Presentation by Russell Callahan.
Geologic and Tectonic Controls on Weathering, Water, and Ecosystems
Tectonic deformation and magmatic processes control mineralogy, and fracture networks, effectively preconditioning bedrock long before it is exposed at Earth’s surface. These inherited properties strongly influence how rock weathers which can strongly influence hydrologic and ecological processes on Earth’s surface. In this talk, I will share results from two studies that use geophysical observations to connect geologic and tectonic processes to patterns of subsurface weathering and critical zone processes. In the central California Coast Range, the regional tectonic environment promotes deep bedrock fracturing, leading to a weathering front that extends more than 10 m below the surface and supports deep groundwater recharge. In the southern Sierra Nevada, relatively small differences in granitic composition related to magmatic differentiation result in large contrasts in subsurface weathering, hydrologic storage, ecosystem productivity, and forest drought response. Together, these examples show that tectonic and geologic processes leave a strong and persistent imprint on critical zone structure, with clear consequences for hydrology and ecosystems.
