Mathematics – Logic
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufm.p13a1248a&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #P13A-1248
Mathematics
Logic
[5415] Planetary Sciences: Solid Surface Planets / Erosion And Weathering, [5470] Planetary Sciences: Solid Surface Planets / Surface Materials And Properties, [6225] Planetary Sciences: Solar System Objects / Mars, [6240] Planetary Sciences: Solar System Objects / Meteorites And Tektites
Scientific paper
Meteorites on the surfaces of other solar system bodies can provide natural experiments for monitoring weathering processes. In the case of Mars, clues to the more subtle aspects of water occurrence and reaction may be revealed by the effects of highly sensitive aqueous alteration processes, while physical processes may be recorded through aeolian abrasion effects. Over the past 2000 sols, the two Mars Exploration Rover (MER) spacecraft have formally identified a minimum of 11 meteorite candidates [1-3], with many more unofficial candidates likely, posing an intriguing set of questions concerning their chemical, mineralogical, and morphological conditions. Five meteorite candidates, including the newly discovered MER-B rock Block Island, and one confirmed meteorite [Meridiani Planum (MP; originally Heat Shield Rock)] [4] have been investigated with the rover arm instruments. All contain levels of ferric iron, which should not be present in pristine samples (i.e. without fusion crust and/or alteration phases). Moreover, preliminary morphologic evidence contributes to the case of possible chemical weathering in Block Island. Scrutiny of a Microscopic Imager (MI) mosaic of MP shows clear evidence for both localized aeolian sculpting, and the Widmanstätten pattern common to sliced and acid-etched surfaces of many iron-nickel meteorites. These latter features are manifest as millimeter-sized chevrons and subparallel linearities, most prominent across a partially brushed surface approximately 3 x 2 cm in area. Similar patterns are observed on a number of hot and cold desert meteorites (e.g. Drum Mountain and Ft. Stockton), and are attributed to physical ablation by sand grains differentially weathering the kamacite and taenite lamellae within the rock. A similar or identical process is interpreted as responsible for the features observed in MP. Other macro-scale features on MP are of questionable weathering origin. While some prefer a regmaglypt interpretation for the cavities in MP, others question whether differential weathering (either aqueous or physical) of softer sulfide (troilite) nodules or other inclusions such as schreibersite [5] in the metal matrix may be at least partly responsible. A discontinuous coating of darker material, interpreted to be oxide (though it is uncertain whether this is relict fusion crust or weathering rind), appears in the MI images also to have been polished and sculpted by abrasive forces. Laboratory experiments designed to address the requirements for iron shaping by wind abrasion would help provide constraints on the wind velocities involved in these processes. Preliminary results for Block Island display many features that are also consistent with aeolian abrasion. References: [1] Schröder C. et al. (2008) JGR 113, E06S22, doi:10.1029/2007JE002990. [2] Ashley J. W. et al. (2009) LPSC XL. [3] Schröder C. et al. (2009) LPSC XL. [4] Connolly H.C.J. et al. (2006) Meteoritical Bulletin #90, Meteoritics and Planet Sci. 41(9): p. 1383-1418. [5] Fleischer I. et al. (2009) Meteoritics and Planet Sci. 44, p. A70.
Ashley James W.
McCoy Timothy James
Schräder Christian
No associations
LandOfFree
Evidence for Physical Weathering of Iron Meteorite Meridiani Planum (Heat Shield Rock) on Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Evidence for Physical Weathering of Iron Meteorite Meridiani Planum (Heat Shield Rock) on Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Evidence for Physical Weathering of Iron Meteorite Meridiani Planum (Heat Shield Rock) on Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1767496