贵州南部印支晚期—燕山期构造变形特征

Tectonic deformation features from Late Indosinian to Yanshanian in southern Guizhou

贵州南部构造变形分带明显,贵阳—贵定—三都以北,断裂带呈近南北走向分布;包裹体数据证实,现今断裂带主活动期在印支晚期—燕山期;构造变形特征符合雪峰山由东向西推覆产生的递进(衰减)变形的总体规律。断裂带岩组样品揭示,岩石主要受到了上盘面理向下盘面理的挤压扭动作用,断层性质多为压性。断裂带以脆性形变为主,伴生少量韧性变形;贵阳—贵定—三都以南,属于雪峰山由东向西推覆作用下的中弱或弱变形带,且受垭紫罗挤压、走滑构造带共同影响,形成北东走向宽缓的背向斜构造格局。这反映了在地史演化过程中,该区北东部所承受的构造应力与西南部之间存在的巨大构造差异。现今,在构造弱变形带内的安顺凹陷、长顺凹陷可能是油气运移聚集最为有利的勘探区。

The tectonic deformations in the southern Guizhou were zoned obviously. To the north of Guiyang- Guiding-Sandu, fault belts distributed in NS direction. The studies of fluid inclusion showed that the present fault belts were active from the late Indosinian to Yanshanian and their tectonic deformation features were in accordance with the general law of progressive （attenuated） deformation caused by the nappe of Xuefeng Moun- tain from east to west. The rock samples from the fault belts confirmed that rocks were influenced by the squeeze and twist effect from the upper to the lower disk. The faults were compressive. The fault belts were brittle and some were ductile. To the south of Guiyang-Guiding-Sandu, the thrusting of Xuefeng Mountain from east to west led to medium-weak or weak deformations and a gentle anticlinal tectonic framework in NE direction was formed under the influence of Yaziluo squeeze and strike-slip belt. Big difference of stress field existed between the northeast and the southwest of the study area during tectonic evolution. The Anshun and Changshun Sags in the weak deformation belt might be favorable targets for petroleum migration and accumulation.