Solar System’s earliest solids as tracers of the accretion region of Ryugu and Ivuna-type carbonaceous chondrites

KAWASAKI Noriyuki YURIMOTO Hisayoshi

Department of Earth and Planetary Sciences

Jul. 17, 2025

小惑星「リュウグウ」から見つかった太陽系最古の岩石「CAI」。Al-Mg放射年代測定法により、太陽系誕生直後の約45億6,730万年前に形成されたことが判明。データは電子顕微鏡により取得したMg（赤）―Ca（緑）―Al（青）の合成X線元素マップ。 （©Kawasaki et al. 2025）

Press release (in Japanese)

Abstract
Samples from the carbonaceous asteroid Ryugu and CI (Ivuna-type) chondrites are dominated by low-temperature, aqueously formed secondary minerals, with rare occurrences of anhydrous primary minerals that formed in the high-temperature region of the solar protoplanetary disk. Here, we show that small (<a few tens of micrometers) Ca-Al-rich inclusions (CAIs) in Ryugu and Ivuna formed within ~0.2 Ma of the Solar System’s birth. These CAIs exhibit mineralogical, O-isotopic, and chronological similarities to CAIs in ordinary and other carbonaceous chondrites, indicating their ubiquitous presence across chondrites. In contrast, larger (>submillimeter) CAIs, commonly found in ……

Read the original article on Communications Earth & Environment

Article inforamation

• Noriyuki Kawasaki, Sota Arakawa, Yushi Miyamoto, Naoya Sakamoto, Daiki Yamamoto, Sara S. Russell & Hisayoshi Yurimoto, Solar System’s earliest solids as tracers of the accretion region of Ryugu and Ivuna-type carbonaceous chondrites. Commun Earth Environ 6, 537 (2025).

DOI: 10.1038/s43247-025-02511-x