地质学报2025，Vol.99Issue(6)：1964-1976,中插1-中插2,15.DOI:10.19762/j.cnki.dizhixuebao.2024170
华北克拉通南缘太华群变质基底剥露过程:(U-Th)/He热年代学的证据
Exhumation processes of the metamorphic basement of the Taihua Group in the southern margin of the North China Craton:Evidence from(U-Th)/He thermochronology
摘要
Abstract
Uplift and exhumation are important mechanisms of crustal thinning.Under standing the exhumation process of metamorphic basements is crucial for comprehending the lithospheric extension and destruction in the southern margin of the North China Craton since the Late Mesozoic.This study investigates the exhumation history of the Taihua Group metamorphic basement in the southern margin of the North China Craton since the Late Cretaceous using zircon and apatite(U-Th)/He thermo chronology.Thermo chronological analyses of five sample groups from the Taihua Group gneisses reveal that apatite(U-Th)/He ages range from 32.9 to 41.9 Ma and zircon(U-Th)/He ages range from 56.9 to 94.1 Ma.HeFTy modeling indicates that the Taihua Group metamorphic complex has experienced four stages of cooling and exhumation since the Late Cretaceous:① Rapid cooling from the Late Cretaceous to Paleocene(94.1～57 Ma),with a cooling rate of approximately 5.58 ℃/Ma,an exhumation rate of about 159 m/Ma,and a total exhumation of 3142 m.This phase of rapid cooling was likely a continuation of the lithospheric thinning of the North China Craton caused by the subduction rollback of the Paleo-Pacific Plate.② Slow cooling from 57 to 40 Ma,with a cooling rate of around 1.18 ℃/Ma,an exhumation rate of about 34 m/Ma,and a total exhumation of 571 m.This period of stable uplift may be due to the reorientation of the subducting Pacific Plate,reducing tectonic stress in eastern China.③ Accelerated uplift and exhumation from 40 to 30 Ma,with a cooling rate of about 4.5 ℃/Ma,an exhumation rate of 129 m/Ma,and a total exhumation of 1286 m.This phase of rapid uplift might result from the aging of the subducting Pacific Plate(as mid-ocean ridges disappeared and the age of oceanic crust entering the subduction zone increased)and the increase in subduction angle.@Slow cooling and exhumation from 30 Ma to the present,with a cooling rate of 0.167 ℃/Ma,an exhumation rate of about 5 m/Ma,and a total exhumation of 143 m.This stage of tectonic quiescence likely indicates that the southern margin of the North China Craton has moved away from the active subduction zone of the Pacific Plate.The exhumation process of the Taihua Group metamorphic basement indicates that the large-scale lithospheric thinning in the southern margin of the North China Craton during the Late Mesozoic continued into the early Cenozoic.This phase of uplift and exhumation may have been crucial for the exposure of polymetallic mineral deposits in the southern margin of the North China Craton.关键词
东秦岭/熊耳山/低温热年代学/(U-Th)/He/华北克拉通破坏Key words
East Qinling Mountains/Xiong'er Mountain/low temperature thermochronology/(U-Th)/He/destruction of the North China Craton引用本文复制引用
雷万杉,张瑞,李三忠,周明丽,王冉,张海东..华北克拉通南缘太华群变质基底剥露过程:(U-Th)/He热年代学的证据[J].地质学报,2025,99(6):1964-1976,中插1-中插2,15.基金项目
本文为国家自然科学基金面上项目(编号 42173028)、国家自然科学基金联合重点项目(编号 U22A20571)和中央高校基本科研业务费项目(编号 300102273202)联合资助的成果. （编号 42173028）
