摘要
阿尔金山脉位于青藏高原北缘。文中主要是利用磷灰石裂变径迹测年分析，探讨阿尔金山脉的隆升和剥露过程。来自阿尔金山脉34个花岗岩、花岗闪长岩和片麻岩样品中磷灰石的裂变径迹测试结果表明，阿尔金山脉存在至少5个阶段的剥露作用，反演出阿尔金山脉具有多期次、阶段性的隆升特征，并存在差异性：EW向的阿尔金北缘拉配泉一红柳沟山体隆升-剥露时间早（61～34Ma）；NE向且未-茫崖山脉的主要隆升时间位于始新世晚期中新世（42～11Ma）；沿阿尔金（主）断裂山体的隆升-剥露最为年轻，存在三期主要的剥露作用：10．2～7．3、5．5～4．5和2．1～1．8Ma。结合区域磷灰石测年数据、区域变形事件及其阿尔金断裂走滑历史分析，推测阿尔金山脉在晚白垩世曾有过初期隆升和剥露，古近纪的剥露局限于阿尔金山脉北缘EW向的山脉，始新世晚期-中新世、上新世晚期和早更新世的山脉剥露作用遍及了青藏高原北缘山脉，8Ma是青藏高原抬升和变形的一期重要构造事件发生时间；前陆盆地和阿尔金山间盆地的沉积作用研究也显示了阿尔金山脉的隆升剥露过程与阿尔金断裂的走滑及其相关盆地沉积构造-演化具有很好的耦合关系。
The Altyn Tagh mountains define the northern boundary of the Qinghai-Tibet plateau. This paper presents apatite fission-track dating that are used to infer the uplifting and exhumation process of the mountain range. This analysis is crucial for understanding the deformation and northward growth history of the plateau during the Indo-Asian collision. Fission-track dating of apatite from 34 samples of granite, granodiorite, and gneiss produced exhumation ages ranging from 61 Ma to 1.8 Ma, and suggesting that the range experienced five stages of uplifting process during the Cenozoic, i. e. , 61-34 Ma, 42-11 Ma, 10.2-7. 3 Ma, 5.5-4. 5 Ma, and 2.1-1.8 Ma. Measurements show that uplift and exhumation of the EW-trending Lapeiquan-Hongliugou range, in the northern Altyn Tagh mountain, was initiated as early as 61 Ma, and lasted until 34 Ma. That of the NE-trending Qiemo-Mangya range occurred from the late Eocene （42 Ma） to the middle Miocene （10 Ma）. The youngest uplift and exhumation within the Altyn Tagh mountains took place near the main Altyn Tagh fault, where three exhumation events, i. e. , 10.2-7.3 Ma, 4.6-4.5 Ma, and 2.1-1.8 Ma are interpreted. Analyses of regional fission-track data, regional deformation events, and left-slip displacement of the Altyn Tagh fault, indicate that the original uplift and exhumation of the Altyn Tagh mountains probably occurred in the late Cretaeeous. Paleogene exhumation was limited to the EW-trending portion of the northern Altyn Tagh range, but three later periods of exhumation, from late Eocene to mid-Miocene （42-11 Ma）, mid-Plioeene （5.5-4.5 Ma）, and early Pleistocene （1.8-2.1 Ma）, were widespread in all mountains along the northern margin of the Tibetan plateau; and 8 Ma was one of the most important periods for the deformation and evolution of the plateau. Studies on the sedimentation in the foreland basin and intra-mountain basins suggest that mountain uplift, and sedimentation and evolution of related basins were coupled with the strike-slip motion of the Altyn Tagh fault.
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2006年第4期91-102,共12页
Earth Science Frontiers
基金
国家重点基础研究发展计划"973"项目(2001CB409808
2001CB7110013)
国家自然科学基金资助项目(40572116)
