阿尔金山东端余石山铌钽矿区霓辉正长岩的LA-ICP-MS定年及对成矿时代的制约

余石山铌钽矿床是近年来发现的一大型矿床,位于阿尔金造山带之红柳沟-拉配泉蛇绿构造混杂岩带、祁连造山带、欧龙布鲁克微陆块的结合部位.对矿区进行成矿背景研究时发现,矿区赋矿地层主要为长城系熬油沟组,岩性组合为变质火山岩及大理岩,穿插有霓辉正长岩体,其中发育细粒烧绿石与霓辉石等富铌钽矿物.并对霓辉正长岩进行锆石LA-ICP-MS年代学测定,结果表明霓辉石正长岩成岩年龄为(776.8±2.5) Ma,成矿与成岩年龄相近或稍晚,表明该霓辉正长岩和铌钽矿床可能形成于南华纪Rodinia超大陆裂解时所产生的大陆边缘裂谷构造环境.     

甘肃阿克塞县变粒岩型铌钽矿综合找矿方法及找矿模型

甘肃阿克塞县余石山变粒岩型铌钽矿是近年在国内新区新层位发现的一种新类型铌钽矿床,其矿床规模已达大型,但对变粒岩型铌钽矿有效的综合找矿方法总结研究不够系统。本次依托1∶5万矿产地质调查和余石山铌钽矿普查等工作成果,系统梳理和分析总结了余石山铌钽矿的有效找矿方法,发现地质、地球化学、地球物理多学科综合找矿方法能快速准确定位铌钽矿带,总结了余石山铌钽矿表格式综合找矿模型,并提出了变粒岩型铌钽矿综合找矿方法组合：（1）优选熬油沟组地层分布区内的1∶5万水系沉积物测量Nb-Ta-La-Ce-Y组合异常和1∶5万地面高精磁测高磁异常的叠加区,确定为铌钽矿的找矿靶区;（2）在1∶5000岩石剖面测量和1∶2000高精磁测剖面浓缩物化探异常的同时,结合矿区大比例尺填图快速圈定铌钽矿带,推断隐伏-半隐伏矿带的有利部位;（3）槽探工程地表圈定矿体,深部钻探验证并寻找隐伏-半隐伏矿。     

内蒙古霍各乞地区矿床新类型及其找矿前景研究

本文通过对霍各乞地区查干楚鲁-那仁宝力格火山岩带地化特征的分析研究,对该套火山岩的异常特征作出评价,对该区的找矿前景作出了探索性的研究。     

浙江东部火山岩型银矿床地球化学特征

浙东火山岩型银矿床属浅成中－低温火山热液成因。与成矿有关的火山岩、次火山岩具有富硅、贫铁、高钾、低钠特点。稀土元素表明，成矿火山岩与次火山岩是由地壳部分熔融形成的。同位素组成具岩浆成因特征。     

甘肃镜铁山矿床构造新认识

甘肃镜铁山铁矿是我国西北地区重要的钢铁基地,目前保有铁矿石4亿吨,因同时具有中等规模铜矿床而倍受关注.原矿山勘探资料认为镜铁山矿床是向斜构造,铁矿体受向斜控制,下部已无矿,基于该认识,自20世纪90年代至今,除一些生产性勘探外,深部及外围找矿基本停滞,并有Ⅲ,Ⅳ矿体,Ⅵ,Ⅶ矿体先后闭坑.笔者最近在此工作期间,依据桦树沟矿区开采现状,黑沟矿区控矿特点以及节理与千枚理关系,推测镜铁山矿并不是向斜,以黑沟矿区为代表,可能主要为断层控矿,深部和外围找矿潜力巨大.     

A Petrographic and Mineralogical Study of Volcanic Rocks from the Mayaxueshan Area, North Qilian Fold Belt, NW China

The Ordovician volcanic rocks in the Mayaxueshan area have been pervasively altered or metamorphosed and contain abundant secondary minerals such as albite, chlorite, epidote, prehnite, pumpellyite, actinolite, titanite, quartz, and/or calcite. They were denoted as spilites or spilitic rocks in terms of their petrographic features and mineral assemblages. The metamorphic grades of the volcanic rocks are equivalent to that of the intercalated metaclastic rocks. This indicates that both the spilitic volcanic rocks and metaclastic rocks in the Mayaxueshan area have formed as a result of Caledonian regional metamorphism. We suggest that the previously denoted spilitic rocks or altered volcanic rocks should be re-denoted as metabasalts or metabasaltic rocks. The metamorphic grade of the volcanic rocks increases with their age: prehnite-pumpellyite facies for the upper part of the Middle Ordovician volcanic rocks, prehnite-pumpeilyite to lower greenschist facies for the lower part of the Middle Ordovician vol     

Rare Earth Elements Geochemistry of Sheikh-Marut Laterite Deposit,NW Mahabad,West-Azarbaidjan Province,Iran

Laterite deposit at Sheikh-Marut(NW Mahabad,West-Azarbaidjan province,Iran) occurred within middle-upper Permian carbonate rocks.It consists of seven stratiform and/or discontinuous lenticular layers extending over 4.2 km in length and having thicknesses ranging from 3 to 14 m.Mineralogical data show that the ores contain kaolinite and hematite as major and boehmite, diaspore,halloysite,amesite,anatase,and muscovite-illite as minor mineral phases.The computed Ce anomaly values in the ores range from 0.05 to 20.84.Conservative index(e.g.,Eu/Eu) suggests that this deposit is a product of alteration and weathering of basaltic rocks.Rhythmic increment ofΣREE values of the ores with approaching to the carbonate bedrocks shows an in-situ occurrence of lateritization processes.Mass change calculations of elements indicate that two competing processes namely leaching and fixation were the major regulating factors in concentration variation of REEs (La-Lu) in this deposit.The obtained results show that pH increase of weathering solutions by carbonate bedrocks,existence of organic matters,and the degree of comlexation with organic ligands played remarkable role in distribution of REEs during lateritization.Further geochemical considerations revealed that secondary phosphates,Mn-oxides and -hydroxides,diaspore,and anatase were the potential hosts for REEs in this deposit.     

新疆雪米斯坦火山岩型铀矿成矿条件及远景预测

笔者在收集、整理前人资料的基础上,对新疆准噶尔西北部雪米斯坦地区进行铀成矿条件分析,认为区内铀成矿与大地构造环境、地层及火山作用、控矿构造、铀源等密切相关。结合已知铀矿床的产出地质特征和近年来的野外地质工作成果,总结了该地区火山岩型铀矿的分布规律,预测并圈定了一级铀矿远景区6片,二、三级铀矿远景区11片。     

阿尔金北缘喀腊达坂火山岩型铅锌矿床研究

火山成因块状硫化物矿床越来越受到重视,喀腊达坂铅锌矿位于北东向阿尔金走滑断裂与东西向阿尔金北缘断裂夹持的喀腊大湾地区,是阿尔金北缘红柳沟—拉配泉金、铜、铁及多金属成矿带中唯一大型铅锌矿床。矿区主要出露奥陶系下统卓阿布拉克组火山沉积岩系,呈近东西走向,以向北中等角度倾斜的单斜层为特点,倾角30°~58°;矿化严格受火山沉积岩特定层位和岩性控制,即矿体均产于卓阿布拉克组第四亚组的中酸性火山岩(流纹岩、英安熔岩、英安质晶屑凝灰岩)中,矿体具有层状、似层状特点,产状稳定延伸大;最大矿体走向延伸超过2400m,倾向延深大于900m。主要有用组分Pb、Zn,伴生有用组分Cu、Au、Ag、S等。主要蚀变类型有黄铁矿化、硅化、绢云母化,地表氧化带形成黄钾铁钒化和褐铁矿化。矿石平均铅同位素组成为~(208)Pb/~(204)Pb=38.1169、~(207)Pb/~(204)Pb=15.6278、~(206)Pb/~(204)Pb=18.4684,显示矿石的铅具有上地壳铅和造山带铅的混合来源;矿石硫同位素组成平均+8.28‰,代表了海相沉积岩来源的硫与岩浆岩来源硫的混合;矿石稀土元素配分曲线与矿区及喀腊大湾地区中酸性火山岩的稀土元素配分曲线具有一致性或者相似,说明矿石与含矿中酸性火山岩具有一致的成因与来源;矿石微量元素特征显示Nb、Ta负异常与Ba的正异常,反映出存在海相沉积岩物质的混入,并具有岛弧成矿构造环境。含矿火山岩锆石SHRIMP U-Pb年龄482~485Ma,代表了矿床的形成时代为早古生代早奥陶世。综合喀腊达坂铅锌矿地质地球化学特征的研究,确认其属于火山成因块状硫化物矿床(VMS型)。所以,喀腊达坂铅锌矿成矿过程可以概括为:在早古生代奥陶纪早期北阿尔金洋发生向南的板块俯冲,板块俯冲作用导致俯冲带下盘的洋壳及其上的海相沉积物和俯冲带上盘的陆壳发生部分熔融,形成了中酸性岛弧型岩浆;在岩浆喷发的晚期,逐渐形成富含铅锌成矿物质的残余岩浆;当这些富含铅锌的残余岩浆发生喷发,最终形成了火山成因岩块状硫化物型铅锌矿床。火山岩型铅锌多金属矿床是阿尔金北缘喀腊大湾地区南带最重要勘查和预测类型,该火山岩型矿化带的西延区段是有利的找矿靶区。     

湖南仁里超大型稀有金属矿床的成矿特征与成矿模型

湖南仁里铌钽矿床位于燕山期幕阜山复式岩体西南缘,是我国近年来新发现的超大型花岗伟晶岩型铌钽矿床,伟晶岩脉产在花岗岩内部裂隙或灌入冷家溪群片岩中。矿区伟晶岩可分为微斜长石型、微斜长石钠长石型、钠长石型和钠长石锂辉石型四个类型分带,且脉体呈NE-SW向分布。相对于北东部的伟晶岩,南西部的伟晶岩具有较高的分异度,铌钽矿化程度高,仁里矿区为幕阜山地区铌钽矿化浓集中心,是幕阜山地区铌钽等稀有金属主要产地。较大规模伟晶岩脉具有较完善的分带,铌钽矿化主要产在伟晶岩内部的中-粗粒白云母钠长石带和锂云母石英带。各伟晶岩脉总体上具有地表品位低,深部品位升高的特点,在标高411 m时,品位达到最高值(Ta_2O_5品位0.438%),说明仁里矿区深部具有较大找矿潜力。本文在总结仁里矿床成矿特征和成矿规律的基础上,分析了周边及深部的找矿方向,建立了复式岩体"体中体"成矿模型。区域找矿需要重视浅部低品位伟晶岩脉的深部评价,按照"北找钽铌、南找锂"的原则开展外围找矿工作。     

Metamorphism of the Basement of the Qilian Fold Belt in the Minhe-Ledu Area, Qinghai Province, NW China

The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on me     

New Nb-Ta Mineralization Age of the Dajishan W-Nb-Ta Deposit in Jiangxi Province,South China

正Objective The Dajishan W-Ta-Nb deposit is located in the junction of southern Jiangxi and Guangdong Provinces(Fig. 1a). This deposit contains about 190, 000 tons of WO_3 reserves,belonging to a super-large W deposit. Most W mineralization (mainly wolframite) at Dajishan occurred in quartz veins, with also some disseminated wolframite in the No. 69 granite. The estimated reserves in     

甘肃北山钨矿床时空分布、矿床类型及成矿动力学背景

甘肃北山造山带经历漫长而复杂的增生造山作用并于二叠纪发生碰撞造山,引发广泛的花岗质岩浆活动及相应的钨成矿作用。前人已对这些矿床的地质地球化学特征进行大量的研究,但在成矿动力学背景、成矿时代等方面仍存在着争议。基于此,本文在前人对甘肃北山钨矿床研究的基础上,通过详细的野外调研和室内综合研究,对该区钨矿床时空分布及地质、地球化学特征进行总结,并提出成矿动力学模型。甘肃北山钨矿床集中分布于星星峡—明水古微陆块周缘及双鹰山—花牛山岛弧,可以进一步厘定为两期成矿作用,即早期早志留世—中石炭世（439～362 Ma,322～314 Ma）岛弧碰撞拼贴引发古陆壳重熔,形成携带大量钨锡成矿元素的花岗质岩浆流体,最终上升至构造有利位置成矿,是北山钨锡多金属成矿的主成矿期,矿化类型多为石英脉型黑钨矿;晚期为早二叠世—中三叠世（286～226 Ma）后碰撞伸展诱发中酸性岩浆的大规模上侵及相关的钨钼矿化,矿化类型为矽卡岩型白钨矿及斑岩型钼（钨）矿,其中钨作为钼的伴生矿种出现。     

Geology and Origin of the Dongping Alkalic-Type Gold Deposit, Northern Hebei Province, People's Republic of China

Abstract: The Dongping deposit, located near the center of the northern margin of the north China craton, is one of the largest gold deposits in China. It is spatially, temporally, and genetically associated with the shallowly-emplaced Hercynian Shuiquan-gou alkaline intrusive complex. The complex intrudes high-grade metamorphic rocks of the Archean Sanggan Group along a deep-seated fault zone within the north China craton. Four major ore bodies (Nos. 1, 2, 22, and 70), consisting mainly of a set of en echelon lenses and veins, have been delineated at the Dongping deposit. Hypogene hydrothermal activities can be divided into four periods from early to late including: (1) gold-bearing K–feldspar–quartz stockworks and veins; (2) disseminated sulfide and gold zones; (3) gold-bearing quartz veins, and (4) barren calcite-quartz veins. Individual veins and stockwork systems can be traced along strike for 125 to 600 m and downdip for 100 to 600 m; they range from 0. 5 to 3 m in thickness. The mineralogical composition of the ore in the first three hypogene periods is relatively simple. It is composed of pyrite, galena, sphalerite, magnetite, specularite, chalcopyrite, native gold, electrum, calaverite, and altaite. Gangue minerals include K–feldspar, quartz, sericite, chlorite, epidote, albite, and calcite. Ore grade averages 6 g/t Au, but varies between 4. 14 and 22. 66 g/t Au. Gold is generally fine-grained and not visible in hand specimen. Fluid inclusions in ore-bearing quartz of periods 1, 2, and 3 are CO₂–rich, variable salinity (2. 5–21 wt% equiv. NaCl), and have variable homogenization temperatures of 195° to 340°C. Quartz in the gold-bearing K–feldspar–quartz stockworks (period 1), disseminated sulfide and gold zones (period 2), and the gold-bearing quartz veins (period 3) has calculated δ¹⁸O_H2O values between –1. 7 and 6. 9%, and δ values of fluid inclusion waters between –101 and –66%. All these isotope data of the ore-forming fluids plot between the magmatic fluid field and the meteoric water line. Sulfide minerals disseminated in host rocks show positive δ³⁴S values of 1. 9 to 3. 5%. Pyrite separates from he gold-bearing K–feldspar–quartz stockworks and veins (period 1) have a δ³⁴S range of –4. 3 to 0. 5%, whereas δ³⁴S values of pyrite, chalcopyrite, galena, and sphalerite from the disseminated sul-fide and gold zones (period 2) and the gold-bearing quartz veins (period 3) vary from –5. 3 to –13. 4%. Gold ores are also characterized by relatively radiogenic lead isotope compositions compared to those of the alkaline syenite host rock. The data are interpreted as indicative of a mixing of lead from the alkaline intrusive complex with lead from Archean metamorphic rocks. The combined fluid inclusion measurements, sulfur, oxygen, hydrogen, and lead isotope data, and petrological observations indicate that the Dongping deposit was formed from the mixing of these magmatic fluids with meteoric waters. The deposit is, therefore, believed to be a product of Hercynian alkaline igneous processes within the north China craton.     

胶东金青顶金矿床围岩蚀变特征与金矿化

金青顶金矿围岩蚀变发育,从近矿到远矿依次发育黄铁绢英岩化、绢英岩化和钾长石化,并呈近似对称的带状分布.由地表至深部,钾长石化蚀变强度有增大的趋势,局部出现膨大收缩的豆英状构造特征;绢英岩化浅部较发育,深部反复尖灭重现;黄铁绢英岩化带宽度很窄,仅浅部独立成带产出.各类蚀变过程中与Au成矿相关的Ag、As、Hg等元素含量增加,蚀变围岩中成矿元素以带入为主,推测围岩的主要作用是冷却成矿热液,并改变其化学性质,使成矿物质在有利的容矿空间沉淀富集,而非提供成矿物质的母岩.     

甘肃阿克塞余石山铌钽矿区二长花岗岩成因和形成环境:来自年代学及地球化学的证据

余石山铌钽矿区位于北阿尔金-柴北缘-祁连的交汇部位,该区域构造演化复杂.为了揭示矿区内二长花岗岩的成因和形成环境,运用岩石学、岩石地球化学、锆石U-Pb年代学、锆石Lu-Hf同位素等理论及技术方法对该二长花岗岩进行了系统的研究.该二长花岗岩的详细定名为中细粒似斑状黑云二长花岗岩,暗色矿物以黑云母、角闪石为主.地球化学特征表明,余石山的二长花岗岩属于钾玄质准铝质-弱过铝质系列,富集Rb、Th、K等大离子亲石元素,相对亏损Nb、Sr、P、Ti等高场强元素,稀土元素配分曲线具有明显的负Eu异常,δEu的平均值为0.57,（La/Yb）_N的平均值为11.09,说明该二长花岗岩体岩浆部分熔融程度较高.根据岩石学及地球化学特征可判断该岩体为I型花岗岩.锆石LA-ICP-MS U-Pb定年显示,该二长花岗岩的结晶年龄为481.3±1.7 Ma,形成于早奥陶世.锆石Lu-Hf同位素分析表明,锆石ε_Hf（t）的值为+0.4~+11.8,均为正值,二阶段模式年龄的范围为675~1 308 Ma,指示其源岩主要为元古代新生地壳物质.该二长花岗岩的形成与早奥陶世时期北阿尔金洋壳俯冲中南祁连陆壳密切相关,在中南祁连陆壳边缘的余石山地区（弧后）,由于洋壳俯冲导致了陆壳的伸展从而产生了裂隙,俯冲产生的熔融岩浆通过裂隙上侵而形成了该二长花岗岩岩体.      

云南中基性火山岩风化壳离子吸附稀土成矿作用分析 ——以腾冲龙井山安山岩风化壳型稀土矿床为例

近年来在云南发现了多个离子吸附型稀土矿,特别是滇西的腾冲—陇川地区、临沧—勐海地区成为了找矿突破最大、最受关注的地区.本次工作在腾冲火山岩带南部龙井山发现一套富含轻稀土的第四系中基性火山岩建造,该含矿建造稀土元素丰度平均值达532×10–6.经过系统的调查研究及采样工作,结果表明腾冲龙井山新近纪中的辉石安山岩富含轻稀土,为一种年轻火山岩形成的风化壳型稀土矿床,矿体平均厚度9.15 m,平均品位(TREEO)0.11％,矿体品位、厚度变化与风化壳厚度呈正相关.该中基性火山岩离子吸附型稀土矿床的发现丰富了云南稀土矿床类型.这种年轻的中基性火山岩型稀土矿的成矿地质背景、地球化学特征等,为寻找中基性岩有关的稀土矿床提供参考.     

广宁洞头南铌钽矿床地质特征及找矿方向

广宁洞头南铌钽矿床位于粤西成矿区(带)内,成矿地质条件较好,有元古界震旦系基底地层和海西-印支期花岗岩,又位处纬向构造体系与新华夏构造体系的斜接复合部位.矿床赋存于震旦系C组地层中,中型规模,矿床类型为岩浆作用形成的白云母钠长石伟晶岩铌钽矿床.     

陕西八卦庙金矿钠长石的成因

陕西八卦庙金矿产于凤太矿田北部，含矿地层为上泥盆统星红铺组下段中上部。赋矿围岩中含有较多的钠长石。钠长石呈层状顺层产出，镜下观察为砂屑状、次棱角状，与石英及铁白云石呈镶嵌粒状关系，而无交代结构；钠长石成分计算其形成温度超过800℃和400℃，表明其形成与喷流作用有关，并受到后期变质改造；锯钠长石X射线衍射分析，其有序度为0．38，形成温度为620－667℃，说明它不是一般意义上的热水沉积岩产物。上述研究表明：八卦庙金矿中的钠长石是火山喷发沉积－变质重结晶的产物，火山沉积作用参与该地区成矿是形成巨型金矿的最有利条件。含钠长石硅质岩、千枚岩、灰岩组合是找矿评价的重要标志。     

“八O一”稀有稀土矿床碱性花岗岩的含矿性、矿化规律及成因分析

内蒙古通辽市扎鲁特旗与碱性花岗岩有关的“八O一”特大型稀有稀土矿床位于巴尔哲北北东向背斜构造部位,以Nb、Y、Ta为主,伴生Be等多种稀有稀土元素。含矿岩体为普遍矿化的燕山期碱性花岗岩,且碱性花岗岩体与“八O一”稀有稀土矿床具有生成关系。通过对碱性花岗岩的岩石特征及含矿性、含矿元素的变化规律、岩石化学成分与稀有元素的关系、矿化元素的富集规律及矿床成因进行综合分析,认为“八O一”稀有稀土矿床为碱性花岗岩岩浆晚期分异交代型矿床。