Plate tectonics and the detection of land-based biosignatures on Mars and extrasolar planets

John Parnell*

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

On Earth, surface detritus has a quartz-rich mineralogy as a consequence of plate tectonics. Rocky planets without plate tectonics, like Mars, have surface detritus derived from volcanic rocks. There is a marked contrast in the transmission of photosynthetically active radiation (PAR) through the upper few millimetres of the two sediment types. Quartz-rich sediment allows PAR to penetrate below the level where ultraviolet (UV) radiation is cut out, so represents a potential refuge for phototrophs at an early stage of evolution before chemical defences against UV radiation are developed. Opaque volcanogenic sediment does not allow significant transmission of radiation beneath the surface. There are consequences for the expression of biosignatures from phototrophs. In the case of direct examination as proposed for Mars, techniques such as Raman spectroscopy will be applicable only to surfaces rather than penetratively into the subsurface. When spectroscopic techniques can be applied to extrasolar planets, the chance of a vegetation signature will be enhanced if the early evolution of phototrophs has been facilitated by a subsurface refuge.

Original languageEnglish
Pages (from-to)175-186
Number of pages12
JournalInternational Journal of Astrobiology
Volume4
Issue number3-4
DOIs
Publication statusPublished - 1 Jan 2005

Keywords

  • biosignatures
  • light transmission
  • mineralogy
  • photosynthesis
  • plate tectonics

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