Hydrogeology of Hot Springs/Martian Fossil Analog

Geological evidence suggests that the early environment of Mars might have resembled that of earth (McKay and Stoker, 1989). Hence, it is possible that the early history of life on Earth may have a counterpart on Mars. Stromatolites, rock structures built by microbial organisms, are the most conspicuous evidence of early life on Earth and, hence, are the most appropriate target for investigation on Mars. Among the modern environments in which stromatolites form are hot springs such as those of Yellowstone National Park, New Zealand and Iceland. The possibility of using modern hot springs a analogs for early life on Earth is currently under investigation by a research group based at the NASA-Ames Research Center of which Professor Hinman is part.

Hinman's research combines hydrogeological and hydrochemical characteristics of modern hot springs systems with textural features of rocks collected from these systems. The overall goal is to provide a basis for unraveling the complex petrographic, chemical and isotopic features of ancient hot springs on Earth and Mars. In many cases, it is difficult even on Earth to distinguish between biogenic and abiogenic structures in Archean and Proterozoic rocks. Hence with limited return payload capacity available on the Mars Lander mission, site and specimen selection are critical. It is therefore necessary to understand the chemical, thermal, hydrological, biological and organizational characteristics of hot springs systems. The timing of biological growth, mineral deposition and subsequent mineral phase transformation must be determined. In this manner, the probability of retrieving appropriate specimens will be maximized. These processes are controlled by the quantity and chemistry of water moving through the hot spring system; permeability enhancement and loss, along with water chemistry, will determine when and how well the microbial features are preserved. Results from Hinman's collaborative research show that textural preservation is dependent on depositional and post- depositional hydrogeological conditions. As in carbonate systems, a full understanding of the depositional and diagenetic history is not possible until the timing of cement emplacement and mineral deposition is determined.

Contact Information

Mail:	Dr. Nancy Hinman
	Department of Geology
	University of Montana
	Missoula, MT 59812