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Sequence stratigraphy and systems tracts of a mixed carbonate and siliciclastic platform-basin setting: The Albian of Lunada and Soba, Northern Spain

Journal Article · · AAPG Bulletin (American Association of Petroleum Geologists); (United States)
OSTI ID:5940267

This paper deals with Albian carbonate and terrigenous succession from the Lunada-Soba area (Albian of Basque-Cantabrian region, northern Spain). Nine type 1 depositional sequences have been identified. Their boundaries represent times of complete exposure of the platform with accompanying karstification and fluvial erosion. During lowstands, deposits of the corresponding systems tract onlapped the platform foreslope or filled incised valleys on the platform top. These deposits comprise facies of: limestone megabreccias derived from the platform margin, allodapic grainstones, hemipelagic marls, fine-grained estuarine sandstones, bank bafflestones and grainstones, fluvio-deltaic pebbly conglomerates and sandstones, and shallowwater orbitolinid grainstones. Relative sea level rises were characterized by deposition of monotonous marls in the basin, and by the growth of coral-rudist mud mounds and accumulations of skeletal grainstones and marls, sometimes with back-stepping stacking. on the platform. During highstands, hemipelagic marls and prodeltaic and talus delta lutites and sandstones dominated in the basin and coral wackestones and orbitolinid grainstones, sometimes with prograding clinoforms, dominated on the platform. Transgressive surfaces have erosion or simply omission features, such as pebble lags or numerous burrows, respectively. No well-developed condensed sections exist and they are represented by thin beds of marls rich in orbitolinids. Fine-grained siliclastic basinal deposits are higher than hemipelagic marls in organic carbon content and they reach maximum TOC values of 1.3%. Possible petroleum reservoirs are paleokarstified intervals of the platform margins under the unconformities, turbidite sandstones, megabreccias and allodapic calcarenites in the basin. 64 refs. 32 figs.

OSTI ID:
5940267
Journal Information:
AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:2; ISSN 0149-1423; ISSN AABUD2
Country of Publication:
United States
Language:
English