|
Andean Orogeny
The Andean orogeny () is an ongoing process of orogeny that began in the Early Jurassic and is responsible for the rise of the Andes mountains. The orogeny is driven by a reactivation of a long-lived subduction system along the western margin of South America. On a continental scale the Cretaceous (90 Ma) and Oligocene (30 Ma) were periods of re-arrangements in the orogeny. The details of the orogeny vary depending on the segment and the geological period considered. Overview Subduction orogeny has been occurring in what is now western South America since the break-up of the supercontinent Rodinia in the Neoproterozoic. The Paleozoic Pampean, Famatinian and Gondwanan orogenies are the immediate precursors to the later Andean orogeny.Charrier ''et al''. 2006, pp. 113–114. The first phases of Andean orogeny in the Jurassic and Early Cretaceous were characterized by extensional tectonics, rifting, the development of back-arc basins and the emplacement of large batholiths. Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Cretaceous
The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 Megaannum#SI prefix multipliers, Ma to 100.5 Ma. Geology Proposals for the exact age of the Barremian–Aptian boundary ranged from 126 to 117 Ma until recently (as of 2019), but based on drillholes in Svalbard the defining Anoxic event#Cretaceous, early Aptian Oceanic Anoxic Event 1a (OAE1a) was dated to 123.1±0.3 Ma, limiting the possible range for the boundary to c. 122–121 Ma. There is a possible link between this anoxic event and a series of Early Cretaceous large igneous provinces (LIP). The Ontong Java Plateau, Ontong Java-Manihiki Plateau, Manihiki-Hikurangi Plateau, Hikurangi large igneous province, emplaced in the South Pacific at c. 120 Ma, is by far the largest LIP in Earth's history. The Onto ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atacama Fault
The Atacama Fault Zone (AFZ) is an extensive system of faults cutting across the Chilean Coastal Cordillera in Northern Chile between the Andean Mountain range and the Pacific Ocean. The fault system is north–south striking and runs for more than 1100 km North and up to 50 km in width through the Andean forearc region. The zone is a direct result of the ongoing subduction of the Eastward moving Nazca plate beneath the South American plate and is believed to have formed in the Early Jurassic during the beginnings of the Andean orogeny. The zone can be split into 3 regions: the North, Central and South. Tectonic history and formation The AFZ has gone through periods of inactivity and reactivation since its inception in the Cretaceous. The fault series was formed through a complex series of tectonic regimes dating back to the Early Jurassic, when the Andean back-arc basin separated from the Pacific Ocean. Intra-arc ductile deformation occurred in the Late Jurassic, cr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South Atlantic Ocean
The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the Age of Discovery, it was known for separating the New World of the Americas (North America and South America) from the Old World of Afro-Eurasia (Africa, Asia, and Europe). Through its separation of Afro-Eurasia from the Americas, the Atlantic Ocean has played a central role in the development of human society, globalization, and the histories of many nations. While the Norse colonization of North America, Norse were the first known humans to cross the Atlantic, it was the expedition of Christopher Columbus in 1492 that proved to be the most consequential. Columbus's expedition ushered in an Age of Discovery, age of exploration and colonization of the Americas by European powers, most notably Portuguese Empire, Portugal, Spanish Empire, Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plate Tectonics
Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by Earth science, geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called ''tectonics''. Tectonic plates also occur in other planets and moons. Earth's lithosphere, the rigid outer shell of the planet including the crust (geology), crust and upper mantle, is fractured into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary (or fault (geology), fault): , , or . The relative movement of the plates typically ranges from zero to 10 cm annu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Erosion
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, transports it to another location where it is deposit (geology), deposited. Erosion is distinct from weathering which involves no movement. Removal of rock or soil as clastic sediment is referred to as ''physical'' or ''mechanical'' erosion; this contrasts with ''chemical'' erosion, where soil or rock material is removed from an area by Solvation, dissolution. Eroded sediment or solutes may be transported just a few millimetres, or for thousands of kilometres. Agents of erosion include rainfall; bedrock wear in rivers; coastal erosion by the sea and Wind wave, waves; glacier, glacial Plucking (glaciation), plucking, Abrasion (geology), abrasion, and scour; areal flooding; Aeolian processes, wind abrasion; groundwater processes; and Mass wastin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mountain Building
Mountain formation occurs due to a variety of geological processes associated with large-scale movements of the Earth's crust (List of tectonic plates, tectonic plates). Fold (geology), Folding, Fault (geology), faulting, Volcano, volcanic activity, igneous intrusion and metamorphism can all be parts of the Orogeny, orogenic process of mountain building. The formation of mountains is not necessarily related to the structural geology, geological structures found on it. From the late 18th century until its replacement by plate tectonics in the 1960s, geosyncline, geosyncline theory was used to explain much mountain-building. The understanding of specific landscape features in terms of the underlying tectonics, tectonic processes is called ''geomorphology, tectonic geomorphology'', and the study of geologically young or ongoing processes is called ''neotectonics''. Types of mountains There are five main types of mountains: volcanic, fold, plateau, fault-block, and dome. A more de ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (engineering)
In engineering, deformation (the change in size or shape of an object) may be ''elastic'' or ''plastic''. If the deformation is negligible, the object is said to be ''rigid''. Main concepts Occurrence of deformation in engineering applications is based on the following background concepts: * ''Displacements'' are any change in position of a point on the object, including whole-body translations and rotations ( rigid transformations). * ''Deformation'' are changes in the relative position between internals points on the object, excluding rigid transformations, causing the body to change shape or size. * ''Strain'' is the ''relative'' ''internal'' deformation, the dimensionless change in shape of an infinitesimal cube of material relative to a reference configuration. Mechanical strains are caused by mechanical stress, ''see stress-strain curve''. The relationship between stress and strain is generally linear and reversible up until the yield point and the deformation is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Aus ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithosphere
A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time scales of up to thousands of years or more. The crust and upper mantle are distinguished on the basis of chemistry and mineralogy. Earth's lithosphere Earth's lithosphere, which constitutes the hard and rigid outer vertical layer of the Earth, includes the crust and the lithospheric mantle (or mantle lithosphere), the uppermost part of the mantle that is not convecting. The layer below the lithosphere is called the asthenosphere, which is the weaker, hotter, and deeper part of the upper mantle that is able to convect. The lithosphere–asthenosphere boundary is defined by a difference in response to stress. The lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oceanic Crust
Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumulates. The crust lies above the rigid uppermost layer of the mantle. The crust and the rigid upper mantle layer together constitute oceanic lithosphere. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometers thick; however, it is denser, having a mean density of about 3.0 grams per cubic centimeter as opposed to continental crust which has a density of about 2.7 grams per cubic centimeter. The crust uppermost is the result of the cooling of magma derived from mantle material below the plate. The magma is injected into the spreading center, which consists mainly of a partly solidified crystal mush derive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batholith
A batholith () is a large mass of intrusive rock, intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate composition, intermediate rock types, such as granite, quartz monzonite, or diorite (see also ''granite dome''). Formation Although they may appear uniform, batholiths are in fact structures with complex histories and compositions. They are composed of multiple masses, or ''plutons'', bodies of igneous rock of irregular dimensions (typically at least several kilometers) that can be distinguished from adjacent igneous rock by some combination of criteria including age, composition, texture, or mappable structures. Individual plutons are solidified from magma that traveled toward the surface from a zone of partial melting near the base of the Earth's crust. Traditionally, these plutons have been considered to form by ascent of relative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
