Fig. 1 - Durham University Community
... 0024-4937/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.lithos.2008.12.009 ...
... 0024-4937/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.lithos.2008.12.009 ...
Correlated geophysical, geochemical, and volcanological
... Figure 2. Geophysical, volcanological, and geochemical variations along the western GSC showing the following: (a) depth of ridge axis (black line) and Galápagos swell (blue line); swell depth is corrected for variations in axial topography along western GSC. (b) Mantle Bouguer anomaly (black line) ...
... Figure 2. Geophysical, volcanological, and geochemical variations along the western GSC showing the following: (a) depth of ridge axis (black line) and Galápagos swell (blue line); swell depth is corrected for variations in axial topography along western GSC. (b) Mantle Bouguer anomaly (black line) ...
Future accreted terranes: a compilation of island arcs, oceanic
... striking, with the elevation rising from sea floor to sometimes a couple of kilometers above sea level over just 10 or 20 km distance. The locations of island arcs (∼ 120 km from the trench in subduction zones; England et al., 2004) are believed to be dictated by slab dip and melting in the mantle w ...
... striking, with the elevation rising from sea floor to sometimes a couple of kilometers above sea level over just 10 or 20 km distance. The locations of island arcs (∼ 120 km from the trench in subduction zones; England et al., 2004) are believed to be dictated by slab dip and melting in the mantle w ...
Phase Transitions and Mineralogy of the Upper Mantle
... less orthopyroxene, and minor clinopyroxene, and an additional aluminous phase such as plagioclase, spinel, or garnet. Figure 1(a) shows the nomenclature of peridotite based on its mineralogical composition (Streckeisen, 1974). The observed variability in mantle rocks may be described in terms of mo ...
... less orthopyroxene, and minor clinopyroxene, and an additional aluminous phase such as plagioclase, spinel, or garnet. Figure 1(a) shows the nomenclature of peridotite based on its mineralogical composition (Streckeisen, 1974). The observed variability in mantle rocks may be described in terms of mo ...
Crustal seismicity and the earthquake catalog maximum moment
... events in Africa and North America are concentrated at the edges of positive dVS anomalies that correspond to thick lithospheric roots beneath cratons. In South America, SCR earthquakes commonly fall within the 0–2% dVS contours. Australian seismicity shows a somewhat weaker correlation with dVS con ...
... events in Africa and North America are concentrated at the edges of positive dVS anomalies that correspond to thick lithospheric roots beneath cratons. In South America, SCR earthquakes commonly fall within the 0–2% dVS contours. Australian seismicity shows a somewhat weaker correlation with dVS con ...
imaging the upper mantle beneath turkey and surrounding regions
... Eastern Anatolia and beneath Dinarides-Hellenides while large negative station delays are observed in Western Anatolia and the Marmara Region. The majority of the stations in Central Anatolia show small station residuals indicating the average crustal thickness of 35±2 km. Western Anatolia and the A ...
... Eastern Anatolia and beneath Dinarides-Hellenides while large negative station delays are observed in Western Anatolia and the Marmara Region. The majority of the stations in Central Anatolia show small station residuals indicating the average crustal thickness of 35±2 km. Western Anatolia and the A ...
Mantle Mixing - Earth and Environmental Sciences
... MORB source has evolved with high ratios of U/3He compared to hotspots, consistent with the history of upper mantle depletion recorded by 87Sr/86Sr and 143Nd/144Nd in MORB (e.g. DePaolo & Wasserburg 1976; O’Nions et al 1979; Allègre et al 1979; Kurz et al 1982). The complement of this idea is that t ...
... MORB source has evolved with high ratios of U/3He compared to hotspots, consistent with the history of upper mantle depletion recorded by 87Sr/86Sr and 143Nd/144Nd in MORB (e.g. DePaolo & Wasserburg 1976; O’Nions et al 1979; Allègre et al 1979; Kurz et al 1982). The complement of this idea is that t ...
Geophysical Constraints on Mantle Composition
... these many orders of magnitude. Unhappily, VS is much more subject to dispersion than is VP, and the magnitude of such effects upon VS (and hence G) only grows with increasing temperature (and hence depth). Thus, until VS values can be both measured at simultaneous high P and T and extrapolated over ...
... these many orders of magnitude. Unhappily, VS is much more subject to dispersion than is VP, and the magnitude of such effects upon VS (and hence G) only grows with increasing temperature (and hence depth). Thus, until VS values can be both measured at simultaneous high P and T and extrapolated over ...
MANTLE MIXING - Earth and Environmental Sciences
... average production of basalt at ridges (Parsons 1981) and an assumption of the extent of MORB melting. An estimate of 20% partial melting at mid-oceanic ridges gives a MORB source mantle He concentration of 1.3 × 109 atoms 3He/g. O’Nions & Oxburgh (1983) noted that the rate of outgassing of the asso ...
... average production of basalt at ridges (Parsons 1981) and an assumption of the extent of MORB melting. An estimate of 20% partial melting at mid-oceanic ridges gives a MORB source mantle He concentration of 1.3 × 109 atoms 3He/g. O’Nions & Oxburgh (1983) noted that the rate of outgassing of the asso ...
Zha, Y., S. C. Webb, S. S. Wei, D. A. Wiens, D. K. Blackman, W
... The current phase of spreading in the Lau basin occurs along several north–south striking segments from 24◦ S to 15◦ S (Conder and Wiens, 2006; Zellmer and Taylor, 2001). From south to north, the spreading rate increases from 30 mm/yr at the southern Valu Fa ridge (VFR) to 95 mm/yr at the northern e ...
... The current phase of spreading in the Lau basin occurs along several north–south striking segments from 24◦ S to 15◦ S (Conder and Wiens, 2006; Zellmer and Taylor, 2001). From south to north, the spreading rate increases from 30 mm/yr at the southern Valu Fa ridge (VFR) to 95 mm/yr at the northern e ...
Seismic Refraction
... is measured at a variety of distances from the source. The type of seismic experiment differs depending on what aspect of the recorded ground motion is used in the subsequent analysis. We do not mean to imply by this statement that any seismic experiment can be done from a given set of observations. ...
... is measured at a variety of distances from the source. The type of seismic experiment differs depending on what aspect of the recorded ground motion is used in the subsequent analysis. We do not mean to imply by this statement that any seismic experiment can be done from a given set of observations. ...
Building and Destroying Continental Mantle - Cin
... of free-air gravity anomalies over continents (implying that continents are in isostatic equilibrium), Jordan proposed the isopycnic (iso = equal, pycnic = density) hypothesis: Continental mantle is made up of low-density, melt-depleted peridotite residua, whose low densities exactly offset the effe ...
... of free-air gravity anomalies over continents (implying that continents are in isostatic equilibrium), Jordan proposed the isopycnic (iso = equal, pycnic = density) hypothesis: Continental mantle is made up of low-density, melt-depleted peridotite residua, whose low densities exactly offset the effe ...
Velocity increase in the uppermost oceanic crust of subducting
... and S waves appear several seconds after the arrival of the relatively weak direct body waves. Previous studies reported that trapped P and S waves are only well observed for a particular geometry between source and receivers for earthquakes occurring in the oceanic crust and that their maximum ampl ...
... and S waves appear several seconds after the arrival of the relatively weak direct body waves. Previous studies reported that trapped P and S waves are only well observed for a particular geometry between source and receivers for earthquakes occurring in the oceanic crust and that their maximum ampl ...
The Earth`s mantle
... (dP/dT = DS/DV where DS and DV refer to entropy and volume changes of reaction, respectively.) (Fig. 2) that can, in conjunction with short-period seismic studies, be used to constrain mantle properties33,34. In the vicinity of a predictable change in mantle temperature structure a phase transformat ...
... (dP/dT = DS/DV where DS and DV refer to entropy and volume changes of reaction, respectively.) (Fig. 2) that can, in conjunction with short-period seismic studies, be used to constrain mantle properties33,34. In the vicinity of a predictable change in mantle temperature structure a phase transformat ...
The Tectonic Framework of the Sumatran Subduction Zone
... The 100-km-wide Barisan Mountains, the backbone of Sumatra (Figure 2), include preTertiary rocks covered by Cenozoic volcanic rocks. The structural central graben led van Bemmelen (1949) to conclude it was a rift structure and that the Sumatran fault was dip-slip in nature. Subsequent work revealed ...
... The 100-km-wide Barisan Mountains, the backbone of Sumatra (Figure 2), include preTertiary rocks covered by Cenozoic volcanic rocks. The structural central graben led van Bemmelen (1949) to conclude it was a rift structure and that the Sumatran fault was dip-slip in nature. Subsequent work revealed ...
Chapter 7. Radiogenic Isotope Geochemistry of the Crust and Oceans
... the next section, implying they formed from precursor material that had differentiated from the primitive mantle within ~200 million years or less of the start of the solar system. The following year, Touboul et al., (2012) reported εW averaging +0.15±0.05 in 2.8 billion year old komatiites (which a ...
... the next section, implying they formed from precursor material that had differentiated from the primitive mantle within ~200 million years or less of the start of the solar system. The following year, Touboul et al., (2012) reported εW averaging +0.15±0.05 in 2.8 billion year old komatiites (which a ...
Earth and Planetary Science
... Deep (at distance of about 400 km), the trench reaches a maximum depth of about 10.9 km. Another area of relatively deep trench is located at distance of about 650 km. The trench depth shows long-wavelength decrease northward. Prominent seamounts are located on the trench axis at distance of 1350, 1 ...
... Deep (at distance of about 400 km), the trench reaches a maximum depth of about 10.9 km. Another area of relatively deep trench is located at distance of about 650 km. The trench depth shows long-wavelength decrease northward. Prominent seamounts are located on the trench axis at distance of 1350, 1 ...
History of geodesy
Geodesy (/dʒiːˈɒdɨsi/), also named geodetics, is the scientific discipline that deals with the measurement and representation of the Earth. The history of geodesy began in antiquity and blossomed during the Age of Enlightenment.Early ideas about the figure of the Earth held the Earth to be flat (see flat earth), and the heavens a physical dome spanning over it. Two early arguments for a spherical Earth were that lunar eclipses were seen as circular shadows which could only be caused by a spherical Earth, and that Polaris is seen lower in the sky as one travels South.