Timothy Paulsen, Department of Geology, University of Wisconsin Oshkosh, 800 Algoma Blvd, Oshkosh, WI 54901 and Terry J. Wilson, School of Earth Sciences, Ohio State University, 125 S. Oval Mall, Columbus, OH 43210-1522.
The orientations and ages of elongate summit calderas on major polygenetic volcanoes were compiled to document Miocene to Pleistocene Shmin (minimum horizontal stress) directions on the western and northern flanks of the West Antarctic rift system. Miocene to Pleistocene summit calderas along the western Ross Sea show relatively consistent ENE long axis trends at a high angle to the Transantarctic Mountain Front and parallel to the N77ºE Shmin direction at Cape Roberts. Elongation directions of many Miocene to Pleistocene summit calderas in Marie Byrd Land parallel the alignment of polygenetic volcanoes in which they occur, except several Pleistocene calderas with ~NE-SW trends. The overall pattern of elongate calderas in Marie Byrd Land is probably due to radial stresses caused by thermal doming of the province and the rift-related stress regime. Some Antarctic calderas may have collapsed due to Neogene stress field changes caused, for example, by glacial loading and unloading.
[Manuscript]
