摘要
通过对野外露头剖面的勘察采样和研究 ,从岩石的颜色、岩性、沉积构造、古生物化石以及地球化学等多项指标分析了喀什凹陷侏罗纪的古环境特征和演化。研究表明 :早侏罗世莎里塔什组属干燥氧化环境下的冲积扇沉积 ,到康苏组时演化为潮湿气候条件下的河流沉积 ;中侏罗世盆地南北出现差异 ,北部以淡水为主 ,而南部出现半咸水—咸水环境 ,古气候向半潮湿—半干燥演变 ,沉积相由三角洲前缘向深—半深湖再到滨浅湖沉积演化 ;晚侏罗世盆地又演化为干燥—半干燥环境下的河流与冲积扇沉积。整个侏罗纪代表了一个水体由浅—深—浅、古气候由干燥—湿热—干燥的演化过程。古水介质盐度基本上保持了陆相淡水湖体系 。
Based on the lithology, structure, fossils and geochemistry through the outcrop study and sample test,the Paleoenvironments and their evolution of Kashi Sag, Southwest Tarim Basin in Jurassic are discussed. The results indicate that the Shalitashi Formation in the early Jurassic was alluvial deposition under dry and oxidative condition, the Kangsu Formation represented the moist fluvial environment.In the middle Jurassic,the sag displayed the deference between the south and north.The north sag belonged to the fresh water environment and the south to the semisalty salty water condition. The paleoclimate gradually evolved into semidry semimoist condition. The sedimentation changed from the delta front into semideep deep lacustrine, then to shore shallow lacustrine. In the late Jurassic,the fluvial and alluvial deposition of semidry dry environment came out againin the basin. The whole Jurassic represented a complete shallow deep shallow palaeogeography and dry moist dry paleoclimate cycle. Paleowaters basically maintained the fresh terrestrial lacustrine environment, only in the middle Jurassic the southern sag displayed the salty water environment.
出处
《古地理学报》
CAS
CSCD
2002年第4期47-54,共8页
Journal of Palaeogeography：Chinese Edition
