Economic geology research, volume 1 1999-2000
... Granberg, Viterliden, Gråberget, Sarvasåive, Sadenåive, Vaikijaur, Iekelvare, and Sjisjka. Most deposits share common characteristics, such as being hosted by intermediate to felsic intrusive rocks. They are all also Cu±Au±Fe oxide dominated deposits with a similar ore mineralogy and they generally ...
... Granberg, Viterliden, Gråberget, Sarvasåive, Sadenåive, Vaikijaur, Iekelvare, and Sjisjka. Most deposits share common characteristics, such as being hosted by intermediate to felsic intrusive rocks. They are all also Cu±Au±Fe oxide dominated deposits with a similar ore mineralogy and they generally ...
Magma genesis, plate tectonics, and chemical
... dynamics. Lavas reach the surface through volcanoes,and It was an over-illustrated, somewhat superficial ramble through the whole Earth emphasizing volcanic activity, the lavas can provide information about the source rocks from can be more dramatic aspectsof the Earth's chemical differentiation. wh ...
... dynamics. Lavas reach the surface through volcanoes,and It was an over-illustrated, somewhat superficial ramble through the whole Earth emphasizing volcanic activity, the lavas can provide information about the source rocks from can be more dramatic aspectsof the Earth's chemical differentiation. wh ...
The Magma Reservoirs That Feed Supereruptions
... The rocky innards of the Earth locally melt to produce magma, which sometimes erupts as cataclysmic explosions. The energy released by these eruptions is matched only by that of large meteorite impacts. Whether large pools of magma generate huge volcanic eruptions, whose volume and duration can have ...
... The rocky innards of the Earth locally melt to produce magma, which sometimes erupts as cataclysmic explosions. The energy released by these eruptions is matched only by that of large meteorite impacts. Whether large pools of magma generate huge volcanic eruptions, whose volume and duration can have ...
Cratons, mobile belts, alkaline rocks and
... arrows. (A) Classical subduction period. The middle crust of the active margin is weakened by wet intrusions. (B) Collision first induces thickening of both crust and mechanical boundary layer of the former active margin which increases rigidity below the Moho. (C) Thermal instability (Bird 1979) pa ...
... arrows. (A) Classical subduction period. The middle crust of the active margin is weakened by wet intrusions. (B) Collision first induces thickening of both crust and mechanical boundary layer of the former active margin which increases rigidity below the Moho. (C) Thermal instability (Bird 1979) pa ...
Major and Trace Element Composition of the Depleted MORB
... melt impregnation (e.g. [20, 25]); as a result, only 5 out of almost 90 samples included have any reported modal plagioclase at all. Anomalously high Ce and Sr values have also been excluded for some samples. For Sr, some anomalous values are suspected seawater alteration; such Sr anomalies are not ...
... melt impregnation (e.g. [20, 25]); as a result, only 5 out of almost 90 samples included have any reported modal plagioclase at all. Anomalously high Ce and Sr values have also been excluded for some samples. For Sr, some anomalous values are suspected seawater alteration; such Sr anomalies are not ...
The Oceanic Lithosphere
... basalts, peridotites, gabbros and other oceanic rocks provide clues on the processes that operate during and after the formation of the mantle lithosphere. These studies provide constraints on mantle composition and temperature, melting, magma accumulation and crystallization in the lithosphere, eru ...
... basalts, peridotites, gabbros and other oceanic rocks provide clues on the processes that operate during and after the formation of the mantle lithosphere. These studies provide constraints on mantle composition and temperature, melting, magma accumulation and crystallization in the lithosphere, eru ...
PDF (Chapter 23. The Upper Mantle)
... and this also appears to be the active layer for plate tectonics. The majority of the incompatible trace elements that are not in the crust may be confined to an even shallower depth range. Bullen's nomenclature is precise and useful and I will follow it. The terms upper mantle and lower mantle are ...
... and this also appears to be the active layer for plate tectonics. The majority of the incompatible trace elements that are not in the crust may be confined to an even shallower depth range. Bullen's nomenclature is precise and useful and I will follow it. The terms upper mantle and lower mantle are ...
Non-chondritic sulphur isotope composition of the terrestrial mantle
... lack of correlation between d34S and 206Pb/204Pb (Supplementary Fig. 5), together with the preservation of the trends between d34S and Sr–Nd isotopes, argue in favour of relatively sulphur-poor HIMU and LOMU endmembers, overprinted by the contribution of a sulphur-rich enriched-mantle component. In ...
... lack of correlation between d34S and 206Pb/204Pb (Supplementary Fig. 5), together with the preservation of the trends between d34S and Sr–Nd isotopes, argue in favour of relatively sulphur-poor HIMU and LOMU endmembers, overprinted by the contribution of a sulphur-rich enriched-mantle component. In ...
Origin of the modern Chiapanecan Volcanic arc in southern México
... trench. The subducting Cocos slab lies ~200 km below the modern Chiapanecan volcanic arc, whereas the majority of subduction-related volcanic arcs are located where the slab is at ~100 km depth (Gill, 1981). Second, although there is a little variation of the slab dip beneath Chiapas (40–45°) (Rebol ...
... trench. The subducting Cocos slab lies ~200 km below the modern Chiapanecan volcanic arc, whereas the majority of subduction-related volcanic arcs are located where the slab is at ~100 km depth (Gill, 1981). Second, although there is a little variation of the slab dip beneath Chiapas (40–45°) (Rebol ...
CHAPTER 5 Mafic-ultramafic complexes
... 5.3 Field characteristics of Arabian Shield ophiolites Ophiolites have been recognized in the Arabian Shield for more than 50 years. Where most complete, the Saudi Arabian ophiolites consist of serpentinized peridotite, gabbro, dike complex, basalt, and pelagic rocks. Because of folding and shearing ...
... 5.3 Field characteristics of Arabian Shield ophiolites Ophiolites have been recognized in the Arabian Shield for more than 50 years. Where most complete, the Saudi Arabian ophiolites consist of serpentinized peridotite, gabbro, dike complex, basalt, and pelagic rocks. Because of folding and shearing ...
Multi-Stage Origin of the Coast Range Ophiolite, Supra-Subduction Zone Ophiolites
... Jurassic sediments of the Great Valley Sequence. At other locales, plutonic rocks are scarce, the volcanic rocks are more like “oceanic” basalts (that is, basalts erupted at oceanic spreading centers or within oceanic plates), and contacts with sediments of the Great Valley Sequence may be faulted. ...
... Jurassic sediments of the Great Valley Sequence. At other locales, plutonic rocks are scarce, the volcanic rocks are more like “oceanic” basalts (that is, basalts erupted at oceanic spreading centers or within oceanic plates), and contacts with sediments of the Great Valley Sequence may be faulted. ...
World Heritage Volcanoes
... normally take place without significant explosive activity (unless water enters the system), which is a style of eruption that will form lava plains, lava fields and low-angled shield volcanoes. If the viscosity of the magma is high, escaping gases are released explosively, blasting magma and fragme ...
... normally take place without significant explosive activity (unless water enters the system), which is a style of eruption that will form lava plains, lava fields and low-angled shield volcanoes. If the viscosity of the magma is high, escaping gases are released explosively, blasting magma and fragme ...
Tectonic controls on the late Miocene–Holocene volcanic eruptions
... were derived from the subduction–collision zone between Indian and Eurasian plates. Zhao and Chen (1992) believed that it was a post-collision arc-volcanism or a delayed arc-volcanism in the southeast margin of the Tibetan plateau. Cong et al. (1994) proposed that the Tengchong volcanic swarms were ...
... were derived from the subduction–collision zone between Indian and Eurasian plates. Zhao and Chen (1992) believed that it was a post-collision arc-volcanism or a delayed arc-volcanism in the southeast margin of the Tibetan plateau. Cong et al. (1994) proposed that the Tengchong volcanic swarms were ...
Mission Moho Workshop: Drilling Through the Oceanic Crust to the
... The sub-seafloor biosphere also plays an important role in the chemical evolution of oceanic crust. The spatial distribution of microbes in the crust is not known but is likely influenced by host rock composition, temperature������ ...
... The sub-seafloor biosphere also plays an important role in the chemical evolution of oceanic crust. The spatial distribution of microbes in the crust is not known but is likely influenced by host rock composition, temperature������ ...
AbdolnaserFazlnia-Word offic file
... gabbros. In the gradational boundaries, gabbros are mineralogically transformed into anorthosites, and/or hornblendites. On the other hand, where the boundaries are sharp, the mineral assemblages change abruptly. There is no obvious deformation in the Mamakan gabbroic intrusions. Hence, the changes ...
... gabbros. In the gradational boundaries, gabbros are mineralogically transformed into anorthosites, and/or hornblendites. On the other hand, where the boundaries are sharp, the mineral assemblages change abruptly. There is no obvious deformation in the Mamakan gabbroic intrusions. Hence, the changes ...
The Volume and Composition of Melt Generated
... MgO, and SiO2 in addition vary with pressure. Another simple parameterization allows the observed compositions of major elements in 91 experiments to be calculated with a mean error of 11%, and those of TiO 2 and Na 2 O to 0 3 % . These expressions are then used to calculate the expected composition ...
... MgO, and SiO2 in addition vary with pressure. Another simple parameterization allows the observed compositions of major elements in 91 experiments to be calculated with a mean error of 11%, and those of TiO 2 and Na 2 O to 0 3 % . These expressions are then used to calculate the expected composition ...
Full-text PDF (final published version)
... long-term isolation of elements that are incompatible in the crystal structure of common mantle minerals and there is a complementary signature in the mantle (Armstrong, 1968; DePaolo and Wasserburg, 1976; O'Nions et al., 1979). While the continental crust is readily accessible, direct samples of th ...
... long-term isolation of elements that are incompatible in the crystal structure of common mantle minerals and there is a complementary signature in the mantle (Armstrong, 1968; DePaolo and Wasserburg, 1976; O'Nions et al., 1979). While the continental crust is readily accessible, direct samples of th ...
Petrology and Geochemistry of El Chichón and Tacaná: Two Active
... et al. 2009) has been grouped according to sample ages “or associated structures” into: 1982 eruption, Holocene, Pleistocene, Dome structures, mafic enclaves, and Chapultenango trachybasalt (Arce et al. 2014). The lava domes and pyroclastic deposits sampled inside the 1982 crater, with trachyandesiti ...
... et al. 2009) has been grouped according to sample ages “or associated structures” into: 1982 eruption, Holocene, Pleistocene, Dome structures, mafic enclaves, and Chapultenango trachybasalt (Arce et al. 2014). The lava domes and pyroclastic deposits sampled inside the 1982 crater, with trachyandesiti ...
Why did not the Ontong Java Plateau form subaerially?
... significant positive buoyancy from hot mantle as well as thick crust, which should be sufficient to raise the surface of the plateau well above sea level. Subaerial eruption is commonly observed for smaller-scale hotspots like Hawaii and Iceland. If viscous stress induced by upwelling is taken into ...
... significant positive buoyancy from hot mantle as well as thick crust, which should be sufficient to raise the surface of the plateau well above sea level. Subaerial eruption is commonly observed for smaller-scale hotspots like Hawaii and Iceland. If viscous stress induced by upwelling is taken into ...
American Journal of Science - gemoc
... 2004; Arndt and others, 2008). In either case, however, the change in MgO at the end of the Archean would reflect a drop in mantle temperature, although not as large if the magmas were wet. Decrease in Ni/Fe ratio in banded iron formation.—As recently documented by Konhauser and others (2009), the N ...
... 2004; Arndt and others, 2008). In either case, however, the change in MgO at the end of the Archean would reflect a drop in mantle temperature, although not as large if the magmas were wet. Decrease in Ni/Fe ratio in banded iron formation.—As recently documented by Konhauser and others (2009), the N ...
mid-ocean ridge tectonics, volcanism and
... Figure 2 Topography of spreading centers. (A) Cross-sections of typical fast-, intermediate-, and slow-spreading ridges based on high resolution deep-tow profiles. The neovolcanic zone is noted (the zone of active volcanism) and is several kilometers wide; the zone of active faulting extends to the ...
... Figure 2 Topography of spreading centers. (A) Cross-sections of typical fast-, intermediate-, and slow-spreading ridges based on high resolution deep-tow profiles. The neovolcanic zone is noted (the zone of active volcanism) and is several kilometers wide; the zone of active faulting extends to the ...
Igneous Environments
... the Jemez Mountains contains imposing cliffs of compacted volcanic ash erupted from the Valles Caldera. How do we recognize volcanic ash, and what makes some ash strong enough to form a cliff? ...
... the Jemez Mountains contains imposing cliffs of compacted volcanic ash erupted from the Valles Caldera. How do we recognize volcanic ash, and what makes some ash strong enough to form a cliff? ...
This PDF file is subject to the following conditions and... Copyright © 2006, The Geological Society of America, Inc. (GSA)....
... plume volcanism in an intraoceanic setting (Richards et al., 1989; Campbell et al., 1989; Hill, 1991). If the melting that forms komatiites occurs under dry conditions, mantle potential temperatures of ≈1500 to 1700 °C are implied: hotter than modern plume ...
... plume volcanism in an intraoceanic setting (Richards et al., 1989; Campbell et al., 1989; Hill, 1991). If the melting that forms komatiites occurs under dry conditions, mantle potential temperatures of ≈1500 to 1700 °C are implied: hotter than modern plume ...
Evolution of the Kurile-Kamchatkan Volcanic Arcs and Dynamics of
... Unit. The northern part of Kamchatsky Mys Peninsula is composed of Cretaceous – Middle Eocenian terrigenous-volcanogenic deposits of the Stolbovskaya Unit similar to those of Kronotsky and Shipunsky Peninsulas of the same age. Primitive tholeiites and high-Al basalts, typical for ensimatic island ar ...
... Unit. The northern part of Kamchatsky Mys Peninsula is composed of Cretaceous – Middle Eocenian terrigenous-volcanogenic deposits of the Stolbovskaya Unit similar to those of Kronotsky and Shipunsky Peninsulas of the same age. Primitive tholeiites and high-Al basalts, typical for ensimatic island ar ...
Minerals and Rocks - The University Digital Library
... are, however, usually compounds e.g. quartz (SiO2), pyrite (FeS2) or olivine (Mg,Fe)2[SiO4] in which the ratio of metal (Fe + Mg) to silicate group [SiO4] is 2:1. Minerals possess a characteristic crystal structure and therefore exclude non-crystalline materials such as glass. For example, quartz is ...
... are, however, usually compounds e.g. quartz (SiO2), pyrite (FeS2) or olivine (Mg,Fe)2[SiO4] in which the ratio of metal (Fe + Mg) to silicate group [SiO4] is 2:1. Minerals possess a characteristic crystal structure and therefore exclude non-crystalline materials such as glass. For example, quartz is ...
Basalt
Basalt (pronounced /bəˈsɔːlt/, /ˈbæsɒlt/, /ˈbæsɔːlt/, or /ˈbeɪsɔːlt/)is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of lava basalt flows.