安徽栏杆地区辉绿岩型原生金刚石特征及成因初探  

Characteristics and genetic studies on primary diamonds from mafic rocks in Lan'gan area,Anhui Province

作　　者：朱仁智 倪培[1] 马玉广 盛中烈[3] 丁俊英 王国光[1] 管申进[4] Zhu Renzhi1 ,Ni Pei1 ,Ma Yuguang2 ,Sheng Zhonglie3 ,Ding Junying1, Wang Guoguang1 ,Guan Shenjin4(1.State Key Laboratory for Mineral Deposit Research, Institute of Geo-Fluids, School of Earth Science and Engineering, Nanjing University, Nanjing, 210023, China; 2.The Second Institute of Hydrology and Engineering Geological Prospecting of Anhui Geological Prospecting Bureau, Wuhu, 241000, China ;3. Anhui Department of Land and Resources, ttefei, Anhui, 230088, China ;4.Southwest Institute of Geological Survey,Geological Survey Center for Non-ferrous Mineral Resources, Kunming University of Science and Technology, Nunming, 650093, Chin)

机构地区：[1]内生金属矿床成矿机制研究国家重点实验室,地质流体研究所,南京大学地球科学与工程学院,南京210023 [2]安徽省地勘局第二水文工程地质勘查院,芜湖241000 [3]安徽省国土资源厅,合肥230088 [4]昆明理工大学有色金属矿产地质调查中心西南地质调查所,昆明650093

出　　处：《南京大学学报（自然科学版）》2018年第2期278-295,共18页Journal of Nanjing University（Natural Science）

基　　金：安徽省国土资源科技项目(2011-K-12,2015-K-9)

摘　　要：安徽栏杆地区位于华北克拉通东部陆块东南缘,该区新元古代地层中发育含原生金刚石的辉绿岩.不同于山东蒙阴和辽宁瓦房店金刚石容矿岩石为金伯利岩,栏杆地区金刚石容矿岩石为基性岩,这在我国尚属首例.对栏杆地区金刚石展开了形态学、拉曼光谱和红外光谱的研究,并对金刚石容矿岩石进行了岩相学和年代学研究.结果表明栏杆地区金刚石呈黄绿色-黄褐色,透明,金刚石光泽,高硬度,晶形良好,为八面体和菱形十二面体,粒径0.1~0.5mm,集中在0.2~0.35mm,在1332cm^(-1)出现典型金刚石拉曼谱峰.金刚石红外光谱中出现1130cm^(-1)谱峰,未出现1282cm^(-1)和1175cm^(-1)谱峰,为Ib型金刚石.岩相学结果表明金刚石容矿岩石为辉绿岩.斜锆石SIMS Pb-Pb定年结果表明辉绿岩形成年龄为912~914Ma,代表了区域上一期新元古代基性岩浆作用事件,该期事件形成了栏杆地区原生金刚石.栏杆地区橄榄玄武岩和玄武质角砾熔岩中捕获了含金刚石的辉绿岩角砾,导致岩石中含有极少量的金刚石.Lan＇gan area is located in the southeastern margin of the North China Craton（NCC）. In this area, the Neoproterozoic strata were intruded by a large amount of dolerites and the latter is diamondiferous. It＇s the first time to find diamonds in mafic rocks in China,which are different from diamondiferous kimberlites in Mengyin and Wafangdian areas in NCC. Studies on the morphology,Raman spectrum, and infrared spectrum were carried out on the diamond,and researches of the petrography and chronology were conducted on the diamondiferous mafic rocks. The results show that diamonds are yellow-green or yellow-brownish color, transparent, and adamantine luster. They have high hardness and cube or dodecahedron crystal. These diamonds are 0.1 ~ 0.5 mm in size, mainly 0.2 ~ 0.35 mm,and show typical diamond peak at 1332 cm^-1 in Raman spectrum. Infrared spectrum results show that these diamonds have peak at 1130 cm^-1 without peaks at 1282 cm^-1 or 1175 cm^-1 ,which suggests that these diamonds can be classified as Ib type. This type of diamond is different from other types of diamonds in kimberlites in NCC, which indicates that these diamonds were rapidly removed from mantle environment after formation,and nitrogen in diamond has not yet been converted in time. Petrographic observation indicates that diamondiferous mafic rocks are mainly dolerite. Compared with non-xenoliths dolerites,the olive basalt and basaltic boulder lava have few diamonds and dolerite xenoliths. The geneses of diamonds in these three mafic rocks are not same： diamonds in dolerites are primary^and diamonds in olive basalt and basaltic boulder lava are derived from dolerites xenoliths in host rocks. SIMS Pb-Pb baddeleyite dating shows that dolerites have crystallization age at 913 ~ 10 Ma, which represents Neoproterozoie mafic magmatism in Lan＇gan area. During this event, diamonds formed. It is believed that the formation of diamond is nearly simultaneously with the formation and migration of basic magma.

关 键 词：原生金刚石 矿物特征 成因探究 辉绿岩 栏杆地区 安徽省 

分 类 号：P619.24[天文地球—矿床学]