排序方式： 共有35条查询结果，搜索用时 62 毫秒
31.
Lithology and Mineral Resources - Studying with precision methods the mineral composition of bauxites in the Kursk Magnetic Anomaly (KMA) made it possible to reevaluate the conditions of their... 相似文献
32.
Savko K. A. Kuznetsov A. B. Ovchinnikova M. Yu. Kramchaninov A. Yu. 《Doklady Earth Sciences》2021,497(2):286-290
Doklady Earth Sciences - The age of carbonate rocks of the Tim Formation of the Oskol Group of the Kursk block, Sarmatia, is limited to 2.22–2.10 Ga on the basis of new data on δ13C and... 相似文献
33.
The geological, geochemical, and isotope-geochronological evidence of the events at the final stage of the Neoproterozoic history of the Yenisei Range is considered (beginning from the formation of fragments of the oceanic crust in the region and their accretion to the Siberian Craton until the postaccretionary stage of crustal tension and onset of the Caledonian orogeny). Based on an analysis of new data on the petrogeochemical composition, age, and geodynamic nature of the formation of contrasting rocks in the composition of tectonic mélange of the Near-Yenisei (Prieniseiskaya) regional shear zone, we have found the chronological sequence of events that marks the early stages of the Paleoasian Ocean evolution in the zone of its junction with the Siberian Craton. These events are documented by the continental marginal, ophiolitic, and island-arc geological complexes, each of which has different geochemical features. The most ancient structures are represented by fragments of oceanic crust and island arcs from the Isakovka terrane (700–620 Ma). The age of glaucophane-schist metamorphic units that formed in the paleosubduction zone corresponds to the time interval of 640–620 Ma. The formation of high-pressure tectonites in the suture zone, about 600 Ma in age, marks the finishing stage of accretion of the Isakovka block to the western margin of the Siberian Craton. The final events in the early history of the Asian Paleoocean were related to the formation of Late Vendian riftogenic amygdaloidal basalts (572 ± 6.5 Ma) and intrusion of postcollisional leucogranites of the Osinovka massif (550–540 Ma), which intruded earlier fragments of the oceanic crust in the Isakovka terrane. These data allow us to refine the Late Precambrian stratigraphic scheme in the northwestern Trans-Angarian part of the Yenisei Range and the evolutionary features of the Sayan–Yenisei accretionary belt. The revealed Late Neoproterozoic landmarks of the evolution of the Isakovka terrane are attributed to the terminal phase of the breakup of Rodinia, separation of the Siberian Craton, and opening of the Paleoasian Ocean. 相似文献
34.
35.
Savko A. D. Manukovskiy S. V. Boeva N. M. Kraynov A. V. Milash A. V. 《Geology of Ore Deposits》2022,64(1):60-72
Geology of Ore Deposits - Secondary kaolins in Upper Devonian deposits are developed within the tectonic depression in the south of the Voronezh Anteclise. They formed as a result of erosion of the... 相似文献