鄂尔多斯盆地延长组长7段烃源岩中磷酸盐化的浮游绿藻化石  

PHOSPHATIZED PLANKTONIC GREEN ALGAE FOSSILS IN THE SOURCE ROCKS OF THE CHANG 7 MEMBER OF THE YANCHANG FORMATION IN THE ORDOS BASIN

作　　者：甘德祥 卞从胜[2,5] 杨伟伟 刘丽静[1,5] 董劲 庄蔚菱 李永新 王建强[1,5] GAN Dexiang;BIAN Congsheng;YANG Weiwei;LIU Lijing;DONG Jin;ZHUANG Weiling;LI Yongxin;WANG Jianqiang(State Key Laboratory of Continental Dynamics,Department of Geology,Northwest University,Xi'an 710069;China Institute of Petroleum Exploration and Development,Xi'an 710069;Petro China Changqing Oilfield Company Exploration and Development Research Institute,Xi'an 710069;National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,PetroChina Changqing Oilfield Company,Xi'an 710069;Academician Zhao Wenzhi Studio of Northwest University,Beijing 100083)

机构地区：[1]大陆动力学国家重点实验室,早期生命与环境陕西省重点实验室,西北大学地质学系,西安710069 [2]中国石油勘探开发研究院,西安710069 [3]中国石油长庆油田公司勘探开发研究院,西安710069 [4]中国石油长庆油田公司低渗透油气田勘探开发国家工程实验室,西安710069 [5]西北大学赵文智院士工作室,北京100083

出　　处：《微体古生物学报》2023年第4期327-349,共23页Acta Micropalaeontologica Sinica

基　　金：国家自然科学基金项目(Grant Nos.42072127,41930319,41972143,41890844,42172014,42272006);国家自然科学基金企业创新发展联合基金集成项目《中低成熟度陆相页岩油资源形成与原位转化开采机理编号:U22B6004》;中石油勘探开发研究院的院级课题《典型陆相中高熟页岩油富集特征与富集区评价编号:2022yjcq03》联合资助;中国石油勘探开发研究院资助。

摘　　要：浮游藻类如绿藻、沟鞭藻、疑源类、硅藻等为具有强大初级生产力的营浮游生活的光合自养型原生生物,因其具有极强的生油能力,是主要的成烃生物。鄂尔多斯盆地三叠系延长组长73段是重要的烃源岩,其中的浮游藻类化石一直备受关注。本文使用偏光显微镜、荧光显微镜、扫描电镜及能谱分析仪对来自鄂尔多斯盆地正75GC-1井和高135井中三叠纪延长组长7_(3)段的216张烃源岩样品的薄片进行了观察,在其中发现了4种数量丰富的磷酸盐保存的球状微体化石:类型Ⅰ和类型Ⅱ微体化石大小为18~30μm,单核单细胞,化石周围可见较为清晰的膜壳;类型Ⅲ大小为80~120μm,化石周围具有膜壳,膜壳较清晰,内部可见大量2~14μm大小的磷酸盐化小圆球体;类型Ⅳ微体化石大小为90~120μm,具膜壳或不具,内部为大量2~18μm的磷酸盐化微米级群体充填。对化石形态和埋藏学分析认为它们是浮游绿藻化石在胶被结构、细胞结构及细胞群体尚未完全分解前被富含磷酸盐的流体渗透矿化作用形成的。经过与化石绿藻和现生绿藻的广泛对比,将其归属于绿藻门绿藻纲团藻目衣藻科、团藻科以及绿球藻目卵囊藻科,分别建立为4个新属,4个新种:球状拟鞭藻Pseudocarteria globuloesis gen.et sp.nov.、椭球状拟衣藻Parachlamydomonas ellipasis gen.et sp.nov.、椭球状拟空球藻Paraeudorina spheroesis gen.et sp.nov.和卵状拟球囊藻Paraoocystis ovalsis gen.et sp.nov.。延长组中这些化石的发现进一步丰富了中晚三叠世浮游绿藻多样性的认识,并极大提升了对鄂尔多斯盆地延长组长7_(3)段深湖相烃源岩可能的生油母质的认识。Phytoplankton such as green algae,dinoflagellates,acritarchs and diatoms are the photosynthetic autotrophic protozoa with a strong primary productivity.They are the main hydrocarbon-forming organisms because of their strong oil-generating capacity.The Middle Triassic Chang 7_(3) member of the Yanchang Formation in the Ordos Basin is an important source rock.The planktonic algae fossils have attracted much attention.In this paper,we used polarized microscope,fluorescence microscope,scanning electron microscope and energy spectrum analyzer to observe about 216 thin sections of the source rock samples from the Chang 7_(3) Member of Well Zheng 75GC-1 and Well Gao 135 in the Ordos Basin.The abundant phosphatic spherical microfossils include four kinds:Type I and Type II microfossils are 18~30 μm in size,single-celled,clear walls and cores seen in the fossils;The size of type Ⅲ is 80~120 μm,while the fossil is surrounded by a relatively clear membrane wall,with a large number of 2~14 μm phosphonated small spheres seen inside.Type Ⅳ microfossils are 90~120 μm in size with or without a membrane wall,with a large number of 2~18 μm phosphatated micron groups filled inside.Analysis of fossil morphology and taphonomy suggested that they were formed by the osmotic mineralization of the fossil planktonic green algae through the phosphate fluids before the enveloped structure,cellular structure,and cellular groups were fully decomposed.After analysis of fossil morphology and taphonomy,it was assigned to Chlamydomonadaceae,Volvocaceae and Oocystaceae,and four new genera and four new species were established:Pseudocarteria globuloesis gen.et sp.nov.,Parachlamydomonas ellipasis gen.et sp.nov.,Paraeudorina spheroesis gen.et sp.nov.,Paraoocystis ovalsis gen.et sp.nov.The discovery of these fossils in the Yanchang Formation further enriches the understanding of the diversity of planktonic green algae in the Middle-Late Triassic,and greatly enhances the understanding of the possible source of the kerogen of the Chang 7_(3) me

关 键 词：微体化石 磷酸盐化 浮游绿藻 胶磷矿 长7_(3)段 三叠系 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]