Geodynamic mechanisms of basin and plateau formation in subduction settings

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Underpinning the geosciences, the plate tectonic paradigm describes creation of lithospheric plates at mid-ocean ridges, their translation across Earth's surface, and destruction by subduction beneath another plate at oceanic trenches. Subduction zones can develop plateaus with extreme topography that have profound impacts on atmospheric circulation, the Earth's climate, and can lead to rapid evolutionary change and biodiversity hotspots. Vertical movement of the Earth's crust in the retroarc, the region on the opposite side of the magmatic arc from the trench, is a sensitive recorder of mountain-building processes related to subduction. Understanding the processes that produce plateaus therefore informs a range of disciplines. I integrate quantitative basin analysis, sediment provenance, and paleoelevation reconstructions to establish vertical crustal movements and link those to the processes that cause basin (downward movement) or plateau formation (upward movement) related to the evolution of subduction systems. The long-term objective of my research is to determine the causes and impacts of plateaus globally. The short-term objective is to understand plateau formation in subduction systems by examining the Bolivian Central Andean Plateau, which is archetypal of the transition from a low-elevation, retroarc foreland basin to a high-elevation plateau. Recent models of retroarc evolution in the Central Andean Plateau of Bolivia and Peru have emphasized a unified basin and uplift history. My recent research (1) revised this model in Peru by providing evidence that the northern segment of the basin may have been partitioned early, accompanying shallowing of subduction, and (2) developed a new paradigm of spatially and temporally variable surface uplift implicating multiple processes in plateau construction. I will document downward crustal movement by determining the rate and locus of basin formation, as well as identifying sediment source areas, through application of a multi-variate approach to determine the source and age of sedimentary basin fill. I will also apply a new method to assess the paleoelevation history of this region that will extend and independently verify previous paleoelevation research. Finally, I will develop new analytical tools in intuitive, open-source software to analyze multi-variate sediment provenance data sets such as the one described above. This study will provide multi-disciplinary field- and lab-based training to a diverse, international group of at least 3 PhD, 2 MSc, and 5 undergraduate students as well as potentially a Colombian post-doctoral fellow (pending additional funding). The 2 MSc projects will be led by Bolivian women who are starting in Fall 2020. I will establish a supportive and inclusive research environment, and will mentor students through successful completion and on into their careers thus increasing representation and success of traditionally underrepresented groups in the geosciences.