Abstract—

The age and geodynamic position of the volcanic source of the Upper Jurassic–Lower Cretaceous deposits of Western Chukotka were determined. Products of synchronous volcanism were revealed by detailed lithological studies. Following sedimentological analysis results we established an admixture of pyroclastic material in the Oxfordian‒Kimmeridgian deposits of the Chukchi microcontinent, indicating the effect of synchronous volcanism on sedimentation. It was shown that the source of pyroclastic material was the intraoceanic Kulpolney island arc, which existed in the northern part of the Proto-Arctic Ocean.The accumulation of the Tithonian‒Valanginian deposits occurred in the back-arc basin at the edge of Chukotka microcontinent. Characteristics of the Tithonian‒Berriasian sandstones are given, which contain significant proportion of ash material in the matrix, as well as lithoclasts and monomineral grains of volcanic origin, predominant in the clasts. With the use of geochemical analysis of volcanic pebbles, the presence of the differentiated series from basaltic andesites to rhyolites in the volcanic source is proved. The suprasubduction origin of the volcanic source is established. The cessation of volcanic activity in Valangin era is confirmed by lack of presence of synchronous pyroclastic material and an insignificant amount of volcanic clasts in Valanginian sandstones. The obtained data of U‒Pb isotope dating of zircons isolated from the Tithonian‒Valanginian sandstones and andesite pebbles of the Tithonian conglomerates made it possible to determine the time for the existence of suprasubduction volcanism on the Chukotka margin in the period of 150‒140 Ma.

中文翻译：

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侏罗纪至白垩纪早期楚科奇火山地带的超生火山作用（俄罗斯，北极地区）

摘要—

确定了楚科奇西部上侏罗统-下白垩统火山岩源的年龄和地球动力学位置。详细的岩性研究揭示了同步火山作用的产物。根据沉积学分析结果，我们在楚科奇州微大陆的牛津-基米底纪沉积物中建立了火山碎屑物质的混合物，表明了同步火山作用对沉积的影响。结果表明，火山碎屑物质的来源是北冰洋内部的库尔波尼岛弧，存在于北冰洋的北部，铁丘尼安-瓦朗吉尼沉积物的堆积发生在楚科奇微大陆边缘的后弧盆地中。 。给出了ththonian‒berriasian砂岩的特征，它们在基质中包含大量的灰分物质，以及碎屑中主要是火山碎屑碎屑和火山成因的单矿物颗粒。通过对火山卵石的地球化学分析，证明了火山源中存在玄武岩安山岩到流纹岩的差异系列。确定了火山源的超俯冲起源。Valangin时代火山活动的停止是由于缺乏同步火山碎屑物质的存在以及Valanginian砂岩中火山碎屑的数量微不足道。