Geological Setting
The Cape Granite Suite formed about 560-520 Ma during the Saldanian orogeny which occurred between 780 to 510 Ma (Harris & Vogelli, 2010; Villaros, Stevens & Buick, 2009). This orogeny formed as a result of the convergence of the Rio de la Plata and Kalahari cratons during the formation of Gondwanaland (Harris & Vogelli, 2010). The granitoids of the CGS were intruded into the three terranes of the metasedimentary and metavolcanic Malmesbury Group which are divided by distinct north-west trending shear zones (Scheepers, 2000). These terranes include the southwestern Tygerberg terrane, Swartland terrane at the centre and Boland terrane to the north east (Fig. 1) (Scheepers, 1995).
The Saldania mobile belt comprises of structural features that are characterised by the occurrence of ductile and dextral strike-slip shearing that preceded the orogenic event which occurred approximately 600 Ma (Scheepers, 2000). This led to the first phase of magmatism about 560-540 Ma (Scheepers & Nortje, 2000). This phase involved the syn- to post tectonic S- type granites intruding the Tygerberg terrane (Scheepers & Nortje, 2000). The second phase involved the intrusion of the I-type granites. Like the S-type granites, the strike-slip movement affected the intrusion of the I- type granitoids which occurred along the Colenso fault in the Swartland and Boland terranes about 540- 520 Ma (Scheepers, 1995; Scheepers & Nortje, 2000). The intrusion of the post-orogenic to anorogenic A- type granites occurred at approximately 520- 500 Ma, representing the third phase of magmatism (Scheepers & Nortje, 2000). They are intrusive in the Tygerberg and Swartland terranes (Scheepers & Nortje, 2000). The final phase of magmatism is often negle...
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...ircon ages of the Cape Granite Suite: implications for the magmatic evolution of the Saldania Belt.", South African Journal of Geology, vol. 105, no. 3, pp. 241-256.
Scheepers, R. & Nortjé, A. 2000, "Rhyolitic ignimbrites of the Cape Granite suite, southwestern Cape province, South Africa", Journal of African Earth Sciences, vol. 31, no. 3, pp. 647-656.
Scheepers, R. & Ozendaal, A. 1995, "Phosphorus as a typological and mineralization potential indicator: the Cape Granite Suite of the Saldania belt as a case study", Journal of African Earth Sciences, vol. 21, no. 1, pp. 127-140.
Villaros, A., Stevens, G., Moyen, J. & Buick, I.S. 2009, "The trace element compositions of S-type granites: evidence for disequilibrium melting and accessory phase entrainment in the source", Contributions to Mineralogy and Petrology, vol. 158, no. 4, pp. 543-561.
Lithologically the Kimmeridge Clay Formation can be subdivided into four units (Figure 2), despite of beds at the base of the succession are poorly exposed. However, in contrast, the units from mid-eudoxus Zone to the top of the formation that are well seen in the Formation. At the base of the formation until the eudoxus Zone, the strata are made up almost entirely of bioturbated shelly clays and in between beds, horizons of oil and bituminous are present. The upper part of the Eudoxus Zone until the upper Pectinatus Zone the composition is kerogen-rich mudstones and coccolith limestone.
The third alluvial deposition consists of sand, silt and minor inter-bedded gravel, and again indicates Brimbank Park’s changing geology over time. (Geological map of Victoria, 1973). These deposits, as well as a nearby fault suggest volcanic activity 5-1.6 million years ago, which explains the olivine basalt (fig. 2) deposits which date back to to the Silurian and Tertiary period.
When standing on top of the butte, the rock that makes up a majority of the area is quartzite. Quartzite is a metamorphic rock that forms when existing rock is exposed to extreme amounts of heat and pressure (4). The quartzite that is found on Kamiak Butte was formed sometime around 1.47 to 1.4 billion years ago during the Paleozoic period of the Precambrian era. Many of the metamorphic rocks have been fractured and decayed due to physical and chemical weathering, but because quartzite consists of one of the strongest minerals quartz...
The central belt of the Franciscan Complex represents older and more metamorphosed units of rock best characterized as a melange. Blocks of graywacke, greenstone, chert, limestone, and blueschists are sheared and thrust upon one another in a choatic mix (Isozaki and Blake, 1994). In contrast to the coastal belt, metamorphism is higher in grade here and dominated by pumpellyite which formed within the matrix of graywacke (Hagstrum and Murchey, 1993). The mixing of these units makes a stratigraphic subdivision difficult but analysis of the graywacke slabs indicates that the depositional environment was also deep sea, near to the continent. Turbidity currents in this environment deposited much of the sediment in both the coastal and central belts.
Tarbuck E., Lutgens F., Tasa D., 2014, An Introduction to Physical Geology, 5th Ed, Pearson Education, Upper Saddle River, New Jersey.
Stone Mountain rises in sharp contrast to the surrounding flat, rolling landscape creating a geomorphic monadnock. Geologists appear to have consensus of the volcanic origins and underground formation of t...
and Metamorphic rocks can be found. There are also a lot of crusted plates, and violent
"Sedimentary Rocks." Backyard Nature with Jim Conrad. N.p., 18 May 2015. Web. 25 Oct. 2015.
During the Late Cretaceous a period of mountain building occurred along the west coast of North America. This is called the Laramide orogeny that started the Rocky Mountains growth about seventy-five million years ago. The Laramide orogeny was different from orogenies that had happened before hand. What caused the Laramide Orogeny is uncertain but there are many theories about what caused it. One big thing to better understand the Laramide orogeny is the theory of Uniformitarianism.
System and the Basalts of the Newark Basic, New Jersey, U.S.A.: Journal of Geology, p.
Since California had previously been mentioned, it is a great place to begin explaining the complex geological impacts starting with the San Andreas Fault. The San Andreas is what geologists know as a strike-slip fault, meaning that when two pl...
Riley, C.M. "Lahars." Geological and Mining Engineering Sciences. Michigan Tech. Web. 6 Feb. 2010. .
The Precambrian Shield Rocks found in the Brickworks was formed in an ancient sea more than 1.4 billion years ago. Over many years, the heat and pressure from plate tectonics slowly pushed the land into a mountain chain. During the Ordovician period (around 470- 448 million years ago), the mountain chains This layer of shale and limestone is called the Georgian Bay
...se two tectonic plates generated intense friction and pressure that generated enough heat to melt rocks. The descent of denser oceanic Farallon Plate into the asthenosphere produced magma that was made from basalt or andesite. Which is dark colored rocks with little silica. The buoyant magma pushed through the silica-rich continental crust, partially melting the crust that it moved though, and becoming more granitic in composition. About 100 million years ago, the granitic magma pooled at depths of only 2 to 5 miles beneath the surface (United States of America). The granitic terrain that makes up the Sierra, was once thought to have only local variations but was produced from one large mass of rock. It has been discovered however that hundreds of intrusions caused the variations in the granite that is displayed in Yosemite and in the Sierra Nevada range (Huber).
Stephen .G,Malcolm.W, Guy H,(2014), GEOL20001 The Geology of Southeast Australia, School of Earth Sciences, University of Melbourne, pg. 23-25