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邦铺钼(铜)多金属矿床是冈底斯带新近发现的大型斑岩型矿床,矿区内发育大量不同类型、不同期次的侵入岩体。矿区南东方向接触带的铅锌矿床,尽管最早受到关注并进行开采,但研究程度却仍然相对较低。文章采用LA-ICP-MS锆石U-Pb测年和锆石Hf同位素、微量元素,首次对铅锌矿区内出露的含矿石英二长斑岩进行研究,23颗锆石206Pb/238U加权平均年龄为(15.43±0.12)Ma(MSWD=2.7,n=23),系中新世岩浆产物。在完成锆石测年后,同时对部分所测锆石进行了系统的Hf同位素原位分析,测得176Hf/177Hf值为0.282790～0.282913,εHf(t)变化范围为0.6～5.0,Hf同位素测试结果与亏损地幔地球化学储库的Hf同位素特征较为相似,表明石英二长斑岩的源区具亏损特征,但在岩浆演化过程中遭受了下地壳物质的混染。稀土元素结果显示轻稀土亏损,重稀土富集,明显的正Ce异常,Eu负异常,属典型的岩浆成因锆石。与前人对钼(铜)矿区的研究结果一致,故推断铅锌矿与钼(铜)矿为同一斑岩系统的产物。结合与区域上相邻的甲玛、驱龙矿床,该矿床显示出与甲玛、驱龙等超大型斑岩型矿床具有统一的地球动力学背景及深部岩浆活动。
The Bangpu molybdenum (copper) polymetallic deposit is a newly discovered large-scale porphyry deposit recently discovered in the Gangdise zone, where a large number of different types of rock intrusions have been developed. The lead-zinc deposits in the south-east contact zone of the mining area, despite their earliest attention and exploitation, are still relatively under-researched. In this paper, LA-ICP-MS zircon U-Pb zircon dating and zircon Hf isotopes and trace elements were used for the first time to study ore-bearing quartz porphyrites exposed in the lead-zinc mining area. The weighted average 206Pb / 238U of 23 zircons The age is (15.43 ± 0.12) Ma (MSWD = 2.7, n = 23), which is a Miocene magmatic product. After the zircon dating was completed, some of the zircons obtained were systematically analyzed by Hf isotope analysis. The results showed that the 176Hf / 177Hf values ranged from 0.282790 to 0.282913 and the εHf (t) ranges from 0.6 to 5.0. The Hf isotope test The results are similar to those of depleted mantle geochemical reservoirs, suggesting that the source region of quartz diopside porphyry has a depletion character but is contaminated by the lower crustal material during magmatic evolution. The result of REE shows the loss of LREE, the enrichment of REE, the obvious positive Ce anomaly and the negative Eu anomaly, belonging to the typical magmatic zircon. And the predecessors of the molybdenum (copper) mining area of the same results, it is concluded that the lead-zinc ore and molybdenum (copper) ore for the same porphyry system products. In combination with the adjacent Jiama and Qunlong deposits in the area, the deposit shows a unified geodynamic background and deep magmatic activity with superlarge porphyry deposits such as Jiama and Qunlong.