Pyroxene Chemistry in Polymict Eucrite Northwest Africa 6475: Contrasts with Juvinas, Stannern and Igdi, and Evaluation of Models for Eucrite Magmatic Evolution
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چکیده
منابع مشابه
Petrology of the Unbrecciated Eucrite, Cumulus Hills 04049
Introduction: Eucrite meteorites represent earlyformed (~4.557-4.565 Ga) crustal basalts and basaltic to gabbroic cumulates from the howardite-eucritediogenite (HED) parent body or bodies (e.g., [1]). The HED are commonly thought to originate from the asteroid Vesta (e.g., [2-3]), although O-isotopes for eucrites [4] and diogenites [5] indicate more than one parent body. Approximately 85% of eu...
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Reliable quantitative mapping of minerals exposed on Vesta’s surface is crucial for understanding the crustal composition, petrologic evolution, and surface modification of the howardite, eucrite, and diogenite (HED) parent body. However, mineral abundance estimates derived from visible–near infrared (VIS–NIR) reflectance spectra are complicated by multiple scattering, particle size, and nonlin...
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We investigate the relationship between the petrology and visible–near infrared spectra of the unbrecciated eucrites and synthetic pyroxene–plagioclase mixtures to determine how spectra obtained by the Dawn mission could distinguish between several models that have been suggested for the petrogenesis of Vesta’s crust (e.g., partial melting and magma ocean). Here, we study the spectra of petrolo...
متن کاملNorthwest Africa 5415: a Howarditic Impact-melt Breccia with Zoned Relict Orthopyroxenes and Augites, and Corroded, Complexly Mantled Fo-59 Olivines
Introduction: The Northwest Africa (NWA) 5415 meteorite is unusual among HED meteorites for its clear manifestation of origin by pervasive, large-scale impact melting. A thin section from a relatively unweathered portion includes five relict olivines, all of which display similar reaction textures (pyroxene coronas) formed as a consequence of immersion of these grains in a melt on the Si-rich s...
متن کاملShock Induced Feldspar and Silica Transformation in Polymict Eucrite
Introduction: Howardite-eucrite-diogenite (HED) meteorites belong to the largest group of achondrites and originate from protoplanet 4 Vesta. The surface of Vesta has been extensively affected by impacts which brecciated and mixed eucrite and diogenite material to produce a regolith and formed large basins in the south pole region [1]. Shock features preserved in meteorites due to high-velocity...
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