收稿日期: 2012-07-24
修回日期: 2012-08-27
网络出版日期: 2012-10-10
基金资助
国家自然科学基金项目“广西大新铀矿成矿物质来源研究”(编号：41173059)；中国核工业地质局重点科研项目“西南地区深部地质过程与铀成矿作用”（编号：201148）；广西地矿局项目“广西大新地区铀成矿规律及找矿方向”资助.
Geological，Geochemical and Chronology Characteristics and Its Significance of the Dolerite in Daxin, Guangxi Province
Received date: 2012-07-24
Revised date: 2012-08-27
Online published: 2012-10-10
广西大新地区位于华南板块南华活动带右江褶皱系西大明山凸起，大新凹断束，那岭—俸屯褶断地垒的北端，辉绿岩脉沿断裂呈北西向零星分布。该区产有铀矿、铅锌矿等矿产资源。前人在进行矿床成因等研究时没有将辉绿岩脉与矿床的形成联系起来。通过研究辉绿岩的地质、地球化学和年代学特征，对二者的关系进行了探讨，取得如下认识：①该区辉绿岩分布受北西向断裂控制，并且遭受了后期变质作用和蚀变作用，使其主要由高岭石、蛇纹石、绿泥石等蚀变矿物组成，局部地段有铀矿化。②辉绿岩的SiO2含量变化较大，主要由后期硅化导致。Fe2O3，MgO，CaO及FeO与SiO2呈明显的负相关，碱质程度（Na2O+K2O）较贫，K2O/Na2O比值较大，为钙碱性系列。微量元素富集高场强元素Ta，Nb，Zr，Hf，及大离子亲石元素Rb，U，Th，Ba，而亏损Sr，构造环境判别为板内玄武岩（WPB）。稀土元素球粒陨石标准化分布型式图呈右倾，稀土元素总量较高，轻稀土较重稀土富集，无明显Eu异常。③辉绿岩的锆石U-Pb年龄总体为90 Ma左右，形成于晚白垩世。④辉绿岩脉与该区矿产资源的形成有一定关系。
徐争启，程发贵，唐纯勇，宋 昊,张成江，倪师军，郭景腾，祁家明 . 广西大新地区辉绿岩地质地球化学、年代学特征及其意义[J]. 地球科学进展, 2012 , 27(10) : 1080 -1086 . DOI: 10.11867/j.issn.1001-8166.2012.10.1080
Guangxi Daxin is located in south China plate of the South China region, the west of Youjiang drape, the north end of daming mountain convex, Daxin concave broken beam, and the ridgeFengTun broken plait horst. The dolerite dikes are distributed sporadically in the north west, along the crack. There are the abundance mineral resources in the region, such as uranium deposits and Pb, Zn. Previous study of ore genesis did not connect the dolerite dikes with the formation of deposit. Through studies of dolerite of the geological, geochemical characteristics and chronology, the relationship between the two is discussed and the conclusions are drawn in this article as follows: (1) Dolerite are controlled by the crack in north west, and the dolerite is made up of altered mineral such as kaolinite, hauling, chlorite, and uranium mineralized in local area, suffering the later metamorphism and altered effect. (2) The content of SiO2 in rocks has a large variation, mainly caused by chloride. SiO2 is obviously negatively correlated with Fe2O3, MgO, CaO and FeO. Alkali degree (Na2O+K2O) is poor. Based on the big ratio of K2O/Na2O, the magma series is for calcium alkaline series. Trace element enriches high field strength element Ta, Nb, Zr, Hf, and big ion lithophile element Rb, U, Th, Ba, and losses Sr. Therefore, tectonic environment is distinguished as the plate basalt (WPB). Rare earth elements the chondritic standardized distribution type is more consistent figure right mode, no obvious Eu abnormal, the total amount of rare earth elements is higher. (3) The U-Pb age of zircons in dolerite rock is overall for 90 Ma or so, developed in late cretaceous. (4) We can speculate that areal mineralization and dolerite are involved in the creation of rock.
Key words： Guangxi Daxin; Dolerite; Geochemistry; Chronology; Metallogenesis.
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