Geochemical characteristics of Late Permian sediments in the Dalong Formation of the Shangsi Section, Northwest Sichuan Basin in South China: Implications for organic carbon-rich siliceous rocks formation

Chen, Hui; Xie, Xinong; Hu, Chaoyong; Huang, Junhua; Li, Hongjing

doi:10.1016/j.gexplo.2011.06.011

Cited by 30 publications

(23 citation statements)

References 47 publications

(53 reference statements)

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“…The conformably overlying Dalong Formation (beds 11–27) is composed of medium-bedded bioturbated siliceous limestone, interbedded with thinly bedded organic-rich limestone and shale, with total organic carbon (TOC) content up to 14% (ref. 38). The depositional environments of the Dalong Formation evolved from platform margin/upper slope, to outer shelf, and to intrashelf basin15.…”

Section: Methodsmentioning

confidence: 99%

Time-calibrated Milankovitch cycles for the late Permian

et al. 2013

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An important innovation in the geosciences is the astronomical time scale. The astronomical time scale is based on the Milankovitch-forced stratigraphy that has been calibrated to astronomical models of paleoclimate forcing; it is defined for much of Cenozoic–Mesozoic. For the Palaeozoic era, however, astronomical forcing has not been widely explored because of lack of high-precision geochronology or astronomical modelling. Here we report Milankovitch cycles from late Permian (Lopingian) strata at Meishan and Shangsi, South China, time calibrated by recent high-precision U–Pb dating. The evidence extends empirical knowledge of Earth’s astronomical parameters before 250 million years ago. Observed obliquity and precession terms support a 22-h length-of-day. The reconstructed astronomical time scale indicates a 7.793-million year duration for the Lopingian epoch, when strong 405-kyr cycles constrain astronomical modelling. This is the first significant advance in defining the Palaeozoic astronomical time scale, anchored to absolute time, bridging the Palaeozoic–Mesozoic transition.

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Section: Methodsmentioning

confidence: 99%

Time-calibrated Milankovitch cycles for the late Permian

et al. 2013

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“…The depositional environment of the Maokou Formation bedded chert is internal depressions in the platform or slope; the deposition depth is deeper than that of nodular chert and below the CCD (CaCO 3 compensation depth) interface (Table ; Figure b); therefore, silica from upwelling and hydrothermal silica mixed, and bedded chert could be deposited directly. Previous studies have shown that hydrothermal activity led to high palaeoproductivity in the Dalong Formation (Chen et al, ). Lin et al () also thought that the increase in silica content in seawater could promote siliceous organisms, such as radiolarians and sponges.…”

Section: Discussionmentioning

confidence: 97%

“…The source of silica is a key issue in studying the origin and depositional environment of chert. Previous studies have shown that multiple sources exist for the Permian cherts of South China, including hydrothermal sources (Chen et al, ; Cheng et al, ; Lin et al, ; Qiu & Wang, ; Yu et al, ; Zhou et al, ), biogenetic sources (Chen et al, ; Takebe et al, ; Yang, ), terrestrial sources (Huang et al, ), and upwelling (Chen et al, ; Lin, Yu, Gao, & Hong, ; Zhou et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…In geological history, Permian chert deposits were particularly developed during a global event known as the Permian Chert Event (PCE; Beauchamp & Baud, 2002;Murchey & Jones, 1992). Permian cherts are widely distributed in the Upper Yangtze region in the form of nodular and bedded cherts, and numerous studies have been undertaken in the area (Chen, Xie, Hu, Huang, & Li, 2012;Cheng, Li, Zhao, & Yan, 2015;Fang, Zhou, Yao, & Liu, 2017;Li et al, 2009;Li, Liu, & Liu, 2010;Lin, Chen, & Zhu, 2010a;Lin, Chen, & Zhu, 2010b;Lin, Yu, Gao, & Hong, 2018;Takebe et al, 2007;Yu, Lin, Ren, Chen, & Gao, 2016;Zhou, He, Luo, & Xu, 2012). A detailed study on the origin of Permian cherts contributes to the reconstruction of the Permian palaeoenvironment.…”

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confidence: 99%

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Geochemical features of the Middle–Upper Permian cherts and implications for origin, depositional environment in the Sichuan Basin, SW China

Lin

Deng

et al. 2019

Geological Journal

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Permian cherts are widely developed in the Sichuan Basin and carry significant information about the evolution of the sedimentary environment. To understand the origins and depositional environments of the Middle–Upper Permian cherts in the Sichuan Basin, we studied the lithological and geochemical characteristics of the cherts. Based on field observations and thin section analysis, Permian cherts occur mainly in the form of nodular and bedded cherts. Nodular cherts present irregular lumps or tuberculous patterns and are composed of mostly cryptocrystalline and microcrystalline quartz with small amounts of carbonate mineral. Bedded cherts contain organic matter, and radiolarians can be found in Late Permian bedded cherts. The geochemical analysis of Permian cherts shows that the chert sources are complex; nodular Middle Permian cherts show hydrothermal and upwelling influences, with less terrestrial influence. Nodular chert is the product of diagenetic metasomatism, formed when silica‐rich fluids entered carbonate that was partially dissolved by H+ released from the oxidation of H2S. Bedded cherts of the Maokou Formation have the same source as nodular cherts but were deposited in a slope or depression of the platform, which was below the CaCO3 compensation depth (CCD) interface, so that bedded chert could be deposited directly. Bedded cherts of the Wujiaping Formation show influence from hydrothermal, biogenetic, and terrestrial sources and were deposited in a deeper water environment, such as basin or the bottom of slope. The Permian cherts in the Sichuan Basin are the response to the global Permian Chert Event (PCE), which was closely related to the Late Palaeozoic Ice Age (LPIA) and the global active volcanism during the Permian.

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“…The plurality of the siliceous rocks is enclosed within carbonate facies (Knauth, ). The chert and chertification were recognized from different palaeoenvironments and several ages; for example, they were observed in the Cambrian of China (Bingsong, Hailiang, Jianqiang, Xingwu, & Changsong, ), Ordovician of the United States (Gao & Land, ), Devonian of south China (Chen, Qing, Yan, & Li, ), Permian of south China (Chen, Xie, Hu, Huang, & Li, ), Middle Triassic of Poland (Kwiatkowski, ), Late Jurassic of south Spain (Bustillo & Ruiz‐Ortiz, ), Campanian–Maastrichtian of Denmark (Madsen & Stemmerik, ), Eocene of United Arab Emirates (Whittle & Alsharhan, ), and the Miocene Monterey Formation of the United States (Behl, ).…”

Section: Introductionmentioning

confidence: 99%

Origin of chert within the Turonian carbonates of Abu Roash Formation, Abu Roash area, Egypt: Field, petrographic, and geochemical perspectives

Hussein

El‐Rahman

2019

Geological Journal

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This paper tries to elucidate the origin of the siliceous rocks (cherts) within the Turonian flint‐bearing chalky limestone member of Abu Roash Formation, Abu Roash area, north Western Desert, Egypt. Understanding the formation mechanism of the studied chert was gained through field and petrographic investigations, supplemented by geochemical analyses of both cherts and host Turonian carbonates. The field observations reveal that the chert is found in two forms: banded and nodular. The microscopic investigation determined that the cherts exhibit two types of silica: replacive silica (cryptocrystalline and microcrystalline quartz) and silica cement (length‐fast chalcedony and megaquartz). The chert texture corroborates that the examined authigenic silica was formed diagenetically by the replacement and void‐filling of the host carbonate rocks. The silica was most likely derived from the biogenic opal‐A of the siliceous radiolarian tests. The silica‐phase transformation started with the dissolution of the biogenic opal‐A and precipitation of opal‐CT. Subsequently, opal‐CT was recrystallized into crypto‐ and microquartz at low pH and high temperature. The length‐fast chalcedony and megaquartz occur later as infill to the cavities and pore spaces. The formation of chert is interpreted to be a result of mixing marine–meteoric waters. The effect of the freshwater diagenesis on carbonates is manifested by the dissolution of the allochems, precipitation of granular, drusy, and blocky calcite (meteoric cements), aggrading neomorphism of matrix, and calcitization of the skeletal particles. Geochemical analyses of the host carbonates indicate nearly flat REE patterns and absence of a negative Ce anomaly. This confirms the deviation from the typical seawater and supports the effect of phreatic meteoric water in the chert formation. The paragenetic relationships reveal that the chertification process was performed after dolomitization and before the carbonate meteoric cementation.

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Geochemical characteristics of Late Permian sediments in the Dalong Formation of the Shangsi Section, Northwest Sichuan Basin in South China: Implications for organic carbon-rich siliceous rocks formation

Cited by 30 publications

References 47 publications

Time-calibrated Milankovitch cycles for the late Permian

Time-calibrated Milankovitch cycles for the late Permian

Geochemical features of the Middle–Upper Permian cherts and implications for origin, depositional environment in the Sichuan Basin, SW China

Origin of chert within the Turonian carbonates of Abu Roash Formation, Abu Roash area, Egypt: Field, petrographic, and geochemical perspectives

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