Record Details

Dating Howardite Melt Clasts: Evidence for an Extended Vestan Bombardment?
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Author and Affiliation:
Cartwright, J. A.(Arizona State Univ., Ctr. for Meteorite Studies, Tempe, AZ, United States);
Hodges, K. V.(Arizona State Univ., School of Earth & Space Exploration, Tempe, AZ, United States);
Wadhwa, M.(Arizona State Univ., Ctr. for Meteorite Studies, Tempe, AZ, United States);
Mittlefehldt, D. W.(NASA Johnson Space Center, Houston, TX, United States)
Abstract: Howardites are polymict breccias that, together with eucrites and diogenites (HED), likely originate from the vestan surface (regolith/ megaregolith), and display a heterogeneous distribution of eucritic and diogenitic material. Melt clasts are also present alongside other regolithic features within howardites, and are noteworthy for their compositional variability and appearance. Melt clasts formed by impact events provide a snapshot of the timings and conditions of surface gardening and bombardment on the vestan surface. By dating such clasts, we aim to better constrain the timings of impact events on Vesta, and to establish whether the impact flux in the asteroid belt was similar to that on the Moon. As the Moon is used as the basis for characterising impact models of the inner solar system, it is necessary to verify that apparent wide-scale events are seen in other planetary bodies. In particular, the observed clustering of Apollo melt clast ages between 3.8-4.0 Ga has led to two hypotheses: 1) The Moon was subjected to a sudden event - 'Lunar Cataclysm' or period of 'Late Heavy Bombardment' (LHB), 2) The age cluster represents the end of an epoch of declining bombardment or 'Heavy Bombardment. No consensus has emerged regarding one or other hypothesis. We are testing these hypotheses by seeking evidence for such events in materials other than those derived from the Moon.
Publication Date: Mar 21, 2016
Document ID:
20160003507
(Acquired Mar 23, 2016)
Subject Category: LUNAR AND PLANETARY SCIENCE AND EXPLORATION
Report/Patent Number: JSC-CN-35237
Document Type: Conference Paper
Meeting Information: Lunar and Planetary Science Conference; 47th; 21-25 Mar. 2016; The Woodlands, TX ; United States
Meeting Sponsor: Lunar and Planetary Inst.; Houston, TX, United States
Financial Sponsor: NASA Johnson Space Center; Houston, TX, United States
Organization Source: NASA Johnson Space Center; Houston, TX, United States
Description: 2p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright; Distribution as joint owner in the copyright
NASA Terms: BRECCIA; CHRONOLOGY; LUNAR ROCKS; PETROLOGY; METEORITIC COMPOSITION; VESTA ASTEROID; LUNAR EVOLUTION; PLANETS; ROCKS; TIME MEASUREMENT; MOON
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