Geochemistry

Quantum mechanics

Chondrule

Meteorite

Literature

Astrophysics

Geology

Physics

Deuterium

Formation and evolution of the Solar System

Protoplanetary disk

Astrobiology

Parent body

Chondrite

Chemistry

Planet

Dual (grammatical number)

Solar System

Asteroid

Isotopic signature

Isotope

Nature Astronomy

Carbonaceous asteroids represent the principal source of water in the inner Solar System and might correspond to the main contributors for the delivery of water to Earth. Hydrogen isotopes in water-bearing primitive meteorites, for example carbonaceous chondrites, constitute a unique tool for deciphering the sources of water reservoirs at the time of asteroid formation. However, fine-scale isotopic measurements are required to unravel the effects of parent-body processes on the pre-accretion isotopic distributions. Here, we report in situ micrometre-scale analyses of hydrogen isotopes in six CM-type carbonaceous chondrites, revealing a dominant deuterium-poor water component (δD = −350 ± 40‰) mixed with deuterium-rich organic matter. We suggest that this deuterium-poor water corresponds to a ubiquitous water reservoir in the inner protoplanetary disk. A deuterium-rich water signature has been preserved in the least altered part of the Paris chondrite (δDParis ≥ −69 ± 163‰) in hydrated phases possibly present in the CM rock before alteration. The presence of the deuterium-enriched water signature in Paris might indicate that transfers of ice from the outer to the inner Solar System were significant within the first million years of the history of the Solar System. Laboratory analyses on six carbonaceous chondrites suggest the presence of two water sources with different deuterium (D) enrichment levels in the protoplanetary disk: a D-poor inner reservoir and a D-rich water component transferred inward from the outer disk.

A dual origin for water in carbonaceous asteroids revealed by CM chondrites