20170228 press-release
... Most earthquakes, volcanoes, mountain building, sea-floor spreading, and other major geological activities on Earth are driven by so called plate tectonics, where large sections of the Earth’s crust move as coherent blocks — or plates — that crash together, pull apart, slide on top of each other, ...
... Most earthquakes, volcanoes, mountain building, sea-floor spreading, and other major geological activities on Earth are driven by so called plate tectonics, where large sections of the Earth’s crust move as coherent blocks — or plates — that crash together, pull apart, slide on top of each other, ...
Deep Mantle Plumes and Geoscience Vision
... of this meeting [the 1997 GSA Annual Meeting] will demonstrate that a large fraction of the program is devoted to GSA’s efforts to educate at all levels. Now, what does all this have to do with deep mantle plumes? ...
... of this meeting [the 1997 GSA Annual Meeting] will demonstrate that a large fraction of the program is devoted to GSA’s efforts to educate at all levels. Now, what does all this have to do with deep mantle plumes? ...
Can progressive melt extraction from a plum
... large depth (-70 kin) of off-axis oceanic lithosphere. The plums are easier to melt, so proportionally more of the incompatible elements are extracted from these components. After melt extraction, the mixture of leftovers is depleted in composition, even though it still contains ~96-99% of the mass ...
... large depth (-70 kin) of off-axis oceanic lithosphere. The plums are easier to melt, so proportionally more of the incompatible elements are extracted from these components. After melt extraction, the mixture of leftovers is depleted in composition, even though it still contains ~96-99% of the mass ...
7. Early Evolution of the South Atlantic Ocean: Role of the Rifting
... to date the end of the rifting phase, based on the age of the oceanic crust at the contact of the COB as determined by identification of oceanic magnetic lineations. This method was previously used by Ryan (in Bolli, Ryan et al., 1978) to date the age of the salt deposition in the Angola Basin, assu ...
... to date the end of the rifting phase, based on the age of the oceanic crust at the contact of the COB as determined by identification of oceanic magnetic lineations. This method was previously used by Ryan (in Bolli, Ryan et al., 1978) to date the age of the salt deposition in the Angola Basin, assu ...
4.4 billion years of crustal maturation: oxygen isotope ratios of
... is increased if temperature decreases significantly during differentiation, however the effects of variable temperature on d18O(Zrc) are minor due to small intermineral fractionations at magmatic temperatures and because zircon fractionations are intermediate among rockforming minerals (i.e., zircon is ...
... is increased if temperature decreases significantly during differentiation, however the effects of variable temperature on d18O(Zrc) are minor due to small intermineral fractionations at magmatic temperatures and because zircon fractionations are intermediate among rockforming minerals (i.e., zircon is ...
On the formation of the arc of the Western Alps and
... continued all the way to Corsica and the Northern Apennines Internal Ligurides further to Calabria, Peloritani Mts., Kabilies into the Betics until some 30 Ma ago, following ideas proposed by Elter & Pertusati (1973) and Michard et al. (2002). The West Ligurian Ocean, i.e. the SE-ward continuation o ...
... continued all the way to Corsica and the Northern Apennines Internal Ligurides further to Calabria, Peloritani Mts., Kabilies into the Betics until some 30 Ma ago, following ideas proposed by Elter & Pertusati (1973) and Michard et al. (2002). The West Ligurian Ocean, i.e. the SE-ward continuation o ...
Could Iceland be a modern analogue for the Earth`s early
... indicating that tholeiitic basalt is the most suitable source for the latter. Consequently, it has been proposed that, in Iceland, depending on their location relative to the ridge-axis and the centre of the plume, felsic magmas could be generated either by fractional crystallization or by partial m ...
... indicating that tholeiitic basalt is the most suitable source for the latter. Consequently, it has been proposed that, in Iceland, depending on their location relative to the ridge-axis and the centre of the plume, felsic magmas could be generated either by fractional crystallization or by partial m ...
Introduction - Beck-Shop
... into the mantle (Mann & Taira, 2004). Although crustal growth by this mechanism appears minimal on modern Earth, it is interesting to speculate whether superplume events were more important earlier in Earth history, and this is one question that will only be answered by full characterization of Eart ...
... into the mantle (Mann & Taira, 2004). Although crustal growth by this mechanism appears minimal on modern Earth, it is interesting to speculate whether superplume events were more important earlier in Earth history, and this is one question that will only be answered by full characterization of Eart ...
Late 20th Century Tests of the Continental Drift Hypothesis
... One curious fact about them caught geologist’s attention: no sediment older than Cretaceous had ever been found in the oceans. (Some late Jurassic sediment is now known, as you will see, but that’s as old as it gets. We’ve looked everywhere there is to look now.) Whereas the continents have a record ...
... One curious fact about them caught geologist’s attention: no sediment older than Cretaceous had ever been found in the oceans. (Some late Jurassic sediment is now known, as you will see, but that’s as old as it gets. We’ve looked everywhere there is to look now.) Whereas the continents have a record ...
Geo-neutrinos and Earth Models
... These models are required to be consistent with physical and chemical observables of the crust, mantle, core system. The families of compositional models that describe the Earth span a factor of three in the abundances of the heat producing elements and differences are due to contrasts in starting as ...
... These models are required to be consistent with physical and chemical observables of the crust, mantle, core system. The families of compositional models that describe the Earth span a factor of three in the abundances of the heat producing elements and differences are due to contrasts in starting as ...
Non-plume magmatism and tectonics during the opening of the
... Because these SE USA dikes and buried basalts are probably all nearly 201 Ma in age (Ragland, 1991; Olsen, 1997), tectonic rift basin activity in the SE USA portion of the rift zone must have ended before the start of Jurassic time. Later uplift with erosion created a major hiatus and unconformity b ...
... Because these SE USA dikes and buried basalts are probably all nearly 201 Ma in age (Ragland, 1991; Olsen, 1997), tectonic rift basin activity in the SE USA portion of the rift zone must have ended before the start of Jurassic time. Later uplift with erosion created a major hiatus and unconformity b ...
Continental crust generated in oceanic arcs
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s−1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s−1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
FREE Sample Here
... and determining the time over which the spreading occurred. (a) Measure the distance between South America and Africa along the fracture zone indicated by the arrow in Figure 2.3. __________________ km The oldest rocks in the South Atlantic Ocean, immediately adjacent to the African and South Americ ...
... and determining the time over which the spreading occurred. (a) Measure the distance between South America and Africa along the fracture zone indicated by the arrow in Figure 2.3. __________________ km The oldest rocks in the South Atlantic Ocean, immediately adjacent to the African and South Americ ...
pdf
... where “magmatic” and “tectonic” spreading varies in both space and time. Keywords: Ocean-Continent transition, MORB, rifting, magma-poor margins, age determinations. INTRODUCTION It is generally accepted that rupturing of continents is followed by localized seafloor spreading at mid-ocean ridges (MO ...
... where “magmatic” and “tectonic” spreading varies in both space and time. Keywords: Ocean-Continent transition, MORB, rifting, magma-poor margins, age determinations. INTRODUCTION It is generally accepted that rupturing of continents is followed by localized seafloor spreading at mid-ocean ridges (MO ...
Flood basalts, continental breakup and the dispersal of
... Although the timings of the Cretaceous magmatic cycles in the Levant are well constrained, the geodynamic processes are less well-known. According to the plume evolution scenario, we would expect to find evidence for a rift/drift zone that might have been opened during this period. Such evidence has ...
... Although the timings of the Cretaceous magmatic cycles in the Levant are well constrained, the geodynamic processes are less well-known. According to the plume evolution scenario, we would expect to find evidence for a rift/drift zone that might have been opened during this period. Such evidence has ...
Continental crust generated in oceanic arcs
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s 1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
... Figure 5 | Integrated continental index results. a, CI versus average VP (from depth >10 km to a maximum velocity of 7.6 km s 1 , Supplementary Table 4). Arcs with no P-wave velocity data are represented as grey asterisks and their VP values are from the correlation equation in Fig. 4a. Uncertaintie ...
Seismic re¯ection image revealing offset of Andean subduction
... shear zone and the Nacza plate oceanic crust. The deepest, `brightest' part of the Nazca re¯ector is slightly ¯atter, and could either image the top of the subduction shear zone or be located a few kilometres above it. The downdip increase in re¯ectivity cannot be related to prograde dehydration met ...
... shear zone and the Nacza plate oceanic crust. The deepest, `brightest' part of the Nazca re¯ector is slightly ¯atter, and could either image the top of the subduction shear zone or be located a few kilometres above it. The downdip increase in re¯ectivity cannot be related to prograde dehydration met ...
Structure and rheology of lithosphere in Italy and surrounding.
... variability of their thicknesses. For the sake of clarity, in the uppermost crustal layers the values of Vs are omitted; these values are given in Farina (2006) and Panza et al. (2007b). The hypocentres with depth and magnitude type specified are denoted by red dots. The hypocentres with magnitude eq ...
... variability of their thicknesses. For the sake of clarity, in the uppermost crustal layers the values of Vs are omitted; these values are given in Farina (2006) and Panza et al. (2007b). The hypocentres with depth and magnitude type specified are denoted by red dots. The hypocentres with magnitude eq ...
Percent Precipitation: Diurnal Cycle DJF 2002-03
... http://www.cpc.ncep.noaa.gov/products/janowiak/cmorph.html ...
... http://www.cpc.ncep.noaa.gov/products/janowiak/cmorph.html ...
PDF format - gemoc - Macquarie University
... Previous studies have shown the mantle beneath Lac de Gras to be strongly stratified, having an ultra-depleted shallow layer (>100-140 km), possibly complementary to the overlying arcrelated crust, and a less depleted deep layer (140-220 km), possibly plume-derived (Pearson et al. 1999; Griffin et a ...
... Previous studies have shown the mantle beneath Lac de Gras to be strongly stratified, having an ultra-depleted shallow layer (>100-140 km), possibly complementary to the overlying arcrelated crust, and a less depleted deep layer (140-220 km), possibly plume-derived (Pearson et al. 1999; Griffin et a ...
crust - National Geographic Society
... general tends to be thicker on the “far side,” which always faces away from Earth. ...
... general tends to be thicker on the “far side,” which always faces away from Earth. ...
Mantle plumes, plumes and “plumes”: do we
... 4. Oceanic island basalts are enriched in incompatible elements compared with depleted mid-oceanic ridge basalts, hence source is primitive in composition (Earth’s lower mantle); 5. Hot spots lie atop of localized thermal upwellings referred to as plumes; 6. Plumes represent the major part of uprais ...
... 4. Oceanic island basalts are enriched in incompatible elements compared with depleted mid-oceanic ridge basalts, hence source is primitive in composition (Earth’s lower mantle); 5. Hot spots lie atop of localized thermal upwellings referred to as plumes; 6. Plumes represent the major part of uprais ...
A numerical investigation of continental collision styles
... asthenosphere. We find that these parameters influence the collision system, but that driving velocity, rheology and lithospheric (rather than Moho and mantle) temperature can be classified as important controls, whereas reasonable variations in the initial density contrast between oceanic lithosphe ...
... asthenosphere. We find that these parameters influence the collision system, but that driving velocity, rheology and lithospheric (rather than Moho and mantle) temperature can be classified as important controls, whereas reasonable variations in the initial density contrast between oceanic lithosphe ...
Endogenous Processes - Where Great Things Happen
... of these happens, the rock layers above the plates fold. That is, they bend of flex. (To visualize this, think of pushing two sheets of paper together.) Link: http://en.wikipedia.org/wiki/Fold_%28geology%29 Mountains often form from folding. In fact, most of the great mountain ranges of the world we ...
... of these happens, the rock layers above the plates fold. That is, they bend of flex. (To visualize this, think of pushing two sheets of paper together.) Link: http://en.wikipedia.org/wiki/Fold_%28geology%29 Mountains often form from folding. In fact, most of the great mountain ranges of the world we ...
The north Pyrenean Front and related foreland basin along the Bay
... sediments filling the Bay of Biscay abyssal plain, and deforms a North Pyrenean foreland basin located in front of the Cantabrian continental slope. Also shifted to the north with respect to the Basque-Parentis domain, this foreland basin lies on the top of the crust of the Bay of Biscay abyssal pla ...
... sediments filling the Bay of Biscay abyssal plain, and deforms a North Pyrenean foreland basin located in front of the Cantabrian continental slope. Also shifted to the north with respect to the Basque-Parentis domain, this foreland basin lies on the top of the crust of the Bay of Biscay abyssal pla ...
Supercontinent
In geology, a supercontinent is the assembly of most or all of the Earth's continental blocks or cratons to form a single large landmass. However, the definition of a supercontinent can be ambiguous. Many tectonicists such as P.F. Hoffman (1999) use the term ""supercontinent"" to mean ""a clustering of nearly all continents"". This definition leaves room for interpretation when labeling a continental body and is easier to apply to Precambrian times. Using the first definition provided here, Gondwana (aka Gondwanaland) is not considered a supercontinent, because the landmasses of Baltica, Laurentia and Siberia also existed at the same time but physically separate from each other. The landmass of Pangaea is the collective name describing all of these continental masses when they were in a close proximity to one another. This would classify Pangaea as a supercontinent. According to the definition by Rogers and Santosh (2004), a supercontinent does not exist today. Supercontinents have assembled and dispersed multiple times in the geologic past (see table). The positions of continents have been accurately determined back to the early Jurassic. However, beyond 200 Ma, continental positions are much less certain.