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8 results on '"Nestola, F."'

5. Protogenetic garnet inclusions and the age of diamonds

Author

Nestola, F., primary, Jacob, D.E., additional, Pamato, M.G., additional, Pasqualetto, L., additional, Oliveira, B., additional, Greene, S., additional, Perritt, S., additional, Chinn, I., additional, Milani, S., additional, Kueter, N., additional, Sgreva, N., additional, Nimis, P., additional, Secco, L., additional, and Harris, J.W., additional

Published
2019
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7. Fossil subduction recorded by quartz from the coesite stability field.

Author

Alvaro, M., Mazzucchelli, M. L., Angel, R. J., Murri, M., Campomenosi, N., Scambelluri, M., Nestola, F., Korsakov, A., Tomilenko, A. A., Marone, F., and Morana, M.

Subjects
*FOSSILS, *METAMORPHIC rocks, *ELASTICITY, *GARNET, *CHEMICAL equilibrium, *MINERAL properties, *QUARTZ
Abstract

Metamorphic rocks are the records of plate tectonic processes whose reconstruction relies on correct estimates of the pressures and temperatures (P-T) experienced by these rocks through time. Unlike chemical geothermobarometry, elastic geobarometry does not rely on chemical equilibrium between minerals, so it has the potential to provide information on overstepping of reaction boundaries and to identify other examples of non-equilibrium behavior in rocks. Here we introduce a method that exploits the anisotropy in elastic properties of minerals to determine the unique P and T of entrapment from a single inclusion in a mineral host. We apply it to preserved quartz inclusions in garnet from eclogite xenoliths hosted in Yakutian kimberlites (Russia). Our results demonstrate that quartz trapped in garnet can be preserved when the rock reaches the stability field of coesite (the high-pressure and hightemperature polymorph of quartz) at 3 GPa and 850 °C. This supports a metamorphic origin for these xenoliths and sheds light on the mechanisms of craton accretion from a subducted crustal protolith. Furthermore, we show that interpreting P and T conditions reached by a rock from the simple phase identification of key inclusion minerals can be misleading. [ABSTRACT FROM AUTHOR]

Published
2020
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8. Depth of diamond formation obtained from single periclase inclusions

Author

Mattia L. Mazzucchelli, Federica Marone, Matteo Alvaro, Simone Morganti, Mark T. Hutchison, Paolo Nimis, Chiara Anzolini, Andrea Gianese, Fabrizio Nestola, Jeff W. Harris, Marcello Campione, Anzolini, C, Nestola, F, Mazzucchelli, M, Alvaro, M, Nimis, P, Gianese, A, Morganti, S, Marone, F, Campione, M, Hutchison, M, and Harris, J

Subjects
GEO/07 - PETROLOGIA E PETROGRAFIA, 010504 meteorology & atmospheric sciences, depth, Metallurgy, periclase, Diamond, Geology, super-deep diamond, geobarometry, elasto-plasticity, engineering.material, 010502 geochemistry & geophysics, diamond, periclase, inclusion, depth, 01 natural sciences, GEO/06 - MINERALOGIA, inclusion, FIS/01 - FISICA SPERIMENTALE, diamond, engineering, Periclase, 0105 earth and related environmental sciences
Abstract

Super-deep diamonds (SDDs) are those that form at depths between ~300 and ~1000 km in Earth's mantle. They compose only 1% of the entire diamond population but play a pivotal role in geology, as they represent the deepest direct samples from the interior of our planet. Ferropericlase, (Mg,Fe)O, is the most abundant mineral found as inclusions in SDDs and, when associated with low-Ni enstatite, which is interpreted as retrogressed bridgmanite, is considered proof of a lower-mantle origin. As this mineral association in diamond is very rare, the depth of formation of most ferropericlase inclusions remains uncertain. Here we report geobarometric estimates based on both elasticity and elastoplasticity theories for two ferropericlase inclusions, not associated with enstatite, from a single Brazilian diamond. We obtained a minimum depth of entrapment of 15.7 (±2.5) GPa at 1830 (±45) K (~450 [±70] km depth), placing the origin of the diamond-inclusion pairs at least near the upper mantle-transition zone boundary and confirming their super-deep origin. Our analytical approach can be applied to any type of mineral inclusion in diamond and is expected to allow better insights into the depth distribution and origin of SDDs.

Published
2019

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