【作者】 赵丽君；

【导师】 王瑜；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2010， 硕士

【摘要】 燕山造山带位于华北板块北缘,是中国地质工作的摇篮之一,以中新生代强烈的板内变形而闻名于世。大量的国内外学者在这一地区开展了关于中新生代及早前寒武纪的地质与构造问题,并取得了很多重要的认识。然而对于燕山东段中生代变形时间和变形机制却一直争议较大。中、晚三叠世在印支运动期间,燕山地区处于近南北向的挤压作用过程中,从侏罗世开始,由于古太平洋的构造作用,中国东部构造格局发生了重大转折,中国东部燕山造山带由近东西向转为北东、北北东向的构造格局。前人在研究区做了很多工作,但主要是对燕山中段东西向构造以及辽西地区北东向逆冲推覆构造的几何形态和形成机制以及构造演化进行了探讨,然而对于东西向向北东向转换的关键地区—宽城的构造变形研究却十分匮乏。本文选择燕山中东段蓟县—宽城—凌源一带作为工作重点,即燕山板内造山带由近东西向向北东向构造转换的关键部位作为工作重点,研究构造格局发生转变时的构造变形(主要是褶皱变形)、深层太古代变质岩和其上覆未发生变质的中元古代及其以上地层之间是否存在滑脱、基底是否卷入褶皱变形以及相应的年代学制约。通过本论文的研究,取得了一些新的认识及进展,主要包括以下几个方面:1研究区内的褶皱变形并非前人所述的轴面倾向北西,大量的轴面南东倾向的褶皱存在,辽西地区的逆冲推覆构造在野外表现为向南东方向的逆冲,实质上是由于南东方向的挤压而发生的内部调整。2通过对岩脉进行年龄测定,确定北东向变形时间为160Ma,在北京西山,同样可以看到北西方向的挤压作用形成了北东走向的构造,时间也在160Ma左右。与太行山中生代岩浆作用也具有时间上的一致性。3太古代—早元古代结晶基底与中、上元古代地层仅在研究区之间存在滑脱,而在蓟县、辽西等地,则表现为角度不整合或逆冲断层。更多还原

【Abstract】 The Yanshan tectonic belt lies in the northern margin of the North China plate, which is one of the cradles of geologic work of China. It’s famous for the intense intracontinental deformation in the Mesozoic and Cenozoic. Quite a few geoscientists have done researches on structural geology and tectonics in Precambrian Mesozoic, and Cenozoic, and have achieved many agreements. However, there are several disputes about the chronology and mechanism of deformation in the eastern part of Yanshan tectonic belt during the Mesozoic.During the period of Indosinian Movement, Yanshan tectonic belt was under approximately NS- compression in Middle Early Triassic. As a result of tectonism of the Palaeo-Pacific plate, a significant transformation took place in the tectonic framework of east China in Jurassic. The tectonic framework in Yanshan tectonic belt was changed from EW-trending to NE-NNE-trending. Previors geologis did many detailed investigations in study area. They mainly focused on EW-trending tectonic framework in middle part of the Yanshan tectonic belt, and the formation mechanism , tectonic evolution of NE-trending thrust zones in western Liaoning area. However, there is little literature on the tectonic deformation in Kuangcheng, which is the key area for the tectonic framework transformation from EW-trending to NE-trending. This paper takes Jixian-Kuangcheng-Lingyuan area as the key area for studying the tectonic framework inversion from EW-trending to NE-trending, focuses on tectonic deformation (mainly folds) when the tectonic framework transformation occurred, whether there was detachment between Archean metamorphic rocks in deep level and Middle Proterozoic and the upper unmetamorphic strata, whether the basement was involved in folding deformation and their chronological constraints.Through this paper, we’ve achieved some new understandings, including:1. Many folds in study area have an axial plane dipping SE, not dipping NW as early described. Thrusts in western Liaoning area shows SE-trending in the field, while actually they are influenced by the SW-trending compression and make their adjustments inside.2. According to the U-Pb zircon chronology of dykes, NE-trending deformation occurred at 160Ma. There are NE-trending structures influenced by NW-trending compression in Western Hills of Beijing, which also occurred at ca. 160Ma. That’s also in agreement with Mesozoic magmatism in the Taihangshan Mountain belt3. The detachment between Archean-Early Proterozoic and Middle-Late Proterozoic strata just exist in study area, In Jixian, western Liaoning Province and other places, it is angular unconformity or thrust fault.更多还原