The Udokan volcanic plateau differs from other volcanic regions of the Late Cenozoic volcanic province of East Asia in the high alkalinity of volcanic rocks, their potassium specialization, and rock composition, varying from melaleucytitis and melanephelinites to alkaline trachytes. The presence of alkaline-salic rocks in volcanic associations makes it unique to the province. The reasons that determined the unique magmatism of the Udokan plateau are considered. The data of geochemical and isotopic studies have shown that the moderately enriched magma of the mantle plume served as a melt source in the region. The initial melts were formed under conditions of garnet stability at low degrees of melting. This contributed to their enrichment in alkalis and other incompatible elements that is especially characteristic of ultramafic rocks. It is established that fractionation processes controlled the distribution of the trace elements in the rocks of volcanic associations. Deep differentiation of the magmas to alkaline trachytes occurred in the peripheral magma chambers. Here, magmas interacted with intracrustal waters, which led to a change in their oxygen isotopic composition. It is shown that contamination did not play a decisive role in the formation of lava plateau rocks.

中文翻译：

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晚新生代乌多坎火山高原岩浆来源及成岩条件

乌多坎火山高原与东亚晚新生代火山省的其他火山区的不同之处在于火山岩的高碱度、钾的特化和岩石成分，从白粉煤炎和黑斑岩到碱性粗面岩不等。火山群中碱性盐酸盐岩的存在使其成为该省独一无二的地区。考虑了决定Udokan高原独特岩浆作用的原因。地球化学和同位素研究数据表明，地幔柱的中等富集岩浆是该地区的熔融源。初始熔体是在石榴石稳定的低熔化度条件下形成的。这导致它们富含碱金属和其他不相容的元素，这是超基性岩的特征。已确定分馏过程控制了火山组合岩中微量元素的分布。外围岩浆房发生岩浆向碱性粗面体的深度分化。在这里，岩浆与地壳内水相互作用，导致其氧同位素组成发生变化。结果表明，污染对熔岩高原岩石的形成没有起决定性作用。