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新疆和田透闪石集合体(软玉)矿带约1 300 km,是世界上最大的软玉矿带。除传统上认识的白玉、青玉和墨玉外,近年来在皮山县发现的一种软玉呈红棕色(糖玉),较为少见。该糖玉矿体产于镁质大理岩与石英闪长岩之间的镁质矽卡岩中,显示矿床为接触交代变质成因。通过镜下观察,发现该地区的糖玉主要由纤维状透闪石和极少量的杂质矿物组成。糖色杂质呈浸染状、叶片状、细脉状或沿裂隙分布,并形成于玉石成矿期或构造活动间歇。糖玉颜色与镁质大理岩中大量的红褐色氧化物有关。通过电子探针和X光粉晶衍射测试均表明糖玉主要由透闪石组成,并含少量伊利石、镁橄榄石、透辉石、磁铁矿等杂质矿物。软玉(细粒透闪石集合体)主要通过透闪石交代大理岩和透辉石形成。样品全岩的化学成分与透闪石晶体化学组成类似,全岩稀土配分模式显示Eu负异常(δEu=0.09~0.28)、LREE亏损、HREE平坦、整体稀土含量(1.94×10~(-6)~26.52×10~(-6))、Cr_2O_3(0.00~0.03×10~(-6))和Ni(0.00~0.01×10~(-6))含量低。成矿流体中氢同位素δD为-81.0‰~-84.0‰,均值为-82.25‰;δ~(18)O在330℃时为3.16‰~5.48‰。这些氢和氧同位素的数值显示形成软玉的成矿流体主要由岩浆热液、大气降水和大理岩脱出的CO2组成。这些糖玉的地球化学和成矿流体组成与已报道的典型的镁质矽卡岩矿床中软玉的组成类似。从透闪石集合体中选出的岩浆锆石年龄约456±7 Ma,这个年龄可以认为是形成该糖玉矿床年龄的上限。
The Hetian tremolite assemblage (Nephrite) ore belt is about 1,300 km and is the largest nephrite ore belt in the world. In addition to the traditionally recognized white jade, sapphires and black jade, in recent years in Pishan County found a nephrite was reddish brown (sugar jade), is relatively rare. The gluconite ore body is produced in magnesian skarn between magnesian marble and quartz diorite, indicating that the deposit is the origin of contact metasomatism. Through microscopic observation, it was found that the saccharin in the area mainly consists of fibrous tremolite and a very small amount of impurity minerals. Sugar-colored impurities were disseminated, leaf-like, fine veins or along the fissure distribution, and formed in the jade mineralization or tectonic activity interval. Sugar jade color and magnesium marble in a large number of reddish brown oxide related. Through the electron probe and the X-ray powder diffraction test, it shows that the jadeite mainly consists of tremolite and contains a small amount of impurity minerals such as illite, forsterite, diopside and magnetite. Nephrite (fine-grained tremolite aggregate) is mainly formed by tremolite dating to marble and diopside. The chemical composition of the whole rock samples is similar to that of tremolite crystals. The REE patterns of the whole rock show Eu negative anomalies (δEu = 0.09-0.28), LREE loss, flat HREE, and total REE content (1.94 × 10 -6) ~ 26.52 × 10 ~ (-6)), Cr_2O_3 (0.00 ~ 0.03 × 10 -6) and Ni (0.00 ~ 0.01 × 10 -6). The hydrogen isotope δD of ore-forming fluid is -81.0 ‰ ~ -84.0 ‰, with an average of -82.25 ‰; δ ~ (18) O is 3.16 ‰ ~ 5.48 ‰ at 330 ℃. The values of these hydrogen and oxygen isotopes show that the ore-forming fluids forming nephrite are mainly composed of magmatic hydrothermal fluids, atmospheric precipitation and CO2 escaped from marble. The geochemical and ore-forming fluid compositions of these gum jars are similar to those of the nephrite jade that has been reported for typical magnesian skarn deposits. The age of magmatic zircons from the tremolite assemblages is about 456 ± 7 Ma, which is considered to be the upper limit of age at which the dolomitic deposit is formed.