The paper presents a new geological, geochronological, geochemical and Nd isotopic data on the latest Paleoproterozoic dolerite sills, exposed in the Biryusa inlier of the southern Siberian craton among the sandstones of sedimentary sequence traditionally suggested as Neoproterozoic. One dolerite sill yielded U-Pb (ID-TIMS) baddeleyite concordia age of 1613 ± 5 Ma, which interpreted as time of their emplacement. New geochronological data allow reconsider previously reported Neoproterozoic age of sedimentary sequence hosting dolerite sills studied and suggest for them at least Paleoproterozoic age. The dolerites correspond to subalkaline and alkaline tholeiitic basalts and less often subalkaline tholeiitic basaltic andesite according to their major-element compositions with lower to moderate mg#, varying from 26 to 58. All dolerites demonstrate a similar slightly negative ɛNd(t) values range from −2.2 to −2.5. Geological, geochemical and Nd isotopic data suggest that mafic melts responsible for genesis of the dolerites were generated in an intracontinental extensional setting from homogeneous mantle source produced by interaction between OIB and ACR-like magmas. Geochemical features of the studied dolerites together with geological observations, namely – a presence of coeval rift-related sedimentary strata in the neighboring Urik-Iya graben (paleorift), suggest an overall extensional tectonic environments in the southern part of the Siberian Craton at 1.65–1.60 Ga. Synthesis of data on ca. 1.65–1.58 Ga magmatism around the world showed that the spatial distribution of various ca. 1.65–1.58 Ga mafic and felsic intrusions, including dyke swarms, anorogenic granites, as well as intracontinental basins within Nuna supercontinent suggest the overall extensional tectonic environments, probably related to the retreat of subduction slabs surrounded the supercontinent.

本文介绍了新的地质，地球年代，地球化学和Nd同位素数据，这些数据是最新的古元古代白云石窗台暴露于西伯利亚克拉通南部Biryusa内陆的沉积序列中的砂岩，传统上被认为是新元古代。一个白云石窗台产生了1613±5 Ma的U-Pb（ID-TIMS）斑脱钙石共生年龄，这被解释为是它们的就位时间。新的地球年代学数据可以重新考虑先前报道的新元古代的沉积序列，该沉积序列具有所研究的白云石基岩，并建议它们至少为古元古代。根据其主要元素组成，白云母分别对应于碱下和碱性可膨胀玄武岩，而碱下可膨胀的玄武岩则较少见，它们的mg＃含量较低至中等，从26到58不等。所有白云母都表现出相似的略微负negativeNd（t）值，范围为-2.2至-2.5。地质，地球化学和Nd同位素数据表明，负责白云石成因的铁镁质熔体是在OIB和ACR状岩浆之间的相互作用所产生的均质地幔源的大陆内伸展环境中产生的。所研究的白云岩的地球化学特征以及地质观测结果，即–邻近的Urik-Iya地en（paleorift）中存在与裂谷有关的沉积地层，表明西伯利亚克拉通南部的总体伸展构造环境为1.65– 1.60 Ga。全世界1.65–1.58的Ga岩浆作用表明，各种ca. 1.65–1.58 Ga的黑手党和长老入侵，包括堤防群，