川西丹巴地区构造──热模式初探

    TECTONO-THERMAL MODEL OF THE DANBA AREA,WESTERN SICHUAN

    • 摘要: 川西丹巴地区出露两套不同岩系:杨子板块结晶基底——康定杂岩、宝兴杂岩;另一套为分布于其北的边缘海型变质沉积宕。印支期该区受南北向挤压,形成大量挤压型构造。由于不均匀分布的、极强硬的结晶基底的影响,各处变形强度不同。本文用应变测量方法分析了各区的变形量,发现基底向北突出的丹巴地区变形量较大,而向南凹的金汤弧区则较小。丹巴地区变质程度高于其他地区,笔者用构造一热模式对该现象进行了定性解释。

       

      Abstract: The Danba area in western Sichuan is located in a passive continental-margin setting on thenorthwestern margin of the Yangtze plate. Two different rock suites are exposed there:one isthe crystalline basement of the Yangte plate the Kangding complex and Baoxing complex;the other is metasedimentary rocks of marginal sea type distributed in the north.In the In-dosinian period ,the area underwent N-S compression,forming a lot of compressive structure. Under the influence of the uneven distribution of hard crystalline basement,the degree of defor-mation varies from place to place. The authors analyzed the amount of deformation at variouslocalities using the strain measuring technique. It has been found that the Danba area where thebasement is convex northward has a larger deformation amount and higher metamorphic grade,while the Jintang arc area concave southward has a smaller amount of deformation,In the paperthis phenomenon is interpreted qualitatively using the tectono-thermal model.

       

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