摘要
铭杨岩体位于甘肃北山南带古堡泉-红柳园断裂北侧,侵位于敦煌岩群,为甘肃北山地区新近发现的一处铜镍矿化镁铁-超镁铁岩体,主要由辉橄岩、二辉橄榄岩、橄榄辉长岩、辉长岩等组成。全岩成分以低碱、低钛为特征,轻稀土略富集,具有明显的正Eu异常;富集大离子亲石元素(LILE)Rb、Ba、Sr和K,相对亏损高场强元素(HFSE)Th、U、Nb、Ta、Zr和Hf。岩浆演化过程中发生了橄榄石、斜长石和辉石的分离结晶作用,经历了一定程度的地壳混染,地、物、化、遥综合信息显示具有较好的铜镍成矿潜力。通过LA-ICP-MS锆石U-Pb测年,首次获得铭杨岩体中橄榄辉长岩和辉长岩结晶年龄分别为(452.9±2.4)Ma和(457.7±2.1)Ma,岩体可能为早古生代陆缘裂谷环境下的产物。北山地区早古生代含铜镍岩体的发现对区域构造演化认识具有重要意义。
The Mingyang rock body is a newly discovered copper-nickel mineralized Mafic-Ultramafic rock body,which is located on the north side of the gubaoquan-hongliuyuan Fault in the southern belt of Beishan,Gansu.The rock intruding in the Dunhuang rock group,which mainly composed of gabbro,diabase peridotite,olivine gabbro,gabbro,etc.The rock composition is characterized by low alkali and low titanium,slightly enriched in light rare earths,with obvious positive Eu anomalies;enriched in large ion-lithophile elements(LILE)Rb,Ba,Sr and K,and relatively deficient in high field strength elements(HFSE)Th,U,Nb,Ta,Zr and Hf.During the magmatic evolution,the separation and crystallization of olivine,plagioclase and pyroxene occurred,it has experienced a certain degree of assimilation and contamination.The geological,geophysical and geochemical information show that it has the better potential of copper and nickel ore.The first crystallization ages of(452.9±2.4)Ma and(457.7±2.1)Ma for olivine gabbro and gabbro in the Mingyang rock mass were obtained by LA-ICP-MS zircon U-Pb dating.The rocks may be the products of the Early Paleozoic continental margin rifting environment.The discovery of early Paleozoic Cu-Ni-bearing rocks in the Beishan area is of great significance to the understanding of regional tectonic evolution.
作者
谢燮
杨建国
张东阳
程功德
XIE Xie;YANG Jianguo;ZHANG Dongyang;CHENG Gongde(Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits,MNR,Xi’an Center of CGS,Xi’an 710119,Shaanxi,China;State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430078,Hubei,China;Baoji No.717 Brigade Company Ltd.of Northwest Nonferrous Metals,Baoji 721000,Shaanxi,China)
出处
《西北地质》
CSCD
北大核心
2024年第1期179-195,共17页
Northwestern Geology
基金
中国地质调查局项目“天山-北山成矿带那拉提-营毛沱地区地质矿产调查”(DD20160009)
“东天山昌吉-双沟山地区区域地质调查”(DD20190065)联合资助。
