Fall, recovery and description of the Coleman chondrite

Osborn, W.; Matty, David J; Velbel, M. A.; Brown, Peter; Wacker, J. F.

doi:10.1111/j.1945-5100.1997.tb01569.x

Cited by 3 publications

(1 citation statement)

References 12 publications

(4 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Although shock remains the dominant driving force for their formation, most so-called shock veins do exhibit micro-offset (e.g. Begemann & Wlotza 1969;Axon & Stefle-Perkins 1975;Spray 1994;Osborn et al 1997), thus a frictional contribution to their energy budget and formation mechanism cannot be neglected. Critically, these so-called shock veins show many similarities to certain pseudotachylytes developed in terrestrial impact structures, as first alluded to by Barnes (1939).…”

Section: Shock Veinsmentioning

confidence: 99%

Localized shock- and friction-induced melting in response to hypervelocity impact

Spray

1998

View full text Add to dashboard Cite

The distribution of shock veins, friction melts and cataclastic rocks in complex impact craters reflects the response of target lithologies to varying rates of strain. Within the Sudbury impact structure, thin (<2 mm), anastomosing veins, which can define shatter cone surfaces, permeate the target rocks in a c. 15 km wide zone around the Sudbury igneous complex (SIC). A similar relationship exists within the Vredefort impact structure, with the additional association of the high-pressure SiO2 polymorphs coesite and stishovite. These S-(shock-dominant) type pseudotachylytes are comparable with shock veins developed in meteorites. Both are considered to form primarily by shock compression-decompression during the contact and compression stage of the collision process. Larger, thicker (up to 1 km wide) friction melt bodies constitute pseudotachylytes formed by the extreme comminution of fault walls during rebound and gravitational collapse of the transient cavity. They also appear to define the concentric fault systems of multi-ring impact basins. These E-(endogenic-) type pseudotachylytes form during the modification stage of the cratering process and post-date S-type pseudotachylytes. At Sudbury, they occur up to 80km beyond the SIC. E-type pseudotachylytes are formed by the same mechanism as pseudotachylytes in non-impact-related fault systems: frictional melting of fault walls during seismogenic slip. Those in impact structures can be large because the extreme displacements (several kilometres) facilitated by superfaults generate massive volumes of friction melt. SPRAY, J. G. 1998. Localized shock-and friction-induced melting in response to hypervelocity impact.

show abstract

Section: Shock Veinsmentioning

confidence: 99%

Localized shock- and friction-induced melting in response to hypervelocity impact

Spray

1998

View full text Add to dashboard Cite

show abstract

The Worden meteorite: A new ordinary chondrite fall from Michigan, USA

Velbel

Matty

Wacker

et al. 2002

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Abstract-An ordinary chondrite fall in southeast Michigan, USA (near the crossroads hamlet of Worden in northeast Washtenaw County) penetrated the garage roof of a private home on 1997 September 1. The Worden chondrite comprises silicate matrix, mineral fragments, chondrules, chondrule fragments, and opaque primary phases. Electron microprobe analyses (olivine, Fa23.9; orthopyroxene, FS20.l, En78.8, W01) indicate diagnostic L-chondrite silicate mineral compositions. Recognizable chondrules and chondrule fragments constitute up to 42 vol%. Chondrule boundaries are readily discernable (especially where chondrules have rims of opaque material) but not sharp, and discrete plagioclase crystals are visible in the devitrified mesostasis of barred olivine chondrules; together, these characteristics suggest petrologic type 5. The spatially averaged ensemble of shockrelated features (optical extinction of olivine grains, minor localized shock melt) suggests assignment of a shock stage of S3.The 26Al and 22Na activities are typical for an L chondrite. Worden fell near the most recent solar minimum in 1997, and the 22Na production rate should have been at a level approaching the maximum levels due to solar modulation of the galactic cosmic-ray flux. The low value for the Worden 22Na activity relative to those observed in chondrite falls associated with the 1969 solar maximum and 1976 solar minimum suggests a relatively small preatmospheric size. The 60Co activity confirms the indication ofa small body. The 56Co activity was essentially zero, indicating that none ofthe recovered meteorite contained material exposed to solar cosmic rays.The Worden chondrite is the fourth documented fall in Michigan, and the fourth stony meteorite recovered in Michigan; all other Michigan meteorites are finds, not observed falls, and are iron meteorites. All Michigan falls to date are ordinary chondrites. The three falls prior to Worden were Allegan (H5) fell 1899; Rose City (H5, brecciated, black (dark matrix)) fell 1921 ; and Coleman (L6, veined (shocked); Osborn et a!., 1997) fell 1994. Worden has a much lighter matrix than Rose City, and is less extensively thermally and shock metamorphosed than either Rose City (Steffler et a!., 1991) or Coleman.

show abstract

Aqueous Alteration in Martian Meteorites

Velbel¹

2012

Sedimentary Geology of Mars

View full text Add to dashboard Cite

Many of the minerals observed or inferred to occur in the sediments and sedimentary rocks of Mars, from a variety of Mars-mission spacecraft data, also occur in Martian meteorites. Even Martian meteorites recovered after some exposure to terrestrial weathering can preserve preterrestrial evaporite minerals and useful information about aqueous alteration on Mars, but the textures and textural contexts of such minerals must be examined carefully to distinguish preterrestrial evaporite minerals from occurrences of similar minerals redistributed or formed by terrestrial processes. Textural analysis using terrestrial microscopy provides strong and compelling evidence for preterrestrial aqueous alteration products in a number of Martian meteorites. Occurrences of corroded primary rock-forming minerals and alteration products in meteorites from Mars cover a range of ages of mineral-water interaction, from ca. 3.9 Ga (approximately mid-Noachian), through one or more episodes after ca. 1.3 Ga (approximately mid-late Amazonian), through the last half billion years (late Amazonian alteration in young shergottites), to quite recent. These occurrences record broadly similar aqueous corrosion processes and formation of soluble weathering products over a broad range of times in the paleoenvironmental history of the surface of Mars. Many of the same minerals (smectite-group clay minerals, Ca-sulfates, Mg-sulfates, and the K-Fe-sulfate jarosite) have been identified both in the Martian meteorites and from remote sensing of the Martian surface. This suggests that both kinds of samples-Martian meteorites and Mars' surface rocks, regolith, and soils-were altered under broadly similar conditions. Temporarily and locally occurring but likely stagnant aqueous solutions reacted quickly with basaltic/mafic/ultramafic minerals at low water-rock ratios. Solutes released by primary mineral weathering precipitated locally on Mars as cation-rich clays and evaporite minerals, rather than being leached away, as on Earth. The main secondary host minerals for Fe differ between Martian meteorites and Mars' surface materials. In Martian meteorites, sideritic-ankeritic carbonate is the predominant secondary host mineral for Fe, whereas in Mars' surface materials, ferric oxides and ferric sulfates are the predominant secondary host minerals for Fe. Differences in the initial compositions of the altering solutions are implied, with carbonate/bicarbonate dominating in the solutions that altered Martian meteorites, and sulfate dominating the solutions that altered most Mars' surface materials. During impact on and ejection from Mars, Martian meteorites may have been exhumed from depths sufficient to have isolated them from large quantities of Mars'surface solutions. Preejection weathering of the basaltic rocks occurred in grain-boundary fracture microenvironments at high pH values in aqueous solutions buffered by reactions with basalt minerals.

show abstract

Fall, recovery and description of the Coleman chondrite

Cited by 3 publications

References 12 publications

Localized shock- and friction-induced melting in response to hypervelocity impact

Localized shock- and friction-induced melting in response to hypervelocity impact

The Worden meteorite: A new ordinary chondrite fall from Michigan, USA

Aqueous Alteration in Martian Meteorites

Contact Info

Product

Resources

About