Print this pageOutcrops of Intact Lower Carboniferous Carbonate Platforms in Asturias (Northern Spain) as Analogues of Coeval Reservoirs in the Subsurface of the Pricaspian Basin (Kazakstan, Russia)
KENTER, JEROEN A. M., GUIDO L BRACCO GARTHER, JAN C. M. DE COO, and JUAN R. BAHAMONDE
Outcrops of intact and large-scale Lower Carboniferous carbonate platforms in Asturias (northern Spain) were studied as analogues of the prolific subsurface reservoirs in the Pricaspian Basin (e.g. Tengiz Field). The Asturian platforms, which have been rotated 90 degrees along the Outcrops of intact and large-scale Lower Carboniferous carbonate platforms in Asturias (northern Spain) were studied as analogues of the prolific subsurface reservoirs in the Pricaspian Basin (e.g. Tengiz Field). The Asturian platforms, which have been rotated 90 degrees along the dip-axis during Late Carboniferous thrusting, are visible on aerial photographs as km-scale cross-sections. Geometrical dimensions are similar to their Pricaspian subsurface equivalents: a thickness between 1.5 and 2.5 km, a slope relief up to 1.0 km, slope angles ranging from 29 to 360 and nearly planar clinoforms. The reconstructed platform has a diameter of more than 100 km.
At least six lithofacies belts were mapped: toe of slope, lower slope, upper slope, margin, outer platform, and inner platform. Calibration of lithofacies with stratal patterns suggests three major phases of platform development: 1) a regional (100 km wide) shallow-water platform during most of the Sephukovian, 2) partial drowning of this platform, renewed platform nucleation and predominantly aggradation in the Bashkirian, and 3) progradation with minor aggradation during the Moscovian. The last phase includes at least four major episodes of subaerial exposure with siliciclastic intercalations.
Synthetic seismic models show great similarity with seismics acquired in the Pricaspian subsurface. The integration and quantification of outcrop data provide a powerful predictive tool for the exploration of coeval and size-similar platforms in the subsurface of the Pricaspian basin.