塔里木板块北部轮南油田中-晚奥陶世之交海进序列的岩相特征  

TRANSGRESSIONAL SEQUENCES THROUGHOUT THE MIDDLE TO UPPER ORDOVICIAN TRANSITION IN THE LUNNAN OIL FIELD, NORTHERN TARIM BLOCK

作　　者：张园园[1] 李越[1] ZHANG Yuan-yuan;LI Yue(State Key Laboratory of Paleobiology and Stratigraphy,Nanjing Institute of Geology and Palaeontology and Center for Excellence in Life and Paleoenvironment,Chinese Academy of Sciences,Nanjing 210008)

机构地区：[1]中国科学院南京地质古生物研究所和生物演化与环境卓越创新中心,现代古生物学和地层学国家重点实验室,江苏南京210008

出　　处：《地层学杂志》2020年第1期12-21,共10页Journal of Stratigraphy

基　　金：自然科学基金青年基金(750100509);中国科学院战略性先导科技专项(B类,XDB26000000)联合资助。

摘　　要：本文分析轮南油田中奥陶统一间房组-上奥陶统吐木休克组灰岩生物多样性、沉积序列和时空展布,显示水深加大是控制地层分界上下岩相-生物相变化的主要因素。中奥陶统一间房组台地相沉积期,水体深度多在正常浪基面附近,岩性以中-高能滩相的砂屑生屑灰岩、砂屑灰岩为主并伴有小型台缘礁。从一间房组上部到上奥陶统吐木休克组,生物相-岩相有明显变化,总体表现为水体加深。吐木休克组发育深水缓斜坡型灰岩沉积,向南连接满加尔凹陷,红色灰岩岩性变化小,生屑和内碎屑含量少,灰泥含量显著增加。轮南油田中-晚奥陶世经历了一次从浅海台地演变为沉没台地的持续性海进过程,其岩相转换的时间节点基本与塔里木板块西北巴楚露头区一致,均发生在整合接触的中奥陶统一间房组-上奥陶统吐木休克组界线附近。Sedimentary sequences and their temporal and spatial patterns throughout the carbonate succession of the Middle Ordovician Yijianfang Formation and Upper Ordovician Tumuxiuke Formation in the Lunnan Oil Field are outlined. An increase in depth of the sea floor is considered to be the key mechanism triggering bioand lithofacies turnover around the stratigraphic boundary. Intra-and bioclastic banks with small-scale reefs of the platform margin of the Yijianfang Formation were mainly deposited on a mid-to high-turbulent platform with depth around the fair-weather wave-base. Micritic components essentially increase from the upper Yijianfang Formation to the Tumuxiuke Formation, the latter having been deposited on a deeper ramp toward the southern Manjiaer Depression. Bioclasts and other intraclasts are sparse throughout the Tumuxiuke Formation. The Middle to Late Ordovician transition corresponds to a transgressive systems tract resulting in a change of the geographic pattern from platform margin to a flooded platform. The gradual sea-level rise was regional, occurring on equivalent carbonate platforms of the northern Lunnan Oil Field and the northwestern Bachu outcrop of the Tarim Block.

关 键 词：灰岩 海进 奥陶系 轮南油田 塔里木板块 

分 类 号：P534.42[天文地球—古生物学与地层学]