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西藏多龙矿集区地堡铜(金)矿位于班公湖—怒江缝合带北侧,羌塘地块南缘,是多龙矿集区中具有较好找矿前景的斑岩—浅成低温热液矿床。本文首次对地堡含矿斑岩进行LA-ICP-MS锆石U-Pb测年、微量元素和Hf同位素分析。含矿斑岩23个锆石点测试,获得锆石~(206)Pb/~(238)U加权平均值年龄为122.0±2.5Ma(MSWD=0.34),与多龙矿集区成矿岩浆活动时限一致,是多龙矿集区的重要组成部分。锆石微量元素特征揭示地堡含矿斑岩中锆石为岩浆锆石,锆石Ti温度计计算出其结晶温度为663~850℃,平均为765℃,其岩浆源区可能经历了水饱和条件下的部分熔融作用。Hf同位素分析结果表明,地堡含矿斑岩锆石n(~(176)Hf)/n(~(177)Hf)值相对较高,为0.282726~0.283054,ε_(Hf)(t)为1.1~12.6,均为正值,其物质来源有幔源组分的加入,可能为壳幔混源的新生下地壳。
The Burundi copper (gold) deposit, located in the northern part of the Bangong Lake-Nujiang suture zone and the southern margin of the Qiangtang block, is a porphyry with a good prospecting potential in the Duolong ore district - light into low temperature Hydrothermal deposit. In this paper, LA-ICP-MS zircon U-Pb dating, trace elements and Hf isotope analysis of the bunker-bearing porphyries are firstly carried out. The results show that the zircon Pb ~ (238) Pb / ~ (238) U weighted average ages of 122.0 ± 2.5Ma (MSWD = 0.34) were obtained from 23 zircons ore- The same time limit is an important part of the multi-ore mining area. The trace element characteristics of zircon reveal that the zircon in the bunker porphyry porphyry is zircon magma. The zircon Ti thermometer calculates the crystallization temperature at 663 ~ 850 ℃ with an average of 765 ℃. The magma source may have experienced water saturation Part of the melting effect. The results of Hf isotope analysis show that the value of n (~ (176) Hf) / n (~ (177) Hf) in the bunker porphyry porphyry is relatively high from 0.282726 to 0.283054 and the ε_ (Hf) 12.6, both of which are positive values. The source of mantle-derived components is probably derived from the crust-mantle mixed sourced lower crust.