The paper reports the isotope-geochronological and petrological-geochemical studies of the Pliocene moderately-acid volcanism of the Akhalkalaki Plateau in the central part of the Lesser Caucasus (Javakheti highland, Georgia). K-Ar dating showed that young dacitic lavas and pyroclastic rocks were formed in the mid-Pliocene (3.28 ± 0.10 Ma) in relation with the explosive–effusive eruptions of small composite volcanic cones and formation of minor extrusive domes confined mainly to the eastern margin of the region. Isotope-geochronological data in the combination with results of structural drilling indicate that the considered short-term pulse of the volcanic activity occurred during a short gap between two phases of the Pliocene–Early Pleistocene mafic magmatism widespread within the Akhalkalaki plateau. The studied Pliocene dacites were erupted at the post-collisional stage of the evolution of the Lesser Caucasus, but bear petrological-geochemical affinity of adakitic series. They are characterized by the steady presence of amphibole phenocrysts, the elevated contents of Sr, Ba, LILE and the lowered contents of Y, Nb, Ta, and HREE, and have depleted Sr isotopic composition (⁸⁷Sr/⁸⁶Sr < 0.7045). Analysis of petrogenetic models earlier proposed to explain the generation of adakite-like magmas in the modern collision zones showed that the origin of the Pliocene dacitic lavas of the Akhlkalaki plateau is best described by the crystallization differentiation of water-saturated calc-alkaline basaltic melts with removal of common mafic rock-forming minerals (first of all, amphibole and pyroxene) and accessory phases (apatite, titanite, Ti-magnetite) as cumulus minerals. Crustal assimilation of evolved magmas only insignificantly contributed to the petrogenesis of the dacites.

中文翻译：

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现代大陆碰撞带中类似于Adakite岩浆的起源：Akhalkalaki熔岩高原（爪哇高地，小高加索地区）的上新世大新世火山作用的证据。

这篇论文报道了小高加索中部（爪哇岛高地）Akhalkalaki高原上新世中酸性火山岩的同位素-地质年代学和岩石地球化学研究。K-Ar测年表明，上新世中期（3.28±0.10 Ma）形成了年轻的达吉斯熔岩和火山碎屑岩，这与小型复合火山锥的爆发性喷发喷发和主要局限于东部边缘的较小的挤压穹顶形成有关。该地区。同位素-地质年代学数据与结构钻探结果的结合表明，火山活动的短期脉动发生在阿赫哈拉拉基高原上广泛分布的上新世—早更新世铁磁质岩浆作用的两个阶段之间的一个短暂间隙内。所研究的上新世新生代在小高加索演化的碰撞后阶段爆发，但具有adakitic系列的岩石地球化学亲和力。它们的特征是稳定存在闪石斑晶，Sr，Ba，LILE的含量升高以及Y，Nb，Ta和HREE的含量降低，并且Sr同位素组成已经耗尽（⁸⁷ Sr / ⁸⁶ Sr <0.7045）。较早提出的岩石成因模型分析可以解释现代碰撞带中的白云石样岩浆的生成，结果表明，Akhlkalaki高原上新世达吉特熔岩的起源最好用含水饱和的钙碱性玄武岩熔体的结晶分化来描述。去除常见的镁铁质成岩矿物（首先是闪石和辉石）和副相（磷灰石，钛矿，钛磁铁矿）作为积垢矿物。演化的岩浆的地壳同化作用对胎儿的成岩作用微不足道。