ABSTRACT The Paleozoic plate boundary zone between Laurussia and Gondwana in western Pangea hosts major magmatic and hydrothermal Sn-W-Ta, Au, and U mineralization. Individual mineral deposits represent the results of the superposition of a series of exogenic and endogenic processes. Exogenic processes controlled (1) the enrichment of the ore elements in sedimentary protoliths via residual enrichment during intense chemical weathering and via climatically or tectonically controlled redox traps, (2) the spatial distribution of fertile protoliths, and, thus, eventually (3) the spatial distribution of mineralization. Endogenic processes resulting in metamorphism and crustal melting controlled the mobilization of Sn-W, Au, and U from these enriched protoliths and, thus, account for the age distribution of Sn-W and Au mineralization and U-fertile granites. It is the sequence of exogenic and endogenic processes that eventually results in the formation of mineralization in particular tectonic zones. Whereas the endogenic processes were controlled by orogenic processes during the assembly of western Pangea itself, the exogenic processes were linked to the formation of suitable source rocks for later mineralization. The contrasting distribution of magmatic and hydrothermal Sn-W-Ta, Au, and U mineralization on the Laurussia and Gondwana sides of the plate boundary zone reflects the contrasting distribution of fertile protoliths and the contrasting tectonic situation on these margins. The Laurussian margin was an active margin during most of the Paleozoic, and the distribution of different mineralization types reflects the distribution of terranes of contrasting provenance. The Gondwanan margin was a passive margin during most of the Paleozoic, and the similar distribution of a wide range of different metals (Sn, W, Ta, Au, and U) reflects the fact that the protoliths for the various metals were diachronously accumulated on the same shelf, before the metals were mobilized during Acadian, Variscan, and Alleghanian orogenic processes.

Abstract The Tornquist Fan, reflecting the northern part of the Trans-European Suture Zone, comprises a series of fault zones and major single faults, striking mainly subparallel to the SW margin of the Fennoscandian Shield. The deep-seated faults of Wiek, Nord Jasmund and Schaabe, which cross the northern part of Rügen Island and areas of the adjacent Baltic Sea from NW to SE, originated in the late Paleozoic. They are accompanied by younger faults, especially in the Pomeranian Bay, that were formed by Mesozoic tectonic processes. Based on reprocessed offshore seismic lines east of Rügen, a polyphase evolution for the Wiek Fault System is proposed. It implies changes in the stress field since the Caledonian Orogeny. Crustal extension in the Middle Devonian led to the formation of basins along the SW margin of Laurussia. Subsequent compressional movements, induced by the distant Variscan Orogeny, resulted in segmentation and block faulting of the Rügen Basin prior to the late Carboniferous. These Paleozoic faults were reactivated by Mesozoic extensional stress regimes. In addition, new en echelon faults were generated, contemporaneously with the formation of the Western Pomeranian Fault System. Since the Late Cretaceous (Africa–Iberia–Europe convergence), selected major normal faults have been reactivated as reverse faults.

The European portion of the Eurasian plate formed as a result of a complex series of tectonic events that included the Caledonian, Variscan, and Carpathian orogenies. These orogenic events occurred along the western margin of the East European craton (a portion of the paleocontinent Baltica). In recognition of the complexity of the rifting that formed this margin in the Neoproterozoic-Cambrian and the subsequent tectonic events along it, the region adjacent to this margin has been called the Trans-European suture zone. In order to understand the processes at work during these tectonic events, a series of large integrated geophysical and geological investigations built around large seismic refraction-experiments (POLONAISE'97, CELEBRATION 2000, ALP 2002, and SUDETES 2003) were conducted between 1997 and 2003. In this study, we compare the results of the two longest seismic profiles and their tectonic implications. These studies showed that lithospheric structure of the East European craton directly inboard of its margin is relatively uniform, and the crust consists of three layers below the sedimentary cover, and it is ∼45 km thick. The lithospheric mantle contains several reflectors, and its velocity is ∼8.2 km/s. In the Variscides (Paleozoic platform) of northern Poland along the Trans-European suture zone, the consolidated crust beneath the sedimentary cover consists of two distinct layers, and the total crustal thickness is 30–35 km. Within the core region of the Trans-European suture zone, the crust is ∼40 km thick, but most of its upper half is the sedimentary fill of the late Paleozoic and Mesozoic Polish trough, which is underlain by a thick sequence of older continental-margin volcanic and sedimentary units. The lithospheric mantle structure is complex and indicative of a plate collision under the Trans-European suture zone region, and it has seismic velocities that are generally higher than those of the East European craton. In the Carpathian region, the effects of younger collisions are present in addition to evidence of the Variscan orogeny. It is somewhat surprising that the crustal thickness beneath the Carpathians is 30–40 km, but it is not surprising that beneath the Pannonian Basin, an extensional feature, the crust is only 24–28 km thick. The thickest crust in this region (∼50 km) occurs under the rifted margin of the East European craton. The sedimentary cover in this region varies greatly in age and thickness. It is 1–3 km thick beneath the East European craton, 10 km thick the beneath Polish Basin/Lublin trough region, ∼18 km thick in the Carpathian foredeep, and 5–8 km thick beneath the Pannonian Basin. The velocity in the lithospheric mantle is 8.1–8.25 km/s beneath the East European craton, 8.2–8.4 km/s beneath the Variscides–Trans-European suture zone, and 7.8–8.0 km/s beneath Carpathian-Pannonian area. The crust and features in the lithospheric mantle appear to dip northward in this area. In northern Poland, the rifted southwestern margin of the East European craton is abruptly bounded by the Trans-European suture zone and ultimately the Variscides over a region that is only ∼100 km wide, while the collisional zone between the East European craton and the Carpathian-Pannonian area is ∼300 km wide. In both areas, the lithospheric structure observed suggests that the Caledonian, Variscan, and Carpathian orogenies in this area were relatively “soft” collisions that left the East European craton passive margin largely intact. The structural model of the transition between the Pannonian Basin–Carpathians and the East European craton indicates northward “old” subduction under Baltica (Jurassic–Early Cretaceous). However, the thinning of the Pannonian lithosphere could be explained as the result of extension and high heat flow, with “young” southward subduction or slab rollback to the east, which took place in the Tertiary (Miocene).

The Trans-European Suture zone in eastern Europe is a complex region that marks the suture of Phanerozoic western European terranes with the Precambrian East European craton. Because of sedimentary cover and the Baltic Sea, the nature of this suture is known primarily from geophysical studies. Seismic velocity and gravity models from earlier experiments indicate changes of crustal thickness from 28–35 km to 42–47 km across the Teisseyre-Tornquist zone from the Paleozoic platform of western Europe to the East European craton. Tectonic models suggest the presence of a Precambrian–early Paleozoic passive margin beneath the Teisseyre-Tornquist zone. The Holy Cross Mountains in southeastern Poland represent an anomalous crustal block whose origin and interaction with the East European craton is unknown. We have employed a new approach to quantitatively integrate (i.e., data fusion) industry-acquired drilling and seismic reflection data, as well as refraction data from the CELEBRATION 2000, POLONAISE ‘97, and Teisseyre-Tornquist zone experiments in a tomographic inversion. We find that it is feasible to integrate data of different resolutions in a tomographic inversion. Secondly, we constrained upper-crustal velocities within our study area to create a more completely resolved velocity structure. Thirdly, we modeled a uniform gravity data set to validate all available data and construct models of crustal structure across the Holy Cross Mountains region.