ALBERT

Description: Ventifacts, rocks abraded by wind-borne particles, are found in Gale Crater, Mars. In the eastward drive from “Bradbury Landing” to “Rocknest,” they account for about half of the float and outcrop seen by Curiosity's cameras. Many are faceted and exhibit abrasion textures found at a range of scales, from sub-millimeter lineations to centimeter-scale facets, scallops, flutes, and grooves. The drive path geometry in the first 100 sols of the mission emphasized the identification of abrasion facets and textures formed by westerly flow. This upwind direction is inconsistent with predictions based on models and the orientation of regional dunes, suggesting that these ventifact features formed from very rare high speed winds. The absence of active sand and evidence for deflation in the area indicates that most of the ventifacts are fossil features experiencing little abrasion today.

Description: Nature Geoscience 8, 605 (2015). doi:10.1038/ngeo2474 Authors: V. Sautter, M. J. Toplis, R. C. Wiens, A. Cousin, C. Fabre, O. Gasnault, S. Maurice, O. Forni, J. Lasue, A. Ollila, J. C. Bridges, N. Mangold, S. Le Mouélic, M. Fisk, P.-Y. Meslin, P. Beck, P. Pinet, L. Le Deit, W. Rapin, E. M. Stolper, H. Newsom, D. Dyar, N. Lanza, D. Vaniman, S. Clegg & J. J. Wray Understanding of the geologic evolution of Mars has been greatly improved by recent orbital, in situ and meteorite data, but insights into the earliest period of Martian magmatism (4.1 to 3.7 billion years ago) remain scarce. The landing site of NASA’s Curiosity rover, Gale crater, which formed 3.61 billion years ago within older terrain, provides a window into this earliest igneous history. Along its traverse, Curiosity has discovered light-toned rocks that contrast with basaltic samples found in younger regions. Here we present geochemical data and images of 22 specimens analysed by Curiosity that demonstrate that these light-toned materials are feldspar-rich magmatic rocks. The rocks belong to two distinct geochemical types: alkaline compositions containing up to 67 wt% SiO2 and 14 wt% total alkalis (Na2O + K2O) with fine-grained to porphyritic textures on the one hand, and coarser-grained textures consistent with quartz diorite and granodiorite on the other hand. Our analysis reveals unexpected magmatic diversity and the widespread presence of silica- and feldspar-rich materials in the vicinity of the landing site at Gale crater. Combined with the identification of feldspar-rich rocks elsewhere and the low average density of the crust in the Martian southern hemisphere, we conclude that silica-rich magmatic rocks may constitute a significant fraction of ancient Martian crust and may be analogous to the earliest continental crust on Earth.

Description: A suite of eight rocks analyzed by the Curiosity Rover while it was stopped at the Rocknest sand ripple show the greatest chemical divergence of any potentially sedimentary rocks analyzed in the early part of the mission. Relative to average martian soil and to the stratigraphically lower units encountered as part of the Yellowknife Bay formation, these rocks are significantly depleted in MgO, with a mean of 1.3 wt %, and high in Fe, averaging over 20 wt % FeO T . with values between 15 - 26 wt% FeO T . The variable iron and low magnesium, and rock texture make it unlikely that these are igneous rocks. Rock surface textures range from rough to smooth, can be pitted or grooved, and show various degrees of wind erosion. Some rocks display poorly defined layering while others seem to show possible fractures. Narrow vertical voids are present in Rocknest-3, one of the rocks showing the strongest layering. Rocks in the vicinity of Rocknest may have undergone some diagenesis similar to other rocks in the Yellowknife Bay Formation as indicated by the presence of soluble calcium phases. The most reasonable scenario is that fine-grained sediments, potentially a mixture of feldspar-rich rocks from Bradbury Rise and normal martian soil, was lithified together by an iron-rich cement.

Description: The Curiosity rover has analyzed abundant light-toned fracture-fill material within the Yellowknife Bay sedimentary deposits. The ChemCam instrument, coupled with Mastcam and ChemCam/Remote Micro Imager images, was able to demonstrate that these fracture fills consist of calcium sulfate veins, many of which appear to be hydrated at a level expected for gypsum and bassanite. Anhydrite is locally present, and is found in a location characterized by a nodular texture. An intricate assemblage of veins crosses the sediments, which were likely formed by precipitation from fluids circulating through fractures. The presence of veins throughout the entire ~5 m thick Yellowknife Bay sediments suggests that this process occurred well after sedimentation and cementation/lithification of those sediments. The sulfur-rich fluids may have originated in previously precipitated sulfate-rich layers, either before the deposition of the Sheepbed mudstones, or from unrelated units such as the sulfates at the base of Mount Sharp. The occurrence of these veins after the episodes of deposition of fluvial sediments at the surface suggests persistent aqueous activity in relatively non-acidic conditions.

Description: Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Chris R -- Mahaffy, Paul R -- Flesch, Gregory J -- Niles, Paul B -- Jones, John H -- Leshin, Laurie A -- Atreya, Sushil K -- Stern, Jennifer C -- Christensen, Lance E -- Owen, Tobias -- Franz, Heather -- Pepin, Robert O -- Steele, Andrew -- MSL Science Team -- Achilles, Cherie -- Agard, Christophe -- Alves Verdasca, Jose Alexandre -- Anderson, Robert -- Anderson, Ryan -- Archer, Doug -- Armiens-Aparicio, Carlos -- Arvidson, Ray -- Atlaskin, Evgeny -- Aubrey, Andrew -- Baker, Burt -- Baker, Michael -- Balic-Zunic, Tonci -- Baratoux, David -- Baroukh, Julien -- Barraclough, Bruce -- Bean, Keri -- Beegle, Luther -- Behar, Alberto -- Bell, James -- Bender, Steve -- Benna, Mehdi -- Bentz, Jennifer -- Berger, Gilles -- Berger, Jeff -- Berman, Daniel -- Bish, David -- Blake, David F -- Blanco Avalos, Juan J -- Blaney, Diana -- Blank, Jen -- Blau, Hannah -- Bleacher, Lora -- Boehm, Eckart -- Botta, Oliver -- Bottcher, Stephan -- Boucher, Thomas -- Bower, Hannah -- Boyd, Nick -- Boynton, Bill -- Breves, Elly -- Bridges, John -- Bridges, Nathan -- Brinckerhoff, William -- Brinza, David -- Bristow, Thomas -- Brunet, Claude -- Brunner, Anna -- Brunner, Will -- Buch, Arnaud -- Bullock, Mark -- Burmeister, Sonke -- Cabane, Michel -- Calef, Fred -- Cameron, James -- Campbell, John -- Cantor, Bruce -- Caplinger, Michael -- Caride Rodriguez, Javier -- Carmosino, Marco -- Carrasco Blazquez, Isaias -- Charpentier, Antoine -- Chipera, Steve -- Choi, David -- Clark, Benton -- Clegg, Sam -- Cleghorn, Timothy -- Cloutis, Ed -- Cody, George -- Coll, Patrice -- Conrad, Pamela -- Coscia, David -- Cousin, Agnes -- Cremers, David -- Crisp, Joy -- Cros, Alain -- Cucinotta, Frank -- d'Uston, Claude -- Davis, Scott -- Day, Mackenzie -- de la Torre Juarez, Manuel -- DeFlores, Lauren -- DeLapp, Dorothea -- DeMarines, Julia -- DesMarais, David -- Dietrich, William -- Dingler, Robert -- Donny, Christophe -- Downs, Bob -- Drake, Darrell -- Dromart, Gilles -- Dupont, Audrey -- Duston, Brian -- Dworkin, Jason -- Dyar, M Darby -- Edgar, Lauren -- Edgett, Kenneth -- Edwards, Christopher -- Edwards, Laurence -- Ehlmann, Bethany -- Ehresmann, Bent -- Eigenbrode, Jen -- Elliott, Beverley -- Elliott, Harvey -- Ewing, Ryan -- Fabre, Cecile -- Fairen, Alberto -- Farley, Ken -- Farmer, Jack -- Fassett, Caleb -- Favot, Laurent -- Fay, Donald -- Fedosov, Fedor -- Feldman, Jason -- Feldman, Sabrina -- Fisk, Marty -- Fitzgibbon, Mike -- Floyd, Melissa -- Fluckiger, Lorenzo -- Forni, Olivier -- Fraeman, Abby -- Francis, Raymond -- Francois, Pascaline -- Freissinet, Caroline -- French, Katherine Louise -- Frydenvang, Jens -- Gaboriaud, Alain -- Gailhanou, Marc -- Garvin, James -- Gasnault, Olivier -- Geffroy, Claude -- Gellert, Ralf -- Genzer, Maria -- Glavin, Daniel -- Godber, Austin -- Goesmann, Fred -- Goetz, Walter -- Golovin, Dmitry -- Gomez Gomez, Felipe -- Gomez-Elvira, Javier -- Gondet, Brigitte -- Gordon, Suzanne -- Gorevan, Stephen -- Grant, John -- Griffes, Jennifer -- Grinspoon, David -- Grotzinger, John -- Guillemot, Philippe -- Guo, Jingnan -- Gupta, Sanjeev -- Guzewich, Scott -- Haberle, Robert -- Halleaux, Douglas -- Hallet, Bernard -- Hamilton, Vicky -- Hardgrove, Craig -- Harker, David -- Harpold, Daniel -- Harri, Ari-Matti -- Harshman, Karl -- Hassler, Donald -- Haukka, Harri -- Hayes, Alex -- Herkenhoff, Ken -- Herrera, Paul -- Hettrich, Sebastian -- Heydari, Ezat -- Hipkin, Victoria -- Hoehler, Tori -- Hollingsworth, Jeff -- Hudgins, Judy -- Huntress, Wesley -- Hurowitz, Joel -- Hviid, Stubbe -- Iagnemma, Karl -- Indyk, Steve -- Israel, Guy -- Jackson, Ryan -- Jacob, Samantha -- Jakosky, Bruce -- Jensen, Elsa -- Jensen, Jaqueline Klovgaard -- Johnson, Jeffrey -- Johnson, Micah -- Johnstone, Steve -- Jones, Andrea -- Joseph, Jonathan -- Jun, Insoo -- Kah, Linda -- Kahanpaa, Henrik -- Kahre, Melinda -- Karpushkina, Natalya -- Kasprzak, Wayne -- Kauhanen, Janne -- Keely, Leslie -- Kemppinen, Osku -- Keymeulen, Didier -- Kim, Myung-Hee -- Kinch, Kjartan -- King, Penny -- Kirkland, Laurel -- Kocurek, Gary -- Koefoed, Asmus -- Kohler, Jan -- Kortmann, Onno -- Kozyrev, Alexander -- Krezoski, Jill -- Krysak, Daniel -- Kuzmin, Ruslan -- Lacour, Jean Luc -- Lafaille, Vivian -- Langevin, Yves -- Lanza, Nina -- Lasue, Jeremie -- Le Mouelic, Stephane -- Lee, Ella Mae -- Lee, Qiu-Mei -- Lees, David -- Lefavor, Matthew -- Lemmon, Mark -- Lepinette Malvitte, Alain -- Leveille, Richard -- Lewin-Carpintier, Eric -- Lewis, Kevin -- Li, Shuai -- Lipkaman, Leslie -- Little, Cynthia -- Litvak, Maxim -- Lorigny, Eric -- Lugmair, Guenter -- Lundberg, Angela -- Lyness, Eric -- Madsen, Morten -- Maki, Justin -- Malakhov, Alexey -- Malespin, Charles -- Malin, Michael -- Mangold, Nicolas -- Manhes, Gerard -- Manning, Heidi -- Marchand, Genevieve -- Marin Jimenez, Mercedes -- Martin Garcia, Cesar -- Martin, Dave -- Martin, Mildred -- Martinez-Frias, Jesus -- Martin-Soler, Javier -- Martin-Torres, F Javier -- Mauchien, Patrick -- Maurice, Sylvestre -- McAdam, Amy -- McCartney, Elaina -- McConnochie, Timothy -- McCullough, Emily -- McEwan, Ian -- McKay, Christopher -- McLennan, Scott -- McNair, Sean -- Melikechi, Noureddine -- Meslin, Pierre-Yves -- Meyer, Michael -- Mezzacappa, Alissa -- Miller, Hayden -- Miller, Kristen -- Milliken, Ralph -- Ming, Douglas -- Minitti, Michelle -- Mischna, Michael -- Mitrofanov, Igor -- Moersch, Jeff -- Mokrousov, Maxim -- Molina Jurado, Antonio -- Moores, John -- Mora-Sotomayor, Luis -- Morookian, John Michael -- Morris, Richard -- Morrison, Shaunna -- Mueller-Mellin, Reinhold -- Muller, Jan-Peter -- Munoz Caro, Guillermo -- Nachon, Marion -- Navarro Lopez, Sara -- Navarro-Gonzalez, Rafael -- Nealson, Kenneth -- Nefian, Ara -- Nelson, Tony -- Newcombe, Megan -- Newman, Claire -- Newsom, Horton -- Nikiforov, Sergey -- Nixon, Brian -- Noe Dobrea, Eldar -- Nolan, Thomas -- Oehler, Dorothy -- Ollila, Ann -- Olson, Timothy -- de Pablo Hernandez, Miguel Angel -- Paillet, Alexis -- Pallier, Etienne -- Palucis, Marisa -- Parker, Timothy -- Parot, Yann -- Patel, Kiran -- Paton, Mark -- Paulsen, Gale -- Pavlov, Alex -- Pavri, Betina -- Peinado-Gonzalez, Veronica -- Peret, Laurent -- Perez, Rene -- Perrett, Glynis -- Peterson, Joe -- Pilorget, Cedric -- Pinet, Patrick -- Pla-Garcia, Jorge -- Plante, Ianik -- Poitrasson, Franck -- Polkko, Jouni -- Popa, Radu -- Posiolova, Liliya -- Posner, Arik -- Pradler, Irina -- Prats, Benito -- Prokhorov, Vasily -- Purdy, Sharon Wilson -- Raaen, Eric -- Radziemski, Leon -- Rafkin, Scot -- Ramos, Miguel -- Rampe, Elizabeth -- Raulin, Francois -- Ravine, Michael -- Reitz, Gunther -- Renno, Nilton -- Rice, Melissa -- Richardson, Mark -- Robert, Francois -- Robertson, Kevin -- Rodriguez Manfredi, Jose Antonio -- Romeral-Planello, Julio J -- Rowland, Scott -- Rubin, David -- Saccoccio, Muriel -- Salamon, Andrew -- Sandoval, Jennifer -- Sanin, Anton -- Sans Fuentes, Sara Alejandra -- Saper, Lee -- Sarrazin, Philippe -- Sautter, Violaine -- Savijarvi, Hannu -- Schieber, Juergen -- Schmidt, Mariek -- Schmidt, Walter -- Scholes, Daniel -- Schoppers, Marcel -- Schroder, Susanne -- Schwenzer, Susanne -- Sebastian Martinez, Eduardo -- Sengstacken, Aaron -- Shterts, Ruslan -- Siebach, Kirsten -- Siili, Tero -- Simmonds, Jeff -- Sirven, Jean-Baptiste -- Slavney, Susie -- Sletten, Ronald -- Smith, Michael -- Sobron Sanchez, Pablo -- Spanovich, Nicole -- Spray, John -- Squyres, Steven -- Stack, Katie -- Stalport, Fabien -- Stein, Thomas -- Stewart, Noel -- Stipp, Susan Louise Svane -- Stoiber, Kevin -- Stolper, Ed -- Sucharski, Bob -- Sullivan, Rob -- Summons, Roger -- Sumner, Dawn -- Sun, Vivian -- Supulver, Kimberley -- Sutter, Brad -- Szopa, Cyril -- Tan, Florence -- Tate, Christopher -- Teinturier, Samuel -- ten Kate, Inge -- Thomas, Peter -- Thompson, Lucy -- Tokar, Robert -- Toplis, Mike -- Torres Redondo, Josefina -- Trainer, Melissa -- Treiman, Allan -- Tretyakov, Vladislav -- Urqui-O'Callaghan, Roser -- Van Beek, Jason -- Van Beek, Tessa -- VanBommel, Scott -- Vaniman, David -- Varenikov, Alexey -- Vasavada, Ashwin -- Vasconcelos, Paulo -- Vicenzi, Edward -- Vostrukhin, Andrey -- Voytek, Mary -- Wadhwa, Meenakshi -- Ward, Jennifer -- Weigle, Eddie -- Wellington, Danika -- Westall, Frances -- Wiens, Roger Craig -- Wilhelm, Mary Beth -- Williams, Amy -- Williams, Joshua -- Williams, Rebecca -- Williams, Richard B -- Wilson, Mike -- Wimmer-Schweingruber, Robert -- Wolff, Mike -- Wong, Mike -- Wray, James -- Wu, Megan -- Yana, Charles -- Yen, Albert -- Yingst, Aileen -- Zeitlin, Cary -- Zimdar, Robert -- Zorzano Mier, Maria-Paz -- New York, N.Y. -- Science. 2013 Jul 19;341(6143):260-3. doi: 10.1126/science.1237961.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23869013" target="_blank"〉PubMed〈/a〉

Description: The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Meslin, P-Y -- Gasnault, O -- Forni, O -- Schroder, S -- Cousin, A -- Berger, G -- Clegg, S M -- Lasue, J -- Maurice, S -- Sautter, V -- Le Mouelic, S -- Wiens, R C -- Fabre, C -- Goetz, W -- Bish, D -- Mangold, N -- Ehlmann, B -- Lanza, N -- Harri, A-M -- Anderson, R -- Rampe, E -- McConnochie, T H -- Pinet, P -- Blaney, D -- Leveille, R -- Archer, D -- Barraclough, B -- Bender, S -- Blake, D -- Blank, J G -- Bridges, N -- Clark, B C -- DeFlores, L -- Delapp, D -- Dromart, G -- Dyar, M D -- Fisk, M -- Gondet, B -- Grotzinger, J -- Herkenhoff, K -- Johnson, J -- Lacour, J-L -- Langevin, Y -- Leshin, L -- Lewin, E -- Madsen, M B -- Melikechi, N -- Mezzacappa, A -- Mischna, M A -- Moores, J E -- Newsom, H -- Ollila, A -- Perez, R -- Renno, N -- Sirven, J-B -- Tokar, R -- de la Torre, M -- d'Uston, L -- Vaniman, D -- Yingst, A -- MSL Science Team -- New York, N.Y. -- Science. 2013 Sep 27;341(6153):1238670. doi: 10.1126/science.1238670.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Universite de Toulouse, UPS-OMP, IRAP, 31028 Toulouse, France. pmeslin@irap.omp.eu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24072924" target="_blank"〉PubMed〈/a〉

Description: The Rocknest aeolian deposit is similar to aeolian features analyzed by the Mars Exploration Rovers (MERs) Spirit and Opportunity. The fraction of sand 〈150 micrometers in size contains ~55% crystalline material consistent with a basaltic heritage and ~45% x-ray amorphous material. The amorphous component of Rocknest is iron-rich and silicon-poor and is the host of the volatiles (water, oxygen, sulfur dioxide, carbon dioxide, and chlorine) detected by the Sample Analysis at Mars instrument and of the fine-grained nanophase oxide component first described from basaltic soils analyzed by MERs. The similarity between soils and aeolian materials analyzed at Gusev Crater, Meridiani Planum, and Gale Crater implies locally sourced, globally similar basaltic materials or globally and regionally sourced basaltic components deposited locally at all three locations.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Blake, D F -- Morris, R V -- Kocurek, G -- Morrison, S M -- Downs, R T -- Bish, D -- Ming, D W -- Edgett, K S -- Rubin, D -- Goetz, W -- Madsen, M B -- Sullivan, R -- Gellert, R -- Campbell, I -- Treiman, A H -- McLennan, S M -- Yen, A S -- Grotzinger, J -- Vaniman, D T -- Chipera, S J -- Achilles, C N -- Rampe, E B -- Sumner, D -- Meslin, P-Y -- Maurice, S -- Forni, O -- Gasnault, O -- Fisk, M -- Schmidt, M -- Mahaffy, P -- Leshin, L A -- Glavin, D -- Steele, A -- Freissinet, C -- Navarro-Gonzalez, R -- Yingst, R A -- Kah, L C -- Bridges, N -- Lewis, K W -- Bristow, T F -- Farmer, J D -- Crisp, J A -- Stolper, E M -- Des Marais, D J -- Sarrazin, P -- MSL Science Team -- New York, N.Y. -- Science. 2013 Sep 27;341(6153):1239505. doi: 10.1126/science.1239505.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Aeronautics and Space Administration Ames Research Center, Moffett Field, CA 94035, USA. david.blake@nasa.gov〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24072928" target="_blank"〉PubMed〈/a〉

Description: The Curiosity rover has analyzed various detrital sedimentary rocks at Gale crater, among which fluvial and lacustrine rocks are predominant [ Grotzinger et al. , 2014, 2015]. Conglomerates correspond both to the coarsest sediments analyzed and the least modified by chemical alteration, enabling us to link their chemistry to that of source rocks on the Gale crater rims. In this study, we report the results of 6 conglomerate targets analyzed by APXS and 40 analyzed by ChemCam. The bulk chemistry derived by both instruments suggests two distinct end-members for the conglomerate compositions. The first group (Darwin type) is typical of conglomerates analyzed before sol 540; it has a felsic alkali-rich composition, with a Na 2 O/K 2 O 〉 5. The second group (Kimberley type) is typical of conglomerates analyzed between sol 540 and 670 in the vicinity of the Kimberley waypoint; it has an alkali-rich potassic composition with Na 2 O/K 2 O 〈 2. The variety of chemistry and igneous textures (when identifiable) of individual clasts suggest that each conglomerate type is a mixture of multiple source rocks. Conglomerate compositions are in agreement with most of the felsic alkali-rich float rock compositions analyzed in the hummocky plains (as reported in Sautter et al., 2015 ). The average composition of conglomerates can be taken as a proxy of the average igneous crust composition at Gale crater. Differences between the composition of conglomerates and that of finer-grained detrital sediments analyzed by the rover suggest modifications by diagenetic processes (especially for Mg-enrichments in fine grained rocks), physical sorting and mixing with finer-grained material of different composition.

Description: The Mars Science Laboratory rover Curiosity encountered potassium-rich clastic sedimentary rocks at two sites in Gale Crater, the waypoints Cooperstown and Kimberley. These rocks include several distinct meters thick sedimentary outcrops ranging from fine sandstone to conglomerate, interpreted to record an ancient fluvial or fluvio-deltaic depositional system. From ChemCam Laser-Induced Breakdown Spectroscopy (LIBS) chemical analyses, this suite of sedimentary rocks has an overall mean K 2 O abundance that is more than 5 times higher than that of the average Martian crust. The combined analysis of ChemCam data with stratigraphic and geographic locations reveals that the mean K 2 O abundance increases upward through the stratigraphic section. Chemical analyses across each unit can be represented as mixtures of several distinct chemical components, i.e., mineral phases, including K-bearing minerals, mafic silicates, Fe-oxides, and Fe-hydroxide/oxyhydroxides. Possible K-bearing minerals include alkali feldspar (including anorthoclase and sanidine) and K-bearing phyllosilicate such as illite. Mixtures of different source rocks, including a potassium-rich rock located on the rim and walls of Gale Crater, are the likely origin of observed chemical variations within each unit. Physical sorting may have also played a role in the enrichment in K in the Kimberley formation. The occurrence of these potassic sedimentary rocks provides additional evidence for the chemical diversity of the crust exposed at Gale Crater.

Description: Reports of plumes or patches of methane in the martian atmosphere that vary over monthly time scales have defied explanation to date. From in situ measurements made over a 20-month period by the tunable laser spectrometer of the Sample Analysis at Mars instrument suite on Curiosity at Gale crater, we report detection of background levels of atmospheric methane of mean value 0.69 +/- 0.25 parts per billion by volume (ppbv) at the 95% confidence interval (CI). This abundance is lower than model estimates of ultraviolet degradation of accreted interplanetary dust particles or carbonaceous chondrite material. Additionally, in four sequential measurements spanning a 60-sol period (where 1 sol is a martian day), we observed elevated levels of methane of 7.2 +/- 2.1 ppbv (95% CI), implying that Mars is episodically producing methane from an additional unknown source.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Webster, Christopher R -- Mahaffy, Paul R -- Atreya, Sushil K -- Flesch, Gregory J -- Mischna, Michael A -- Meslin, Pierre-Yves -- Farley, Kenneth A -- Conrad, Pamela G -- Christensen, Lance E -- Pavlov, Alexander A -- Martin-Torres, Javier -- Zorzano, Maria-Paz -- McConnochie, Timothy H -- Owen, Tobias -- Eigenbrode, Jennifer L -- Glavin, Daniel P -- Steele, Andrew -- Malespin, Charles A -- Archer, P Douglas Jr -- Sutter, Brad -- Coll, Patrice -- Freissinet, Caroline -- McKay, Christopher P -- Moores, John E -- Schwenzer, Susanne P -- Bridges, John C -- Navarro-Gonzalez, Rafael -- Gellert, Ralf -- Lemmon, Mark T -- MSL Science Team -- New York, N.Y. -- Science. 2015 Jan 23;347(6220):415-7. doi: 10.1126/science.1261713. Epub 2014 Dec 16.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. chris.r.webster@jpl.nasa.gov. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; University of Michigan, Ann Arbor, MI 48109, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. ; Institut de Recherche en Astrophysique et Planetologie, UPS-OMP, CNRS, 31028 Toulouse, France. ; California Institute of Technology, Pasadena, CA 91125, USA. ; Instituto Andaluz de Ciencias de la Tierra [Consejo Superior de Investigaciones Cientificas (CSIC)-Universidad de Granada], Granada, Spain. Division of Space Technology, Lulea University of Technology, Kiruna, Sweden. ; Centro de Astrobiologia, Instituto Nacional de Tecnica Aeroespacial-CSIC, Madrid, Spain. ; Department of Astronomy, University of Maryland, College Park, MD 20742, USA. ; University of Hawaii, Honolulu, HI 96822, USA. ; Carnegie Institution of Washington, Washington, DC 20015, USA. ; Jacobs Technology, NASA Johnson Space Center, Houston, TX 77058, USA. ; Laboratoire Inter-Universitaires Des Systemes Atmospheriques (LISA), UMR CNRS 7583, Paris, France. ; NASA Ames Research Center, Mountain View, CA 94035, USA. ; York University, Toronto, Ontario M3J 1P3, Canada. ; The Open University, Milton Keynes MK7 6AA, UK. ; Space Research Centre, University of Leicester, Leicester LE1 7RH, UK. ; Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Mexico City 04510, Mexico. ; University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Texas A&M University, College Station, TX 77843, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25515120" target="_blank"〉PubMed〈/a〉