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<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place"> Effect of Miocene paleoceanographic changes on the benthic foraminiferal diversity at ODP site 754A (southeastern Indian Ocean) </smarttagtype>

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Title Effect of Miocene paleoceanographic changes on the benthic foraminiferal diversity at ODP site 754A (southeastern Indian Ocean)
 
Creator Rai, Ajai Kumar
Maurya, Abhayanand Singh
 
Subject Benthic Foraminifera
Diversity
Indian Ocean
Miocene
Oceanography
 
Description 423-431
Miocene deep sea benthic foraminiferal diversity at ODP site 754A, in the southeastern Indian Ocean was examined in the present study. Paleoceanographic and paleoclimatic changes were inferred based on the above study. Species diversity was measured in terms of Shannon-Weaver Index [H(S)], Hurlbert’s Diversity Index (S100), Alpha Index (α) and Equitability (E’). Values of S100 show more positive correlation with H(S) and α value. All diversity parameters show almost similar pattern during the study interval. Present study infers that the changing trophic level has much influence on the faunal diversity. More diverse fauna of late early Miocene to early middle Miocene along with low δ18O and high δ13C values reflect warm and stable bottom waters with low food supply. This corresponds to the Miocene climatic optimum. This was also an interval of global warming and reduced Antarctic ice-sheet volume. Significant decline in diversity and d13C values along with abrupt increase in d18O values at ~ 14 Ma indicate cold, relatively less oxygenated and unstable bottom waters with increased food supply due to higher surface productivity. Development of thermal gradient between low and high latitudes in response to the expansion of Antarctic ice-sheet during 15-12.5 Ma was responsible for increased upwelling and high surface productivity. Decrease in faunal diversity at ~7 Ma onwards along with low δ13C and high δ18O values corresponds with the Chron-6 negative Carbon shift, expansion of west Antarctic ice-sheets and lowering of sea level.
 
Date 2010-01-05T11:43:52Z
2010-01-05T11:43:52Z
2009-12
 
Type Article
 
Identifier 0975-1033 (Online); 0379-5136 (Print)
http://hdl.handle.net/123456789/7079
 
Language en_US
 
Publisher CSIR
 
Source IJMS Vol.38(4) [December 2009]