摘要
震旦系白云岩是当前塔里木深层油气勘探战略突破的潜在层系之一,但是受资料限制,对新元古代原型盆地和烃源岩分布仍存在较大争议。综合重磁电反演和地震解释,开展了塔里木新元古代地层分布、隆坳格局和原型盆地性质研究。地球物理位场异常和联合反演结果显示,塔西南、阿瓦提地区深层都有新元古界广泛分布。新元古代盆地呈隆-坳相间格局,塔北和中央隆起带是前寒武系继承性基底古隆起,北部裂陷带和塔西南裂陷带均以NWW向裂谷为主,纵向上呈现断-坳结构,平面上构成大型垒-堑结构,裂谷形成演化和同沉积断裂的分布与基底岩相组成以及基底断裂分布密切相关。塔里木新元古代原型盆地演化以南华纪裂谷、早震旦世断-坳转换和晚震旦世坳陷为特征,震旦纪末期柯坪运动导致短暂的地壳抬升,构造剥蚀南强北弱。在早震旦世断-坳转换过程中,由多个南华纪分散的裂谷沉降中心逐渐合拢、收缩成宽缓分布的深水凹陷区,晚震旦世伴随周缘洋盆扩张,生烃凹陷开始向大陆边缘迁移。塔西南深层古裂陷内可能发育前寒武系烃源岩,古裂陷与古隆起之间的配置关系是寒武系盐下勘探突破的关键。上震旦统台缘礁滩相和表生岩溶作用形成的规模性碳酸盐岩储集体是当前古老层系勘探的重要目标类型。
The marine carbonate layers of the upper Sinian are one of the potential targets for deep and ultra-deep oil and gas exploration in the Tarim basin. However, evolution of the Neoproterozoic prototype basin and the distribution of source rocks remains controversial or unconfirmed. Together with the joint inversion of gravity, aeromagnetic and electric data, seismic interpretation of horizons and faults were conducted to depict the framework of uplift and depression in the Tarim basin from the Nanhua to the Sinian periods. The Neoproterozoic strata were expected to be well developed in the deep of Southwest Tarim and Awati depressions based on the evidence from geophysical anomaly and joint inversion of non-seismic data. Furthermore, the seismic interpretation indicated that the Neoproterozoic depressions were distributed around the inherited Precambrian basement paleo-uplifts, with the northern subsidence zone and the southwestern Tarim subsidence zone dominated by the NWW stretched rifts. The rifts were vertically characterized by lower faulted-down depression and upper intracratonic sag, and laterally by large-scale horsts and grabens. The formation and distribution of Neoproterozoic rift basins in Tarim were genetically closely related to lithofacies composition and fault system in the basement. From rift basin in the Nanhua to intracratonic sag in the Sinian, the sedimentary deposits in Tarim changed from clastic rocks to carbonatites. The Keping Movement occurring at the end of the Sinian resulted in an ephemeral crustal uplift and cessation of sedimentation, with the denudation in South Tarim being stronger than in North Tarim. Those scattered rifting subsidence centers formed in Nanhua gradually contracted into relatively widespread hydrocarbon generation depressions in the early Sinian, and the deepwater facies for source rocks deposition became migration pathways to the continental margin of Tarim in the late Sinian. Precambrian source rocks were assumed to have developed in the paleo-rifts in deep of southwest Tarim, and the effective coordination between the Paleo-rifts and Paleo-uplifts were the key issues for the oil and gas exploration of dolomite rocks under Cambrian salt. The large-scale carbonate reservoirs formed in the reefs and shoals in platform margin, and epiphytic karst in the upper Sinian were important target types.
作者
杨鑫
赵永强
兰明杰
杨波
颜萍
焦存礼
YANG Xin;ZHAO Yongqiang;LAN Mingjie;YANG Bo;YAN Ping;JIAO Cunli(SINOPEC Petroleum Exploration and Development Research Institute,Beijing 100083,China;Key Laboratory of Petroleum Resources Research,Institute of Geology and Geophysics,Chinese Academy of Sciences,Lanzhou,Gansu 730000,China;Exploration and Development Research Institute of Northwest Branch,SINOPEC,Urumqi,Xinjiang 830011,China;School of Earth Science,Zhejiang University,Hangzhou,Zhejiang 310012,China)
出处
《地质学报》
EI
CAS
CSCD
北大核心
2021年第5期1426-1447,共22页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号41802135、U19B6003-01)
国家重大专项(编号2017ZX05005-002)资助的成果。
关键词
深层—超深层
前寒武系
古裂陷
古老烃源岩
塔里木
deep and ultra-deep layer
Precambrian
paleo-rifts
ancient source rocks
Tarim
