ALBERT

Description: Diagenetic silica enrichment in fracture-associated halos that cross-cut lacustrine and unconformably overlying aeolian sedimentary bedrock are observed on the lower north slope of Aeolis Mons in Gale crater, Mars. The diagenetic silica enrichment is co-located with detrital silica enrichment observed in the lacustrine bedrock, yet extends into a considerably younger, unconformably draping aeolian sandstone, implying that diagenetic silica enrichment post-dates the detrital silica enrichment. A causal connection between the detrital and diagenetic silica enrichment implies that water was present in the subsurface of Gale crater long after deposition of the lacustrine sediments, and that it mobilized detrital amorphous silica and precipitated it along fractures in the overlying bedrock. Although absolute timing is uncertain, the observed diagenesis likely represents some of the most recent groundwater activity in Gale crater, and suggests that the timescale of potential habitability extended considerably beyond the time that the lacustrine sediments of Aeolis Mons were deposited.

Description: Data gathered with the Dynamic Albedo of Neutrons (DAN) instrument onboard Curiosity rover were analyzed for variations in subsurface neutron flux and tested for possible correlation with local geological context. A special DAN observation campaign was executed in which 18 adjacent DAN active measurements were acquired every 0.75-1.0 m to search for variations of subsurface hydrogen content along a 15 m traverse across geologic contacts between the Sheepbed and Gillespie Lake members of the Yellowknife Bay formation. It was found that several subunits in Sheepbed and Gillespie Lake could be characterized with different depth distributions of water equivalent hydrogen (WEH) and different chlorine equivalent abundance responsible for the distribution of neutron absorption elements. The variations of average WEH at the top 60 cm of the subsurface are estimated at up to 2-3%. Chlorine equivalent neutron absorption abundances ranged within 0.8-1.5%. The largest difference in WEH and Chlorine equivalent neutron absorption distribution is found between Sheepbed and Gillespie Lake.

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 Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Sumner, D Y -- Kah, L C -- Stack, K -- Gupta, S -- Edgar, L -- Rubin, D -- Lewis, K -- Schieber, J -- Mangold, N -- Milliken, R -- Conrad, P G -- DesMarais, D -- Farmer, J -- Siebach, K -- Calef, F 3rd -- Hurowitz, J -- McLennan, S M -- Ming, D -- Vaniman, D -- Crisp, J -- Vasavada, A -- Edgett, K S -- Malin, M -- Blake, D -- Gellert, R -- Mahaffy, P -- Wiens, R C -- Maurice, S -- Grant, J A -- Wilson, S -- Anderson, R C -- Beegle, L -- Arvidson, R -- Hallet, B -- Sletten, R S -- Rice, M -- Bell, J 3rd -- Griffes, J -- Ehlmann, B -- Anderson, R B -- Bristow, T F -- Dietrich, W E -- Dromart, G -- Eigenbrode, J -- Fraeman, A -- Hardgrove, C -- Herkenhoff, K -- Jandura, L -- Kocurek, G -- Lee, S -- Leshin, L A -- Leveille, R -- Limonadi, D -- Maki, J -- McCloskey, S -- Meyer, M -- Minitti, M -- Newsom, H -- Oehler, D -- Okon, A -- Palucis, M -- Parker, T -- Rowland, S -- Schmidt, M -- Squyres, S -- Steele, A -- Stolper, E -- Summons, R -- Treiman, A -- Williams, R -- Yingst, A -- MSL Science Team -- New York, N.Y. -- Science. 2014 Jan 24;343(6169):1242777. doi: 10.1126/science.1242777. Epub 2013 Dec 9.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24324272" target="_blank"〉PubMed〈/a〉

Description: The DAN instrument onboard the MSL Curiosity rover acquired a series of measurements as part of an observational campaign of the Kimberley area in Gale crater. These observations were planned to assess the variability of bulk hydrogen and neutron-absorbing elements, characterized as chlorine-equivalent concentration, in the geologic members of the Kimberley formation and in surface materials exposed throughout the area. During the traverse of the Kimberley area, Curiosity drove primarily over the "Smooth Hummocky" unit, a unit composed primarily of sand and loose rocks, with occasional stops at bedrock of the Kimberley formation. During the Kimberley campaign, DAN detected ranges of water equivalent hydrogen (WEH) and chlorine equivalent concentrations of 1.5-2.5 wt% and 0.6-2 wt%, respectively. Results show that as the traverse progressed, DAN observed an overall decrease in both WEH and chlorine equivalent concentration measured over the sand and loose rocks of the Smooth Hummocky unit. DAN measurements of WEH and chlorine equivalent concentrations in the well-exposed sedimentary bedrock of the Kimberley formation show fluctuations with stratigraphic position. The Kimberley campaign also provided an opportunity to compare measurements from DAN with those from the SAM and the APXS instruments. DAN measurements obtained near the Windjana drill location show a WEH concentration ~1.5 wt%, consistent with the concentration of low-temperature absorbed water measured by SAM for the Windjana drill sample. A comparison between DAN chlorine equivalent concentrations measured throughout the Kimberley area and APXS observations of corresponding local surface targets and drill fines shows general agreement between the two instruments.

Description: The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Grotzinger, J P -- Gupta, S -- Malin, M C -- Rubin, D M -- Schieber, J -- Siebach, K -- Sumner, D Y -- Stack, K M -- Vasavada, A R -- Arvidson, R E -- Calef, F 3rd -- Edgar, L -- Fischer, W F -- Grant, J A -- Griffes, J -- Kah, L C -- Lamb, M P -- Lewis, K W -- Mangold, N -- Minitti, M E -- Palucis, M -- Rice, M -- Williams, R M E -- Yingst, R A -- Blake, D -- Blaney, D -- Conrad, P -- Crisp, J -- Dietrich, W E -- Dromart, G -- Edgett, K S -- Ewing, R C -- Gellert, R -- Hurowitz, J A -- Kocurek, G -- Mahaffy, P -- McBride, M J -- McLennan, S M -- Mischna, M -- Ming, D -- Milliken, R -- Newsom, H -- Oehler, D -- Parker, T J -- Vaniman, D -- Wiens, R C -- Wilson, S A -- New York, N.Y. -- Science. 2015 Oct 9;350(6257):aac7575. doi: 10.1126/science.aac7575.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Geologic and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. ; Department of Earth Science and Engineering, Imperial College London, London SW7 2AZ, UK. ; Malin Space Science Systems, Post Office Box 910148, San Diego, CA 92121, USA. ; Department of Earth and Planetary Sciences, University of California-Santa Cruz, Santa Cruz, CA 95064, USA. ; Department of Geological Sciences, Indiana University, Bloomington, IN 47405, USA. ; Department of Earth and Planetary Sciences, University of California-Davis, Davis, CA 95616, USA. ; Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA. ; Department of Earth and Planetary Sciences, Washington University in St. Louis, St. Louis, MO 63130, USA. ; Astrogeology Science Center, U.S. Geological Survey, Flagstaff, AZ 86001, USA. ; Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. ; Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, USA. ; Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD 21218, USA. ; Laboratoire Planetologie et Geodynamique de Nantes-Le Centre National de la Recherche, Unite Mixte de Recherche 6112 and Universite de Nantes, 44322 Nantes, France. ; Planetary Science Institute, Tucson, AZ 85719, USA. ; Department of Geology, Western Washington University, Bellingham, WA 98225, USA. ; Department of Space Sciences, NASA Ames Research Center, Moffett Field, CA 94035, USA. ; NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. ; Department of Earth and Planetary Science, University of California-Berkeley, Berkeley, CA 94720, USA. ; Laboratoire de Geologie de Lyon, Universite de Lyon, 69364 Lyon, France. ; Department of Geology and Geophysics, Texas A&M University, College Station, TX 77843, USA. ; Department of Physics, University of Guelph, Guelph, Ontario N1G 2W1, Canada. ; Department of Geosciences, Stony Brook University, Stony Brook, NY 11794-2100, USA. ; Department of Geological Sciences, University of Texas at Austin, Austin, TX 78712, USA. ; Astromaterials Research and Exploration Science Division, NASA Johnson Space Center, Houston, TX 77058, USA. ; Department of Geological Sciences, Brown University, Providence, RI 02912, USA. ; Institute of Meteoritics, University of New Mexico, Albuquerque, NM 87131 USA. ; LZ Technology, NASA Johnson Space Center, Houston, TX 77058, USA. ; Space Remote Sensing, Los Alamos National Laboratory, Los Alamos, NM 87544, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26450214" target="_blank"〉PubMed〈/a〉

Description: The Yellowknife Bay formation represents a ~5 m thick stratigraphic section of lithified fluvial and lacustrine sediments analyzed by the Curiosity rover in Gale crater, Mars [ Grotzinger et al ., 2014 ]. Previous works have mainly focused on the mudstones that were drilled by the rover at two locations. The present study focuses on the sedimentary rocks stratigraphically above the mudstones by studying their chemical variations in parallel with rock textures. Results show that differences in composition correlate with textures and both manifest subtle but significant variations through the stratigraphic column. Though the chemistry of the sediments does not vary much in the lower part of the stratigraphy, the variations in alkali elements indicate variations in the source material and/or physical sorting. as shown by the identification of alkali feldspars. The sandstones contain similar relative proportions of hydrogen to the mudstones below, suggesting the presence of hydrous minerals that may have contributed to their cementation. Slight variations in magnesium correlate with changes in textures suggesting that diagenesis, through cementation and dissolution modified the initial rock composition and texture simultaneously. The upper part of the stratigraphy (~1m thick) displays rocks with different compositions suggesting a strong change in the depositional system. The presence of float rocks with similar compositions found along the rover traverse suggests some of these outcrops extend further away in the nearby hummocky plains.

Description: Reflectance spectroscopy is a rapid and non-destructive method that can be used to detect organic compounds in geologic samples over a wide range of spatial scales that includes outcrops, hand samples, drill cores, and planetary surfaces. In order to assess the viability of this technique for quantification of organics and aliphatic compounds in particular, the present study examines how clay mineralogy, water content, and albedo influence the strength of organic absorptions in near-infrared (NIR) reflectance spectra. The effects of clay structure and water content are evaluated using kaolinite, smectite (montmorillonite), and a mixed-layer illite-smectite as starting materials. Absorption strengths for C–H absorptions are compared to known total organic carbon (TOC) values using both reflectance spectra and single scattering albedo (SSA) spectra derived from a Hapke radiative transfer model. A linear relationship was observed between band depth and TOC for each sample suite, but strong albedo variation led to non-unique trends when band depths were calculated from reflectance spectra. These effects were minimized by conversion to SSA, for which band depth-TOC trends were similar for all mixture suites regardless of albedo or hydration level, indicating that this approach may be more broadly applicable for clay and organic-bearing samples. Extrapolation of band depth-TOC trends for the synthetic mixtures suggested a very conservative lower limit of detection of 〈1 wt.% TOC, but preliminary results for natural organic-bearing shales indicated that detection limits may be an order of magnitude lower.