caa a22 4500 477064558 CHVBK 20180405111409.0 cr unu---uuuuu 170330e19960601xx s 000 0 eng 10.1007/BF02422228 doi (NATIONALLICENCE)springer-10.1007/BF02422228 Multiple factors in the origin of the Cretaceous/Tertiary boundary: the role of environmental stress and Deccan Trap volcanism [Elektronische Daten] [G. Glasby, H. Kunzendorf] A review of the scenarios for the Cretaceous/Tertiary (K/T) boundary event is presented and a coherent hypothesis for the origin of the event is formulated. Many scientists now accept that the event was caused by a meteorite impact at Chicxulub in the Yucatan Peninsula, Mexico. Our investigations show that the oceans were already stressed by the end of the Late Cretaceous as a result of the long-term drop in atmospheric CO2, the long-term drop in sea level and the frequent development of oceanic anoxia. Extinction of some marine species was already occurring several million years prior to the K/T boundary. The biota were therefore susceptible to change. The eruption of the Deccan Traps, which began at 66.2 Ma, coincides with the K/T boundary events. It erupted huge quantities of H2SO4, HCl, CO2, dust and soot into the atmosphere and led to a significant drop in sea level and marked changes in ocean temperature. The result was a major reduction in oceanic productivity and the creation of an almost dead ocean. The volcanism lasted almost 0.7 m.y.. Extinction of biological species was graded and appeared to correlate with the main eruptive events. Elements such as Ir were incorporated into the volcanic ash, possibly on soot particles. This horizon accumulated under anoxic conditions in local depressions and became the marker horizon for the K/T boundary. An oxidation front penetrated this horizon leading to the redistribution of elements. The eruption of the Deccan Traps is the largest volcanic event since the Permian-Triassic event at 245 Ma. It followed a period of 36 m.y. in which the earth's magnetic field failed to reverse. Instabilities in the mantle are thought to be responsible for this eruption and therefore for the K/T event. We therefore believe that the K/T event can be explained in terms of the effects of the Deccan volcanism on an already stressed biosphere. The meteorite impact at Chicxulub took place after the onset of Deccan volcanism. It probably played a regional, rather than a global, role in the K/T extinctions. Springer-Verlag GmbH & Co KG, 1996 Cretaceous/Tertiary boundary nationallicence Mass extinction nationallicence Deccan Traps nationallicence Environmental stress nationallicence Glasby G. Department of Earth Sciences, University of Sheffield, S10 2UH, Sheffield, England aut Kunzendorf H. Environmental Science and Technology Department, Risø National Laboratory, P.O. Box 49, DK-4000, Roskilde, Denmark aut Geologische Rundschau Springer-Verlag 85/2(1996-06-01), 191-210 0016-7835 85:2<191 1996 85 531 https://doi.org/10.1007/BF02422228 text/html Onlinezugriff via DOI 1 review-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02422228 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Glasby G. Department of Earth Sciences, University of Sheffield, S10 2UH, Sheffield, England aut NATIONALLICENCE 700 1- Kunzendorf H. Environmental Science and Technology Department, Risø National Laboratory, P.O. Box 49, DK-4000, Roskilde, Denmark aut NATIONALLICENCE 773 0- Geologische Rundschau Springer-Verlag 85/2(1996-06-01), 191-210 0016-7835 85:2<191 1996 85 531 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer