A cone on Mercury: Analysis of a residual central peak encircled by an explosive volcanic vent
Journal
Date Issued
2015
Author(s)
Thomas, Rebecca J.
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Rothery, David A.
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Conway, Susan J.
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Anand, Mahesh
Description
Acknowledgements Rebecca Thomas acknowledges support via a PhD grant from the Science and Technology Facilities Council (UK) (Grant no. ST/K502212/1 ) and David Rothery acknowledges support from the UK Space Agency (Grant nos. PP/E002412/1 and ST/M002101/1 ) in preparation for the BepiColombo mission. This research was also supported by the Italian Space Agency (ASI) within the SIMBIOSYS Project (ASI-INAF agreement no. I/022/10/0 ). We gratefully acknowledge the developers of iSALE, including Gareth Collins, Kai Wnnemann, Dirk Elbeshausen, Boris Ivanov, and Jay H. Melosh (see www.iSALE-code.de). The image and MLA data used in this paper are available at the PDS Geosciences Node of Washington University, St. Louis, U.S.A. All other data are available from the authors on request.
Abstract
We analyse a seemingly-unique landform on Mercury: a conical structure, encircled by a trough, and surrounded by a 23,000 km2 relatively bright and red anomaly of a type interpreted elsewhere on the planet as a pyroclastic deposit. At first glance, this could be interpreted as a volcanically-constructed cone, but if so, it would be the only example of such a landform on Mercury. We make and test the alternative hypothesis that the cone is the intrinsic central peak of an impact crater, the rim crest of which is visible beyond the cone-encircling trough, and that the trough is a vent formed through explosive volcanism that also produced the surrounding bright, red spectral anomaly. We test this hypothesis by comparing the morphology of the cone and the associated landform assemblage with morphologically-fresh impact craters of the same diameter as the putative host crater, and additionally, by modelling the original morphology of such a crater using a hydrocode model. We show that the present topography can be explained by formation of a vent completely encircling the crater's central peak and also make the observation that explosive volcanic vents frequently occur circumferential to the central peaks of impact craters on Mercury. This indicates that, although this cone initially appears unique, it is in fact an unusually well-developed example of a common process by which impact-related faults localize magma ascent near the centre of impact craters on Mercury, and represents an extreme end-member of the resulting landforms.
Volume
108
Start page
108
Issn Identifier
0032-0633
Ads BibCode
2015P&SS..108..108T
Rights
open.access
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