伊犁地块航磁异常与石炭纪铁矿床成因  

The regional aeromagnetic features and genesis of iron deposits in Yili terrane,western Xinjiang

作　　者：闫晓兰 

机构地区：[1]新疆维吾尔自治区矿产资源储量评审中心,乌鲁木齐830001

出　　处：《地球物理学进展》2014年第1期346-354,共9页Progress in Geophysics

摘　　要：研究表明,西天山大中型富铁矿床主要赋存于伊犁石炭纪弧后盆地,铁的成矿应与早石炭世海相火山诱发的熔流体喷溢与热液交代密切相关,且盆地建造制约矿化类型及其分布.区域航磁测量获得了近东西走向的高磁异常带和北西向、东西向的低磁异常带相间分布的格局,磁场梯度变化较大,客观反映了不同构造单元中地壳物质组分的明显差异,且很好地反映了阿吾拉勒铁矿带的区域分布特点.赋存于大哈拉军山组熔岩-火山碎屑岩建造中的铁矿床主要定位于火山机构断裂系中,大多与容矿火山岩系呈不协和接触关系,其产状取决于矿床在火山机构/火山穹窿中所处的具体位置,成矿物质主要来源于火山晚期高温熔流体和岩浆热液;而赋存于伊什基里克组的铁矿床主要属于化学沉积铁矿,其定位和规模主要受控于水下沉积洼地的古地貌特征,因而它们大多与上下盘地层呈整合接触关系.因此,伊犁盆地石炭纪海相火山岩建造与海相火山-沉积建造之间的差异性,很可能是控制不同类型矿床形成与定位的第一要素.The newly discovered medium- to large-sized iron deposits in western Tianshan, Xinjiang are mainly distributed within the Yili Carboniferous back-arc basin. The formation of most major iron deposits were intimately linked with Early Carboniferous marine volcanic rocks （ hosted by the Dahalajunshan Fro. ）, but some other deposits were genetically relatedto chemical deposition of iron and silica from seawater in Late Carboniferous time （hosted by the Yishijilike Frn. ）. The regional aeromagnetic surveys turned out a perfect response to the iron deposit distribution in the region. The iron deposits hosted within volcanic-volcaniclastic rocks ofthe Dahalajunshan Fm. were chiefly localized in the ring and radiate faults of crater structures and formed by ore-magma and/or high- temperature volcanic hydrothermal fluids, thus they are not concert with the surrounding volcanic strata in their orientations. The deposits hosted within the sedimentary rocks ofthe Yishijilike Fro. are chemically precipitated along with other sediments from the surrounding seawater, therefore they are conformable with the hosting stratigraphy and controlled by paleo-topography of the basin. However, overprinting by Sedex-type mineralization on these sedimentary iron deposit cannot be totally precluded. It is suggested that the differences between the marine volcanic rock package and sedimentary rock package might be the principal and crucial factor in controlling the generation and localization of the iron mineralization in the regiorL

关 键 词：新疆 伊犁地块 区域航磁异常 石炭纪铁矿床成因 时空分布规律 

分 类 号：P631[天文地球—地质矿产勘探]