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Abstract A series of palinspastic and paleogeographic reconstructions has been made for the Pannonian and surrounding regions for five time periods: (1) Coniacian-Paleocene, (2) early-middle Eocene, (3) late Eocene-early Oligocene, (4) late Oligocene-early Miocene, and (5) late Miocene. These maps were constructed by grouping together various crustal blocks that underwent similar phases of deformation or sedimentation into tectonostrati-graphic units. We show how the present complex distribution of Mesozoic tectonostratigraphic units could have developed from a simple initial configuration during Cenozoic deformation of the Carpathian-Pannonian region, and that the formation, duration, and disruption of various Paleogene paleogeographic elements can be directly related to contemporaneous tectonic events. In this analysis we interpret the elongate Hungar, ian Paleogene basin as a wrench related basin that formed along an east, northeast, trending zone of dextral shear in Eocene-Oligocene time. This shear zone was probably responsible for the Paleo-gene dislocation of the Apuseni Mountains from the inner West Carpathians. We further interpret the Pieniny Klippen belt as the result of conver, gence and sinistral shear active in part during Eocene time. This analysis suggests that the inner flysch zones (podhale flysch, Szolnok, Maramures flysch, and Transcarpathian flysch) originally con, stituted a continuous flysch basin that was subse, quently disrupted by roughly east, northeast, trending dextral shear zones. Large shear zones such as those postulated in this paper are required partly because of the diachro, nous nature of the convergent boundary extending from the Eastern Alps to the East Carpathians and partly because of the different directions of thrusting around the belt. These shear zones separate areas of active shortening in the outer Carpathian orogenic belt from inactive parts of the belt and also act as transform type boundaries that connect areas of shortening in the Carpathians to areas of short, ening in the Dinaric Alps. The existence of such shear zones can thus be deduced almost directly from analysis of the varying rates and directions of convergence across the Carpathian belt.

Abstract The Miocene evolution of the Carpathian-Pannonian system appears to have been controlled by events within the adjacent Alpine mountain belts. Early Miocene initiation of northward to eastward thrusting in the outer Carpathians is best ascribed to the eastward escape of the Pannonian continental lithospheric fragments) away from the zone of collision in the Eastern Alps. The subsequent “back arc” extension in the Pannonian basin system in middle-late Miocene time was coeval with the late stages of thrusting in the adjacent Carpathian belt. Net east-west extension within the basin system can be related both to the arrangement of continental lithospheric fragment boundaries outside of the Pannonian area, which prohibited continued convergence of the Pannonian fragment with Europe, and to the continued subduction and shortening beneath the East Carpathians at the same time. Basin extension was heterogeneous and diachro-nous throughout the Pannonian basin system. Variations in basin development were intimately related to contemporaneous thrust belt activity in the Carpathian Mountains. Extension occurred along a conjugate system of strike-slip faults that connected areas of coeval extension to one another and to coeval areas of shortening within the Carpathian thrust belt, thus providing a mechanical link between basin extension and thrusting. The style of extension at depth was controlled by the geometry of the thrust belt at depth and the distance from the thrust front. The style of sedimentation within each basin was also influenced by the proximity of each basin to the thrust front. Basins located near the thrust belt contain thick synextensional fault-bounded sedimentary rocks overlain by thin postextensional sediments. The normal faults reach nearly to the surface. Basins located far from the thrust belt contain thin sequences of synextensional fault-bounded sedimentary rock sequences overlain by thick sequences of postextensional, unfaulted, flat-lying sedimentary rocks. These differences can be explained by differences in the thermal subsidence rate of the basement after extension and by the proximity of each basin to the sediment sources in the Carpathians.

Abstract Extensional styles at depth beneath five basins within the Pannonian basin system (Vienna, Danube, Zala, and Transcarpathian basins and Great Hungarian Plain) were evaluated by applying a simple graphical technique to subsidence and heat flow data from wells in each basin. The average rate of thermal subsidence in each basin, excluding the Transcarpathian basin, indicates the same rate of cooling of the lithosphere as does the surface heat flow measured in the same basin. Thermal subsidence rates, heat flow, and effective mantle thinning or (heating) show a systematic increase with increasing distance from the Carpathian thrust front. Initial subsidence and crustal thinning show little to no correlation with distance from the thrust front. These results are consistent with thin-skinned extension (involving only crustal rocks) beneath the Vienna basin, which is located near the thrust front. At greater distances from the thrust front, extension involves both the crust and mantle-lithosphere. Beneath the basins located more than 200 km from the thrust front, the mantle lithosphere appears to be very thin or very hot. A transitional zone exists between the area of thin-skinned extension in the crust and the area of greatly thinned mantle lithosphere, and is roughly coincident with the Miocene calcalkaline volcanic belts.

Abstract Recently available vitrinite reflectance data, temperature-depth profiles, and heat flow values have made it possible for us to develop an improved computer model to simulate the subsidence, thermal, and maturation history of the Pannonian basin. This model takes into consideration different rates of extension in the lower and upper lithosphere, heat generation in the crust, the thermal blanketing effect of fast sedimentation, the change in porosity and thermal conductivity in space and time, and both normal and abnormal compaction of sediments. Model parameters are constrained by comparison of predicted and observed subsidence histories, present crustal thicknesses, temperature versus depth profiles, and heat flow values. We conclude that lithospheric stretching, combined with major additional thinning of the subcrustal lithosphere, is adequate to explain the formation and evolution of the Pannonian basin.

Abstract The aim of this volume has been to present a study of basin evolution within the Pannonian basin, which is more accurately called the Pannonian basin system because it consists of several individual basins. The papers contained in this volume were designed to present basic data from a wide variety of geological disciplines, and to integrate these different data sets into acomprehensive study of the evolution ofthe Pannonian basin. These papers have focused not only on evolution of the basins themselves, but also on attendant processes within the crust and upper mantle that controlled the development of the basin in some fundamental ways. The Pannonian basin system is a particularly good candidate for basin analysis, partly because the evolution of this young basin system is relatively simple. In addition, the basin system had one brief period of extension, a simple sedimentary history and a clearly defined regional tectonic setting. The active processes that formed the basin system were short-lived and recent, are essentially finished, and have not been overprinted by subsequent tectonic events. Events within the basin system itself can be spatially and temporally related to regional tectonic events outside of the basin area. The young age of the basin system ensures that many geological and geophysical data such as heat flow, seismic velocities, earthquakes, and so on, provide useful constraints on the processes of basin formation. Because dating is more accurate in young rocks than in older ones, events that are diachronous by as little as one or two million years can be documented in this young basin system, whereas in older basins these events would appear to be contemporaneous everywhere.