Material composition characteristics of Naijtal Group in subduction accretion complex on the southern slope of East Kunlun Mountains
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摘要:
东昆仑的形成经历了长期的构造演化、地体拼贴、碰撞及复合造山的动力过程。奥陶纪—志留纪昆中洋由南向北俯冲形成典型的东昆仑南坡俯冲增生杂岩楔，其中发育的纳赤台群物质组成复杂，也是该带主要的组成物质。通过野外详细调查，发现纳赤台群物质由洋中脊－洋岛环境下的含蛇绿岩残片组分及远洋泥钙质沉积、具有浊积岩特征的大陆斜坡次深海-深海相物质、前陆盆地复理石沉积组合、火山岛弧环境下的物质组合等构成。不同岩石组合间多为断层后韧性剪切接触，岩石构造变形十分强烈，不同岩块间时代跨度大，所处的构造环境迥异。在长期俯冲过程中，将不同的物质在东昆仑陆块边缘以不同规模，形态各异的岩片、岩块样式拼贴或堆垛在一起。
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关键词:
- 东昆仑南坡俯冲增生杂岩 /
- 奥陶纪—志留纪 /
- 纳赤台群物质组成 /
- 形成时代 /
- 构造环境
Abstract:The formation of the East Kunlun Mountains experienced long-term tectonic evolution, collage, collision and the complex orogenic process, thus generating very complex geological structure. During its northward subduction, Ordovician-Silurian Kunduz formed typical subduction accretion complex on the southern slope of East Kunlun Mountains. In addition, the extremely complicated composition of the Naijtal Group is also the vital component in this belt. Through field investigation, the authors found that the Naijtal Group has very complicated composition, and consists of ophiolite fragments-bearing deposits, ocean mud calcium deposits, midocean ridge-ocean island deposits that contain ophiolite fragments and ocean pelitic calcareous sediments, abyssal-bathyal sediments with the characteristics of turbidite on the continental slope, foreland basin flysch sediments and volcanic island arc material composition. The contact relationships between different rock combinations are ductile shear contact after faulting, and these rocks with strong tectonic deformation have very different ages and tectonic environments. In the process of long-term subduction, different materials collaged or heaped together at the edge of the east Kunlun block in the forms of rocks with different sizes and shapes.
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