Physical Sciences and Mathematics Commons^™

Magnetic Fabric Analysis Of Foreslope Sediments Of The Fraser River Delta, British Columbia, Andrew P. (Andrew Paul) Wiser

WWU Graduate School Collection

The results of a combined magnetic fabric and sedimentological investigation of trench and ridge structures along the foreslope of the Fraser Delta, British Columbia, indicate that turbidity currents are the likely origin of slope morphology. Evidence includes multiple and repetitive sequences of graded beds where trench and ridge structures are most pronounced and abundant. Distal to this region are fewer graded bedding sequences and increased evidence of hemipelagic deposition. A magnetic fabric analysis of cored sediments supports these conclusions. Stereographic projections of AMS ellipsoids from graded beds extracted from the mid-slope display characteristic turbidite relationships, whereas distal cores display hemipelagic …

Paleomagnetism And Detrital Zircon Geochronology Of The Skeena Group, British Columbia, Christopher L. Ward-Guthrie

WWU Graduate School Collection

The mid-Cretaceous Skeena Group of British Columbia is a sedimentary continental margin deposit that overlies the lower Jurassic Hazelton Group of the Stikine Terrane. Nine paleomagnetic sites were collected in 2006 and 2007, demagnetized thermally in 50-15°C steps, and high temperature components fit using principal component analysis. A new Ar⁴⁰/Ar³⁹ age of 93.9 ± 0.6 Ma for a flow of the Rocky Ridge Formation was also collected.

Three volcanic sites of the Rocky Ridge Volcanics possess coherent magnetizations, but did not prove useful. Five of six sedimentary sites from the Rocher de Boule and Bulkley Canyon Formations …

Timing And Nature Of Post-Collapse Sedimentation In Kulshan Caldera, North Cascades, Washington, Dennis M. (Dennis Martin) Feeney

WWU Graduate School Collection

Sedimentary rocks found in the 4.5 x 8 km Kulshan caldera of the Mount Baker volcanic field in the North Cascades, WA, indicate that the post-collapse basin hosted a lacustrine environment shortly after the initial collapse at 1.149 Ma (Hildreth, 1996). The sedimentary rocks of the 14 Goat area in Kulshan caldera are well-preserved in 124 meters of stratigraphic exposure. Blocks of wall rock debris in the lower stratigraphy show instability in the caldera wall. Intermediate and late stages are mainly turbidites composed primarily of sediments derived from extra-caldera ignimbrite. From these 1 interpret the 14 Goat area of Kulshan …

Characterizing Surface Deformation From 1981 To 2007 On Mount Baker Volcano, Washington, Brendan E. Hodge

WWU Graduate School Collection

Surface deformation studies at active volcanoes are used to detect changes to magmatic source regions beneath the volcano. At Mount Baker, Washington, continued elevated gas (CO₂ and H₂S) and heat flux from fumaroles in Sherman Crater indicate the presence of a degassing magma reservoir. Campaign geographic positioning system surveys in 2006 and 2007 provide slope distance measurements of all 19 trilateration lines on Mount Baker. These data are compared with previous slope distance measurements acquired in 1981 and 1983 with electronic distance measurement. The results indicate that surface deformation has occurred on Mount Baker during the last …

An Investigation Of The Magnetic Fabrics And The Paleomagnetism Of The Ghost Rocks Formation, Kodiak Islands, Alaska, Sean F. Gallen

WWU Graduate School Collection

Recent tectonic models based on the hypothesized existence of the Resurrection plate between the Kula and Farallon plates have questioned the location(s) of trench-ridge-trench (TRT) triple junction(s) along the Northern Cordilleran margin during Paleocene to Eocene time. The Paleocene Ghost Rocks Formation, located in the Kodiak islands, Alaska (latitude ~57°N), consists of pillow lavas and hypabyssal sills interbedded with turbidites, and is interpreted to have formed in a trench slope or slope basin during the passage of a TRT triple junction. A previous paleomagnetic study (Plumley et al., 1983) on the volcanic flows of the Ghost Rocks Formation suggests these …

Revisiting The Seven Devils-Wrangellia Connection: The Paleogeography Of Triassic Rocks In Western Idaho., Michael Liam. Kalk

WWU Graduate School Collection

The origins of and relationships between allochthonous terranes located west of the ⁸⁷Sr/⁸⁶Sr 0.706 line (Armstrong et al., 1977) have profound implications for understanding the Mesozoic paleogeography of western North America. The Wallowa- Seven Devils terrane has long been associated with Wrangellia, whose fragments can now be found in British Columbia, Canada and Alaska. However, stratigraphic, fossil, geochemical, structural, and paleomagnetic evidence linking the Wallowa-Seven Devils terrane to Wrangellia is considered equivocal (Follo, 1992). A new paleomagnetic study of the Seven Devils terrane may yield better results than Hillhouse et al. (1982) and, in conjunction with other …

Kinematic Analysis Of Ductile Features Within The Northern Wenatchee Block, North Cascades, Washington, Gerald Griesel

WWU Graduate School Collection

The Cascade crystalline core of Washington State is a block of high grade metamorphic and plutonic rocks at the southeast end of the Cretaceous-Tertiary Coast Plutonic Complex. Previous workers have debated whether northwest translation or southwest-vergent thrusting was responsible for regional metamorphism and deformation. The present study finds structural evidence supporting both orogen-normal and orogen-parallel displacements, thus indicating that the regional deformation can be broadly characterized as transpressional.

Units of the study area include: 1) the Napeequa schist, derived from an ocean floor protolith, and 2) an accreted Triassic arc, which includes the Marblemount Meta Quartz-Diorite (MMQD) and metamorphosed volcanic …

Structural Geology Of The Central San Juan Islands, Northwest Washington, Todd I. Belanger

WWU Graduate School Collection

Within the Late Cretaceous San Juan thrust system, northwest Washington, tectonically juxtaposed melange separates the relatively unmetamorphosed, arc-affinity Fidalgo Complex and the high pressure-low temperature, MORB-affmity Ocean Floor terrane. Structural analysis. X-ray diffraction, and fault-slip analysis are used to constrain the relative timing, kinematics, and pressure-temperature conditions of postfabric ductile and brittle deformation in the Fidalgo Complex, Ocean Floor, and melange. Structural analysis of the melange, Fidalgo Complex, and Ocean Floor terranes help to constrain the tectonic development of the structurally highest terranes in the San Juan thrust system and provide insight into the mechanisms required for uplift of high-pressure …