| 鄂尔多斯盆地长城系沉积充填格架与源区物质组成 |
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| 引用本文：张雷,王永超,李钊,魏丽娟,李涵.2026.鄂尔多斯盆地长城系沉积充填格架与源区物质组成[J].地球学报,47(4):715-732. |
| DOI：10.3975/cagsb.2025.091712 |
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| 基金项目:本文由中国石油长庆油田分公司重大科技专项“鄂尔多斯盆地地震格架大剖面综合解释与基础地质研究”(编号: 2023DZZ02)、中国地质科学院基本科研业务费专项经费(编号: JKYDM2025201)和中国地质调查局地质调查项目“鄂尔多斯东南缘区域基础地质调查”(编号: DD20242779)联合资助。 |
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| 中文摘要:鄂尔多斯盆地长城系是当前深部油气勘探的重要目标层位, 然其沉积时代、充填格架和源区物质组成方面的研究依旧较为薄弱。基于最新的钻孔资料和岩心样品, 本文针对长城系开展了岩相学、碎屑锆石测年、地层对比等工作。区域对比结果显示, 鄂尔多斯盆地长城系在岩性上具有明显的“两分”特征, 下部由基性火山岩组成, 上部由碎屑沉积岩组成, 充填格架与外围的熊耳裂谷系高度相似。根据此次测年以及前人报道的相关数据, 上部沉积岩段的底界年龄被较好地限定在1 673~1 632 Ma之间, 接近最新修订的燕辽地区长城系的最大沉积年龄。该年龄区间对应华北克拉通一次重要的非造山岩浆事件, 记录了大火成岩事件之后持续的引张过程。其余锆石构成了峰值为~1.82 Ga、2.05 Ga和2.5 Ga的3个主要年龄区间, 它们主要源自远源的阴山、太行山等外围山体以及古元古代变沉积岩的二次搬运过程, 部分可能来自盆内近源的花岗质岩体。 |
| 中文关键词:鄂尔多斯盆地 长城系 碎屑锆石测年 中元古代 物源分析 |
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| Sedimentary Filling Framework and Provenance Composition of the Changcheng System in the Ordos Basin |
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| Abstract:The Changcheng System in the Ordos Basin is currently a key target horizon for deep hydrocarbon exploration. However, research on its depositional age, filling framework, and provenance composition remains relatively limited. Based on the latest drilling data and core samples, this study has conducted petrographic analysis, detrital zircon dating, and stratigraphic correlation of the Changcheng System. Regional correlation reveals that the Changcheng System in the Ordos Basin exhibits a distinct “bipartite” lithological character, that is the lower section consists of mafic volcanic rocks while the upper section comprises clastic sedimentary rocks. This filling framework is highly similar to that of the Xionger Rift System. Combined with previous data, our new geochronological results constrain the basal age of the upper sedimentary section to 1 673~1 632 Ma, which aligns with the revised maximum depositional age of the Changcheng System in the Yanliao area. This age interval corresponds to a significant anorogenic magmatic event in the North China Craton, recording prolonged extension following a large igneous province event. The remaining zircons define three primary age peaks at ~1.82 Ga, 2.05 Ga, and 2.5 Ga. These were likely sourced from coeval granitic intrusions in the Yinshan and Taihang Mountains, as well as recycled Paleoproterozoic metasedimentary rocks. A minor contribution may derive from proximal granitoids within the basin. |
| keywords:Ordos Basin Changcheng system detrital zircon dating Mesoproterozoic provenance analysis |
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