赣江断裂带地质特征及其动力学演化  

Geological Features and Dynamic Evolution of the Ganjiang Fault in Jiangxi Province

作　　者：邓平[1] 舒良树[1] 杨明桂 郭英杰 余心起[1] 

机构地区：[1]南京大学地球科学系 [2]江西省地质调查院,南昌330000

出　　处：《地质论评》2003年第2期113-122,共10页Geological Review

基　　金：国家自然科学基金(编号40172067);国家自然科学基金(编号40132010);教育部博土点基金(编号20010284005)

摘　　要：赣江断裂带发育在江西省境内,全长大于600km,宽50～120km,走向N20°E左右,伴生有一系列NE向和NW向的次级断裂。在地球物理上,它是一个具有显著重力、航磁异常梯度带的深大断裂带;岩石学上,是一个晚中生代的火山岩线;沉积学上,控制了一系列晚白垩世—古近纪的红色沉积盆地。构造形迹和沉积作用特征表明,中—新生代是赣江断裂带活动的高峰期,主体上表现为一个大规模的左行走滑脆性剪切带,其左旋走滑变形具有北强南弱、走滑时代北早南晚的穿时特点以及伸展断陷向北扩展、沉积中心向西迁移的演化规律。控盆作用及构造交切关系表明,赣江断裂带起始于印支期扬子与华北板块碰撞造山之后的早侏罗世。年代学、运动学研究表明,该断裂带经历了三个阶段的构造演化:早白垩世左旋走滑、晚白垩世—古近纪的滑脱伸展和新近纪—第四纪的右旋挤压,其动力学原因主要受侏罗纪以来太平洋板块运动体制的制约。The geophysical features at the deep levels, geometry, structural kinematics, forming mechanism and tectonic evolution of the Ganjiang fault are studied. This fault zone, in Jiangxi Province, and with a width of 50-120 km and length more than 600 km along direction of NNE20°±, is associated with a series of NE-trending and NW-trending secondary faults. The oldest strata cut by the fault belong to the Proterozoic and Sinian, and the youngest strata to the Tertiary. Geophysically, it is an ultra-crust fault zone with distinct gravitational and aeromagnetic anomalies. Petrologically, it was a Late Mesozoic volcanic line. Sedimentologically, the Ganjiang fault controlled a series of Late Cretaceous-Paleogene red basins. Research results on deformed structures and sedimentary features indicate that the active peak took place during the Mesozoic-Cenozoic times. Generally, the fault is a large-scale, sinistral strike-slip, brittle shear zone with a component of normal faulting and dipping to the east. Geological crosscutting relations in the field indicate that the sinistral strike-slip deformation took place in the Early Cretaceous. The sinistral strike-slip deformation has a trend weakening from the north to south, which resulted in the widening of the northern segment relative to the southern segment. Kinematic study suggests that the fault zone experienced three stages of structural evolution, i. e. , sinistral strike-slip deformation during the Early Cretaceous, detachment extension from the Late Cretaceous to Paleocene leading to the westward migration of the sedimentary center of basins and dextral strike-slipping with a compression in the Neogene-Quaternary interval. Geodynamically, the formation of the Ganjiang fault zone was related to the Paleo-Pacific plate subduction toward the eastern Asian continent from the southeast to northwest since the Middle Jurassic.

关 键 词：地质特征 地球动力学 赣江断裂带 中一新生代 构造形迹 沉积作用 

分 类 号：P542.3[天文地球—构造地质学]