期刊
JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
卷 118, 期 2, 页码 335-346出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/jgre.20057
关键词
-
资金
- NASA's Discovery Program
- University of California, Los Angeles
- NASA's Dawn at Vesta Participating Scientists Program
- Italian Space Agency
- Max Planck Society
- German Space Agency (DLR)
- Planetary Science Institute under Jet Propulsion Laboratory
The estimated excavation depth of the huge Rheasilvia impact basin is nearly twice the likely thickness of the Vestan basaltic crust, so the mantle should be exposed. Spectral mapping by the Dawn spacecraft reveals orthopyroxene-rich materials, similar to diogenite meteorites, in the deepest parts of the basin and within its walls. Significant amounts of olivine are predicted for the mantles of bulk-chondritic bodies like Vesta, and its occurrence is demonstrated by some diogenites that are harzburgite and dunite. However, olivine has so far escaped detection by Dawn's instruments. Spectral detection of olivine in the presence of orthopyroxene is difficult in samples with < 25% olivine, and olivine in Rheasilvia might have been diluted during impact mixing or covered by the collapse of basin walls. The distribution of diogenite inferred from its exposures in and around Rheasilvia provides a geologic context for the formation of these meteorites, but does not clearly distinguish between a magmatic cumulate versus partial melting restite origin for diogenites. The former is favored by geochemical arguments, and crystallization in either a magma ocean or multiple plutons emplaced near the crust-mantle boundary is permitted by Dawn observations. Citation: McSween, H. Y., et al. (2013), Composition of the Rheasilvia basin, a window into Vesta's interior, J. Geophys. Res. Planets, 118, 335-346, doi:10.1002/jgre.20057.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据