Compilation of a microtectonic observation data base for most of the data measured in the Pannonian Basin and surrounding orogens permits a detailed reconstruction of the Tertiary stress field evolution. Combination of tectonic observations, borehole, gravity and seismic data, palaeogeographic and stratigraphic information led to an understanding of fault kinematics and description of the structural evolution in seven major tectonic episodes. The first two episodes depict the kinematics of the two major separated blocks, the Eastern Alpine-Western Carpathian-Northern Pannonian (Alcapa) and the Southern Pannonian-Eastern Carpathian (Tisza-Dacia) microplates. A Mid-Eocene to Early Oligocene N-S compression led to contractional basin formation both in the foreland (Western Carpathians) and hinterland (Hungarian Palaeogene basins) of the orogenic wedge. Due to oblique convergence, the Palaeogene basins are generally asymmetric and often dissected by dextral tear faults. Northward advance of the Adriatic promontory initiated the separation of the Alcapa from the Southern Alps and its eastward extrusion. This process probably started during latest Oligocene and reached its climax during the Early Miocene. The main displacement was accommodated by dextral slip along the Periadriatic and Mid-Hungarian shear zones and during and after this tectonic episode Alcapa suffered 50° CCW rotation. At about the same time period the Tisza-Dacia block also experienced rotation of 60–80°, but clockwise. These opposite rotations resulted in the marked actual deviation of earlier compression axes, which are now N or NW in the Eastern Alps, WNW-ESE in the Western Carpathian-Pannonian domain and NE-SW in the Tisza-Dacia domains. Termination of rotations can be considered as the time for final amalgamation of the two separate blocks and the beginning of extensional tectonics in a single Pannonian unit. The Pannonian Basin system was born by rifting of back-arc style during the late Early and Mid-Miocene time. Extension was controlled by the retreat and roll-back of the subducted lithospheric slab along the Carpathian arc. Two corners, the Bohemian and Moesian promontories formed gates towards this free space. At both the northern and southern corners, broad shear zones developed. The initial NE-directed tension was gradually replaced by a later E- to SE-directed tension as a consequence of the progressive termination of subduction roll-back along the arc from the Western Carpathians towards the Southern Carpathians. There is growing evidence that an E-W-oriented short compressional event occurred during the earliest Late Miocene but during the most of the Late Miocene extension was renewed. Starting from the latest Miocene roll-back terminated everywhere and a compressional stress field has propagated from the Southern Alps gradually into the Pannonian Basin, and resulted in Pliocene (?) through Quaternary tectonic inversion of the whole basin system.

A three-dimensional model of the regional crustal architecture of the western Trans-Hudson Orogen, based on the interpretation of 590 km of deep-sounding seismic reflection data and a comparable length of existing seismic reflection information, is presented. The seismic images identify the regional geometry of the basal detachment zone (Pelican thrust) that separates juvenile allochthonous terranes from the underlying Archean microcontinent (Sask craton). The Sask Craton is inferred to have a minimum spatial extent of over 100 000 km2 with an associated crustal root that extends for 200 km along strike. During terminal collision, complete convergence of the Rae–Hearne and Superior continental blocks was precluded by the presence of the Sask Craton, resulting in the preservation of anomalous amounts of oceanic and associated sedimentary juvenile material. Along regional tectonic strike, consistency of crustal structure across the Rae–Hearne margin – Reindeer zone boundary is established. Several phases of tectonic development, including multistage subduction and continent–continent collision, are inferred for the western margin of the orogen. A bright, shallow (2–3.5 s two-way traveltime) band of reflectivity (Wollaston Lake reflector) imaged over ~150 000 km2 area is inferred to be a large post-orogenic mafic intrusion. A highly reflective, well-defined and structurally disturbed Moho discontinuity is mapped throughout the western Trans-Hudson Orogen. The present-day crustal architecture of the western Trans-Hudson Orogen is described in terms of the tectonic evolution within the region.

Seismic-reflection techniques have been applied in several studies over the last 20 years as a uranium-exploration tool within the Athabasca Basin and have been utilized to provide the larger structural context for known uranium deposits within the basin. At the crustal scale, deposits within the eastern Athabasca Basin are shown to be associated with deep-seated shear zones that originated during Trans-Hudson orogeny and have subsequently been reactivated during and subsequent to deposition of the basin-fill sandstones. Seismic properties of the Athabasca sandstones and underlying basement have been determined through in situ borehole measurements. Reflectivity within the sandstones is generally weak. Seismically recognizable signatures are primarily associated with variations in fracture density, porosity, and degree of silicification. The basement unconformity and regolith, a prime target of exploration, is widely imaged as it is characterized by variable but generally distinct reflectivity. Results from the McArthur River mine site suggest that the spatial coincidence of seismically imaged high-velocity zones and deep-seated faults that offset the unconformity may be a more broadly applicable exploration targeting tool. Three-dimensional (3-D) seismic imaging near existing ore zones can define the local structural controls on the mineralization and point the way to new targets, thus leading to more efficient exploration drilling programs. Furthermore, seismically generated structural maps of the unconformity and rock competence properties may play a significant role at the outset of mine planning.