豫西南南秦岭石墨成矿带地质特征及找矿潜力

Geological Characteristics and Prospecting Potential of the South Qinling Graphite Metallogenic Belt in Southwestern Henan Province

豫西南南秦岭石墨成矿带分布于淅川县小陡岭蒲堂老灌河一带,地处秦岭造山带东段南支,木家垭内乡断裂与淅川断裂之间。为查明区域石墨矿床的地质特征、成矿规律、矿床规模、矿石特征和矿床成因等,相继开展了矿产普查、预查工作,并对整个成矿带开展了调查研究。结果表明:①石墨矿赋存于古元古代大沟岩组中,石墨斜长片麻岩、石墨片岩是石墨矿的主要赋存层位,矿层受地层控制明显,矿体与矿层基本吻合;②矿层多分布于成矿带西段和东段,中段较少,西段矿层多赋存于大沟岩组上部岩石组合中,中段及东段矿层赋存于中部岩石组合中;③西段矿石类型多为石墨斜长片麻岩型,少量为石墨片岩型,中段和东段多为石墨片岩型,少量为石墨斜长片麻岩型;④含碳沉积建造和区域变质作用是石墨矿床的主要成矿控制因素,成矿期为中、新元古代。在上述分析的基础上,经过矿产勘查,在该成矿带上相继提交了小陡岭、徐家湾李家营、下大扒、柳树沟4个大型、特大型石墨矿产地;圈定了3处找矿靶区,靶区内矿产地外围均发现了规模较大的石墨矿层。综合成矿预测结果表明:豫西南南秦岭石墨成矿带远景资源量可达上亿吨,将成为我国重要的石墨矿开采基地。

South Qinling graphite metallogenic belt in southwestern Henan Province is distributed in Xiaoduling-Putang- Laoguanhe area of Xichuan County.It is located in the south branch of the eastern section of Qinling orogenic belt,and it is dis-tributed between Mujiaya-Nixiang fault and the Xichuan fault.In order to find out the geological characteristics of the graphite deposits,metallogenic regularity,scale of the deposits,ore characteristics and deposit genesis,general survey and preliminary survey of the deposits are conducted,besides that,geological investigation of the whole metallogenic belt is done.The analysis results of the above geological data show that:①the graphite deposits are occurred in Paleoproterozoic Dagou Formation,graph-ite plagioclass gneiss and graphite schist are main occurrence layers of graphite orebodies,the ore-bearing layers are clearly controlled by strata,and the orebodies are basically consistent with the ore-bearing layers;②ore-bearing layers are mostly dis-tributed in the western and eastern sections of the metallogenic belt,ore-bearing layers of the middle section of the metallogen-ic belt are few,the western sections of ore-bearing layers are mostly distributed in the upper rock combination of Dagou Forma-tion,and the middle and eastern sections of ore-bearing layers are distributed in the central rock combination of Dagou Forma-tion;③most of the ore types of the western sections of ore- bearing layers are graphite plagioclass gneiss type,and a small amount is graphite schist type,ore types of the middle and eastern sections of ore- bearing layers are mostly graphite schist type,and small amount of graphite plagioclass gneiss type;④carbon-bearing sedimentary construction and regional metamor-phism are the main metallogenic controlling factors of graphite deposits,and the metallogenic period is Middle and Neoprotero-zoic.Based on the above analysis results,through mineral prospecting,four large and extra large graphite orefields named Xiao-douling,Xujiawan- Lijiaying,Xiadapa and Liushugou are determined in South Qinling graphite metallogenic belt,and three prospecting target areas are delineated,graphite deposits with large scale are found on the periphery of the orefields in the prospecting target areas.The comprehensive metallogenic predictions results show that the potential resources of South Qinling graphite metallogenic belt in Southeastern Henan Province can reach up to hundreds of millions of tons,which will become an important graphite mining base in our country.