郯庐断裂带晚中生代演化历史及其对华北克拉通破坏过程的指示

Late Mesozoic evolution history of the Tan-Lu Fault Zone and its indication to destruction processes of the North China Craton

郯庐断裂带晚中生代的演化历史是华北克拉通破坏过程的重要记录。中侏罗世末(燕山运动A幕),郯庐断裂带局部发生左行平移活动,而华北克拉通上出现了一系列北北东走向的缩短构造,指示了西太平洋伊泽奈崎板块俯冲的开始。晚侏罗世期间,郯庐断裂带没有发生活动,而华北克拉通出现局部伸展与岩浆活动及区域性隆升,应为弧后弱拉张背景。早白垩世初(燕山运动B幕),郯庐断裂带再次发生强烈的左行平移活动,华北克拉通北部与东部出现了一系列近南北向挤压产生的构造,应是鄂霍茨克洋最终关闭与伊泽奈崎板块高速俯冲双重作用的结果。随后的早白垩世期间,华北克拉通在弧后拉张背景下发生峰期破坏,郯庐断裂带呈现为强烈的伸展活动。早白垩世末的区域性挤压作用,结束了华北克拉通的峰期破坏,并使郯庐断裂带再次发生了一期左行平移活动。这期挤压作用出现在太平洋板块接替伊泽奈崎板块这一重大板块调整的背景之中。

Late Mesozoic evolution history of the Tan-Lu Fault Zone is important record for destruction processes of the North China Craton. The Tan-Lu Fault Zone suffered local sinistral faulting at the end of Middle Jurassic. This event,i. e. the episode A of the Yanshan Movement,was accompanied with formation of series of NNE-striking,shortening structures in the North China Craton. This event suggests initiation of the Izanagi Plate subduction. The fault zone showed no activity during Late Jurassic while the North China Craton experienced local extension and magmatism as well as regional uplifting. Weak back-arc extension should be responsible for the Late Jurassic events. The fault zone was subjected to intense,sinistral movement at the beginning of Early Cretaceous while northern and eastern parts of the North China Craton presented a series of structures produced by nearly N-S compression. It is suggested that this shortening event,i. e. the episode B of the Yanshan Movement,is related to both the final closure of the Okhotsk Ocean and highspeed subduction of the Izanagi Plate. The eastern North China Craton turned into peak destruction under the setting of back-arc extension during the Early Cretaceous while the Tan-Lu Fault Zone experienced intense extensional activity. Regional compression at the end of the Early Cretaceous terminated the peak destruction of the North China Craton and caused another sinistral faulting event in the Tan-Lu Fault Zone. This compressive event occurred under the important plate adjustment from the Izanagi Plate to Pacific Plate.