"Life on the Rocks: Mines, Microbes, & Martians"

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Picture a world before the dinosaurs when plants and animals hadn't evolved yet. Where volcanoes gave birth to new land and spewed toxic gases into an oxygen free atmosphere. Where the continents were just being born and where the oceans were almost free of life except for tiny single celled organisms. But what was there to eat? Look a little deeper. In the cracks and crevices deep beneath the seafloor seawater seeps down into the rocks, gets heated, and strips metals that are later concentrated in jets of dense black "smoke" that exit through mineralized chimneys rising like misshapen spires into the darkness. As these chimneys grow they sometimes crumble under their own weight, forming mounds that briefly expose their glistening riches of metal sulfides before they quickly rust in the cold, oxidized, salty seawater. In these deep, dark, watery places microbes have been found that colonize the sulfide mounds and glassy lavas beneath, extracting nutrients from this unlikely food source. Lavas are continuously erupted at undersea volcanoes that form mountain chains beneath the sea like seams on a baseball. These mid-ocean ridges are dynamic environments where globally significant chemical, biological, and heat fluxes occur between the geo-, hydro-, and atmosphere. The formation of new oceanic crust at ridge axes and the reincorporation of aged crust into the mantle at subduction zones are perhaps the most fundamental components of the plate tectonic cycle. These processes control the physiography of the Earth and the chemical and thermal evolution of the crust and mantle. The guiding principle of the proposed research is the investigation of water-rock-microbial alteration of oceanic crust through billions of years of Earth history. This is an emerging field that is at the forefront of interdisciplinary study. The temperature and depth limits of microbiological activity deep beneath the surface have yet to be explored in detail. Interactions between hydrothermal activity and the deep biosphere may have a profound impact on chemical fluxes during water-rock reactions that lead to vast economic enrichments of metals and possibly hold the key to the development of life on the Earth and other planets.