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- 积分
- 17983
- 威望
- 17983
- 包包
- 26159
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The most heavily cratered terrains on Mercury exhibit
8 S7 q/ D. q- T9 j2 P; @a lower density of craters smaller than about 100 km in diameter than on the
* v. F8 e$ S6 W1 d$ VMoon, a deficit that has been attributed to resurfacing by formation of ancient - R( g5 z; n( m( ~& b! @
intercrater plains. Simone Marchi et al. used a crater areal density map
5 m. h! T8 v* c3 jbased on data from the MESSENGER spacecraft (the colour-coded foreground on 9 x( A$ h. b7 | ~
cover, with a global surface mosaic in the background) to locate the oldest ; a# } E/ W0 x$ u
surfaces on Mercury and interpret the crater populations in the framework of a
5 x! i1 R/ R5 j& e" irecent lunar crater chronology. They conclude that the oldest surfaces were ( p- u( G% k" T
emplaced just after the start of the Late Heavy Bombardment 4.0 to 4.1 billion
$ F) R3 A# _# R2 q/ \8 ]years ago. The large impact basins, not previously dated, yield a similar * \3 U/ a8 i' m( v" q; ]+ n
surface age. This agreement implies that resurfacing was global and due to 7 F: R1 y! u3 d6 Z
volcanism, perhaps aided by heavy bombardment as previously suggested. Cover:
# P9 i+ X8 G& r* M0 fSimone Marchi/MESSENGER data: NASA/JHUAPL/Carnegie Institution of Washington
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发表于 2013-7-5 23:43
发表于 2013-7-6 08:19
