Antipodal hotspots and bipolar catastrophes: Were oceanic large
... and test the antipodal character of Earth’s hotspot distribution, to evaluate a possible mechanism of antipodal hotspot formation, and to briefly explore the geological implications of such a mechanism of ...
... and test the antipodal character of Earth’s hotspot distribution, to evaluate a possible mechanism of antipodal hotspot formation, and to briefly explore the geological implications of such a mechanism of ...
crust - National Geographic Society
... Earth’s layers constantly interact with each other, and the crust and upper portion of the mantle are part of a single geologic unit called the lithosphere. The lithosphere’s depth varies, and the Mohorovicic discontinuity (the Moho)—the boundary between the mantle and crust—does not exist at a unif ...
... Earth’s layers constantly interact with each other, and the crust and upper portion of the mantle are part of a single geologic unit called the lithosphere. The lithosphere’s depth varies, and the Mohorovicic discontinuity (the Moho)—the boundary between the mantle and crust—does not exist at a unif ...
Mechanisms for the Origin of Mid-Ocean Ridge Axial Topography: Implications
... The well known difference in the axial topography of and widely available geophysicaldata, it is also important slow and fast spreadingmid-oceanridges is shownin Figure to understandthe possibleimplicationsof ridge axis topog1 by typical topographicprofiles across the axes of slow, raphy for the the ...
... The well known difference in the axial topography of and widely available geophysicaldata, it is also important slow and fast spreadingmid-oceanridges is shownin Figure to understandthe possibleimplicationsof ridge axis topog1 by typical topographicprofiles across the axes of slow, raphy for the the ...
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... in the entire Izu‐Bonin‐Mariana (IBM) arc. The relatively robust magmatic nature of this cross chain may reflect extensional stresses on the bending NW Philippine Sea plate as it is subducted beneath central Japan. [4] Several geochemical and isotopic studies have been carried out on Izu cross‐chain ...
... in the entire Izu‐Bonin‐Mariana (IBM) arc. The relatively robust magmatic nature of this cross chain may reflect extensional stresses on the bending NW Philippine Sea plate as it is subducted beneath central Japan. [4] Several geochemical and isotopic studies have been carried out on Izu cross‐chain ...
Origin and evolution of the lower crust in magmatic arcs and
... Talkeetna crust resulted in the replacement of dense mafic and ultramafic cumulates by residual upper mantle, producing a sharp seismic discontinuity at depths of around 38 to 42 km, characteristic of the continental Moho. Dynamic calculations indicate that foundering is an episodic process that oc ...
... Talkeetna crust resulted in the replacement of dense mafic and ultramafic cumulates by residual upper mantle, producing a sharp seismic discontinuity at depths of around 38 to 42 km, characteristic of the continental Moho. Dynamic calculations indicate that foundering is an episodic process that oc ...
Archaean plate tectonics revisited 1. Heat flow, spreading rate, and
... and Windley, 1982], the average thickness ...
... and Windley, 1982], the average thickness ...
Chapter 16 - Cenozoic - Tertiary
... – you will see that some important biological events – are related to isolation and/or connections – between various landmasses ...
... – you will see that some important biological events – are related to isolation and/or connections – between various landmasses ...
2014-Wannamaker-Casc.. - University of Alberta
... The present Cascadia subduction system and volcanic arc was established 40 Ma with disappearance of the Farallon plate and development of the Juan de Fuca plate [Humphreys, 2008]. In middle Cenozoic time, the arc extended farther south to present day southwestern Nevada but has shortened northward ...
... The present Cascadia subduction system and volcanic arc was established 40 Ma with disappearance of the Farallon plate and development of the Juan de Fuca plate [Humphreys, 2008]. In middle Cenozoic time, the arc extended farther south to present day southwestern Nevada but has shortened northward ...
- Wiley Online Library
... The present Cascadia subduction system and volcanic arc was established 40 Ma with disappearance of the Farallon plate and development of the Juan de Fuca plate [Humphreys, 2008]. In middle Cenozoic time, the arc extended farther south to present day southwestern Nevada but has shortened northward ...
... The present Cascadia subduction system and volcanic arc was established 40 Ma with disappearance of the Farallon plate and development of the Juan de Fuca plate [Humphreys, 2008]. In middle Cenozoic time, the arc extended farther south to present day southwestern Nevada but has shortened northward ...
Seismic Investigation of the Yavapai-Mazatzal Transition Zone
... During cratonic assembly, tectonic elements of various scales up to lithospheric-scale were incorporated in the Laurentia super-continent and the boundaries between these elements persisted as shallowly to steeply dipping structural and chemical boundaries, some of which appear to have been reactiva ...
... During cratonic assembly, tectonic elements of various scales up to lithospheric-scale were incorporated in the Laurentia super-continent and the boundaries between these elements persisted as shallowly to steeply dipping structural and chemical boundaries, some of which appear to have been reactiva ...
Static and dynamic support of western United States
... The continental Moho is more complicated than the oceanic Moho. However, to a first approximation, the geophysically defined crust–mantle boundary, the depth where vP jumps above 7.6 km/s, can be associated with a change in composition. Therefore, we assume that the major, shallow impedance contrast ...
... The continental Moho is more complicated than the oceanic Moho. However, to a first approximation, the geophysically defined crust–mantle boundary, the depth where vP jumps above 7.6 km/s, can be associated with a change in composition. Therefore, we assume that the major, shallow impedance contrast ...
Seafloor Spreading Hypothesis
... The features of the seafloor and the patterns of magnetic polarity symmetrically about the mid-ocean ridges were the pieces that Hess needed. He resurrected Wegener’s continental drift hypothesis and also the mantle convection idea of Holmes. Hess wrote that hot magma rose up into the rift valley at ...
... The features of the seafloor and the patterns of magnetic polarity symmetrically about the mid-ocean ridges were the pieces that Hess needed. He resurrected Wegener’s continental drift hypothesis and also the mantle convection idea of Holmes. Hess wrote that hot magma rose up into the rift valley at ...
Episodic Tremor and Slip The Cascadia Subduction Zone
... recently, using improved GPS data and analysis tools, scientists discovered more subtle stick-slip behaviour in a deeper portion of the subduction fault, now referred to as the ETS slip zone. ETS is observed as very small, slow slips that occur far more frequently than the massive, sudden shifts tha ...
... recently, using improved GPS data and analysis tools, scientists discovered more subtle stick-slip behaviour in a deeper portion of the subduction fault, now referred to as the ETS slip zone. ETS is observed as very small, slow slips that occur far more frequently than the massive, sudden shifts tha ...
Numerical models of slab migration in continental collision zones
... to a reversal of subduction polarity (Petterson et al., 1997; Knesel et al., 2008). Once the continental collision occurs, the position of the trench becomes a zone that marks a suture between the two plates. The mechanisms that drive the motion of this zone during the evolution of collision are sti ...
... to a reversal of subduction polarity (Petterson et al., 1997; Knesel et al., 2008). Once the continental collision occurs, the position of the trench becomes a zone that marks a suture between the two plates. The mechanisms that drive the motion of this zone during the evolution of collision are sti ...
Computation of phase equilibria by linear programming
... phase boundaries. Treatment of isentropic and isothermal phase relations involving felsic and mafic silicate melts by this method is illustrated. To demonstrate the tractability of more complex problems involving mass transfer, a model for infiltration driven-decarbonation in subduction zones is eva ...
... phase boundaries. Treatment of isentropic and isothermal phase relations involving felsic and mafic silicate melts by this method is illustrated. To demonstrate the tractability of more complex problems involving mass transfer, a model for infiltration driven-decarbonation in subduction zones is eva ...
Collision of continental corner from 3
... Continental collision has been extensively investigated with 2-D numerical models assuming infinitely wide plates or insignificant along-strike deformation in the third dimension. However, the corners of natural collision zones normally have structural characteristics that differ from linear parts of ...
... Continental collision has been extensively investigated with 2-D numerical models assuming infinitely wide plates or insignificant along-strike deformation in the third dimension. However, the corners of natural collision zones normally have structural characteristics that differ from linear parts of ...
Chapter 2 The Way the Earth Works: Plate Tectonics
... changes; continents waltz around this planet’s surface, variously combining and breaking apart through geologic time. The revolution began in 1960, when an American geologist, Harry Hess, proposed that as continents drift apart, new ocean floor forms between them by a process that his contemporary, ...
... changes; continents waltz around this planet’s surface, variously combining and breaking apart through geologic time. The revolution began in 1960, when an American geologist, Harry Hess, proposed that as continents drift apart, new ocean floor forms between them by a process that his contemporary, ...
Atlantic volcanic margins: a comparative study
... Abstract: Volcanic margins in the Atlantic Ocean reveal a series of common crustal units and structural features developed during continental extension and break-up. We suggest that four main crustal zones can be recognized on volcanic margins. This tectono-magmatic zonation implies a history of dev ...
... Abstract: Volcanic margins in the Atlantic Ocean reveal a series of common crustal units and structural features developed during continental extension and break-up. We suggest that four main crustal zones can be recognized on volcanic margins. This tectono-magmatic zonation implies a history of dev ...
Composition of the depleted mantle
... DM. The age of this single depletion event is an average age of the depletion of the DM; actual formation of the reservoir is not related to a single event, but is expected to be continuous. Using this approach it is assumed that processes operating on the mantle resulting in chemical change and for ...
... DM. The age of this single depletion event is an average age of the depletion of the DM; actual formation of the reservoir is not related to a single event, but is expected to be continuous. Using this approach it is assumed that processes operating on the mantle resulting in chemical change and for ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.