Influence of mantle dynamic topography on Quaternary sea-level change
Sea level has continuously changed throughout Quaternary glacial cycles due to redistribution of surface water between ice sheets and oceans; this sea-level change is spatially heterogenous due to a number of spatially variable processes. I seek to identify the relative influence of changes in mantle dynamic topography, the deflection of Earth's surface by viscous flow in the mantle. In particular, I am focusing on the MIS-5e sea-level highstand in the Caribbean region.
Effects of Quaternary climate variability on rivers and landscapes
While qualitative and quantitative models of landscape evolution typically assume steady environmental and climatic conditions, the paleoclimate record clearly shows that this assumption is violated most places on earth by Quaternary glacial cycles and associated climate changes. I seek to quantify the timescales of environmental change a river system is or is not sensitive to, and test the resulting predictions against observational evidence of fluvial response to an unsteady climate.
Mechanisms and processes of drainage reorganization and river capture
It is commonly recognized that the topology and geometry of river networks change through time, by a combination of gradual divide motion and abrupt river capture. However, a mechanistic understanding of these processes remains elusive due to the long timescales and infrequency of abrupt events. Using a combination of theoretical and numerical models and field measurements, I aim to test the role of feedbacks among drainage area, discharge, and sediment flux between growing and shrinking river basins to understand how drainage divides shift through time.
Implications of transport-limited behavior for erosional systems
Models of fluvial bedrock incision often assume instantaneous and complete removal of the eroded sediment. However, many erosional rivers on Earth exhibit significant alluviation of their beds, indicating that sediment transport may play an important role in the evolution of these systems. Theoretical models of erosion incorporating feedbacks between erosion, sediment transport, and alluvial bed cover predict a transport-limited regime in which erosion rate is governed by sediment transport processes rather than the detachment of bedrock material from the bed. I seek to explore the implications of this prediction for the topographic expression of lithologic heterogeneity, and test model predictions against observational evidence for the role of sediment transport in modulating rates of bedrock river incision.
Anthropogenic soil deposits in the Amazon
Amazonian dark earth is fertile, carbon-rich human-modified soil and is abundant in archaeological sites. However, its distribution and spatial patterns are poorly constrained due to labor-intensive field excavations typically used to identify it, and known locations likely exhibit substantial geographic sampling bias. I aim to use remote sensing imagery for automated detection of dark earth deposits. Combining this approach with laboratory measurements of carbon and other nutrients from dark earth allows the estimation of the carbon sequestration potential of these deposits.
Paleozoic climate and oxygen isotope thermometry
The early Paleozoic climate record is poorly constrained due to the sparsity of fossil material typically used for oxygen isotope paleothermometry. Nevertheless, a robust climate record of this interval is critical to evaluating hypotheses of linkages among the climate, tectonics and life during the time of early animal evolution. I use clumped-isotope geochemistry to assess the diagenetic character of ancient carbonate muds and the reliability of their bulk oxygen isotopic composition as a recorder of past surface conditions. Combining this analysis with a global compilation of bulk rock carbonate δ18O measurements yields a climate record that it consistent with available fossil evidence but allows far greater temporal and spatial coverage.