High-precision dating of the Kalkarindji large igneous province, Australia, and synchrony with the Early–Middle Cambrian (Stage 4–5) extinction

Jourdan, F., Hodges, K., Sell, B., Schaltegger, U., Wingate, M.T.D., Evins, L.Z., Sōderlund, U., Haines, P.W., Phillips, D., and Blenkinsop, T. (2014) High-precision dating of the Kalkarindji large igneous province, Australia, and synchrony with the Early–Middle Cambrian (Stage 4–5) extinction. Geology (Boulder), 42 (6). pp. 543-546.

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Abstract

The voluminous Kalkarindji flood basalts erupted in Australia during the Cambrian and covered >2 × 10^6 km^2. New U-Pb and ^40Ar/^39Ar age data from intrusive rocks and lava flows yielded statistically indistinguishable ages at ca. 511 Ma, suggesting a relatively brief emplacement for this province. A zircon age of 510.7 ± 0.6 Ma shows that this province is temporally indistinguishable at the few-hundred-thousand-year level from the Early–Middle Cambrian (Stage 4–5) boundary age of 510 ± 1 Ma, which marks the first severe extinction of the Phanerozoic and an extended marine anoxia period. Sulfur concentration measurements ranging from <50 to 1900 μg/g, and fractal analysis of extensive explosive volcanic breccias, suggest that blasts and phreatomagmatic explosions have contributed to injection of large amounts of sulfur into the stratosphere. In addition, magma intrusions in oil, gas, and sulfate deposits may have generated significant emission of CH(4) and SO(2) which, along with volcanic gases, would have combined to cause an oscillation of the climate and led to the Cambrian extinction.

Item ID: 36074
Item Type: Article (Research - C1)
ISSN: 0091-7613
Funders: Marie Curie Outgoing International Fellowship
Date Deposited: 12 Nov 2014 12:35
FoR Codes: 04 EARTH SCIENCES > 0403 Geology > 040308 Palaeontology (incl Palynology) @ 30%
04 EARTH SCIENCES > 0403 Geology > 040303 Geochronology @ 40%
04 EARTH SCIENCES > 0403 Geology > 040304 Igneous and Metamorphic Petrology @ 30%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970104 Expanding Knowledge in the Earth Sciences @ 100%
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