Physical Sciences and Mathematics Commons^™

Geology And Structure Of The Western And Southern Margins Of Twin Sisters Mountain, North Cascades, Washington, Frederic I. Frasse

WWU Graduate School Collection

Detailed mapping of the Goat Mountain dunite and the western and southern margins of the Twin Sisters dunite indicates that the structural setting of these bodies is dominated by high-angle northwest-trending fault zones. The Goat Mountain dunite overlies rocks of the Chilliwack Group and Yellow Aster Complex as a lowangle, west-dipping slab approximately 2500 feet thick. Cretaceous phyllite west of Goat Mountain overlies Chilliwack Group rocks along a similar low-angle west-dipping fault contact. These structures are both truncated by high-angle fault zones.

The timing of faulting is poorly constrained. High-angle faulting is at least post-Eocene through Holocene (?), and may …

The Geology And Mineralogy Of Bentonites And Associated Rocks Of The Chuckanut Formation, Mt. Higgins Area, North Cascades, Washington, Susan Kinder Cruver

WWU Graduate School Collection

In the Mt. Higgins area, the Chuckanut Formation is in probable fault contact with pre-Tertiary metamorphlc rocks. The Chuckanut is over- lain by Oso volcanics (zircon fission track age of 43.2 ± 1.9 MY). A diorite body (k/At date = 53 ± 8 MY) crops out in the Granite Lake area and is thought to be intrusive into the Chuckanut. Sedimentary rocks of much of the study area are dominantly thick- bedded arkoses that are generally cross-bedded, and resemble the Chuckanut type section. Sediments cropping out along and near Deer Creek are different; black, bituminous shale is the dominant rock …

The Rocks Of Bulson Creek: Eocene-Oligocene Sedimentation And Tectonics In The Lake Mcmurray Area, Washington, Kim Lance Marcus

WWU Graduate School Collection

Upper Eocene to lower Oligocene sedimentary rocks in the Lake McMurray area of Skagit County, Washington, consist of approximately 1500 m of conglomerate, sandstone, shale, and siltstone which were deposited in fluvial and marine environments along the continental margin. These rocks are known as the rocks of Bulson Creek.

Two main lithofacies can be recognized within the sequence: the lowest is nonmarine and consists of poorly sorted, thick, and structureless conglomerate with interbedded sandstone, siltstone, shale, and minor coal lenses; the upper lithofacies grades from a transitional nonmarine facies to a shallow water marine facies that consists of well sorted, …

The Chemical Composition Of The Shuksan Metamorphic Suite In The Gee Point - Finney Creek Area, North Cascades, Washington, Leah V. Street-Martin

WWU Graduate School Collection

Samples from the Shuksan Metamorphic Suite in the Gee Point-Finney Creek area were analyzed for twelve major elements and for the trace elements Y, Sr, Rb, Sc, Ni, Cr, Cu, Zr and Ba. The chemical compositions suggest that the protolith for the blueschist and greenschist was tholeiitic basalt, that the protolith for the iron-rich metasediment was a hydrothermally-formed sea floor precipitate on an active oceanic ridge and that the pelitic schists were once deep sea pelagic sediments. This assemblage probably formed along an oceanic spreading ridge.

The Mineralogy, Petrology And Geochemistry Of The Uranium-Bearing Vein Deposits Near Boulder, Montana, And Their Relationship To Faulting And Hot Spring Activity, Stanton Parker Dodd

WWU Graduate School Collection

Three "siliceous reef" uraniferous vein deposits of the Boulder batholith were studied. Two of these, the Free Enterprise and the W. Wilson, occur within hydrothermally altered Late Cretaceous Butte Quartz Monzonite and related rocks. Both deposits contain fine-grained iron and base-metal sulfides and uraninite in a matrix of microcrystalline quartz and chalcedony. The deposition of uraninite in these veins was contemporaneous with the majority of the sulfide minerals. The third deposit studied, the uraniferous Red Rock Mine, is similar in many respects to the other two occurrences, yet occurs within altered Late Cretaceous Elkhorn Mountains Volcanics.

All three occurrences formed …

The Paleomagnetism Of A Thick Middle Tertiary Volcanic Sequence In Northern California, Douglas Edward Craig

WWU Graduate School Collection

The mean direction of remanent magnetism for 44 sampling sites from Oligo-Miocene lava flows in northern California points about 12° east of the expected Oligo-Miocene geomagnetic field direction for the area. Our paleomagnetic data and other data indicate that the Cascade Range has rotated clockwise since the middle Tertiary. Similar, but larger, clockwise rotations have been documented in previous studies throughout the Coast Ranges. Two mechanisms are suggested to account for the differential rotation that has occurred within the Coast and Cascade Ranges. First, the Coast Ranges are rotated and then accreted to a curved continental margin during the Eocene, …