Properties and distribution of paired candidate stony meteorites at Meridiani Planum, Mars

Abstract

[1] The Mars Exploration Rover Opportunity investigated four rocks, informally dubbed Barberton, Santa Catarina, Santorini, and Kasos, that are possible stony meteorites. Their chemical and mineralogical composition is similar to the howardite, eucrite, and diogenite group but with additional metal, similar to mesosiderite silicate clasts. Because of their virtually identical composition and because they appear to represent a relatively rare group of meteorites, they are probably paired. The four rocks were investigated serendipitously several kilometers apart, suggesting that Opportunity is driving across a larger population of similar rock fragments, maybe a meteorite strewn field. Small amounts of ferric Fe are a result of weathering. We did not observe evidence for fusion crusts. Four iron meteorites were found across the same area. Although mesosiderites are stony irons, a genetic link to these irons is unlikely. The stony meteorites probably fell later than the irons. The current atmosphere is sufficiently dense to land such meteorites at shallow entry angles, and it would disperse fragments over several kilometers upon atmospheric breakup. Alternatively, dispersion by spallation from an impacting meteoroid may have occurred. Santa Catarina and a large accumulation of similar rocks were found at the rim of Victoria crater. It is possible that they are associated with the impactor that created Victoria crater, but our limited knowledge about their distribution cannot exclude mere coincidence.

Amazonian chemical weathering rate derived from stony meteorite finds at Meridiani Planum on Mars

“…Although they were discovered serendipitously dispersed across almost 10 km, their chemical and mineralogical composition is virtually identical789. Their chemistry is most similar to the HED group of meteorites albeit with an elevated (Fe, Ni) metal content78. They thus resemble the silicate component of mesosiderites, which are a group of stony-iron meteorites7.…”

“…Santorini and Kasos are ∼1.5 and ∼3.3 km south of Victoria crater, respectively, in large rippled terrain. Because the meteorites appear paired based on their chemistry8, they may be part of the same fall. One possibility is that they are fragments of the impactor that formed Victoria crater as suggested by their similar distribution to fragments around terrestrial impact craters819.…”

“…The stony meteorites discovered by Opportunity are probably paired8 and therefore fell at the same time. Because of their distribution surrounding Victoria Crater, they may be part of the impactor that created that crater.…”

“…Mars' atmosphere is sufficiently dense to expect finding meteorites on its surface6, and both Mars Exploration Rovers (MERs), Spirit and Opportunity, as well as the Mars Science Laboratory or Curiosity rover have discovered meteorites7891011. Most of these are iron meteorites but Opportunity also came across several stony meteorite fragments789.…”

“…Most of these are iron meteorites but Opportunity also came across several stony meteorite fragments789. Meteorite finds of a known type—whose unweathered composition is well known from the study of other specimens of the same type on Earth—provide standard samples that have been exposed to the weathering environment of the surface area they fell on121314.…”