|Title||Potassium isotopic compositions of howardite-eucrite-diogenite meteorites|
|Publication Type||Journal Article|
|Year of Publication||2019|
|Authors||Tian Z., Chen H., Fegley B., Lodders K., Barrat J.A, Day JMD, Wang K.|
|Type of Article||Article|
|Keywords||chemical fractionations; Geochemistry & Geophysics; K isotopes; Magma Ocean; martian meteorite; mass-dependence; mc-icp-ms; ordinary chondrites; origin; parent body; petrology; planetary; solar nebula; Vesta|
We report new high-precision stable K isotope data for three martian meteorites, one lunar meteorite, one ordinary chondrite, four terrestrial igneous United States Geological Survey (USGS) reference materials, and twenty howardite-eucrite-dio genite [HED] meteorites. The three martian meteorites define a relatively narrow delta K-41 range with an average of -0.36 +/- 0.12 parts per thousand (2 SD) that is slightly heavier than the Bulk Silicate Earth (BSE) K isotopic composition (-0.48 +/- 0.03 parts per thousand). Except for the four Northwest Africa samples which were terrestrially contaminated, all HED meteorites reveal substantial K-41 enrichment compared to BSE, lunar samples, martian meteorites, and chondrites. We propose that the average delta K-41 (+0.36 +/- 0.16 parts per thousand) obtained from HED meteorites is representative of Bulk Silicate 4-Vesta. The coupled volatile depletion and heavy K isotope enrichment in 4-Vesta could be attributed to both nebula-scale processes and parent-body events. The asteroid 4-Vesta is likely to have accreted from planetary feedstocks that have been significantly volatile-depleted prior to the major phases of planetary accretion in the early Solar System, with secondary effects of K loss during accretionary growth and magma ocean degassing. (C) 2019 Elsevier Ltd. All rights reserved.