Dataset Information

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite.

ABSTRACT: Meteorites preserve evidence of processes on their parent bodies, including alteration, metamorphism, and shock events. Here we show that the Kakowa (L6) ordinary chondrite (OC) preserves both shock-melt veins and pockets of detrital grains from a brecciated and altered object, including corundum, albite, silica, fayalite, forsterite, and margarite in a Pb- and Fe-rich matrix. Preservation of the observed mineralogy and texture requires a sequence of at least two impacts: first, a high-velocity collision formed the shock melt veins containing the high-pressure minerals ringwoodite, wadsleyite, majorite, and albitic jadeite; later, a low-velocity impact formed fractures and filled them with the detrital material. Oxygen and Pb isotope ratios suggest an OC origin for these detrital minerals. Although fluid alteration is common in carbonaceous chondrites, the discovery of margarite with an OC oxygen isotopic signature is novel. Kakowa extends both the impact and alteration history of L6 ordinary chondrites in general.

SUBMITTER: Baziotis IP

PROVIDER: S-EPMC9005539 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite.

Baziotis I P IP Ma C C Guan Y Y Ferrière L L Xydous S S Hu J J Kipp M A MA Tissot F L H FLH Asimow P D PD

Scientific reports 20220412 1

Meteorites preserve evidence of processes on their parent bodies, including alteration, metamorphism, and shock events. Here we show that the Kakowa (L6) ordinary chondrite (OC) preserves both shock-melt veins and pockets of detrital grains from a brecciated and altered object, including corundum, albite, silica, fayalite, forsterite, and margarite in a Pb- and Fe-rich matrix. Preservation of the observed mineralogy and texture requires a sequence of at least two impacts: first, a high-velocity ...[more]

PMID: 35414699

Similar Datasets

Project description:The presence of hydrated minerals in chondrites indicates that water played an important role in the geologic evolution of the early Solar System; however, the process of aqueous alteration is still poorly understood. Renazzo-like carbonaceous (CR) chondrites are particularly well-suited for the study of aqueous alteration. Samples range from being nearly anhydrous to fully altered, essentially representing snapshots of the alteration process through time. We studied oxygen isotopes in secondary-minerals from six CR chondrites of varying hydration states to determine how aqueous fluid conditions (including composition and temperature) evolved on the parent body. Secondary minerals analyzed included calcite, dolomite, and magnetite. The O-isotope composition of calcites ranged from δ18O ≈ 9 to 35 ‰, dolomites from δ18O ≈ 23 to 27 ‰, and magnetites from δ18O ≈ -18 to 5 ‰. Calcite in less-altered samples showed more evidence of fluid evolution compared to heavily altered samples, likely reflecting lower water/rock ratios. Most magnetite plotted on a single trend, with the exception of grains from the extensively hydrated chondrite MIL 090292. The MIL 090292 magnetite diverges from this trend, possibly indicating an anomalous origin for the meteorite. If magnetite and calcite formed in equilibrium, then the relative 18O fractionation between them can be used to extract the temperature of co-precipitation. Isotopic fractionation in Al Rais carbonate-magnetite assemblages revealed low precipitation temperatures (~60°C). Assuming that the CR parent body experienced closed-system alteration, a similar exercise for parallel calcite and magnetite O-isotope arrays yields "global" alteration temperatures of ~55 to 88 °C. These secondary mineral arrays indicate that the O-isotopic composition of the altering fluid evolved upon progressive alteration, beginning near the Al Rais water composition of Δ17O ~ 1 ‰ and δ18O ~ 10 ‰, and becoming increasingly 16O-enriched toward a final fluid composition of Δ17O ~ -1.2 ‰ and δ18O ~ -15 ‰.

Dataset Information

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite.

Publications

Unique evidence of fluid alteration in the Kakowa (L6) ordinary chondrite.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets