45th Lunar and Planetary Science Conference (2014) 2712.pdf

MINERALOGY OF ACID SULFATE FUMAROLE VS. NEAR NEUTRAL SINTER DEPOSITS AT LASSEN VOLCANIC NATIONAL PARK: COMPARISON TO GUSEV CRATER, . L. J. McHenry1, T. L. Gerard1, G. L. Carson1 and G. L. Walters1, 1 UW Milwaukee Department of Geosciences, 3209 N. Maryland Ave., Milwaukee, WI 53211. [email protected]

Introduction: Hydrothermal environments have Water results: Thermal waters varied in been postulated for early Mars, based on abundant temperature from boiling to near ambient, and in pH evidence for water and [1,2], as well as from 1.88 (Boiling Springs Lake, 2012) to 8.09 direct detection of likely hydrothermal deposits at (Growler ). While acidic conditions Gusev Crater and elsewhere by orbital and rover dominate at Sulphur Works, Bumpass Hell, and platforms [3,4]. Such environments could have Boiling Springs Lake (high-T acid sulfate fumarole provided both a source of water and a source of heat areas), both acidic and more neutral conditions were for life, though their habitability depends on many observed at Devil’s Kitchen, and only neutral other factors [5,6]. One important factor is whether a conditions were observed at Drakesbad and Growler hydrothermal environment is more akin to acid-sulfate Hot Springs (Table 1). fumaroles (less habitable) or more neutral sinter- depositing hot springs (more habitable). Both have Table 1: Hydrolab water analysis results, 2013 been proposed to explain features of the Columbia Site T pH ORP SpCond Sal TDS °C mV uS/cm ppt g/l Hills [7,8]. Studies of modern terrestrial fumarole and Sulph ur Works hot spring environments and their deposits can help 84.0 2.07 216 7206 4.01 4.6 identify diagnostic mineralogical and geochemical Bumpass Hell signatures. 8 .0 3.03 212 716 0.37 0.5 In this abstract we report preliminary results for a 65.0 2.36 25 4334 2.37 0.5

geochemical and mineralogical study of modern 40.2 2.02 -228 8005 4.48 5.1 88.6 2.39 -223 4342 2.37 2.8 fumaroles and hot springs in the vicinity of Lassen Growler/Morgan in the southern Cascades of California. Lassen 93.5 8.09 - 258 10963 6.23 7 has both gas-dominated acid-sulfate fumaroles and 49.6 7.01 -229 9456 5.34 6.1 water-dominated near-neutral sinter depositing hot Devil's Kitchen

springs, both likely originating from the same 51.8 2.07 88 6636 3.68 4.2 80.9 2.5 -143 3235 1.75 2.1 hydrothermal system [9,10]. 85.7 5.92 -320 538 0.27 0.3 Drakesbad 52 .0 6.87 - 189 962 0.5 0.6 Boiling Spr ings Lake 46.4 2.24 226 4085 2.23 2.6 50.0 4.01 -214 860 0.45 0.6 77.0 3.44 -85 884 0.46 0.6 XRD results: -bearing minerals are present in all but one sample (SW-12-2), which represents Figure 1: Sulphur Works fumarole sample spot, 2012 and 2013. The altered substrate (Table 2). Samples from Sulphur 2012 deposit was more coarsely crystalline and dominated by Works, Bumpass Hell, and Devil’s Kitchen contain alunogen, a mineral that was scarce in the same deposit sampled in elemental sulfur, lining fumarole vents. Sulfate 2013. minerals dominate further out, and include Fe-sulfates Methods: We collected mineral, rock, and water (jarosite, voltaite, rhomboclase), Al-sulfates (alunite, samples at and near fumaroles and hot springs at alunogen), Ni/V sulfates, and mixed sulfates Lassen (Sulphur Works (Fig. 1), Bumpass Hell, (natroalunite). Coatings on rocks in the near-neutral Devil’s Kitchen, Boiling Springs Lake, Drakesbad, and Drakesbad Hot Spring yielded the only examples of Growler hot spring) in 2012 and 2013. We also gypsum and calcite. At Bumapass Hell the Fe-sulfides measured water temperature, pH, and other parameters pyrite and marcasite (and the negative ORP) indicate using a Hydrolab sonde (2013). Select mineral and reducing conditions. rock samples were hand ground without liquids or heat Some Sulphur Works, Bumpass Hell, and Devil’s and analyzed using a Bruker D8 Focus X-ray Kitchen samples yielded clay minerals. Kaolinite is a Diffractometer (XRD) for phase identification. Future typical alteration product formed by acid hydrothermal work will involve X-ray Fluorescence (XRF), Scanning Electron Microscopy, and water chemistry. 45th Lunar and Planetary Science Conference (2014) 2712.pdf

leaching of feldspars or other igneous minerals, while direct precipitation under neutral sinter conditions [e.g. smectite forms under a wider range of conditions. 7]. It is likely that both processes took place at Lassen [e.g. 9]; the amorphous phase in the altered substrate Table/2:/XRD/results sample from Sulphur Works likely formed by acid- sulfate leaching, while the amorphous phase in the rock coating at Drakesbad probably resulted from Mineral sinter precipitation. Future SEM analysis of these SW*12*1 SW*12*2 SW*12*14 SW#12#4 13#SW#1 BH*12*4 BH*12*5 DK*12*3 DK*12*5 DB*12*7 Amorphous XX X X XX samples will help confirm the presence of amorphous Quartz XX XXX + X XX XXX silica (as opposed to glass or another amorphous Tridymite XX X XXX X phase). Cristobalite XXX XX XXX XXX The Lassen hydrothermal system likely represents Feldspar X X a 2-phase system, where acid-sulfate steam separates Pyroxene X + from a hydrothermal reservoir, fueling high- Sulfur XXX + + X XX temperature, gas-driven fumaroles at higher elevations, FeJsulfide XXX leaving behind more neutral hot water that emerges at FeJoxide hot springs [9,10]. Thus, the same system produces Kaolinite X X X both acid-sulfate fumarole alteration and near-neutral Smectite + + XX X sinter deposition, in contact with the same volcanic Jarosite X XX substrate. Rhomboclase X Mars comparison: Ruff et al. [2011: 7] suggest a Voltaite X near-neutral sinter origin for the silica rich deposits Alunogen + XXX X + observed by the rover at the Columbia Hills of Alunite X X Gusev Crater, which would be a more habitable Natroalunite X environment than the previously envisioned acid- Ni/VJsulfate X sulfate environment. Nearby sulfate-rich soils could Gypsum XXX still be consistent with acid-sulfate conditions Calcite X [11,12,13], which would require a diverse suite of Table 2: XRD phases. SW=Sulphur Works, BH= Bumpass Hell, hydrothermal environments in a relatively small area. DK=Devil’s Kitchen, DB=Drakesbad. Samples in red collected from Lassen provides an analog for a single hydrothermal same spot in 2012 and 2013. XXX = abundant, XX = common, X = system that can produce this range of deposits; further rare to common, + = rare. geochemical and mineralogical studies can help The SiO2 mineral assemblage varied widely, and identify unique signatures that can be used to tell the included quartz, tridymite, cristobalite, and an two apart in the ancient rock record. amorphous phase likely consistent with amorphous Acknowledgments: This research was funded by silica. While quartz is a primary igneous component of grants from the Wisconsin Space Grant Consortium to the dacitic substrate, it was most abundant in samples to McHenry and Gerard. Thanks to Dr. W.-S. Han for lacking feldspar and pyroxene (other dacitic minerals), the use of the Hydrolab sonde, and to the NPS for so it is more likely related to the secondary and permission to sample within Lassen Park. precipitated minerals. Cristobalite and tridymite are References: [1] Phillips R.J. et al. (2001) Science also SiO2 phases associated with altered volcanics. 291: 2587-2591. [2] Hynek B.M., Beach M., Hoke Discussion: A year-to-year difference in M.R.T. (2010) JGR 115. [3] Yen A.S. et al. (2008) mineralogy and appearance was seen at a Sulphur JGR 113: E06S10. [4] Ehlmann B.L. et al. (2009) JGR Works fumarole visited in 2012 and 2013 (Fig 1). In 114: E00D08. [5] Schulze-Makuch D. et al. (2007) 2012, cm-scale thin crystals (identified as alunogen by Icarus 189: 308-324. [6] Walter M.R., Des Marais, XRD: Table 2) were observed, while a sample D.J. (1993) Icarus 101: 129-143. [7] Ruff S.W. et al. collected from the same spot in 2013 had no coarse (2011) JGR 116: E00F23. [8] Schmidt M.E. et al. crystals and minimal alunogen (quartz and tridymite (2009) EPSL 281: 258-266. [9] Janik C.J., LcLaren dominated). The 2013 sample likely represents the M.K. (2010) JVGR 189: 257-277. [10] Clynne M.A., substrate underlying the 2012 sulfates. The sulfate-rich Janik C.J., Muffler L.J.P. (2003) U.S. Geological deposit appears to have been largely dissolved, Survey Fact Sheet 101-02. [11] Morris R.V. et al. indicating that such deposits are very ephemeral and (2008) JGR 113: E12S42. [12] Wang A. et al. (2008) unlikely to be preserved in the rock record. JGR 113: E12S40. [13] Squyres S.W. et al. [2008] Amorphous silica can form during hydrothermal Science 320: 1063-1067. alteration, either by leaching under acidic conditions or