摘要
四川盆地德阳-安岳震旦纪裂谷周缘发现了我国最大的震旦系气田,但由于缺乏地质资料、地震资料分辨率低,是否发育前震旦纪裂谷存疑,裂谷成因研究对开拓超深层勘探领域具有重要意义。本文在地震构造解析的基础上,综合区域地质资料与锆石Hf同位素分布特征分析,探讨四川盆地前震旦纪裂谷成因机制。研究结果表明:①四川盆地存在前震旦纪北东向深大裂谷,其分布与结构不同于震旦纪坳陷,而且存在前震旦纪构造间断;②新元古代岩浆锆石εHf值呈现先降低后升高的分布趋势,并在约830~780 Ma出现俯冲构造转换期;③四川盆地发育转换俯冲作用下的南华纪裂谷体系,不同于地幔柱机制与俯冲机制的裂谷模式。结论认为,四川盆地存在受控于转换俯冲机制的北东向广泛分布的前震旦纪裂谷体系,值得进一步研究与勘探。
The Neoproterozoic supercontinent breakup played a significant role in the origin of rift basins and their associated hydrocarbon systems on Earth.However,the trigger for this rifting,whether a superplume or a subduction process,remains debated.The Deyang-Anyue rift in the Sichuan basin,which hosts Chinas largest Sinian gas field,provides a key area for this investigation.Due to the lack of geological data and low-resolution seismic imaging,the origin and distribution of pre-Sinian rifts in ultradeep subsurface settings remain enigmatic.By integrating seismic interpretation with compiled geochemical data,this study examines the characteristics and formation mechanism of the pre-Sinian rifts in the Sichuan basin.Our results show that:①Well-developed,NE-trending pre-Sinian rifts,with deposits exceeding 5000 m in thickness,are present throughout the basin.Their architecture and distribution differ significantly from the Sinian depression,indicating a pre-Sinian tectonic discontinuity.②εHf values in Neoproterozoic zircons show a distinct shift from a decreasing to an increasing trend,marking a tectonic transition period at ca.830~780 Ma.③The pre-Sinian rifting,which initiated during this transition period,is consistent with a subduction process rather than a mantle plume.In conclusion,the mid-Neoproterozoic transitional subduction has resulted in the distributed deep pre-Sinian rifts in the Sichuan basin,which represent a new,favorable hydrocarbon exploration frontier.
作者
唐浩
邬光辉
温银宇
苏琛
代兰
邹禺
陶夏妍
马兵山
TANG Hao;WU Guanghui;WEN Yinyu;SU Chen;DAI Lan;ZOU Yu;TAO Xiayan;MA Bingshan(School of Geoscience and Technology,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Qiangtang Basin Research Institute,Southwest Petroleum University,Chengdu,Sichuan 610500,China;PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China)
出处
《地质学报》
北大核心
2025年第7期2451-2462,共12页
Acta Geologica Sinica
基金
国家自然科学基金项目(编号U24B2019,42241202)
四川省自然科学基金项目(编号2024NSFSC0814)联合资助的成果。
关键词
四川盆地
前震旦纪
大陆裂谷
HF同位素
俯冲作用
勘探
Sichuan basin
pre-Sinian
continental rift
Hf isotope
subduction process
exploration
