Abstract The Cuonadong super-large Be-W-Sn rare metals deposits are hosted by skarns and marbles in the middle unit of the Cuonadong Dome. Rocks in the Cuonadong Dome record four major deformational events: D1, top-to-S thrust; D2, top-to-N extension; D3, approximately E–W extensional deformation; and D4, late collapse structural deformation. Skarns and/or marbles featured by the directional alignment of skarn minerals are exposed in garnet-staurolite-bearing mica schist, and are closely related to the deformed leucogranites and pegmatites. The boundary between leucogranites and skarns is locally gradual or sharp, which suggests that skarns and the deformed leucogranites resulted from the synkinematic magmatism and the strong activity of the STDS. Ar-Ar dating of muscovite from the deformed granites in the middle unit and biotite from granitic gneiss in the core yielded Ar-Ar plateau ages of 15.0 ± 0.2 Ma and 13.9 ± 0.4 Ma, respectively, which reflects the age of syntectonic magmatism, and the activity time of the STDS at the Cuonadong Dome, respectively. Ar-Ar dating of biotite from marble in the middle unit yielded Ar-Ar plateau age of 16.1 ± 0.2 Ma, which was interpreted as the formation age of the synkinematic skarns. Skarns in the Cuonadong Dome were related to the detachments and formed in association with the emplacement of leucogranites. Therefore, we suggest that the formation of the Cuonadong Be-W-Sn skarn deposit was contemporaneous with the intrusion of leucogranitic magma and the top-to-north extensional deformation along the STDS.

中文翻译：

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藏南新生代错那洞穹窿矽卡岩稀有金属成矿的构造和热年代学约束

摘要 错那东超大型Be-W-Sn稀有金属矿床赋存于错那东穹窿中部单元的矽卡岩和大理岩中。错那洞穹顶的岩石记录了四大变形事件：D1，顶向S推力；D2，top-to-N扩展；D3，近似 E-W 拉伸变形；D4，晚期倒塌结构变形。以矽卡岩矿物定向排列为特征的矽卡岩和/或大理岩出露在含石榴石星柱石的云母片岩中，与变形的无色花岗岩和伟晶岩密切相关。暗色花岗岩与矽卡岩的分界处局部渐进或尖锐，表明矽卡岩和变形的暗色花岗岩是同运动岩浆作用和STDS强烈活动的产物。中间单元变形花岗岩白云母和岩心花岗片麻岩黑云母的Ar-Ar定年结果分别为15.0±0.2Ma和13.9±0.4Ma，反映了同构造岩浆作用的年龄， STDS在错那洞穹顶的活动时间。中间单元大理岩黑云母的Ar-Ar定年结果为16.1±0.2Ma，这被解释为同运动矽卡岩的形成年龄。错那洞穹窿中的矽卡岩与拆离有关，与白花岗岩的就位有关。因此，我们认为错那东Be-W-Sn矽卡岩矿床的形成与白花岗质岩浆的侵入和沿STDS自上而北的伸展变形同时发生。