Geofizikai Közlemények/Geophysical Transactions Vol. 35. No. 1-2 [antikvár]

GEOPHYSICAL TRANSACTIONS 1989 Vol. 35. No. 1-2. pp. 3-63 LARGE-SCALE TERTIARY STRIKE-SLIP DISPLACEMENTS RECORDED IN THE STRUCTURE OF THE TRANSDANUBIAN RANGE Zoltán BALLA* and Antonina DUDKO** Two main epochs of intensive tectonism have been distinguished in the Transdanubian Range. The first of them occurred in the Middle Cretaceous and resulted in a synclinal structure bent in the northeast together with accompanying thrust slices. This old structural pattern has been used as a marker system in the analysis of the tectonism of the second epoch which took place in the Oligocene-Miocene. Three stages of this young tectonism have been established as follows: 1) dextral shear of the southeastern margin of the Transdanubian Range domain in the Oligocene (appr. 30-22 Ma B.P.); 2) S-shaped bending of all structures in the Early-Middle Miocene (appr. 22-14 Ma); 3) sinistral shear and compression in the Middle Miocene (appr. 14-12 Ma). These features have been correlated with synchronous kinematic processes of the Alpine-Car-pathian-Pannonian realm as follows: '1' with the removal of the northwestern Carpatho-Pannonian domains from the Alpine realm; '2' with the collision of the clockwise rotating southeastern Carpatho-Pannonian domains with the northwestern Carpatho-Pannonian domains, and with the push of the latter towards the north; '3' with the clockwise rotation of the southeastern Carpatho-Pannonian domains resulting in the sinistral shear of the contact zone with the northwestern Carpatho-Pannonian domains, and with the partial drag of the northwestern Carpatho-Pannonian domains resulting in the s inistral shear of their interiors. A check of the consequences of the regional kinematic modelling in the Transdanubian Range, i.e. in a well-studied area, has revealed consistency of local tectonic features with the regional model Keywords: Transdanubia, Oligocene, Miocene, bending, strike-slip faults, shear, syncline, models, kinematics 1. Introduction The Oligocene-Miocene development of the Alpine-Carpathian-Pannonian region has recently been studied by kinematic modelling [Balla 1985, 1986, 1987]. It would be of interest to test the consequences in a well-studied area like the Transdanubian Range. The goal of this work comprises (1) selection of important and reliable tectonic data with their primary interpretation, (2) synthesis of the data selected in geological maps and in a uniform picture of kinematic features and (3) correlation of the picture obtained with the kinematics of the Alpine-Carpathian-Pannonian realm. 2. Selection and primary interpretation of data All data on the tectonics of the Transdanubian Range (for review, see Table I) can be gathered into two groups: data on the tectonics of the whole Range (regional tectonics); data of its parts (local tectonics). * Eötvös Loránd Geophysical Institute of Hungary, Budapest, POB 35, H-1440, Hungary ""Hungarian Geological Survey, Budapest Népstadion út 14, H-1142, Hungary Manuscript received (revised version): 16 June, 1988