TY - JOUR
T1 - Constraints on iron sulfate and iron oxide mineralogy from ChemCam visible/near-infrared reflectance spectroscopy of Mt. Sharp basal units, Gale Crater, Mars
AU - Johnson, Jeffrey R.
AU - Bell, James
AU - Bender, Steve
AU - Blaney, Diana
AU - Cloutis, Edward
AU - Ehlmann, Bethany
AU - Fraeman, Abigail
AU - Gasnault, Olivier
AU - Kinch, Kjartan
AU - Le Mouelic, Stephane
AU - Maurice, Sylvestre
AU - Rampe, Elizabeth
AU - Vaniman, David
AU - Wiens, Roger C.
N1 - Funding Information:
This work was funded by the NASA Mars Science Laboratory Participating Scientist program through the Jet Propulsion Laboratory (contract 1350588). The U.S. portion of ChemCam and MSL rover operations was funded by NASA's Mars Exploration Program. The French contribution to MSL is supported by the Centre National d'Etudes Spatiales (CNES). Work by K. Kinch was supported by the Danish Council for Independent Research/Natural Sciences (FNU grant 12.127126).
Publisher Copyright:
© 2016 by Walter de Gruyter Berlin/Boston.
PY - 2016/7/1
Y1 - 2016/7/1
N2 - Relative reflectance point spectra (400-840 nm) were acquired by the Chemistry and Camera (ChemCam) instrument on the Mars Science Laboratory (MSL) rover Curiosity in passive mode (no laser) of drill tailings and broken rock fragments near the rover as it entered the lower reaches of Mt. Sharp and of landforms at distances of 2-8 km. Freshly disturbed surfaces are less subject to the spectral masking effects of dust, and revealed spectral features consistent with the presence of iron oxides and ferric sulfates. We present the first detection on Mars of a ~433 nm absorption band consistent with small abundances of ferric sulfates, corroborated by jarosite detections by the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument in the Mojave, Telegraph Peak, and Confidence Hills drilled samples. Disturbed materials near the Bonanza King region also exhibited strong 433 nm bands and negative near-infrared spectral slopes consistent with jarosite. ChemCam passive spectra of the Confidence Hills and Mojave drill tailings showed features suggestive of the crystalline hematite identified by CheMin analyses. The Windjana drill sample tailings exhibited flat, low relative reflectance spectra, explained by the occurrence of magnetite detected by CheMin. Passive spectra of Bonanza King were similar, suggesting the presence of spectrally dark and neutral minerals such as magnetite. Long-distance spectra of the "Hematite Ridge" feature (3-5 km from the rover) exhibited features consistent with crystalline hematite. The Bagnold dune field north of the Hematite Ridge area exhibited low relative reflectance and near-infrared features indicative of basaltic materials (olivine, pyroxene). Light-toned layers south of Hematite Ridge lacked distinct spectral features in the 400-840 nm region, and may represent portions of nearby clay minerals and sulfates mapped with orbital near-infrared observations. The presence of ferric sulfates such as jarosite in the drill tailings suggests a relatively acidic environment, likely associated with flow of iron-bearing fluids, associated oxidation, and/or hydrothermal leaching of sedimentary rocks. Combined with other remote sensing data sets, mineralogical constraints from ChemCam passive spectra will continue to play an important role in interpreting the mineralogy and composition of materials encountered as Curiosity traverses further south within the basal layers of the Mt. Sharp complex.
AB - Relative reflectance point spectra (400-840 nm) were acquired by the Chemistry and Camera (ChemCam) instrument on the Mars Science Laboratory (MSL) rover Curiosity in passive mode (no laser) of drill tailings and broken rock fragments near the rover as it entered the lower reaches of Mt. Sharp and of landforms at distances of 2-8 km. Freshly disturbed surfaces are less subject to the spectral masking effects of dust, and revealed spectral features consistent with the presence of iron oxides and ferric sulfates. We present the first detection on Mars of a ~433 nm absorption band consistent with small abundances of ferric sulfates, corroborated by jarosite detections by the Chemistry and Mineralogy (CheMin) X-ray diffraction instrument in the Mojave, Telegraph Peak, and Confidence Hills drilled samples. Disturbed materials near the Bonanza King region also exhibited strong 433 nm bands and negative near-infrared spectral slopes consistent with jarosite. ChemCam passive spectra of the Confidence Hills and Mojave drill tailings showed features suggestive of the crystalline hematite identified by CheMin analyses. The Windjana drill sample tailings exhibited flat, low relative reflectance spectra, explained by the occurrence of magnetite detected by CheMin. Passive spectra of Bonanza King were similar, suggesting the presence of spectrally dark and neutral minerals such as magnetite. Long-distance spectra of the "Hematite Ridge" feature (3-5 km from the rover) exhibited features consistent with crystalline hematite. The Bagnold dune field north of the Hematite Ridge area exhibited low relative reflectance and near-infrared features indicative of basaltic materials (olivine, pyroxene). Light-toned layers south of Hematite Ridge lacked distinct spectral features in the 400-840 nm region, and may represent portions of nearby clay minerals and sulfates mapped with orbital near-infrared observations. The presence of ferric sulfates such as jarosite in the drill tailings suggests a relatively acidic environment, likely associated with flow of iron-bearing fluids, associated oxidation, and/or hydrothermal leaching of sedimentary rocks. Combined with other remote sensing data sets, mineralogical constraints from ChemCam passive spectra will continue to play an important role in interpreting the mineralogy and composition of materials encountered as Curiosity traverses further south within the basal layers of the Mt. Sharp complex.
KW - IR spectroscopy
KW - Invited Centennial article
KW - Mars remote sensing
KW - Mars spectroscopy
KW - ferric sulfates
KW - iron oxides
KW - visible/near-infrared
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U2 - 10.2138/am-2016-5553
DO - 10.2138/am-2016-5553
M3 - Article
AN - SCOPUS:84983320168
SN - 0003-004X
VL - 101
SP - 1501
EP - 1514
JO - American Mineralogist
JF - American Mineralogist
IS - 7
ER -