| 华南陆块岩石圈有效弹性厚度及其构造意义 |
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| 关键词:South China Block effective elastic thickness of lithosphere geothermal state earthquakes |
| 基金项目:中国地质调查局地质调查项目(编号: DD20190012; DD20221643; DD20190016);国家自然科学基金项目(编号: 92062108; 42074099; 41630320) |
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| 摘要: |
| The Effective Elastic Thickness of Lithosphere and Its Tectonic Implications in the South China Block |
| The South China Block (SCB) has undergone multi-stage tectonic events (e.g., polymerization, fission, collision, orogeny, extension) that have led to its complex deep structure and construction. The effective elastic thickness (Te) of the lithosphere represents the response of the lithosphere to long-term flexural strength. It can reflect the deformation mechanism and thermodynamic state of the lithosphere. In this study, we applied a joint inversion of admittance and coherence for calculated the spatial variations of Te in the SCB based on topography and the crustal Bouguer gravity anomaly data. The Sichuan Basin within the Yangtze Block (YB) and its surroundings mostly corresponded to high Te (>20 km), whereas the Cathaysian Block (CB) and Jiangnan Orogenic Belt (JOB) tended to display low Te (<20 km). Moreover, the Te distribution characteristics were closely related to geothermal state and earthquakes. We analyzed the relationship of between Te and geothermal state (terrestrial heat flow and the Curie depth), earthquakes, and their tectonic implications. The results are as follows: (1) The Te had a good correlation with geothermal state parameters, but the Longmenshan fault and the JOB had a contrary correspondence between Te and terrestrial heat flow or the Curie depth. The above anomaly phenomenon may have been the disruption of the shallow crust disrupted, and the deep crust is still the craton. (2) The relationship between earthquake and Te is complicated. The Te thinner areas did not equat with the areas of high-frequency earthquake occurrences. The frequency of earthquake occurrences are related to the deep environment. The high frequency of earthquakes in the Longmenshan fault is due to the long-term interaction between the rigid strata of the upper-middle crust of the YB and Songpang-Ganzi Block. It resulting in a strong accumulation of stress and energy. The low frequency of earthquake occurrences in the CB because the crust-mantle was strongly reformation by the upwelling of deep thermal material, and has lateral distribution uneven weak strata in the crust to absorb the stress. The stronger lithospheric mechanics strength of the YB resulted in fewer earthquakes distribution. |
| LUO Fan,YAN Jia-yong,ZHANG Chong,ZHONG Ren-fu,XIE Xue-hua.2022.The Effective Elastic Thickness of Lithosphere and Its Tectonic Implications in the South China Block[J].Acta Geoscientica Sinica,43(6):771-784. |
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