Seward Peninsula, Alaska 2003
Project Leader: Jeff Amato
Field Assistant: J.R. Hennessey
Photos
In June 2003, Jeff Amato and undergraduate geology major J.R. Hennessey spent two weeks on Seward Peninsula, Alaska. The goal was to collect metasedimentary rock samples for U/Pb detrital zircon analysis. We collected from both the Nome Group and Kigluaik Group rocks along all of the major roads in the Nome area (see map on photo page). In addition, several orthogneiss and other metaigneous rocks were collected to provide further constraints on the depositional age of the sediments using cross-cutting relationships.
Structural Investigations in Lake Clark National Park, Alaska
Project Leader: Jeff Amato
Field Assistant: Kevin Hon
Photos
Abstract
The Tlikakila Complex in southern Alaska: A supra-subduction-zone ophiolite between the Wrangellia Composite terrane and North America (paper)
Southwestern Alaska consists of many tectonostratigraphic terranes, each of which is a fault-bounded assemblage of rocks with a unique geologic history. Three of the largest of the southern Alaska terranes include the Peninsular terrane, the Wrangellia terrane, and the Alexander terrane. Each of these terranes includes metamorphic and igneous rocks that were transported from far to the south to their present positions between early Mesozoic time and late Mesozoic to early Tertiary time.
The metamorphic rocks of the Lake Clark Region have not been examined in detail, and it is unknown whether or not they represent the roots of an island arc terrane, or instead represent oceanic crust that formerly separated the Peninsular terrane and mainland Alaska. The deformational history of these complexes is also unknown. For example, the Tlikakila complex crosses Lake Clark , which is an elongate glacial lake mapped as occupying a topographic depression within a strike-slip fault system. However, the complex itself does not appear to be significantly offset. These questions have important implications for Mesozoic tectonic reconstructions of southern Alaska.
The Ancestral Rocky Mountain Basins Project
This project examines the sedimetologic and stratigraphic evolution of two Ancestral Rocky Mountain basins; the Orogrande and Pedregosa basins. The stratigraphic record will be used to discern the tectonic history of these basins. Two past students have been partially funded for this program.
Paradox Basin Research Project, Utah
Castle Valley, near Moab
Project Leaders:
Katherine A. Giles
Timothy F. Lawton
Brenda J. Buck, UNLV
Salt walls and diapirs in the Late Paleozoic Paradox basin of Utah and Colorado are flanked by Pennsylvanian through Triassic strata that thin onto the salt structures, display halokinetic sequences, and contain diapir-derived detritus including fragments of dolostone and gypsum. Research in the Paradox basin builds on our theme of salt-sediment interaction in various salt provinces. A project in progress seeks to interpret how diapir growth influenced depositional facies, stratal geometries and soil development in the Lower Triassic Moenkopi Formation. A future project will examine stratal geometries in the Permian Cutler Formation with the objective of correlating them with well imaged geometries in the subsurface of the basin. These projects have applicability to exploration in the petroliferous Paradox basin and in other settings where salt walls have not been welded by shortening.
