New outcrops created during the 1983 draining of Watauga Lake within the Mountain City window exposed the Little Pond Mountain thrust zone, marked by more than 200 m of Max Meadows-type carbonate breccia. The breccias are derived from the lower Rome Formation of the hanging wall, which is thrust 12 km over younger Rome beds. The upper boundary of the fault zone is gradational, beginning with intact shales and dolostones that become progressively disaggregated by boudinage and disharmonie folding, grading into a thick zone of polymict breccia in contact with Rome shales in the footwall. The brecciation is thrust related and tied to a particular stratigraphie horizon. Extreme competency contrast between brittlely deformed dolostones and shales, and interlayered, plastically deformed calcitic laminites is inconsistent with the current mineralogy and suggests the presence of weak evaporite-rich layers during deformation. Within the fault zone, these weak beds grade into the breccia matrix. Boudinaged dolostones and shales form clasts in a breccia mixed by mesoscopic isoclinal folding. Raindrop prints, ubiquitous mudcracks, and evaporite crystal molds in the lower Rome Formation are consistent with evaporative depositional environments. The breccias also exhibit features of evaporite solution-collapse breccias, including sedimentary cavity fillings. Pétrographie evidence for vanished evaporites includes anhydrite inclusions, evaporite crystal molds, and chert nodules pseudomorphous after anhydrite. A sparry calcite mosaic that apparently replaced evaporite laminites also forms the breccia matrix. The evaporite hypothesis is supported by interbedded dolostone and anhydrite discovered in the subsurface at the base of the Rome. The Watauga Lake breccias are postulated to be the result of décollement thrusting within a dolostone-anhydrite sequence at the base of the Rome Formation, producing a polymict evaporite-matrix breccia, which after deformation, underwent local solution collapse and widespread replacement of anhydrite by calcite. The Max Meadows breccias have long been considered unique, but a review of published work shows that these rocks and occurrences at Watauga Lake are identical in many ways to Rauhwacken (cornieules) of Europe and similar carbonate breccias in Nevada, the northern U.S. and Canadian Rockies, Ireland, and southern England, all of which have been interpreted as deformed carbonate-evaporite sequences. There are also similarities to carbonate breccias in Nova Scotia, northern Michigan, and the foreland of the Canadian Rockies that are purely the result of evaporite dissolution. These comparisons show that, in a given occurrence, thick carbonate breccias with similar diagenetic histories may originate from either décollement thrusting, evaporite dissolution, or a combination of the two processes.

Skardu Basin is a northwest-trending intermontane basin along the Indus River in the Karakoram Himalaya Mountains of Pakistan. Seismotectonic domain boundaries in the Karakoram Himalaya commonly cross lithologic and some older structural boundaries. Four major structural-seismotectonic domains exist in the Skardu area: the Himalayan seismic zone, characterized by thrust tectonics; the complex Hindu Kush–Pamir seismic zone; the Skardu quiet zone, characterized by strike-slip, extensional, and rotational tectonics with relatively little seismicity; and the southern edge of Eurasian lithosphere (Tarim–Kun Lun–Tibet) northeast of the Karakoram fault. The Skardu quiet zone is interpreted to be within the Himalayan thrust prism, above an aseismic detachment along which stable sliding or ductile faulting accommodates displacement. Stresses transmitted into the Skardu quiet zone laterally from the Himalayan seismic zone toward Eurasia and perhaps upward from the inferred basal detachment result in gross clockwise rotation, translation to the north-northwest, and a right-lateral sense of shear in the Skardu region. Landsat lineaments defined by major drainages suggest an array of fractures and faults in the Skardu quiet zone. Field data suggest that the lineaments generally reflect distributed shear along myriad small faults rather than displacement exclusively localized on major, discrete fault surfaces. Extensive glacial and fluvial erosion have accentuated trends characterized by relatively dense fracturing and faulting. At its confluence with the Indus at Skardu, the Shigar River flows through a breach that may have originated as a pull-apart structure similar to the pull-apart basin along the upper Sutlej River. The preserved vestiges of the upper Cenozoic Bunthang sedimentary sequence reflect Skardu’s early basin phase. Uplift along the Nanga Parbat–Haramosh syntaxis and along the northeastern margin of the Himalayan seismic zone may have contributed to the ponding of the Indus River in the Skardu Basin during Bunthang time. These axes of uplift may be related to movement of the Himalayan thrust wedge from a region of easy basal slip (Skardu quiet zone) to a region of increased resistance to basal slip (Himalayan seismic zone, or, in the case of the NP-H syntaxis, the Hindu Kush-Pamir seismic areas). Regional uplift within the Skardu quiet zone may reflect thickening of the thrust prism in response to variations in shear resistance along the detachment. Quaternary glacial lake beds located on the floor of Skardu Basin are generally undeformed in the western half of the basin. Local deformation within the lake beds in the eastern half of the basin is probably due to interaction with glaciers.

Abstract West Newfoundland was critical in developing the Wilson Cycle concept. Neoproterozoic rifting established a passive margin adjacent to the Iapetus Ocean. Ordovician (Taconian) arc–continent collision emplaced ophiolites and the thin-skinned Humber Arm Allochthon. Subsequent Devonian (Acadian) ocean closure produced basement-cutting thrust faults that control the present-day distribution of units. New mapping, and aeromagnetic and seismic interpretation, around Parsons Pond enabled the recognition of structures in poorly exposed areas. Following Cambrian to Middle Ordovician passive-margin deposition, Taconian deformation produced a flexural bulge unconformity. Subsequent extensional faults shed localized conglomerate into the foreland basin. The Humber Arm Allochthon contains a series of stacked and folded duplexes, typical of thrust belts. To the east, the Parsons Pond Thrust has transported shelf and foreland-basin units c. 8 km westwards above the allochthon. The Long Range Thrust shows major topographical expression but <1 km offset. Stratigraphic relationships indicate that most thrusts originated as normal faults, active during Neoproterozoic rifting, and subsequently during Taconian flexure. Devonian continental collision inverted the Parsons Pond and Long Range thrusts. Basement-cored fault-propagation folds in Newfoundland are structurally analogous to basement uplifts in other orogens, including the Laramide Orogen in western USA. Similar deep-seated inversion structures may extend through the northern Appalachians.

Yucca Mountain has been proposed as the site for the nation's first geologic repository for high-level radioactive waste. This chapter provides the geologic framework for the Yucca Mountain region. The regional geologic units range in age from late Precambrian through Holocene, and these are described briefly. Yucca Mountain is composed dominantly of pyroclastic units that range in age from 11.4 to 15.2 Ma. The proposed repository would be constructed within the Topopah Spring Tuff, which is the lower of two major zoned and welded ash-flow tuffs within the Paintbrush Group. The two welded tuffs are separated by the partly to nonwelded Pah Canyon Tuff and Yucca Mountain Tuff, which together figure prominently in the hydrology of the unsaturated zone. The Quaternary deposits are primarily alluvial sediments with minor basaltic cinder cones and flows. Both have been studied extensively because of their importance in predicting the long-term performance of the proposed repository. Basaltic volcanism began ca. 10 Ma and continued as recently as ca. 80 ka with the eruption of cones and flows at Lathrop Wells, ∼10 km south-southwest of Yucca Mountain. Geologic structure in the Yucca Mountain region is complex. During the latest Paleozoic and Mesozoic, strong compressional forces caused tight folding and thrust faulting. The present regional setting is one of extension, and normal faulting has been active from the Miocene through to the present. There are three major local tectonic domains: (1) Basin and Range, (2) Walker Lane, and (3) Inyo-Mono. Each domain has an effect on the stability of Yucca Mountain.