The coupling control of biological precursors and environmental factors onβ-carotane enrichment in alkaline lacustrine source rocks:A case study from the Fengcheng formation in the western Junggar Basin,NW China

作     者：Mao-Guo Hou Ming Zha Hua Liu Hai-Lei Liu Jiang-Xiu Qu Ablimit Imin Xiu-Jian Ding Zhong-Fa Jiang 

作者机构：School of GeosciencesChina University of PetroleumQingdaoShandong266580China Research Institute of Exploration and DevelopmentXinjiang Petroleum Administration BureauKaramayXinjiang834000China 

出 版 物：《Petroleum Science》 (石油科学（英文版）)

年 卷 期：2024年第21卷第2期

页      面：836-854页

核心收录：

学科分类：0820[工学-石油与天然气工程] 0709[理学-地质学] 07[理学] 070901[理学-矿物学、岩石学、矿床学] 

基　　金：financial support from the National Key Research and Development Program of China(2019YFC0605502) the National Natural Science Foundation of China(42302156) the Major Projects of Petro China Science and Technology Fund(2021DJ0206) the Natural Science Foundation of China University of Petroleum(22CX06046A)。 

主　　题：β-carotane enrichment Cyanobacterial input Environmental impact Alkaline lacustrine source rocks The Fengcheng formation 

摘      要：The organic-rich mudstones and dolostones of the Permian Fengcheng Formation(Fm.)are typically alkaline lacustrine source rocks,which are typified by impressively abundantβ-carotane.Abundantβ-carotane has been well acknowledged as an effective indicator of biological sources or depositional environments.However,the specific biological sources ofβ-carotane and the coupling control of biological sources and environmental factors on the enrichment ofβ-carotane in the Fengcheng Fm.remains obscure.Based on a comprehensive investigation of the bulk,molecular geochemistry,and organic petrology of sedimentary rocks and the biochemistry of phytoplankton in modern alkaline lakes,we proposed a new understanding of the biological precursors ofβ-carotane and elucidated the enrichment mechanism ofβ-carotane in the Fengcheng Fm.The results show that the biological precursors crucially control the enrichment ofβ-carotane in the Fengcheng Fm.The haloalkaliphilic cyanobacteria are the primary biological sources ofβ-carotane,which is suggested by a good positive correlation between the2-methylhopane index,7-+8-methyl heptadecanes/C_(max),C_(29%),andβ-carotane/C_(max)in sedimentary rocks and the predominance of cyanobacteria with abundantβ-carotene in modern alkaline lakes.The enrichment ofβ-carotane requires the reducing condition,and the paleoredox state that affects the enrichment ofβ-carotane appears to have a threshold.The paleoclimate conditions do not considerably impact the enrichment ofβ-carotane,but they have some influence on the water s paleosalinity by affecting evaporation and precipitation.While it does not directly affect the enrichment ofβ-carotane in the Fengcheng Fm.,paleosalinity does have an impact on the cyanobacterial precursor supply and the preservation conditions.