Stratigraphy of small shield volcanoes on Venus
... Received 20 February 2004; revised 7 June 2004; accepted 14 July 2004; published 5 October 2004. ...
... Received 20 February 2004; revised 7 June 2004; accepted 14 July 2004; published 5 October 2004. ...
The Mechanism of Intrusion of the Inyo Dike, Long
... mechanically most favorable orientation, regardless of their origin. The N07' W alignment of the young Jnyo Domes chain appears lUlaffected by two large, preexisting tectonic features. The first large structure is the active system of normal faults that bound the Sierra Nevada block. One of these, t ...
... mechanically most favorable orientation, regardless of their origin. The N07' W alignment of the young Jnyo Domes chain appears lUlaffected by two large, preexisting tectonic features. The first large structure is the active system of normal faults that bound the Sierra Nevada block. One of these, t ...
Venus`s shield terrain - University of Minnesota Duluth
... 1997), the mechanism(s) responsible for lowland volcanism remain mostly elusive. Lowland resurfacing is typically attributed to emplacement of extensive flood lava (e.g., Banerdt et al., 1997). This supposition forms the basis for two related hypotheses: catastrophic resurfacing (Strom et al., 1994) ...
... 1997), the mechanism(s) responsible for lowland volcanism remain mostly elusive. Lowland resurfacing is typically attributed to emplacement of extensive flood lava (e.g., Banerdt et al., 1997). This supposition forms the basis for two related hypotheses: catastrophic resurfacing (Strom et al., 1994) ...
Petrogenesis and correlation of the mid
... caldera and was active from approximately 35 to 26 Ma (Lipman, 1982). Volcanism began with a period of intermediate composition eruptions which then changed to silicic ash flows from caldera centers at ~30 Ma, shortly after the eruption of the rhyolitic UBT. The Thirtynine Mile volcanic field lies t ...
... caldera and was active from approximately 35 to 26 Ma (Lipman, 1982). Volcanism began with a period of intermediate composition eruptions which then changed to silicic ash flows from caldera centers at ~30 Ma, shortly after the eruption of the rhyolitic UBT. The Thirtynine Mile volcanic field lies t ...
View paper
... and furthermore that this difference is in majority of cases within 0-5%. The samples are subdivided further according to their alteration zone identity. Although a broad alteration range within each zone is observed, the main bulk of the samples within each of them shift to the right with higher al ...
... and furthermore that this difference is in majority of cases within 0-5%. The samples are subdivided further according to their alteration zone identity. Although a broad alteration range within each zone is observed, the main bulk of the samples within each of them shift to the right with higher al ...
calcalk13
... The term calc-alkaline has persisted for volcanic suites characteristically occurring in volcanic arcs associated with zones of subduction. This ingrained assumption is, however, dangerous because contamination combined with crystal fractionation can produce a spectrum of lava compositions that exhi ...
... The term calc-alkaline has persisted for volcanic suites characteristically occurring in volcanic arcs associated with zones of subduction. This ingrained assumption is, however, dangerous because contamination combined with crystal fractionation can produce a spectrum of lava compositions that exhi ...
Annex 2：Geological Heritage
... During 270,000 to 90,000 years, gigantic pyroclastic flow eruptions of andesitic to rhyolitic magma occurred four times in the volcanic field and formed the Aso caldera, 25 km north-south and 18 km east-west. Basement rocks of Aso volcanoes consist of Quaternary Pre-Aso volcanic rocks, Cretaceous gr ...
... During 270,000 to 90,000 years, gigantic pyroclastic flow eruptions of andesitic to rhyolitic magma occurred four times in the volcanic field and formed the Aso caldera, 25 km north-south and 18 km east-west. Basement rocks of Aso volcanoes consist of Quaternary Pre-Aso volcanic rocks, Cretaceous gr ...
rifting of the plate boundary in north iceland 1975-1978
... - 15 have been cyclic up and down movements (Fig. 3) while elevation changes on the fissure swarm to the south and north of the caldera are more or less transient phenomena. During subsidence events rapid and permanent changes in land elevation are observed, accompanied by east-west widening and ea ...
... - 15 have been cyclic up and down movements (Fig. 3) while elevation changes on the fissure swarm to the south and north of the caldera are more or less transient phenomena. During subsidence events rapid and permanent changes in land elevation are observed, accompanied by east-west widening and ea ...
VIRTUAL FIELD TRIP
... eruption depends on how easy magma can flow and the amount of gas trapped in it. When a volcano erupts, the magma goes up to the earth’s surface. The magma that goes up to earth surface is called Lava. Magma is the molten rock within the earth’s crust. Rock also come from the volcanoes in different ...
... eruption depends on how easy magma can flow and the amount of gas trapped in it. When a volcano erupts, the magma goes up to the earth’s surface. The magma that goes up to earth surface is called Lava. Magma is the molten rock within the earth’s crust. Rock also come from the volcanoes in different ...
Igneous Processes and Rock Bodies
... Texture reflects two stage cooling history of the rock. Minerals begin to form slowly beneath Earth’s surface, resulting in large crystals (plutonic stage). Then eruption occurs allowing remaining magma or lava to cool quickly resulting in smaller crystals ...
... Texture reflects two stage cooling history of the rock. Minerals begin to form slowly beneath Earth’s surface, resulting in large crystals (plutonic stage). Then eruption occurs allowing remaining magma or lava to cool quickly resulting in smaller crystals ...
Geology of Maui
... other consisting of Maui and Kaho'olawe. Kaho'olawe then separated from Maui, and finally Lanai separated from Moloka'i, both within the last 100,000 to 200,000 years. Penguin Bank probably submerged within the last several hundred thousand years. During the last glacial maximum (LGM), about 21,000 ...
... other consisting of Maui and Kaho'olawe. Kaho'olawe then separated from Maui, and finally Lanai separated from Moloka'i, both within the last 100,000 to 200,000 years. Penguin Bank probably submerged within the last several hundred thousand years. During the last glacial maximum (LGM), about 21,000 ...
Volcanic hazard mapping in Indonesia
... Bandung 40122, Indonesia Abstract: Indonesia is a wide archipelago where 129 active volcanoes are located. It means that about 13% of active volcanoes all over the world are located in the Indonesian archipelago. The volcanoes are located along the 7,000 km tectonic belt through Sumatera, Java, Nusa ...
... Bandung 40122, Indonesia Abstract: Indonesia is a wide archipelago where 129 active volcanoes are located. It means that about 13% of active volcanoes all over the world are located in the Indonesian archipelago. The volcanoes are located along the 7,000 km tectonic belt through Sumatera, Java, Nusa ...
The Tiers of Vocabulary - Cattaraugus
... they spouted red-hot molten rock. In modern times, scientists began to study volcanoes. They still don’t know all the answers, but they know much about how a volcano works. Our planet is made up of many layers of rock. The top layers of solid rock are called the crust. Deep beneath the crust is the ...
... they spouted red-hot molten rock. In modern times, scientists began to study volcanoes. They still don’t know all the answers, but they know much about how a volcano works. Our planet is made up of many layers of rock. The top layers of solid rock are called the crust. Deep beneath the crust is the ...
Igneous Rocks
... dense than the surrounding rocks. (When rock melts it takes up more space and, hence, it becomes less dense than the surrounding solid rock.) Occasionally molten rock reaches Earth’s surface where it is called lava . Sometimes lava is emitted as fountains that are produced when escaping gases propel ...
... dense than the surrounding rocks. (When rock melts it takes up more space and, hence, it becomes less dense than the surrounding solid rock.) Occasionally molten rock reaches Earth’s surface where it is called lava . Sometimes lava is emitted as fountains that are produced when escaping gases propel ...
The `rings of fire` and thyroid cancer
... worldwide. This phenomenon possibly suggests that common environmental influences in these regions may be responsible for the strikingly high rates.4,5 Both Hawaii and the Philippines in the Pacific region as well as Iceland in Europe are characterized by the presence of numerous volcanoes, a fact w ...
... worldwide. This phenomenon possibly suggests that common environmental influences in these regions may be responsible for the strikingly high rates.4,5 Both Hawaii and the Philippines in the Pacific region as well as Iceland in Europe are characterized by the presence of numerous volcanoes, a fact w ...
Lava is the molten rock expelled by a volcano during an eruption
... Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, and also c ...
... Intermediate or andesitic lavas are lower in aluminium and silica, and usually somewhat richer in magnesium and iron. Intermediate lavas form andesite domes and block lavas, and may occur on steep composite volcanoes, such as in the Andes. Poorer in aluminium and silica than felsic lavas, and also c ...
Mantle magmatic convective storms – a mechanism for intraplate
... dynamics. Linear, long-lived, and age-progressive volcanic chains have been explained as the manifestation of fixed hotspots possibly generated by buoyantly plumes of rising material originating deep in the mantle. However, the fixed hotspot model fails to explain observed short-lived chains, violat ...
... dynamics. Linear, long-lived, and age-progressive volcanic chains have been explained as the manifestation of fixed hotspots possibly generated by buoyantly plumes of rising material originating deep in the mantle. However, the fixed hotspot model fails to explain observed short-lived chains, violat ...
Snowflake ObsidianPDF
... Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline; in addition, its composition is too complex to comprise a single mineral. It is sometimes classified as a mineraloid. Though obsidian is usually dark in color similar to mafic rocks such as basalt, obsidian's ...
... Obsidian is mineral-like, but not a true mineral because as a glass it is not crystalline; in addition, its composition is too complex to comprise a single mineral. It is sometimes classified as a mineraloid. Though obsidian is usually dark in color similar to mafic rocks such as basalt, obsidian's ...
Geology and Geothermal Systems in the Bajawa Volcanic Rift Zone
... of them, has abruptly appeared in 1987 as a new lava dome. On the Mataloko anticline, volcanic activity has continued from 4 Ma to the present, and this terrain is almost entirely covered by the Pliocene and Quaternary volcanic rocks. Several late Quaternary volcanoes are recognized on the Mataloko ...
... of them, has abruptly appeared in 1987 as a new lava dome. On the Mataloko anticline, volcanic activity has continued from 4 Ma to the present, and this terrain is almost entirely covered by the Pliocene and Quaternary volcanic rocks. Several late Quaternary volcanoes are recognized on the Mataloko ...
Aim: What are igneous rocks?
... magma never reaches the surface Cooling time: cools slowly Crystal size: form large crystals Texture: medium to coarse grained texture Get exposed at the surface only when rock is uplifted and exposed • Also known as plutonic ...
... magma never reaches the surface Cooling time: cools slowly Crystal size: form large crystals Texture: medium to coarse grained texture Get exposed at the surface only when rock is uplifted and exposed • Also known as plutonic ...
Igneous Rocks - Home - KSU Faculty Member websites
... The nature of magma • Consists of three components: – A liquid portion, called melt, that is composed of mobile ions – Solids, if any, are silicate minerals that have already crystallized from the melt – Volatiles, which are gases dissolved in the melt, including water vapor (H2O), carbon dioxide (C ...
... The nature of magma • Consists of three components: – A liquid portion, called melt, that is composed of mobile ions – Solids, if any, are silicate minerals that have already crystallized from the melt – Volatiles, which are gases dissolved in the melt, including water vapor (H2O), carbon dioxide (C ...
Note - ees.nmt.edu
... Other volcanic features • Flood basalts – Largest volcanic events in terms of volume – Volatiles, viscosity are low, so not very explosive – Cover large areas w/ thick layers of lava ...
... Other volcanic features • Flood basalts – Largest volcanic events in terms of volume – Volatiles, viscosity are low, so not very explosive – Cover large areas w/ thick layers of lava ...
magma intrusion in `proto-caldera caldera` systems: example from
... 'K(iJ-Niavpo~'- TIjAO<;' , JiE: KarE:v8vv(J'/7 yvpw am B320° KW TI( roJii;~' o.Vrr7~' n7~' ypo.JiJlIj~' W B50oA, B300A and B20oL1 Karcv8vvoJiE:vo. PrlYIWW. H o.pXlreKrOVlK17 rov Kala ...
... 'K(iJ-Niavpo~'- TIjAO<;' , JiE: KarE:v8vv(J'/7 yvpw am B320° KW TI( roJii;~' o.Vrr7~' n7~' ypo.JiJlIj~' W B50oA, B300A and B20oL1 Karcv8vvoJiE:vo. PrlYIWW. H o.pXlreKrOVlK17 rov Kala ...
EENS 2120 Petrology Prof. Stephen A. Nelson Igneous Rocks of the
... In the early part of the century a debate among igneous petrologists ensued concerning the origin of granitic rocks (known as the "Granite Controversy"). One group referred to themselves as the granitizationists and argued that granitic rocks were produced by ultrametamorphism at high temperatures a ...
... In the early part of the century a debate among igneous petrologists ensued concerning the origin of granitic rocks (known as the "Granite Controversy"). One group referred to themselves as the granitizationists and argued that granitic rocks were produced by ultrametamorphism at high temperatures a ...
EN CRACK`N OPEN GEODES
... One of the most beautiful varieties of quartz found in geodes is amethyst. Amethyst is often present in volcanic rocks; accumulated in small pyramidal clusters. It is commonly used in jewelry for its brightness and characteristic purple color which comes from traces of iron. Legend has it, Amethyst ...
... One of the most beautiful varieties of quartz found in geodes is amethyst. Amethyst is often present in volcanic rocks; accumulated in small pyramidal clusters. It is commonly used in jewelry for its brightness and characteristic purple color which comes from traces of iron. Legend has it, Amethyst ...
Volcanology of Mars
Volcanic activity, or volcanism, has played a significant role in the geologic evolution of Mars. Scientists have known since the Mariner 9 mission in 1972 that volcanic features cover large portions of the Martian surface. These features include extensive lava flows, vast lava plains, and the largest known volcanoes in the Solar System. Martian volcanic features range in age from Noachian (>3.7 billion years) to late Amazonian (< 500 million years), indicating that the planet has been volcanically active throughout its history, and some speculate it probably still is so today. Both Earth and Mars are large, differentiated planets built from similar chondritic materials. Many of the same magmatic processes that occur on Earth also occurred on Mars, and both planets are similar enough compositionally that the same names can be applied to their igneous rocks and minerals.Volcanism is a process in which magma from a planet’s interior rises through the crust and erupts on the surface. The erupted materials consist of molten rock (lava), hot fragmental debris (tephra or ash), and gases. Volcanism is a principal way that planets release their internal heat. Volcanic eruptions produce distinctive landforms, rock types, and terrains that provide a window on the chemical composition, thermal state, and history of a planet's interior.Magma is a complex, high-temperature mixture of molten silicates, suspended crystals, and dissolved gases. Magma on Mars likely ascends in a similar manner to that on Earth. It rises through the lower crust in diapiric bodies that are less dense than the surrounding material. As the magma rises, it eventually reaches regions of lower density. When the magma density matches that of the host rock, buoyancy is neutralized and the magma body stalls. At this point, it may form a magma chamber and spread out laterally into a network of dikes and sills. Subsequently, the magma may cool and solidify to form intrusive igneous bodies (plutons). Geologists estimate that about 80% of the magma generated on Earth stalls in the crust and never reaches the surface.As magma rises and cools, it undergoes many complex and dynamic compositional changes. Heavier minerals may crystallize and settle to the bottom of the magma chamber. The magma may also assimilate portions of host rock or mix with other batches of magma. These processes alter the composition of the remaining melt, so that any magma reaching the surface may be chemically quite different from its parent melt. Magmas that have been so altered are said to be ""evolved"" to distinguish them from ""primitive"" magmas that more closely resemble the composition of their mantle source. (See igneous differentiation and fractional crystallization.) More highly evolved magmas are usually felsic, that is enriched in silica, volatiles, and other light elements compared to iron- and magnesium-rich (mafic) primitive magmas. The degree and extent to which magmas evolve over time is an indication of a planet's level of internal heat and tectonic activity. The Earth's continental crust is made up of evolved granitic rocks that developed through many episodes of magmatic reprocessing. Evolved igneous rocks are much less common on cold, dead bodies such as the Moon. Mars, being intermediate in size between the Earth and the Moon, is thought to be intermediate in its level of magmatic activity.At shallower depths in the crust, the lithostatic pressure on the magma body decreases. The reduced pressure can cause gases (volatiles), such as carbon dioxide and water vapor, to exsolve from the melt into a froth of gas bubbles. The nucleation of bubbles causes a rapid expansion and cooling of the surrounding melt, producing glassy shards that may erupt explosively as tephra (also called pyroclastics). Fine-grained tephra is commonly referred to as volcanic ash. Whether a volcano erupts explosively or effusively as fluid lava depends on the composition of the melt. Felsic magmas of andesitic and rhyolitic composition tend to erupt explosively. They are very viscous (thick and sticky) and rich in dissolved gases. Mafic magmas, on the other hand, are low in volatiles and commonly erupt effusively as basaltic lava flows. However, these are only generalizations. For example, magma that comes into sudden contact with groundwater or surface water may erupt violently in steam explosions called hydromagmatic (phreatomagmatic or phreatic) eruptions. Also, erupting magmas may behave differently on planets with different interior compositions, atmospheres, and gravity fields.