--> Abstract: Late Orogenic Faulting - an Important Component of Hydrocarbon Systems of Orogenic Belts and Their Forelands, by Frank J. Picha; #90072 (2007)

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Late Orogenic Faulting - an Important Component of Hydrocarbon Systems of Orogenic Belts and Their Forelands

Frank J. Picha
Consulting Geologist, USA

The hydrocarbon potential of the frontal zones of some thrust belts, e.g., the Carpathians and Dinarides-Hellenides, and their forelands is affected by the late orogenic normal, reverse, and strike-slip faulting, at least partly related to the renewed activity along the pre-existing fault systems of the foreland. During the last stages of the convergence, various structural elements of the foreland tend to adjust to the orogenic stresses by uplifting, sagging and/or by a lateral translation and opening of pull-apart basins. Examples of the latter are the middle Miocene and Pliocene pull-apart phases in the Vienna basin and the Albanian foredeep, respectively. The sudden opening and fast filling of these depocenters enhance the generation of hydrocarbons from source rock within the thrust belt or the underlying platform. In addition, reservoir sands are deposited in deltaic systems of these depocenters. The deeply rooted faults may facilitate vertical migration, but also breach the existing seals or restrict the lateral migration toward the foreland.
In the Eastern Carpathians, the reactivated faulting in the Polish trough deepened the Carpathian foredeep and created a buttress behind which the advancing nappes piled in a form of recumbent folds. This positively affected the petroleum potential both of the thrust belt (e.g., Boryslav field) and the subthrust platform (Lopushna field).
The late orogenic faulting and its timing thus represent important factors, which may determine hydrocarbon potentials of various segments of orogenic belts and their forelands.

 

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