华北克拉通东部~110Ma以来岩石圈厚度变化的岩石学约束

岩石圈演化是理解克拉通破坏过程的基础。为厘清华北克拉通破坏峰期之后岩石圈演化史，本项目拟选取碱锅、曲家屯、老虎台、乱石山子、菜园子、大西庄、栖霞和蓬莱等华北克拉通东部<~110Ma的玄武岩为研究目标，应用高精度的橄榄石斑晶成分结合全岩，识别玄武岩的源区岩性，估算玄武岩中源区为辉石岩的熔体贡献比例，定性描述~110Ma以来岩石圈厚度的相对变化；在此基础上，对由橄榄岩熔融形成的玄武岩，应用地质温压计准确限定它们形成时的岩石圈厚度，进一步约束~110Ma以来岩石圈厚度变化，完善华北克拉通东部的岩石圈演化史。本项目的预期成果，有助于理解华北克拉通破坏的深部动力学过程。

Lithospheric evolution is critical in understanding cratonic destruction process, but how the lithosphere of the North China Craton evolved after the peak time of cratonic destruction is poorly constrained. To address this issue, this project planned to select the basalts with ages of < ~110 Ma in the eastern North China Craton as objects，including basalts from Jianguo, Qujiatun, Laohutai, Luanshishanzi, Caiyuanzi, Daxizhuang, Qixia and Penglei. Using high-precision olivine compositions, together with bulk rock compositions, we try to identify their mantle source lithology, evaluate contribution of pyroxenite-derived melts in the basalts and qualitatively determine the relative variations of the lithospheric thickness after ~ 110Ma. For the peridotite-derived basalts, we will apply geothermobarometer to precisely determine the lithospheric thickness at the basalts’ formation time, further constraining the lithospheric evolution of the North China Craton. The expected results of the project will be helpful in understanding the destruction process of the North China Craton.