西藏列廷冈铁多金属矿侵入岩锆石U_Pb定年、Hf同位素组成及其地质意义

Zircon U_Pb dating and Hf isotopic composition of intrusions in the Lietinggang iron polymetallic deposit in Tibet and their geological significance

西藏列廷冈铁多金属矿床位于冈底斯-念青唐古拉岩浆弧北缘,是冈底斯北缘Pb-Zn-Ag-Cu-Fe多金属成矿带上典型的铁多金属矿床,与成矿关系最为密切的岩体为花岗闪长岩和花岗斑岩。采用锆石LA-ICP-MS对花岗闪长岩和花岗斑岩进行了定年,结果显示花岗闪长岩的成岩年龄为58.69±0.68 Ma,花岗斑岩成岩年龄为60.69±0.98 Ma。与加拉普铁多金属矿、沙让钼矿、亚贵拉铅锌银矿等冈底斯-念青唐古拉岩浆弧上其它矿床的对比分析表明,这一系列矿床受印度-欧亚大陆碰撞过程中地幔的岩浆底侵作用影响,形成于印度-亚洲大陆碰撞早期。列廷冈锆石的Lu-Hf测试结果显示岩体的εHf（t）值为-3.01-3.0,Hf二阶段模式年龄742-1 322 Ma,表明岩浆具有壳幔混源的特点。结合列廷冈的目前勘探情况,认为在区域的铁多金属矿中,深部的Cu、Pb、Zn矿产将是今后勘查方向。

Lying in the north of Gandise-Nyainqentanglha magmatic arc, the Lietinggang deposit is a typical iron polymetallic deposit in the Gandise Pb-Zn-Ag-Cu-Fe metallogenic belt. Granodiorite and granite porphyry have a close metallogenic relationship with the Lietinggang deposit. The authors conducted LA-ICP-MS zircon dating of the granodiorite and granite porphyry, which yielded monzonitic granite age of 58. 69 ± 0. 68 Ma and granite porphyry age of 60. 69 ± 0. 98 Ma. The Lietinggang deposit was compared in metallogenic background with the ore deposits in Gandise-Nyainqentanglha magmatic arc, such as Jialapu, Sharang and Yaguila. With the underplating of mantle-derived magma during India-Eurasin continental collision, the series of deposits were formed in the main collision period. The zircon Lu-Hf of zircons from the Lietinggang deposit have εHf（ t） values ranging from- 3. 01 to 3. 0, and tDM2 ages of Hf between 742 and 1 322 Ma, suggesting that the m agm a w as from the m antle and the crust. The exploration achievem ents of the Lietinggang deposit show that the exploration of the iron polymetallic deposits in this region should be focused on the prospecting for Cu,Pb,Zn resources in the depth.