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| 基金项目：国家自然科学基金项目“龙门山冲断带构造分段变形机制研究”（41002072），油气资源与探测国家重点实验室开放课题基金项目“川北碧口地块中生代以来构造隆升的热年代学研究”（PRP/open-1307） |
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| 摘要： |
| 青藏高原具有复杂的构造演化特征，该地区自中、新生代以来的构造隆升和构造演化机制一直是地质研究的热点。为精细刻画青藏高原板块、华北板块和华南板块之间的拼合关系及差异性隆升特征，对位于青藏高原东北端的碧口地块进行了磷灰石和锆石裂变径迹测试，以及热史模拟和岩石冷却速率计算。结果锆石和磷灰石裂变径迹年龄分别在（118±5～265±29）Ma和（29.0±2.7～54.0±7.0）Ma之间；碧口地块东北缘及北缘冷却速率接近，在3.125～3.448 ℃/Ma之间，东缘冷却速率相对较低，为2.041～2.273 ℃/Ma。结果表明，中、新生代以来，碧口地块及其周缘总体上经历了持续隆升过程，但不同地区隆升特征具有差异性：碧口地块北侧在早、中侏罗世（151±7）Ma经历了构造挤压和隆升过程；东部相对较晚，在晚侏罗世（143±11）Ma经历了构造隆升阶段；东北端在早白垩世才与华北板块拼接并进入持续构造隆升阶段。进入古近纪（54.0±7.0）Ma隆升阶段，即始新世早期后，碧口地块东缘在始新世中后期（44 Ma）开始发生构造隆升，北缘自渐新世中晚期（29～32 Ma）开始发生显著的构造隆升。上述区域在10 Ma（中新世晚期）共同进入快速隆升阶段。 |
| 关键词：磷灰石 锆石 裂变径迹 热史模拟 碧口地块 青藏高原 |
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| Abstract: |
| Characterized by complex tectonic evolution, the tectonic uplift and tectonic evolution mechanism in the Qinghai-Tibet Plateau since Meso-Cenozoic have been the focus of geological research. To accurately describe the splicing relationship and differential uplift characteristics among the Qinghai-Tibet Plateau plate, North China plate, and South China plate, the apatite and zircon fission track tests, thermal history simulation and rock cooling rate calculation were carried out on the Bikou block located in the northeastern end of the plateau. The results show that the zircon fission track ages range from (118±5) Ma to (265±29) Ma, the apatite fission track ages range from (29.0±2.7) Ma to (54.0±7.0) Ma. The cooling rates of the northeastern margin and the northern margin of the Bikou block are close, ranging from 3.125 ℃/Ma to 3.448 ℃/Ma, while the cooling rates of the eastern margin are relatively low, ranging from 2.041 ℃/Ma to 2.273 ℃/Ma. The results show that the Bikou block and its periphery have experienced continuous uplift since the Meso Cenozoic, but the uplift characteristics are different in different regions. The northern side of the Bikou block experienced tectonic compression and uplift in the Early and Middle Jurassic (151±7) Ma. The eastern part experienced tectonic uplift relatively late in the Late Jurassic (143±11) Ma. In the Early Cretaceous, the northeast end joined with the North China plate and began its continuous tectonic uplift. Upon entering the Paleogene uplift stage (54.0±7.0) Ma, that is, the early Eocene, the eastern margin of the Bikou block began to rise in the middle and late Eocene (44 Ma), and the northern margin began to rise remarkably in the middle and late Oligocene (29-32 Ma). The above areas entered a rapid uplift stage together at 10 Ma (late Miocene). |
| Keywords:apatite zircon fission track thermal history simulation Bikou block Qinghai-Tibet Plateau |
| 金文正，白万奎，叶治续.碧口地块东-北缘中、新生代构造隆升及演化：来自磷灰石和锆石裂变径迹的证据[J].地质学刊,2023,47(3):231-241 |
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