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多龙矿集区北侧的究浅西铜金矿床与早白垩世究浅西岩体有关,该岩体主要岩性为石英二长斑岩,LA-ICP-MS方法测得石英二长斑岩锆石206 Pb/238 U年龄加权平均值为120±1 Ma(MSWD=1),属于早白垩世,与扎普-多不杂岩浆弧内的普让(116±2 Ma)、青草山(122±1 Ma)、多不扎(121.6±2.0Ma)以及波龙(119~120 Ma)等岩体侵位时间基本一致。该岩体含角闪石、黑云母、磁铁矿等富铁镁质矿物,无堇青石、白云母等富铝矿物,高SiO_2(63.66%~67.12%),高K_2O(43.60%~4.65%),总碱(K_2O+Na_2O)含量高(7.94%~8.96%),低Al_2O_3(1.83%~2.33%),中等CaO含量(2.94%~4.15%)的特征。里特曼指数(σ43)为2.71~3.31,A/CNK值为:0.84~0.93。在CIPW标准矿物计算中,出现了透辉石而未出现刚玉。在ACF图解上,样品落于I型花岗岩范围内,Th、Y与Rb,Pb与SiO_2含量正相关,P_2O_5与SiO_2含量负相关,表明究浅西石英二长岩为高钾钙碱性准铝质的I型花岗岩。稀土元素和微量元素配分曲线均位于羌塘南缘主要早白垩世花岗岩的范围内。球粒陨石配分曲线具有向右倾斜的“海鸥”形特征,轻稀土曲线较陡,重稀土曲线较平缓,具明显的Eu异常,基本无Ce异常。原始地幔标准化蛛网曲呈像右倾斜的起伏曲线。相对富集Rb、Th、U、K等大离子亲石元素,相对亏损Nb、Ta、Zr、Hf、P、Ti等高场强元素。具有较典型的岛弧岩浆岩的地球化学特征。结合区域地质演化综合分析认为,究浅西花岗岩为班公湖-怒江洋壳北向俯冲的背景下,在温度较高的条件下地壳物质发生部分熔融作用的产物。
The shallow As-Cu-Cu gold deposit on the northern side of the Duolong ore district is related to the Early Cretaceous study of the West-West pluton. The main lithology of this rock mass is quartz-dimpled porphyry. The LA-ICP-MS The 206 Pb / 238 U zircon ages weighted average of 120 ± 1 Ma (MSWD = 1) belongs to the Early Cretaceous and belongs to Early Cretaceous. (122 ± 1 Ma), unconsolidated (121.6 ± 2.0 Ma) and Paleo (119 ~ 120 Ma). The rock contains hornblende, biotite, magnetite and other iron-rich magnesia minerals, without cordierite, muscovite and other aluminum-rich minerals, high SiO_2 (63.66% ~ 67.12%), high K_2O (43.60% ~ 4.65% ), Total K 2 O + Na 2 O content (7.94% ~ 8.96%), low Al 2 O 3 (1.83% ~ 2.33%) and medium CaO content (2.94% ~ 4.15%). The Rittman Index (σ43) was 2.71-3.31, and the A / CNK was 0.84-0.93. In the CIPW standard mineral calculation, diopside appears without the presence of corundum. In the ACF plot, the samples fall within the range of type I granites. Th, Y and Rb, Pb and SiO 2 contents are positively correlated, while P 2 O 5 and SiO 2 contents are negatively correlated, indicating that the shallow Paleocrystalline quartz montenite is a high-K calc-alkaline Al I-type granite. The distribution curves of REEs and trace elements are all located within the range of the main Early Cretaceous granites on the southern margin of Qiangtang. The distribution curve of chondrite has a “sea-gull” shape tilted to the right, the curve of light rare earth is steep, the curve of heavy rare earth is relatively flat, with obvious Eu anomaly and little Ce anomaly. The original mantle normalized arachnoid curve shows a right-angled undulating curve. Relatively enriched in large ion lithophile elements such as Rb, Th, U, K and relatively depleted in field elements such as Nb, Ta, Zr, Hf, P and Ti. With more typical island arc magmatic rocks geochemical characteristics. According to the comprehensive analysis of regional geological evolution, it is considered that the shallow western granite is the product of partial melting of crustal material under the condition of high temperature in the northward subduction of the Bangong-Nujiang oceanic crust.