武当地块主要地质事件年代学研究

武当地块是南秦岭构造带内一系列前寒武纪地块之一 ,古生代以来经历过 3次重要的构造变形 ,即伸展作用、逆冲推覆作用和造山晚期走滑构造作用。运用4 0 Ar/39Ar阶段升温、4 0 Ar/39Ar激光探针及Sm Nd等时线等多种测年方法确定伸展构造发生于 4 2 3~ 2 6 1Ma、逆冲推覆构造发生于 2 34~ 2 0 0Ma ,表明伸展构造可能分别与商丹缝合带的碰撞及勉略洋的拉开有关 ,称之为同碰撞伸展构造 ,而武当地块内发育的逆冲推覆构造则应是华北板块与扬子板块沿勉略带发生碰撞的结果。

Chronology of major geological events of the Wudang block in the south Qinling orogen

The Wudang block is one of several median blocks in a series of rigid orogenic belts in the South Qinling tectonic belt. It has undergone three major tectonic deformation events since the Paleozoic, i.e. syncollisional extention, thrusting and late orogenic strike slip. Structural study indicates that the deformational events are related to the collision of the North China plate and the South Qinling tectonic belt along the Shangdan suture zone, the opening of the late Paleozoic Mianlue Ocean and the wholesale collision of the North China plate with the Yangtze plate in the Qinling orogen, respectively. The syncollisional extension occurred 423~261 Ma ago and thrusting about 234~200 Ma ago.