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Electron microprobe analysis, stable isotope analysis, fluid inclusion thermometry, and coal rank, illite and chlorite crystallinity calculations were undertaken to determine metamorphic conditions of the Taveyanne formation of western Switzerland. Electron microprobe analyses for actinolite, epidote, phengite, chlorite, phrenite, pumpellyite, titanite and laumontite are presented.

Th KAIOsub2-MgO-SiOsub2-Hsub2O-Cosub2 system is a model for the processes of granulite-facies metamorphism, representing the simplest model for stability of biotite in subaluminous and metaluminous, quartz-saturated crustal rocks. There has been much controversy over the role of carbon dioxide in metamorphism and partial melting. New experiments have been performed, and findings show that the univariant reaction Ph1 + Qtz + F1 = En + Sa + melt is nearly coincident with the fluid-absent reaction in the COsub2 free subsystem.

Determining fluid flow patterns and sources is important to understanding crustal evolution. Stable isotope geochemistry is successfully used in fluid-rock interaction studies. The infiltration of water-rich fluids into marbles from Jervois, central Australia is described. Some marbles garnet grew when the deltasuper18O values of the host rock were changing, due to different fluid volumes needed to reset mineralogies and oxygen isotopes. Marbles outside the fluid-flow zones consisted of calcite + quartz + anorthite + diopside plus or minus phlogopite.

Geochronologic data from the Nanga Parbat-Haramosh Massif (NPHM), NW Pakistan, reveal high denudation and cooling rates for the NHPM over the past 10 million years (m.y.). Two phases of metamorphism over a period of 50 m.y. are also revealed for the NHPM. The initial phase of high pressure metamorphism was due to obduction of the Kohistan terrane. The following decompression metamorphism, at 3.3-4.0 Ma, resulted due to rapid denudation. The overall cooling age pattern within the massif gives an idea about the syntaxial growth and folding and faulting in the Nanga Parbat region.

Uranium-lead sphene analysis is a powerful tool for dating metamorphic events. Geochronological study of amphibolites and granite gneisses within the contact aureole of the Red Mountain pluton, Laramie anorthosite complex, Wyoming, reveals a 300 million year spread in 207Pb/206Pb ages. This range of ages resulted from two periods of sphene growth, corresponding to phases of regional and contact metamorphism, respectively. The ages were reset by thermal diffusion at high temperatures and the U-Pb ages recorded the new growth of sphene. Textural study distinguished the two phases of sphene.

The use of Sm-Nd and Rb-Sr isotopic data for two layered mafic complexes in the eastern Baltic Shield helps to study the effect of the age of host rocks and the post-crystallization metamorphic history on the isotopic signatures. Rb addition, during metamorphism 1.75-1.50 billion years ago, disturbed the Rb-Sr systems of minerals in the Olanga rocks. A mantle plume model with minor crustal and asthenospheric contamination explains the isotopic variations in Olanga. The undisturbed Sm-Nd systems of Burakovka are due to multiple magma injections, and complex mixing and contamination.

The mineralogical and stable isotope study of siliceous carbonate rocks from the Ballachulish aureole, Scotland, provides information about retrograde and prograde fluid flow during contact metamorphism. A model describes the infiltration of dolomites and limestones by CO2-H2O fluid and the subsequent alteration modes, reaction textures, and incompatibility between different minerals. Most of the univariant assemblages formed during retrograde metamorphism. The lack of stable isotope alteration of the carbonates explains the small values of prograde and retrograde time-integrated flux.

Two-dimensional pressure-temperature-time modeling facilitates the interpretation of the late Mesozoic and Cenozoic tectonic evolution of Eastern Alps. The short phase subduction of the South Penninic oceanic lithosphere began after crustal thickening of the Austro-Alpine upper plate nappe stack and its subsequent return to normal thickness. Temperature gradients and inverted metamorphic events are explained by this modeling technique. Reasons for a weak lithospheric core in the Eastern Alps are discussed.

A variety of deformational and metamorphic features at different stratigraphic levels build up the Jurassic structural record in the Pine Forest Range, Nevada, which is a part of the Mesozoic volcanic arc system. Structural analysis, supported by information from U-Pb zircon dating of two major plutons, suggests that regional shortening deformation occurred during Early Jurassic. Contrasting results from other parts of the arc system hint at a complex tectonic history of the western US Cordillera plate margin.

A study of western Adirondack Highlands, New York, shows the presence of minerals formed by moderate pressure metamorphism and anatexis from anorthosite intrusion. The monazite age indicates the occurrence of high temperature metamorphism for 1040-960 Ma. The zircon ages and metapelite's textural relations indicate anatexis for 1150 Ma. The presence of nelsonite indicates anorthosite intrusion during partial melting in the gneiss.

Complex discordance patterns are exhibited by the U-Pb isotopic relations in titanite and zircon of granulite and amphibolite gneisses in the Lewisian complex in NW Scotland. The complex discordance patterns reveal the presence of Early Proterozoic and multiple Late Archean crystallizations, Pb-loss event and overgrowth. The discordance patterns also indicate the occurrence of magmatism and metamorphism, associated with the magmatic and tectonic accretion in the continental arc setting. The metamorphic and magmatic processes are caused by the emplacement of granitic pegmatites and amphibolization of the granulites.

The thin shale interval of Witwatersrand Basin, South Africa, exhibits the first recorded occurrence of sudoite in Archaean rocks. The presence of metamorphic conditions above the Kaolimite to pyrophyllite transition reveals the sudoite stability. The Witwatersrand sudoite formed under a low-pressure from the Archaean successions. The bulk rock compositions indicate that the sudoite must have been subjected to post-burial alteration.

The Dabie Shan, China, is composed of sapphirine as inclusions with enstatite clinochlore, talc, gedrite, hornblende, corundum and phlogopite as minute garnets in the orthopyroxenites. Orthopyroxenites are found in the 50-meter- thick mafic-ultramafic domain in the Dabie Shan. Felsic gneiss consists of meter-scale intercalation of garnet-orthoxopyroxenite or -clinopyroxenite, eclogite and gneiss.

The Tongbai/Dabie Shan orogen in China shows an infracrustal crystalline rock abundant section of a Himalayan-type continent-continent collision zone. Sedimentary cover nappes and obducted ophiolites are absent in this zone. This orogen has a coherent tectonic unit of ultrahigh-pressure metamorphic rocks, made of crustal slices having various metamorphic origins. Continent-continent collision leads to subduction of continental lithosphere and sometimes it leads to the formation of diamond- and coesite-bearing crustal rocks.

Metamorphic and ophiolitic rocks in the orogenic belt of southeast Anatolia yield petrologic and stratigraphic data about the time and place of metamorphic unit evolution. The ophiolites represent the oceanic rocks formed during Late Cretaceous to Miocene time and metamorphic rocks represent oceanic and continental rocks. The metamorphic units provide data about nappe transportation phases that correspond to the development of the orogenic belt.

Dome-stage or backfold-deformation resulted in the formation of several structural features of the small-scale Acadian. Two stages of shearing existed in the Bronson Hill anticlinorium and the eastern side of the Monson Gneiss. Peak metamorphism preceded late-stage deformation during Acadian orogeny. There was a shift into orogen-parallel extension during this deformation. There may be a variation in the orientation of the direction of maximum extension at the backfold-stage uplift, from near vertical to near parallel and horizontal to the orogen at the stage of dome-formation.

A significant deformation exists in the Nizky Jesenik Mountains, which has carboniferous sedimentary rocks, and the Hruby Jesenik Mountains, which has Devonian crystalline and pre-Cambrian rocks. There is an overprinted magnetic fabric in the crystalline and sedimentary rocks. There is a ductile deformation due to slaty cleavage, as seen in the Andelska Hora formation and the Horni Benesov formation. A multistadial deformation development is exhibited by the Hruby Jesenik Mountains.