Organics Preservation in the Hyperarid Qaidam Basin, China: An Analog for Fluvio-lacustrine Deposits in Gale Crater, Mars S. E. Shaner1, A. J. Williams1, G. Zhuang2, 1Department of Geological Sciences, University of Florida, 2Department of Geology and Geophysics, Louisiana State University

Introduction Results Discussion

• Qaidam Basin is an analog for Gale Crater, Mars 0.6 • C26 detected in ZK1405 drill core samples using • Analog environments provide terrestrial materials that exhibit Martian 0.5 14-7 30-1 20-1 38-1 alkane/alkene method (C-19 addition only) (Figure properties 0.4 44-4 5-1 8-3 • Qaidam Basin clays can be tested to see how organic compounds may be 0.3 3), which in indicative of higher plants. 0.2 preserved and allude to how they would be on Mars sample 0.1 • The even-over-odd chain length preference in FAMEs • Organics indicate fossilized/previous life existing at site 0.0 C4 C5 C6 C7 C8 C9 C10 C11 C12:1 C12 C13 C14 C15 C16 C17 C18 C19 C20 C22 C23 C24 C25 C26 detected in ZK1405 drill core samples and LLH dried • A low-risk study for how effective similar methods to detect organic of permg of ng lipid Total std material would be in space flight Alkane/alkene stream bed samples indicates a modern microbial Figure 3: In the ZK1405 drill core samples by pyrolysis and addition of only C-19, straight-chained community (Figure 4). hydrocarbons produced through the seven samples include: C , C , C , C , C , C , C , C , C , C , C , Objectives 4 5 6 7 8 9 10 11 12 12:1 13

C14, C15, C16, C17, C18, C20, C21, C22, C23, C24, C25, and C26. • There is a lack of wax esters in these samples, which ALKANES/ALKENES

250.0 is typically expected of a hyperarid clay environment • To determine how successful flash pyrolysis and methylation by TMSH 14-7 30-1 20-1 38-1 are in detection of lipid biomarkers, alkanes, alkenes, and fatty acid methyl due to the charged mineral surfaces of clays. 200.0 esters 44-4 8-3 5-1 • Possibly more organic compounds in the samples • To compare the amount of biosignatures present in Eocene vs. last glacial 150.0 maximum rock samples than detected because we are limited by method; no 100.0 comparison within this study but can be compared Study Area 50.0 to other studies to determine how relatively

Figures 1 & 2: Location of Qaidam Basin in 0.0 successful this is.

Total ng of lipid per mg of sample of permg of ng lipid Total

C4 C5 C6 C7 C8 C9

C11 C12 C13 C14 C15 C16 C17 C18

intermontain North Tibetan Plateau, China. C10

C16:1 C18:1 iC15:0 Sampling sites for each set of samples noted by red FAME aC15:0 markers. ZK1405 samples (Eocene age) obtained Figure 4: In the ZK1405 drill core samples by pyrolysis and methylation, the FAMEs C4, C5, C6, C7, C8, C9, Conclusion C , C , C , C , C , and C were detected. at a drill site located at 38°38’N 93°00'E, and LLH 10 11 12 14 16 18 samples (last glacial maximum) from what LLH30 LLH35B LLH36 LLH38 LLH39A LLH46 16.0 The organic molecules present in these samples are geomorphologically appears to be a small dried 14.0 12.0 wash around 38°06′ N 94°40′ E. 10.0 biosignatures due to their presence in bacterial and 8.0 6.0 eukaryotic phospholipid bilayers of cell membranes. 4.0 2.0 of sample of 0.0 We conclude that an abundance of constituents that

FATTY ACID METHYL METHYL ESTERS ACID FATTY C4 C5 C6 C7 C8 C9 C10 C11 C12 C13 C14 C15 C16 C17 C18 C19 C20 C21 C22 C23 C24 C25 Analogous features: std

Total ng of lipid per mg permg of ng lipid Total make up life can be preserved under these hyperarid clay • Yardangs FAME • Dunes conditions and detected by this method of flash pyrolysis Figure 5: In the LLH dried stream bed samples, the FAMEs C8, C10, C14, C20, and C22 were detected. One • Fluvial structures sample (LLH 24A) produced no detectable FAMEs. and TMSH injection. These methods should be • Playas • Evaporites considered when constructing rover instrument = lacustrine evolution Methods to non-lacustrine. payloads in order to find more conclusive evidence of THERMOCHEMOLYSIS PREPARATION GAS CHROMATOGRAPHY-MASS organic matter preservation in Martian sediments. Halophilic archaea • Samples broken into 3-5 mm pieces using rock SPECTROMETRY This study provides ample reason for the SAM found by Xiao et al. hammer and ashed (500°C, 8 hrs) chisel (2016). • Ground with ashed mortar and pestle to instrument on the Curiosity rover to visit sites with clay homogenous powder • Residual surface organics removed from the dominated mineralogies in search of the lipid powder via solvent washing and sonication • Transferred to solvent-washed vials with solvent- biosignatures.

Sample Name Rock type Table 1: Description of LLH samples washed scoop in the hood for refrigerated storage taken from different places along Alkanes/alkenes: Addition of 1.5 uL C-19 standard Figure 6: Samples were loaded into an LLH 24A Light red, massive siltstone References dried wash. Altogether samples are Fatty acids: Addition of 1.5 uL C-19 standard + TMSH Agilent GC-MS coupled to a Frontier LLH 30 Brown, massive silty clay a mix of clays, siltstones, and (uL equivalent to milligram weight of sample). pyrolyzer. The oven program ramped For LLH samples, additionally naphthalene-18 (uL LLH 35B Greenish-grey, massive silty clay sandstones. from 50°C to 300°C at 20°C/min with a 10 equivalent to milligram weight of sample) minute hold. Samples analyzed for fatty [1] Ishida, Y, et al (1999) Journal of Analytical and Applied Pyrolysis 49:1-2, LLH 36 Light grey, massive clay acids were subject to the same pyrolyzer 267-276. [2] Milliken, R. E., et al (2009) Lunar and Planetary Science LLH 38 Light green, massive clay and oven programs as for alkanes. Conference 1479. [3] Wilhelm, M. B. et al (2017) Organic Geochemistry LLH 39A Brown, massive siltstone Molecules were identified using TMSH (tetramethylammonium hydroxide) allows methylation of fatty acids to fatty acid methyl ChemStation software. 103:97-104. [4] Williams, A. J., et al (2015) Lunar and Planetary Science LLH 46 Light green, massive siltstone-fine sandstone esters (FAMEs) to happen at a lower temperature and with a more direct reaction pathway. Here, R1 refers to the carboxyl group of a fatty acid and R2 refers to the new methyl group. Conference 1814. [5] Xiao, L., et al (2016) Earth-Science Reviews 164, 84-101.