古裂谷双模式地质特征

裂谷特有的作用过程——早期沿上地幔热异常带岩石圈遭受拉张上隆、减薄,中期断裂下陷及晚期的挤压、回返,造成陆内古裂谷具一系列双模式地质特征:先张后压构造形迹互相叠置、基性与酸性火山岩同时并存、非补偿性沉积与补偿性沉积构成沉积双元结构、双向式水流体系以及双模式成矿,变质作用。

BIMODAL GEOLOGICAL CHARACTERISTICS OF FAILED RIFT

Distinguished rifting includes 3 stages: lithospherc is tensed, uplifted, and thinned along thermal anomalzone of upper mantle in early stage, faulting-depressing takes place in middle stage, and rift is intensively compressed and finally comes to ceasation in late stage. Consequently, rift displays a series of bimodal geologic features as follows: tensive and compressive structure superposed on each other, basic and acidic volcanic rocks coexist, double-layered sedimentary structure consisting of uncompensated and compensated sedimentation, double- drainage system, bimodal mineralization and metamorphism.