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language
eng
Author
Hossain, H. M. Z Department of Petroleum and Mining Engineering, Jashore University of Science and Technology, Jashore 7408, Bangladesh
Ratul-Al-Istiak, H. M. Department of Petroleum and Mining Engineering, Jashore University of Science and Technology, Jashore 7408, Bangladesh
Mahid, T. R. Department of Petroleum and Mining Engineering, Jashore University of Science and Technology, Jashore 7408, Bangladesh
Ratnayake, A. S. Faculty of Science and Technology, Uva Wellassa University, Passara Road, Badulla 90000, Sri Lanka
Naseem, S. Department of Geology, University of Karachi, Karachi 75270, Pakistan
Hakro, A. A. A. D. Centre for Pure & Applied Geology, University of Sindh, Jamshoro 76080, Pakistan
Description
The middle Paleocene sub-bituminous coals and lignites in the Lakhra coalfield, Sindh Province, Pakistan were investigated to clarify source of organic matter and depositional environments in the Indus Delta. Here we present multiproxy approach such as C/N and C/S ratios, n-alkane indicators such as average chain length (ACL), carbon preference index (CPI), and aquatic index (Paq), as well as pristane/phytane (Pr/Ph) ratio, oleanane/hopane (Ole/Hop) ratio, and Ts/(Ts + Tm) ratio to evaluate the peat accumulation conditions at the Lakhra coalfield. The TOC, TN and TS contents range from 8.15 to 55.1%, 0.08 to 0.93% and 2.14 to 11.4%, respectively. The C/N ratios (51.2-96.5) indicate a dominant control of organic matter by terrestrial higher plants to the peat bog. The values of C32 hopanes 22S/(22S + 22R) and C29 sterane 20S/(20S + 20R) are 0.14-0.36 and 0.26-0.29, respectively, showing that the maturity level is immature. The depositional environment was evaluated to be lagoonal brackish water pond or marsh where depositional condition was anoxic to dysoxic based on the datasets of high sulfur contents (2.1-11.4%), low to high C/S ratios (0.7-26) and low Pr/Ph ratios (0.14-1.00) without UCM. The Lakhra coals and lignites are characterized by high C/N ratios (51-97), high oleanane/C30-hopanes ratios (<1.30), medium to high CPI ( ~2.0-9.8), medium ACL (27.6-28.7) and low to medium Paq values (0.13-0.34). According to these results, main origin of the coals was probably angiosperm reed/grass. The coals are also minorly accompanied by aquatic/ submerged plants and specific mosses without Sphagnum. The Lakhra coals are not abundant in regular steranes and characterized by high contents of diasteranes probably due to fine clay rich depositional environment.
Journal Title
Researches in Organic Geochemistry
Volume
36
Issue
1
Start Page
1
End Page
11
ISSN
1344-9915
ISSN(Online)
2189-7891
Published Date
2020
DOI
Publisher
日本有機地球化学会
Publisher Transcription
ニホン ユウキ チキュウ カガク カイ
Publisher Aalternative
The Japanese Association of Organic Geochemists
NII Type
Journal Article
Format
PDF
Relation
Resource URL(IsVersionOf)
http://www.ogeochem.jp/pdf/ROG_BN/vol36/v36_pp01-11.pdf
Text Version
出版社版
Gyoseki ID
39615
OAI-PMH Set
Faculty of Science and Engineering