The bulk of the Martian crust is basaltic with a wide variety of subsequently derived aqueous alteration phases. Study of analogue terrains is vital to better understand the weathering of such mafic bedrock at a range of surface temperatures. Moreover, climatic models have suggested that the early Martian climate was not warm and wet, but cold and icy, with some of the apparent fluvial and lacustrine features attributable to transient melting of ice sheets as opposed to persistent surface water. This study examines sediment samples from Collier glacial valley, Three Sisters, Oregon (OR), with the aim of better characterizing erosion, transport, and in situ aqueous alteration in a glaciated Mars-analogue terrain

Bamber, E. R.

Horgan, B.

Rampe, E. B.

Rutledge, A. M.

Scudder, N. A.

Smith, R. J.

NASA Technical Reports Server

SEDIMENT TRANSPORT AND AQUEOUS ALTERATION IN A MARS-ANALOG GLACIAL SYSTEM.  
E. R. Bamber1, E.B. Rampe2, B. Horgan3, R. J. Smith3, N. A. Scudder3, A. M. Rutledge3, 1Department of Earth Sciences, Univer-
sity of Oxford, Oxford, UK, 2Astromaterials Research and Exploration Science Division, NASA Johnson Space Centre, Houston, 
TX, USA, 3Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, IN, USA. Emi-
ly.Bamber@spc.ox.ac.uk 
Introduction: 
The bulk of the martian crust is basaltic [1, 2] with a 
wide variety of subsequently derived aqueous altera-
tion phases [3-5]. Study of analogue terrains is vital to 
better understand the weathering of such mafic bedrock 
at a range of surface temperatures. Moreover, climatic 
models have suggested that the early martian climate 
was not warm and wet, but cold and icy [6], with some 
of the apparent fluvial and lacustrine features attributa-
ble to transient melting of ice sheets as opposed to per-
sistent surface water [e.g. 6, 7]. 
This study examines sediment samples from Collier 
glacial valley, Three Sisters, Oregon (OR), with the 
aim of better characterizing erosion, transport, and in 
situ aqueous alteration in a glaciated Mars-analogue 
terrain. 
Methods: 
Collier glacier drains dacite, andesite, and basaltic an-
desite units [8, 9; Figure 1]. Basaltic andesite units 
show evidence of hydrothermal alteration. 
Samples were sieved to eight particle size fractions 
corresponding to divisions in the Wentworth classifica-
tion and the %wt for each size-component was meas-
ured. Samples were spiked with 20 wt% corundum as 
an internal standard for X-ray diffraction (XRD). XRD 
patterns were measured from 2-80 º2 at 100 seconds 
per step with a 0.0167º step size, in a Panalytical 
X’Pert Pro instrument with a Co-K source. Mineral 
abundances were determined using the Panalytical 
High Score Plus software (HSP) which, combined with 
measurement uncertainty, has a detection limit of 2-
3%wt. Rietveld refinement was conducted using the 
Jade software package, for a transect of moraine sam-
ples [Figure 1]. Jade has a detection limit of ~0.5%wt.  
Six field samples were selected for study in the JEOL 
7600F Scanning Electron Microscope (SEM) at John-
son Space Centre, Houston. Secondary electron images 
and EDS data were obtained at 15kV and 800pA.  
Results: 
The glacial sediments are dominated by the minerals 
plagioclase feldspar and pyroxene. Upstream and 
westwards, low-Ca dominates over high-Ca pyroxene. 
Downstream, pyroxene compositions vary. X-ray 
amorphous phases were also detected at up to 27%wt. 
All other phases detected did not exceed 10%wt.  
Quartz appears absent from the up-valley, eastern sed-
iments and displays a tendency to be concentrated in 
the coarser particle size fractions upstream and finer 
fractions on the banks of the proglacial lake. Magnetite 
also fines downstream like quartz. Hematite, a less 
abundant oxide, is associated with coarser grain sizes 
in the uppermost glacial toe-region and central-eastern 
side of the valley, close to hydrothermally altered ash 
units [8] and consistent with remote sensing observa-
tions [10]. Ilmenite is detected by Jade and SEM but 
not HSP, thus it’s distribution is not yet characterized. 
Zeolites were not detected using HSP nor SEM, but 
analysis using Jade identified chabazite in samples B 
and D on either side of the valley transect. 
Potassium feldspar was not detected by HSP, but a K-
bearing phase was detected by SEM in samples A and 
D. Jade suggested up to 5 %wt orthoclase in sample C 
in the cross-valley transect, but no others [Figure 2].  
The X-ray-amorphous content, evident from the broad 
hump centered around 3.8Å, is quantified using Jade 
for the east-west valley transect and varies between 0-
30%wt [Figure 2]. The composition of such poorly 
crystalline phases cannot be derived from XRD, but the 
potential candidates are primary volcanic glass and 
secondary alteration phases.  
Figure 1: Geological map of the area surrounding Collier glacier, 
adapted from [9]. mlb=mafic Little Brother (basaltic andesite); 
mns=mafic North Sister (basaltic andesite); mms=mafic Middle Sister 
(basaltic andesite); awc=andesite of west Collier; dbh=dacite of Black 
Hump. The locations of samples A-E along an east-west transect are 
indicated.  
2485.pdf49th Lunar and Planetary Science Conference 2018 (LPI Contrib. No. 2083)
https://ntrs.nasa.gov/search.jsp?R=20180004264 2019-08-31T15:20:46+00:00Z
Detailed investigation of the trends across the east-west 
transect revealed that sample mineralogy varies signifi-
cantly [Figure 2]. Sample C towards the east is notably 
distinct with potassium feldspar and trace amounts of 
actinolite within the modelled mineralogy. Zeolite was 
found in samples B and D. Sample E contains the 
greatest amorphous content. 
Discussion: 
The varying abundances of certain mineral phases up-
stream indicates the extent of contribution from the 
more evolved volcanic rocks (andesite awc and dacite 
dbh). Increasing low-Ca pyroxene and quartz content 
eastwards downstream signifies homogenization. More 
detailed textural and compositional analyses of primary 
phases could expose trends not noted here.  
The concentration of quartz and oxides in finer frac-
tions downstream is consistent with physical weather-
ing during glacial transport of bedrock. However, due 
to the low %wt of such phases, close to the detection 
limit of HSP, patterns require confirmation by Jade.  
Crystalline alteration phases (zeolites and hematite) are 
detected at low %wt in samples and are most likely 
derived from altered units on North Sister and Little 
Brother [Figure 1; 8]. The absence of any significant 
amounts of crystalline phases formed in situ indicates 
that glacial environments lead to minimal chemical 
alteration. However, amorphous alteration phases may 
be present since the amorphous hump in XRD patterns 
is not entirely consistent with just volcanic glass [10, 
11]. Transmission electron microscopy of sediment 
samples [12] has identified several of these phases in-
cluding nanophase iron oxides and “proto-clays”. Ob-
servations of similar amorphous materials on Mars [3, 
4, 13-16] may be evidence of the Red Planet’s ancient 
glaciated surface. 
Across the east-west transect, mineralogical variations 
indicate bedrock source units for each sample [Figure 
2]. For example, the distinct mineralogy of sample C 
replicates that of the unit awc [Figure 1]. However, 
sample E has a much higher amorphous content than 
it’s adjacent unit mns, potentially due to the in situ 
formation of amorphous alteration phases.  
Overall, the olivine content is less than that of the 
mafic source units, indicating increased dissolution 
relative to other primary phases.  
Conclusions: 
The main downstream trends are the increased mixing 
of phases and confinement of rarer minerals to fine-
grained fractions. Cross-valley mineralogical variations 
are clearly related to the bedrock source region, except 
for in olivine and amorphous content which may com-
prise the main weathering signature of mafic glacial 
terrains. The near absence of crystalline alteration 
phases confirms there is minimal chemical alteration. 
In comparison to Mars, the wide variety of secondary 
phases [5] detected by the Curiosity at Gale Crater 
[17], could not be produced in a glacial terrain similar 
to the Three Sisters volcanic complex. On the other 
hand, the amorphous content at Gale [13-16] is compa-
rable to that of Collier glacial valley and probably not 
produced by a warm, wet climate. Some work has ad-
dressed the nature of the amorphous phases within Col-
lier [11, 12, 18], but more is needed to further charac-
terize the unique weak alteration signatures produced 
in a mafic glacial terrain. 
Acknowledgements: 
We are grateful to Dr. Eve Berger for helpful comments re-
lated to SEM work. We thank LPI, USRA, and colleagues at 
NASA JSC for supporting Emily Bamber as a summer intern 
to undertake this research.  
References: [1] A. D. Rogers and P. R. Christensen (2007) 
JGR, 112: E01003 [2] H. Y. Mcsween et al. (2009) Science, 324: 
736-739 [3] B. Horgan and J. Bell (2012) Geology, 40: 391-394 [4] 
E. B. Rampe et al. (2012) Geology, 40: 995-998 [5] B. L. Ehlmann 
and C.S. Edwards (2014) Annu. Rev. Earth Planet. Sci., 42:291–315 
[6] R. Wordsworth et al. (2013) Icarus, 222: 1-19 [7] J. W. Head 
and D. R. Marchant (2014) Antarctic Science, 26(6): 774-800 [8] 
M. E. Schmidt and A. L. Grunder (2009) GSA bulletin, 121: 643-
662 [9] W. Hildreth et al. (2012) USGS, Scientific Investigations 
Map 3186 [10] N. A. Scudder et al. (2017) LPSC XLVIII #2625 
[11] R. J. Smith et al. (2017) LPSC XLVIII, #2465 [12] E. B. 
Rampe et al. (2017) GSA Annual Meeting [13] D. L. Bish et al. 
(2013) Science, 341(6153): 1238932 [14] D. F. Blake et al. (2013) 
Science, 341(6153): 1239505 [15] D.T. Vaniman et al (2014) Sci-
ence, 343(6169):1243480 [16] R. V. Morris et al. (2015) LPSC 
XLVI #2434 [17] E. B. Rampe et al. (2016) LPSC XLVII #2543 
[18] E. B. Rampe et al (2017) AGU P33C-2892. 
 
WEST                                                                                                                                                    EAST 
Figure 2: Pie charts indicating the weighted average abundance of mineral phases in samples A-E across the central valley transect, as modeled by 
JADE and weighted by %wt in each particle size fraction. KEY: orange = plag (andesine, labradorite, anorthite, albite), pink = Kfs, dark blue = High-Ca px, light 
blue = low-Ca px, green = olivine, reds = oxides (hematite, magnetite), purple = fluorapatite, light grey = amorphous, dark grey = zeolite, dark green = actinolite 
D E A B C 
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Sediment Transport and Aqueous Alteration in a Mars-Analog Glacial System

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