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Geology Newsletter- 1983, Department Of Geology

Geological and Environmental Sciences News

Vol. 1 No. 8

• Dear Alumni and Friends
• Geology Development Fund
• Faculty News
• Geology/ Earth Science Club
• 1982-1983 Awards and Scholarships
• Alumni News
• Geology Department Graduate Students

The Geology Of The Southern Bull Mountain Area, Jefferson County, Montana, Michael Edward Streeter

Masters Theses

The Late Cretaceous-Early Tertiary Laramide orogeny was responsible for the northward tilting of the pre-Eocene rocks of the area. The Late Cretaceous deposition of the Elkhorn Mountains Volcanics resulted in the volcanic-Madison Group unconformity. Late Cretaceous faulting took place probably in response to caldera subsidence. Laramide uplift erosion and downstream transport resulted in the deposition of the Conrow Creek conglomerate and debris flows over the Lodgepole Limestone. Block faulting took place in response to regional extension probably during Late Oligocene-Early Miocene time resulting in the formation of the St. Paul's Gulch, Golden Sunlight, and Boulder basin faults. The Oligocene Dunbar …

Environment Of Deposition Of The A-1 Carbonate, Salina Group, Michigan Basin, Barbara June Leonard

Masters Theses

The lower Salina Group of the Michigan Basin is composed of a cyclic succession of carbonate and evaporite units. The lowermost Salina unit is the A-1 unit which consists of a lower A-1 evaporite and an upper A-1 carbonate. The A-1 unit is underlain by Niagara Group carbonates. The transition from Niagaran carbonates to A-1 evaporite to A-1 carbonate has not been thoroughly understood and previous models have not satisfied some of the evidence. This paper sets forth the hypothesis that the A-1 carbonate was deposited in a non-marine lake environment rather than an isolated marine environment. Findings supporting this …

The Geology Of Burnt Ridge Quadrangle And Vicinity Ravalli County, Montana, Randall Reichert

Masters Theses

Peltitic schist, quartzofeldspathic gneiss, and calc-silicate rocks of the Precambrian Belt Supergroup hav ebeen intruded by granatic plutons of the northeastern Idaho batholith within the vicinity of the southern Bitterroot Range, Montana. These units were mylonitized along the eastern margin of the intrusive complex, with shear surfaces presently dipping approximately 20° to the east. Rhyolitic ash flows and associated mafic to felsic dikes developed on and within the granitic-metamorphic terrance during Tertiary time. Numerous northeast- trending and northwest-trending faults and joints are present throughout the mapped region.

The following events play a major role in the geologic history: 1) amphibolite- …

Sedimentation Rate Of Salt Determined By Micrometeorite Analysis, James Matthew Barnett

Masters Theses

The sedimentation rate of the A-l Evaporite of Michigan was determined by analysis of micrometeorites found as inclusions in the halite deposit. The samples were obtained from the Dow Chemical Company salt well number eight. The residue from the dissolved salt was magnetically separated and later analyzed by Particle Induced X-ray Emission (PIXE), X-ray diffraction , and microprobe techniques. The amount of extraterrestrial material was determined from the quantity of nickel present.

A sedimentation rate of .01 to .4 centimeters per year was calculated for the salt based on a constant influx rate of meteoritic material of 1 x 10 …

The Geology And Geochemistry Of The Summit Creek Molybdenum Prospect, Custer County, Idaho, Thomas Murray Hanna

Masters Theses

The Summit Creek stock, a molybdenum prospect located in the Pioneer Mountains of central Idaho, is a 46.7 m.y. old medium grained, slightly porphyritic quartz monzonite, which has intruded the late Ordovician Phi Kappa formation. Trend surface analysis shows that the stock is the product of one intrusive event. Pervasive mineral alteration usually associated with such porphyry (stockwork) molybdenum deposits is not present in this pluton, and the alteration that is present is confined to local faults and fractures.

Geochemical and petrographic evidence suggest that the pluton is a felsic differentiate from a melt which originated at a depth of …