GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAU

 
 
 
 

GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAU

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Title: GEOCHEMICAL AND STABLE ISOTOPIC EVALUATION OF FENGHUOSHAN GROUP LACUSTRINE CARBONATES, NORTH-CENTRAL TIBET: IMPLICATIONS FOR THE PALEOALTIMETRY OF THE MID-TERTIARY TIBETAN PLATEAU
Author: Cyr, Andrew J
Description: Comprehensive analysis of lacustrine carbonates from the Eocene-Oligocene Fenghuoshan Group, north-central Tibet, allows interpretation of the paleolimnology and paleoaltitude of the north-central Tibetan Plateau during the mid-Tertiary. Sedimentologic evidence suggests carbonate deposition occurred in shallow lacustrine systems. Stable O and C isotopic analysis of Fenghuoshan carbonates show δ18O values ranging from –11.7‰ to –10.26 (PDB), and δ13C values between –7.13‰ and –2.22‰ (PDB). Poor correlation between these isotopic systems (r2 = 0.0219)suggests open lakes during carbonate deposition. Mineralogy and Mg/Ca ratios indicate fresh water conditions. XRD and Mg/Ca data combined with δ18O values and petrography show little diagenetic alteration. These data indicate that the oxygen isotopic composition of Fenghuoshan carbonates represents the oxygen isotopic composition of meteoric water feeding Fenghuoshan lakes at the time of deposition. Oxygen isotope fractionation model calculations using this meteoric water composition indicate the hypsometric mean elevation of basins feeding Fenghuoshan lakes was ~2 km.
Permanent Link: http://rave.ohiolink.edu/etdc/view?acc_num=miami1080329128
http://hdl.handle.net/2374.OX/18180
Date: 2004

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