Spectroscopic studies on the Puga Hot Spring Deposits, Ladakh: a
possible astrobiological Martian analog site in India
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 field 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 fossilized martian hydrothermal settings that are
prospective in the search for extinct/extant extra-terrestrial life.