| 柴达木盆地东缘中新世盆山系统演化与构造古地貌重建 |
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| 引用本文：王永超,陈宣华,邵兆刚,余苇,苏和.2021.柴达木盆地东缘中新世盆山系统演化与构造古地貌重建[J].地球学报,42(1):43-54. |
| DOI：10.3975/cagsb.2020.062901 |
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| 基金项目:中国地质调查项目(编号: DD20190011);中国地质科学院基本科研业务费专项经费(编号: YWF201908);国家自然科学基金(编号: 41902116) |
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| 中文摘要:柴达木盆地东缘毗邻柴北缘断裂带与鄂拉山构造带的交接部位, 其中新世盆地充填过程为正确认识周缘山脉隆升剥露历史提供了有效约束。本文以乌兰和查查盆地为例, 通过沉积地层学研究与物源分析, 刻画了柴东地区中新世2个阶段的构造地貌演化历史。中新世早期, 乌兰盆地表现为典型的山间挠曲盆地, 主要充填辫状河—三角洲沉积体系, 其源区为盆地北侧持续抬升的柴北缘断裂带, 与鄂拉山地区无明显关联; 查查盆地属于典型的背驮盆地, 并以稳定的辫状河道沉积为显著特征, 其汇水系统起源于柴北缘断裂带中段(甚至西段), 向东流经牦牛山地区后, 最终汇入共和盆地。因此, 该时期鄂拉山并未显著抬升, 即柴东与共和盆地隶属统一的前陆盆地系统。至中晚中新世, 在区域性左旋剪切作用的驱使下, 包括鄂拉山在内的周缘山脉近于同时抬升, 使得乌兰盆地脱离共和盆地成为封闭的欠补偿湖盆。与此同时, 牦牛山断裂剧烈活动导致查查盆地所在地区整体抬升, 从而缺失同时代地层沉积。 |
| 中文关键词:柴达木盆地东缘 乌兰盆地 中新世 油砂山组 物源分析 构造地貌 |
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| Miocene Evolution of the Basin-mountain System and Paleogeomorphic Reconstruction in the Easternmost Qaidam Basin |
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| Abstract:The easternmost Qaidam Basin adjoins the intersection of the North Qaidam fault system (NQF) and the Elashan structural belt (ESB). The infilling process of Miocene sedimentary basins developed in this area must provide constraints on the uplifting history of their peripheral mountain belts. The well-preserved Wulan and Chacha basins were studied by sedimentology and provenance analysis, revealing two-stage geomorphic evolution history during the Miocene in the study area. At the first stage (~20–15 Ma), the Wulan basin performed as a typical intermountain flexural basin and mainly consists of braided river and delta depositional associations. These sediments were mainly fed by the persistently unroofed NQF, which means that another potential source area of the ESB had not yet been notably exhumed. By contrast, the Chacha basin is considered as a piggy-back basin and accommodated a stable braided river depositional system. These sediments were transported by eastward-flowing longitudinal rivers that originated from the western part of NQF and finally flowed into the Gonghe basin via the Maoniushan region. All these information supports the idea that the eastern Qaidam basin was once connected with the Gonghe basin during the early Miocene. At the second stage (~15–8 Ma), responding to the regional left-lateral shearing, the peripheral mountain belts of the Wulan basin, especially the ESB, uplifted simultaneously. This event broke the previous unified basin system and made the Wulan basin grade into a relative walled setting. Meanwhile, the intense activity of the Maoniushan fault led to the region where the Chacha basin occupied uplifted integrally, which seems to have been responsible for the absence of the coeval sediments. |
| keywords:eastern Qaidam basin Wulan basin Miocene Youshashan Formation provenance analysis structural geomorphy |
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