A Discussion Of Ultrahigh Pressure Metamorphic Conditions : With Tectonic Models Of Formation And Exhumation

Rock Canyon is an excellent site for geologic research and has been investigated by geologists from around Utah and neighboring states. With outstanding extrusions of quartzite, tillite and limestone, it’s a favored destination for hikers, rock climbers and scientists. The quartzite is considered the most unique feature of Rock Canyon as it’s one of the few clear and distinct examples of the sedimentary processes involved with a shallow marine setting. The tillite beneath the quartzite draws attention to the ancient glaciers to the past. In conjunction with the active Wasatch Fault found at its doorstep, Rock Canyon is an important place in Utah for geologists.

Gerta Keller, professor of geosciences at Princeton University, has recently conducted research on the Chicxulub asteroid in which she analyzed new core samples taken from the asteroid site (Botzer 2004). These samples indicate that the impact that occurred at Chicxulub actually predated the mass extinction of the dinosaurs, which occurred at the Cretaceous-Tertiary boundary about sixty-five million years ago. Keller claims that the Chicxulub impact occurred approximately 300,000 years before the extinction (Keller 2004). Although previous researchers estimated that the Chicxulub asteroid was the cause of the extinctions, there had always been doubts about the exact age and size of the crater, and about the origin of the “mega tsunami deposits” that were located within the crater (Keller 2004). The focus of Keller’s recent research was on finding some answers to these questions. To do so she analyzed Cretaceous limestone, dolomite, and anhydrite deposits as the site of the Chicxulub crater (Keller 2004).

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

The Glasshouse Mountains are volcanic plugs that were originally surrounded by sandstone (MSCR, 2012). The plugs are formed of material that is more resistant to erosion than the sandstone that once surrounded it, and the plugs were revealed when the softer rock eroded away (Tourism Australia, 2015). The weathering of the sandstone is evidence to support the existence of

Schulz’s article is split into five sections. The first section introduces the readers to Chris Goldfinger, a paleoseismologist at Oregon State University. Goldfinger was at a seismology conference in Kashiwa, Japan when the 2011 Tohoku

One of the major things noticeable from the cross section is that quite a few of the rock layers are over turned, where the older rock layers are above the newer rock layers. This is seen in the contact between the Quartz Monzonite of Papoose Flat and the Campito Formation which is also a disconformity. Next there is some fault zones separating the Camptio, Poleta, and Harkless formations. We then see some more overturned layers with the contacts between Saline Spring Valley Formation (lower and upper members) above the Mule Spring Formation along with some inferred folding. With a normal fault separating the inferred folding event, we see where the overturning occurs. In between the Cambrian layers we see Tertiary Basalt nonconformities also being folded, thus with that we know that the folding event was more recent than the formation of the Basalt. Next there is a large Basalt field with a spot of the Harkless formation. Again we see over tuning as the Basalt field ends there are the Devonian and Mississippian rock Layers on top of the basalt. Separating these overturned layers from the Harkless Formation and the Saline valley Formation (upper member), which are not overturned, is a thrust fault. From this information, there was a major stress event sometime after the Tertiary period causing the rock layers to fold and overturn. And from this stress event and from the folding, normal and thrust faults are formed. Finally we see that there were alluvial and landslide deposits from the Quaternary after the folding, faulting, and over

Rarely do the geologic processes of the earth make major news headlines, but oftentimes when they do, it is because a catastrophic event has occurred and has seized public attention. This was unfortunately the case in 2013, when Florida native Jeff Bush became the victim of a tragic geologic event that left many Americans wondering if they were truly ever standing on “solid ground” (Sinkhole Swallows Florida Man). Bush, and a large portion of his suburban home, was swallowed up by a sudden sinkhole as his brother looked on in horror, trying in vain to rescue him as he was forced deeper underground. This sinkhole developed as a result of the dissolution of limestone, which is prevalent under much of Florida’s soil, and the

Lutgens, F. K. & Tarbuck, E. J. (2011). Foundations of earth science (6th ed.). Upper Saddle River, NJ: Prentice

Convection currents may bring magma to the surface at diverging boundaries. Sedimentary rocks from the ocean floor gets pushed down to the mantle at convergent boundaries. The crust soon melts and rises to the surface creating igneous rock. Typically mountain ranges are metamorphic rock, maybe our mountains are.

The first deformation event (D1) resulted in folding of volcanic rocks in the Wabigoon and Wawa subprovinces (Hooper and Ojakangas, 1971; Hudleston, 1976; Hudleston et al., 1987; Jirsa et al., 1992) and locally within the Quetico subprovince (Bauer, 1985b). Most D1 folds in the Wawa terrane in MN rarely display axial-planar cleavage, with Bauer (1985b), Hooper and Ojakangas (1971), Hudleston (1976), and Jirsa et al. (1992) having identified cleavage (S1) development locally in the Vermillion greenstone belt (Peterson, 2001). In the Wabigoon terrane, D1 resulted in recumbent folding that overturned the stratigraphic sequence and the first regional schistosity (Poulsen et al., 1980). S1 is generally subparallel to the layering in the metavolcanic and metasedimentary rocks, and a gneissic foliation attributed to D1 is well developed in gneissic domes (Czeck and Poulsen, 2010). Although D1 likely created significant thrust or oblique faulting, direct evidence

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).

Many millions of years ago the Sierra Nevada was filled with ocean water until sediments began collecting and formed mountain ranges. Over a large period of time, the mountains began to wear out and became immersed in the ocean once again. Many different particles and materials began to make layers and created the first mountain system. After the Jurassic era, “…new strata were folded and crumpled and invaded by molten granite from below” (Beatty, 1943). A large

Historic data analysis, 3D models, interpretations of geophysical data, prospecting results and a mineral potential map of the Virginia Horn (VH) project are presented. Comparison of data from the VH to analog gold-hosting rocks in Canada suggest that future exploration should focus on identifying Au-bearing veins in the Midway sequence, within 300 meters of the Pike River fault (PRF). Specifically, exploration drilling should be conducted in the buried area north of the Jola and Sopp excavation pit, where the PRF is inferred to have experienced compressional bending and a silicified/arsenopyrite-rich metasediment (?) boulder has been discovered. A high-resolution aeromagnetic (or electromagnetic) survey would enhance a geologic interpretation of the VH, but may not be necessary as currently available data justify further exploration in the high-potential area outlined in this report.

     Metamorphic rocks are pre-existing rocks that are changed by heat and pressure. The pre-existing rock is called the parent rock, or protolith. Metamorphism occurs in these rocks when the minerals become instable. There are two types of metamorphism, contact and regional. Contact is high temperature, low pressure. It is basically a massive rock that is baked. Regional is high pressure and low temperature. Strong fabric, or layering, develops from