【作者】 曹圣华；

【导师】 陈毓川； 王登红；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 西藏冈底斯中部地区是青藏高原冈底斯成矿带的重要组成部分，地质工作程度明显低于冈底斯东南段。本次通过实施中央地勘基金普查项目和其它矿调项目，在措勤县尼雄矿田滚纠矿区内重新圏定了3条铁矿体，主矿体Fe1走向长度大于1千米，厚度7.49～72.76米，mFe品位35.56％～49.33%，估算333+334富铁矿石资源量5100多万吨；并在尼雄矿田及其周边新发现了一批具有中型以上资源潜力的铁、铜多金属矿床(点)，进一步找矿的潜力巨大，可能是国家级铁、铜矿接替资源基地的理想地区。本文取得的成果与认识归纳如下：1、通过典型矿床研究，查明了尼雄滚纠矽卡岩型铁矿区矿体规模、形态、产状及空间分布特征；将矿化蚀变分为岩体内蚀变带、内矽卡岩与磁铁矿带、外矽卡岩带、大理岩化带和黄铁矿化-角岩化带等五个带；认为滚纠铁矿床的矿化蚀变特征、蚀变类型与我国典型的矽卡岩型铁矿床不同(如大冶式)，明显缺少钠长石化；并对矽卡岩矿物学特征、矿床地球化学特征进行了初步研究。2、对与滚纠铁矿形成有关的花岗闪长岩和二长花岗岩进行了精确的SHRIMP锆石U-Pb测年，获得年龄分别为119.90±1.9Ma和116.9±1.7Ma，结合矿床成因综合分析，认为成岩与成矿作用是同一地质作用过程，成矿时代为燕山晚期早白垩世。3、初步建立了西藏冈底斯成矿带“尼雄式”矽卡岩型铁矿床的成矿模式、矿床模型和冈底斯中部区域成矿模式；归纳总结了各类地质、地球物理等找矿标志，可进一步指导本区地质找矿工作。4、对冈底斯中部区域成矿规律进行了较系统的总结，首次划分了5条Ⅳ级成矿亚带和22个Ⅴ级成矿远景区；指出冈底斯中段位于研究程度高的南冈底斯成矿带与藏北班公湖－怒江构造成矿带之间，在成矿规律研究方面起到衔接作用，意义重大。但本区勘查及科研工作程度低，故本文的初步研究成果将填补冈底斯中部区域成矿规律研究方面空白区。5、总结了冈底斯中部地区5条矿带和6处主要成矿远景区的成矿特征，评述了冈底斯成矿带中段的铁铜矿资源潜力；划分的成矿远景区为下一步中央地质勘查基金项目的立项工作指明了方向。6、运用成矿系列理论，根据近期矿调工作中新发现的矿床(点)特征、各类矿化信息的时间、空间分布规律，在冈底斯中部初步划分了2个矿床成矿系列、6个成矿亚系列。其中，首次厘定了与燕山早期中酸性侵入岩有关的铁矿床成矿亚系列，为在西藏冈底斯中部寻找比尼雄式铁矿形成时代更老的矿床指明了找矿新方向；与喜山期斑岩有关的铜多金属矿床成矿亚系列的初步划分，证明南冈底斯斑岩型铜矿带可能由东向西延伸，并有可能由南向北伸入冈底斯中部，拓展了斑岩型铜矿的找矿空间。更多还原

【Abstract】 The middle Grandise in Tibet is the important component of the Gangdese metallogenicbelt in the Qinghai-Tibet Platean, which was studied geologically in obviously lower degreethan the southeastern Gangdese. This time, three new iron-ore bodies have been confined inthe Gunjiu mine of the Nixong iron ore field in the Cuoqin County through carrying out thegeneral survey projects from the Middle Fund of Geological Survey and other mineralprospecting projects. The Fel main iron-ore body has a length of over 1000m, thicknessesfrom 7.49m to 72.76m, tenors of 35.56%-49.33% mFe in its iron ore and an estimation ofmore than 51 million tons of 333+334 rich iron-ore resource. Moreover, a series of Fe, Cupolymetallic deposits (ore occurrences) with medium-sized and greater scales potentialshave been found in the Nixong ore field and around it, in which there are great prospectingpotentials and which is also regarded as the ideal area serving as the national base ofsuperseding iron and copper resourcesThe main results and knowledge are summarized as follows:1.By studying the representative deposit, the wallrock alternation in the Gunjiuskarn-type iron deposit in Nixong is divided into five zones as the alternation zone inside theintrusive body, the inner skarn-magnetite zone, the outer skarn zone, the marmorizationzone and the pyritization-hornfels zone. As there is distinctly short of albitization in theGunjiu iron deposit, it is considered that its mineralization and alternation characteristics aredifferent from that in the representative skarn-type iron deposits (as Day-type iron deposits) inChina. Furthermore, the mineralogical features of the skarn and the geochemical features ofthe deposit were preliminarily studied.2.The precise SHRIMP U-Pb Zircon Dating of the granodiorite and admellite involvedin the Gunjiu iron deposit forming resulted in respectively an age of 119.90±1.9Ma and anage of 116.9±1.7Ma. Combined with the comprehensive analysis of the deposit genesis, it isbelieved that its mineralization and diagenesis are the same geological process and itsmetallogenetic epoch is Early Cretaceous Epoch.3.The author preliminarily established the metallogenic model and deposit model of theNixong-type skarn iron deposit in the Gangdese metallogenic belt and the regionalmetallogenic model in the middle Gangdese, Tibet. The author also summarized variousprospecting indications in geology and geophysics, which can be used in indicating furthergeological prospecting.4.The article systemically summed up the regional metallogenic regularity in the middleGangdese, which is redivided into fiveⅣ-level metallogenic subzones and twenty-twoⅤ-level prospects. It was pointed out that the middle Gangdese is situated between the southGangdese metallogenic belt and the Bangong Co-Nujiang tectonic- metallogenic belt studiedin higher degree and so it is a join and of great significance in studying the metallogenicregularity. However, this area was surveyed in extremely low degree, so the articlepreliminarily filled up the blank in the research of the regional metallogenic rules in the middle Gangdese.5.The article described the mineralization characteristics of five metallogenic zones andsix main prospects in the middle Gangdese and estimated the potential of iron and copperresources in the middle part of the Gangdese metallogenic belt. The proposed prospects showclearly the direction for the future project approval and survey of the Middle Fund ofGeological Survey.6.On the bases of the features of deposits (ore occurrences) found newly and thespace-time distribution of various types of mineralization in the middle Gangdese, twometallogenic series and six metallogenic sub-series have been preliminarily distinguished.Among them was firstly defined the metallogenic sub-series of iron deposit involved in theintermediate-acid intrusive rock of Early Yanshan Period, pointing out the new direction toprospect older deposits than the Nixong iron deposit in the the middle Gangdese, Tibet. Thepreliminarily definition of the metallogenic series of copper polymetallic deposit associatedwith porphyry of Himalayan period proves that the porphyry-type copper ore belt in thesouthern Gangdese probably extends from east to west, and likely stretches into the middleGangdese, expanding the area for prospecting porphyry-type copper deposits.更多还原