Oxygen isotope analysis of bone and tooth enamel phosphate from paleogene sediments: Experimental techniques and initial results |
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| Authors: | M K Bera Kasturi Bhattacharya A Sarkar A Samanta Kishor Kumar Ashok Sahni |
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| Institution: | (1) India Meteorological Department, Pune, India;(2) Indian Institute of Tropical Meteorology, Dr. Homi Bhabha Road, NCL Post, Pashan, 411008 Pune, India; |
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| Abstract: | Oxygen isotope composition (δ18O) of fossil bone and tooth enamel phosphate (bioapatite) is an important tool for estimating the isotopic composition of
past environmental water. Lack of analytical facility was a hindrance for studying such bioapatites in spite of large number
of fossil materials reported from various geological ages in India. We have established in our laboratory, based on available
methods, the chemical procedure for extraction of very small amount (<1000 μg) PO4
−3 from bioapatite and on-line mass spectrometric measurement of its δ18O composition by high temperature (∼1450°C) pyrolysis. The achieved precision is ∼± 0.3 ‰ similar to obtained elsewhere, with
interlaboratory calibration showing excellent agreement of standard phosphates. Inferred δ18O values of environmental water, based on the analysis of teeth and bones of sharks, fish and terrestrial mammals from the
Paleogene successions of the northwest sub-Himalayan and the Peninsular India show strong correspondence with animal habitats.
The freshwater δ18O values are much depleted having range similar to modern monsoon precipitation. However, owing to our small dataset it is
not possible at this stage to infer about the existence of monsoon over the Indian sub-continent during the Eocene-Oligocene
time. |
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