雅鲁藏布江缝合带内构造岩片划分及形成——以仲巴-桑桑段为例

构造岩片作为造山带中非史密斯地层地区的填图单位有其重要的地质意义,本文将雅鲁藏布江缝合带分为6大构造岩片,其中蛇绿混杂岩岩片又分4个次级岩片,进一步阐述了缝合带内不同单元具有不同岩性和不同构造型式,是一条复杂的构造带,并发现俯冲板块一侧的不同构造单元具有自南而北,由脆性变形到低温高压变质、脆-韧性变形,超基性岩的深层次韧性变形的分布规律,大多数岩片的分布是通过多重逆冲推覆型或走滑型的断层将其从地壳深部挤出定位的。雅鲁藏布江缝合带内的构造岩片特征,反映了冈瓦那大陆北缘自三叠纪末期到第四纪经历了裂陷、扩张、多岛洋、闭合、俯冲、碰撞、褶皱、推覆造山的全过程。

HIERARCHY OF TECTONIC SLICE AND FORMATION OF YALUZANGBU SUTURE ZONE - TAKE ZHONGBA-SANGSANG BELT AS AN EXAMPLE

It is of significant geological importance that tectonic slices can be regarded as units for geological mapping in orogens of non-Smith strata areas. In this paper the Yaluzangbu suture zone is divided into 6 structural zones, and the ophiolite complex can be further divided into 4 secondary rock slices. It is further elaborated that the different structural units are characterized by different lithologies and structural patterns within the same suture zone, which is definitely a complicated structural zone. It is found that for the structural units of a subduction plate from south to north, the deformation features of ultramafic rocks change from brittle deformation to low-temperature and high-pressure metamorphism, then to brittle-ductile deformation and deep-sited ductile deformation. The majority of the present rock slices was squeezed out of the deep crust and got positioned through multiple thrust-napping or strike-slip faulting events. The tectonic slices of the Yaluzangbu suture zone reflect that the north margin of Gondwana Continent has experienced rifting, spreading, formation of archipelagic ocean, closing, subduction, collision, folding, napping, and orogenesis from late Triassic to Quaternary.