Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH84001

  title={Search for Past Life on Mars: Possible Relic Biogenic Activity in Martian Meteorite ALH84001},
  author={David S. Mckay and Everett K. Gibson and Kathie Louise Thomas-Keprta and Hojatollah Vali and Christopher S. Romanek and Simon J. Clemett and Xavier D. F. Chillier and Claude Ricketts Maechling and Richard N. Zare},
  pages={924 - 930}
Fresh fracture surfaces of the martian meteorite ALH84001 contain abundant polycyclic aromatic hydrocarbons (PAHs). These fresh fracture surfaces also display carbonate globules. Contamination studies suggest that the PAHs are indigenous to the meteorite. High-resolution scanning and transmission electron microscopy study of surface textures and internal structures of selected carbonate globules show that the globules contain fine-grained, secondary phases of single-domain magnetite and iron… 

Modern terrestrial analogues for the carbonate globules in Martian meteorite ALH84001

Modern carbonate globules, located in cracks of submerged volcanic rocks and in calcareous pinnacles in alkaline (sodic) Lake Van, Turkey, appear to be analogues for the ~3.9 billion-year-old carbonates in Martian meteorite ALH84001, indicating that the ALH 84001 carbonates may have formed in similar setting on ancient Mars.

An Evaporation Model for Formation of Carbonates in the ALH84001 Martian Meteorite

Small, discoid globules and networks of magnesium-iron-calcium carbonates occur within impact-produced fracture zones in the ALH84001 Martian meteorite. Because these carbonates contain or are

Alteration Assemblages in Martian Meteorites: Implications for Near-Surface Processes

The SNC (Shergotty-Nakhla-Chassigny) meteorites have recorded interactions between martian crustal fluids and the parent igneous rocks. The resultant secondary minerals — which comprise up to ∼1

Submicron magnetite grains and carbon compounds in Martian meteorite ALH84001: inorganic, abiotic formation by shock and thermal metamorphism.

Purported biogenic features of the ALH84001 Martian meteorite (the carbonate globules, their submicron magnetite grains, and organic matter) have reasonable inorganic origins, and a comprehensive

The Search for Biosignatures in Martian Meteorite Allan Hills 84001

  • H. McSween
  • Geology
    Biosignatures for Astrobiology
  • 2018
Proposed biosignatures in the ancient Allan Hills 84001 martian meteorite are most plausibly explained as abiotic features. The purported evidence of biological activity on Mars included biogenic

Bulk and stable isotopic compositions of carbonate minerals in Martian meteorite Allan Hills 84001: No proof of high formation temperature

The bulk and stable isotopic compositions of the carbonate minerals are open to multiple interpretations and so lend no particular support to a high-temperature origin, and other methods will have to be used to determine the formation temperature of thecarbonates in ALH84001.

Petrographic and geochemical evidence for multiphase formation of carbonates in the Martian orthopyroxenite Allan Hills 84001

Martian meteorites can provide valuable information about past environmental conditions on Mars. Allan Hills 84001 formed more than 4 Gyr ago, and owing to its age and long exposure to the Martian

[Meteoritics and mineralogy on possible ancient Martian life].

The mineralogical and biomineralogical evidence for martian bacteria given by McKay et al. (1996) is controversial, and could be formed by non-biogenic processes, so further study of ALH84001 and other martian meteorites is required.

Graphite in the martian meteorite Allan Hills 84001

Abstract We use confocal Raman imaging spectroscopy and transmission electron microscopy to study the martian meteorite Allan Hills (ALH) 84001, reported to contain mineral assemblages within



A possible high-temperature origin for the carbonates in the martian meteorite ALH84001

It is argued that the most likely explanation for the observed compositions, and for the absence of co-existing hydrous minerals, is that the carbonates were formed by reactions between hot (>650 °C), CO2-rich fluids and the ultramafic host rock during an impact event.

What we have learned about Mars from SNC meteorites

The SNC meteorites are thought to be igneous martian rocks, based on their young crystallization ages and a close match between the composition of gases implanted in them during shock and the

Martian atmospheric carbon dioxide and weathering products in SNC meteorites

SNC meteorites—four shergottites, three nakhlites and Chassigny—are postulated to have originated on Mars1. Their late crystallization ages (<1,300 Myr compared with 4,600 Myr for other igneous

Magnetofossil dissolution in a palaeomagnetically unstable deep-sea sediment

MAGNETOFOSSILS1, the fossil remains of bacterial magneto-somes2, are found in various deep-sea sediments, and have been linked to the preservation of stable natural remanent magnetization in many of

Ultrafine-grained magnetite in deep-sea sediments: Possible bacterial magnetofossils

A new extraction technique now permits ultrafine magnetite crystals to be separated from a variety of deep-sea sediments. Morphologic characterization of these particles with transmission electron

ALH84001, a cumulate orthopyroxenite member of the martian meteorite clan

ALH84001, originally classified as a diogenite, is a coarse-grained, cataclastic, orthopyroxenite meteorite related to the martian (SNC) meteorites. The orthopyroxene is relatively uniform in

Soft-bodied fossils from a Silurian volcaniclastic deposit

A group of soft-bodied fossils from carbonate concretions within a volcanic ash are described, identifying an important new source ofsoft-bodied taxa in the Silurian of Italy.

Cyanobacterial precipitation of gypsum, calcite, and magnesite from natural alkaline lake water

Results from transmission electron microscopy provide direct evidence for cyanobacterial biomineralization of gypsum and calcite in aquatic environments. Laboratory simulations using

Lithoautotrophic Microbial Ecosystems in Deep Basalt Aquifers

Bacterial communities were detected in deep crystalline rock aquifers within the Columbia River Basalt Group (CRB). CRB ground waters contained up to 60 μM dissolved H2 and autotrophic microorganisms