【作者】 郝金华；

【导师】 陈建平；

【作者基本信息】 中国地质大学（北京） ， 矿产普查与勘探， 2011， 博士

【摘要】 近年来在青海南部开展的地质调查和研究工作揭示出三江北段成矿带具有形成大型、特大型金属矿床的赋存条件及地质背景,通过深入研究有望取得继三江中段之后的找矿重大突破。本文在系统收集前人研究成果基础上,通过对典型矿床（纳日贡玛、陆日格）开展野外地质调查和室内测试分析工作,基于成矿地质特征、岩石及矿床地球化学特征、同位素年代学等,对纳日贡玛、陆日格开展成矿地质背景、主要控矿因素、矿化规律、成矿模式等方面进行探讨,并与三江成矿带其它矿床进行对比。取得了如下研究成果和认识:1、通过野外地质填图、钻孔编录和室内分析测试工作,详细地对陆日格、纳日贡玛斑岩型矿床的矿化类型、矿化特征、矿化元素及矿石学特征开展了大量基础性工作。确定了与青海三江北段Mo-Cu成矿作用有关的斑岩主要为黑云母花岗斑岩和浅色石英花岗斑岩,三江北段斑岩矿化以细脉浸染状、网脉状矿化为主;其矿化类型相对单一,主要为Mo、Cu矿化,伴生丰富的Bi、Te矿化,为进一步的找矿和勘探工作奠定了基础,明确了方向。2、对陆日格、纳日贡玛矿床开展了斑岩锆石U-Pb同位素定年、辉钼矿Re-Os同位素定年工作。纳日贡玛含矿斑岩锆石LA ICP-MS U-Pb同位素测试结果为42.9 Ma～43.4Ma,陆日格矿床岩浆侵入年龄为61.7 Ma～62.1Ma;辉钼矿Re-Os同位素定年结果为纳日贡玛为40.5±0.87Ma,陆日格为60.7±1.5Ma。从而认为,纳日贡玛和陆日格为各自独立的两个岩浆-热液成矿过程。提出新生代以来青海三江段斑岩型矿床存在两次较大规模的岩浆成矿作用事件。3、系统地对陆日格、纳日贡玛矿矿床开展了岩石学研究工作,并与三江成矿带其它矿床进行了对比。研究表明纳日贡玛、陆日格斑岩岩性主要为黑云母花岗斑岩、石英花岗斑岩及花岗闪长斑岩。岩石具有高SiO₂、富K₂O及Na₂O,wt（K₂O）>w（Na₂O）,与邻近的玉龙矿带相似,斑岩主要为高钾钙碱性-钾玄岩系列。含矿斑岩稀土元素总量较高,稀土分配模式为轻稀土富集的右倾型,弱或无负Eu异常。微量元素表现为大离子亲石元素（LILE）富集、高场强（HFSE）亏损,具显著的Ti、Nb和Sr谷;具有部分埃达克岩的地球化学属性。4、对陆日格、纳日贡玛含矿斑岩进行Sr-Nd-Pb同位素测试分析工作。三江北段斑岩钼铜矿带含矿斑岩的²⁰⁶Pb/²⁰⁴Pb值为18.4100～19.4290,²⁰⁷Pb/²⁰⁴Pb值为15.6090～15.6850,²⁰⁸Pb/²⁰⁴Pb值为38.5770～39.5228。含矿斑岩的(⁸⁷Sr/⁸⁶Sr)_t为0.702873～0.705859,(¹⁴³Nd/¹⁴⁴Nd)_t为0.512573～0.513204,ε_Nd（t）基本处于0.30～0.64,接近玉龙矿带的0.8～1.0Ga。青海三江段岩石Sr-Nd-Pb同位素非常接近EMll地幔端元,表明侵入岩主要来自交代富集地幔。5、对纳日贡玛、陆日格开展了S、C-H-O同位素、包裹体等矿床地球化学研究,研究表明纳日贡玛硫化物δ³⁴S为4.0‰～7.1‰,陆日格矿石矿物δ³⁴S为-2.60‰～5.8‰。石英金属矿化物脉中H-O测试结果表明,成矿流体与石英达到平衡时,纳日贡玛成矿流体δ¹⁸O_H2O为0.6‰～3.0‰,陆日格δ¹⁸O_H2O为-0.76‰～3.54‰。随着深度的加强大,δ¹⁸O_H2O逐渐变大和δD变小,成矿流体更偏向于岩浆水。成矿后期流体中的δ¹3C的分布范围,也与岩浆/地幔源的δ¹3C近似。因此,青海南部三江段斑岩矿床为成矿金属物质来源于岩浆,成矿流体为岩浆期后热液。6、在综合研究基础上,提出了斑岩型矿床的成矿模型及找矿标志。并对区域青海南部三江段斑岩成矿规律进行了总结,认为青海南部三江成矿带的走滑断裂构造活动引起了区域内两期较大规模的成矿（分别以陆日格、纳日贡玛为代表）。对区域的找矿工作提出了建设性的意见和建议。更多还原

【Abstract】 Recent studies on the Northern Sangjiang ore belt ,Southern Qinghai,reveal that the ore belt have excellent metallogenic conditions and geological background to form the Large, extra large metal deposits and expect to have breakthrough in prospecting after intensive work.By detailed field geological work and systemic modern analysis work ,this dessertation studies the geological Characteristics ,petrology,geochemistry and geochronology of the ore-bearing porphyries,such as Narigong and Lurige deposits.to research the dynamical backgroud,mineralization features and deposit model in Northern Sangjing ore belt and compare orther porphyies deposits in Sangjiang belt.The main conclusions were drawn as follows:The Northern Sangjiang ore belt’s ore-bearing porphyries include Biotite monzogranite porphyry and Light-colored quartz monzonite porphyry.Ore stone show Veinlets- disseminated structure and mesh-vein texture.Mineralization is mainly Mo-Cu,and associted Bi,Te.This paper carries out the porphyry zircon LA ICP-MS U-Pb isotope dating method and Molybdenite Re-Os isotope dating method, the first time for Lurige and detailed measurements for Narigongma .The rock-forming ages of Lurige range from 61.7Ma to 62.1Ma, and Narigongma deposit range from 42.9Ma to 43.4Ma.The Molybdeum mineralization age at Lugrge is 60.7±1.5Ma,and Narigongma is 40.5±0.8Ma.So Narigongma and Lurige porphyry deposits are two separate magmatic-hydrothermal ore forming process,and the span age of mineralization age and rock-forming age is about 2-3Ma. Therefore,since Cenozoic the Sanjiang porphyry deposits have two large-scale presence of magmatic mineralization events.The element geochemical features in Northern SanJiang belt show adakite magmatic affinity ,similar to Yulong ore belt.The ore porphyries rocks are high SiO₂,k₂O and high k₂O/Na₂O ratio and mainly high-K calc-alkaline porphyry-shoshonitic series.The rocks are all enriched in large-ion lithophile elements（eg.K,Rb,Sr,Ba,Th,La）and light rare earthelements,depleted in high field-strength elements and heavy rare earth elements.The ²⁰⁶Pb/²⁰⁴Pb,²⁰⁷Pb/²⁰⁴Pb,²⁰⁸Pb/²⁰⁴Pb values of Northern Sanjiang ore-bearing porphyries range from 18.4100～19.4290,15.6090～15.6850,38.5770～39.5228.The (⁸⁷Sr/⁸⁶Sr)_t,(¹⁴³Nd/¹⁴⁴Nd)_t values range from 0.702873～0.705859, 0.512573～0.513204, and the values ofεNd（t）is 0.30～0.64 Roughly.The Sr-Nd-Pb isotope of Northern Sanjiang ore belt,Southern Qinghai,were very close to Emll,so the intrusive rocks maybe come from the account of enriched mantle.Theδ³⁴S value of Narigongma’sulfide was 4.0‰⁷.1‰and Lurige was -2.60‰⁵.8‰.Narigongmaδ¹⁸O values of the Forming fluid which Ore-forming fluids and quartz Reach equilibrium was 0.6‰～3.0‰,and Lurige was -0.76‰～3.54‰.As the depth increased,δ¹⁸O become larger andδD become smaller.Theδ¹³C values of the dolomite are smilier with magma/mantle source.So the Ore-forming metals of Northern Sanjiang belt comes from magma and the ore-forming fluid comes from magmatic hydrothermal fluids.Based on the comprehensive study,the thesis propose porphyries mineralization model and prospecting indications and summarize the metallogenic regularity .The two large-scale regional porphyries mineralization was coused by the conversion of Strike-slip fault tectonic stress in Northern Sanjiang belt ,Southern Qinghai.更多还原