Ahmad, S. M.; Dayal, A. M.; Padmakumari, G.; Babu, G. Anil; Gopalan, K. (2005): Changes in seawater (super 87) Sr/ (super 86) Sr curve during early Miocene to early late Miocene; implications of ODP Site 758A record. Geological Society of India, Bangalore, India, Journal of the Geological Society of India, 65 (2), 147-157, georefid:2005-051744
Abstract:
A seawater (super 87) Sr/ (super 86) Sr record is generated for early Miocene to early late Miocene based on measurements of 114 samples of cleaned planktonic foraminifera from Ocean Drilling Program site 758 (Hole 758A) in the eastern Indian Ocean. Age model for this Site is based on nannofossil events and interpolated numerical ages are compared with Sr isotopically-derived ages. There is a fairly good agreement between the two stratigraphic tools (<+ or -1.5 Ma). (super 87) Sr/ (super 86) Sr ratio during approximately 23.7 Ma to approximately 8.1 Ma increased from 0.70828 to 0.70895, with variations in the rate of (super 87) Sr/ (super 86) Sr increase. Seventh-order polynomial fit curve shows the (super 87) Sr/ (super 86) Sr increase rates of 44X10 (super -6) m.y. (super -1) for approximately 23.7 to approximately 19.2 Ma, 41X10 (super -6) m.y. (super -1) for approximately 10.8 Ma, and 25X10 (super -6) m.y. (super -1) for approximately 10.8 to approximately 8.1 Ma. These rates are broadly consistent with the growth rates of (super 87) Sr/ (super 86) Sr reported from other DSDP and ODP sites with some minor differences. A composite Sr isotope curve constructed for the 24-8 Ma is broken into linear segments with a different linear regression equation. The overall rate of (super 87) Sr/ (super 86) Sr increase for approximately 24-8 Ma at site 758A (40X10 (super -6) m.y. (super -1) ) is in agreement with the rate of (super 87) Sr/ (super 86) Sr increase of the composite curve (42X10 (super -6) m.y. (super -1) ).
Coverage:
West: 90.2140 East: 90.2141 North: 5.2303 South: 5.2302
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