Geological characteristics and metallogenesis of the shilu Fe-ore deposit in Hainan Province, South China
Geological characteristics and metallogenesis of the shilu Fe-ore deposit in Hainan Province, South China
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DOI：
10.1016/j.oregeorev.2013.01.015
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发表时间：
2013-09
影响因子：
3.3
通讯作者：
Deru Xu;Zhilin Wang;Jianxin Cai;Chuanjun Wu;N. Bakun-czubarow;Li Wang;Huayong Chen;M. Baker
中科院分区：
文献类型：
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作者：
Deru Xu;Zhilin Wang;Jianxin Cai;Chuanjun Wu;N. Bakun-czubarow;Li Wang;Huayong Chen;M. Baker
海南省石碌铁矿存款是一个大型的富赤铁矿存款矿床，已探明储量超过4.6亿吨铁矿51%，4.07亿吨钴0.29%和6.65亿吨铜矿1.18%。该存款主要是托管在中新元古代（约。石路群为一套浅变质硅质岩和沉积碳酸盐岩，保存了原始的沉积结构和构造。石碌群由6个岩石地层序列组成，其中含有条带状铁建造（BIFs），当地称之为角闪岩伊变岩。富铁矿主要赋存于第六层序中段的辉石-角闪石岩中，而钴铜矿主要赋存于第六层序下部的条带状或不纯白云岩中，位于铁矿层以下30- 60 m处。这些矿石主要呈透镜状或片状，沿NW-SE向复向斜的槽和/或翼向槽的过渡带产出，一般呈条带状或块状构造，具鳞片变晶、隐晶质或微晶结构。偶见的鲕粒和变余砂屑结构，表明石碌铁多金属矿为原始沉积物源。至少有两个阶段的变形和相关的变质作用可以识别。D1变形对应于一个北西-南东向复向斜，并伴有区域绿片岩相变质作用。D2变形记录了早期NW-SE向的收缩（D2 a），随后隆起并伴有明显的矽卡岩化（D2 b），最后过渡到近E-W向的伸展（D2c），导致了不同程度的褶皱、断裂和矿物重结晶。矿石和容矿岩石的放射性同位素分析记录了3个变质年龄，其中Sm-Nd等时线年龄为830± 16 Ma和212.9±6.6Ma，40 Ar-39 Ar坪年龄为132.08±1.57Ma，分别对应于D1、D2 b和D2c。结合以前的U-Pb SHRIMP年龄约。960米，1300 Ma和同位素地球化学数据（Xu et al.，2009），以及其他区域变质事件，提出了一个更新的四阶段成矿模式：（1）BIF型矿源层之间的沉积约。830 ~ 960 Ma变质沉积型存款的形成。830- 360 Ma之间的D2变形对存款的细化作用。250和210 Ma之间的岩浆热液叠加成矿阶段。130和90 Ma。因此，石碌铁矿存款可视为一个更好的构造和热液改造和再富集的BIF型矿床存款。
The Shilu Fe-ore deposit, a large-scale hematite-rich ore deposit in Hainan Province, South China, contains proven reserves of over 460Mt Fe-ore at 51% FeO, 4.07Mt Co-ore at 0.29% and 6.65Mt Cu-ore at 1.18%. The deposit is largely hosted within the Meso- to Neoproterozoic (ca. 0.85–1.30Ga) Shilu Group, a suite of metamorphosed neritic siliciclastic rocks and sedimentary carbonates, in which original sedimentary textures and structures are elegantly preserved. The Shilu Group, which hosts banded iron formations (BIFs), locally called amphibolitic itabirites, comprises six lithostratigraphic sequences. Fe-rich ores mainly reside in pyroxene–amphibole rocks of the middle sixth sequence, whereas the Co–Cu ores are located about 30–60m below the Fe-ore horizons and are primarily hosted by banded or impure dolostones of the lower sixth sequence. These ores are present mainly as lens-like or sheet-like bodies trending along troughs and/or transitional zones from limbs to troughs of the NW–SE trending synclinorium, and generally show banded or massive structures with lepidoblastic, cryptocrystalline or microcrystalline textures. Occasional oolitic and blastopsammitic textures are present, indicating an original sedimentary source for the Shilu Fe-polymetallic ores. At least two stages of deformation and associated metamorphism can be recognized. D1deformation corresponds to a NW–SE trending synclinorium with associated regional greenschist facies metamorphism. D2deformation records an early NW–SE orientated contraction (D2a), followed by doming with apparent skarnization (D2b) and finally transitional to a nearly E–W orientated extension (D2c), resulting in various amounts of folding, faulting and mineral recrystallization. Radiogenic isotopic analyses conducted on ores and host rocks record three metamorphic ages, including two Sm–Nd isochron ages of 830±16Ma and 212.9±6.6Ma, and a40Ar–39Ar plateau age of 132.08±1.57Ma corresponding to D1, D2b, and D2c, respectively. Combined with previous U–Pb SHRIMP ages from ca. 960Ma to ca. 1300Ma and isotopic geochemical data (Xu et al., 2009), as well as other regional metamorphic events, an updated four-stage metallogenic model is proposed here: (1) deposition of the BIF-type ore source horizons between ca. 830 and 960Ma, (2) formation of a metamorphic sedimentary-type ore deposit from ca. 830–360Ma, (3) refinement of the deposit due to D2deformation between ca. 250 and 210Ma and (4) superposed mineralizing stage formed by magma-related hydrothermal fluids between ca. 130 and 90Ma. The Shilu Fe-ore deposit can thus be better regarded as a structurally and hydrothermally reworked and re-enriched BIF-type ore deposit.