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.

In southeast Karakorum (northwest Himalaya, Pakistan), kilometric size migmatitic domes were exhumed in a context of north-south shortening during Neogene times. The domes are characterized by a conical shape, and ductile deformation criteria indicate both radial expansion and extrusion of the migmatitic core relative to the surrounding gneisses. Most of the domes are aligned along the dextral, strike-slip Shigar fault that is parallel to the N130°E Karakorum fault. Along the Shigar fault, exhumation of the domes is mainly vertical with a slight dextral component. We propose that the high temperature exhumation of the domes is due to diapiric ascent of the molten mid-crust helped by the compressive regime. The localization of the initial diapir was controlled by crustal-scale vertical structures parallel to the Karakorum fault. The later stage of exhumation in mid to low temperature conditions was related to the uplift and erosion of the whole southeastern Karakorum by crustal-scale east-west folding. In south Tibet, the westward prolongation of south Karakorum, Neogene crustal melting is also supported by geophysical data and volcanism, but mid-crustal rocks have not been exhumed. This difference between the amount of exhumation in south Karakorum and south Tibet could be related to the transpressive context of south Karakorum inducing a strain partitioning between the N130°E faults and east-west folding. Such partitioning produces heterogeneous uplift in this area. Moreover, zones of rapid uplift rate are associated with erosion due to the high incision rate of the large Shyok and Braldu rivers and the large Biafo-Hispar and Concordia glaciers in south Karakorum.

Abstract Rock avalanches have been widespread in the Karakoram Himalaya. More than 100 events have been identified in recent surveys and they include the largest catastrophic landslides known in the region. Some occurred in the present-day glacierized zone and during the past decade. Most have been identified and reconstructed from more or less ancient deposits at lower elevations. The incidences of these deposits and features that place them in the general class of rock-avalanche fragmentites are described. However, the main focus is on certain morphological and sedimentary phenomena that reflect interactions of rock avalanches with rugged terrain. In most cases, relations between runout path and geometry of opposing valley walls and interfluves have had major effects on the overall shape, surface morphology, and internal structures of the deposits. In some cases there are complex interactions with erodible substrates. Further complications arise from later erosion and burial of rockavalanche deposits, and the large changes they bring about in other geomorphic conditions. Styles of rock avalanche are proposed based upon the configuration of depositional complexes and their relations to surrounding topography, especially to local valley systems. The analysis and terminology for such topography-constrained forms are developed, in particular, from the work of Albert Heim. An understanding of these forms provides a useful guide to field identification and reconstruction of past rock avalanches in rugged mountain valleys, and necessary background for assessing future risks from catastrophic landslides.