Permian Source-to-Sink Processes and Paleogeographic Reconstruction in the Northern Ordos Basin and Its Periphery
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摘要:
【目的】二叠纪为鄂尔多斯盆地北部构造-沉积转换的关键时期,精细刻画其复杂源-汇过程对于揭示多物源差异供给特征及古地理演化具有重要意义。【方法】本研究通过露头观测、钻测井资料、碎屑锆石U-Pb定年,系统分析鄂尔多斯盆地北部物源信号与沉积充填过程,明确源-汇系统约束下的古地理格局其对古亚洲洋闭合过程的启示。【结果】(1)碎屑锆石U-Pb定年揭示了阿拉善地块、兴蒙造山带及华北克拉通基底在二叠纪各时期均不同程度提供物源且东西差异明显:从太原期西部混源、东侧基底主导,到山西期西侧阿拉善地块与东侧基底共同增强,再到石盒子期基底供源全面增强。基于各组分的东西性将盆地北物源区命名为阿拉善、阴山西段与东段。(2)二叠纪沉积体系由潮控三角洲向辫状河三角洲演化,沉积厚度与砂体展布呈现西厚东薄、北强南弱的格局。物源供给强度与沉积环境变化密切相关,山西组和石盒子组沉积期砂体横向连续性较太原组增强,反映强物源输入背景下的辫状河道发育。(3)源-汇过程分析表明,太原期以近源弱供给沉积为主;山西期物源混合增强,形成东西分异的沉积格局;石盒子期华北克拉通基底隆升显著,物源供给以远源为主,砂体厚度与展布范围达到最大。【结论】古亚洲洋俯冲/闭合的非均匀性驱动兴蒙造山带西强东弱与华北克拉通基底东强西弱的差异性隆升,控制盆地北部物源呈现“西部混源、东部克拉通基底”的东西分异格局及演化,太原期至石盒子期沉积体系从海陆过渡的潮控三角洲向陆相辫状河三角洲转型。【意义】基于源-汇过程的鄂尔多斯盆地北部古地理演化模式,为明确多物源-沉积响应机制及大型克拉通盆地油气勘探提供了动态源-汇耦合模型。
Abstract:[Objective] The Permian represents a critical period of tectonic-sedimentary transition in the northern Ordos Basin. A detailed characterization of its complex source-to-sink processes is essential for revealing multi-provenance differential supply patterns and paleogeographic evolution.[Methods] This study systematically analyzes provenance signals and sedimentary filling processes in the northern Ordos Basin through outcrop observations, well-logging data, and detrital zircon U-Pb geochronology, aiming to clarify the paleogeographic framework constrained by source-to-sink systems and its implications for the closure of the Paleo-Asian Ocean. [Results](1) Detrital zircon U-Pb ages reveal that the Alxa Block, Xing-Meng Orogenic Belt, and North China Craton contributed differentially during the Permian, with marked east-west variations. Multidimensional scaling (MDS) analysis divides the northern basin into three provenance zones: Alxa, western Yinshan, and eastern Yinshan. (2) The Permian depositional systems evolved from tide-dominated deltas to braided-river deltas, with sediment thickness and sandbody distribution showing a "thicker in the west and stronger in the north" pattern. Provenance supply intensity closely correlated with environmental changes. Enhanced lateral continuity of sandbodies in the Shanxi and Shihezi Formations reflects braided channel development under strong sediment supply.(3) Source-to-sink analysis indicates:Taiyuan Stage: Dominated by proximal weak supply.Shanxi Stage: Increased provenance mixing formed an east-west differentiated depositional pattern.Shihezi Stage: Significant uplift of the North China Craton basement led to dominant distal supply, with maximum sandbody thickness and spatial extent. [Conclusions]The inhomogeneity of the subduction/closure of the Paleo-Asian Ocean drove the differential uplift characterized by "strong in the west and weak in the east" in the Xing'an-Mongolian Orogenic Belt and "strong in the east and weak in the west" in the basement of the North China Craton. This controlled the east-west differentiation pattern and evolution of the provenance in the northern part of the basin, which showed "mixed provenance in the west and cratonic basement in the east". The sedimentary system transformed from a tide-dominated delta in the marine-continental transitional environment to a continental braided river delta from the Taiyuan Stage to the Shihezi Stage. [Significance] The established paleogeographic evolution model, based on source-to-sink processes, provides a dynamic coupling framework for understanding multi-provenance-sedimentation responses and hydrocarbon exploration in large cratonic basins.
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Key words:
- Detrital zircon /
- provenance analysis /
- northern Ordos Basin /
- paleogeographic framework /
- Permian
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附加数据:碎屑锆石LA-ICP-MS U-Pb测年分析结果.docx
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