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Recent Publications

Ecological ranking of Phanerozoic biodiversity crises: The Serpukhovian (Early Carboniferous) crisis had a greater ecological impact than the end-Ordovician.  Geology vol. 20(2), p.147-150.

Please note that GSA does not permit posting of pdf copies of its journal articles.  I include the free abstract below and the link to Geology here, but note membership is required to view/obtain a pdf copy.  http://geology.gsapubs.org/content/40/2/147.full.pdf+html

Abstract: We propose a new ecological ranking of the major Phanerozoic biodiversity crises in which the Serpukhovian biodiversity crisis is ranked fifth in ecological impact, lesser than the Late Devonian but greater than the end-Ordovician, and the end-Ordovician mass extinction is ranked sixth. It is interesting that both the end-Ordovician mass extinction and the Serpukhovian biodiversity crisis were triggered by glaciations. Other than that common trigger, the two events were very different. Glaciation in the Ordovician triggered an enormous jump in the extinction rate of marine organisms and was taxonomically very severe, yet the ecological impact of those extinctions was minimal. Glaciation in the Serpukhovian triggered a precipitous drop in the speciation rate but only moderate diversity losses, yet the ecological impact of those diversity losses and ecosystem restructuring was an ecological level of magnitude larger than that seen in the end-Ordovician mass extinction.

     

    Multiproxy record of abrupt sea surface temperature cooling across the Eocene-Oligocene transition in the Gulf of Mexico. Geology, vol. 40, p. 159-162. 

    Please note that GSA does not permit posting of pdf copies of its journal articles.  I include the free abstract below and the link to Geology here, but note membership is required to view/obtain a pdf copy. http://geology.gsapubs.org/content/40/2/159.full.pdf+html

    Abstract: The Eocene-Oligocene transition (EOT; ca. 33–34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (∼15–34 k.y. resolution) from St. Stephens Quarry, Alabama, USA, derived from foraminiferal Mg/Ca, δ18O, and TEX86. We constrain sea-surface temperatures (SSTs) in the latest Eocene and early Oligocene and address the issue of climatic cooling during the EOT. Paleotemperatures derived from planktic foraminifera Mg/Ca and TEX86 are remarkably consistent and indicate late Eocene subtropical SSTs of >28 °C. There was substantial and accelerated cooling of SSTs (3–4 °C) through the latest Eocene “precursor” δ18O shift (EOT-1), prior to Oligocene Isotope-1 (Oi-1). Our multispecies planktic foraminiferal δ18O records diverge at the E/O boundary (33.7 Ma), signifying enhanced seasonality in the earliest Oligocene in the Gulf of Mexico in the Gulf of Mexico.

     

     

     

    Magnetization of polar ice: a measurement of terrestrial dust and extraterrestrial fallout: Quaternary Science Reviews, v. 33, p. 20-31. 

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    Remote laser-induced breakdown spectroscopy analysis of East African Rift sedimentary samples under Mars conditions. 

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