Abstract

Hot alkali chloride fluids ascend from deep geothermal reservoirs and discharge at the surface as hot springs. As the silica-rich fluid discharges and cools to below 100°C, the silica carried in solution precipitates and accumulates to form a rock referred to as siliceous sinter. Hot springs display broad temperature gradients from high temperature vent to low-temperature distal-apron areas. Distinctive sinter textures form, depending on environmental conditions such as flow rate or water temperature. These textures are preserved over time and throughout diagenesis. As sinters and deep geothermal reservoirs remain long after hot spring discharge ceases, sinter textures can be used to create maps of paleo-flow conditions and to establish the locations of historic hot up-flow zones. But does altitude make a difference? Can our knowledge of preserved low altitude sinter textures be applied to high altitude sinters? This study compares the modern high altitude hot springs of El Tatio, Chile with the modern low altitude hot springs of Orakei Korako, New Zealand. If we are to use textural recognition in paleo-sinter outcrops from different elevations to establish hot spring paleo-flow conditions, it is important to understand both hot spring environments, and how altitude influences sinter textures. By identifying the modern high and low altitude hot spring settings and associated microbial communities, we can recognize preserved sinter textures in high and low altitude ancient sinters. From accurate textural sinter mapping, high temperature locations could be targeted as sites for further exploration with more advanced exploration techniques such as geophysical methods.