Glass, Billy P.; Koeberl, Christian; Huber, Heinz (1999): Trace element study of upper Eocene clinopyroxene-bearing spherules; preliminary results. Geological Society of America (GSA), Boulder, CO, United States, In: Anonymous, Geological Society of America, 1999 annual meeting, 31 (7), 64, georefid:2001-006896

As part of an investigation to determine the number of (and source craters for) ejecta/spherule layers in upper Eocene marine sediments, we started a study of the petrography and major and trace element compositions of 73 clinopyroxene-bearing (cpx) spherules and 37 microtektites from 8 upper Eocene sites. The spherules came from the eastern equatorial Indian Ocean (DSDP Site 216), western equatorial Pacific (DSDP Site 292), central equatorial Pacific (DSDP sites 69A, 162, and 166), Gulf of Mexico (DSDP Site 94), and Caribbean Sea (DSDP Site 149 and Core RC9-58). Trace element abundances were obtained for Sc, Cr, Ni, Zn, As, Rb, Sr, Zr, Sb, Ba, Hf, Ta, Au, Th, U, and the rare earth elements (REE) using INAA. Limited data were obtained for Br, Cs, and W. We determined major element compositions for the same spherules using energy dispersive x-ray analysis. We report our preliminary results for the trace element abundances of the upper Eocene cpx spherules. In general, the cpx spherules have trace element abundances similar to the average for the upper continental crust; but they generally have 1-2 orders of magnitude more Cr, Co, Ni, and Au; some have up to nearly 3 orders of magnitude more Ir; and most have approximately 10x less Th and U. The REE abundances and chondrite-normalized patterns of the cpx spherules are similar to those of the average upper continental crust. Trace element contents of the cpx spherules from the eastern equatorial Indian Ocean and western equatorial Pacific Ocean are similar to those from the central equatorial Pacific Ocean, Gulf of Mexico, Caribbean Sea, and NW Atlantic Ocean (DSDP Site 612). Thus, trace element data do not support the hypothesis that the cpx spherules in the eastern Indian Ocean and western equatorial Pacific are older than those from the other sites. We attribute the high siderophile abundances of the cpx spherules to meteoritic contamination.
West: -175.0448 East: 147.0000 North: 38.4913 South: -60.0000
West: NaN East: NaN North: NaN South: NaN
West: NaN East: NaN North: NaN South: NaN
Expedition: 10
Site: 10-94
Expedition: 16
Site: 16-162
Expedition: 17
Site: 17-166
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Site: 22-216
Expedition: 31
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Site: 95-612
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