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1、乔夏哈拉式铁铜金矿成矿模式及其找矿意义本文受“我国西部重要成矿区带矿产资源潜力评估”项目资助应立娟1 王登红2 梁婷3 周汝洪4Ying Lijuan1 Wang Denghong2 Liang Ting3 Zhou Ruhong41. 中国地质科学院研究生部，北京 1000372. 中国地质科学院矿产资源研究所，北京 1000373. 长安大学 资源学院，陕西西安，7100544. 新疆地矿局，新疆乌鲁木齐，8300001. Graduate Department, Chinese Academy of Geological Sciences, Beijing 1000372. Instit
2、ute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 1000373. Changan University, Xian, 710054;4. Bureau of Geology and Mineral Resources in Xinjiang, Wulumuqi, 830000Abstract: The Qiaoxiahala iron-copper-gold deposit as a typical ore deposit presents Qiaoxiahala-type mineral de
3、posits, a group of iron-copper-gold deposits related to volcanism in Early Paleozoic. This paper has expounded the describing pattern, metallogenetic pattern and prospecting model of Qiaoxiahala-type mineral deposits in details.Key words: Qiaoxiahala-type, models of mineral deposits, minerogenetic s
4、eries of mineral deposits, mineral deposit type摘要：新疆阿尔泰乔夏哈拉铁铜金矿床作为乔夏哈拉式的典型矿床，代表了一组阿尔泰地区与早古生代海西期火山作用有关的铁铜金矿床。本文对乔夏哈拉式铁铜金矿的主要内容：描述性模式、成因模式和找矿评价模型进行了具体阐述。关键词：乔夏哈拉式 成矿模式 矿床成矿系列 矿床式 1 引言19992004年中国成矿体系和区域成矿评价大调查综合研究项目，较系统地综合研究了全国及各省、区的区域成矿规律问题，对成矿系列的研究达到了新高度，进一步完善了成矿系列的概念，在全国建立了214个矿床成矿系列，434个矿床成矿亚系列，978
5、个矿床式，编制了第二代全国前寒武纪、古生代、中生代及新生代成矿系列图(陈毓川等，2007)。矿床成矿系列(minerogenetic series of mineral deposits)是在一定的地质历史期间或构造运动阶段，在一定的地质构造单元及构造部位，与一定的地质成矿作用有关，形成一组具有成因联系的矿床组合自然体。亦可视为一种新的矿床自然分类。矿床成矿系列的序次为矿床成矿系列组合、矿床成矿系列类型；矿床成矿系列；矿床成矿亚系列；矿床式和矿床(陈毓川等，2006)。矿床是其研究的基本单位，位于第五序次，而矿床式则位于高于矿床一个序次的第四序次。每个矿床式的主要内容可包括描述性模式、成因模式
6、和找矿评价模型。2 乔夏哈拉式铁铜金矿的成矿模式新疆阿尔泰乔夏哈拉铁铜金矿床是乔夏哈拉式铁铜金矿床的典型代表。以乔夏哈拉铁铜金矿床为例，乔夏哈拉式铁铜金矿的主要内容分别叙述如下。2.1 描述性模式乔夏哈拉铁铜金矿床以产于基性海相火山岩及其火山碎屑岩中的磁铁矿、黄铜矿为主，TFe 34.13%，Cu平均0.53%，含Cu最高品位达2.65%。东矿区III号矿体，Cu平均1.4%，Au平均0.15g/t；东矿区I号矿体，Cu平均0.55%，Au平均2.4g/t邓吉牛，王军升，廖启林. 2000. 布尔根矿带金铜找矿评价研究报告. 新疆305项目办公室：内部资料。东矿段部分矿体含铜、钴，伴生的钴品位
7、已达工业要求，达0.4%，钼最高达0.024%(120万富蕴幅，1978)。西矿区基性火山岩中磁铁矿矿体为主，有Fe1-1，Fe1-2，Cu1-1，Cu1-2等；东矿区以铜金矿体为主，有IVII号矿体，III号为主。磁铁矿矿体呈多层产出，以薄层状夹于围岩之间，但在多数情况下，主含矿层仅为一层(李龙乾，2003)。在矿体形态方面，磁铁矿体呈似层状、扁豆状、透镜状产出。如，在西矿段：矿体呈扁豆状或板状，局部为透镜状；在东矿段：矿体呈不规则的疙瘩状、团块状和透镜状，长轴走向与岩层一致。黄铜矿体以透镜状和似层状为主。矿石的矿物组合按矿石的构造不同而有所区别，块状矿石主要为磁铁矿或黄铜矿；条带状矿石为绿
8、帘石磁铁矿；而浸染状矿石则包括黄铁矿黄铜矿磁铁矿和黄铜矿磁铁矿。金的主要赋存矿物主要为黄铁矿、黄铜矿、斑铜矿和磁铁矿。矿石构造主要出现致密块状矿石，条带状磁铁矿和浸染状磁铁矿；矿石结构包括自形、半自形粒状结构，多边形解理结构、他形粒状结构和片状结构(120万富蕴幅，1978)。乔夏哈拉铁铜金矿床位于阿尔泰山南缘额尔齐斯断裂的南侧，其含矿地层为中泥盆统北塔山组(D2b)，磁铁矿体的直接容矿围岩为凝灰砂岩、沉凝灰岩、铁质粉砂岩；东矿区II号矿体，矿体底板为基性火山岩、火山碎屑岩，矿体顶底板多数为火山熔岩及其碎屑岩。自上而下矿化分带出现FeFe-CuCu-Au，分别对应于磁铁矿矿石含铜磁铁矿矿石黄铜
9、矿矿石，层纹状、条带状和块状块状和稠密浸染状致密块状构造的变化。围岩蚀变出现绿帘石化，绿泥石化，碳酸盐化，绢云母化，硅化，黄铁矿化，透闪石化(120万富蕴幅，1978)。蚀变分带由远离矿体到接近矿体出现四个蚀变带：即绿帘石化带，绿帘方解滑石绿泥石化蚀变带，绿泥透辉石化蚀变带，铜(金)矿体。地表出现孔雀石化、褐铁矿化和磁铁矿化(倪梁，2004)。2.2 成因模式乔夏哈拉为火山沉积后期热液叠加成因铁铜金矿床，形成火山沉积成因块状、条带状磁铁矿矿石和热液交代成因细脉浸染状黄铜矿矿石、块状黄铜矿矿石和层纹状磁铁矿矿石。成矿时代主要为泥盆纪火山沉积期和石炭纪火山热液叠加期。成矿出现于早泥盆世，其奥长花岗
10、岩K-Ar年龄为390.3Ma(陈哲夫，1995)；结束于晚泥盆世早石炭世(刘德权等，1996)，错断磁铁矿层的闪长岩角闪石Ar-Ar年龄为380Ma左右。区域成矿构造背景方面，乔夏哈拉矿床所处的环境根据不同地质学家的构造分类方案而有所不同：1)西伯利亚板块阿尔泰陆壳板段额尔齐斯Pz2早期拉张陆缘岩浆带(肖序常等，1992)；2)西伯利亚板块蒙古阿尔泰Pz1大陆边缘额尔齐斯构造混杂带(何国琦等，1994)；3)斋桑北准噶尔褶皱系富蕴构造建造带额尔齐斯亚带(陈毓川等，1995)；4)准噶尔陆间开合系北准噶尔Pz开合带乔夏哈拉阿尔曼泰-O洋壳残片(陈哲夫等，1997)。其大地构造位置为阿尔泰南缘和
11、准噶尔北缘的过渡地带，额尔齐斯断裂的南侧，而不属于阿尔泰造山带。乔夏哈拉矿床磁铁矿的具体成矿环境可能为浅海陆棚上相对低洼的地段，在这种洼地中的海底水处于一种相对较静止的碱性还原环境，这是磁铁矿形成的必备条件。就成矿物质来源而言，Fe来源于基性火山熔岩，与海底火山作用有关；Cu主要来源于后期的热液，少量可能由基性火山熔岩提供；而Au来源于热液为主，后期闪长岩侵入事件与Cu-Au的成矿作用关系密切。地球化学标志方面，东矿区II号矿体，其原生晕有Cu、Au、As、Sb、Co、Ni、Zn、Ag；Ba的正异常范围十分宽广，而Co、Ni、Cr、As、Sb的异常则主要分布于矿体下方。 硫同位素资料中，黄铁矿
12、d34S值为+0.73+2.92，平均值+1.56；黄铜矿d34S值为+1.17+2.2，平均值+1.7，说明黄铁矿、黄铜矿中硫来源于地幔(李泰德，2002)。乔夏哈拉黄铁矿铅同位素的206Pb/204Pb为18.12418.158；207Pb/204Pb为15.40815.446；208Pb/204Pb为37.50537.622；m值变化为9.129.19，显示正常铅的特征(万博等，2006)。氢氧同位素方面，磁铁矿d18OH2O为+9.93+11.49，平均为+10.73，属原生岩浆水范围。磁铁矿气液包裹的dD为-80.9-115.3，偏于大气降水。证明磁铁矿的物质来自火山喷气，但在沉积成
13、矿过程中掺入了大气降水(李泰德，2002)。成矿流体具有岩浆水加大气降水的混合源特征(彭省临等，1996)。乔夏哈拉铁铜金矿区黄铁矿的(87Sr/86Sr)变化范围为0.7044070.704417， eNd(t)变化范围1.16.5由(380Ma)推算。乔夏哈拉矿区黄铁矿矿石初始锶平均为0.704412，而 eNd(t)相对较高。2.3 找矿模型 矿床式的找矿模型可从以下几个方面考虑：地质条件；找矿历史标志；地球物理标志；地球化学标志；遥感信息标志和地表找矿标志。(1)地质条件：构造环境：乔夏哈拉铁铜金矿床处于额尔齐斯断裂南侧的额尔齐斯挤压带内。岩石组合：磁铁矿仅赋存于中泥盆统北塔山组第3岩
14、性段(第三岩性段(D2b3)为主要容矿层，上下为灰白色大理岩、不纯大理岩或结晶灰岩，中部为片理化钙质凝灰岩，钙质、凝灰质砂岩夹灰岩透镜体，局部有玄武岩出露受构造作用多蚀变为绿泥绢云母片岩)，因该岩性段的钙质砂岩及灰岩为找磁铁矿的间接标志。闪长岩类的侵入往往导致后期的热液叠加改造，因此闪长岩类的侵入可作为金铜的间接找矿标志。围岩蚀变：在铁矿体的围岩中往往形成绿帘石化矽卡岩，此为叠加改造最具代表性和最明显的标志。凡出现绿帘石矽卡岩的地方，将有可能找到金铜矿体；碳酸盐化带亦为找金铜的标志；强烈硅化则为找金矿的标志(倪梁，2004)。(2)找矿历史标志：找矿遗迹：乔夏哈拉铁铜金矿床于1955年经地质局
15、622队踏勘，1958年713队进行矿检。1959年阿勒泰地质大队又在外围普查，同年，物探队进行电、磁测，否定矿床价值，认为主要异常由超基性岩引起。19601961年阿尔泰地质大队进行初勘，确定为小型矿床(120万富蕴幅，1978)。之后地表磁铁矿出露处有民采遗迹。文字记录：在1978年的120万富蕴幅区调报告中就有乔夏哈拉的记录，当时为小型铁矿和铜矿点。近年来，其规模有所扩大，截止2002年底，铁矿石总资源储量为462万吨，铜31200吨，金1051千克。(3)地球物理标志：重力：乔夏哈拉铁铜金矿床重力异常以线性异常为主，形态多变，走向变化上分区明显，与构造线方向基本一致，属于重力高值区。这
16、些重力异常高值区反映了本区地幔普遍上升的特点，局部高重力异常还与石炭纪、泥盆纪以中基性火山岩为主的复式背斜及隐伏基性岩体有关。磁法：瞬变电磁法(TEM)为低响应值、高磁性异常、中高电阻率、低极化值的综合异常模型。乔夏哈拉老山口金铜成矿带位于额尔齐斯异常带和乌伦古河断裂异常带之间的航磁异常区，其磁场走向以北西向为主，呈现条带状正负相间的异常区。该异常区的航磁特点是强度大，变化剧烈，梯度陡，形成向北突起的弧形航磁异常带。乔夏哈拉铜金矿化区显示高磁异常。电法：在测区北部的中基性火山岩和自西矿段至东矿段的铜金磁铁矿带上，激电具有基本一致的响应特征，极化率极大值可达5%，视电阻率在600m左右；而在南部
17、的背景磁场上，激电则显示出低阻高极化特征，其中极化率大于10%，视电阻率小于100m。这一特征为在该地段寻找新类型的矿体提供了较为有利的信息邓吉牛，王军升，廖启林. 2000. 布尔根矿带金铜找矿评价研究报告. 新疆305项目办公室：内部资料。(4)地球化学标志：区域：以Au、Cu、As综合异常为主，并伴有Cr、Ni、Co异常。矿区：乔夏哈拉矿床东矿区II号矿体：一方面与海底火山成矿作用有关的异常有些相似，如Co、Ni、Cr的异常主要分布于矿体下方，另一方面又显示热液成矿作用的特点，如异常范围宽，异常分带明显，As、Sb异常则主要分布于矿体下方等。(5)遥感信息标志：乔夏哈拉的遥感信息资料暂无
18、。(6)地表找矿标志：在乔夏哈拉东矿区和西矿区地表能见到磁铁矿铁矿(化)体露头。3 找矿意义 根据古生代成矿区带划分，新疆乔夏哈拉铁铜金矿床位于古亚洲成矿域准噶尔成矿省北准噶尔镍、铜、铁、钼、金、膨润土、煤成矿带(汤中立等，2005)。现有的矿床成矿体系中，还没有乔夏哈拉式铁铜金矿的确切位置，但根据该矿床的地质特征和其他矿床的对比，与索尔库都克式铜钼矿较为相似，可暂时地将乔夏哈拉式铁铜金矿归入与晚古生代构造岩浆作用有关的铁、铜、镍矿床成矿系列，与华力西早期次火山火山岩建造有关的铁铜金矿床成矿亚系列中。在古生代大规模成矿作用中，乔夏哈拉铁铜金矿床与海相火山岩浆作用或海底火山喷流沉积作用大规模成矿
19、作用关系最为密切。乔夏哈拉式铁铜金矿在华力西期构造活动带的岛弧带基性火山岩系中比较有利于成矿。 位于乔夏哈拉东南青河县的老山口磁铁矿矿床，其地质特征和乔夏哈拉矿床相似，在深部也具有铜的潜力。乔夏哈拉式铁铜金矿在准噶尔北缘向东南具有进一步找矿的潜力。Minerogenetic model of Qiaoxiahala-type Fe-Cu-Au deposits and its prospecting significanceAssissted by the project named “Assessment on the mineral resources in the significant
20、 metallogenic regions of West China”Ying Lijuan1 Wang Denghong2 Liang Ting3 Zhou Ruhong41. Graduate Department, Chinese Academy of Geological Sciences, Beijing 1000372. Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 1000373. Changan University, Xian, 710054;4. Bureau
21、 of Geology and Mineral Resources in Xinjiang, Wulumuqi, 830000Abstract: The Qiaoxiahala Fe-Cu-Au deposit as a typical ore deposit presents Qiaoxiahala-type mineral deposits, a group of Fe-Cu-Au deposits related to volcanism in Early Paleozoic. This paper has expounded the describing pattern, minero
22、genetic pattern and prospecting model of Qiaoxiahala-type mineral deposits in details.Key words: Qiaoxiahala-type, model of mineral deposits, minerogenetic series of mineral deposits, mineral deposit type1 IntroductionMinerogenetic series of mineral deposits presents a natural group of mineral depos
23、its with genetic relationships formed at a certain geological period or a tectonic movement stage in a certain geological unit and a certain tectonic position under a certain mineralization (Chen Yuchuan et al., 2007). It is a brand-new natural classification of mineral deposits. Minerogenetic syste
24、m includes five order classes of units: minerogenetic series association of mineral deposits and minerogenetic series type of mineral deposits; minerogenetic series of mineral deposits; minerogenetic sub-series of mineral deposits; mineral deposit type and mineral deposit (Chen Yuchuan et al., 2006)
25、. Mineral deposit is the basic unit at the fifth class, whereas mineral deposit type is one class higher than mineral deposit at the fourth. Each mineral deposit type can contain a describing pattern, minerogenetic pattern and prospecting-evaluation model.2 Minerogenetic model of Qiaoxiahala-type Fe
26、-Cu-Au depositsThe Qiaoxiahala Fe-Cu-Au deposit in Xinjiang is the typical one as Qiaoxiahala-type Fe-Cu-Au deposit. Taking it as an example, the main contents of this type can be concluded as following.2.1 Describing patternThe Qiaoxiahala Fe-Cu-Au deposit mainly produces magnetite and chalcopyrite
27、 hosted by basic marine volcanic rocks and the responding pyroclastic rocks with TFe at 34.13 % and Cu at 0.53% at average and up to 2.65%. The No. III orebody in the eastern mining sector is with Cu at 1.4% at average and Au at 1.5g/t, whereas No. I with Cu at .055% and Au at 2.4g/t. Cu and Co asso
28、ciated have reached the pay grade up to 0.4% and 0.024% respectively (Xinjiang Uygur Autonomous Region Geological Bureau, 1978). Magnetite orebodies mainly occurred in the western mining sector as the stratiform-like, phacoidal, lenticular, whereas chalcopyrite orebodies concentrated in the eastern
29、mining sector labelled IVII as stratiform and/or lenticular (Li Longqian, 2003). Ores included massive magnetite and chalcopyrite, banded epidote+magnetite, and disseminated pyrite+chalcopyrite+magnetite and chalcopyrite+magnetite. Ore structures appeared euhedral and subhedral granular, polygonal c
30、leavage, anhdral granular and sheet texture.The Qiaoxiahala Fe-Cu-Au deposit located at the south side of the Ertix Fault at the margin of Altay Mountains hosted by Middle Devonian Beitashan Formation (D2b). The footwall rocks were basic volcanic rocks and pyroclastic rocks, whereas volcanic lava an
31、d the pyroclastic rocks were the hanging wall. Orebodies occurred as FeFe-CuCu-Au from top to bottom vertically, responding to the stratified, banded and massive magnetite oremassive and disseminated Cu-bearing magnetite orecompact massive chalcopyrite ore. Alterations in the wall rocks developed we
32、ll including epidotization, chloritization, carbonatization, sericitization, quartz, pyrite, tremolite et al (Ni Liang, 2004). 2.2 Minerogenetic patternThe Qiaxiahala Fe-Cu-Au deposit was supposed to be formed by marine volcanic-sedimentary mineralization enriched by later hydrothermal activity. The
33、 Ar-Ar plateau age of hornblende in diorite from the western mining sector as almost vertically cutting the iron bed was 378.13.6 Ma, indicating the major iron minerogenetic period concentrated in Devonian. At the aspect of regional minerogenetic tectonic background, the tectonic location of the Qia
34、oxiahala ore deposit was argued according to different geologists: 1)Siberia plateAltay continental crust partErtix Pz2 early exssentioned continental margin magmatic belt (Xiao Xuchang et al., 1992); 2) Siberia plateMongolia-Altay Pz1 continental marginErtix tectonic mixing belt (He Guoqi et al., 1
35、994); 3) Zaisang-North Junggar fold systemFuyun tectonic formation beltErtix sub-belt (Chen Yuchuan et al., 1995); 4)Junggar open-close system between continentsNorth Junggar Pz open-close beltQiaoxiahala-Aermantai -O ocean crust relic (Chen Zhefu et al., 1997). Its present geotectonic location was
36、in the transitional belt between Altay south margin and Junggar north margin, and also the southern side of Ertix Fault, but not the inside of Altay orogin belt. As far as the minerogenetic material concerned, Fe came from the same magmatic source as the basic volcanic lava related to the marine vol
37、canism, Cu mainly sourced from later hydrotherm and a little from the basic volcanic lava, whereas Au was mainly provided by the later hydrotherm related to the diorite intrusion.On geochemistry of sulfur isotopes, d34S of pyrite changed from +0.73 to +2.92, +1.56 at average; d34S of chalcopyrite ra
38、nged between +1.17+2.2 at the average of +1.7, indicating sulfur in pyrite and chalcopyrite sourced from the mantle (Li Taide, 2002). On lead isotopes, 206Pb/204Pb of pyrite was 18.12418.158, 207Pb/204Pb was 15.40815.446, 208Pb/204Pb was 37.50537.622, and the value of m was 9.129.19, indicating the
39、feature of normal lead (Wan Bo et al., 2006). Meanwhile on isotopes, d18OH2O of magnetite was +9.93+11.49, +10.73 at average, in the range of original magmatic water. dD of gas-liquid inclusions in magnetite was -80.9-115.3 relating to meteoric water. It suggested hydrogen-oxygen in magnetite source
40、d from volcanic gas erruption, but contaminated by meteoric water in the deposition process (Li Taide, 2002), and also indicated the minerogenetic fluid derived from magmatic water and meteoric water (Peng Shenglin et al., 1996). 2.3 Prospecting model Prospecting model of mineral deposit type can co
41、nsider from the following aspects: geological condition, history criteria for prospecting, geophysical criteria, geochemical criteria, remote sensing information criteria and surface criteria for prospecting.(1) Geological condition: tectonic setting: the Qiaoxiahala Fe-Cu-Au deposit located in the
42、Ertix mixing belt; rock association: basic volcanic rocks and pyroclastic rocks hosted the orebodies, and also intruded by later diorites; alteration in wall rocks: epidotization occurred closely to Fe orebodies and widely spreaded, carbonation was closely related to Cu-Au, and silication guided for
43、 Au (Ni Liang, 2004).(2) History criteria for prospecting:prospecting relic: the Qiaoxiahala Fe-Cu-Au deposit was found by Team 622 in Geological Bureau in 1955, and checked by Team 713 in 1958. In 1959, the Altay geological team finished the peripheral reconnaissance survey, and the geophysical tea
44、m denied its economic value after electric and magnetic survey. Later it was confirmed as a small-scale deposit by the Altay geological team after initial exploration. There were magnetite open pit relic by locals on the surface; written records: it was recorded in the regional report of Fuyun at sc
45、ale of 1:200 000 in 1978 as a small-scale Fe deposit and Cu occurrence. In recent years, Fe ore resources have reached 4620 000 t, Cu 31200 t and Au 1051 kg.(3) Geophysical criteria:gravity: the gravity anomaly in Qiaoxiahala was lineary consist with the tectonic striking as the high value of gravit
46、y; magnetic: TEM had low response value, high magnetic anomaly, middle-high electrical resistivity, and low polarization value; electrical method: in the northern part, it showed the lower polarization value and higher apparent electrical resistivity than those in the south.(4) Geochemical criteriai
47、n the region: Au, Cu and As presented the integrated anomaly associated with Cr, Ni and Co anomaly; in the mining area: taking No.II orebody in the eastern mining sector as an example, it was similar to the marine volcanism anomaly such as Co, Ni, and Cr occurring beneath the orebody, meanwhile it a
48、lso showed the similarity to hydrothermal mineralization with wide anomaly area, clear anomaly zoning and As and Sb anomaly beneath the orebody.(5) Remote sensing information criteria: until now, there is no remote sensing information about the Qiaoxiahala area.(6) Surface criteria for prospecting: there occurred magnetite outcrops in the eastern and western mining sectors in Qiaoxiahala.3 Prospecting significanceBased on the Palaeozoic minerogenetic region classification, the Qiaoxiahala Fe-Cu-Au deposit in Xinjiang located in the Paleo-Asian minerogenetic domainJunggar mine