【作者】 滕飞；

【导师】 张长厚；

【作者基本信息】 中国地质大学(北京) ， 构造地质学， 2012， 硕士

【摘要】 华北克拉通北部中生代早期构造属性问题仍然存在着比较明显的认识分歧。岩浆岩岩石地球化学研究结果多显示其处在伸展构造状态，但缺少相关伸展变形研究成果的支持。在燕山中部区域未有准确的构造变形和年代学研究结果证明早中生代的构造变形属性。蓟县断层位于华北克拉通北部，燕山造山带中段南缘，呈NEE向分布于盘山岩体及其东、西两侧的府君山向斜和庄果峪向斜南部。该区域的构造演变过程方面存在明显的争论。我们在盘山岩体南部开展的野外研究表明，在蓟县断层延伸的相应区域内不存在断裂破碎带等断层活动迹象，表明盘山岩体南部的岩体侵入早于断层活动。对采自该区域岩石中的锆石运用LA-MC-ICPMS方法进行U-Pb定年，获得年龄为195Ma，表明蓟县断层活动早于195Ma。在许家台西部采石场发现，顺层侵入于雾迷山组白云岩中的岩床卷入到了蓟县断层下盘的伴生变形中，LA-MC-ICPMS方法测得脉岩锆石U-Pb年龄为204Ma，与前人测得的盘山岩体北部锆石SHRIMP U-Pb法测得岩体形成时代（203~207Ma）近于一致。上述野外观测和年代学测试结果表明，盘山岩体本身不是一个就位时代一致的统一侵入体，而是由不同阶段侵入岩组成的复合岩体。其中较早期侵入岩及其灌入围岩中的岩床卷入到了蓟县断层逆冲活动之中，后期侵入活动之后，蓟县断层未再进一步发生变形。即蓟县断层形成于204-195Ma期间。蓟县断层运动学属性及其形成时代表明，在早中生代期间华北克拉通北部浅层地壳处于收缩变形状态。椴树凹-尖宝山断层总体呈近EW向分布于西椴树凹-尖宝山一带，上盘蓟县系向南逆冲于青白口系、寒武系、早侏罗统地层之上，断层东段被宽城盆地内的髫髻山组火山岩覆盖。宽城盆地底部火山岩样品给出的LA-MC-ICPMS锆石U-Pb年龄为151.8±2.5Ma，这样将椴树凹-尖宝山断层及相关褶皱活动时代限定在早、中侏罗世，指示燕山中段燕山运动A幕近NS向收缩的变形特征。在此之后，该区有NE向微弱构造进行叠加。更多还原

【Abstract】 Differences on tectonic features of the northern part of North China in earlierMesozoic have still existed. The geochemical study of magmatic rocks shows it’smainly in the extensional state, but lack of support on related deformation. Noaccurate structural deformation and geochronology study in Yanshan central areasshows the early Mesozoic tectonic deformation properties.Jixian fault, oriented to NEE, is located in the northern part North China craton,southern margin of the middle Yanshan orogen, on both west and east sides ofPanshan pluton, and southern part of Fujunshan syncline and Zhuangguoyu syncline.The tectonic evolution of this area has been of much controversy. Our field work inthe south of Panshan pluton shows rock in the area which Jixian fault extend to don’texist fracture zone or fault activity indicate that the region’s rock intrusion is earlierthan the fault activity. We obtained195Ma by dating rocks in this region by zirconU-Pb LA-MC-ICPMS, indicating that the Jixian fault thrusted before195Ma. Sheet indolomite of Wumishan formation involved in deformation as footwall of Jixian faultin the west of Xujiatai. LA-MC-ICPMS zircon U-Pb dating result is204Ma, cloth tothe result of dating on northern part of Panshan pluton (203-207Ma, by SHRIMPzircon U-Pb). Field work and geochronology show that the Panshan pluton hasmulti-episode magmatic intrusion process. The earlier pluton and sheet in surroundingrock were involved in Jixian fault activity. Jixian fault was not activity after the laterintrusion. Jixian faults formed during204-195Ma.It’s kinematic properties andchronology suggest that shallow crust of North China craton was in compressionduring the early Mesozoic.Duanshuao-Jianbaoshan fault is oriented to EW, dips to north and makes Jixiansystem on top of Qingbaikou system, Cambrian system and lower Jurassic series.Eastern part of this fault is covered by Tiaojishan formation. Dating of VolcanicSample at the bottom of Kuanchang Basin shows Duanshuao-Jianbaoshan faultformed before152Ma, in early-middle Jurassic. Which indicate NS compression in Aperiod of Yanshan movement. After that, superimposed folds whose axis oriented toNE formed.更多还原