ABSTRACT: Diapiric Structures in the Pricaspian Basin, Kazakhstan

PILIFOSSOV, VIKTOR M., and EDGAR M. VOTSALEFSKY, Institute of Geological Sciences, Kazakh Academy of Sciences, Alma-Ata, Kazakhstan, and STEVEN SCHAMEL and JOHN L. SMALE, University of South Carolina, Columbia, SC

The Pricaspian depression in northwestern Kazakhstan is one of the great salt basins of the world. Up to 4.5 km of salt and associated evaporites were deposited in this deep, tectonically silled, circular depression during the Late Permian. The Kungurian-Kazanian salt was subsequently buried beneath an average of 5 km of post-Paleozoic terrigenous sediments that loaded the salt and triggered extensive, long-lived diapirism. Only the extreme margins and southern rim of the basin are unaffected by salt diapirs.

The structural style of the diapirs relates directly to the original depositional thickness of the Upper Permian salt. Based on style, three principal structural provinces are recognized. Salt rollers, anticlines, and elongate walls characterize the outer margins of the basin where only a thin layer of Kungurian-age salt is present. The central portion of the basin contains large, close-set, circular and branching salt domes developed in the thick Kungurian-Kazanian salt. Structural relief on these domes is on the order of 6-8 km. In a broad transition zone, thin Kazanian-age salt layers are passively infolded into the peripheral synclines between Kungurian salt domes. Active diapirism ended prior to the Early Cretaceous in the marginal areas of the basin but continued through the Pal ogene in the central region.

High-resolution seismic reflection lines display the variations in both the style of the salt structures and the structural/stratigraphic traps associated with them.

AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)