Latest Permian to Middle Triassic redox condition variations in ramp settings, South China: Pyrite framboid evidence

Huang, Yuangeng; Chen, Zhong‐Qiang; Wignall, Paul B.; Zhao, Laishi

doi:10.1130/b31458.1

Cited by 97 publications

(62 citation statements)

References 83 publications

(2 reference statements)

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“…Cerium anomalies in their conodont fossils, which reflect seawater values, indicated a dysoxic–anoxic event in the lower interval of the Paragondolella bulgarica conodont zone. In addition, several redox cycles from oxic to euxinic conditions during the middle Anisian (Bithynian–Pelsonian) were recognized based on the pyrite morphometrics from South China (Huang et al, ). Our data suggest that the study section records significant anoxic conditions in deep seafloor facies at the level of the first occurrence of conodont P. bulgarica.…”

Section: Discussionmentioning

confidence: 99%

“…Cerium anomalies in their conodont fossils, which reflect seawater values, indicated a dysoxic-anoxic event in the lower interval of the Paragondolella bulgarica conodont zone. In addition, several redox cycles from oxic to euxinic conditions during the middle Anisian (Bithynian-Pelsonian) were recognized based on the pyrite morphometrics from South China (Huang et al, 2017). Our data suggest that the study section records significant anoxic conditions in deep Box model calculations of strontium isotopic compositions ( 87 Sr/ 86 Sr ratios) in the conodont fossils, whose balance is controlled mainly by riverine input via continental weathering and mantle input through hydrothermal circulation at mid-ocean ridges, predicted that continental weathering of the Middle Triassic (Anisian) was about 1.2 times higher than that of the Late Permian levels (Song et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Grasby, Beauchamp, Embry, & Sanei, ; Huang, Chen, Wignall, & Zhao, ; Lau et al, ; Song et al, ; Tian et al, ; Wignall et al, ) have revealed that the three major anoxic events occurred in the Early Triassic (late Changhsingian–early Dienerian, Smithian–early Spathian and middle Spathian). In addition to the Early Triassic anoxia, the early Middle Triassic (Anisian) anoxic events are recognized and discussed in Japan and South China (Fujisaki et al, ; Huang et al, ; Kubo, Isozaki, & Matsuo, ; Song et al, ; Sugitani & Mimura, ; Wignall et al, ). These studies suggest that the anoxic interval was not restricted to the PTB, but had a much longer duration, until the Anisian (~ 10 Myr of the Triassic).…”

Section: Introductionmentioning

confidence: 99%

“…Spathian). In addition to the Early Triassic anoxia, the early Middle Triassic (Anisian) anoxic events are recognized and discussed in Japan and South China (Fujisaki et al, 2016;Huang et al, 2017;Kubo, Isozaki, & Matsuo, 1996;Song et al, 2012;Sugitani & Mimura, 1998;Wignall et al, 2010). These studies suggest that the anoxic interval was not restricted to the PTB, but had a much longer duration, until the Anisian (~10 Myr of the Triassic).…”

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confidence: 99%

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Paleoenvironmental reconstruction for termination stage of Superanoxia in Middle Triassic (Anisian) sedimentary sequence of the Mino belt, central Japan

Soda

Onoue

2018

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Superanoxia across the Permian/Triassic boundary, which is a long period of oceanic anoxia from the late Middle Permian to the early Middle Triassic, has been recognized and debated well in the context of the end Permian mass extinction. However, few studies have focused on the Middle Triassic anoxia because of limited application of geochemical proxies. To reconstruct paleoenvironmental changes during the termination stage of Superanoxia, various geochemical proxies were applied to chemical compositions of the Middle Triassic (Anisian) bedded chert sequence in the Mino belt, Japan, which accumulated in a deep seafloor environment in a low‐ to mid‐latitude zone of the Panthalassa Ocean. Three anoxic events were identified by statistically robust geochemical proxies during the middle Anisian. Degrees of calibrated‐chemical weathering intensity show higher values during these anoxic events, suggesting that the intensified continental weathering was a trigger mechanism for the oceanic anoxic events in the middle Anisian. Furthermore, our data indicate that the termination of Superanoxia in the Panthalassa Ocean was associated with a gradual decrease in continental weathering rates during the middle to late Anisian.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Paleoenvironmental reconstruction for termination stage of Superanoxia in Middle Triassic (Anisian) sedimentary sequence of the Mino belt, central Japan

Soda

Onoue

2018

Island Arc

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“…The framboid mean diameters of this section vary from 4.6 to 7.3 μm, with maximum diameters range from 7.2 to 16.1 μm. Such small pyrite framboids, together with pyrite morphological features, are usually interpreted to indicate a euxinic to dysoxic condition in water columns (Y. Huang, Chen, Wignall, & Zhao, ; Lan & Chen, , ; Lan et al, ; Wilkin et al, ). Accordingly, it can be speculated that marine environments from the lower part of the studied section (i.e., Beds 4–6) to its upper part (i.e., Beds 9–13) varied gradually from the oxic to euxinic–dysoxic conditions, pacing with a general rise in sea level during the Late Ordovician revealed by sequence stratigraphical and facies analyses from the same section in the Tarim Basin (Lin et al, ).…”

Section: Discussionmentioning

confidence: 99%

Abundant microspherules from the Upper Ordovician of northern Tarim Basin, Northwest China: Origin and palaeoenvironmental implications

et al. 2018

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A continuous record of abundant microspherules, pyrite framboids, and bacterial fossils is obtained from the Upper Ordovician in the Dawangou section of northern Tarim Basin, Northwest China. Chemical and physical characteristics of these microspherules were determined using a scanning electron microscope and an energy dispersive spectrometer. Microspherules were formed as a single spherule, spherule aggregates, and drop‐like particles. Physical morphology of the spherules has no relation to its formational process. Energy dispersive spectrometry results indicate that microspherules are mainly composed of Ca, C, O, Si, Al, S, Fe, and Ti. Thus, these microspherules are further categorized into 5 major types: iron, titaniferous‐iron, siliceous, calcareous, and organic microspherules. The first 3 types of microspherules are likely of volcanic origin rather than extraterrestrial origins (i.e., impact event or cosmic dusts) or modern industrial pollutions due to their morphologies and chemical compositions. Both calcimicrospherules and organic microspherules are biogenic, and they are distributed in the lower part of the studied section (Beds 4–6), in which cephalopods, brachiopods, and bacterial fossils are also commonly present and pyrite framboids are absent. These features generally point to an oxic condition. In contrast, other microspherules are abundant in the upper part of the section (Beds 9–13), in which tiny pyrite framboids (mean diameters 4.6–7.3 μm) are rather abundant and typical of euxinic to dysoxic conditions. Both microspherule and pyrite framboid evidences indicate that the northern Tarim region became oxygen‐poor conditions, which were coupled with intensive volcanic eruptions during the Late Ordovician.

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Preservation of Permian–Triassic boundary section in the Jurassic accretionary complex of the Lake Hamana, Central Japan

2020

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We examined the lithostratigraphy and deformation structures of the accreted pelagic rocks in Lake Hamana area, Central Japan, based on a detailed field mapping and the radiolarian ages. The constructed lithostratigraphy is composed of Lopingian (Upper Permian) grey chert, black chert, black claystone with a high carbon content of 4.85-6.78 wt%, siliceous claystone, black chert, and Anisian (Middle Triassic) grey chert, in the ascending order. The symmetry in the lithostratigraphy and the change in the radiolarian ages with respect to black carbonaceous claystone are presumed to represent a deep-sea anoxic event that occurred across the Permian-Triassic (P-Tr) boundary. The P-Tr boundary black carbonaceous claystone suffered from an intense shear, resulting in blocks of siliceous claystone in the scaly black claystone matrix. In places, the sheared terrigenous rocks composed of sandstone blocks in the mudstone matrix are intercalated into the pelagic rocks, possibly representing complex mélange forming processes during the development of the Jurassic accretionary complex.

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Latest Permian to Middle Triassic redox condition variations in ramp settings, South China: Pyrite framboid evidence

Cited by 97 publications

References 83 publications

Paleoenvironmental reconstruction for termination stage of Superanoxia in Middle Triassic (Anisian) sedimentary sequence of the Mino belt, central Japan

Paleoenvironmental reconstruction for termination stage of Superanoxia in Middle Triassic (Anisian) sedimentary sequence of the Mino belt, central Japan

Abundant microspherules from the Upper Ordovician of northern Tarim Basin, Northwest China: Origin and palaeoenvironmental implications

Preservation of Permian–Triassic boundary section in the Jurassic accretionary complex of the Lake Hamana, Central Japan

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