Abstract Recognition and subsequent study of the syn-convergent low-angle normal faults and shear zones – the South Tibetan Detachment System (STDS) – that form the upper boundary of the Himalayan mid-crust fundamentally changed views of how the Himalayan orogenic system developed. This paper reviews the past four decades of discovery and major advances in our understanding of the detachment system. Significantly conflicting maps of the fault trace, as well as proposed extensions of the detachment system up to hundreds of kilometres both up and down dip of the main fault trace, call for a unifying definition of the detachment system based on structural criteria. The different proposed models for the formation of the STDS during tectonic evolution of the Himalayan orogen are compared. Finally, critical outstanding questions about the origin, extent and character of the detachment system are identified and point to future directions for research.

Abstract Gneiss domes in the Himalaya and southern Tibet record processes of crustal thickening, metamorphism, melting, deformation and exhumation during the convergence between the Indian and Eurasian plates. We review two types of gneiss domes: North Himalayan gneiss domes (NHGD) and later domes formed by orogen-parallel extension. Located in the southern Tibetan Plateau, the NHGD are cored by granite and gneiss, and mantled by the Tethyan sedimentary sequence. The footwall of these were extruded southwards from beneath the Tibetan Plateau and subsequently warped into a domal shape. The second class of domes were formed during displacement on normal-sense shear zones and detachments that accommodated orogen-parallel extension during the Late Miocene. In some cases, formation of these domes involved an early stage of southwards-directed extrusion prior to doming. We review evidence for orogen-parallel extension to provide context for the formation of these gneiss domes. Compilations of pressure–temperature–time–deformation data and temperature–time paths indicate differences between dome types, and we accordingly propose new terminology. Type 1 domes are characterized by doming as an artefact of post-high-temperature exhumation processes in the Middle Miocene. Type 2 domes formed in response to exhumation during orogen-parallel extension in the Late Miocene that potentially post-dates south-directed extrusion.