Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer

Evidence for near-surface water

Philip Christensen, J. L. Bandfield, R. N. Clark, K. S. Edgett, V. E. Hamilton, T. Hoefen, H. H. Kieffer, R. O. Kuzmin, M. D. Lane, M. C. Malin, R. V. Morris, J. C. Pearl, R. Pearson, T. L. Roush, Steven Ruff, M. D. Smith

Research output: Contribution to journalArticle

369 Citations (Scopus)

Abstract

The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite (α-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2° S latitude between 0° and 5° W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525 cm-1 and by the absence of silicate fundamentals in the 1000 cm-1 region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 μm). Diameters up to and greater than hundreds of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 μm in diameter (as either unpacked or hard-packed powders) fail to match the TES spectra. The spectrally derived areal abundance of hematite varies with particle size from ∼10% (>30 μm diameter) to 40-60% (10 μm diameter). The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 μm), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it might be a late stage sedimentary unit or a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: the first is chemical precipitation that includes origin by (1) precipitation from standing, oxygenated, Fe-rich water (oxide iron formations), (2) precipitation from Fe-rich hydrothermal fluids, (3) low-temperature dissolution and precipitation through mobile ground water leaching, and (4) formation of surface coatings, and the second is thermal oxidation of magnetite-rich lavas. Weathering and alteration processes, which produce nanophase and red hematite, are not consistent with the coarse, crystalline hematite observed in Sinus Meridiani. We prefer chemical precipitation models and favor precipitation from Fe-rich water on the basis of the probable association with sedimentary materials, large geographic size, distance from a regional heat source, and lack of evidence for extensive groundwater processes elsewhere on Mars. The TES results thus provide mineralogic evidence for probable large-scale water interactions. The Sinus Meridiani region may be an ideal candidate for future landed missions searching for biotic and prebiotic environments, and the physical characteristics of this site satisfy all of the engineering requirements for the missions currently planned.

Original languageEnglish (US)
Pages (from-to)9623-9642
Number of pages20
JournalJournal of Geophysical Research E: Planets
Volume105
Issue numberE4
StatePublished - Apr 25 2000

Fingerprint

thermal emission
hematite
surface water
Surface waters
mars
Spectrometers
Mars
spectrometer
spectrometers
mineralization
Crystalline materials
sinuses
precipitation (chemistry)
Water
ground water
water
detection
Hot Temperature
ferric oxide
Groundwater

ASJC Scopus subject areas

  • Earth and Planetary Sciences (miscellaneous)
  • Atmospheric Science
  • Geochemistry and Petrology
  • Geophysics
  • Oceanography
  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Christensen, P., Bandfield, J. L., Clark, R. N., Edgett, K. S., Hamilton, V. E., Hoefen, T., ... Smith, M. D. (2000). Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer: Evidence for near-surface water. Journal of Geophysical Research E: Planets, 105(E4), 9623-9642.

Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer : Evidence for near-surface water. / Christensen, Philip; Bandfield, J. L.; Clark, R. N.; Edgett, K. S.; Hamilton, V. E.; Hoefen, T.; Kieffer, H. H.; Kuzmin, R. O.; Lane, M. D.; Malin, M. C.; Morris, R. V.; Pearl, J. C.; Pearson, R.; Roush, T. L.; Ruff, Steven; Smith, M. D.

In: Journal of Geophysical Research E: Planets, Vol. 105, No. E4, 25.04.2000, p. 9623-9642.

Research output: Contribution to journalArticle

Christensen, P, Bandfield, JL, Clark, RN, Edgett, KS, Hamilton, VE, Hoefen, T, Kieffer, HH, Kuzmin, RO, Lane, MD, Malin, MC, Morris, RV, Pearl, JC, Pearson, R, Roush, TL, Ruff, S & Smith, MD 2000, 'Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer: Evidence for near-surface water', Journal of Geophysical Research E: Planets, vol. 105, no. E4, pp. 9623-9642.
Christensen, Philip ; Bandfield, J. L. ; Clark, R. N. ; Edgett, K. S. ; Hamilton, V. E. ; Hoefen, T. ; Kieffer, H. H. ; Kuzmin, R. O. ; Lane, M. D. ; Malin, M. C. ; Morris, R. V. ; Pearl, J. C. ; Pearson, R. ; Roush, T. L. ; Ruff, Steven ; Smith, M. D. / Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer : Evidence for near-surface water. In: Journal of Geophysical Research E: Planets. 2000 ; Vol. 105, No. E4. pp. 9623-9642.
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abstract = "The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite (α-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2° S latitude between 0° and 5° W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525 cm-1 and by the absence of silicate fundamentals in the 1000 cm-1 region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 μm). Diameters up to and greater than hundreds of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 μm in diameter (as either unpacked or hard-packed powders) fail to match the TES spectra. The spectrally derived areal abundance of hematite varies with particle size from ∼10{\%} (>30 μm diameter) to 40-60{\%} (10 μm diameter). The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 μm), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it might be a late stage sedimentary unit or a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: the first is chemical precipitation that includes origin by (1) precipitation from standing, oxygenated, Fe-rich water (oxide iron formations), (2) precipitation from Fe-rich hydrothermal fluids, (3) low-temperature dissolution and precipitation through mobile ground water leaching, and (4) formation of surface coatings, and the second is thermal oxidation of magnetite-rich lavas. Weathering and alteration processes, which produce nanophase and red hematite, are not consistent with the coarse, crystalline hematite observed in Sinus Meridiani. We prefer chemical precipitation models and favor precipitation from Fe-rich water on the basis of the probable association with sedimentary materials, large geographic size, distance from a regional heat source, and lack of evidence for extensive groundwater processes elsewhere on Mars. The TES results thus provide mineralogic evidence for probable large-scale water interactions. The Sinus Meridiani region may be an ideal candidate for future landed missions searching for biotic and prebiotic environments, and the physical characteristics of this site satisfy all of the engineering requirements for the missions currently planned.",
author = "Philip Christensen and Bandfield, {J. L.} and Clark, {R. N.} and Edgett, {K. S.} and Hamilton, {V. E.} and T. Hoefen and Kieffer, {H. H.} and Kuzmin, {R. O.} and Lane, {M. D.} and Malin, {M. C.} and Morris, {R. V.} and Pearl, {J. C.} and R. Pearson and Roush, {T. L.} and Steven Ruff and Smith, {M. D.}",
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TY - JOUR

T1 - Detection of crystalline hematite mineralization on Mars by the Thermal Emission Spectrometer

T2 - Evidence for near-surface water

AU - Christensen, Philip

AU - Bandfield, J. L.

AU - Clark, R. N.

AU - Edgett, K. S.

AU - Hamilton, V. E.

AU - Hoefen, T.

AU - Kieffer, H. H.

AU - Kuzmin, R. O.

AU - Lane, M. D.

AU - Malin, M. C.

AU - Morris, R. V.

AU - Pearl, J. C.

AU - Pearson, R.

AU - Roush, T. L.

AU - Ruff, Steven

AU - Smith, M. D.

PY - 2000/4/25

Y1 - 2000/4/25

N2 - The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite (α-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2° S latitude between 0° and 5° W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525 cm-1 and by the absence of silicate fundamentals in the 1000 cm-1 region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 μm). Diameters up to and greater than hundreds of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 μm in diameter (as either unpacked or hard-packed powders) fail to match the TES spectra. The spectrally derived areal abundance of hematite varies with particle size from ∼10% (>30 μm diameter) to 40-60% (10 μm diameter). The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 μm), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it might be a late stage sedimentary unit or a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: the first is chemical precipitation that includes origin by (1) precipitation from standing, oxygenated, Fe-rich water (oxide iron formations), (2) precipitation from Fe-rich hydrothermal fluids, (3) low-temperature dissolution and precipitation through mobile ground water leaching, and (4) formation of surface coatings, and the second is thermal oxidation of magnetite-rich lavas. Weathering and alteration processes, which produce nanophase and red hematite, are not consistent with the coarse, crystalline hematite observed in Sinus Meridiani. We prefer chemical precipitation models and favor precipitation from Fe-rich water on the basis of the probable association with sedimentary materials, large geographic size, distance from a regional heat source, and lack of evidence for extensive groundwater processes elsewhere on Mars. The TES results thus provide mineralogic evidence for probable large-scale water interactions. The Sinus Meridiani region may be an ideal candidate for future landed missions searching for biotic and prebiotic environments, and the physical characteristics of this site satisfy all of the engineering requirements for the missions currently planned.

AB - The Thermal Emission Spectrometer (TES) instrument on the Mars Global Surveyor (MGS) mission has discovered a remarkable accumulation of crystalline hematite (α-Fe2O3) that covers an area with very sharp boundaries approximately 350 by 350-750 km in size centered near 2° S latitude between 0° and 5° W longitude (Sinus Meridiani). Crystalline hematite is uniquely identified by the presence of fundamental vibrational absorption features centered near 300, 450, and >525 cm-1 and by the absence of silicate fundamentals in the 1000 cm-1 region. Spectral features resulting from atmospheric CO2, dust, and water ice were removed using a radiative transfer model. The spectral properties unique to Sinus Meridiani were emphasized by removing the average spectrum of the surrounding region. The depth and shape of the hematite fundamental bands show that the hematite is crystalline and relatively coarse grained (>5-10 μm). Diameters up to and greater than hundreds of micrometers are permitted within the instrumental noise and natural variability of hematite spectra. Hematite particles <5-10 μm in diameter (as either unpacked or hard-packed powders) fail to match the TES spectra. The spectrally derived areal abundance of hematite varies with particle size from ∼10% (>30 μm diameter) to 40-60% (10 μm diameter). The hematite in Sinus Meridiani is thus distinct from the fine-grained (diameter <5-10 μm), red, crystalline hematite considered, on the basis of visible, near-IR data, to be a minor spectral component in Martian bright regions like Olympus-Amazonis. Sinus Meridiani hematite is closely associated with a smooth, layered, friable surface that is interpreted to be sedimentary in origin. This material may be the uppermost surface in the region, indicating that it might be a late stage sedimentary unit or a layered portion of the heavily cratered plains units. We consider five possible mechanisms for the formation of coarse-grained, crystalline hematite. These processes fall into two classes depending on whether they require a significant amount of near-surface water: the first is chemical precipitation that includes origin by (1) precipitation from standing, oxygenated, Fe-rich water (oxide iron formations), (2) precipitation from Fe-rich hydrothermal fluids, (3) low-temperature dissolution and precipitation through mobile ground water leaching, and (4) formation of surface coatings, and the second is thermal oxidation of magnetite-rich lavas. Weathering and alteration processes, which produce nanophase and red hematite, are not consistent with the coarse, crystalline hematite observed in Sinus Meridiani. We prefer chemical precipitation models and favor precipitation from Fe-rich water on the basis of the probable association with sedimentary materials, large geographic size, distance from a regional heat source, and lack of evidence for extensive groundwater processes elsewhere on Mars. The TES results thus provide mineralogic evidence for probable large-scale water interactions. The Sinus Meridiani region may be an ideal candidate for future landed missions searching for biotic and prebiotic environments, and the physical characteristics of this site satisfy all of the engineering requirements for the missions currently planned.

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