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Martian Brines: Clues from Sulfur and Chlorine in Salts from Some Martian Meteorites and MER Samples
| Content Provider | Semantic Scholar |
|---|---|
| Author | Rao, Mallikharjuna Mckay, David S. Wentworth, Susan J. Garrison, Daniel H. |
| Copyright Year | 2006 |
| Abstract | Introduction: For studying the aqueous alteration records in rocks and soils on Mars, halogens and sulfur seem to be better suited [1]. The coupling and de-coupling of these mobile elements such as S and Cl in salt-bearing mineral assemblages in Martian meteorites and MER samples are complex partly due to leaching and deposition of sulfates and chlorides by brine solutions on Mars. While reviewing the extensive Martian meteorite data, Treiman [2] noted that the differences between the alteration materials in nakhlites and shergottites are great enough to suggest the occurrence of two different altering fluids on Mars. Here, we explore selected nakhlites, shergottites and Meridiani samples to decipher the nature of these brines by studying the distribution of S and Cl abundances in salts produced from fluids that interacted with the regolith materials on Mars. Results and Discussion: NAKHLITES: We analyzed several veins in Nakhla olivines bearing idding-site and carbonates as fracture-filling materials by EMPA and SEM/EDS techniques. Typical results are : Iddingsite [Cl:1.43%(ave), range 0.75-3.06%; SO 3 : 0.18% (ave), range 0-0.46%] and Carbonates (Fe-carb, Fe-Mn-carb, Fe-Mg-carb) [Cl: 1.5% (ave), range 0.51-2.23%; SO 3 : 0.7% (ave), range 0.1-0.26%]. The errors in Cl are small whereas the errors in SO 3 values are relatively large (2σ). Gooding et al. [3] used a different approach to study S and Cl abundances in Nakhla salts. They pyrolyzed the interior Nakhla sample (,369) and analyzed the evolved Cl (Cl & HCl) and S (oxidized SO 2 and reduced S 2 & H 2 S) components using quadrapole mass-spectrometric methods. The total Cl released amounted to 0.4-0.5% in this sample, whereas the total S varied between 0.05-0.08%. During pyrolysis of ,369, they noticed a one-to-one correspondence between the release of Cl and Na in the temperature interval 850-1050 o C (NaCl decomposition), followed by monotonic relase of Cl at >1300 o C probably due to the decomposition of refrac-tory Cl-beraing phases such as Cl-apatite or merrilite. In iddingsite and carbonate bearing veins in Nak-hla, sulfur seems to be subordinate to the dominant chlorine abundance. Because iddingsite does not contain major concentrations of S, its formation probably did not occur by the oxidation of indigenous FeS. Instead, it appears that iddingsite is a silicate alteration product formed through the action of fluids enriched in halides [4,5]. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.lpi.usra.edu/meetings/lpsc2006/pdf/1969.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
