Temperatures and cooling rates recorded by the New Caledonia ophiolite: implications for cooling mechanisms in young forearc sequences.
نویسندگان
چکیده
Abstract To unveil how forearc lithosphere cools and re‐equilibrates, we carried out a comprehensive geothermometric investigation of the New Caledonia ophiolite, which represents rare example proto‐arc section generated during subduction infancy. A large data set, including more than 80 samples (peridotites mafic‐ultramafic intrusives), was considered. Closure temperatures calculated for lherzolites using slow (T REE‐Y ) fast diffusing Ca‐in‐Opx , T BKN Ca‐in‐Ol Ol‐Sp geothermometers provide some highest values ever documented ophiolitic peridotites, akin to modern sub‐oceanic mantle. Cooling rates deduced from yield ≈10 −3 °C/y, similar those obtained with . These features are consistent post‐melting history emplacement, possibly along transform fault, thermal re‐equilibration via conduction. Cpx‐free harzburgites register high‐T evolution, followed by quenching obduction. The relatively high cooling computed (≈10 °C/y) atypical this geodynamic setting, mirroring development an ephemeral system, uplift emplacement Peridotite Nappe. Temperature profiles across crust‐mantle transect point closure temperatures, limited variations depth. results indicative injection crystallization non‐cogenetic magma batches in lithosphere, at −4 –10 °C/y. Our study shows that conditions recorded sequences intimately related specific areal processes previous lithospheric evolution. Thus, detailed sampling exhaustive knowledge geological background critical unravel mechanisms setting.
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ژورنال
عنوان ژورنال: Geochemistry Geophysics Geosystems
سال: 2022
ISSN: ['1525-2027']
DOI: https://doi.org/10.1029/2021gc009859