Spectroscopic Studies on the Puga Hot Spring Deposits, Ladakh, an Astrobiological Martian Analog Site in India. Issue 11 (4th November 2022)

• Record Type: Journal Article
• Authors: Sarkar, S.; Moitra, H.; Bhattacharya, S.; Dagar, A.; Ray, D.; Gupta, S.; Chavan, A.; Shukla, A. D.; Bhandari, S.
• Is Part Of: Journal of geophysical research. Volume 127:Issue 11(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-11-04
• Subjects: Planets -- Periodicals; Geophysics -- Periodicals; 559.9
• DOI: 10.1029/2022JE007299
• Languages: English
• ISSNs: 2169-9097

Abstract

Abstract: 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 (400–2, 500 nm) and lab measured mid‐infrared (4, 000–400 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. Plain Language Summary: Signatures of the earliest life on Earth are found around hot spring localities, where hot water from depth, containing chemicals dissolved from surrounding rocks, reached the surface. Hot springs have characteristic mineral assemblages, which, if present in extra‐terrestrial settings (e.g., on Mars), could indicate the presence of ancient hot springs that can be further explored for the signs of extinct or extant life. Detection of certain minerals, for example, chlorite and opaline silica on Mars, suggest the existence of ancient Martian hot springs, while hydrous sulfate minerals prove past water activity on Mars. To facilitate the identification of extra‐terrestrial hot springs, we have analyzed the complete mineralogical suite from the Puga hot spring deposit, Ladakh, India, which can act as an analog to cold and dry Martian conditions. We have used instruments equivalent to those presently deployed on the Martian rovers and identified sodium borate minerals like borax and tincalconite and hydrous sulfates such as alunite, jarosite, copiapite, gypsum, and tamarugite (reported for the first time from the Indian subcontinent) and opaline silica. This mineralogical assemblage can help us identify localities on Mars that might have hosted ancient hydrothermal systems having signatures of extinct or extant life. Key Points: We conducted detailed spectroscopic investigations on Puga hot spring deposit in Ladakh (UT), India using visible/near‐infrared, mid‐infrared, and XRD techniques Documented tincalconite‐borax occurrences associated with acid sulfates, tamarugite, gypsum, native sulfur, opaline silica, and halite Mineral assemblages identified at Puga by Martian rover equivalent instruments may be used to detect potential hydrothermal sites on Mars