【作者】 关会梅；

【导师】 刘俊来；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2008， 博士

【摘要】 本文系统总结了辽南变质核杂岩的组成与结构及其特点。厘定了万福变质核杂岩,对其基本特点开展了深入研究,确定了辽南-万福变质核杂岩对,阐述了其剥露机制。并结合中国东部、俄罗斯远东和东蒙地区区域伸展构造的特点综合分析,阐述了该变质核杂岩对对于区域岩石圈减薄过程的意义。获得以下成果:(1)对辽南变质核杂岩的主拆离断层带及其构造-岩浆关系开展了深入研究。辽南变质核杂岩具有三层结构,由五部分组成。主拆离断层带内岩石在空间上具有分带性,它是一套以糜棱岩为主的反映地壳深部岩石在隆升过程中不断演变的糜棱片麻岩到微角砾岩构造岩组合。辽南变质核杂岩拆离断层具有典型的波瓦状构造特征,它与下盘晚期阶段花岗质岩体的侵位同步发育。(2)首次厘定了万福变质核杂岩,它是一个典型的Cordillera型变质核杂岩,具有三层结构。主拆离断层倾向东倾角较小,拆离断层带拉伸线理与擦痕构造倾伏向东,运动学指向显示下盘向北西西方向运动。(3)对五个岩浆岩样品进行锆石U-Pb测年得出,火山岩的年龄具有两个时期,分别为为构造期前(SL0530,169±8 Ma)和同构造期(SL0585,123±7 Ma);花岗岩的年龄具有三个阶段,分别为:构造期前(SL05103,166±4 Ma)、同构造期(SL0543,124±3 Ma)和构造期后(SL0536,113±2 Ma)。而同一构造期的火山岩和花岗岩样品的年龄非常相近,说明本区岩浆事件时间上的一致性。(4)万福与辽南变质核杂岩构成一个变质核杂岩对。辽南变质核杂岩的形成时间略早于前者。万福变质核杂岩的发现为阐述华北克拉通晚中生代岩石圈的力学和流变学属性,及岩石圈减薄范围提供了新证据。(5)辽南、万福变质核杂岩演化过程的年代学格架,为阐述辽东半岛南部晚中生代时期岩石圈伸展减薄过程提供了重要依据。赵房岩体所记录的拆离断层停止时限(113Ma)可以作为辽东半岛南部强烈构造岩浆活动的转捩点。(6)辽南、万福变质核杂岩与其他地区发育的伸展构造在形成时代、运动学规律等方面具有统一性。揭示了整个东亚地区岩石圈在晚中生代时期遭受了强烈的伸展作用改造,同时伴随着大规模岩石圈减薄作用。区域伸展作用的动力学过程纯剪作用占据主导地位,而地壳拆离作用主要发生在中浅部地壳层次。更多还原

【Abstract】 This research summarized the constitution, structure and evolution of the Liaonan metamorphic core complex(mcc). Revealed the existence of the Wanfu mcc and made it certain that Wanfu mcc and Liaonan mcc form a mcc pair, and expatiated their’exhumation mechanism. Combination with analysis of the regional extensional structures characteristics in East China, far east of Russa and eastern Mogolia, illustrated that mcc pair is very important to the regional lithospheric thinning. The results of this research list below:(1) Liaonan metamorphic core complex has a three-layer structure and is constituted by five parts. Different types of fault rocks(from mylonitic gneissto pseudotachylites) giving clues to the evolution of the detachment fault zone. The detachment fault of Liaonan mcc is characterized by typical corrugation, the emplacement of granitic plutons contributed to the development of the corrugation.(2) This research reveals the existence of a new metamorphic core complex (mcc), i.e. the Wanfu mcc for the first time. The Wanfu mcc has a three-layer structure. Stretching lineation indicate uniform top-to-SEE shearing along the main detachment fault zone.(3) The zircon U-Pb dating results of Five samples from different part of the two mccs indicate that the volcanic rocks form in two periods: pre-tectonic type(SL0530,169±8 Ma)and syn tectonic type(SL0585,123±7 Ma) magmatic activities; granites in three periods: pre-tectonic type(SL05103,166±4 Ma), syn-tectonic type(SL0543,124±3 Ma) and post- tectonic magmatic activities. The extraordinary same age of pre-tectonic type and syn-tectonic type vocalnic and granite rocks make us know that the time of the magmatic events is coincident.(4) The Wanfu mcc and Liaonan mcc form a mcc pair. They share many common features. The occurrence of the mcc pair and some suspected mcc’s to the east of Wanfu area provide new evidences for discussion on the mechanical and rheological behavior and thinning processes of the North China plate in late Mesozoic.(5) The evolution geochronological framework of Liaonan-Wanfu mcc pair provides important evidence to the lithospheric extension and thinning of North China craton. We considered that the emplacement of Zhaofang intrusion(113 Ma) marks the termination of a series of tectono-magamtic activities during regional extension.(6) Liaonan, Wanfu mcc have unification with extensional structures of other aeras in deformation time and movement regularity. It reveals the lithosphere in the whole east Asia experienced intense extension and lithosphere thinning during late Mesozoic. Shearing was the dominant mechanism of the regional extension and the detachment mainly occurred in shallow to middle crust.更多还原