Abstract

The Sikhote-Alin Orogen in the southeast of Russia is a collage of geological terranes of various age and tectonic origin, which formed along the East Asian continental margin as a result of the Jurassic–Early Cretaceous subduction of the Pacific oceanic plates. The Jurassic Samarka accretionary complex (AC) and the Early Cretaceous Zhuravlevka turbidite basin in the southern part of the orogen are considered indicators of subduction continental margin and transform plate boundary regimes, respectively. The regime conversion was assumed at the end of the Jurassic, when subduction stopped. Our biostratigraphic study of radiolarians from siliceous and fine-clastic sedimentary rocks has revealed the latest oceanic deposits and the youngest, Early Cretaceous fragment of the Samarka AC in its less studied northeastern part, which is ascribed to the Anuy tectono-stratigraphic element. The well-preserved radiolarians allow accurate dating of cherts, siliceous mudstone, and mudstone. This and other available biostratigraphic data allow the reinterpretation of the stratigraphy of the accreted oceanic sedimentary rocks. The refined stratigraphy is interpreted as a subsequent change in depositional settings on an oceanic plate, which moves to the convergent plate margin. Cherts accumulated in an oceanic pelagic zone from the Middle Triassic to the Late Jurassic (Early Oxfordian). Siliceous mudstone were deposited in a hemipelagic zone in the early Oxfordian–middle Tithonian. Mudstone and siltstones deposited on an external slope of a deep trench in the late Tithonian–Berriasian. The sandy deposits were deposited in an axial part of the trench in the early Valangian, which best corresponds to the timing of accretion. Thus recognized early Valanginian accretion episode shows that subduction underneath the continental margin lasted longer than previously suggested. The onset of the transform continental boundary regime occurred later, probably, in the late Valanginian. This further details the Mesozoic evolutionary scenario, which was previously proposed for the Sikhote-Alin segment of the East Asian continental margin. We also refine the tectonic zonation and evolution of the Samarka AC.

中文翻译：

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Anuy区域的沉积，构造带化和Samarka增生复合体的演化：东亚大陆边缘Sikhote-Alin段的演化方案详细信息

摘要

俄罗斯东南部的Sikhote-Alin造山带是不同年龄和构造起源的地质地貌的拼贴画，这些地貌沿太平洋板块的侏罗纪-早白垩世俯冲作用沿东亚大陆边缘形成。造山带南部的侏罗纪撒马尔加增生复合体（AC）和早白垩世Zuravlevka浊积盆地被认为是俯冲大陆边缘和转换板块边界制度的标志。俯冲停止后，侏罗纪末期进行了政权转换。我们对来自硅质和细碎屑沉积岩的放射虫的生物地层学研究表明，在其研究较少的东北部，撒马尔罕AC的最新海洋沉积物和最年轻的白垩纪早期碎片，归因于Anuy构造地层要素。保存完好的放射虫可以准确地对，石，硅质泥岩和泥岩进行测年。这些和其他可用的生物地层数据可以重新解释增生的海洋沉积岩的地层学。精细的地层被解释为大洋板块上沉积环境的后续变化，该变化移动到会聚板块边缘。从中三叠纪到侏罗纪晚期（牛津早期），石在海洋中上层带聚集。硅质泥岩沉积在牛津早期至中提通期的半海相带中。泥岩和粉砂岩沉积在Tithonian-Berriasian晚期深沟的外坡上。沙质沉积物沉积在瓦朗纪早期的海沟的轴向部分，最好与吸积的时间相对应。因此，公认的瓦朗吉尼亚早期增生事件表明，大陆边缘下的俯冲作用持续的时间比以前建议的要长。转换大陆边界体制的发生可能发生在瓦朗吉尼后期。这进一步详细说明了中生代演化情景，该情景先前是针对东亚大陆边缘的锡克特-阿林线段提出的。我们还完善了撒马尔加AC的构造带和演化。这进一步详细说明了中生代演化情景，该情景先前是针对东亚大陆边缘的锡克特-阿林线段提出的。我们还完善了撒马尔加AC的构造带和演化。这进一步详细说明了中生代演化情景，该情景先前是针对东亚大陆边缘的锡克特-阿林线段提出的。我们还完善了撒马尔加AC的构造带和演化。