A unique collection of deep (up to 4.5 km) drillcores from across the Pechora Basin of NW Russia indicate that the Precambrian basement beneath Palaeozoic sediments mainly comprise Neoproterozoic metasedimentary and magmatic complexes. These Neoproterozoic rocks are variously deformed and metamorphosed. They are intruded by granitoids of latest Neoproterozoic age (557 ± 6 Ma, 95% confidence). The granitoids are variably deformed, metamorphose their country rock, and represent syn- to post-tectonic magmatism. Major element, trace element, and Sm-Nd and Rb-Sr isotopic data indicate that these intrusions represent continental arc magmatism. Their geochemistry indicates assimilation of older crust by a magma derived from a depleted mantle source. We infer that the granitoids were generated by westward subduction of oceanic crust beneath Baltica (present day coordinates) at c. 560 Ma.
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The Neoproterozoic Timanide Orogen of Eastern Baltica
The Neoproterozoic Timanide Orogen of eastern Baltiea extends from the high Arctic to the southern Ural Mountains and represents significant crustal growth of the northeastern European continental margin in the late Neoproterozoic. This volume, a co-operation between Western European and Russian scientists within the framework of the European Science Foundation’s EUROPROBE programme, provides a comprehensive overview of the orogen and represents a new synthesis of Timanian Orogeny. It includes: the pre-Timanian passive margin deposits of the northern and northeastern flank of the East European Craton; the magmatic, metamorphic and structural evolution of the orogen across the Timan Mountain and Pechora Basin regions to the Ural Mountains; the post-Timanian platform successions, important for interpreting the timing of orogeny and the return to an early Palaeozoic passive margin setting; and the extension of the orogen northwards to Novaya Zemlya. Relationships westwards to the Caledonides of Greenland and Scandinavia and eastwards to the Baikalides of Siberia are also treated.
This volume will be of interest to geoseientists, students and researchers concerned with orogenic processes and regional tectonics.