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Yanshanian
The Yanshanian movement were first recognized by Weng WH (1927,1929) in the Yansan area of China (116°-119.5°N, 40°-42°E). Since then, the Yanshanian has been used as a local term in China for tectonic events which occurred mainly during the Jurassic Period. Later, Ding WJ (1929), Huang JQ (1945,1960) and Zhao ZF (1959) extended the term to cover tectonic events which occurred throughout China during the Jurassic and Cretaceous tectonic periods. However, it was soon realized that tectonic and magmatic events in the Jurassic and Cretaceous were very different. In the Jurassic there are NNE-NE trending folds and thrusts related to transpressional tectonics, and WNW trending normal faults with some strike-slip movement and widespread calc-alkaline magmatism Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonic
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles is essential to geomorphologists to explain erosion patterns and other Earth surface features. Main types of tectonic regime Extensional tectonics Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere. This type of tectonics is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jurassic Period
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic Era and is named after the Jura Mountains, where limestone strata from the period were first identified. The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian Stage started around 183 million years ago and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined. By the beginning of the Jurassic, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of the entire Phanerozoic. The name is derived from the Latin ''creta'', "chalk", which is abundant in the latter half of the period. It is usually abbreviated K, for its German translation ''Kreide''. The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now- extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was ice free, and forests extended to the poles. During this time, new groups of mammals and birds appeared. During the Early Cretaceous, flowering plants appeared and began to rapidly diversify, becoming the dominant group of plants across the Earth b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calc-alkaline
The calc-alkaline magma series is one of two main subdivisions of the subalkaline magma series, the other subalkaline magma series being the tholeiitic series. A magma series is a series of compositions that describes the evolution of a mafic magma, which is high in magnesium and iron and produces basalt or gabbro, as it fractionally crystallizes to become a felsic magma, which is low in magnesium and iron and produces rhyolite or granite. Calc-alkaline rocks are rich in alkaline earths ( magnesia and calcium oxide) and alkali metals and make up a major part of the crust of the continents. The diverse rock types in the calc-alkaline series include volcanic types such as basalt, andesite, dacite, rhyolite, and also their coarser-grained intrusive equivalents (gabbro, diorite, granodiorite, and granite). They do not include silica-undersaturated, alkalic, or peralkaline rocks. Geochemical characterization Rocks from the calc-alkaline magma series are distinguished from rocks ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magmatism
Magmatism is the emplacement of magma within and at the surface of the outer layers of a terrestrial planet, which solidifies as igneous rocks. It does so through magmatic activity or igneous activity, the production, intrusion and extrusion of magma or lava. Volcanism is the surface expression of magmatism. Magmatism is one of the main processes responsible for mountain formation. The nature of magmatism depends on the tectonic setting. For example, andesitic magmatism is associated with the formation of island arcs at convergent plate boundaries while basaltic magmatism is found at mid-ocean ridges during sea-floor spreading at divergent plate boundaries. On Earth, magma forms by partial melting of silicate rocks either in the mantle, continental or oceanic crust. Evidence for magmatic activity is usually found in the form of igneous rocks formed from magma. Convergent boundaries Magmatism is associated with all stages of the development of convergent plate boundaries, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fault (geology)
In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic forces, with the largest forming the boundaries between the plates, such as the megathrust faults of subduction zones or transform faults. Energy release associated with rapid movement on active faults is the cause of most earthquakes. Faults may also displace slowly, by aseismic creep. A ''fault plane'' is the plane that represents the fracture surface of a fault. A ''fault trace'' or ''fault line'' is a place where the fault can be seen or mapped on the surface. A fault trace is also the line commonly plotted on geologic maps to represent a fault. A ''fault zone'' is a cluster of parallel faults. However, the term is also used for the zone of crushed rock along a single fault. Prolonged motion along closely spaced faults can blur the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geology Of China
The geology of China (or the geological structure of the People's Republic of China) consists of three Precambrian cratons surrounded by a number of orogenic belts. The modern tectonic environment is dominated by the continued collision of India with the rest of Asia starting 40–50 million years ago. This has formed the Himalaya and continues to deform most of China. China has vast mineral reserves, a significant earthquake risk in its Western regions and rare isolated active volcanoes throughout the country. Many geological concepts were discovered very early in China's history. However, it was not until the adoption of European natural science in the late 19th century that geology became a science in China. Landscape evolution The geomorphology of China can be divided into several parts. The historical centre of Chinese culture is on the loess plateau, the world's largest Quaternary loess deposit, and on the alluvial lands at the east of it. The alluvial East China pl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
