摘要
重点报道了藏北高原双湖地区早侏罗世海相油页岩和可可西里地区中新世陆相油页岩生物标志化合物组合差异。在两套油页岩中均检出丰富的正构烷烃、类异戊二烯烷烃、萜类化合物及甾类化合物,但二者生物标志化合物组合明显不同。这种不同是在有机质演化程度差异的基础上,主要由原始生物输入和沉积环境差异造成的。海相油页岩正构烷烃具有低碳数优势,nC15、nC16或nC17为主峰碳,无明显的奇偶碳数分布,Pr/Ph比值显示,多数海相油页岩具有姥鲛烷优势,缺乏β-胡萝卜烷,伽马蜡烷含量较低,海相油页岩原始有机母质构成中,既有丰富的菌藻类等低等水生生物,还有一定比例的陆生高等植物混合输入的特点,属贫氧—缺氧、弱氧化—弱还原沉积环境,进一步证明了早托尔期这种富碳缺氧黑色油页岩是一次全球性海平面上升事件的产物。陆相油页岩正构烷烃具有高碳数优势,主峰碳数为nC23或nC29,奇碳数优势突出,Pr/Ph比值显示,陆相油页岩具有强烈植烷优势,β-胡萝卜烷含量相对较高,伽马蜡烷/αβC30霍烷比值为0.31～0.60,陆相油页岩原始有机母质构成中,既有高含量的高等陆生植物,还有一定数量低等水生生物混合输入,且在剖面序列中有由早期C3型陆生高等植物向晚期C4型转变,特别是剖面顶部油页岩中具有丛粒藻Botryococus输入的特点,从?
Abundant biomarkers,including n-alkanes,isoprenoid,steranes an d terpanes,are detected by GC-MS from the Lower Jurassic marine oil sh ales i n Shuanghu area and Miocene con tinental oil shales in Hoh Xil area,t he Zangbe i Plateau.The biomarker comb inations in both areas have distinct differences, and are in close relationship with organic matter import and sedim entary enviro nment.The n-alkanes of marine oil shales show a d ominance of low carbon molec ular components with highest peaks of nC 15 ,nC 16 or nC 17 .OEP values of the n-alkanes show no odd-even carbon dominance.Pr/Ph r a tios indicate most marine oil shales possess pristine dominance.There a re al so short ofa-carotene in marine oil shales,with low abundance gammacerane.Al l these biomarkers characteristics indicate organic matters in marine oil shales are of alg ae origin,with proper contribution from terrestrial plant.Biomarke rs para meters also reflect that deposition al environment under low oxygen or a n oxic condition,with weak oxidation or we ak reduction.It documents that the e arly Toarcian anoxic organic-rich b lack oil shale is a global event controll ed by sea level change.The n-alkanes of continental oil shales h ave a dominan ce of high carbon number,with nC 23 or nC 29 as the highest peaks.OEP values show that n-alkanes possess outstanding od d carbon number distribution.Pr/Ph ratios show that continental oil s hales h ave phytane dominance.a-carotene abundance is relatively high and ratios of g ammacerane/áaC 30 hop range from 0.34to 0.60.All these biomarker characteristics refl ect organic ma tters are of terrestrial plant (early stage C 3-type,later period C 4-type)origin,with proper import of algae.Especially,the upper part of c ontinental oil shales in section sequence possesses ab undant Botryococus impor t.This special plant import re sults in abnormity of? 13 C.Biomarkers parameters also indic ate oxygen deficiency and reduction dep ositional environment of continent al oil shales.It reflects that lacustrine ec osystem were
出处
《地球化学》
CAS
CSCD
北大核心
2004年第1期57-64,共8页
Geochimica
基金
国家重点基础研究发展计划项目(G1998040801-5)
中国科学院有机地球化学国家重点实验室项目资助(OGL-9703)
关键词
油页岩
生物标志化合物
有机质输入
沉积环境
biomarkers contrast
organic matt e r import
depositional environment
marine oil shales
continental oil shales
Zangbei Plateau
