CAJ | 학술논문

利用LA-MC-ICP-MS锆石U-Pb测年获得马兰峪背斜核部前分水岭二长花岗岩、茅山二长花岗岩、王坪石二长花岗岩、高家店石英闪长岩、肖营子花岗闪长岩及钾长花岗岩的结晶年龄分别为(153.8±2.7) Ma、(162.7±1.5) Ma、(162.3±1.3) Ma、(170.5±1.8) Ma、(164.6±2.2) Ma和(186.8±1.3) Ma,同时获得180~175 Ma和201~186 Ma的继承岩浆锆石年龄,时代上分属于印支期和燕山期,以燕山期为主；岩石地球化学特征表明其岩浆来源于上地幔物质底侵引起下地壳部分熔融。结合区域地质资料分析,本文认为：1)马兰峪背斜开始形成于印支期,完成于燕山期；2)印支—燕山期强烈构造运动不但使地台基底与盖层同步卷入褶皱作用,地壳缩短加厚,而且使上地幔物质底侵,下地壳物质部分熔融,从而形成了一系列发育于背斜核部的侵入岩体；3)燕山地区中生代造山作用,并不只是地壳表层的物质运动,而是涉及全地壳以至上地幔的物质运动,它使中朝地块北部由原来稳定克拉通状态进入一个全面活化的新阶段。
이용LA-MC-ICP-MS고석U-Pb측년획득마란욕배사핵부전분수령이장화강암、모산이장화강암、왕평석이장화강암、고가점석영섬장암、초영자화강섬장암급갑장화강암적결정년령분별위(153.8±2.7) Ma、(162.7±1.5) Ma、(162.3±1.3) Ma、(170.5±1.8) Ma、(164.6±2.2) Ma화(186.8±1.3) Ma,동시획득180~175 Ma화201~186 Ma적계승암장고석년령,시대상분속우인지기화연산기,이연산기위주；암석지구화학특정표명기암장래원우상지만물질저침인기하지각부분용융。결합구역지질자료분석,본문인위：1)마란욕배사개시형성우인지기,완성우연산기；2)인지—연산기강렬구조운동불단사지태기저여개층동보권입습추작용,지각축단가후,이차사상지만물질저침,하지각물질부분용융,종이형성료일계렬발육우배사핵부적침입암체；3)연산지구중생대조산작용,병불지시지각표층적물질운동,이시섭급전지각이지상지만적물질운동,타사중조지괴북부유원래은정극랍통상태진입일개전면활화적신계단。
LA-MC-ICP-MS U-Pb dating of zircons from the Qianfenshuiling monzonitic granite, Maoshan monzonitic granite, Wangpingshi monzonitic granite, Gaojiadian quartz diorite, Xiaoyingzi granodiorite and moyite yielded (153.8±2.7) Ma, (162.7±1.5) Ma, (162.3±1.3) Ma, (170.5±1.8) Ma, (164.6±2.2) Ma and (186.8±1.3) Ma respectively, and several inheritable magmatic zircons were dated at 180~175 Ma and 201~186 Ma. The results indicate that the Mesozoic intrusive bodies along the core of the Malanyu anticlinorium were emplaced in the Indosinian and Yanshanian, with the latter being predominant. Their geochemical characteristics show that the magma was generated from partial melting of lower crustal material caused by the upper mantle underplating. Combining these data with the regional geological information, the authors have reached some conclusions: 1) the Malanyu anticline was initiated in the Indosinian period, and formed finally in the Yanshanian period; 2) the Indosinian-Yanshanian orogeny not only contributed to the crust thickening characterized by basement-involved folding but also resulted in partial melting of the lower crust, bringing about the fromation of intrusive bodies along the anticlinal core; and 3) the Mesozoic orogeny in the Yanshan area was represented not only by the tectonic process of the surface of the crust but also by the movement of the lower crust and upper mantle, which caused the northern part of the Sino-Korean block to enter into a new evolutionary stage, i.e., from the original stability to overall activation.