Jay Chapman

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Field of Study: Structure and Tectonics

Summary

I am working with Terry Pavlis on the Saint Elias Erosion and Tectonics Project (STEEP) in the Chugach-St. Elias mountains in southern Alaska. STEEP is a five year project (2005-2010) aimed at understanding the complex interactions between tectonics and erosion in an orogenic system. Among my interests are how focused erosion can lead to localized deformation in an active convergent orogen and if these surficial interactions on small to medium sized structures (e.g. individual thrust sheets) can affect overall orogenic architecture on longer time-scales. I am using structural techniques along with other analytic methods to contrain how oblique collision is currently partitioned within the orogen and understand the spatial and temporal variability of the orogen's deformation history. In addition, I am focusing on linking the longer structural record with a suite of neotectonic techniques (tectonic geomorphology, remote sensing, paleoseismology, etc.) to build a more complete narrative of tectonic processes.

Current Research

At the boudary between the western syntaxis and central segment I am trying to quantify uplift rates and subsurface structural geometry in the Suckling Hills, which is part of the Kayak Island - Bering Glacier fault system that likely represents a splay off the Aleutian megathrust. The Suckling Hills preserve a upland surface mantled by glacial loess that I hope to OSL date and use as a structural marker along with more traditional structural data..

In the western segement, the Yakutat terrane suture zone crosses Wingham Island where a uplifted section of Quaternary marine deposits are preserved that may record both a paleoseismic signal and erosional history beyond the Holocene, which is the current limit for the paleoseismic record of megathrust events and known glacial limits. I hope to use diatom analysis, stratigraphic relationships, and radiocarbon dating to piece back together this history.

In the central segment, I have been using structural and tectonic geomorphic techniques to examine active faulting and am interested in modelling how strain may have been repartitioned from margin normal thrusting in a typical fold and thrust belt to an oblique en echelon thrust system. In particular, I would like to understand if the process by which orogens evolve towards doubly vergence and if mass redistribution from focused erosion played a role in the evolution of the system.

My thesis work is primarily focusing on the Eastern syntaxis of the St. Elias orogen, which is the nexus between the transfer of strike slip motion from the Fairweather fault into the orogenic interior, likely retrothrust motion in the backstop, an active thrust front in the foreland, and the Dangerous River Zone (DRZ) where basement changes from continental to oceanic affinities and pre-tectonic sedimentary cover thickens abruptly to the west. In addition, the Seward and Malaspina glacial system (one of the largest and most dynamic in North America) occupies this region of high topography (~5km peaks) and is part of a dynamic geodynamic system. I am working on constructing an accurate map of the region and geometric fault model through remote sensing and structural / mechanical analysis.

Within the Eastern syntaxis, the Samovar Hills is something of a Rosetta stone for regional tectonics and is the only known exposure of the DRZ and oceanic basement. The area preserves an older history of deformation, previously unrecognized, and may record a polyphase deformational history encompassing the transition from strike-slip to thrust motion. At the leading edge of the deformation front, the overprinting of young structures is likely a template for strain histories throughout the rest of the orogen. Detailed mapping in the last two field seasons including kinematic studies combined with 3D structural reconstructions will resolve some of these relationships.

Email: jbchapman @ miners.utep.edu
Office phone: x5983 (shared graduate student phone)
Geological Sciences Building Rm. 212
Office Hours: T,R 9:30 - 10:30