2/22/2017 - Climatic and geodynamic influences on ocean island geomorphology

Information:

12:00 PM - 12:50 PM
Geology 1707

Presented By:
Kim Huppert - MIT

Abstract

Climatic and geodynamic influences on ocean island geomorphology

With homogeneous bedrock, dramatic rainfall gradients, and remnant surfaces that constrain their age, initial topography, and vertical motions relative to sea level, volcanic ocean islands provide an exceptional natural experiment in landscape evolution. Analyses traversing gradients in island climate and bedrock age have the potential to advance our understanding of landscape evolution in a diverse range of continental settings. Yet, islands are initially conic, net subsiding, and boundary-dominated landmasses, in many ways dissimilar to most continental landscapes. In this talk, I examine unique aspects of island landscape evolution and exploit steep climate gradients and variations in bedrock age on volcanic ocean islands to quantify controls on erosion and constrain the contribution of lithosphere and mantle processes to surface deformation at hotspots. Through physically-based modeling, analysis of remote sensing and geochronologic data, and field measurements, I assess (1) the dominant mechanisms of vertical motion in the Hawaiian Islands, (2) the control of rainfall rates on the efficiency of bedrock river incision on the Hawaiian Island of Kaua’i, (3) the evolution of erosion rates over the course of landscape development on Kaua’i and other volcanic ocean islands, and (4) the mechanisms that cause volcanic ocean islands to subside below sea level to form atolls and guyots. These analyses provide empirical evidence for climatic control on erosion processes and they constrain the dynamics of plume-plate interactions at ocean hotspots.

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