Geology Of The Oaks Belt

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).

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.

Weathering, geologic processes such as erosion, and climatic shifts allow for this immense desert ecosystem to continually evolve and change which has taken place for millions of years. This geologically wealthy environment is composed of alternating flat-lying layers of soft and hard deposits of mostly sedimentary rocks. Interchanging slopes and cliffs along the landscape helped form these layers of rock which can be seen fully exposed in areas of the mesa. Deposition of this landscape mainly occurred during the Permian, Pennsylvanian, Triassic and Jurassic time periods. The assortment of warm hues of sandstone were produced by varying levels of iron oxide minerals during formation.

It is subdivided, from north to south, into the Wabigoon, Quetico, Wawa, and Minnesota River Valley (MRV) subprovinces (Figure 2, Jirsa et al., 2011). The Wabigoon subprovince is composed of greenschist facies mafic volcanic and volcaniclastic rocks intruded by granitoid batholiths. Algoma-type iron formation and small mafic intrusions are also common in this terrane. Amphibolite to greenschist facies rocks comprise the majority of the Quetico subprovince. In Minnesota, it occurs as a westward thinning belt of relatively homogenous metasediments and interstratified migmatites. The Wawa subprovince is composed of greenschist facies mafic and felsic volcanic rocks, granitoid batholiths and subsidiary Algoma-type iron formation. The MRV is the oldest of the terranes, and is characterized by granulite facies gneissic domes (Jirsa et al., 2011). Although not included as part of this study, a comprehensive overview of the mineral potential of the Vermillion Greenstone (Wawa Terrane in MN) was provided by Peterson

Majority of the Canadian Shield is made up of metamorphic and igneous rocks. The rocks

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

One piece of this history is the subsurface Paleozoic rocks. Paleozoic rocks are for the most part hidden in the Park despite being in the Colorado Plateau, which is likely due to both erosion, and it being buried in other various rocks. Next is the deposition of the Moenkopi Formation during the early Triassic time period. When North America was still apart of Pangea, the area that was the Colorado Plateau was located within close range of the Equator. 300-600 feet of sand and mud were accumulated during this time, with marine life being included which tells Geologists that the sea sometimes was in the area. The climate at the time was warm, with varying times of humid and dry spells. There is very few beds of the Moenkopi Formation left in the area once again due to erosion. Third is the deposition of the Shinarump Member of the Chinle Formation. This basal conglomerate was deposited on top of the Moenkopi Formation. It is made up of gravel and sand, which indicates that there was water depositing it. The Shinarump Member also averages between 35-50 feet thick. Next in the geological history is the deposition of Chinle beds later in the Triassic time period. When the sea regressed to the west of the area, a large plain was left behind. As the climate changed, so did the environment. Soon grasslands and marshes began to form in the area. During this time hundreds of feet of shaly material accumulated which formed both the Lower Petrified Forest Member and the Upper Petrified Forest Member. In some parts, these two members are separated by the Sonsela Sandstone Member, composed of the most petrified wood compared to all other rock units featured in the Park. The Owl Rock Member is at the top of the Chinle Formation, and completes it. Near the end of the Triassic time period, tectonic activity was occurring heavily in the Arizona basin. In the western sea at this time a chain of volcanoes erupted,

These rocks grade abruptly northward into a marine geo-synclinal facies up to as much as 6,000 feet thick in the Las Vegas sub-basin. The Magdalena Group is missing from the Cimarron arch, but it most likely present in the western part of the northern Raton Basin. Orogenic debris of the Sangre de Cristo Formation of Pennsylvanian and Early Permian age was derived mainly from the San Luis uplift, filled the Rowe-Mora and Central Colorado basins, and lapped onto Precambrian rocks of the other bounding uplifts. The Sangre de Cristo Formation is 700-3,500 feet thick at the south, and 6,000-9,500 feet thick at the north (Baltz 1965).

1. The geology of Ontario is divided into three layers of rock. The first layer, Precambrian Canadian Shield rocks, is composed of mainly igneous and metamorphic rocks from the Precambrian Eon. This layer is the eldest at approximately 3-0.8x109 years old and is therefore the bottom-most layer (L). Although this layer is largely found in the Canadian Shield region of Ontario, glacial erratics from the Precambrian layer can be found at the Don Valley Brickyard (L). In the GTA, younger sediments and rocks cover the Precambrian rock layer (L). The second layer is Paleozoic rock, composed of sedimentary rocks
. It was deposited 600-400 million years

The Blue Ridge Mountains sit within a larger tectonic area that includes part of the smoky mountains and Appalachian mountain chain. The Blue Ridge Mountains sit upon a large thrust plate area that has experienced repeated movement in the orogeny process as the Appalachians were built. This process occurred during the Proterozoic to the Paleozoic period (Tectonic Setting of the Southern Appalachians). Evidence of the faulting includes sedimentary zones at the end of the thrust. Within the thrust areas is high-grade metamorphic rocks and some igneous rocks from intrusion during collision events (Hatcher, R). Evidence of the intrusions are the dikes which can be seen and the large granite facies throughout the area (Grant, Willard).

Many petroglyphs, animal fossils, and artifcats are visible throughout this formation in addition to the exposed, petrified logs. Chinle is broken up into smaller members and from oldest to youngest they are- Mesa Redondo Member, Blue Mesa Member, Sonsela Member, Petrified Forest Member, and Owl Rock Member. Each member is made up of unique materials that are responsible for their remarkable color. The Paleozoic sandy conglomerate and siltstone of Mesa Redondo Member is red, yellow and purple and was once part of the river’s floodplain before its deposition between 225-227 million years ago. The Blue Mesa Member consists of multicolored mudstone cobbles in blue, green, grey, and purple colors and dates to 220-225 million years ago. These older members make up the badlands of Petrified Forest and display their colorful banding. The 216 million year old Sonsela member includes a few smaller bedded areas with brown cross-bedded sandstones, more multicolored mudstones in blue, grey, and purple, white and grey sandstone beds, and white cross-bedded sandstone conglomerates with an assortment of sizes for cobbles. The Petrified Forest member, an area within the Painted Desert feature, is approximately 213 million years old with thick red and brown mud and sandstone layers. As one would guess, this member contains a good majority of the fossilized wood segments and uranium-bearing minerals that are often present with such organic matter as trees and logs. At 205 million years old, the youngest Owl Rock Member represents an area where there had once been a dry inland lakebed, leaving observable trace minerals from the evaporation process. The colors found here are typically light to dark red with orange and white, resulting from the mudstone littered with thin layers of limestone throughout. The wide variety of color

Lacustrine deposits at profiles 13-6 and 13-5, located within the maar crater near its eastern wall, occur at elevations of 1921.5 ± 0.2 m and 1919.4 ± 0.2 m, respectively. The profile 13-6 deposits are ~25 m higher than the modern lake level (1895.9 m) and ~10 m higher than highstand deposits at ~1911 m previously documented and radiocarbon dated by Bradbury (1967) on the northeast flank of the west cinder cone. The ~1921.5 m lacustrine deposits in the eastern part of the crater thus appear to represent the highest documented level of ZSL. Although Bradbury (1967:Figure 13) apparently also documented the same lacustrine highstand deposits as we did at profiles 13-5 and 13-6, it appears he mapped them ~50 m west (and downslope) of their actual location. We were able to more accurately plot their location and elevation using a

The Carolina Slate Belt is a gold rich strip that runs from Virginia through both North and South Carolina and ends up in Georgia. The slate is made up of low grade metamorphosed volcanic and slaty cleavages. The mountainous Piedmont of North Carolina isolates the Triassic-Jurassic rift basin and the level Coastal Plain from the hilly Blue Ridge and Appalachians The Coastal Plain comprises of Mesozoic-Cenozoic sediments created when the North Atlantic Ocean got to be more wider, and the Triassic-Jurassic rift basin was filled by sedimentary rocks washed into the rift formed during the opening of the Atlantic Ocean. The Raleigh Belt and Eastern Slate Belt contain rocks like those of the Piedmont. These, however, are

Depending on what the sedimentary rock is formed by, determines whether is known as clastic or chemical. Clastic rocks are composed of particles from weathering. They are then sorted by grain size, gravel being the largest and clay being the smallest. A few examples would be sandstones and shales. Chemical sedimentary rocks are biochemical, and contain ions in the solution from weathering. These are also further classified. First you have limestone, which can be either organic or inorganic. An example would be fossiliferous or chalk. Next is dolostone, and it is formed from dolomite. Chert is next; and can be organic or inorganic also. Flint and jasper are some examples of chert. Rock salt and gypsum are what are known as evaporites. These form from the evaporation of saline waters in an arid environment. Finally there is coal, which is organic and forms from buried plant remains and carbon. There is one more type of rock that is classified the same way as the previous two.