Rainy Lake Wrench Zone ( Rlwz )

The youngest of these rocks are dated at about 220,000 years ago. Rhyodacties and quartz latites in the modern caldera area extruded from about 320,000 years ago to 260,000 years ago, and then silica-rich rhyolites at Glass Mountain northeast of the caldera erupted from about 210,000 years ago to 80,000 years ago. The scattered distribution of the initial mafic eruptions indicates that they were erupted from the mantle, while the slightly younger domes and flows were from a deep-crustal source. The youngest rhyolite eruptions erupted at the northeast rim of the caldera at Glass Mountain and were the first activity of the silicic Long Valley magma chamber (Bailey, et. al., 1989).

Sims et al. (1989) synthesized U-Pb zircon ages for the Pembine-Wausau terrane. Sims concluded that the volcanic rocks were generated from around 1889 to 1860 Ma as island arcs and closed back-arc basins above the south-dipping subduction zone (Niagara fault zone). Granitoid rocks in the terrane, emplaced from around 1870 to 1760 Ma, are mainly granodiorite and tonalite but include gabbro, diorite, and granite. These developed as island arcs above the Eau Pleine shear zone. The Niagara fault zone contains a relict ophiolite, suggesting that the rocks in the Pembine-Wausau terrane probably accumulated on

Next, we can see that the rock displays a subtle porphyritic texture with plagioclase comprising the phenocrysts. The overall texture of the surrounding groundmass is granoblastic equigranular. Under thin section we also see a weakly defined foliation evidenced in the preferential alignment of actinolite grains and to a lesser extent chlorite grains. Undulose extinction is also observed in quartz indicating the rock was subject to deformation. The normalized quartz, alkali-feldspar, and plagioclase (QAP) values of this rock indicate that it is classified as a grano-diorite according to the IUGS QAPF classification system which is consistent with the hand sample interpretation.

This study classifies the two granites under one unit named the Kilbride Granite, however, the research, which uses both radiometric dating and composition analysis, identifies them as two compositionally separate units with different ages. On the other hand, it is not wrong to say that the granites were related as they are the two latest forming members of the Eastern Red Hills complex. (Bell and Harris, 1986)

In the 1920’s, geologist J. Harlen Bretz challenged the current concept of how various geological formations happened. At the time, geologists believed in uniformitarianism, which meant that geologic change in the past resulted from the same slow, steady processes at work today.

The Wabigoon Subprovince is part of the Superior Province, an Archean age craton composed of E-NE trending granite-greenstone and metasedimentary terranes that span from western MN to northern Quebec. In Canada, the Neoarchean Wabigoon subprovince hosts numerous precious and base metal deposits, including the Sturgeon Lake VMS deposits and Rainy River and Hammond Reef gold deposits (Figure 2). Historically considered moderately to weakly prospective for hosting VMS deposits due to inferred shallow marine conditions and relatively low temperature felsic volcanic rocks (Lesher et al., 1986; Gaboury and Pearson, 2008), the observation that many Wabigoon- hosted gold deposits may exhibit characteristics r of epithermal deposits

A period of volcanism resulted in igneous intrusions within the Raton Basin-Sierra Grande Uplift Province that was sourced from the upper mantle about 26. 6 billion years ago and is associated with parallel dikes and sills (Higley, 2007). Igneous rocks are common within the Raton Basin and include Tertiary dikes and sills that range in age from 6.7 to 29 5 million years ago (Flores and Bader, 1999). One of the main differences between dikes and sills is that dikes are longer lived magma conduits and sills are features that form when magma is in neutral buoyancy with the surrounding rock (Rooper et al., 2006). These volcanic events are associated with hydrothermal alteration of coal within the basin (Higley, 2007).

In addition, per my knowledge none of the western US geologists have documented passive margin deposits as young as of upper Paleozoic age or younger. Therefore, Hildebrand (2009, 2013) hypothesis faces deficiency to explain the thrusting of Roberts Mountain and the emplacement of the Proterozoic rocks over the rocks of Lower Paleozoic age.

The Slave Structural Province is a unique and distinctive Archean craton in the northwest Canadian Shied, which is indicated by its rock types, deposits and structures (Padgham,1992). The Slave province covers much smaller than (1/10) that of Superior Province, which is about 213 000 km2. The supracrustals (33% of Slave province) consist of 70-80% of greywacke- mudstone and approximately 20% of volcanic rocks, which is high in SiO2 (felsic to intermediate) (Padgham,1992). There are abundant mineral deposits in the Slave Province: gold deposits, rare-element-rich pegmatite and zinc-lead-silver-concentrated volcanogenic massive sulfides (VMS), which differ from the high contents of copper-zinc-gold in the Superior Province (Padgham & Fyson, 1992).

The Raton-Clayton volcanic field is about 20 000 km2 in size, and has been active periodically for the past 9 million years. The area is filled with peaks, cones, and lava-capped mesas. The mesas developed as lava flowed into valleys and depressions, cooled off and formed a resistant top layer over sedimentary rocks. As the surrounding rock eroded, the lava protected the underlying stratigraphy from erosion. This caused todays topography, where that which was once the lowest point, is now the highest. There is some disagreement over why the volcanic field is here, one possible cause is that it is near the end of the Jemez Lineament, which has numerous volcanic centers along its reach, possibly

As the PFR is considered to be a 2nd order splay off the Fayal Fault (FF), most holes in the VH were drilled outside the 300 meter buffer that is prospective for hosting significant gold deposits. Although drill holes in the 2009 and 2010 campaigns did intercept significant Au mineralized zones 800+ meters from the PFR, currently available data suggest these mineralized zones are likely small ore shoots that will not constitute a large (+1 Moz) and mineable

The age of the thrusts and the areas where they occurred are dated to varying ages with the oldest tectonic action dated 595 million years ago to the youngest at 265 million years ago (Hatcher, R). The thrust faults in the center of the Blue Ridge area would appear to have the highest grade of metamorphism while the faults to the edge have the lowest grade metamorphism or sedimentary features (Hatcher, Robert, and Arthur Merschat.). this is easily seen because the area where the

About 7,700 years ago, Mount Mazama erupted on itself after building upon itself and reaching an impressive height of 12,000 feet. The aftermath of the collapse left a crater more than 2000 feet deep and 6 miles wide (Reichmann)! The rocks and minerals from the Mount Mazama

At the beginning of the Tertiary, there is a layer of andesite breccia -a fast cooling extrusive rock that has not traveled far from its original deposition. This indicates a volcanic depositional environment. This formation was then intruded by intrusive slower cooling rocks that create a noncomformity between it and the Walker formation. The tuff breccia in the Walker formation is consistent with the same depositional environment as the andesite breccia formation as they are both extrusive rocks. It is possible that there was an eruption from a volcano that deposited the highly viscous andesite rocks followed by slower falling ash, which was then

Tempe Quadrangle only has rock of Precambrian and Cenozoic Era. First, the oldest rock, metarhyolite, was deposited came from metamorphosed rhyolitic ashes and lava flows. Two different granite intrude the metarhyolite; They are the Tovrea Granite and Camelback Granite. This fist granite is rich in biotite