Source and Distribution of Organic Matter in the Andaman Backarc Basin Sediments: Insights from Rock-Eval Pyrolysis and Palynofacies Analysis

Mishra, Subhashree and Peketi, Aditya and Dhar, Sunil Kumar and Sethi, Chinmay and Mazumdar, A. (2025) Source and Distribution of Organic Matter in the Andaman Backarc Basin Sediments: Insights from Rock-Eval Pyrolysis and Palynofacies Analysis. Journal of the Geological Society of India , 101 (10). pp. 1520-1529. ISSN 0016-7622

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Official URL: https://doi.org/10.17491/jgsi/2025/174270

Abstract

The present research characterises the organic matter composition in sediments from the Andaman Backarc Basin using a combined approach of Rock-Eval pyrolysis and palynofacies analysis. The integration of these techniques enabled the comprehensive identification of organic matter type, source, nature, and hydrocarbon generation potential within the study area. The analysis was conducted on 82 cm sediment core (10°18.909′ N; 93°33.078′ E; 1395m water depth) collected during the ORV Sindhu Sankalp (SSK-145) expedition. Palynofacies analysis reveals an abundance of labile materials, including unstructured Amorphous Organic Matter (AOM), and resistant marine organic walled microfossils (dinoflagellate cysts, acritarchs, prasinophytes, and other zoomorphs), and terrestrial inputs (spores, pollen grains, cuticles, tracheids, and resins). The organic matter is characterised by a dominance of amorphous organic matter, along with abundant oxidised plant twigs/recycled organic matter and wood remnants, indicating a primarily terrigenous origin supplied by major rivers and their tributaries. The results of Rock-Eval pyrolysis indicate low to moderate organic matter abundance (TOC: 0.2–0.8 wt%) with predominance of Type III kerogen and early mature organic matter (Tmax: 420–432°C), suggesting a gas-generative potential. This study provides an initial evaluation of organic matter abundance in the Andaman Backarc Basin; further high-resolution investigations of deeper regions and a broader aerial extent are needed to develop a more comprehensive understanding of its hydrocarbon potential.

Item Type:	Article
Subjects:	Coal Preparation
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	10 Feb 2026 05:02
Last Modified:	10 Feb 2026 05:02
URI:	https://cimfr.csircentral.net/id/eprint/2938

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