Abstract: Structure and Kinematics of a Bent Fold-and-Thrust Belt: The Oil-Bearing Outer Eastern Carpathians (Romania)

Peter Wagner-Zweigel

The east-vergent fold-and-thrust belt of the Eastern Carpathians changes strike by 70° in the south. It formed from early Cretaceous to Recent times and contains the oil-productive province of Ploiesti. To understand orocline formation, a detailed kinematic analysis of folding-thrusting by means of mesoscale fault-slip analysis was carried out.

Most stations revealed mainly subhorizontal contraction axes which fan around the bending zone from 110 degrees in the N to 160 degrees at the southwestern end of the Eastern Carpathians. Since this fanning pattern is consistent for rocks ranging from Lower Cretaceous to at least Miocene, its formation 15 interpreted as syn- or post-Miocene in age. The strain pattern probably resulted from the following processes: (a) Cretaceous to Oligocene thrusting and folding. Contractional axes representing this process trend normal to fold axes and were calculated from the oldest fault sets in outcrops exhibiting polyphase brittle deformation. (b) Miocene to Recent eastward thrusting and folding coeval with dextral wrenching in the southern part of the N-S-trending fold-and-thrust belt. The seco d process is characterized by curved strain trajectories and caused rotation of older structures. As Miocene and post-Miocene structures are strongly influenced by wrench tectonics new tectonic models are needed to guide exploration in the oil province of Ploiesti.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France