EXHUMATION MECHANISM CRITERIA

Exhumation along strike slip systems occurs by erosion in transpressional restraining bends and general zones of shortening/transpression, and by extension, commonly beneath detachments in transtensional releasing bends and general zones of extension/transtension. The former is slow and reflected in detritus of adjacent basins. The latter can be very fast and is revealed by the absence of footwall detritus in hanging wall basins The progressively deeper eastward erosion of the Venezuelan/Trinidadian coastal ranges in transpression along the dextral South Caribbean plate boundary is seen in the eastward-lengthening Cenozoic Maturin Basin. The Montagne Noire and several Pyreneean "mantled gneiss domes" formed in pull-apart offsets along strike-slip faults. More complicated orogen-parallel extension, during dextral transpression, exhumed the Penninic and Tauern Cores beneath, respectively, the Simplon and Brenner Detachments. In Southwest Norway Siluro-Devonian sinistral transtension including and south of the More-Trondelag Zone led to the extremely rapid unroofing of coesite-eclogites with constrictional fabrics beneath an extensional detachment (s) whose hanging wall carries synchronous sedimentary basins with not a single pebble of eclogite. A critical key to elucidating exhumation mechanisms is rock fabric and history.