Altersbestimmung des prograden Metamorphismus von ozeanischen Hochdruck-Gesteinen durch die Kombination von der Lawsonit- und Granat 176Lu-176Hf-Geochronologie: Eine Durchführbarkeitsstudie (Halilbagi-Einheit, Zentralanatolien)

• Antragsteller: Dr. Amaury Pourteau
• Fachliche Zuordnung: Mineralogie, Petrologie und Geochemie
• Förderung: Förderung von 2013 bis 2016
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 237640821

Well-preserved high-pressure metamorphosed (HP) oceanic rocks now exposed at the Earth s surface constitute premier natural archives of subduction processes. Deciphering their prograde metamorphic history, in terms of pressure (P) and temperature (T) changes through time (t), can provide crucial information on the thermal, mechanical and chemical evolution of subduction zones. Recent advances in the 176Lu-176Hf dating method have made it possible to obtain robust and precise growth ages of garnet and lawsonite, which commonly form in such rocks during prograde to peak stages. This pilot project aims at testing the feasibility of combining, in individual samples, 176Lu-176Hf geochronology on both lawsonite and garnet, which are preferential hosts for heavy rare-earth elements (including Lu, the parent element) among blueschist- and eclogite-facies assemblages, respectively. This novel approach shall rely on a detailed petrological study of the lawsonite-garnet-bearing assemblages (textural relations, major and trace element distribution, specific thermobarometry), which will allow unravelling mineral growth sequences and Lu partitioning between cogenetic phases. Thence, 176Lu-176Hf geochronology shall be performed on a selection of samples containing lawsonite and/or garnet. This study will be focused on the Halilbagi Unit of Central Anatolia, which encompasses among the best-preserved lawsonite-garnet-bearing parageneses worldwide and is already well understood in terms of phase relations, P-T paths, and bulk rock geochemistry.

• DFG-Verfahren: Sachbeihilfen
• Beteiligte Personen: Professor Dr. Roland Oberhänsli; Professor Dr. Erik Scherer; Dr. Alexander Schmidt