The relationship between CK and CV chondrites

Abstract

CK chondrites are highly oxidized meteorites containing abundant magnetite and trace amounts of Fe,Ni-metal. Although the group is predominately composed of equilibrated meteorites (types 4 to 6), in recent years a significant number of new samples have been classified as being either CK3 or CK3-anomalous. These unequilibrated CKs often display a close affinity with members of the CV oxidized subgroup. CKs and CVs (oxidized subgroup) may therefore form a continuum and by implication could be derived from a single common parent body. To investigate the relationship between these two groups a detailed study of the oxygen isotope composition, opaque mineralogy and major and trace element geochemistry of a suite of CV and CK chondrites has been undertaken. The results of oxygen isotope analysis confirm the close affinity between CV and CK chondrites, while excluding the possibility of a linkage between the CO and CK groups. Magnetites in both CV and CK chondrites show significant compositional similarities, but high Ti contents are a diagnostic feature of the latter group. The results of major and trace element analysis demonstrate that both CV and CK chondrites show overlapping variation. Supporting evidence for a single common source for both groups comes from their similar cosmic-ray exposure age distributions. Recent reflectance spectral analysis is consistent with both the CVs and CKs being derived from Eos family asteroids, which are believed to have formed by the catastrophic disruption of a single large asteroid. Thus, a range of evidence appears to be consistent with CV and CK chondrites representing samples from a single thermally stratified parent body. In view of the close similarity between CV and CK chondrites some modification of the present classification scheme may be warranted, possibly involving integration of the two groups. One means of achieving this would be to reassigned CK chondrites to a subgroup of the oxidized CVs. It is recognized that a full evaluation of this proposal may require further study of the still poorly understood CK3 chondrites. ACCEPTED MANUSCRIPT3

A mutli-technique search for the most primitive CO chondrites

“…2 (Clayton and Mayeda, 1999;Young et al, 1999), hydrothermal alteration resulted in bulk O isotope variations along slopes that are significantly shallower than the CCAM line. The O isotope variation seen in the COs is similar to that found in the CVs (Greenwood et al, 2010). It is often argued that nebula water O isotopic compositions fell close to 16 O-poor extensions of the CCAM or Young and Russell lines (Clayton and Mayeda, 1999;Young et al, 1999;Sakamoto et al, 2007).…”

Spatial distribution of carbon dust in the early solar nebula and the carbon content of planetesimals

“…The chondrule abundance of CK chondrites is given in the literature as 15%, but a new determination by Chaumard & Devouard (2016) found ∼50 volume percent for CK3 meteorites. It has been proposed that CK and CV are derived from the same parent body (Greenwood et al 2010b), and this may be the parent body of the Eos family (Greenwood et al 2010a;Novaković & Tsirvoulis 2014). The chondrule abundance for CH chondrites is taken from Hezel et al (2001).…”

Chondrule size and related physical properties: A compilation and evaluation of current data across all meteorite groups

“…Some evidence exists (Greenwood et al, 2010;Wasson et al, 2013) that the CV and CK chondrites are genetically related (i.e., their chondrule dimensions may be identical), but we consider them individually below.…”