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Presently, little is known about the zircon age–Hf isotope record of (meta)sedimentary rocks exposed in the southernmost part of the Mid-German Crystalline Zone and adjacent Rhenohercynian Domain, preventing detailed reconstructions of the geodynamic evolution in Central Europe. In this study, such data are presented from Late Devonian to Viséan greywackes and granite gneisses of the Palatinate Forest (Mid-German Crystalline Z...
Timescale of evolution of a late archean collision zone from Coorg, S. India: constraints from zircon and garnet geochronologyNARA Subscribed
Petrology, geochemistry and geochronology of a metapelite (sillimanite-garnet-biotite-plagioclase-quartz) from the vicinity of the Archean Mercara Shear Zone in Coorg, S. India show that metamorphism at temperatures > 850 °C occurred between 2700–3300 Ma (Phase equilibria, thermobarometry, U-Pb dating of zircons and Lu-Hf dating of garnets). Subsequently, the rocks experienced thermal events at lower temperatures at 2400-2600...
Authigenic growth of monazite, xenotime, rutile and zircon by fluid-rock interaction in the Southern Serra do Espinhaço, BrazilNARA Subscribed
The minerals zircon, monazite, xenotime and rutile commonly occur in metasedimentary rocks as detrital but also authigenic grains, which can result from different fluid-driven processes. In this study such processes are investigated on the basis of detailed petrographic observations, mineral-geochemical data, and results of in situ U-Pb dating and Nd isotope analyzes in a kaolinitized micaschist. The data provide evidence for...
Eclogite and omphacitite xenoliths of the Navajo Volcanic Field (NVF) provide a unique opportunity to study processes in an oceanic slab down to subarc depths. However, ambiguities remained about protolith origin, prograde metamorphic conditions, and metasomatic processes, which we address here with new geothermobarometric and in-situ U-Pb data. The earliest garnet (53.4 ± 4.8 Ma), omphacite, and phengite generations yielded c...
The effect of high-pressure metasomatism on the boron isotope signature of subducted oceanic crust in the Raspas Complex (Ecuador)NARA Subscribed
Boron abundances and B isotopic compositions of well-characterized blueschists and eclogites from the Raspas Complex (Ecuador) were analyzed to improve the use of boron as a tracer for recycling at convergent margins. The MORB-type eclogite interacted with internally-derived fluids released from metabasalt during the transition from blueschist to eclogite, with input from sediments. During metasomatism, B was gradually leached...