塔里木盆地古生代重要演化阶段的古构造格局与古地理演化

Tectonic framework and paleogeographic evolution of the Tarim basin during the Paleozoic major evolutionary stages

塔里木盆地在古生代经历了中-晚奥陶世、晚奥陶世末、中泥盆世末等多个重要的盆地变革期,形成了多个重要的不整合,盆地构造古地理发生了重要的变化。中、晚奥陶世盆地的变革形成了由巴楚古斜坡-塔中隆起-和田河隆起构成的大型古隆起带、相对沉降的北部坳陷带以及由于挤压挠曲沉降形成的塘古孜巴斯坳陷带。中部古隆起带制约着晚奥陶世东窄西宽的弧立碳酸盐岩台地体系的发育,而开始形成于震旦纪的满加尔拗拉槽及东南侧的塘古孜巴斯坳陷接受了巨厚的中、晚奥陶世重力流沉积。奥陶纪末的盆地变革形成了北东东向展布的西南-东南缘和西北缘的强烈隆起带,总体的古构造地貌控制着早志留世北东东向展布的滨浅海陆源碎屑盆地的沉积格局。中泥盆纪世末期的盆地强烈隆升并遭受了夷平化的剥蚀作用,形成了大范围分布的角度不整合面,并以塔北隆起和塔东隆起的强烈抬升为显著特征。盆地古构造地貌从东低西高转为东高、西低,制约着晚泥盆和早石炭世由东向西南方向从滨岸到浅海的古地理分布。中、晚奥陶世主要不整合及其剥蚀量的分布反映出北昆仑向北碰撞和挤入是造成盆地南缘、东南缘及盆内隆起的主要原因。南天山洋的俯冲、碰撞在奥陶世末至早志留世已对盆地西北缘产生影响,导致塔北英买力隆起的抬升和遭受剥蚀。

Tarim basin underwent several major evolutionary stages during the Paleozoic,including the periods at the end of the Middle to early Late Ordovician,the end of the Late Ordovician and the end of the Middle Devonian or Early Carboniferous,and resulted in a series of important unconformities.The tectonic movement occurred in the Middle to the early Late Ordovician led to the development of the central paleo-uplift belt composed of the Bachu paleo-slope,the Tazhong uplift and the Hetianhe uplift,the relatively subsidence Northern depression belt and the Tangguzibasi depression formed due to compressive flexural subsidence.Constrained by the paleo-uplift,the Tazhong uplift belt of the Late Ordovician formed a peninsula-shaped carbonate platform which narrowed eastwards.The Majiaer depression,which generated in Sinian,and the Tangguzibasi depression received several thousand meters of deep water muddy and turbidite deposits during the Middle to Late Ordovician.At the end of the Ordovician,formed the Tarbei paleo-uplift belts along the northwestern basin margin and the Southeastern paleouplift belt along the southwest to southeastern basin margin.The resulted tectonic geomorphology controlled the Early Silurian depositional framework of the neritic terrigenous clastic basin extended northeast-eastwards.At the end of the Middle Devonian,the basin experienced an intense uplifting and suffered strong denudation,and formed an extensive angular unconformity surface along the Tabei and the Tadong paleo-uplifts.The tectonic geomorphology of the basin during this period changed from lower to higher in the east and higher to lower in the west,which made a significant influence on the paleogeographic pattern of the Late Devonian and Early Carboniferous.The study show that the deformation occurred at the end of the Middle to early Late Ordovician might have resulted from the northward collision and extrusion of the North Kunlun orogenics.At the end of the Middle Devonian,the intensively uplifting of the Tabei uplifts and the folding and uplifting of the Manjiaer depression might be attributed to the collision of the southern Tianshan Ocean.