Building and Destroying Continental Mantle - Cin
... The interiors of continents are cored by cratons (kratos is Greek for strength), regions of crustal basement that have not been deformed for >∼1 Ga. Thus, cratons include Archean and Proterozoic basements (see Goodwin 1991 and Hoffman 1989). Figure 1 shows the distribution of Precambrian (>540 Ma) c ...
... The interiors of continents are cored by cratons (kratos is Greek for strength), regions of crustal basement that have not been deformed for >∼1 Ga. Thus, cratons include Archean and Proterozoic basements (see Goodwin 1991 and Hoffman 1989). Figure 1 shows the distribution of Precambrian (>540 Ma) c ...
Hot spot activity and the break-up of Pangea (PDF
... and geological observations. Major hot spots helped to determine the longitudinal position of Pangea and to construct a model of plate motion during the Pangean break-up. The position of the northern part of Pangea was constrained using Iceland and Jan Mayen hot spots. The Iceland hot spot was trace ...
... and geological observations. Major hot spots helped to determine the longitudinal position of Pangea and to construct a model of plate motion during the Pangean break-up. The position of the northern part of Pangea was constrained using Iceland and Jan Mayen hot spots. The Iceland hot spot was trace ...
117. Lee, C. - Cin
... predates the time of crustal reworking. From the Rb/Sr ratio of the juvenile crust, they are able to infer the juvenile crust’s silica content. It turns out that the Rb/Sr ratio of juvenile crust increased around 3 Ga. This change implies a transition from basaltic to more silicic crust and points t ...
... predates the time of crustal reworking. From the Rb/Sr ratio of the juvenile crust, they are able to infer the juvenile crust’s silica content. It turns out that the Rb/Sr ratio of juvenile crust increased around 3 Ga. This change implies a transition from basaltic to more silicic crust and points t ...
2013249 - Geological Society of America
... triple junction, as the magnetic bight between the Japanese and Hawaiian lineation sets is clearly identified. There are uncertainties associated with reconstructing the exact history of ridge subduction, asymmetries of spreading where we only have information on one plate preserved, and several oth ...
... triple junction, as the magnetic bight between the Japanese and Hawaiian lineation sets is clearly identified. There are uncertainties associated with reconstructing the exact history of ridge subduction, asymmetries of spreading where we only have information on one plate preserved, and several oth ...
Unit 1 - Delmar
... Features like the one running down the middle of the Atlantic Ocean are called spreading ridges. They look like long, jagged scars and in a sense they are. To better understand the topography of the Mid-Atlantic Ridge, look at the three topographic profiles that cross it. Using the Hyperlink tool , ...
... Features like the one running down the middle of the Atlantic Ocean are called spreading ridges. They look like long, jagged scars and in a sense they are. To better understand the topography of the Mid-Atlantic Ridge, look at the three topographic profiles that cross it. Using the Hyperlink tool , ...
Hotspots and Melting anomalies - Earth and Environmental Sciences
... stationary with respect to each other, but prior to ~50 Ma, could have moved with respect to the geomagnetic poles and the Atlantic and Indian hotspots. The oldest volcanism of some, but not all, hotspot tracks is in the form of voluminous eruptions characterizing large igneous provinces. The connec ...
... stationary with respect to each other, but prior to ~50 Ma, could have moved with respect to the geomagnetic poles and the Atlantic and Indian hotspots. The oldest volcanism of some, but not all, hotspot tracks is in the form of voluminous eruptions characterizing large igneous provinces. The connec ...
Ancient recycled mantle lithosphere in the Hawaiian plume: Osmium
... Generation of basaltic oceanic crust at divergent plate boundaries (i.e. mid oceanic ridges) and recycling of the lithospheric plate back into the Earth's mantle via subduction at convergent plate boundaries play a principle role in the generation of long-lived chemical and isotopic heterogeneities ...
... Generation of basaltic oceanic crust at divergent plate boundaries (i.e. mid oceanic ridges) and recycling of the lithospheric plate back into the Earth's mantle via subduction at convergent plate boundaries play a principle role in the generation of long-lived chemical and isotopic heterogeneities ...
Major and Trace Element Composition of the Depleted MORB
... reference model for DMM (with the exception of Salters and Stracke, [6]), or one that is robust enough to be applied to the above-mentioned outstanding issues in earth science. The most compelling evidence for upper mantle depletion comes from its heavy-element isotopic composition; although MORBs a ...
... reference model for DMM (with the exception of Salters and Stracke, [6]), or one that is robust enough to be applied to the above-mentioned outstanding issues in earth science. The most compelling evidence for upper mantle depletion comes from its heavy-element isotopic composition; although MORBs a ...
Serpentine and the subduction zone water cycle
... deposited onto it adding material containing both pore and chemically bound water. Finally, there is increasing speculation that as the plate bends during subduction, its cold lithospheric mantle may become significantly hydrated [1– 4]. Dehydration occurs deeper within the subduction zone by fluid ...
... deposited onto it adding material containing both pore and chemically bound water. Finally, there is increasing speculation that as the plate bends during subduction, its cold lithospheric mantle may become significantly hydrated [1– 4]. Dehydration occurs deeper within the subduction zone by fluid ...
Week 23 Lesson Plan Science 8 all classes
... their folders according to CA results to monitor their progress. ...
... their folders according to CA results to monitor their progress. ...
Evolution of early continental crust
... crustal evolution. The only dated material older than ~ 4.3 Ga are detrital zircons from metaconglomerate of Neyerer complex, western Australia, which support the existence of continental crust 4.2 b.y. ago28. The presence of 3960 ± 3 Ma old gneiss reported from Slave Province of Canada31 and other ...
... crustal evolution. The only dated material older than ~ 4.3 Ga are detrital zircons from metaconglomerate of Neyerer complex, western Australia, which support the existence of continental crust 4.2 b.y. ago28. The presence of 3960 ± 3 Ma old gneiss reported from Slave Province of Canada31 and other ...
Shear zones in the Proterozoic lithosphere of the
... shear zones ( Fuchs, 1983) and shallow low velocity zones (Benz and McCarthy, 1994) speculatively caused by pervasive partial melt ( Thybo and Perchuc, 1997). Noting that the Hales discontinuity beneath the Canadian Slave province appears as a sharply bounded layer of width 10 km, Bostock (1998) pro ...
... shear zones ( Fuchs, 1983) and shallow low velocity zones (Benz and McCarthy, 1994) speculatively caused by pervasive partial melt ( Thybo and Perchuc, 1997). Noting that the Hales discontinuity beneath the Canadian Slave province appears as a sharply bounded layer of width 10 km, Bostock (1998) pro ...
Igneous Rock Associations 8. Arc Magmatism II: Geo
... mafic arc rocks are quartz-normative. Alkali-rich rocks and feldspathoidal rocks are rare (feldspathoids and quartz are mutually exclusive) and plagioclase typically dominates over alkalifeldspar. In recent years, chemical studies of arc magmas have integrated data from major elements (those that ty ...
... mafic arc rocks are quartz-normative. Alkali-rich rocks and feldspathoidal rocks are rare (feldspathoids and quartz are mutually exclusive) and plagioclase typically dominates over alkalifeldspar. In recent years, chemical studies of arc magmas have integrated data from major elements (those that ty ...
lesson 1 - sciencecafe
... enough to melt rock and form a thick, flowing substance called magma. Lighter than the solid rock that surrounds it, ...
... enough to melt rock and form a thick, flowing substance called magma. Lighter than the solid rock that surrounds it, ...
Post-collision, Shoshonitic Volcanism on the Tibetan Plateau
... the world and, although in a thermal context its Karakorum fault to the south and west (Fig. 1). origin is poorly understood, it often has similar Successive stages of the India—Asia collision and characteristics irrespective of location and age accretion of the Tibetan plateau were accompanied (Pea ...
... the world and, although in a thermal context its Karakorum fault to the south and west (Fig. 1). origin is poorly understood, it often has similar Successive stages of the India—Asia collision and characteristics irrespective of location and age accretion of the Tibetan plateau were accompanied (Pea ...
Dynamic lithosphere within the Great Basin
... lithosphere has been removed, likely via inflow of hot asthenosphere as subduction of the Farallon spreading center occurred and the region extended. In our proposed model, fragments of thermal lithosphere removed by this process were gravitationally unstable and subsequently sank into the underlying ...
... lithosphere has been removed, likely via inflow of hot asthenosphere as subduction of the Farallon spreading center occurred and the region extended. In our proposed model, fragments of thermal lithosphere removed by this process were gravitationally unstable and subsequently sank into the underlying ...
A New Mineral Province for PGEs, Au, Sc, Cu, Ni, Technology Metals
... Geodynamic interpretation: a Devonian age plume track in the Australian plate. Greenfield exploration opportunities in this new metallogenic province. Applications in South Australia. ...
... Geodynamic interpretation: a Devonian age plume track in the Australian plate. Greenfield exploration opportunities in this new metallogenic province. Applications in South Australia. ...
PDF
... silicate planets, but there are many variants. We especially do not understand the magmatically active stagnant lid mode, where lithosphere nevertheless must sink―perhaps by delamination―into the deep interior, in order to compensate for magma moving to the surface[30,31]. The reasons for stagnant l ...
... silicate planets, but there are many variants. We especially do not understand the magmatically active stagnant lid mode, where lithosphere nevertheless must sink―perhaps by delamination―into the deep interior, in order to compensate for magma moving to the surface[30,31]. The reasons for stagnant l ...
D4 : Paleomagnetism and plate tectonics
... Alexander von Humboldt noticed that rocks could be magnetized by lighting strikes. ...
... Alexander von Humboldt noticed that rocks could be magnetized by lighting strikes. ...
Niu, Y., Generation and evolution of basaltic magmas
... melting is the process that “transforms” a single and perhaps uniform rock (source) into two compositionally very different rocks: (1) the melt (or magma), which, upon cooling/assimilation, evolves to igneous rocks of various mineral assemblages, textures and bulk compositions, and which is enriched ...
... melting is the process that “transforms” a single and perhaps uniform rock (source) into two compositionally very different rocks: (1) the melt (or magma), which, upon cooling/assimilation, evolves to igneous rocks of various mineral assemblages, textures and bulk compositions, and which is enriched ...
Compositional symmetry between Earth`s crustal building blocks
... character (Fig. S-5), which coupled with their HFSE- and LILE-rich signature, points to the increasing importance and/or preservation of Phanerozoic-style intra-plate volcanism across the Archean-Proterozoic boundary (2.7–2.2 Ga; Condie and O’Neill, 2010). The extent to which this signal is influenc ...
... character (Fig. S-5), which coupled with their HFSE- and LILE-rich signature, points to the increasing importance and/or preservation of Phanerozoic-style intra-plate volcanism across the Archean-Proterozoic boundary (2.7–2.2 Ga; Condie and O’Neill, 2010). The extent to which this signal is influenc ...
Mantle Influence, Rifting and Magmatism in the East African Rift
... impact. The African Superplume has installed an anomalously high subsurface temperature regime in the South-central, Eastern and Northeastern Africa regions. On this background is superimposed an anomalous temperature regime caused by two focused mantle plumes, one rising under Afar and the other fr ...
... impact. The African Superplume has installed an anomalously high subsurface temperature regime in the South-central, Eastern and Northeastern Africa regions. On this background is superimposed an anomalous temperature regime caused by two focused mantle plumes, one rising under Afar and the other fr ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.