A Terrestrial Analogue for the Origin of Life? The Role of Mixing Zones in Modern Hot Springs in Rotorua, New Zealand

Abstract

Terrestrial hot springs have long been suggested to be a place for life’s origin, as early as Darwin’s “warm little ponds” of 1871, as they may have provided the ingredients necessary for life to get started. Understanding how life initiated and if life exists elsewhere in the Solar System have become hot topics over the past decade, with new research expanding our ideas of the ideal conditions in which life began, as well as upcoming Mars Missions that have astrobiological targets. Recently, exciting new work has begun testing in the field actual hypotheses regarding the initiation of life. This thesis presents new mineralogical and geochemical (water and sediment) data from mixing zones between geochemically distinct hot springs at Taupō Volcanic Zone, New Zealand, from field sites including: Tikitere/Hell’s Gate, Lake Rotokawa/Sinter Flats, Parariki Stream, and Wai-O-Tapu. To understand where elements are concentrating and minerals are precipitating, this study focuses on water and mineral geochemistry including: in-situ measurements, major anions, cations, trace elements, dissolved inorganic carbon (concentration and isotopes), dissolved organic carbon (concentration and isotopes), oxygen and hydrogen isotopes and sediment mineralogy and geochemistry (including: minor and trace element concentrations, Scanning Electron Microscope imaging and X-ray diffraction data). Results indicate a combination of processes lead to elemental concentration within mixing zones including but not limited to subsurface liquid-phase separation, and surface evaporation, temperature changes, pH changes, and redox gradients. These processes occurring within mixing zones allow for elements to concentrate and drive mineral precipitation within terrestrial hot springs. This thesis presents evidence for element concentration within different hot spring environments and thus supports the terrestrial hot spring origin of life hypothesis. Understanding the significance of mixing zones is not only important for a better understanding how life might have initiated on Earth, but also aids interpretations of putative hot spring deposits in Precambrian early life settings and may better inform the search for preserved life elsewhere in our Solar System and beyond.