新疆北部晚古生代沉积盆地类型及其沉积特征

TYPES OF LATE PALEOZOIC SEDIMENTARY BASINS AND THEIR SEDIMENTARY CHARACTERISTICS IN NORTHERN XINJIANG

新疆北部晚古生代,构造岩浆活动十分强烈并发育复杂且变迁迅速的众多沉积盆地。沉积盆地可划分为7类(大陆边缘裂谷类、岩浆弧类、弧前盆地类、边缘海盆地类、弧后前陆盆地类、边缘前陆盆地类、海沟-洋盆类)19型。沉积组合复杂多变,不同类型的沉积盆地各具特色。沉积盆地的演化经历了5次重大变革。新疆北部晚古生代沉积盆地随新疆北部板块的拉张-俯冲-碰撞而产生、发展、消亡。

The tectonomagmatic activity was very strong and many changeable, complicated sedimentary basins were developed in northern Xinjiang in the Late Paleozoic. The sedimentary basins may be classified into 7 types and 19 subtypes which were formed respectively in five Late Paleozoic stages, i. e. ( 1 )continental-margin rift type: southern Tianshan subtype; ( 2 ) magmatic arc type: northern Tianshan subtype and Ertix-Santanghu subtype; ( 3 ) forearc basin type: Eren-haberga subtype; ( 4 ) marginal sea basin type: Altay subtype and western Junggar subtype; ( 5 ) backarc foreland basin type: Altay subtype, northern Junggar subtype and Borohoro subtype; ( 6 ) peripheral foreland basin type: Ertix-Santanghu subtype, northern Junggar subtype, southern Junggar subtype, Yining subtype, southwestern Tianshan subtype and Hongshanzui subtype; ( 7 ) trench-sea basin type: Karameili subtype, Ertix subtype, Hantangri subtype and Bayingou subtype.The sedimentary basin have the following sedimentary characteristics in common: high sedimentary rate, generally 4-40 mm/100 yr.; huge thickness; complex sedimentary types; rich volcanic material; irregular distribution of trace elements; low stability and maturity; mainly marine facies; rapid facies change, esp. in the crosssection of facies zone. But different types of sedimentary basins have their own special sedimentary characteristics.There are 5 important transformations in the development of the sedimentary basins, which occurred respectively at the end of the Middle Devonian, the end of the Tournaisian of the Early Carboniferous, the end of the Visean of the Early Carboniferous, the end of the Weining of the Late Carboniferous and the end of the Permian. The generation, development and consumption of the sedimentary basins were controlled by the complicated tectonic settings, that is, constant extension-subduction, collision and northward accretion→reextension-subduction, recollision and junction among 3 plates (the southern margin of the Sibrian plate, the eastern Kasakhstan plate and northern border of the Tarim plate) in northern Xinjiang in the Late Paleozoic.