An achondrite clast in Parnallee with possible links to ureilites

Details An achondrite clast in Parnallee with possible links to ureilites An achondrite clast in Parnallee with possible links to ureilites

Jul 1994

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1994metic..29..449b&link_type=abstract

Meteoritics (ISSN 0026-1114), vol. 29, no. 4, p. 449-450

Computer Science

Achondrites, Chondrites, Chondrule, Feldspars, Meteoritic Composition, Nepheline, Oxygen Isotopes, Chemical Analysis, Mineralogy, Rare Earth Elements, Ureilites

Scientific paper

The presence of exotic xenoliths or clasts in ordinary chondrites is well documented on the basis of O isotopes. Here we report a feldspar-nepheline clast (FELINE) found in Parnallee, which may have a planetary origin. FELINE is a 3-mm subrounded clast containing 88 modal% plagioclase and 12 modal% nepheline. Prior to late parent-body fracturing the plagioclase appears to have consisted of a few large individual grains. FELINE has no chondrule-like fine-grained rim and may be a fragment of a larger body. Plagioclase is An 75-87, Ab 25-13. Nepheline contains 0.24-3.12 wt% Cl. The mildly alkaline bulk composition of FELINE is distinct from Al-rich chondrules, having lower MgO and FeO, and is too Na2O- and Cl-rich for Ca-Al rich inclusions (CAI)-like compositions. Plagioclase has negative Rare Earth Element (REE)/chondrite slopes with pronounced positive Eu anomalies. Such a REE signature is consistent with an igneous origin for FELINE. The O isotope signature of FELINE is delta O-17 4.5, delta O-18 8.9. FELINE lies apart from most oc chondrules on the three-isotope plot showing its exotic origin. It plots near the intersection of the carbonaceous chondrite anhydrous minerals line (CCAM) with the terrestrial fractionation line. Bulk ureilites also plot long CCAM, and FELINE plots on an extension of the currently known field. Ureilite genesis is still controversial with models requiring extensive planetary differentiation or relatively limited reworking and melting of primitive precursors. FELINE might also be a product of the missing Ca-, Al-rich melt. The mildly alkaline bulk composition and fractionated REE of FELINE suggest that it crystallized from a differentiated melt. Whether FELINE is related to ureilite genesis or not, it provides further evidence that achondritic planetary clasts are one of the components in ordinary chondrites.

Affiliated with

Also associated with

No associations

Rating

An achondrite clast in Parnallee with possible links to ureilites 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 An achondrite clast in Parnallee with possible links to ureilites, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and An achondrite clast in Parnallee with possible links to ureilites will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-821948