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Studies the tectonic assembly of east-central Alaska through evidence from Cretaceous-Tertiary sandstones of the Kandik River terrane. Geochemistry; Paleotectonics; Petrography; Volcanic arc.

Presents the results of a study on the distribution of fluid pressure, the origin of cement and vein minerals that inhibit fluid flow, and the mechanisms for fluid migration and fluid-pressure generation within the northeastern part of Cook Inlet basin in Alaska. Tectonics of upper Cook Inlet basin; Lithology of tertiary and upper mesozoic sedimentary rocks.

Presents a study on the structural and kinematic evolution of tectonics in the Yukon-Tanana terrane in the northern North American Cordillera, Alaska. What the Yukon-Tanana upland consists up; Methodology used to conduct study; Factors that caused the kinematic evolution of tectonics in this area.

Discusses structural, metamorphic, and geochronological observations relating to the exhumation history of high pressure/low temperature metamorphic rocks in Seward Peninsula, Alaska. Crustal extension and unroofing of blueschists; Thinning of the crust; Partial erosional unroofing of metamorphic rocks.

Studies the crustal velocity structure of the northern Yukon-Tanana upland in central Alaska by analyzing the results of the US Geological Survey Trans-Alaska Crustal Transect (TACT) project in 1987. Description of the region; Division of the crustal velocity structure; Tectonic history.

The Kodiak batholith is one of the largest, most elongate intrusive bodies in the forearc Sanak-Baranof plutonic belt located in southern Alaska. This belt is interpreted to have formed during the subduction of an oceanic spreading center and the associated migration of a slab window. Individual plutons of the Kodiak batholith track the location and evolution of the underlying slab window. Six U/Pb zircon ages from the axis of the batholith exhibit a northeastward-decreasing age progression of 59.2 ± 0.2 Ma at the southwest end to 58.4 ± 0.2 Ma at the northeast tip. The trench-parallel rate of age progression is within error of the average slab-window migration rate for the entire Sanak-Baranof belt (19 cm/yr). Structural relationships, U/Pb ages, and a model of new gravity data indicate that magma from the Kodiak batholith ascended 5-10 km as a northeastward-younging series of 1-8-km-diameter viscoelastic diapirs. Individual plutons ascended by multiple emplacement mechanisms including downward flow, collapse of wall rock, stoping, and diking. Stokes flow xenolith calculations suggest ascent rates of 5-100 m/yr and an effective magmatic viscosity of ≈107-108 Pa s. Pre-existing structural or lithologic heterogeneities did not dominantly control the location of the main batholith. Instead, its location was determined by migration of the slab window at depth. [ABSTRACT FROM AUTHOR]

Late Neogene and younger deformation in Cook Inlet basin is caused by dextral transpression in the plate margin of south-central Alaska. Collision and subduction of the Yakutat microplate at the northeastern end of the Aleutian subduction zone is driving the accretionary complex of the Chugach and Kenai Mountains toward the Alaska Range on the opposite side of the basin. This deformation creates belts of fault-cored anticlines that are prolific traps of hydrocarbons and are also potential sources for damaging earthquakes. The faults dip steeply, extend into the Mesozoic basement beneath the Tertiary basin fill, and form conjugate flower structures at some localities. Comparing the geometry of the natural faults and folds with analog models created in a sandbox deformation apparatus suggests that some of the faults accommodate significant dextral as well as reverse-slip motion. We develop a tectonic model in which dextral shearing and horizontal shortening of the basin is driven by microplate collision with an additional component of thrust-type strain caused by plate subduction. This model predicts temporally fluctuating stress fields that are coupled to the recurrence intervals of large-magnitude subduction zone earthquakes. The maximum principal compressive stress is oriented east-southeast to east-northeast with nearly vertical least compressive stress when the basin's lithosphere is mostly decoupled from the underlying subduction megathrust. This stress tensor is compatible with principal stresses inferred from focal mechanisms of earthquakes that occur within the crust beneath Cook Inlet basin. Locking of the megathrust between great magnitude earthquakes may cause the maximum principal compressive stress to rotate toward the northwest. Moderate dipping faults that strike north to northeast may be optimally oriented for rupture in the ambient stress field, but steeply dipping faults within the cores of some anticlines are unfavorably oriented with respect to both modeled and observed stress fields, suggesting that elevated fluid pressure may be required to trigger fault rupture. [ABSTRACT FROM AUTHOR]