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Cosmochemistry. The formation, composition, and structure of Earth
Published in Aleksey B. Ptitsyn, Lectures in Geochemistry, 2018
For geochemistry dealing with plate tectonics, special zones characterized by active geochemical life are of special importance. These zones are as follows: mid-oceanic ridges known as oceanic spreading centers rich in volcanoes; subduction zones where the oceanic lithosphere (or, more often, the oceanic crust) of one plate slides beneath the continental lithosphere of another plate and sinks into the mantle (in this way oxidized rocks of the surface can increase the oxidation potential of the Earth’s depths); and rift zones having a series of cracks that allow the intrusion to the surface of fresh portions of magmatic matter from the Earth’s depths. Thus, tectonic processes are a global factor affecting physicochemical conditions in the Earth’s interior.
Magmatism in the Context of the Present-Day Tectonic Settings
Published in O.A. Bogatikov, R.F. Fursenko, G.V. Lazareva, E.A. Miloradovskaya, A. Ya, R.E. Sorkina, Magmatism and Geodynamics Terrestrial Magmatism Throughout the Earth’s History, 2020
O.A. Bogatikov, V.I. Kovalenko, E.V. Sharkov, V.V. Yarmolyuk
Locally continental rifts are linked, along strike, with oceanic rifts by transitional structures. Here these structures are considered to be located at plate margins. The transitional zone of the Arabian–Indian oceanic ridge and the Red Sea oceanic spreading zone into the continental rift zones of East Africa, incorporating the Ethiopian and Kenyan continental rifts, provide an example of the connection between continental and oceanic rifts (Fig. 2.14). However, continental rifts are often intra-plate in nature and not related to plate margins as inferred from geophysical data (Western Europe, Eastern Australia, Central and East Asia, etc.).
Tackling Heterogeneity in Groundwater Numerical Modeling: A Comparison of Linear and Inverse Geostatistical Approaches— Example of a Volcanic Aquifer in the East African Rift
Published in M. Thangarajan, Vijay P. Singh, Groundwater Assessment, Modeling, and Management, 2016
The study area is located in the East African Rift region, which is found in a particular geodynamic context, related to the separation of African and Arabian plates since about 30 million years ago. The East African Rift is an active continental rift zone. It includes the Main Ethiopian Rift, which continues south as the Kenyan Rift Valley. Therefore, the volcanic formations resulting from plate tectonics outcrop over a major part of the territory. The volcanic aquifer system, which is the focus of this chapter, is located in Ethiopia (Upper Awash aquifer).
Prediction Equations for the Fundamental Period and Mode Shape of Roller Compacted Concrete Gravity Dams considering Three Dimensional Geometry Effects
Published in Journal of Earthquake Engineering, 2021
Since the beginning of the civilization, great efforts have been made in all societies with respect to the use of water resources. The efficient use of water resources for energy production has recently become even more important due to the increase of the urban population and because of global warming. In addition, fossil fuel resources have lost their popularity due to their environmental hazards as they release greenhouse gases in the production process. Consequently, clean energy technologies such as hydroelectric power plants have come into prominence in developing countries with population growth. Evidently, dams are among the most suitable structures that serve for both water storage and energy generation. Dams are constructed on rivers flowing through large or deep valleys so as to amass water in their artificially created reservoirs. Carter [2017] has stated that faults are generally localized in narrow valleys such as the San Andreas Rift Zone, separating the Pt. Reyes Peninsula to the west from mainland California to the east. Therefore, the probable construction zones for dams often lie in earthquake-prone regions. For example, 98.6% of the dams being constructed in Western China are located in high to moderate seismic hazard zones [Jackson, 2012]. A similar situation is valid for Turkey, where 90% of the dams are in earthquake prone zones. Thus, for these facilities, there is a serious risk of damage that might endanger both the health and wealth of the society. These statistics provide proof of the importance of the seismic design and assessment of dam structures.
Sedimentary characteristics and the implications of cobalt-rich crusts resources at Caiwei Guyot in the Western Pacific Ocean
Published in Marine Georesources & Geotechnology, 2020
Bin Zhao, Zhenquan Wei, Yong Yang, Gaowen He, Heng Zhang, Weilin Ma
The Magellan Seamounts, located in the oldest Jurassic seabed of the Pacific Plate, was formed by volcanic activities in the Cretaceous Period. The Magellan Seamounts sit on a large rift zone with a horizontal extension of approximately 1,200 km (Koppers et al. 2003; Lee et al. 2003, 2005; Zhao et al. 2010). Large-scale eruption of hot spots occurred in the vicinity of what is now the French Polynesia Islands within which the Magellan Seamounts were situated during 90 ∼ 120 Ma. The formations of Magellan Seamounts were inferred to have some relationship with the hot spot eruption and were subject to subsequent volcanic magmatism (Staudigel et al. 1991; Koppers et al. 1998). The Magellan Seamounts are categorized as the off-ridge type according to the effective elastic thickness of lithosphere analysis (Zhao et al. 2010). The Ogasawara Fault Zone (OFZ), developed in the Magellan Seamounts, was formed in the middle and late Jurassic Period (Nakanishi, Tamaki, and Kobayashi 1989), and divided the Western Pacific Region into two parts: the East Mariana Basin and the Peifetta Basin (Lee et al. 2005, Figure 1a). Abrams, Larson, and Shiply (1992) found (through multichannel seismic research) that the OFZ is a rift zone with a width of approximately 150 km. Koppers et al. (1998) further divided OFZ into three separate faults: OFZ1, OFZ2, and OFZ3 (Figure 1a).
Quantitative discrimination of normal fault segment growth and its geological significance: example from the Tanan Depression, Tamtsag Basin, Mongolia
Published in Australian Journal of Earth Sciences, 2018
H. X. Wang, X. F. Fu, S. R. Liu, R. Chu, B. Liu, P. P. Shi
Segments are, however, transient features in the evolution of a rift zone, as they grow and interact, they may link to form larger structures (Dawers & Anders, 1995; Kim & Sanderson, 2005; Pollard & Aydin, 1988). Therefore, the process of interaction is a necessary step in the evolution of a rift zone over a range of scales. The main basin geometries of rift systems (half-graben or graben) are controlled by major faults (Morley, 1995), with fault segment growth linkages controlling the evolution of depocentres (half-graben or graben) (Dawers & Underhill, 2000). Transfer zones are associated with such faults as transfer zones link major boundary faults that are located on opposite sides of rifts (Gawthorpe & Hurst, 1993) and can therefore cause variations in rift segment geometry (Morley, Nelson, Patton, & Mun, 1990; Rosendahl et al., 1986). As well as on basin formation and depositional patterns (Athmer & Luthi, 2011; Gawthorpe & Hurst, 1993; Morley, 1999, 2002), transfer zones also have considerable influence on hydrocarbon migration and trapping in rift systems (Coskun, 1997; Morley et al., 1990; Peacock & Sanderson, 1994).