|
Pali-Aike Crater
The Pali-Aike volcanic field is a volcanic field along the Argentina–Chile border. It is part of a family of back-arc volcanoes in Patagonia, which formed from processes involving the collision of the Chile Ridge with the Peru–Chile Trench. It lies farther east than the Austral Volcanic Zone, the volcanic arc that makes up the Andean Volcanic Belt at this latitude. Pali-Aike formed over sedimentary rock of Magallanes Basin, a Jurassic-age basin starting from the late Miocene as a consequence of regional tectonic events. The volcanic field consists of an older plateau basalt formation and younger volcanic centres in the form of pyroclastic cones, scoria cones, maars and associated lava flows. There are approximately 467 vents in an area of . The vents often form local alignments along lineaments or faults, and there are a number of maars and other lakes, both volcanic and non-volcanic. The volcanic field is noteworthy for the presence of large amounts of xenoliths in its ro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Volcanic Field
A volcanic field is an area of Earth's crust that is prone to localized volcanic activity. The type and number of volcanoes required to be called a "field" is not well-defined. Volcanic fields usually consist of clusters of up to 100 volcanoes such as cinder cones. Lava flows may also occur. They may occur as a monogenetic volcanic field or a polygenetic volcanic field. Description Alexander von Humboldt observed in 1823 that geologically young volcanoes are not distributed uniformly across the Earth's surface, but tend to be clustered into specific regions. Young volcanoes are rarely found within cratons, but are characteristic of subduction zones, rift zones, or in ocean basins. Intraplate volcanoes are clustered along hotspot traces. Within regions of volcanic activity, volcanic fields are clusters of volcanoes that share a common magma source. Scoria cones are particularly prone to cluster into volcanic fields, which are typically in diameter and consist of several tens ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magma
Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural satellites. Besides molten rock, magma may also contain suspended crystals and gas bubbles. Magma is produced by melting of the mantle or the crust in various tectonic settings, which on Earth include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Mantle and crustal melts migrate upwards through the crust where they are thought to be stored in magma chambers or trans-crustal crystal-rich mush zones. During magma's storage in the crust, its composition may be modified by fractional crystallization, contamination with crustal melts, magma mixing, and degassing. Following its ascent through the crust, magma may feed a volcano and be extruded as lava, or it may solidify underground to form an intrusion, such as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protected Area
Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the enabling laws of each country or the regulations of the international organizations involved. Generally speaking though, protected areas are understood to be those in which human presence or at least the exploitation of natural resources (e.g. firewood, non-timber forest products, water, ...) is limited. The term "protected area" also includes marine protected areas, the boundaries of which will include some area of ocean, and transboundary protected areas that overlap multiple countries which remove the borders inside the area for conservation and economic purposes. There are over 161,000 protected areas in the world (as of October 2010) with more added daily, representing between 10 and 15 percent of the world's land surface area. As of 20 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fell Cave
Cueva Fell is a natural cave and archaeological site in southern Patagonia. Cueva Fell is in proximity to the Pali Aike Crater, another significant archaeological site. Cueva Fell combined with the nearby Pali Aike site have been submitted to UNESCO as a possible World Heritage Site. Site discovery Fell's Cave was discovered by Junius Bird. It came to his attention because arrow points and flakes were found on the surface. The cave was originally called the Río Chico shelter, but was later renamed by Bird to Fell's Cave in honor of the Fell family who owned the Estancia Brazo Norte, the North Arm Station, where the cave is located. Excavation of the site began in 1936. Site formation Fell's Cave is located in the Río Chico canyon, Chile, near the Straits of Magellan and the Argentine border. This area is known as the ''Southern Patagonian Basalt Plateaus''.Markgraf, in Bird, 1988, p.196 Situated on the southeast side of what was once a river bank, it is more accurately ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archaeological Site
An archaeological site is a place (or group of physical sites) in which evidence of past activity is preserved (either prehistoric or historic or contemporary), and which has been, or may be, investigated using the discipline of archaeology and represents a part of the archaeological record. Sites may range from those with few or no remains visible above ground, to buildings and other structures still in use. Beyond this, the definition and geographical extent of a "site" can vary widely, depending on the period studied and the theoretical approach of the archaeologist. Geographical extent It is almost invariably difficult to delimit a site. It is sometimes taken to indicate a settlement of some sort although the archaeologist must also define the limits of human activity around the settlement. Any episode of deposition such as a hoard or burial can form a site as well. Development-led archaeology undertaken as cultural resources management has the disadvantage (or the ben ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Before Present
Before Present (BP) years, or "years before present", is a time scale used mainly in archaeology, geology and other scientific disciplines to specify when events occurred relative to the origin of practical radiocarbon dating in the 1950s. Because the "present" time changes, standard practice is to use 1 January 1950 as the commencement date (epoch) of the age scale. The abbreviation "BP" has been interpreted retrospectively as "Before Physics", which refers to the time before nuclear weapons testing artificially altered the proportion of the carbon isotopes in the atmosphere, which scientists must now account for. In a convention that is not always observed, many sources restrict the use of BP dates to those produced with radiocarbon dating; the alternative notation RCYBP stands for the explicit "radio carbon years before present". Usage The BP scale is sometimes used for dates established by means other than radiocarbon dating, such as stratigraphy. This usage differs from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palaeoclimatology
Paleoclimatology (American and British English spelling differences, British spelling, palaeoclimatology) is the study of climates for which direct measurements were not taken. As instrumental records only span a tiny part of Earth's history, the reconstruction of ancient climate is important to understand natural variation and the evolution of the current climate. Paleoclimatology uses a variety of proxy (climate), proxy methods from Earth science, Earth and list of life sciences, life sciences to obtain data previously preserved within Rock (geology), rocks, sediments, boreholes, ice sheets, tree rings, corals, mollusc shell, shells, and Micropaleontology#Microfossils, microfossils. Combined with techniques to date the proxies, the paleoclimate records are used to determine the past states of Earth's atmosphere. The scientific field of paleoclimatology came to maturity in the 20th century. Notable periods studied by paleoclimatologists are the frequent glacial period, glaciatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Laguna Potrok Aike
Potrok Aike is a maar in the Patagonian province of Santa Cruz, Argentina. It has a roughly circular shape and an average diameter of 2,700 metres. It is located just 2,200 metres north of the Argentina-Chile border. It is a maar lake and part of the Pali-Aike Volcanic Field The Pali-Aike volcanic field is a volcanic field along the Argentina–Chile border. It is part of a family of back-arc volcanoes in Patagonia, which formed from processes involving the collision of the Chile Ridge with the Peru–Chile Trench. .... The Potrok Aike Maar Lake Sediment Archive Drilling Project (PASADO) bore a number of ICDP drill holes for October–November 2008. The aim is to investigate the crater-filling sediments and the underlying volcaniclastic deposits. Climate Notes Lakes of Santa Cruz Province, Argentina Maars of Argentina Volcanoes of Santa Cruz Province, Argentina {{SantaCruzAR-geo-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xenolith
A xenolith ("foreign rock") is a rock fragment (country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in igneous rock entrained during magma ascent, emplacement and eruption. Xenoliths may be engulfed along the margins of a magma chamber, torn loose from the walls of an erupting lava conduit or explosive diatreme or picked up along the base of a flowing body of lava on the Earth's surface. A xenocryst is an individual foreign crystal included within an igneous body. Examples of xenocrysts are quartz crystals in a silica-deficient lava and diamonds within kimberlite diatremes. Xenoliths can be non-uniform within individual locations, even in areas which are spatially limited, e.g. rhyolite-dominated lava of Niijima volcano (Japan) contains two types of gabbroic xenoliths which are of different origin - they were formed in different temperature and ... [...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] |
Fissure Vent
A fissure vent, also known as a volcanic fissure, eruption fissure or simply a fissure, is a linear volcanic vent through which lava erupts, usually without any explosive eruption, explosive activity. The vent is often a few metres wide and may be many kilometres long. Fissure vents can cause large flood basalts which run first in lava channels and later in lava tubes. After some time, the eruption tends to become focused at one or more spatter cones. Small fissure vents may not be easily discernible from the air, but the crater rows (see Laki) or the canyons (see Eldgjá) built up by some of them are. The Dike_(geology)#Magmatic_dikes, dikes that feed fissures reach the surface from depths of a few kilometers and connect them to deeper magma chamber, magma reservoirs, often under volcanic centers. Fissures are usually found in or along rifts and rift zones, such as Iceland and the East African Rift. Fissure vents are often part of the structure of shield volcanoes. Icelan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
