The Werra cyclotheme (Upper Permian, Fore-Sudetic Monocline, Poland): Insights into fluctuations of the sedimentary environment from organic geochemical studies

The Longtan Formation of the Upper Permian in the Sichuan Basin has become a significant target for shale gas exploration in recent years. Multiple methods, including outcrop observations, thin sections, total organic matter content, X-ray diffraction and scanning electron microscopy were used to investigate the mineralogy, shale lithofacies assemblages and their relationships with the deposition environment. The mineral composition of the Longtan Formation has strong mineral heterogeneity. The TOC values of the Longtan Formation have a wide distribution range from 0.07% to 74.67% with an average value of 5.73%. Four types of shale lithofacies assemblages of the Longtan Formation could be distinguished, as clayey mudstone (CLS), carbonaceous shale (CAS), siliceous shale (SS) and mixed shale (MS) on the basis of mineral compositions. The TOC values of various types of shale lithofacies assemblages in the Longtan Formation varied widely. The shore swamp of the Longtan Formation is most influenced by the terrestrial input and mainly develops CLS and MS. The tidal flat is influenced by the terrestrial input and can also deposit carbonate minerals, developing CLS, CAS and MS. The shallow water melanged accumulation shelf develops CAS and MS, dominated by clay and carbonate minerals. The deep water miscible shelf develops CLS and SS, whose mineral composition is similar to that of the shore swamp, but the quartz minerals are mainly formed by chemical and biological reactions, which are related to the Permian global chert event. The depositional environment of the Longtan Formation controls the shale mineral assemblage of the Longtan Formation and also influences the TOC content.

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AROMATIC STEROIDS BIOMARKERS APPLIED TO HIGH RESOLUTION STRATIGRAPHY: IRATI FORMATION, SOUTHERN OF PARANÁ BASIN, BRAZIL

Journal of Sedimentary Environments ◽

10.12957/jse.2017.32495 ◽

2018 ◽

Vol 2 (4) ◽

pp. 174-182 ◽

Cited By ~ 1

Author(s):

Lina Liliana Osorio ◽

Darlly Erika Silva dos Reis ◽

René Rodrigues

Keyword(s):

High Resolution ◽

Sedimentary Environment ◽

Water System ◽

Sedimentary Basins ◽

Lower Permian ◽

Irati Formation ◽

Organic Matter Type ◽

Living Organisms ◽

Rock Eval ◽

Geochemical Studies

The use of aromatic steroids in geochemical studies is almost absent in Brazilian sedimentary basins. For this reason, it is intended to test the application of these compounds in high-resolution stratigraphy in the relatively well known Lower Permian Irati Formation. The Irati Formation is about 40 meters thick. It is thermally immature, and comprise two lithological distinct members: the lower siliciclastic Taquaral Member and the upper calcareous-siliciclastic Assistência Member. Based on the whole rock data, mostly TOC, total sulfur, Rock-Eval pyrolysis and alkanes biomarkers, was possible to split the Irati Formation into seven chemostratigraphic units, named from A to C in the Taquaral Member and from D to G in the Assistência Member. Each of these units represents: distinct inputs of land derived organic matter type (chemostratigraphic units C and F) and/or; the response of living organisms to salinity changing of the water system (chemostratigraphic unit D) and; anoxia (chemostratigraphic unit E) during sedimentation. The methodology applied in this work can be used in other sedimentary basins but considering the lithology and sedimentary environment particularities.

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Geological and Geochemical Characteristics of Low-Arsenic Groundwater in The Karamay Area Between Two High Arsenic Areas of Xinjiang, China

10.21203/rs.3.rs-498060/v1 ◽

2021 ◽

Author(s):

Qiao Li ◽

Hongfei Tao ◽

Mahemujiang Aihemaiti ◽

Youwei Jiang ◽

Wenxin Yang ◽

...

Keyword(s):

River Basin ◽

Sedimentary Environment ◽

Water Injection ◽

Arsenic Concentration ◽

Junggar Basin ◽

High Energy ◽

Geochemical Characteristics ◽

Upper Permian ◽

Arsenic Content ◽

River Diversion

Abstract The groundwater of several regions in Xinjiang, China, including the Kuitun and the Manas River Basins in the Junggar Basin, is heavily polluted with arsenic. However, the arsenic content of the groundwater of the Karamay area located within the Junggar Basin is relatively low and below the recommended drinking water limit. In our study, we analyze the factors that result in this anomaly. The geological and geochemical characteristics of the water-bearing system in this area were investigated by analyzing water samples, carrying out hydrogeological surveys, and statistical techniques. Since the Carboniferous, the geological development and subsequent structural evolution resulted in a lower arsenic concentration in groundwater of the Karamay region than that of the Kuitun River Basin and the Manasi River Basin. The missing high-energy sedimentary environment in the Middle-Upper Permian and the composition of sediments controlled the characteristics of the multi-layer aquifer in this area. We find that the lack of arsenic sources, neutral and slightly alkaline environment, water injection to extract oil, and the Irtysh River Diversion to Urumqi Project, result in better groundwater quality and lower arsenic pollution in this area.

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LOWER TRIASSIC VOLCANOGENIC FORMATIONS OF THE PRONCHISHCHEV RIDGE (NORTH OF CENTRAL SIBERIA)

Interexpo GEO-Siberia ◽

10.33764/2618-981x-2021-2-1-201-206 ◽

2021 ◽

Vol 2 (1) ◽

pp. 201-206

Author(s):

Aleksei Yu. Popov ◽

Evgeny S. Sobolev ◽

Artem Ya. Shevko ◽

Andrei V. Yadrenkin

Keyword(s):

Sedimentary Rocks ◽

Spatial Relationship ◽

Lower Triassic ◽

Middle Part ◽

Upper Permian ◽

Central Siberia ◽

Supply Channel ◽

Single Complex ◽

Geochemical Studies ◽

Different Parts

The volcanogenic formations of the middle part of the Pronchishchev ridge are considered. Based on new data from the lithological, petrographic, geochemical studies of igneous and volcanogenic sedimentary rocks and stratigraphic studies of the Upper Permian-Lower Triassic terrigenous strata that enclose them, a model of their spatial relationship is proposed. It is shown that the dolerite body and the adjacent tuff breccia in the field of development of Upper Permian rocks as well as tuffite gravelites in the field of Lower Triassic rocks are a single complex of formations of different parts of the diatreme. The time of implantation of the diatreme is defined as the beginning of the Late Olenek. The wide development of vent facies dolerites in the diatreme may indicate the repeated activation of the supply channel.

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Sedimentary environment of organic-rich shale in the Upper Permian Longtan Formation in Qinglong area, western Guizhou, China

China Geology ◽

10.31035/cg2018086 ◽

2019 ◽

Vol 2 (1) ◽

pp. 108-109 ◽

Cited By ~ 2

Author(s):

Rong Chen ◽

◽

Kun Yuan ◽

Zi-ya Zhang ◽

Qiu-feng Xu

Keyword(s):

Sedimentary Environment ◽

Upper Permian ◽

Western Guizhou

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Geochemical Characteristics and Sedimentary Environment of the Upper Permian Longtan Coal Series Shale in Western Guizhou Province, South China

Geofluids ◽

10.1155/2021/9755861 ◽

2021 ◽

Vol 2021 ◽

pp. 1-11

Author(s):

Lingyun Zhao ◽

Peiming Zhou ◽

Yi Lou ◽

Youzhou Zhao ◽

Wei Liu ◽

...

Keyword(s):

Organic Matter ◽

South China ◽

Shale Gas ◽

Vitrinite Reflectance ◽

Sedimentary Environment ◽

Guizhou Province ◽

Upper Permian ◽

Yangtze Platform ◽

Western Guizhou ◽

Exploration And Development

China’s marine-continental transitional facies shale gas resources are abundant with shale gas resources of about 19.8 trillion cubic meters, while the exploration and development of these shale gas resources are still in the initial stage. The Upper Permian Longtan coal series shale is one of the most important transitional shales in the Yangtze platform, China. In this study, the comprehensive methods of mineralogy and organic geochemistry are used to discuss the characteristic of organic matter and sedimentary environment of the Longtan coal series shale in western Guizhou Province, South China. The results show that (1) the total organic carbon (TOC) content of this shale ranges in 0.6%-28.21%, mainly in 3%-12%, indicating a “good-excellent” hydrocarbon source rock, and its vitrinite reflectance ( R o ) ranges from 1.48% to 2.93%, indicating a high-overmature organic matter; (2) the organic matter in this shale is multiorigin, and most of them come from the terrestrial higher plant while the rest come from the plankton; (3) type index (TI) of organic matter is from -65 to 41, indicating most of the kerogens which are II1-III types; and (4) the sedimentary environment of this shale is dominated by suboxic-anoxic fresh water environment, which provides a favorable condition for the preservation of organic matter. In addition, the warm and humid climate during the Late Permian in the Yangtze platform promotes plant growth, and as a result, the Longtan coal series shale is rich in organic matter and has great potential of shale gas exploration and development.

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