广西十万大山前陆冲断推覆构造

通过十万大山盆地内地震剖面资料和ＴＭ遥感图象的地质构造解译，结合重力资料和野外地质观察及构造分析，阐述了十万大山前陆冲断推覆构造的发育特征和前陆盆地的构造演化。前陆冲断推覆构造由３个不同的构造变形带组成：卷入海西和印支期花岗岩体的逆冲断裂带、充填中生代陆相沉积并发生构造滑脱的前陆盆地和对应于华南准地台的前陆腹地。冲断推覆构造的形成和演化是与中、晚古生代钦州海槽晚二叠世的褶皱回返和中生代相继的构造复活密切联系的，它经历了３期主要构造应力作用事件：晚二叠世海西运动晚幕为冲断推覆构造的雏形期，晚三叠世印支运动晚幕的近ＳＮ向挤压是陆相前陆盆地的发育期；早白垩世末期燕山运动主幕ＮＷ—ＳＥ向挤压是现今十万大山前陆冲断推覆构造的成型期。

FORELAND THRUST AND NAPPE TECTONICS OF SHIWANDASHAN, GUANGXI

This paper presents basic characteristics of foreland thrust and nappe tectonics of Shiwandashan, based on seismic profile interpretations, gravity data, Landsat TM imagery interpretation and field observations. It shows that the Shiwandashan foreland thrust and nappe tectonics are featured by three major structural belts: a NW thrusted fault belt that involves Late Permian and Mid Triassic granites and Late Paleozoic marine sediments; a Mesozoic foreland basin that is filled with thick Late Triassic to Early Cretaceous continental facies deposits and dominated by décollement tectonics; and a hinterland zone corresponding to Huanan Caledonides. The occurrence of thrust tectonics is closely related to Late Permian closure and successive reactivation during Mesozoic of the active Qingzhou Trough, in responding to regional tectonic events. Thrust tectonics was accompaned with the formation and NW ward migration of the Shiwandashan foreland basin. The major thrusting phase took place near the end of Early Cretaceous, that caused granitic massif to be strongly thrusted NW ward over the foreland zone and Mesozoic continental facies deposits to be widely detached.