华北典型晶质石墨矿床成因研究

发布时间：2018-04-26 16:53

本文选题：石墨 + 混合岩化型　；参考：《辽宁工程技术大学》2015年博士论文

【摘要】：华北克拉通(简称华北)为全球最古老(-3.8 Ga)克拉通之一,在其地壳演变过程中发生了一系列的重大地质事件,包括陆核发育,结晶基底形成,克拉通裂解、汇聚、拼贴,盖层发育,沉积变质和岩浆活动等；重大地质事件发生的同时产生了大规模的石墨矿化作用,形成了丰富的石墨资源。2004年,由于石墨烯的发现,石墨矿产战略地位突出,国际掀起新一轮的石墨勘查找矿热潮；华北独有的石墨成矿地质条件,应为国内找矿重点区域,但由于以往对华北石墨矿床研究程度较低,仅对个别矿床在成矿地质特征和矿床成因等方面做过一些研究,不仅制约了石墨找矿工作的开展,而且在一定程度上限制了国家对其进行具体的战略规划。作者通过对华北区域成矿地质背景和已有石墨矿床地质资料的系统研究,划分出胶东、华北北缘、秦岭、辽吉4个石墨成矿带和莱西-平度、朱阳关-柳泉铺等12个成矿亚带。选择成矿带内典型石墨矿床,对其成矿地质特征进行分析,得出矿床赋矿层位为中深变质岩系,具有典型的孔兹岩系特征；含矿岩石类型主要为富铝的片麻岩、片岩、变粒岩、透辉岩和大理岩；矿体主要受褶皱控制,褶皱具有变质成矿所需的封闭还原环境,使石墨在此富集、储存；石墨形成与区域变质作用密切相关,变质程度越高,石墨晶体越大；后期的混合岩化作用,一方面促进石墨进一步富集生长,另一方面造成局部矿体相对贫化。对采集样品进行岩石化学处理分析,主量元素特征显示出样品硅质页岩的Si02含量在80%左右,碳酸盐岩Si02含量多小于30%,花岗岩SiO2含量在50%-70%之间，具有富碱和陆源物质等特征,反映出原岩沉积环境为浅海大陆架或陆相裂谷沉积环境,原岩主要为一套富碳质、富铝的泥质岩,夹中基性火山岩及碳酸盐岩；微量元素特征显示富集Rb、U、La、Nd、Sm,亏损Sr、Ba、 Th、Nb的规律,Rb/Sr和Sr/Ba比值反映出变质原岩主要为陆源沉积特征,Th/U、V/V+Ni和V/Cr比值反映出缺氧的沉积变质环境；稀土元素显示出轻稀土富集、重稀土亏损,呈右倾型曲线,6 Ce值均为1左右,6 Eu值多小于1,稀土配分曲线图整体显示出弱负铕异常而无铈异常,反映出原岩沉积环境为太古代后期陆棚相沉积特征。对采集的石墨样品进行锆石SHRIMP U-Pb定年,胶东成矿带莱西南墅石墨矿成矿时代为1.82 Ga-1.86Ga,为古元古代晚期；华北北缘成矿带兴和黄土窑石墨变质成矿作用开始于1.97Ga,为古元古代晚期；秦岭成矿带小岔沟石墨变质成矿作用开始于2.08Ga,为古元古代中期,辽吉成矿带张家堡石墨变质成矿作用开始于2.36Ga,为古元古代早期,四个典型矿床的变质成矿初始年龄均与所在地层年代相吻合,同时与石墨矿床多期变质叠加特征相吻合。对华北众多石墨矿床的碳同位素δ13C测试分析,δ13C‰数值范围为-6.72‰～-28.93‰(绝大部分在-18‰～-28.93‰之间),通过与现代有机物、地质各时代有机生物和碳酸盐岩的δ13C‰数值对比,结果表明石墨中的碳主要来自有机碳(区域变质作用形成),少数来自无机碳(混合岩化作用形成)。通过对典型石墨矿床的成矿地质特征、地球化学特征、年代学特征和13C同位素特征的研究,华北石墨矿床成因类型主要为混合岩化型。综合混合岩化型石墨矿床的控矿条件及找矿标志,建立综合信息找矿预测模型；依据综合信息找矿预测模型,选择有利找矿靶区,首先开展勘查找矿工作,并在内蒙古大乌淀、辽宁杜屯和张家堡取得重大找矿成果,使得成矿模型和找矿模型的科学性得到了很好的验证,表明综合信息找矿预测模型对区内石墨找矿具有重要的指导意义,且混合岩化型石墨矿床仍是今后区内重点找矿类型。
[Abstract]:North China Craton ( North China ) is one of the world ' s oldest ( - 3.8 Ga ) craton , and a series of major geological events occurred during the evolution of the crust , including continental nucleus development , crystalline basement formation , craton cleavage , convergence , splicing , cap development , sedimentary metamorphism and magmatic activity .
In 2004 , due to the discovery of graphene , the strategic position of graphite was outstanding , and a new upsurge of graphite exploration was launched in 2004 .
In this paper , 12 metallogenic subzones , such as Jiaodong , North Margin of North China , Qinling , Liaoji , 4 graphite metallogenic belts and Laixi - Ping , Zhuyangguan - Liuquan pu , are divided into the typical graphite deposits in North China .
The ore - bearing rock types are mainly aluminum - rich gneiss , slate , metamorphic rock , diaphorite and marble ;
The ore body is mainly controlled by the fold , and the fold has the enclosed reduction environment required for the metamorphic ore - forming , so that the graphite is enriched and stored ;
Graphite formation is closely related to the regional metamorphism , and the higher the degree of metamorphism , the larger the graphite crystal ;
The results show that the content of Si02 of the sample siliceous shale is about 80 % , the content of Si02 in carbonate rocks is less than 30 % , the content of SiO2 in carbonate rocks is between 50 % and 70 % , and it has rich alkali and terrigenous materials .
The trace elements show that the enrichment of Rb , U , La , Nd , Sm , loss Sr , Ba , Th , Nb and Rb / Sr and Sr / Ba ratio reflect that the metamorphic rock is mainly terrigenous sedimentary characteristics , Th / U , V / V + Ni and V / Cr ratio reflect the sedimentary metamorphic environment of hypoxia ;
The rare earth element shows light rare earth enrichment , heavy rare earth loss , right dip curve , 6 Ce value is about 1 , the value of 6 Eu is more than 1 , the REE distribution graph shows weak negative europium anomaly and no Ce anomaly , which reflects the sedimentary environment of the primitive rock is Archean early stage continental shelf facies sedimentary characteristics . The zircon U - Pb dating for the collected graphite samples is 1 . 82 Ga - 1.86Ga , which is the late Proterozoic era ;
The mineralization of the North Margin of North China and the metamorphism of the graphite in the loess kiln begin at 1.97Ga , which is the late Proterozoic ;
In this paper , the authors suggest that carbon isotope 未13C test and geochemical characteristics , chronology features and 13C isotopic characteristics of many graphite deposits in North China show that carbon in the graphite is mainly from organic carbon ( formation of regional metamorphism ) and minority is from inorganic carbon ( formation of mixed rock ) .
According to the comprehensive information prospecting prediction model , the favorable prospecting target area is selected , and the prospecting and prospecting work is carried out firstly , and significant prospecting results are obtained in the Dawu Lake , Liaoning Datun and Zhangpu , Inner Mongolia , so that the ore - forming model and the scientific nature of the prospecting model are well verified , and the comprehensive information prospecting prediction model has important guiding significance to the graphite prospecting in the region , and the mixed rock type graphite deposit is still the main prospecting type in the future .

【学位授予单位】：辽宁工程技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：P619.252

【参考文献】