconsistent with anticipated values.

Tammemagi, H.Y.; Loken, M.C.; Osnes, J.D.; Wagner, R.A.

1986-01-01

33

Climatic and biotic changes around the Carboniferous/Permian boundary recorded in the continental basins of the Czech Republic.  

Czech Academy of Sciences Publication Activity Database

Ro?. 119, ?. 1 (2013), s. 114-151. ISSN 0166-5162 Institutional research plan: CEZ:AV0Z30130516 Institutional support: RVO:67985831 Keywords : biotic change * Bohemian Massif * Carboniferous-Permian transition * continental basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.313, year: 2013

Opluštil, S.; Šim?nek, Z.; Zajíc, Jaroslav; Mencl, V.

2013-01-01

34

77 FR 57188 - Iowa Pacific Holdings, LLC and Permian Basin Railways-Continuance in Control Exemption-Rusk...  

Science.gov (United States)

...Cruz and Monterey Bay Railway Company, upon its becoming a Class III rail carrier. Iowa Pac. Holdings, LLC and Permian Basin Rys.--Continuance in Control Exemption--Santa Cruz and Monterey Bay Ry., FD 35632 (STB served Aug. 17, 2012). IPH...

2012-09-17

35

Evolution of groundwater from Permian and Triassic aquifers in the Thuringian basin, Germany  

Science.gov (United States)

The hydrochemical properties of shallow and deep groundwater with special emphasis on stable isotopes (2H, 18O, 34SSO4, 18OSO4) as well as rare earth elements (REE) are investigated to study the evolution of groundwater in the edge areas of the Thuringian basin (central Germany). The Thuringian basin is a syncline structure with an extension of 160 km in northwest-southeast and 100 km in northeast-southwest direction. It consists of sandstones, limestones, clays, gypsum and salts, that were deposited from the Late Permian until the Early Jurassic (approximately 250 to 180 million years ago). At the edge areas of the basin, sediments of Zechstein (Permian) and Bunter Sandstone (Early Triassic) are cropping out over a wide area being the catchment areas for ground water recharge of the main aquifers in Bunter Sandstone and Zechstein formations. In addition to the infiltration of atmospheric water, highly mineralized ascending groundwater occurs at fault systems leading to interactions between the aquifers. The isotope data of dissolved sulfates (34SSO4) indicate a terrestrial origin of sulfates in Early Bunter Sandstone as well as marine conditions for sulfate formation in Late Bunter Sandstone and Late Zechstein. Thus, sulfate isotopes can be used to identify the origin of water and to estimate the proportions of sulfates of different sources in mixing water. The isotopic composition of water in Bunter Sandstone aquifers in the eastern part of the basin indicate an increasing influence of sulfates from Late Bunter Sandstone in aquifers of Middle Bunter Sandstone along the groundwater flow towards the center of the basin. On the other hand there is no indication for mixing with Zechstein associated water in these aquifers. In contrast, in the northern part of the Thuringian basin and southward of the basin (south of the Thuringian forest) an interaction of Zechstein and Bunter Sandstone aquifers bound on fault systems becomes evident. The fractionations of rare earth elements in groundwater were determined after an enrichment procedure based on the method of Shabani (1992). Positive and negative Ce anomalies on PAAS (Post Achaean Australian shale) normalized REE fractionation pattern give hints on different redox conditions during groundwater evolution. Positive Ce anomalies were identified only on samples originated at Zechstein aquifers, whereas groundwaters in Bunter Sandstone aquifers with high redox potential show negative Ce anomalies, generally. References: Shabani, M.B., T. Akagi, and A. Masuda (1992): Preconcentration of trace rare earth elements in seawater by complexation with (2-ethylhexyl) hydrogen phosphate and 2-ethylhexyl dihydrogen phosphate adsorbed on a C18 cardridge and determination by inductively coupled plasma mass spectrometry: Anal. Chem. 64, 737-743.

Lonschinski, Martin; Merten, Dirk; Büchel, Georg

2014-05-01

36

Upper Permian magnetic stratigraphy of the lower Beaufort Group, Karoo Basin  

Science.gov (United States)

We carried out a magnetostratigraphic and geochronological study of late Permian sediments in the Karoo Basin of the Western Cape Province, South Africa. A continuous, ~700 m thick section of deltaic sediments of the upper Waterford Formation (uppermost Ecca Group) and the fluvial sediments of the Abrahamskraal Formation (lowermost Beaufort Group) were sampled at the meter scale. U-Pb dating of zircons from interbedded volcanic ash beds by ion microprobe (SHRIMP) provided absolute age constraints on the age of the sedimentary rocks. Paleomagnetic analysis reveals a partial overprint of the Natural Remanent Magnetization (NRM) that is tentatively ascribed to the emplacement of the Karoo Large Igneous Province in the Western Cape region during the middle Jurassic. A stable component of the NRM was found at temperatures higher than 450 °C and was interpreted as a Characteristic Remanent Magnetization (ChRM) acquired during deposition, supported by a positive reversals test for this dual polarity ChRM. The virtual geomagnetic pole position for the Waterford and Abrahamskraal Formations computed from the average ChRM direction is in general agreement with the late Permian directions for stable Gondwana. A significantly different average inclination, and thus paleomagnetic pole position, is obtained by correcting the inclination shallowing error by the Elongation-Inclination method (Tauxe and Kent, 2004). The presence of both normal and reversed polarity zones indicate deposition after the end of the Kiaman Superchron, moreover the polarity sequence is in good agreement with the Illawarra sequence of Steiner (2006). Our results indicate a Capitanian (late Guadalupian) age for the Abrahamskraal Fm., in agreement with the Late Permian age, based on presence of Glossopteris flora and Dicynodont fauna, traditionally assigned to the fluvial-lacustrine sediments of the Beaufort Group. However, the U-Pb zircon ages of ca. 264-268 Ma suggest an age of 269 Ma for the top of the Kiaman superchron.

Lanci, L.; Tohver, E.; Wilson, A.; Flint, S.

2013-08-01

37

Investigation of deep permeable strata in the permian basin for future geothermal energy reserves  

Energy Technology Data Exchange (ETDEWEB)

This project will investigate a previously unidentified geothermal energy resource, opening broad new frontiers to geothermal development. Data collected by industry during oil and gas development demonstrate deep permeable strata with temperatures {ge} 150 C, within the optimum window for binary power plant operation. The project will delineate Deep Permeable Strata Geothermal Energy (DPSGE) assets in the Permian Basin of western Texas and southeastern New Mexico. Presently, geothermal electrical power generation is limited to proximity to shallow, high-temperature igneous heat sources. This geographically restricts geothermal development. Delineation of a new, less geographically constrained geothermal energy source will stimulate geothermal development, increasing available clean, renewable world energy reserves. This proposal will stimulate geothermal reservoir exploration by identifying untapped and unrealized reservoirs of geothermal energy. DPSGE is present in many regions of the United States not presently considered as geothermally prospective. Development of this new energy source will promote geothermal use throughout the nation.

Erdlac, Richard J., Jr.; Swift, Douglas B.

1999-09-23

38

Geology and metallogeny of the uranium deposits in the Lodeve Permian basin (southern Massif Central, France)  

International Nuclear Information System (INIS)

The Permian continental basin of Lodeve, in the southern part of the Massif Central, 60 km west of Montpellier contains a significant uranium potential by French mining standards. The orebodies can take the form of ribbon-shaped, massive or even stratiform bodies, but always associated with bituminous facies beds and strong brittle tectonics. The major faults are sites of hydrothermal activity and in places hydraulic fracturing. Most of the uraniferous mineralisation is thought to have been associated with acid volcanism, contemporaneous with sedimentation, which could also have facilitated syn- and diagenetic preconcentrations of uranium. Later, in the course of two phases of hydrothermal mobilisation during the Jurassic and Cretaceous, uranium was remobilised on a large scale along faults containing bituminous material and impregnated with sulphides

39

Radiometric age determination of tonsteins and stratigraphic constraints for the Lower Permian coal succession in southern Parana Basin, Brazil  

Energy Technology Data Exchange (ETDEWEB)

Ion microprobe (SHRIMP II) dating of zircons from tonsteins interbedded with coal seams from the Candiota and Faxinal coalfields (Early Permian, Rio Bonito Formation, Parana Basin, Brazil) is presented. The mean ages obtained (290.6 {+-} 1.5 Ma) are more precise than previously published intervals. Calibrations of chronostratigraphic data with radiometric ages show that the main coal succession from the southern Basin is constrained to the Middle Sakmarian. The {+-} 2 Ma time interval of deposition supports the hypothesis that the coal-generating process was quite rapid in terms of geological time. In a general context, Faxinal and Candiota coals are assigned, into the Protohaploxypinus goraiensis Subzone, besides some paleocological differences evidenced by palynological studies. This bio-interval does not correspond to a consistent palynostratigraphic tool and more accurate biostratigraphic zonation for the Carboniferous-Permian interval must be delineated. The new results have far-reaching significance for correlations of the Basin with sequences of the Argentinian Paganzo Basin (302 {+-} 6 Ma and 288 {+-} 7 Ma) and also with the Karoo Basin, with the lowermost Ecca Group (288 {+-} 3 Ma and 289.6 {+-} 3.8 Ma). This new evidence supports the presence of an active and widespread Lower Permian explosive volcanic event in western Gondwana, which is interpreted as the same volcanism which produced the Choiyoi Group in western Argentina. According to this correlation the ash-fall source is located about 1400 km to the southwest of their area of deposition. (author)

Guerra-Sommer, Margot; Cazzulo-Klepzig, Miriam; Hartmann, Leo Afraneo; Formoso, Milton Luis Laquintinie [Instituto de Geociencias, Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves, 9500, 91501-970 Porto Alegre, Rio Grande do Sul (Brazil); Santos, Joao Orestes Schneider [Centre for Global Targeting, University of Western Australia, Crawley, Perth 6009, WA (Australia); Ketzer, Joao Marcelo [Instituto de Meio Ambiente, Pontificia Universidade Catolica, Avenida Ipiranga, Porto Alegre, Rio Grande do Sul (Brazil)

2008-03-03

40

Geological environment of the uranium deposits in the Permian of Lodeve Basin, France  

International Nuclear Information System (INIS)

The Permian rocks of the Lodeve Basin are characterized by a biorhexistasic cycle which produced fine alternating sequences of organic-rich sedimentary deposits in a basin ranging from lacustrine to a confined briny lagoon. The erosion of the Hercynian massifs, source for the sediments, along with the constant arrival of volcanic ash, provided metallic ions, particularly uranium. A continual subsidence permitted a regular influx of sediments and a burial compatible with a genesis of hydrocarbons. Post-sedimentary tectonic extension as well as the fine bedding of certain layers, created permeable zones that facilitated the circulation of fluids: the oils migrated, concentrated in petroleum-type traps by fault zones and the finely bedded layers. The interstitial waters flushed by compaction were carriers of metallic ions in solution. They used the same permeable zones as the oil, and the uranium was precipitated in the hydrocarbon traps which were strong reducing agents. During diagenesis, an important physical and mineralogical evolution affected the surroundings and certainly played a role of prime importance in the ''recycling'' and precipitation of the uranium. In the meantime, oxidizing and carbonate-bearing meteoric water rose within the rock formations along the principal faults, flushing and transporting uranium to the traps, developing a complementary accretion process. Classified into three principal types, the mineralizations developed within the framework ofizations developed within the framework of a dynamic basin system in which several factors - sedimentary, tectonic and diagenetic - operated. (author)

41

Depositional environment and coal petrography of the permian coal deposits in the Karoo Basins of South - West Tanzania (Ruhuhu, Songwe-Kiwira and Mhukuru Basins)  

Energy Technology Data Exchange (ETDEWEB)

The Permian coal deposits in the Karoo Basins of SW Tanzania have been investigated in terms of sedimentary environments and coal petrography. The Lower Permian (Sakmarian/Artinskian) coal deposits in the Ruhuhu and Songwe-Kiwira Basins occur in the Mchuchuma Formation (K2), which consists of Mpera Sandstone Member at the bottom, sandstone-coal facies in the middle and shale-coal-sandstone facies at the top. The Mpera Sandstone Member and the sandstone-coal facies occur only in the Ruhuhu Basin, at Ketewaka-Mchuchuma Subbasin and at Mbalawala section in the Ngaka Subbasin. They were not deposited in Mbuyura-Mkapa section (Ngaka Subbasin) and in the Songwe-Kiwira Basin. (orig.)

Zahabu Semkiwa, P.

1992-01-01

42

Detrital records for Upper Permian-Lower Triassic succession in the Shiwandashan Basin, South China and implication for Permo-Triassic (Indosinian) orogeny  

Science.gov (United States)

Upper Permian to Lower Triassic siliciclastic succession in the Shiwandashan Basin, South China, accumulated in response to a Permo-Triassic orogeny (often referred to as the Indosinian orogeny). The petrology, geochemistry and geochronology of this succession, along with north and northwest-directed paleocurrent indicators, reveal an evolving provenance related to erosion and reworking of Precambrian, Early Paleozoic and Permian to Early Triassic units exposed to the south of the basin. The Upper Permian to Lower Triassic sandstones within the basin are quartz dominated, which along with their high Th/Sc and Zr/Sc ratios indicate a multi-cycled source. Sandstone clasts in the Upper Permian conglomerates display age patterns similar to nearby Silurian strata. Other clast types (limestone, mudstone and cherts) are from the Early Paleozoic strata within or adjoining the basin. Detrital zircon age spectra of the strata display prominent age groups at 1200-800 Ma, 650-500 Ma and 460-420 Ma, and are inferred to have been derived from basement units similar to those exposed in the Yunkai Massif to the south and southeast of the Shiwandashan Basin and/or from reworking of the Paleozoic units around the basin. The Lower Triassic strata also contain 260-240 Ma zircons that were likely derived from magmatic rocks located to the south of the basin. The Late Permian marks a significant change in the paleogeography of the Shiwandashan Basin from an older deep marine chert succession to a terrestrial to shallow marine environment receiving an influx of clastic detritus related to uplift and erosion to the south of the basin. The Lower Triassic units within the basin record a further pulse of sediment influx including detritus derived from approximately syn-sedimentary magmatic activity. Yunkai Massif, located in the southeast of the basin, underwent uplift in Late Permian and provided majority detritus for the basin in the Late Permian to Early Triassic. Integration of provenance data with regional geological information, magmatic and metamorphic records to the south of the Shiwandashan Basin suggests the basin was converted from a pre-Late Permian deep marine extensional basin to a Late Permian to Early Triassic foreland basin. Conversion to a foreland basin reflected collision between the South China and Indochina blocks.

Hu, Lisha; Cawood, Peter A.; Du, Yuansheng; Xu, Yajun; Xu, Wangchun; Huang, Hongwei

2015-02-01

43

A mid-Permian chert event: widespread deposition of biogenic siliceous sediments in coastal, island arc and oceanic basins  

Science.gov (United States)

Radiolarian and conodont of Permian siliceous rocks from twenty-three areas in teh the circum-Pacific and Mediterranean regions reveal a widespread Permian Chert Event during the middle Leonardian to Wordian. Radiolarian- and (or) sponge spicule-rich siliceous sediments accumulated beneath high productivity zones in coastal, island arc and oceanic basins. Most of these deposits now crop out in fault-bounded accreted terranes. Biogenic siliceous sediments did not accumulate in terranes lying beneath infertile waters including the marine sequences in terranes of northern and central Alaska. The Permian Chert Event is coeval with major phosphorite deposition along the western margin of Pangea (Phosphoria Formation and related deposits). A well-known analogue for this event is middle Miocene deposition of biogenic siliceous sediments beneath high productivity zones in many parts of the Pacific and concurrent deposition of phosphatic as well as siliceous sediments in basins along the coast of California. Interrelated factors associated with both the Miocene and Permian depositional events include plate reorientations, small sea-level rises and cool polar waters. ?? 1992.

Murchey, B.L.; Jones, D.L.

1992-01-01

44

Late Permian cycle-stratigraphy in the continental deposits of the Karoo basin (South Africa) (Invited)  

Science.gov (United States)

Magnetostratigraphic and geochronological studies of late Permian Waterford and Abrahamskraal Formations (uppermost Ecca Group and lowermost Beaufort Group, respectively) in the Karoo Basin of South Africa yielded age-constrained magnetostratigraphy that can be correlated with the most recent reference geomagnetic polarity time scale. This precise chronological framework provides the basis for a chemostratigraphic analysis of cyclicity based on the measured major and trace element composition of these fluvial mudstones and sandstones. Our multi-taper spectral power analysis was computed using the concentration of major oxides, showing clear peaks at frequencies that are compatible with the expected orbital periodicities according to the magnetostratigraphic chronology. Given the length of the studied section (~500 m) and the relatively high sedimentation rate (~100m/Myr), we consider that the short hiatuses that are to be expected in river deposits are not likely to obliterate long-period cyclicity such as orbital eccentricity. We interpret long period cyclicity as reflecting orbital eccentricity (ca. 400 kyr), with even shorter period orbital frequencies observed in the record. Statistical analysis suggests that the chemical composition does not correlate with the sediments grain size but is related to the lithology through their relative abundance of clays and SiO2-rich clastic material. Although chemical changes might partly reflect stochastic fluctuation due to fluvial hydrodynamics, their orbital periodicity suggests that they are mainly paced by environmental changes that in turn may control the sediment weathering and/or fluvial dynamics. Recognition of the orbitally controlled sedimentation allows very precise dating of the time involved in the deposition of these sedimentary rocks. Astronomical tuning provides an improved calibration of this portion of the polarity time scale and give hints on the variability of the environmental conditions during the Late Permian.

Lanci, L.; Tohver, E.; Wilson, A.; Ratcliffe, K. T.; Flint, S.

2013-12-01

45

Thermomechanical analyses of conceptual repository designs for the Paradox and Permian Basins  

International Nuclear Information System (INIS)

The potential repositories are designed to accommodate all waste forms emplaced at various thermal loadings; specifically, commercial high-level waste (30 W/m2), spent fuel (15 W/m2), defense high-level waste (20 W/m2), and remote-handled and contact-handled transuranic nonheat-generating waste. The study evaluates the design parameters, primarily thermal loading, based on a comparison of calculable thermomechanical parameters with prescribed performance constraints. This evaluation was accomplished by numerical simulation using finite element techniques of the canister, disposal room, and repository regions of each potential site. Important thermal and thermomechanical results were compared with their prescribed constraint or limit value. All of the performance constraints were satisfied at the Davis Canyon site in the Paradox Basin for commercial high-level waste, spent fuel, and defense high-level waste at areal thermal loadings of 20 W/m2, 15 W/m2, and 20 W/m2, respectively. Similarly, for the Deaf Smith County site in the Permian Basin, commercial high-level waste, spent fuel, and defense high-level waste thermal loadings of 13.5 W/m2, 8.5 W/m2, and 6.0 W/m2, respectively, satisfied all of the performance constraints. 89 refs., 64 figs., 22 tabs

46

Late orogenic magmatism and sedimentation within Late Carboniferous to Early Permian basins in the Balkan terrane (Bulgaria): geodynamic implications  

Science.gov (United States)

The orogenic Balkanid belt, which developed between the Moesian Plate and the Moravian-Rhodopi-Thracian Massifs, was affected by the Late Carboniferous and Early Permian opening of W-E oriented graben structures. The progressive tectonic rejuvenation of the basins is demonstrated by the deposition of repeated regional sedimentary cycles, associated with volcanism that was mostly localised along the tectonic boundaries, in an intramontane setting.

Cortesogno, Luciano; Gaggero, Laura; Ronchi, Ausonio; Yanev, Slavcho

2004-09-01

47

Coricladus quiteriensis gen. et sp. nov., a new conifer in Southern-Brazil Gondwana (Lower Permian, Paraná Basin)  

OpenAIRE

A new taxon of conifers (Coricladus quiteriensis) is described based on megafloristic remains from the roofshale level at the Quitéria Outcrop (Rio Bonito Formation - Lower Permian - Southern Paraná Basin - Rio Grande do Sul - Brazil). This megafloristic community is included in the Botrychiopsis Zone - Botrychiopsis valida Sub-Zone (Kungurian/Roadian). The assemblage, preserved as impressions, do not present remains of epidermic characters, and is composed mainly of isolated vegetative bra...

Jasper André; Ricardi-Branco Fresia; Guerra-Sommer Margot

2005-01-01

48

Progress on the palynostratigraphy of the Permian strata in Rio Grande do Sul State, Paraná Basin, Brazil  

OpenAIRE

A review of published papers and results of analysis of new material have allowed improvements on the palynostratigraphy of the Permian strata of the Paraná Basin in Rio Grande do Sul State. Based on first and last occurrences of certain species of pollen taxa, two palynozones are formalized, these are the Vittatina costabilis and Lueckisporites virkkiae Interval Zones, in ascending order. The Vittatina costabilis Interval Zone is subdivided into two units, in ascending order the Protohaplox...

Souza, Paulo A.; Marleni Marques-Toigo

2005-01-01

49

Late Permian Palynology and depositional environment of Chintalapudi sub basin, Pranhita-Godavari basin, Andhra Pradesh, India  

Science.gov (United States)

The present study deals with the palynological dating, correlation and depositional setting of the sediments from bore cores MGP-11 and MGP-4 from Gauridevipet area of Chintalapudi sub-basin of Godavari master basin, south India. On the basis of palynological studies, three palynoassemblages have been identified, one in bore core MGP-11 a Faunipollenites (=Protohaploxypinus) and Striasulcites assemblage and two in bore core MGP-4; one is characterized by the dominance of striate bisaccates and Densipollenites and the other by Striatopodocarpites and Cresentipollenites palynoassemblages. The other stratigraphically significant taxa include Guttulapollenites hannonicus, Lunatisporites noviaulensis, Lunatisporites pellucidus, Densoisporites contactus, Chordasporites australiensis, Goubinispora spp., Lundbladispora microconata, Lundbladispora raniganjensis and Klausipollenites schaubergeri. The recovered taxa suggest a Late Permian, Lopingian age for these rocks. This interpretation is based on the correlation of the assemblages with similar assemblages from previous Gondwana studies chiefly Densipollenites magnicorpus Zone of Damodar Basin, India and Late Permian palynoassemblages from Africa, Antarctica, Australia and South America. On the basis of palaeobotanical affinity of the identified microflora it has been inferred that the peat forming plant community was composed mainly of gymnosperm pollen attributable to glossopterids, that includes striate and non-striate bisaccates and paucity of cordaites which includes monosaccates. Spores are subordinate and are derived from lycopsids (Lundbladispora, Densoisporites), sphenopsids (Latosporites) and filicopsids (Horriditriletes, Lophotriletes, Verrucosisporites, Osmundacidites, Leiotriletes, Callumispora, Brevitriletes and Microbaculispora) occurring in variable proportions. The dominance of subarborescent/arborescent vegetation suggests a development in a forest swamp probably in a small distant marginal part of the mire or periods of standing water. This flooding environment favoured the growth of herbaceous lycopsids, filicopsids and sphenopsids in the palaeomire. More or less similar environments of deposition have been deduced for both the sedimentary sequences on the basis of palynofacies analysis. Anaerobic, reducing, water logged peat-forming conditions have been inferred based on the abundance of phytoclasts. The relative abundance of structured organic matter implies the existence of a fairly dense vegetation cover in the hinterland. The charcoal fragments recovered from the present study area reflects a possible wildfire in the accumulated swamps or a wildfire in the hinterland after which the sediments were flushed by fluvial systems into the swamps.

Jha, Neerja; Pauline Sabina, K.; Aggarwal, Neha; Mahesh, S.

2014-01-01

50

Rock mechanics evaluation of potential repository sites in the Paradox, Permian, and Gulf Coast Basins: Volume 1  

International Nuclear Information System (INIS)

Thermal and thermomechanical analyses of a conceptual radioactive waste repository containing commercial and defense high-level wastes and spent fuel have been performing using finite element models. The thermal and thermomechanical responses of the waste package, disposal room, and repository regions were evaluated. four bedded salt formations, in Davis and Lavender Canyons in the Paradox Basin of southeastern Utah and in Deaf Smith and Swisher counties in the Permian Basin of northwestern Texas, and three salt domes, Vacherie Dome in northwestern Louisiana and Richton and Cypress Creek Domes in southeastern Mississippi, located in the Gulf Coast Basin, were examined. In the Paradox Basin, the pressure exerted on the waste package overpack was much greater than the initial in situ stress. The disposal room closure was less than 10 percent after 5 years. Surface uplift was nominal, and no significant thermomechanical perturbation of the aquitards was observed. In the Permian Basin, the pressure exerted on the waste package overpack was greater than the initial in situ stress. The disposal room closures were greater than 10 percent in less than 5 years. Surface uplift was nominal, and no significant thermomechanical perturbation of the aquitards was observed. In the Gulf Coast Basin, the pressure exerted on the waste package overpack was greater than the initial in situ stress. The disposal room closures were greater than 10 percent in less than 5 years. No significantrcent in less than 5 years. No significant thermomechanical perturbation of the overlying geology was observed. 40 refs., 153 figs., 32 tabs

51

Charcoal remains from a tonstein layer in the Faxinal Coalfield, Lower Permian, southern Paraná Basin, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Charcoal fóssil foi encontrado na Mina do Faxinal, Permiano Inferior, Formação Rio Bonito, na porção sul da Bacia do Paraná, Brasil. Foram descritos três tipos de lenhos gimnospérmicos picnoxílicos originários de um único nível de tonstein, o que confirma a ocorrência de paleoincêndios vegetacionais [...] nesta área. Uma redução da concentração de charcoal da base para o topo no nível de tonstein indica que a quantidade de combustível diminuiu durante a deposição, provavelmente devido ao consumo da vegetação existente pelo fogo. A presença de inertinita na camada de carvão, em níveis sobrepostos e sotopostos ao tonstein , indica que incêndios não estavam restritos ao intervalo de deposição da cinza vulcânica. A integração dos novos dados aqui apresentados com outros publicados anteriormente acerca da Mina do Faxinal, demonstra que eventos vulcânicos ocorridos nas áreas circunvizinhas podem ser identificados como potenciais fatores de ignição para os incêndios. A presença de chacoal em sedimentos associados a níveis de carvão em diferentes localidades no Permiano, demonstra que incêndios vegetacionais foram relativamente comuns nos ambientes formadores dos depósitos de carvão da Bacia do Paraná. Abstract in english Fossil charcoal has been discovered in the Faxinal Coalfield, Early Permian, Rio Bonito Formation, in the southernmost portion of the Paraná Basin, Brazil. Three types of pycnoxylic gymnosperm woods recovered from a single tonstein layer are described and confirm the occurrence of paleowildfire in t [...] his area. A decrease of the charcoal concentration from the base to the top within the tonstein layer indicates that the amount of fuel declined during the deposition probably due to the consumption of vegetation by the fire. The presence of inertinite in coals overlying and underlying the tonstein layer indicates that fire-events were not restricted to the ash fall interval. The integration of the new data presented in the current study with previously published data for the Faxinal Coalfield demonstrates that volcanic events that occurred in the surrounding areas can be identified as one potential source of ignition for the wildfires. The presence of charcoal in Permian sediments associated with coal levels at different localities demonstrates that wildfires have been relatively common events in the peat-forming environments in which the coal formation took place in the Paraná Basin.

André, Jasper; Dieter, Uhl; Margot, Guerra-Sommer; Abdalla M. B, Abu Hamad; Neli T. G, Machado.

2011-06-01

52

High precision radiometric ages from the northern Sydney Basin and their implication for the Permian time interval and sedimentation rates  

International Nuclear Information System (INIS)

Three pyroclastic samples that bracket the coal-bearing Permian System of the northern Sydney Basin have been dated using the zircon U/Pb and hornblende K/Ar methods. The Matthews Gap Dacitic Tuff Member, situated 170 m below the base of the Permian System, gives a best estimate of 309 ± 3 Ma. Its age correlates well with the Paterson Volcanics which suggests that the immediately overlying clastic sediments are equivalent to the Seaham Formation. The Awaba Tuff, which is located 50 m below the top of the Permian System, gives a best estimate of 256 ± 4 Ma. An intervening horizon, the Thornton Claystone of the Tomago Coal Measures, gives a best estimate of 266 ± 0.4 Ma. The ages indicate an earlier beginning ? 299 Ma BP), an earlier termination (? 255 Ma BP) and slightly longer duration (44±13 Ma) of the Permian System in the Hunter Valley than previously suggested. Sedimentation rates of ± 65m/Ma, calculated from proximal sequence thicknesses, are only half the rate calculated from the closest maximum thicknesses. Both are considerably lower than previously quoted rates. The estimated time interval of 10 Ma between the Thornton Claystone and the Awaba Tuff is more than twice the length of time previously attributed to accumulation of the combined Tomago and Newcastle Coal Measures. 38 refs., 5 tabs., 2 figs

53

Why stratigraphy and sedimentology in shales are important : an example from the Woodford Shale, Permian Basin, west Texas  

Energy Technology Data Exchange (ETDEWEB)

This presentation explained why stratigraphy and sedimentology in shales are important. The presentation provided an example from the Woodford Shale, Permian Basin, located in western Texas. Several illustrations were presented to demonstrate a stratigraphic sequence in black shale. Other topics that were discussed included geologic settings; paleogeography; silled basins; motivation for rock properties research; and factor analysis results. It was concluded that sequence stratigraphic analyses in black shales requires an integrated, multidisciplinary approach. The presentation showed that third and fourth order stratigraphic cycles are indicated by the repetition of exotic beds whose composition vary regionally. tabs., figs.

Harris, N.B. [Alberta Univ., Edmonton, AB (Canada); Colorado School of Mines, Boulder, CO (United States); Hemmesch, N.T.; Mnich, C.A. [Colorado School of Mines, Boulder, CO (United States). Geology and Geological Engineering; Aoudia, K.; Miskimins, J. [Colorado School of Mines, Boulder, CO (United States). Dept. of Petroleum Engineering

2010-07-01

54

Permian salt dissolution, alkaline lake basins, and nuclear-waste storage, Southern High Plains, Texas and New Mexico  

International Nuclear Information System (INIS)

Areas of Permian salt dissolution associated with 15 large alkaline lake basins on and adjacent to the Southern High Plains of west Texas and eastern New Mexico suggest formation of the basins by collapse of strata over the dissolution cavities. However, data from 6 other alkaline basins reveal no evidence of underlying salt dissolution. Thus, whether the basins were initiated by subsidence over the salt dissolution areas or whether the salt dissolution was caused by infiltration of overlying lake water is conjectural. However, the fact that the lacustrine fill in Mound Lake greatly exceeds the amount of salt dissolution and subsidence of overlying beds indicates that at least Mound Lake basin was antecedent to the salt dissolution. The association of topography, structure, and dissolution in areas well removed from zones of shallow burial emphasizes the susceptibility of Permian salt-bed dissolution throughout the west Texas-eastern New Mexico area. Such evidence, combined with previous studies documenting salt-bed dissolution in areas surrounding a proposed high-level nuclear-waste repository site in Deaf Smith County, Texas, leads to serious questions about the rationale of using salt beds for nuclear-waste storage

55

Permian salt dissolution, alkaline lake basins, and nuclear-waste storage, Southern High Plains, Texas and New Mexico  

Energy Technology Data Exchange (ETDEWEB)

Areas of Permian salt dissolution associated with 15 large alkaline lake basins on and adjacent to the Southern High Plains of west Texas and eastern New Mexico suggest formation of the basins by collapse of strata over the dissolution cavities. However, data from 6 other alkaline basins reveal no evidence of underlying salt dissolution. Thus, whether the basins were initiated by subsidence over the salt dissolution areas or whether the salt dissolution was caused by infiltration of overlying lake water is conjectural. However, the fact that the lacustrine fill in Mound Lake greatly exceeds the amount of salt dissolution and subsidence of overlying beds indicates that at least Mound Lake basin was antecedent to the salt dissolution. The association of topography, structure, and dissolution in areas well removed from zones of shallow burial emphasizes the susceptibility of Permian salt-bed dissolution throughout the west Texas-eastern New Mexico area. Such evidence, combined with previous studies documenting salt-bed dissolution in areas surrounding a proposed high-level nuclear-waste repository site in Deaf Smith County, Texas, leads to serious questions about the rationale of using salt beds for nuclear-waste storage.

Reeves, C.C. Jr.; Temple, J.M.

1986-11-01

56

Extent of water-rock interactions in Lower Permian Wolfcamp carbonates, Palo Duro Basin, Texas  

International Nuclear Information System (INIS)

A laterally-extensive permeable zone in upper Wolfcampian carbonate strata constitutes the first important transmissive unit below a thick evaporite sequence that is being considered for nuclear waste isolation. The extent of water-rock interaction was evaluated by comparing the chemical and isotopic composition of formation water and core collected at four DOE test wells. Wolfcamp mineralogy is dominantly calcite and dolomite with minor anhydrite at each of the four sites despite minor variations in depositional environment, diagenetic alteration, and abundance of clastic material. Isotopic compositions of calcite and dolomite and of anhydrite are within the ranges expected for Permian marine sediments altered by early diagenesis. Wolfcamp formation water compositions are more variable than host rock compositions, and are not completely controlled by local water-rock equilibria. Wolfcamp brines from two wells in the western part of the basin have depleted isotopic compositions relative to the two eastern wells and have not equilibrated with Wolfcamp carbonates, whereas the eastern fluids have. Strontium in the western samples is more radiogenic than that of the eastern samples, indicating a greater influence of clays or feldspars on the western fluids. Comparison of water and rock compositions suggests: (1) the western brines have interacted less with the carbonate host than the eastern brines due to shorter residence times or greater water: rock ratios, and (2) the r greater water: rock ratios, and (2) the minerals encountered along flow paths prior to entering the Wolfcamp are different for the western and eastern Wolfcamp brines

57

Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa  

Scientific Electronic Library Online (English)

Full Text Available Dicynodonts are an extinct group of herbivorous non-mammalian therapsids ('mammal-like' reptiles) that are widely known from terrestrial Permo-Triassic strata throughout Pangaea. Dicynodont fossil remains are common within the Late Permian Beaufort Group of the Karoo Basin in South Africa. A large, [...] partially articulated dicynodont skeleton recovered from the Tropidostoma Assemblage Zone is taphonomically important in having an unusual disarticulation pattern, bone surface punctures and a broken tooth of an unidentified carnivore associated with it. Here we report on the nature of the bone damage, and the identity of the carnivore that lost a canine tooth whilst scavenging the dicynodont carcass. The morphological characteristics of the serrations on the unidentified tooth were compared with those of contemporaneous carnivores, the gorgonopsians and therocephalians. Scanning electron microscopy analysis of a silicone cast of the unidentified tooth revealed distinctive 0.5-mm square-shaped serrations. Our comparative assessment of the tooth size, curvature, cross-sectional shape and morphology of the serrations revealed that the unidentified canine most closely matched Aelurognathus, a gorgonopsian known from the same assemblage zone.

Nicholas, Fordyce; Roger, Smith; Anusuya, Chinsamy.

58

Thermal conductivity and diffusivity of Permian Basin bedded salt at elevated pressure and temperature  

International Nuclear Information System (INIS)

Measurements of thermal conductivity and diffusivity were made on five core samples of bedded rock salt from the Permian Basin in Texas to determine its suitability as an underground nuclear waste repository. The sample size was 100 mm in diameter by 250 mm in length. Measurements were conducted under confining pressures ranging from 3.8 to 31.0 MPa and temperatures from room temperature to 473 K. Conductivity showed no dependence on confining pressure but evidenced a monotonic, negative temperature dependence. Four of the five samples showed conductivities clustered in a range of 5.6 +- 0.5 W/m.K at room temperature, falling to 3.6 +- 0.3 W/m.K at 473 K. These values are approximately 20% below those for pure halite, reflecting perhaps the 5 to 20%-nonhalite component of the samples. Diffusivity also showed a monotonic, negative temperature dependence, with four of the five samples clustered in a range of 2.7 +- 0.4 x 10-6 m2/s at room temperature, and 1.5 +- 0.3 x 10-6 m2/s at 473 K, all roughly 33% below the values for pure halite. One sample showed an unusually high conductivity (it also had the highest diffusivity), about 20% higher than the others; and one sample showed an unusually low diffusivity (it also had the lowest conductivity), roughly a factor of 2 lower than the others. 27 references, 8 figures, 4 tables

59

Evidence of a therapsid scavenger in the Late Permian Karoo Basin, South Africa  

Directory of Open Access Journals (Sweden)

Full Text Available Dicynodonts are an extinct group of herbivorous non-mammalian therapsids (‘mammal-like’ reptiles that are widely known from terrestrial Permo-Triassic strata throughout Pangaea. Dicynodont fossil remains are common within the Late Permian Beaufort Group of the Karoo Basin in South Africa. A large, partially articulated dicynodont skeleton recovered from the TropidostomaAssemblage Zone is taphonomically important in having an unusual disarticulation pattern, bone surface punctures and a broken tooth of an unidentified carnivore associated with it. Here we report on the nature of the bone damage, and the identity of the carnivore that lost a canine tooth whilst scavenging the dicynodont carcass. The morphological characteristics of the serrations on the unidentified tooth were compared with those of contemporaneous carnivores, the gorgonopsians and therocephalians. Scanning electron microscopy analysis of a silicone cast of the unidentified tooth revealed distinctive 0.5-mm square-shaped serrations. Our comparative assessment of the tooth size, curvature, cross-sectional shape and morphology of the serrations revealed that the unidentified canine most closely matched Aelurognathus,a gorgonopsian known from the same assemblage zone.

Nicholas Fordyce

2012-10-01

60

Pumping test and fluid sampling report, Mansfield No. 1 well, Palo Duro Basin: Report of the Geologic Project Manager, Permian Basin  

International Nuclear Information System (INIS)

This report describes pumping test and fluid sampling activities performed at the Mansfield No. 1 well in Oldham County about 10 miles north of Vega, Texas. The well site was selected by TBEG and is located along the northern margin of the Palo Duro Basin in an area of active dissolution with the Permian salt sections. The objectives of the pumping test and fluid sampling program were to collect data to determine the hydrologic characteristics (formation pressure and permeability) of deep water bearing formations, and to obtain formation fluid samples for analyses (gas and fluid chemistry) in order to evaluate fluid migration and age relationships in the Permian Basin. 4 refs., 8 figs., 2 tabs

61

U-Pb zircon ages from the southwestern Karoo Basin, South Africa - Implications for the Permian-Triassic boundary  

Science.gov (United States)

U-Pb ages determined using sensitive high-resolution ion microprobe-reverse geometry on 205 single-grain zircons from 16 ash beds within submarine fan deposits of the Ecca Group provide the first evidence of a marine Permian-Triassic (P-T) boundary in the Karoo Basin of South Africa. These U-Pb ages provide an objective basis for correlating the deep-marine sediments of the southwest Karoo Basin with fluvial-deltaic deposits in the central and eastern parts of the basin where the P-T boundary is recorded in a diverse macrofauna. Furthermore, these new zircon ages and their correlation imply asymmetric subsidence and variable sedimentation rates across the basin. ?? 2009 Geological Society of America.

Fildani, A.; Weislogel, A.; Drinkwater, N.J.; McHargue, T.; Tankard, A.; Wooden, J.; Hodgson, D.; Flint, S.

2009-01-01

62

Natural gas qualities in the Southern Permian basin; Die Erdgasqualitaeten im suedlichen Permbecken  

Energy Technology Data Exchange (ETDEWEB)

There is a substantial amount of molecular and isotopic gas data in the literature but mostly in the archives of companies and geological services. As the geological services of most European countries traditionally contain (confidential and non-confidential) data on geology and resources these institutions from Great Britain, the Netherlands, Denmark, Poland and Germany decided to compile molecular and isotopic natural gas data from the area of the Southern European Permian basin. The partially EU-subsidised project was carried out between 1994 and 1997 (LOKHORST ed. 1998) The atlas is based on existing data and also on newly determined molecular and isotopic gas parameters. Ring analyses of national and international standard gases ensure the quality and comparability of the data thus obtained. The aim of the ``stocktaking`` of natural gas was to describe the gas qualities from the Southern North Sea in the West to the Eastern borders of Poland, to characterise them genetically and to relate the to the geological environment. (orig.) [Deutsch] Ein substantieller Anteil von molekularen und isotopischen Gasdaten existiert, teilweise in der Literatur, vor allem aber in den Archiven der Firmen und der geologischen Dienste. Da die geologischen Dienste der meisten europaeischen Laender traditionell (oeffentliche und vertrauliche) Daten ueber die Geologie und Rohstoffe vorhalten, haben sich diese Institutionen aus Grossbritanien, den Niederlanden, Daenemark, Polen und Deutschlands entschlossen, molekulare und isotopische Erdgasdaten aus dem Bereich des suedlichen europaeischen Permbeckens zu kompilieren. Das partiell von der EU gefoerderte Projekt wurde in den Jahren 1994 bis 1997 durchgefuehrt (LOKHORST ed. 1998). Ausser auf bereits vorhandenen Daten beruht der Atlas auf etwa 200 Neu-Bestimmungen molekularer und isotopischer Gasparameter. Ringanalysen nationaler und internationeler Standardgase gewaehrleisteten die Qualitaet und die Vergleichbarkeit der gewonnenen Daten. Ziele dieser `Erdgas-Inventur` waren, die Gasqualitaeten in ihrer raeumlichen Verteilung von der suedlichen Nordsee im Westen bis nahezu an die Ostgrenze Polens darzustellen, sie genetisch zu charakterisieren und eine Beziehung zu den geologischen Rahmenbedingungen herzustellen. (orig.)

Gerling, P.; Kockel, F. [BGR, Hannover (Germany); Lokhorst, A.; Geluk, M.C. [TNO, Haarlem (Netherlands); Nicholson, R.A. [British Geological Survey, Nottingham (United Kingdom); Laier, T. [Danmarks og Groenlands Geologiske Undersoegelse, Kopenhagen (Denmark); Pokorski, J. [Panstwowy Instytut Geologiczny, Warsaw (Poland)

1998-12-31

63

Fibers and cylinders of cryptomelane-hollandite in Permian bedded salt, Palo Duro Basin, Texas  

International Nuclear Information System (INIS)

Fibers and thin-walled, hollow cylinders of cryptomelane-hollandite have been found in both the chevron and the clear salt from various drill cores in Permian bedded salt from the Palo Duro Basin, Texas. The authors have found fibers or cylinders from only the lower San Andres Formation units 4 and 5, the upper San Andres Formation, and the Salado-Transill salt. The fibers are inorganic, light to dark reddish brown, pleochroic, highly birefringent, filamentary single crystals, < 1 to ? 5 ?m in diameter, with length-to-diameter ratios of at least 20:1. The fibers can be straight and/or curved, can bifurcate, can form loops, waves or spirals, and can be isolated or in parallel groups. Detailed petrographic analyses show no evidence for recrystallization or deformation of the enclosing salt after fiber formation. Although the authors observations do not provide a definitive explanation for fiber origin, they suggest that the fibers grew in situ by a solid-state diffusional process at low temperatures. The cylinders are pleochroic, highly birefringent, light to dark reddish brown, hollow, thin-walled, open-ended right cylinders, having a 1- to 2-?m wall thickness and variable lengths and diameters. There also appear to be single crystals of cryptomelane-hollandite, but these are found almost entirely in fluid inclusions in the chevron and clear salt. Their presence in the primary halite suggests that they were formed contemporaneously with the chevron structure and weusly with the chevron structure and were accidentally trapped in the fluid inclusions. The observation of cylinders partially or completely enclosed by salt stratigraphically above large fluid inclusions suggests that natural downward fluid-inclusion migration has occurred, in response to the geothermal gradient

64

Thermal properties of Permian Basin evaporites to 493 K temperature and 30 MPa confining pressure  

International Nuclear Information System (INIS)

Laboratory measurements of the thermal conductivity and diffusivity of four rock salts, two anhydrites, and two dolomites bordering Cycle 4 and Cycle 5 bedded salt formations in the Permian Basin in Deaf Smith County, Texas, were made in conditions ranging from 303 to 473 K in temperature and 0.1 to 31.0 MPa in hydrostatic confining pressure. Within the +-5% measurement resolution neither conductivity nor diffusivity showed a dependence upon pressure in any of the rocks. Conductivity and diffusivity in all rocks had a negative temperature dependence. For the Cycle 4 salt samples, conductivity fell from 5.5 to 3.75 W/m . K, and diffusivity fell from about 2.7 to 1.7 x 10-6 m2/s. One Cycle 5 salt was a single crystal with anomalous results, but the other had a low conductivity with very weak temperature dependence and a high diffusivity. In the nonsalts, conductivity and diffusivity decreased 10 to 20% over the temperature range explored. In measurements of the coefficient of thermal linear expansion for Cycle 5 salt and nonsalts, the coefficient typically varied from about 12 x 10-6 K-1 at P = 3.0 MPa to 4 x 10-6 K-1 at P = 30 MPa for both nonsalt rocks. In anhydrite, it decreased with increasing temperature. In dolomite, the coefficient increased at roughly the same rate. Expansion of the salt ranged from 33 to 38 x 10-6 K-1 and was independent of pressure and temperature

65

Petrographic approach to the study of organic microfossils from the Irati Subgroup (Permian, Paraná Basin, Brazil)  

Science.gov (United States)

Early diagenetic chert, infrequently exploited in Phanerozoic micropaleontology, was examined for organic-walled microfossils in petrographic thin sections of silicified dolostones from diverse levels and localities of the Assistência Formation (Permian, Paraná Basin) in the state of São Paulo, Brazil. In contrast to previous palynological studies of this formation, the use of thin sections allowed direct observation in three dimensions of common palynomorphs, as well as benthic microbial mats preserved in situ in various stages of their life cycles and degradation. As in palynological residues from the more well-known shale of this formation, the chert contains wind-dispersed pollen grains and phytoclasts derived from terrestrial sources and planktonic cryptarchs (unornamented coccoidal unicellular or colonial palynomorphs). However, only in the chert is it possible to see much more delicate microfossils, such as abundant cyanobacteria of the in situ benthic microbiota as well as chlorophycean microalgae of the microphytoplankton. Post-depositional processes affecting the formation have destroyed all but the most resistant organic remains in the other lithologies, such that only rare, degraded pollen grains are seen in the unsilicified dolostone of the formation, and in the shale the vast majority of microfossils have been compacted to flattened disks. On the other hand, early silicification not only preserved organic remains at an incipient stage of decomposition but also impeded significant further degradation due to compaction, recrystallization, and oxidation. Thus, the petrographic study of such chert can complement traditional palynological investigations in Phanerozoic rocks by furnishing hitherto unavailable information, especially with regard to benthic organic microfossils and fragile organic-walled phytoplankton normally absent from organic residues.

Calça, Cléber Pereira; Fairchild, Thomas R.

2012-04-01

66

Regional summary and recommended study areas for the Texas panhandle portion of the Permian Basin. Technical report  

International Nuclear Information System (INIS)

This report summarizes the regional geologic and environmental characterizations that have been completed for the Permian region of study, and describes the procedure used to identify study areas for the next phase of investigation. The factors evaluated in the Permian region fall into three broad areas: health and safety, environmental and socioeconomic, and engineering and economic considerations. Health and safety considerations included salt depth and thickness, faults, seismic activity, groundwater, salt dissolution, energy and mineral resources, presence of boreholes, and interactive land uses. Salt depth and thickness was the key health and safety factor, and when mapped, proved to be a discriminator. The evaluation of environmental and socioeconomic conditions focused primarily on the presence of urban areas and on designated land uses such as parks, wildlife areas, and historic sites. Engineering and economic considerations centered primarily on salt depth, which was already evaluated in the health and safety area. The Palo Duro and Dalhart basins are recommended for future studies on the basis of geology. In these two basins, salt depth and thickness appear promising, and there is less likelihood of past or future oil and gas exploratory holes. Environmental and socioeconomic factors did not preclude any of the basins from further study

67

OIL RESERVOIR CHARACTERIZATION AND CO2 INJECTION MONITORING IN THE PERMIAN BASIN WITH CROSSWELL ELECTROMAGNETIC IMAGING  

Energy Technology Data Exchange (ETDEWEB)

Substantial petroleum reserves exist in US oil fields that cannot be produced economically, at current prices, unless improvements in technology are forthcoming. Recovery of these reserves is vital to US economic and security interests as it lessens our dependence on foreign sources and keeps our domestic petroleum industry vital. Several new technologies have emerged that may improve the situation. The first is a series of new flooding techniques to re-pressurize reservoirs and improve the recovery. Of these the most promising is miscible CO{sub 2} flooding, which has been used in several US petroleum basins. The second is the emergence of new monitoring technologies to track and help manage this injection. One of the major players in here is crosswell electromagnetics, which has a proven sensitivity to reservoir fluids. In this project, we are applying the crosswell EM technology to a CO{sub 2} flood in the Permian Basin oil fields of New Mexico. With our partner ChevronTexaco, we are testing the suitability of using EM for tracking the flow of injected CO{sub 2} through the San Andreas reservoir in the Vacuum field in New Mexico. The project consisted of three phases, the first of which was a preliminary field test at Vacuum, where a prototype system was tested in oil field conditions including widely spaced wells with steel casing. The results, although useful, demonstrated that the older technology was not suitable for practical deployment. In the second phase of the project, we developed a much more powerful and robust field system capable of collecting and interpreting field data through steel-cased wells. The final phase of the project involved applying this system in field tests in the US and overseas. Results for tests in steam and water floods showed remarkable capability to image between steel wells and provided images that helped understand the geology and ongoing flood and helped better manage the field. The future of this technology is indeed bright with development ongoing and a commercialization plan in place. We expect that this DOE sponsored technology will be a major technical and commercial success story in the coming years.

Michael Wilt

2004-02-01

68

A comparison of the Iberian and Ebro Basins during the Permian and Triassic, eastern Spain: A quantitative subsidence modelling approach  

Science.gov (United States)

The Permian-Triassic sediments of the Iberian Plate are a well studied case of classical Buntsandstein-Muschelkalk-Keuper facies, with good sedimentological interpretations and precise datings based on pollen and spore assemblages, ammonoids and foraminifera. Synrift-postrift cycles are recorded in these facies, but there are only a few studies of quantitative subsidence analysis (backstripping method) and only a previous one using forward modelling for the quantification of synrift-postrift phases of this period. Here we present the results obtained by the quantitative analysis of fourteen field sections and oil-well electric log records in the Iberian and Ebro Basins, Spain. Backstripping analysis showed five synrift phases of 1 to 3 million years duration followed by postrift periods for the Permian-Triassic interval. The duration, however, shows lateral variations and some of them are absent in the Ebro Basin. The forward modelling analysis, assuming local isostatic compensation, has been applied to each observation point using one-layer and two-layer lithospheric configurations. The second one shows a better fit between observation and model prediction in a systematic way, so a two layer configuration is assumed for the sedimentary basin filling analysis. Lithospheric stretching factors ? and ? obtained in the forward modelling analysis are never higher than 1.2, but sometimes ? 1 in the same section. If surficial extension is compensated by deep compression either at the roots of the rift basins or in far-away zones is not yet clear, but this anomaly can be explained using a simple shear extensional model for the Iberian and Ebro basins.

Vargas, Henar; Gaspar-Escribano, Jorge M.; López-Gómez, José; Van Wees, Jan-Diederik; Cloetingh, Sierd; de La Horra, Raúl; Arche, Alfredo

2009-09-01

69

The Post-Permian evolution of the Northern Part of the North German Basin  

Science.gov (United States)

In the frame of the Priority Program 1135 of the German Research Foundation (DFG) "Dynamics of sedimentary systems under varying stress conditions by example of the Central European Basin System", the scientific goal of the NeoBaltic project is to describe the post-Permian to recent geological evolution of the entire western Baltic Sea region, with a special emphasis on neotectonic activity and it relation to salt dynamics. The western Baltic Sea comprises the northern part of the North German Basin (NGB), a part of the Central European Basin System (CEBS), and the transitional zone between the NGB and the Baltic Shield. In order to investigate these scientific goals the Universities of Aarhus (Denmark) and Hamburg (Germany) has since 1998 completed seven marine campaigns in the western Baltic Sea, collecting 2D high resolution seismic (HRS), gravity and magnetic data in the entire region during different projects. Since 2003 all these data has been available for the NeoBaltic project. All together the data pool have more than 7000 km HRS, 5000 km gravity and 4000 km magnetic data. Until now the project work has been focused on the completion of the data processing and the digital interpretation of important Mesozoic and Cenozoic markers on the seismic sections from the Bays of Kiel and Mecklenburg. Furthermore, several maps have been completed from the potential field data (gravity and magnetic). As a result of the digital interpretation of the HRS data, the overall geological evolution of the northern part of the NGB can be subdivided into four distinct periods. During the Triassic and the Early Jurassic, E-W extension and the deposition of clastic sediments initiated the movement of the underlying Zechstein evaporites. This is seen by the presence of several salt pillows in the region. The deposition ceased during the Middle Jurassic, when the entire area was uplifted, due to the Mid North Sea Doming. The uplift resulted in a pronounced erosion of Upper Triassic and Lower Jurassic strata. This event is marked by a clear unconformity on the seismic sections. The region remained an area of non-deposition until the end of the Early Cretaceous. The sedimentation resumed in the late part of the Early Cretaceous and continued throughout the Late Cretaceous. No pronounced halokinesis has been detected during this period. Towards the end of the Late Cretaceous, the Alpine Collision caused the reactivation of salt structures seen on a thinning of the Cenozoic sequence across the different structures. As a result of the different Pleistocene glaciasations, several buried valleys have been detected on the seismic sections, especially in the Bay of Kiel and the Danish Lillebelt region. Some of these buried valleys contain biogenic gas, which results in a sufficient pull-down of the underlying markers on the seismic sections.

Hansen, M. B.; Huebscher, C.; Lykke-Andersen, H.; Gajewski, D.; Dehghani, A.; Reicherter, K.

2004-12-01

70

Regulatory Project Manager for Salina and Permian Basins for the NWTS [National Waste Terminal Storage] Program: Final techical report  

International Nuclear Information System (INIS)

The identification of candidate sites for nuclear waste repositories involves geological and environmental studies to characterize potential sites. These investigations include the collection and analysis of detailed geological and environmental data and comparison of the data against predetermined site performance criteria, i.e., geologic characteristics, environmental protection, and socioeconomic impacts. The work summarized in this final technical report encompasses mainly ''environmental characterization'' studies in the Permian Basin in the Texas Panhandle during the period of 1977-86; in the earlier phase of the contract, regional environmental work was also done in the Salina Basin (1977-79) and certain licensing support activities and safety analyses were conducted (1977-82). Considerable regulatory support work was also performed during 1986. 9 figs., 2 tabs

71

Rock Magnetic Properties of the Latest Permian to Earliest Triassic Beaufort Group, Tweefontein area, Karoo Basin, South Africa  

Science.gov (United States)

Over the past decade, terrestrial records of the end Permian mass extinction have received increased attention to better understand the absolute age of these deposits and their synchronicity with their marine counterparts. One of the best preserved terrestrial records of the Permian-Triassic boundary (PTB) is in the Eastern Cape of the Karoo Basin of South Africa. Study of the rock magnetic properties of Beaufort Group strata deposited across the vertebrate-defined PTB (Palingkloof member of the Balfour Formation and Katberg Formation) is part of an ongoing investigation to better understand the magnetic polarity stratigraphy across the PTB in the Karoo Basin. The definition of a magnetic polarity stratigraphy in these strata is predicated on the recognition of primary or early-acquired magnetizations. However, almost the entire region where Permian and Lower Triassic strata crop out is intruded by Early Jurassic (ca. 186-183 Ma) Karoo sills and related rocks, whose remanence is almost exclusively of normal polarity. Preliminary paleomagnetic results from the Tweefontein area (West Lootsberg Pass) suggest that Beaufort Group strata are overprinted by a normal polarity remanence similar in direction to Karoo sills sampled in a regional context. To better characterize the remanence in these rocks and assess the preservation of a primary remanence, a systematic rock magnetic stratigraphy is being obtained from a nearly continuously exposed, sub-horizontal section (~150 m) of upper Permian (Elandberg and Palingkloof members of the Balfour Formation) to lower Triassic strata (Katberg Formation) Preliminary anisotropy of magnetic susceptibility (AMS) data shows that a well-developed sedimentary fabric is preserved, with K3 directions near vertical and of low dispersion (e.g., decl/inc [confid estimates] 170/77 [ 5.1/4.1]; 228/85 [7.2/3.5] and 164/84 [9.3/3.0]). In general, bulk magnetic susceptibility data group at ~2.3x10-4 or ~4.8x10-4 SI volume and do not suggest substantial modification by remagnetization processes. NRM intensities range from 5 to 60 mA/m, and are not indicative of a strong thermal modification of the remanence/magnetic mineralogy. Preliminary petrographic studies of siltstones and very fine sandstones show that unaltered, detrital magnetite and maghemite grains of a few tens of microns in diameter, or less, are common.

Lycka, B.; Geissman, J. W.; Gastaldo, R.; Neveling, J.

2013-12-01

72

Problems and challenges in detection of pre-Mesozoic maar volcanoes: example from the Principálek Volcano in the Permian Krkonoše Piedmont Basin.  

Czech Academy of Sciences Publication Activity Database

Ro?. 59, ?. 3 (2014), s. 169-181. ISSN 1802-6222 Institutional support: RVO:67985891 Keywords : diatreme * geophysics * volcanology * Permian * Krkonoše Piedmont Basin Subject RIV: DB - Geology ; Mineralogy Impact factor: 0.744, year: 2013 http://www.jgeosci.org/detail/jgeosci.170

Valenta, Jan; Rapprich, V.; Stárková, M.; Skácelová, Z.; Fojtíková, Lucia; Stan?k, František; Balek, Jan

2014-01-01

73

Integrated Synthesis of the Permian Basin: Data and Models for Recovering Existing and Undiscovered Oil Resources from the Largest Oil-Bearing Basin in the U.S.  

Energy Technology Data Exchange (ETDEWEB)

Large volumes of oil and gas remain in the mature basins of North America. This is nowhere more true than in the Permian Basin of Texas and New Mexico. A critical barrier to recovery of this vast remaining resource, however, is information. Access to accurate geological data and analyses of the controls of hydrocarbon distribution is the key to the knowledge base as well as the incentives needed by oil and gas companies. The goals of this project were to collect, analyze, synthesize, and deliver to industry and the public fundamental information and data on the geology of oil and gas systems in the Permian Basin. This was accomplished in two ways. First we gathered all available data, organized it, and placed it on the web for ready access. Data include core analysis data, lists of pertinent published reports, lists of available cores, type logs, and selected PowerPoint presentations. We also created interpretive data such as type logs, geological cross sections, and geological maps and placed them in a geospatially-registered framework in ARC/GIS. Second, we created new written syntheses of selected reservoir plays in the Permian basin. Although only 8 plays were targeted for detailed analysis in the project proposal to DOE, 14 were completed. These include Ellenburger, Simpson, Montoya, Fusselman, Wristen, Thirtyone, Mississippian, Morrow, Atoka, Strawn, Canyon/Cisco, Wolfcamp, Artesia Group, and Delaware Mountain Group. These fully illustrated reports include critical summaries of published literature integrated with new unpublished research conducted during the project. As such these reports provide the most up-to-date analysis of the geological controls on reservoir development available. All reports are available for download on the project website and are also included in this final report. As stated in our proposal, technology transfer is perhaps the most important component of the project. In addition to providing direct access to data and reports through the web, we published 29 papers dealing with aspects of Permian Basin and Fort Worth Basin Paleozoic geology, and gave 35 oral and poster presentations at professional society meetings, and 116 oral and poster presentations at 10 project workshops, field trips, and short courses. These events were attended by hundreds of scientists and engineers representing dozens of oil and gas companies. This project and the data and interpretations that have resulted from it will serve industry, academic, and public needs for decades to come. It will be especially valuable to oil and gas companies in helping to better identify opportunities for development and exploration and reducing risk. The website will be continually added to and updated as additional data and information become available making it a long term source of key information for all interested in better understanding the Permian Basin.

John Jackson; Katherine Jackson

2008-09-30

74

Lower Permian stems as fluvial paleocurrent indicators of the Parnaíba Basin, northern Brazil  

Science.gov (United States)

A comprehensive biostratinomic study was carried out with abundant stems from the Lower Permian Motuca Formation of the intracratonic Parnaíba Basin, central-north Brazil. The fossils represent a rare tropical to subtropical paleofloristic record in north Gondwana. Tree ferns dominate the assemblages (mainly Tietea, secondarily Psaronius), followed by gymnosperms, sphenophytes, other ferns and rare lycophytes. They are silica-permineralized, commonly reach 4 m length (exceptionally more than 10 m), lie loosely on the ground or are embedded in the original sandstone or siltstone matrix, and attract particular attention because of their frequent parallel attitudes. Many tree fern stems present the original straight cylindrical to slightly conical forms, other are somewhat flattened, and the gymnosperm stems are usually more irregular. Measurements of stem orientations and dimensions were made in three sites approximately aligned in a W-E direction in a distance of 27.3 km at the conservation unit "Tocantins Fossil Trees Natural Monument". In the eastern site, rose diagrams for 54 stems indicate a relatively narrow azimuthal range to SE. These stems commonly present attached basal bulbous root mantles and thin cylindrical sandstone envelopes, which sometimes hold, almost adjacent to the lateral stem surface, permineralized fern pinnae and other small plant fragments. In the more central site, 82 measured stems are preferentially oriented in the SW-NE direction, the proportion of gymnosperms is higher and cross-stratification sets of sandstones indicate paleocurrents mainly to NE and secondarily to SE. In the western site, most of the 42 measured stems lie in E-W positions. The predominantly sandy succession, where the fossil stems are best represented, evidences a braided fluvial system under semiarid conditions. The low plant diversity, some xeromorphic features and the supposedly almost syndepositional silica impregnation of the plants are coherent with marked dry seasons. Thick mudstones and some coquinites below and above the sandy interval may represent lacustrine facies formed in probably more humid conditions. The taphonomic history of the preserved plants began with exceptional storms that caused fast-flowing high water in channels and far into the floodplains. In the eastern site region, many tree ferns only fell, thus sometimes covering and protecting plant litter and leaves from further fragmentation. Assemblages of the central and western sites suggest that the trees were uprooted and transported in suspension (floating) parallel to the flow. Heavier ends of stems (according to their form or because of attached basal bulbous root mantle or large apical fronds) were oriented to upstream because of inertial forces. During falling water stage, the stems were stranded on riverbanks, usually maintaining the previous transport orientation, and were slightly buried. The perpendicular or oblique positions of some stems may have been caused by interference with other stems or shallow bars. Rare observed stems were apparently waterlogged before the final depositional process and transported as bedload. The differences of interpreted channel orientations between the three sites are expected in a braided fluvial system, considering the very low gradients of the basin and the work scale in the order of tens of kilometers. The mean direction of the drainage probably was to east and the flows apparently became weaker downstream. This study seems to provide reliable data for paleocurrent interpretations, especially considering areas with scarce preserved sedimentary structures.

Capretz, Robson Louiz; Rohn, Rosemarie

2013-08-01

75

Ichnological analysis in San Gregorio deposits (Lower Permian) in the Guazunambi hills area Uruguayan north basin  

International Nuclear Information System (INIS)

Ichnological analysis in deposits corresponding to San Gregorio Fm.(lower Permian) in the Guazunambi hills area (Cerro Largo Department, Uruguay) was made.Trace fossils in sandstones and mud stones outcrops were studied.The ichnofossil assemblage studied allows to propose a shallow marine environment. (author)

76

Provenance study of Permian non-marine sandstones and conglomerates of the Krkonoše Piedmont Basin (Czech Republic): exotic marine limestone pebbles, heavy minerals and garnet composition  

OpenAIRE

This study focuses on identifying major source areas in several stratigraphic intervals in the Permian sediments of the Krkonoše Piedmont Basin and integrates it with existing sedimentological data. Pebbles in Cisuralian-Guadalupian conglomerates of alluvial fans, nearshore lacustrine and lacustrine fan-delta deposits that were deposited close to the northwestern and southeastern basin margin, respectively, correspond almost exclusively to local material from adjacent crystalline complexes. ...

Martínek K; Štolfová K

2009-01-01

77

Depositional cyclicity and paleoecological variability in an outcrop of Rio Bonito Formation, Early Permian, Parana Basin, Rio Grande do Sul, Brazil  

Energy Technology Data Exchange (ETDEWEB)

This article integrates faciological, paleobotanical, and palynological analyses to establish the relationship between depositional cyclicity and paleoecological patterns for the (Early Permian) Quiteria outcrop, Rio Bonito Formation, southern Parana Basin, Rio Grande do Sul state. The record in some coal palynofloras of Striadopodocarpites fusus, a component of the Hamiapollenites karrooensis subzone, as defined in the palynostratigraphic framework for the Parana Basin, indicates a Kungurian age for the palynoflora.

Jasper, A.; Menegat, R.; Guerra-Sommer, M.; Cazzulo-Klepzig, M.; de Souza, P.A. [UNIVATES, Lajeado (Brazil)

2006-07-15

78

Play Analysis and Digital Portfolio of Major Oil Reservoirs in the Permian Basin: Application and Transfer of Advanced Geological and Engineering Technologies for Incremental Production Opportunities  

Energy Technology Data Exchange (ETDEWEB)

A play portfolio is being constructed for the Permian Basin in west Texas and southeast New Mexico, the largest onshore petroleum-producing basin in the United States. Approximately 1,300 reservoirs in the Permian Basin have been identified as having cumulative production greater than 1 MMbbl (1.59 x 10{sup 5} m{sup 3}) of oil through 2000. Of these significant-sized reservoirs, approximately 1,000 are in Texas and 300 in New Mexico. There are 32 geologic plays that have been defined for Permian Basin oil reservoirs, and each of the 1,300 major reservoirs was assigned to a play. The reservoirs were mapped and compiled in a Geographic Information System (GIS) by play. The final reservoir shapefile for each play contains the geographic location of each reservoir. Associated reservoir information within the linked data tables includes RRC reservoir number and district (Texas only), official field and reservoir name, year reservoir was discovered, depth to top of the reservoir, production in 2000, and cumulative production through 2000. Some tables also list subplays. Play boundaries were drawn for each play; the boundaries include areas where fields in that play occur but are smaller than 1 MMbbl (1.59 x 10{sup 5} m{sup 3}) of cumulative production. Oil production from the reservoirs in the Permian Basin having cumulative production of >1 MMbbl (1.59 x 10{sup 5} m{sup 3}) was 301.4 MMbbl (4.79 x 10{sup 7} m{sup 3}) in 2000. Cumulative Permian Basin production through 2000 was 28.9 Bbbl (4.59 x 10{sup 9} m{sup 3}). The top four plays in cumulative production are the Northwest Shelf San Andres Platform Carbonate play (3.97 Bbbl [6.31 x 10{sup 8} m{sup 3}]), the Leonard Restricted Platform Carbonate play (3.30 Bbbl [5.25 x 10{sup 8} m{sup 3}]), the Pennsylvanian and Lower Permian Horseshoe Atoll Carbonate play (2.70 Bbbl [4.29 x 10{sup 8} m{sup 3}]), and the San Andres Platform Carbonate play (2.15 Bbbl [3.42 x 10{sup 8} m{sup 3}]). Detailed studies of three reservoirs are in progress: Kelly-Snyder (SACROC unit) in the Pennsylvanian and Lower Permian Horseshoe Atoll Carbonate play, Fullerton in the Leonard Restricted Platform Carbonate play, and Barnhart (Ellenburger) in the Ellenburger Selectively Dolomitized Ramp Carbonate play. For each of these detailed reservoir studies, technologies for further, economically viable exploitation are being investigated.

Shirley P. Dutton; Eugene M. Kim; Ronald F. Broadhead; Caroline L. Breton; William D. Raatz; Stephen C. Ruppel; Charles Kerans

2004-01-13

79

Irradiation of quartz grains - a new method of sedimentological analysis applied to Permian - Carboniferous arenites in the Maranhao Basin - Brazil  

International Nuclear Information System (INIS)

The quartz grains of sediments and sedimentary rocks change their colour in variable intensity to smoky-quartz by X-ray irradiation, Co60 or in reactors, dependent on their temperature of cristallization. The quantity of quartz grains which were stained and which were not stained after being irradiated are related to rock types from the source areas. This method was applied for selected sandstones of different stratigraphical levels of the Permian-Carboniferous in the Maranhao Basin of Brazil. Studeis on heavy minerals of these sandstones have been done before. The heavy mineral associations of the Permian Pedra de Fogo Formation corroborate the results of the analysis of quartz grains which indicate a predominance of the metamorphic rocks in the source area. However, the heavy mineral parageneses of the Carboniferous Piaui Formation are different. This may be because the frequency of those heavy minerals depend directly on the stage of the weathering of the sandstones. It should be mentioned that heavy minerals occur in paleozoic sediments only in a small quantity, sometimes below 1% of the rock constitution. The irradiation analysis, which is applied for the predominant mineral in sandstones, appears to be most reliable. It is used here as the basis for the interpretations presented. (Author)

80

Progress on the palynostratigraphy of the Permian strata in Rio Grande do Sul State, Paraná Basin, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available A review of published papers and results of analysis of new material have allowed improvements on the palynostratigraphy of the Permian strata of the Paraná Basin in Rio Grande do Sul State. Based on first and last occurrences of certain species of pollen taxa, two palynozones are formalized, these are the Vittatina costabilis and Lueckisporites virkkiae Interval Zones, in ascending order. The Vittatina costabilis Interval Zone is subdivided into two units, in ascending order the Protohaploxypinus goraiensis and the Hamiapollenites karrooensis Subzones, and is recognized from the glacial (Itararé Group and post-glacial sequence (Rio Bonito Formation and the base of the Palermo Formation. The Lueckisporites virkkiae Interval Zone occurs from the uppermost Rio Bonito Formation, through the Palermo and Irati formations, and into the Serra Alta and Teresina formations. The main characteristics and reference sections are established, as well as additional criteria to recognize biostratigraphical units, in accordance with the International Stratigraphic Guide. Palynostratigraphical correlation suggests that the Vittatina costabilis Zone concerns the Early Permian (early Cisuralian, while the Lueckisporites virkkiae is regarded as late Early Permian to early Middle Permian (late Cisularian to early Guadalupian.Com base na distribuição de grãos de pólen, duas unidades palinobioestratigráficas são formalisadas para o Permiano da Bacia do Paraná no Rio Grande do Sul. As unidades correspondem, da base para o topo, às zonas de intervalo Vittatina costabilis e Lueckisporites virkkiae, sendo a primeira subdividida em duas subzonas: Protohaploxypinus goraiensis e Hamiapollenites karrooensis. A primeira zona é considerada eopermiana (Eo a Mesocisuraliano, tendo sido detectada junto à seqüência glacial e pós-glacial referente ao Grupo Itararé e Formação Rio Bonito, abrangendo ainda porções inferiores da Formação Palermo. A Zona Lueckisporites virkkiae, considerada neo-eopermiana a mesopermiana (neocisuraliana a eoguadalupiana, ocorre nas formações Palermo e Irati, podendo ainda ser estendida a estratos mais superiores da bacia (formações Serra Alta e Teresina. Suas principais características e seções de referência são apresentadas, bem como outros critérios requeridos pelo Código Estratigráfico Internacional na proposição de unidades bioestratigráficas.

Paulo A. Souza

2005-06-01

81

Thermochronological Constraints on Detrital Sediments of the Late Permian Karoo Basin: Insights Into Uplift History of the Cape Fold Belt  

Science.gov (United States)

The Karoo Basin and its equivalents cover most of southern Africa, with correlative basins found also in South America. The vast geographic expanse of these basins indicates a common history of deposition along the active Panthalassan margin of southern Gondwana. The early Paleozoic history of the Karoo Basin is marked by early glacio-marine to later shallow marine-deltaic sedimentation with a final shift to a continental setting by the late Permian. In South Africa, this transition to a fluvial environment is defined by the deposition of the Beaufort Group, a ca. 5 km thick sequence of meandering river channel sandstones and muddy overbank deposits. We have identified an 800 m thick sequence of the lowermost Beaufort Group where magnetostratigraphy and U-Pb dating of zircon in volcanic tuffs establish a depositional age of 264-268 Ma. Detrital zircon from sandstone samples were dated by U-Pb SHRIMP, revealing age populations typical of the cratonic/metamorphic provinces of the Kalahari craton (Kaapval and Namaqua-Natal provinces) as well as late Paleozoic magmatic zircons probably from southern South America. Populations of detrital muscovite dated using the 40Ar/39Ar step-heating technique are dominated by a tight cluster of ca. 272 Ma cooling ages, indicating rapid exhumation of the tectonically active Cape Fold belt and short lag times (4-8 Ma) for detritus deposited into the Karoo foreland basin, similar to rates observed for modern sediments of Himalayan-draining rivers. Ongoing work will reveal whether the Cape Belt is the source for the sediments of the Karoo foreland basin.

Tohver, E.; Arosio, R.; Schmieder, M.; Jourdan, F.; Wilson, A.; Flint, S.

2012-12-01

82

Lower Permian facies of the Palo Duro Basin, Texas: depositional systems, shelf-margin evolution, paleogeography, and petroleum potential  

Energy Technology Data Exchange (ETDEWEB)

A Palo geological study suggests that potential hydrocarbon reservoirs occur in shelf-margin carbonates, delta-front sandstones, and fan-delta arkoses. Zones of porous (greater than 10 percent) dolomite are concentrated near shelf margins and have configurations similar to productive Lower Permian shelf-margin trends in New Mexico. Delta-front sandstones (log-computed porosity of 18 to 25 percent) are similar to producing deltaic sandstones of Morris Buie-Blaco Fields in North-Central Texas. Porous (18 percent) fan-delta sandstones along the south flank of the Amarillo Uplift may form reservoirs similiar to that of the Mobeetie Field on the north side of the Amarillo Uplife in Wheeler County, Texas. Potential hydrocarbon source beds occur in slope and basinal environments. Total organic carbon generally ranges from 1 to 2.3 percent by weight and averages 0.589 percent by weight.

Handford, C.R.

1980-01-01

83

The Permian Whitehill Formation (Karoo Basin, South Africa): deciphering the complexity and potential of an unconventional gas resource  

Science.gov (United States)

A key energy policy objective of the South African government is to diversify its energy mix from coal which constitutes 85% of the current mix. Gas will play a key role in the future South African economy with demand coming from electricity generation and gas-to-liquids projects. A study on world shale reserves conducted by the Energy Information Agency (EIA) in 2011 concluded that there could be as much as 485 Tcf recoverable reserves of shale gas in the South African Karoo Basin. However, the true extent and commercial viability is still unknown, due to the lack of exploration drilling and modern 3D seismic. The present study compiles existing data from literature review and new data from outcrop analogue studies on the Permian Whitehill Formation, the main target formation for future shale gas production, including thickness, depth, maturity, TOC, lithologies, sedimentary and organic facies, and dolerite occurrence to provide a first reference dataset for further investigations and resource estimates.

Götz, Annette E.

2014-05-01

84

Environmental characterization of bedded salt formations and overlying areas of the Permian Basin  

International Nuclear Information System (INIS)

This report constitutes one input to the first stage of site qualification studies. It presents a general environmental characterization of the region that is underlain by the Permian bedded salt formation. The formation covers portions of Colorado, Kansas, New Mexico, Oklahoma, and Texas. The Permian bedded salt formation is one of a number of deep, stable geologic formations being studied for potential locations for nuclear waste repositories. These studies will not necessarily lead to selection of a site. They are intended only to provide information necessary to evaluate the suitability of locations for repositories. The report is intended as a general characterization of the existing environmental setting of the Permian Region with emphasis on land, water, and air characteristics; resources; plant and animal life; and man's organizations and activities. The report provides background information about the role that this regional study will play in the overall plan for environmental impact assessments and statements deemed necessary as input to the decision-making process. Background information on the present concept of nuclear waste repository design and function is also included. The information presented in this report has been summarized from open literature readily accessible to the public. No field work was conducted nor new data used in developing the descriptions contained herein

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Paleoenvironmental reconstitution of Motuca and Sambaíba formations, Permian-Triassic of the Parnaíba Basin in southwest Maranhão state, Brazil  

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Full Text Available The interval between the Late Paleozoic and Early Mesozoic was marked by paleogeographic and paleoclimatic global changes, partly attributed to catastrophic events. The intense continentalization of the supercontinent Pangaea of End-Permian propitiated the development of extensive deserts that succeeded the coastal and platform environments of Early Permian. The records of these events in northern Brazil are found in intracratonic basins, particularly in the Permo-triassic succession of the Parnaíba Basin. The facies and stratigraphic outcrops analysis of this succession allowed the individualization of 14 sedimentary facies grouped into four facies associations (FA: FA1 and FA2 related to deposits of Motuca Formation and, FA3 and FA4, representative of the base of Sambaíba Formation. The FA1 – Shallow lake/Mudflat consists of red laminated mudstone with lenses of gypsum, calcite and marl, besides lobes of sigmoidal sandstones. The FA2 – Saline pan consists of lenticular bodies of laminated gypsum, nodular gypsum and gypsarenite, overlapped by greenish mudstones with dolomite nodules and palygorskite. The FA3 – sand sheet and FA4 – dunes field are formed, respectively, for orange cream sandstones with even parallel stratification and medium- to large-scale cross-bedding. In the contact between Motuca and Sambaíba formations occurs a deformed interval, laterally continuous for hundreds of kilometers. Brecciated and contorted bedded siltstones and mudstone (Motuca Formation and sandstone with sinsedimentary faults/microfaults, convolute lamination and mud-filled injection dykes (Sambaíba Formation are interpreted as seismites triggered by high magnitude earthquakes (> 8 according Richter scale.

Francisco Romério Abrantes Júnior

2013-09-01

86

A brief lithostratigraphic review of the Abrahamskraal and Koonap formations of the Beaufort Group, South Africa: Towards a basin-wide stratigraphic scheme for the Middle Permian Karoo  

Science.gov (United States)

The basal strata of the Beaufort Group of the South African Karoo Basin, comprising the western Abrahamskraal and eastern Koonap formations, contain the most time extensive record of Middle Permian fossil tetrapods and hold the key to understanding Middle Permian biodiversity change in the continental realm. To determine faunal stratigraphic ranges a reliable lithostratigraphic framework for Middle Permian Beaufort deposits is essential. Until now this has proved difficult to achieve, largely due to the homogeneity of the fluvial succession coupled with structural complexity as a result of Cape Fold Belt orogenesis. Accordingly, the Abrahamskraal Formation has been only locally subdivided on the basis of sandstone packages but regional stratigraphic subdivision has not yet achieved satisfactorily. Collation of stratigraphic sections from around the Karoo Basin for this study demonstrates the presence of four sandstone packages are present within the Abrahamskraal Formation in the south-western corner of the basin. These sandstone packages are given member status, based upon the nomenclature of Le Roux (1985) with the addition of the newly recognised Grootfontein Member. The Combrinkskraal and Grootfontein Members occur in the lower half of the Abrahamskraal Formation and are laterally persistent along the southern margin of the basin. The Koornplaats Member is more restricted to the south west corner of the basin, where it quite thick, suggesting the narrowing of the highly channelized area. The overlying Moordenaars Member, more extensive towards the north than underlying packages, indicates subsequent northwesterly expansion of the locus of active channelization with time. Although thin sandstone packages in the more easterly positioned and stratigraphically equivalent Koonap Formation, this does not facilitate lithostratigraphic subdivision of this part of the stratigraphic succession and may indicate a different form of fluvial architecture. Our study provides a regional lithostratigraphic scheme for the Abrahamskraal Formation that will facilitate its biostratigraphic subdivision and the investigation of Middle Permian Gondwanan basin evolution.

Day, Michael Oliver; Rubidge, Bruce Sidney

2014-12-01

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Morphology, intersections, and syn/late-diagenetic origin of vein networks in pelites of the Lodève Permian Basin, Southern France  

Science.gov (United States)

This paper presents the results of a field study aiming to describe and to interpret new types of relationships between vein sets. Three vein sets of the Lodève Permian Basin (Languedoc, Southern France) were studied. They consist of a family of N100E-N120E, widely opened sinuous veins with a composite infilling (sparite, calcite fibres, barite), hereafter called Sparitic Sinuous Veins, and of two orthogonal families of slim veins presenting a fibrous infilling of calcite, and oriented N10E-N20E and N90E-N100E, respectively. These two latter families are hereafter called N20 Fibrous Slim Veins and N90 Fibrous Slim Veins. The intersections between the three vein sets are shown to be original and more complex than those classically observed in the case of joint sets (abutting, crosscutting, …). The analysis of these intersections permitted a relative chronology of formation of the different vein sets to be established: the N20 Fibrous Slim Veins post-date the N90 Fibrous Slim Veins, which themselves post-date the Sparitic Sinuous Veins, the two former vein sets being shown to reopen contemporaneously. Furthermore, the vein intersections were not as simple as expected. Indeed, the successive propagating cracks of one set could in certain cases crosscut the pre-existing veins of an earlier set, or could be stopped at contact with earlier veins in other cases. This implies a physical change in the interface between the pre-existing veins and the host rock (pelites) during the formation of the latest cracks. Taking into account the well-known tectonic history of the Lodève basin, and the field observations (vein features, intersections, …), the origin of each vein set is discussed. We put forward that the Sparitic Sinuous Veins formed during the burial history of the basin: their morphological characteristics suggest that they appeared during the phase of active compaction of the basin, in response to the Permo-Triassic NS extension, and that their formation was assisted by fluid pressure. Second, we propose that the two orthogonal sets of Fibrous Slim Veins formed during the same extensional phase, their formation being favoured by the tectonic relaxation occurring at the beginning of the uplift of the basin at the end of the Permian. We attribute their particular characteristics (straight morphology of joints but systematic mineral infilling) to their origin in a medium already compacted but still incompletely lithified, and containing a large amount of fluids. We suggest that the fracturing history of the Lodève basin occurred in the time interval between the Late Permian (Thuringian) and the Middle Triassic (Anisian). Finally, the observed evolution in the propagation path between the Sparitic Sinuous Veins and the N90 Fibrous Slim Veins is discussed, and bears out the idea that the rock material was not completely lithified when the vein sets formed.

de Joussineau, Ghislain; Bazalgette, Loïc; Petit, Jean-Pierre; Lopez, Michel

2005-01-01

88

The geology petrology, palynology and geochemistry of Permian coal basins in Tanzania. 1. Namwele-Mkomolo, Muze and Galula coalfields  

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Permian coal-bearing strata occur in a number of intracratonic rift basins in Tanzania. This study examines coals, shales and mudstones of the Namwele-Mkomolo, Muze and Galula coalfields (Rukwan basin) by coal petrological, palynological and rock eval techniques. For the coals the focus was on the establishment of coal seam characteristics and related quality and utilization potentials, whereas the shales and mudstones were examined for age relationships, flora and related palaeodepositional environments and source rock potential. The coal seams, which have a thickness of up to 2.95 m are high in ash and have calorific values ranging from 5344 to 18947 J/g. Many seams are detrital with a high content finely disseminated clay minerals, quartz and detrital macerals. Pyrite content is variable. Vitrinite reflectance ranges from 0.43 to 0.66% R{sub random}. Use of the coals in small-scale power generation and for domestic use would greatly reduce the dependency of rural Tanzania on wood and wood-derived charcoal. Palynomorph assemblages are characterized by the predominance of nontaeniate and taeniate pollen, and trilete spores in the Namwele-Mkomolo and Muze coalfields. At Galula coalfields the palynomorph assemblages were poor. On the basis of age correlations with Karoo basins to the south and the Collie Basin of western Australia, an Artinskian to Kungurian (?) age is suggested for the coal measures in the Rukwa basin. The diversity of palynomorph assemblages suggests a variety of floras and contemporary depositional environments. This is consistent with coal petrography indicating that peat accumulation occurred in upper delta plain, braided plan and lacustrine depositional environments. Rock eval parameters indicate koergen type III for all samples investigated and indicate very poor hydrocarbon source rock potential. 59 refs., 17 figs., 6 plates, 3 tabs.

Semkiwa, P.; Kalkreuth, W.; Utting, J.; Mayagilo, F.; Mpanju, F.; Hagemann, H. [Tanzania Ministry of Water, Energy and Minerals, Dodoma (Tanzania)

1998-03-01

89

Thermal and cementation histories of Permian shelf-edge carbonate rocks in the Nanpanjiang Basin, South China  

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As of 1984, the Nanpanjiang Basin of South China has had almost no exploration by drilling although oil seeps exist among its margins and producing wells occur in adjacent basins.  however, cooperative studies by petroleum geologists and geochemists of the United States and the People's Republic of China (1982-1984) show that calcite-cemented reef and fore-reef carbonate rocks near Ziyun contain bitumen in Upper Permian shelf-edge sediment.  the cementation history consists of three episodes: (1)precipitation of syndepositional marine cement (formerly botryoidal aragonnite and fibrous magnesian calcite); (2)precipitation of post-depositional early cement (radiaxial calcite); and (3)precipitation of late burial cement (white calcite spar).  Hydrocarbons were introduced into the rocks between cementation episodes 2 and 3.  Fluid inclusion analysis of secondary inclusions in the burial cement indicates that the rocks were heated to nearly 200 C after hydrocarbon migration and cementation episode 3.  Bitumen remains in the rocks as evidence of the earlier presence of liquid hydrocarbons.

Halley, Robert B.; Parrish, Judith T.; Zahn, Xie; Wenhai, Hu; Scholle, Peter A.; Zhongrui, Su; Yirong, Zhang; Yunming, Huang; Guangxuan, Li

1989-01-01

90

Dissolution of salt on the east flank of the Permian Basin in the southwestern U.S.A.  

Science.gov (United States)

Hydrogeologic studies prove that natural dissolution of bedded salt occurs at shallow depths in many parts of the Permian Basin of the southwestern U.S.A. This is especially well-documented on the east side of the basin in study areas on the Cimarron River and Elm Fork in western Oklahoma, and on the Red River in the southeastern part of the Texas Panhandle. Four requirements for salt dissolution are: (1) a deposit of salt; (2) a supply of water unsaturated with respect to NaCl; (3) an outlet for removal of brine; and (4) energy to cause water to flow through the system. The supply of fresh groundwater in the region is recharged through permeable rocks, alluvium, terrace deposits, karstic features and fractures. Groundwater dissolves salt at depths of 10-250 m, and the resulting brine moves laterally and upward under hydrostatic pressure through caverns, fractures in disrupted rock, and clastic or carbonate aquifers until it reaches the land surface, where it forms salt plains and salt springs. In many areas, salt dissolution produces a self-perpetuating cycle: dissolution causes cavern development, followed by collapse and subsidence of overlying rock; then the resulting disrupted rock has a greater vertical permeability that allows increased water percolation and additional salt dissolution.

Johnson, Kenneth S.

1981-12-01

91

Origin, distribution, and movement of brine in the Permian Basin (U.S.A.). A model for displacement of connate brine  

International Nuclear Information System (INIS)

Na-Cl, halite Ca-Cl, and gypsum Ca-Cl brines with salinities from 45 to >300 g/L are identified and mapped in four hydrostratigraphic units in the Permian Basin area beneath western Texas and Oklahoma and eastern New Mexico, providing spatial and lithologic constraints on the interpretation of the origin and movement of brine. Na-Cl brine is derived from meteoric water as young as 5-10 Ma that dissolved anhydrite and halite, whereas Ca-Cl brine is interpreted to be ancient, modified-connate Permian brine that now is mixing with, and being displaced by, the Na-Cl brine. Displacement fronts appear as broad mixing zones with no significant salinity gradients. Evolution of Ca-Cl brine composition from ideal evaporated sea water is attributed to dolomitization and syndepositional recycling of halite and bittern salts by intermittent influx of fresh water and sea water. Halite Ca-Cl brine in the evaporite section in the northern part of the basin differs from gypsum Ca-Cl brine in the south-central part in salinity and Na/Cl ratio and reflects segregation between halite- and gypsum-precipitating lagoons during the Permian. Ca-Cl brine moved downward through the evaporite section into the underlying Lower Permian and Pennsylvanian marine section that is now the deep-basin brine aquifer, mixing there with pre-existing sea water. Buoyancy-driven convection of brine dominated local flow for most of basin history, with regional advection governed by topographically related force governed by topographically related forces dominant only for the past 5 to 10 Ma. 71 refs., 11 figs

92

Volcanic relicts in the permian-filled deposits of the Lodeve basin: metallogenic occurrences. Reliques volcaniques dans le remplissage permien du bassin de Lodeve. Incidence metallogenique  

Energy Technology Data Exchange (ETDEWEB)

Petrographical and mineralogical studies of the various lithological Permian facies of the uraniferous Lodeve basin show evidence of volcanic activity, as witnesses by the existence of pumices, shards, perlites particularly in sedimentary formations of the Upper Thuringian where volcanism has not been described so far. Major and trace chemistry of the most inert elements contributing towards alteration and diagenesis confirm the volcanic contribution to the sedimentation.

Nmila, A.; Cabanis, B.; Treuil, M. (Paris-6 Univ., 75 (FR) Laboratoire d' Analyse par Activation Pierre Sue, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur Yvette (FR)); Dardel, J. (CEA, 75 - Paris (FR)); Saint Martin, J. (Compagnie Generale des Matieres Nucleaires (COGEMA), 34 - Lodeve (FR))

1989-12-01

93

A sedimentological analysis of sediments corresponding to the San Gregorio Formation )Lower Permian), located in the eastern border of the North Uruguayan Basin, Sierra Guazunambi  

International Nuclear Information System (INIS)

A sedimentological analysis of sediments corresponding to the San Gregorio Formation (Lower Permian), located in the eastern border of the Norte Uruguayan Basin, Sierra Guazunambi, Cerro Largo Departament was made. Facies analysis of about 100 otucrops fand more than 1.300 meters, in an area of 45 square kilometers showed diamictites rhytmites and massive sandstones, formed by gravitational sedimentary flows. Also present are prodelta mudrocks and deltaic front sandstones.(author)

94

Fluvial architecture as a response to two-layer lithospheric subsidence during the Permian and Triassic in the Iberian Basin, eastern Spain  

OpenAIRE

The stratigraphy of a sedimentary basin is mainly the result of the long-term response of a depositional surface to prolonged subsidence. However, the real nature of interrelations between fluvial architecture and subsidence is still unknown. Herein, we present new data on these relationships by combining the results of detailed sedimentological field work with data acquired through automated forward modelling and backstripping for the alluvial Permian and Triassic sediments of th...

Lo?pez Go?mez, Jose?; Arche, Alfredo; Vargas Herna?ndez, Henar Mari?a; Marzo Carpio, Mariano

2010-01-01

95

Permian rhyolitic volcanism, changing from subaqueous to subaerial in post-Variscan intra-continental Sirinia Basin (SW Romania-Eastern Europe)  

Science.gov (United States)

The Sirinia Basin is a well-exposed, Upper Carboniferous-Lower Permian intra-continental extensional basin, containing 1-2 km of Permian interbedded terrigeneous sediments and primary volcanic and volcaniclastic rocks of rhyolitic composition. These are mostly the products of subaqueous volcanism passing into a subaerial volcanism. The intra-continental basin lies on the Danubian metamorphic units in the south westernmost part of the Carpathians (SW Romania) and is N-S oriented (18 × 8 km), as result of Alpine tectonic evolution and deformation. The Sirinia Basin setting formed a dynamic closed intra-continental sedimentary system that experienced a successive subsidence; it started with lacustrine sediments and then with large volumes of rhyolitic volcanic and volcaniclastic material dominantly sited in the central part of the basin. Volcanism included (1) subaqueous extrusion of domes surrounded by hyaloclastite deposits closely associated with secondary sedimentation, (2) extrusive and explosive Surtseyan-type and subaerial eruptions from shallow water to emergent volcanoes on dome-cap and associated reworked deposits, towards the southern side of the basin, and (3) subaerial extrusive domes. Fluvial erosion and deposition completed the evolution of the emerged marginal part of the basin. Most of the erupted material of the first and second phase filling the central part of the basin along extensional normal faults was rapidly transported on sides of the basin by turbidite sedimentation, debris flows, slumping and sliding. While turbidites prevail toward the central part of the basin, the debris flow sedimentation predominated at the margin of the basin, infrequently interrupted by deposition of fallout ash from hydromagmatic explosive eruptions related to the dome-cap tuff and pumice cones.

Seghedi, Ioan

2011-04-01

96

Permian to Late Triassic evolution of the Longmen Shan Foreland Basin (Western Sichuan): Model results from both the lithospheric extension and flexure  

Science.gov (United States)

The lithosphere was extended during the Permian-Middle Triassic in the Yangtze Craton where the Sichuan Basin located, and then bent due to thrusting of the Longmen Shan orogen, leading to formation of the Longmen Shan Foreland Basin (Western Sichuan) during the Late Triassic Indosinian orogeny. The lateral variation of the lithospheric strength resulted by former differential extension would inevitably influence the subsequent evolution of the foreland basin. In order to investigate this, both extensional and flexural models were applied in modeling Permian-Late Triassic basin evolution. A 2D kinematic extensional model was initially developed along a profile crossing the Yangtze Craton to simulate the lithospheric thermal evolution during the Permian-Middle Triassic. Based on the thermal results, the thermal-rheological structure, as well as the effective elastic thickness of the lithosphere (Te), was then determined. Extension model show that the stretching factors decrease gradually from Songpan-Ganzi to the Sichuan Basin, leading to variable thermal-rheological structure and increased Te from west to east. Taking into account of the Te variation, a flexural model was finally constructed to investigate the evolution of the Longmen Shan Foreland Basin during the Late Triassic spanning the time period c. 227-206 Ma. Three episodes were divided according to the corresponding tectonostratigraphic units. By matching the stratigraphic observations, three phase advance distances eastward of the Longmen Shan along the Qingchuan-Maowen Fault turned out to be 18, 22, and 18 km. It implied a slow and similar thrust advance rate of 3.6 (c.227-222 Ma), 2.2 (c.222-212 Ma), and 3 mm/yr (c.212-206 Ma), respectively.

He, Lijuan

2014-10-01

97

Preliminary study of uranium in Pennsylvanian and lower Permian strata in the Powder River Basin, Wyoming and Montana, and the Northern Great Plains  

International Nuclear Information System (INIS)

Persistent and widespread radiometric anomalies occur in Pennsylvanian and Lower Permian strata in the subsurface of the northern Great Plains and the Powder River Basin. The primary host lithology of these anomalies is shale interbedded with sandstone, dolomite, and dolomitic sandstone. Samples from the project area indicate that uranium is responsible for some anomalies. In some samples there seems to be a correlation between high uranium content and high organic-carbon content, which possibly indicates that carbonaceous material acted as a trapping mechanism in some strata. The Pennsylvanian and Permian rocks studied are predominantly marine carbonates and clastics, but there are rocks of fluvial origin in the basal Pennsylvanian of Montana, North Dakota, and South Dakota and in the Pennsylvanian and Permian deposits on the east flank of the Laramie Mountains. Fine-grained clastic rocks that flank the Chadron arch in western Nebraska are possibly of continental origin. The trend of the Chadron arch approximately parallels the trend of radiometric anomalies in the subsurface Permian-Pennsylvanian section. Possible source areas for uranium in the sediments studied were pre-Pennsylvanian strata of the Canadian Shield and Precambrian igneous rocks of the Ancestral Rocky Mountains

98

Palynology of the Permian San Miguel Formation (Western Paraná Basin, Paraguay): Gondwanan biostratigraphic correlations  

OpenAIRE

The palynological analysis of five samples from three levels in cores of the Mallorquín-1 well (Paraná Basin, eastern Paraguay) is presented here. The borehole penetrated the San Miguel Formation, the basal lithostratigraphic unit of the Independencia Group. This palynoflora represents the westernmost palynological record reported from Upper Paleozoic sequences along this basin margin at this latitude. This diverse spore-pollen flora includes several age marker taxa, viz. Verrucosisporites ...

Pe?rez Loinaze, V. S.

2010-01-01

99

Post-Variscan (end Carboniferous-Early Permian) basin evolution in Western and Central Europe  

OpenAIRE

The Variscan orogeny, resulting from the collision of Laurussia with Gondwana to form the supercontinent of Pangaea, was followed by a period of crustal instability and re-equilibration throughout Western and Central Europe. An extensive and significant phase of Permo-Carboniferous magmatism led to the extrusion of thick volcanic successions across the region (e.g. NE German Basin, NW part of the Polish Basin, Oslo Rift, northern Spain). Coeval transtensional activity led to the formation of ...

 mccann, T.;  pascal, C.;  timmermann, M. J.;  krzywiec, P.;  lopez-gomez, J.;  wetzel, A.;  krawczyk, C. M.;  rieke, H.;  lamarche, J.

2006-01-01

100

Dispersal syndromes of fossil seeds from the Lower Permian of Paraná Basin, Rio Grande do Sul, Brazil.  

Science.gov (United States)

The morphological analysis of seeds has been an important subject in modern ecological studies, once it provides evidence about the biology and adaptations of the parent plant. However, this kind of study has been restricted to the ecology of modern plants and is rarely used in interpretations of Paleozoic data. From the understanding of dispersal syndromes analysis as an important tool to paleoecological reconstruction, this study provides a first approach using this tool with seeds from the Lower Permian strata of southern Paraná Basin in Rio Grande do Sul. Based on previously classified seeds and using their biological and taphonomic data, the syndrome of dispersal was interpreted, and their placement in successional groups (pioneer, early-successional and later-successional) was suggested. Seven morphospecies were analyzed: Samaropsis gigas, representing a later-successional species living in water bodies with hydrochory as its dispersal syndrome; Samaropsis kurtzii, typical of early-successional species showing anemochory as its dispersal syndrome and living in distal areas in relation to water bodies; Samaropsis aff. S. millaniana, Cordaicarpus aff. C. brasilianus, Cordaicarpus cerronegrensis and Cordaicarpus truncata have typical characteristics of pioneer plants, exhibiting barochory as their primary dispersal syndrome with other syndromes associated. PMID:22441595

Souza, Juliane M; Iannuzzi, Roberto

2012-03-01

101

Ichnology of the non-marine deposits of the Boskovice Basin (Carboniferous-Permian, Czech Republic  

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Full Text Available In the area of the Boskovice Basin, simple ichnoassemblages and ichnofabric patterns characterize a suite of lacustrine and fluvial deposits. The succession of ichnofabrics enables us to correlate several sections in the northern part of the basin, supporting the correlation of the previously recognized Ba?ov, Míchov and Obora horizons. The mostly finegrained lacustrine deposits below bituminous limestones contain Planolites beverleyensis, Planolites montanus, amphibian footprints, and rare Cruziana problematica. Reddish sandstones, which can be interpreted as alluvial plain deposits, contain Planolites, Scoyenia, 'star-like traces', and Diplocraterion. In the southern part of the basin, the coal-bearing strata are characterized by generally poor bioturbation, with isolated levels of 'root spots' and Planolites. The lowermost strata of the overlying red-bed unit show intensive and rhythmical Planolites ichnofabric, the intensity and uniformity of which decrease upwards.

Mikuláš R

2006-03-01

102

Controls of alluvial stratigraphy in the Upper Pennsylvania-Lower Permian Dunkard Basin  

Energy Technology Data Exchange (ETDEWEB)

The Casselman, Pittsburgh, and Waynesburg formations exposed in northern West Virginia were deposited within a foreland basin adjacent to the Alleghenian fold and thrust belt. Sandstones were deposited in fluvial channels on an aggrading and prograding coastal plain. however, unlike mid-continental cyclothems, these channels were isolated from eustatic changes because previous delta progradation had blocked circulation between the local depositional basin and the larger mid-continental sea. Thus, eustatic changes had no direct or strong influence on Dunkard basin deposition, a conclusion supported by interbasinal correlation. Also, climate was largely stable during this interval. The evolution of channel properties, therefore, most likely reflects the influence of intrabasinal controls and possibly tectonism. Detailed correlation indicates that coeval channel belts were separated by about 50 km with an intervening area of slower subsidence and deposition. Quantitative reconstruction of bankfull hydraulics and geometry indicates that channels were of moderate sinuosity, were not braided, and were of two distinct sizes (average widths, 80 and 250 m, respectively). An overall decrease in discharge in the smaller channels throughout the studied interval may be attributed to a slowing of subsidence rates as the locus of sedimentation prograded beyond the northwestern margin of the Rome Trough or to thrustward migration of a forebulge following episodic thrusting. The increase in size and discharge of channels in the uppermost Waynesburg Formation is attributed to progradation of the upper fluvial-deltaic plain over the lower fluvial-deltaic plain, a progradation that may likewise have been promoted by thrusting.

Dominic, D.F. (Wright State Univ., Dayton, OH (United States))

1991-08-01

103

Radiometric dating of ochoan (permian) evaporites, WIPP site, Delaware basin, New Mexico, USA  

International Nuclear Information System (INIS)

The authors have attempted radiometric dating of halide-sulfate salts and clay minerals from the Delaware Basin, New Mexico, USA, as part of geochemical study of the stability of the evaporite sequence at the WIPP (Waste Isolation Pilot Plant - a US DOE facility) site. They undertook this dating to determine: (1) primary age of evaporite genesis or time(s) of recrystallization, (2) if previously undated evaporite minerals (leonite, polyhalite, kieserite) give useful data, and (3) if the detrital clay minerals have been radiometrically reset at any time following their incorporation into the evaporite medium. They have shown earlier that polyhalites can indeed be successfully dated by the K-Ar method, and once corrections are applied for admixed halide minerals, dates of 210-230 Ma for the Delaware Basin are obtained. Rb-Sr isochrons from early stage sylvites-polyhalites-anhydrites yield 220 +/- 10 Ma, even when some sylvites yield lower K-Ar dates due to loss of 40Ar*. K-Ar dates on leonites and kieserites are also low due to 40Ar* loss, but their Rb-Sr dates are higher. Detrital clay minerals from the Delaware Basin collectively yield a highly scattered isochron (390 +/- 77 Ma), but samples from a local area, such as the WIPP Site, give a much better age of 428 +/- 7 Ma. These dates show that the interaction between the clay minerals and the evaporitic brines was insufficient to reset the clay minerals Rb-Sr systematics. In a related study, theyb-Sr systematics. In a related study, they note that a dike emplaced into the evaporite at 34 Ma had only very limited effect on the intruded rocks; contact phenomena were all within 2 m of the dike. All of their geochemical (radio-metric and trace element) studies of the WIPP site argue for preservation of the isotopic and chemical integrity of the major minerals for the past 200 Ma. 19 references, 1 figure, 5 tables

104

Coricladus quiteriensis gen. et sp. nov., a new conifer in Southern-Brazil Gondwana (Lower Permian, Paraná Basin)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Um novo taxon de coníferas (Coricladus quiteriensis) é descrito a partir de fragmentos de megafósseis vegetais do nível de roof-shale do Afloramento Quitéria (Formação Rio Bonito - Permiano Inferior - Sul da Bacia do Paraná - Rio Grande do Sul - Brasil). Esta comunidade megaflorística é incluída na [...] Zona Botrychiopsis - Sub-Zona Botrychiopsis valida (Kunguriano/Roadiano). A assembléia, preservada sob forma de impressões, não apresenta registros de caracteres epidérmicos, e é composta por ramos vegetativos isolados, portando folhas aciculares dispostas helicoidalmente, as quais possuem uma nervura central conspícua. Além disso, são registrados ramos férteis com folhas esparsas e irregulares e cones terminais. Ramos principais, áfilos, conectados organicamente a ramos vegetativos e férteis, são raros. Escamas reprodutivas femininas, dispostas em um só plano, estão organizadas em cones terminais, compostos por 4 (quatro) escamas ovulíferas e 8 (oito) sementes anátropas alongado-elípticas. Dados paleoecológicos indicaram um habitat mesófilo a higrófilo, desenvolvido em um ambiente pantanoso. Abstract in english A new taxon of conifers (Coricladus quiteriensis) is described based on megafloristic remains from the roofshale level at the Quitéria Outcrop (Rio Bonito Formation - Lower Permian - Southern Paraná Basin - Rio Grande do Sul - Brazil). This megafloristic community is included in the Botrychiopsis Zo [...] ne - Botrychiopsis valida Sub-Zone (Kungurian/Roadian). The assemblage, preserved as impressions, do not present remains of epidermic characters, and is composed mainly of isolated vegetative branches with spirally disposed acicular leaves, presenting a conspicuous central vein and also isolated fertile branches with sparse and irregular leaves and terminal cones. Leafless principal branches, organically connected with sterile and fertile branches, are rare. Reproductive feminine scales, disposed in a plane, are organized in lax terminal cones on branches, composed by 4 (four) distal ovuliferous scales, and 8 (eight) elliptical-elongated anatropous seeds. Paleoecological data pointed out to a mesophylous to higrophylous habitat in swampy environments.

André, Jasper; Fresia, Ricardi-Branco; Margot, Guerra-Sommer.

2005-03-01

105

Stratigraphy, structure, and lithofacies relationships of Devonian through Permian sedimentary rocks: Paradox Basin and adjacent areas - southeastern Utah. Technical report  

International Nuclear Information System (INIS)

Geophysical well log analysis, literature review, and field work were conducted to develop isopach, structure contour, outcrop, and facies maps and cross sections for the Devonian through Permian strata of a 14,586-km2 (5632-square-mile) area in southeastern Utah. The study area includes part of the Paradox Basin, the salt deposits of which are of interest in siting studies for a nuclear waste repository. For this reason hydrologic models of this area are needed. This study, part of which included the development of a three-dimensional stratigraphic computer model utilizing Geographic Information System software, can serve as a base for hydrologic or other models for this area. Within and adjacent to the study area, 730 wells were screened to select the 191 wells analyzed for the study. It was found that the Elbert through Molas formations did not exhibit noticeable facies changes within the study area. The Pinkerton Trail Formation exhibits moderate changes: anhydrite and shale become somewhat more abundant toward the northeast. Facies changes in the Paradox Formation are more dramatic. Thick saline facies deposits are present in the northeast, grading to thinner anhydrite and then to carbonate facies in the south and west. The lithology of the Honaker Trail Formation appears to be fairly uniform throughout the area. Facies changes in the Cutler Group are numerous and sometimes dramatic, and generally correspond to the named formations of the group. Other the named formations of the group. Other factors that could affect groundwater flow, such as stratigraphic cover of fine-grained rocks, area of formation outcrops, and fracturing and faulting are discussed and delineated on maps

106

Kinetics of evaporite mineral-brine interactions: mathematical modeling and experimental determination of the effect of gamma radiation and threshold crystallization inhibition on Permian Basin brine composition  

International Nuclear Information System (INIS)

The San Andres and Salado bedded salt formations in the evaporitic Permian Basin contain fluid phases in equilibrium with the host rock. Anthropogenic perturbations such as emplacing heat-generating high level radioactive wastes (HLW) in a mined repository mobilize this brine. Kinetic factors are of extreme importance in the precipitation and dissolution of evaporites and may govern the diagenesis of phosphate, sulfate, and chloride phases in the type of environment occurring at both the time of the original deposition of the sediment and in the very nearfield of a HLW repository. Using the computer code XLRATE, newly-formulated geometric models incorporating critical aspects of mineralogical defects and dislocations describe a wide variety of kinetic data for the dissolution of apatite and irradiated Permian Basin rock salt. The lattice damage in rock salt caused by gamma radiation increases the halite dissolution rate. The escape of chlorine gas and the radiolysis of trace impurities moves the NaCl concentration of saturated brines made from irradiated salt to lower values with Cl- decreasing to a greater extent than Na+. A new model incorporating nucleation time best describes crystallization kinetics in the calcium sulfate system. The solubilities and saturation indices of irradiated Permian Basin rock salt and calcium sulfates in brines of different ionic strengths were numerically modeled. Seventy-five naturally-occurring and commercial cryive naturally-occurring and commercial crystallization inhibitors including carboxylic acids, amino acids, carbohydrates, humic and tannic substances, and organic polyelectrolytes were tested for their effect on gypsum/anhydrite and rock salt precipitation and dissolution. Of these, 70% proved relative or very effective

107

Temporal and spatial variations in tectonic subsidence in the Iberian Basin (eastern Spain): inferences from automated forward modelling of high-resolution stratigraphy (Permian Mesozoic)  

Science.gov (United States)

By subsidence analysis on eighteen surface sections and 6 wells, which cover large part of the Iberian Basin (E Spain) and which are marked by high-resolution stratigraphy of the Permian, Triassic, Jurassic and Cretaceous, we quantify the complex Permian and Mesozoic tectonic subsidence history of the basin. Backstripping analysis of the available high resolution and high surface density of the database allows to quantify spatial and temporal patterns of tectonically driven subsidence to a much higher degree than previous studies. The sections and wells have also been forward modelled with a new `automated' modelling technique, with unlimited number of stretching phases, in order to quantify variations in timing and magnitude of rifting. It is demonstrated that the tectonic subsidence history in the Iberian Basin is characterized by pulsating periods of stretching intermitted by periods of relative tectonic quiescence and thermal subsidence. The number of stretching phases appears to be much larger than found by earlier studies, showing a close match with stretching phases found in other parts of the Iberian Peninsula and allowing a clear correlation with discrete phases in the opening of the Tethys and Atlantic.

Van Wees, J. D.; Arche, A.; Beijdorff, C. G.; López-Gómez, J.; Cloetingh, S. A. P. L.

1998-12-01

108

Paleomagnetic and magnetostratigraphic investigations of the whitehorse group/quartermaster (Dewey Lake) formation (upper permian-lowermost triassic) in the Palo Duro basin, northwest Texas, USA  

Science.gov (United States)

In northwest Texas, upper Permian to lowermost Triassic hematite-cemented detrital sedimentary rocks, which include a small number of regionally extensive ash beds, were deposited during the time interval of the greatest mass extinction event sequences in Earth history. The magnetic polarity stratigraphy, as well as key rock magnetic properties, of the upper Whitehorse Group (WH) and Quartermaster formations (QM) at selected sections in the Palo Duro Basin, have been determined using thermal, and chemical demagnetization approaches and anisotropy of magnetic susceptibility, acquisition of isothermal remanent magnetization (IRM) and backfield demagnetization, and thermal demagnetization of three component IRM methods. Demagnetization results show that the WH/QM contains a primary/near-primary characteristic remanent magnetization at each level sampled and thus the magnetic polarity stratigraphy for each section can be compared with existing polarity time scales across the Permian-Triassic boundary. Estimated site mean directions yield a paleomagnetic pole for the latest Permian for North America of 57.8°N, 130.6°E from 38 sampled sites.

Collins, Dylan R.

109

Permian bivalves of the Taciba Formation, Itararé Group, Paraná Basin, and their biostratigraphic significance  

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Full Text Available A small and poorly diversified bivalve fauna from Taciba Formation, Itararé Group, Paraná Basin (State of Santa Catarina,Mafra Municipality, is described in this paper for the first time, based on new findings. The fauna is recorded in a 30 cmthick interval of fine sandstone locally at the top of Taciba Formation, in the Butiá quarry. The studied fossil-bearing sandstonebed is a marine intercalation recording a brief eustatic rise in sea-level, probably following glacier retreat and climateamelioration at the end of a broad glacial scenario. The fauna is mainly dominated by productid brachiopods, which are notdescribed here, and rare mollusk shells (bivalves and gastropods. Two bivalve species were identified: Myonia argentinensis(Harrington, 1955, and Aviculopecten multiscalptus (Thomas, 1928. The presence of Myonia argentinensis is noteworthysince this species is also present in the Baitaca assemblage found in marine siltstones (Baitaca assemblage of theRio do Sul Formation, cropping out at the Teixeira Soares region, Paraná State. This species is also recorded in the bivalvefauna from the Bonete Formation, Pillahinco Group, Sauce Grande Basin, Buenos Aires Province, in Argentina. Hence, themarine bivalves of the Taciba Formation are associated with the transgressive event that characterizes the Eurydesma fauna,indicating a Late Asselian-Sakmarian age for the bivalve fauna. Presence of the Myonia argentinensis megadesmid speciesreinforces the Gondwanic nature of the studied fauna.

Marcello Guimarães Simões

2012-04-01

110

Record of the genus Lycopodites in the Lower Permian of Paraná Basin, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O gênero Lycopodites, que engloba formas herbáceas de licópsidas, apresenta ampla distribuição temporal e espacial durante o Paleozóico no Hemisfério Norte, iniciando seu registro no Devoniano da Europa. Já no Paleozóico do Gondwana, até o presente momento, somente Lycopodites amazonica Dolianiti ha [...] via sido reportada para o Devoniano Médio da Amazônia (Grupo Curuá). Assim, os exemplares reportados no presente trabalho como Lycopodites sp., provenientes de rochas sedimentares do Subgrupo Itararé, SP, e Lycopodites riograndensis sp. nov., coletados na Formação Rio Bonito, RS, representam as formas férteis mais antigas registradas para o Gondwana e as primeiras a serem descritas para a Bacia do Paraná. A sua presença em camadas depositadas após o término da glaciação neopaleozóica, evidencia o ingresso de novos taxa em latitudes altas, bem como a diversidade das licópsidas presentes na Bacia, já esboçada através dos abundantes esporos associados à Classe Lycopsida presentes nas assembléias de palinomorfos. Abstract in english The genus Lycopodites, which encompasses the herbaceous forms of the lycopsids, presents broad time and spacial distribution during the Paleozoic in the Northern Hemisphere, with its initial records dating from the European Devonian. As to Gondwanan Paleozoic, to this moment, only Lycopodites amazon [...] ica Dolianiti had been reported for the Amazonian Middle Devonian (Curuá Group). Thus, the specimens reported in this study such as Lycopodites sp., coming from sedimentary rocks of the Itararé Subgroup, São Paulo State, and Lycopodites riograndensis sp. nov., collected in Rio Bonito Formation, Rio Grande do Sul, represent the oldest fertile forms recorded for Gondwana and the first ones to be described for the Paraná Basin. Its presence in layers, deposited after the end of the Neopaleozoic Glaciation, shows the appearance of new taxa in high latitudes, as well as the diversity of the lycopsids present in the Basin, previously indicated through the abundance of spores associated to the Class Lycopsida present in the palinomorphous assemblages.

Juliana, Salvi; André, Jasper; Fresia, Ricardi-Branco; Mary Elizabeth C., Bernardes-de-Oliveira; Margot, Guerra-Sommer.

2008-09-01

111

Radionuclides distribution in blooming of the permian sediments from the Irati Formation of the Parana Basin  

International Nuclear Information System (INIS)

The objective of this work is to study natural radionuclides in sedimentary rocks. The concentration of them reflects the origin of the sediments, the depositional environment as well as some mineralogical characteristics of the rock matrix, and also more recent events as weathering and erosion. Using gamma ray high resolution spectrometry, the profile of activity concentration of the natural radionuclides was assessed for 226Ra, 238U, 32Th and 40K in rocks of the Irati Formation belonging to Parana Sedimentary Basin. The samples were collected at a limestone abandoned mine, in the city of Sapopema, (PR). 24 samples were collected, eleven from the exposed vertical profile with approximately 5.50 m, whose stratigraphy is represented by an alternation among decimetrics layers of limestones, bituminous shales, and some rhythmits layers (milimetric sheets of limestone and bituminous shales), 9 repetitions of a sample to study the variability, and three rigolits samples in sequential apprenticeships of weathering. Each sample was dried in the sun during about 48 hours, broken, drizzled in a sieve of 4 mesh and put, in a cylindrical container. The measures were accomplished using a Germanium Hyper Pure detector (HPGe) with relative efficiency of 66%, connected to a standard spectrometry electronic chain. The measured concentrations of activity of 238U were smaller for the limestones (17.80 ±0.09 Bq.Kg-1), larger for the bituminous shales (125.5 ± 2.6 Bq.Kg-1 with enrichment of uranium in the sample (200), 548 ± 16 Bq.Kg-1, upper part of the column), and intermediate for the rhythmits (23.0 ± 1,3 Bq.Kg-1. The ratio eTh/K obtained for the studied profiles has equivalent values, indicating similar mineralogical characteristics for the limestones, bituminous shales, rhythmits and studied rigolits. On the other hand, to the ratio eTh/eU showed that two of the three regolits samples belong to oxidizer atmospheres, favoring the leaching of uranium, what can be causing the enrichment of the sample (200), once these soils are above the column. The average measured doses were 16 nGy.h-1 for the limestones and rhythmits, 79.5 nGy.h-1 for the bituminous shales and 329.5 nGy.h-1 for the enriched bituminous shales of the top of the column. These results supply data to estimate the contribution of these products for the radiation dose received by the public in general, besides of database for mineralogical and geophysical studies of the Parana Basin. (author)

112

Liassic U-Pb age of the Rabejac pitchblende. Isotopic arguments for a Permian uraniferous preconcentration in the Lodeve basin (Herault)  

International Nuclear Information System (INIS)

Located in the basal part of the Saxonian formations of he Lodeve basin, the massive pitchblendes of the Rabejac ore deposit provide an age of 183 ± 4 Ma (Pb-Pb isochron), consistent with a Liassic mobilization of uranium in southern Massif central previously dated in the U ore deposits of Lodeve (Herault), Bertholene (Aveyron) and Pierres-Plantees (Lozere). This mobilization is related to the circulation of rather hot saline fluids (3-14%, 130-2500C) induced by the tectonic phase of continental crust thinning (horsts, grabens, tilted blocks) which preceded the opening of the Ligurian-Piemontais ocean. Using Concordias diagrams we discuss the isotopic composition of the initial lead incorporated into the Rabejac pitchblendes during their cristallization which appears to have been radiogenic. This constitutes the first isotopic argument in favour of a primary U concentration during Permian times in the Lodeve basin

113

Dispersal Syndromes of fossil Seeds from the Lower Permian of Paraná Basin, Rio Grande do Sul, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A Análise morfológica das sementes tem sido um importante objeto em estudos ecológicos modernos, uma vez que fornece evidências sobre a biologia e as adaptações das plantas-mãe de sementes. Entretanto, este tipo de estudo tem sido restrito a ecologia de plantas modernas e é raramente utilizado em in [...] terpretações de dados paleozóicos. A partir do entendimento da análise das sindromes de dispersão como uma importante ferramenta para reconstruções paleoecológicas, este estudo oferece uma primeira abordagem utilizando essa ferramenta com sementes do Permiano Inferior do Sul da Bacia do Paraná, no Rio Grande do Sul. Baseado em sementes previamente classificadas e utilizando seus dados biológicos e tafonômicos, a síndrome de dispersão foi interpretada, e a classificação das sementes nos grupos successionais (pioneira, secundária inicial ou secundária tardia) foi sugerida. Sete morfoespécies foram analisadas: Samaropsis gigas, representando uma espécie de secundária-tardia, vivendo próximo a corpos d'água, com síndrome de dispesão hidrocórica; Samaropsis kurtzii, típica espécie de sucessão secundária inicial, apresentando a anemocoria como síndrome de dispersão e habitando áreas distantes em relação a corpos d'água; Samaropsis aff. S. millaniana, Cordaicarpus aff. C. brasilianus, Cordaicarpus cerronegrensis e Cordaicarpus truncata com características típicas de plantas pioneiras, sendo a barocoria sua principal síndrome de dispersão com outras síndromes associadas. Abstract in english The morphological analysis of seeds has been an important subject in modern ecological studies, once it provides evidence about the biology and adaptations of the parent plant. However, this kind of study has been restricted to the ecology of modern plants and is rarely used in interpretations of Pa [...] leozoic data. From the understanding of dispersal syndromes analysis as an important tool to paleoecological reconstruction, this study provides a first approach using this tool with seeds from the Lower Permian strata of southern Paraná Basin in Rio Grande do Sul. Based on previously classified seeds and using their biological and taphonomic data, the syndrome of dispersal was interpreted, and their placement in successional groups (pioneer, early-successional and later-successional) was suggested. Seven morphospecies were analyzed: Samaropsis gigas, representing a later-successional species living in water bodies with hydrochory as its dispersal syndrome; Samaropsis kurtzii, typical of early-successional species showing anemochory as its dispersal syndrome and living in distal areas in relation to water bodies; Samaropsis aff. S. millaniana, Cordaicarpus aff. C. brasilianus, Cordaicarpus cerronegrensis and Cordaicarpus truncata have typical characteristics of pioneer plants, exhibiting barochory as their primary dispersal syndrome with other syndromes associated.

Juliane M., Souza; Roberto, Iannuzzi.

2012-03-01

114

Provenance study of Permian non-marine sandstones and conglomerates of the Krkonoše Piedmont Basin (Czech Republic: exotic marine limestone pebbles, heavy minerals and garnet composition  

Directory of Open Access Journals (Sweden)

Full Text Available This study focuses on identifying major source areas in several stratigraphic intervals in the Permian sediments of the Krkonoše Piedmont Basin and integrates it with existing sedimentological data. Pebbles in Cisuralian-Guadalupian conglomerates of alluvial fans, nearshore lacustrine and lacustrine fan-delta deposits that were deposited close to the northwestern and southeastern basin margin, respectively, correspond almost exclusively to local material from adjacent crystalline complexes. The heavy mineral associations of the sandstone matrix of these conglomerates support this interpretation. Crystalline units of the south-western part of the Krkonoše-Jizera Crystalline Complex and Orlice-Sn?žník Crystalline Complex, respectively, are considered as the most favourable sources. Heavy mineral associations of fluvial sandstone facies are of complex composition pointing to repeated recycling of clastic material. However, heavy mineral indices reveal distinct source areas for the main lithostratigraphic units. Two main possible source areas for the fluvial Asselian deposits (Vrchlabí Formation of the south-western part of the basin were found. Pebbles of late Devonian- early Carboniferous marine limestones probably came from the central part of the hypothetical Jítrava-Hradec Basin. The garnet compositions in sand detrital material point to leucogranites and pegmatites of the north-eastern Moldanubian Zone, P?ibyslavice area, as the possible source rocks. Guadalupian fluvial deposits reveal a wide range of sources that can be attributed to the recycling of detrital material from Cisuralian and Carboniferous deposits. Garnet compositions indicate Moldanubian granulites, garnet clinopyroxenites, leucogranites and pegmatites as a possible sources. We infer that Moldanubian granulites and garnet clinopyroxenites were exposed to an erosion level in the Early Permian at the latest.

Martínek K

2009-09-01

115

Perspectives and perils of using U-Pb zircon geochronology to constrain stratigraphic age: lessons from the Permian-Triassic Karoo basin, South Africa  

Science.gov (United States)

The Karoo basin contains an important Carboniferous-Jurassic sedimentary record that chronicles the amalgamation of Pangea, subduction along the southern Panthallasan margin and later opening of the South Atlantic, Southern, and Indian oceans. It also preserves a robust record of the end-Permian extinction, Earth's largest paleobiologic crisis. Fortuitously, this stratigraphic record is interleaved with numerous air-fall volcanic ashes likely derived from a continental magmatic system, part of which is currently exposed in the Choiyoi igneous province of South America. Our U-Pb geochronology of air-fall ash zircon from the Ecca and Beaufort Groups via SHRIMP analysis, along with LA-ICP-MS U-Pb analysis of detrital zircon from interbedded sandstones indicate that magmatic activity of this system likely persisted for at least 50 Ma. Particularly noteworthy is that uppermost Ecca Group detrital zircon signature exhibits few Precambrian ages and abundant Permian-Triassic ages; thus, by the start of marginal marine deposition, Karoo basin clastic influx was primarily sourced by some part of the Permian-Triassic Panthallassic magmatic system (i.e., the Choiyoi igneous province or its southern equivalent). Detrital zircon U-Pb ages suggest initial zircon formed within this magmatic system by ~300 Ma and that the apex of zircon crystallization occurred at ~265-275 Ma, after which, zircon crystallization decreased through time. We hypothesize that over the long duration of magmatic evolution, the melt began to become depleted with respect to zircon, such that by ~260 Ma, the melt became primarily undersaturated with respect to zircon. As a result, zircon was no longer a major accessory phase and ultimately after ~250 Ma was extruded only in scant trace amounts. This interpretation is also supported by U-Pb zircon geochronology on a few dozen Ecca and Beaufort Group ashes from across the Karoo basin. Individual ash ages were determined from statistically-robust, coherent populations of single U-Pb zircon ages. When interpreted in the context of recent ash U-Pb zircon geochronology results of others, the results depict a regional and repeatable occurrence of Permian ashes within the Triassic Beaufort Group that are consistently older than or within statistical error of ash ages found in the Ecca Group, despite the stratigraphic position of Ecca Group ashes 100's to >1000 m downsection of the Beaufort Group ashes. Lacking a reasonable geological explanation for this inversion, it appears that zircon within Beaufort Group ashes are of recycled or xenocrystic origin and yield coherent U-Pb zircon age populations which are older than the ash depositional age. Thus, even when high analytical precision is attained and Pb-loss is considered, ash ages determined by U-Pb zircon geochronology may not reliably demarcate the record of the end-Permian extinction and associated environmental changes preserved within Karoo basin strata. Furthermore, any stratigraphic age constrained solely by U-Pb zircon age populations from one or even a few separate ash beds may in fact be spurious given the evolution of zircon saturation within the magmatic system that sourced the ash.

Weislogel, A. L.; Mckay, M. P.; Dean, J.; Fildani, A.

2013-12-01

116

Depositional setting, petrology and chemistry of Permian coals from the Paran?? Basin: 2. South Santa Catarina Coalfield, Brazil  

Science.gov (United States)

In Brazil economically important coal deposits occur in the southern part of the Paran?? Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Paran?? Basin.In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapu??, Barro Branco and Treviso seams).Seam thicknesses range from 1.70 to 2.39. m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapu?? seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapu?? seam has the highest inertinite content (33.8. vol%). Liptinite mean values range from 7.8. vol% (Barro Branco seam) to 22.5. vol% (Irapu?? seam).Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (>50wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the predominance of quartz and kaolinite (also pyrite). Gypsum, gibbsite, jarosite and calcite were also identified in some samples. Feldspar was noted but is rare. The major element distribution in the three seams (coal basis) is dominated by SiO2 (31.3wt.%, mean value), Al2O3 (14.5wt.%, mean value) and Fe2O3 (6.9 wt.%, mean value). Considering the concentrations of trace elements that are of potential environmental hazards the Barro Branco, Bonito and Irapu?? seams (coal base) are significantly enriched in Co (15.7ppm), Cr (54.5ppm), Li (59.3ppm), Mn (150.4ppm), Pb (58.0ppm) and V (99.6ppm), when compared to average trace elements contents reported for U. S. coals.Hierarchical cluster analysis identified, based on similarity levels, three groups of major elements and seven groups of trace elements. Applying discriminant analyses using trace and major element distribution, it could be demonstrated that the three seams from Santa Catarina show distinct populations in the discriminant analyses plots, and also differ from the coals of Rio Grande do Sul analyzed in a previous study. ?? 2010 Elsevier B.V.

Kalkreuth, W.; Holz, M.; Mexias, A.; Balbinot, M.; Levandowski, J.; Willett, J.; Finkelman, R.; Burger, H.

2010-01-01

117

Depositional setting, petrology and chemistry of Permian coals from the Parana Basin: 2. South Santa Catarina Coalfield, Brazil  

Energy Technology Data Exchange (ETDEWEB)

In Brazil economically important coal deposits occur in the southern part of the Parana Basin, where coal seams occur in the Permian Rio Bonito Formation, with major coal development in the states of Rio Grande de Sul and Santa Catarina. The current paper presents results on sequence stratigraphic interpretation of the coal-bearing strata, and petrological and geochemical coal seam characterization from the South Santa Catarina Coalfield, Parana Basin. In terms of sequence stratigraphic interpretation the precursor mires of the Santa Catarina coal seams formed in an estuarine-barrier shoreface depositional environment, with major peat accumulation in a high stand systems tract (Pre-Bonito and Bonito seams), a lowstand systems tract (Ponta Alta seam, seam A, seam B) and a transgressive systems tract (Irapua, Barro Branco and Treviso seams). Seam thicknesses range from 1.70 to 2.39 m, but high proportions of impure coal (coaly shale and shaley coal), carbonaceous shale and partings reduce the net coal thickness significantly. Coal lithoypes are variable, with banded coal predominant in the Barro Branco seam, and banded dull and dull coal predominantly in Bonito and Irapua seams, respectively. Results from petrographic analyses indicate a vitrinite reflectance range from 0.76 to 1.63 %Rrandom (HVB A to LVB coal). Maceral group distribution varies significantly, with the Barro Branco seam having the highest vitrinite content (mean 67.5 vol%), whereas the Irapua seam has the highest inertinite content (33.8 vol%). Liptinite mean values range from 7.8 vol% (Barro Branco seam) to 22.5 vol% (Irapua seam). Results from proximate analyses indicate for the three seams high ash yields (50.2 - 64.2 wt.%). Considering the International Classification of in-Seam Coals, all samples are in fact classified as carbonaceous rocks (> 50 wt.% ash). Sulfur contents range from 3.4 to 7.7 wt.%, of which the major part occurs as pyritic sulfur. Results of X-ray diffraction indicate the predominance of quartz and kaolinite (also pyrite). Gypsum, gibbsite, jarosite and calcite were also identified in some samples. Feldspar was noted but is rare. The major element distribution in the three seams (coal basis) is dominated by SiO{sub 2} (31.3 wt.%, mean value), Al{sub 2}O{sub 3} (14.5 wt.%, mean value) and Fe{sub 2}O{sub 3} (6.9 wt.%, mean value). Considering the concentrations of trace elements that are of potential environmental hazards the Barro Branco, Bonito and Irapua seams (coal base) are significantly enriched in Co (15.7 ppm), Cr (54.5 ppm), Li (59.3 ppm), Mn (150.4 ppm), Pb (58.0 ppm) and V (99.6 ppm), when compared to average trace elements contents reported for U. S. coals. Hierarchical cluster analysis identified, based on similarity levels, three groups of major elements and seven groups of trace elements. Applying discriminant analyses using trace and major element distribution, it could be demonstrated that the three seams from Santa Catarina show distinct populations in the discriminant analyses plots, and also differ from the coals of Rio Grande do Sul analyzed in a previous study. (author)

Kalkreuth, W.; Mexias, A.; Balbinot, M.; Levandowski, J. [Instituto de Geociencias, UFRGS, Porto Alegre (Brazil); Holz, M. [Inst. de Geociencias, UFBA, Salvador, Bahia (Brazil); Willett, J.; Finkelman, R. [U.S. Geological Survey, Reston, VA (United States); Burger, H. [Freie Universitaet Berlin, Geoinformatik, (Germany)

2010-12-01

118

Deformation bands in carboniferous-permian sandstones of the Parana Basin; Bandas de deformacao em arenitos permocarboniferos da Bacia do Parana  

Energy Technology Data Exchange (ETDEWEB)

Deformation bands developed on Carboniferous-Permian sandstones in the eastern portion of the Parana Basin are analyzed. Emphasis was made on their geologic evolution and possible impacts on fluid circulation within naturally fractured reservoirs. Sub vertical fractures and fault zones prevail in the studied area and were generated and/or reactivated in at least three major deformation events during Permian, Jurassic-Cretaceous and Cenozoic times. Micro structurally, two types of deformation bands can be recognized: one type characterized by grain fracturing and a second type showing gouge zone formation due to intense grain comminution. According to hydraulic properties of deformation bands and temporal relationship with hydrocarbon generation and migration, fractures within the sandstones can act as permeability barriers or conduits for fluid flow. In the studied sandstones, deformation bands with gouge zones were potential seals because grain comminution is closely related to permeability decrease. Alternatively, it is probable that marginal damaged zones should have acted as permeability pathways laterally along the gouge zones. Fractured deformation bands were conduits for fluid flow at least during a short time interval in the mesodiagenesis. Carbonate and anhydrite cementation along fractures from core samples suggest that these potential conduits were subsequently sealed still during mesodiagenesis. (author)

Trzaskos, Barbara [PETROBRAS, Rio de Janeiro, RJ (Brazil). E e P. Gerencia de Geologia Estrutural e Analise Tectonica]. E-mail: barbara.t@petrobras.com.br; Rostirolla, Sidnei Pires; Bocardi, Luciane Bergamin

2006-11-15

119

Permian radiolarian faunas from Thailand and their paleogeographic significance  

Science.gov (United States)

Chert and fine-grained clastic rocks in Thailand contain rich Permian radiolarian faunas. We have discriminated eight radiolarian assemblages in these rocks; Pseudoalbaillella bulbosa (Upper Carboniferous to lowermost Permian; Gzhelian to Asselian), Pseudoalbaillella simplex (lowermost Permian; Asselian), Pseudoalbaillella lomentaria (Lower Permian; Asselian to Sakmarian), Pseudoalbaillella scalprata (Lower Permian; Sakmarian), Follicucullus monacanthus (Middle Permian; Wordian), Follicucullus porrectus (upper Middle to lowermost Upper Permian; Capitanian to lower Wuchiapingian), Neoalbaillella ornithoformis (Upper Permian; Wuchiapingian), and Neoalbaillella optima (Upper Permian; Changsingian) assemblages in stratigraphic order. These radiolarians have a potential to contribute to understanding the history of the Paleotethys. Based on the radiolarian biostratigraphy and lithological characteristics, Lower to lower Upper Permian radiolarian-bearing cherts are thought to have been deposited in a pelagic environment in a deep basin far from land. The uppermost Permian radiolarian-bearing cherts, however, reveal differences in their depositional environments. In northern Thailand the uppermost Permian to Middle Triassic radiolarian chert was deposited in a pelagic basin, while in eastern Thailand the uppermost Permian chert and the conformably overlying clastic rocks show a change in depositional environment across the P-T boundary, from a deep pelagic or hemipelagic, to shallow seas in the Triassic.

Sashida, K.; Salyapongse, S.

2002-08-01

120

Petrology and chemistry of Permian coals from the Parana?? Basin: 1. Santa Terezinha, Lea??o-Butia?? and Candiota Coalfields, Rio Grande do Sul, Brazil  

Science.gov (United States)

The current paper presents results on petrological and geochemical coal seam characterization in Permian coal-bearing strata from the Parana?? Basin, southern Brazil. Sequence stratigraphic analysis shows that peat accumulation in Permian time was closely linked to transgressive/regressive cycles, with peat accumulation occurring in a predominantly back barrier/lagoonal setting. Coal petrographic analysis indicates subbituminous coals at Candiota and Lea??o-Butia?? and high volatile bituminous coals at Santa Terezinha, where locally the coal seams are thermally altered by volcanic intrusions. Petrographic composition is highly variable, with seams at Candiota and Santa Terezinha frequently enriched in inertinite. Chemical analyses indicate that all coals are mineral matter-rich (mean 49.09 wt.%), with SiO2 and Al2O3 dominating as determined by ICP-AES. Quartz is also the predominant mineral detected by X-ray diffraction, where it is associated with feldspar, kaolinite and hematite and iron-rich carbonates. The results from Scanning Electron Microscopy are broadly consistent with the bulk chemical and mineralogical analysis. Quartz and clays are common in all samples analyzed. Other minerals observed were, amongst others, carbonates (calcite, siderite, ankerite), pyrite, monazite, kaolinite, barite, sphalerite, rutile and quartz of volcanic origin. The distribution of trace elements is well within the range typical for coal basins of other areas despite the fact that the Parana?? Basin coals are very high in ash yields. The average concentrations for elements of environmental concern (As, B, Be, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, Pb, Sb, Se, Tl, U, V, Zn) are similar to or less than the mean values for U.S. coal. However, considered on an equal energy basis, Parana?? Basin coals will produce in combustion 5 to 10 times the amount of most elements compared to an equal weight US coal. Concentrations of major and trace elements, such as Fe, B and S, appear to be controlled by depositional setting, with increasing values in coal seams overlain by brackish/marine strata. Hierarchical cluster analysis identified three groups of major minerals and seven groups of trace elements based on similarity levels. On a regional scale, the coalfields can be separated by the differences in rank (Candiota and Lea??o-Butia?? versus Santa Terezinha) and by applying discriminant analysis based on 4 trace elements (Li, As, Sr, Sb). Highest Rb and Sr values occur at Candiota and are linked to syngenetic volcanism of the area, whereas high Y and Sr values at Santa Terezinha can be related to the frequent diabase intrusions in that area. ?? 2006 Elsevier B.V. All rights reserved.

Kalkreuth, W.; Holz, M.; Kern, M.; Machado, G.; Mexias, A.; Silva, M.B.; Willett, J.; Finkelman, R.; Burger, H.

2006-01-01

121

Petrology and chemistry of Permian coals from the Parana Basin: 1. Santa Terezinha, Leao-Butia and Candiota Coalfields, Rio Grande do Sul, Brazil  

Energy Technology Data Exchange (ETDEWEB)

The current paper presents results on petrological and geochemical coal seam characterization in Permian coal-bearing strata from the Parana Basin, southern Brazil. Sequence stratigraphic analysis shows that peat accumulation in Permian time was closely linked to transgressive/regressive cycles, with peat accumulation occurring in a predominantly back barrier/lagoonal setting. Coal petrographic analysis indicates subbituminous coals at Candiota and Leao-Butia and high volatile bituminous coals at Santa Terezinha, where locally the coal seams are thermally altered by volcanic intrusions. Petrographic composition is highly variable, with seams at Candiota and Santa Terezinha frequently enriched in inertinite. Chemical analyses indicate that all coals are mineral matter-rich (mean 49.09 wt.%), with SiO{sub 2} and Al{sub 2}O{sub 3} dominating as determined by ICP-AES. Quartz is also the predominant mineral detected by X-ray diffraction, where it is associated with feldspar, kaolinite and hematite and iron-rich carbonates. The results from Scanning Electron Microscopy are broadly consistent with the bulk chemical and mineralogical analysis. Quartz and clays are common in all samples analyzed. Other minerals observed were, amongst others, carbonates (calcite, siderite, ankerite), pyrite, monazite, kaolinite, barite, sphalerite, rutile and quartz of volcanic origin. The distribution of trace elements is well within the range typical for coal basins of other areas despite the fact that the Parana Basin coals are very high in ash yields. The average concentrations for elements of environmental concern (As, B, Be, Cd, Co, Cr, Cu, Hg, Li, Mn, Mo, Ni, Pb, Sb, Se, Tl, U, V, Zn) are similar to or less than the mean values for U.S. coal. However, considered on an equal energy basis, Parana Basin coals will produce in combustion 5 to 10 times the amount of most elements compared to an equal weight US coal. Concentrations of major and trace elements, such as Fe, B and S, appear to be controlled by depositional setting, with increasing values in coal seams overlain by brackish/marine strata. Hierarchical cluster analysis identified three groups of major minerals and seven groups of trace elements based on similarity levels. On a regional scale, the coalfields can be separated by the differences in rank (Candiota and Leao-Butia versus Santa Terezinha) and by applying discriminant analysis based on 4 trace elements (Li, As, Sr, Sb). Highest Rb and Sr values occur at Candiota and are linked to syngenetic volcanism of the area, whereas high Y and Sr values at Santa Terezinha can be related to the frequent diabase intrusions in that area. (author)

Kalkreuth, W.; Holz, M.; Kern, M.; Mexias, A.; Silva, M.B. [Instituto de Geociencias, UFRGS, Av. Bento Goncalves, 9500, 91501-970 Porto Alegre, RS (Brazil); Machado, G. [Instituto de Quimica, UFRGS, Av. Bento Goncalves, 9500, 91501-970 Porto Alegre, RS (Brazil); Willett, J.; Finkelman, R. [U.S. Geological Survey, Mail Stop 956, Reston, VA 20192 (United States); Burger, H. [Freie Universitaet Berlin-Geoinformatik-Malteserstr. 74-100, 12249 Berlin (Germany)

2006-08-01

122

Diagenesis of clay minerals and K-bentonites in Late Permian/Early Triassic sediments of the Sichuan Basin (Chaotian section, Central China)  

Science.gov (United States)

Detailed clay mineralogical analyses were carried out on Late Permian/Early Triassic carbonate sediments exposed on the Chaotian section (Sichuan Basin, Central China). The clay assemblages are dominantly composed of illite in platform carbonates and clay seams, and illite-smectite mixed-layers (I/S) in tuff layers (K-bentonites) intercalated in the carbonate succession. Detrital and authigenic volcanogenic clay minerals have been partially replaced through illitisation processes during burial, raising questions about diagenetic effects. The precise determination of I/S occurring in K-bentonites shows that the sediments reached a temperature of about 180 °C, which is consistent with (1) previous estimates based on fluid-inclusion homogenisation temperature analysis, (2) the burial depth of the sedimentary series deduced from the post-Palaeozoic geological history of the Sichuan Basin and (3) the new data (Tmax) obtained on organic matter indicating the transition between oil and gas windows. The Wangpo Bed, located close to the Guadalupian-Lopingian Boundary, is interpreted either as a volcanic acidic tuff or as a clastic horizon. This controversial origin probably results from mixed volcanogenic and detrital influences. The Wangpo Bed is therefore interpreted as a reworked bentonite as revealed by the occurrence of I/S similar to those found in tuff layers, together with preserved detrital kaolinite.

Deconinck, J. F.; Crasquin, S.; Bruneau, L.; Pellenard, P.; Baudin, F.; Feng, Q.

2014-02-01

123

Occurrence of Early Permian palynofossils in the subsurface sediments of Dhansiri Valley, Assam-Arakan Basin, India  

Energy Technology Data Exchange (ETDEWEB)

The occurrence of Lower Gondwana palynoassemblage has been recorded from the subsurface sediments of an exploratory well Dergaon-A in Dhansiri Valley of Assam-Arakan Basin. The recorded palynoassemblage includes rich radial monosaccate genera Potoneisporites sp, Parasaccites sp, Plicatipollenites sp, Virkkipollenites sp, associated with the trilete spores viz. Microfoveolatispora sp, Microbaculispora sp, along with acritarch Leiosphaeridia sp. These palynofossils are correlatable with those recorded from the Talchir Formation of South Rewa Basin, Jayantia coal field, Cauvery Basin and Krishna Godavari Basin. Occurrence of Leiosphaeridia indicate that the sediments appears to be deposited under marine conditions.

Basavaraju, M.H.; Pundeer, B.S. [ONGC Ltd, Sivasagar (India). Regional Geological Labs.

2003-11-01

124

A Resource Assessment Of Geothermal Energy Resources For Converting Deep Gas Wells In Carbonate Strata Into Geothermal Extraction Wells: A Permian Basin Evaluation  

Energy Technology Data Exchange (ETDEWEB)

Previously conducted preliminary investigations within the deep Delaware and Val Verde sub-basins of the Permian Basin complex documented bottom hole temperatures from oil and gas wells that reach the 120-180C temperature range, and occasionally beyond. With large abundances of subsurface brine water, and known porosity and permeability, the deep carbonate strata of the region possess a good potential for future geothermal power development. This work was designed as a 3-year project to investigate a new, undeveloped geographic region for establishing geothermal energy production focused on electric power generation. Identifying optimum geologic and geographic sites for converting depleted deep gas wells and fields within a carbonate environment into geothermal energy extraction wells was part of the project goals. The importance of this work was to affect the three factors limiting the expansion of geothermal development: distribution, field size and accompanying resource availability, and cost. Historically, power production from geothermal energy has been relegated to shallow heat plumes near active volcanic or geyser activity, or in areas where volcanic rocks still retain heat from their formation. Thus geothermal development is spatially variable and site specific. Additionally, existing geothermal fields are only a few 10’s of square km in size, controlled by the extent of the heat plume and the availability of water for heat movement. This plume radiates heat both vertically as well as laterally into the enclosing country rock. Heat withdrawal at too rapid a rate eventually results in a decrease in electrical power generation as the thermal energy is “mined”. The depletion rate of subsurface heat directly controls the lifetime of geothermal energy production. Finally, the cost of developing deep (greater than 4 km) reservoirs of geothermal energy is perceived as being too costly to justify corporate investment. Thus further development opportunities for geothermal resources have been hindered. To increase the effective regional implementation of geothermal resources as an energy source for power production requires meeting several objectives. These include: 1) Expand (oil and gas as well as geothermal) industry awareness of an untapped source of geothermal energy within deep permeable strata of sedimentary basins; 2) Identify and target specific geographic areas within sedimentary basins where deeper heat sources can be developed; 3) Increase future geothermal field size from 10 km2 to many 100’s km2 or greater; and 4) Increase the productive depth range for economic geothermal energy extraction below the current 4 km limit by converting deep depleted and abandoned gas wells and fields into geothermal energy extraction wells. The first year of the proposed 3-year resource assessment covered an eight county region within the Delaware and Val Verde Basins of West Texas. This project has developed databases in Excel spreadsheet form that list over 8,000 temperature-depth recordings. These recordings come from header information listed on electric well logs recordings from various shallow to deep wells that were drilled for oil and gas exploration and production. The temperature-depth data is uncorrected and thus provides the lower temperature that is be expected to be encountered within the formation associated with the temperature-depth recording. Numerous graphs were developed from the data, all of which suggest that a log-normal solution for the thermal gradient is more descriptive of the data than a linear solution. A discussion of these plots and equations are presented within the narrative. Data was acquired that enable the determination of brine salinity versus brine density with the Permian Basin. A discussion on possible limestone and dolostone thermal conductivity parameters is presented with the purpose of assisting in determining heat flow and reservoir heat content for energy extraction. Subsurface maps of temperature either at a constant depth or within a target geothermal reservoir are discusse

Erdlac, Richard J., Jr.

2006-10-12

125

Fluvial facies characteristics of the Sunan formation of the later period of upper permian in Binggoumen basin  

International Nuclear Information System (INIS)

Two types of paleochannels wewe developed in the Sunan Formation of the later period of Upper Permian (P2s) in Binggoumen anomalous area, Gansu province. The braided tributary river represented by the Daciyao River has a low uranium abundance in the area of erosion and steep gradient of the river bed, short water course and rapid water flow which are not favourable for the formation of uranium mineralization. During the middle to late stage of the development of the Guliyuan River, low-high sinuosity meandering rivers were formed where point bars had developed in a moderate size (river width<300m). Uranium source was abundant, and the river water was enriched with organic matters such as plant debris. During the period of deposition-diagenesis, uranium accumulated at the river bend and at the intersecting part between main channel and tributary channel providing a good prerequiste for the economic uranium concentration in the epigenetic period

126

The Carboniferous - Permian basins of Central and Western Bohemia, the Krkonoše Mt. foreland and the Bohemian Massif, Czech Republic : part I.  

Czech Academy of Sciences Publication Activity Database

Ro?. 46, ?. 1 (2014), s. 14-54. ISSN 1433-1284. [Field Meeting on Carboniferous and Permian Nonmarine – Marine Correlation. Freiberg, 21.07.2014-27.07.2014] Institutional support: RVO:67985831 Keywords : Carboniferous * Permian * excursion guide Subject RIV: DB - Geology ; Mineralogy

Opluštil, S.; Martínek, K.; Lojka, R.; Rosenau, N.; Zajíc, Jaroslav; Šim?nek, Z.; Drábková, J.; Štamberg, S.

2014-01-01

127

Shahejie-Shahejie/Guantao/Wumishan and Carboniferous/Permian Coal-Paleozoic Total Petroleum Systems in the Bohaiwan Basin, China (based on geologic studies for the 2000 World Energy Assessment Project of the U.S. Geological Survey)  

Science.gov (United States)

This report discusses the geologic framework and petroleum geology used to assess undiscovered petroleum resources in the Bohaiwan basin province for the 2000 World Energy Assessment Project of the U.S. Geological Survey. The Bohaiwan basin in northeastern China is the largest petroleum-producing region in China. Two total petroleum systems have been identified in the basin. The first, the Shahejie&ndashShahejie/Guantao/Wumishan Total Petroleum System, involves oil and gas generated from mature pods of lacustrine source rock that are associated with six major rift-controlled subbasins. Two assessment units are defined in this total petroleum system: (1) a Tertiary lacustrine assessment unit consisting of sandstone reservoirs interbedded with lacustrine shale source rocks, and (2) a pre-Tertiary buried hills assessment unit consisting of carbonate reservoirs that are overlain unconformably by Tertiary lacustrine shale source rocks. The second total petroleum system identified in the Bohaiwan basin is the Carboniferous/Permian Coal–Paleozoic Total Petroleum System, a hypothetical total petroleum system involving natural gas generated from multiple pods of thermally mature coal beds. Low-permeability Permian sandstones and possibly Carboniferous coal beds are the reservoir rocks. Most of the natural gas is inferred to be trapped in continuous accumulations near the center of the subbasins. This total petroleum system is largely unexplored and has good potential for undiscovered gas accumulations. One assessment unit, coal-sourced gas, is defined in this total petroleum system.

Ryder, Robert T.; Qiang, Jin; McCabe, Peter J.; Nuccio, Vito F.; Persits, Felix

2012-01-01

128

Paleomagnetism of an uppermost Permian section in the Lootsberg Pass area, central Karoo Basin: What remanence signal is recorded in the Permo-Triassic boundary sequences in the Karoo Basin?  

Science.gov (United States)

The end Permian is associated with the greatest mass extinction in Earth history, with some 80 percent of genus-level extinctions and a range of 75 to 96 percent specie- level extinction in the marine environment, depending upon clade. Although most of our understanding of the Permian-Triassic boundary (PTB) and extinction are based on information from marine sequences in Europe and Asia, a growing body of observations from continental sequences demonstrates a similar extinction event. Yet, the synchronicity of marine and terrestrial events is far from clear. As part of an ongoing, multifaceted effort to better understand one of the best-preserved terrestrial sequences deposited across the PTB, we have collected paleomagnetic data from part of the Beaufort Group of the central Karoo Basin in South Africa with the goal of identifying a magnetic polarity record that can be correlated with the now well-established polarity record across the PTB. We sampled a total of 40 distinct beds (typically each bed was sampled with 8 to 16 cores) at a 127 m thick section near Lootsberg Pass and five sites along the R61 at New Wapadsburg Pass; at both of these localities the PTB has been reported or interpreted to be exposed. Sampled beds at both localities are in siltstone, fine grained sandstone, and carbonate concretions in mudstone intervals. Intensities of NRM typically range from 10 to 50 mA/m. Most materials respond favorably to both progressive alternating field and thermal demagnetization; thermal treatment typically yields a more complete definition of the NRM, with laboratory unblocking temperatures up to about 580 C. NRM directions in all samples are of normal polarity, and most samples yield a well-defined magnetization of NNW declination and moderate negative inclination (normal polarity). At laboratory unblocking temperatures above ~450 C, some samples indicate the possible preservation of a reverse polarity remanence, but it is poorly defined in further demagnetization. The prevailing remanence in these rocks is very comparable to characteristic magnetizations from the ca. 184 to 178 Ma mafic sills of the Karoo Large Igneous Province (e.g., Decl = 336.9, Inc=-55.7, a95=3.8, k=66.2, N = 22 sites; Geissman et al., 2010), which are common throughout the central Karoo Basin. We tentatively question whether the Beaufort Group strata in the central Karoo Basin retain a primary magnetization and, thus, a magnetic polarity stratigraphy across the PTB.

Geissman, J. W.; Gastaldo, R.; Neveling, J.; Prevec, R.; Kamo, S.; Spencer, K.; Langwenya, M.

2012-12-01

129

The influence of palaeoenvironment and lava flux on the emplacement of submarine, near-shore Late Permian basalt lavas, Sydney Basin (Australia)  

Science.gov (United States)

Lava flux and a low palaeoslope were the critical factors in determining the development of different facies in the Late Permian Blow Hole flow, which comprises a series of shoshonitic basalt lavas and associated volcaniclastic detritus in the southern Sydney Basin of eastern Australia. The unit consists of a lower lobe and sheet facies, a middle tube and breccia facies, and an upper columnar-jointed facies. Close similarities in petrography and geochemistry between the basalt lavas from the three facies suggest similar viscosities at similar temperatures. Sedimentological and palaeontological evidence from the sedimentary units immediately below the Blow Hole flow suggests that the lower part of the volcanic unit was emplaced in a cold water, shallow submarine environment, but at least the top of the uppermost lava was subaerial with some palaeosol development. The lower lobe and sheet facies was emplaced on a low slope (<2°) in a lower to middle shoreface environment with water depths of ˜20-25 m. Lava may have transgressed from subaerial to subaqueous and was emplaced relatively passively with lava flux sufficiently high and uniform to form lobes and sheets rather than pillows. The middle unit probably originated from a subaerial vent and flowed into a shallow (10-15 m) submarine environment, and wave action probably interacted with the advancing lava front to form a lava delta. Lava flux was sufficiently high to produce well-developed, subcircular lava tubes, which lack evidence for thermal erosion. In some areas, lava 'burrowed' into the unconsolidated, water-saturated lava delta and sand pile to produce intrusive contacts. The upper columnar-jointed unit represents a ponded facies probably emplaced initially in water depths <5 m but whose top was subaerial.

Carr, Paul F.; Jones, Brian G.

2001-12-01

130

Alteration of a basaltic glass in an argillaceous medium:. The Salagou dike of the Lodève Permian Basin (France). Analogy with an underground nuclear waste repository  

Science.gov (United States)

Volcanic basaltic glasses are commonly considered to be very suitable natural analogs of vitrified waste packages intended for geological disposal. The studied basaltic glass of the Salagou dike (Lodève Basin, France) intruded into a Permian argillaceous formation about 1.4 Ma ago, provides a means of assessing the long-term behavior of nuclear waste glass in an argillaceous repository concept. This study is based on combining chemical, mineralogical and isotopic investigations. The occurrence of a palagonite film no more than 1.2 mm thick characterizes the basaltic glass alteration in contact with the argillaceous host rock. The chemical and structural properties of the palagonite suggest constant volume alteration. The alteration rates estimated from palagonite thickness and age of the glass are comparable to those measured on natural glasses altered in nonargillaceous media. The occurrence of the studied argillaceous material in contact with the basaltic glass did not result in long-term alteration kinetics significantly different from those measured in simple glass/water systems. Mineralogical, chemical, and isotopic data obtained on the basaltic and argillaceous components suggest that an aqueous fluid flowed primarily at the glass/argillite interface and did not propagate in the argillaceous host rock beyond 5 cm from the basaltic dike. The elements released by alteration of the basaltic glass - notably strontium - did not diffuse into the surrounding clay. This conclusion is important from the perspective of a natural analog for a deep geological repository for nuclear waste, and highlights the major role of the structural properties of the clayey barrier.

Techer, Isabelle; Lancelot, Joël; Clauer, Norbert; Liotard, Jean Michel; Advocat, Thierry

2001-04-01

131

Coal petrology of coal seams from the Leao-Butia Coalfield, Lower Permian of the Parana Basin, Brazil - Implications for coal facies interpretations  

Energy Technology Data Exchange (ETDEWEB)

In the Leao-Butia Coalfield, Rio Grande do Sul the coal seams occur in the Rio Bonito Formation, Guata Group, Tubarao Supergroup of the Parana Basin, Brazil and are of Permian (Artinskian-Kungurian) age. This study is the first detailed investigation on the coal petrographic characterization of the coal-bearing sequence in relation to the depositional settings of the precursor mires, both in terms of whole seam characterization and in-seam variations. The study is based on the analyses of nine coal seams (I2, CI, L4, L3, L2, L1, S3, S2, S1), which were selected from core of borehole D-193, Leao-Butia and represent the entire coal-bearing sequence. The interpretation of coal facies and depositional environment is based on lithotype, maceral and microlithotype analyses using different facies-critical petrographic indices, which were displayed in coal facies diagrams. The seams are characterized by the predominance of dull lithotypes (dull, banded dull). The dullness of the coal is attributed to relatively high mineral matter, inertinite and liptinite contents. The petrographic composition is dominated by vitrinite (28-70 vol.% mmf) and inertinite (> 30 vol.% mmf) groups. Liptinite contents range from 7 to 30 vol.% (mmf) and mineral matter from 4-30 vol.%. Microlithotypes associations are dominated by vitrite, duroclarite, carbominerite and inertite. It is suggested that the observed vertical variations in petrographic characteristics (lithotypes, microlithotypes, macerals, vitrinite reflectance) were controlled by groundwater level fluctuations in the ancient mires due to different accommodation/peat accumulation rates. Correlation of the borehole strata with the general sequence-stratigraphical setting suggests that the alluvial fan system and the coal-bearing mudstone succession are linked to a late transgressive systems tract of sequence 2. Based on average compositional values obtained from coal facies diagrams, a deposition in a limno-telmatic to limnic coal facies is suggested. (author)

Silva, M.B. [Laboratorio de Oceanografia Geologica, Departamento de Geociencias, Fundacao Universidade Federal do Rio Grande, FURG, Av. Italia km 08, Campus Carreiros, 96201-900, Rio Grande, RS (Brazil); Kalkreuth, W.; Holz, M. [Instituto de Geociencias, UFRGS, Av. Bento Goncalves, 9500 91501-970 Porto Alegre, RS (Brazil)

2008-02-01

132

Depositional environments and sequence stratigraphy of the Late Carboniferous-Early Permian coal-bearing successions (Shandong Province, China): Sequence development in an epicontinental basin  

Science.gov (United States)

This study focuses on the Late Carboniferous-Early Permian coal-bearing successions in Shandong Province, North China in order to understand the depositional processes and sequence-stratigraphic framework in an epicontinental basin. Based on detailed analysis of eleven facies, five facies assemblages (FAs) were recognized in the studied succession. FA1-3 are present mainly in the Benxi and Taiyuan formations, and consist of mixed siliciclastic and carbonate lithofacies, representing eluvial-lagoon, barrier-lagoon, and tidal-flat environments. FA4 occurs in the Shanxi formation and consists mainly of interbedded medium to fine sandstone, siltstone, mudstone, and coal lithofacies, representing river-dominated deltaic environments. FA5 is characterized by interbeds of trough cross-stratified coarse sandstone, and silty mudstone, mainly in the Lower Shihezi Formation, which was deposited in meandering river channel and floodplain. Three third-order sequences were established based on the vertical arrangement of facies assemblages and identification of physical surfaces (i.e., subaerial unconformity, transgressive surface, and regressive surface). Each sequence comprises a transgressive systems tract (TST) and a highstand systems tract (HST). TST of sequence 1 is composed of eluvial lagoonal deposits (FA1), whereas HST formed in lagoon-barrier and tidal-flat settings (FA2 and FA3). TST of sequence 2 formed in a barrier-lagoon system (FA2), whereas HST is characterized by repetitive accumulation of interbedded limestone, sandstone, mudstone, and coal, deposited under lagoonal and tidal-flat settings (FA2 and FA3). TST of sequence 3 comprises FA2, and HST mainly FA4, deposited in a river-dominated shallow-water delta system. Sequence 3 is overlain by a fluvial sequence (FA5). The three third-order sequences in the Shandong region are generally correlated with those in the Taebaeksan Basin (South Korea), the eastern part of the North China Block. The relative sea-level curves established in the two regions show a generally similar long-term rising trend.

Lv, Dawei; Chen, Jitao

2014-01-01

133

Permian arc-back-arc basin development along the Ailaoshan tectonic zone: Geochemical, isotopic and geochronological evidence from the Mojiang volcanic rocks, Southwest China  

Science.gov (United States)

This paper presents a set of new SHRIMP zircon U-Pb geochronological, elemental and Sr-Nd-Pb isotopic data for the Wusu and Yaxuanqiao basaltic rocks (the Mojiang area) along the Ailaoshan tectonic zone. The Wusu basaltic sequence is dominated by SiO 2-poor, MgO- and TiO 2-rich basalts with a major mineral assemblage of plagioclase + clinopyroxene. These rocks gave a SHRIMP zircon U-Pb age of 287 ± 5 Ma (MSWD = 0.58). In contrast, the Yaxuanqiao basaltic sequence is predominantly composed of high-Al basaltic andesite, which gave a SHRIMP zircon U-Pb age of 265 ± 7 Ma (MSWD = 0.34). The analyzed samples for both sequences exhibit significant enrichment in LILEs and depletion in HFSEs with (Nb/La)n of 0.38-0.81, similar to arc-like volcanics. They have positive ?Nd(t) values (+ 3.52 to + 5.54). In comparison with MORB-derived magmatic rocks, the Wusu basalts are more enriched in LILEs and REEs, and the Yaxuanqiao samples are more enriched in LILEs but variably depleted in Ti, Y and HREE. The Wusu samples show high Pb isotopic ratios, similar to the Tethyan basalts, whereas the Yaxuanqiao samples plot in the field of the global pelagic sediments. The geochemical and Sr-Nd-Pb isotopic characteristics suggest that the Wusu basalts originated from a MORB-like source metasomatised by slab-derived fluids, while the Yaxuanqiao rocks have a fluid-modified MORB source with the input of subducted sediments. The geochemical affinity to both MORB- and arc-like sources, together with other geological observations, appears to support the development of a Permian arc-back-arc basin along the Ailaoshan-Song Ma tectonic zone in response to the northward subduction of the Paleotethys main Ocean. The final closure of the arc-back-arc basin took place in the uppermost Triassic due to the diachronous amalgamation between the Yangtze and Simao-Indochina Blocks.

Fan, Weiming; Wang, Yuejun; Zhang, Aimei; Zhang, Feifei; Zhang, Yuzhi

2010-10-01

134

Reservoir characterization of a Permian Slope Fan/basin-floor fan complex: Cherry Canyon Formation, Ward County, Texas  

Energy Technology Data Exchange (ETDEWEB)

The Cherry Canyon Formation consists of a 925-ft- (280-m) thick section of up to 25 different sandstone and siltstone units that were deposited in a deep-water environment in the Delaware basin. Lowstand sedimentation by fluid density currents with periodic turbidity currents resulted in a broad-migrating channelized slope fan/basin-floor fan complex interpreted to exhibit an intricate reservoir geometry. Thirteen lithofacies are identified. Primary reservoirs are found in massive channel sandstones, and beds of lesser reservoir quality are present in laminated overbank/interchannel sandstones. Original depositional fabric modified by diagenetic cements and authigenic clays created three petrophysical rock types. Type I reservoirs contain intergranular macroporosity relatively free of carbonate cement and authigenic clay. Types II and III reservoirs contain mesoporosity and abundant microporosity created by moderate to abundant carbonate cementation and plugging of pore throats by authigenic grain-coating chlorite and pore-bridging fibrous illite. Depositional and diagenetic factors combine with insufficient oil column height to yield low initial oil saturations that decrease with depth in a hydrocarbon-water transition zone. Mercury injection capillary pressure measurements illustrate the vertical stratification of petrophysical rock types that exist in the section; reservoirs which contain all water are interbedded with reservoirs containing mostly oil. Subsequently, a slight change in height above free water can drive production from all water to all oil. Hydrocarbon column heights greater than 60 ft are required to establish water-free oil production. Accurate reservoir water saturations can be derived using Archie's equation; when combined with a movable oil analysis and drainage relative permeability/fractional flow curves, initial water cuts can be predicted to maximize deliverability.

Spain, D.R. (Amoco Production Co., Houston, TX (USA))

1990-05-01

135

Sr evolution in the Upper Permian and Lower Triassic carbonates, northeast Sichuan basin, China: Constraints from chemistry, isotope and fluid inclusions  

International Nuclear Information System (INIS)

Petrographic features, C, O and Sr isotopes, rare earth and trace elements were determined, and fluid inclusions were analyzed on various stages of interparticle cements and vug-fillings from the Upper Permian and Lower Triassic sour reservoirs in northeastern Sichuan basin. The aim was to assess the origin and evolution of palaeo-waters in the carbonates. The original water was contemporary seawater, from which marine cements precipitated with slightly high Sr contents (mean 1911 ppm), 87Sr/86Sr ratios from 0.7067 to 0.7082 and nonluminescent CL. The palaeo-seawater was diluted by meteoric water, as indicated by bright cathodoluminescence (CL) and Sr-depletion (0–516 ppm) in low-temperature calcite. When buried to temperatures of about 60–90 °C during Middle to Late Triassic, the palaeo-water was enriched in Sr released from the transformation of precursor aragonite and calcite to dolomite, resulting in precipitation of substantial pre-bitumen Sr-rich minerals (SrSO4 and SrCO3). For un-dolomitized limestone sections, aragonite neomorphism may have contributed Sr to the precipitation of small amounts of Sr-bearing minerals and calcite crystals with elevated homogenization temperatures (HTs, mainly from 90 to 130 °C) and wide Sr contents (from 34 to 3825 ppm), as recorded in stage III calcite. Since the Middle Jurassic, almost all of the early stage celestite and significant amounts of solid CaSO4 have been cf solid CaSO4 have been consumed by reactions with hydrocarbons (i.e., TSR), resulting in water enriched in isotopically light CO2 and HCO3-,Sr2+,Ba2+ and Eu2+, as recorded in calcite with low ?13C values (down to ?18.9‰), 87Sr/86Sr ratios from 0.7072 to 0.7076, high HTs (mainly 110–198 °C), positive Eu anomalies and high Sr and Ba contents. Subsequently, the water was uplifted and cooled down to about 115 °C, celestite and strontianite were precipitated with the occurrence of natural elemental S immiscible inclusions. TSR may have produced significant amounts of freshwater, which brought down Sr concentrations and salinities of the palaeo-waters to not more than about 6.0 wt.% NaCl equivalent.

136

Variable eruptive styles in an ancient monogenetic volcanic field: examples from the Permian Levín Volcanic Field (Krkonoše Piedmont Basin, Bohemian Massif  

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Full Text Available The Permian pyroclastic deposits of the Levín Volcanic Field within the Krkonoše Piedmont Basin were studied in terms of volcanology. Pyroclastic rocks are exposed in two quarries and the study was supported with the 30 m deep borehole K1 penetrating these rocks. The pyroclastic rocks are altered but preserved textures enabled reconstruction of eruptive styles. The volcanic sequence exposed in the abandoned Hv?zda quarry starts with a phreato-Strombolian pyroclastic rocks rich in basaltic scoriae, cuspate glass shards, armoured- and accretionary lapilli overlain with mafic lava. Subsequent activity was phreatomagmatic in style and produced fall-out of accretionary lapilli and accumulation of base surge deposits. Overlying subhorizontally bedded matrix-supported pyroclastic deposits are rich in scoria and contain spindle-shaped bombs. These rocks are interpreted as mafic pyroclastic flow deposits related to Strombolian eruptions. A similar succession capped by scoriaceous fall-out deposit was documented in the K1 borehole. A coherent mafic volcanic rock (lava or sill terminates the succession exposed in the Hv?zda quarry.
Agglutinates at the base of the Studenec quarry were produced during Hawaiian eruptions building up a spatter cone. The cone most probably dammed a stream and created an ephemeral lake. Increasing influence of water on eruptive styles is documented in overlying pyroclastic deposits of phreatomagmatic eruptions. Subsequent lava flowed into the lake. Quenching of the lava resulted in formation of pillows enclosed in hyaloclastite breccia. Further up in the exposure, transition of pillow lava to massive lava has been recognized. Overlaying pyroclastic deposits are matrix-supported and rich in scoria and spindle-shaped bombs. Similarly to the Hv?zda quarry, these are interpreted as mafic pyroclastic flow deposits.
Volcanic activity in the Levín Volcanic Field was characterized by Hawaiian, Strombolian, phreato-Strombolian and phreatomagmatic eruptions accompanying lava effusions and possibly sills emplacement. The lavas were emitted in both subaerial and subaquatic conditions. The character and distribution of volcaniclastic facies suggests existence of several monogenetic volcanoes.

Stárková M

2011-07-01

137

TSR versus non-TSR processes and their impact on gas geochemistry and carbon stable isotopes in Carboniferous, Permian and Lower Triassic marine carbonate gas reservoirs in the Eastern Sichuan Basin, China  

Science.gov (United States)

The Palaeozoic and lowermost Mesozoic marine carbonate reservoirs of the Sichuan Basin in China contain variably sour and very dry gas. The source of the gas in the Carboniferous, Permian and Lower Triassic reservoirs is not known for certain and it has proved difficult to discriminate and differentiate the effects of thermal cracking- and TSR-related processes for these gases. Sixty-three gas samples were collected and analysed for their composition and carbon stable isotope values. The gases are all typically very dry (alkane gases being >97.5% methane), with low (sour while the Lower Triassic gas tends to be most sour. The elevated H2S (up to 62%) is due to thermochemical sulphate reduction with the most sour Triassic and Permian reservoirs being deeper than 4800 m. The non-TSR affected Carboniferous gas is a secondary gas that was derived from the cracking of sapropelic kerogen-derived oil and primary gas and is highly mature. Carboniferous (and non-sour Triassic and Permian) gas has unusual carbon isotopes with methane and propane being isotopically heavier than ethane (a reversal of typical low- to moderate-maturity patterns). The gas in the non-sour Triassic and Permian reservoirs has the same geochemical and isotopic characteristics (and therefore the same source) as the Carboniferous gas. TSR in the deepest Triassic reservoirs altered the gas composition reaching 100% dryness in the deepest, most sour reservoirs showing that ethane and propane react faster than methane during TSR. Ethane evolves to heavier carbon isotope values than methane during TSR leading to removal of the reversed alkane gas isotope trend found in the Carboniferous and non-sour Triassic and Permian reservoirs. However, methane was directly involved in TSR as shown by the progressive increase in its carbon isotope ratio as gas souring proceeded. CO2 increased in concentration as gas souring proceeded, but typical CO2 carbon isotope ratios in sour gases remained about -4‰ V-PDB showing that it was not solely derived from the oxidation of alkanes. Instead CO2 may partly result from reaction of sour gas with carbonate reservoir minerals, such as Fe-rich dolomite or calcite, resulting in pyrite growth as well as CO2-generation.

Liu, Q. Y.; Worden, R. H.; Jin, Z. J.; Liu, W. H.; Li, J.; Gao, B.; Zhang, D. W.; Hu, A. P.; Yang, C.

2013-01-01

138

Early Permian post-glacial bivalve faunas of the Itararé Group, Paraná Basin, Brazil: Paleoecology and biocorrelations with South American intraplate basins  

Science.gov (United States)

The uppermost portion of the Taciba Formation, Itararé Group, Paraná Basin, Brazil, records a succession of depositional environments tied to the demise of late Paleozoic glaciation. In the study area, Teixeira Soares county, state of Paraná, the unit is dominated by massive to laminated diamictites with inclusions of sandstones and other coarse-grained lithotypes, representing re-sedimented material in proximal areas. These are succeeded by fine to medium-grained sandstones with tabular cross-stratification and pectinid-rich shell pavements, interpreted as nearshore deposits. Above this, laminated and intensely bioturbated siltstones with closed articulated bivalve shells are recorded, probably deposited in inner shelf settings. Fine to very fine sandstones/siltstones with hummocky cross-stratification and intercalated mudstones, including infaunal in situ shells, are interpreted as stacked storm deposits, generated in distal shoreface environments. These are succeeded by fossil-poor, massive to laminated siltstones/mudstones or gray shales (=Passinho shale) that are inferred to be outer shelf deposits, generated in organic-rich, oxygen-deficient muddy bottoms. In this sedimentary succession dropstones or ice-rafted debris are missing and locally the Passinho shale marks the maximum flooding surface of the Itararé succession. These are capped by the fluvio-deltaic deposits of the Rio Bonito Formation (Sakmarian-Artinskian). Six facies-controlled, bivalve-dominated assemblages are recognized, representing faunal associations that thrived in aerobic to extreme dysaerobic bottoms along a nearshore-offshore trend. Within these assemblages, nineteen bivalve species (three of them new) were recorded and described in detail. The presence of Myonia argentinensis (Harrington), Atomodesma (Aphanaia) orbirugata (Harrington) and Heteropecten paranaensis Neves et al. suggests correlation with bivalve assemblages of the Eurydesma-bearing Bonete Formation, Pillahuincó Group, Sauce Grande-Colorado Basin (Buenos Aires Province), Argentina, indicating a possible Asselian age for this diverse post-glacial bivalve fauna. Despite that, typical members of the icehouse-style Eurydesma-Trigonotreta biota (stricto sensu) have not yet been found in the studied bivalve assemblages.

Neves, Jacqueline Peixoto; Anelli, Luiz Eduardo; Simões, Marcello Guimarães

2014-07-01

139

SHRIMP chronology of the Magallanes Basin basement, Tierra del Fuego: Cambrian plutonism and Permian high-grade metamorphism / Geocronología SHRIMP del basamento de la Cuenca de Magallanes, Tierra del Fuego: plutonismo Cámbrico y metamorfismo Pérmico de alto grado  

Scientific Electronic Library Online (English)

Full Text Available SciELO Chile | Language: English Abstract in spanish Cinco nuevas edades radiométricas logradas mediante análisis U-Pb en circón utilizando el SHRIMP, fueron determinadas en gneises y rocas plutónicas foliadas obtenidas desde el fondo de pozos de sondajes en la Cuenca de Magallanes y pertenecientes al denominado Complejo ígneo y Metamór-fico de Tierra [...] del Fuego. En tres de las muestras fueron calculadas edades del Cámbrico Temprano (523±7 Ma, 522±6 Ma y 538±6 Ma), interpretadas como edades de cristalización ígnea de las rocas estudiadas. Un gneis migmatítico presenta 'peaks' de circones heredados de ca. 950-1.100 Ma y de 560-650 Ma además de dos granos de edades de 525 Ma, indicando la participación de material Grenviliano y Brasiliano en el protolito de la migmatita cámbrica. Un gneiss de cordierita-sillimanita-granate presenta una población de circones ígneos de edad cámbrica y otro grupo de circones metamórficos, ricos en U, de edad pérmica, indicando que en el Pérmico un evento metamórfico del alto grado acompañado de anatexis (P=2-3 kbar, T=730-770°C) afectó a rocas ígneas cámbricas y/o a rocas sedimentarias derivadas de ellas. Rocas plutónicas cámbricas/ediacaranas han sido descritas en el NW de Argentina, en los basamentos de la Sierra de la Ventana y del Cinturón Plegado del Cabo (en el sur de África), y en el Orógeno de Ross en Antartica. El evento metamórfico Pérmico es contemporáneo con la deformación y metamorfismo de bajo grado, registrado en las sucesiones sedimentarias que sobreyacen el basamento en muchas de estas areas. Siguiendo al episodio Pérmico de metamorfismo de alto grado, en Tierra del Fuego fueron removidos al menos 8 a 12 km de rocas de cobertura antes de la depositación de las rocas volcánicas de la Formación Tobífera en el Jurásico Medio y Superior. Las rocas erosionadas representan una fuente importante de material para las sucesiones conglomerádicas pérmicas y triásicas? ubicadas en las regiones vecinas de América del Sur, África y Antartica. Abstract in english Five new SHRTMP U-Pb zircon ages are reported for gneisses and foliated plutonic rocks belonging to the Tierra del Fuego igneous and metamorphic basement complex (TFIMC), obtained from the bottom of borehole cores through the Magallanes Basin. Three of the samples yielded weighted mean 206Pb/238U ag [...] es (523±7 Ma, 522±6 Ma and 538±6 Ma), interpreted as indicating Early Cambrian igneous crystallization of the host rocks. A migmatitic gneiss shows peaks at ca. 950-1,100 Ma and 560-650 Ma from inherited zircon grains in addition to two grains with ages of ca. 525 Ma, suggesting involvement of Grenvillian and Brasiliano material in the protolith of a Cambrian migmatite. A cordierite-sillimanite-garnet gneiss contains igneous zircons of Cambrian age and a population of U-rich metamorphic Permian zircons, indicating that a Permian high-grade metamorphic and anatectic (P=2-3 kbar, T=730-770°C) event affected the Cambrian igneous rocks or sedimentary rocks derived from them. Cambrian/Ediacaran plutonic rocks are known from the basement of NW Argentina, the Sierra de la Ventana, the Cape Fold Belt in South Africa, and the Ross Orogen in Antarctica. The Permian metamorphic event is coeval with the deformation and low-grade metamorphism of the sedimentary successions that overlie the basement in many of these areas. In Tierra del Fuego at least 8 to 12 km of cover rocks were removed following the high-grade Permian metamorphic episode and the unconformable deposition of the Tobífera Formation volcanic rocks in the Middle to Late Jurassic. This eroded cover could nave been an important source of detritus for the conglomeratic Permian and Triassic? Successions of neighboring regions in South America, Africa and Antarctica.

Francisco, Hervé; Mauricio, Calderón; C. Mark, Fanning; Stefan, Kraus; Robert J, Pankhurst.

2010-07-01

140

SHRIMP chronology of the Magallanes Basin basement, Tierra del Fuego: Cambrian plutonism and Permian high-grade metamorphism Geocronología SHRIMP del basamento de la Cuenca de Magallanes, Tierra del Fuego: plutonismo Cámbrico y metamorfismo Pérmico de alto grado  

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Full Text Available Five new SHRTMP U-Pb zircon ages are reported for gneisses and foliated plutonic rocks belonging to the Tierra del Fuego igneous and metamorphic basement complex (TFIMC, obtained from the bottom of borehole cores through the Magallanes Basin. Three of the samples yielded weighted mean 206Pb/238U ages (523±7 Ma, 522±6 Ma and 538±6 Ma, interpreted as indicating Early Cambrian igneous crystallization of the host rocks. A migmatitic gneiss shows peaks at ca. 950-1,100 Ma and 560-650 Ma from inherited zircon grains in addition to two grains with ages of ca. 525 Ma, suggesting involvement of Grenvillian and Brasiliano material in the protolith of a Cambrian migmatite. A cordierite-sillimanite-garnet gneiss contains igneous zircons of Cambrian age and a population of U-rich metamorphic Permian zircons, indicating that a Permian high-grade metamorphic and anatectic (P=2-3 kbar, T=730-770°C event affected the Cambrian igneous rocks or sedimentary rocks derived from them. Cambrian/Ediacaran plutonic rocks are known from the basement of NW Argentina, the Sierra de la Ventana, the Cape Fold Belt in South Africa, and the Ross Orogen in Antarctica. The Permian metamorphic event is coeval with the deformation and low-grade metamorphism of the sedimentary successions that overlie the basement in many of these areas. In Tierra del Fuego at least 8 to 12 km of cover rocks were removed following the high-grade Permian metamorphic episode and the unconformable deposition of the Tobífera Formation volcanic rocks in the Middle to Late Jurassic. This eroded cover could nave been an important source of detritus for the conglomeratic Permian and Triassic? Successions of neighboring regions in South America, Africa and Antarctica.Cinco nuevas edades radiométricas logradas mediante análisis U-Pb en circón utilizando el SHRIMP, fueron determinadas en gneises y rocas plutónicas foliadas obtenidas desde el fondo de pozos de sondajes en la Cuenca de Magallanes y pertenecientes al denominado Complejo ígneo y Metamór-fico de Tierra del Fuego. En tres de las muestras fueron calculadas edades del Cámbrico Temprano (523±7 Ma, 522±6 Ma y 538±6 Ma, interpretadas como edades de cristalización ígnea de las rocas estudiadas. Un gneis migmatítico presenta 'peaks' de circones heredados de ca. 950-1.100 Ma y de 560-650 Ma además de dos granos de edades de 525 Ma, indicando la participación de material Grenviliano y Brasiliano en el protolito de la migmatita cámbrica. Un gneiss de cordierita-sillimanita-granate presenta una población de circones ígneos de edad cámbrica y otro grupo de circones metamórficos, ricos en U, de edad pérmica, indicando que en el Pérmico un evento metamórfico del alto grado acompañado de anatexis (P=2-3 kbar, T=730-770°C afectó a rocas ígneas cámbricas y/o a rocas sedimentarias derivadas de ellas. Rocas plutónicas cámbricas/ediacaranas han sido descritas en el NW de Argentina, en los basamentos de la Sierra de la Ventana y del Cinturón Plegado del Cabo (en el sur de África, y en el Orógeno de Ross en Antartica. El evento metamórfico Pérmico es contemporáneo con la deformación y metamorfismo de bajo grado, registrado en las sucesiones sedimentarias que sobreyacen el basamento en muchas de estas areas. Siguiendo al episodio Pérmico de metamorfismo de alto grado, en Tierra del Fuego fueron removidos al menos 8 a 12 km de rocas de cobertura antes de la depositación de las rocas volcánicas de la Formación Tobífera en el Jurásico Medio y Superior. Las rocas erosionadas representan una fuente importante de material para las sucesiones conglomerádicas pérmicas y triásicas? ubicadas en las regiones vecinas de América del Sur, África y Antartica.

Francisco Hervé

2010-07-01

141

A first record of late Middle Permian actinopterygian fish from Anatolia, Turkey  

Science.gov (United States)

The Middle-Upper Permian of the Gomaniibrik Formation, of the Tanin Group, in south-east Anatolia, close to the Iraq border, yielded moderately preserved fish remains. Two species, Palaeoniscum freieslebeni and Pygopterus cf. nielseni, known so far only from the Upper Permian deposits of the Zechstein Basin in western Central Europe, were recognised. This late Middle Permian Anatolian record significantly widens the geographical range of these actinopterygians into the equatorial Palaeotethys Realm.

Ho?gör, Izzet; Štamberg, Stanislav

2014-06-01

142

Lithofacies of the Irati formation in the FP-01-PR borehole (Permian, eastern border of the Parana basin); Litofacies da Formacao Irati no furo de sondagem FP-01-PR (Permiano, borda leste da Bacia do Parana)  

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The Irati Formation (Passa Dois Group, Permian, Parana Basin) is being analyzed in the borehole FP-01-PR of the CPRM Company (UTM cord. 3845.00N/562.000E, at the altitude of 513 m), in Congonhinhas (PR). This study presents the petrographic results and the columnar section of the borehole, including some discussions about the lithostratigraphic boundaries. Although the Irati Formation has been exhaustively studied, some new aspects have been observed, especially for the 22.5 m thick Taquaral Member at the lower part of the Formation. This Member presents three discrete upward coarsening shale cycles, the middle of which grades to sandy heterolithic rocks with wavy bedding, overlain by fine bivalve coquinas. There are no previous records of moluscan bivalves for the Taquaral Member. The Assistencia Member, 21.5 m thick in the borehole, is similar to the successions of the Northeastern Parana Basin, but thinner, composed of micritic ritmites and alternated micrites and betuminous shales, with mesosaurs in its upper half. All micrites are impure, indicating that siliciclastic contributions were continuous. Another important aspect is the occurrence of fine breccias with fish remains at the lower and upper boundaries of the Formation, suggesting that they correspond to unconformities. (author)

Rohn, Rosemarie [UNESP, Rio Claro, SP (Brazil). Dept. de Geologia Aplicada]. E-mail: rohn@rc.unesp.br; Lages, Leandra Costa [UNESP, Rio Claro, SP (Brazil). Geologia Regional

2003-07-01

143

Petrographic report on clay-rich samples from Permian Unit 4 salt, G. Friemel No. 1 well, Palo Duro Basin, Deaf Smith County, Texas: unanalyzed data  

International Nuclear Information System (INIS)

This report presents the results of mineralogic and petrographic analyses performed on five samples of clay-rich rock from salt-bearing Permian strata sampled by drill core from G. Friemel No. 1 Well, Deaf Smith County, Texas. Five samples of clay-rich rock from depths of about 2457, 2458, 2521, 2548, and 2568 feet were analyzed to determine the amounts of soluble phase (halite) and the amounts and mineralogy of the insoluble phases. The amounts of halite found were 59, 79, 47, 40, and 4 weight percent, respectively, for the samples. The insoluble minerals are predominately clay (20 to 60 volume percent) and anhydrite (up to 17 volume percent), with minor (about 1.0%) and trace amounts of quartz, dolomite, muscovite, and gypsum. The clays include illite, chlorite, and interstratified chlorite-smectite. The results presented in this petrographic report are descriptive, uninterpreted data. 2 references, 7 tables

144

News Palynology data of the basal section of Formacion San Gregorio located in Paso de las Bochas (I lower permian north basin, Uruguay  

International Nuclear Information System (INIS)

Samples from outcrops and concretions of the locality of Paso de las Bochas on the Negro River, provided new palynologycal data to the basal section of the San Gregorio Formation. At least 10 new ta xa are added for San Gregorio concretions, and some of the cited palynomorphs are mentioned for the first time for Uruguay (Rattiganispora minor, Waltzispora pol ita). Moreover, some of the found ta xa have been mentioned for glacial deposits related to the Carboniferous-Permian boundary in other Gondwana regions (p.e. Psomospora detect a, Waltzispora pol ita). The preliminary results reached here allow to admit the hypothesis of the existence of carboniferous dee posits on the Uruguayan territory whose were eroded or not yet recognized. Keywords: San Gregorio Formation, Carboniferous

145

Spectral gamma-ray signature of fluvial deposits: a case study from the Late Permian Rio do Rasto Formation, Paraná Basin, Brazil  

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Full Text Available Fluvial channel-fill deposits form highly heterogeneous hydrocarbon reservoirs. The study of outcrop analogs can help in the characterization of these heterogeneities, which are usually not detected by subsurface geophysical methods. The aim of this research is to compare outcrop log signatures with grain size trends and depositional elements of the fluvial deposits of the Late Permian Rio do Rasto Formation. A series of vertical gamma-ray logs were assembled in two outcrops in order to: 1 characterize log-facies in a succession composed of alternated flood plain, channel fill and eolian strata; 2 define within-channel spectral gamma-ray variability of a mixed-load composite point bar deposit and its relationship with grain size trends and lithofacies; 3 correlate log signatures observed in the outcrop sections with deep exploratory wells drilled several tens of kilometers from the study area. The results of this study show that gamma-ray logs have good correlation with grain size trends and that different depositional elements have distinct signatures. On the other hand, point bar deposits exhibit strong lateral changes in log signature due variations in grain size and mud content within lateral accretion strata. Although frequent, the classic bell-shaped log motif was not always detected, which means that the amount of fluvial channel-fill deposits recognized in subsurface can be underestimated. Similar log signatures were detected in the boreholes, at least in the closest ones, helping in paleoenvironmental interpretation in the subsurface.

Guilherme Arruda Sowek

2013-09-01

146

Spectral gamma-ray signature of fluvial deposits: a case study from the Late Permian Rio do Rasto Formation, Parana Basin, Brazil  

International Nuclear Information System (INIS)

Fluvial channel-fill deposits form highly heterogeneous hydrocarbon reservoirs. The study of outcrop analogs can help in the characterization of these heterogeneities, which are usually not detected by subsurface geophysical methods. The aim of this research is to compare outcrop log signatures with grain size trends and depositional elements of the fluvial deposits of the Late Permian Rio do Rasto Formation. A series of vertical gamma-ray logs were assembled in two outcrops in order to: 1) characterize log-facies in a succession composed of alternated flood plain, channel fill and eolian strata; 2) define within-channel spectral gamma-ray variability of a mixed-load composite point bar deposit and its relationship with grain size trends and lithofacies; 3) correlate log signatures observed in the outcrop sections with deep exploratory wells drilled several tens of kilometers from the study area. The results of this study show that gamma-ray logs have good correlation with grain size trends and that different depositional elements have distinct signatures. On the other hand, point bar deposits exhibit strong lateral changes in log signature due variations in grain size and mud content within lateral accretion strata. Although frequent, the classic bell-shaped log motif was not always detected, which means that the amount of fluvial channel-fill deposits recognized in subsurface can be underestimated. Similar log signatures were detected in the boreholes, at least in the closest ones, helping in paleoenvironmental interpretation in the subsurface. (author)

147

Taphonomy of Condensed Shell Storm beds of the Teresina Formation in Rio Preto (State of Paraná, Middle Permian, Paraná Basin: Paleoenvironmental Implications  

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Full Text Available The deposits of the Permian Teresina Formation are mainly characterized by fi ne-grained siliciclastic rocks and centimetricintercalations of tempestites (bioclastic sandstones and coquinas. Despite the relevance of the bivalve-rich carbonate bedsof the Teresina Formation to paleoenvironmental studies, their taphonomy is still poorly studied. The fossil concentrationstudied in this work was found in a quarry in the city of Irati, Rio Preto district, Paraná State. The fossil concentration is locatedin the middle/upper portion of the unit, far from the top. The studied bed is a bioclastic, intraclastic, peloidal, grainstone/packstone, with abundant bivalve shell fragments, pelitic and micritic intraclasts, peloids, rare ooids and oncoids, as well aspermineralized of Lycophyta microphylles and fi sh scales. The grains of this carbonate concentration show: high degree oftime-averaging, variable degree of packing (dense to disperse, no sorting and chaotic orientation. Notably, the concentrationincludes a mixture of elements which are indicative of: a restrictive, low energy, carbonate environment (peloids, ooidsand oncoids; b subaerial environment surrounding the main body of water (Lycophyta microphylles and c quiet-waterenvironment punctuated by storm events, where the suspension-feeding bivalves thrived. At least four depositional eventscaused by storm fl ows were recorded. The amalgamated nature of the bed is a result of storm events in an intracratonic basinwith very low seafl oor slope and low rates of sedimentation and subsidence.

Jacqueline Peixoto Neves

2011-12-01

148

Isopach map of the interval from surface elevation to the top of the Pennsylvanian and Permian Minnelusa Formation and equivalents, Powder River basin, Wyoming and Montana  

Science.gov (United States)

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 1,480 of these wells that penetrate the Minnelusa Formation and equivalents.

Crysdale, B.L.

1990-01-01

149

Map showing contours on the top of the Pennsylvanian and Permian Minnelusa Formation and equivalents, Powder River basin, Wyoming and Montana  

Science.gov (United States)

This map is one in a series of U.S. Geological Survey Miscellaneous Field Studies (MF) maps showing computer-generated structure contours, isopachs, and cross sections of selected formations in the Powder River basin, Wyoming and Montana. The map and cross sections were constructed from information stored in a U.S. Geological Survey Evolution of Sedimentary Basins data base. This data base contains picks of geologic formation and (or) unit tops and bases determined from electric resistivity and gamma-ray logs of 8,592 wells penetrating Tertiary and older rocks in the Powder River basin. Well completion cards (scout tickets) were reviewed and compared with copies of all logs, and formation or unit contacts determined by N. M. Denson, D.L. Macke, R. R. Schumann and others. This isopach map is based on information from 1,480 of these wells that penetrate the Minnelusa Formation and equivalents.

Crysdale, B.L.

1990-01-01

150

Contribution of research borehole data to modelling fine-grained turbidite reservoir analogues, Permian Tanqua-Karoo basin-floor fans (South Africa)  

Energy Technology Data Exchange (ETDEWEB)

Outcrop analogue studies can be augmented and constrained by drilling research wells through the same stratigraphic interval. Close-to-outcrop wells help to validate outcrop observations with well log and core data and thus improve the use of such data in actual field developments. Research wells located further away from the outcrops increase the spatial data coverage and can give important insight into regional facies distributions and net:gross changes. In the Tanqua-Karoo Basin (South Africa), seven wells were drilled into fine-grained sand-rich basin-floor fans and interfan mudstones to supplement outcrop data. Three close-to-outcrop wells proved useful in establishing characteristic log responses of the main architectural elements identified from the nearby outcrops. Lithofacies were correctly identified in more than 80% of cases using an artificial neural network. Borehole images provided detailed information on sedimentary structures, including a wealth of palaeocurrent data from climbing ripples that significantly enhanced the interpretations based only on outcrops. Wells sited away from the outcrops supplied information on lateral thickness and facies trends and intrafan stacking patterns, which helped to define the stratigraphic evolution of the fans. The combined data indicate that deposition was controlled in part by subtle basin-floor topography, and that intrafan lobe switching took place, leading to internal subdivisions that potentially caused effective compartmentalization of the basin-floor fan. (Author)

Luthi, Stefan M. [Delft Univ. of Technology, Dept. of Geotechnology, Delft (Netherlands); Hodgson, David M.; Flint, Stephen S. [Liverpool Univ., Dept. of Earth and Ocean Sciences, Liverpool (United Kingdom); Drinkwater, Nicholas J. [Schlumberger Cambridge Research, Cambridge (United Kingdom); Johannessen, Erik P. [Statoil, Stavanger (Norway); Geel, Cees R.; Goedbloed, Jan Willem

2006-07-01

151

geologic record of biogenic processes in fluviatile settings of semi-arid area (Carboniferous-Permian -; Krkonoše Piedmont Basin; Czech Republic.  

Czech Academy of Sciences Publication Activity Database

Prague : Faculty of Science, Charles University, 2004. s. 12. [Coal Geology Conference /10./. 07.06.2004-11.06.2004, Prague] Institutional research plan: CEZ:AV0Z3013912 Keywords : Krkonoše Piedmont Basin * biogenic processes fluviatile settings Subject RIV: DB - Geology ; Mineralogy

Mikuláš, Radek; Štolfová, K.

152

Sill-induced evaporite- and coal-metamorphism in the Tunguska Basin, Siberia, and the implications for end-Permian environmental crisis  

Science.gov (United States)

The emplacement of the Siberian Traps Large igneous province is regarded as the main processes behind the end-Permian environmental crisis. The details of this link are however still under investigation. Among the suggestions are lava degassing of mantle- and crustal-derived gases, explosive lava and phreatomagmatic eruptions, and gas release from contact metamorphism related to the sub-volcanic sill complex. Whereas the lava pile is relatively well studied and investigated, the sub-volcanic sills, dikes, and contact aureoles are poorly studied and documented. We present borehole and field data of sills and contact aureoles from across the Siberian Traps, from Norilsk in the north to Bratsk in the south. The data have been compiled during three field campaigns in 2004, 2006, and 2010. The sill geometries and thicknesses vary considerably from kilometer-scale intrusive complexes to individual thin sills of a few tens of meters. In contrast to several other LIPs, sills are also emplaced within the extrusive pile. Thick sills (up to 900 meters in thickness) occur in high abundance in the upper part of the sedimentary succession, affecting the coal-rich Tungusska Series sediments. Moreover, very thick sills (100-300 meters) are also emplaced within the vast Cambrian salt formations. Petrographic investigations of the metamorphic sediments demonstrate that widespread high temperature devolatilization took place. We show that depending on the specific location within the province and the emplacement depth, the potential for degassing of both greenhouse gases (CH4, CO2), aerosols (SO2), and ozone destructive gases (CH3Cl, CH3Br) was substantial and can explain the crisis.

Svensen, Henrik; Polozov, Alexander G.; Planke, Sverre

2014-05-01

153

An accurate record of volcanic ash fall deposition as characterized by dispersed organic matter in a Lower Permian tonstein bed (Faxinal Coalfield, Paraná Basin, Brazil)  

OpenAIRE

For the first time, the dispersed organic matter in the tonstein layer interbedded with a coal seam in the Faxinal Coalfield (Sakmarian, Southern Paraná Basin, Brazil) is characterized. The deposition of clusters of pollen grains was highly influenced by the intense ash fall process that probably occurred during seasonal dehiscence of reproductive structures. The well-preserved phytoclasts with their upper and lower leaf cuticles stuck together indicate that the rapid fall of ash on this mat...

Simas, M. W.

2013-01-01

154

Permian karst topography in the Wichita uplift, southwestern Oklahoma  

Energy Technology Data Exchange (ETDEWEB)

The Wichita uplift in southwestern Oklahoma is one part of a record of Pennsylvania and early Permian deformation that affected the Southern Oklahoma aulacogen. As a result of a partial inversion, the Lower Paleozoic section of this aulacogen was sequentially stripped off an uplift between the Wichita uplift and the Anadarko basin, resulting in the exposure of ultrabasic rocks deep in the Cambrian igneous fill of the aulacogen. Following the late Paleozoic tectonism, the topography of the uplift was entombed beneath Permian sediments and remained essentially undisturbed until exhumation during the present erosional cycle. Modern erosion is gradually exposing this topography, permitting morphometric analysis of the Permian hill forms. Because of the variation of lithology in the uplift, it is possible to isolate the effects of weathering processes such as intense hydrolysis of the igneous rocks (producing, among other features, or topography) and limestone dissolution, in the form of a surface and subsurface karst imprint. The latter process resulted in a network of small caves that are essentially fissures eroded along tectonic fractures. These small caves can be found in all the exposed areas of limestone. They are particularly noteworthy for three reasons: in at least five examples they contain a complex fauna of Permian vertebrates (mostly fragmentary), speleothems in some examples contain hydrocarbon inclusions, derived from the underlying Anadarko basin, some of the caves yield evidence of post burial evolution in the form of clay infiltration from the surface and brine flushing from the underlying Anadarko basin.

Donovan, R.N. Busbey, A.B. (Texas Christian Univ., Ft. Worth, TX (United States). Geology Dept.)

1993-02-01

155

Middle-Late Permian mass extinction on land  

Energy Technology Data Exchange (ETDEWEB)

The end-Permian mass extinction has been envisaged as the nadir of biodiversity decline due to increasing volcanic gas emissions over some 9 million years. We propose a different tempo and mechanism of extinction because we recognize two separate but geologically abrupt mass extinctions on land, one terminating the Middle Permian (Guadalupian) at 260.4 Ma and a later one ending the Permian Period at 251 Ma. Our evidence comes from new paleobotanical, paleopedological, and carbon isotopic studies of Portal Mountain, Antarctica, and comparable studies in the Karoo Basin, South Africa. Extinctions have long been apparent among marine invertebrates at both the end of the Guadalupian and end of the Permian, which were also times of warm-wet greenhouse climatic transients, marked soil erosion, transition from high- to low-sinuosity and braided streams, soil stagnation in wetlands, and profound negative carbon isotope anomalies. Both mass extinctions may have resulted from catastrophic methane outbursts to the atmosphere from coal intruded by feeder dikes to flood basalts, such as the end-Guadalupian Emeishan Basalt and end-Permian Siberian Traps.

Retallack, G.J.; Metzger, C.A.; Greaver, T.; Jahren, A.H.; Smith, R.M.H.; Sheldon, N.D. [University of Oregon, Eugene, OR (United States). Dept. of Geological Science

2006-11-15

156

A long geoclimatic record from the Permian  

Science.gov (United States)

A 260,000-year, continuous, annual geoclimatic time series has been compiled from the varved Permian Castile and Bell Canyon Formations of the Delaware Basin, southeastern New Mexico, and southwestern Texas. The last 200,000 years of the record was obtained from calcite-laminated anhydrite and anhydrite-laminated halite, which formed as a result of seasonal and annual deposition in the evaporite basin. The time series is based on measured thickness of individual varves. Analyses of calcium sulfate, calcium carbonate, and organic matter were made on 50-year intervals in the evaporite part of the sequence. Time series of the major components were examined by using smoothed graphic plots, variance spectra, and moving correlation coefficients. The longest oscillation recorded in the series that may be of climatic origin has a period of about 100,000 years. The calcium sulfate record contains 9-11 distinct oscillations with an average period of about 20,000 years. The strongest oscillation has a preferred spectral period of 2700 years and is recorded throughout the series as thickness changes in calcium sulfate, as events controlling halite deposition, and as episodes of basin freshening. A broad spectral response near a period of about 200 years reflects changes in sulfate, carbonate, and halite thickness. Shorter periods do not have consistent spectra. The time series contains no preferred periods that have not already been identified in previously described records. The climatic changes appear to be the result of a deterministic response to orbital effects at the longer periods and stochastic processes at the shorter periods. An unusually strong response near 2700 years is associated with episodic freshening of the basin. This period has been well established in the Holocene paleoclimatic record, and its presence in the Permian suggests a deterministic origin.

Anderson, Roger Y.

1982-08-01

157

Extinguishing a Permian World  

OpenAIRE

At the end of the Permian, ca. 252 Ma ago, marine and terrestrial fauna were facing the most extensive mass extinction in Earth history (Raup and Sepkoski, 1982). 80%–95% of all species on Earth, on land and in the oceans, became extinct (Benton et al., 2004) within an estimated time interval of less than 200 k.y. to 700 k.y. (Huang et al., 2011; Shen et al., 2011). Among the prominent Paleozoic animal groups that vanished are fusulinid foraminifera, rugose and tabulate co...

Schneebeli-hermann, E.

2012-01-01

158

Permian potentiometric analysis  

International Nuclear Information System (INIS)

Pacific Northwest Laboratory (PNL) was requested to analyze potentiometric data from the Wolfcamp Formation of the Permian System to evaluate the recommendations by the University of Texas/Bureau of Economic Geology (UT/BEG) that additional geohydrologic boreholes be drilled into the Wolfcamp. The UT/BEG recommended that two stratigraphic and two geohydrologic borings be drilled into the Permian System during FY83 and that several shallow hydrologic tests be made in the Dockum Formation. A geostatistical technique known as kriging was applied to objectively evaluate these geohydrologic borehole recommendations. The Deaf Smith County location appears to be an excellent choice for a borehole. No high quality potentiometric data are available from Deaf Smith County and a borehole location immediately upgradient from the candidate repository site is needed. Adding this borehole location to the potentiometric data base will significantly reduce field data uncertainty near the location being studied. The Swisher County location does not appear to be the best choice. High quality data values H2206 and H2360 are located immediately upgradient from the proposed repository site. The best placement of additional geohydrological boreholes in the Wolfcamp Formation depends strongly upon the proposed repository location. The variability of the potentiometric data causes estimation errors to rapidly increase away from locations of field measurements. Suggested locations for additional boreholes for the Deaf Smith investigations are in northwest Randall or central Potter Counties. Ideal borehole locations for the Swisher county studies appear to be in southeast Randall and Armstrong Counties

159

Permian potentiometric analysis  

Energy Technology Data Exchange (ETDEWEB)

Pacific Northwest Laboratory (PNL) was requested to analyze potentiometric data from the Wolfcamp Formation of the Permian System to evaluate the recommendations by the University of Texas/Bureau of Economic Geology (UT/BEG) that additional geohydrologic boreholes be drilled into the Wolfcamp. The UT/BEG recommended that two stratigraphic and two geohydrologic borings be drilled into the Permian System during FY83 and that several shallow hydrologic tests be made in the Dockum Formation. A geostatistical technique known as kriging was applied to objectively evaluate these geohydrologic borehole recommendations. The Deaf Smith County location appears to be an excellent choice for a borehole. No high quality potentiometric data are available from Deaf Smith County and a borehole location immediately upgradient from the candidate repository site is needed. Adding this borehole location to the potentiometric data base will significantly reduce field data uncertainty near the location being studied. The Swisher County location does not appear to be the best choice. High quality data values H2206 and H2360 are located immediately upgradient from the proposed repository site. The best placement of additional geohydrological boreholes in the Wolfcamp Formation depends strongly upon the proposed repository location. The variability of the potentiometric data causes estimation errors to rapidly increase away from locations of field measurements. Suggested locations for additional boreholes for the Deaf Smith investigations are in northwest Randall or central Potter Counties. Ideal borehole locations for the Swisher county studies appear to be in southeast Randall and Armstrong Counties.

Devary, J.L.

1983-09-01

160

Permian magmatism, Permian detachment faulting, and Alpine thrusting in the Orobic Anticline, southern Alps, Italy  

Science.gov (United States)

The Grassi Detachment Fault is located in the Orobic Alps east of Lake Como and was described by Froitzheim et al. (2008) as an Early Permian extensional structure. Many issues still remained unclear, like the exact timing of faulting and the extension from the well-exposed part of the detachment towards west. The Grassi Detachment Fault separates the Variscan Basement in its footwall from the volcanic and sedimentary rocks of the Early Permian Collio Formation within its hanging wall, marked by a mylonitic and cataclastic layer whose textures indicate top-to-the-southeast displacement. The footwall basement is formed by the Variscan Morbegno Gneiss and two granitic intrusions, the Val Biandino Quarz Diorite (VBQD) and the Valle Biagio Granite (VBG). The former is syntectonic with respect to the detachment, whereas for the latter, the relation to the detachment is unknown. The age of the VBQD is poorly defined as 312 Ma ± 48 Ma (Thöni et al. 1992); the VBG has not been dated. Volcanic rocks of the Collio Formation in the hanging wall may represent the extrusive part of the magmatic system. In our study area west of Val Biandino, several faults and shear zones are exposed: (1) The Grassi Detachment Fault is represented by mylonites and cataclasites with top-SE shear sense, between basement rocks and the Collio Volcanics. Towards NW, it is truncated by the unconformably overlying Late Permian Verrucano Lombardo. This may reflect the eroded culmination of a Permian metamorphic core complex. (2) A steeply NW-dipping, brittle normal fault is found further west in the footwall between VBQD and VBG. It is sealed by the basal unconformity of the Verrucano Lombardo and therefore should also be of Early Permian age (Sciunnach, 2001). It may represent an antithetic fault with respect to the detachment, accommodating the uplift of the magmatically inflated core complex. (3) The Biandino Fault is a steeply SE-dipping reverse fault, affecting also the Late Permian Verrucano Lombardo. It is therefore an Alpine structure. (4) Several south-directed Alpine thrusts duplicate the lithostratigraphy, including the detachment, and are related to the Orobic thrust further north. They also offset the Biandino Fault. U-Pb zircon ages measured with LA-ICP-MS (work in progress) will further clarify the temporal relations between the intrusions, volcanics, and the shear zones. Froitzheim, N., Derks, J.F., Walter, J.M. & Sciunnach, D. 2008. Evolution of an Early Permian extensional detachment fault from synintrusive, mylonitic flow to brittle faulting (Grassi Detachment Fault, Orobic Anticline, southern Alps, Italy) Geological Society, London, Special Publications, 298; 69-82. doi:10.1144/SP298.4 Thöni, M., Mottana, A., Delitala, M. C., De Capitani, L. & Liborio, G. 1992. The Val Biandino composite pluton: A late Hercynian intrusion into the South-Alpine metamorphic basement of the Alps (Italy). Neues Jahrbuch für Mineralogie-Monatshefte, 12, 545-554. Sciunnach, D. 2001. Early Permian palaeofaults at the western boundary of the Collio Basin (Valsassina, Lombardy). Natura Bresciana. Annuario del Museo Civico di Scienze Naturali, Brescia, Monografia, 25, 37-43.

Pohl, Florian; Froitzheim, Niko; Geisler-Wierwille, Thorsten; Schlöder, Oliver

2014-05-01

161

Residual basins  

International Nuclear Information System (INIS)

Exploration for uranium carried out over a major portion of the Rio Grande do Sul Shield has revealed a number of small residual basins developed along glacially eroded channels of pre-Permian age. Mineralization of uranium occurs in two distinct sedimentary units. The lower unit consists of rhythmites overlain by a sequence of black shales, siltstones and coal seams, while the upper one is dominated by sandstones of probable fluvial origin. (Author)

162

International correlation of Early Permian palynofloras from the Karoo sediments of Morupule, Botswana  

Energy Technology Data Exchange (ETDEWEB)

This paper is the first published account of Palaeozoic palynological assemblages from Botswana. Palynological assemblages of the lower Karoo Morupule Main Seam of the Morupule Colliery in Botswana are similar to those of the Striatopodocarpites fusus Biozone of the Collie Basin, Western Australia and the 3a Microfloral Biozone of the northern Karoo Basin, South Africa. This indicates an Aktastinian (Early Permian) age for the strata of Morupule. 34 refs., 7 figs., 1 tab.

Stephenson, M.H.; McLean, D. [University of Sheffield, Sheffield (United Kingdom). Dept. of Earth Sciences

1999-03-01

163

Permian tectonic framework and palaeogeography of SE Asia  

Science.gov (United States)

The principal continental lithospheric terranes, now comprising SE Asia and that existed in the Permian, are the South China/Indochina Super Terrane, and the Sibumasu, Simao, West Burma and SW Borneo/Semitau terranes. The Simao Terrane is here regarded a separate terrane, derived from South China by back-arc spreading in the Lower Carboniferous, rather than as an extension of Indochina. The main Palaeo-Tethys ocean in Thailand is identified as being represented by the Chiang Mai and Sra Kaeo sutures, and the eastern boundary of the Sibumasu Terrane is thus interpreted to lie farther west in Thailand than previously inferred. The Nan-Uttaradit Suture is interpreted as representing a marginal back-arc basin, and contiguous with the Ailaoshan and Jinshajiang sutures in SW China. The South China/Indochina Super Terrane, and the Simao Terrane were located within the Palaeo-Tethys in equatorial latitudes during the Permian, where they, together with North China, exhibit Cathaysian floras and faunas. The Sibumasu Terrane was located on the NW Australian margin of Gondwana until the Sakmarian. Major shifts in faunal affinities from Gondwana province faunas to an independent Sibumasu Province and then to assimilation into the Cathaysian Province, records the separation and rapid northward drift of Sibumasu after the Late Sakmarian. The principal Permian palaeogeographic models for the region are assessed for internal consistencies and conflicts.

Metcalfe, I.

2002-08-01

164

Permian basalts and trachytes from Esterel (SE France): a transitional tholeiitic suite emplaced during lithosphere thinning  

International Nuclear Information System (INIS)

Geochemical (major, trace and rare earth elements) and isotopic (143Nd/144Nd) compositions of lavas emplaced in the Esterel Massif (eastern Provence, France) at the end of the Permian allow to estimate the evolution of the continental lithosphere between the end of the Hercynian orogenesis and the beginning of the Tethyan rifting. Basalts from Agay basin and trachyte from Batterie des Lions belong to a transitional tholeiitic suite, characterized by negative Nb and Ta anomalies (relative to N-MORB) and homogeneous ?Nd(T=250Ma) ratios, close to the Bulk Earth. This suggests that the basalts from Agay basin and trachyte from Batterie des Lions derived from the partial melting of a mantle contaminated by lower continental crust. Maure Vieille trachytes differ from the differentiated rocks of the transitional suite by higher heavy rare earth abundances and ?Nd(T=250Ma) of +4/+5. These high ?Nd ratios suggest that the Maure Vieille trachytes could derive from the partial melting of a more depleted source, likely an asthenospheric mantle. The isotopic compositions of the Permian lavas from Esterel suggest the thinning (and perhaps the disappearance) of the lithospheric mantle which is associated at the surface with a NNW-SSE extension. The progressive change recorded in Agay basin from a stretching regime to a strike-slip regime may be related to the end of the lithospheric thinning and of the Permian magmatism. (authors) the Permian magmatism. (authors)

165

SHRIMP ages for Permian boundaries  

International Nuclear Information System (INIS)

The article in Newsletter 122 (pp. 25-27) by Australian workers on the value of SHRIMP dates issues a stout defence of that technique, and if it is a little on the optimistic side, must nonetheless educe hopes for the future. At present, SHRIMP radiometric values for the Permian Period are not consistent, even using the same team and same laboratory. (author). 10 refs

166

Subaqueous systems fed by glacially derived hyperpycnal flows: a depositional model for Carboniferous-Permian sandstones of the Itarare Group, Parana Basin; Sistemas subaquosos alimentados por fluxos hiperpicnais glaciogenicos: modelo deposicional para arenitos do Grupo Itarare, Permocarbonifero da Bacia do Parana  

Energy Technology Data Exchange (ETDEWEB)

The glacial Itarare Group constitutes the lower interval of the Carboniferous-Permian mega sequence in the Parana Basin. Thick glacially related sandstone reservoirs present in this unit contain gas and condensate sourced by Devonian marine shales. Based on outcrop data from the eastern basin margin, the sedimentary facies and stacking patterns were analyzed in order to propose a depositional model for these sandstone successions. It is suggested that the sandstones were deposited subaqueously as pro glacial fans due to melt water-derived highly concentrated hyperpycnal flows. Regional Itarare Group's stratigraphy can be expressed as several unconformity-bounded sequences deposited in a marine glaciated basin during repeated deglaciation episodes. The lower half of each sequence is constituted of thick sand-rich successions typically showing fining-upward and a retrogradational stacking pattern. Eleven facies were recognized, ranging from conglomerates to fine-grained sandstones, massive, graded or stratified. Conglomerates and cross-bedded coarse sandstones represent proximal Subaqueous deposits and were formed as ice-contact out wash fans/aprons due to melt water-derived hyper concentrated and concentrated flows and traction dominated bottom currents. These flows served as feeder systems to stratified, massive or graded turbiditic sandstone lobes deposited more distally. Parallel bedding and climbing ripples present in these beds were formed due to continuous aggradation from waxing and/or waning long-lived turbidity currents. These characteristics typify hyperpycnites and suggest that melt water derived hyperpycnal flows were the main trigger mechanisms to turbidity currents in the Itarare Group. (author)

Vesely, Fernando Farias [PETROBRAS, Rio de Janeiro, RJ (Brazil). E e P. Gerencia de Estratigrafia]. E-mail: vesely@petrobras.br

2006-11-15

167

An overview of the Permian (Karoo) coal deposits of southern Africa  

Energy Technology Data Exchange (ETDEWEB)

The coal deposits of southern African countries (Botswana, Malawi, Mozambique, Nambia, South Africa, Swaziland, Tanzania. Zambia and Zimbabwe) are reviewed. The coal seams formed during two periods, the Early Permian (Artinskian-Kungurian) and the Late Permian (Ufimian-Kazanian). The coals are associated with non-marine terrestrial elastic sedimentary sequences, most commonly mudrock and sandstones, assigned to the Karoo Supergroup. The Early Permian coals are mainly sandstone-hosted while the younger coals typically occur interbedded with mudstones. The sediments were deposited in varying tectono-sedimentary basins such as foreland, intracratonic rifts and intercratonic grabens and half-grabens. The depositional environments that produced the coal-bearing successions were primarily deltaic and fluvial, with sonic minor shoreline and lacustrine settings. Coals vary in rank from high-volatile bituminous to anthracite and characteristically have a relatively high inertinite component, and medium- to high-ash content.

Cairncross, B. [Rand Afrikaans University, Gauteng (South Africa). Dept Geology

2001-07-01

168

Fossil footprints from the Late Permian of Brazil: An example of hidden biodiversity  

Science.gov (United States)

Although Late Permian tetrapods are relatively common around the world, few taxa are known in rocks of this age in South America. So far, the study of the tetrapod paleofaunas in the Permian of Brazil has provided significant chronological data, though knowledge about them is still incipient. These studies generally take into account only body fossil records, but the ichnological record can provide new biostratigraphic elements for correlation. In Brazil, fossil tracks were first recorded in Rio do Rasto and Corumbataí Formations (Late Permian from Paraná Basin), but to date these tracks have not been studied in an ichnotaxonomic, morphofunctional, paleoenvironmental and chronological context. The study of these tracks became possible due to a considerable increase in the number of taxa from the Late Permian of Brazil, including Chelichnus isp. (Synapsida: Caseidae?), Procolophonichnium isp. (Procolophonoidea), Rhynchosauroides gangresci isp. nov. (basal Diapsida), Dicynodontipus penugnu isp. nov. (Dicynodontia) and Incertae sedis (Amphibia?). With the exception of Dicynodontia, the remaining recorded taxa are unknown through fossil skeletons, showing that the Brazilian Permian faunas were much more diverse than was previously reported and demonstrating the potential of South American fossil vertebrates for global correlations.

da Silva, Rafael Costa; Sedor, Fernando Antonio; Fernandes, Antonio Carlos Sequeira

2012-10-01

169

The last "pelycosaur": a varanopid synapsid from the Pristerognathus Assemblage Zone, Middle Permian of South Africa.  

Science.gov (United States)

We report on a partial varanopid skull and mandible from the Pristerognathus Assemblage Zone of the Beaufort Group, in the South African Karoo Basin, which is probably latest Middle Permian (Capitanian) in age. This mycterosaurine is not only the youngest known varanopid from the Southern Hemisphere, but it is also the youngest known "pelycosaur" (i.e., non-therapsid synapsid). Like all other members of this clade of hypercarnivores, the teeth are strongly flattened, recurved, and have finely serrated cutting edges. The anterior dentary teeth form a caniniform region, and the splenial features a foramen intermandibularis oralis, the first ever to be described in a "pelycosaur." The last varanopids were the smallest carnivores of latest Middle Permian continental faunas. Occupation of the small carnivore guild appears to have allowed varanopids to achieve a nearly cosmopolitan distribution throughout the Middle Permian, between the great Early Permian radiation of basal synapsids and the spectacular diversification of therapsid synapsids in the Late Permian and Early Triassic. PMID:22009069

Modesto, Sean P; Smith, Roger M H; Campione, Nicolás E; Reisz, Robert R

2011-12-01

170

Stratigraphy sequence analysis application for multi scalar characterization of paralic reservoirs - an example in the Guata group (E O-Permian) of the Parana Basin, in the state of Rio Grande do Sul, Brazil; Aplicacao da estratigrafia de sequencias para caracterizacao multiescalar de reservatorios paralicos - um exemplo no Grupo Guata (EO-Permiano) da Bacia do Parana, no Rio Grande do Sul, Brasil  

Energy Technology Data Exchange (ETDEWEB)

Detailed stratigraphic analysis of the Early Permian Rio Bonito and Palermo Formations of the Parana Basin in the region of Sao Gabriel County has been used for a study on reservoir characterization of paralic sandstones. Two main depositional systems were recognized, a fluvial-dominated delta system and a wave-dominated barrier island system. The succession is divided in two third-order depositional sequences, enclosing thirteen fourth-order para sequences. This high-resolution stratigraphic framework was the base for a multi scale approach on reservoir characterization of the sandstone bodies. Reservoir heterogeneities are discussed, staring from the scale of depositional sequence (heterogeneity level 1), passing down to heterogeneity at the scale of systems tracts (heterogeneity level 2) and finalizing with an approach at para sequence scale (heterogeneity level 3). Main control on heterogeneity at the first level is base-level variation as generating mechanism for un conformities at the sediment type and rate. At the second level, the reservoir heterogeneity is controlled by the lateral and vertical variations in thickness of particular systems within the different systems tracts, and at the third level, the heterogeneity occurs controlling reservoir continuity and connectivities between reservoirs. The study supplies a model which is useful as a predictive tool for similar geologic settings in producing oil fields. (author)

Kuechle, Juliano [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Geociencias. Curso de Pos-graduacao em Geociencias]. E-mail: juk666@zipmail.com.br; Holz, Michael [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Geociencias]. E-mail: michael.holz@ufrgs.br

2003-07-01

171

The inherent moisture content of South African Permian coals  

Energy Technology Data Exchange (ETDEWEB)

The inherent moisture content (IM) of coals impinges on many usages but little is known about the controls on this parameter in Gondwana coals. In the Permian coals of the main Karoo Basin the chief mediator of IM (on as as-received basis) is rank, which is determined by regional and contact metamorphism, independent of burial depth. Mineral matter content and maceral composition are ancillary controls. The relationship between IM and rank is inverse up to the anthracite/meta-anthracite boundary, where development of secondary porosity causes IM to rise sharply. Northern Transvaal coals deposited in structural basis separate from the main Karoo Basin are strongly deficient in IM relative to Northern Hemisphere coals of equivalent rank and type. Pressure generated by tectonism may explain this anomaly. 37 refs., 6 figs., 4 tabs.

Roberts, D.L.

1991-06-01

172

Early Permian intrusions in the Paleozoic sediments of the Eastern North Sea area  

DEFF Research Database (Denmark)

This study presents the geometry of Paleozoic intrusions in the Skagerrak area located at the northern flank of the Ringkøbing-Fyn High and suggests factors controlling the formation of the intrusions. The intrusions have here been mapped in detail using 3D seismic data. The study area is located in the Northern Permian Basin which in the eastern North Sea is separated from the Southern Permian Basin by the Ringkøbing-Fyn High. The Permian basins were initiated during thermal subsidence following a late Carboniferous- early Permian rifting phase associated with extensive igneous activity recorded across the entire North Sea Basin. The easternmost intrusions and extrusions have been associated to the “Skagerrak-Centered Large Igneous Province” that has an early Permian age of c. 297 Ma. Compared to the Southern Permian Basin which historically has been intensely investigated because of the known presence of hydrocarbons within the Paleozoic sediments, the Northern Permian Basin has gained much less interest outside the hydrocarbon producing Mesozoic graben systems. This is mainly due to an apparent lack of potential source rocks. A major E-W striking northward dipping fault system characterizes the study area and causes rotation of older probably Paleozoic sediments and creates syn-tectonic sediment wedges. The syn-tectonic wedges most probably contain volcaniclastic sediments of the Karl Formation or sandstones of the Auk Formation, but it cannot be excluded that the earliest late Permian Kupfershiefer which is a potential source rock, has local depositional maxima associated to the basement faults. Salt structures which have been periodically active during the post Paleozoic dominate the northern part of the study area. The Paleozoic intrusions observed in the hanging-wall segment of the E-W striking fault system are generally planar and strike parallel to the fault with a southward dip geometrically similar to antithetic faults. In contrast, the intrusions in the footwall segment show a much more complex pattern striking at a high angle to the E-W basement fault and outlining a sill complex, which in certain areas resembles a poorly outlined composite cone. The intrusions are not observed in the syn-tectonic sedimentary wedges and this combined with the general age of the intrusions suggests that the syn-tectonic wedges are of latest early Permian or earliest late Permian age. The study demonstrates Paleozoic intrusions with a systematic orientation and geometry that most likely was directly controlled by the basement faulting. Syn-tectonic hanging-wall deformation represented by antithetic fractures is suggested to be the most important controlling factor for the intrusions at the hanging-wall. At the footwall a more composite geometry of the intrusions is observed, resulting in a much more complex compartmentalization of the Paleozoic sediments due to intrusions compared to the hanging-wall segment. The intrusions and especially the compartmentalization must be taken into account during evaluation of the hydrocarbon potential of the Paleozoic.

Clausen, O.R.; Andresen, Katrine Juul

173

Structure and depositional environments of Permian-Triassic terrigeneous complex of the Barents Sea shelf  

Science.gov (United States)

Permian-Triassic complex of the Barents Sea shelf composed of up to 8-12 km of clastic sediments has a great interest for geology as it contains hydrocarbon-bearing reservoirs and source rocks. It is drilled on shelf margins and structural highs; it outcrops in adjoining archipelagos. However within depositional centers like the South-Barents basin where Permian-Triassic reaches maximum thickness and burial, its structure can only be understood from seismic data. We present an evaluation of structure, depositional environments and cyclicity of Permian-Triassic terrigeneous complex based on interpretation of 18 000 km of regional seismic profiles with record length of 10-12 s acquired by MAGE in 2007-09 in the south-east shelf. Transgressive-regressive sequences were identified and correlated using well log analysis for 17 wells, descriptions of well sections and outcrops in Franz Josef Land, Svalbard and Novaya Zemlya archipelagos. Cooling of the climate throughout Sakmarian-Artinskian (Lower Permian), marine transgression, and Ural orogeny in the south-east had interrupted carbonate deposition and initiated the deposition of terrigeneous (East Barents) and spiculite, siliceous-carbonate, and siliciclastic (West Barents) sediments (Geological history, 2009). Triassic is represented by clastic lithologies all over the basin. On seismic data lower boundary of Permian-Triassic complex is a high-amplitude reflector (Ia) and downlap surface corresponding to the top of Lower Permian carbonates. Upper boundary is related to Rhaetian erosional unconformity best pronounced in the pre-Novaya Zemlya foredeep, Kola monocline and Pechora Sea. Permian is represented by 5 transgressive-regressive sequences with upward regressive trend and total thickness of 100-800 m. Low-angle clinoforms prograding from south-east (Ural provenance) and east were interpreted on seismic. Increasing thickness of Permian towards Novaya Zemlya is consistent with up to 4 km of sediments in the archipelago's outcrops and indicates Kara provenance. In the south-eastern basin margin Permian-Triassic boundary is well-traced due to its erosional origin and downlapping of overlaying Induan clinoforms. Triassic sediments were formed in deltaic, shallow-marine to deep shelf environments in the large epicontinental basin with vast transgressions and significant lateral shift of the shoreline during sea level changes. Interpreted Triassic horizons correspond to Induan/Olenekian (top Havert), Lower/Upper Olenekian, Olenekian/Anisian (top Klappmyss) and Ladinian/Carnian boundaries. These relatively continuous reflectors were formed as transgressive shaly packages overlaid sequence boundaries. During Induan clinoforms (height ~100 s) had prograded to the north-west and west compensating the steady subsidence of the South- and North Barents depressions and pre-Novaya Zemlya foredeep. We traced migration of the clinoform break (platform margin) of several Induan prograding sequences across the South-Barents basin towards Norwegian Barents Sea, where the area of non-compensated deposition in deep shelf environments was delineated (Glorstad-Clark, 2010). During Olenekian and Middle Triassic the clinoform break persisted in the western shelf, thus no clinoforms are observed in the south-east of the Barents Sea where deltaic environments had prevailed. Late Triassic was characterized by shallowing of the basin, spreading of deltas and filling of previously non-compensated area in the north-west. Maximum thickness of Triassic is related to Lower Triassic within South Barents basin and Lower-Middle Triassic within the pre-Novaya Zemlya foredeep.

Norina, Daria; Stoupakova, Antonina

2014-05-01

174

The paleoclimate of the Kazanian (early Late Permian) world  

Energy Technology Data Exchange (ETDEWEB)

The Kazanian (early Late Permian, 258-253 m.y.) marked the onset of a unique interval in the Phanerozoic, distinguished by a classic end-member case of continental assembly, the megacontinent Pangaea. Compilation of biostratigraphic and lithofacies data indicate a warm, extensively arid world, largely ice free, and characterized by the onset of atmospheric conditions that were exceedingly stressful to the biosphere, the worst of the eon. Using Chevron's version of the Community Climate model, the authors report here on two Kazanian paleoclimate seasonal simulations, one using 200 ppm CO{sub 2} and the other with 2,000 ppm CO{sub 2}. The authors consider the knowledge of plate assembly back to the Permian accurate enough to allow employment of a seasonal model. Simulation of a warmer Earth with an elevated greenhouse effect (modeled as CO{sub 2}) fits the observed geology and isotope signals. The increased CO{sub 2} experiment warmed the entire planet with the greatest increases north of 50{degree} latitude and least changes in the tropics. The warming caused the poleward retreat of sea ice in both hemispheres. Precipitation and evaporation increased, but runoff was confined to areas of very intense rainfall. Monsoons are limited to the southern hemisphere, associated with the western Tethys sea and the eastern equatorial Panthalassa ocean. Extreme southeastern Pangaea (northern Australia) was a focus of precipitation throughout the year. Precipitation occurred in the higher latitudes (50-55{degree}) on the western coast, of Pangaea where storm tracks make landfall. High evaporation rates characterized the restricted Permian (US), Zechstein, and Perm (Soviet Union) basins, a time of evaporite, deposition. Interior Pangaea at middle to high latitudes endured frigid winters ({minus}40{degree}C) and torrid summers (60{degree}C).

Moore, G.T. (Chevron Oil Field Research Co., La Habra, CA (USA)); Peoples, C.J. (Texas A and M Univ., College Station (USA))

1990-05-01

175

Stratigraphy of the Carboniferous-Permian volcanosedimentary sequences of the Northern Pamir, Tajikistan  

Science.gov (United States)

The point of view on two angular unconformities in the section of the Lower Carboniferous volcanosedimentary sequences of the northern Pamir is disproved. Two terrigenous sequences in contrast to one Beleuli sequence of shales are present in the Beleuli River basin. The first Carboniferous sequence conformably overlaps limestones with Serpukhovian goniatites and the second Permian sequence may be correlated with the Pshikharv Formation of shales from the western regions of the northern Pamir and contacts by the thrust Carboniferous rocks.

Leven, E. Ja.

2013-11-01

176

Uppermost Permian ammonoids from northern Thailand  

Science.gov (United States)

Uppermost Permian (Dorashamian) ammonoids, Pseudogastrioceras aff. P. guangxiensis Zhao et al., Paratirolites nakornsrii sp. nov. and Xenodiscus? sp. occur in the Huai Thak Formation near Lampang, northern Thailand. The stratigraphical sequence of the Huai Thak and Phra That Formations appears to extend from the Permian into the Triassic without a break from field observations. The present faunule is found at a distinct stratigraphical horizon about 50 m below the occurrence of Triassic bivalve Claraia (Lower Scythian). An Uppermost Permian Palaeofusulina fauna-bearing limestone bed is also present in the same area of Doi Pha Phlung and represents a related heteropic facies of the ammonoid-shale bed. Paleontological evidence is thus available to establish the position of the boundary between the Permian and the Triassic in this province.

Ishibashi, Takeshi; Chonglakmani, Chongpan

177

Dalhart's only Permian field gets best oil well  

International Nuclear Information System (INIS)

This paper reports that activity is picking up in Proctor Ranch oil field in the northwestern Texas panhandle, the only Permian producing field in the lightly drilled Dalhart basin. During the last 2 1/2 months, the field has a new operator and a new producing well, the best of five drilled since discovery in 1990. Corlena Oil Co., Amarillo, acquired the field from McKinney Oil Co. in May and tested its first well in early July. The 1-64 Proctor, 18 miles west of Channing, pumped at rates as high as 178 bd of oil and 6 b/d of water from Permian Wolfcamp dolomite perforations at 4,016-29 ft. Corlena plans to drill another well south of the field soon. The lease requires that the next well be spudded by early November. The field appears to be combination structural-stratigraphic trap in which the dolomite pinches out against the Bravo Domes-Oldham nose to the west

178

Sedimentary evolution of Rio do Rastro formation (permian-triassic of the Parana Basin) at central south portion of Santa Catarina State, Brazil; Evolucao sedimentar da Formacao Rio do Rastro (Permo-Triassico da Bacia do Parana) na porcao centro sul do estado de Santa Catarina, Brasil  

Energy Technology Data Exchange (ETDEWEB)

Between the Late Carboniferous and the Early Triassic, the south portion of the Gondwana Supercontinent witnessed the development of intracratonic basins related with the coeval Sanrafaelic Orogeny. The continuous subsidence and consequent generation accommodation space resulted in the formation of a large confined water body and the accumulation of a transgressive regressive sequence between the Late Permian and the Early Triassic. The progradational nature of the upper portion of this sequence, represented by de Rio do Rasto e Piramboia formations, culminated with the complete filling of the water body. In the south-eastern portion of Santa Catarina State (Southern Brazil), the Rio do Rasto Formation overlies the Teresina formation and is overlain by the Piramboia formation, both contacts being characterized by lithological transition. The lower portion of the Rio do Rasto Formation is characterized by architectural elements deposited in offshore environments subject to storm action. A marked change of the color of the pelitic facies, from gray to red and purple occurs at the top of the unit. At this stratigraphic level, there is also a predominance of deltaic and eolian architectural elements. The intercalation of near shore and offshore architectural elements can be explained by the strong auto cyclic character expected in deltaic depositional systems and by the variation of relative rates of base-level rise. The occurrence of eolian architectural elements interbedded with subaquatically deposited sediments on the second third of the unit can be considered an evidence of continentalization to the top, materialized as the transition to the Piramboia desert system. (author)

Warren, Lucas Verissimo; Roldan, Luis Fernando; Steiner, Samar dos Santos; Chamani, Marlei Antonio Carrari [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Programa de Pos Graduacao em Geoquimica e Geotectonica]. E-mail: lvwarren@yahoo.com; Almeida, Renato Paes de; Hachiro, Jorge; Machado, Romulo [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias. Dept. de Geologia Sedimentar e Ambiental

2008-06-15

179

Palinologia das formações Rio Bonito e Palermo (Permiano Inferior, Bacia do Paraná) em Candiota, Rio Grande do Sul, Brasil: novos dados e implicações bioestratigráficas / Palynology of the Rio Bonito and Palermo formations (Lower Permian, Paraná Basin) in Candiota, Rio Grande do Sul, Brazil: new data and biostratigraphic implications  

Scientific Electronic Library Online (English)

Full Text Available SciELO Argentina | Language: Portuguese Abstract in portuguese Novos conjuntos palinológicos foram recuperados de um afloramento localizado às margens da BR 293, situado entre os municípios de Bagé e Candiota, sul do Estado do Rio Grande do Sul, correspondentes às formações Rio Bonito e Palermo, Permiano Inferior da Bacia do Paraná. Um total de oito amostras fo [...] i estudado, revelando palinofloras ricas e diversificadas, com a identificação de 76 espécies, dentre as quais 42 são relativas a esporos, 24 a grãos de pólen, e 10 relacionadas a algas e fungos. Em termos bioestratigráficos, palinomorfos documentados na seqüência sedimentar analisada permitiram identificar duas unidades bioestratigráficas na seção, as zonas Vittatina costabilis e Lueckisporites virrkiae. Algumas espécies de distribuição estratigráfica limitada a determinados níveis do Subgrupo Itararé e da Formação Rio Bonito foram registrados em posição estratigráfica mais superior, podendo sugerir, à primeira vista, aumento na amplitude estratigráfica destes táxons. Entretanto, outras implicações estratigráficas são também admitidas, e constituem parte da discussão da presente contribuição. Abstract in english New palynologic associations were recovered from an outcrop located at BR 293 Highway, between Bagé and Candiota municipalities, Rio Grande do Sul state, Brazil, related to the Rio Bonito and Palermo formations, Lower Permian of Paraná Basin. Eight samples were colected and studied, showing rich and [...] diversified palynofloras. A total of 76 species were recognized, 42 corresponding to spores, 24 to pollen grains and 10 related to algae and fungi. Palynomorphs registered in the section here analysed indicate the recognition of the Vittatina costabilis and Lueckisporites virrkiae zones. Species with stratigraphic ranges limitated to Itararé Subgroup and Rio Bonito Formation were identified in a higher stratigrapical levels, meaning for instance, increasing on the stratigraphic range of these taxa. On the other hand, other stratigraphic interpretations are possible, constituting the scope of the present contribution.

Ana L.O., Mori; Paulo A., Souza.

2010-03-30

180

SHRIMP chronology of the Magallanes Basin basement, Tierra del Fuego: Cambrian plutonism and Permian high-grade metamorphism Geocronología SHRIMP del basamento de la Cuenca de Magallanes, Tierra del Fuego: plutonismo Cámbrico y metamorfismo Pérmico de alto grado  

OpenAIRE

Five new SHRTMP U-Pb zircon ages are reported for gneisses and foliated plutonic rocks belonging to the Tierra del Fuego igneous and metamorphic basement complex (TFIMC), obtained from the bottom of borehole cores through the Magallanes Basin. Three of the samples yielded weighted mean 206Pb/238U ages (523±7 Ma, 522±6 Ma and 538±6 Ma), interpreted as indicating Early Cambrian igneous crystallization of the host rocks. A migmatitic gneiss shows peaks at ca. 950-1,100 Ma and 560-650 Ma from ...

Francisco Hervé; Mauricio Calderón; Mark Fanning, C.; Stefan Kraus; Pankhurst, Robert J.

2010-01-01

181

Mineralogical and isotopic data on two hydrothermal uranium deposits located in the Permian volcano-sedimentary basin of Collio Orobico (Bergamasc Alps): occurrence of a Cretaceous U mobilization phase  

International Nuclear Information System (INIS)

The U deposits of Novazza and Val Vedello are located close to the unconformity with the South-Alpine basement. The ignimbrites adjacent to the Novazza deposit have undergone a pervasive hydrothermal alteration. For this deposit, the study of the micas provides crystallization temperatures ranging from 5400C to 3500C. These micas do not show a zonal distribution with respect to the mineralized bodies. In the neighbouring barren basin, the mica crystallization temperatures at 2000C suggest a post-magmatic evolution very different. The U-Pb data on zircons were made for ignimbrites collected in the Novazza mine and in the barren basin. They allow to propose a multi-episodic evolution model taking into account a mixing of two populations of zircons: a small amount of Precambrian zircons located in basement xenoliths within the ignimbrites, and a large proportion of zircons having crystallized in the ignimbrites, which are supposed to have been emplaced about 280 My ago. The U-Pb data suggest a phase of U concentration, during Cretaceous times. For each deposit, this age does not seem to be related to the ages of fault motions. Different hypothesis concerning the genesis of Novazza and Val Vedello deposits are discussed which take into account the paleotemperature data on micas, the ore paragenesis and the U-Pb data obtained on U-mineralizations

182

Provincialization of terrestrial faunas following the end-Permian mass extinction.  

Science.gov (United States)

In addition to their devastating effects on global biodiversity, mass extinctions have had a long-term influence on the history of life by eliminating dominant lineages that suppressed ecological change. Here, we test whether the end-Permian mass extinction (252.3 Ma) affected the distribution of tetrapod faunas within the southern hemisphere and apply quantitative methods to analyze four components of biogeographic structure: connectedness, clustering, range size, and endemism. For all four components, we detected increased provincialism between our Permian and Triassic datasets. In southern Pangea, a more homogeneous and broadly distributed fauna in the Late Permian (Wuchiapingian, ?257 Ma) was replaced by a provincial and biogeographically fragmented fauna by Middle Triassic times (Anisian, ?242 Ma). Importantly in the Triassic, lower latitude basins in Tanzania and Zambia included dinosaur predecessors and other archosaurs unknown elsewhere. The recognition of heterogeneous tetrapod communities in the Triassic implies that the end-Permian mass extinction afforded ecologically marginalized lineages the ecospace to diversify, and that biotic controls (i.e., evolutionary incumbency) were fundamentally reset. Archosaurs, which began diversifying in the Early Triassic, were likely beneficiaries of this ecological release and remained dominant for much of the later Mesozoic. PMID:23630295

Sidor, Christian A; Vilhena, Daril A; Angielczyk, Kenneth D; Huttenlocker, Adam K; Nesbitt, Sterling J; Peecook, Brandon R; Steyer, J Sébastien; Smith, Roger M H; Tsuji, Linda A

2013-05-14

183

The Jurassic of Denmark and Greenland: Late Triassic – Jurassic development of the Danish Basin and the Fennoscandian Border Zone, southern Scandinavia  

OpenAIRE

The continental to marine Upper Triassic – Jurassic succession of the Danish Basin and the Fennoscandian Border Zone is interpreted within a sequence stratigraphic framework, and the evolution of the depositional basin is discussed. The intracratonic Permian–Cenozoic Danish Basin was formed by Late Carboniferous – Early Permian crustal extension followed by subsidence governed primarily by thermal cooling and local faulting. The basin is separated from thestable Precambrian Baltic Shiel...

Nielsen, Lars Henrik

2003-01-01

184

Radionuclides distribution in blooming of the permian sediments from the Irati Formation of the Parana Basin; Distribuicao de radionuclideos em um afloramento de sedimentos permianos da Formacao Irati na Bacia do Parana  

Energy Technology Data Exchange (ETDEWEB)

The objective of this work is to study natural radionuclides in sedimentary rocks. The concentration of them reflects the origin of the sediments, the depositional environment as well as some mineralogical characteristics of the rock matrix, and also more recent events as weathering and erosion. Using gamma ray high resolution spectrometry, the profile of activity concentration of the natural radionuclides was assessed for {sup 226}Ra, {sup 238}U, {sup 32}Th and {sup 40}K in rocks of the Irati Formation belonging to Parana Sedimentary Basin. The samples were collected at a limestone abandoned mine, in the city of Sapopema, (PR). 24 samples were collected, eleven from the exposed vertical profile with approximately 5.50 m, whose stratigraphy is represented by an alternation among decimetrics layers of limestones, bituminous shales, and some rhythmits layers (milimetric sheets of limestone and bituminous shales), 9 repetitions of a sample to study the variability, and three rigolits samples in sequential apprenticeships of weathering. Each sample was dried in the sun during about 48 hours, broken, drizzled in a sieve of 4 mesh and put, in a cylindrical container. The measures were accomplished using a Germanium Hyper Pure detector (HPGe) with relative efficiency of 66%, connected to a standard spectrometry electronic chain. The measured concentrations of activity of {sup 238}U were smaller for the limestones (17.80 {+-}0.09 Bq.Kg{sup -1}), larger for the bituminous shales (125.5 {+-} 2.6 Bq.Kg{sup -1} with enrichment of uranium in the sample (200), 548 {+-} 16 Bq.Kg{sup -1}, upper part of the column), and intermediate for the rhythmits (23.0 {+-} 1,3 Bq.Kg{sup -1}. The ratio eTh/K obtained for the studied profiles has equivalent values, indicating similar mineralogical characteristics for the limestones, bituminous shales, rhythmits and studied rigolits. On the other hand, to the ratio eTh/eU showed that two of the three regolits samples belong to oxidizer atmospheres, favoring the leaching of uranium, what can be causing the enrichment of the sample (200), once these soils are above the column. The average measured doses were 16 nGy.h{sup -1} for the limestones and rhythmits, 79.5 nGy.h{sup -1} for the bituminous shales and 329.5 nGy.h{sup -1} for the enriched bituminous shales of the top of the column. These results supply data to estimate the contribution of these products for the radiation dose received by the public in general, besides of database for mineralogical and geophysical studies of the Parana Basin. (author)

Ferreira, Ademar de Oliveira

2008-02-15

185

Carbon isotope variations in the upper Carboniferous - Permian Mallemuk Mountain Group, eastern North Greenland  

International Nuclear Information System (INIS)

Isotope data from Late Palaeozoic limestones of the Wandel Sea Basin in eastern North Greenland show a variation of ?13C from 0.0 0/00 to 5.7 0/00 vs PDB. Carbonates depleted in 13C occur in the basal part of lower Moscovian, upper Moscovian and middle Gzhelian transgressive sequences. 13C enriched limestones occur later in the cycles. The most 13C enriched limestones occur in the youngest (late Early Permian-early Late Permian) part of the sequence in Amdrup Land. The isotopic data is believed to represent changes in the global carbon cycle. Thus 13C enriched carbonates correlate to periods of burial of organic carbon mostly as coal, while 13C depleted carbonates formed as the result of erosion and oxidation of organic carbon during sea-level low stands. (author)

186

Paleomagnetism of Permian sediments and volcanic rocks from Sardinia  

Science.gov (United States)

During the Late Carboniferous, large granitic bodies were emplaced on Sardinia related to a change of the tectonic setting from compressional to extensional. Simultaneously the newly formed fault-bounded basins were filled with continental clastic sediments, paleontologoically and radiometrically dated to be Late Carboniferous to Early Permian in age. These basins provide an ideal testing ground for tectonic models such as the controversial Pangea B to A transition, which should have occurred prior to the opening of the Atlantic Ocean in the Jurassic. The mega-shear zone required for this transition has been postulated to be situated in today's Mediterranean (Arthaud and Matte, 1977). If this is valid, Sardinia should have been caught within this shear zone and suffered massive internal deformation. Here we report paleomagnetic data from six Permian basins from different Sardinian regions: in the NW (Nurra), N (Gallura), SW (Iglesiente-Sulcis) and SE (Gerrei-Sarcidano). About 200 samples from 23 sites covering mostly continental redbeds and subordinate acidic volcanics were thermally demagnetised. The overwhelming majority of the specimens studied displayed rather simple directional behaviour. A positive intraformational conglomerate test (Gerrei-Sarcidano) as well as the general improvement of the between-site scatter after correcting for minor tilt supports the primary character of the magnetisation. The resulting mean direction for five sites from Nurra (Dec: 126°, Inc: -24°, ?95: 8°, k: 118) is in perfect agreement with data published earlier by Vigliotti et al. (1990). Three sites of the Gallura area farther to the east yield a mean site direction (Dec: 158°, Inc: -34°, ?95: 23°, k: 28) which is rotated clockwise with respect to the data of Vigliotti et al. (1990). Seven sites from southern Sardinia (SW and SE) yield a mean direction with a declination of 82° and inclination of 12° (?95: 12°, k: 25). These results imply crustal coherence of Nurra and southern Corsica. The mean direction for Gallura, however, indicates significant clockwise rotation with respect to Nurra. The new data from southern Sardinia indicate approximately 40° or more degrees of counterclockwise rotation with respect to Nurra. These results are essentially coherent with the paleomagnetic data for the Late Paleozoic dyke swarms (Emmer et al., 2005) from the island of Sardinia and support the interpretation that Sardinia cannot longer be considered as a coherent block, but suffered massive internal deformation of pre-Triassic age.

Moser, E.; Emmer, B.; Bachtadse, V.; Kent, D. V.; Muttoni, G.; Ronchi, A.

2005-12-01

187

The Late Permian Ocean: What's the Big Stink?  

Science.gov (United States)

Since the ocean is (and has been) sulfate rich, the development of basinal to global anoxia is often associated with the buildup of hydrogen sulfide in anoxic waters. Bacterial sulfate reduction begins to dominate after oxygen and nitrate have been depleted, producing hydrogen sulfide. Hence, low atmospheric oxygen content, warm surface ocean temperatures, and high O2 demand reduce oceanic oxygen content and favor the establishment of euxinia. Biomarker evidence for photic zone sulfide and biogeochemical calculations suggest that the end-Permian mass extinction was one interval during which extreme anoxia may have led to H2S buildup. We hypothesize that H2S release to the atmosphere would be possible if the upward flux of sulfide from deep water in a largely euxinic ocean exceeded the oxygen flux into the surface ocean from wind mixing. In this scenario, destabilization of the chemocline (oxygen-sulfide interface) would cause sulfide poisoning in both the marine and terrestrial realms and contribute to the extinction. We used the end-Permian configuration of GENIE (www.genie.ac.uk), an energy-moisture-balance atmosphere model coupled to a 3-D, non-eddy-resolving, frictional geostrophic model to evaluate this hypothesis. This model includes marine biogeochemistry and capably simulates processes associated with the transition to oceanic anoxia. We performed a series of simulations designed to identify the conditions necessary for widespread euxinia and chemocline destabilization. We characterized the magnitude of hydrogen sulfide flux as a function of increasing oceanic phosphate content resulting from P release from sediments in anoxic environments. Significant ocean-atmosphere fluxes of H2S result from 6- to 10-fold increases in ocean phosphate at modern oxygen levels. These fluxes are focused in upwelling regions, although toxic H2S concentrations are also observed in the surface waters of nearshore equatorial regions. Our initial simulations support the hypothesis that extreme euxinia and episodic H2S eruptions can result from modest changes in the ocean's nutrient budget and may have contributed to the end-Permian mass extinction. Ongoing work addresses additional feedbacks involving sulfur utilization by sulfur-oxidizing phototrophs and the role of the nitrogen cycle during the transition to anoxia.

Meyer, K. M.; Ridgwell, A.; Kump, L. R.

2006-12-01

188

Sedimentary conditions of Upper Permian volcano-clastic rocks of Ayan-Yrahskiy anticlinorium (Verhoyansk-Kolyma orogen)  

Science.gov (United States)

Sedimentation conditions of upper Permian volcano-clastic rocks of Ayan-Yurakhsky anticlinorium are the reason of discussions between researchers. It is important to correctly solve this problem. Investigation allows us to conclude that upper Permian sediments was formed due to high rate deltaic sedimentation on shelf and continental slope of epicontinental sea basin. More than 45 outcrops of upper Permian sediments were described within Ayan-Yurakhsky anticlinorium. Termochemical and X-ray phase, lithological facies, stadial, paleogeographic and others were applied. Investigation allows to classify following types: tuffs, tuffites of andesites, andesi-dacites, sandstone tuffs, siltstone tuffs and claystone tuffs. Two facies were deliniated in the research area: 1) delta channel facies 2) epicontinental sea shelf edge and continental slope. Delta channel facies are located on the south-west part of Aian-Yrahskiy anticlinorium. It is composed of silty packsand and psammitic tuff-siltstone alternation and gravel-psammitic andesi-dacitic tuffute and tuff-breccia bands. Sediments have cross-bedding, through cross-bedding, curvilinear lamination structures. Facies occurred during high rate deltaic sedimentation on the shelf of epicontinental sea. Epicontinental sea shelf edge and continental slope facies are located on the south-west part. Sediments are represented by large thickness tuff-siltstone with tuff-sandstone, tuff-madstone, tuff, tuffite bands and lenses. Large number of submarine landslides sediments provide evidence that there was high angle sea floore environment. 30-50 m diametr eruption centers were described by authors during geological traverses. They are located in Kulu river basin. Their locations are limited by deep-seated pre-ore fault which extended along Ayan-Yurakhsky anticlinorium. U-Pb SHRIMP method showed that the average age of circons, taken from eruption centers, is Permian (256,3±3,7 ma). This fact confirms our emphasis that eruption centers were the centre of underwater effusive explosions which had been occurred in late Permian time. Gold ore deposits mainly localized in the south of Ayan-Yurakhsky anticlinorium and associated with upper Permian deltaic facies sediments. Taking into account lithological facies feature and volcanoclastic origin of sediments it is reasonable to suggest expelled-catagenesis model of gold mineralization. Gold was entered in sedimentary basin with piroclastic material. During catagenesis stage gold migrated from complex of shelf edge and continental slope to fan delta front complex in conjunction with expelled water. The emplacement of ore gold deposits related with upper Permian sediments can be successfully predicted, using this model and associated techniques.

Astakhova, Anna; Khardikov, Aleksandr

2013-04-01

189

Impact of Siberian Trap volcanism on the end-Permian and Early Triassic carbon cycle  

Science.gov (United States)

The Siberian Traps are the largest of the large igneous provinces, covering approximately 5 million km2. The timing of this volcanic episode is indistinguishable from the end-Permian mass extinction, and the event likely both directly and indirectly impacted marine ecosystems, leading to the largest extinction of Earth history. Recent studies suggest record volumes of carbon dioxide and other greenhouse gases were released from both lava degassing and degassing due to heating of Tunguska Basin sediments. In this study, we use Genie-1, an Earth system model of intermediate complexity (http://wwww.genie.ac.uk), to examine the impact of volcanic volatile release on the sedimentary carbon isotope record and end-Permian carbonate system under a wide range of volumes, rates, and isotope compositions of CO2 input. These model experiments place quantitative constraints on the magnitude and rates of CO2 addition that can account for the sedimentary and C isotope records of the end-Permian and Early Triassic.

Meyer, K. M.; Kump, L.; Cui, Y.; Ridgwell, A. J.; Payne, J.

2011-12-01

190

An overview of the Permian (Karoo) coal deposits of southern Africa  

Science.gov (United States)

The coal deposits of southern Africa (Botswana, Malawi, Mozambique, Namibia, South Africa, Swaziland, Tanzania, Zambia and Zimbabwe) are reviewed. The coal seams formed during two periods, the Early Permian (Artinskian-Kungurian) and the Late Permian (Ufimian-Kazanian). The coals are associated with non-marine terrestrial clastic sedimentary sequences, most commonly mudrock and sandstones, assigned to the Karoo Supergroup. The Early Permian coals are most commonly sandstone-hosted while the younger coals typically occur interbedded with mudstones. The sediments were deposited in varying tectono-sedimentary basins such as foreland, intracratonic rifts and intercratonic grabens and half-grabens. The depositional environments that produced the coal-bearing successions were primarily deltaic and fluvial, with some minor shoreline and lacustrine settings. Coals vary in rank from high-volatile bituminous to anthracite and characteristically have a relatively high inertinite component, and medium- to high-ash content. In countries where coal is mined, it is used for power generation, coking coal, synfuel generation, gasification and for (local) domestic household consumption.

Cairncross, B.

2001-08-01

191

A paleoclimatic simulation of the Late Permian greenhouse world and its consequences  

Energy Technology Data Exchange (ETDEWEB)

Sea-floor spreading assembled all the major cratonic blocks into a single supercontinent once in the Phanerozoic Eon. This unique Late Permian crustal tectonic event produced Pangaea and an enormous oceanic basin volume that dropped sea level to a global lowstand unrivaled in the Phanerozoic. Two paleoclimatic simulations using a numerical three-dimensional general circulation model tested changes in the greenhouse effect. The authors conclude that for a simulation to fit the Late Permian geologic record, the paleoatmosphere must contain an enhanced greenhouse gas effect. A third simulation tested changes of paleogeography in southern Pangaea (Gondwana) that did not appreciably alter the harsh continental paleoclimate. The simulated paleoclimatic changes provide extraordinarily warm ocean and atmosphere, and a significant reduction in continental rainfall and runoff. These conditions inevitably lead to more aridity and less vegetation on land, gradually reduce the delivery of vital nutrients from continental sources to marine margins, systematically liberate CO{sub 2} dissolved in ocean water, and incrementally increase stress on marine and terrestrial biotas. These consequences severely disrupted rates of oxygen and carbon cycling. Their quantitative paleoclimatic simulation is consistent with distributions of red beds, evaporites, coals, marine shelf areas, seawater isotope trends, and paleontologic originations and extinctions. Thus, the Pangaean plate assembly probably triggered an inexorable sequence of geophysical, geochemical, and biological events that forced an elevated greenhouse effect in the Late Permian, nearly annihilating the Phanerozoic biota.

Moore, G.T.; Jacobson, S.R.; Hayashida, D.N. (Chevron Oil Field Research Co., La Habra, CA (United States))

1991-03-01

192

Acritarchs from the Number 5 Seam in the Permian Vryheid Formation, Witbank Coalfield, South Africa  

Energy Technology Data Exchange (ETDEWEB)

Two species of marine acritarchs, Mehlisphaeridium fibratum and Mehlisphaeridium gondwanaensis, are described from a shale parting near the top of the No. 5 Seam at Greenside Colliery, Witbank Coalfield, Republic of South Africa. The sedimentary sequence containing this coal seam consists of fine- to very coarse-grained sandstone, siltstone, shale, and coal which constitute part of the Early Permian Vryheid Formation (Karoo Supergroup). The paleoenvironmental implications of the discovery of acritarchs imply that marine conditions prevailed in the basin at the time of deposition of this particular shale unit. 56 refs., 6 figs., 1 tab.

Venter, M.E.; Cairncross, B. [Rand Afrikaans University, Auckland Park (South Africa). Dept. of Geology

1995-12-01

193

Megaspores from coals of the Triunfo Member, Rio Bonito Formation (Lower Permian), northeastern Parana State, Brazil  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the results of a detailed study of megaspores occurring in coal seams of the Triunfo Member, Rio Bonito Formation at Figueira, Parana State, Brazil. This coal-bearing sequence accumulated in a marine delta system during the Early Permian. Four species are described and illustrated: Lagenoisporites triunfensis, L. scutiformis, Sublagenicula cf. brasiliensis, and Setosisporites cf. furcatus. Of these, the two species of Lagenoisporites are predominant. Relationships to other megaspore species are discussed; and the temporal and spatial distributions of the four species in the Parana Basin are documented.

Ricardi-Branco, F.; Arai, M.; Rosler, O. [UNICAMP, Campinas (Brazil)

2002-07-01

194

Pumping test and fluid sampling report - Mansfield No. 1 (PD-4) well, Palo Duro Basin, Texas: unanalyzed data  

International Nuclear Information System (INIS)

This report contains pumping test and fluid sampling data collected at Mansfield No. 1 well, located in Oldham County, in the Permian Basin of Texas. These data were collected by Stone and Webster Engineering Corporation to support studies of fluid migration and age relationships in the Permian Basin. The testing and sampling took place between October 1981 and October 1982. These data are preliminary. They have been neither analyzed nor evaluated. 4 references, 8 figures, 2 tables

195

An integrated study of the NE German Basin  

OpenAIRE

The NEGermanBasin is part of the Southern Permian Basin south of the TransEuropean Suture Zone (TESZ). Here we report an attempt to integrate a variety of geological and geophysical data in order to reveal the present day deep crustal structure of the NEGermanBasin. Special focus is taken on detailed geological information, available reflection seismic data, wide angle refraction seismic data and gravity data. Based on this integrative approach, a concise crustal model is developed which ...

 bayer, U.;  scheck, M.;  rabbel, W.;  krawczyk, C. M.; -j  go?tze, H.;  stiller, M.; Th. Beileckeb; -m  marotta, A.;  barrio-alvers, L.;  kuder, J.

1999-01-01

196

Deep crustal structure of the Northeast German basin: New DEKORP-BASIN '96 deep-profiling results  

OpenAIRE

An integrated reflection and refraction seismic survey across the Permian-Cenozoic Northeast German basin yields new insights on the evolution of intracontinental basins. No precursor rift basin was observed, but there is evidence of lower-crustal thinning and an initial magmatic stage. Minor Triassic rifting and Late Cretaceous compressional tectonics indicate that intraplate deformation was strongly influenced by older structures. Intraplate thinning and contraction were strongly decoupled ...

Dekorp-basinresearch Group,  .

1999-01-01

197

Petroleum geology of the Palo Duro Basin, Texas Panhandle  

International Nuclear Information System (INIS)

The Palo Duro Basin, Permian Basin, Texas is an asymmetric, relatively shallow, intracratonic basin in the southern Texas Panhandle filled mostly by Mississippian, Pennsylvanian, and Permian sedimentary rocks. Although deeper and prolific prolific petroleum-producing basins adjoin it on the north (Anadarko Basin), south (Midland Basin), and east (Hardeman Basin), the Palo Duro Basin has produced remarkably small amounts of oil and gas to date. This is all the more noteworthy because the sedimentary sequence and rock types of the basin are similar to those of the adjacent basins. Analyses of the stratigraphic succession and structural configuration of the Palo Duro Basin suggest that adequate reservoir rocks, top-seals, and geologic structures are present. Most of the structures formed early enough to have trapped hydrocarbons if they were migrating in the rock column. Although additional work is under way to properly address the question of the petroleum source rocks, generation, and migration, the general absence of production in the basin may relate to an overall deficiency in hydrocarbon generation within the basin. Geologic information in this report will form part of the basis for further analysis and conclusions on hydrocarbon potential in the Palo Duro Basin

198

The stratigraphic significance of the Solenoid Complex in the Permian of Gondwana  

Directory of Open Access Journals (Sweden)

Full Text Available The Solenoid Complex comprises a fossil wood assemblage with stratigraphic distribution restricted to the middle-late Kungurian, present in Western (Irati Formation, Paraná Basin, Brazil and Eastern (Upper Barakar Interval of the Indian basins Gondwana. Its occurrence seems to be related to the adaptation of certain plant groups to paleoenvironmental stress in lowland niches of coastal areas subject to salinity variation. The disappearance of these forms in the latest Kungurian is probably linked to the cessation of these conditions, which is confirmed by the sedimentary record. The here designated “Solenoid Complex Zone” correlates with the acme in diversification of striate and taeniate patterns especially in bisacatte pollen grains, but also in monosacatte ones, reflecting important tectonically and climatically driven changes in the vegetational pattern. The waning icehouse stage during the Permian was an important factor to the development of similar vegetation patterns in Western and Eastern Gondwana in the latitudinal belt of 40° – 55°.

Margot Guerra-Sommer

2014-06-01

199

Ocean anoxia did not cause the Latest Permian Extinction  

Science.gov (United States)

The Latest Permian Extinction (LPE, ~252 million years ago) was a turning point in the history of life on Earth with a loss of ~96% of all marine species and ~70% of all terrestrial species. While, the event undoubtedly shaped the evolution of life its cause remains enigmatic. A leading hypothesis is that the global oceans became depleted in oxygen (anoxia). In order to test this hypothesis we investigated a proxy for marine oxygen levels (molybdenum isotopic composition) in shale across the LPE horizon located on the subtropical northwest margin of Pangea at that time. We studied two sedimentary records in the Sverdrup basin, Canadian High Arctic: Buchanan Lake (eastern Axel Heiberg Island; 79° 26.1'N, 87° 12.6'W), representing a distal deep-water slope environment, and West Blind Fiord (southwest Ellesmere Island; 78° 23.9'N, 85° 57.2'W), representing a deep outer shelf environment (below storm wave base). The molybdenum isotopic composition (?98/95Mo) of sediments has recently become a powerful tool as a paleo-oceanographic proxy of marine oxygen levels. Sample preparation was carried out in a metal-free clean room facility in the isotope laboratory of the Department of Physics and Astronomy, University of Calgary, Canada, that is supplied by HEPA-filtered air. Molybdenum isotope ratios were determined on a Thermo Scientific multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) with an uncertainty better than ±0.10o for ?98/95Mo values. Results from the Buchanan Lake section show a large shift in ?98/95Mo values from 2.02o to +2.23o at the extinction horizon, consistent with onset of euxinic conditions. In contrast, West Blind Fiord shales, representing the sub-storm wave base shelf environment, show little change in the molybdenum isotopic composition (1.34o to +0.05), indicating ongoing oxic conditions across the LPE (Proemse et al., 2013). Our results suggest that areas of the Pangea continental shelf (North West Pangea) experienced oxic conditions throughout the LPE event, while anoxic conditions developed in the deep ocean. Hence, anoxic marine waters did not extend globally onto shelf environments and as such ocean anoxia cannot have been the main driver of the extinction event. While global systems were stressed by anoxia, the anoxic conditions may better represent a symptom of Siberian Trap eruptions that had catastrophic impact on the environment, potentially through nutrient loading and deposition of toxic substances into marine and terrestrial systems. Proemse et al., 2013: Molybdenum isotopic evidence for oxic marine conditions during the latest Permian extinction. Geology 41, 967-970.

Proemse, Bernadette C.; Grasby, Stephen E.; Wieser, Michael E.; Mayer, Bernhard; Beauchamp, Benoit

2014-05-01

200

Summary of the stratigraphy, sedimentology, and mineralogy of Pennsylvanian and permian rocks of Oklahoma in relation to uranium-resource potential  

International Nuclear Information System (INIS)

Pennsylvanian-Permian strata in Oklahoma were deposited in environments which ranged from deep marine to alluvial fan. The former was most common in the Ouachita geosyncline during Early Pennsylvanian, but parts of the Anadarko basin were also relatively deep water during Middle and Late Pennsylvanian. Alluvial-fan deposits in Oklahoma are related primarily to the Amarillo-Wichita-Criner, Arbuckle, and Ouachita uplifts. As a result of erosion of the Wichita and Arbuckle areas during the Pennsylvanian-Permian, Precambrian and Cambrian felsic igneous rocks were exposed and became sources of significant quantities of feldspar in the sandstones and conglomerates, especially those on the flanks of the uplifts, and possibly sources of significant uranium concentrations in basinal waters. The Ouachita uplift, Sierra Grande-Apishapa uplift to the northwest, and possibly the Appalachian system also furnished feldspar to form the rather common subarkoses in the Upper Pennsylvanian-Permian. Feldspar is an apparent source of uranium which is present in the alluvial-fan deposits associated with the Wichita and Arbuckle uplifts, the Permian sandstones on oil-producing structures in southern Oklahoma, the lenticular sandstones on the Muenster-Waurika arch, and the tidal-flat sandstone-siltstones in western Oklahoma and possibly in north-central Oklahoma. Radioactive anomalies associated with Cherokee sandstones may be related to the Desmoinesian phosphatic shales, local depositionalsian phosphatic shales, local depositional environments of deltaic complexes which influenced diagenetic conditions, and/or the pre-Pennsylvanian unconformity with respect to the radioactive Woodford Shale

201

New discovery of Permian belemnoids in Hunan  

Energy Technology Data Exchange (ETDEWEB)

The fossil belemnoids described here were discovered from the Upper Permian Dalong Formation in Hunan province. There are nearly one hundred specimens, including one genus and one species. The diagnosis of the species is as follows: Genus: palaeobelemnopsis Chen, 1982; Species: Palaeobelemnosis sp. The guard is small and slender, about six times the maximum transverse diameter in length, with outline slightly hastate or fusiform. The maximum transverse diameter locates the border between the apical region and the stem region, and is nearly cycloid or slightly compressed in the anterior of the alveolus. The apical angle is about 70{degree}. The median ventral groove is wide and shallow, and is sometimes absent. Two dorso-lateral grooves are apparent and extending from the alveolus to the apex. The Phragmocone is slender. The outer shape of the guard is very similar to that of P. sinensis and P. minor. Nevertheless, this species differs from the two latters in having many transverse lines covering on the whole surface of the guard. Because all of these specimens are fossils of external mold and no inner structures have been preserved except a piece of siphuncle remains, the species is not given a new species name. Permian belemnoids are rarely found and the Palaeobelemnopsis is a primitive genus of belemnoids, therefore these specimens have important significance for research on the origin of COLEOIDEA. 4 refs., 3 figs.

Liu, Z.; Su, L. [Xiangtan Mining Institute, Hunan (China). Dept. of Geology

1999-06-01

202

A passive margin-type submarine fan complex, Permian Ecca Group, South Africa  

Energy Technology Data Exchange (ETDEWEB)

A submarine fan complex, comprising five arenaceous fan systems separated by basinal shale units, occurs in the southwestern part of the intracratonic Karoo basin in South Africa. Although basin development is related to a subduction zone bordering the palaeo-Pacific ocean to the south of Gondwanaland and the evolution of the Cape Fold Belt, the entire Lower Permian Ecca Group basin-fill succession reflects depositional characteristics of a passive-margin setting. The submarine fan complex, 250 m thick, originated from sediments supplied by Mississippi-type deltas dominating the Ecca coastline. The fine grain-size and low sand/shale ratio of the submarine fan and deltaic deposits reflect the maturity of the ancient river systems. Outcrops of the fan complex are well exposed and cover an area of 650 km{sup 2}. The strata are not affected by folding, and deep erosion allows three-dimensional viewing of mid-fan to outer-fan deposits. Features of interest include stacked lobe deposits displayed along 2.5 km of a 60 m high cliff section, and a transverse cliff section through channel-fill deposits 500 m wide. Paleocurrent directions reveal that each sequence had its own main source area located to the northwest and south of its present geographic location. The cyclic nature of the fan complex is attributed to relative sea-level changes; deposition took place on the basin floor in water depths that do not exceed 500 m. Shoaling of the basin to wave base depths is reflected in the pro-delta and delta front deposits overlying the uppermost fan sequence. Major factors in controlling direction of fan progradation were delta switching and basin floor topography.

Wickens, H.D. (SOEKOR-Pty. Ltd., Parow (South Africa)); Bouma, A.H. (Louisiana State Univ., Baton Rouge (United States))

1991-03-01

203

Gas hydrate contribution to Late Permian global warming.  

Czech Academy of Sciences Publication Activity Database

Ro?. 393, May (2014), s. 243-253. ISSN 0012-821X Institutional support: RVO:67985530 Keywords : Latest Permian extinction * gas hydrates * carbon isotope shift Subject RIV: DC - Siesmology, Volcanology, Earth Structure Impact factor: 4.724, year: 2013

Majorowicz, J.; Grasby, S. E.; Šafanda, Jan; Beauchamp, B.

2014-01-01

204

The contorted New England Orogen (eastern Australia): New evidence from U-Pb geochronology of early Permian granitoids  

Science.gov (United States)

A series of sharp bends (oroclines) are recognized in the Paleozoic to early Mesozoic New England Orogen of eastern Australia. The exact geometry and origin of these bends is obscured by voluminous magmatism and is still debated. Here we present zircon U-Pb ages that confirm the lateral continuation of early Permian (296-288 Ma) granitoids and shed new light on the oroclinal structure. Orogenic curvature is defined by the alignment of early Permian granitoids parallel to the structural grain of the orogen, as well as the curved geometry of sub-vertical deformation fabrics, forearc basin terranes, and serpentinite outcrops. Alternative geometrical interpretations may involve two bends (Texas and Coffs Harbour Oroclines), three bends (+Manning Orocline), or even four bends (+Nambucca Orocline). We argue that the model involving four bends is most consistent with available data, although further kinematic constraints are required to confirm the existence of the Manning and Nambucca Oroclines. A subsequent phase of younger magmatism (<260 Ma) cuts across the curved structural grain, providing a minimum age constraint for orocline development. Assuming a structure of four oroclines, we suggest a tentative tectonic model that involves an early stage of subduction curvature during slab rollback at 300-285 Ma, followed by bending associated with dextral transpression. A final tightening of the curved structures was possibly obtained by E-W shortening during the late Permian to Triassic (265-230 Ma) Hunter-Bowen orogeny.

Rosenbaum, Gideon; Li, Pengfei; Rubatto, Daniela

2012-02-01

205

Biostratigraphic correlation in the Karoo: The case of the Middle Permian parareptile Eunotosaurus  

Scientific Electronic Library Online (English)

Full Text Available The richness of fossil tetrapods from the Beaufort Group of South Africa has enabled biostratigraphic subdivision of this Permo-Triassic succession, with global applicability. Despite being the thickest of the seven biozones recognised, attempts at further subdivision of the Middle Permian Tapinocep [...] halus Assemblage Zone (Abrahamskraal Formation) have not been successful, largely because the exact stratigraphic ranges of fossil taxa are unknown. This gap in knowledge has limited stratigraphic correlation of the Abrahamskraal Formation and hindered understanding of Middle Permian Karoo basin development. Currently, the lowermost Beaufort Group is split between an eastern and a western stratigraphic scheme and, because of poor outcrop and the relative paucity of fossils in the east, stratigraphic correlation between the two areas has been uncertain. Recent fossil discoveries of the parareptile Eunotosaurus africanus in the Eastern Cape and Free State provinces have extended its known geographic range in the east. An additional specimen from the lower Middleton Formation in the Eastern Cape has, for the first time, enabled the biostratigraphic correlation of this unit with the Poortjie Member of the Teekloof Formation in the west. These finds confirm the diachroneity of the boundary between the marine Ecca Group and the terrestrial Beaufort Group.

Mike, Day; Bruce, Rubidge; John, Almond; Sifelani, Jirah.

206

Ecosystem remodelling among vertebrates at the Permian-Triassic boundary in Russia.  

Science.gov (United States)

The mass extinction at the Permian-Triassic boundary, 251 million years (Myr) ago, is accepted as the most profound loss of life on record. Global data compilations indicate a loss of 50% of families or more, both in the sea and on land, and these figures scale to a loss of 80-96% of species, based on rarefaction analyses. This level of loss is confirmed by local and regional-scale studies of marine sections, but the terrestrial record has been harder to analyse in such close detail. Here we document the nature of the event in Russia in a comprehensive survey of 675 specimens of amphibians and reptiles from 289 localities spanning 13 successive geological time zones in the South Urals basin. These changes in diversity and turnover cannot be explained simply by sampling effects. There was a profound loss of genera and families, and simplification of ecosystems, with the loss of small fish-eaters and insect-eaters, medium and large herbivores and large carnivores. Faunal dynamics also changed, from high rates of turnover through the Late Permian period to greater stability at low diversity through the Early Triassic period. Even after 15 Myr of ecosystem rebuilding, some guilds were apparently still absent-small fish-eaters, small insect-eaters, large herbivores and top carnivores. PMID:15525988

Benton, M J; Tverdokhlebov, V P; Surkov, M V

2004-11-01

207

An upwelling model for the Phosphoria sea: A Permian, ocean-margin sea in the northwest United States  

Science.gov (United States)

The Permian Phosphoria Formation, a petroleum source rock and world-class phosphate deposit, was deposited in an epicratonic successor basin on the western margin of North America. We calculate the seawater circulation in the basin during deposition of the lower ore zone in the Meade Peak Member from the accumulation rates of carbonate fluorapatite and trace elements. The model gives the exchange rate of water between the Phosphoria sea and the open ocean to the west in terms of an upwelling rate (84 m yr-1) and residence time (4.2 yr) of seawater in the basin. These hydrographic properties supported a mean rate of primary productivity of 0.87 g m-2 d-1 of carbon in the uppermost few tens of meters of the water column (the photic zone) and denitrifying redox conditions in the bottom water (below approximately 150 m depth). High rain rates, onto the sea floor, of the organic matter that hosted the phosphate and several trace elements contributed to the accumulation of phosphorite, chert, and black shales and mudstones. Evaporation in the Goose Egg basin to the east of the Phosphoria basin ensured the import of surface seawater from the Phosphoria sea. Budgets of water, salt, phosphate, and oxygen, plus the minor accumulation of the biomarker gammacerane, show that exchange of water between the two basins was limited, possibly by the shallow carbonate platform that separated the two basins.

Piper, D.Z.; Link, P.K.

2002-01-01

208

Permian and Triassic rocks of the Mojave Desert and their implications for timing and mechanisms of continental truncation  

Science.gov (United States)

Upper Paleozoic and lower Mesozoic rocks in the Mojave Desert and adjacent areas record the change from a passive continental margin to a subduction margin in the southwestern United States. This change was apparently accompanied by truncation and reorientation of the continental margin in the Mojave Desert and western Basin and Range Province. From Late Proterozoic to Mississippian time the western margin of North America had a northeast-southwest trend through Nevada and eastern California. Truncation of the margin began in Pennsylvanian time when a northwest trending, left-lateral strike-slip fault zone formed across the Antler orogenic belt, the Cordilleran miogeocline, and the more cratonal character Mojave Desert. Rocks of the Antler belt were apparently displaced southward from east central California to their present position in the northwestern Mojave Desert. Sedimentary rocks deposited during this interval record an active continental borderland, characterized by alternately subsided and uplifted marine basins. This transcurrent faulting continued to Late Permian time. Magmatic activity and deformation started in the Mojave Desert in Late Permian time and affected both miogeoclinal-cratonal and displaced Antler rocks. Magmatic activity ceased and marine sedimentation resumed in Early Triassic time. Lower Triassic rocks constitute an overlap sequence on both deformed and undeformed miogeoclinal-cratonal rocks and possibly on displaced Antler rocks. Facies trends in these rocks are northwest-southeast, indicating the new margin trend. Truncation and reorientation of the margin were completed therefore by Early Triassic time, or possibly as early as Late Permian time. Upper Permian magmatism and deformation in the Mojave Desert are older than, and distinct from, the early Triassic Sonoma Orogeny of Nevada. Lower Triassic rocks in the Mojave Desert are post tectonic with respect to deformation in that region, whereas correlative Lower Triassic rocks in Nevada are pretectonic to syntectonic with respect to the Sonoma Orogeny. This difference reflects the variation in deformation and tectonic setting along a newly developed Cordilleran margin. The southern part of the Cordillera was apparently a subduction margin as early as Late Permian or Middle Triassic time, while the central (Nevada segment) was the site of collision tectonics.

Walker, J. Douglas

1988-06-01

209

Geotectonic implications of Permian and Triassic carbonate successions in the Central Plain of Thailand  

Science.gov (United States)

Two carbonate successions constituting Paleozoic-Mesozoic basement rocks distributed in the Nakhon Sawan-Uthai Thani area in the Chao Phraya Central Plain of Thailand were investigated to understand basic geotectonic subdivision of the area. Of them, we newly proposed the term Khao Pathawi Limestone for a Triassic succession exposed in eastern Uthai Thani Province, from which a rich foraminiferal fauna consisting of Aulotortus sinuosus, A. friedli, Tetrataxis inflata, Diplotermina subangulata, Agathammina austroalpina, Ammobaculites rhaeticus, Alpinophragmium perforatum, Gaudryina triadica, and others was discriminated. They clearly suggest a Late Triassic age and highly probably Norian/Rhaetian. This limestone succession is considered to have formed a carbonate platform and is comparable to those on the Triassic Lampang-Phrae Basin in the Sukhothai Zone of Northern Thailand. In contrast, the Uthai Thani Limestone exposed just west of the Khao Pathawi Limestone, in the form of NNW-SSE trending monadnocks, represents a slightly metamorphosed, thick-bedded Permian succession. Its outcrop alignment is distinct from the north-south trending Khao Pathawi Limestone, suggesting their structural separation. The Uthai Thani Limestone is correlated to the Sai Yok Formation and the Ratburi Limestone, both of which are well-known as typical Permian successions on the Sibumasu Block. By integrating these data from the carbonates, together with available geological information from other Paleozoic-Mesozoic basement units in the Central Plain, such as petrochemical properties of granitoids and volcanic/volcaniclastic rocks and litho- and chronostratigraphic characteristics of sedimentary successions, including the Permian Khao Gob Chert, we explain that the central part of the Nakhon Sawan-Uthai Thani area where the Khao Pathawi Limestone and the Khao Gob Chert are distributed, corresponds geotectonically to the direct southern extension of the Sukhothai Zone of Northern Thailand. Thus, as is the case of Northern Thailand, we recognized three geotectonic domains also in the Central Plain; they are the Indochina Block (part of Cathaysialand), Sukhothai Zone (Permian-Triassic island arc system), and Sibumasu Block (part of Gondwanaland) from east to west. To the south, the Sukhothai Zone probably extends to the Klaeng Zone of Southeast Thailand. In this paper, Endotriada martiniae Ueno, Miyahigashi and Charoentitirat, n. sp. from the Khao Pathawi Limestone is also described.

Ueno, Katsumi; Miyahigashi, Akira; Kamata, Yoshihito; Kato, Miyako; Charoentitirat, Thasinee; Limruk, Seranee

2012-11-01

210

Nitrogen isotope chemostratigraphy across the Permian-Triassic boundary at Chaotian, Sichuan, South China  

Science.gov (United States)

Nitrogen isotopic compositions of upper Permian to lowermost Triassic rocks were analyzed at Chaotian in northern Sichuan, South China, in order to clarify changes in the oceanic nitrogen cycle around the Permian-Triassic boundary (P-TB) including the entire Changhsingian (Late Late Permian) prior to the extinction. The analyzed ca. 40 m thick interval across the P-TB at Chaotian consists of three stratigraphic units: the upper Wujiaping Formation, the Dalong Formation, and the lowermost Feixianguan Formation, in ascending order. The upper Wujiaping Formation, ca. 10 m thick, is mainly composed of dark gray limestone with diverse shallow-marine fossils such as calcareous algae and brachiopods, deposited on the shallow shelf. In contrast, the overlying Dalong Formation, ca. 25 m thick, is mainly composed of thinly bedded black mudstone and siliceous mudstone containing abundant radiolarians, deposited on the relatively deep slope/basin. Absence of bioturbation, substantially high total organic carbon contents (up to 15%), and abundant occurrence of pyrite framboids in the main part of the Dalong Formation indicate deposition under anoxic condition. The lowermost Feixianguan Formation, ca. 5 m thick, is composed of thinly bedded gray marl and micritic limestone with minor fossils such as ammonoids and conodonts, deposited on the relatively shallow slope. ?15NTN values are in positive values around +1 to +2‰ in the upper Wujiaping Formation implying denitrification and/or anammox in the ocean. ?15NTN values gradually decrease to -1‰ in the lower Dalong Formation and are consistently low (around 0‰) in the middle Dalong to lowermost Feixianguan Formation. No clear ?15NTN shift is recognized across the extinction horizon. The consistently low ?15NTN values suggest the enhanced nitrogen fixation in the ocean during the Changhsingian at Chaotian. Composite profiles based on previous and the present studies demonstrate the substantial ?15N variation on a global scale in the late Permian to earliest Triassic; a systematic ?15N difference by low and high latitudes is particularly clarified. Although the enhanced nitrogen fixation throughout the Changhsingian at Chaotian was likely a regional event in northwestern South China, the composite ?15N profiles imply that the sea area in which fixed nitrogen is depleted has gradually developed worldwide in the Changhsingian, possibly acting as a prolonged stress to shallow-marine biota.

Saitoh, Masafumi; Ueno, Yuichiro; Nishizawa, Manabu; Isozaki, Yukio; Takai, Ken; Yao, Jianxin; Ji, Zhansheng

2014-10-01

211

Synthrusting deposition of the Pennsylvanian and Permian Strathearn Formation, Northern Carlin Trend, Nevada  

Science.gov (United States)

The middle Upper Pennsylvanian and middle Lower Permian Strathearn Formation belongs to the overlap assemblage of the Antler orogen in Nevada. At Beaver Peak, near the Carlin Trend of gold deposits, it contains synorogenic conglomerate deposits associated with emplacement of a regionally extensive, 1-km-thick tectonic wedge that is floored by the Coyote thrust. Normal marine conodont biofacies throughout the Strathearn Formation suggest middle shelf or deeper, depositional environments. The allochthon floored by the Coyote thrust has been thrust above a middle Upper Pennsylvanian, lower conglomerate unit of the Strathearn Formation. A middle Lower Permian upper conglomerate unit, the highest unit recognized in the Strathearn Formation, as well as similarly aged dolomitic siltstone, onlap directly onto Ordovician quartzarenite of the Vinini Formation that makes up most of the Coyote allochthon. Quartz grains and quartzarenite fragments of variable roundness and shape in the conglomerate units were derived from the presently adjoining tectonic lobe of mostly quartzarenite that advanced southeast (present geographic coordinates) during the late Paleozoic into the developing Strathearn basin. Chert fragments in the conglomerates probably were derived mostly from Devonian Slaven Chert, including a widespread thick mélange unit of the Slaven Chert in the footwall of the Coyote thrust. Lithologic and shape ratio data from approximately 4200 clasts at 17 sites of the two major conglomerate units in the Strathearn Formation at Beaver Peak are roughly similar in that they contain only chert and quartzarenite clasts, and chert clasts predominate in both units. They differ in the relative proportion of the two lithologies whereby quartzarenite clasts increase sixfold in the upper unit (middle Lower Permian) versus its content in the lower conglomerate unit. Relations at the unconformity between the upper conglomerate unit and its underlying quartzarenite shows quartzarenite fragments actually breaking away from an immediately subjacent source. Ordovocian quartzarenite, which forms a tectonically uplifted wedge with the Coyote thrust at its base, became a source region for much of the quartzarenite detritus deposited preferentially in the upper parts of the Strathearn Formation. The conglomerate units of the Strathearn Formation temporally bracket emplacement of the Coyote thrust. Thrusting related to contractional reactivation of the Robert Mountains thrust system largely was completed by middle Early Permian.

Theodore, Ted G.; Berger, Vladimir I.; Singer, Donald A.; Harris, Anita G.; Stevens, Calvin H.

2004-03-01

212

Plant biodiversity in the Mahanadi Basin, India, during the Gondwana period  

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The Mahanadi Basin is one of five major sedimentary basins of Peninsular India. The sediments are exposed in two different regions: an extensive basin comprising Lower to Upper Gondwana with coal measures towards the west (Talchir and Ib-River Sub-basins); and the Athgarh Sub-basin in the east with rocks of only Upper Gondwana age. This study was mainly concerned with plant species diversification and the development of flora in the Mahanadi Basin from the Early Permian to the Early Cretaceous. A number of successive megafloras were recognised with gaps in the sequence. Leaves were the dominant part of the preserved flora, followed by fruits. Maximum plant diversification in gymnosperms was recorded in the Late Permian (Kamthi Formation), and in pteridophytes in the Early Cretaceous (Athgarh Formation).

Singh, K.J. [Birbal Sahni Institute of Paleobotany, Lucknow (India)

2000-07-01

213

Ground-water hydraulics of the deep-basin brine aquifer, Palo Duro Basin, Texas panhandle  

International Nuclear Information System (INIS)

The Deep-Basin Brine aquifer of the Palo Duro Basin (Texas Panhandle) underlies thick Permian bedded evaporites that are being evaluated as a potential high-level nuclear waste isolation repository. Potentiometric surface maps of 5 units of the Deep-Basin Brine aquifer were drawn using drill-stem test (DST) pressure data, which were analyzed by a geostatistical technique (kriging) to smooth the large variation in the data. The potentiometric surface maps indicate that the Deep-Basin Brine aquifer could be conceptually modeled as 5 aquifer units; a Lower Permian (Wolfcamp) aquifer, upper and lower Pennsylvanian aquifers, a pre-Pennsylvanian aquifer, and a Pennsylvanian to Wolfcampian granite-wash aquifer. The hydraulic head maps indicate that ground-water flow in each of the units is west to east with a minor northerly component near the Amarillo Uplift, the northern structural boundary of the basin. The Wolfcamp potentiometric surface indicates the strongest component of northerly flow. Inferred flow direction in Pennsylvanian aquifers is easterly, and in the pre-Pennsylvanian aquifer near its pinch-out in the basin center, flow is inferred to be to the north. In the granite-wash aquifer the inferred flow direction is east across the northern edge of the basin and southeast along the Amarillo Uplift

214

Water mass denitrification during the latest Permian extinction in the Panthalassic Ocean  

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The latest Permian extinction (LPE) event, about 252 Myr ago, resulted in the disappearance of >90 % of marine and terrestrial species. Possible explanations invoke, Siberian Trap volcanism, anoxia, H2S poisoning draw down of bioessential elements or a combination of these. Recent observation of coal ash dispersion into global oceans prior to LPE suggest global ash fall could have created toxic marine (terrestrial) conditions. Recent work also suggests volcanic mercury emissions may have added to toxic marine conditions. While development of marine euxinic conditions in the Tethyan region across the LPE is widely accepted, inferences on the redox and environmental conditions of the Panthalassic Ocean more equivocal. Indications of (photic zone) euxinia occur in marginal areas of Panthalassa. In central pelagic areas, however, expansion of low oxygen conditions across the LPE may be restricted to the oxygen minimum zone rather than towards the photic zone or the seafloor. Here, we report the ?15N isotopic signature in Late Permian - Early Triassic sediments from the Buchanan Lake section in the Sverdrup Basin, Canadian Arctic. Deep water marine sedimentation in the Sverdrup Basin, connected to Panthalassa via a western seaway, allows inferences on the nitrogen cycling across the LPE. We confirm that expansion of low oxygen conditions in the Panthalassic Ocean began prior to the paleo-Tethys Ocean. Further, the detailed correspondence of changes in denitrification, nitrate utilization/fixation across the LPE in both oceans indicate rapid reorganization of the marine ecosystem in response to changes in nutrient inventories, probably mediated through the eruption of the Siberian Traps.

Knies, J.; Grasby, S.; Beauchamp, B.; Schubert, C.

2012-04-01

215

Palynological records of the Early Permian icehouse-greenhouse transition (Ecca Group, South Africa)  

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The Permian coal-bearing formations of the South African Karoo Basin play a crucial role in the study and interpretation of Gondwana's climate history and biodiversity in this time of major global changes in terrestrial and marine ecosystems. Here, we report on new palynological data from the No. 2 coal seam of the northern Witbank coal field, documenting the switch from Icehouse to Greenhouse conditions in the Early Permian (Lower Ecca Group). The studied postglacial fluvio-deltaic deposits of a highly proximal setting comprise coarse-grained to pebbly sandstones, partially with an abrupt upward transition into fine-grained sediments and coal, trough cross-stratified medium- to coarse-grained sandstones, and horizontally laminated fine- to medium-grained sandstones and siltstones. The sedimentary organic matter content clearly documents stratal changes in the palynomorph assemblage and variations in the amount and in the type, size and shape of plant debris. Generally, palynofacies is characterized by a high amount of opaque phytoclasts. Amorphous organic matter is characteristic of laminated siltstones and coals. The palynological record indicates a cold climate, fern wetland community, characteristic of lowland alluvial plains, and an upland conifer community in the lower part of the coal seam. Up section, these communities are replaced by a cool-temperate cycad-like lowland vegetation and gymnospermous upland flora. Ongoing studies focus on the cyclic architecture of the coal seam, applying palynofacies analysis as high-resolution correlation tool with respect to decipher signatures of prominent climate amelioration on basin-wide, intercontinental and intra-Gondwanic scales.

Götz, Annette E.; Ruckwied, Katrin

2013-04-01

216

Comparative Analysis of Biogeographic, Sedimentologic and Paleomagnetic Data and the Geodynamics of Terranes of Northeast Asia in Late Permian  

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We present the first consistent model of the relative locations of the most important tectonic structures in Northeast of Asia for Late Paleozoic time. This model is based on comparative analysis of paleomagnetic, sedimentologic and biogeographic data. Results of research by the authors and critically reviewed data of the other researchers are used. The current paleomagnetic data for Permian rocks from the Northeast region still remain scanty and are practically non-existent for some tectonic structures such as the Okhotsk microcontinent. Nevertheless we believe that it can be shown that there was no major (thousands of kilometers) horizontal motion between the separate tectonic blocks of Yana-Kolyma fold-and-thrust area, at least starting Middle Paleozoic. In paleogeographic terms Northeast Asia in the Permian represented a system of marine basins of various types. Okhotsk microcontinent was outboard from the Siberian craton to the southeast (present day coordinates). A system of deepwater marginal type marine basins lay to the east of the Siberian craton. The Koni-Taigonos volcanic arc was along the south edge, and. its erosion products formed deepwater fore-arc basins. Significant differences between the Permian bivalve communities on the Omolon microcontinent and contemporary communities of Verkhoyansk indicate the existence of the deepwater Ayan-Yuryakh trough basin. The strata of the latter are characterized as thick (up to 7 km) flysch deposits plus thick diamictites. Paleobiogeographic studies show that major biogeographic units can be clearly distinguished in the Verkhoyansk-Okhotsk on one side and Kolyma-Omolon biochores on the other, which can be currently ranked as sub regions. Verkhoyansk-Okhotsk sub region includes Verkhoyansk epicontinental sea shelf and the Okhotsk microcontinent shelf. These can be further subdivided into a number of provinces. The Kolyma-Omolon sub region includes continental shelves of the Omolon, Omulevka, Prykolyma microcontinents and the Koni-Taigonos arc. The degree of diversity of these two biochores is so great that it requires separate development and indicates the existence of a major biogeographical barrier during the Permian. The distinctions between the Verkhoyansk-Okhotsk and Kolyma-Omolon sub regions are found througout the whole Permian and over other faunal groups such as brachiopods and ammonites as well as over the rest of bivalve taxons. Multiple use of biogeographic, sedimentologic and paleomagnetic materials including new original data on sedimentology and paleomagnetism allowed a model of the relative positions of the basic tectonic structures of Verkhoyansk-Kolyma fold-and-thrust area in the second half of the Permian. . These studies have been supported by the Russian Foundation for Basic Research, grant N 03-05-96012-Arctic and Far East Branch Russian Academy of Sciences, Grant N 04-3-A-08-014.

Biakov, A.; Kolosev, E.

2004-12-01

217

Gondwana basins and their coal resources in Bangladesh  

International Nuclear Information System (INIS)

Fault bounded five Gondwana basins have been discovered in the north western Bangladesh. Among these basins show considerable amount of coal deposits. The Gondwana rocks are highly formed during the Permo-carboniferous diastrophism and later on acquired dynamic characters. In almost all basins, the Permian rocks overlie the Precambrian basement and underlie either the Tertiary or the Cretaceous sediments, structural, stratigraphic, and depositional history of these basins is more or less similar. The sedimentary sequences are composed of light to dark gray, fine to very coarse grained, sub angular to sub rounded felspathic sandstone, dark grey carbonaceous shale and sandstone, variegated conglomerate and thick coal seams (single seam max. 42.38m). The rocks are often alternated and bear the characteristics of cyclic sedimentation. The depositional environments varied from restricted drainage to open fluvial dominated low to moderate sinuous drainage system. The coal bearing basins were flanked by vegetated and swampy over bank. Age of these coals is suggested to be the late permian. Proved and probable reserves of coal in Jamalganj-Paharpur basin are 670 and 1,460 million metric tons, in Barapukuria basin 303 and 3899 million metric tons; in Barapukuria basin 303 and 389 million metric tons; and in Khalaspir basin 143 and 685 million metric tons respectively. The coal is high volatile, low sulphur, bituminous type. It can be used for different forms of thermal converssed for different forms of thermal conversion. (author)

218

Cyclic development of sedimentary basins at convergent plate margins — 1. Structural and tectono-thermal evolution of some gondwana basins of eastern Australia  

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The Devono-Carboniferous Drummond Basin of eastern Australia formed by extensional tectonics, most probably in a back-arc setting, as an oceanic plate subducted westward under Gondwana's continental margin. Within this basin a syn-rift sequence and a relatively thick post-rift sequence are recognized, and the latter is separated from the overlying Galilee Basin by a mid-Carboniferous unconformity, which heralds a time of relatively mild compression, uplift and folding. The lower Galilee Basin formed as a foreland, secondary peripheral bulge, or mixed-style basin during the Late Carboniferous to Early Permian time interval. A mid-Permian unconformity separates it from the extensive Late Permian to Mid-Triassic upper Galilee Basin, here suggested to be a platform basin. Nest, the main, Mid- to Late Triassic compressional event led to reverse movement along previously normal faults, folding, uplift and erosion of up to 2 km of section from the Galilee and Bowen basins. During Jurassic and Cretaceous times, the Eromanga/Surat/Carpentaria Basin, a platform basin originally >1.7 million km 2 in extent, developed cratonward of the zone of continuing subduction. Subsequently, the culminating extensional event took place further east, where Lord Howe Rise rifted apart from the continental landmass and drifted eastward as oceanic seafloor spread in the Tasman Basin, and widespread uplift and erosion occurred over the eastern Australian coastal area. New data, re-interpretation of existing data and extensive literature support the interpretation of the Phanerozoic tectonic evolution of eastern Australia in a context of convergent plate margins. Within this context, overall eastward migration through time of the subduction zone and associated morphotectonic entities (e.g. the Warburton, Adavale, Drummond, Bowen and Tasman extensional basins) and vertical stacking of unconformity-bound extensional, foreland and platform basins (e.g. the Drummond, Galilee and Eromanga basins) occurred.

de Caritat, Patrice; Braun, Jean

1992-12-01

219

Facies evolution and cyclicity of alluvial coal deposits in the Lower Permian of East Africa (Tanzania)  

Energy Technology Data Exchange (ETDEWEB)

The Ruhuhu Basin in SW Tanzania contains several small coal basins; Mchuchuma, Ngaka North, Mbalawala, Lumecha, consisting of fault controlled half-grabens submitted to several stages of tectonic activation. All basins underwent fragmentation in the middle Jurassic and late Miocene to Pliocene. Palaeotopography of pre-Karoo basement was partly responsible for the development of coal seam thickness distribution. Facies characteristics of the lower/middle and upper Mchuchuma Formation and the Scarp sandstone of the overlying Ketewaka formation exhibit synsedimentary basin subsidence. Vitrinite reflectance data suggest similar temperature gradients and burial history for Mchuchuma and Ngaka. A computer simulation program revealed the effect of post-sedimentary tilting of depositional surfaces. In Mchuchuma back rotation of the base of the economic coal seam was calculated at -2{degree}, Ngaka showed a back rotation of -6{degree}. Cyclicity was determined for both basins. Mainly fining upward cycles prevail, characteristic for a fluvial environment. The depositional model for Mchuchuma shows a meandering river system with a lower basal channel fill and upper overbank and flood plain sediments. Ngaka is tentatively attributed to a braided river system. Thinning of coal seams and increased ash in upper stratigraphic units depict deteriorating peat formation and preservation. Swamp water chemistry was responsible for peat preservation, channel configuration and differential compaction governed coal seam geometry. A slightly warmer climate than usually described for the Gondwana coals is proposed for the Lower Permian Tanzania coals. Microfloral evolution, eustatic sea level rises in the Sakmarian of Australia and available palaeotemperature curves suggest a mean annual temperature of 10-12{degree}C for a palaeolatitude of 60{degree}S.

Kreuser, T. (Universitaet zu Koeln, Koeln (Germany, F.R.). Geologisches Inst.)

1991-01-01

220

Structural evolution of the early Permian Nambucca Block (New England Orogen, eastern Australia) and implications for oroclinal bending  

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The Paleozoic to early Mesozoic southern New England Orogen of eastern Australia exhibits a remarkable ear-shaped curvature (orocline), but the geodynamic processes responsible for its formation are unclear. Oroclinal bending took place during the early Permian, simultaneously with the deposition of the rift-related Sydney, Gunnedah, and Bowen basins, which bound the oroclines to the west. The Nambucca Block is another early Permian rift basin, but it is situated in the core of the oroclinal structure. Here we present new stratigraphic, structural, and geochronological data from the Nambucca Block in an attempt to better understand its tectonic history and relationships to the formation of the oroclines. We recognized four phases of folding and associated structural fabrics (S1-4), with the second phase (S2) dated at 275-265 Ma by 40Ar/39Ar geochronology of muscovite. This age overlaps with independent constraints on the timing of oroclinal bending, suggesting that the earlier two phases of deformation in the Nambucca Block (F1 and F2) were associated with orocline formation. We propose that oroclinal bending involved three major stages. The first stage (plate coupling that was possibly linked to flat-slab subduction.

Shaanan, Uri; Rosenbaum, Gideon; Li, Pengfei; Vasconcelos, Paulo

2014-07-01

221

Palynostratigraphy and age correlation of subsurface strata within the sub-basins in Singrauli Gondwana Basin, India  

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In the study area, changes in the facies of sediments and spores-pollen content appear to be all causally linked with the depositional set-up. Here, the qualitative and quantitative changes observed in the spores-pollen assemblages have led to recognize 10 Assemblage-zones representing from that earliest Permian in the Talchir Formation to that latest Late Triassic in the Parsora Formation. These spores-pollen assemblages are obtained from the wider parts in the Singrauli Gondwana Basin that includes (i) Moher sub-basin (boreholes SSM-1 and 2), and (ii) Singrauli main sub-basin (boreholes SMJS-2, 3 and SMBS-1). The progressively changing spores-pollen content infer the hiatuses of varied magnitude in the sedimentary sequences during the extended time interval of Permian and Triassic.

Vijaya; Tripathi, Archana; Roy, A.; Mitra, Saibal

2012-08-01

222

The Permian mega floras of Uruguay.A synthesis  

International Nuclear Information System (INIS)

The Permian megafloras of Uruguay. A synthesis. An analysis of the impression and fossil wood floras from the Permian of Uruguay is given through a series of Tables. These show : (1) the list of taxa, (2) anatomical characters of the woods, (3) data on the microfloral associations, (4) paleoenvironmental information and (5) comparisons with contemporaneous Gondwana floras. The evolutionary degree of the woods is briefly analyzed where they correspond to the so-called ''transition xilotaphofloras'' as they present typical Paleozoic anatomical characters but with secondary xylem of more advanced characteristics. (author)

223

Upper Permian (Late Changhsingian) marine strata in Nan Province, northern Thailand  

Science.gov (United States)

In the Upper Permian of northeastern Thailand (Loei Province), continental plants have been found and to the north in Laos near Luang Prabang, continental vertebrates (Dicynodon species) have been discovered. The Middle Permian is in sharp contrast to this as it is represented only by marine sediments. West of these areas in the province of Nan in Thailand, the Upper Permian is represented by marine sediments which extend to a high level in the Upper Permian and continental beds appear to be entirely absent, at least at Pha Dang Khwai, a locality where limestone extends from the end of the Lower Permian to the Triassic.

Fontaine, Henri; Hoang, Thi Than; Kavinate, Sathaporn; Suteethorn, Varavudh; Vachard, Daniel

2013-10-01

224

Middle Permian plume-related volcanism of the Hawasina Nappes (Oman) and the Neo-Tethys opening  

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According to palinspastic reconstructions, the Neo-Tethys opening took place during the Permian between the Cimmerian fragments in the north and the Indian-Arabian margin in the south. Igneous remnants of this opening are found nowdays in Oman where they belong mostly to the Hawasina nappes and consist of pillowed mafic flows interbedded with Middle Permian sediments. Three groups of rocks have been distinguished among the Middle Permian rocks from Oman which were emplaced either on the Arabian submerged platform or the neighbouring Hawasina basin. Group 1 is tholeiitic and characterized by low TiO_2 (Group 1 volcanics are either (i) LREE-depleted, or (ii) with flat REE patterns or even (iii) slightly enriched in LREE. Group 1 plots at the boundary or within the MORB field in the Pb-Pb correlation diagrams and between the MORB and Bulk Silica Earth (BSE) fields in ?Ndi-(206Pb/204Pb)_i diagram. Group 2 is alkalic and differs from Group 1 by higher TiO_2, La and Nb contents, and lower and more homogeneous ?Ndi values (+3). Most of the Group 2 volcanics share with Group 1 similar initial Pb ratios.Group 3 differs from Groups 1 and 2 by low to negative ?Ndi (+1.6 to -2). It consists of tholeiitic (TiO_2-poor) and alkalic (TiO_2-rich) rocks which are either interbedded with carbonate-platform sediments from the Saih Hatat window or found with deep-sea sdiments from the Hawasina Nappes. Group 3 trace element chemistry is similar to that of Group 2. Thus, whatever the geological setting of the Oman Permian lavas, they belong to tholeiitic and alkalic magmas but differ by their Nd isotopic composition. A majority of the magmas emplaced in the Hawasina basin are characterized by ?Nd that fall within the range of OIB. In contrast, most of the volcanic rocks emplaced on the submerged Arabian platform and few samples from the Hawasina nappes have low to negative ?Ndi suggesting a contribution of continental crust.

Lapierre, H.; Samper, A.; Bosch, D.; Maury, R. C.; Cotten, J.; Béchennec, F.; Brunet, P.; Caroff, J.; Keller, F.; Demant, A.

2003-04-01

225

Permian plants from the Chutani Formation (Titicaca Group, Northern Altiplano of Bolivia: II. The morphogenus Glossopteris  

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Full Text Available Fossil plants belonging to the morphogenera Glossopteris, Pecopteris and Asterotheca were collected from the upper part of the Chutani Formation (Titicaca Group, near the town of San Pablo de Tiquina, on the southeastern shore of Lake Titicaca (northern Altiplano, Bolivia. This paper presents the first description of specimens of the morphogenus Glossopteris from Bolivia. The Bolivian specimens of Glossopteris consist of poorly-preserved impressions, although they present the diagnostic features of this morphogenus. They are fragments of leaves with secondary veins of taeniopterid-type, typical of glossopterids from Late Permian deposits of Gondwana. The only species of Pecopteris confirmed in the first part of this study, i.e. P. dolianitii Rösler and Rohn (see Vieira et al. 2004, was previously reported from the Late Permian beds of the Rio do Rasto and Estrada Nova formations in the Paraná Basin (southern Brazil. Therefore, a Late Permian age is proposed for the fossil plant-bearing beds of the Chutani Formation based on the analyzed assemblage. The phytogeographic implications of this new find are briefly analyzed.Plantas fósseis, pertencentes aos morfo-gêneros Glossopteris, Pecopteris e Asterotheca, foram coletadas na porção superior da seção aflorante da Formação Chutani, próxima ao povoado de San Pablo de Tiquina, sudeste do lago Titicaca (Altiplano norte, Bolívia. Este trabalho apresenta a primeira descrição de espécimes do morfo-gênero Glossopteris provenientes da Bolívia. Os espécimes estudados de Glossopteris consistem em impressões foliares pobremente preservadas nas quais feições diagnósticas estão presentes. Os fragmentos foliares apresentam venação secundária do tipo teniopteróide, uma característica típica de glossopterídeas encontradas em depósitos do Permiano Superior do Gondwana. Por sua vez, a única espécie de Pecopteris confirmada para estes níveis da Formação Chutani, i.e. P. dolianitii Rohn and Rösler (ver Vieira et al. 2004, foi previamente assinalada para estratos do Permiano Superior da Bacia do Paraná (formações Estrada Nova e Rio do Rasto. Portanto, uma idade neopermiana é tentativamente proposta para os níveis da Formação Chutani que contém a associação estudada. As implicações fitogeográficas deste novo achado são brevemente analisadas.

Roberto Iannuzzi

2004-03-01

226

Permian plants from the Chutani Formation (Titicaca Group, Northern Altiplano of Bolivia): II. The morphogenus Glossopteris  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Plantas fósseis, pertencentes aos morfo-gêneros Glossopteris, Pecopteris e Asterotheca, foram coletadas na porção superior da seção aflorante da Formação Chutani, próxima ao povoado de San Pablo de Tiquina, sudeste do lago Titicaca (Altiplano norte, Bolívia). Este trabalho apresenta a primeira descr [...] ição de espécimes do morfo-gênero Glossopteris provenientes da Bolívia. Os espécimes estudados de Glossopteris consistem em impressões foliares pobremente preservadas nas quais feições diagnósticas estão presentes. Os fragmentos foliares apresentam venação secundária do tipo teniopteróide, uma característica típica de glossopterídeas encontradas em depósitos do Permiano Superior do Gondwana. Por sua vez, a única espécie de Pecopteris confirmada para estes níveis da Formação Chutani, i.e. P. dolianitii Rohn and Rösler (ver Vieira et al. 2004), foi previamente assinalada para estratos do Permiano Superior da Bacia do Paraná (formações Estrada Nova e Rio do Rasto). Portanto, uma idade neopermiana é tentativamente proposta para os níveis da Formação Chutani que contém a associação estudada. As implicações fitogeográficas deste novo achado são brevemente analisadas. Abstract in english Fossil plants belonging to the morphogenera Glossopteris, Pecopteris and Asterotheca were collected from the upper part of the Chutani Formation (Titicaca Group), near the town of San Pablo de Tiquina, on the southeastern shore of Lake Titicaca (northern Altiplano, Bolivia). This paper presents the [...] first description of specimens of the morphogenus Glossopteris from Bolivia. The Bolivian specimens of Glossopteris consist of poorly-preserved impressions, although they present the diagnostic features of this morphogenus. They are fragments of leaves with secondary veins of taeniopterid-type, typical of glossopterids from Late Permian deposits of Gondwana. The only species of Pecopteris confirmed in the first part of this study, i.e. P. dolianitii Rösler and Rohn (see Vieira et al. 2004), was previously reported from the Late Permian beds of the Rio do Rasto and Estrada Nova formations in the Paraná Basin (southern Brazil). Therefore, a Late Permian age is proposed for the fossil plant-bearing beds of the Chutani Formation based on the analyzed assemblage. The phytogeographic implications of this new find are briefly analyzed.

Roberto, Iannuzzi; Carlos E. L., Vieira; Margot, Guerra-Sommer; Enrique, Díaz-Martínez; George W., Grader.

2004-03-01

227

Lipid Biomarker Records Across the Permian-Triassic Boundary from Kap Stosch, Greenland  

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The end-Permian extinction was the most severe in the past 500 million years of the Earth's history and evidence that an oceanic anoxic event (OAE) occurred contemporaneously has been presented previously [1,2]. OAEs have, therefore, been proposed as responsible for the mass mortality, and if the anoxic ocean was also euxinic, the release of hydrogen sulfide during upwelling and/or transgression provides an extinction agent in the ocean as well as on land. Chlorobiaceae, as indicators of photic zone euxinia (PZE), utilize hydrogen sulfide as an electron donor for anoxygenic photosynthesis. The detection of isorenieratane and a series of short-chain monoaromatic aryl isoprenoids, biomarkers for Chlorobiaceae, in sediments indicates the presence of hydrogen sulfide in the photic zone of the water column during sediment deposition. The Kap Stosch area in Eastern Greenland was identified as a Permian-Triassic boundary (PTB) outcrop of homogeneous shale, silty shale, and siltstone facies [3]. Another late Permian section in Eastern Greenland, the Ravnefjeld Formation, has framboidal pyrites indicative of sulfidic deep water [4]. A sample suite from the Kap Stosch region was studied using standard organic geochemistry methods including stable isotopic analyses of organic carbon, Rock-Eval pyrolysis, and biomarker hydrocarbon analysis. Aryl isoprenoids, including isorenieratane, were present in all samples studied and the concentrations were observed to fluctuate in tandem with TOC, similar to other Mesozoic OAEs. The molecular ratios of pristane/phytane and hopanes/steranes as well as the 2-methyl-hopane index (2-MHI) fluctuated dramatically through this section as they do at the type section at Meishan and in the Perth Basin [5]. The 2-MHI shows an inverse pattern to the total aryl isoprenoids, perhaps indicative of instability in the form of primary productivity in the water column during euxinic episodes. This can result in nitrogen limitation and a competitive advantage of cyanobacteria over microalgae for nutrient resources [6]. Overall, the biomarker patterns in these samples indicate the presence of PZE at this location leading up to and continuing through the PTB. 1. Isozaki Y., 1997. Science 276, 235. 2. Wignall P. and R. Twichett, 1996. Science 272, 1155. 3. Teichert C. and B. Kummel, 1972. Bull. Canadian Petrol. Geol. 20, 659. 4. Nielsen J. and Y. Shen, 2004. Geology 32, 1037. 5. Grice K., et al., 2005. Science 307, 706. 6. Kuypers M., et al., 2004. Geology 32, 853.

Hays, L. E.; Love, G. D.; Foster, C. B.; Grice, K.; Summons, R. E.

2006-12-01

228

Carboniferous and permian noeggerathialean plants and their spores; preliminary report.  

Czech Academy of Sciences Publication Activity Database

Prague : National Museum, 2006. ISBN 80-7036-198-0. [European Palaeobotany-Palynology Conference /7./. 06.09.2006-11.09.2006, Prague] R&D Projects: GA AV ?R IAA3013902 Institutional research plan: CEZ:AV0Z30130516 Keywords : Noeggerathiales * in situ spores * Palaeozoic-Permian Subject RIV: EF - Botanics

Bek, Ji?í; Wang, J.

229

Permian Triassic palynofloral transition in Chintalapudi area, Godavari Graben, Andhra Pradesh, India  

Science.gov (United States)

The entire 606 m-thick sedimentary sequence in borecore MCP-7 from Chintalapudi area, Chintalapudi sub-basin has been lithologically designated as Kamthi Formation. However, the palynological investigation revealed five distinct palynoassemblages, which essentially fall under two groups, one group (Palynoassemblage-I, II and III) having dominance of striate disaccates along with presence of some stratigraphically significant taxa, belongs to Late Permian (Raniganj) palynoflora, while the other group (Palynoassemblages IV and V) shows sharp decline in percentage of characteristic taxa of first group, i.e., striate disaccates, and consequent rise or dominance of taeniate and cingulate cavate spores, belongs to Early Triassic (Panchet) palynoflora. Palynoassemblage-I, II and III (Group I) are characterized by dominance of striate disaccates chiefly, Striatopodocarpites spp. and Faunipollenites spp. along with presence of rare but stratigraphically significant taxa, viz., Gondisporites raniganjensis, Falcisporites nuthaliensis, Klausipollenites schaubergeri, Chordasporites sp., Striomonosaccites, ovatus, Crescentipollenites multistriatus, Verticipollenites debiles, Strotersporites crassiletus, Guttulapollenites hannonicus, G. gondwanensis, Hamiapollenites insolitus, Corisaccites alutus, Lunatisporites ovatus, Weylandites spp. and Vitreisporites pallidus. Palynoassemblage-I is distinguished by significant presence of Densipollenites spp. while Palynoassemblage-II shows significant presence of Crescentipollenites spp. and Palynoassemblage-III differs from the above two assemblages in having significant presence of Guttulapollenites hannonicus. Palynoassemblage-IV (Group II) is characterized by high percentage of taeniate disaccates chiefly Lunatisporites spp., while Palynoassemblage-V (Group II) is characterized by cingulate-cavate trilete spores chiefly, Lundbladispora spp. and Densoisporites spp. Striate disaccates show a sharp decline in these two assemblages. In Chintalapudi area Late Permian and Early Triassic palynoflora has been recorded for the first time indicating existence of Raniganj and Panchet sediments as well. The study further supports the earlier studies of Jha and Srivastava (1996) that Kamthi Formation represents Early Triassic (=Panchet Formation) overlying Raniganj equivalent sediments with a gradational contact.

Jha, Neerja; Chary, M. Basava; Aggarwal, Neha

2012-10-01

230

Late Permian-Mesozoic events and the Mergui group Nappe in Myanmar and Thailand  

Science.gov (United States)

Re-interpretations of geological maps of Thailand and Myanmar, together with new geological data from northern Thailand, suggest that the continental Shan-Thai Block became accreted to the Indochina block to the east by closure of two Tethyan ocean basins, terminating in a late Norian collision with generation of anatectic granites. Lower Permian diamictites and associated rocks of the Mergui Group were not part of Shan-Thai until the late Triassic or early Jurassic, when they were emplaced as a nappe from the present west, perhaps as part of an early Mesozoic arc system rifted from Gondwanaland. Subsequent emplacement of an ophiolite and overlying east-facing mafic magmatic arc on to the western margin of the Shan-Thai-Mergui Group block in the early Cretaceous was followed by polarity reversal and development of the west-facing mid-Cretaceous to Quaternary Myanmar arc. During east-directed back-thrusting and crustal thickening, late Cretaceous to Eocene anatectic granites were intruded into the Mergui Group nappe and elevated Mogok belt metamorphics to the west. The inferred evolution of the region implies at least two reversals in tectonic polarity following ophiolite emplacement, and closure of four Tethyan ocean basins.

Mitchell, A. H. G.

231

Overview of the structural geology and tectonics of the Central Basin Platform, Delaware Basin, and Midland Basin, West Texas and New Mexico  

Energy Technology Data Exchange (ETDEWEB)

The structural geology and tectonics of the Permian Basin were investigated using an integrated approach incorporating satellite imagery, aeromagnetics, gravity, seismic, regional subsurface mapping and published literature. The two primary emphases were on: (1) delineating the temporal and spatial evolution of the regional stress state; and (2) calculating the amount of regional shortening or contraction. Secondary objectives included delineation of basement and shallower fault zones, identification of structural style, characterization of fractured zones, analysis of surficial linear features on satellite imagery and their correlation to deeper structures. Gandu Unit, also known as Andector Field at the Ellenburger level and Goldsmith Field at Permian and younger reservoir horizons, is the primary area of interest and lies in the northern part of Ector county. The field trends northwest across the county line into Andrews County. The field(s) are located along an Ellenburger thrust anticline trap on the eastern margin of the Central Basin Platform.

Hoak, T. [Kestrel Geoscience, Littleton, CO (United States); Sundberg, K. [Phillips Petroleum Co., Bartlesville, OK (United States); Ortoleva, P. [Indiana Univ., Bloomington, IN (United States)

1998-12-31

232

Paleotectonic reconstruction of the central Tethys domain since the Late Permian: the DARIUS Maps  

Science.gov (United States)

The DARIUS Programme is a 4-years consortium sponsored by Major Oil Companies and Research Organizations. DARIUS drive together a group of academic scientific teams whose expertise includes several domains of tectonics (structural analysis, paleotectonic reconstructions, basin analysis, subsidence modeling), stratigraphy (paleontology, sequence stratigraphy, organic matter analysis), modeling, kinematics, and geophysics. The main objective is characterizing the tecto-stratigraphic evolution of a vast domain around Central Tethys extending from Black-Sea Anatolia in the west to western Central Asia in the east. One of the final products of the DARIUS Programme is a set of 20 paleotectonic maps of the DARIUS domain ranging in age from the Late Permian to Pliocene. In these maps we propose paleotectonic reconstructions of the south-central Eurasian and north African-Arabian plates starting after the Late Paleozoic Hercynian orogeny. These palinspastic maps are based on an up-to-date kinematics reconstruction of the African, Indian and Arabian plates with respect to Eurasia. For each map we depict the major tectonic-geodynamic features (i.e. the rifts, different types of basins, major orogens and fold belts, main transcurrent faults, subduction zones, accretionary prisms...) as well as the main paleofacies. Our reconstructions are based on an accurate timing of the tectonic events that have succeeded in the central Tethyan margins since the Late Paleozoic. These events include both the main orogenies resulting from collisions of major plates and blocks and the series of openings and inversions of basins that developed in the northern and southern Tethyan margins between the main collisions. Following the Variscian orogeny that ended in the Early Permian, the Mid to Late Triassic Eo- and Mid-Cimmerian orogenies are related to the collision of Gondwanian blocs with the Pangea margin after closure of the Paleo-Tethys oceanic domain. Then, for the rest of the Mesozoic and Early Cenozoic mainly developed: (1) a northward subduction of the Neo-Tethys oceanic lithosphere beneath the southern Eurasian margin, and (2) a passive margin bordering the African-Arabian plate to the North. In this latter plate, riftings and basins developed until Late Cretaceous when the Neo-tethys ophiolites were obducted onto the Arabian passive margin. On the contrary, the North Tethys active margin recorded a complex tectonic evolution characterized by: (1) the opening of back-arc and marginal basins during the Triassic to Early-Mid Cretaceous times (e.g. Black Sea, Great Caucasus, South Caspian, Central Iran, Amu-Darya and Tadjik basins), and (2) regional compressions associated with the inversions and/or closure of these basins. The main inversions are Mid-Jurassic, Early Cretaceous, and uppermost Cretaceous-Paleogene in age. The first collision between major plates began in the Early Eocene when the northern Indian and southern Eurasian margins collided. The second one is the Arabia-Eurasia collision, which initiated in the Late Eocene. Both developed until Present, originating the Himalaya and Tien-Shan ranges and the Alpine chains respectively. After the complete closure of the remnant Tethyan oceanic domain, at the beginning of Neogene, the continent-continent collisions were developing all along the southern Eurasian active margin.

Barrier, Eric; Vrielynck, Bruno; Brunet, Marie-Françoise; Robertson, Alastair; Sosson, Marc; Zanchi, Andrea; Brouillet, Jean-françois; Kaveh, Frédéric

2014-05-01

233

Bringing dicynodonts back to life: paleobiology and anatomy of a new emydopoid genus from the Upper Permian of Mozambique.  

Science.gov (United States)

Dicynodontia represent the most diverse tetrapod group during the Late Permian. They survived the Permo-Triassic extinction and are central to understanding Permo-Triassic terrestrial ecosystems. Although extensively studied, several aspects of dicynodont paleobiology such as, neuroanatomy, inner ear morphology and internal cranial anatomy remain obscure. Here we describe a new dicynodont (Therapsida, Anomodontia) from northern Mozambique: Niassodon mfumukasi gen. et sp. nov. The holotype ML1620 was collected from the Late Permian K5 formation, Metangula Graben, Niassa Province northern Mozambique, an almost completely unexplored basin and country for vertebrate paleontology. Synchrotron radiation based micro-computed tomography (SRµCT), combined with a phylogenetic analysis, demonstrates a set of characters shared with Emydopoidea. All individual bones were digitally segmented allowing a 3D visualization of each element. In addition, we reconstructed the osseous labyrinth, endocast, cranial nerves and vasculature. The brain is narrow and the cerebellum is broader than the forebrain, resembling the conservative, "reptilian-grade" morphology of other non-mammalian therapsids, but the enlarged paraflocculi occupy the same relative volume as in birds. The orientation of the horizontal semicircular canals indicates a slightly more dorsally tilted head posture than previously assumed in other dicynodonts. In addition, synchrotron data shows a secondary center of ossification in the femur. Thus ML1620 represents, to our knowledge, the oldest fossil evidence of a secondary center of ossification, pushing back the evolutionary origins of this feature. The fact that the specimen represents a new species indicates that the Late Permian tetrapod fauna of east Africa is still incompletely known. PMID:24324653

Castanhinha, Rui; Araújo, Ricardo; Júnior, Luís C; Angielczyk, Kenneth D; Martins, Gabriel G; Martins, Rui M S; Chaouiya, Claudine; Beckmann, Felix; Wilde, Fabian

2013-01-01

234

Repository site data and information in bedded salt: Palo Duro Basin, Texas  

International Nuclear Information System (INIS)

This report is a compilation of data from the literature on the Palo Duro Basin. The Palo Duro Basin is a structural basin, about 150 miles long and 80 miles wide, that is a part of the much larger Permian Basin. The US Department of Energy is investigating the Palo Duro Basin as a potentially suitable area for the site of a repository for the disposal of high-level radioactive waste. Sediments overlying the Precambrian basement range from about 5000 to about 11,000 ft in thickness and from Cambrian to Holocene in age. The strata in the Palo Duro Basin that are of primary interest to the Department of Energy are the bedded salts of the Permian San Andres Formation. The total thickness of the bedded salts is about 2000 ft. The geology of the Palo Duro Basin is well understood. A great deal of information exists on the properties of salt, although much of the available information was not collected in the Palo Duro Basin. Mineral resources are not currently being exploited from the center of the Palo Duro Basin at depth, although the possibility of exploration for and development of such resources can not be ruled out. The continued existence of salts of Permian age indicates a lack of any large amount of circulating ground water. The hydrology of the pre-Tertiary rocks, however, is currently too poorly understood to carry out detailed, site-specific hydrologic modeling with a high degree of confidence. In general, ground water flows from west to east in the Basin. Therflows from west to east in the Basin. There is little or no hydraulic connection between aquifers above and below the salt sequences. Potable water is pumped from the Ogallala aquifer. Most of the other aquifers yield only nonpotable water. More extensive hydrological data are needed for detailed future modeling in support of risk assessment for a possible repository for high-level waste in the Palo Duro Basin. 464 references

235

Permian basalts and trachytes from Esterel (SE France): a transitional tholeiitic suite emplaced during lithosphere thinning; Basaltes et trachytes permiens de l`Esterel (SE France): une serie tholeiitique transitionnelle epanchee pendant l`amincissement lithospherique  

Energy Technology Data Exchange (ETDEWEB)

Geochemical (major, trace and rare earth elements) and isotopic ({sup 143}Nd/{sup 144}Nd) compositions of lavas emplaced in the Esterel Massif (eastern Provence, France) at the end of the Permian allow to estimate the evolution of the continental lithosphere between the end of the Hercynian orogenesis and the beginning of the Tethyan rifting. Basalts from Agay basin and trachyte from Batterie des Lions belong to a transitional tholeiitic suite, characterized by negative Nb and Ta anomalies (relative to N-MORB) and homogeneous {epsilon}Nd{sub (T=250Ma)} ratios, close to the Bulk Earth. This suggests that the basalts from Agay basin and trachyte from Batterie des Lions derived from the partial melting of a mantle contaminated by lower continental crust. Maure Vieille trachytes differ from the differentiated rocks of the transitional suite by higher heavy rare earth abundances and {epsilon}Nd{sub (T=250Ma)} of +4/+5. These high {xi}Nd ratios suggest that the Maure Vieille trachytes could derive from the partial melting of a more depleted source, likely an asthenospheric mantle. The isotopic compositions of the Permian lavas from Esterel suggest the thinning (and perhaps the disappearance) of the lithospheric mantle which is associated at the surface with a NNW-SSE extension. The progressive change recorded in Agay basin from a stretching regime to a strike-slip regime may be related to the end of the lithospheric thinning and of the Permian magmatism. (authors) 37 refs.

Lapierre, H.; Basile, Ch. [Grenoble-1 Univ., 38 - Grenoble (France). Laboratoire de Geodynamique des Chaines Alpines, CNRS UPRES-A5025; Dupuis, V. [Institut de Geodynamique, UMR Geosciences Azur, 06 - Valbonne (France)

1999-11-01

236

Source, evolution and emplacement of Permian Tarim Basalts: Evidence from U-Pb dating, Sr-Nd-Pb-Hf isotope systematics and whole rock geochemistry of basalts from the Keping area, Xinjiang Uygur Autonomous region, northwest China  

Science.gov (United States)

Permian basalts distribute at least 250,000 km2, and underlie the southwest Tarim Basin in Xinjiang Uygur Autonomous region, northwest China. This vast accumulation of basalt is the main part of the Tarim Large Igneous Province (LIP). The basaltic units in the Lower Permian Kupukuziman and Kaipaizileike Formations in the Keping area, Tarim Basin; were the best exposure of the Permian basalt sequence in the basin. LA-ICP-MS U-Pb dating of zircon from the basal basaltic unit in the section gives an age of 291.9 ± 2.2 Ma (MSWD = 0.30, n = 17); this age, combined with previously published geochronological data, indicates that the basalts in the Tarim Basin were emplaced between 292 Ma and 272 Ma, with about 90% of the basalts being emplaced between 292 and 287 Ma. Basalts from the Keping area have high FeOT (10.8-18.6 wt.%), low Mg#s (0.26-0.60), and exhibit primitive mantle normalized patterns with positive Pb, P and Ti but negative Zr, Y and Ta anomalies. The basalts from both formations have similar 206Pb/204Pb (18.192-18.934), 207Pb/204Pb (15.555-15.598) and 208Pb/204Pb (38.643-38.793) ratios. The basalts also have high ?Sr(t) (45.7-62.1), low ?Nd(t) (-3.6 to -2.2) and low zircon ?Hf(t) (-4.84 to -0.65) values. These characteristics are typical of alkali basalts and suggest that the basalts within the Tarim Basin were derived from an OIB-type mantle source and interacted with enriched mantle (EMI-type) before emplacement. Rare earth element systematics indicate that the parental melts for the basalts were high-degree partial melts derived from garnet lherzolite mantle at the base of the lithosphere. Prior to emplacement, the Tarim Permian Basalts (TPB) underwent fractional crystallization and assimilated crustal material; the basalts were finally emplaced during crustal extension in an intra-plate setting. The wide distribution, deep source and high degree partial melting of the TPB was consistent with a mantle plume origin. The TPB and other coeval igneous rocks in the Tarim Basin constitute a Permian LIP formed by a mantle plume in a similar fashion to the plume-related Emeishan LIP in southwest China.

Zhang, Dayu; Zhou, Taofa; Yuan, Feng; Jowitt, Simon M.; Fan, Yu; Liu, Shuai

2012-04-01

237

Palynological evidence for the age of the Permian Karoo coal deposits near Vereeniging, northern Orange Free State, South Africa  

Energy Technology Data Exchange (ETDEWEB)

Palynological investigations of the coal-bearing strata of the Vereeniging area, Orange Free State Coalfield, have led to an interpretation of the age of the northern coal measures of the Main Karoo Basin. The sequence, part of the Vryheid Formation, is composed of three major coal seams, these being the Bottom, Middle, and Top Seams. The well-preserved palynoflora obtained from the sequence allows correlation of the Vereeniging coal seams with the coal-bearing sequence of the Witbank/Highveld coalfields. The age determination of the sequence is dependent upon comparison of the ranges of [ital Granulatisporites trisinus] Balme and Hennelly, 1956, [ital Pseudoreticulatispora pseudoreticulata] (Balme and Hennelly) Bharadwaj and Srivastava, 1969 and [ital Praecolpatites sinuosus] (Balme and Hennelly) Bharadwaj and Srivastava, 1969 with their distribution in the better understood Australian Permian sequences. An Artinskian (Aktastinian to lower Baigendzhinian) age for the Vryheid Formation is suggested. The determination of the age and correlation of these strata is important as they are associated with historically significant plant macrofossil deposits, which were important in the development of the Permian chronostratigraphy of South Africa and Gondwana. 48 refs., 4 figs.

Millsteed, B.D. (Geological Survey of South Africa, Pretoria (South Africa))

1994-03-01

238

The Triassic dicynodont Kombuisia (Synapsida, Anomodontia) from Antarctica, a refuge from the terrestrial Permian-Triassic mass extinction.  

Science.gov (United States)

Fossils from the central Transantarctic Mountains in Antarctica are referred to a new species of the Triassic genus Kombuisia, one of four dicynodont lineages known to survive the end-Permian mass extinction. The specimens show a unique combination of characters only present in this genus, but the new species can be distinguished from the type species of the genus, Kombuisia frerensis, by the presence of a reduced but slit-like pineal foramen and the lack of contact between the postorbitals. Although incomplete, the Antarctic specimens are significant because Kombuisia was previously known only from the South African Karoo Basin and the new specimens extend the taxon's biogeographic range to a wider portion of southern Pangaea. In addition, the new finds extend the known stratigraphic range of Kombuisia from the Middle Triassic subzone B of the Cynognathus Assemblage Zone into rocks that are equivalent in age to the Lower Triassic Lystrosaurus Assemblage Zone, shortening the proposed ghost lineage of this taxon. Most importantly, the occurrence of Kombuisia and Lystrosaurus mccaigi in the Lower Triassic of Antarctica suggests that this area served as a refuge from some of the effects of the end-Permian extinction. The composition of the lower Fremouw Formation fauna implies a community structure similar to that of the ecologically anomalous Lystrosaurus Assemblage Zone of South Africa, providing additional evidence for widespread ecological disturbance in the extinction's aftermath. PMID:19956920

Fröbisch, Jörg; Angielczyk, Kenneth D; Sidor, Christian A

2010-02-01

239

The formation of Serra Alta, Teresina and Rio do Rasto, Brazil, in the SP-23-PR (Permian, Passa Dois group, and the eastern border of the Parana basin) borehole; As Formacoes Serra Alta, Teresina e Rio do Rasto no furo de sondagem SP-23-PR (Permiano, Grupo Passa Dois, Borda Leste da Bacia do Parana)  

Energy Technology Data Exchange (ETDEWEB)

The borehole SP-23-PR of the CPRM company, located in Congonhinhas-PR (UTM coord. 7374.863N/545.384E at an altitude of 953,64m), has the longest cored interval of the Passa Dois Group, in the eastern border of the Parana Basin. The Serra Alta and the Teresina formations and the Serrinha Member of the Rio do Rasto Formation, in an approximately 600 m long vertical succession, were analysed with emphasis to the lithofaciology and to the lithostratigraphic boundaries. Almost the whole interval is siliciclastic, but there are many carbonatic intercalations, which were studied in detail. The borehole shows a gradual contact between the Serra Alta and Teresina formations, suggesting a transition from distal and low energy environments to shallow or coastal settings of an interior sea, dominated by storm waves, in an intracratonic large basin. The carbonates of the Teresina Formation are decimetric, mainly micritic and oosparitic, frequently impure and amalgamated, with abundant ostracodes and endemic bivalves, correlationable for long distances (according to the interpreted other borehole wireline logs), and they were probably originated during drier climatic intervals. The boundary between the Teresina and the Rio do Rasto formations is abrupt, probably discordant, characterized by the appearance of thick sandstones, but still occurring micritic and coquine intercalations. There also appear abundant fossil conchostracans, which indicate continental aquatic environments. (author)

Rohn, Rosemarie; Lourenco, Augusto Tortolero Araujo [UNESP, Rio Claro (Brazil)]. E-mail: rohn@rc.unesp.br; atal20@bol.com.br; Meglhioratti, Thiago [UNESP, Rio Claro (Brazil). Dept. de Geologia]. E-mail: madmaxth@yahoo.com.br

2003-07-01

240

Latest Permian Deep-Water Ostracod (Crustacea) Fauna from South China  

OpenAIRE

As the other marine organisms, ostracods suffered drastic change during the end-Permian mass extinction, the largest event among the "Big Five" in the Phanerozoic history. In South China, Late Permian strata are well and widely exposed, which provides the great availability for related studies. Previous studies on Late Permian shallow water ostracod faunas in South China have been evolved in the taxonomy, biostratigraphy and palaeoenvironment. These studies have greatly increased our knowledg...

Yuan, Aihua

2008-01-01

241

Area environmental characterization report of the Dalhart and Palo Duro basins in the Texas Panhandle. Volume I. Dalhart Basin  

International Nuclear Information System (INIS)

This area report describes the environmental characteristics of the Dalhart and Palo Duro basins of the Texas Panhandle portion of the Permian basin. Both basins are rather sparsely populated, and the overall population is decreasing. The economic base is centered on agribusiness and manufacturing. Most of the potentially conflicting land uses in both basins (i.e., parks, historic sites) occupy small land areas, with the exception of a national grassland in the Dalhart and military air training routes in both basins. Ground transportation in the Dalhart basin is adequate, and it is well developed in the Palo Duro basin. In both basins irrigation constitutes the principal water use, and groundwater is the principal source. However, the dominant aquifer, the Ogallala, is being depleted. Both basins consist primarily of grasslands, rangelands, and agricultural areas. No critical terrestrial or aquatic habitats have been identified in the basins, though several endangered, threatened, or rare terrestrial species occur in or near the basins. Aquatic resources in both basins are limited because of the intermittent availability of water and the high salt content of some water bodies. Playa lakes are common, though usually seasonal or rain dependent. The climate of the area is semiarid, with low humidity, relatively high wind speeds, and highly variable prcipitation. Restrictive dispersion conditions are infrequent. National ambient secondary air quality standards for particuecondary air quality standards for particulates are being exceeded in the area, largely because of fugitive dust, although there are some particulate point sources

242

Permian U-Pb (CA-TIMS) zircon ages from Australia and China: Constraining the time scale of environmental and biotic change  

Science.gov (United States)

In eastern Australia, the interconnected Bowen and Sydney Basins are filled with terrestrial sediments of late Paleozoic to early Mesozoic age. These sedimentary units record significant evolutionary events of eastern Gondwana during the time interval between two major mass extinctions (end Middle Permian and Permian-Triassic), and also provide lithological evidence for the Carboniferous-Permian Late Paleozoic Ice Age of southern Pangea, considered to be divisible into up to seven discrete glaciation events in Australia [e.g., 1]. These glaciations are currently assigned ages that indicate that the last of the glaciations predate the end Middle Permian mass extinction at ca. 260 Ma. However, the estimates for the time and durations are largely based on biostratigraphy and lithostratigraphy that, in the absence of robust and precise radioisotopic ages, are unacceptably fragile for providing an accurate high-resolution framework. Interbedded with the sediments are numerous tuff layers that contain zircon, many of which are associated with extensive coal measures in the Sydney and Bowen Basins. Published SHRIMP U-Pb zircon ages [2, 3] have been shown to be less precise and inaccurate when compared to ages applying the CA-TIMS method to the same horizons. Also within the late Middle Permian, the eruption of the Emeishan flood basalts in SW China has been proposed to have caused the end Middle Permian mass extinction [e.g., 4], though a causal link between these events demands a rigorous test that can only be provided by high-resolution geochronology. We present new U-Pb (CA-TIMS) zircon ages on tuff layers from the Sydney and Bowen Basins, with the purpose of generating a timescale for the Upper Permian of Australia to allow correlation with different parts of the world. Initial results, with permil precision, date a tuff layer within the uppermost Bandanna Fm. to ca. 252 Ma, a tuff within the Moranbah Coal Measures to ca. 256 Ma, and a tuff within the Ingelara Fm. to ca. 257 Ma, the latter two units lying stratigraphically below the latest identified glacial deposits. U-Pb (CA-TIMS) results on zircons from the Emeishan flood basalts and related volcanic products confirm the end-Guadalupian age (ca. 260 Ma) of the magmatism, and based on present data, place the Emeishan volcanic event (and its possibly associated mass extinction) within the occurrence of the Late Paleozoic Ice Age. This study’s primary goal is the establishment of a chronostratigraphic framework that would allow the integration of calibrated records from both terrestrial and marine units from different parts of the world in order to constrain the timing and rates of extinctions and recoveries in different locations and physical environments. [1] Fielding et al. (2008), J. Geol Soc. Lon., v. 165, pp. 129-140 [2] Michaelsen et al. (2001), Aus. J. Earth Sci., v. 48, pp. 183-192 [3] Roberts et al. (1996), Aus. J. Earth Sci., v. 43, pp. 401-421 [4] He et al. (2007), EPSL, v. 255, pp. 306-323

Denyszyn, S. W.; Mundil, R.; Metcalfe, I.; He, B.

2010-12-01

243

Palynostratigraphic correlation of the Sardhai Formation (Permian) of Pakistan  

OpenAIRE

Palynological assemblages from the Sardhai Formation shale (Permian), lying between the red-bed Warchha Formation and the Amb Formation limestones in the Salt and Khisor ranges of Pakistan contain abundant bisaccate pollen grains and few spores. In particular, well-preserved specimens of Florinites? balmei, a bilaterally symmetrical monosaccate pollen grain, are common. The presence of this pollen and the stratigraphic context suggest that the Sardhai Formation correlates with the Khuff trans...

Jan, Irfan U.; Stephenson, Michael H.; Khan, Fazli R.

2009-01-01

244

Numerical modeling of regional ground-water flow in the deep-basin brine aquifer of the Palo Duro Basin, Texas Panhandle  

International Nuclear Information System (INIS)

Bedded Permian-age evaporite sequences in the Palo Duro Basin are being considered for a permanent nuclear waste repository by the U.S. Department of Energy. The purpose of this modeling study is to provide an understanding of regional ground-water flow in the formations beneath the Permian evaporite section. From this understanding, more detailed, smaller scale studies can be designed. This study is also intended to provide a better understanding of the boundary conditions and permeabilities of the aquifer and aquitard system as well as provide estimates of ground-water travel times across the basin. Numerical simulations were made of the Wolfcamp aquifer modeled as a single layer and of the entire Deep-Basin Brine aquifer system, including the Wolfcamp aquifer, modeled as a single layer

245

Repository site data and information in bedded salt: Palo Duro Basin, Texas  

Energy Technology Data Exchange (ETDEWEB)

This report is a compilation of data from the literature on the Palo Duro Basin. The Palo Duro Basin is a structural basin, about 150 miles long and 80 miles wide, that is a part of the much larger Permian Basin. The US Department of Energy is investigating the Palo Duro Basin as a potentially suitable area for the site of a repository for the disposal of high-level radioactive waste. Sediments overlying the Precambrian basement range from about 5000 to about 11,000 ft in thickness and from Cambrian to Holocene in age. The strata in the Palo Duro Basin that are of primary interest to the Department of Energy are the bedded salts of the Permian San Andres Formation. The total thickness of the bedded salts is about 2000 ft. The geology of the Palo Duro Basin is well understood. A great deal of information exists on the properties of salt, although much of the available information was not collected in the Palo Duro Basin. Mineral resources are not currently being exploited from the center of the Palo Duro Basin at depth, although the possibility of exploration for and development of such resources can not be ruled out. The continued existence of salts of Permian age indicates a lack of any large amount of circulating ground water. The hydrology of the pre-Tertiary rocks, however, is currently too poorly understood to carry out detailed, site-specific hydrologic modeling with a high degree of confidence. In general, ground water flows from west to east in the Basin. There is little or no hydraulic connection between aquifers above and below the salt sequences. Potable water is pumped from the Ogallala aquifer. Most of the other aquifers yield only nonpotable water. More extensive hydrological data are needed for detailed future modeling in support of risk assessment for a possible repository for high-level waste in the Palo Duro Basin. 464 references.

Tien, P.; Nimick, F.B.; Muller, A.B.; Davis, P.A.; Guzowski, R.V.; Duda, L.E.; Hunter, R.L.

1983-11-01

246

Hooked: Habits of the Chinese Permian gigantopterid Gigantonoclea  

Science.gov (United States)

Based upon anatomical evidence, Permian aged gigantopterid fossils are in general reconstructed as climbing or scrambling plants. Gigantonoclea, a genus of adpressed gigantopterid foliage from the Permian of northern China, has been reported to co-occur with hook-like organs that were interpreted as indicating a scrambling/climbing habit. We reinvestigated these hook-like structures and re-evaluated the nature of the co-occurrences in context with the flora preserved in each plant-bearing fossil 'bed' in the North China sedimentary succession. New findings show that the species Gigantonoclea hallei probably climbed using specially adapted clusters of compound grappling hook-like shoots borne on the stems. This structural arrangement comprising shoots of hooks is new to the scrambling/climbing concept in gigantopterids. However, a key figured specimen previously reported as showing intermediate hook-tipped leaf morphology on a sole pinnule tip is discounted as such and is reinterpreted as a 'normal' pinnule partially hidden under sediment that results in an unusual appearance to this pinnule tip. Adaptations for climbing or scrambling based upon 'hooked leaves' observed in Gigantonoclea lagrelii are no longer supported and are reinterpreted as incompletely expanded leaves where the vernation process was interrupted. These data weaken prior interpretations of G. lagrelii as a climber/scrambler and raise doubts about the ubiquity of hooks amongst the gigantopterids as structures enabling them to climb or scramble their way through the Permian world.

Seyfullah, Leyla J.; Glasspool, Ian J.; Hilton, Jason

2014-04-01

247

Regional depositional systems tracts, paleogeography, and sequence stratigraphy, upper Pennsylvanian and lower Permian strata, North-and-West-Central Texas  

Energy Technology Data Exchange (ETDEWEB)

This book provides a regional stratigraphic and depositional framework of the Virgilian and Wolfcampian Series of North-Central Texas. The authors have identified 16 major and several minor depositional sequences, commonly called cyclothems, deposited during Late Pennsylvanian and Early Permian regressive-transgressive episodes. These cyclothems were mapped from outcrop across the Eastern Shelf and into the Midland Basin. Seventeen maps and 23 cross-sections were constructed to show regional net-sandstone distribution within siliciclastic systems, to document sequential depositional history and paleogeography, to analyze depositional response to paleobathymetry and tectonics, and to offer a regional sequence-stratigraphic framework for evaluating controls on relative sea level. Regional perspective provided by the map series will stimulate new ideas about inadequately tested sandstone trends and unrealized stratigraphic-trap potential in this large, mature petroleum province.

Brown, L.F.; Solis-Iriarte, R.F.; Johns, D.A.

1990-01-01

248

The marine Permian of East and Northeast Asia: an overview of biostratigraphy, palaeobiogeography and palaeogeographical implications  

Science.gov (United States)

The Permian marine biostratigraphy, faunal successions and mutual correlations (where possible) throughout East and Northeast Asia are synthesized, region by region, based on both published literature and the author's field observations in certain parts of the region. The correlation of the Permian marine successions of NE Asia with the Permian international timescale and, in particular, with Gondwanan Permian marine sequences remains a major challenge, due to profound marine provincialism during the Permian. However, by employing biogeographically mixed faunas from East Asia (SE Mongolia, NE China, South Primorye of Far East Russia and the South Kitakami Terrane of Japan) as 'biostratigraphic gateways', coupled with some bipolarly and bi-temperately shared Permian marine taxa and faunas, it has been possible to correlate, with reasonable confidence, some of the high-palaeolatitude Permian marine rock units and faunas of NE Asia with those of the Tethyan region and Gondwana. Palaeobiogeographically, the Permian marine faunas of East and NE Asia are assigned to four major provinces: Verkolyman, Sino-Mongolian-Japanese, Cathaysian and Panthalassan provinces, on the basis of their palaeogeographical distribution patterns and characteristics of faunal assemblages. Of these, the Sino-Mongolian-Japanese Province has considerable significance for regional palaeogeographical, plate tectonic and palaeoceanographical reconstructions during the Middle Permian, because of its conspicuously mixed cool- and warm-water marine biota. The origin of this biogeographically mixed marine biota is interpreted to have resulted from a combination of some key factors, including the increased tectonic convergence between the Bureya-Jiamusi Terrane and the Sino-Korean Platform during the Permian and the intermingling of both warm- and cold-water ocean currents off the eastern coastal areas of the Bureya-Jiamusi Terrane and the Sino-Korean Platform during the Middle Permian.

Shi, G. R.

2006-03-01

249

Permian ultrafelsic A-type granite from Besar Islands group, Johor, peninsular Malaysia  

Science.gov (United States)

The granitic rocks of the peninsula have traditionally been divided into two provinces, i.e., Western and Eastern provinces, corresponding to S- and I-type granite respectively. The Western Province granite is characterised by megacrystic and coarse-grained biotite, tin-mineralised, continental collision granite, whereas, the Eastern Province granite is bimodal I-type dominated by granodiorite and associated gabbroic of arc type granite. This paper reports the occurrence of an A-type granite from peninsular Malaysia. The rocks occur in the Besar, Tengah, and Hujung islands located in the southeastern part of the peninsula. The granite is highly felsic with SiO2 ranging from 75.70% to 77.90% (differentiation index = 94.2-97.04). It is weakly peraluminous (average ACNK =1.02), has normative hypersthene (0.09-2.19%) and high alkali content (8.32-8.60%). The granites have many A-type characteristics, among them are shallow level of emplacement, high Ga, FeT/MgO and low P, Sr, Ti, CaO and Nb. Calculated zircon saturation temperatures for the Besar magma ranging from 793 ? to 806 ?C is consistent with high temperature partial melting of a felsic infracrustal source which is taken as one of the mechanisms to produce A-type magma. The occurrence of the A-type granite can be related to the extensional back arc basin in the Indo-China terrane during the earliest Permian.

Ghani, Azman A.; Hazad, Fatin Izzani; Jamil, Azmiah; Xiang, Quek Long; Atiqah Wan Ismail, Wan Nur; Chung, Sun-Lin; Lai, Yu-Ming; Roselee, Muhammad Hatta; Islami, Nur; Nyein, Kyaw Kyaw; Amir Hassan, Meor Hakif; Abu Bakar, Mohd Farid; Umor, Mohd Rozi

2014-12-01

250

Permian palynostratigraphy and palaeoclimate of Lingala-Koyagudem coalbelt, Godavari Graben, Andhra Pradesh, India  

Science.gov (United States)

Godavari Graben, one of the biggest basins among several Gondwana basins of India, holds a unique position not only because of its geographical location in South India, but also due to the presence of almost complete succession from Permian to Cretaceous sediments. The Graben is traversed by many small faults due to which the dating and correlation of coal bearing horizons is difficult in this area. As palynology is one of the most reliable parameter for dating, correlation and characterization of continental deposits, palynological studies have been carried out in order to date and correlate the coal bearing horizons of Gundala, Mamakannu and Kachinapalli areas from Lingala-Koyagudem coalbelt of Godavari Graben.The distributional pattern of various palynotaxa has suggested the occurrence of eight distinct palynozones in five borecores of Gundala (MLG-23, MLG-24, and MLG-28), Mamakannu (MMK-19) and Kachinapalli (MGK-6) areas. These palynozones are comparable to Talchir, Lower Karharbari, Upper Karharbari, Barakar and Raniganj palynoflora of Indian Lower Gondwana. Palynozone-1 is equivalent to Parasaccites Assemblage of Talchir Palynoflora; Palynozone-2 is correlatable with Callumispora + Parasaccites Assemblage of Lower Karharbari palynoflora; Palynozone-3 corresponds well with Parasaccites + Scheuringipollenites Assemblage of Upper Karharbari palynoflora; Palynozone-4 is comparable to Scheuringipollenites Assemblage of Barakar palynoflora; Palynozone-5 is correlatable with Faunipollenites + Striatopodocarpites Assemblage of Raniganj palynoflora; Palynozone-6 is comparable with Striasulcites Assemblage of Raniganj palynoflora; Palynozone-7 shows its equivalence with Parasaccites Assemblage of Raniganj palynoflora and Palynozone-8 corresponds well with the Crescentipollenites Assemblage of Raniganj palynoflora. On the basis of palynofloral evidences, it has been suggested that palaeoclimate during Palynozone 1-3 was cool but humidity was more in Palynozone-3 in comparison to Palynozone-2. Warmer phase started during Palynozone-4 with thick coal deposits, while Palynozones 5-8 representing Raniganj palynoflora indicate warm climate with very high humidity.

Aggarwal, Neha; Jha, Neerja

2013-03-01

251

Paleozoic of the post-Variscan platform in the Bohemian Massif and its environs: Upper Permian.  

Czech Academy of Sciences Publication Activity Database

Prague : Czech Geological Survey, 2010 - (Cháb, J.), s. 215-216 ISBN 978-80-7075-747-5 Institutional research plan: CEZ:AV0Z30130516 Keywords : Permian * Upper Permian * Bohemian Massif * post-Variscan platform Subject RIV: DB - Geology ; Mineralogy

Cháb, J.; Zajíc, Jaroslav

252

[Insects at the borderline between the Permian and the early triassic (Urzhum - Olenek age) and the problem of Permian-Triassic biodiversity crisis].  

Science.gov (United States)

Distribution of 115 insect families is considered in 15 local assemblages of European Russia, Siberia, Australia and South Africa. The assemblage ages embrace the Urzhum stage of the Middle Permian, the Late Permian, and the transitional Permian-Triassic interval. The assemblages are ordered statistically using two criteria. Ordination after the appearance of a fauna, that is, relation of the number of younger vs. older families, is found to be generally consistent with the stratigraphic data. The method of minimizing the gaps (ghost ranges) in distribution of the families is useful in interpreting the results. Urzhum time is characterized by the balance of emergence and extinction of families (counted as their first and latest appearances, respectively). In Severodvinsk and particularly in Vyatka time, the number of first appearances was decreasing resulted in prevailing extinction. In the transitional Permian-Triassic interval, the emergence of new families accelerated. Initially, the appearance of assemblages was typically Paleozoic (with older families prevailed). It changed gradually, so as by the end of Vyatka time it turned to be quite post-Paleozoic. Diversity was the highest in Severodvinsk time, and it halved at Vyatka time and at the transition interval. However, if we consider transitional families (those not found on a particular interval, but known before and after), the extinction rate reduces to one-third. And when normalized after the material volume, the diversity drop decreases up to a quarter. There was no mass extinction found at the end of the Permian, and the less so at the Permian-Triassic boundary and during the Lower Triassic. Structure of the Permian-Triassic diversity crisis is similar to that of the Cretaceous crisis in many respects. Since the Middle Triassic and up to now, the biodiversity kept increasing quickly and continuously. This implies that the Permian-Triassic crisis resulted in profound modification of the biosphere structure, so as its capacity increased manifold. PMID:23659113

Rasnitsyn, A P; Aristov, D S; Rasnitsyn, D A

2013-01-01

253

The Permian post-orogenic collapse in the Alps: insights from the Campo unit (Austroalpine nappes, N-Italy, SE-Switzerland)  

Science.gov (United States)

The final stage of the Variscan orogeny (310-270 Ma) is characterized by an intense tectonic, magmatic and metamorphic event. During the Permian, acid and mafic intrusions were emplaced at all crustal levels and are associated to high-temperature contact metamorphism. While most of the studies focus either on the formation of Permian basins or on the lower crustal magmatic and metamorphic evolution, the characterization of the middle crust is lacking. Therefore, this study aims to unravel the processes active at mid-crustal levels during the Permian. We investigate the contact aureole of the Sondalo gabbro emplaced in a mid-crustal position during the Permian, exposed in the Austroalpine Campo unit (N-Italy). This work is based on a multidisciplinary approach linking structural geology, metamorphic petrology and geochronology. The country rock of the gabbroic intrusion is composed of Grt-St micaschists and paragneisses indicating a prograde path in the amphibolite facies associated with the formation of a N-W steeply dipping S2 foliation. This foliation is pervasively reworked by a N-E trending sub-vertical S3 fabric made of Ms-Bt metasediments. This S3 fabric is also found in metapelitic septa in the core of the mafic intrusion, whereas in the narrow contact aureole a moderately dipping S4 fabric roughly parallel to the margins of the pluton is developed. From host-rock to the center of the intrusion, the metapelites show destabilization of muscovite, appearance of sillimanite, spinel, cordierite, crystallization of a large amount of garnet and finally disappearance of biotite and potassic feldspar. As a consequence, the kinzigitic restites of the contact aureole are replaced by Grt-Sil-Crd-Spl granulites in an intra-plutonic position. Qualitative P-T estimates indicate a barrovian prograde path during D2, similar to P-T evolutions found in other Austroalpine units (e.g. Ulten zone). Thermodynamic modelling of the high-grade granulites due to the thermal effect of the ~290 Ma (U-Pb on zircon) mafic intrusion give conditions of ~6 kbar and > 900°C. Our results bring constrains on the thermal and mechanical relation between the pluton and the host rock in the middle crust and confirm the mid-crustal position of the Campo unit during the Permian. Furthermore, this study highlights the contrasted evolution of mid-crustal levels compared to lower-crustal systems such as the Ivrea zone. Eventually at a larger scale, these results provide insights on the tectonic and magmatic processes and thermal conditions of the continental crust during Variscan post-orogenic evolution.

Petri, Benoît; Mohn, Geoffroy; Štípská, Pavla; Manatschal, Gianreto; Schulmann, Karel

2014-05-01

254

Ocean redox change at the Permian-Triassic mass extinction  

DEFF Research Database (Denmark)

Earth’s history is marked by multiple events of ocean anoxia developing along continental margins and po¬tentially into the open ocean realm. These events of¬ten coincide with the emplacement of large igneous provinces (LIPs) on continents, major perturbations of global geochemical cycles and marine (mass) ex¬tinction. The geographic and temporal extend and the intensity (ferruginous vs. euxinic) of anoxic con¬ditions is, however, strongly debated and not well constraint. This complicates understanding of close coupling between Earth’s physical, chemical and bi¬ological processes. We studied ocean redox change over the largest mass extinction event in Earth history, at the Permian-Tri¬assic boundary (at ~252 Ma). This event is marked by a major perturbation in the global exogenic carbon cycle (and associated major negative carbon isotope excursion (CIE)), likely initiated by carbon outgassing from the Siberian Traps. We measured redox-sensitive trace element concentrations (e.g. Mo, Cu, U) and the speciation of iron [Fe-HR/Fe-T and Fe-PY/ Fe- HR] in marine sediments from Svalbard (Festningen). We compare these data to additional, new, high-lati-tude data from eastern Greenland and the equatorial Tethys realm in Iran. We show that the Permian-Tri¬assic boundary at Svalbard is marked by 2 phases of euxinic (sulfidic) ocean conditions. An initial short phase at the onset of atmospheric carbon release is separated from a subsequent longer phase by a re¬turn to ferruginous ocean conditions (anoxic but not euxinic) coinciding with the main extinction event. Molybdenum enrichments, often indicative for freely available sulfide in the water-column, only occur dur¬ing the second phase of euxinia. This pattern of ocean redox-change in Svalbard direct¬ly reflects similar trends in Greenland and Iran. It sug¬gests a strongly decreased global ocean molybdenum (and possibly also ocean sulfate) inventory by massive molybdenum drawdown (and possibly pyrite buri¬al) at the onset of end-Permian atmospheric carbon release and leading up to the Permian-Triassic mass extinction. We compare these oceanographic changes to similar observations for the Triassic-Jurassic mass extinction and discuss environmental forcing, poten¬tially inherent to major volcanic events and leading to global environmental change and extinction

Ruhl, Micha; Bjerrum, Christian J.

2013-01-01

255

Plant biodiversity in the Mahanadi Basin, India, during the Gondwana period  

Science.gov (United States)

The Mahanadi Basin is one of five major sedimentary basins of Peninsular India and is situated on the east coast. The sediments are exposed in two different regions: an extensive basin comprising Lower to Upper Gondwana with coal measures towards the west (Talchir and lb-River Sub-basins); and the Athgarh Sub-basin in the east with rocks of only Upper Gondwana age. This study is mainly concerned with plant species diversification and the development of flora in the Mahanadi Basin from the Early Permian to the Early Cretaceous. A number of successive megafloras are recognised with gaps in the sequence. A few animal records are also considered in order to examine biodiversity in the basin. Leaves are the dominant part of the preserved flora, followed by fruits. No stem or wood parts are preserved and the root parts are represented by the form genus Vertebraria. Pre-angiosperm fossil floras at species level are plotted systematically in Table 2 to examine the plant diversity through different geological formations in the Mahanadi Basin. Maximum plant diversification in gymnosperms is recorded in the Late Permian (Kamthi Formation), and in pteridophytes in the Early Cretaceous (Athgarh Formation).

Singh, K. J.

2000-07-01

256

Mixing mechanisms in siliciclastic-carbonate successions of Khan Formation (Permian), Central Iran  

Science.gov (United States)

Mixing mechanisms in siliciclastic-carbonate successions of Khan Formation (Permian), Central Iran M. Shadan & M. Hosseini-Barzi Geology Department, Faculty of Earth Science, Shahid Beheshti University, Tehran, Iran shadangeo@gmail.com Mixing mechanisms in siliciclastic-carbonate successions of Khan Formation (Permian) have been studied in two sections (Chahroof with 197 m thick in north and Cheshmeh Bakhshi with 204 m thick in south) along basement Kalmard fault in Posht-e-Badam block, Central Iran. Siliciclastic units are characterized by well sorted, fine to medium grain quartzarenites with laterite interbeds, deposited in shoreline zone (foreshore, upper and lower shoreface) influencing wave and longshore currents. Longshore sands which have been transported along the coast made the sand bars in the shoreface. Further along the coast, returning of these currents as rip currents produced erosive channel inlets and caused to carry fine grain into the deeper regions of the basin. Based on this sedimentary model we introduced longshore currents as a probable agent for mixing, by transporting some volumes of sands into the adjacent carbonate environments. Vertically, clastic units of Khan Formation underlined by carbonate units of a tidal flat and high-energy inner ramp system. Repeating of this pattern produced 3 cycles in each section. Cyclic evolution, in studied sections, is accompanied with discrepancy in erosion and sedimentation. These factors caused to disperse local sub-aerial exposures in successions which are recognizable by laterite and conglomerate interbeds. These horizons of sub-aerial exposures are more often in Chahroof section than in Cheshmeh Bakhshi section and indicate more fluctuations of relative sea level probably due to more local tectonic activity in the northern part of the Kalmard fault than in the southern part of it. Also, thicker siliciclastic units in Chahroof section show higher rate of sediment supply and/or more accommodation space there. Moreover, the late Paleozoic glacial conditions in Gondwana lands supported the large volume of clastic supply into the basin by intense weathering and erosion of vast exposed regions in Posht-e-Badam block. Also, tectonic activity along Kalmard basement fault mainly controlled local sea level changes and lithology of outcrops in the hinterlands. Therefore, interplay of these factors during lowstand of relative sea level, with lower accommodation space and higher gradient led to high rate of sediment input and distribution of siliciclastics in the base of each cycles. In contrast, relative sea level rises have been corresponded to the more accommodation space and reducing of siliciclastic entrance into the sedimentary basin that made a suitable condition for carbonate production. Therefore, during relative sea level rise, verities of carbonate-producing organisms tend to more rates of biogenic carbonate products and eventually formation of carbonate units upon the preexistence silisiclastics. Therefore, mixing of siliciclastics with carbonate deposits in Khan Formation have mainly been controlled temporally by sea level fluctuations due to local and/or eustatic sea level changes and spatially by variations in local tectonic activities and lateral facies mixing by longshore currents.

Shadan, Mahdi; Hosseini-Barzi, Mahboubeh

2010-05-01

257

Permian dust in Oklahoma: Source and origin for Middle Permian (Flowerpot-Blaine) redbeds in Western Tropical Pangaea  

Science.gov (United States)

Analogous to many Permian units globally, the Middle Permian of Oklahoma (Flowerpot Shale and Blaine Formation) contains voluminous fine-grained redbeds. These units have long been interpreted to record marine to marginal-marine deposition owing to minor evaporite/dolomite strata; this interpretation, however, disregards the predominant siliciclastic material. Siltstone predominates, and all siliciclastic material is of inferred aeolian origin owing to the fine and remarkably uniform grain size, internally massive structure, blanket-like geometry, and common palaeosols, especially in the Flowerpot Shale. Previously suggested alternative environments for such abundant fine-grained material, such as distal deltaic deposition, are inconsistent with the absence of key sedimentary structures (e.g., graded beds), associated facies (e.g., channelised units), and vertical or lateral trends (e.g., upward coarsening). The minor claystone and associated evaporite and dolomite facies of the Blaine Formation exhibit evidence for subaqueous deposition, but with aeolian delivery of the siliciclastic component. An aeolian dust origin for the siliciclastic material reinforces the interpretation of generally semiarid conditions for this equatorial region of western Pangaea. Whole-rock geochemical and detrital-zircon geochronological data on the siliciclastic units indicate a mixed provenance that includes a mafic component exhibiting a composition similar to reference populations from the Ouachita orogen. The dominant zircon populations reflect transport from easterly/southeasterly directions, with fewer grains likely derived from basement located to the west. Combining an aeolian delivery with the provenance signal indicates predominant equatorial easterlies during deposition of the study units, and subordinate westerlies, consistent with Pangaean monsoonal circulation. Permian redbeds preserved in many parts of former low-latitude Pangaea bear attributes similar to those of the units documented here, suggesting a possible greater role for dust deposition during this time than previously appreciated.

Sweet, Alisan C.; Soreghan, Gerilyn S.; Sweet, Dustin E.; Soreghan, Michael J.; Madden, Andrew S.

2013-02-01

258

Polyphase tectonic events and Cenozoic basin-range coupling in the Tianshan Belt, Northwestern China  

Energy Technology Data Exchange (ETDEWEB)

Studies show that the Tianshan orogenic belt was built in the late stage of the Palaeozoic, as evidenced by the Permian red molasses and foreland basins; which are distributed in parallel with the Tianshan belt, indicating that an intense folding and uplifting event took place. During the Triassic, this orogenic belt was strongly eroded, and basins were further developed. The folding and faulting of Mesozoic sedimentary rocks, spontaneous combustion of Jurassic coal layers and formation of sintered rocks, the Cenozoic earthquakes and active faulting, and the unique mosaic pattern of basin-range framework of Xinjiang are all products of tectonism since the Neogene.

Shu, L.S.; Wang, B.; Yang, F.; Lu, H.F.; Charvet, J.; Laurent-Charvet, S. [Nanjing University, Nanjing (China). Dept. of Earth Science

2003-12-01

259

Panjal Paleomagnetism: Implications for Early Permian Gondwana break-up  

Science.gov (United States)

The mid-Early Permian represents an important phase in Pangaea's development marking the time when the >13,000 km-long string of terranes that are collectively known as 'Cimmeria' separated from Gondwana's Tethyan margin (northern Africa-NE Arabia-northern India-NW and northern Australia). The ~289 Ma Panjal Traps of NW India (Kashmir) are one of a number of mafic suites (Abor, Sikkim etc.) that were erupted onto the Indian block possibly during the separation of the Lhasa/SE Qiangtang block. Herein, we report data from the first modern paleomagnetic study of the unit. Results from four quarry sections (15 individual cooling units) from a locality close to Srinagar together form a tectonically coherent sequence spanning 2-3 km of stratigraphy. The derived direction and paleopole yield key new information concerning (1) the Early Permian location of India, and by inference that of central Gondwana, and (2) inform debates related to Cimmeria's breakup from eastern Gondwana. Moreover, they provide a new independent control for assessing NW Greater India's extent prior to its collision with Asia and the amount of vertical-axis rotation this sector of the Himalayan range experienced in the mid to late Cenozoic.

Stojanovic, D.; Aitchison, J.; Ali, J. R.; Ahmad, T.; Ahmad Dar, R.; Agarwal, A.; Roeder, T.

2013-12-01

260

Evolution of a complex behavior: the origin and initial diversification of foliar galling by Permian insects.  

Science.gov (United States)

A central notion of the early evolution of insect galling is that this unique behavior was uncommon to rare before the diversification of angiosperms 135 to 125 m.yr. ago. However, evidence accumulated during recent years shows that foliar galls were diverse and locally abundant as early as the Permian Period, 299 to 252 m.yr. ago. In particular, a diversity of leaf galling during the Early Permian has recently been documented by the plant-damage record of foliar galls and, now, our interpretation of the body-fossil record of culprit insect gallers. Small size is a prerequisite for gallers. Wing-length measurements of Permian insects indicate that several small-bodied hemipteroid lineages originated early during the Permian, some descendant lineages of which gall the leaves of seed plants to the present day. The earliest foliar gallers likely were Protopsyllidiidae (Hemiptera) and Lophioneuridae (Thripida). Much of the Early Permian was a xeric interval, and modern galls are most common in dry, extra-tropical habitats such as scrubland and deserts. Plant-damage, insect body fossils, and the paleoclimate record collectively support the ecological expansion of foliar galling during the Early Permian and its continued expansion through the Late Permian. PMID:25783809

Schachat, Sandra R; Labandeira, Conrad C

2015-04-01

261

Evolution of a complex behavior: the origin and initial diversification of foliar galling by Permian insects  

Science.gov (United States)

A central notion of the early evolution of insect galling is that this unique behavior was uncommon to rare before the diversification of angiosperms 135 to 125 m.yr. ago. However, evidence accumulated during recent years shows that foliar galls were diverse and locally abundant as early as the Permian Period, 299 to 252 m.yr. ago. In particular, a diversity of leaf galling during the Early Permian has recently been documented by the plant-damage record of foliar galls and, now, our interpretation of the body-fossil record of culprit insect gallers. Small size is a prerequisite for gallers. Wing-length measurements of Permian insects indicate that several small-bodied hemipteroid lineages originated early during the Permian, some descendant lineages of which gall the leaves of seed plants to the present day. The earliest foliar gallers likely were Protopsyllidiidae (Hemiptera) and Lophioneuridae (Thripida). Much of the Early Permian was a xeric interval, and modern galls are most common in dry, extra-tropical habitats such as scrubland and deserts. Plant-damage, insect body fossils, and the paleoclimate record collectively support the ecological expansion of foliar galling during the Early Permian and its continued expansion through the Late Permian.

Schachat, Sandra R.; Labandeira, Conrad C.

2015-04-01

262

The Permian volcanism of Sardinia revisited: new geochronological and geochemical data as a key for geodynamic evolution of the western Peri-Tethian sector  

Science.gov (United States)

Recent studies have confirmed the important role played by magmatism affecting Sardinian basins during the latest Carboniferous and Permian age (Cortesogno et al. 1998; Buzzi et al., 2008; Casini et al., 2012). To-date, most of the geochronological analysis performed on the Permian volcanic events in the island are methodologically overcome and frequently not in tune with the stratigraphy. In the north-western and central-southeastern Sardinian basins (Nurra, Perdasdefogu, Seui-Seulo and Escalaplano), the late-post Variscan tectonic collapse favored the emplacement of a calc-alkaline products not only in the form of generally shallow intrusions but also volcanism within intramontane strike-slip basins. This magmatism is expressed both as pyroclastic rocks-lava flows filling small half-graben basins and hypabyssal intrusions (lava-domes and dykes). These volcano-sedimentary troughs generally include both external and internal igneous eruptions as well as the detrital products eroded from the surrounding structural highs. Rhyolites, andesites and dacites are the main rock types while trachydacites and trachyandesites are less represented. Our goal is to couple the petrographic and geochemical features of 17 selected samples stratigraphically constrained and new U-Pb ages data on zircons from the post-Variscan effusive rocks in Sardinia. The whole-rock and REE geochemical features confirm a progressive evolution in the post-Variscan extensional, trans-tensile regime in with and fits an origin in a stacking of nappes associated with thermal re-equilibration of lithospheric mantle and telescopic partial melting of the thickened crust. The process is dominated by AFC. As far as the geochronological analysis is concerned, a preliminary cathodoluminescence study has been performed on all mounted crystals in order to select the precise location of the shot points. Each crystal has been analyzed for U, Th and Pb in the epoxy mount by laser-ablation inductively coupled plasma mass spectrometry (LA ICP-MS) at the Institute of Geosciences and Earth Resources IGG-CNR of Pavia. The time lag of Permian ages recorded along the Sardinia cross section is significant in the modeling of the post- Variscan tectonic, sedimentary evolution and in the perspective of the geodynamic evolution of Southern Variscides. REFERENCES Casini L., Cuccuru S., Maino M., Oggiano G., Tiepolo M 2012. Emplacement of the Arzachena Pluton (Corsica-Sardinia Batholith) and the geodynamics of incoming Pangaea. Tectonophysics 544-545 (2012) 31-49. Buzzi L., Gaggero L., Oggiano G. 2008. The Santa Giusta ignimbrite (NW Sardinia): a clue for the magmatic, structural and sedimentary evolution of a Variscan segment between Early Permian and Triassic. Italian Journal of Geoscience 127(3), 683-695. Cortesogno L., Cassinis G., Dallagiovanna G., Gaggero L., Oggiano G., Ronchi A., Seno S., Vanossi M. 1998. The Variscan post-collisional volcanism in Late Carboniferous-Permian sequences of Ligurian Alps, Southern Alps and Sardinia (Italy): a synthesis. Lithos 45, 305-328.

Gaggero, Laura; Gretter, Nicola; Lago, Marceliano; Langone, Antonio; Oggiano, Giacomo; Ronchi, Ausonio

2014-05-01

263

The Karoo Basin of South Africa: type basin for the coal-bearing deposits of southern Africa  

Energy Technology Data Exchange (ETDEWEB)

The coal-bearing sediments and coal seams of the Karoo Basin, Southern Africa are described. The Karoo Basin is bounded on its southern margin by the Cape Fold Belt, onlaps onto the Kaapvaal Craton in the north and is classified as a foreland basin. Coal seams are present within the Early Permian Vryheid Formation and the Triassic Molteno Formation. The peats of the Vryheid Formation accumulated within swamps in a cool temperate climatic regime. Lower and upper delta plain, back-barrier and fluvial environments were associated with peat formation. Thick, laterally extensive coal seams have preferentially accumulated in fluvial environments. The coals are in general inertinite-rich and high in ash. However, increasing vitrinite and decreasing ash contents within seams occur from west to east across the coalfields. The Triassic Molteno coal seams accumulated within aerially restricted swamps in fluvial environments. These Molteno coals are thin, laterally impersistent, vitrinite-rich and shaly, and formed under a warm temperate climatic regime. Palaeoclimate, depositional systems, differential subsidence and basin tectonics influence to varying degrees, the maceral content, thickness and lateral extent of coal seams. However, the geographic position of peat-forming swamps within a foreland basin, coupled with basin tectonics and differential subsidence are envisaged as the primary controls on coal parameters. The Permian coals are situated in proximal positions on the passive margin of the foreland basin. Here, subsidence was limited which enhanced oxidation of organic matter and hence the formation of inertinitic coals. The coals in this tectonic setting are thick and laterally extensive. The Triassic coals are situated within the tectonically active foreland basin margin. Rapid subsidence and sedimentation rates occurred during peat formation which resulted in the preservation of thin, laterally impersistent, high ash, vitrinite-rich, shaly coals. 82 refs., 14 figs.

Cadle, A.B.; Cairncross, B.; Christe, A.D.M.; Roberts, D.L. (Witwatersrand University, Wits (South Africa). Geology Department)

1993-09-01

264

Deep-seated salt dissolution in the Delaware basin, Texas and New Mexico  

International Nuclear Information System (INIS)

Patterns of salt dissolution in the Delaware Basin are related to the bedrock geometry and hydrology that developed following uplift, tilting, and erosion in the late Cenozoic, and the greatest volume of salt has been removed since that time. During the Permian, some salt was dissolved from the top of the Castile Formation before deposition of the Salado Formation and from the top of the Salado before deposition of the Rustler Formation. In addition, some salt dissolution occurred after the Permian and before the Cretaceous. Post-uplift surface dissolution has progressed across the Delaware Basin from south to north and west to east and generally down the regional dip. Deep-seated dissolution has occurred around the margin of the basin where the Capitan Limestone aquifer is in contact with the Permian evaporites and within the basin where selective dissolution in the lower Salado has undercut the overlying salt beds of the middle and upper Salado. Dissolution has not advanced down regional dip uniformly but has left outliers of salt and has progressed selectively into structurally predisposed areas. This selective advance has significance for the stability of the U.S. Department of Energy's Waste Isolation Pilot Plant (WIPP) site

265

Geochemical evidence from Lower Permian volcanic rocks of northeast New South Wales for asthenospheric upwelling following slab breakoff  

International Nuclear Information System (INIS)

The ca 280 Ma Alum Mountain Volcanics and Werrie Basalt were erupted in northeast New South Wales, Australia, during Early Permian lithospheric extension that separated discrete episodes of subduction of Carboniferous and Late Permian - Triassic age. The Alum Mountain rocks, which are preserved in two major synclines in the southeast Tamworth Belt, are mostly basalt, but andesite and rhyolite are also present. The Werrie Basalt found further north in the Tamworth Belt and in the floor of the Gunnedah Basin is composed mainly of basalt, but includes more evolved rocks in the vicinity of several eruptive centres. The Alum Mountain rocks have REE abundances similar to N-MORB, with flat REE patterns, (La/Sm)N ratios ranging from 0.54 to 1.07, and (La/Yb)N ratios from 0.94 to 2.78, suggesting an origin by large degrees of partial melting of asthenosphere at a depth Nd values, ranging from +2.05 to +6.00, suggesting an asthenospheric origin for these rocks. Spider diagrams show a clear negative Nb anomaly, typical of subduction zones, but LREE/HREE [(La/Sm)N = 1.61 to 2.20; (La/Yb)N = 5.07 to 8.81], Ti/Zr, and Ti/P ratios are close to OIB values. The enriched character of the Werrie Basalt has resulted from either asthenospheric melts being progressively modified during ass being progressively modified during ascent of fractionating magmas through the lithosphere, or by partial melting of a mantle metasomatised by subduction. The presence of a significant depleted-mantle component in the signature of the Lower Permian volcanic rocks indicates rise of the local mantle geotherm to allow extensive melting. We therefore propose a model of asthenospheric upwelling and lateral flow following breakoff of the Carboniferous subducting slab. Our model of asthenospheric convection as derived from eastern Australia suggests a major role for the asthenosphere in subduction zones: not only is the asthenosphere the reservoir from which magmatic arc melts originate, but we surmise that the behaviour of asthenospheric mantle at subduction zones may have far-reaching implications for the overall thermal state of the planet. Copyright (2001) Geological Society of Australia

266

Basaltic activity preserved in an Upper Permian radiolarian chert from the Paleo-Tethys in the Inthanon Zone, northern Thailand  

Science.gov (United States)

Basaltic sandstone composed mainly of clay- to sand-sized fragments of glass and basaltic rock has been discovered in a pelagic chert sequence in northern Thailand. The sandstone conformably underlies and is partly intercalated with the Upper Permian (Wuchiapingian-early Changhsingian) radiolarian-bearing chert. Geological age dating based on radiolarians, petrographic examination of the bedded chert with the basaltic sandstone, and geochemical studies were conducted to investigate the origin and sedimentary mode of the lithologic sequence. The bedded chert overlying the basaltic sandstone yielded Late Permian radiolarians and was correlatable with the Wuchiapingian Follicucullus charveti-Albaillella yamakitai assemblage zone as well as the early Changhsingian Neoalbaillella ornithoformis assemblage zone. Lithofacies and microfacies of the bedded chert indicated deposition in a pelagic realm of the Paleo-Tethys. Although the tectonic setting was difficult to estimate based on geochemical features because of element mobility and alteration, the basaltic fragments likely originated as oceanic basalt such as oceanic island basalt. Microfacies and sedimentary structures of the chert and sandstone indicated that the studied sequence is composed of intermittent high sedimentation rates, mainly gravity currents of basaltic fragments, in a background setting of very slowly accumulating radiolarian chert. The sedimentary mode of the sequence, the rare terrigenous influx, and the presence of fusulinoidean or other foraminiferal tests indicate that the basaltic rocks fragment were originally sourced from an oceanic topographic high such as a seamount or an oceanic plateau, and that the volcanic activity occurred in the chert-accumulated oceanic basin of the Paleo-Tethys in the Wuchiapingian.

Kamata, Yoshihito; Maezawa, Ayako; Hara, Hidetoshi; Ueno, Katsumi; Hisada, Ken-ichiro; Sardsud, Apsorn; Charoentitirat, Thasinee; Charusiri, Punya

2012-11-01

267

Characterization of an upper Permian tight gas reservoir. A multidisciplinary, multiscale analysis from the rotliegend, northern Germany  

Energy Technology Data Exchange (ETDEWEB)

Outstanding Ph.D. thesis nominated for a Springer Theses Prize by the RWTH Aachen University, Germany. Uses various approaches and covers a broad range of disciplines. Integrated study, carried out on multiple scales with state of the art technical equipment, that only few laboratories can offer worldwide. ''The thesis of Philipp Antrett is focused on reservoir properties, petrography, lithofacies and sedimentology, core analysis and nanoporosity studies. It will be of major interest for colleagues involved in the exploration and production of tight gas reservoirs in Northern Europe and elsewhere.'' - Francois Roure, August 2012 This thesis describes a multidisciplinary, multiscale approach to the analysis of tight gas reservoirs. It focused initially on the facies architecture of a Permian tight gas field in the Southern Permian Basin (SPB), East Frisia, northern Germany. To improve field development, 3D seismic data, wireline and core data were compared to a reservoir analogue in the Panamint Valley, California, United States. In addition to the large scale approach, a work flow that investigates microporosity by combining Scanning Electron Microscopy-Broad Ion Beam (SEM-BIB) and optical microscopy was developed. For a better understanding of the depositional environment and reservoir rock distribution in the SPB, a sedimentary facies analysis of four cores from the tight gas field in East Frisia was compared to a second study area in northern central Germany. This study demonstrates that tight gas exploration and production requires multidisciplinary, multiscale approaches beyond standard seismic interpretation work flows to better understand the temporal and spatial evolution of these complex reservoirs.

Antrett, Philipp [RWTH Aachen Univ. (Germany). Energy and Mineral Resources Group

2013-06-01

268

The salt that wasn't there: Mudflat facies equivalents to halite of the Permian Rustler Formation, southeastern New Mexico  

International Nuclear Information System (INIS)

Four halite beds of the Permian Restler Formation in southeastern New Mexico thin dramatically over horst lateral distances to correlative classic (mudstone) beds. The mudstones have long been considered residues after post-burial dissolution (subrosion) of halite, assumed to have been deposited continuously across the area. Hydraulic properties of the Culebra Dolomite Member have often been related to Rustler subrosion. In cores and three shafts at the Waste Isolation Pilot Plant (WIPP), however, these mudstones display flat bedding, graded bedding, cross-bedding, erosional contacts, and channels filled with intraformational conglomerates. Cutans indicate early stages of soil development during subaerial exposure. Smeared intraclasts developed locally as halite was removed syndepositionally during subaerial exposure. The authors interpret these beds as facies formed in salt-pan or hypersaline-lagoon, transitional, and mudflat environments. Halite is distributed approximately as it was deposited. Breccia in limited areas along one halite margin indicates post-burial dissolution, and these breccials are key to identifying areas of subrosion. A depositional model accounts for observed sedimentary features of Restler mudstones. Marked facies and thickness changes are consistent with influence by subsidence boundaries, as found in some modern continental evaporites. A subrosion model accounts for limited brecciated zones along (depositional)halite margins, but bedding obspositional)halite margins, but bedding observed in the mudstones would not survive 90% reduction in rock volume. Depositional margins for these halite beds will be useful in reconstructing detailed subsidence history of the Late Permian in the northern Delaware Basin, It also no longer is tenable to attribute large variations in Culebra transmissivity to Rustler subrosion

269

A modern vs. Permian black shale - the hydrography, primary productivity, and water-column chemistry of deposition  

Science.gov (United States)

The sediment currently accumulating in the Cariaco Basin, on the continental shelf of Venezuela, has an elevated organic-carbon content of approximately 5%; is accumulating under O2-depleted bottom-water conditions (SO42- reduction); is composed dominantly of foraminiferal calcite, diatomaceous silica, clay, and silt; and is dark greenish gray in color. Upon lithification, it will become a black shale. Recent studies have established the hydrography of the basin and the level of primary productivity and bottom-water redox conditions. These properties are used to model accumulation rates of Cd, Cr, Cu, Mo, Ni, V, and Zn on the seafloor. The model rates agree closely with measured rates for the uppermost surface sediment.The model is applied to the Meade Peak Phosphatic Shale Member of the Phosphoria Formation, a phosphate deposit of Permian age in the northwest United States. It too has all of the requisite properties of a black shale. Although the deposit is a world-class phosphorite, it is composed mostly of phosphatic mudstone and siltstone, chert, limestone, and dolomite. It has organic-carbon concentrations of up to 15%, is strongly enriched in several trace elements above a terrigenous contribution and is black. The trace-element accumulation defines a mean primary productivity in the photic zone of the Phosphoria Basin as moderate, at 500 g m-2 year-1 organic carbon, comparable to primary productivity in the Cariaco Basin. The source of nutrient-enriched water that was imported into the Phosphoria Basin, upwelled into the photic zone, and supported primary productivity was an O2 minimum zone of the open ocean. The depth range over which the water was imported would have been between approximately 100 and 600 m. The mean residence time of bottom water in the basin was approximately 4 years vs. 100 years in the Cariaco Basin. The bottom water was O2 depleted, but it was denitrifying, or NO3- reducing, rather than SO42- reducing. Published by Elsevier B.V.

Piper, D.Z.; Perkins, R.B.

2004-01-01

270

Evolution of the Northeast German Basin — inferences from a 3D structural model and subsidence analysis  

Science.gov (United States)

A 3D structural model of the Northeast German Basin was evaluated with special emphasis on its evolution as an intracontinental depression. The study includes investigations on subsidence history and structural setting of the basin. Thickness evolution and calculated tectonic subsidence volumes of Permian to Quaternary sediments in the Northeast German Basin indicate that the subsidence history was related to five stages of basin evolution which differ in their subsidence mechanisms. For the initial rift phase in the Late Carboniferous to Early Permian, a dominant thermal event and subordinate horizontal stresses were indicated by thickness variation evolution and by structural evidence. The main part of basin subsidence occurred in a NW-SE-oriented basin in the subsequent phase of thermal relaxation with maximum subsidence from Early Permian (Rotliegend) to Middle Triassic (Muschelkalk). From Middle Triassic the thermal subsidence pattern was superposed by further tectonic events. In the Middle Triassic regional extension led to a reconfiguration of the southern part of the basin, where new NNE-SSW-trending troughs (Rheinsberg and Gifhorn Troughs) developed. In the Jurassic the northwestern part of the basin was uplifted while in the south the Keuper subsiding areas continued to sink and NW-SE-trending depressions, related to salt margins, became important. Differentiation continued into Cretaceous times when regional compression caused uplift of the southeastern part of the basin and basin margins. A final subsidence phase occurred in the Cenozoic. This was accompanied by intensive salt movement. Recent basin configuration reflects the superposition of structural elements resulting from different evolution stages. The main structural characteristics of the basin are: (1) a vertical tectonic zonation in a pre-Zechstein succession, which lacks significant internal structures, and a strongly deformed post-Zechstein succession, which was decoupled due to the thick Zechstein salt; and (2) a marked asymmetry of the basin with a shallow northern slope and a steep bounding fault at the southern margin (Elbe Fault System). The northwestern part of the basin shows the structural properties of an intracratonic sag basin with persisting subsidence and with minor salt mobilisation. In contrast, initial structures in the southeastern part are strongly overprinted by younger tectonic events including Middle Triassic to Jurassic extension, Late Cretaceous inversion and Late- to post-Cretaceous salt movements. Tectonic elements that deform the whole sedimentary succession are restricted to the basin's southern, eastern and northeastern margins where salt thickness decreases. Combined volumetric and backstripping investigations show that 2/3 of the total subsidence was induced by the sediment load and 1/3 was caused by tectonics. The tectonic subsidence history varies laterally across the basin. While tectonic subsidence curves in the northwestern part of the basin show fast subsidence during the Permian, and Early Triassic decreasing exponentially with time, subsidence curves in the southeastern part indicate repeated tectonic activity. However, the tectonic subsidence volume created during Permian to Late Triassic is significantly higher than the tectonic subsidence during younger phases of basin history.

Scheck, M.; Bayer, U.

1999-11-01

271

Longitudinal fluvial drainage patterns within a foreland basin-fill: Permo-Triassic Sydney Basin, Australia  

Science.gov (United States)

The north-south trending Permo-Triassic Sydney Basin (southern sector of the Sydney-Bowen Basin) is unique compared to many documented retro-arc foreland basins, in that considerable basin-fill was derived from a cratonic source as well as a coeval fold belt source. Quantitative analysis of up-sequence changes in sandstone petrography and palaeoflow directions, together with time-rock stratigraphy of the fluvial basin-fill, indicate two spatially and temporally separated depositional episodes of longitudinal fluvial dispersal systems. A longitudinal drainage-net similar in geometry to the modern Ganga River system (reduced to 60% original size) explains many of the palaeoflow patterns and cross-basinal petrofacies variation recorded in the basin-fill. The Late Permian to Early Triassic rocks reveal a basin-wide southerly directed fluvial drainage system, contemporaneous with east-west shortening recorded in the New England Fold Belt. In contrast, the Middle Triassic strata reveal a change to an easterly directed fluvial system, correlated to a shift in orogenic load to a NW-SE orientation in the fold belt northeast of the basin. The detailed petrofacies variation in the deposits of the second longitudinal fluvial dispersal system reveals vertical jumps in petrofacies compositions, with uniform compositions between jumps. The petrological jumps are interpreted as the result of minor fault adjustments in the fold belt, resulting in changing rates of sediment supply to the foreland basin. Uninterrupted erosion of the same terrain most likely caused the compositional uniformity between jumps. The identification of similar longitudinal fluvial systems, with transverse variation in detrital composition, is likely to help resolve the tectonic history of foreland fold belts elsewhere.

Cowan, E. Jun

1993-05-01

272

Volcanic sediments - new reservoir fairways in back-arc basins, eastern Australia  

Energy Technology Data Exchange (ETDEWEB)

Volcanic rocks and associated lithic sandstones, hitherto thought to be too tight and impermeable, may well form important new reservoirs in the extensive Permian back-arc basins of eastern Australia. Oil and gas production has already been established in these sediments in the Permian Bowen and Surat basins of Queensland with some new discoveries in tuffaceous rocks. Most of these volcanic rocks were derived from andesitic, dacitic, and rhyolitic island-arc complexes that lay to the east or the open paleo-Pacific side of a back-arc depositional area. The sediment in these back-arc areas is composed mainly of sand, conglomerate, and silt, all with low percentages of quartz and derived from the volcanic arc. These sediments are interbedded with 1-5 m thick subbituminous to bituminous coal seams, which have been mined extensively in open-cut and shallow subsurface areas of the Bowen and Sydney basins. Basin analysis, using coal stratigraphy and deep wells in the Sydney basin, has established several potential reservoir fairways controlled by facies distribution of the cleaner sands. The variation in reservoir properties within many new potential fairways can be illustrated for parts of both the Sydney and Surat basins. A combination of better understanding of the reservoir properties of these volcanic sediments combined with better drilling, completion, and stimulation techniques lends credence to the hope that these back-arc provinces may become important new oil and gas basins.

Conolly, J.R.; Ferm, J.C.

1985-02-01

273

Catagenesis of organic matter of oil source rocks in Upper Paleozoic coal formation of the Bohai Gulf basin (eastern China)  

Energy Technology Data Exchange (ETDEWEB)

The Bohai Gulf basin is the largest petroliferous basin in China. Its Carboniferous-Permian deposits are thick (on the average, ca. 600 m) and occur as deeply as 5000 m. Coal and carbonaceous shale of the Carboniferous Taiyuan Formation formed in inshore plain swamps. Their main hydrocarbon-generating macerals are fluorescent vitrinite, exinite, alginite, etc. Coal and carbonaceous shale of the Permian Shanxi Formation were deposited in delta-alluvial plain. Their main hydrocarbon-generating macerals are vitrinite, exinite, etc. The carbonaceous rocks of these formations are characterized by a high thermal maturity, with the vitrinite reflectance R{sub 0} > 2.0%. The Bohai Gulf basin has been poorly explored so far, but it is highly promising for natural gas.

Li, R.X.; Li, Y.Z.; Gao, Y.W. [Changan University, Xian (China)

2007-05-15

274

Rare-earths in size fractions and sedimentary rocks of Pennsylvanian-Permian age from the mid-continent of the U.S.A  

International Nuclear Information System (INIS)

The REE (rare-earth) contents of sixty-three <2? fractions of Pennsylvanian and Permian platform sediment from the mid-continent of the U.S.A. vary considerably (?REE = 46 to 439 ppm: La/Lu = 5.2 to 15.7; correlation coefficient of REE with La Lu = 0.89), but the Eu/Sm ratios are nearly constant even in reducing environments that concentrate U (0.16 to 0.22). There is no correlation of REE content to clay mineralogy. Lower Permian <2? fractions from continental to nearshore marine sediment in Oklahoma have higher REE content (244 to 261 ppm) than marine facies in Kansas (46 to 140 ppm) but <2? Upper Permian fractions in an evaporite basin have constant but high REE content (288 to 281 ppm; one = 153 ppm). All Pennsylvanian <2? fractions from Oklahoma have high REE content (209 to 439 ppm), and fractions from Kansas cyclothems have variable REE content (86 to 438 ppm). REE content in the <2? fractions is inherited from the provenance, but is modified by ion exchange during weathering, transportation or deposition. Exchangable REE tend to be concentrated in clay minerals in basic environments, but removed in acid environments. Sand and gravel-size fractions consist mostly of quartz or chert so their REE content is low (7.9 to 40.6 ppm) although heavy minerals may contribute a large fraction of the REE content. Unexpectedly silt-size fractions have REE contents (74 to 355 ppm) that are usually lower but similar to their <2? fractions, and the REE contents do not cions, and the REE contents do not correlate to clay mineral/quartz ratios. (author)

275

Extensive, uplift-related and non-fault-controlled spar precipitation in the Permian Capitan Formation  

Science.gov (United States)

With time, unlithified grains in sediments become cemented and eventually lithified to form sedimentary rocks. Sedimentary rocks of all ages, lithologies and depositional settings exhibit cements. The timing of cementation within a given sedimentary unit, however, is generally poorly constrained. The formation conditions of the youngest of cement generations are particularly difficult to characterize. Typically, traditional carbonate carbon (?13Ccarb) and oxygen (?18Ocarb) isotope analyses are used to characterize precipitation timing and environment. However, ambiguities associated with the interpretation of ?18Ocarb data lead to conflicting hypotheses. The Permian Capitan Formation is one of the most widely studied carbonate sequences and contains extensive calcite cements that have been interpreted to form across a range of diagenetic environments through ?18Ocarb analyses. Here, we present new and previously reported clumped isotope data from calcite spars of Capitan fore-reef slope and equivalent shelf facies (Tansill Formation) in order to constrain mineralization temperatures, provide previously unattainable information concerning precipitation environment, and explore the spatial extent of precipitation events. Spar precipitation temperatures range from ~ 30 to 75 °C and show positive correlation with reconstructed pore water ?18O values, indicating rock-buffered behavior. Evaluation of the data using a simple water-rock model indicates that the fluid(s) involved in diagenesis must have had a significant meteoric component, exhibiting fluid ?18O values approaching - 12‰ (VSMOW). These new data along with previously reported outcrop and core relationships indicate that spar precipitation occurred well after deposition of the Capitan Formation and likely during Tertiary uplift when fluids with such light isotopic signatures would have infiltrated the basin, and not during burial as generally assumed. The meteoric fluids responsible for spar precipitation may have been delivered locally through fracture networks, but also penetrated less fractured facies and produced extensive spar cements.

Loyd, S. J.; Dickson, J. A. D.; Scholle, P. A.; Tripati, A. K.

2013-12-01

276

Body size reductions in nonmammalian eutheriodont therapsids (Synapsida) during the end-Permian mass extinction.  

Science.gov (United States)

The extent to which mass extinctions influence body size evolution in major tetrapod clades is inadequately understood. For example, the 'Lilliput effect,' a common feature of mass extinctions, describes a temporary decrease in body sizes of survivor taxa in post-extinction faunas. However, its signature on existing patterns of body size evolution in tetrapods and the persistence of its impacts during post-extinction recoveries are virtually unknown, and rarely compared in both geologic and phylogenetic contexts. Here, I evaluate temporal and phylogenetic distributions of body size in Permo-Triassic therocephalian and cynodont therapsids (eutheriodonts) using a museum collections-based approach and time series model fitting on a regional stratigraphic sequence from the Karoo Basin, South Africa. I further employed rank order correlation tests on global age and clade rank data from an expanded phylogenetic dataset, and performed evolutionary model testing using Brownian (passive diffusion) models. Results support significant size reductions in the immediate aftermath of the end-Permian mass extinction (ca. 252.3 Ma) consistent with some definitions of Lilliput effects. However, this temporal succession reflects a pattern that was underscored largely by Brownian processes and constructive selectivity. Results also support two recent contentions about body size evolution and mass extinctions: 1) active, directional evolution in size traits is rare over macroevolutionary time scales and 2) geologically brief size reductions may be accomplished by the ecological removal of large-bodied species without rapid originations of new small-bodied clades or shifts from long-term evolutionary patterns. PMID:24498335

Huttenlocker, Adam K

2014-01-01

277

Pumping test and fluid sampling report - Sawyer No. 1 well, Palo Duro Basin, Texas: unanalyzed data  

International Nuclear Information System (INIS)

This report describes pumping test and fluid sampling activities performed at the Sawyer No. 1 well, Donley County, Texas. Sawyer No. 1 well is located along the eastern margin of the Palo Duro Basin in an area of active dissolution within the Permian salt section. These data were collected by Stone and Webster Engineering Corporation working in conjunction with the Texas Bureau of Economic Geology as part of a nationwide program to identify potential locations for a nuclear waste repository. These data support studies to determine the hydrologic characteristics of deep water-bearing formations. Formation fluid studies samples were analyzed in order to evaluate fluid migration and age relationships in the Permian Basin. These data were collected from June until October, 1981. Zone isolation for pump testing was accomplished in November, 1981. These data are preliminary. They have been neither analyzed nor evaluated

278

Detrital zircon geochronology in blueschist-facies meta-conglomerates from the Western Alps: implications for the late Carboniferous to early Permian palaeogeography  

Science.gov (United States)

In the Western Alps, the Money Complex of the Gran Paradiso Massif, metamorphosed under blueschist facies during the Alpine cycle, is considered to be Permo-Carboniferous in age, but no palaeontological or radiometric data constrain this interpretation. A revision of the lithostratigraphy of the Money Complex allows recognizing a polygenic (graphite-rich) and a monogenic (graphite-poor) meta-sedimentary formation. Detrital zircon U-Pb geochronology in both meta-sedimentary formations shows that (i) the main population is Cambrian and Ordovician in age, (ii) the youngest grains are Silurian and Lower Devonian, and (iii) Carboniferous zircon grains are lacking. A careful study of the age distributions in the Alps suggests that potential source for the detrital material in the Money Complex is the Briançonnais basement. Late Carboniferous magmatism is widespread in the Helvetic Zone of the Alps. Permian magmatism is dominant in the Briançonnais, the Austroalpine and the Southalpine basements. The lack of Carboniferous zircons in the Money Complex suggests that the detritus was not shed from the Helvetic zone, which was separated from the Money basin by the Zone Houillère basin, where the main drainage pattern was developed from south to north and where the depocenters migrated northwards from the Upper Missisippian to Upper Pennsylvanian. We suggest that the Money Complex may had been located to the east of the main river drainage inside the Zone Houillère basin or alternatively may represent a small basin, located on the east of the Zone Houillère.

Manzotti, Paola; Poujol, Marc; Ballèvre, Michel

2014-11-01

279

U/Pb zircon geochronology and tempo of the end-permian mass extinction  

Science.gov (United States)

The mass extinction at the end of the Permian was the most profound in the history of life. Fundamental to understanding its cause is determining the tempo and duration of the extinction. Uranium/lead zircon data from Late Permian and Early Triassic rocks from south China place the Permian-Triassic boundary at 251.4 +/- 0.3 million years ago. Biostratigraphic controls from strata intercalated with ash beds below the boundary indicate that the Changhsingian pulse of the end-Permian extinction, corresponding to the disappearance of about 85 percent of marine species, lasted less than 1 million years. At Meishan, a negative excursion in delta13C at the boundary had a duration of 165,000 years or less, suggesting a catastrophic addition of light carbon. PMID:9582110

Bowring; Erwin; Jin M W Martin YG; Davidek; Wang

1998-05-15

280

Geochemical changes at the Permian–Triassic transition in Southern Alps and adjacent area: a review  

OpenAIRE

Compilation of the recent literature from the Southern Alps and adjacent area confirms the geochemical variations of unusual amplitudes during the Permian-Triassic boundary interval (PTBI). A great attention has been given to the negative ?13C anomaly within the Tesero Member close to the Permian-Triassic boundary. Very detailed geochemical works have been done on the scientific Gartnerkofel core (Gk-1) and on the Slovenian sections. Major minor and rare earth elements (REE) data are reporte...

Aymon Baud

2005-01-01

281

Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea  

OpenAIRE

The medial Permian (?270–260 Ma: Guadalupian) was a time of important tetrapod faunal changes, in particular reflecting a turnover from pelycosaurian- to therapsid-grade synapsids. Until now, most knowledge on tetrapod distribution during the medial Permian has come from fossils found in the South African Karoo and the Russian Platform, whereas other areas of Pangaea are still poorly known. We present evidence for the presence of a terrestrial carnivorous vertebrate from the Middle Permia...

Cisneros, Juan Carlos; Abdala, Fernando; Atayman-gu?ven, Saniye; Rubidge, Bruce S.; S?engo?r, A. M. Cela?l; Schultz, Cesar L.

2012-01-01

282

The Mont Collon mafic complex (Austroalpine Dent Blanche nappe): permian evolution of the Western European mantle  

OpenAIRE

The early Permian Mont Collon mafic complex (Dent Blanche nappe, Austroalpine nappe system) is one of the best preserved examples of the Permian mafic magmatism in the Western Alps. It is composed of discontinuous exposures and a well-preserved magmatic layering (the Dents de Bertol cliff) crops out in the center part of the complex. It mainly consists of cumulative mafic rocks, which represent 95 vol-% of the mafic complex (ol- and cpx-bearing gabbros and rare anorthositic layers, troctolite...

Monjoie, Philippe; Lapierre, Henriette; Pfeifer, Hans-rudolf

2005-01-01

283

A taphonomic model for the Mesosauride assemblage of the Irati Formation (Paraná Basin, Brazil)  

OpenAIRE

The Irati Formation (Permian, Paraná Basin, Brazil) is made up of a succession of black bituminous and nonbituminous shales and mudstones with interbedded carbonate layers, which record deposition in marine environments. Mesosaur remains are abundant at several sites in this formation, where they occur preserved in centimetre- thick beds and displaying various degrees of skeletal disarticulation. This paper seeks to establish a model to explain the processes that generated the mesosaurian ta...

Soares, M. B.

2003-01-01

284

Oxidoreduction processus in a uranium deposit (Aumance - Cerilly Permian basin, Allier (France))  

International Nuclear Information System (INIS)

Stratigraphic and tectonic data are briefly reviewed. Then a method giving the oxidoreducing properties of elements and using the chemical oxygen demand is exposed. The study of secondary textures shows the effects of the oxidoreducing process. Three pyrite textures were identified at Cerilly by petrographic observations. They are always bound to a secondary enrichment in uranium and they can be used as an exploration guide. Application of factor analysis confirms the studied phenomenon

285

Declining Petroleum Production and the Effect Upon Communities in New Mexico's Permian Basin  

Science.gov (United States)

The petroleum industry, a vital component of New Mexico's economy, is in a gradual decline. As petroleum production is primarily focused in the southeastern corner of the state, this decline phenomenon is particularly relevant to area residents. The problem addressed in this study was that little information is available regarding the lived experiences of business and community leaders concerning this phenomenon, particularly in terms of future economic sustainability. The purpose of this qualitative phenomenological study was to interview a purposive sample of business and community leaders regarding their lived experiences and perceptions relating to the economic sustainability of the region. Research questions asked about the general awareness of the decline of oil production---data collected from federal and state databases---and potential options for alternative economic development. Coded data were analyzed and themes and patterns were identified. Findings included a general lack of awareness of area residents regarding a decline of production, assumed economic stability, and resistance to change based on a lack of incentive. Included in the findings were potential options for strategic economic diversification. Recommendations included a campaign to promote awareness of the decline of oil, provide incentives for change, and economic diversification as method of moving the local economy away from dependence upon the petroleum industry. Implications for positive social change were that the affected region can use the findings to identify sustainable alternative industries to support the communities into the future.

Tipton, Ryan D.

286

Record of the genus Lycopodites in the Lower Permian of Paraná Basin, Brazil  

OpenAIRE

The genus Lycopodites, which encompasses the herbaceous forms of the lycopsids, presents broad time and spacial distribution during the Paleozoic in the Northern Hemisphere, with its initial records dating from the European Devonian. As to Gondwanan Paleozoic, to this moment, only Lycopodites amazonica Dolianiti had been reported for the Amazonian Middle Devonian (Curuá Group). Thus, the specimens reported in this study such as Lycopodites sp., coming from sedimentary rocks of the Itararé S...

Juliana Salvi; André Jasper; Fresia Ricardi-Branco; Bernardes-de-oliveira, Mary Elizabeth C.; Margot Guerra-Sommer

2008-01-01

287

Late Permian global coal hiatus linked to {sup 13}C depleted CO{sub 2} flux into the atmosphere during the final consolidation of Pangea  

Energy Technology Data Exchange (ETDEWEB)

At a time when all continents were finally arrayed in their Pangea supercontinental configuration (250 {+-} 50 Ma), Earth`s stratigraphy records a global and very abrupt coal discontinuity. From the Tartarian stage of the Late Permian to the Middle Triassic, reduced coal productivity and/or preservation overlaps with a period of anomalous oceanic and atmospheric decrease in {sup 13}C, as recorded in marine carbonates and organic matter, and terrestrial plant and animal fossils from the Northern and Southern hemispheres. During the same short period, the peripheral margin of the entire supercontinent Pangea, except for the southern shores of Tethys, was effectively under compressive stress. This unique tectonic state caused deformation and uplift of coal-bearing foreland basins and oxidation of Pangea`s vast peat deposits. The latter resulted in a rapid, massive {sup 13}C-depleted CO{sub 2} flux into the atmosphere, which in turn may have forced global warming.

Faure, K.; Dewit, M.J.; Willis, J.P. [University of Cape Town, Rondesbosch (South Africa). Dept. of Geological sciences

1995-06-01

288

Source rocks of the Sub-Andean basins  

Energy Technology Data Exchange (ETDEWEB)

Seven source rock systems were mapped using a consistent methodology to allow basin comparison from Trinidad to southern Chile. Silurian and Devonian systems, deposited in passive margin and intracratonic settings, have fair-good original oil/gas potential from central and northern Bolivia to southern Peru. Kerogens range from mature in the foreland to overmature in the thrust belt. Permian to Carboniferous deposition in local restricted basins formed organic-rich shales and carbonates with very good original oil/gas potential, principally in northern Bolivia and southern Peru. Late Triassic to early Jurassic marine shales and limestones, deposited in deep, narrow, basins from Ecuador to north-central maturity. Locally, in the Cuyo rift basin of northern Argentina, a Triassic lacustrine unit is a very good, mature oil source. Early Cretaceous to Jurassic marine incursions into the back-arc basins of Chile-Argentina deposited shales and limestones. Although time transgressive (younging to the south), this system is the principal source in southern back-arc basins, with best potential in Neuquen, where three intervals are stacked A late Cretaceous marine transgressive shale is the most important source in northern South America. The unit includes the La Luna and equivalents extending from Trinidad through Venezuela, Colombia, Ecuador, and into northern Peru. Elsewhere in South America upper Cretaceous marine-lacustrine rocks are a possible source in the Altiplano and Northwest basins of Bolivia and Argentina. Middle Miocene to Oligocene source system includes shallow marine, deltaic, and lacustrine sediments from Trinidad to northern Peru.

Raedeke, L.D. (Chevron Overseas Petroleum Inc., San Ramon, CA (United States))

1993-02-01

289

Mongolian coal-bearing basins: Geological settings, coal characteristics, distribution, and resources  

Energy Technology Data Exchange (ETDEWEB)

This paper presents geological settings, stratigraphy, coal quality, petrography, reserves and the tectonic history of the Mongolian coal-bearing basins. This is based on a synthesis of the data from nearly 50 coal deposits. The results of ultimate and proximate analyses, and calorific value, maceral composition and vitrinite reflectance data is given. The coal deposits of Mongolia tend to become younger from west to east and can be subdivided into two provinces, twelve basins, and three areas. Main controlling factor of coal rank is the age of the coal bearing sequences. Western Mongolian coal-bearing province contains mostly high rank bituminous coal in strata from Late Carboniferous. The basins in southern Mongolia and the western part of central Mongolia have low rank bituminous coal in strata from the Permian. The northern and central Mongolian basins contain mainly Jurassic subbituminous coal, whereas the Eastern Mongolian province has Lower Cretaceous lignite. The Carboniferous, Permian and Jurassic coal-bearing sequences were mainly deposited in foreland basins by compressional tectonic event, whereas Cretaceous coal measures were deposited in rift valleys caused by extensional tectonic event. Petrographically, Mongolian coals are classified as humic type. Vitrinite/huminite groups of Carboniferous, Permian, and Cretaceous coal range from 44.9% to 82.9%. Inertinite group varies between 15.0% and 53.3%, but liptinite group does not exceed more than 7%. Jurassic coals are characterized by high percentages of vitrinite (87.3% to 96.6%) and liptinite groups (up to 11.7%). This might be explained by paleoclimatic conditions. Mongolian coal reserves have been estimated to be 10.2 billion tons, of which a predominant portion is lignite in the Eastern Mongolian province and coking coal in the South Gobi basin. (author)

Erdenetsogt, Bat-Orshikh; Lee, Insung [School of Earth and Environmental Sciences, Seoul National University, Seoul 151-747 (Korea); Bat-Erdene, Delegiin; Jargal, Luvsanchultem [Faculty of Geosciences, National University of Mongolia, Ulaanbaatar (Mongolia)

2009-11-01

290

Geochemical evidence from bio-apatite for multiple oceanic anoxic events during Permian-Triassic transition and the link with end-Permian extinction and recovery  

Science.gov (United States)

A detailed, 20 myr redox history of Permian to Triassic oceans (Changhsingian to Carnian stages) has been constructed using Ce-anomaly (?Ce) and Th/U ratios from conodont albid crown apatite material. The results show that the well-established phenomenon of intense ocean anoxia (coincident with the end-Permian mass extinction) is faithfully recorded in conodont ?Ce and Th/U data. Extending this conodont redox record shows that end-Permian anoxia persisted possibly into the earliest Dienerian Stage and that two intense oceanic anoxic events also occurred later in the Early Triassic (earliest Smithian-earliest Spathian, and middle Spathian), followed by a weaker manifestation of anoxia in the Anisian Stage, seen in ?Ce data. Marine benthic radiation, following the end-Permian mass extinction, began after the Smithian-earliest Spathian anoxic event suggesting a suppression of evolution prior to this due to these inimical conditions. The failure of the middle Spathian anoxic event to retard the evolutionary rebound implies shallow shelf seas remained well ventilated at this time even if the oceans did not. Other attributes of the Early Triassic record also closely coincide with redox fluctuations: phases of anoxia intensification saw the proliferation of microbial carbonates and major negative carbon isotope swings that can be attributed to chemocline shallowing causing alkalinity pulses and enrichment in light, remineralised carbon and/or indicate a trigger meachnaims related to increased fluxes of light C from Siberian volcanic sources.

Song, Haijun; Wignall, Paul B.; Tong, Jinnan; Bond, David P. G.; Song, Huyue; Lai, Xulong; Zhang, Kexin; Wang, Hongmei; Chen, Yanlong

2012-11-01

291

U Pb ages and source composition by Hf-isotope and trace-element analysis of detrital zircons in Permian sandstone and modern sand from southwestern Australia and a review of the paleogeographical and denudational history of the Yilgarn Craton  

Science.gov (United States)

Detrital zircons from the Permian Collie Coal Measures and modern sands on the northern part of the Albany Province have been analysed for U-Pb ages by a laser ablation microprobe-inductively coupled plasma mass spectrometer (LAM-ICPMS) and for Hf-isotope compositions by a laser ablation microprobe multi-collector inductively coupled plasma mass spectrometer (LAM-MC-ICPMS). Trace elements were determined by analysis on the electron microprobe (EMP) and the ICPMS's. This combination of techniques makes it possible to determine for each grain not only the age but the nature and source of the host magma, whether crustal or juvenile mantle, and a model age ( TDM) based on a depleted-mantle source, which gives a minimum age for the source material of the magma from which the zircon crystallised. The integrated analysis, applied to suites of detrital zircon, gives a more distinctive, and more easily interpreted, picture of crustal evolution in the provenance area than age data alone. Zircons from Permian and Triassic sediments already analysed for U-Pb ages by a sensitive high-resolution ion microprobe (SHRIMP) were also analysed for Hf isotopes and trace elements. Zircons from Collie and Permian and Early Triassic rocks of the northern Perth Basin have an age spectrum with a peak at about 1200 Ma that can be traced to the Albany Province. Differences, however, in Hf-isotope composition indicate that the Collie Coal Measures and the northern Perth Basin sandstones were not derived from the northern part of the Albany Province or from the coastal strip of felsic granitoids. The Perth Basin samples have a second peak age of 600-500 Ma that can be traced to the Leeuwin Block. One of the modern sands has a major peak at 2616 Ma that can be traced to the Yilgarn Craton. Compiled with previously published U-Pb zircon age spectra, the analyses provide insights into the paleogeographical history. The Yilgarn Craton sloped from the north at 1700 Ma, from the southeast at 1350-1140 and 490 Ma, its eastern part to the east at 300 Ma, and the southern part to the northwest from the Albany Province at 300-255 Ma. Denudational data from apatite fission-track analysis and vitrinite-reflectance studies suggest that the Yilgarn Craton was covered by a ˜5-km-thick blanket of Permian and Mesozoic sedimentary rock that was almost entirely removed by the Cenozoic, possibly because the craton was situated between the shoulders of rift systems that grew into the eastern and southeastern Indian Ocean. Ordovician, Permian, Early Triassic, and Quaternary sediment of the Perth Basin came from Proterozoic orogens. Only the Late Permian sample contains significant populations of Archean (Yilgarn) zircons but whether they came direct from the craton or were recycled from the postulated sedimentary cover is not known. The increased influx of sediment during the Jurassic matched by a peak in the denudation rate would seem to require a primary supply from the craton. This question could be resolved by dating zircon from the rapidly accumulated Jurassic formations.

Veevers, J. J.; Saeed, A.; Belousova, E. A.; Griffin, W. L.

2005-01-01

292

Fullerenes and interplanetary dust at the Permian-Triassic boundary.  

Science.gov (United States)

We recently presented new evidence that an impact occurred approximately 250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a (3)He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for (3)He vs. giant impact for fullerene). PMID:12804366

Poreda, Robert J; Becker, Luann

2003-01-01

293

Late Permian brachiopoda fauna in north-western Iran  

Scientific Electronic Library Online (English)

Full Text Available La secuencia marina del Pérmico superior en el noroeste de Irán y el este de Azerbaiyán, sección estatigráfica de Zal, fue seleccionada para este estudio de braquiópodos. Las muestras fueron tomadas en las formaciones Ali Bashi y Jolfa. Se reconocieron 27 especies de 13 géneros de braquiópodos en es [...] te análisis. Las muestras recolectadas fueron comparadas con sus similares de otras regiones de Irán y de la región del Tetis, lo que sugirió el período de tardío de Dzhulfan como la proveniencia de estos depósitos. Los braquiópodos reconocidos en este trabajo pertenecen a las familias de Athyris, Rhynconellida, Productida y Strophomenida. Abstract in english The Late Permian marine sequence in the north- west of Iran, in eastern Azerbaijan province in the Zal stratigraphic section, was selected for studying brachiopods. Samples were collected from the Ali Bashi and Jolfa Formation.S. Twenty-seven species from 13 brachiopoda genera were recognised in thi [...] s study.The recognised fossil community was compared to brachiopod communities in some regions of Iran and the Tethyan region, suggesting the Late Dzhulfian period as the age for the deposits being studied. Recognized brachiopods belonge to the orders Athyris, Rhynconellida, Productida and Strophomenida.

Yousefirad, Mostafa; Khamooshi, Touran; Shaabanian, Rahim.

2013-06-01

294

Petrographic studies of Permian carbonates in southern Thailand  

Science.gov (United States)

Detailed petrographic studies were conducted on Permian carbonates from four areas: Ratburi, Prachuab Khirikhan, Ko Ang Thong, and Surat Thani-Phang Nga. Six carbonate facies were identified in these areas—mudstone, wackestone, packstone, grainstone, algal boundstone, and intramicrite. The allochems of these carbonates are similar and composed of bioclastic and non-bioclastic grains. The bioclastic grains are blue-green algae (stromatolite), green algae (dasycladacean), tabulate corals, solitary corals, crinoids, foraminiferas ( Shanita sp. and Hemigordius sp.), brachiopods, bryozoan, gastropods and unidentified skeletal fragments. The non-bioclastic grains are ooids, peloids, and intraclasts. Three phases of paragenesis were observed: micritization and neomorphism, dolomitization and non-ferroan/ferroan calcite fractures and veinlets. Micritization, neomorphism, and dolomitization are extensive. Rhombic and mosaic-crystalline dolomites had replaced carbonate mud, sparry calcite cement as well as the allochems. Abundant non-ferroan calcite veinlets cross cut allochems, mud matrix, and dolomite rhombs which suggests they postdate dolomitization. These carbonate facies were interpreted as interior-platform carbonate with a generally well developed shoaling-upward sequence starting from mudstone to wackestone, packstone, and grainstone. Local algal boundstone or algal mound and intramicrite could indicate low energy, regressive cycles.

Chinoroje, Owas

295

Diagenesis of Permian alluvial fan deposits of Northern Switzerland  

International Nuclear Information System (INIS)

Fine-grained sandstones of Permian alluvial fan deposits from three Nagra boreholes (Weiach, Riniken, Kaisten) and an exploration well, drilled at Wintersingen are clast supported, moderately sorted arkosic greywackes containing typically 2-20 % clayey matrix. Petrographic studies indicate that the origin of this clayey matrix is postdepositional. Mechanical infiltration of fines and diagenetic reddening of detrital and authigenic iron oxides are the earliest recorded events. Additionally, nodular calcites of calcrete origin and fibrous illitic clays are also ascribed to the eogenetic environment. The present strong compaction fabric results from general lack of eogenetic framework supporting cements. During mesogenesis, secondary porosity was generated through partial removal of early calcite. At the same time, a first generation of syntaxial quartz cementation and a subsequent fibrous illite authigenesis took place. Leaching of detrital K-feldspars post-dating compaction is recorded throughout the studied boreholes. The following burial diagenetic events differ between the various boreholes: in Weiach and Wintersingen kaolinite, illite, prismatic quartz and ankerite/siderite are recorded; in Riniken K-feldspar, illite, prismatic quartz and dolomite developed; whilst in Kaisten K-feldspar and microcrystalline quartz-cement dominate. These differences reflect the chemistry, pH and ionic strength of the pore fluids. Filling of veins by dolomite/ankerite, iron-rich and veins by dolomite/ankerite, iron-rich and subsequent iron-poor calcite is the latest recorded event. (author) 21 refs., 10 figs., 1 tab

296

Simulated warm polar currents during the middle Permian  

Energy Technology Data Exchange (ETDEWEB)

During Permian Stage 6 (Wordian, Kazanian) the Pangaean supercontinent was surrounded by a superocean - Panthalassa. An ocean general circulation model has been coupled to an atmospheric energy balance model to simulate the sensitivity of the Wordian climate ({proportional_to}265 million years ago) to changes in greenhouse gas concentrations, high latitude geography, and Earth orbital configurations. The model shows a high sensitivity of the ocean circulation to changes in the greenhouse gas forcing, ranging from a forceful southern circulation at low CO{sub 2} concentration (present level) to a more symmetric circulation cell with deep water formation in both hemispheres at high CO{sub 2} concentration (8 x present level). The simulated climate with 4 x present level CO{sub 2} concentration agrees generally well with climate-sensitive sediments and phytogeographic patterns. In this experiment, the model simulates strong subtropical gyres with similarities to the modern South Pacific circulation and moderate surface temperatures on the southern continent Gondwana, resulting from a strong poleward heat transport in the ocean. An even more moderate climate can be generated if high latitude land is removed so that ocean currents can penetrate into the polar regions or if orbital configurations favor high summer insolation over Gondwana. (orig.)

Winguth, A.M.E.; Kutzbach, J.E. [Wisconsin Univ., Madison, WI (USA). Center for Climatic Research; Heinze, C.; Maier-Reimer, E.; Mikolajewicz, U. [Max-Planck-Institut fuer Meteorologie, Hamburg (Germany); Rowley, D.; Rees, A.; Ziegler, A.M. [Chicago Univ., IL (United States). Dept. of Geophysical Sciences

2001-05-01

297

Fullerenes and Interplanetary Dust at the Permian-Triassic Boundary  

Science.gov (United States)

We recently presented new evidence that an impact occurred ~250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a 3He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for 3He vs. giant impact for fullerene).

Poreda, Robert J.; Becker, Luann

2003-01-01

298

Radon in the Creswell Crags Permian limestone caves  

International Nuclear Information System (INIS)

An investigation of radon levels in the caves of Creswell Crags, Derbyshire, an important Site of Special Scientific Interest (SSSI) shows that the Lower Magnesian Limestone (Permian) caves have moderate to raised radon gas levels (27-7800 Bq m-3) which generally increase with increasing distance into the caves from the entrance regions. This feature is partly explained in terms of cave ventilation and topography. While these levels are generally below the Action Level in the workplace (400 Bq m-3 in the UK), they are above the Action Level for domestic properties (200 Bq m-3). Creswell Crags has approximately 40,000 visitors per year and therefore a quantification of effective dose is important for both visitors and guides to the Robin Hood show cave. Due to short exposure times the dose received by visitors is low (0.0016 mSv/visit) and regulations concerning exposure are not contravened. Similarly, the dose received by guides is fairly low (0.4 mSv/annum) due in part to current working practice. However, the risk to researchers entering the more inaccessible areas of the cave system is higher (0.06 mSv/visit). This survey also investigated the effect of seasonal variations on recorded radon concentration. From this work summer to winter ratios of between 1.1 and 9.51 were determined for different locations within the largest cave system

299

Stratigraphic architecture of back-filled incised-valley systems: Pennsylvanian-Permian lower Cutler beds, Utah, USA  

Science.gov (United States)

The Pennsylvanian to Permian lower Cutler beds collectively form the lowermost stratigraphic unit of the Cutler Group in the Paradox Basin, southeast Utah. The lower Cutler beds represent a tripartite succession comprising lithofacies assemblages of aeolian, fluvial and shallow-marine origin, in near equal proportion. The succession results from a series of transgressive-regressive cycles, driven by repeated episodes of climatic variation and linked changes in relative sea-level. Relative sea-level changes created a number of incised-valleys, each forming through fluvial incision during lowered base-level. Aeolian dominance during periods of relative sea-level lowstand aids incised-valley identification as the erosive bounding surface juxtaposes incised-valley infill against stacked aeolian faces. Relative sea-level rises resulted in back-flooding of the incised-valleys and their infill via shallow-marine and estuarine processes. Back-flooded valleys generated marine embayments within which additional local accommodation was exploited. Back-filling is characterised by a distinctive suite of lithofacies arranged into a lowermost, basal fill of fluvial channel and floodplain architectural elements, passing upwards into barform elements with indicators of tidal influence, including inclined heterolithic strata and reactivation surfaces. The incised-valley fills are capped by laterally extensive and continuous marine limestone elements that record the drowning of the valleys and, ultimately, flooding and accumulation across surrounding interfluves (transgressive surface). Limestone elements are characterised by an open-marine fauna and represent the preserved expression of maximum transgression.

Wakefield, Oliver J. W.; Mountney, Nigel P.

2013-12-01

300

Permian plants from the Chutani Formation (Titicaca Group, Northern Altiplano of Bolivia): I. Genera Pecopteris and Asterotheca  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Plantas fósseis, pertencentes aos morfo-gêneros Glossopteris, Pecopteris e Asterotheca, foram coletadas na porção superior da seção aflorante da Formação Chutani, próxima ao povoado de San Pablo de Tiquina, sudeste do lago Titicaca (Altiplano norte, Bolívia). Este trabalho analisa folhagens do tipo [...] feto encontradas neste sítio. Entre os espécimes estéreis, três espécies de frondes pecopterídeas foram identificadas: Pecopteris dolianiti, P. cf. cadeadensis e P. cf. pedrasica. Todas essas espécies eram até agora restritas aos depósitos permianos da Bacia do Paraná. A despeito do estado de preservação ruim do material, um espécime fértil pôde ser determinado como pertencente ao gênero Asterotheca. Implicações paleoambientais e paleoecológicas deste novo achado são brevemente analisadas. Abstract in english Fossil plants belonging to the morphogenera Glossopteris, Pecopteris and Asterotheca were collected from the upper part of the Chutani Formation (Titicaca Group), near the town of San Pablo de Tiquina, on the southeastern shore of Lake Titicaca (northern Altiplano, Bolivia). Here we report the analy [...] sis of fern-type foliage found at this location. Three species of pecopterid fronds are identified: Pecopteris dolianitii Rohn and Rösler, P. cf. P. cadeadensis Rohn and Rösler, and P. cf. P. pedrasica Read. All these species are typically found in Permian deposits of the Paraná Basin in southern Brazil. Despite the poor preservation of the material, a fertile specimen could be studied and was determined as Asterotheca sp. The paleoenvironmental and paleoecological implications of this new find are briefly analyzed.

Carlos E. L., Vieira; Roberto, Iannuzzi; Margot, Guerra-Sommer; Enrique, Díaz-Matrínez; George W., Grader.

2004-03-01

301

Influence of localised igneous activity on cleat dawsonite formation in Late Permian coal measures, Upper Hunter Valley, Australia  

Energy Technology Data Exchange (ETDEWEB)

Stable ({delta}{sup 13}C and {delta}{sup 18}O) and radiogenic {sup 87}Sr/{sup 86}Sr isotopic data have been used to investigate the origin of cleat dawsonite (NaAlCO{sub 3}(OH){sub 2}) in the Late Permian Wittingham Coal Measures of the Upper Hunter region in the Sydney Basin, New South Wales. The {delta}{sup 13}C{sub PDB} values have a narrow range (-1.7%% to +2.4%%), with an average of +0.3%%, suggesting a magmatic source for the carbon. In contrast, {delta}{sup 18}O{sub SMOW} values have a wide range (+13.6%% to +19.8%%), and decrease systematically with decreasing distance from a major intrusion. This systematic variation reflects establishment of localised hydrothermal cells. Water-rock interaction between fluids associated with these hydrothermal cells, and Rb-poor volcaniclastic detritus in the coal measures, produced mantle-like {sup 87}Sr/{sup 86}Sr (0.705032 to 0.706464) in the dawsonite. (author)

Golab, Alexandra N.; Palamara, Daniel R. [School of Civil, Mining and Environmental Engineering, University of Wollongong, NSW, 2522 (Australia); Carr, Paul F. [School of Earth and Environmental Sciences, University of Wollongong, NSW, 2522 (Australia)

2006-04-03

302

Raining lead around 250mya a smoking gun for an Australian impact origin of the Permian Extinction  

CERN Document Server

Recent documentation of extreme atmospheric sulfur and methane contents at the time of the vast Permo-Triassic (P-T) extinction makes it possible to interpret an observation that has lain unnoticed in the geological literature for 40 years. This is the finding of microscopic metallic lead tear drops in the fluvial strata of the early Triassic sandstones that overlie Permian coal beds and other sedimentary deposits in the Sydney basin of Australia. Elemental lead is almost unknown in nature, so its occurrence in these graphite-loaded sandstones is a provocative finding. While climate change and vulcanism could explain the carbon and sulfur anomalies, the only way to account for metallic lead aerodynamic droplets is by massive impact and vaporization of lead mineral-containing formations. Since lead occurs geologically as the sulfide and since lead is an easily reduced element, its occurrence in conjunction with sulfur and carbon count anomalies suggests a bolide impact on carbon-loaded strata in a sulfide mine...

Standard, J C

2003-01-01

303

Organic petrology, thermal maturity, geology, and petroleum source rock potential of Lower Permian coal, Karoo supersystem, Zambia  

Energy Technology Data Exchange (ETDEWEB)

This paper reports on data concerning organic petrology and thermal maturity of Lower Karoo coal measures (Lower Permian) which are of considerable importance in determining the hydrocarbon potential of sediments in the rift-valley and half-graben complexes of the Luangwa and Zambezi valleys of eastern and southern Zambia, respectively, and in the extensive sedimentary basin developed on relatively stable Precambrian basement in western Zambia, a total area in excess of 3000 km{sup 2}. Samples from seven outcrop and subsurface localities situated in the northeast (northern Luangwa Valley), east (mid-Luangwa Valley), south (mid-Zambezi Valley), and the Western Province of Zambia were studied. The coal measures are from 9 to 280 m thick, but individual coal seams are generally less than 6 m. The coal macerals contain an average of 60% vitrinite and 9% liptinite, enough to have potential to generate hydrocarbon. A few samples contain twice this amount of liptinite. Reflected-light microscopy and the thermal alteration index of spores were used to determine the thermal maturity. The organic matter in samples studied is within the oil generation zone (thermal alteration index 2{minus} to 2+; %R{sub 0} max = 0.5-0.9). The petrological and palynological data indicate that the organic matter consists of Types II (generally approximately 25% in carbonaceous shale samples), III, and IV, indicating source rock potential. Late Karoo ( ) and post-Karoo fault blocks with differential vertical displacements may have produced structural traps suitable for oil and gas accumulation.

Utting, J. (Institute of Sedimentary and Petroleum Geology, Calgary, AB (Canada)); Wielens, H. (Unocal Canada Exploration Ltd., 150 6th Av. SW, Calgary, Alberta (CA))

1992-10-01

304

Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution.  

Science.gov (United States)

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured for different palaeogeographical provinces. Our results suggest a general trend from low osteichthyan diversity in the Permian to higher levels in the Triassic. Diversity dynamics in the Permian are marked by a decline in freshwater taxa during the Cisuralian. An extinction event during the end-Guadalupian crisis is not evident from our data, but 'palaeopterygians' experienced a significant body size increase across the Guadalupian-Lopingian boundary and these fishes upheld their position as large, top predators from the Late Permian to the Late Triassic. Elevated turnover rates are documented at the Permian-Triassic boundary, and two distinct diversification events are noted in the wake of this biotic crisis, a first one during the Early Triassic (dipnoans, actinistians, 'palaeopterygians', 'subholosteans') and a second one during the Middle Triassic ('subholosteans', neopterygians). The origination of new, small taxa predominantly among these groups during the Middle Triassic event caused a significant reduction in osteichthyan body size. Neopterygii, the clade that encompasses the vast majority of extant fishes, underwent another diversification phase in the Late Triassic. The Triassic radiation of Osteichthyes, predominantly of Actinopterygii, which only occurred after severe extinctions among Chondrichthyes during the Middle-Late Permian, resulted in a profound change within global fish communities, from chondrichthyan-rich faunas of the Permo-Carboniferous to typical Mesozoic and Cenozoic associations dominated by actinopterygians. This turnover was not sudden but followed a stepwise pattern, with leaps during extinction events. PMID:25431138

Romano, Carlo; Koot, Martha B; Kogan, Ilja; Brayard, Arnaud; Minikh, Alla V; Brinkmann, Winand; Bucher, Hugo; Kriwet, Jürgen

2014-11-27

305

Tectono-metamorphic map of the Mont Morion Permian metaintrusives (Mont Morion - Mont Collon - Matterhorn Complex, Dent Blanche Unit), Valpelline - Western Italian Alps  

OpenAIRE

The presented map displays the structural and metamorphic evolution of lithotypes from pre-Permian to present. We distinguish pre-Permian rocks (e.g., amphibolite, biotite-bearing gneiss and acid granulite) preserved as roof pendants (i.e., xenoliths) within Permian intrusives. Permian intrusives and hosted xenoliths are then re-equilibrated during Alpine evolution, producing coronitic to mylonitic metaintrusives, due to meter to kilometer-scale fabric gradients, and associated white mica-, g...

Zucali, Michele

2011-01-01

306

Provenance and structural constraints of the early Permian Nambucca Block (eastern Australia), and implications for the origin of the New England oroclines  

Science.gov (United States)

The late Paleozoic to early Mesozoic southern New England Orogen of eastern Australia exhibits a remarkable omega-shaped orogenic curvature (orocline), but the geodynamic processes responsible for the formation of the orogenic curvatures (oroclines) are still unclear. Oroclinal bending took place during the early Permian, simultaneously with the development of rift-related sedimentary basins (Sydney, Gunnedah and Bowen basins), which bound the oroclines to the west. The Nambucca Block is part of another early Permian rift basin that is situated farther east, in the core of the oroclinal structure. We present new stratigraphic, structural and geochronological data from the Nambucca Block in an attempt to better understand its provenance, tectonic history and its role in the formation of the oroclines. Four phases of folding and associated structural fabrics are recognised in the Nambucca Block. 40Ar/39Ar age of metamorphic micas from the second deformational phase provides a minimum depositional age constraint at 275-265 Ma. This age overlaps with the timing of oroclinal bending, suggesting that the first two phases of deformation resulted from the same mechanism that formed the oroclines. Detrital zircon geochronology (U/Pb ICP-MS ages) of six samples from the Nambucca Block constrains the maximum depositional age of the sequence to 280 Ma. The sedimentary succession, though extremely polymictic, is unimodal in its sources, and is therefore interpreted to consist mainly of recycled detritus from a Devonian-Carboniferous accretionary complex. We propose a model for oroclinal bending involving three stages. The first stage, starting at about 293 Ma and including the deposition of the sequence of Nambucca (i.e. overlaps with the 280-265 Ma time constraint), was associated with formation of rift basins in an extensional backarc setting. This was followed by N-S contraction, which gave rise to second-order oroclinal structures. The third and final stage involved contractional deformation that gave rise to recumbent folds and penetrative sub-horizontal structural fabrics at 275-265 Ma and further tightened the oroclinal structure.

Shaanan, Uri; Rosenbaum, Gideon; Li, Pengfei; Vasconcelos, Paulo; Wormald, Richard

2014-05-01

307

Stress and strain modeling of the Central European Basin System  

Science.gov (United States)

The present study presents results from 2D numerical models concerning the tectonic evolution of the Central European Basin System (CEBS) in North and Central Europe. The modeling approach is based on the classical thin sheet formulation here implemented for a spherical geometry in order to model large-scale lithospheric stress and deformation fields. Additional 3D steady state conductive finite element temperature and lithospheric strength models for different time slices are carried out in order to provide suitable input parameters and constraints for the numerical simulations. The study provides insight into the tectonic evolution through time of the main Permian basins and Mesozoic troughs in the system. The obtained results elucidate the relevance of inherited large-scale lithospheric structures in combination with slightly variable stress boundary conditions as derived by several published (palaeo)tectonic plate reconstructions. The complex geological evolution of the different sub-basins reflects the mechanical response of these basins to far-field intraplate stresses which governed the megatectonic setting of Western and Central Europe. On the other hand, inherited crustal and deeper structures inducing processes as strain localization and major deviation of stresses provide first order elements in controlling the evolution of the basin system. The obtained results strongly suggest the close interplay between lithospheric structure and geodynamic forces in controlling basin evolution through time.

Cacace, M.; Bayer, U.

2009-04-01

308

Permian tetrapods from the Sahara show climate-controlled endemism in Pangaea.  

Science.gov (United States)

New fossils from the Upper Permian Moradi Formation of northern Niger provide an insight into the faunas that inhabited low-latitude, xeric environments near the end of the Palaeozoic era (approximately 251 million years ago). We describe here two new temnospondyl amphibians, the cochleosaurid Nigerpeton ricqlesi gen. et sp. nov. and the stem edopoid Saharastega moradiensis gen. et sp. nov., as relicts of Carboniferous lineages that diverged 40-90 million years earlier. Coupled with a scarcity of therapsids, the new finds suggest that faunas from the poorly sampled xeric belt that straddled the Equator during the Permian period differed markedly from well-sampled faunas that dominated tropical-to-temperate zones to the north and south. Our results show that long-standing theories of Late Permian faunal homogeneity are probably oversimplified as the result of uneven latitudinal sampling. PMID:15829962

Sidor, Christian A; O'Keefe, F Robin; Damiani, Ross; Steyer, J Sébastien; Smith, Roger M H; Larsson, Hans C E; Sereno, Paul C; Ide, Oumarou; Maga, Abdoulaye

2005-04-14

309

Terrestrial paleoenvironment characterization across the Permian-Triassic boundary in South China  

Science.gov (United States)

Well-preserved marine fossils in carbonate rocks permit detailed studies of the end-Permian extinction event in the marine realm. However, the rarity of fossils in terrestrial depositional environments makes it more challenging to attain a satisfactory degree of resolution to describe the biotic turnover on land. Here we present new sedimentological, paleontological and geochemical (X-ray fluorescence) analysis from the study of four terrestrial sections (Chahe, Zhejue, Mide and Jiucaichong) in Western Guizhou and Eastern Yunnan (Yangtze Platform, South China) to evaluate paleoenvironmental changes through the Permian-Triassic transition. Our results show major differences in the depositional environments between the Permian Xuanwei and the Triassic Kayitou formations with a change from fluvial-lacustrine to coastal marine settings. This change is associated with a drastic modification of the preservation mode of the fossil plants, from large compressions to small comminuted debris. Plant fossils spanning the Permian-Triassic boundary show the existence of two distinct assemblages: In the Xuanwei Formation, a Late Permian (Changhsingian) assemblage with characteristic Cathaysian wetland plants (mainly Gigantopteris dictyophylloides, Gigantonoclea guizhouensis, G. nicotianaefolia, G. plumosa, G. hallei, Lobatannularia heinanensis, L. cathaysiana, L. multifolia, Annularia pingloensis, A. shirakii, Paracalamites stenocostatus, Cordaites sp.) is identified. In the lowermost Kayitou Formation, an Early Triassic (Induan) Annalepis-Peltaspermum assemblage is shown, associated with very rare, relictual gigantopterids. Palynological samples are poor, and low yield samples show assemblages almost exclusively represented by spores. A ?1 m thick zone enriched in putative fungal spores was identified near the top of the Xuanwei Formation, including diverse multicellular forms, such as Reduviasporonites sp. This interval likely corresponds to the PTB 'fungal spike' conventionally associated with land denudation and ecosystem collapse. While the floral turnover is evident, further studies based on plant diversity would be required in order to assess contribution linked to the end-Permian mass extinction versus local paleoenvironmental changes associated with the transition between the Xuanwei and Kayitou formations.

Bercovici, Antoine; Cui, Ying; Forel, Marie-Béatrice; Yu, Jianxin; Vajda, Vivi

2015-02-01

310

Origin of the Permian-Triassic komatiites, northwestern Vietnam  

Science.gov (United States)

Rare examples of Phanerozoic komatiites are found in the Song Da zone, NW Vietnam. These komatiites were erupted through continental crust and may belong to the SE extension of the Permo-Triassic Emeishan volcanic province located in SW China. They provide a good opportunity to study the source characteristics of starting plume magmas in a continental flood basalt province. Erupted on late-Permian carbonate rocks, the komatiitic rocks are interbedded with low-Ti olivine basalts. Basaltic komatiites display pyroxene spinifex textures, while more magnesian rocks (MgO up to 32 wt.%) are porphyritic, containing a single, cognate population of euhedral to elongated olivine phenocrysts with Fo up to 93.0%. This suggests a highly magnesian parental magma with 22-23 wt.% MgO. In terms of major and minor elements, the komatiites are similar to the ca. 89 Ma old Gorgona Island komatiites of Colombia. The Song Da komatiites are also strongly light-rare-earth-element- (LREE) depleted (CeN/YbN 0.30-0.62) and have unfractionated heavy rare earth element (HREE) patterns. The komatiites have high Os concentrations (up to 7.0 ppb), low but variable Re/Os ratios, and define an isochron with an age of 270+/-21 Ma, and an initial 188Os/187Os ratio of 0.12506+/- 0.00041 (?Os=+0.02+/-0.40). The Os isotopic systematics of the komatiites show no effects of crustal contamination. In contrast, their initial ?Nd values range from +3 to +8, reflecting varying but generally small degrees of contamination with Proterozoic sialic basement material. Associated low-Ti basalts have low initial ?Nd values (-0.8 to -7.5), high initial ?Os values (>=15), flat or LREE-enriched REE patterns, and Nb-Ta depletion. These characteristics are also attributed to variable extents of crustal contamination.

Hanski, Eero; Walker, Richard J.; Huhma, Hannu; Polyakov, Gleb V.; Balykin, Pavel A.; Tran Trong Hoa; Ngo Thi Phuong

311

The first record of Upper Permian and Lower Triassic scorpions from Russia (Chelicerata: Scorpiones.  

Directory of Open Access Journals (Sweden)

Full Text Available Several small fragments of fossil scorpions are reported from two localities in Vologda Province, Russia, representing the Upper Permian (Severodvinian, correlated to Wuchiapingian (Isady and Lower Triassic just above the Permian-Triassic boundary (Induan (Nedubrovo. Most observed structures are not diagnostic at genus or family level. The Isady leg fragment possesses ungues (claws, which are both denticulated and setaceous, and resembles a Carboniferous Eobuthus sp. (Eobuthidae. It is the latest record of this type of ungues, which are known in some Paleozoic scorpions (extinct suborder Mesoscorpiones; all extant scorpions have smooth claws without enticulation or setation.

Fet, V.

2011-08-01

312

Large perturbations of the carbon cycle during recovery from the end-permian extinction.  

Science.gov (United States)

High-resolution carbon isotope measurements of multiple stratigraphic sections in south China demonstrate that the pronounced carbon isotopic excursion at the Permian-Triassic boundary was not an isolated event but the first in a series of large fluctuations that continued throughout the Early Triassic before ending abruptly early in the Middle Triassic. The unusual behavior of the carbon cycle coincides with the delayed recovery from end-Permian extinction recorded by fossils, suggesting a direct relationship between Earth system function and biological rediversification in the aftermath of Earth's most devastating mass extinction. PMID:15273391

Payne, Jonathan L; Lehrmann, Daniel J; Wei, Jiayong; Orchard, Michael J; Schrag, Daniel P; Knoll, Andrew H

2004-07-23

313

Restoration of geometry and emplacement mode of the Permian mafic dyke swarms in Keping and its adjacent areas of the Tarim Block, NW China  

Science.gov (United States)

The Permian mafic dyke swarms are widely distributed in the Tarim Block, East Tianshan and the western Junggar Block in northwestern China. These mafic dyke swarms, together with coeval basalts, mafic-ultramafic intrusions and A-type granitic plutons, constitute the Permian Tarim large igneous province (LIP), which is considered to be mantle plume-derived. In this study, multi-source high-resolution remote sensing images are used to identify the geometry and emplacement mode of the mafic dykes, sills and flood basalts in Keping and its adjacent areas including Bachu (northwestern Tarim Block), Beishan and Kuluketag (northeastern Tarim Block) and Kelamyi (western Junggar Block). Structural analysis and paleomagnetic results are used to restore the primary geometry of the mafic dykes. The results indicate that the lengths and thicknesses among a total of 117 extracted mafic dykes in Keping follow negative exponent size distributions. The mafic dykes have a mean thickness of 3.8 m with a maximum of 21.4 m. The length of unconnected mafic dyke segments ranges from 0.127 km to 17.1 km, with an arithmetic length of 1.8 km. The restoration of geometry of the mafic dykes indicates that the Permian mafic dyke swarms in Keping may have extended as far as 61-69 km along a primary orientation of about N320°W, and the flood basalts of the Tarim LIP may have extended to Keping so that the areal extent of the Tarim LIP could be enlarged for about 12,000 km2 compared with that originally reported (about 250,000 km2). The geometric features of the mafic dyke swarms in Keping and its adjacent areas are different from those of the giant radiating dyke swarms due to radial fractures associated with domal uplift. The mafic dyke swarms and sills in the Tarim LIP make up the plumbing system of the mantle plume. Accompanied by the upwelling of mantle plume, many eruptive centers and regional dykes are generated in Beishan, East Tianshan and Tarim basin. The flood basalts in Keping are fissure-type, which may have been fed by magma conduits from the plume center; whereas in Bachu, the central volcanic eruption is dominant.

Chen, Ning-hua; Dong, Jin-jin; Yang, Shu-feng; Chen, Jian-yu; Li, Zi-long; Ni, Ni-na

2014-09-01

314

Mesozoic evolution of the Amu Darya basin  

Science.gov (United States)

This study, granted by the Darius Programme, aims at proposing a model of tectono-stratigraphic evolution of the Amu Darya basin since the Late Palaeozoic and to understand the relationship with the nearby basins. The Amu Darya basin, as its close eastern neighbour, the Afghan-Tajik basin, lies on the Turan platform, after the closure of the Turkestan Ocean during the Late Paleozoic. These two basins, spread on mainly lowlands of Turkmenistan, southwest Uzbekistan, Tajikistan, and northern Afghanistan, are separated from one another by the South-Western Gissar meganticline, where series of the northern Amu Darya margin are outcropping. The evolution is closely controlled by several periods of crustal thinning (post-collision rifting and back-arc extension), with some marine incursions, coming in between accretions of continental blocks and collisions that succeeded from the Late Triassic-Early Jurassic (Eo-Cimmerian orogeny) to the Cenozoic times. These orogenies controlled the deposition of thick clastics sequences, and the collision of the Indian Plate with Eurasia strongly deformed the sedimentary cover of the Afghan-Tajik basin. The more than 7 km thick Meso-Cenozoic sedimentary succession of the Amu Darya basin, lies on a complex system of rifts and blocks. Their orientation and age (late Permian, Triassic?) are not well known because of deep burial. The north-eastern margin, with the Bukhara (upper margin) and Chardzhou steps, is NW oriented, parallel to the Paleozoic Turkestan suture. The orientation bends to W-E, in the part of the Gissar situated to the North of the Afghan-Tajik basin. This EW trending orientation prevails also in the south(-eastern) margin of the basin (series of North Afghanistan highs) and in the Murgab depression, the south-eastern deepest portion of the Amu Darya basin. It is in this area and in the eastern part of the Amu Darya basin that the Jurassic as well as the lower Cretaceous sediments are the thickest. The south-western part of the basin is occupied by the Pre-Kopet Dagh Cenozoic foreland basin NW oriented, possibly underlain by an earlier extensional trough. The main elements of the sedimentary pile, which can be partly observed in the South-Western Gissar are: Lower to Middle Jurassic continental to paralic clastic rocks; upper Middle to Upper Jurassic marine carbonate then thick Tithonian evaporite rocks, sealing the reservoirs in the Jurassic carbonates; continental Neocomian clastic rocks and red beds, Aptian to Paleogene marine carbonate and clastic rocks. To reconstruct the geodynamic evolution of the Amu Darya Basin, we analysed the subsidence by backstripping of some wells/pseudo-wells and of three cross-sections with some examples of thermal modelling on the periods of maturation of the potential source rocks. The crustal thinning events take place in the Permo-Triassic? (depending on the age of the rifts underlying the basin), in Early-Middle Jurassic and during the Early Cretaceous, resulting in increases of the tectonic subsidence rates.

Brunet, Marie-Françoise; Ershov, Andrey; Korotaev, Maxim; Mordvintsev, Dmitriy; Barrier, Eric; Sidorova, Irina

2014-05-01

315

Anatomy of a Permian Erg sequence: the De La Cuesta Formation (northwestern Argentina)  

International Nuclear Information System (INIS)

This work is about the Permian red beds of the La Cuesta Formation (Sierra de Narvaez, northwestern Argentina) which is composed of sandstones associated with mud stones and subordinate conglomerates. The sediments obtained from the interaction between aeolian and ephemeral fluvial systems, are represented by aeolian dune, dry aeolian inter dune and aeolian sand sheet, mud flat, wet aeolian inter dune, and fluvial deposits

316

Unique organic remains from an upper Permian coal bearing sequence in the Talcher Coalfield, Orissa, India  

Energy Technology Data Exchange (ETDEWEB)

The playnological assemblage of coal bearing upper Permian sequence of Talcher Coalfield registers presence of some peculiar organic remains. These are described as Orissiella gen. nov., which is characterized by a vesicle with collar-like structure at the oral end, spines and or corrugations on the body. The affinity and palaeoecological significance of Orissiella is also discussed. 12 refs., 4 figs., 2 plates.

Tripathi, A. [Birbal Sahni Institute of Palaeobotany, Lucknow (India)

2004-07-01

317

Carnivorous dinocephalian from the Middle Permian of Brazil and tetrapod dispersal in Pangaea.  

Science.gov (United States)

The medial Permian (~270-260 Ma: Guadalupian) was a time of important tetrapod faunal changes, in particular reflecting a turnover from pelycosaurian- to therapsid-grade synapsids. Until now, most knowledge on tetrapod distribution during the medial Permian has come from fossils found in the South African Karoo and the Russian Platform, whereas other areas of Pangaea are still poorly known. We present evidence for the presence of a terrestrial carnivorous vertebrate from the Middle Permian of South America based on a complete skull. Pampaphoneus biccai gen. et sp. nov. was a dinocephalian "mammal-like reptile" member of the Anteosauridae, an early therapsid predator clade known only from the Middle Permian of Russia, Kazakhstan, China, and South Africa. The genus is characterized, among other features, by postorbital bosses, short, bulbous postcanines, and strongly recurved canines. Phylogenetic analysis indicates that the Brazilian dinocephalian occupies a middle position within the Anteosauridae, reinforcing the model of a global distribution for therapsids as early as the Guadalupian. The close phylogenetic relationship of the Brazilian species to dinocephalians from South Africa and the Russian Platform suggests a closer faunistic relationship between South America and eastern Europe than previously thought, lending support to a Pangaea B-type continental reconstruction. PMID:22307615

Cisneros, Juan Carlos; Abdala, Fernando; Atayman-Güven, Saniye; Rubidge, Bruce S; ?engörc, A M Celâl; Schultz, Cesar L

2012-01-31

318

Water-rock-CO{sub 2} interactions in saline aquifers aimed for carbon dioxide storage: Experimental and numerical modeling studies of the Rio Bonito Formation (Permian), southern Brazil  

Energy Technology Data Exchange (ETDEWEB)

Mineral trapping is one of the safest ways to store CO{sub 2} underground as C will be immobilized in a solid phase. Carbon dioxide will be, therefore, sequestered for geological periods of time, helping to diminish greenhouse gas emissions and mitigate global warming. Although mineral trapping is considered a fairly long process, owing to the existence of kinetic barriers for mineral precipitation, it has been demonstrated both experimentally and by numerical modeling. Here the results of experimental and numerical modeling studies performed in sandstones of the saline aquifer of the Rio Bonito Formation, Parana Basin, are presented. The Rio Bonito Formation consists of paralic sandstones deposited in the intracratonic Parana Basin, southern Brazil, during the Permian (Artinskian-Kungurian). These rocks have the largest potential for CO{sub 2} storage because of their appropriated reservoir quality, depth and proximity to the most important stationary CO{sub 2} sources in Brazil. Here it is suggested that CO{sub 2} can be permanently stored as carbonates as CO{sub 2} reacts with rocks of the Rio Bonito Formation and forms CaCO{sub 3} at temperatures and pressures similar to those encountered for CO{sub 2} storage in geological formations. Results of this work will be useful for studies of partitioning mechanisms for C trapping in CO{sub 2} storage programs.

Ketzer, J.M. [Brazilian Carbon Storage Research Center, Pontifical Catholic University, Av. Ipiranga 6681, Building 96J, Porto Alegre (Brazil); Iglesias, R., E-mail: rsiglesias@gmail.com [Brazilian Carbon Storage Research Center, Pontifical Catholic University, Av. Ipiranga 6681, Building 96J, Porto Alegre (Brazil); Einloft, S.; Dullius, J.; Ligabue, R.; Lima, V. de [Brazilian Carbon Storage Research Center, Pontifical Catholic University, Av. Ipiranga 6681, Building 96J, Porto Alegre (Brazil)

2009-05-15

319

Integrating petroleum and sulfur data to map the Guadalupian-Ochoan (Middle to Upper Permian) Boundary of the Delaware Basis, Trans-Pecos, Texas  

Science.gov (United States)

The Delaware Basin of the Permian Basin is a classic intra-cratonic basin of West Texas and Southeast New Mexico. Hydrocarbon exploration and production have occurred in the region since the early 1920s, and, as a result, the formations related to these oil and gas reserves have been studied in great detail. Some formations in the Delaware Basin, however, have not been studied in such detail, and this thesis examines one, lesser-known unit that could have economic potential. The Lamar Limestone (Lamar Lime) of the Bell Canyon Formation has commonly been dismissed as a production interval; rather, it has been described as a source and seal rock for the Ramsey Sand of the lower Bell Canyon Formation. However, recent studies found that the Lamar Lime was contributing to production, and it has been described by Trentham (2006) as a potentia "mini Barnett" reservoir. The depths of these deposits are in a range that is ideal for oil accumulation. This study made use of data from wells and test holes drilled in the western Delaware Basin, Culberson County, Texas. Many oil and gas wells have been drilled in the western Delaware Basin, but they are concentrated in the north and east portions of Culberson County. In addition, sulfur wells were drilled in the area in the late 1960s and early 1970s. Analyses of the well logs of these wells and of core and outcrop studies were completed to gain a better understanding of the distribution and economic potential of the Lamar. Both datasets were combined to provide information not readily available in the oil and gas dataset. The Lamar Lime is an excellent marker bed because it underlies thick evaporites. The evaporite sequences are Ochoan in age, and, therefore, the contact of the Lamar Lime (Bell Canyon Formation) and the Castile Formation is the approximate boundary for the Guadalupian-Ochoan Series. The Castile Formation, the Salado Formation, and the Rustler Formation (from oldest to youngest) are the evaporite units that consist of halite, gypsum, and anhydrite and are discussed herein. The boundary also marks a significant faunal-extinction event. The high organic content found in the Lamar Lime helps to evaluate the economic potential. Updated isopach and structural contour maps extend the knowledge of the Lamar Lime more to the western Delaware Basin.

Dishron, Joseph B.

2011-12-01

320

The Saint Martin de Belleville syncline and its uraniferous permian sandstone  

International Nuclear Information System (INIS)

This dissertation (these de specialite) is a study of the geology of the St.Martin d.B. syncline and the uranium prospect 'le Cochet' in the Carboniferous Brianconnais Zone of Savoy. Stratigraphy and sedimentology: This syncline presents continental detrital sediments ranging from U.Carboniferous to L.Triassic. In the U.Carboniferous, magmatic activity begins with the Moriaz Layers acid volcanics that are considered as a lateral equivalent of the Stephanian Courchevel Conglomerates. In Permian times, parts of an alluvial fan seem to occupy the north of the study area (gray and green conglomeratic sandstone). Southwards these inter-finger with flood plain sediments (red slate) including a locally oolitic limestone. Volcanic detritus is important in the Permian. Tourmalinite pebbles are frequent and seem to be related to the regional Permian magmatism. Albitization of feldspars is general in the Carboniferous and the Permian. The Permo-triassic typically shows microcline bearing dolomitic sandstones. In the Scythian quartzites orthoclase is the dominant feldspar. The quartzites are overlain by L.Triassic evaporites identified by the sulfur isotope ratio of their gypsum. The morphology of the zircons in the sandstones has been investigated using the typological method of J.P. Pupin. Regional Permian magmatism apparently produces volcanics of the calc-alkalic and tholeiitic series as well as a high level granitic intrusion of anatectic origin. The uranium occurrences are strata-bound on a kilometric and hecto-metric scale. They are developed almost exclusively in the gray variety of the Permian sandstones whose gray and red varieties are always barren. Within this unit, the mineralization impregnates irregularly distributed lenses and pods of coal material. Uranium is accompanied by vanadium occurring as roscoelite. The association U-V, of bio-philic character, reflects the concentration in the sedimentary environment and argues for a quite indirect relation with the source rocks. The mineralization is regarded as syn-genetic or more probably early epigenetic of Permian age, related to surface or groundwater flow that precipitated its metal content on wooden debris ('trash piles') in the host rocks. Alpine deformation resulted in folds and strong schistosity striking N2O that almost obliterate north verging transverse folds. The deformation caused plastic flow of the mineralized carbonaceous material on a metric scale. This material is now commonly found in lenses parallel to schistosity. Metamorphism is at the epizone/anchizone limit with a barrovian to high pressure gradient. It had practically no effect on the mineralization. (author)

321

Ostracods (Crustacea associated with microbialites across the Permian-Triassic boundary in Dajiang (Guizhou Province, South China  

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Full Text Available 26 samples were processed for a taxonomic study of ostracods from the Upper Permian (Changhsingian - Lower Triassic (Griesbachian interval of the Dajiang section, Guizhou Province, South China. 112 species belonging to 27 genera are recognized. Five new species are described: Acratia candyae sp. nov, Bairdia adelineae sp. nov., Bairdia? huberti sp. nov., Bairdia jeromei sp. nov., Orthobairdia jeanlouisi sp. nov. The unexpected survival faunas associated with microbial formations in the aftermath of the end-Permian extinction are documented for the first time. Ostracod biodiversity variations and palaeo-environmental modifications associated with microbial growth through the Permian-Triassic boundary (PTB are discussed.

Marie-Beatrice FOREL

2012-08-01

322

Using conodont elements to distinguish Permian-Triassic boundary disconformity near Haftad Gholleh, central Iran  

Scientific Electronic Library Online (English)

Full Text Available El presente estudio se enfoca en la estatigrafía del Límite Pérmico-Triásico en el área de Haftad Gholleh, al este de Arak y al norte de Mahallat, centro de Irán. Este límite de discordancia erosiva, al igual que en otras secuencias iraníes relacionadas al período Pérmico, contiene calizas dolomías, [...] esquistos y areniscas discordantes localizadas debajo de la secuencia Triásica. En una medida estratigráfica detallada del área de estudio se encontraron conodontas del Límite Pérmico-Triásico (PTB, por sus siglas en inglés). Se reconocieron tres áreas de conodontas, lo que ubica esta sección del PTB como bioestatigráfica precisa. Una de las secuencias superiores del Pérmico pertenece al período Guadalupiense. La secuencia Triásica consiste en calizas con capas vermiculitas coloreadas de esquisto que pertenecen al período Triásico temprano. La discordancia del Límite Pérmico Triásico, entonces, representa un lapso cercano a los 10 millones de años. Abstract in english The present study focuses on the stratigraphy of the Permian-Triassic boundary in the Haftad Gholleh area in eastern Arak and north of Mahallat,located in central Iran. This boundary of erosional unconformity or disconformity and as in other Iranian sequences related to the Permian period, contains [...] dolomitic limestone and shale and sandstone disconformably located below the Triassic sequence. A detailed measured stratigraphic section has provided conodonts from the Permian-Triassic boundary (PTB) sequences in the area being studied. Three conodont areas have been recognied which place the PTB in this section by precise biostratigraphy. One of the most upper Permian sequences belongs to the Guadalupian period. The Triassic sequence consists of vermiculate limestone layers with coloured shale inter beds belonging to the Early Triassic period; unconformity at the Permian-Triassic boundary therefore represents a hiatus of about 10 million years.

Mostafa, Yousefirad; Somayeh, Ghanbari; Mahnaz, Parvanehnejad Shirazi.

2013-06-01

323

Microbialites and global environmental change across the Permian-Triassic boundary: a synthesis.  

Science.gov (United States)

Permian-Triassic boundary microbialites (PTBMs) are thin (0.05-15 m) carbonates formed after the end-Permian mass extinction. They comprise Renalcis-group calcimicrobes, microbially mediated micrite, presumed inorganic micrite, calcite cement (some may be microbially influenced) and shelly faunas. PTBMs are abundant in low-latitude shallow-marine carbonate shelves in central Tethyan continents but are rare in higher latitudes, likely inhibited by clastic supply on Pangaea margins. PTBMs occupied broadly similar environments to Late Permian reefs in Tethys, but extended into deeper waters. Late Permian reefs are also rich in microbes (and cements), so post-extinction seawater carbonate saturation was likely similar to the Late Permian. However, PTBMs lack widespread abundant inorganic carbonate cement fans, so a previous interpretation that anoxic bicarbonate-rich water upwelled to rapidly increase carbonate saturation of shallow seawater, post-extinction, is problematic. Preliminary pyrite framboid evidence shows anoxia in PTBM facies, but interbedded shelly faunas indicate oxygenated water, perhaps there was short-term pulsing of normally saturated anoxic water from the oxygen-minimum zone to surface waters. In Tethys, PTBMs show geographic variations: (i) in south China, PTBMs are mostly thrombolites in open shelf settings, largely recrystallised, with remnant structure of Renalcis-group calcimicrobes; (ii) in south Turkey, in shallow waters, stromatolites and thrombolites, lacking calcimicrobes, are interbedded, likely depth-controlled; and (iii) in the Middle East, especially Iran, stromatolites and thrombolites (calcimicrobes uncommon) occur in different sites on open shelves, where controls are unclear. Thus, PTBMs were under more complex control than previously portrayed, with local facies control playing a significant role in their structure and composition. PMID:22077322

Kershaw, S; Crasquin, S; Li, Y; Collin, P-Y; Forel, M-B; Mu, X; Baud, A; Wang, Y; Xie, S; Maurer, F; Guo, L

2012-01-01

324

On the origin of the ultradeep East Barents Sea basin  

Science.gov (United States)

Very large subsidence, with up to 20 km thick sediment layers, is observed in the East Barents Sea basin. Subsidence started in early Paleozoic, accelerated in Permo-Triassic times, finished during the middle Cretaceous, and was followed by moderate uplift in Cenozoic times. The observed gravity signal suggests that the East Barents Sea is at present in isostatic balance and indicates that a mass excess is required in the lithosphere to produce the observed large subsidence. Several origins have been proposed for the mass excess. We use 1-D thermokinematic modeling and 2-D isostatic density models of continental lithosphere to evaluate these competing hypotheses. The crustal density in 2-D thermokinematic models resulting from pressure-, temperature-, and composition-dependent phase change models is computed along transects crossing the East Barents Sea. The results indicate the following. (1) Extension can only explain the observed subsidence provided that a 10 km thick serpentinized mantle lens beneath the basin center is present. We conclude that this is unlikely given that this highly serpentinized layer should be formed below a sedimentary basin with more than 10 km of sediments and crust at least 10 km thick. (2) Phase changes in a compositionally homogeneous crust do not provide enough mass excess to explain the present-day basin geometry. (3) Phase change induced densification of a preexisting lower crustal gabbroic body, interpreted as a mafic magmatic underplate, can explain the basin geometry and observed gravity anomalies. The following model is proposed for the formation of the East Barents Sea basin: (1) Devonian rifting and extension related magmatism resulted in moderate thinning of the crust and a mafic underplate below the central basin area explaining initial late Paleozoic subsidence. (2) East-west shortening during the Permian and Triassic resulted in densification of the previously emplaced mafic underplated body and enhanced subsidence dramatically, explaining the present-day deep basin geometry.

Gac, SéBastien; Huismans, Ritske S.; Podladchikov, Yuri Y.; Faleide, Jan Inge

2012-04-01

325

Vinna Basin.  

Czech Academy of Sciences Publication Activity Database

Prague : Czech Geological Survey, 2014, s. 223-241 ISBN 978-80-7075-862-5 R&D Projects: GA ?R GA105/06/0653 Institutional support: RVO:67985891 ; RVO:67985831 Keywords : Tertiary basins * Czech Republic * Cenomanian and Tertiary lignite * geology * stratigraphy Subject RIV: DB - Geology ; Mineralogy

Hon?k, J.; Franc?, J.; Mikuláš, Radek; Pešek, J.; Sýkorová, Ivana; Tomanová-Petrová, P.

326

Discussion of gas enrichment mechanism and natural gas origin in marine sedimentary basin, China  

Energy Technology Data Exchange (ETDEWEB)

There are abundant natural gas resources in Chinese marine sedimentary basin. The exploration hot shots of natural gas are the Palaeozoic marine strata here in recent years, and several large scale gas fields have been discovered. Chinese Palaeozoic high-post matured and coal measure hydrocarbon source rocks are mainly prone to gas generation in the present. This research considered that gas source rocks and TSR are the key cause of gas enrichment of marine strata. High-quality argillaceous and coal measure hydrocarbon rocks are distributed widely in the Palaeozoic marine strata, which have been in highly matured phase in the present. The argillaceous source rock generally contains various sulfates that could accelerate crude oil cracking to gas for TSR occurrence, and coal measure source rock mainly generates gas, so Chinese marine basin gives priority to accumulating gas. Marine strata have not founded oil reservoirs in the Sichuan Basin and Ordos Basin, and they consist mainly of dry gas. Marine natural gases are the mixed gases of oil cracking gas and coal-formed gas in a general way, oil cracking gases contain usually some H{sub 2}S and CO{sub 2}. Hydrocarbon carbon isotopes are very complicated, and methane and ethane isotopic values bear apparent reversal caused by thermal evolution and mixing among different genetic types of natural gas. Coal-formed gases are the main component of Chinese marine natural gas. The Upper Permian of the Sichuan Basin and the Carboniferous-Permian of the Ordos Basin coal measure hydrocarbon source rock present large hydrocarbon generation potential, which are the prospecting highlight of marine natural gas hereafter. Oil cracking gas exploration will be paid much attention to in the Tarim Basin because of the lack of coal measure hydrocarbon source rock.

Zhu, G.Y.; Zhao, W.Z.; Zhang, S.C.; Liang, Y.B.; Wang, Z.J.

2007-11-15

327

Glacial and proglacial Talchir sedimentation in Son-Mahanadi Gondwana basin: Paleogeographic reconstruction  

Science.gov (United States)

In the southern part of the Son-Mahanadi basin, the early Permian glacigene Talchir rocks occur in exhumed glacial valleys overlying the Precambrian basement unconformably with gentle to somewhat steeper contacts. In the broader low lying part to the north, the strata are flat lying and uninterrupted by granitic inliers. The overall sequence thickens progressively lengthwise from south (400 m) to north (800 m) and from the margins of the basin inward. Two distinct groups of facies characterize the Talchir assemblage. The first group, the proximal facies, occurs in exhumed valleys near the granitic highlands and includes diamictite, conglomerate, and sandstone. The second group, distal facies, occurs away from the highlands in the broader, northern region and abounds in fine elastics. This group includes shale and rhythmites containing dropstones. Paleocurrent analysis suggests that the ice movement and paleoflow of meltwater streams were directed locally inward and regionally along the length of the basin from southeast to northwest. The occurrence of marine fauna at Manendragarh and Umaria is the only evidence of marine ingression along the northwestern margin. However, there is no conclusive evidence of marine transgression to the south of Manendragarh. The present study suggests a somewhat plateau-like upland topography in the southern part of the Mahanadi basin, with a dissected northern edge passing into an extensive low-lying Son basin farther north. The entire southern terrain was characterized by the exhumed valleys dominated by glacial, glaciofluvial, and glaciolacustrine environments, whereas the low lying northern terrain represented deltaic milieu in the central part and tidal estuary setting along the margins of the basin in the northwest. The paper reconstructs the paleogeography of the Son-Mahanadi basin during early Permian time.

Casshyap, S. M.; Srivastava, V. K.

328

Late Palaeozoic palynomorph assemblages from the Karoo Supergroup and their potential for biostratigraphic correlation, Kalahari Karoo Basin, Botswana  

Directory of Open Access Journals (Sweden)

Full Text Available Late Carbonifeous to Permian core samples from two borehole sections, STRAT 1 and CKP 6, that penetrate the glacial to postglacial and coal-bearing Lower Karoo sequence, Kalahari Karoo Basin, Botswana, contain well preserved pollen and spore palynomorphs. The palynomorph assemblages comprise 165 species of spores and pollen, and few acritarchs and chlorophycean algae. This paper presents a local biozonation of three succeeding assemblage zones, recognisable in each borehole section. The assemblage zones are named: the Hamiapollenites bullaeformis Biozone, the Cyclogranisporites gondwanensis Biozone and the Platysaccus papilionis-Striatopodocarpites fusus Biozone, in ascending order of stratigraphy. Assemblages are compared and correlated with assemblages described from other Gondwana areas of Africa, Australia, Arabia, South America and Antarctica. A general analysis of taxa from the Kalahari Karoo Basin indicates a distinct similarity with assemblages from the Paraná Basin of South America. The Hamiapollenites bullaeformis Biozone is comparable with the Vittatina costabilis Interval Zone of the Paraná Basin. Assemblages from the Cyclogranisporites gondwanensis and the Platysaccus papilionis-Striatopodocarpites fusus zones are comparable with the Lueckisporites virkkiae Interval Zone. Age determination for the assemblages in the Kalahari Karoo Basin is inferred from comparison with similar assemblages from previous Gondwana studies, and ranges from the Late Carboniferous (Kasimovian-Gzhelian to latest Early or possibly earliest Middle Permian (Late Cisularian to Early Guadalupian.

Modie B N

2009-06-01

329

Summary of petrographic and chemical data for Palo Duro Basin samples examined by Bendix Field Engineering Corporation, Grand Junction, Colorado, as of April 29, 1983  

International Nuclear Information System (INIS)

Bendix Field Engineering Corporation performed petrographic and chemical analyses on selected samples from the Palo Duro Basin, Texas. Permian bedded salt in the basin is being evaluated as a candidate nuclear waste repository site. This report summarizes procedures, petrographic data, chemical data, and trends in these data. A total of 38 Unit 4 and Unit 5 salt samples from the Permian Lower San Andres Formation have been examined; in addition, 14 samples from outside the candidate salt horizons were analyzed. Petrographic data were gathered from thin-section analyses, bulk-rock x-ray diffraction, and clay-mineral analyses. Chemical data were derived from analyses of the water-soluble fraction. Samples from outside the salt horizons were also analyzed for whole-rock chemistry. 6 references, 5 figures, 3 tables

330

Integrated provenance analysis of Zakeen (Devonian) and Faraghan (early Permian) sandstones in the Zagros belt, SW Iran  

Science.gov (United States)

Successions of a controversial period of time in the Zagros and Arabian Plate stratigraphic column, including Zakeen (Devonian) and Faraghan (early Permian) formations are investigated for their provenance characteristics. Nearly similar depositional environments of the formations, regardless of 70-80 My hiatus between them, is the main motivation for this study. Evidence from various methods are put together to reconstruct a comprehensive image of their provenance. Results from petrographic and detrital mode analysis indicate a continental block provenance for of the sandstones of both formations. In addition, evidence of recycling is evident from some rock fragments in the conglomeratic facies. Heavy mineral diversities are limited to the ultra-stable species which represent consistent morphological characteristics in both formations. However, the values of rutile: zircon index (RZi) showed intermittent changes from low RZi to high RZi intervals in both formations. Detrital zircon age data in previous studies represented the same source for these two formations, which also remained unchanged from Neo-Proterozoic to late Paleozoic successions. Zircon grains' morphology, however, showed remarkable difference between the Zakeen and Faraghan formations on the one hand and successions deposited in the basin prior to the tectonic movements of mid-Paleozoic time on the other. Outcomes of this study show that, although each single technique may shed light on a particular aspect of the greater provenance problem, by integration of all the data, important evidence of recycled nature of these successions could be confirmed. Changes in the thickness of the Paleozoic units, the nature of their stratal surfaces, along with the information from magmatic events in the area provide a tectono-stratigraphic framework for northern margin of Gondwana in which the recycled nature of these successions is justifiable. The recycled nature of the studied formations on the one hand, and their identical provenance on the other, raise a challenge for the timing proposed for two tectonic activities of middle Paleozoic and mid-Carboniferous.

Zoleikhaei, Yousef; Amini, Abdolhossein; Zamanzadeh, S. Mohammad

2015-01-01

331

Integrated Vitrinite Reflectance and Apatite Fission Track Thermocronology of the Lower Karoo rocks in the Moatize Basin, Tete Province, Mozambique.  

Science.gov (United States)

The Karoo in Mozambique is represented by Late Carboniferous to Late Triassic sediments that were deposited in rift basins that fringe or developed between Proterozoic cratons. In Tete Province, central-west Mozambique, the Karoo is well represented along the Zambezi river valley forming several intra-cratonic basins separated by horsts consisting of igneous and high grade metamorphic Proterozoic rocks. One of the main horst blocks is located between the Cahora Bassa region and Tete city, separating the Middle Zambezi Basin and the Lower Zambezi Basin. The area of study is located in the Moatize Basin, one of many small basins that form the Lower Zambezi Basin. The stratigraphy of this basin consists of several sedimentary formations that record changes in depositional environment and palaeoclimate from glacial (Vúzi Formation - Lower Permian) at the base, through wet to temperate in the middle (Moatize Formation - Lower Permian), to warm arid at the top of the succession (Matinde and Cádzi formations - Middle to Upper Permian). The Upper Karoo volcanics of Early Jurassic age do not crop out in the Moatize Basin. One of the most remarkable characteristics of the Moatize Basin is the richness of coal deposits present in the Lower Permian Moatize Formation. Two coal exploration boreholes (DW123 - T.D. 489 m and DW132 - T.D. 516 m) drilled in the Moatize Basin were studied by means of vitrinite reflectance (VR) and apatite fission track analysis (AFTA), in order to assess their burial and uplift histories. The two boreholes intersected only Moatize Formation lithologies. VR increases in the two borehole sections from ca. 1.30-1.32 % Ro at the top to ca. 1.52-1.69 % Ro at the bottom, indicating medium to low volatile coal rank. Modelled VR data from the two boreholes indicate palaeogeothermal gradients between 40 and 56ºC/km, possible related to basin forming processes. Fission track ages increase from 84 Ma and 102 Ma at the bottom to 138 Ma and 146 Ma at the top of the DW132 and DW123 wells respectively. The Mean Track Length is approximately 11.7±0.2 ?m for the four samples studied. Inverse modelling of both VR and fission track data have been undertaken with QTQt software. The results are consistent for the two boreholes. Thermal histories indicate that samples have been heated to a maximum temperature of 150 to 180 °C following deposition. Maximum temperature was reached at 260 Ma., then a first phase of cooling occurred between 255 and 230 Ma, related to post Lower Karoo exhumation. The sections subsequently cooled very slowly until Neogene time. At 7 Ma, a second, fast cooling episode reduced rock temperatures from 50 - 60 °C to present day temperature. This second cooling episode is possibly related to exhumation caused by the uplift and erosion of the East-African rift shoulders. The thermal reconstruction indicates that the present coal rank was attained shortly after deposition. Following this burial under a thick sedimentary sequence of approximately 4 km, two main pulse of exhumation affected the Moatize Basin during the Triassic and Pliocene, eroding ca. 2.5 km of Upper Permian strata in the first and 1.5 km in the latter.

Fernandes, Paulo; Cogné, Nathan; Rodrigues, Bruno; Jorge, Raul; Marques, João

2014-05-01

332

Exploratory shaft conceptual design report: Paradox Basin  

International Nuclear Information System (INIS)

This conceptual design report summarizes the conceptualized design for an exploratory shaft facility at a representative site in the Paradox Basin located in the southeastern part of Utah. Conceptualized designs for other possible locations (Permian Basin in Texas and Gulf Interior Region salt domes in Louisiana and Mississippi) are summarized in separate reports. The purpose of the exploratory shaft facility is to provide access to the reference repository horizon to permit in situ testing of the salt. The in-situ testing is necessary to verify repository salt design parameters, evaluate isotropy and homogeneity of the salt, and provide a demonstration of the constructability and confirmation of the design to gain access to the repository. The fundamental purpose of this conceptual design report is to assure the feasibility of the exploratory shaft project and to develop a reliable cost estimate and realistic schedule. Because a site has not been selected and site-specific subsurface data are not available, it has been necessary to make certain assumptions in order to develop a conceptual design for an exploratory shaft facility in salt. As more definitive information becomes available to support the design process, adjustments in the projected schedule and estimated costs will be required

333

Sudden changes in fluvial style across the Permian / Triassic boundary in the eastern Iberian Ranges, Spain: Analysis of possible causes  

OpenAIRE

The sedimentary record of the Late Permian and Early Triassic of the eastern Iberian Ranges shows four major, sudden, or very rapid, vertical changes in fluvial style. The Late Permian sedimentary cycle starts with the Boniches Formation, of alluvial fan-braided fluvial origin, which grades vertically over within a few metres into the Alcotas Formation, deposited by low to high sinuosity, avulsion-prone rivers with extensive floodplains. The Alcotas Formation contains calcimorphic so...

Arche, Alfredo; Lo?pez Go?mez, Jose?

2005-01-01

334

Sensitivity of Late Permian climate to bathymetric features and implications for the mass extinction  

Science.gov (United States)

Evidence from stratigraphic sections of the Panthalassa, Paleo-Tethys and Neo-Tethys suggests that the oceans experienced widespread anoxia during the Late Permian, which likely contributed to the extinction of ~ 90% of marine and ~ 70% of terrestrial species. The Late Permian and Early Triassic were also characterized by significant carbon isotope excursions implying that considerable perturbations in the carbon cycle occurred. Bathymetric features of the Panthalassa during this period are not well known since most of the ocean floor has been subducted; however, tectonic reconstructions suggest that active marine subduction zones surrounded Pangea. Thus, it is reasonable to assume that there was an active mid-ocean ridge system located in Panthalassa during the Late Permian. In this study, the impact of such a spreading center within Panthalassa on the climate and carbon cycle is investigated using a comprehensive climate system model for the end-Permian. This is a novel approach because a majority of previous simulations assumed a flat bottom for the Panthalassa deep-sea. The mid-ocean ridge (MOR) simulation enhanced vertical mixing and topographic steering of the currents near the ridge-axis but in comparison with the simulation using a flat bottom, changes in the global distribution of water masses and circulation in the Panthalassa were insignificant. Dissolved oxygen concentrations were not considerably affected by the implementation of the mid-ocean ridge. Thus the approximation of using a flat-bottom topography in ocean models for the Late Permian remains valid. In a second sensitivity study, the effect of a sill between the deep Paleo-Tethys and Panthalassa on water mass distribution and oxygen content has been investigated. Model results suggest that the introduction of a sill led to enhanced stratification, as well as an increase in salinity and temperature in the Paleo-Tethys. An associated reduction of the dissolved oxygen concentration to dysoxic to near-anoxic conditions below 1800 m suggests that the changes in sill height between the Paleo-Tethys and Panthalassa may have been a contributing factor of regional importance to the Permian-Triassic mass extinction.

Osen, Angela K.; Winguth, Arne M. E.; Winguth, Cornelia; Scotese, Christopher R.

2013-06-01

335

Euxinia prior to end-Permian main extinction at Xiaojiaba section, Sichuan Province, South China  

Science.gov (United States)

Redox conditions in the global ocean prior to, during, and following the end-Permian mass extinction at 252.28 Ma remain contentious. Previous studies in western Australia, South China, and East Greenland have shown that photic-zone euxinia was present at least intermittently from the early Changhsingian through the Dienerian1-3. Here we report a study of organic carbon isotopes, pyrite sulfur isotopes, TOC, pyritic sulfur content, REE, and major and trace elements from the Upper Permian Xiaojiaba section in the Chaotian district of Guangyuan City, Sichuan Province, China. During the Permian-Triassic transition, this section was located on the northwestern margin of the South China Block, facing the Paleo-Tethys Ocean. Our results indicate that suboxic conditions prevailed during the Wuchiapingian and suboxic to anoxic conditions with several pulses of euxinia during the Changhsingian. ?13Corg values are mostly -28‰ to -26‰ but show three positive excursions (to -22‰) prior to the end-Permian mass extinction horizon. These positive excursions are associated with higher Spy concentrations (to ~1%). ?34Spy values are variable (from -41‰ to +5‰) but show a sharp negative excursion in the late Changhsingian (to -43.4‰) that coincided with the most positive ?13Corg values. This horizon is also associated with increases in Eu/Eu*, Baxs, ?REE, Si, and redox-sensitive metals such as V. These patterns reflect linkage of the C and S cycles during the latest Permian, possibly in response to redox controls. The observed positive excursions in ?13Corg may be due to organic inputs from green sulfur bacteria, which exhibit a smaller photosynthetic fractionation (-12.5‰4) than eukaryotic algae. The pronounced negative excursion of ?34Spy corresponds to a sulfate-sulfide S isotope fractionation of about -60‰, suggesting a large flux of syngenetic framboidal pyrite, which would be indicative of euxinic water-column conditions. We infer that the euxinia prior to the main extinction horizon may have been caused by oceanic oxygen-minimum zone expansion and upward movement of the chemocline5. The coupled increases in Eu/Eu* and Baxs may record hydrothermal influence, possibly accompanied by increased ocean acidity and high seawater temperatures. Collectively, our results document major changes in seawater chemistry during the Changhsingian prior to the main end-Permian crisis.

Wei, H.; Algeo, T. J.; Chen, D.; Yu, H.

2013-12-01

336

Episodic euxinia in the Changhsingian (late Permian) of South China: Evidence from framboidal pyrite and geochemical data  

Science.gov (United States)

A multiproxy study of a new Upper Permian-Lower Triassic section (Xiaojiaba) in Sichuan Province, China, documents large changes in marine productivity, redox conditions and detrital input prior to the latest Permian mass extinction. Marine productivity, as proxied by total organic carbon content (TOC), biogenic SiO2, and excess barium, displays a long-term decline through most of the Changhsingian stage (late late Permian), culminating in very low values around the Permian-Triassic boundary. Concurrently, redox proxies including pyrite framboid, ?34Spy, Moauth and Uauth, and Corg/P document a shift from suboxic to dysoxic/oxic conditions that was interrupted by several episodes of benthic euxinia, and detrital siliciclastic proxies (Al, Hf, Nb, and REEs) suggest an increased flux of weathered material from land areas. The long-term changes in productivity, redox conditions, and terrigenous detrital fluxes were probably caused by a regional sea-level fall across the South China Craton. On the other hand, the brief euxinic episodes occurring during the late Permian had oceanographic causes, probably related to the transient upward expansion of the chemocline at the top of the oceanic oxygen-minimum zone. These euxinic episodes may have been harbingers of the more widespread anoxia that developed concurrently with the latest Permian mass extinction and that may have played a major role in triggering the largest biotic crisis of the Phanerozoic.

Wei, Hengye; Algeo, Thomas J.; Yu, Hao; Wang, Jiangguo; Guo, Chuan; Shi, Guo

2015-04-01

337

Origin of Permian gabbroic intrusions in the southern margin of the Altai Orogenic belt: A possible link to the Permian Tarim mantle plume?  

Science.gov (United States)

Zircon U-Pb dating and Hf isotopic compositions, whole-rock and mineral geochemistry, as well as field and petrographic observations, are reported for the Permian gabbroic intrusions in the southern margin of the Altai orogenic belt. Similar zircon ages (~ 280 Ma) of these intrusions to that of the Permian Tarim mantle plume suggest a possible link to the Tarim plume. Olivine grains from the intrusions have Fo contents ranging from 69 to 81 and NiO from 0.05 to 0.21 wt.%, indicating the crystallization from evolved mafic magmas. Clinopyroxene grains from the intrusions have 0.3 to 1.5 wt.% TiO2 and display a rift- to arc-like affinity. The intrusions are tholeiitic and have slightly LREE-depleted to LREE-enriched chondrite-normalized rare earth element (REE) patterns. Zircons from the intrusions have ?Hf(t) values higher than + 8.0, whereas the whole-rock ?Nd(t) values range from + 2.7 to + 7.0. Rocks from the intrusions have Nb/La of 0.2 to 0.8, consistent with the derivation from a depleted sub-lithospheric mantle with variable degrees of crustal contamination. The presence of primary hornblende and/or biotite in the rocks indicates metasomatism by slab-derived fluids/melts in the mantle source. We propose that upwelling of asthenospheric mantle in the Permian Tarim mantle plume along the Irtish suture zone, resulted in partial melting of the sub-continental lithospheric mantle. Based on a comparison between the Ni-Cu sulfide-bearing Kalatongke complex and un-mineralized intrusions, we suggest that Ni-Cu sulfide mineralized intrusions in the Altai orogenic belt are characterized by the enrichments of LREEs and LILEs and by the presence of primary water-bearing minerals.

Zhang, Chuan-Lin; Zou, Hai-Bo; Yao, Chun-Yan; Dong, Yong-Guan

2014-09-01

338

Isotopic evidence for water-column denitrification and sulfate reduction at the end-Guadalupian (Middle Permian)  

Science.gov (United States)

The total nitrogen and pyrite sulfur isotopic compositions of the Guadalupian-Lopingian (Middle-Upper Permian) shelf carbonates are analyzed at Chaotian in northern Sichuan, South China, to clarify the environmental changes in the relatively deep disphotic zone (generally deeper than 150 m) in the ocean at the end-Guadalupian, focusing on the possible relationships with the deep-sea oxygen depletion and the shallow-sea extinction. At Chaotian, the Guadalupian Maokou Formation and the Early Lopingian Wujiaping Formation are primarily composed of bioclastic limestone of shallow-water facies, although the topmost part of the Maokou Formation (ca. 11 m thick) is composed of bedded black mudstone and chert that was deposited on the disphotic slope/basin under anoxic conditions. Substantially high ?15N values of total nitrogen (up to + 14‰) in the topmost Maokou Formation of the deep-water facies indicate water-mass denitrification. In the same disphotic interval, the consistently low ?34S values of pyrite (ca. - 37‰) suggest sulfate reduction in the sulfate-rich water column. The new nitrogen and sulfur isotopic records at Chaotian indicate the enhanced anaerobic respiration in the oxygen-depleted disphotic zone in the Late Guadalupian in northwestern South China. The active water-column sulfate reduction likely resulted in the emergence of a sulfidic deep-water mass on the disphotic slope/basin, which is supported by the high proportions of pyrite Fe to highly reactive Fe in the rocks shown using 57Fe Mössbauer spectroscopy. The anaerobic respiration in the disphotic zone at the end-Guadalupian may have been enhanced by an expansion of the oxygen minimum zone (OMZ) caused by the increased primary productivity in the surface oceans; the OMZ expansion may have corresponded to the onset of prolonged oxygen depletion in the deep sea. The clear stratigraphic relationship at Chaotian shows the emergence of the sulfidic deep-waters preceding the extinction, implying that the upwelling of the sulfidic deep-water from the previously overlooked disphotic zone to the shallow shelves along the continental margin may have acted as a stress to the shallow-marine biota.

Saitoh, Masafumi; Ueno, Yuichiro; Isozaki, Yukio; Nishizawa, Manabu; Shozugawa, Katsumi; Kawamura, Tetsuya; Yao, Jianxin; Ji, Zhansheng; Takai, Ken; Yoshida, Naohiro; Matsuo, Motoyuki

2014-12-01

339

A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom  

Energy Technology Data Exchange (ETDEWEB)

This report presents the results of a small-scale pilot study of the mineralogy and alteration characteristics of unusual sheet-like native copper occurring together with uraniferous and vanadiferous concretions in mudstones and siltstones of the Permian Littleham Mudstone Formation, at Littleham Cove, south Devon, England. The host mudstones and siltstones are smectitic and have been compacted through deep Mesozoic burial. The occurrence of native copper within these rocks represents a natural analogue for the long-term behaviour of copper canisters, sealed in a compacted clay (bentonite) backfill, that will be used for the deep geological disposal of high-level radioactive waste by the SKB. The study was undertaken by the British Geological Survey (BGS) on behalf of SKB between November 1999 and June 2000. The study was based primarily on archived reference material collected by the BGS during regional geological and mineralogical surveys of the area in the 1970's and 1980's. However, a brief visit was made to Littleham Cove in January 2000 to try to examine the native copper in situ and to collect additional material. Unfortunately, recent landslips and mudflows obscured much of the outcrop, and only one new sample of native copper could be collected. The native copper occurs as thin plates, up to 160 mm in diameter, which occur parallel to bedding in the Permian Littleham Mudstone Formation at Littleham Cove (near Budleigh Salterton) in south Devon. Each plate is made up of composite stacks of individual thin copper sheets each 1-2 mm thick. The copper is very pure (>99.4% Cu) but is accompanied by minor amounts of native silver (also pure - >99%) which occurs as small inclusions within the native copper. Detailed mineralogical and petrological studies of the native copper sheets, using optical petrography, backscattered scanning electron microscopy, X-ray diffraction analysis and electron probe microanalytical techniques, reveal a complex history of mineralisation and alteration that can be related to the burial and diagenetic history of the Permian strata. The native copper mineralisation exhibits close temporal association with the formation of uraniferous and vanadiferous concretions (known as 'fish-eyes') in the same rocks. Petrographical relationships indicate that both the copper and the 'fish-eye' concretions formed during burial diagenesis but before the maximum compaction of the host mudstone and siltstone. The regional burial history Wessex Basin, indicates that the maximum compaction of the Permian strata would have been achieved by at least the end of the Lower Jurassic (possibly even in the Triassic). Therefore, the native copper mineralisation is older than 176 Ma. The native copper sheets display a complex sequence of alteration and subsequent mineral growth of minerals on their surfaces. The earliest alteration was to copper oxides - principally cuprite with minor tenorite, indicating a change to more oxidising groundwater conditions. The dissolution of native silver and the growth of fringes of copper arsenides followed this. Nickel arsenides and chalcocite, associated with the precipitation of uranium silicates occurred in the later stages of alteration. This suggests a return to a more reducing pore water environment. Again, petrographical relationships indicate that this alteration and subsequent mineralisation is geologically old (i.e. Lower Jurassic or older). Secondary malachite, intimately intergrown copper sulphate and copper oxides, copper chloride, copper-uranium arsenate and uranium vanadates have formed as late-stage alteration products of the native copper and earlier diagenetic cuprite, chalcocite, copper-nickel arsenide and uranium silicate alteration and mineralisation. This latest stage alteration is most probably attributable to near-surface weathering processes. Although the native copper is affected by corrosion, the study has shown that a significant proportion (30-80% of the original thickness) of the copper sheets has been preserved in the s

Milodowski, A.E.; Styles, M.T.; Hards, V.L. [Natural Environment Research Council (United Kingdom). British Geological Survey

2000-08-01

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A natural analogue for copper waste canisters: The copper-uranium mineralised concretions in the Permian mudrocks of south Devon, United Kingdom  

International Nuclear Information System (INIS)

This report presents the results of a small-scale pilot study of the mineralogy and alteration characteristics of unusual sheet-like native copper occurring together with uraniferous and vanadiferous concretions in mudstones and siltstones of the Permian Littleham Mudstone Formation, at Littleham Cove, south Devon, England. The host mudstones and siltstones are smectitic and have been compacted through deep Mesozoic burial. The occurrence of native copper within these rocks represents a natural analogue for the long-term behaviour of copper canisters, sealed in a compacted clay (bentonite) backfill, that will be used for the deep geological disposal of high-level radioactive waste by the SKB. The study was undertaken by the British Geological Survey (BGS) on behalf of SKB between November 1999 and June 2000. The study was based primarily on archived reference material collected by the BGS during regional geological and mineralogical surveys of the area in the 1970's and 1980's. However, a brief visit was made to Littleham Cove in January 2000 to try to examine the native copper in situ and to collect additional material. Unfortunately, recent landslips and mudflows obscured much of the outcrop, and only one new sample of native copper could be collected. The native copper occurs as thin plates, up to 160 mm in diameter, which occur parallel to bedding in the Permian Littleham Mudstone Formation at Littleham Cove (near Budleigh Salterton) in south Devon. Each plate is made up of composite stacks of individual thin copper sheets each 1-2 mm thick. The copper is very pure (>99.4% Cu) but is accompanied by minor amounts of native silver (also pure - >99%) which occurs as small inclusions within the native copper. Detailed mineralogical and petrological studies of the native copper sheets, using optical petrography, backscattered scanning electron microscopy, X-ray diffraction analysis and electron probe microanalytical techniques, reveal a complex history of mineralisation and alteration that can be related to the burial and diagenetic history of the Permian strata. The native copper mineralisation exhibits close temporal association with the formation of uraniferous and vanadiferous concretions (known as 'fish-eyes') in the same rocks. Petrographical relationships indicate that both the copper and the 'fish-eye' concretions formed during burial diagenesis but before the maximum compaction of the host mudstone and siltstone. The regional burial history Wessex Basin, indicates that the maximum compaction of the Permian strata would have been achieved by at least the end of the Lower Jurassic (possibly even in the Triassic). Therefore, the native copper mineralisation is older than 176 Ma. The native copper sheets display a complex sequence of alteration and subsequent mineral growth of minerals on their surfaces. The earliest alteration was to copper oxides - principally cuprite with minor tenorite, indicating a change to more oxidising groundwater conditions. The dissolution of native silver and the growth of fringes of copper arsenides followed this. Nickel arsenides and chalcocite, associated with the precipitation of uranium silicates occurred in the later stages of alteration. This suggests a return to a more reducing pore water environment. Again, petrographical relationships indicate that this alteration and subsequent mineralisation is geologically old (i.e. Lower Jurassic or older). Secondary malachite, intimately intergrown copper sulphate and copper oxides, copper chloride, copper-uranium arsenate and uranium vanadates have formed as late-stage alteration products of the native copper and earlier diagenetic cuprite, chalcocite, copper-nickel arsenide and uranium silicate alteration and mineralisation. This latest stage alteration is most probably attributable to near-surface weathering processes. Although the native copper is affected by corrosion, the study has shown that a significant proportion (30-80% of the original thickness) of the copper sheets has been preserved in the saturated compacted clay environment

341

Tectonic and climatic controls on sedimentation during deposition of the Sinakumbe Group and Karoo Supergroup in the mid-Zambezi Valley Basin, southern Zambia  

Energy Technology Data Exchange (ETDEWEB)

Sediments of the Ordovician to Devonian Sinakumbe Group (about 210 m thick) and overlying Upper Carboniferous to Lower Jurassic Karoo Supergroup (about 4.5 km thick) were deposited in the mid-Zambezi Rift Valley Basin, southern Zambia. The Sinakumbe-Karoo succession represents deposition in a extensional fault-controlled basin of half-graben type. The basin-fill succession incorporates two major fining-upward cycles that resulted from major tectonic events, one event beginning with Sinakumbe Group sedimentation, possibly as early as Ordovician times, and the other beginning with Upper Karoo Group sedimentation near the Permo-Triassic boundary. Minor tectonic pulses occurred during deposition of the two major cycles. Glaciation followed by deglaciation resulted in glaciofluvial an