Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Treiman, Allan H.; Essene, Eric J.

doi:10.1016/j.gca.2011.06.038

Cited by 15 publications

(10 citation statements)

References 62 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both huntite and nesquehonite can serve as precursors to magnesite. The latter rapidly transforms to hydromagnesite ((Mg 5 (CO 3 ) 4 (OH) 2 · 4H 2 O) by the loss of crystalline water and dehydroxylation with a minor temperature increase (≥52 °C; Davies and Bubela ) and then to magnesite at >220 °C (Hollingbery and Hull ), consistent with the observation of higher P‐T magnetite and graphite in the meteorite (Treiman and Essene ; Steele et al. ).…”

Section: Thermochemical Modeling Methodssupporting

confidence: 79%

See 1 more Smart Citation

Alteration minerals, fluids, and gases on early Mars: Predictions from 1‐D flow geochemical modeling of mineral assemblages in meteorite ALH 84001

Daswani

Schwenzer

Reed

et al. 2016

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Abstract-Clay minerals, although ubiquitous on the ancient terrains of Mars, have not been observed in Martian meteorite Allan Hills (ALH) 84001, which is an orthopyroxenite sample of the early Martian crust with a secondary carbonate assemblage. We used a lowtemperature (20°C) one-dimensional (1-D) transport thermochemical model to investigate the possible aqueous alteration processes that produced the carbonate assemblage of ALH 84001 while avoiding the coprecipitation of clay minerals. We found that the carbonate in ALH 84001 could have been produced in a process, whereby a low-temperature (~20°C) fluid, initially equilibrated with the early Martian atmosphere, moved through surficial clay mineral and silica-rich layers, percolated through the parent rock of the meteorite, and precipitated carbonates (thereby decreasing the partial pressure of CO 2 ) as it evaporated. This finding requires that before encountering the unweathered orthopyroxenite host of ALH 84001, the fluid permeated rock that became weathered during the process. We were able to predict the composition of the clay minerals formed during weathering, which included the dioctahedral smectite nontronite, kaolinite, and chlorite, all of which have been previously detected on Mars. We also calculated host rock replacement in local equilibrium conditions by the hydrated silicate talc, which is typically considered to be a higher temperature hydrothermal phase on Earth, but may have been a common constituent in the formation of Martian soils through pervasive aqueous alteration. Finally, goethite and magnetite were also found to precipitate in the secondary alteration assemblage, the latter associated with the generation of H 2 . Apparently, despite the limited water-rock interaction that must have led to the formation of the carbonates~3.9 Ga ago, in the vicinity of the ALH 84001 source rocks, clay formation would have been widespread.

show abstract

Section: Thermochemical Modeling Methodssupporting

confidence: 79%

“…, ; Steele et al. ; Treiman and Essene ). A large range of pressure–temperature (P‐T) conditions have been invoked to explain the abiotic formation of the alteration assemblage (see supporting information, Fig.…”

Section: Introductionmentioning

confidence: 99%

Alteration minerals, fluids, and gases on early Mars: Predictions from 1‐D flow geochemical modeling of mineral assemblages in meteorite ALH 84001

Daswani

Schwenzer

Reed

et al. 2016

Meteorit & Planetary Scien

View full text Add to dashboard Cite

show abstract

“…In the former hypothesis, as CO 2 -containing aqueous fluids cooled out of equilibrium, f O 2 fluctuated to a large extent at the nanoscale within the growing carbonates. Under these conditions, graphite deposition with magnetite would be possible during the bulk deposition of carbonate (Brearley 2003;French 1971;French and Rosenberg 1965;Koziol 2004;McCollom 2003;Steele et al 2007;Treiman et al 2002;Treiman and Essene 2011). In the latter, the same phase relationships are applicable, but siderite in already formed globules decomposes to graphite and magnetite during a transient heating event possibly linked to impact derived ejection from the martian surface (Brearley 2003;French 1971;French and Rosenberg 1965;Koziol 2004;McCollom 2003;Steele et al 2007;Treiman et al 2002;Treiman and Essene 2011).…”

Section: Discussionmentioning

confidence: 99%

“…This approach required an understanding of the phase relationships of iron oxides, graphite (which had not been identified), and CO 2 over a range of P, T, and f O 2 (Brearley 2003;French 1971;French and Rosenberg 1965;Koziol 2004;McCollom 2003;Steele et al 2007;Treiman et al 2002;Treiman and Essene 2011). Within these relationships there are two competing abiotic hypotheses to explain the carbonate assemblages, both of which require the presence of graphite:…”

Section: Discussionmentioning

confidence: 99%

Graphite in the martian meteorite Allan Hills 84001

Steele

McCubbin

Fries

et al. 2012

American Mineralogist

View full text Add to dashboard Cite

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 carbonate globules (carbonate + magnetite), interpreted as potential relict signatures of ancient martian biota. Models for an abiologic origin for these assemblages required the presence of graphite, and this study is the first report of graphite within ALH 84001. The graphite occurs as hollow spheres (nano-onions), filaments, and highly crystalline particles in intimate association with magnetite in the carbonate globules. In addition to supporting an abiologic origin for the carbonate globule assemblages in ALH 84001, this work proves that there is an inventory of reduced-carbon phases on Mars that has not yet been thoroughly investigated.

show abstract

“…). However, the temperature history of this meteorite is complicated and the exact method of globule formation is still not fully understood (Treiman and Essene ), which makes further elucidation of the formation mechanism for the secondary carbonates and graphite in ALH 84001 difficult.…”

Section: Geological Implications For Reduced Organic Carbon On Marsmentioning

confidence: 99%

The provenance, formation, and implications of reduced carbon phases in Martian meteorites

Steele

McCubbin

Fries

2016

Meteorit & Planetary Scien

View full text Add to dashboard Cite

This review is intended to summarize the current observations of reduced carbon in Martian meteorites, differentiating between terrestrial contamination and carbon that is indigenous to Mars. Indeed, the identification of Martian organic matter is among the highest priority targets for robotic spacecraft missions in the next decade, including the Mars Science Laboratory and Mars 2020. Organic carbon compounds are essential building blocks of terrestrial life, so the occurrence and origin (biotic or abiotic) of organic compounds on Mars is of great significance; however, not all forms of reduced carbon are conducive to biological systems. This paper discusses the significance of reduced organic carbon (including methane) in Martian geological and astrobiological systems. Specifically, it summarizes current thinking on the nature, sources, and sinks of Martian organic carbon, a key component to Martian habitability. Based on this compilation, reduced organic carbon on Mars, including detections of methane in the Martian atmosphere, is best described through a combination of abiotic organic synthesis on Mars and infall of extraterrestrial carbonaceous material. Although conclusive signs of Martian life have yet to be revealed, we have developed a strategy for life detection on Mars that can be utilized in future life-detection studies.

show abstract

Chemical composition of magnetite in Martian meteorite ALH 84001: Revised appraisal from thermochemistry of phases in Fe–Mg–C–O

Cited by 15 publications

References 62 publications

Alteration minerals, fluids, and gases on early Mars: Predictions from 1‐D flow geochemical modeling of mineral assemblages in meteorite ALH 84001

Alteration minerals, fluids, and gases on early Mars: Predictions from 1‐D flow geochemical modeling of mineral assemblages in meteorite ALH 84001

Graphite in the martian meteorite Allan Hills 84001

The provenance, formation, and implications of reduced carbon phases in Martian meteorites

Contact Info

Product

Resources

About