Review of hydrothermal processes and systems on Earth and implications for Martian analogues

Abstract

A review of hydrothermal processes and systems on Earth shows how they provide the environment for both the formation of ore deposits and for life on the modern through to the ancient Earth. We discuss submarine hydrothermal systems, subaerial volcanic and subvolcanic systems (low and high sulfidation), hydrothermal systems in the East African rifts and those of the Red Sea. Geothermal springs in both modern and ancient Earth exemplify the links between hydrothermal systems and life. Examples are discussed from the Sulphur Springs Group and Dresser Formation in the Pilbara Craton, Western Australia. These hydrothermal systems illustrate the dynamic, continuously evolving link between the lithosphere, hydrosphere and biosphere. A summary of the geology of Mars is used to develop ideas as to what type of hydrothermal systems may occur there and where to search for signs of ancient and possibly extant life, most notably around Tharsis volcanoes, caldera floors, in fractures and in rift valleys. The interaction of hot magmas with the cryosphere is proposed as a mechanism to explain many of the surface features of Mars. A model is developed to explain the widespread deposition of sulfates on Mars as hydrothermal precipitates, generated through the interaction of magmatic H2S in hydrothermal solutions with water in the cryosphere.