长白山玄武岩覆盖区新太古代基底性质：U-Pb锆石年代学和地球化学证据

发布时间：2018-03-01 07:47

本文关键词： 长白山地区第四系玄武岩晚太古代基底和龙地块白山地块　出处：《吉林大学》2017年硕士论文　论文类型：学位论文

【摘要】：长白山新生代火山岩覆盖区之下存在新太古代变质结晶基底,主要由白云母二长花岗岩、花岗质片麻岩和黑云斜长(角闪)片麻岩等组成。锆石U-Pb测年结果揭示这些岩石的形成时代均为新太古代,其中,花岗岩和花岗片麻岩的锆石年龄介于2509~2558Ma之间,黑云斜长(角闪)片麻岩的锆石年龄介于2475~2553Ma之间;岩石地球化学特征显示,这些岩石均具有奥长花岗岩-英云闪长岩-石英闪长岩(TTG)岩系特征。上述特征与长白山新生代玄武岩覆盖区外围的白山地块和和龙地块中的太古代变质岩系完全一致,表明玄武岩区之下存在与外围两地块组成一致的新太古代变质结晶岩系,揭示出白山地块与和龙地块在晚太古代曾是一个统一的陆块(龙岗陆块)。目前,东部的和龙地块和西部的白山地块的分布格局是后期构造改造的结果,说明新生代玄武岩之下隐伏有北东向的左行走滑断层。该走滑断裂的性质及时代应与敦密断裂带有密切关系。
[Abstract]:The Mesozoic metamorphic crystalline basement of the Cenozoic volcanic rocks in Changbai Mountain is mainly composed of Muscovite monzogranite. The results of U-Pb zircon dating indicate that the ages of these rocks are NeoArchean, in which the zircon ages of granite and granitic gneiss are between 2509 and 2558 Ma, and the zircon ages of granitic gneiss and granitic gneiss are between 2509 and 2558 Ma. The zircon age of the long (hornblende) gneiss is between 2475 and 2553 Ma. These rocks all have the characteristics of the Ordovician granite, dolomite diorite and quartz diorite rock series TTG. The above characteristics are identical with those of the Baishan block and the Archean metamorphic rock series in the Cenozoic basalt covering area of Changbai Mountain, and the Archean metamorphic rock series in the long block. This indicates that there are NeoArchean metamorphic crystalline rocks under the basalt area, which are consistent with the composition of the two blocks in the periphery. It is revealed that the Baishan block and the Helong block were once a unified continental block (Longgang block) in the late Archean. The distribution pattern of the Hulong block in the east and the Baishan block in the west is the result of the later structural transformation. It is suggested that there is a left strike slip fault in the north to east direction under the Cenozoic basalt. The nature and age of the strike slip fault should be closely related to the Dumi fault zone.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P597.3;P534.2

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