Skip to Main Content
Book Chapter

Regional Controls on Lacustrine Sandstone Reservoirs: The Pliocene of the South Caspian Basin

By
Nazim R Abdullayev
Nazim R Abdullayev
BP Exploration
,
Middlesex
,
United Kingdom
Search for other works by this author on:
Gregory W. Riley
Gregory W. Riley
BP Exploration
,
Middlesex
,
United Kingdom
Search for other works by this author on:
Andrew P. Bowman
Andrew P. Bowman
BP Exploration
,
Middlesex
,
United Kingdom
Search for other works by this author on:
Published:
January 01, 2012

Abstract

The Pliocene Productive Series of the South Caspian Basin records a major lowstand relative to pre-existing Miocene and subsequent Pleistocene and Holocene shelf margins. The Productive Series records approximate 2.6 m.y. of relatively continuous deposition of lacustrine sediments and reaches more than 6 km (0.62 mi) in thickness. Regional-scale seismic mapping has allowed an interpretation of the basin evolution during the deposition of the Productive Series. The Productive Series is subdivided into four phases of deposition. Differences between these phases are interpreted to reflect changes in the balance between sediment and water input and the evolving basin morphology. Basin morphology inherited from a previous depositional phase strongly influence successive phases of deposition.

Phase 1. Messinian: Base-level fall, roughly coincident with the Messinian Salinity Crisis, resulted in isolation of the Caspian Sea from the global oceans. Reconstruction of the basin profile immediately after this event indicates that the South Caspian Basins base-level fell by approximately 1.5 km (0.93 mi).

Phase 2. Integration of drainage systems to this dramatically lowered base level resulted in the delivery of large volumes of sediment and water from the Russian Platform, Caucasus mountains, and Kopet-Dagh mountains to the South Caspian Basin through the Paleo Volga, Kura, and Amu darya/Uzboy rivers. Within the South Caspian Basin, fluvial and fluvio-lacustrine facies were deposited in preexisting structural depressions, forming the Lower Productive Series.

Phase 3. Infill of paleotopographic depressions by the Lower Productive Series resulted in the formation of a low gradient ramp over much of the South Caspian Basin. Middle Productive Series strata were deposited on this low-gradient ramp as aerially extensive fluvial, deltaic, and lacustrine facies. Reconstructed basin profiles show a reduction of the depositional gradient as the result of sediment infill.

Phase 4. During deposition of the Upper Productive Series, the ratio of sediment supply to water supply decreased as much of the coarse-grained sediment supplied from the Paleo-Volga was deposited updip. Thus, the updip depositional profile became increasingly low relief.

This change led to the creation of a relatively deep-water lake in the center of the South Caspian Basin surrounded by lacustrine shelf margins. Evaporites were deposited in the center of this lake, suggesting that it was subject to episodic phases of desiccation.

Overlying the Productive Series is a regionally extensive marine condensed section, the Akchagyl Suite. The Akchagyl Suite records a major regional transgression and a return to marine conditions as the South Caspian Basin was reconnected to the global oceans. Pleis-tocene shelf margin complexes downlap onto the Akchagyl Suite and record progradation of shorelines into a deep-water brackish lake (~1000 m [3280 ft]). This Pleistocene depositional system was similar to the present-day depositional setting of the Caspian Sea.

You do not currently have access to this article.

Figures & Tables

Contents

AAPG Memoir

Lacustrine Sandstone Reservoirs and Hydrocarbon Systems

Olive W. (Terry) Baganz
Olive W. (Terry) Baganz
Search for other works by this author on:
Yuval Bartov
Yuval Bartov
Search for other works by this author on:
Kevin M. Bohacs
Kevin M. Bohacs
Search for other works by this author on:
Dag Nummedal
Dag Nummedal
Search for other works by this author on:
American Association of Petroleum Geologists
Volume
95
ISBN electronic:
9781629810096
Publication date:
January 01, 2012

GeoRef

References

Related

Citing Books via

Close Modal
This Feature Is Available To Subscribers Only

Sign In or Create an Account

Close Modal
Close Modal