Systematic Joints within the Adriatic Carbonate Platform, Istria, Croatia: A Reflection of Strike-slip Kinematics Near the Apulian Plate Boundary

Terry Engelder¹ and Vlastimila Dvorakova^2
1The Pennsylvania State University, University Park, PA
²Czech Geological Survey, Brno, Czech Republic

Foreland fold-thrust belts including the Appalachian Mountains of North America carry fracture patterns that record components of strike-slip motion at the boundaries of lithosphere plates. The same is true of the Dinarides where Cretaceous limestone of the gently deformed Adriatic carbonate platform carry a systematic joint set striking to the ESE in the southern portion of Istria, Croatia. Evidence for tectonic deformation also includes gentle folds with axes normal to the systematic joint set, minor faults, and a disjunctive cleavage indicative of ESE-WNW shortening. Together this suite of structures is not consistent with the kinematics of the SW vergence of both the Dinaridic carbonate platform thrust over the imbricated Adriatic carbonate platform. However, both the imbricated Dinaridic and Adriatic platform rocks were cut by late right lateral strike-slip faults. The slip vector on these fault blocks is toward the WNW and within a few degrees of the strike of the systematic joints of Istria. Late orogenic strike-slip faulting has also been attributed to escape tectonics to the ESE causing the pull-apart basin of the Albanian foredeep. Blocks to the WNW of the Albania foredeep are interpreted as having abutted against the Adriatic carbonate platform of Istria. The structures of lightly tectonized Istria are a manifestation of resistance this WNW movement which set up a regional maximum horizontal stress (SH) that is recorded by systematic joints of Istria.

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