CAJ | 학술논문

德尔布干断裂带是大兴安岭隆起西侧NE向的重要断裂带,处在海拉尔-拉布达林-根河盆地西缘,是著名德尔布干成矿区东南边界断裂带.为了确定德尔布干断裂带运动性质、活动时间,深入探讨该断裂带与中生代海拉尔-拉布达林-根河盆地及大兴安岭盆山格局、认识德尔布干断裂带多金属矿床成因等问题,本文应用锆石SHRIMP和云母~(40)Ar/~(39)Ar定年技术,分别对断裂带内的细粒黑云母花岗岩侵入体、韧性变形的花岗闪长质片麻岩、白云母石英片岩,进行了同位素年代学研究.其中花岗闪长质片麻岩岩浆型锆石SHRIMP谐和年龄300.6±9.3Ma,为花岗闪长质片麻岩海西期的侵位年龄;而花岗闪长质片麻岩中黑云母~(40)Ar/~(39)Ar坪年龄是130.9±1.4Ma,白云母石英片岩的白云母~(40)Ar/~(39)Ar坪年龄是115.6±1.6Ma,代表早白垩世伸展构造变形年龄;细粒黑云母花岗岩侵入体岩浆型锆石SHRIMP谐和年龄130.1±1.4Ma,为同伸展构造变形侵位的岩浆事件.上述地质年代说明德尔布干断裂带是早白垩世(110～130Ma)该区最年轻的重大伸展构造变形产物.控制NE向大兴安岭隆起和中生代海拉尔-拉布达林-根河等火山沉积盆地的发育格局、以及中生代以来的地壳演化与成矿类型.
덕이포간단렬대시대흥안령륭기서측NE향적중요단렬대,처재해랍이-랍포체림-근하분지서연,시저명덕이포간성광구동남변계단렬대.위료학정덕이포간단렬대운동성질、활동시간,심입탐토해단렬대여중생대해랍이-랍포체림-근하분지급대흥안령분산격국、인식덕이포간단렬대다금속광상성인등문제,본문응용고석SHRIMP화운모~(40)Ar/~(39)Ar정년기술,분별대단렬대내적세립흑운모화강암침입체、인성변형적화강섬장질편마암、백운모석영편암,진행료동위소년대학연구.기중화강섬장질편마암암장형고석SHRIMP해화년령300.6±9.3Ma,위화강섬장질편마암해서기적침위년령;이화강섬장질편마암중흑운모~(40)Ar/~(39)Ar평년령시130.9±1.4Ma,백운모석영편암적백운모~(40)Ar/~(39)Ar평년령시115.6±1.6Ma,대표조백성세신전구조변형년령;세립흑운모화강암침입체암장형고석SHRIMP해화년령130.1±1.4Ma,위동신전구조변형침위적암장사건.상술지질년대설명덕이포간단렬대시조백성세(110～130Ma)해구최년경적중대신전구조변형산물.공제NE향대흥안령륭기화중생대해랍이-랍포체림-근하등화산침적분지적발육격국、이급중생대이래적지각연화여성광류형.
Derbugan fault zone, a NE tending fault zone in the West of the Great Xing' an Range uplift and along the western margin of the Hailar-Labudalin-Genhe basins, is the famous zone which is the NS boundary fault zone of the Derbugan metallogenic belt. In order to understanding the character for the activity and timing of this fault, and its relations to the Hailar-Labudalin-Genhe basins, and polymetal ore deposit along this fault, we show the SHRIMP zircon and mica ~(40)Ar/~(39)Ar dating for the granule-biotite granitic vein, granodioritic gneiss with ductile deformation and mica-quartz schist in this fault zone. SHRIMP zircon U-Pb dating of the granodioritic gneiss yield concordant age of 300.6±9.3Ma, together with its igneous zircon in CL image, indicate that age of 300. 6±9. 3Ma is the protolith ages for this gneiss. The biotite ~(40)Ar/~(39)Ar dating also from this granodioritic gneiss, which yield the plateau age of 130.9± 1.4Ma, together with the biotite ~(40)Ar/~(39)Ar plateau age of 115.6±1.6Ma from the mica-quartz schist, indicate that those ages between the 115～130Ma are the extensional event ages at the Early Cretaceous in the Derbugan fault zone. The granule-biotite granitic vein also analyzed by the SHRIMP method, which yield the concordant age of 130.1±1.4Ma with the igneous zircon in CL image, indicate that age of 130.1±1.4Ma are the protolith age and incursion due to the syn-extensional event during the Yanshanian in this fault zone. Those results from this study, suggest that the Derbugan fault zone is the youngest extensional structure with the ages between 110～130Ma during the Yanshanian in this area. Derbugan fault zone has dominated the framework of the Mesozoic volcanism in the Hailar-Labudalin-Genhe basins, the crust evolutions and ore-forming types in the Great Xing' an Range. Therefore the Derbugan fault zone with the extensional event ages of 115～130Ma are the typical evidence for the intra-continental orogen at Yanshanian during the Mesozoic.