Chapter 3Modelling late devonian extinction hypotheses

TY - JOUR

T1 - Chapter 3Modelling late devonian extinction hypotheses

AU - McGhee, George R.

PY - 2005

Y1 - 2005

N2 - Modelling the conditions of extinction hypotheses can lead to the discernment of the critical observations that must be made in order to definitively test those hypotheses. Models considered here are based upon the beginning ning assumption that the end-Frasnian biodiversity crisis was triggered in large part by pulses of global cooling. Both classes of models are catastrophic: large-igneous-province volcanism and asteroid or comet impact. A single impact model can be ruled out, as its predicted effects do not match those of the extinction pulses seen in the Late Fransian. An episodic global-winter model would, but those effects can be produced by both the catastrophic volcanism and multiple impacts models. Alternative models suggest that both catastrophic volcanism and multiple impacts may trigger a global greenhouse-induced temperature increase, a predicted effect that does not match the empirical data. However, if both of those mechanisms are shifted back in time to produce lag-time models of short-term global temperature increase and then rapid temperature drops as the anomalous greenhouse interval collapsed, then both produce effects that do match the empirical data. To definitively choose among the several model predictions two critical data are needed: (1) an accurate radiometric date on the Frasnian/Famennian (F/F) boundary, and (2) an accurate Late Devonian global temperature curve. Recent research results suggesting a 376 Ma age for the F/F boundary would indicate that several known impact craters post-date the F/F extinctions, and make the impact-induced extinction models less likely. High-research priority should thus be given to obtaining a biostratigraphic date or an accurate radiometric date on the Viluy Traps, as a test to corroborate the volcanic-induced extinction models.

AB - Modelling the conditions of extinction hypotheses can lead to the discernment of the critical observations that must be made in order to definitively test those hypotheses. Models considered here are based upon the beginning ning assumption that the end-Frasnian biodiversity crisis was triggered in large part by pulses of global cooling. Both classes of models are catastrophic: large-igneous-province volcanism and asteroid or comet impact. A single impact model can be ruled out, as its predicted effects do not match those of the extinction pulses seen in the Late Fransian. An episodic global-winter model would, but those effects can be produced by both the catastrophic volcanism and multiple impacts models. Alternative models suggest that both catastrophic volcanism and multiple impacts may trigger a global greenhouse-induced temperature increase, a predicted effect that does not match the empirical data. However, if both of those mechanisms are shifted back in time to produce lag-time models of short-term global temperature increase and then rapid temperature drops as the anomalous greenhouse interval collapsed, then both produce effects that do match the empirical data. To definitively choose among the several model predictions two critical data are needed: (1) an accurate radiometric date on the Frasnian/Famennian (F/F) boundary, and (2) an accurate Late Devonian global temperature curve. Recent research results suggesting a 376 Ma age for the F/F boundary would indicate that several known impact craters post-date the F/F extinctions, and make the impact-induced extinction models less likely. High-research priority should thus be given to obtaining a biostratigraphic date or an accurate radiometric date on the Viluy Traps, as a test to corroborate the volcanic-induced extinction models.

KW - Late Devonian

KW - catastrophic volcanism hypotheses

KW - global cooling

KW - mass extinctions

KW - multiple impacts hypotheses

UR - http://www.scopus.com/inward/record.url?scp=45449094420&partnerID=8YFLogxK

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U2 - https://doi.org/10.1016/S0920-5446(05)80003-2

DO - https://doi.org/10.1016/S0920-5446(05)80003-2

M3 - Article

SN - 0920-5446

VL - 20

SP - 37

EP - 50

JO - Developments in Palaeontology and Stratigraphy

JF - Developments in Palaeontology and Stratigraphy

IS - C

ER -