《自然》[Nature]13年7月4日出版pdf全文

nero1981

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The most heavily cratered terrains on Mercury exhibit 7 A) c) q4 B: n$ p" }2 ^2 z% i. J
a lower density of craters smaller than about 100 km in diameter than on the   P& E# H/ a+ y2 Q, |# v6 U
Moon, a deficit that has been attributed to resurfacing by formation of ancient ) W) X) O2 I1 H' ~  N% Q- i
intercrater plains. Simone Marchi et al. used a crater areal density map . Q/ }6 q$ Q$ @) ~
based on data from the MESSENGER spacecraft (the colour-coded foreground on " u. g/ O9 k4 O) Y  L9 ~, @7 D  a
cover, with a global surface mosaic in the background) to locate the oldest
+ [% {2 o3 p1 O$ O3 m; R1 B; qsurfaces on Mercury and interpret the crater populations in the framework of a 7 l# G* Z& X& B
recent lunar crater chronology. They conclude that the oldest surfaces were
/ f" X  a8 w6 r$ h$ o- t4 e: O" e$ cemplaced just after the start of the Late Heavy Bombardment 4.0 to 4.1 billion
0 K; z) j' ]# `* z" myears ago. The large impact basins, not previously dated, yield a similar
# B: R3 _( y4 |1 rsurface age. This agreement implies that resurfacing was global and due to 1 Q) Y& X: w# i9 G6 t) p) H: h
volcanism, perhaps aided by heavy bombardment as previously suggested. Cover: . m, ?( D( r0 N
Simone Marchi/MESSENGER data: NASA/JHUAPL/Carnegie Institution of Washington
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