Mineralogy and stratigraphy of phyllosilicate-bearing and dark mantling units in the greater Mawrth Vallis/west Arabia Terra area: Constraints on geological origin

被引：113

作者：

Dobrea, E. Z. Noe ^{[1
,2
]}

Bishop, J. L. ^{[3
]}

McKeown, N. K. ^{[4
]}

Fu, R. ^{[1
]}

Rossi, C. M. ^{[1
]}

Michalski, J. R. ^{[2
,4
]}

Heinlein, C. ^{[1
]}

Hanus, V. ^{[1
]}

Poulet, F. ^{[5
]}

Mustard, R. J. F. ^{[6
]}

Murchie, S. ^{[7
]}

McEwen, A. S. ^{[8
]}

Swayze, G. ^{[9
]}

Bibring, J. -P. ^{[5
]}

Malaret, E. ^{[10
]}

Hash, C. ^{[10
]}

机构：

[1] CALTECH, Jet Prop Lab, Pasadena, CA 91109 USA

[2] Planetary Sci Inst, Tucson, AZ 85710 USA

[3] SETI Inst, Mountain View, CA 94043 USA

[4] Univ Calif Santa Cruz, Dept Earth & Planetary Sci, Santa Cruz, CA 95064 USA

[5] Univ Paris 11, Inst Astrophys Spatiale, F-91405 Orsay, France

[6] Brown Univ, Dept Geol Sci, Providence, RI 02912 USA

[7] Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA

[8] Univ Arizona, Lunar & Planetary Lab, Tucson, AZ 85721 USA

[9] US Geol Survey, Denver, CO 80225 USA

[10] Appl Coherent Technol Corp, Herndon, VA 20170 USA

来源：

JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS | 2010年 / 115卷

关键词：

THERMAL-CONDUCTIVITY; MARS; REFLECTANCE; SPECTROSCOPY; SERPENTINES; EVOLUTION; SMECTITES; OLIVINE; SPECTRA; SILICA;

D O I：

10.1029/2009JE003351

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

Analyses of MRO/CRISM images of the greater Mawrth Vallis region of Mars affirm the presence of two primary phyllosilicate assemblages throughout a region similar to 1000 x 1000 km. These two units consist of an Fe/Mg-phyllosilicate assemblage overlain by an Al-phyllosilicate and hydrated silica assemblage. The lower unit contains Fe/Mg-smectites, sometimes combined with one or more of these other Fe/Mg-phyllosilicates: serpentine, chlorite, biotite, and/or vermiculite. It is more than 100 m thick and finely layered at meter scales. The upper unit includes Al-smectite, kaolin group minerals, and hydrated silica. It is tens of meters thick and finely layered as well. A common phyllosilicate stratigraphy and morphology is observed throughout the greater region wherever erosional windows are present. This suggests that the geologic processes forming these units must have occurred on at least a regional scale. Sinuous ridges (interpreted to be inverted channels) and narrow channels cut into the upper clay-bearing unit suggesting that aqueous processes were prevalent after, and possibly during, the deposition of the layered units. We propose that layered units may have been deposited at Mawrth Vallis and then subsequently altered to form the hydrated units. The Fe/Mg-phyllosilicate assemblage is consistent with hydrothermal alteration or pedogenesis of mafic to ultramafic rocks. The Al-phyllosilicate/hydrated silica unit may have formed through alteration of felsic material or via leaching of basaltic material through pedogenic alteration or a mildly acidic environment. These phyllosilicate-bearing units are overlain by a darker, relatively unaltered, and indurated material that has probably experienced a complex geological history.

引用

页数：27