【作者】 王伟；

【导师】 李文渊；

【作者基本信息】 长安大学 ， 构造地质学， 2007， 硕士

【摘要】 本文依托南秦岭平利地区南北4幅1:5万矿产远景调查,在充分搜集研究前人资料的基础上,通过野外实际路线和矿点调查及重要样品实验测试研究,重点对平利地区的区域地质和矿产特征、重要矿化类型及成矿特点进行了研究,探索了以花桥钛磁铁矿为代表的重要成矿类型,并研究分析了平利地区主要矿化类型的找矿远景。取得了以下主要成果和进展。1.平利地区地处扬子陆块与秦岭造山带结合部位,主要出露有基底中元古界杨坪组,由绢云绿泥片岩和绢云钠长片岩等组成,上覆有南华系耀岭河组的变质火山岩系、震旦系陡山沱组的碳硅质板岩和灯影组白云质灰岩等,早古生代主要沉积了一套被动大陆边缘还原相的硅质岩、灰岩和碳质板岩等,自泥盆纪以后地层缺失;区内岩浆作用微弱,岩浆岩出露有限,主要发育有南华系基性火山岩和奥陶纪碱性辉长岩类两期岩浆事件,分别代表Rodinia超大陆裂解在秦岭地区的响应和早古生代大陆板内构造—岩浆事件。现有构造和地形地貌是印支期构造运动的结果。2.平利地区整体矿化较弱,仅发现有一些工作程度较低的矿点、矿化点,主要成矿类型为与奥陶纪碱性辉长岩类有关的岩浆分异型钛磁铁矿,产于震旦纪灯影组灰岩中的MVT型铜铅锌矿和主要分布于寒武纪鲁家坪组碳硅质岩中的沉积改造型钒钼矿等。其中,钛磁铁矿有较好找矿远景,已发现有中小型成矿潜力的花桥矿点;产于灯影组灰岩中的铜铅锌矿化,区域成矿分析与扬子北缘MVT型铅锌矿处于同一层位,可能是该类型矿产在本研究区的表现,但研究区产于灯影组灰岩中的罗家院子矿点,以铅锌含量较低（0.01—1.68%）,铜含量高（2.56—17.25%）为特点,与区域上扬子型MVT铅锌矿在矿种上有显著差异;寒武系中的钒钼矿目前尚未见有工业意义的矿化,可能是成矿元素富集不足。3.花桥钛磁铁矿作为区域上较有价值的与碱性辉长岩类有关的金属成矿类型,本论文进行了较为深入的研究。花桥钛磁铁矿可见赋矿岩体长约250m,宽8—10m,面积约2500m²,岩体呈透镜体状,岩石类型主要为辉石岩、辉长岩等,主要含矿岩相为黑云母辉石岩,岩石主要由含钛普通辉石组成,其次为黑云母。含钛普通辉石呈自形一半自形晶,见微量磷灰石和榍石,岩石绿泥石化、碳酸盐化明显。钛磁铁矿体产于岩体中部,与岩体呈过渡关系,无清楚界线,矿石主要为稠密浸染状,主要金属矿物为钛磁铁矿、钛铁矿、磁铁矿和少量黄铁矿。4.花桥钛磁铁矿赋矿岩石岩石地球化学全碱—硅图解投图,主要落入碱性辉长岩中,但与一般碱性辉长岩相比,SiO₂较低,已获样品SiO₂在42.82—44.95（wt%）之间,Na20＞K₂O,Na₂O/K₂O在2.56—5.26之间,属典型钠质型碱性岩类;MgO含量5.32—6.74%,TiO₂为3.82—5.84%,Al₂O₃为13.27—15.06%;m/f比值为0.37—0.56,属富铁质系列。Pearce（1977）的FeO—MgO—Al₂O₃图解,落入大陆板内。稀土元素总量较高,∑REE为157.60—336.63×10^-6,呈显著轻稀土富集特点,（La/Yb）N=10.13—18.88,δEu为1.51—2.13,铕呈轻微正异常。矿石矿物钛磁铁矿TiO₂含量0.415—23.69%,FeO含量69.7—96.18%,Cr₂O₃含量0.062—0.761%。上述特征表明研究区钛磁铁矿是扬子陆块北缘早古生代幔源低程度部分熔融产物上侵分凝成矿作用结果。5.平利地区南北长80余公里,东西宽20余公里,约1700km²范围内,运用综合分析方法,对岩浆分异型钛磁铁矿、MVT型铜铅锌矿和沉积改造型钒钼矿找矿远景进行预测。钛磁铁矿以碱性辉长岩类矿化,特别是辉石岩的产出为有利找矿标志,有明显磁异常和Ti元素地球化学异常,在研究区共圈出3个找矿远景区,以花桥远景区最具找矿前景;MVT型铜铅锌矿,主要找矿标志为震旦纪白云质灰岩及后期构造裂隙发育为典型特征,Cu、Pb、Zn元素地球化学异常为重要找矿指示,在研究区圈出6个找矿远景区,其中以罗家院子远景区最具找矿潜力。更多还原

【Abstract】 On the basis of 4 one to fifty thousand of mineralization and prospective survey in Pingli area in South Qinling,the author collected and researched many datas of the the former geological workers in the area,and then through investigating field routes and ore occurrences and testing on important samples,especially researched the characters of regional geology,mineralization,important mineralization types in Pingli area.And quest for the important mineralization types which representative of Huaqiao titanomagnetite occurrence in the research area,then analyse and predicate the ore deposit of the major mineralization types in Pingli area.The major inclusion and advances as follows.1.The Pingli area is located in the region of the joints of Yangtze block and Qinling orogenic belt.The outcrops are mainly fundus of Yangping Group of Middle Algonkian, which is composed of sericite chlorite-schist and sericite albite-schist.The roof rock consist of metamorphic lava of Nanhuaan System,Doushantuo Group carbonaceous-siliceous rocks and Dengying Group dolomitic-limestone of Sinian Period,and a set of siliceous rocks, limestone and carbonaceous slate in deoxidize environment on the edge of passive continental margin in Early Paleozoic.And the strata were lost began from Devonian.The magmatism were faint and the magmatic rock are exiguous exposed in the Pingli area,and mainly developed two times of magma events of basic lava of Nanhuaan System and alkaline-gabbro of Ordovician,The basic lava of Nanhuaan System represents the corresponding to the breakup of the Rodinia super-continent in Qinling,and the alkaline gabbro of Ordovician represents the intracontinental tectonic- magmatism in Early Paleozoic.2.The mineralization is faint in the whole Pingli area,and only found some mineralization occurrences which were inadequate exploration in this area.The main mineralization types of them are Magmatic Differentiation-type of titanomagnetite occurrence related to the alkaline-gabbro of Ordovician,the MVT-type of Cu-Pb-Zn mineralization produced in the Dengying Group dolomitic-limestone of Sinian Period and the Sedimentary Reformation-type of V-Mo mineralization mainly distributed in the Lujiaping Group carbonaceous-siliceous rocks of Cambrian et al.The titanomagnetite occurrence has the long-range view in these mineralization types and it has found the Luojiayuanzi Cu-Pb-Zn ore occurrence,which has the long-term view of becoming small-middle sized deposit.According to the regional mineralization analysis,the Cu-Pb-Zn mineralization occurs in the Dengying Group limestone is found in the same strata horizon to the MVT-type of Cu-Pb-Zn mineralization in the edge of Yangtze block,it maybe the behaviour of MVT-type of Cu-Pb-Zn mineralization in Pingli area.But the Luojiayuanzi is characterd by low-grade of Pb/Zn（0.01—1.68%）,high-grade of Cu（2.56—17.25%）,it is different to the ore of MVT-type mineralization.It hasn’t found economic value of V-Mo mineralization in the Cambrian system,it is probably because of the inadequate enrichment of mineralization elements.3.Huaqiao titanomagnetite occurrence,as has the economic value of the metal mineralization type related to the alkaline-gabbro in the region,the author made embedded study on it.The visible ore-body of Huaqiao titanomagnetite occurrence is about 250m long and 8—10m wide,and the area is about 2500m².It was lens shape,and the ore type are mainly pyroxenite and gabbro et al.The ore-bearing lithofacies is biotite- pyroxenite.The rock mainly consists of titaniferous-pyroxene,the others is biotite.In the rock the titaniferous-pyroxene is automorphic-hypautomorphic,and there is a little of apatite and sphene in it.The chloritization and carbonatization are distinct in the rock.The titanomagnetite occurrence is occured in the middle part of the pyroxenite body,and is gradual changed of no obvious borderline between the ore body and the country rocks.The ore is mainly of dense-disseminated and consists of titanomagnetite,mohsite,magnetite and little pyrite.4.The petrogeochemistry of Whole alkali-Silicon schema of Huaqiao titanomagnetite occurrence reveals it is in the alkaline-gabbro range,but it has lower content of SiO₂ than the common gabbro,the SiO₂ is 42.82—44.95（wt%） of the now get samples.The Na₂O＞K₂O, （Na₂O/K₂O = 2.56—5.26）,so that it is typical natrium-type alkali rock.MgO = 5.32—6.74%,TIO₂ = 3.82—5.84%,Al₂O₃ = 13.27—15.06%.The value of m/f= 0.37—0.56,then it is belongs to Fe-rich rock series.The FeO—MgO—Al₂O₃ schema（Pearce,1977） of the samples’ data revels it is within the continent.The∑REE = 157.60—336.63×10^-6,shows the LREE-rich character.（La/Yb）_N =10.13—18.88.δEu =1.51—2.13,display a faint positive anomaly trend of Eu.The TIO₂=0.415—23.69%,FeO = 69.7—96.18%,Cr₂O₃ = 0.062—0.761%of the titanomagnetite.All the characters above show that the titanomagnetite occurrence is the result of magmatic segregation when the low-degree of partly fusing outcome of mantle origin in the north edge of the Yangtze block in the early Paleozoic.5.The investigation area of this paper is about 80 km long and 20 km wide,the area is about 1700km².Through the integrate analysis,the author predicate the prospective ore deposit to the Magmatic Differentiation-type of titanomagnetite mineralization,the MVT-type of Cu-Pb-Zn mineralization and the Sedimentary Reformation-type of V-Mo mineralization.It suggest in this paper that the mineralization of alkaline-gabbro,spatially the emergence of pyroene is the effective symbol indicating the titanomagnetite mineralization,and there are distinct magnetic and Ti petrogeochemistry abnormity,and predict 3 prospective zones,the Huaqiao zone is the best one.The major orefinding symbols of MVT-type of Cu-Pb-Zn mineralization are dolomitic-limestone of Sinian Period and development of Later tectonic break,and the Cu/Pb/Zn petrogeochemistry abnormity are important oresearch indicator,and predict 6 prospective zones,the Luojiayuanzi zone is the best one.更多还原