A new dataset for the high-pressure to ultrahigh-pressure Western Gneiss Region allows the definition of distinct structural and petrological domains.Much of the study area is an E-dippinghomoclinewith E-plunging lineations that exposes progressively deeper, more strongly deformed, more eclogite-rich structural levels westward. Although eclogites crop out across the WGR, Scandian deformation is...

SUMMA R Y. In the Dahomeyan of the western Accra Plains marie gneisses, amphibolites, and orthoamphibolite dykes in granitic gneiss occur. During the latest recrystallization, metamorphic conditions ranged (north to south) from oligoclase--epidote amphibolite subfacies through andesineepidote amphibolite subfacies to at least the medium or upper part of the amphibolite facies. Chemical analyses...

[1] The Nordfjord area of western Norway hosts one of the best known provinces of ultrahigh-pressure (UHP) rocks in the world, yet the nature of the transition from the UHP rocks into surrounding amphibolite-facies crust has remained unclear. New thermobarometry of phengiteand kyanite-bearing eclogites shows that this transition is unbroken by major structures: the pressure and temperature grad...

Metamorphism along the southern margin of the Archean Superior Province has been historically attributed to the Penokean orogeny. A narrow corridor of amphibolite facies rocks north of the main suture does record 1.83–1.80 Ga metamorphic monazite U–Th–Pb ages that mark the culmination of arc accretion. However, subsequent widespread amphibolite facies metamorphism and associated magmatism is re...

Thermobarometry suggests that ultrahigh-pressure (UHP) to high-pressure (HP) rocks across the Western Gneiss Region ponded at the Moho following as much as 100 km of exhumation through the mantle and before exhumation to the upper crust. Eclogite across the c. 22 000 km study area records minimum pressures of c. 8–18 kbar and temperatures of c. 650–780 C. One orthopyroxene eclogite yields an UH...

The crystalline basement of New Zealand shows a chi-shaped combination of the straight Alpine Fault and a curved late Paleozoic continental margin, so that the plutonic basement of northern Fiordland converges toward the plane of the Alpine Fault. On the ground along Milford Sound the petrography suggests (1) a gradual change from amphibolite and granulite fades in the west to igneous fabrics d...

Extreme uplift associated with the formation of the 2.02 Ga Vredefort dome has exposed a substantial cross section through the crystalline early Archean basement complex rocks of the Kaapvaal craton. The rocks comprise polydeformed high-grade tonalite–trondhjemite–granodiorite (TTG) gneisses, migmatites and late-tectonic intrusive granitoids that straddle the upper amphibolite-to granulite–faci...

Metamorphic coesite and diamond in the Dabie Shan, eastern China, testify to subduction of continental crust to >100 km depth. Exhumation of these ultrahigh-pressure rocks through the crust encompassed two stages. (1) South-dipping foliation, southeastplunging stretching lineation, lineation-parallel isoclinal folds, and boudins indicate extreme subhorizontal shortening and subvertical extensio...