大别造山带中新生代隆升作用的时空格局——构造年代学证据

UPLIFT EVOLUTION DURING MESOZOIC-CENOZOIC OF THE DABIE OROGENIC BELT:EVIDENCE FROM THE TECTONO_CHRONOLOGY

运用构造年代学方法对大别造山带中新生代隆升作用的时空格局进行了分析与确定．印支—早燕山期（２４０～１８０Ｍａ）是大别山广泛的逆冲或楔冲抬升时期，中深层次为向北西或北北西方向的透入性韧性逆冲推覆或楔冲，浅表层次为向造山带两侧的背冲式逆冲推覆，体现出分层楔入—逆冲抬升作用特点．晚侏罗世—早白垩世（１５０～９６Ｍａ）大别山又一次发生广泛的隆升作用，有关隆升构造包括顶托式片麻岩穹隆、岩浆底辟穹隆及西大别的背向式剥离滑脱构造，其中对岩石抬升剥露影响最大的是顶托式片麻岩穹隆，且以东大别罗田穹隆区及岳西穹隆区的抬升剥露幅度最大．晚白垩世早期，在北西－南东向伸展条件下，麻城－药铺－青山弧形剥离断层形成，随之在晚白垩世晚期至老第三纪发生差异断块隆陷构造，引起东大别核部地区，特别是罗田穹隆区进一步掀斜抬升．

The uplift structures during Mesozoic-Cenozoic can be divided into four kinds and six types. (1)thrusts; (2)domes, including wedging_thrust domes and diapiric domes which can be subdivided into gneiss domes and granite domes according to their rocks; (3)detachment fault systems; and (4)fault_block horsts and grabens. The forming ages of the uplift structures are determined by using tectono_chronology method. The layered_thrusting and wedge_thrusting occurred in the Indosinian-early Yanshanian period (240-180Ma)and formed uniform ductile thrusts system and some wedging_thrust domes at a deep crust level which topped the NW or N-NW brittle or ductile_brittle back_thrust systems in north_south direction at a shallow crust lever. The diapiric domes happened during the Late Jurassic-Early Cretaceous (150-96Ma). The back_detachment system in western Dabieshan also formed in this period (139Ma±) according to the age dating. The Macheng_Yaopu_Qingshan ductile detachment fault formed in the early stage of Late Cretaceous. The fault_block horsts and grabens occurred during the late stage of Late Cretaceous to Eocene.