Project Description
The McMurdo Dry Valleys region of Antarctica is one of the coldest, driest, and windiest places on the planet, and is often used as an analog for the surface of Mars. It is also the largest ice-free region of Antarctica, and thus its deposits and landforms contain unique records of past climate not accessible elsewhere in the Antarctic continent or the world. In order to accurately interpret any geologic feature, however, we must understand how it forms and changes through time. In particular, in the Dry Valleys, we have a poor understanding of the rates and causes of one of Earth's most fundamental geologic phenomenon - physical rock breakdown. For example, the Dry Valleys lack moisture which is thought to play a key role in rock breakdown in most other locations on the planet. What serves to fracture rocks in this seemingly inert environment? This project aims to answer that question by 'listening' as rocks crack in one of the most arid portions of the Dry Valleys, Beacon Valley. We will instrument several boulders with acoustic emission sensors that record microcracking events on and within the rocks. At the same time, we will monitor the environment around the rocks to record the conditions that trigger cracking events. We will also gather rock samples from deposits of different ages (from thousands to millions of years old). Cosmogenic nuclide techniques including a novel combination of 6 isotopes (Be-10, Al-26, He-3, Ne-21, Cl-36, C-14) together with rock property measurements (e.g., strength, elastic moduli, thermal properties) on these samples will be used to elucidate the complex relationship between long-term (kyr to Myr) boulder erosion rates, lithology, rock properties, and subaerial exposure duration. By synthesizing these measurements with short-term cracking data from the acoustic emission system, the proposed work will thoroughly examine which lithological and environmental factors and grain-scale processes are driving geomorphic evolution in the Dry Valleys. The combined datasets will allow future scientists to more accurately understand the paleoclimates and landscapes of Antarctica, and possibly even Mars.