ChemCam results from the Shaler outcrop in Gale crater, Mars

doi:10.1016/j.icarus.2014.07.025

Icarus

Volume 249, 15 March 2015, Pages 2-21

https://doi.org/10.1016/j.icarus.2014.07.025 Get rights and content

Highlights

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ChemCam collected spectra and images from 26 targets on 5 of the 7 facies at Shaler.
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Facies 3 has low K₂O, while Facies 7 has high K₂O.
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Shaler overall has higher K₂O than other stratigraphic units.
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Elevated K₂O may indicate an alkaline igneous source.
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There is little evidence for chemical alteration at Shaler.

Abstract

The ChemCam campaign at the fluvial sedimentary outcrop “Shaler” resulted in observations of 28 non-soil targets, 26 of which included active laser induced breakdown spectroscopy (LIBS), and all of which included Remote Micro-Imager (RMI) images. The Shaler outcrop can be divided into seven facies based on grain size, texture, color, resistance to erosion, and sedimentary structures. The ChemCam observations cover Facies 3 through 7. For all targets, the majority of the grains were below the limit of the RMI resolution, but many targets had a portion of resolvable grains coarser than ∼0.5 mm. The Shaler facies show significant scatter in LIBS spectra and compositions from point to point, but several key compositional trends are apparent, most notably in the average K₂O content of the observed facies. Facies 3 is lower in K₂O than the other facies and is similar in composition to the “snake,” a clastic dike that occurs lower in the Yellowknife Bay stratigraphic section. Facies 7 is enriched in K₂O relative to the other facies and shows some compositional and textural similarities to float rocks near Yellowknife Bay. The remaining facies (4, 5, and 6) are similar in composition to the Sheepbed and Gillespie Lake members, although the Shaler facies have slightly elevated K₂O and FeO_T. Several analysis points within Shaler suggest the presence of feldspars, though these points have excess FeO_T which suggests the presence of Fe oxide cement or inclusions. The majority of LIBS analyses have compositions which indicate that they are mixtures of pyroxene and feldspar. The Shaler feldspathic compositions are more alkaline than typical feldspars from shergottites, suggesting an alkaline basaltic source region, particularly for the K₂O-enriched Facies 7. Apart from possible iron-oxide cement, there is little evidence for chemical alteration at Shaler, although calcium-sulfate veins comparable to those observed lower in the stratigraphic section are present. The differing compositions, and inferred provenances at Shaler, suggest compositionally heterogeneous terrain in the Gale crater rim and surroundings, and intermittent periods of deposition.

Introduction

The Curiosity rover landed on the floor of Gale crater (137.7°E, 5.44°S) in a region that has been described as “hummocky” based on orbital mapping (Anderson and Bell, 2010, Grotzinger et al., 2013, Rice et al., 2013). Sporadic rock outcrops in the vicinity of the landing site comprise sedimentary conglomerate deposits which have been interpreted as evidence of ancient fluvial activity (Williams et al., 2013). Upon landing, the Mars Science Laboratory (MSL) science team decided to drive east toward a location named “Glenelg” where three geologic units observed from orbit converged (Grotzinger et al., 2013). The three units are the hummocky plains, a distinctive heavily cratered surface, and a light-toned, fractured unit inferred to be the distal facies of the alluvial fan that occupies much of the Curiosity landing site (Anderson and Bell, 2010, Palucis et al., 2013).

Outcrops of the light-toned, fractured unit nearest to Glenelg, informally named “Yellowknife Bay,” are roughly 18 m lower in elevation than the rover’s initial landing location. The lowest ∼4 m of the section are composed of (in descending order) the Glenelg, Gillespie Lake, and Sheepbed members (Grotzinger et al., 2013). The Sheepbed member is a smectite-bearing mudstone with elemental composition similar to the average martian crust (Grotzinger et al., 2013, McLennan et al., 2013, Vaniman et al., 2013). The Gillespie Lake member is ∼2.0 m thick and comprises a poorly sorted sandstone that overlies the Sheepbed member, and is interpreted as a distal fluvial sandstone (Grotzinger et al., 2013). It has a composition similar to the Sheepbed mudstone (McLennan et al., 2013). Overlying Gillespie Lake is the Glenelg member, which is composed of the Point Lake, Shaler, Rocknest, and Bathurst outcrops. Point Lake is characterized by pervasive cm-scale voids (Grotzinger et al., 2013), and Rocknest is characterized by fine-grained well-cemented rocks with high iron content (Blaney et al., 2014). Bathurst is a fine-grained layered rock with elevated K₂O (Grotzinger et al., 2013, Mangold et al., submitted for publication).

The “Shaler” outcrop is located at 137.4488°E 4.5905°S (planetocentric), near the location in the Glenelg region where the three distinct terrain types meet. Shaler was first identified in panoramic images from the Rocknest aeolian drift. From this distance (∼40 m), it stood out as a unique thinly layered outcrop of resistant and recessive strata (Fig. 1), and due to its appearance it received the name “Shaler”. The outcrop is approximately 0.7 m thick and >20 m long, and consists of well-exposed cross-stratified sandstones with significant variation in erosional-resistance, resulting in interstratification of resistant pebbly sandstones and recessive intervals. Curiosity first encountered the Shaler outcrop on sol 120 of the mission, during the descent into Yellowknife Bay, when it was analyzed only briefly by ChemCam and Mastcam.

After the science campaign in Yellowknife Bay was completed, Curiosity followed a path back up onto the hummocky plains and once again passed near Shaler. Given the interesting sedimentary structures in the Shaler outcrop, the Curiosity science team decided to conduct a more detailed investigation of Shaler on sols 309–324.

Because of the rugged nature of the exposed beds and the limited time available to analyze the outcrop, arm contact science was only possible from one rover location. However, the ChemCam instrument can analyze targets from a distance (<7 m) to determine their chemistry (Maurice et al., 2012, Wiens et al., 2012), and the Remote Micro-Imager (RMI) provides images that permit detailed analysis of target grain sizes and fine-scale sedimentary structures. The remote measurement capabilities of ChemCam were invaluable in the geologic triage at Shaler.

Here we use the results from the ChemCam campaign at Shaler to investigate sedimentary textures, examine the chemostratigraphy of the outcrop, and evaluate the composition and diagenetic history of the sedimentary facies that comprise Shaler. Detailed description of the sedimentology and stratigraphy of Shaler, and an interpretation of the sedimentary processes and paleoenvironments are presented elsewhere (Edgar et al., submitted for publication).

Note that all target and unit names used in this manuscript are informal names assigned by the Curiosity science team.

Section snippets

Methods and data

The ChemCam instrument (Maurice et al., 2012, Wiens et al., 2012) collects both spectroscopic and image data. ChemCam acquired data from a total of 28 non-soil targets at Shaler, 26 of which included active laser-induced breakdown spectroscopy (LIBS) plus context RMI imagery, and 2 of which were imaged with the RMI without accompanying LIBS spectra. Table 1 summarizes the ChemCam observations at Shaler, including the average ChemCam compositions in wt.%, and Fig. 1, Fig. 2 show the locations of

Shaler facies

The Shaler outcrop can be subdivided into seven facies based on grain size, resistance to erosion, texture, color, and sedimentary structures (Edgar et al., 2014). Each facies represents a distinct sedimentary process or environment. While facies were initially identified using Mastcam images, additional details such as grain size and stratification were revealed by MAHLI and ChemCam RMI images. Five of the seven facies were investigated by ChemCam (Fig. 1, Fig. 2, Fig. 4; Table 1), and we

RMI results

We measured grain sizes in 27 targets at the Shaler outcrop and applied the methodology of Yingst et al., 2008, Yingst et al., 2013 to determine limitations on grain resolution. For all targets, the majority of the visible surface is composed of grains that are unresolvable in the RMI images (smaller than coarse sand; Fig. 3). Measurable grain sizes range from coarse sand (the smallest resolvable grain size in RMI) to pebble.

All of the Facies 3 targets had grains that were unresolvable over

Qualitative results (PCA and ICA)

In general, within each facies there is significant heterogeneity from point to point, as shown on a PCA scores plot in Fig. 5. For ease of comparison between the different facies, all ICA and PCA plots are shown as both scatterplots and simplified outlines of the points for each facies. The cloud of Shaler points spans a significant portion of the full range of spectral diversity observed by the Curiosity rover through sol 360. There is considerable overlap between the different Shaler facies,

Average compositions

Table 2 lists the average ChemCam composition for each of the Shaler facies, as well as the major stratigraphic units at Yellowknife Bay (YKB): the Sheepbed member, Gillespie Lake member, and the Point Lake, Rocknest, and Bathurst outcrops. The “Snake” – a clastic dike that cuts the Sheepbed and Gillespie members (Grotzinger et al., 2013) – is also listed. For these average unit compositions, spectra with low signal to noise and those that appear to have sampled diagenetic features (e.g. raised

Conclusion

ChemCam data from 28 targets at Shaler have allowed a detailed chemical and textural investigation of the well-exposed interbedded sedimentary facies. Facies 1 and 2 were not analyzed by ChemCam, but the remaining facies all have ChemCam LIBS and RMI data from multiple targets.

Grain size analyses were used to describe the grain size distribution in each target. This was instrumental in defining the sedimentary facies and understanding of the depositional history at the Shaler outcrop. For each

Acknowledgments

This work was supported by the Mars Science Laboratory project. The French contribution to ChemCam on MSL is supported by the Centre National d’Etudes Spatiales (CNES). Anderson acknowledges support from the Shoemaker Postdoctoral Fellowship. Gupta, Bridges, and Schwenzer acknowledge the support of the UK Space Agency. Contributions from Blaney have been conducted at the Jet Propulsion Laboratory, California Institute of Technology under a contract with the National Aeronautics and Space

References (49)

S.M. Clegg et al.
Multivariate analysis of remote laser-induced breakdown spectroscopy spectra using partial least squares, principal component analysis, and related techniques
Spectrochim. Acta, Part B: At. Spectrosc.
(2009)
S. Le Mouélic et al.
The ChemCam Remote Micro-Imager at Gale crater: Review of the first year on Mars
Icarus
(2015)
N. Melikechi
Correcting for variable laser-target distances of laser-induced breakdown spectroscopy measurements with ChemCam using emission lines of martian dust spectra
Spectrochim. Acta, Part B: At. Spectrosc.
(2014)
H.W. Nesbitt et al.
Major and trace element geochemistry and genesis of supracrustal rocks of the North Spirit Lake Greenstone belt, NW Ontario, Canada
Precambrian Res.
(2009)
B. Sallé
Laser-induced breakdown spectroscopy for Mars surface analysis: Capabilities at stand-off distances and detection of chlorine and sulfur elements
Spectrochim. Acta, Part B: At. Spectrosc.
(2004)
S.P. Schwenzer
Gale crater: Formation and post-impact hydrous environments
Planet. Space Sci.
(2012)
P. Sobron et al.
Extraction of compositional and hydration information of sulfates from laser-induced plasma spectra recorded under Mars atmospheric conditions—Implications for ChemCam investigations on Curiosity rover
Spectrochim. Acta, Part B: At. Spectrosc.
(2012)
R.C. Wiens
Pre-flight calibration and initial data processing for the ChemCam laser-induced breakdown spectroscopy instrument on the Mars Science Laboratory rover
Spectrochim. Acta, Part B: At. Spectrosc.
(2013)
H. Abdi
Partial Least Square Regression (PLS Regression)
(2003)
R. Anderson et al.
Geologic mapping and characterization of Gale crater and implications for its potential as a Mars Science Laboratory landing site
Mars J.
(2010)

Blaney, D. et al., 2014. Chemical and textural variability among rocks observed at Rocknest, Gale crater. J. Geophys....

J.C. Bridges et al.

The SNC meteorites: Basaltic igneous processes on Mars

J. Geol. Soc.

(2006)

H.G. Changela et al.

Alteration assemblages in the nakhlites: Variation with depth on Mars

Meteorit. Planet. Sci.

(2010)

Clegg, S.M. et al., 2014. Expansion of the ChemCam calibration database. Lunar Planet. Sci. 45, p....

P. Comon

Independent component analysis

High.-Order Stat.

(1992)

K. Drüppel et al.

Fire bombing of the Tell Halaf Museum in Berlin during World War II – Reconstruction of the succession of events based on mineralogical investigations

Eur. J. Mineral.

(2009)

L. Dudragne et al.

Time-resolved laser-induced breakdown spectroscopy: Application for qualitative and quantitative detection of fluorine, chlorine, sulfur, and carbon in air

Appl. Spectrosc.

(1998)

Dyar, M.D., Bridges, J.C., Wiens, R.C., 2013. Mineralogy at Bradbury landing and Yellowknife Bay, Gale crater, Mars as...

Edgar, L.A., et al., A fluvial sandbody on Mars: Reconstruction of the Shaler outcrop, Gale crater, Mars,...

K.S. Edgett

Curiosity’s Mars Hand Lens Imager (MAHLI) investigation

Space Sci. Rev.

(2012)

Fedo, C.M., Friday, M.E., McGlynn, I.O., McSween, H.Y., 2012. Resolving basaltic sediment characteristics from 2D...

Forni, O. et al., 2013. Chemical variability and trends in ChemCam Mars observations in the first 90 sols using...

A.A. Fraeman

A hematite-bearing layer in Gale crater, Mars: Mapping and implications for past aqueous conditions

Geology

(2013)

Friday, M.E., Fedo, C.M., McGlynn, I.O., McSween, H.Y., 2013. The accuracy of 2D assessment of sediment textures, and...

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ChemCam results from the Shaler outcrop in Gale crater, Mars

Highlights

Abstract

Introduction

Section snippets

Methods and data

Shaler facies

RMI results

Qualitative results (PCA and ICA)

Average compositions

Conclusion

Acknowledgments

Spectrochim. Acta, Part B: At. Spectrosc.

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Spectrochim. Acta, Part B: At. Spectrosc.

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Planet. Space Sci.

Spectrochim. Acta, Part B: At. Spectrosc.

Spectrochim. Acta, Part B: At. Spectrosc.

Partial Least Square Regression (PLS Regression)

Geologic mapping and characterization of Gale crater and implications for its potential as a Mars Science Laboratory landing site

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