IRES Track I: Lithological controls on strain localization in metasedimentary rocks along the Southern Iberian Shear Zone

University Of Wisconsin-Milwaukee, Milwaukee WI

Investigators

Abstract

While stresses imparted on rocks during plate interactions may be pervasive, the characteristic structures formed by them that facilitate rock deformation are generally localized. Deformation or strain localization is an important phenomenon throughout the crust, resulting in major contrasts in rock strength that impact crustal architecture and tectonics, fluid flow, and potential seismicity. The researchers hypothesize that the factors that control strain localization vary by scale. The PI proposes to unravel the factors causing strain localization at a variety of scales within metasedimentary rocks at a major tectonic structure, the Southern Iberian Shear Zone in southwestern Spain. A diverse, international team of geoscience faculty, graduate students, and undergraduate students will perform this research by collecting integrated structural geology, geomatics, and geochemical datasets through an international field-based program of research and mentorship. Each year, four undergraduates and one graduate student will spend up to four weeks in Spain conducting fieldwork and perform follow-up analyses at UWM for a minimum of 13 weeks. Strain localization processes in the lithosphere are fundamental to our understanding of plate tectonics. While deformation may be pervasive throughout tectonic zones, deformation intensity is often strongly localized. Factors that may control strain localization include rheology contrasts and mechanical boundaries, differences in mineralogy or grainsize, fabric formation, and various grain-scale softening mechanisms, which are often enhanced by fluids. The primary scientific goal is to unravel multi-faceted causes of strain localization within metasedimentary rocks affected by the Southern Iberian Shear Zone and determine if and how they vary with scale. Faculty, graduate students, and undergraduate students will collect integrated lithology, tectonic fabric, microstructure, geomatics, and geochemical datasets through a field-based program of research and mentorship. The strength of this project lies in the integrated datasets derived from a suite of relatively modest graduate and undergraduate student projects. Brought together through careful spatial mapping and the integrated 3D digital model, these disparate datasets can create a holistic picture of strain localization. These results will help further our understanding of strain localization and shear band formation in other metapelitic units in a wide array of tectonic settings. The program will also enhance the careers of students as they gain international research experience. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.