青海省东昆仑成矿带铁矿成矿规律与找矿方向研究
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Metallogenic Law and Prospect Direction of Iron Deposits in the East Kunlun Metallogenic Belt in Qinghai
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    摘要:

    东昆仑成矿带位于西域板块南缘活动带与华南板块接合部位,属昆祁秦缝合系的昆仑缝合带。区内由昆北、昆中及昆南三条呈近东西向到北西西向平行展布的区域深大断裂,构成东昆仑复杂的构造格局,由此划分出三大构造成矿单元,即东昆仑北带、中带、南带。这三条大断裂均为切穿地壳或岩石圈的区域性长期活动深大断裂,不仅构成各地质单元的边界和控制岩浆岩分布,也控制了东昆仑隆起、凹陷带沉积盆地及沉积建造的展布,与次级北西、北北西向和北东向断裂一起,把不同时代地层和部分岩体切割成规模不等的断块(条),同时不同级次的断裂构造作为成矿的导矿场和储矿场,为各类矿床的形成提供了良好的迁移通道和赋存空间。该区地层主要集中发育在前寒武纪、早古生界奥陶―志留纪、晚古生代石炭―二叠纪、中生界三叠纪及新生代几个时间段中。在区域分布上,昆中、昆北带出露地层较相近,昆南带与昆北和昆中带有显著差异,反映为不同地层分区。岩浆活动非常强烈而频繁,分布亦十分广泛,主要分布在昆仑山北坡断隆带和祁漫塔格地区,在昆仑山主脊形成著名的东昆仑山花岗岩带,昆仑山南坡出露少量中酸侵入岩。岩浆活动始于元古代,止于新生代,表现为间歇性的火山喷发与岩浆侵入频繁交替。岩性从基性、超基性到酸性均有出露。主要活动时代为加里东期、华力西期,其次为印支期、燕山期;兴凯期和前兴凯期主要以少量基性、超基性喷流活动。东昆仑成矿带是青海重要成矿带之一,东昆仑成矿带侵入岩、褶皱、断裂构造发育,岩浆活动频繁强烈,成矿地质条件十分优越,具有较大找矿潜力。该带也是青海省主要的工业矿床集中分布的地区,储量大,品位较高,矿产地集中,同时共伴生的多金属矿床也往往具有一定的规模。尤其是矽卡岩型和沉积变质型铁矿的绝大多数储量都集中在本带。铁矿床成因类型复杂多样,主要有与火山喷流沉积有关的喷流—沉积、热液交代变质改造型,沉积变质型和矽卡岩型,具备大型—超大型矿床的成矿条件。矿床多沿昆北、昆中和昆南深大断裂带分布,与次级构造及岩浆岩体关系密切。东昆仑西段是重要的大—超大型矿床找矿远景区,中段具有沉积变质型铁矿找矿前景,东段则是矽卡岩型铁矿床聚集区。该带铁矿资源量占全省的75.51%,铁矿共、伴生有用组分较多,可综合利用。接触交代型铁矿是目前开发的重点,此类型矿石质量较好,TFe品位一般在35%~55%,有害杂质硫、磷一般低于工业要求。特别是都兰、野马泉地区的铁矿多共、伴生有铅、锌、铜、金、银、锡、钴、铋、镉、硫铁矿等有益元素,需综合开发利用。由于共、伴生组分可综合利用,极大地提高了开发价值。

    Abstract:

    The East Kunlun metallogenic belt, located in the binding part between the south mobile belt of Xiyu block and South China block, belongs to the Kunlun suture belt of Qilian Qinling suture system. It consists of three regional deep seated faults trending from near EW to NWW in the south, middle and north of the Kunlun basin, and forms a complicated structure of this belt. Hence, three tectonic metallogenic units were divided: the north, middle and south belt of East Kunlun. All three fractures are the long lived regional deep fractures cutting through the earth's crust or lithosphere, which not only form the boundary of each geologic unit but control the distribution of magmatic rock, uplifting of East Kunlun, sedimentary basins and formation of depression zone. Along with secondary NW , NNW and NE trending faults, the three fractures cut strata of different era and some rock masses into fault blocks on various scales. Therefore, the fracture structures of different levels, which can be storage space for ore, provide excellent migration passages and occurrence space for formation of various ore deposits. The strata in the region were formed mainly in Precambrian, Ordovician Silurian, Carboniferous Permian, Triassic and Cenozoic Era. As for regional distribution, the outcrops in the middle and northern Kunlong belts are similar while there is significant difference between the south belt and other two belts. Magmatic activities were very strong and frequent, and are distributed extensively in fault uplift zone of the north slope of Kunlun Mountain as well as the Qimantage region, with the famous granite belt formed in the major ridge of Kunlun mountain and small amount of intermediate acid intrusive rocks exposed in the south slope. Lithological characters are shown as mafic, ultramafice and acid. The main active periods are Caledonian and Variscan, followed by Indosinian and Yanshanian, with minor mafic and ultramafic exhalative activities existing in Xingkai and Early Xingkai period. East Kunlun metallogenic belt is one of the most important metallogenic belts in Qinghai with advantageous geological conditions and great prospecting potential where structures of intrusive rock, fold and fracture are well developed as well as frequent and strong magmatic activities. Moreover, this belt is also the concentrated region of major industrial ore deposits in Qinghai with large reserves and high grade and concurrently paragenic and associated poly metallic deposit normally possess certain scale. In particularly most skarn type and sedimentary metamorphic iron ores are concentrated in this area. Genetic types of iron ore deposits in the East Kunlun metallogenic belt are complex, including exhalative sedimentary and pyrometasomatic metamorphism reformation type related to volcanic exhalative sedimentation, and sedimentary metamorphic and skarn types. Therefore, the belt is provided with metallogenic conditions for large or super large ore deposits. The ore deposits distribute mostly along the deep fractures of the north, middle and south of Kunlun Mountain and are closely connected with secondary structures and magmatic rock mass. The west of East Kunlun metallogenic belt is the important prospecting area for large ore deposits, the middle has prospecting potential of sedimentary metamorphic iron ores, and the east is regarded as the accumulation area of skarn type iron ore deposits. The resources of iron ores in this belt occupy 75.51% of the whole province and large quantity of useful components associated with iron deposits can be also utilized. The contact metasomatic iron deposits are the target for current exploration. The ores of this kind is excellent and the grade of TFe is between 35% and 55%, with low contents of sulphur and phosphorus (normally lower than industrial requirements). Especially in the Dulan and Yemaquan areas, the associated elements in iron depsotis, such as such as lead, zinc, copper, gold, silver, tin, cobalt, bismuth, cadmium, pyrite, etc. can be utilized, which greatly improves the development value.

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许长坤,刘世宝,赵子基,张梅芬,张开成,刘建华,詹发余,黄朝晖,张钟月,王红英,张文君,乔强.2012.青海省东昆仑成矿带铁矿成矿规律与找矿方向研究[J].地质学报,86(10):1621-1678.
XU Changkun, LIU Shibao, ZHAO Ziji, ZHANG Meifeng, ZHANG Kaicheng, LIU Jianhua, ZHAN Fayu, HUANG Chaohui, ZHANG Zhongyue, WANG Hongying, ZHANG Wenjun, QIAO Qiang.2012. Metallogenic Law and Prospect Direction of Iron Deposits in the East Kunlun Metallogenic Belt in Qinghai[J]. Acta Geologica Sinica,86(10):1621-1678.

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  • 收稿日期:2011-05-20
  • 最后修改日期:2012-02-12
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