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赛什塘-日龙沟以铜为主的多金属矿田位于东昆仑与西秦岭的交接部位,分布有大量中酸性侵入体,与成矿作用有密切关系。通过对日龙沟锡多金属矿区花岗闪长岩LA-ICP-MS锆石U-Pb同位素和岩石地球化学研究,认为该岩体形成于中三叠世(230.7±1.5Ma),属于相对贫硅(Si O2含量为62.24%~63.67%)、偏碱(碱度率AR为1.73~1.88)、过铝(铝饱和指数A/CNK介于2.37~2.70之间)的花岗闪长岩。稀土元素总量较高(∑REE=111×10-6~164×10-6),稀土元素配分曲线呈轻稀土元素富集(LREE/HREE=9.83~16.95)的右倾曲线,(La/Yb)N介于16.5~34.32之间,Eu、Gd具有弱负异常(δEu=0.79~0.98,δGd=0.73~0.81),而Tb具有弱正异常(δTb=1.23~1.28)。微量元素显示,Rb、Ba、Th、U等大离子亲石元素相对富集,Nb、Ta、Dy、Y、Ho、Yb、Lu等高场强元素亏损。岩相学特征显示,岩体主要由斜长石、黑云母、石英及角闪石组成;镜下可见2组斜长石及包含结构。综合判断认为,日龙沟花岗闪长岩体属I型花岗岩,可能是二叠系中性火山岩部分熔融形成的。结合野外地质调查,初步认为赛什塘-日龙沟矿田具有2期成矿作用。
The Seishitang-Rilong ditch copper-dominated polymetallic ore field is located at the junction of the East Kunlun and the West Qinling. A large number of intermediate-acidic intrusions are distributed and are closely related to metallogenesis. Based on the LA-ICP-MS zircon U-Pb isotopic and geochemical studies of the granodiorite in the Zhilonggou tin polymetallic deposit, it is believed that this rock mass is formed in the Middle Triassic (230.7 ± 1.5Ma) Poor Si (62.24% -63.67% Si 2 O 4), Alkali (alkalinity AR 1.73-1.88), and Al (aluminum saturation index A / CNK between 2.37 and 2.70) . The total REEs (ΣREE = 111 × 10-6 ~ 164 × 10-6) and the REE curves are the right-angled curves of light rare earth elements enrichment (LREE / HREE = 9.83 ~ 16.95) ) N is between 16.5 and 34.32. Eu and Gd have weak negative anomalies (δEu = 0.79-0.98 and δGd = 0.73-0.81), while Tb has a weak positive anomaly (δTb = 1.23-1.28). Trace elements show that Rb, Ba, Th, U and other large ion lithophile elements are relatively enriched and Nb, Ta, Dy, Y, Ho, Yb, Lu and other high field strength elements are depleted. Petrographical features show that the rock mass is mainly composed of plagioclase, biotite, quartz and amphibole. There are two groups of plagioclase and inclusions in the microstructure. The comprehensive judgment shows that the Zhilonggou granodiorite is a type I granite probably formed by the partial melting of Permian neutral volcanic rocks. Combined with field geological survey, it is initially believed that the Seishitang-Rilonggou orefield has the second-stage mineralization.