The appearance of an oxygen-depleted condition on the Capitanian disphotic slope/basin in South China: Middle–Upper Permian stratigraphy at Chaotian in northern Sichuan

Saitoh, Masafumi; Isozaki, Yukio; Yao, Jianxin; Ji, Zhongqiang; Ueno, Yuichiro; Yoshida, Naohiro

doi:10.1016/j.gloplacha.2012.01.002

Cited by 54 publications

(53 citation statements)

References 55 publications

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“…In our previous studies, we identified evidence for anoxia and for water-mass denitrification and sulfate reduction on the relatively deep slope/basin along the continental margin, prior to the extinction ( Fig. 1c; Isozaki et al 2008;Saitoh et al 2013aSaitoh et al , 2013bSaitoh et al , 2014a. Here, we report on the occurrence of anomalous carbonate crystals in a characteristic interval of deep-water facies in the uppermost Guadalupian at Chaotian.…”

supporting

confidence: 56%

“…c Stratigraphy across the Guadalupian-Lopingian (Middle-Upper Permian) boundary (G-LB) at Chaotian. The sedimentary environments and sea-level changes are modified from Saitoh et al (2013a). carb.…”

Section: Methodsmentioning

confidence: 99%

“…Griesbachian, Fei. Feixianguan, P-TB Permian-Triassic boundary N 2 (aq)) in the initial seawater was 15 μmol/L based on the vertical NO 3 − profile in the modern oceans (Lam et al 2009) and on the estimated water depth of the sedimentary environment of the Mudstone Unit at Chaotian (>150 m deep) (Saitoh et al 2013a). The pH of the initial seawater was assumed to be 7.8 on the basis of the model results by Ridgwell (2005).…”

Section: Methodsmentioning

confidence: 99%

“…At Chaotian, the Permo-Triassic rocks (>300 m thick in total) include the Guadalupian Maokou Formation, the Lopingian Wujiaping and Dalong formations, and the lowermost Triassic Feixianguan Formation, in ascending order ( Fig. 1c; Isozaki et al 2004Isozaki et al , 2008Saitoh et al 2013aSaitoh et al , 2013bSaitoh et al , 2014b. The Maokou Formation, >150 m thick, consists mainly of massive dark gray bioclastic limestone with abundant shallow-marine fossils such as calcareous algae, brachiopods, and fusulines.…”

Section: Geologic Setting and Stratigraphymentioning

confidence: 99%

“…1c; Isozaki et al 2008;Saitoh et al 2013a). The Limestone Unit of the Maokou Formation,~11 m thick, is composed of bioclastic limestone with abundant shallowmarine fossils (e.g., calcareous algae, fusulines, and corals) deposited on a euphotic and oxic shelf.…”

Section: Geologic Setting and Stratigraphymentioning

confidence: 99%

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Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceans

Saitoh

Ueno

Isozaki

et al. 2015

Prog. in Earth and Planet. Sci.

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Carbonate precipitation is a major process in the global carbon cycle. It was recently proposed that authigenic carbonate (carbonate precipitated in situ at the sediment-water interface and/or within the sediment) played a major role in the carbon cycle throughout Earth's history. The carbon isotopic composition of authigenic carbonates in ancient oceans have been assumed to be significantly lower than that of dissolved inorganic carbon (DIC) in seawater, as is observed in the modern oceans. However, the δ 13 C carb values of authigenic carbonates in the past has not been analyzed in detail. Here, we report authigenic carbonates in the uppermost Guadalupian (Middle Permian) rocks at Chaotian, Sichuan, South China. Monocrystalline calcite crystals <20 mm long are common in the black mudstone/chert sequence that was deposited on a relatively deep anoxic slope/basin along the continental margin. Textures of the crystals indicate in situ precipitation on the seafloor and/or within the sediments. The calcite precipitation corresponds stratigraphically with denitrification and sulfate reduction in the anoxic deep-water mass, as indicated by previously reported nitrogen and sulfur isotope records, respectively. Relatively high δ 13C carb values of the authigenic carbonates (largely −1 ‰) compared with those of organic matter in the rocks (ca. −26 ‰) suggest that the main carbon source of the carbonates was DIC in the water column. The calcite crystals precipitated in an open system with respect to carbonate, possibly near the sediment-water interface rather than deep within the sediments. The δ 13C carb values of the carbonates were close to the δ 13 C DIC value of seawater due to mixing of 13 C-depleted remineralized organic carbon (that was released into the water column by the water-mass anaerobic respiration) with the large DIC pool in the oceans. Our results imply that δ 13 C carb values of authigenic carbonates in the anoxic oceans might have been systematically different from the values in the oxic oceans in Earth's history, controlled by the depth of the redoxcline in the water column and sediments. If our model is correct, authigenic carbonates with relatively high δ 13C carb values in the ancient anoxic oceans may have had a less substantial influence on the bulk δ 13C carb values in geologic records than has been previously suggested.

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supporting

confidence: 56%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Geologic Setting and Stratigraphymentioning

confidence: 99%

Section: Geologic Setting and Stratigraphymentioning

confidence: 99%

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Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceans

Saitoh

Ueno

Isozaki

et al. 2015

Prog. in Earth and Planet. Sci.

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End-Paleozoic Mass Extinction: Hierarchy of Causes and a New Cosmoclimatological Perspective for the Largest Crisis

Isozaki

2019

Astrobiology

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Origin, formation, and transformation of different forms of silica in Xuanwei Formation coal, China, and its’ emerging environmental problem

Chen,

Shi,

et al. 2023

Environ Sci Pollut Res

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The study on the origin of quartz and silica in Xuanwei Formation coal in Northwest Yunnan, China, is helpful to understand the relationship between quartz and silica and the high incidence of lung cancer from the root. To address these questions, the mineralogy and microscopic studies of silica in Xuanwei Formation coal were performed.The following results were obtained: (1) silica in the late Permian Xuanwei Formation coal seams originated from detrital input, early diagenesis, and late diagenesis. (2) A more signi cant contribution comes from early diagenesis, which contains abundant authigenic quartz and amorphous silica. (3) Quartz and silica from inorganic silicon are more symbiotic with kaolinite and from biogenic silicon with chamosite. (4) Three silica polymorphs in coal samples have been identi ed: opal-A (amorphous silica), opal-CT/-C (cristobalite/tridymite), and α quartz. ( 5) Opal-A is ubiquitous, while opal-CT/-C and α quartz are rare. (5) Opal-A is an amorphous and nontoxic ordinary silica. Highlights 1. Silica originated from detrital input, early diagenesis, and late diagenesis.2. Early diagenetic silica contains authigenic quartz and amorphous silica.3. Inorganic silica is more symbiotic with kaolinite and biogenic silica with chamosite. 4. Opal-A is ubiquitous, while opal-CT/-C and α quartz are rare. 5. Opal-A is an amorphous and nontoxic ordinary silica.

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The appearance of an oxygen-depleted condition on the Capitanian disphotic slope/basin in South China: Middle–Upper Permian stratigraphy at Chaotian in northern Sichuan

Cited by 54 publications

References 55 publications

Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceans

Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceans

End-Paleozoic Mass Extinction: Hierarchy of Causes and a New Cosmoclimatological Perspective for the Largest Crisis

Origin, formation, and transformation of different forms of silica in Xuanwei Formation coal, China, and its’ emerging environmental problem

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