Physical Sciences and Mathematics Commons^™

Tectonic Rotations In The Cascade Mountains Of Southern Washington, Roger G. (Roger Glenn) Bates

WWU Graduate School Collection

Paleomagnetic directions from 34 widely distributed sampling sites in the Oligocene Ohanapecosh Formation in the Cascade Mountains of southern Washington are well grouped with a mean and confidence interval of: Dec. = 27°, Inc. = 64°, α₉₅ = 4°. When compared to the expected direction, computed from the Oligocene reference pole for stable North America, a clockwise rotation of 31° ± 12° is apparently present. This result is not significantly different from other studies within the Cascades and Coast Range of southern Washington and suggests that the two Ranges have rotated as a single unit during late Eocene to …

Stratigraphy, Lithology, And Depositional Environment Of The Black Prince Formation Southeastern Arizona And Southwestern New Mexico, Patrick Kevin Spencer

WWU Graduate School Collection

The Black Prince Formation (new manuscript name) of southeastern Arizona and southwestern New Mexico is subdivided into four lithologic facies representing four environments of deposition. The first lithofacies consists of the basal member of the type section of the Black Prince Limestone and is a result of erosion and reworking of the underlying Escabrosa Limestone. The three limestone lithofacies suggest deposition on a shallow shelf under supratidal, intertidal and subtidal conditions. Cyclic fluctuations in sea level are seen in the rock record in the vertical alternation of lithofacies. Six unconformities are recognized and these are traceable throughout the region.

The …

Geology, Petrology, And Paleomagnetism Of Eocene Basalts From The Black Hills, Washington Coast Range, Brian R. Globerman

WWU Graduate School Collection

Geologic mapping in the Black Hills area strongly suggests that the middle Eocene basalts of the Crescent Formation and over- lying upper Eocene and Oligocene sedimentary rocks constitute a structurally coherent terrane that is bounded by northeast- and northwest-trending faults. I interpret the Black Hills as a homocline which dips about 10° to 15° to the west. Units within the block are commonly cut by normal and reverse faults, but are not appreciably folded.

Major- and trace-element geochemical analyses indicate that the Black Hills suite is co-magmatic, and is composed of hyper- sthene-normative tholeiites which were apparently derived by plagioclase …

Geology And Petrology Of The Lake Ann Stock And Associated Rocks, Eric William James

WWU Graduate School Collection

The Lake Ann stock is a two pyroxene quartz monzodiorite to granodiorite epizonal intrusive emplaced into the Shuksan thrust fault in the latest Pliocene. It is similar to other Late Tertiary Cascade intrusives in mineralogy, texture, chemistry, and setting. These similarities are attributable to near surface emplacement, quick cooling and magmatic arc setting. Epizonal emplacement is indicated by fine, equigranular textures, granophyre, late stage alteration, late miarolitic dikes, plagioclase resorbed by alkali feldspar, and low pressure contact metamorphic assemblages. Temperature of emplacement was between 600°C and 925°C; pressure was less than 2 kb. Chemistry of individual samples and variation diagrams …

The Shuksan Metamorphic Suite And Shuksan Thrust Mt Watson Area, North Cascades, Washington, Ralph Albert Haugerud

WWU Graduate School Collection

Rocks of the Shuksan Metamorphic Suite exposed on Mt Watson are metamorphosed pillow basalts, basaltic flows (?), basaltic tuffs, carbonaceous sediments, Mn-enriched cherty sediments, rare calcareous sediments and rare ferromanganese nodules.

Greenschist of the Suite records the following history: 1) early static hydrothermal metamorphism; 2) Early Cretaceous (about 125 ma ago) synkinematic blueschist-facies metamorphism at P~7 kb, T~350° C, ^Pfluid ^{near P}total, ^XCO₂ < 0.1, with production of S₁ and L₁ ; 3) late-metamorphic isoclinal folding (F₂) around axes commonly at high angles to L₁; 4) L₃ crenulation of S₁. Phyllite of the …

The Petrology, Petrography, And Geochemistry Of The Black Jack Breccia Pipe, Silver Star Plutonic Complex, Skamania County, Washington, Robert H. Birk

WWU Graduate School Collection

Tourmaline-bearing breccia pipes are associated with late stage Tertiary porphyritic intrusive rocks in the Silver Star Plutonic Complex.

Whole-rock geochemical analysis of rocks from the complex show a silica vs. alumina/(K₂O + Na₂O + CaO) trend (Feiss, 1978) toward geochemical conditions favorable for porphyry copper-type mineralization. Copper present in diorite, quartz diorite, and quartz diorite porphyry rocks probably entered silicates, whereas copper formed porphyry copper-type mineralization in the more felsic granodiorite and granodiorite porphyry intrusions.

Optical, x-ray, and chemical analyses indicate two distinct populations of tourmaline present in the breccia pipes; an early "Hemlock Ridge-type" which …

Neoglaciation Of Avalanche Gorge And The Middle Fork Nooksack River Valley Mt. Baker, Washington, Steven Richard Fuller

WWU Graduate School Collection

The Neoglacial fluctuations of two of Mt. Baker's alpine glaciers were studied by tephrochronologic, dendrochronologic, and relative dating methods coupled with detailed geologic mapping. The earliest recognizable advance of the Deming Glacier occurred prior to deposition of Mazama tephra and after the Vashon Stade of Fraser Glaciation. The oldest recognizable Holocene advance of the Deming Glacier occurred >800 years B.P. and 16th, 17th, 18th(?), early 19th, late 19th, and 20th centuries. The Neoglacial record for the Rainbow Glacier is poorly preserved due to modification by two historic rock-debris avalanches, but the 20th century moraines of the Rainbow and Deming Glaciers …