--> Abstract: Basement Inheritance Controls on Fold Evolution in the South Caspian Sea, by Ken McCaffrey and Richard Jolly; #90072 (2007)

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Basement Inheritance Controls on Fold Evolution in the South Caspian Sea

Ken McCaffrey1 and Richard Jolly2
1Durham University, Durham, United Kingdom
2BP/Sunbury, London, United Kingdom

Geological architectures are ultimately generated by plate movement vectors and mechanical stratigraphy, but significantly complicated by basement inheritance – defined as previous geohistory and pre-existing mechanical heterogeneities. The Caspian Sea provides an active example where interaction between plate movements, basement blocks and mechanical stratigraphy control structural trends and styles that vary across the region. Here, we discuss ongoing work to establish the dominant controls on the origin and evolution of the South Caspian fold structures. A thick Tertiary sequence is being actively folded into trains of 10-20km wavelength, 5-10km amplitude upright folds which display 3 main structural trends - NNW-SSE, WNW-ESE and NE-SW. These form a triangular-shaped fold pattern in the NE part of the basin with dome and basin structures created in the apex regions where the trends interfere. NNW-SSE trending linear fold arrays were most likely influenced by inversion of Mesozoic or older basin margin normal faults. The WNW-ESE fold trains formed by reactivation of a Mesozoic to Miocene accretionary complex formed underneath the Apsheron sill along the southern boundary of a basement block (Karabogaz). In contrast the NE-SW to E-W folds appear to have formed as pure detachment structures in response to NW-directed movement of South Caspian basement. Folds along all three trends appear to have initiated at about the same time. Whereas the younger folds began forming in the centre of the ‘triangular region' creating dome and basin structures with short, bifurcating hinges.

 

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece