ISSN 1009-6248CN 61-1149/P 双月刊

主管单位:中国地质调查局

主办单位:中国地质调查局西安地质调查中心
中国地质学会

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    秦岭北缘中-新生代构造隆升历史:来自现代河砂的低温热年代学约束

    Mesozoic-Cenozoic Exhumation of the Northern Margin of the Qinling Mountains: Constraints from Low-Temperature Thermochronology of Modern River Sands

    • 摘要: 恢复秦岭山脉的隆升历史对于理解板块构造驱动下大陆内部的地表变形过程以及揭示我国现今地貌格局的形成具有重要意义。笔者采用碎屑锆石、磷灰石裂变径迹对秦岭山脉中段涝峪河现今河砂进行热年代学分析。结果显示样品存在91.0~82.0 Ma、54.4~41.9 Ma和约24.9 Ma等3个主要峰值年龄。这些峰值年龄揭示了秦岭山脉晚中生代—新生代以来可能存在3期快速隆升剥露阶段。晚白垩世的年龄峰(91~82 Ma)指示了秦岭北缘受燕山运动后期的强烈陆内造山影响下的快速隆升剥露;始新世的快速冷却(54.4~41.9 Ma)指示了秦岭北缘于早新生代在太平洋俯冲或印度–欧亚板块初始碰撞背景下的伸展断陷,这与渭河盆地的初始断陷形成时间一致;渐新世末—中新世早期的快速冷却阶段(约24.9 Ma)在秦岭北缘地区被广泛报道,这可能与太平洋板块西向俯冲作用相关,并造成了秦岭北缘地区的加速伸展。

       

      Abstract: Reconstructing the exhumation history of the Qinling Mountains is crucial for understanding plate tectonics-driven surface deformation processes within continental interiors and revealing the formation of China's present-day geomorphic framework. This study employs thermochronological analysis using detrital zircon and apatite fission track dating on modern river sands from the Laoyu River in the central Qinling Mountains.The results reveal three dominant peak ages of 91.0–82.0 Ma, 54.4–41.9 Ma, and ca. 24.9 Ma in the samples. These peak ages indicate three potential rapid uplift-exhumation phases in the Qinling Mountains since the Late Mesozoic to Cenozoic: The Late Cretaceous (91–82 Ma) age peak indicates rapid uplift-exhumation of the northern margin of the Qinling influenced by the late Yanshanian intracontinental orogeny. The Eocene (54.4–41.9 Ma) rapid cooling phase reflects extensional faulting along the northern margin of the Qinling under tectonic regimes of Pacific subduction or initial India-Eurasia collision, consistent with the initial rifting timing of the Weihe Basin. The latest Oligocene to early Miocene (ca. 24.9 Ma) rapid cooling episode, widely documented in the northern Qinling region, is likely associated with westward subduction of the Pacific plate, which accelerated extensional deformation along the northern Qinling margin.

       

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