Hyperarid Cold Polar Deserts on Earth:
The Antarctic Dry Valleys and Evidence for Climate Change
Here we are documenting and assessing microclimate zones in the hyperarid polar deserts through extensive fieldwork and analysis. These microclimate zones represent a very sensitive template to detect climate change, and we are assessing possible buried 8 million year old ice and its contained climate record in the upland frozen zone microenvironment. In the second year of this NSF-funded research, we analyzed the data from the first two field seasons (in which three Brown students, Joseph Levy, David Shean and Rebecca Parsons participated) and have five papers submitted or in press resulting from this work. This work, in collaboration with Dave Marchant at Boston University, has proven to be very important for teaching and research at Brown and also for application to Mars.
Water on Mars:
Evolution of Mars Polar Caps, Tropical Mountain Cold-Based Glaciers,
and Relation to the History of Mars Climate
We have been working for several years to document the water budget of Mars and to understand how the geological record might hold information about past climate. Sarah Milkovich recognized a fundamental climate signal in the polar layered terrain and David Shean and others have documented the presence of huge tropical mountain glaciers. Working with French global climate modeler colleagues, we have been able to show that obliquity excursions of 45o in recent Mars history are required to account for these deposits. We have also been working with a glacial modeler, Jim Fastook (University of Maine) to model accumulation and flow patterns predicted for the climate models and compare these to the geological record. This work has been very rewarding because of its synergistic nature. We co-sponsored a major workshop bringing climate modelers and geologists together to discuss these issues, In the past year we documented the presence of mid-latitude debris-covered valley glaciers and published several papers on the nature and significance of these.
Explosive Eruptions on Earth’s Seafloor
Research on the Earth's seafloor as a planetary environment continues with theoretical modeling of the ascent and eruption of magma in the high-pressure, deep seafloor environment (pressure equivalent to that of Venus) following our participation in a series of dives in the deep-sea submersible Pisces V to the summit of Loihi, where we found the first abundant evidence for widespread magmatic explosive eruptions at 1200 m depth. We followed up these studies with a two-week scientific cruise on the R/V Western Flyer and ROV Tiburon to the Gorda Ridge last summer; these new data provide important constraints on the eruption and dispersal of pyroclasts in the submarine environment.
Europa and Ganymede: Tectonics, Cryovolcanism and Global Oceans
High-resolution data from the Galileo Europa Mission (GEM) have given us insight into the nature of tidal interaction and surface deformation in keeping Europa geologically active late into its history. Wes Patterson continues to document evidence for the nature of tectonic structures, solid-state convection, and wide-ranging evidence for a global ocean at shallow depths under a brittle icy shell and a ductile substrate on Europa. Global mapping of Ganymede is nearing completion and will result in a USGS Map publication. We have developed a theoretical basis for the ascent and eruption of magma (liquid water) on Ganymede and Europa and are presently assessing cryomagmatic and cryovolcanic processes.
Global Evolution of Venus
Continuing progress has been made in interpretation of the global tectonics of Venus and understanding implications for Earth. We documented the global geological history of Venus and its tectonic and volcanic processes, and have provided evidence for possible catastrophic and episodic volcanic and tectonic activity late in the history of Venus. These findings have important implications for the formation of continents on Earth, the processes that might have initiated plate tectonics on our own planet, and the formation of large igneous provinces on Earth, themes that are presently being pursued. Two geologic maps (V-13 and V-61) are currently in press in the USGS Mapping program.