Fall 2018 Colloquia

August 20: Gary Pavlis, Earth and Atmospheric Sciences Title: Three-dimensional Structure of the Alaska System and the St. Elias Syntaxis

Abstract: My presentation is a review of current knowledge the three-dimensional structure of Alaska at lithospheric to crustal scale. I will first review the Cenozoic history of Alaska to clarify the fundamental role the Yakutat microplate has played in shaping Alaska tectonic over the past 20 million years. I use plate kinematics to argue that the southern tip of the Yakutat microplate can serve as an anchor to constrain the geometry of the eastern edge of subducting Yakutat slab. GPS data indicate the Yakutat microplate is currently moving as an independent block midway between two feasible end members. The end members are defined by two strike slip faults that define the southern (Transition Fault) and eastern (Fairweather Fault) boundaries of the Yakutat microplate. I then show components of a 3D model of Alaska developed for a paper presently in press in Geosphere. The model defines the geometry by three surfaces: (1) topography, (2) crust-mantle boundary, and (3) mantle lithosphere. The later is different from the former throughout much of the area because multiple lines of evidence indicate large parts of southeast Alaska crust do not move coherently with underlying mantle. Finally, I focus on the syntaxis formed by a tectonic corner in southeast Alaska near Mt. St. Elias.

Thermochronology results demonstrate uplift rates in the region east of St. Elias are comparable to the eastern and western syntaxes of the Himalya. In our Geosphere paper we argue the strong uplift is linked to a crustal scale structure we call the middlebuster structure because of its resemblance to a two sided plow with that name used in farming.

August 27: Larisa DeSantis, Vanderbilt University. Title: Clarifying Mammalian Responses to Climate Change and Megafaunal Extinctions during the Pleistocene

September 3: No Colloquium - Labor Day

September 10: Maria Mastalerz, Indiana University Geological and Water Survey. Title: TBA

September 17: Quinn Lewis, Earth and Atmospheric Sciences. Title: TBA

September 24: Arndt Schimmelmann, IU Earth and Atmospheric Sciences. Title: TBA

October 1:TBA

October 8: Sarah Schanz, Earth and Atmospheric Sciences. Title: TBA

October 15: Suzana Camargo, Columbia University. Title: TBA

October 22: TBA

October 29:Dylan Ward, University of Cincinnati. Title: TBA

November 5: Annual GSA Meeting, Indianapolis

November 12:Scott Robeson, IU Department of Geography. Title: TBA

November 19:No Colloquium, Thanksgiving Break

November 26:David Boutt, Northeast Climate Adaptation Science Center, University of Massachusetts Amherst. Title: TBA

December 3: TBA

December 10:End of Semester