Tightly coupled records of Ca and C isotope changes during the Hirnantian glaciation event in an epeiric sea setting

Holmden, Chris; Panchuk, Karla; Finney, Stanley C.

doi:10.1016/j.gca.2012.09.017

Cited by 47 publications

(35 citation statements)

References 58 publications

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“…Based on previous work, the distribution and amplitude of the Silurian CIE's suggest that the anomalies probably had a non-whole-ocean nature (Melchin & Holmden 2006, Loydell 2007, LaPorte et al 2009, Holmden et al 2012, Kozłowski & Sobień 2012, but occurs as "spooky", synchronous events on independent carbonate platforms. On the other hand, the flat top of the δ 13 C curves with similar absolute values and regardless the palaeogeographic position, suggests that the detached in space "isotopic anomalies originated from the same global isotopic reservoir rather than being evolved independently within small restricted epeiric basins" (Frýda & Manda 2013).…”

Section: Causes Of the Ciementioning

confidence: 96%

“…10A) during the sea-level fall (see Holmden et al 2012) that took place just below the mid-Ludfordian CIE.…”

Section: A C Bmentioning

confidence: 99%

“…Melchin & Holmden 2006);or (ii) by local large scale loss of the 12 C from the DIC pool ("residual CIE" -e.g. Holmden et al 2012, Kozłowski & Sobień 2012.…”

Section: Causes Of the Ciementioning

confidence: 99%

“…Loydell 2007, Cramer & Munnecke 2008, Holmden et al 2012, Kozłowski & Sobień 2012, Frýda & Manda 2013, Ghienne et al 2014 and to date several models have been proposed (summarized in Calner 2008, Ghienne et al 2014. Early Palaeozoic CIEs appear to coincide with perturbations in the isotopic record of sulphur (e.g.…”

mentioning

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%

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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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Section: Causes Of the Ciementioning

confidence: 96%

“…10A) during the sea-level fall (see Holmden et al 2012) that took place just below the mid-Ludfordian CIE.…”

Section: A C Bmentioning

confidence: 99%

“…Melchin & Holmden 2006);or (ii) by local large scale loss of the 12 C from the DIC pool ("residual CIE" -e.g. Holmden et al 2012, Kozłowski & Sobień 2012.…”

Section: Causes Of the Ciementioning

confidence: 99%