投稿时间：2015-03-20
修订日期：2016-03-07
网络发布日期：2016-04-29
中文摘要:阿尔金山喀腊大湾铁矿田位于北东向阿尔金走滑断裂与东西向阿尔金北缘断裂所夹持的地区。通过对已有铁矿床地质特征的研究,确认喀腊大湾地区铁矿床属于火山沉积型,因此,铁矿床具有成带状分布的特点,由八八铁矿床、八八西铁矿床、7914铁矿床、7915铁矿床、7918铁矿床和7910铁矿床共同构成喀腊大湾铁矿田。铁矿田范围内的地层以向北陡倾的单斜层为主,倾角75~88°;仅矿田西段八八西铁矿床、八八铁矿床一带沿走向发生直立陡倾伏(背斜)褶皱,可见地层和含矿岩系局部发生褶皱重复,形成铁矿带和含矿层位呈横卧"勾"状形态。铁矿床的产出严格受火山沉积岩系的特定层位和岩性控制,即铁矿床均产在卓阿布拉克组第三亚组第一岩性段(下部玄武岩段)的上部,其北侧为卓阿布拉克组第三亚组第二岩性段(大理岩段)标志层。与铁矿床关系密切的中基性火山岩锆石SHRIMP U-Pb年龄为(517±7) Ma, 显示该套火山沉积岩系中基性火山岩的时代为早古生代晚寒武世,因此,铁矿床的形成(火山-沉积)时代为晚寒武世。铁矿床形成之后主要发生2期地质构造事件,其一是发生了构造变形,致使铁矿体及含铁岩系均呈陡立状态,并形成褶皱;其二是中酸性岩浆侵入活动,使已经形成的铁矿床受到中酸性侵入岩的吞食破坏,并发生接触变质矽卡岩化改造。矽卡岩化改造时代为早奥陶世末期(辉钼矿铼锇等时线年龄480 Ma)。
Abstract:The Kaladawan iron orefield in Altun Mountains is located within the area sandwiched between the NE-striking Altun strike-slip faults and EW-striking northern Altun fault. Based on the study of the geological characteristics of the Kaladawan iron orefield,the authors hold that the iron deposit belongs to the volcanic-sedimentary type. So the deposits would be in zonal distribution in the orefield which consists of 6 iron deposits, i.e., Baba iron deposit, western Baba iron deposit, No. 7914 iron deposit, No. 7915 iron deposit, No. 7918 iron deposit and No. 7910 iron deposit dispersed from west to east. The strata in the field is monoclinal with mainly steep northward dipping at 75~88°. Nevertheless, in the western orefield, (i. e., in the range of Baba iron deposit and western Baba iron deposit), there occurs an anticline with vertical axial plane and steep dipping hinge, the strata and ore-bearing rock series reappear in the shape of lying down letter "L" due to the fold. The iron deposit is controlled by a special stratigraphic horizon of volcanic-sedimentary rock; in other words, all iron deposits occur in the upper part of intermediate-basic volcanic rocks which is the first member (lower basalt member) of the third sub-formation of Zhuo'abulake Formation. Nearby in the north, a marker band for iron deposit is exposed, which is the second member (marble member) of the third sub-formation of Zhuo'abulake Formation. The intermediate-basic volcanic rocks related to the iron deposit are about 517 Ma, as shown by zircon SHRIMP U-Pb dating, which suggests that the iron mineralization happened in late Cambrian epoch of early Paleozoic era. After the formation of iron deposits, there occurred two geological events: one was structural deformation that uplifted the strata and ore-bearing rock series steeply and resulted in folding, the other was intermediate-acid magmatic intrusive activity. The late event not only destroyed the iron deposit or devoured the iron orebodies but also caused contact metasomatic metamorphism (skarnization transformation of iron deposit). The skarnization transformation happened in late Ordovician epoch of early Paleozoic era at 480 Ma as shown by molybdenite rhenium-osmium isochron method.
keywords:geochemistry volcanic-sedimentary type origin metallogenic age Kaladawan iron orefield Altun Mountains
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中图分类号：P618.31
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基金项目:本文为"十一·五"、"十二·五"国家科技支撑计划重点项目(编号: 2006BAB07B02-04、2011BAB06B08-04)和地质矿产调查专项(编号: 1212011085043)资助的成果
引用文本：
陈柏林,李丽,祁万修,陈正乐,王永,郝瑞祥,李松彬,周永贵,蒋荣宝,韩凤彬,崔玲玲,赵树铭.2016.阿尔金山喀腊大湾铁矿田地质特征与形成时代[J].矿床地质,35(2):315~334CHEN BaiLin,LI Li,QI WangXiu,CHEN ZhengLe,WANG Yong,HAO RuiXiang,LI SongBin,ZHOU YongGui,JIANG RongBao,HAN FengBin,CUI LingLing,ZHAO ShuMing.2016.Geological characteristics and metallogenic age of Kaladawan iron orefield in Altun Mountains, northwestern China[J].Mineral Deposits35(2):315~334
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