Meteoritics & Planetary Science, Volume 41, Number 8 (2006)http://hdl.handle.net/10150/6412572024-03-28T13:43:35Z2024-03-28T13:43:35ZNoble gas space exposure ages of individual interplanetary dust particlesKehm, K.Flynn, G. J.Sutton, S. R.Hohenberg, C. M.http://hdl.handle.net/10150/6567052021-02-16T02:07:48Z2006-01-01T00:00:00ZNoble gas space exposure ages of individual interplanetary dust particles
Kehm, K.; Flynn, G. J.; Sutton, S. R.; Hohenberg, C. M.
The He, Ne, and Ar compositions of 32 individual interplanetary dust particles (IDPs) were measured using low-blank laser probe gas extraction. These measurements reveal definitive evidence of space exposure. The Ne and Ar isotopic compositions in the IDPs are primarily a mixture between solar wind (SW) and an isotopically heavier component dubbed fractionated solar (FS), which could be implantation-fractionated solar wind or a distinct component of the solar corpuscular radiation previously identified as solar energetic particles (SEP). Space exposure ages based on the Ar content of individual IDPs are estimated for a subset of the grains that appear to have escaped significant volatile losses during atmosphere entry. Although model-dependent, most of the particles in this subset have ages that are roughly consistent with origin in the asteroid belt. A short (<1000 years) space exposure age is inferred for one particle, which is suggestive of cometary origin. Among the subset of grains that show some evidence for relatively high atmospheric entry heating, two possess elevated 21Ne/22Ne ratios generated by extended exposure to solar and galactic cosmic rays. The inferred cosmic ray exposure ages of these particles exceeds 107 years, which tends to rule out origin in the asteroid belt. A favorable possibility is that these 21Ne‐rich IDPs previously resided on a relatively stable regolith of an Edgeworth‐Kuiper belt or Oort cloud body and were introduced into the inner solar system by cometary activity. These results demonstrate the utility of noble gas measurements in constraining models for the origins of interplanetary dust particles.
2006-01-01T00:00:00ZFrontier Mountain 93001: A coarse-grained, enstatite-augite-oligoclase-rich, igneous rock from the acapulcoite-lodranite parent asteroidFolco, L.D'Orazio, M.Burroni, A.http://hdl.handle.net/10150/6567042021-02-16T02:07:05Z2006-01-01T00:00:00ZFrontier Mountain 93001: A coarse-grained, enstatite-augite-oligoclase-rich, igneous rock from the acapulcoite-lodranite parent asteroid
Folco, L.; D'Orazio, M.; Burroni, A.
The Frontier Mountain (FRO) 93001 meteorite is a 4.86 g fragment of an unshocked, medium-to coarse-grained rock from the acapulcoite-lodranite (AL) parent body. It consists of anhedral orthoenstatite (FS13.3 +/- .04 WO 3.1 +/- 0.2), augite (FS6.1 +/- 0.7 WO42.3 +/- 0.9; Cr2O3 = 1.54 +/- 0.03), and oligoclase (Ab80.5 +/- 3.3 Or 3.1 +/- 0.6) up to >1 cm in size enclosing polycrystalline aggregates of fine-grained olivine (average grain size: 460 +/- 210 micrometers) showing granoblastic textures, often associated with Fe,Ni metal, troilite, chromite (cr# = 0.91 +/- 0.03; fe# = 0.62 +/ 0.04), schreibersite, and phosphates. Such aggregates appear to have been corroded by a melt. They are interpreted as lodranitic xenoliths. After the igneous (the term "igneous" is used here strictly to describe rocks or minerals that solidified from molten material) lithology intruding an acapulcoite host in Lewis Cliff (LEW) 86220, FRO 93001 is the second-known silicate-rich melt from the AL parent asteroid. Despite some similarities, the silicate igneous component of FRO 930011 (i.e., the pyroxene-plagioclase mineral assemblage) differs in being coarser-grained and containing abundant enstatite. Melting-crystallization modeling suggests that FRO 93001 formed through high-degree partial melting (greater than or equal to 35 wt%; namely, greater than or equal to 15 wt% silicate melting and ~20 wt% metal melting) of an acapulcoite source rock, or its chondritic precursor, at temperatures greater than or equal to 1200 degrees C, under reducing conditions. The resulting magnesium-rich silicate melt then underwent equilibrium crystallization; prior to complete crystallization at ~1040 degrees C, it incorporated lodranitic xenoliths. FRO 93001 is the highest-temperature melt from the AL parent-body so far available in laboratory. The fact that FRO 93001 could form by partial melting and crystallization under equilibrium conditions, coupled with the lack of quench-textures and evidence for shock deformation in xenoliths, suggests that FRO 93001 is a magmatic rock produced by endogenic heating rather than impact melting.
2006-01-01T00:00:00ZMicrobial diversity on the Tatahouine meteoriteBenzerara, K.Chapon, V.Moreira, D.López-García, P.http://hdl.handle.net/10150/6561672021-02-16T01:41:48Z2006-01-01T00:00:00ZMicrobial diversity on the Tatahouine meteorite
Benzerara, K.; Chapon, V.; Moreira, D.; López-García, P.
Biological processes can alter the chemistry and mineralogy of meteorites in a very short time, even in cold or hot deserts. It is thus important to assess the diversity of microorganisms that colonize meteorites in order to better understand their physiological capabilities. Microscopy observations of Tatahouine meteorite fragments that were exposed for 70 years in the Sahara desert showed that they were colonized by morphologically diverse biomorphs. A molecular diversity study based on 16S rRNA gene amplification of DNA supported the conclusion that a huge taxonomic diversity of prokaryotes colonized the Tatahouine meteorite in less than 70 years in the Tatahouine sand. Eleven different bacterial divisions were evidenced, among which Cytophaga-Flexibacter- Bacteroides (CFB), Cyanobacteria, and Alpha-Proteobacteria were dominantly represented. Crenarcheota were also detected. Most of the Tatahouine meteorite phylotypes were related to sequences identified in the surrounding Tatahouine more generally to sequences detected in soils. Some of them, in particular many of the archaeal phylotypes, were detected in arid regions in association with desert varnish. The results suggest that the diversity of the clone library generated from the meteorite fraction was reduced compared with that of the Tatahouine sand clone library, which can be explained as the result of partial colonization of the meteorite and/or a specific selection of colonizing bacteria by the substrate. We discuss the possibility that several groups detected in this study may play a prominent role in the various alteration processes detected at the surface of the Tatahouine meteorite.
2006-01-01T00:00:00ZBook Review: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, Vanessa Hill, Patrick François, Francesca Primas (Eds.)Meyer, B. S.http://hdl.handle.net/10150/6561682021-02-16T01:42:01Z2006-01-01T00:00:00ZBook Review: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, Vanessa Hill, Patrick François, Francesca Primas (Eds.)
Meyer, B. S.
Book Review: From Lithium to Uranium: Elemental Tracers of Early Cosmic Evolution, Vanessa Hill, Patrick François, Francesca Primas (Eds.). Cambridge University Press (2005).
2006-01-01T00:00:00Z