Abstract The Miocene Cuonadong leucogranites in the easternmost section of the Tethyan Himalaya, Southern Tibet, are characterized by two types of tourmaline. Tourmaline occurs as needle-like crystals in the two-mica ± tourmaline granites (Tur G) and large patches in the pegmatites (Tur P). Both the granite and the pegmatites yield Miocene ages (ca. 20 Ma) based on monazite U(-Th)-Pb dating, whereas 40Ar/39Ar geochronology of the coarse-grained tourmalines (Tur P) crosscut by pegmatite veins yielded an Eocene mini-plateau age of 43 ± 6 Ma. Major element concentrations of tourmaline indicate that both Tur P and Tur G belong to the schorl group with a magmatic origin, but trace elements such as V indicate that they are not cogenetic. Boron isotopes suggest that Tur P (average –9.76‰) was derived from typical crustal sources, whereas Tur G (average –7.65‰) contains relatively more mafic input. The capture of Eocene tourmaline by the Miocene leucogranites at Cuonadong suggests that the crustally derived Eocene magmatism may have occurred in the southern Tethyan Himalaya. Identification of the inherited magmatic tourmaline (Tur P), although not common, challenges the current application of tourmaline chemistry to the investigation of magmatic-hydrothermal systems.

中文翻译：

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中新世喜马拉雅无色花岗岩捕获的始新世岩浆碧玺

摘要 藏南特提斯喜马拉雅山最东段的中新世错那东白质花岗岩以两种碧玺为特征。电气石以针状晶体的形式出现在两云母 ± 电气石花岗岩 (Tur G) 和伟晶岩 (Tur P) 中的大片中。基于独居石 U(-Th)-Pb 测年，花岗岩和伟晶岩均产生中新世年龄（约 20 Ma），而伟晶岩脉横切粗粒碧玺 (Tur P) 的 40Ar/39Ar 年代学产生了始新世迷你- 43 ± 6 Ma 的高原年龄。电气石的主要元素浓度表明Tur P和Tur G都属于岩浆成因的schorl组，但微量元素如V表明它们不是共同成因的。硼同位素表明Tur P（平均–9.76‰）来自典型的地壳来源，而Tur G（平均–7.65‰）包含相对较多的镁铁质输入。措那东中新世白花岗岩对始新世碧玺的捕获表明，始新世地壳岩浆作用可能发生在特提斯喜马拉雅山南部。继承岩浆碧玺 (Tur P) 的鉴定虽然不常见，但对目前电气石化学在岩浆-热液系统研究中的应用提出了挑战。