Heat flow study of the Emeishan large igneous province region: Implications for the geodynamics of the Emeishan mantle plume
Heat flow study of the Emeishan large igneous province region: Implications for the geodynamics of the Emeishan mantle plume
复制标题
峨眉山大火成岩省区域的热流研究：对峨眉山地幔柱地球动力学的启示
DOI：
10.1016/j.tecto.2017.12.027
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发表时间：
2018-01
期刊：
影响因子：
2.9
通讯作者：
Q. Jiang;N. Qiu;Chuanqing Zhu
中科院分区：
文献类型：
--
作者：
Q. Jiang;N. Qiu;Chuanqing Zhu
峨眉山大火成岩省（ELIP）被广泛认为是地幔柱的产物。支持的证据包括快速侵位，大量的洪水玄武岩喷发，高地幔潜在温度的估计。一些研究表明，在峨眉山溢流玄武岩喷发之前，存在地表抬升。此外，羽流的横向范围很难限制，直径估计为800-1400公里。在这项研究中，我们分析了现今的热流数据和重建二叠纪古热流镜质体反射率和锆石（U-Th）/He热年代学数据在ELIP地区，并讨论了峨眉山地幔柱的地球动力学意义。现今的热流在内部和中间区域比在外部区域更高，平均热流从76 mW/m2减少到51 mW/m2。热史模拟结果表明，峨眉山地幔柱活动导致了异常高的古热流（90-110 mW/m2）。根据现今地球热流资料，我们可以计算出ELIP区中部存在岩石圈减薄现象，这可能是地幔柱上涌和岩浆底侵作用对岩石圈的破坏所致。二叠纪古热流异常表明地幔存在温度异常。上升的高温地幔柱和减薄的岩石圈可能是ELIP区大规模隆升的主要原因。根据地表热流异常的范围，推测峨眉山地幔柱平顶头的直径可达1600-1800 km。通过对峨眉山地幔柱热流的研究，为探讨峨眉山地幔柱的地球动力学提供了新的认识。
The Emeishan large igneous province (ELIP) is widely considered to be a consequence of a mantle plume. The supporting evidence includes rapid emplacement, voluminous flood basalt eruptions, and high mantle potential temperature estimates. Several studies have suggested that there was surface uplift prior to the eruption of the Emeishan flood basalts. Additionally, the plume's lateral extent is hard to constrain and has been variously estimated to be 800–1400 km in diameter. In this study, we analyzed present-day heat flow data and reconstructed the Permian paleo-heat flow using vitrinite reflectance and zircon (U-Th)/He thermochronology data in the ELIP region and discussed implications for the geodynamics of the Emeishan mantle plume. The present-day heat flow is higher in the inner and intermediate zones than in the outer zone, with a decrease of average heat flow from 76 mW/m2to 51 mW/m2. Thermal history modeling results show that an abnormal high paleo-heat flow of 90–110 mW/m2was caused by the Emeishan mantle plume activity. Based on the present-day heat flow data, we can calculate that there is lithospheric thinning in the central ELIP region, which may be due to the destruction of the lithosphere by mantle plume upwelling and magmatic underplating. The Permian paleo-heat flow anomaly implies that there was a temperature anomaly in the mantle. The ascending high-temperature mantle plume and the thinned lithosphere may have induced the large-scale uplift in the ELIP region. According to the range of the surface heat flow anomaly, it can be estimated that the diameter of the flattened head of the Emeishan mantle plume could have reached ~ 1600–1800 km. Our research provides new insights into the geodynamics of the Emeishan mantle plume through study of heat flow.