Extensional troughs in the Caloris Basin of Mercury: Evidence of lateral crustal flow

Thomas R. Watters, Francis Nimmo, Mark Robinson

Research output: Contribution to journalArticle

34 Citations (Scopus)

Abstract

Thirty years ago Mariner 10 revealed extensional troughs that form giant polygons in the floor material of the Caloris impact basin, Mercury. The polygonal troughs occur in the interior of the basin and overprint wrinkle ridges formed in an earlier stage of compression. In contrast, lunar and martian basins exhibit extensional troughs that are circumferential and confined to basin margins. Loading by basin-filling material can explain the extensional and compressional features seen in deformed lunar and martian basins, but not the existence of the Caloris polygonal troughs. Here we suggest that the Caloris troughs formed from late-stage basin uplift and extension due to lateral now of a relatively thick crust toward the basin center. If such lateral flow occurs, the resulting timing, location, and magnitude of the extensional stresses predicted by our model are consistent with those inferred from the polygonal troughs. These results are not strongly dependent on the degree of lateral flow or the assumed crustal rigidity. For a dry plagioclase rheology and likely radiogenic heat fluxes, the crustal thickness around Caloris is 90-140 km. Similar late-stage uplift and extension probably do not occur in basins on the Moon and Mars because their crusts are too thin to allow analogous lateral flow.

Original languageEnglish (US)
Pages (from-to)669-672
Number of pages4
JournalGeology
Volume33
Issue number8
DOIs
StatePublished - Aug 2005
Externally publishedYes

Fingerprint

trough
basin
uplift
crust
mercury
crustal thickness
polygon
rigidity
rheology
Moon
heat flux
Mars
plagioclase
compression

Keywords

  • Caloris Basin
  • Crustal flow
  • Mercury
  • Tectonics
  • Uplift

ASJC Scopus subject areas

  • Geology

Cite this

Extensional troughs in the Caloris Basin of Mercury : Evidence of lateral crustal flow. / Watters, Thomas R.; Nimmo, Francis; Robinson, Mark.

In: Geology, Vol. 33, No. 8, 08.2005, p. 669-672.

Research output: Contribution to journalArticle

Watters, Thomas R. ; Nimmo, Francis ; Robinson, Mark. / Extensional troughs in the Caloris Basin of Mercury : Evidence of lateral crustal flow. In: Geology. 2005 ; Vol. 33, No. 8. pp. 669-672.
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