Radiogenic Isotope Geochemistry of the Mantle
... A principal objective of geology is to understand how the Earth evolved from its initial state to its present one. Radiogenic isotope geochemistry is uniquely suited for this sort of study because an isotope ratio such as 87Sr/86Sr is a function not only of the differentiation processes which fracti ...
... A principal objective of geology is to understand how the Earth evolved from its initial state to its present one. Radiogenic isotope geochemistry is uniquely suited for this sort of study because an isotope ratio such as 87Sr/86Sr is a function not only of the differentiation processes which fracti ...
Subduction styles in the Precambrian
... whereas the second transition is more abrupt and occurs at 175–160 K. The link between geological observations and model results suggests that the transition to the modern plate tectonic regime might have occurred during the Mesoarchean–Neoarchean time (ca. 3.2–2.5 Ga). In the case of the “pre-subdu ...
... whereas the second transition is more abrupt and occurs at 175–160 K. The link between geological observations and model results suggests that the transition to the modern plate tectonic regime might have occurred during the Mesoarchean–Neoarchean time (ca. 3.2–2.5 Ga). In the case of the “pre-subdu ...
Convective destabilization of a thickened continental lithosphere
... paths recorded by crustal rocks and the states of stress and strain in the belt [2]. Removal of the lithospheric root is then often proposed to explain uplift, high temperature metamorphism, and the development of syn orogenic extension in an orogenic belt. England and Houseman [3] and England [4], ...
... paths recorded by crustal rocks and the states of stress and strain in the belt [2]. Removal of the lithospheric root is then often proposed to explain uplift, high temperature metamorphism, and the development of syn orogenic extension in an orogenic belt. England and Houseman [3] and England [4], ...
P R E L I M I N A R Y P R O O F S Unpublished Work © 2008 by
... History. Within the uppermost portion of the mantle, near the surface of Earth our terminology becomes more complicated. For example, the cool, strong outermost layer of Earth is also called the lithosphere (lithos means “rock”). It is much stronger and more rigid than the material underlying it, th ...
... History. Within the uppermost portion of the mantle, near the surface of Earth our terminology becomes more complicated. For example, the cool, strong outermost layer of Earth is also called the lithosphere (lithos means “rock”). It is much stronger and more rigid than the material underlying it, th ...
Geological understanding of plate tectonics
... Fig. 4. a. The ocean-lithosphere-asthenosphere system illustrating “mean” density differences due to thermal or compositional differences, indicating the thick oceanic plateau lithosphere (OPL) to be less dense than the normal oceanic lithosphere (NOL). b. Two groups (A and B) of conjugate faults de ...
... Fig. 4. a. The ocean-lithosphere-asthenosphere system illustrating “mean” density differences due to thermal or compositional differences, indicating the thick oceanic plateau lithosphere (OPL) to be less dense than the normal oceanic lithosphere (NOL). b. Two groups (A and B) of conjugate faults de ...
- Wiley Online Library
... [Wallace and Green, 1991]. This standard is used as a proxy for the density of the asthenosphere influenced by the Afar hot spot. The buoyancy is calculated as the density difference between asthenosphere and mantle lithosphere: asthlith. The dataset of chemical compositions, the description of th ...
... [Wallace and Green, 1991]. This standard is used as a proxy for the density of the asthenosphere influenced by the Afar hot spot. The buoyancy is calculated as the density difference between asthenosphere and mantle lithosphere: asthlith. The dataset of chemical compositions, the description of th ...
Fluid Processes in Subduction Zones Hydrous Minerals and
... great depth in cool s.z. • Distribution + amount of H2O incoming lithosphere is critical unknown ...
... great depth in cool s.z. • Distribution + amount of H2O incoming lithosphere is critical unknown ...
Izu detachment hypothesis: A proposal of a unified cause for... event and the Tokai slow event
... most coincides with the region over which the horizontal crustal movements associated with the Miyake-Kozu event were evident. It is also noted that the Tokai slow event occurred just after the Miyake-Kozu event; Ozawa et al. (2002) inverted the slip history at the plate boundary to estimate slip on ...
... most coincides with the region over which the horizontal crustal movements associated with the Miyake-Kozu event were evident. It is also noted that the Tokai slow event occurred just after the Miyake-Kozu event; Ozawa et al. (2002) inverted the slip history at the plate boundary to estimate slip on ...
Extensional troughs in the Caloris Basin of Mercury
... gives rise to lateral pressure gradients, which can drive flow toward the basin center even if the basin is isostatically compensated (Nimmo and Stevenson, 2001). Lateral crustal flow will result in late-stage uplift of the existing basin materials (Fig. 4A) at a rate determined by the crustal thick ...
... gives rise to lateral pressure gradients, which can drive flow toward the basin center even if the basin is isostatically compensated (Nimmo and Stevenson, 2001). Lateral crustal flow will result in late-stage uplift of the existing basin materials (Fig. 4A) at a rate determined by the crustal thick ...
Crustal thickness variation in south
... These crustal thickness data allow us to consider isostatic compensation of the Alaska Range. Assuming perfect Airy isostasy we compare crustal thickness predicted from topography to crustal thickness determined by receiver function analysis. We use a mean crustal density of 2830 kg m⫺3 (Christensen ...
... These crustal thickness data allow us to consider isostatic compensation of the Alaska Range. Assuming perfect Airy isostasy we compare crustal thickness predicted from topography to crustal thickness determined by receiver function analysis. We use a mean crustal density of 2830 kg m⫺3 (Christensen ...
imp prefaz.qxp - Istituto Nazionale di Oceanografia e di Geofisica
... years) is relatively short; therefore, fluctuations of the activity in the different areas cannot be avoided. Nevertheless, we preferred to use more reliable data, especially for the focal depth, rather than extend the observation period. For the same reason the information can be poor in some speci ...
... years) is relatively short; therefore, fluctuations of the activity in the different areas cannot be avoided. Nevertheless, we preferred to use more reliable data, especially for the focal depth, rather than extend the observation period. For the same reason the information can be poor in some speci ...
Basin Analysis Basin Analysis Introduction Introduction Introduction
... Stretched over distances of 50-500 km Overlain by seaward-thickening sediment prisms ...
... Stretched over distances of 50-500 km Overlain by seaward-thickening sediment prisms ...
101 - Durham University Community
... subduction as is the case at present, (3) the average thickness of ocean crust is about 5 km as is at present, then the amount of recycled ocean crust since 3.0 Ga would be ~1.5 wt% of the entire mantle if whole-mantle convection has been the case or ~6 wt% if plate tectonics related mantle convecti ...
... subduction as is the case at present, (3) the average thickness of ocean crust is about 5 km as is at present, then the amount of recycled ocean crust since 3.0 Ga would be ~1.5 wt% of the entire mantle if whole-mantle convection has been the case or ~6 wt% if plate tectonics related mantle convecti ...
Contents and Preface
... The lithosphere is one of the most fundamental elements in solid Earth science in general, and in plate tectonics, in particular. As a result, solid Earth scientists from different backgrounds have studied the Earth’s lithosphere intensively. In doing so, most studies have focused on particular area ...
... The lithosphere is one of the most fundamental elements in solid Earth science in general, and in plate tectonics, in particular. As a result, solid Earth scientists from different backgrounds have studied the Earth’s lithosphere intensively. In doing so, most studies have focused on particular area ...
Composition of the crust and upper-mantle in the central Andes (19
... ratios and low velocity beneath the magmatic arc indicates partially molten rocks from a depth of 20 km down to the asthenospheric wedge. The Myers et al. (1998) results are based on data from mantle earthquakes recorded by two portable seismic cross-shaped networks. One of them, the BANJO array, wa ...
... ratios and low velocity beneath the magmatic arc indicates partially molten rocks from a depth of 20 km down to the asthenospheric wedge. The Myers et al. (1998) results are based on data from mantle earthquakes recorded by two portable seismic cross-shaped networks. One of them, the BANJO array, wa ...
Tectonics, Dynamics, and Seismic Hazard in the Canada–Alaska
... Our GPS velocity map can be used to help define the western edge of stable North America. As expected, all the sites located east of the Cordillera deformation front show very low horizontal velocities (<1 mm/a, Plate 3). However, one of the main questions of this study is the extent to which sites w ...
... Our GPS velocity map can be used to help define the western edge of stable North America. As expected, all the sites located east of the Cordillera deformation front show very low horizontal velocities (<1 mm/a, Plate 3). However, one of the main questions of this study is the extent to which sites w ...
Zoned mantle convection
... begun to hint at compositional heterogeneity in the bottom 1000 km or so of the mantle, but there is no compelling evidence in support of an interface between deep and shallow mantle at mid-depth. We suggest that in a system of thermochemical convection, lithospheric plates subduct to a depth that d ...
... begun to hint at compositional heterogeneity in the bottom 1000 km or so of the mantle, but there is no compelling evidence in support of an interface between deep and shallow mantle at mid-depth. We suggest that in a system of thermochemical convection, lithospheric plates subduct to a depth that d ...
Chapter 13 - The Theory of Plate Tectonics
... the inner core, the outer core, the mantle, and the crust Based on 2008 seismic data, the inner core is thought to be solid and composed mainly of iron crystals The entire inner core is 2,400 kilometers (1,491 miles) in diameter inner core has an inner core 1,180 km (733 miles) in diameter i ...
... the inner core, the outer core, the mantle, and the crust Based on 2008 seismic data, the inner core is thought to be solid and composed mainly of iron crystals The entire inner core is 2,400 kilometers (1,491 miles) in diameter inner core has an inner core 1,180 km (733 miles) in diameter i ...
fault - Science Partnership
... right-lateral. Displaced curbs such as this can be seen on the east side of Mission Blvd along cross streets. The creep rate in Hayward is approximately 5 mm/ year. Saturday, August 4, 12 ...
... right-lateral. Displaced curbs such as this can be seen on the east side of Mission Blvd along cross streets. The creep rate in Hayward is approximately 5 mm/ year. Saturday, August 4, 12 ...
Flow and melting of a heterogeneous mantle
... Understanding the partial melting process is key to our ability to relate geochemical characteristics of hotspot and midocean ridge lavas to the dynamics and chemical structure of the mantle. We present a method of computing the trace-element and isotopic compositions of magmas generated by melting ...
... Understanding the partial melting process is key to our ability to relate geochemical characteristics of hotspot and midocean ridge lavas to the dynamics and chemical structure of the mantle. We present a method of computing the trace-element and isotopic compositions of magmas generated by melting ...
Chapter 16. Noble Gas Isotopes
... generated by U + Th decay. This is known as the h e l ium heat - f l ow paradox. Since it is probably more difficult to degas the mantle now than during the early, high-temperature period of Earth history, it is likely that the stable noble gas isotopes - those that have not increased over time - ar ...
... generated by U + Th decay. This is known as the h e l ium heat - f l ow paradox. Since it is probably more difficult to degas the mantle now than during the early, high-temperature period of Earth history, it is likely that the stable noble gas isotopes - those that have not increased over time - ar ...
as a PDF
... same general subduction experiment for different parameter values such as plate age is, however, debatable. It is not always clear if global or regional dynamics leads to local deviations from general trends. Section 3 reviews results from global models for the role of slabs in driving plate motions ...
... same general subduction experiment for different parameter values such as plate age is, however, debatable. It is not always clear if global or regional dynamics leads to local deviations from general trends. Section 3 reviews results from global models for the role of slabs in driving plate motions ...
Mantle Discontinuities - Northwestern University
... coefficient of 0.072kO.010 at 660 km, for which they suggest a Vs contrast of about 8.5% and a density contrast of 6.1%. Their travel time correlations are consistent with endothermic (i.e., negative P-T slope) phase transitions near 650 km, with about 12 km of longwavelength topography on the bound ...
... coefficient of 0.072kO.010 at 660 km, for which they suggest a Vs contrast of about 8.5% and a density contrast of 6.1%. Their travel time correlations are consistent with endothermic (i.e., negative P-T slope) phase transitions near 650 km, with about 12 km of longwavelength topography on the bound ...
The thermal effects of steady-state slab
... m3 in a 10-km-thick upper crust. To facilitate comparison of the models with the observed heat flow, each heat flow measurement was adjusted to the model heat production rate over a 10-km-thick upper crust (Fig. 2). After this adjustment, the surface heat flow for the northern Cascadia backarc is qu ...
... m3 in a 10-km-thick upper crust. To facilitate comparison of the models with the observed heat flow, each heat flow measurement was adjusted to the model heat production rate over a 10-km-thick upper crust (Fig. 2). After this adjustment, the surface heat flow for the northern Cascadia backarc is qu ...
Post-glacial rebound
Post-glacial rebound (sometimes called continental rebound) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Post-glacial rebound and isostatic depression are different parts of a process known as either glacial isostasy, glacial isostatic adjustment, or glacioisostasy. Glacioisostasy is the solid Earth deformation associated with changes in ice mass distribution. The most obvious and direct affects of post-glacial rebound are readily apparent in northern Europe (especially Scotland, Estonia, Latvia, Fennoscandia, and northern Denmark), Siberia, Canada, the Great Lakes of Canada and the United States, the coastal region of the US state of Maine, parts of Patagonia, and Antarctica. However, through processes known as ocean siphoning and continental levering, the effects of post-glacial rebound on sea-level are felt globally far from the locations of current and former ice sheets.