K-Ca dating and Ca isotope composition of the oldest Solar System lava, Erg Chech 002

Abstract

Erg Chech 002 (EC 002) is an andesitic meteorite, which is the oldest lava in the Solar System as determined by the 26 Al-26 Mg relative chronometer. Here, we present high precision Ca isotope data for the bulk rock and mineral separates of EC 002, and for the first time, obtain a 40 K-40 Ca isochron by using the Nu Sapphire, a collision cell equipped MC-ICP-MS instrument. The mineral separates yield a 40 K-40 Ca age of 4545 ± 78 Ma with an initial 40 Ca/ 44 Ca = 47.16065 ± 0.00049 (ε 40 Ca SRM 915a = −0.33 ± 0.10). The age is identical with those obtained from other long lived isotopic systematics but more precise, and it is consistent with the short lived 26 Al-26 Mg age. The δ 44/40 Ca of EC 002 is 0.87 ± 0.05 ‰ suggesting that EC 002 might represent a differentiated melt from an ordinary chondritic parent body. The extremely old age of EC 002, along with the similar ε 40 Ca values among most meteorites, suggests that the 40 Ca was homogeneously distributed within early formed planetesimals and the ε 40 Ca value of EC 002 could represent the average of initial ε 40 Ca of the Solar System.

High-Precision Measurements of 44Ca/40Ca Using Multiple-Collector Inductively Coupled Plasma Mass Spectrometry without Collision-Cell Technology

“…Comparison between previously reported Ca isotopic data and values measured in this study. Previously reported values are from the literature. ,,− ,,− Gray, red, and blue spots represent data from the literature, this study, and average values of literature values. All the compiled data are listed in Table S9.…”

Petrogenesis of Erg Chech 002 Achondrite and Implications for an Altered Magma Ocean

“…The recently discovered ungrouped achondrite Erg Chech 002 (EC 002) has been dated as the oldest magmatic achondrite (0.7-2.25 Ma after the formation of calcium-aluminum-rich inclusions, CAIs) and provides evidence for very early volcanism in the nascent solar system (Barrat et al 2021;Anand et al 2022;Fang et al 2022;Zhu et al 2022;Connelly et al 2023;Dai et al 2023;Krestianinov et al 2023;Reger et al 2023). The investigations into this meteorite thus benefit our understanding on the driving source for the generation of intermediate-felsic magmatism in the early solar system.…”