Cimmeride (Middle and Late Triassic) Structures Beneath the Moesian Platform of Romania and Bulgaria

Gabor Tari, Georgi Georgiev, Mihai Stefanescu, and Gary Weir

Numerous structures within the pre-Jurassic sequence underneath the Moesian Platform of Romania and Bulgaria are traditionally attributed to the loosely defined Triassic "Old Cimmeride" phase. Widespread Anisian-Carnian volcanism indicates an aborted rifting period also marked by locally very thick (>2000 m) evaporites. Based on isopach maps and the subcrop of the overlying Jurassic passive margin sequence we interpret a large-scale (150×60 km) subsurface feature (North Bulgarian Arch) as the northern rift flank of a failed, E-trending branch of the Paleotethys.

The extensional period was replaced by the Norian-Rhaetian by a compressional regime in the whole Moesian Platform. Although the Cimmeride folds were undoubtedly formed due to compression, detailed structural analysis permitted a more specific interpretation of the deformation in terms of fault-bend folding in a northvergent thin-skinned thrust-fold belt. Structural modeling of the anticlines suggests relatively minor shortening (5-20%). In a wider paleotectonic scenario the north-vergent anticlines beneath the Moesian Platform are interpreted as the frontal, foreland thrust-fold belt of the Mediterranean Cimmerides propagating into the foreland. The recognition of a Cimmeride foreland thrust-fold belt in the Moesian Platform area has an important impact for the reconstruction of the estern Paleo-Tethys.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California