I have identified evidence for potentially active northeast-striking faults in the greater Fairbanks area and have developed a model for their evolution that defines the character of faults and timing of structural events. Seismicity, topographic data, and geological and geophysical maps show that potentially active faults correspond with previously mapped bedrock faults, topographic lows, and magnetic anomalies. Seismicity indicates that faults in Interior Alaska have low to moderate tectonic activity; geomorphic and structural analyses of mapped faults indicate they are dominantly left-lateral strike-slip, but have smaller normal or reverse components. The normal component of slip increases to the west toward the Nenana basin based on tilted fault block geometries observed in seismicity. Deformed Pliocene to Quaternary strata, placer deposits presumably related to tectonic-induced stream capture events, and geomorphic anomalies such as valley and basin asymmetry, barbed drainages, and changes in river morphology all suggest Pliocene-Quaternary tectonic activity along northeast-striking left-lateral faults. Northeast-striking faults have been at least episodically active since the late Cretaceous. Northeast-striking fault-hosted gold deposits related to ~90 Ma intrusions suggest that fault parallel extension fractures or tension veins formed at ~90 Ma during a period of northwest-southeast extension. Thermochronological data are consistent with exhumation at ~56-42 Ma, possibly resulting from dextral shearing between the Denali and Tintina faults. Northeast-striking faults were reactivated as normal faults along pre-existing extensional trends. Thermochronological data suggest that strike-slip displacement on the Tintina fault significantly decreased at ~42 Ma. However, dip-slip motion continued along northeast-striking faults after 42 Ma as a result of contraction related to northward plate convergence. Drainage restorations, high-levels of background seismicity, and focal mechanisms support the hypothesis that at ~6 Ma, significant left-lateral motion occurred along northeast-striking faults and has continued to the present.

Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 179. This multidisciplinary monograph provides the first modern integrative summary focused on the most spectacular active tectonic systems in North America. Encompassing seismology, tectonics, geology, and geodesy, it includes papers that summarize the state of knowledge, including background material for those unfamiliar with the region; address global hypotheses using data from Alaska; and test important global hypotheses using data from this region. It is organized around four major themes: subduction and great earthquakes at the Aleutian Arc, the transition from strike slip to accretion and subduction of the Yakutat microplate, the Denali fault and related structures and their role in accommodating permanent deformation of the overriding plate, and regional integration and large-scale models and the use of data from Alaska to address important global questions and hypotheses. The book's publication near the beginning of the National Science Foundation's EarthScope project makes it especially timely because Alaska is perhaps the least understood area within the EarthScope footprint, and interest in the region can be expected to rise with time as more EarthScope data become available.

"The convergent margin of southern Alaska is considered one of the type areas for understanding the growth of continental margins through collisional tectonic processes. Collisional processes that formed this margin were responsible for multiple episodes of sedimentary basin development, subduction complex growth, magmatism, and deformation. Two main collisional episodes shaped this Mesozoic-Cenozoic continental margin. The first event was the Mesozoic collision of the allochthonous Wrangellia composite terrane. This event represents the largest addition of juvenile crust to western North America in the past 100 m.y. The second event is the ongoing collision of the Yakutat terrane along the southeastern margin of Alaska. This Cenozoic event has produced the highest coast mountain range on Earth (Saint Elias Mountains), the Wrangell continental arc, and sedimentary basins throughout southern Alaska. Active collisional processes continue to shape the southern margin of Alaska, mainly through crustal shortening and strike-slip deformation, large-magnitude earthquakes, and rapid uplift and exhumation of mountain belts and high sedimentation rates in adjacent sedimentary basins. This volume contains 24 articles that integrate new geophysical and geologic data, including many field-based studies, to better link the sedimentary, structural, geochemical, and magmatic processes that are important for understanding the development of collisional continental margins."--Publisher's website.

The NE-trending Nenana basin is a Cenozoic-aged basin located in central Alaska between the Denali and Tintina fault systems. The narrow, deep basin is a current exploration target for oil and gas resources in Interior Alaska. Natural fractures were analyzed to further understand larger structural features such as faults and folds related to the structural evolution of the Nenana basin and surrounding areas. Fracture sets were measured and described on the margin of the basin at four field locations: the Fairbanks area, along the Parks Highway between Fairbanks and Nenana, and in outcrop around the Nenana and Healy areas. In addition to measuring fracture sets in outcrop and collecting oriented samples, statistical and thin section analyses were used to further analyze fracture characteristics. Calcite twin thermometry and apatite fission track analysis were used to constrain the timing and thermal evolution of the field area. Based on the orientations of observed map-scale faults, folds, and fracture sets, I divided the four field locations into two structural domains. Domain I is characterized by NE-striking faults and associated active seismicity while Domain II is dominated by E-W striking folds and faults related to the late Cenozoic development of the Northern Foothills fold-and-thrust belt. I interpret that fracture sets in Domain I are related to the evolution of high angle faulting between the Nenana basin and the Fairbanks area during Cenozoic time. In Domain II, I interpret fracture sets are related to the evolution of the fold-and-thrust belt north of the Alaska Range. By combining fracture characteristics and apatite fission track analyses I provide constraints for the timing and shear sense of larger structural features related to the opening history of the Nenana basin. Furthermore, I propose that the evolution of the Nenana basin took place in three distinct tectonic phases during the Cenozoic. The three phases represent the transition from a pure extensional setting in the Late Paleocene to oblique-extensional faulting from the Late Miocene to present day.