Record Details

Higher plant biomarker signatures of Early Eocene sediments of North Eastern India

DSpace at IIT Bombay

View Archive Info
 
 
Field Value
 
Title Higher plant biomarker signatures of Early Eocene sediments of North Eastern India
 
Creator CHATTOPADHYAY, A
DUTTA, S
 
Subject Early Eocene
Coal
Biomarker
Hydrocarbon potential
Rainforest elements
UPPER ASSAM BASIN
CRUDE OILS
GEOCHEMICAL CHARACTERIZATION
THERMAL MAXIMUM
ORGANIC-MATTER
DITERPENOID HYDROCARBONS
AROMATIC-HYDROCARBONS
NORTHEASTERN INDIA
AUSTRALIAN COALS
TERTIARY OILS
 
Description The biomarkers, molecular fossils of paleobiota, have been studied in detail from a coal-bearing sequence of Early Eocene Lakadong sandstone member of Sylhet Formation of Upper Assam Basin, NE India, using gas chromatography-mass spectrometry. Corresponding hydrocarbon source potential of the same unit has been studied using Rock-Eval pyrolysis. The Rock-Eval data suggest dominant terrestrial land plant contribution, i.e., Type III kerogen and the sediments of the section had entered the early stage of catagenesis. The alkane and isoprenoid distributions are characterized by odd over even preference (OEP) (1.1-1.2) of n-alkanes and high pristane/phytane ratio (2.9-7.6) which corroborate the Rock-Eval data. The distribution of aliphatic biomarkers is characterized by dominance of C-24 tetracyclics over C-23 tricyclics, high concentration of des-E hopane, moderate to high C-29/C-30 hopane ratio, extremely low oleanane index and low C-35 homohopane index. The extremely low oleanane index is correlated with a high degree of aromatization of oleanane skeleton, favoured by acidic swampy depositional environment. The presence of diterpanes at the base of the Early Eocene section indicates contribution from gymnosperms (Coniferales order of land plants) whereas angiospermous biomarkers with oleanoid skeleton are also preserved. This pattern subsequently evolved to angiosperm dominated towards the top of the section with no gymnosperm signature indicating possible climatic variation during the Early Eocene. Towards the top of the section presence of bicadinanes indicates contribution of Dipterocarpaceae family of trees and advent of the evergreen tropical rain forest element in eastern India in Early Eocene, similar to the pattern found in western India, e.g., Cambay and Kutch basins. (C) 2014 Elsevier Ltd. All rights reserved.
 
Publisher ELSEVIER SCI LTD
 
Date 2014-12-28T16:54:23Z
2014-12-28T16:54:23Z
2014
 
Type Article
 
Identifier MARINE AND PETROLEUM GEOLOGY, 5751-67
0264-8172
1873-4073
http://dx.doi.org/10.1016/j.marpetgeo.2014.04.004
http://dspace.library.iitb.ac.in/jspui/handle/100/16936
 
Language English