Thermal spring deposits are features of considerable interest to Mars scientists because of their potential as astrobiological oases and as records of the paleohydrology of the planet. Terrestrial counterparts can assist in recognizing such features on Mars and in developing technologies for their study and sampling. In this paper, we describe one such analog, the Dalhousie Springs complex in central Australia. The Dalhousie Springs complex is one of largest groundwater discharge landforms known on Earth. It is a carbonate-limited precipitation system due to the non-supersaturated ascending water. Spring carbonates are deposited as discrete mounds and outflow channels resting unconformably on older units. Although subject to postformation geomorphic modification, the spring deposits persist in the landscape and are recognizable long after the parental spring has shut down. We identify 14 specific microfacies belonging to seven facies, which form three environmental associations related to specific depositional environments. Diagenesis has occurred in several stages, as evidenced by distinctive textures on the deposits. Spring deposits on Mars would potentially be recognized by similar textures (although compositions may be quite different) and similar geomorphic relationships. However, in satellite images, spring deposits may be difficult to differentiate from deposits resulting from other processes that produce similar geomorphic features, including mud volcanoes, pingos, and rootless cones. Mineralogical data may assist, but ultimately ground truth will be required.

Abstract Our understanding of calcium carbonate precipitation within freshwater carbonate systems is being revolutionized by new quantitative approaches at both field and laboratory scale. These systems cover a diverse range of topical research areas including tufas, speleothems, stromatolites and microbial processes. Progress by various international research groups has been impressive, with major contributions to such areas as climate change, absolute dating, carbon sequestration, and biofilm construction and precipitation. A diverse sample of interrelated research is presented that provides a tantalizing glimpse of the interplay between microbial, geochemical and physical processes that control the development of tufas and speleothems. This volume will provide a cross-disciplinary platform that will stimulate further exchanges about new concepts, methodologies and interpretations associated with freshwater carbonates. In particular, it will help reinforce the importance of cross-discipline research: the driving force behind the new field of Geobiology.