西准噶尔古生代地层区划及古地理演化

根据大地构造环境与沉积组合(建造)类型，地层序列与地层接触关系，古地理格局与古环境条件，古生物类型与生物古地理区系，地层类型与地层的变形、变质和变位特征，地层区划的边界类型与识别标志，地层区划可以区分为综合和断代地层区划2类，都可以分为4级:地层大区(stratomegaregion)、地层区(stratoregion)、地层分区(stratosubregion)和地层小区(stratomicroregion).基于近年来取得的大量新资料、新认识和上述地层区划6方面的判据，西准噶尔地区古生代地层区划自北向南划分为萨吾尔山地层小区、沙尔布尔提山地层小区、玛依力山地层小区和克拉玛依地层小区.在构造古地理上，西准噶尔地区古生代表现为多岛洋和软碰撞的特点，志留纪后期至早石炭世是多岛洋和软碰撞的鼎盛时期，也是西准噶尔地区古生代地层区划的重要形成时期；晚石炭世至二叠纪，西准噶尔地区主体脱离海洋环境，进入陆内造山阶段，西准噶尔地区古生代地层的分区性逐渐消失.在生物古地理上，早古生代西准噶尔地区属于介于太平洋生物大区与大西洋生物大区之间的混生生物大区，不同于东北部西伯利亚板块南部由Tuvaella(图瓦贝)动物群所代表的生物区系；从志留纪至泥盆纪，西准噶尔地区的生物组合面貌明显属于热带-亚热带的古特提斯生物大区；晚石炭世-二叠纪西准噶尔地区陆相地层中的植物群面貌显示出明显的北温带安加拉植物群的特点.在沉积古地理上，西准噶尔地区古生代的作用相包括正常沉积与事件沉积，特别是反映活动构造环境的内力事件沉积特别发育，如火山爆发相、火山溢流相和震积岩相；环境相包括古陆、河流相、滨-浅海相和半深海-深海相. 

Paleozoic Stratigraphic Regionalization and Paleogeographic Evolution in Western Junggar,Northwestern China

Both general and special stratigraphic regionalizations have been worked out in this study according to (1) geotectonic environments and sedimentary association types; (2) stratigraphic sequences and contact relationships; (3) paleogeographic framework and paleoenvironmental conditions; (4) paleontological taxa and paleobiogeography; (5) deformational and metamorphic specialty of strata, as well as (6) boundary types of stratigraphic regionalization and their criterion. Both general and special stratigraphic regionalizations can be subdivided into four hierarchies of the stratomegaregion, stratoregion, stratosubregion, and stratomicroregion. The Paleozoic strata of western Junggar can be divided into four stratomicroregions from north to south, i. e. the Saur Mountains, Shaerbuerti Mountains, Mayili Mountains and Karamay stratomicroregions based on the mentioned-above six aspects, and new data and progresses gained in recent studies. Paleozoic western Junggar is featured by its archipelagic ocean and soft-collisional orogenics in tectonopaleogeography. The Late Silurian till Early Carboniferous represents the prime of such tectonic pattern and regimes, forming the Paleozoic stratigraphic regionalization. Western Junggar emerged from ocean and stepped into an intracontinental orogenic period from the Late Carboniferous to Permian, announcing a gradual disappearance of stratigraphic regionalization. In paleobiogeography, the Early Paleozoic of western Junggar is distinguished by its mixed fauna between the Pacific and Atlantic biomegaprovinces, and also different from the bioprovince represented by the Tuvaella fauna in the southern part of the Siberian plate. The fossil assemblages of western Junggar during the Silurian to Devonian periods show a prominent relevance to the tropical-subtropical palaeo-tethys biomegaprovince.However, an Angara flora typical of the north temperate zone dominates the Late Carboniferous to Permian continental strata in western Junggar. In sedimentary paleogeography, the processing facies of Paleozoic western Junggar include both normal and event sedimentary facies, with the latter particularly developed such as volcanic eruption, volcanic overflow and seismite facies, which reflects its active tectonic background. The environmental facies comprise palaeo-continental, fluvial, littoral-shallow-marine and bathyal-abyssal facies.