桂东北苗儿山—越城岭矿集区成岩成矿演化分析

发布时间：2018-06-25 17:58

  本文选题：苗儿山—越城岭 + 界牌　； 参考：《中国科学院研究生院(广州地球化学研究所)》2016年博士论文

【摘要】：苗儿山—越城岭复式岩体位于南岭西段,由多期多阶段岩浆活动形成的侵入岩组成,过去多认为复式岩体主体为加里东期花岗岩,印支期花岗岩也分布较为广泛,且零星出露燕山期小岩株,但缺少精确的同位素定年。在苗儿山—越城岭复式岩体与围岩的接触带中,形成众多大大小小的矿床及矿点,围绕复式岩体形成矿集区,较著名矿床主要有牛塘界W矿床、界牌W-Cu矿床、长岗岭Pb-Zn多金属矿床及云头界W-Mo矿床等。近年来,研究人员对苗儿山—越城岭复式岩体时空分布、地球化学特征、来源及矿床的形成年龄等方面进行了研究,并获得了不少成果。但对于区内矿床形成演化过程、成矿岩体地球化学特征、成矿与非成矿岩体差异等研究工作相对较少。苗儿山—越城岭矿集区发育不同成矿元素组合的矿床,由于缺少典型矿床成岩成矿过程剖析,矿化与赋矿岩体关系不清,因而对形成不同成矿元素组合矿床的主要控制因素了解不多。综上所述,苗儿山—越城岭矿集区仍主要存在以下问题:(1)苗儿山—越城岭区域系统的成岩成矿时空分布如何?成矿作用主要发生于加里东期、印支期还是燕山期?(2)相关矿床成矿岩体有何地球化学特征及其成矿流体的演化过程?(3)形成矿集区内不同成矿元素组合矿床的主要控制因素是什么?针对上述问题,本次工作以界牌W-Cu、牛塘界W和舜皇山W矿床等为研究对象。开展如下工作:(1)通过野外地质调查及资料的全面收集、矿化蚀变特征及矿化期次等观察分析,厘清矿化相关的侵入岩的关系,初步厘定相关成矿岩体;(2)测定成矿期白云母Ar-Ar同位素年龄及赋矿岩体和矿区周边相关侵入岩的LA-ICP-MS锆石U-Pb年龄,了解岩体时空结构及确定成岩成矿演化系列;(3)测定矿区内外的主要类型岩石的主微量元素和Sr-Nd-Hf同位素组成,分析成矿岩体及相关侵入岩的地球化学特征及源区特征,深入探讨不同成矿元素组合矿床成矿岩体源区差异;(4)分析不同类型矿床成矿流体特征及演化,结合蚀变特征,揭示不同类型成矿元素沉淀析出主要控制因素。本工作主要取得了下列成果:(1)苗儿山—越城岭一带与矿化相关岩体主要形成于加里东期及印支期,矿集区内主要矿床与加里东期和印支期岩浆活动有关,而不是过去认为的燕山期。苗儿山—越城岭矿集区界牌、牛塘界、舜皇山等3个矿区主要赋矿岩体及咸水乡闪长岩和五星村浅色岩体LA-ICP-MS锆石U-Pb年龄表明,舜皇山W矿区的两期花岗岩侵入年龄分别为219.6±2.4Ma和220.3±3.6Ma;界牌矿区两期早期岩基和晚期岩脉的年龄分别为422±11Ma、428.3±6.5Ma和410±7.4Ma;咸水乡闪长岩的年龄为431.4±3.8Ma;五星村浅色岩体的年龄为412±14Ma;牛塘界矿区外围两期岩基的年龄分别为430±4.9ma和432.2±8.4ma。除舜皇山矿区的两期花岗岩形成于印支期外,其余矿区相关侵入岩的形成时代均为加里东期。界牌w-cu矿产于斑状黑云母花岗闪长岩和灰岩接触带矽卡岩中及从岩体至围岩显示从中高温蚀变矿物组合至中低温蚀变矿物组合等表明矿化与斑状黑云母花岗闪长岩有关,矿床形成于加里东期,约为422±11ma;舜皇山w矿主要为脉状产于印支期花岗岩中,赋矿岩体发生广泛的云英岩化,表明w矿与赋矿岩体具有内在成因关系,成矿主要发生在印支期,约为220ma。前人成果表明,苗儿山—越城岭矿集区牛塘界w矿是加里东期形成的,云头界w-mo矿和高岭w矿床是印支期形成的。因此,苗儿山—越城岭矿集区内的w-mo、w、w-cu等矿床主要形成于加里东期和印支期。(2)苗儿山—越城岭复式岩体主要为过铝质花岗岩,具有壳源花岗岩的地球化学特征,主要是中晚元古代基底地壳部分熔融形成的。苗儿山—越城岭复式岩体主体为酸性岩,发育有少量中性岩。其主量元素都表现为高si、富k、贫mg的特征,属钙碱性-高钾钙碱性系列,且全部样品为过铝质花岗岩,微量元素明显富集rb、th、u及亏损sr、ba、ti,稀土元素呈明显的eu负异常,总体显示壳源花岗岩的特征。且界牌、牛塘界矿区晚期浅色岩体都呈现稀土总量偏低,稀土配分模式呈“海鸥状”等特征,与南岭其他地区燕山期w-sn成矿岩体地球化学特征相似。舜皇山钨矿花岗岩具有低εnd(t)(-9.33~-10.58)值和低εhf(t)(-5.9~-10.5)值,对应的nd、hf二次模式年龄分别为1907~2760ma和1626~1918ma,与牛塘界w、云头界w-mo矿成矿岩体的同位素特征相似,由古地壳重熔形成;界牌矿区钨铜矿化有关岩体的εnd(t)(-5.91~-7.92)值和εhf(t)(-4.4~-10.7)值呈较大负值,nd和hf二次模式年龄分别为1621~1963ma及1690~2088ma,总体具有壳源的特征,但其εnd(t)值相对较高,且其εhf(t)值比较分散,表明其源区和舜皇山钨矿化岩体有一定差异,可能含有一些地幔或新生地壳物质。(3)成矿岩体来源是控制区内矿床形成不同成矿元素组合的重要因素。界牌w-cu矿床和舜皇山w矿床、牛塘界w矿床和云头界w-mo矿床成矿岩体地球化学化特征有一定的差异,前者相对低硅高铁镁钙及具较高的εnd(t)值,后者高硅,具高演化花岗岩特征及相对更低的εnd(t)值。这表明苗儿山—越城岭矿集区高演化花岗岩有利于w和w-mo矿床的形成,而cu-w矿化则和非高演化花岗岩具亲缘性。w和w-mo成矿花岗岩主要为古老基底部分熔融形成的,而w-cu矿化花岗岩源区可能含有少量地幔(新生地壳物质)。岩浆源区及成岩过程中演化程度差异可能是形成不同成矿元素组合矿床的主要控制因素。(4)界牌矽卡岩型w-cu矿成矿流体主要为中高温、低盐度NaCl-H2O-CO_2-CH4热液体系,流体混合为其成矿元素沉淀的主要机制;舜皇山W矿成矿流体主要为中低温、低盐度NaCl-H2O-CO_2-CH4热液体系,流体冷却降温为其成矿元素沉淀的主要因素,流体不混溶也可能是因素之一。我们分析了界牌矽卡岩W-Cu矿床伟晶岩、白钨矿石和晚期石英脉三个不同成矿阶段的流体特征。伟晶岩石英中的流体包裹体均一温度峰值为310~330°C,盐度为0.18~5.71%NaCleqv,拉曼光谱显示气体中具有CO_2和CH4的成分,属于中高温、低盐度NaCl-H2O-CO_2-CH4热液体系;白钨矿石中流体包裹体均一温度具有两个峰值,分别为260~280°C和320~340°C,盐度为0.35%~5.56%NaCleqv,属中高温、低盐度热液范畴;晚期石英脉均一温度峰值为270~300°C,盐度为0.18~3.71%NaCleqv,气体中亦含有CO_2和CH4的成分,属中温、低盐度范畴。界牌W-Cu矿白钨矿矿石中的流体均一温度和盐度具有明显正相关的线性关系,说明其经历了流体混合作用,促使成矿元素沉淀。观察分析了舜皇山矿区成矿花岗岩、云英岩和晚期石英脉三个阶段的流体包裹体特征。岩体阶段石英中未见熔融包裹体,测试对象主要为流体包裹体,其均一温度峰值为210~240°C,盐度为0.18~3.55%NaCleqv,与云英岩阶段流体包裹体均一温度、盐度特征相似,推测其受云英岩阶段热液改造形成,同时在云英岩石英包裹体气体中发现CO_2和CH4,因此两个阶段同属中温、低盐度NaCl-H2O-CO_2-CH4热液体系;晚期石英脉均一温度峰值为190~220°C,盐度为0.18~3.71%NaCleqv,其气体成分中也含有CO_2和CH4,属中低温、低盐度NaCl-H2O-CO_2-CH4热液体系。而舜皇山W矿床主成矿阶段云英岩中的流体包裹体温度跨度较大,但盐度处于一个较小的范围,说明其经历了流体冷却降温过程,造成成矿元素沉淀,同时见少量富气相与富液相两类包裹体共生,且富气相包裹体均一温度较高,说明其经历了流体不混溶,这也可能是造成成矿元素沉淀的因素之一。
[Abstract]:The Miao mountain - Yuecheng ridge complex is located in the western section of Nanling, which is composed of intrusive rocks formed by multi stage and multi stage magmatic activities. In the past, the main body of complex rock mass was CALEDONIAN GRANITE, and the Indosinian granites were also widely distributed, and the small rocks were scattered in Yanshan period, but the exact isotope dating was scarce. In the contact zone of complex rock mass and surrounding rock, many large and small ore deposits and ore spots are formed, and the ore deposits are formed around complex rock mass. The famous ore deposits are mainly Niu Tong W deposit, Jie brand W-Cu deposit, Chang Gang Ling Pb-Zn polymetallic deposit and cloud head W-Mo deposit. In recent years, the researchers have made the spatial and temporal distribution of the compound rock mass in Miao mountain - Yuecheng ridge. The geochemical characteristics, sources and the age of the formation of the deposit have been studied, and many achievements have been obtained. However, there are relatively few research work on the formation and evolution process of the deposits in the area, the geochemical characteristics of the ore-forming rock mass and the difference of metallogenic and non metallogenic rocks. Due to the lack of analysis of typical ore forming and metallogenic processes, the relationship between mineralization and ore bearing rock mass is not clear, so the main control factors for the formation of different metallogenic elements are not well understood. In summary, the following problems still exist in the Miao Er mount Yuecheng Ling ore collection area: (1) the spatial and temporal distribution of the diagenesis and mineralization of the Miao Er mountain Yuecheng ridge regional system, for example What is the mineralization mainly occurring in Caledonian, Indosinian or Yanshan period? (2) what are geochemical characteristics and evolution process of ore-forming fluids in the related ore deposits? (3) what are the main controlling factors for the formation of different ore-forming elements in the ore-forming area? For the above problems, this work is based on the W-Cu, Niutang boundary W and shun. The Huangshan W deposit is the research object. (1) through the comprehensive collection of field geological survey and data, the characteristics of mineralized alteration and the secondary observation and analysis of mineralization period, the relation of mineralization related intrusive rocks is clarified, and the Related Ore-forming rock mass is preliminarily identified; (2) the age of the Muscovite isotopes in the Ce Dingcheng period, the ore bearing rock mass and the mining area The LA-ICP-MS zircon U-Pb age of the associated intrusive rocks, to understand the spatial and temporal structure of rock mass and to determine the series of diagenetic and metallogenic evolution; (3) to determine the main trace elements and Sr-Nd-Hf isotopes of the main types of rock in the mining area and to analyze the geochemical and source characteristics of the ore-forming and related intrusive rocks, and to explore the different metallogenic elements in depth. The differences in the source area of the ore-forming rock mass of the ore deposit are found. (4) to analyze the characteristics and evolution of the ore-forming fluids of different types of ore deposits and to reveal the main controlling factors for the precipitation and precipitation of different types of metallogenic elements. The main results are as follows: (1) the mineralization related rocks in the Miao mountain and Yuexing area are mainly formed in Caledonian and Indosinian periods. The main ore deposits in the ore gathering area are related to the Caledonian and Indosinian magmatic activities, but not the Yanshan period in the past. The main ore bearing rocks in the 3 mining areas of the Miao and Yuecheng ridge, the Niu Tang and Shun Huangshan, and the LA-ICP-MS zircalo U-Pb age of the salt water and the Wuxing village light color rock show that the two phases of the granite in the W mining area of Shun Huangshan The age of rock intrusion is 219.6 + 2.4Ma and 220.3 + 3.6Ma, respectively, the age of the early rock base and late vein in the two phases of the Jie brand mining area is 422 + 11Ma, 428.3 + 6.5Ma and 410 + 7.4Ma, the age of the diorite in salty water Township is 431.4 + 3.8Ma, the age of the five star village light color rock mass is 412 + 14Ma, and the age of the two phases of the periphery of the Niu Tang mining area is 430 + 4.9ma, respectively. The two phases of granite, except Shun Huangshan mining area, formed in the Indosinian period, and the formation times of the related intrusive rocks in the other mining areas are all Caledonian. The W-Cu mineral is in the porphyritic mica granodiorite and limestone contact belt skarn, and from the rock mass to the surrounding rock, the mineral assemblage from the middle and high temperature alteration mineral to the medium and low temperature alteration mineral group is shown from the rock mass to the surrounding rock. The mineralization is related to the porphyritic biotite granodiorite. The deposit is formed in Caledonian period, which is about 422 + 11ma, and the w mine of Shun Huangshan is mainly produced in the Indo branch granite, and the ore bearing rock mass has a wide range of cloud and rock formation. It indicates that the w ore and the ore bearing rock have an inherent genetic relationship, and the mineralization occurs mainly in the Indosinian period, which is about 220ma. predecessors. The results show that the w ore of the niintang boundary in the Miao mountain - Yuecheng Ling ore area is formed in Caledonian period, and the W-Mo ore and the kaolin w deposit of the cloud head boundary are formed in the Indosinian period. Therefore, the W-Mo, W and W-Cu deposits in the Miao mountain - Yuecheng Ling ore gathering area are mainly formed in Caledonian and Indo Chinese periods. (2) the Miao and Yuecheng ridge complex rock mass is mainly peraluminous granite. The geochemical characteristics of the rock, with the crust source granite, are mainly formed by partial melting of the basement crust of the middle and late Proterozoic. The main body of the Miao mountain - Yucheng ridge complex body is acid rock and a small amount of neutral rocks. Its main elements are characterized by high Si, K rich and poor mg, which belong to the calc alkaline high potassium calc alkaline series, and all the samples are peraluminous Granite, trace elements obviously enrich Rb, th, u and loss Sr, Ba, Ti, and the rare earth elements show obvious negative Eu anomaly, which generally shows the characteristics of the crust source granite. Moreover, the late light color rocks in the Niu Tang mining area show the low rare-earth total amount, and the REE distribution pattern is characterized by "Seagull like", and the Yanshan stage W-Sn metallogenic rock mass in other areas of Nanling. The chemical characteristics of the ball are similar. The Huangshan tungsten granite has low Nd (T) (-9.33~-10.58) value and low epsilon HF (T) (-5.9~-10.5) value. The corresponding nd, HF two mode age is 1907~2760ma and 1626~1918ma respectively. It is similar to the isotopic characteristics of the Niu Tang W and cloud head W-Mo ore ore-forming rock, which is formed by the remelting of the paleo crust and the tungsten copper mineralization in the Jie brand mining area. The values of the epsilon Nd (T) (-5.91~-7.92) and the HF (T) (-4.4~-10.7) of the rock mass are negative. The age of the two modes of Nd and HF are 1621~1963ma and 1690~2088ma, respectively, which have the characteristics of the shell source, but the values of the epsilon Nd (T) are relatively high and the values are relatively dispersed, indicating that there are some differences between the source area and the tungsten mineralized rock mass of Shun Huangshan, which may contain some ground. Mantle or new crust material. (3) the source of ore-forming rock mass is an important factor in the formation of different metallogenic elements in the controlled area. The geochemical characteristics of the W-Cu deposit and the Shun Huangshan w deposit, the Niu Tang boundary w deposit and the cloud head W-Mo ore deposit are different, the former is relatively low silicon, high iron, magnesium, calcium and high Nd (T) value. High silicon, characterized by high evolution granites and relatively lower Nd (T) values. This indicates that the high evolutionary granite in the Miao mountain and Yucheng ridge ore area is beneficial to the formation of W and W-Mo deposits, while the Cu-W mineralized and non highly evolving granite and the.W and W-Mo granites are mainly formed by the melting of the ancient basement and the W-Cu mineralized granites. The source area may contain a small amount of mantle (new crust material). The difference in the evolution degree of the magmatic source area and diagenesis may be the main controlling factor for the formation of different metallogenic element combination deposits. (4) the ore-forming fluid of Sijie skarn type W-Cu ore is mainly medium high temperature, low salinity NaCl-H2O-CO_2-CH4 hydrothermal system, and the fluid mixture is its metallogenic element precipitation. The main mechanism of lake deposit is that the ore-forming fluid of W ore of Shun Huangshan is mainly medium and low salinity NaCl-H2O-CO_2-CH4 hydrothermal system, fluid cooling and cooling are the main factors of its metallogenic element precipitation, and fluid immiscibility may also be one of the factors. We analyzed the three different mineralization of siberi skarn W-Cu deposit, scheelite ore and late quartz vein. The fluid inclusions in the pegmatite quartz have a homogeneous temperature peak of 310~330 C, the salinity is 0.18~5.71%NaCleqv, and the Raman spectrum shows the composition of CO_2 and CH4 in the gas, which belongs to the middle and low salinity NaCl-H2O-CO_2-CH4 hydrothermal system, and the homogeneous temperature of the fluid inclusions in the scheelite ore has two peaks, 260~, respectively. 280 C and 320~340 degree C, the salinity is 0.35%~5.56%NaCleqv, which belongs to middle temperature and low salinity. The peak value of the homogeneous temperature of the late quartz vein is 270~300 C, the salinity is 0.18~3.71%NaCleqv, the gas also contains CO_2 and CH4, which belongs to the middle temperature and low salinity category. The homogeneous temperature and salinity of the wolframite ore of the Jie brand W-Cu ore are obviously positive. The related linear relation shows that it has experienced fluid mixing to precipitate the metallogenic element, and observed and analyzed the fluid inclusion characteristics of the three stages of the metallogenic granite, the cloud English rock and the late quartz vein in the Shun Huangshan mining area. The quartz in the rock phase has not seen the molten inclusions in the quartz, and the test pair is mainly fluid inclusions, and the peak value of the homogeneous temperature is 2. 10~240 degree C, with the salinity of 0.18~3.55%NaCleqv, and the homogeneous temperature of fluid inclusions in the stage of the cloud English rock phase, the salinity is similar. It is presumed that it is formed by the transformation of the hydrothermal fluid in the phase of the cloud English rock. At the same time, CO_2 and CH4 are found in the gas of the quartz inclusions in the quartz rock. Therefore, the two stages belong to the middle temperature and low salinity NaCl-H2O-CO_2-CH4 hydrothermal system, and the late quartz vein is homogeneous. The peak temperature is 190~220 C, the salinity is 0.18~3.71%NaCleqv, and the gas composition also contains CO_2 and CH4, which belongs to middle low temperature and low salinity NaCl-H2O-CO_2-CH4 hydrothermal system, while the temperature span of the fluid inclusions in the cloud English rock of the main mineralization stage of the Huangshan Mountain W deposit is larger, but the salinity is in a small range, indicating that it has experienced the cooling and cooling of the fluid. The process leads to the precipitation of metallogenic elements. At the same time, a small amount of rich gas phase and rich liquid phase two inclusions are symbiotic, and the homogeneous temperature of the rich gas phase inclusions is high, which indicates that the fluid immiscibility has been experienced. This may also be one of the factors that cause the precipitation of the metallogenic elements.
【学位授予单位】：中国科学院研究生院(广州地球化学研究所)
【学位级别】：博士
【学位授予年份】：2016
【分类号】：P612
，

本文编号：2066981