ISSN 0869-5938, Stratigraphy and Geological Correlation, 2011, Vol. 19, No. 2, pp. 125–140. © Pleiades Publishing, Ltd., 2011. Original Russian Text © A.V. Kuptsova, A.K. Khudoley W. Davis, R.H. Rainbird, V.P. Kovach, N.Yu. Zagornaya, 2011, published in Stratigrafiya. Geologicheskaya Korrelyatsiya, 2011, Vol. 19, No. 2, pp. 3–19. 125 INTRODUCTION The Riphean volcano-sedimentary complex of the Pasha–Ladoga basin is poorly exposed and available information on its stratigraphy and structure is largely derived from seismic profiling records and rare bore- holes drilled in its different parts (Amantov and Spiri- donov, 1989; Amantov et al., 1996; Gosudarstven- naya…, 2000; Kheraskova et al., 2006). Drilling car- ried out in the eastern part of the Pasha–Ladoga basin since the mid-1980s revealed that this area hosts the Karku unconformity type uranium deposit (Kushner- enko et al., 2004; Mikhailov, 2004). Such deposits are confined to the unconformity zone between the sedi- mentary cover and basement and, according to studies of their classical representatives such as unconfor- mity-related deposits in the Athabasca basin in Can- ada, their formation is closely related to the evolution of a sedimentary basin at its early development stages (Jefferson et al., 2007). The main purpose of this research is the refinement of the stratigraphic position of Riphean rock complexes in the eastern part of the Pasha–Ladoga graben and reconstruction of prove- nances for detrital material and its sedimentation set- tings using the U–Pb zircon geochronology and Sm– Nd systematics in bulk samples of terrigenous rocks. BRIEF REVIEW OF THE REGIONAL GEOLOGICAL STRUCTURE The Pasha–Ladoga basin corresponds to the syn- onymous trough, a large graben-shaped depression that originated in the Late Proterozoic together with a system of paleorifts (Satakunta, Mukos, and others) in the Fennoscandian Shield (Gosudarstvennaya… 2000). The trough is superimposed on two principally differ- ent crustal blocks (from the east westward): (1) south- eastern extremity of the Raahe–Ladoga Suture repre- senting a junction zone of the Archean Karelian Cra- ton and Early Proterozoic Svecofennian fold belt and (2) southeastern part of the Svecofennian fold system proper (Fig. 1). On the northeastern slope of the trough, unmeta- morphosed Riphean sedimentary rocks rest upon Archean–Lower Proterozoic leuco- and mesocratic Age and Provenances of Sandstones from the Riphean Priozersk and Salmi Formations in the Eastern Pasha–Ladoga Basin (Southern Margin of the Baltic Shield) A. V. Kuptsova a , A. K. Khudoley a , W. Davis b , R. H. Rainbird b , V. P. Kovach c , and N. Yu. Zagornaya c a St. Petersburg State University, Universitetskaya nab. 7/9, St. Petersburg, 199034 Russia e-mail: alina-kuptsova@yandex.ru b Geological Survey of Canada, Ottawa, Canada c Institute of Precambrian Geology and Geochronology (IGGD), Russian Academy of Sciences, nab. Makarova 2, St. Petersburg, 199034 Russia Received February 2, 2010; in final form April 28, 2010 Abstract—The data on the age of sediments and their sources were first obtained by isotopic methods and lithological-petrographic observations for the Priozersk and Salmi formations in the northeastern Pasha– Ladoga basin. Wide development of coarse-grained terrigenous rocks and peculiar structures point to the proximity of provenances and dominant sedimentation in terrestrial settings. U–Pb dating of 168 detrital zir- cons revealed that approximately 87% of all grains are Early Riphean in age, while other grains are dated back to the Early Proterozoic. Archean age is documented for only two zircon grains. It is established that detrital material of sandstones from the Priozersk and Salmi formations largely originate from the Salmi Massif (1.55–1.53 Ga) and secondarily from the Svecofennian intrusions of the northern Ladoga region aged approximately 1.88 Ga, which is confirmed also by Sm–Nd data. The occurrence of detrital zircons dated at approximately 1480–1490 Ma indicates development of coeval magmatic bodies in the immediate proximity to the sedimentation basin, which remain undiscovered. The concordant age obtained for the youngest detri- tal zircon grain points to the onset of sedimentation in the basin after 1477 ± 8 Ma ago. Thus, Riphean sed- imentation on the eastern slope of the trough commenced only 20 Ma prior to the emplacement of the Val- aam Sill. Keywords: Ladoga region, Priozersk Formation, Salmi Formation, Riphean, provenances, geochronology. DOI: 10.1134/S0869593811020067