^1,2S. Sarkar,³H. Moitra,^1,3S. Bhattacharya,¹A. Dagar,⁴D. Ray,³S. Gupta,³A. Chavan,⁴A. D. Shukla,²S. Bhandari
Journal of Geophysical Research (Planets)(in Press) Link to Article [https://doi.org/10.1029/2022JE007299]
¹Space Applications Centre, Indian Space Research Organisation, Ahmedabad, 380015 Gujarat, India
²Department of Earth and Environment Science, Krantiguru Shyamji Krishna Verma Kachchh University, Bhuj, 370001 Gujarat, India
³Department of Geology and Geophysics, Indian Institute of Technology Kharagpur, Kharagpur, 721302 India
⁴Physical Research Laboratory, Ahmedabad, 380 009 Gujarat, India
Published by arrangement with John Wiley & Sons

Hot spring localities on continents may represent the most probable locales for the formation of early life constituents on Earth. Apart from liquid water and carbohydrates, these components also include elements like boron that are crucial for stabilization of the complex organic molecules that constitute life. Many of these life sustaining ingredients are commonly found in the vicinity of terrestrial hot springs. Analogously, similar existing or extinct hot spring localities on other planets may constitute prospective astrobiological sites. In the present study, we have characterized the complete mineralogical assemblage of the Puga hot spring deposit, Ladakh, India, using detailed spectroscopic and X-ray diffraction studies. The spectroscopic characterization was done using both field as well as lab based visible/near-infrared (VNIR; 400-2500 nm) and lab measured mid-infrared (MIR, 4000-400 cm-1) hyperspectral data. The identified mineral phases include Na-borates, such as borax and tincalconite, and hydrous sulfates such as jarosite, alunite, copiapite, tamarugite and gypsum, in conjunction with native sulfur, halite and opaline silica. Borate minerals have been identified from the valley-fill material along with halite and opaline silica, whereas sulfates occur alongside crystalline sulfur deposits. We have compared mineral assemblages found in Puga with other hot spring/hydrothermal deposits on Earth identified as martian analog sites, and also with mineral assemblages identified in situ on Mars. We argue that the spectral characterization of hydrated borates in natural association with hydrous sulfates can be used for identification of fossil/paleo hydrothermal settings on Mars that are prospective in the search for extinct/extant extra-terrestrial life.