"隐伏"超高压造山带的滞后折返-一种特殊类型造山带构造解析

Mechanism of the exhumation process of deeply subducted rocks is a hot and difficult issue on the tectonic. On the basis of the structural analysis, geochronological, petrology and sedimentology works on the Late Triassic Jiaonan UHP orogenic belt, two stages of the exhumation of UHP rocks was separated. These two exhumation stages have different geodynamics. The early stage: UHP rocks, which corresponding the continental collision between North China Block and South China Block, were exhumed at the different level of the crust and made "a deep-seated UHP orogen" during the Late Triassic. It was considered as a post collisional extension tectonic with the geodynamic of the delamination of the syn-collisional thickening lithosphere. The late stage: an Early Cretaceous detachment normal fault that largely exhumed the UHP rocks to the surface with the background of regional extension tectonics on Eastern Eurasia continent with the geodynamic of lithosphere thinning or North China Craton Destruction. On account of this Early Cretaceous hysteresis exhumation, the HP-UHP exposed at the surface or placed near the surface. These two processes exhumation stages make the Jiaonan UHP orogen like an "atypical" or a "special" UHP orogenic belt. To recognize and establish the geometry and polyphase deformation on Jiaonan UHP orogenic belt and post-orogenic evolution sequence were the target of this project.

本研究以胶南超高压造山带晚三叠世和早白垩世两期伸展构造为研究对象, 围绕深俯冲岩石折返的动力学机制这一热点、难点问题, 结合野外构造地质考察和同位素年代学分析, 并辅以相关的岩石学和沉积学工作, 研究胶南地块超高压岩石两期折返的构造背景, 探讨早白垩世伸展构造对晚三叠世折返至地壳不同层次上的超高压岩石所构成"隐伏"超高压造山带滞后折返作用及构造叠加型式, 从而建立以胶南地块为代表的后造山和造山后演化序列, 了解我国东部超高压造山带造山过程横向上的不均一性, 从新的角度思考和理解超高压岩石折返的复杂动力学过程与背景.

本研究以苏鲁超高压造山带及邻近的胶东-胶北晚三叠世和早白垩世两期伸展构造为研究对象, 围绕深俯冲岩石折返的动力学机制这一热点、难点问题, 结合野外构造地质考察和同位素年代学分析, 并辅以相关的岩石学和沉积学工作, 研究胶南地块超高压岩石两期折返的构造背景, 探讨早白垩世伸展构造对晚三叠世折返至地壳不同层次上的超高压岩石所构成“隐伏”超高压造山带滞后折返作用及构造叠加型式, 从而建立以胶南地块为代表的后造山和造山后演化序列, 解析我国东部超高压造山带造山过程横向上的不均一性, 从新的角度思考和理解超高压岩石折返的复杂动力学过程与背景.