Based on lithological, structural and geophysical characteristics, the Proterozoic Grenville Orogen of southern Ontario and New York has been divided into domains that are separated from each other by ductile shear zones. In order to constrain the timing of metamorphism, U-Pb ages were determined on metamorphic and igneous sphenes from marbles, calc-silicate gneisses, amphibolites, granitoids, ...

Seismic anisotropy has been widely observed in crust and mantle materials and plays a key role in the understanding of structure and flow patterns. Although seismic anisotropy can be explained by the crystal preferred orientation (CPO) of highly anisotropic minerals in the crust, that is, amphibole, experimental studies on the CPO of amphibole are limited. Here we present the results of novel e...

We investigated the crystal and structural behavior of several Cr-bearing spinels from the Archean chromitites of Amsaga (Mauritania). The chemical and structural data testified a retrograde metamorphism from amphibolite to greenschist facies, witnessed by relative changes in the amount of all the major oxides (Cr, Al, Mg, Fe2+, Fe3+), the relative proportion of Fe/Fetot as well as the structur...

Abstract Upper amphibolite-facies metamorphism in subduction zone rocks may occur under exceptional tectonic settings. Differentiating competing mechanisms for its occurrence requires carefully integrated, high-resolution thermobarometric and geochronologic studies of mélange with well-defined field relationships. We present new pressure, temperature, age data from the classic Cretaceous Catali...

The basement of eastern Mexico comprises Grenvillian-age granulite-facies metamorphic rocks. Oaxacan Complex represents the largest outcrop belt this in Mexico. In work, southwestern garnets are studied from a petrographical, geochemical, and geothermobarometrical perspective for first time. display different grain sizes nucleated polyphase evolution. almandine end member proportion is similar ...

High-precision dating of the metamorphic sole ophiolites can provide insight into tectonic evolution and subduction zone processes. To understand initiation beneath a young, well-preserved, well-characterized ophiolite, we performed coupled zircon laser-ablation inductively mass spectrometry (LA-ICP-MS) trace element analyses high-precision isotope dilution-thermal ionization (ID-TIMS) U-Pb on ...

Metamorphic index mineral zones, pressure– temperature (P–T) conditions, and CO2–H2O fluid compositions were determined for metacarbonate layers within the Wepawaug Schist, Connecticut, USA. Peak metamorphic conditions were attained in the Acadian orogeny and increase from 420 C and 6.5 kb in the low-grade greenschist facies to 610 C and 9.5 kb in the amphibolite facies. The index minerals olig...