Organo-petrographic and geochemical characteristics of Gurha lignite deposits,Rajasthan,India:Insights into the palaeovegetation,palaeoenvironment and hydrocarbon source rock potential  

作　　者：Runcie Paul Mathews Bhagwan DSingh Vikram Partap Singh Alpana Singh Hukam Singh Mahesh Shivanna Suryendu Dutta Vinod A.Mendhe Rimpy Chetia 

机构地区：[1]DST-Birbal Sahni Institute of Palaeosciences,Lucknow,226007,India [2]Department of Earth Sciences,Indian Institute of Technology Bombay,Mumbai,400076,India [3]CSIR-Central Institute of Mining and Fuel Research,Dhanbad,826015,India

出　　处：《Geoscience Frontiers》2020年第3期965-988,共24页地学前缘（英文版）

基　　金：DST-SERB for providing the post-doctoral fellowship(PDF/2018/000883)。

摘　　要：The sedimentary sequence containing lignite deposits in Gurha quarry of the Bikaner-Nagaur Basin(Rajasthan)has been investigated.The samples from lignite and allied shale horizons were evaluated for petrographical,palynological,palynofacies and organic geochemical inferences,to depict the source flora and to reconstruct the palaeodepositional conditions prevailed during the sedimentation.An assessment for the hydrocarbon generation potential of these deposits has also been made.The results revealed the dominance of huminite macerals and phytoclasts organic matter(OM) indicating the existence of forested vegetation in the vicinity of the depositional site.A relatively high terrigenous/aquatic ratio(TAR) and the carbon preference index(CPI) are also suggesting the contribution of higher plants in the peat formation.However,the n-alkane distributions,maximizing at n-C17 and n-C29,showed inputs from the algal communities along with the higher plant derived organic matters.Recovered palynomorphs of the families Onagraceae,Meliaceae,Arecaceae,Rhizophoraceae,Rubiaceae,Ctenolophonaceae, etc.together with oleanene and ursane types of triterpenoids suggest the contribution from angiosperms source vegetation.Interestingly,the presence of Araucareaceae and Podocarpaceae pollen grains shows the existence of gymnosperms vegetation.Further,the presence of tetracyclic diterpanes;demethylated entbeyerane,sandaracopimarane,pimarane,and Kaurane type of compounds confirms the contribution of conifers.The variation in the values of the coefficient of non-equality(H:0.68%-7.56%),the standard deviation(8:0.04%-0.16%) and the coefficient of variability(V:16.10%-46.47%),also shows the heterogeneity in the source organic matter.The various petrographical indices,palynological entities,and geochemical parameters indicate that the peatforming vegetation was accumulated under a mixed environment and fluctuating hydrological settings.The interpretation of palynofacies data on APP(Amorphous organic matter-Phytoclast-Palynomorphs) diagram sugge

关 键 词：PALYNOFACIES Biomarkers ROCK-EVAL PALAEOCENE DEPOSITS Bikaner-Nagaur Basin 

分 类 号：P618.11[天文地球—矿床学]