松辽盆地青山口组页岩沉积水体环境演变的古生物学证据  

Paleobiological evidence of the paleowater environment evolution during deposition of the Qingshankou shale in the Songliao Basin

作　　者：吕丹 王华建[1] 李罡[2] 张江永[3] 付秀丽 刘畅[1] 王晓梅[1] 朱如凯[1] 张水昌[1] LYU Dan;WANG Huajian;LI Gang;ZHANG Jiangyong;FU Xiuli;LIU Chang;WANG Xiaomei;ZHU Rukai;ZHANG Shuichang(Research Institute of Petroleum Exploration&Development,PetroChina,Beijing 100083,China;Nanjing Institute of Geology and Paleontology,Chinese Academy of Sciences,Nanjing,Jiangsu 210008,China;Institute of Vertebrate Paleontology and Paleoanthropology,Chinese Academy of Sciences,Beijing 100044,China;Petroleum Exploration and Development Research Institute of Daqing Oilfield,PetroChina,Daqing,Heilongjiang 163412,China)

机构地区：[1]中国石油勘探开发研究院,北京100083 [2]中国科学院南京地质古生物研究所,江苏南京210008 [3]中国科学院古脊椎动物与古人类研究所,北京100044 [4]中国石油大庆油田有限责任公司勘探开发研究院,黑龙江大庆163412

出　　处：《石油与天然气地质》2023年第4期857-868,共12页Oil & Gas Geology

基　　金：国家自然科学基金项目(72088101);中国石油勘探开发研究院院级项目(2021ycq01,yjkt2019-3);黑龙江省揭榜挂帅项目(2022-JS-1740,2022-JS-1853)。

摘　　要：松辽盆地古龙页岩油勘探开发目的层和有利区优选对页岩沉积水体环境恢复提出了新要求。以古生物群落作为古湖泊水体环境演变的示踪指标,对古页8HC井白垩系青山口组古生物组合(包括鱼、叶肢介、介形类、藻类)进行了系统分析。研究发现,满洲鱼和叶肢介仅出现在Q7油层,丰度高但属种单一;介形类在Q7—Q9油层的种属数目和丰度相较于Q1—Q6油层均显著增加;沟鞭藻丰度在Q1,Q2和Q7油层存在3个峰值。古生物组合指示松辽盆地青山口组沉积期整体为淡水-微咸水的古湖泊环境;Q7油层中生物多样性的显著增加和沟鞭藻的峰值丰度,则指示比较明确的海侵事件;Q1和Q2油层的沟鞭藻峰值丰度可能指示了湖平面上升初期的海侵事件。通过与现代马拉开波湖的对比,提出松辽盆地青山口组沉积期虽出现了海洋生物,但海侵可能只是在独特古地理位置和气候背景下的暂时性或偶发性湖-海连通,并未显著改变松辽古湖泊整体的水体属性和生态组成。Identification of target intervals and delineation of favorable areas for exploration and development of the Gulong shale oil require better reconstruction of the paleowater environment during deposition of the shale of interest.Paleontological communities were used as indicators to trace the paleowater environment of ancient lakes to perform a comprehensive analysis of paleotological evidence(including fish,clam shrimp,ostracoda and algae)of the Qingshankou Formation from the Well GY8HC.The results show that Manchurichthys and clam shrimp only occur in the Q7 oil layer with large abundance but single species.Compared with the lower Q1—Q6 oil layers,there is a significant increase in the species and abundance of ostracods in the upper Q7—Q9 oil layers.Three abundance peaks of dinoflagellate fossils appear in Q1,Q2 and Q7 oil layers.The biological assemblage indicates a whole freshwater-brackish water feature of the Songliao Basin during the deposition of the Qingshankou Formation.The significant increase in diversity of fossil record and peak abundances of dinoflagellate fossils in Q7 oil layer indicates relatively definite marine transgression events,while the abundance peaks of dinoflagellate fossils in Q1 and Q2 oil layers suggest possible marine transgression event(s)in the early stage of lake-level rising.Through the comparison with the modern Maracaibo Lake,it is proposed that the appearance of marine organisms in the paleo-Songliao Lake during the deposition of the Qingshankou Formation might be the result of temporary or occasional lake-sea connection under unique paleogeographic and climatic backgrounds.However,the lake-sea connection did not cause any obvious change in the nature of water body and the components of ecosystem.

关 键 词：古水体环境 海侵事件 古生物 黑色页岩 青山口组 松辽盆地 

分 类 号：TE121.3[石油与天然气工程—油气勘探]