论文部分内容阅读
九瑞矿集区成矿与燕山期中酸性侵入岩体关系密切,但对该区东雷湾矿床的地质地球化学研究还相对较少,对东雷湾矿区中酸性侵入岩(花岗闪长斑岩、石英闪长玢岩)及其铁镁质包体进行了系统的锆石U-Pb年代学、矿物化学、岩石地球化学和SrNd-Pb-Hf同位素研究,探讨其岩石成因.锆石LA-ICP-MS U-Pb定年表明:东雷湾中酸性侵入岩的成岩年龄为144.3~148.7 Ma,铁镁质包体的年龄为146.4~147.1 Ma,与寄主侵入岩花岗闪长斑岩的年龄一致,东雷湾侵入岩属准铝质范围,岩石的Mg~#较高(42.5~68.0,平均56.0),并具有较高的相容元素含量,富集轻稀土,Eu异常不明显,富集大离子亲石元素,亏损高场强元素,暗色铁镁质包体呈细粒结构,常见针状磷灰石和钾长石斑晶.东雷湾样品的Sr-Nd同位素组成变化范围较小,初始~87Sr/~86Sr比值位于0.706 4~0.7079,ε_(Nd)(t)值变化于-5.80~-3.31,t_(2DM)(Nd)为1.2~1.4 Ga,锆石ε_(Hf)(t)值为-15.9~-3.6.样品的~(206)Pb/~(204)Pb(t)、~(207)Pb/~(204)Pb(t)、~(208)Pb/~(204)Pb(t)值分别变化于17.333 3~18.260 0、15.513 5~15.6210、37.404 1~38.395 4之间,详尽的元素和同位素地球化学特征表明,东雷湾铁镁质包体是由拆沉的加厚下地壳发生部分熔融,并在其上升过程中与地幔物质发生相互作用,进而与花岗质岩浆混合过冷结晶形成的.该区侵入岩的形成很可能是因为加厚下地壳拆沉入软流圈地幔后发生部分熔融,熔体与地幔橄榄岩相互作用后在上侵的过程分别形成了铁镁质岩石和花岗质岩石.
However, the geo-geochemistry of the Dongleiwan deposit in this area is relatively small, and the mineralization of moderately acidic intrusive rocks (granodiorod spots Rock, quartz diorite porphyrite) and their magnesian inclusions, and systematically studied the zircon U-Pb geochronology, mineral chemistry, geochemistry and SrNd-Pb-Hf isotopes of zircons, The ICP-MS U-Pb dating indicates that the diagenetic age of the intermediate-acid intrusive rocks in Donglei Bay is 144.3-148.7 Ma and that of the magnesian inclusions is 146.4-147.1 Ma, which is similar to the age of the host intrusive granodiorite porphyry In the same area, the Donglei Bay intrusive rocks belong to the range of quasi-aluminum. The rocks have higher Mg ~ # (42.5 ~ 68.0, average 56.0) and higher content of compatible elements. The light rare earths are enriched, the Eu anomaly is not obvious, Set of large ion lithophile elements, loss of high field strength elements, dark-colored magnesian inclusions showed fine-grained structure, common acicular apatite and potassium feldspar phenocrysts.Deng Lei Bay samples Sr-Nd isotopic composition range The initial ~ 87Sr / ~ 86Sr ratios ranged from 0.706 4 to 0.7079, the ε_ (Nd) (t) values varied from -5.80 to -3.31, the t_ (2DM) (t) (204) Pb (t), ~ (207) Pb / ~ (204) Pb (t), ~ 208 Pb / ~ 204 Pb in samples from -15.9 to -3.6. (t) values change between 17.333 3 ~ 18.260 0,15.513 5 ~ 15.6210,37.404 1 ~ 38.395 4, respectively. The detailed elemental and isotopic geochemical characteristics show that the magnesia-encrustation in the Donglewan Bay is formed by the detachment of sediments The lower crust is partly melted and interacts with the mantle material during its ascending process and is then formed by the supercooled crystallization of the granitic magma.The formation of intrusive rocks in this area is likely due to the thickening of the lower crust After the asthenospheric mantle, partial melting occurred, and after the interaction between the melt and the mantle peridotite, the magmatic rocks and granitic rocks formed during the process of intrusion.