Unit 1 – Plate Tectonics – april 2012GLC
... Paleoglaciation: Evidence suggests that vast ice sheets existed in South America, Africa, India, Australia, and Antarctica about 250 million years ago. However, many of these areas are tropical today. The current position of the continents would lead one to believe that glaciers must have existed in ...
... Paleoglaciation: Evidence suggests that vast ice sheets existed in South America, Africa, India, Australia, and Antarctica about 250 million years ago. However, many of these areas are tropical today. The current position of the continents would lead one to believe that glaciers must have existed in ...
Influence of convergent plate boundaries on upper mantle flow and
... by Hofmeister [1999]. We specify a depth-dependent viscosity that begins to rapidly increase at 660 km depth and attains approximately ninety percent of its maximum value at a depth of 1660 km, after which the rate of increase becomes much more gradual. This stratified viscosity matches the general ...
... by Hofmeister [1999]. We specify a depth-dependent viscosity that begins to rapidly increase at 660 km depth and attains approximately ninety percent of its maximum value at a depth of 1660 km, after which the rate of increase becomes much more gradual. This stratified viscosity matches the general ...
Crust and upper mantle discontinuity structure beneath eastern
... 4.5 km/s in the top sedimentary rock layer and 5.3 km/s in the bottom layer. These velocities are based on the range of P wave velocities in consolidated sediments (4.0 – 5.3 km/s) quoted by Mooney et al. [1998] and are broadly consistent with values from individual profiles summarized by Braile et ...
... 4.5 km/s in the top sedimentary rock layer and 5.3 km/s in the bottom layer. These velocities are based on the range of P wave velocities in consolidated sediments (4.0 – 5.3 km/s) quoted by Mooney et al. [1998] and are broadly consistent with values from individual profiles summarized by Braile et ...
Driving mechanism and 3-D circulation of plate tectonics
... cursor of plate tectonics—operated before about two billion years ago. Secular cooling of the upper mantle by 75 °C or 100 °C per b.y. is likely (Anderson, 2007; Hamilton, 2007). Plates commonly are visualized as being driven by wholemantle convection in a mostly unfractionated mantle: bottomheated ...
... cursor of plate tectonics—operated before about two billion years ago. Secular cooling of the upper mantle by 75 °C or 100 °C per b.y. is likely (Anderson, 2007; Hamilton, 2007). Plates commonly are visualized as being driven by wholemantle convection in a mostly unfractionated mantle: bottomheated ...
Upper mantle structure of eastern Asia from multimode surface
... seismograms for this study (Figure 3a) results in excellent density and azimuthal distribution of paths. Most of the earthquakes we study are located on the plate boundaries surrounding Asia. We selected the events from the Harvard centroid moment tensor catalog during the period 1977– 2002; however ...
... seismograms for this study (Figure 3a) results in excellent density and azimuthal distribution of paths. Most of the earthquakes we study are located on the plate boundaries surrounding Asia. We selected the events from the Harvard centroid moment tensor catalog during the period 1977– 2002; however ...
Formation of plate boundaries: The role of mantle volatilization
... plate tectonics had started earllier than the Archean/Proterozoic boundary (Burke et al., 1976; Campbell and Griffiths, 1992). However, even if we accept that it had started by that time, it is not easy to describe how it began. Because of the strongly temperature-dependent viscosity of the mantle ma ...
... plate tectonics had started earllier than the Archean/Proterozoic boundary (Burke et al., 1976; Campbell and Griffiths, 1992). However, even if we accept that it had started by that time, it is not easy to describe how it began. Because of the strongly temperature-dependent viscosity of the mantle ma ...
Buckling instabilities of subducted lithosphere beneath the transition
... thickening is real, we performed a synthetic test using the same path coverage and regularization parameters as those used to construct the velocity model RSHB. The input velocity model for the test (Fig. 3d) represents a slab 200 km wide that extends down to the core–mantle boundary (CMB). After in ...
... thickening is real, we performed a synthetic test using the same path coverage and regularization parameters as those used to construct the velocity model RSHB. The input velocity model for the test (Fig. 3d) represents a slab 200 km wide that extends down to the core–mantle boundary (CMB). After in ...
Searching to Learn - DigitalCommons@USU
... 12. Integrated Analysis on Gravity and Magnetic Fields of the Hailar Basin, NE China: Implications for Basement Structure and Deep Tectonics. Subjects: GRAVITY; MAGNETIC fields; GEOLOGY, Structural; PLATE tectonics; MANCHURIA (China); ...
... 12. Integrated Analysis on Gravity and Magnetic Fields of the Hailar Basin, NE China: Implications for Basement Structure and Deep Tectonics. Subjects: GRAVITY; MAGNETIC fields; GEOLOGY, Structural; PLATE tectonics; MANCHURIA (China); ...
Subduction-zone metamorphism, calc-alkaline - U
... to significant differences in regional metamorphic phase assemblages, described contrasting geologic occurrences, and inferred their characteristic ranges of physical conditions. He advanced the paired metamorphic belt concept, involving an oceanward, narrow, high-P/low-T blueschist zone intimately i ...
... to significant differences in regional metamorphic phase assemblages, described contrasting geologic occurrences, and inferred their characteristic ranges of physical conditions. He advanced the paired metamorphic belt concept, involving an oceanward, narrow, high-P/low-T blueschist zone intimately i ...
Tectonically asymmetric Earth - Dipartimento di Scienze della Terra
... Torsvik et al. (2010) computed the net rotation of the lithosphere (using indiscriminately all the hotspots and assuming that they are sourced from the deep mantle) and found that it is very slow, and that it has varied over the past 150 Ma. In their opinion this could suggest that the net rotation ...
... Torsvik et al. (2010) computed the net rotation of the lithosphere (using indiscriminately all the hotspots and assuming that they are sourced from the deep mantle) and found that it is very slow, and that it has varied over the past 150 Ma. In their opinion this could suggest that the net rotation ...
Загрузить этот файл PDF - Геодинамика и тектонофизика
... тивные ячеи Рэлея‐Бенара предопределяют размеры первичного разделения протолитосферы на отдельные массы – прообразы блоков. Ячеи Рэлея‐Бенара не впервые используются в геологии и геодинамике. Первона‐ ...
... тивные ячеи Рэлея‐Бенара предопределяют размеры первичного разделения протолитосферы на отдельные массы – прообразы блоков. Ячеи Рэлея‐Бенара не впервые используются в геологии и геодинамике. Первона‐ ...
Faulting and hydration of the Juan de Fuca plate system
... largely restricted to crustal levels. If dehydration embrittlement is an important mechanism for triggering intermediate-depth earthquakes within the subducting slab, then the limited occurrence rate and magnitude of intraslab seismicity at the Cascadia margin may in part be explained by the limited ...
... largely restricted to crustal levels. If dehydration embrittlement is an important mechanism for triggering intermediate-depth earthquakes within the subducting slab, then the limited occurrence rate and magnitude of intraslab seismicity at the Cascadia margin may in part be explained by the limited ...
Faulting and hydration of the Juan de Fuca plate system
... largely restricted to crustal levels. If dehydration embrittlement is an important mechanism for triggering intermediate-depth earthquakes within the subducting slab, then the limited occurrence rate and magnitude of intraslab seismicity at the Cascadia margin may in part be explained by the limited ...
... largely restricted to crustal levels. If dehydration embrittlement is an important mechanism for triggering intermediate-depth earthquakes within the subducting slab, then the limited occurrence rate and magnitude of intraslab seismicity at the Cascadia margin may in part be explained by the limited ...
Decoupling along plate boundaries: Key variable controlling the
... the Periadratic fault system, leading to crustalscale decoupling between the orogen proper and the indenter (Handy et al., 2005). 2. The switch from dominant north-directed thrusting of the orogenic wedge onto the European foreland to south-directed thrusting and internal deformation of the indenter ...
... the Periadratic fault system, leading to crustalscale decoupling between the orogen proper and the indenter (Handy et al., 2005). 2. The switch from dominant north-directed thrusting of the orogenic wedge onto the European foreland to south-directed thrusting and internal deformation of the indenter ...
Uppermost mantle structure of the eastern margin of the Tibetan
... travel times along the overlapped ray paths are almost identical (Fig. 2) (Phillips et al., 2005; Seward et al., 2009; Li et al., 2011b). To demonstrate this, we simulate the variation of P (including Pn) wave traveltime differences between a pair of stations followed the method proposed by Phillips ...
... travel times along the overlapped ray paths are almost identical (Fig. 2) (Phillips et al., 2005; Seward et al., 2009; Li et al., 2011b). To demonstrate this, we simulate the variation of P (including Pn) wave traveltime differences between a pair of stations followed the method proposed by Phillips ...
Geology
... However, in global mantle convection models, where this asymmetry is not prescribed, subduction is symmetrical, or “two-sided” (Figs. 1C and 1D), where downwelling involves materials from both plates (Tackley, 2000). Recent dynamic models of subduction process, operating with realistic viscoelasticp ...
... However, in global mantle convection models, where this asymmetry is not prescribed, subduction is symmetrical, or “two-sided” (Figs. 1C and 1D), where downwelling involves materials from both plates (Tackley, 2000). Recent dynamic models of subduction process, operating with realistic viscoelasticp ...
Lesson Plan - ScienceA2Z.com
... crust and mantle accumulates deformation gradually via shearing whereas the brittle upper crust reacts by fracture, or instantaneous stress release to cause motion along the fault. The ductile surface of the fault can also release instantaneously when the strain rate is too great. The energy release ...
... crust and mantle accumulates deformation gradually via shearing whereas the brittle upper crust reacts by fracture, or instantaneous stress release to cause motion along the fault. The ductile surface of the fault can also release instantaneously when the strain rate is too great. The energy release ...
On the structure and mechanical behaviour of the - Perso-sdt
... wavelengths of about 1OO- 1000 km, is mainly linked to the Moho geometry, we infer that surface loading (topography) applied on an elastic plate of variable effective thickness is not able to reproduce the observed Moho geometry. Current external sources of stress, as well as plate heterogeneities, ...
... wavelengths of about 1OO- 1000 km, is mainly linked to the Moho geometry, we infer that surface loading (topography) applied on an elastic plate of variable effective thickness is not able to reproduce the observed Moho geometry. Current external sources of stress, as well as plate heterogeneities, ...
Density constraints on the formation of the continental Moho and crust
... Regardless of whether the mass of the continental crust has grown or has been conserved with time, the isotopic data indicate that large volumes of calcalkaline magmas could have originated from the mantle during certain episodes. For a detailed discussion of the relationship between isotopic "age p ...
... Regardless of whether the mass of the continental crust has grown or has been conserved with time, the isotopic data indicate that large volumes of calcalkaline magmas could have originated from the mantle during certain episodes. For a detailed discussion of the relationship between isotopic "age p ...
Episodic Tremor and Slip
... Based on an analysis of non-volcanic tremor, it appears to be composed of swarms of so-called low frequency earthquakes, since typical earthquakes of similar magnitude would have more energy at higher frequencies. The swarm of seismic sources results in many overlapping signals on a seismogram (Figu ...
... Based on an analysis of non-volcanic tremor, it appears to be composed of swarms of so-called low frequency earthquakes, since typical earthquakes of similar magnitude would have more energy at higher frequencies. The swarm of seismic sources results in many overlapping signals on a seismogram (Figu ...
(on faults). - dynamicearth.de
... Displacement on a single fault that slip periodically in large earthquakes. The fault that cuts through entire elastic lithosphere. The lower part of the fault creeps at continuously at a slip rate equal to plate rate. Flow rate constant in asthenosphere. The stresses on the fault are ge ...
... Displacement on a single fault that slip periodically in large earthquakes. The fault that cuts through entire elastic lithosphere. The lower part of the fault creeps at continuously at a slip rate equal to plate rate. Flow rate constant in asthenosphere. The stresses on the fault are ge ...
Three Dimensional Electrical Structure of the Crust and Upper
... (Figs. 8a & 8b). While removing C3 had a relatively minor impact on the overall ...
... (Figs. 8a & 8b). While removing C3 had a relatively minor impact on the overall ...
EAS 102 / BIO G 170 Lecture 10, Page 1 of 6 PLATE TECTONICS
... little — from as much as 1600° C to about 1300° C — since the Early Archean, as shown by komatiites with eruption temperatures as much as 300° C higher than basalts in corresponding tectonic settings today. Abundant indications of liquid water and life in sedimentary rocks of all ages show that sea- ...
... little — from as much as 1600° C to about 1300° C — since the Early Archean, as shown by komatiites with eruption temperatures as much as 300° C higher than basalts in corresponding tectonic settings today. Abundant indications of liquid water and life in sedimentary rocks of all ages show that sea- ...
as a PDF
... quently, for making reconstructions of the regions adjacent to the Philippine Sea plate. Combining the Philippine Sea plate history with the known movements of the major plates, India, Australia, Pacific and Eurasia, provides some limits within which reconstructions of SE Asia, and parts of the west ...
... quently, for making reconstructions of the regions adjacent to the Philippine Sea plate. Combining the Philippine Sea plate history with the known movements of the major plates, India, Australia, Pacific and Eurasia, provides some limits within which reconstructions of SE Asia, and parts of the west ...
Chapter 8
... Plate boundaries • Types of plate boundaries • Transform fault boundaries • Plates slide past one another • No new crust is created • No crust is destroyed • Transform faults • Most join two segments of a mid-ocean ridge • At the time of formation, they roughly parallel the direction of plate movem ...
... Plate boundaries • Types of plate boundaries • Transform fault boundaries • Plates slide past one another • No new crust is created • No crust is destroyed • Transform faults • Most join two segments of a mid-ocean ridge • At the time of formation, they roughly parallel the direction of plate movem ...
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.