Amphibolitic and gabbroic rocks occur in Tarlang area in Chinese Altay. Amphibolites are metamorphosed products of mafic magmatic rocks (SiO 2 = 45.42% - 52.96%) and contain high Al 2O 3 (13.14% - 17.92%), Fe 2O 3 T (9.08% - 16.88%) and TiO 2 (0.82% - 3.23%) contents. The amphibolite samples show relatively flat REE patterns, without significant fractionations of REEs (La/Yb N = 1.53 - 1.79). These samples are depleted in HFSEs slightly, with slightly Ti-Nb-Ta negative anomalies, which suggest a subtle relation to subduction-related environment. The gabbroic samples (SiO 2 = 46.96% - 49.86%) have intermediate TiO 2 (0.38% - 1.89%) and relatively low K 2 O contents (K 2 O = 0.34% - 1.03%), belonging to subalkali rocks (Na 2 O > K 2 O). They have relatively high Al 2O 3 (15.0% - 20.81%), CaO (10.13% - 11.60%) and moderate MgO (7.3% - 8.3% ) contents. The gabbroic samples show two types of REE patterns. One is characterized by slight fractionation of REEs (La/Yb N = 1.10 - 1.67) and weak Eu anomalies (δEu = 1.03 - 1.10), while the other is enriched in LREE s (La/Yb N = 5.97 - 6.39), with significantly positive Eu anomalies (δEu = 1.31 - 1.44), which may reflect accumulation of plagioclase in the magma chamber. These gabbroic rocks all exhibit Ti-Nb-Ta troughs and Pb-Sr spikes, also implying a subduction-related origin. The 40Ar/ 39Ar spectrum of the gabbroic sample is simple and flat (plateau age of 266.9 ± 4.2Ma; isochron age of 261 ± 23Ma), indicating that its K-Ar isotopic system was not seriously disturbed by subsequent thermal events and may reflect the intrusion time of the gabbro. However, 40Ar- 39Ar analysis of the amphibolite give rise to a saddle-like spectrum, and its youngest plateau (297.3 ± 6.1Ma) probably reflects the last metamorphic event. The difference on age and geochemistry between the amphibolitic and gabbroic rocks implies that they probably represent different mafic magma. The protolith of amphibolites probably formed in a seamount near a subduction zone and subsequently accreated to the Altai. The gabbro exhibits subduction-releted characteristics and was coeval with transtensional movement in the Chinese Altai, probably reflecting a tectonic transition in the Permian.
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机译：两栖和辉长岩分布于中国阿尔泰的塔朗地区。角闪石是镁铁质岩浆岩的变质产物（SiO 2 = 45.42％-52.96％），并含有高含量的Al 2O 3（13.14％-17.92％），Fe 2O 3 T（9.08％-16.88％）和TiO 2（0.82％- 3.23％）的内容。角闪石样品显示相对平坦的REE模式，没有明显的REE分离（La / Yb N = 1.53-1.79）。这些样品在HFSE中略有耗尽，而Ti-Nb-Ta负异常略有减少，这暗示了与俯冲相关环境的微妙关系。辉长岩样品（SiO 2 = 46.96％-49.86％）具有中等TiO 2（0.38％-1.89％）和相对较低的K 2 O含量（K 2 O = 0.34％-1.03％），属于碱下岩石（Na 2 O> K 2 O）。它们具有较高的Al 2O 3（15.0％-20.81％），CaO（10.13％-11.60％）和中等的MgO（7.3％-8.3％）含量。辉长岩样品显示两种类型的REE模式。一种特征是稀土元素的轻度分级（La / Yb N = 1.10-1.67）和弱的Eu异常（δEu= 1.03-1.10），而另一种则富含LREE s（La / Yb N = 5.97-6.39），其中显着的正Eu异常（δEu= 1.31-1.44），这可能反映了岩浆室内斜长石的堆积。这些辉长岩均具有Ti-Nb-Ta槽和Pb-Sr尖峰，也暗示了与俯冲有关的成因。辉长岩样品的40Ar / 39Ar谱图简单而平坦（高原年龄为266.9±4.2Ma;等时年龄为261±23Ma），表明其K-Ar同位素系统并未受到随后的热事件的严重干扰，并可能反映了长颈鹿的入侵时间。然而，对角闪石的40Ar-39Ar分析产生了鞍状光谱，其最年轻的平稳期（297.3±6.1Ma）可能反映了最后的变质事件。两性和辉长岩之间的年龄和地球化学差异意味着它们可能代表不同的镁铁质岩浆。角闪石的原生岩可能在俯冲带附近的海山中形成，随后被阿尔泰生化。辉长猴具有俯冲消减的特征，与中国阿尔泰地区的张性运动同时期，可能反映了二叠纪的构造过渡。
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