藏北羌塘盆地中部中侏罗统层序地层研究

A STUDY ON MIDDLE JURASSIC SEQUENCE STRATIGRAPHY IN THE CENTRAL QIANGTANG BASIN

运用露头层序地层学原理与方法,将羌塘盆地中部地区中侏罗统划分为6个Ⅱ型层序,并阐述了各层序的体系域特征和形成的沉积动力学机制以及海平面变化对沉积、生物迁移及环境的控制作用。研究区中侏罗统存在6个海平面变化旋回:巴柔期早期、巴柔期晚期、巴通期早期、巴通期晚期、卡洛期早期和卡洛期晚期。研究结果表明,研究区中侏罗世为一裂陷—坳陷盆地,海平面变化与全球海平面变化的曲线基本吻合,其沉积面貌主要受控于全球海平面变化。

The Middle Jurassic in the central Qiangtang Basin is divided into six type II sequences using the principles and methods of outcrop sequence stratigraphy. The characteristics sedimentary dynamics sea level changes biological migration, and environment of each system tract are elucidated. Six sea level change cycles are recognized in the Middle Jurassic System in the study area： early Bajocian age, late Bajocia age, early Bathonian age, late Bathonian age, early Callorian age, and late Callorian age. Results show that the study area was a fault-controlled depression in the Middle Jurassic Epoch, with its sea level variation curve matching that of global sea level changes.