title: Volcanism on Mercury: evidence from the first MESSENGER flyby.
abstract: The origin of plains on Mercury, whether by volcanic flooding or impact ejecta ponding, has been controversial since the Mariner 10 flybys (1974-75). High-resolution images (down to 150 meters per pixel) obtained during the first MESSENGER flyby show evidence for volcanic vents around the Caloris basin inner margin and demonstrate that plains were emplaced sequentially inside and adjacent to numerous large impact craters, to thicknesses in excess of several kilometers. Radial graben and a floor-fractured crater may indicate intrusive activity. These observations, coupled with additional evidence from color images and impact crater size-frequency distributions, support a volcanic origin for several regions of plains and substantiate the important role of volcanism in the geological history of Mercury.
authors.affiliation: Department of Geological Sciences, Brown University, Providence, RI 02912, USA. James_Head@brown.edu
authors.forename: James W
authors.initials: JW
authors.lastname: Head
authors.forename: Scott L
authors.initials: SL
authors.lastname: Murchie
authors.forename: Louise M
authors.initials: LM
authors.lastname: Prockter
authors.forename: Mark S
authors.initials: MS
authors.lastname: Robinson
authors.forename: Sean C
authors.initials: SC
authors.lastname: Solomon
authors.forename: Robert G
authors.initials: RG
authors.lastname: Strom
authors.forename: Clark R
authors.initials: CR
authors.lastname: Chapman
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Watters
authors.forename: William E
authors.initials: WE
authors.lastname: McClintock
authors.forename: David T
authors.initials: DT
authors.lastname: Blewett
authors.forename: Jeffrey J
authors.initials: JJ
authors.lastname: Gillis-Davis