Geology Sample Clauses

Geology. Subsidence of the Muş-Van Basin has originated through a combination of normal and strike- slip faulting and thrusting (Sengör et al., 2008). This subsidence was triggered by the gradual collapse of the magma chamber that fed the Nemrut Volcano, which is one of a series of volcanoes in the region, related to the regional tectonics associated with the closure of Tethys (Degens et al., 1984).Neotectonic evolution of Eastern Anatolia has started with the existence of peneplain geomorphology in Middle Miocene (15.97 -11.608 Ma BP). In the beginning of neotectonic evolution of Eastern Anatolia, sediments have deposited in the shallow and large lakes or in river environments synchronously. Due to tectonic forces, east-west trending inclined folds have generated and the region has become undulated. However, accelerated rate of folding exceeding the erosion resulted in generation of undulated topography. The elevation between ridges and basins increased as the drainage basin was forming (Fig.1.4).Not only the tectonic activity but also accompanied volcanism has caused variations on morphology such as asymmetry of folds, east-west trending vertical/close to vertical thrusts developed at the north-south borders of the basins such as the elongated Muş Basin (Şaroğlu and Güner, 1981; Dewey et al., 1986; Şengör et al., 2008). N-S trending tensional fissures that intersect with each other have developed parallel to the direction of compression facilitating suitable environment for possible volcanic eruptions. During the compressive phase, the calc- alkalic magmas extruded through Süphan and Ararat Volcanoes, whereas extensional phase in the region is characterized by alkalic volcanism in Tendürek and Nemrut Volcanoes.Lake Van-Muş Basin was separated into two sub-basins as consequence of eruption of Nemrut Volcano from vertical transacting tensional fissures, forming the Lake Van basin to the east (Şaroğlu and Güner,1981). Fig 1.4: A. Block diagram showing morphology and structural relations in Eastern Turkey in neotectonical period (from Şaroğlu &Güner, 1981). B.Schematic secitons showing morphology-structure relations and geomorphological evolution of Eastern Turkey (from Şaroğlu&Güner, 1981)
Geology. The WCGS site is located within the Central Stable Region of the North American Continent. This region was subjected to gentle structural uparching and down- warping during Mesozoic and Paleozoic time. These structural movements resulted in the formation of broad-scale basins and arches which have been modified locally by folding and faulting. Geotechnical investigations at the site during construction excavation have identified the presence of localized zones of penecontemporaneous deformation in the bedrock. However, the investigations have established the last age of deformation as Pennsylvanian, and there is no known macroseismic activity associated with these zones and no structural association with capable faults (Reference 1). The faulting, shearing and deformation, therefore, are noncapable as defined by Appendix A to 10 CFR 100. The surface bedrock in the site area consists of alternating layers of Pennsylvanian age shales, limestones, sandstones, and a few thin coal seams. These bedrock units dip gently to the west and northwest and have been folded locally into small-scale plunging anticlines and synclines. At the site, the Precambrian basement is present at a depth of approximately 2,500 feet. The Precambrian rocks consist of approximately 1,000 feet of sedimentary deposits which rest on a granitic basement complex. The site area has been submaturely to maturely dissected by the Neosho River and its tributaries to form flat to gently rolling uplands with a maximum topographic relief of 100 feet or less from the uplands to the valley floors. Residual soils ranging in thickness from 0 to 16 feet are developed on the Pennsylvanian strata. Quaternary alluvium reaches a thickness of approximately 25 feet in the Wolf Creek valley. Scattered Tertiary age deposits of clayey gravel cap some of the higher hills in the site area. Glacial deposits are not present at the site. The alternating Pennsylvanian strata forming the bedrock surface consist of competent rock units with a low amount of structural discontinuities in the rock mass. No major geologic features have been identified which could adversely affect the stability of subsurface materials at seismic Category I facilities. Minor geologic features, such as jointing, the zones of penecontemporaneous deformation, and the weathering profile in the rock, were considered during design and construction of facilities. Comprehensive geotechnical investigations of the site have determined the subsurface con...
Geology. Buranga hot springs emerge through sediments of Kaiso beds and peneplain gravels which consists of variable sands and gravels with irregularly distributed boulders containing sub-angular fragments. The Kaiso sediments are underlain by fine to medium-grained, poorly consolidated sands and clays; some coated with calcareous material. The structural geology of the area is characterized by the Range-front fault making a number of 250m to 1km right and left steps (Figure 12). Measurements on exposed fault surfaces in Precambrian rock east of the hot springs range 50-60°and, average 55° to NW (Hinz et al., 2017). Additional observations indicate that the NE-striking, down-to-NW normal faults intersect the range-front fault. Large landslide deposit along range-front NE of Buranga hot springs has locally concealed range-front fault traces. The main geology of Rwenzori massif which forms the Eastern escarpment of the Rift, the Bwamba fault, is metamorphic composed mainly of migmitites, amphibolites and gneisses.This type of fault pattern is typical of other normal fault step-overs and normal fault intersections along major range-front faults in the Basin and Range region in the U.S.A (e.g., Steptoe Valley, Nevada). As with other step-overs, upflow could favour one or more of the primary faults, including the primary range-front fault, the outer concealed NE-striking fault, intervening concealed faults, or any combination of these structures. Figure 12: Buranga. Structural geology map.Yellow is the landslide deposit that has concealed range-front fault traces.Buranga has the most impressive surface geothermal manifestations with a wide areal coverage in the whole of the Western Branch of the East African Rift System. They include hot springs that are close to boiling and calcareous tufas. The highest surface temperature is close to 98.7˚C and the flow is approximately 28 litres/second, an indication of high permeability (Bahati, 2018).
Geology. The McNeil property occurs within the Western Abitibi Subprovince as defined by Jackson and Fyon (1991). The property occurs in an area of Archean volcanic and lesser sedimentary rocks, intruded by Archean granitoids (Fig. 5). The Proterozoic Cobalt Embayment, consisting of Cobalt Group sediments and the Nipissing Diabase, occurs mostly to the south of the property, but tongues of Cobalt Embayment also occur both east and west of the property (Fig. 5). The regional scale Montreal River Fault passes through the northeast part of the property. Ice flow direction in this region is south to southeasterly (Bajc, 1996). Figure 5: Geology in the Vicinity of the McNeil Property. Modified after Ontario Geological Survey (2006). The bulk of the geological mapping in the area of the McNeil property has been completed by Larry Jensen of the Ontario Geological Survey (Jensen, 1992a; 1992b; 2002). Jensen’s mapping shows that the property is underlain predominantly by mafic volcanics, with lesser intermediate to felsic volcanics, intruded in the northeast corner by Archean granodiorite (Fig. 6). Northerly trending diabase dikes of the Matachewan dike swarm cut all other rock types. Jensen believes that the volcanic rocks are part of the 2702/2701 Ma Kinojevis assemblage. Stratigraphy typically strikes east and dips steeply on the property, and generally becomes younger to the south. Jensen (1992b) divides the volcanic rocks on the property into five separate units, from oldest to youngest: i) Mg-rich tholeiitic basalt; ii) tholeiitic basalt; iii) Fe-rich tholeiitic basalt, which is typically magnetic; iv) calc­alkaline mafic to intermediate volcanics; and v) minor calc-alkaline intermediate to felsic volcanics (Fig. 6). Jensen (1992a; 2002) postulates the presence of one or more east-striking faults that may have juxtaposed various elements of the stratigraphy, particularly the Mg-rich tholeiites against the Fe-rich tholeiites. Jensen (1992a) notes the presence of northwest-trending, fracture controlled zones of carbonate alteration, particularly in the tholeiitic and Fe-rich tholeiitic basalt. These zones may be cored by quartz veins, and contain inner zones of ankerite flanked by wider haloes of calcite. Up to 3% pyrite is present. Gold is associated with some of these zones (see below).
Geology. The geological history of the region underpins the current island formations and biodiversity patterns. The initial arc volcanism and island-building of the hotspot began in an area northeast of the Australian craton. This initial arc development included a broad continuous line of island-building from what is now the Huon Peninsula of mainland PNG, through to the Fiji plateau (Yan and Kroenke 1993), which has gradually migrated south. Islands have appeared and subsided, and sea levels have risen and fallen, so the current islands we see in the hotspot today are but the present state of a dynamic and continuously changing array of above-sea land masses along the migrating arcs. Young volcanic islands are composed of purely igneous rocks, while older islands, which have subsided and then been uplifted subsequently, have a composite geology, with limestone overlaying the original igneous rock, and sometimes with metamorphic rocks where plate tectonic pressure and heat have exerted an influence. The oldest rocks in thehotspot are Cretaceous lavas (Packham 1973) under limestone in the “central” geological province of the Solomons Archipelago, with the rocks being oldest to the east of this arc, especially around Guadalcanal. Nonetheless, the modern island arcs of the Solomons, Bismarcks and Admiralties have been consistently above sea level since the Eocene epoch (40 million years ago), allowing a long time for the evolution of unique biotas. As well as the complex series of old igneous, sedimentary and metamorphic rocks, the central geological province of the Solomons Archipelago is also characterized by mineral-rich ultramafic intrusions along the arc (Hackman 1973). The oldest rocks of the New Hebrides arc, which extend from Nendö through the Torres Islands to Santo and Malakula, are of the younger pre-mid Miocene Epoch (Mallick 1973). As with the oldrocks of Admiralties, Bismarcks and Solomons, the older islands of the New Hebrides arc have a significant layer of limestone overlaying an igneous basement. Young volcanic islands are present in the western Solomons and in the New Hebrides arc from Aneityum to Tinakula. Recent volcanoes also intrude through old islands, such as in Bougainville and New Britain. Some examples of active volcanism in the hotspot are the Tuluman Islands, formed in Manus province by a rhyolitic eruption in 1953-57, the active Tavurvur volcano in East New Britain, which buried Rabaul town in 1994, and the active Yasur volcano on the ...
Geology. Inspection of maps and publications of Geoscience Victoria and the Geological Society of Australia has suggested that geological succession most likely to be of concern in the Study Area and design of the Preferred Alignment comprises the Wunghnu Group alluvial deposits of Quaternary age (subdivided into the Coonambidgal Formation and the Shepparton Formation, according to relative depositional environments and ages). Other geological units that may influence design of the Project in the Preferred Alignment are the underlying Palaeocene to Miocene age Murray Group carbonate rocks and Renmark Group lacustrine sandstones, siltstones and coals, and the bedrock strata of undifferentiated Palaeozoic rocks, such as Silurian & Devonian siltstone/sandstone at depth. The Shepparton Formation of northern Victoria is described by Birch et al. as a set of highly variable sediments of fluviatile, overbank and lacustrine origin, ranging from gravels to clays, and present along the Riverine Plain. The nature of these deposits is typical of complex river systems and produces laterally interfingering, vertically and horizontally variable deposits such as sand channels flanked by layers of fine sandy clay deposited as river levees. The upper part of this deposit consists of a sheet like layer of calcareous clay 1m – 3m thick. Soils developed on the Shepparton Formation are red brown to yellow brown sodic duplex soils. The Coonambidgal Formation consists of river channel deposits with associated lakes and flood plains. These fluviatile deposits may have an overprint of an Aeolian environment, and are of late Pleistocene age. Modern rivers represent the most recent set of four such terraces of river deposits. Soils developed on these deposits are generally yellow grey in colour and poorly structured. An extract from the relevant 1:250,000 scale Geological Survey of Victoria geological map (Sheet SJ55-1, Bendigo) is presented in Appendix A. The extract includes 2 faults, the Mount William and Corop Fault denoted by the dashed red lines. These faults are well outside the Preferred Alignment and will not be encountered during construction.
Geology. The pilot area is located in Saxothuringian zone of the Bohemian Massif. The northern part of the pilot area comprises of the Vogtland syncline. The southern part belongs to the Fichtelgebirge-Erzgebirge anticline composed of crystalline complexes. These units are separated by the SW-NE striking Central Saxonian lineament. The metamorphic grade of the Variscian rocks in the pilot area increases generally from north to south. In the south, the Fichtelgebirge (Smrčiny) and Erzgebirge (Krušné hory) crystalline complexes are covered by the Cenozoic Cheb basin.The oldest high grade metamorphic rocks are of Cambrian age. Less metamorphosed phyllites and slates comprise the Ordovician Series. Cherts, chert shales and alum shales were depositied in the Silurian. The north western part of the pilot area is composed of Devonian rocks. The Lower and Middle Devonian rocks are dominated by shales, the Upper Devonian by volcanites. The Mehlteuer syncline in the NW, a part of the Vogtland syncline, consists of Lower Carboniferous greywackes and shales. The Paleozoic development in the Vogtland syncline ends with the intrusion of the Permian-Carboniferous plutonic rocks. These are the Fichtelgebirge granite and the Bergen and Kirchberg granites (Mlčoch et al., 1997). Sequences of the Cheb – Dyleň crystalline, which is also assigned to the Saxothuringian zone, crop out south of the Fichtelgebirge pluton. Its southern part consists of micaschists with andalusite, eventually sillimanite.The post-variscian platform evolution of pilot area is represented by Cheb basin. The first episode of the Cenozoic Cheb Basin evolution is related to the structural domain of the Eger (Ohře) Graben (Špičáková et al. 2000). The specific role of the Cheb Basin in the geological fabric of the NW part of the Bohemian Massif is a result of its location at the intersection of the Eger Graben structural domain, characterized by dominance of NE-striking graben systems, and the NW-striking Cheb-Domažlice Graben, a major feature in the topography of Western Bohemia. The eastern margin of the basin is defined by the Eastern Border Fault Zone, a northern termination of the Mariánské Lázně Fault Zone, which facilitated basin subsidence during later evolution. The western margin of the basin forms a transition to the zone of erosional relicts of Neogene sediments and volcanic rocks of the Fichtelgebirge Mts. in Bavaria. Locally the Cheb basin is covered by Quarternary sediments. Total thickness of Cenozoi...
Geology. The geology of the Lower Florida Keys has been described in detail by Hoffmeister (1974). Two limestone formations of marine origin are found in the Lower Florida Keys. Miami oolite overlays the Key Largo limestone formation. Miami oolite was formed during the Pleistocene era in a high energy, shallow water environment containing an abundance of calcium carbonate. On some islands (e.g., Little Pine Key), this formation is exposed and is characterized by numerous vertical solution holes. Any soils that are present are thin.