Deep low-frequency earthquakes near the downward extension of the
... The electrical resistivity structure (Oshiman et al., 2003) exhibits low resistivity regions that also may indicate the fluid activity in the focal region. Doi et al. (2003) obtained the three dimensional distribution of the S-wave reflectors beneath the focal region of the Western Tottori earthquak ...
... The electrical resistivity structure (Oshiman et al., 2003) exhibits low resistivity regions that also may indicate the fluid activity in the focal region. Doi et al. (2003) obtained the three dimensional distribution of the S-wave reflectors beneath the focal region of the Western Tottori earthquak ...
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 ...
Moores and Twiss chapter 5
... region undergoing extension. Heat flow in the region is high, as much as three times normal for continental areas (Fig. 5.6). Most seismic activity in historical time has been concentrated in two northtrending zones along the western and eastern margins of the province. Earthquake first-motion studi ...
... region undergoing extension. Heat flow in the region is high, as much as three times normal for continental areas (Fig. 5.6). Most seismic activity in historical time has been concentrated in two northtrending zones along the western and eastern margins of the province. Earthquake first-motion studi ...
Quantifying the net slab pull force as a driving mechanism for plate
... their models, in which slab rollback was not allowed. In such a scenario, the surrounding mantle supports the slab only by shear stresses. However, if subduction would be allowed at a non-vertical subduction angle and if slab rollback would be allowed, then the mantle would support the slab by addit ...
... their models, in which slab rollback was not allowed. In such a scenario, the surrounding mantle supports the slab only by shear stresses. However, if subduction would be allowed at a non-vertical subduction angle and if slab rollback would be allowed, then the mantle would support the slab by addit ...
Volcanism in the Afar Rift sustained by decompression melting with
... This model is supported by a number of other observations, for example, Africa has moved >500 km northwards in a hotspot reference frame, away from the location where the plume-related flood basalt magmatism occurred ∼30 Myr ago26 . Furthermore, our predicted range of potential temperatures (1,350–1 ...
... This model is supported by a number of other observations, for example, Africa has moved >500 km northwards in a hotspot reference frame, away from the location where the plume-related flood basalt magmatism occurred ∼30 Myr ago26 . Furthermore, our predicted range of potential temperatures (1,350–1 ...
Tectonics of the Aegean/Anatolian region
... the NAF is almost entirely defined by a series of strike-slip earthquakes. Figure 4 shows a line of earthquakes that define the NAF from its junction with the EAF to its western termination. Focal mechanisms (see figure 3) show predominant strike-slip faulting with most slip vectors aligned approxim ...
... the NAF is almost entirely defined by a series of strike-slip earthquakes. Figure 4 shows a line of earthquakes that define the NAF from its junction with the EAF to its western termination. Focal mechanisms (see figure 3) show predominant strike-slip faulting with most slip vectors aligned approxim ...
A complex Tibetan upper mantle A fragmented Indian slab and no
... 51 azimuth and 101 epicentral distance sector, recorded by the same station. A weight was assigned to the travel times based on how many events from the same azimuth and epicentral distance range were recorded by the stations, and the weight was equal to the reciprocal value of the number of events ...
... 51 azimuth and 101 epicentral distance sector, recorded by the same station. A weight was assigned to the travel times based on how many events from the same azimuth and epicentral distance range were recorded by the stations, and the weight was equal to the reciprocal value of the number of events ...
The regional tectonic setting and possible causes of Cenozoic
... recognized. This extension affected a larger (Le Pichon 1982) and would comfortably enregion than the younger Basin and Range compass much of western Europe. The principal problem with Cenozoic extenProvince extending from northern British Columbia across the western United States and sional tectoni ...
... recognized. This extension affected a larger (Le Pichon 1982) and would comfortably enregion than the younger Basin and Range compass much of western Europe. The principal problem with Cenozoic extenProvince extending from northern British Columbia across the western United States and sional tectoni ...
Tectonic evolution of a continental collision zone
... sense is unlikely for convergence rates below 1.5– 2.5 cm/yr, but is not impossible for higher rates. Yet, many additional conditions must be satisfied to allow for continental subduction in nature. In particular, the competing deformation modes, such as RT instability, folding or pure shear should ...
... sense is unlikely for convergence rates below 1.5– 2.5 cm/yr, but is not impossible for higher rates. Yet, many additional conditions must be satisfied to allow for continental subduction in nature. In particular, the competing deformation modes, such as RT instability, folding or pure shear should ...
VS and density structure beneath the Colorado Plateau constrained
... [1] The Colorado Plateau is a physiographic province in the western US with an average elevation of 1.9 km where, in contrast to neighboring provinces, there is little evidence of large scale tectonic deformation or magmatism. Recent availability of Earthscope/ USArray seismic data allow us to bett ...
... [1] The Colorado Plateau is a physiographic province in the western US with an average elevation of 1.9 km where, in contrast to neighboring provinces, there is little evidence of large scale tectonic deformation or magmatism. Recent availability of Earthscope/ USArray seismic data allow us to bett ...
Eurasia spreading basin to Laptev Shelf transition: structural pattern
... The heat-flow stations are located in an area of high sediment accumulation. Thus a correction for the reduced geothermal gradient owing to rapid sedimentation has to be applied. The average sedimentation rate can be deduced from the thickness and age of the sedimentary cover. As the heat-flow stati ...
... The heat-flow stations are located in an area of high sediment accumulation. Thus a correction for the reduced geothermal gradient owing to rapid sedimentation has to be applied. The average sedimentation rate can be deduced from the thickness and age of the sedimentary cover. As the heat-flow stati ...
Uplift at lithospheric swellsI: seismic and gravity
... a means of mapping the geometry of such horizons within the sediment column, such as unconformities, which reflect major phases of subsidence or uplift. Wide-angle (WA) refraction data, on the other hand, not only provide velocities for depth conversion and subsequent top-of-plate load volume and ma ...
... a means of mapping the geometry of such horizons within the sediment column, such as unconformities, which reflect major phases of subsidence or uplift. Wide-angle (WA) refraction data, on the other hand, not only provide velocities for depth conversion and subsequent top-of-plate load volume and ma ...
letters - Institut de Physique du Globe de Paris
... Off-axis, the Moho reflections are observed between 1.9 and 2.3 s below the sea floor (Fig. 3a), which are similar to those observed in ref. 17 using widely spaced 2D seismic lines, whereas these reflections are 2.6–2.9 s below the sea floor beneath the wide AMC on the eastern limb, about 0.6–0.7 s ...
... Off-axis, the Moho reflections are observed between 1.9 and 2.3 s below the sea floor (Fig. 3a), which are similar to those observed in ref. 17 using widely spaced 2D seismic lines, whereas these reflections are 2.6–2.9 s below the sea floor beneath the wide AMC on the eastern limb, about 0.6–0.7 s ...
Thermal structure of the shallow upper mantle beneath Italy and
... Vs (shear-waves velocity) to the hydrous melt presence. This enhanced procedure provides supplementary information concerning the melt fraction (MF) in the upper mantle, corresponding to the temperature value inferred by the conversion. The degree of melting is modelled as a function of pressure, te ...
... Vs (shear-waves velocity) to the hydrous melt presence. This enhanced procedure provides supplementary information concerning the melt fraction (MF) in the upper mantle, corresponding to the temperature value inferred by the conversion. The degree of melting is modelled as a function of pressure, te ...
Effects of mantle and subduction-interface rheologies on slab
... Trench rollback has been a widely discussed phenomenon in recent years, and multiple studies have concentrated on various parameters that may influence trench migration and related aspects of slab deformation in the (upper) mantle. Here we concentrate on the effects of rheological description (yield ...
... Trench rollback has been a widely discussed phenomenon in recent years, and multiple studies have concentrated on various parameters that may influence trench migration and related aspects of slab deformation in the (upper) mantle. Here we concentrate on the effects of rheological description (yield ...
Large igneous provinces linked to supercontinent assembly
... 250 Ma, the geological and paleomagnetic evidence summarized above, conflicts with the plume hypothesis and suggests that LIPs coincided with the assembly of the supercontinent Pangea, and not with any major breakup event. There are several reasons why the Tarim and Emeishan LIPs are probably not rel ...
... 250 Ma, the geological and paleomagnetic evidence summarized above, conflicts with the plume hypothesis and suggests that LIPs coincided with the assembly of the supercontinent Pangea, and not with any major breakup event. There are several reasons why the Tarim and Emeishan LIPs are probably not rel ...
Uppermost mantle structure of the North China Craton: Constraints
... The uppermost mantle is the key area for exchange of heat flux and material convection between the crust and lithospheric mantle. Spatial variations of lithospheric thinning and dynamic processes in the North China Craton could inevitably induce the velocity heterogeneity in the uppermost mantle. In ...
... The uppermost mantle is the key area for exchange of heat flux and material convection between the crust and lithospheric mantle. Spatial variations of lithospheric thinning and dynamic processes in the North China Craton could inevitably induce the velocity heterogeneity in the uppermost mantle. In ...
The ocean-continent transition in the uniform lithospheric stretching
... The base of the lithosphere rises from hl to h1//3 during extension by a factor /3, which results in the ascent between hl and hl/Bofhot upper mantle material at the temperature of the asthenosphere, Ta,which we take as the temperature at depth hi in the mantle (figure 1). At small stretching factor ...
... The base of the lithosphere rises from hl to h1//3 during extension by a factor /3, which results in the ascent between hl and hl/Bofhot upper mantle material at the temperature of the asthenosphere, Ta,which we take as the temperature at depth hi in the mantle (figure 1). At small stretching factor ...
Flow and melting of a heterogeneous mantle: 2. Implications for a
... trace element and isotope composition of ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) [G. Ito, J. Mahoney, Flow and melting of a heterogeneous mantle 1: method and importance to the geochemistry of ocean island and midocean ridge basalts, Earth Planet. Sci. Lett. 230 (2005) 29–46] ...
... trace element and isotope composition of ocean island basalts (OIBs) and mid-ocean ridge basalts (MORBs) [G. Ito, J. Mahoney, Flow and melting of a heterogeneous mantle 1: method and importance to the geochemistry of ocean island and midocean ridge basalts, Earth Planet. Sci. Lett. 230 (2005) 29–46] ...
Geomagnetic Deep Sounding in and around the Kenya Rift Valley
... The computer program of Jones and Pascoe has been used to compute the response of two-dimensional conductivity models. The type of model that fits the experimental data involves a strip of high conductivity material at a depth of no more than 20 km beneath the floor of the rift with, in addition, a ...
... The computer program of Jones and Pascoe has been used to compute the response of two-dimensional conductivity models. The type of model that fits the experimental data involves a strip of high conductivity material at a depth of no more than 20 km beneath the floor of the rift with, in addition, a ...
Tomographic evidence for hydrated oceanic crust of the Pacific slab
... 2. Data, Method, and Resolution Test [5] In this study, we applied double-difference tomography method [Zhang and Thurber, 2003, 2006] to a large number of arrival-time data of 311,280 for P waves and 267,828 for S waves from 14,032 earthquakes that occurred in the period from 2001 to 2006. Arrival- ...
... 2. Data, Method, and Resolution Test [5] In this study, we applied double-difference tomography method [Zhang and Thurber, 2003, 2006] to a large number of arrival-time data of 311,280 for P waves and 267,828 for S waves from 14,032 earthquakes that occurred in the period from 2001 to 2006. Arrival- ...
The Continental Drift Hypothesis Plate Tectonics
... The figure below shows how some of the continents were joined as part of Pangaea 250 million years ago. The lighter area on the map shows where Glossopteris fossils have been found. Notice that the plant once grew in parts of five continents—South America, Africa, India, Antarctica, and Australia. B ...
... The figure below shows how some of the continents were joined as part of Pangaea 250 million years ago. The lighter area on the map shows where Glossopteris fossils have been found. Notice that the plant once grew in parts of five continents—South America, Africa, India, Antarctica, and Australia. B ...
Water transportation from the subducting slab into the mantle
... mantle transition depth (approximately 400 km) lawsonite is no longer stable and thereafter H2O is once migrated upward to the mantle wedge then again carried down to the transition zone due to the induced convection. At this depth, hydrous β-phase olivine is stable and plays a role as a huge water ...
... mantle transition depth (approximately 400 km) lawsonite is no longer stable and thereafter H2O is once migrated upward to the mantle wedge then again carried down to the transition zone due to the induced convection. At this depth, hydrous β-phase olivine is stable and plays a role as a huge water ...
Bio 1309 Early Earth History 4 Billion Years old! Horrible Place!
... geological trends between eastern coast of South America and western coast of Africa ...
... geological trends between eastern coast of South America and western coast of Africa ...
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.