Structural deformation characteristics of the Kalpin thrust belt, NW Tarim
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摘要: 柯坪冲断带位于塔里木盆地西北缘，是新生代南天山褶皱冲断系的一部分.本文根据野外实际考察和地震剖面解释，总结了该冲断带的构造变形特征.它是发育于古生界中且以中寒武统膏盐层为主滑脱面的薄皮构造，是内部结构相对简单的叠瓦状冲断，因更新世才定型而具暴露式冲断前锋，有断层传播褶皱发育但已遭强烈剥蚀，前展式冲断.上新世晚期的冲断曾控制了磨拉石盆地发育（西域组砾岩），但该盆地已遭更新世的冲断推覆作用破坏.根据平衡剖面恢复，柯坪冲断带南部3排冲断层的总构造缩短量为29.1%-40.7%.Abstract: The Kalpin thrust belt or Kalpin fold-and-thrust belt, located in the northwestern margin of the Tarim Basin,is a part of the South Tianshan fold-and-thrust system.On the basis of field investigation and seismic section interpretation,the main features of the Kalpin thrust belt could be summerized as the follows.1)Only the Paleozoic rocks were involved into the thrusting,which meant that the major detachment fault was gypsum-salt Iayer in the Middle Cambrian.2)The belt was characterized by imbricated thrusting, with a relatively simple inner texture.3)The belt had an exposed thrust front,since it did not create till Pleistocene.4)The fault-propagation folds once occurred,which were experienced violently denuded.5)The belt was a piggyback one with the thrusting expanded southwards.6)A molasse basin once occurred during Pliocene,with the geological records being conglomerate of the Xiyu Formation but the basin had been disrupted by the Pleistocene thrusting-nappe structuring.The Kalpin thrust belt consisted of the northern fold sub-belt and the southern thrust-nappe structural subbelt, and for the latter, the balanced section analysis revealved the minimal shortening rate being 29.1% to 40.7%.
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