First evidence for silica condensation within the solar protoplanetary disk.

ABSTRACT: Calcium-aluminum-rich inclusions (CAIs) and amoeboid olivine aggregates (AOAs), a refractory component of chondritic meteorites, formed in a high-temperature region of the protoplanetary disk characterized by approximately solar chemical and oxygen isotopic (Δ¹⁷O ∼ -24‰) compositions, most likely near the protosun. Here we describe a ¹⁶O-rich (Δ¹⁷O ∼ -22 ± 2‰) AOA from the carbonaceous Renazzo-type (CR) chondrite Yamato-793261 containing both (i) an ultrarefractory CAI and (ii) forsterite, low-Ca pyroxene, and silica, indicating formation by gas-solid reactions over a wide temperature range from ∼1,800 to ∼1,150 K. This AOA provides direct evidence for gas-solid condensation of silica in a CAI/AOA-forming region. In a gas of solar composition,

SUBMITTER: Komatsu M 

PROVIDER: S-EPMC6055204 | biostudies-literature | 2018 Jul

REPOSITORIES: biostudies-literature