Cosmogenous

Cosmogenous refers to materials that originate from outer space and are deposited on Earth, particularly in soils and sediments. It is one of the major categories used to describe the provenance of marine and terrestrial sediments, alongside lithogenic (from land), biogenic (from organisms), and authigenic (formed in place) components.

The primary sources of cosmogenous material are micrometeorites and interplanetary dust particles that survive entry through Earth’s atmosphere and settle onto surfaces. Meteorite fragments, tektites formed by meteorite impacts, and the glassy debris produced by airburst events also contribute to cosmogenous inputs. A constant but dilute flux of cosmic dust continuously adds material to the planet.

Cosmogenous materials occur in various forms, most commonly as glassy spherules, nickel-iron grains, or silicate-rich fragments. Tektites are a notable, highly distinctive form derived from terrestrial impact melting of extraterrestrial material. Their isotopic and chemical signatures help distinguish cosmogenous origin from terrestrial sources, and they can be preserved in both marine and continental sediments.

In sedimentary records, cosmogenous components are typically a minority relative to lithogenic and biogenic fractions, but they can be more detectable in certain environments such as deep-sea or high-lacustrine zones. Identification relies on microscopic analysis, electron microscopy, and geochemical/isotopic characterization, sometimes combined with separation techniques to isolate micrometeorites.

Significance lies in constraining the flux of extraterrestrial material to Earth and informing studies of solar system processes, meteorite delivery history, and potential influences on climate and ocean chemistry over geological timescales.