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Volcanism on Mercury: Evidence from the first MESSENGER flyby for extrusive and explosive activity and the volcanic origin of plains

Head, James W. and Murchie, Scott L. and Prockter, Louise M. and Solomon, Sean C. and Chapman, Clark R. and Strom, Robert G. and Watters, Thomas R. and Blewett, David T. and Gillis-Davis, Jeffrey J. and Fassett, Caleb I. and Dickson, James L. and Morgan, Gareth A. and Kerber, Laura (2009) Volcanism on Mercury: Evidence from the first MESSENGER flyby for extrusive and explosive activity and the volcanic origin of plains. Earth and Planetary Science Letters, 285 (3-4). pp. 227-242. ISSN 0012-821X.

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The first MESSENGER flyby of Mercury obtained images of 21% of the surface not seen by Mariner 10, including the center and western half of the Caloris basin and regions near the terminator that show details of the nature of smooth and intercrater plains. These new data have helped to address and resolve a series of longstanding questions on the existence and nature of volcanism on Mercury and the distribution of volcanic materials. Data from the Mercury Dual Imaging System (MDIS) on the MESSENGER spacecraft have shown the following: (1) Numerous volcanic vents, in the form of irregularly shaped rimless depressions, are concentrated around the interior edge of the Caloris basin. (2) These vents appear to be sources for effusive volcanism that in one case built a shield in excess of 100 km in diameter and in some cases formed bright haloes around the vents that are interpreted to represent pyroclastic eruptions. (3) Lobate margins of plains units, seen previously in Mariner 10 data, are documented in MESSENGER images with more clarity and are often distinctive in morphology and color properties, supporting the interpretation that these features are the edges of lava flow units. (4) The interior of the Caloris basin is filled with plains units spectrally distinctive from the rim deposits, and comparison with the lunar Imbrium basin and superposed impact crater stratigraphy provide evidence that these units are volcanic in origin; detailed differences in the mineralogy of lava flow units, so prominent in Imbrium, are not seen in the Caloris interior. (5) Some of the smooth plains surrounding the exterior of the Caloris basin show distinct differences in color and morphological properties, supporting a volcanic origin. (6) Some smooth and intercrater plains units distant from the Caloris basin show evidence of flooding and embayment relations unrelated to Caloris ejecta emplacement; local and regional geological and color relationships support a volcanic origin for these plains. (7) Large impact craters show a sequence of embayment of interior floor and exterior ejecta deposits that supports a volcanic origin for the embayment and filling processes. (8) Crater embayment and flooding relationships in selected areas suggest volcanic plains thicknesses of many hundreds of meters and local thicknesses inside impact craters of up to several kilometers. (9) Impact crater size–frequency distributions for Caloris exterior deposits, including the facies of the Caloris Group and relatively high- and low-albedo smooth plains, show that they are younger than plains interior to Caloris and thus must be dominantly the product of post-Caloris volcanism. These new data provide evidence that supports and confirms earlier hypotheses from Mariner 10 data that volcanism was important in shaping the surface of Mercury. The emerging picture of the volcanic style of Mercury is similar to that of the Moon, the other small, one-plate planetary body: there are no major shield volcanoes (e.g., comparable to Tharsis Montes on Mars), shallow magma reservoirs are rare, and there is little evidence for surface deformation or long-lived volcanic sources related to sites of upwelling mantle. The close association of volcanic plains and surface deformation features suggests that future observations and analyses can help document the relation between the volcanic flux and the evolving state and magnitude of stress in the lithosphere of Mercury.

Item Type:Article
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Head, James W.0000-0003-2013-560X
Murchie, Scott L.0000-0002-1616-8751
Fassett, Caleb I.0000-0001-9155-3804
Additional Information:© 2009 Elsevier B.V. Accepted 4 March 2009; Available online 28 April 2009. We gratefully acknowledge the personnel of the Johns Hopkins University Applied Physics Laboratory, who have planned and executed the MESSENGER mission. Without their dedication and perseverance, this analysis would not have been possible. We thank Kris Becker, Mark Robinson, Brett Denevi, and all those who worked long and hard to process and calibrate the MDIS data. The careful reviews by Mark Cintala and an unidentified reviewer helped to improve the manuscript and are gratefully acknowledged. The MESSENGER Project is supported by the NASA Discovery Program under contracts NASW-00002 to the Carnegie Institution of Washington and NAS5-97271 to the Johns Hopkins University Applied Physics Laboratory.
Funding AgencyGrant Number
Subject Keywords:Mercury; volcanism; plains; Caloris basin; MESSENGER
Issue or Number:3-4
Record Number:CaltechAUTHORS:20161130-100936819
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Official Citation:James W. Head, Scott L. Murchie, Louise M. Prockter, Sean C. Solomon, Clark R. Chapman, Robert G. Strom, Thomas R. Watters, David T. Blewett, Jeffrey J. Gillis-Davis, Caleb I. Fassett, James L. Dickson, Gareth A. Morgan, Laura Kerber, Volcanism on Mercury: Evidence from the first MESSENGER flyby for extrusive and explosive activity and the volcanic origin of plains, Earth and Planetary Science Letters, Volume 285, Issues 3–4, 15 August 2009, Pages 227-242, ISSN 0012-821X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72436
Deposited By: Tony Diaz
Deposited On:30 Nov 2016 19:40
Last Modified:09 Mar 2020 13:19

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