| 青藏高原北部欧龙布鲁克地体寒武纪苗岭世古地磁研究及其构造意义 |
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| 引用本文：曹勇,孙知明,裴军令,仝亚博,李海兵,许伟,叶小舟.2025.青藏高原北部欧龙布鲁克地体寒武纪苗岭世古地磁研究及其构造意义[J].地球学报,46(6):1095-1106. |
| DOI：10.3975/cagsb.2025.032401 |
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| 基金项目:基本科研业务费专项经费(编号: DZLXJK202401)； 国家自然科学基金项目(编号: 42472297; 41930218; 42172255) |
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| 中文摘要:青藏高原北部是原特提斯洋闭合所形成的早古生代造山系, 其早古生代古地理位置对研究原特提斯洋的演化过程至关重要。欧龙布鲁克地体保存了相对连续且具有生物年代学约束的寒武纪地层, 为限定原特提斯洋演化提供了重要的窗口。本次研究对欧龙布鲁克地体寒武纪苗岭世灰岩开展了系统的古地磁采样和测试, 通过系统热退磁获得了10个采点的高温特征剩磁分量, 其构造校正后的平均方向为Ds=221.6°, Is= –40.9°, κs=87.8, α95=5.2°。高温特征剩磁分量通过了褶皱检验和倒转检验, 结合岩石磁学和显微构造分析, 认为所获得的高温特征剩磁分量为岩石形成时的原生剩磁。古地磁结果表明青藏高原北部欧龙布鲁克地体寒武纪苗岭世的古纬度为(23.4±3.8)°S(参考点: 37.2°N/96.5°E)。对比前人古地磁结果显示欧龙布鲁克地体在晚寒武世期间未发生明显的纬向运动。综合分析地质资料提出欧龙布鲁克地体在寒武纪苗岭世位于冈瓦纳大陆印度板块西北部, 原特提斯洋主要分支洋盆在晚寒武世处于南半球低纬度地区。 |
| 中文关键词:青藏高原北部 欧龙布鲁克地体 寒武纪 原特提斯洋 古地磁 |
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| Paleomagnetic Study of the Cambrian Miaolingian in the Oulongbuluke Terrane, Northern Tibetan Plateau, and Its Tectonic Implications |
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| Abstract:The northern Tibetan Plateau is an Early Paleozoic orogenic system formed by the closure of the Proto-Tethys Ocean. Understanding the Early Paleozoic paleogeographic position of terranes in the northern Tibetan Plateau is crucial for revealing the evolution of the Proto-Tethys Ocean. The Oulongbuluke terrane preserves relatively continuous and biostratigraphically constrained successions of the Cambrian strata, providing a pivotal window for constraining the evolution of the Proto-Tethys Ocean. In this study, a paleomagnetic investigation was carried out on the Cambrian Miaolingian limestone in the Oulongbuluke terrane. The site-mean direction of the 10 sampling sites was Ds=221.6°, Is= ?40.9°, κs=87.8, α95=5.2° (tilt-corrected). The characteristic remanent magnetization obtained in this study was confirmed as primary origin by fold test, reversal test, and rock magnetic and petrographic investigations. The paleomagnetic results indicate that the Oulongbuluke terrane was located at (23.4±3.8)° S during the Cambrian Miaolingian (reference site: 37.2°N/96.5°E). Comparisons with previous paleomagnetic results indicate that the Oulongbuluke terrane did not undergo significant N–S movement during the Late Cambrian. Combined paleomagnetic and geological evidence suggests that the Oulongbuluke terrane may have been located to the northwest of the Indian Plate of Gondwana during the Cambrian Miaolingian. The main branches of the Proto-Tethys Ocean were located at low latitudes in the Southern Hemisphere during the Late Cambrian. |
| keywords:Northern Tibetan Plateau Oulongbuluke terrane Cambrian Proto-Tethys ocean paleomagnetism |
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