Carbon and sulfur isotopic anomalies across the Ordovician–Silurian boundary on the Yangtze Platform, South China

Yan, Detian; Chen, Daizhao; Wang, Qingchen; Wang, Jianguo; Wang, Zhuozhuo

doi:10.1016/j.palaeo.2008.12.016

Cited by 126 publications

(71 citation statements)

References 39 publications

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“…For all three sections, TOC contents are highest in the Wufeng and Lungmachi formations, and a positive δ 13 C org excursion commences in the upper Katian and peaks in the Hirnantian. The observed changes are broadly consistent with previously published records from coeval sections around the world, implying global controls (Fan et al, 2009;Yan et al, 2009;Zhang et al, , 2010Gorjan et al, 2012;Hammarlund et al, 2012). Drawing on redox interpretations based on iron speciation data (see Section 6.1), it is possible to infer controls on carbon cycling during the O-S transition.…”

Section: Carbon and Sulfur Cycling Through O-s Transitionsupporting

confidence: 86%

Global and regional controls on marine redox changes across the Ordovician-Silurian boundary in South China

Liu

Algeo

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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The Ordovician-Silurian (O-S) transition coincided with significant environmental and biological changes. In South China, the Yangtze Platform experienced both global and regional events at this time, including sea-level fluctuations, tectonic movements, volcanic eruptions, mass extinction, and widespread anoxia. The O-S transitional strata of the Yangtze Platform comprise organic-rich black shales that are an important oil source rock. To explore the evolution of watermass chemistry and its relationship to organic matter accumulation, we conducted an integrated Fe-S-C geochemical study (i.e., Fe-speciation, δ 13 C org , δ 34 S py , pyrite-S and TOC) of the O-S boundary sections at Datianba (Chongqing Municipality) and Shuanghe (Sichuan Province). These sections were located in the restricted inner Yangtze Sea, in contrast to the previously studied Wangjiawan section, which was deposited in a more open setting of the outer Yangtze Sea. In contrast to the well-oxygenated conditions at Wangjiawan, the Datianba and Shuanghe sections record persistently anoxic, and episodically euxinic, conditions during the Hirnantian, which can be explained by the unique paleogeography and restricted hydrography of the inner Yangtze Sea. We propose that the regional Kwangsian Orogeny, which was driven by collision of the Yangtze and Cathaysia blocks, played a key role in basin development, watermass chemistry changes, and accumulation of Wufeng Formation black shales within the Yangtze Sea. The more widespread black shales of the Lower Silurian Lungmachi Formation were linked to the post-Hirnantian global marine transgression.

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Section: Carbon and Sulfur Cycling Through O-s Transitionsupporting

confidence: 86%

Global and regional controls on marine redox changes across the Ordovician-Silurian boundary in South China

Liu

Algeo

et al. 2016

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…In this case, pyrite accumulation also co-occurred with silt-bearing deposits during an inferred glacial regression. Positive sulphur isotope excursions, interpreted as caused by mass sulphide deposition, have been found in the Hirnantian glaciation interval in South China (Yan et al 2009) and the Furongian Steptoean Positive Carbon Isotope Excursion (SPICE; Gill et al 2011). Because pyrite formation is strongly limited by iron availability, the eolian dust driver seems very likely to play an important role in such events.…”

Section: Discussionmentioning

confidence: 99%

“…Early Palaeozoic CIEs appear to coincide with perturbations in the isotopic record of sulphur (e.g. Yan et al 2009, Gill et al 2011), nitrogen (LaPorte et al 2009, and calcium (Holmden et al 2012), hence represent only part of the pronounced perturbations in the seawater chemistry.…”

mentioning

confidence: 99%

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Kozłowski¹

2015

Bull. Geosci.

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The mid-Ludfordian Carbon Isotope Excursion (CIE) is one of the biggest perturbation in the isotope and facies record in the Palaeozoic. However, its causes still remain unknown. In the periplatform setting of the Baltica palaeocontinent the event interval contains rock-forming minute calcite crystals, interpreted here as suspension-originated analogues of recent whitings and calcite rafts. The grains were preferentially formed around picocyanobacterial filaments, which are preserved as tubes inside. An event-related, 9 m-thick, massive calcisiltite bed points to the persistent hypersaturated state conditions (HSS) during the increasing limb of the CIE. The studied interval contains also a significant admixture of minute-sized detrital dolomite grains, appear for the first time several meters below and reach peak abundance immediately below the calcisiltite interval. The dolomite grains show consistent δ 13 C values (~0‰) across the CIE. Their record is decoupled from the bulk-rock C-isotope record and thus indicates overwhelmingly pre-sedimentary formation and extrabasinal provenance of the dolomite. The size and provenance of the grains, along with their incorporation into surface water precipitates and formation of specific very thin laminas with internal density gradation of grains (dolomite-quartz couplets), suggest the eolian delivery of the grains to the basin. The dust influx pulses seem to have triggered the calcite precipitation events. Furthermore, the size-frequency distribution of the pyrite framboids across the studied interval shows that the progressing dust influx was followed by persistent euxinia occurring right before and during the increasing limb of the CIE. In the proposed model, globally enhanced eolian delivery of iron during the assumed glaciation promoted high net pyrite formation. The resulting "sulphate to bicarbonate exchange", a hypothetical dissolution of eolian carbonate dust particles in deep basins, a concurrent bicarbonate supply from the carbonates emerged due to the sea-level fall, and a parallel cessation of the carbonate factory (exposed carbonate platform tops), raised the alkalinity and formed the global carbonate hypersaturated state (HSS) of the ocean. The processes needed largescale invasion of the CO 2 , consumed in the ocean by bicarbonate formation processes. It is hypothesized that during the subsequent initial transgression, the HSS was discharged by massive carbonate precipitation. The rapid "carbonate reflux" returned the earlier uptaken CO 2 to the atmosphere by fast degassing. Its fast transfer resulted in the globally synchronized, kinetic, residual, 13 C DIC -enrichment of water pools localized over individual carbonate platforms. During "carbonate reflux", the local CIE amplitude depended on the carbonate production rate, water column thickness and pool residence time.•

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“…At Dingjiapo, the Wufeng, and Lungmachi formations are both characterized by black shale that contains rich graptolite fossils 35-37, representing deep water conditions, while the Kuanyinchiao Formation is dominated by argillaceous limestone with Hirnantian fauna fossils that record a drop in eustatic sea level 38 and lowstand conditions during the Hirnantian glacial maximum 10,34,38 . The O-S boundary at the Wangjiawan section, GSSP of the base of Hirnantian Stage (Latest Ordovician), was marked by two extinction phases [39][40][41][42] . The first lasted from the Late Katian (D. mirus Zone) to the Early Hirnantian (N. extraordinarius Zone), and coincided with the development of Gondwanan glaciation 42,43 .…”

Section: Ordovician Record In South Chinamentioning

confidence: 99%

“…in δ 13 C values of both carbonate and organic carbon 40 . The marine organisms that had been adapted to warm waters suffered massive demise 34,40 , while the Hirnantian fauna accustomed to cold and shallow waters became prosperous and widespread all over the world 7,8 . The second extinction pulse occurred at the beginning of Late Hirnantian (from N. extraordinarius Zone to N. persculptus Zone) 42 .…”

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confidence: 97%

Mercury Spikes Suggest Volcanic Driver of the Ordovician-Silurian Mass Extinction

Qing¹,

Zhao²,

Wang³

et al. 2017

Geological Society of America Abstracts With Programs

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The second largest Phanerozoic mass extinction occurred at the Ordovician-Silurian (O-S) boundary. However, unlike the other major mass extinction events, the driver for the O-S extinction remains uncertain. The abundance of mercury (Hg) and total organic carbon (TOC) of Ordovician and early Silurian marine sediments were analyzed from four sections (Huanghuachang, Chenjiahe, Wangjiawan and Dingjiapo) in the Yichang area, South China, as a test for evidence of massive volcanism associated with the O-S event. Our results indicate the Hg concentrations generally vary in parallel with TOC, and that the Hg/TOC ratios remain low and steady state through the Early and Middle Ordovician. However, Hg concentrations and the Hg/TOC ratio increased rapidly in the Late Katian, and have a second peak during the Late Hirnantian (Late Ordovician) that was temporally coincident with two main pulses of mass extinction. Hg isotope data display little to no variation associated with the Hg spikes during the extinction intervals, indicating that the observed Hg spikes are from a volcanic source. These results suggest intense volcanism occurred during the Late Ordovician, and as in other Phanerozoic extinctions, likely played an important role in the O-S event.Refinements in radio-isotopic dating techniques has demonstrated a strong temporal link between Large Igneous Province (LIP) volcanism and four out of the five largest mass extinctions in the Phanerozoic, leading to suggestions that LIP events have devastating effects on global ecosystems that in some ways mirrors concerns over modern anthropogenic impacts on the planet [1][2][3][4] . The one anomaly is the Ordovician-Silurian (O-S) mass extinction, the second largest of the "Big Five" extinctions. In terms of species loss the O-S represented about 86% of marine life 5,6 , including the elimination of graptolites 7-9 and brachiopods 10, 11 . The triggering mechanism of the O-S mass extinction has been extensively debated, and various hypotheses have been proposed, including gamma ray burst and bolide impact 12,13 ; however, the cause still remains highly controversial. Intense Late Ordovician volcanism was also suggested as a potential extinction mechanism 14,15 , although no clear geologic record of a Late Ordovician LIP event has been demonstrated. The age of the event makes it possible that any geologic record has been lost 15 . Given this, we tested for indirect evidence of volcanism at the O-S extinction boundary by examining the Hg record from classic sections in south China. Here we show that significant spikes in Hg concentrations occur at the O-S extinction, along with Hg stable isotope data that indicate a volcanic source for these spikes. We suggest that this reflects Hg loading by a LIP event. If correct, these results demonstrate that LIP events have indeed played a critical role in the evolution of life through time. Mercury as a Proxy for LIP eventsVolcanic eruptions are the main natural source of Hg to the environment 16 . Sanei et al. 17 demonstrated that th...

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Carbon and sulfur isotopic anomalies across the Ordovician–Silurian boundary on the Yangtze Platform, South China

Cited by 126 publications

References 39 publications

Global and regional controls on marine redox changes across the Ordovician-Silurian boundary in South China

Global and regional controls on marine redox changes across the Ordovician-Silurian boundary in South China

Eolian dust influx and massive whitings during the kozlowski/Lau Event: carbonate hypersaturation as a possible driver of the mid-Ludfordian Carbon Isotope Excursion

Mercury Spikes Suggest Volcanic Driver of the Ordovician-Silurian Mass Extinction

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