THE TRANSFER ZONE WITHIN INTRA-CONTINENT SUBDUCTION OROGENIC BELT IN THE TIANSHAN, NORTHWEST CHINA
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摘要: 天山山系是中国西北地区的一个复合造山带,中、新生代以来在印度板块与欧亚板块俯冲碰撞的远程挤压效应影向下,发生了陆内俯冲。塔里木地块和准噶尔地块相向俯冲于天山之下,造成了山系的急剧隆升和冲断推覆,在构造重荷作用下,沿着天山南、北山前发育了陆内俯冲型前陆盆地,这一特点已为大多数学者所共识。然而,天山陆内造山带在形成过程中沿着走向却存在明显的变化,尤其是东、西天山在地壳厚度、山系海拔高度、地震活动烈度等方面均有较大的差异,总体上以西天山的活动性明显大于东天山为特点。发育于准噶尔地块内的博格达山在这一阶段表现出强烈的活动性,山系隆升和褶皱冲断控制其边缘前陆盆地的充填,与西天山相对应。这说明天山陆内造山过程中存在着转换作用,把西天山陆内俯冲的地壳缩短量转换到了博格达山地区,由此平衡东、西天山的差异,故称之为陆内造山转换带。Abstract: The Tianshan Mountains is a composite orogenic belt. The intra-continent subduction occurred under the influence of distant compressure of subduction and collision taking place between the Indian plate and the Eurasia plate in the Mesozoic-Cenozoic. The Tarim block and the Junggar block subducted in the opposite direction beneath the Tianshan Mountains. The mountains was lifted rapidly and thrust-folded from central to north and south. Intra-continent subduction foreland basins were developed, under effect of the tectonic load, in the North and South of the Tianshan Mountains. There were differences along the trend of the intra-continent subduction orogenic belt, in terms of the thickness of crust, the elevation of mountains, the intensity of earthquake etc, between eastern and western Tianshan Mountains. It was clear that the West of Tianshan Mountains was more active than the East. The Bogeda Mountains showed the intensive activity in the formation of intra-continent orogenic belt. Lift and thrust-fold belt, formed in the stage, controlled the deposition in the foreland basins developed in the two sides of the Mountains. There was comparison between the West of the Tianshan Mountains and Bogeda Mountains. All of them showed that there was a transfer zone, which transferred the shortening from the West of the Tianshan Mountains to the Bogeda Mountains, in the development of intra-continent orogenic belt. The difference of the crust shortening of western and eastern Tianshan Mountains was transferred to the Bogeda Mountains. The transfer zone balanced the differences between eastern and western Tianshan Mountains, and named as Urumqi-Kuerle transfer zone.
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