Bedrock formation at Meridiani Planum (Reply)

Thomas M. McCollom () and Brian M. Hynek
Additional contact information
Thomas M. McCollom: Center for Astrobiology, University of Colorado
Brian M. Hynek: Laboratory for Atmospheric and Space Physics, University of Colorado

Nature, 2006, vol. 443, issue 7107, E2-E2

Abstract: Abstract Squyres et al .1 contend that our proposed volcanic origin for Meridiani Planum2 is inconsistent with more recently obtained data3. But although the new data reveal some variation in chemical composition, this variation is small (Fig. 1a) and mainly due to modest variations in magnesium and sulphur, with concentrations of the other elements remaining essentially constant3. In a volcanic model, this variation can be readily explained by mobilization of highly soluble magnesium sulphate salts during the later stages of alteration and diagenesis (Fig. 1a), as in the sedimentary/evaporite model in which sediments that were initially deposited with uniform composition are subsequently modified3,4,5. Although morphological features in the bedrock may be consistent with aeolian and fluvial origins6, this interpretation is not unique, particularly as features with similar grain size, sorting and morphology are seen in base surge deposits2,7,8,9. Neither chemical nor morphological data therefore preclude a volcanic origin. Figure 1 Ternary diagrams showing relative molar abundances of major elements for Meridiani bedrock. Diagrams include data discussed by Squyres et al.1 and typical martian basalts2. a, In a volcanic scenario2, bedrock compositions are attributable to reaction of basaltic ash with sulphuric acid from volcanic vapours. Minor scattering among compositions can be accounted for by mobilization of magnesium sulphate salts in the later stages of alteration (arrows). b, In a sedimentary/evaporite scenario, extrapolation from bedrock compositions to remove sulphate salts would require the original siliciclastic component to be substantially depleted in divalent cations and enriched in Si + Al relative to martian basalt12.

Date: 2006
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.nature.com/articles/nature05213 Abstract (text/html)
Access to the full text of the articles in this series is restricted.

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:nat:nature:v:443:y:2006:i:7107:d:10.1038_nature05213

Ordering information: This journal article can be ordered from
https://www.nature.com/

DOI: 10.1038/nature05213

Access Statistics for this article

Nature is currently edited by Magdalena Skipper

More articles in Nature from Nature
Bibliographic data for series maintained by Sonal Shukla () and Springer Nature Abstracting and Indexing ().