# Icarus pre-proof: heating in asteroids depleted halogens in ordinary and enstatite chondrites

- Published: 2026-11-15 10:07 UTC
- Section: Sky & Space › Astronomy
- Tags: halogens in meteorites, chlorine isotopes, ordinary chondrites, enstatite chondrites, asteroid metamorphism, asteroidal distillation, Earth volatile inventory, potassium isotopes, onion-shell model
- URL: https://realtech.media/news/rt-7ce0f8ff56c81c450b367c79_icarus_pre_proof/

**Authors report that metamorphism drove off and redistributed halogens, so parent-body budgets may be lower than the least-altered meteorites imply. A mass-balance model supports this.**

![Icarus pre-proof: heating in asteroids depleted halogens in ordinary and enstatite chondrites](https://realtech.media/media/2026/11/3b645d771d3640c7.jpg)
*techtimes.com*

Anthony Gargano and seven co-authors report in an Icarus pre-proof that heating inside asteroids drove off and redistributed fluorine, chlorine, bromine and iodine, according to techtimes.com. [1] As a result, the bulk halogen budgets of the parent bodies could be much lower than their least-altered meteorites imply. [1] A pre-proof is an accepted manuscript not yet assigned to a journal issue, so details can still change.

## Halogens and isotopes in chondrites

The team analyzed ordinary chondrites (H, L and LL groups, petrologic types 3.1 to 6), enstatite chondrites (EH and EL groups, types 3 to 6) and several achondrites. [1] Type 3 rocks are the least metamorphosed, while types 4 to 6 record higher temperatures. For ordinary chondrites these reach roughly 1,200 to 1,300 kelvin (about 1,700 to 1,880°F). [1]

According to the abstract, halogen and potassium concentrations fall as metamorphic grade rises, while the heavier isotopes of chlorine and potassium become more abundant. [1] Values generally increase from −4.5 to +8.6 per mil for δ³⁷Cl and from −1.41 to −0.33 per mil for δ⁴¹K. [1] The authors read this as open-system loss or transfer of volatiles during sub-solidus metamorphism, that is, heating well below the melting point of the rock. [1]

Ordinary chondrites show the strongest depletion and the widest isotopic spread, which the authors tie to vapors escaping through comparatively permeable material. [1] Enstatite chondrites, which are highly chemically reduced, show much more muted changes, attributed to better volatile retention. [1] The authors also say fluorine favors enstatite chondrite-like bodies as Earth's main halogen source. [1]

## Asteroidal distillation and the model

The authors call their central idea asteroidal distillation. Vapors released from the hot interior travel outward and condense in cooler, near-surface material, which can overprint the chemistry of "unequilibrated" samples traditionally used as proxies for the starting composition. [1]

To test this, the team built an onion-shell mass-balance model that treats the asteroid as concentric layers exchanging volatiles. It suggests that bulk parent-body halogen budgets could be considerably lower than the most primitive chondrites indicate. [1] Model parameters, data tables and achondrite results are in the full text and are not described in the abstract.

Earlier work gives context. A 2017 Nature paper led by Patricia Clay found chlorine, bromine and iodine in several chondrite classes to be about 6, 9 and 15 to 37 times lower, respectively, than earlier accepted values, regardless of petrologic type. [1] Hannah Bloom and colleagues measured potassium isotopes in more than 40 carbonaceous and ordinary chondrites and found no clear correlation with petrologic type. [1] The abstract does not say how its grade-dependent trends relate to Clay's result.

## Sources

1. [techtimes.com](https://www.techtimes.com/articles/330746/20261114/study-finds-heated-asteroids-lost-chlorine-pristine-meteorites-may-overstate-halogen-supply.htm)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-7ce0f8ff56c81c450b367c79_icarus_pre_proof/