Crustal structure of the ultra-slow spreading Knipovich Ridge, North
... The Knipovich Ridge exhibits a 1,000–2,000 m deep rift valley with a seafloor depth ranging from 2,500 to 3,800 m. The axial trace, as defined by the deep rift valley, is more or less continuous and shows no distinct offsets. Based on axial depth variations, however, the ridge may be divided into se ...
... The Knipovich Ridge exhibits a 1,000–2,000 m deep rift valley with a seafloor depth ranging from 2,500 to 3,800 m. The axial trace, as defined by the deep rift valley, is more or less continuous and shows no distinct offsets. Based on axial depth variations, however, the ridge may be divided into se ...
doc
... work is connected with the very long return period of destroying events (M≥ 6.5). 2. Some problems of the seismicity of the Earth Since the birth of modern instrumental seismology at the end of XIXth century elapsed a little more than a century. In the same time the return period of characteristic s ...
... work is connected with the very long return period of destroying events (M≥ 6.5). 2. Some problems of the seismicity of the Earth Since the birth of modern instrumental seismology at the end of XIXth century elapsed a little more than a century. In the same time the return period of characteristic s ...
Drilling Active Tectonics and Magmatism (Volcanics, Geoprisms
... I. INTRODUCTION Forces originating deep within the active Earth are expressed on Earth’s surface, where they have a profound effect on human societies. On a global scale, these effects include the development of mountain ranges and subduction zones. On a local scale, they are expressed as active fau ...
... I. INTRODUCTION Forces originating deep within the active Earth are expressed on Earth’s surface, where they have a profound effect on human societies. On a global scale, these effects include the development of mountain ranges and subduction zones. On a local scale, they are expressed as active fau ...
Sample
... A) not related to the location of mid-ocean ridges. B) parallel to and symmetric about mid-ocean ridges. C) parallel to, but not symmetric about mid-ocean ridges. D) perpendicular to and symmetric about mid-ocean ridges. E) perpendicular to, but not symmetric about mid-ocean ridges. Answer: B Diff: ...
... A) not related to the location of mid-ocean ridges. B) parallel to and symmetric about mid-ocean ridges. C) parallel to, but not symmetric about mid-ocean ridges. D) perpendicular to and symmetric about mid-ocean ridges. E) perpendicular to, but not symmetric about mid-ocean ridges. Answer: B Diff: ...
Quantum Monte Carlo computations of phase of high-pressure silica
... of shock data (41, 42) and thermocalorimetry measurements (39, 43), while the WC boundary is about 4 GPa too low in pressure. The melting curve shown is from a classical model (44), which agrees well with available experiments collected in the reference. The triple point seen in the melting curve is ...
... of shock data (41, 42) and thermocalorimetry measurements (39, 43), while the WC boundary is about 4 GPa too low in pressure. The melting curve shown is from a classical model (44), which agrees well with available experiments collected in the reference. The triple point seen in the melting curve is ...
Structure of the Lithosphere and the Sedimentary Record: Where do
... The regional R2 pattern of the MD, VA, Delaware portions of the Salisbury Embayment is quite different from N.J. and requires several tectonic events, including a long-term subsidence event in the mid to Late Miocene. The center of the Eocene impact crater is showing the opposite sense of motion, su ...
... The regional R2 pattern of the MD, VA, Delaware portions of the Salisbury Embayment is quite different from N.J. and requires several tectonic events, including a long-term subsidence event in the mid to Late Miocene. The center of the Eocene impact crater is showing the opposite sense of motion, su ...
Moho Depth along the Antarctic Peninsula and
... material into the crust, or uplift of the lower crust. In the NE part of the Bransfield Strait where the larger “mushroom” HVB has its root, velocity increases continuously to 7.8 km s-1 at 30 km depth. This suggests the existence of a thick crust-mantle transition zone, often encountered in active ...
... material into the crust, or uplift of the lower crust. In the NE part of the Bransfield Strait where the larger “mushroom” HVB has its root, velocity increases continuously to 7.8 km s-1 at 30 km depth. This suggests the existence of a thick crust-mantle transition zone, often encountered in active ...
Constraints on the composition of the Aleutian arc lower crust from
... Figure 4. Seismic velocities of obducted arc rocks from Talkeetna and Kohistan [Kelemen et al., 2003a; Jagoutz et al., 2006]. Phase proportions and velocities were calculated from bulk composition with a version of Perple_X modified to include the alpha/beta quartz transition at (a) 750 C and (b) 90 ...
... Figure 4. Seismic velocities of obducted arc rocks from Talkeetna and Kohistan [Kelemen et al., 2003a; Jagoutz et al., 2006]. Phase proportions and velocities were calculated from bulk composition with a version of Perple_X modified to include the alpha/beta quartz transition at (a) 750 C and (b) 90 ...
Cr-Pyrope Garnets in the Lithospheric Mantle. I
... less depleted average lithospheric compositions from ~2·5 Ga to the present. These observations have important implications for Earth models: they suggest that lithospheric mantle is formed together with the overlying crust; that in most circumstances the lithospheric mantle (at least 200 km thick i ...
... less depleted average lithospheric compositions from ~2·5 Ga to the present. These observations have important implications for Earth models: they suggest that lithospheric mantle is formed together with the overlying crust; that in most circumstances the lithospheric mantle (at least 200 km thick i ...
Workshop Report - Consortium for Ocean Leadership
... opportunities to directly study fluid flow and melt fluxes above a subducting slab that are only now just being exploited. An increasingly large segment of the community working on cratonic mantle xenoliths understands these as refertilized residues, which initially underwent about 40% partial melti ...
... opportunities to directly study fluid flow and melt fluxes above a subducting slab that are only now just being exploited. An increasingly large segment of the community working on cratonic mantle xenoliths understands these as refertilized residues, which initially underwent about 40% partial melti ...
Crustal structure across the post-spreading - Archimer
... Briais et al., 1993; Wang et al., 2009; Sibuet et al., 2016). Compared with the Hawaiian-Emperor seamounts chain produced by mantle plume activities (Morgan, 1972), the Zhenbei-Huangyan seamounts chain does not show obviously along-trend variation with age. Therefore, these seamounts chains are like ...
... Briais et al., 1993; Wang et al., 2009; Sibuet et al., 2016). Compared with the Hawaiian-Emperor seamounts chain produced by mantle plume activities (Morgan, 1972), the Zhenbei-Huangyan seamounts chain does not show obviously along-trend variation with age. Therefore, these seamounts chains are like ...
Effects of active crustal movements on thermal structure in
... of oceanic sediments to overriding continental plates, we numerically simulate the evolution process of the thermal structure in subduction zones. 4.1 Vertical crustal movements caused by steady plate subduction Matsu’ura & Sato (1989) and Sato & Matsu’ura (1988, 1992, 1993) have constructed a kinem ...
... of oceanic sediments to overriding continental plates, we numerically simulate the evolution process of the thermal structure in subduction zones. 4.1 Vertical crustal movements caused by steady plate subduction Matsu’ura & Sato (1989) and Sato & Matsu’ura (1988, 1992, 1993) have constructed a kinem ...
Dynamic models of continental rifting with melt generation
... been applied successfully for the explanation of volcanic sequences at volcanic rich rifted continental margins (White et al., 1987; White and McKenzie, 1989). Given the extreme variability of abundance or absence of volcanic rocks at passive continental margins, and, at the same time the rather uni ...
... been applied successfully for the explanation of volcanic sequences at volcanic rich rifted continental margins (White et al., 1987; White and McKenzie, 1989). Given the extreme variability of abundance or absence of volcanic rocks at passive continental margins, and, at the same time the rather uni ...
Carboniferous and Permian igneous rocks of Great Britain
... memoirs were prepared, many of which remain as definitive sources to this day, despite the publication of subsequent editions. Non-Geological Survey workers were also prolific. Scores of papers were published on the eastern Midland Valley, in particular by D. Balsillie, R. Campbell, T.C. Day and F. ...
... memoirs were prepared, many of which remain as definitive sources to this day, despite the publication of subsequent editions. Non-Geological Survey workers were also prolific. Scores of papers were published on the eastern Midland Valley, in particular by D. Balsillie, R. Campbell, T.C. Day and F. ...
Chapter 18: Volcanic Activity
... Basaltic Magma Basaltic magma typically forms when rocks in the upper mantle melt. Most basaltic magma rises relatively rapidly to Earth’s surface and reacts very little with crustal rocks because of its low viscosity. Because basaltic magma contains small amounts of dissolved gases and silica, the ...
... Basaltic Magma Basaltic magma typically forms when rocks in the upper mantle melt. Most basaltic magma rises relatively rapidly to Earth’s surface and reacts very little with crustal rocks because of its low viscosity. Because basaltic magma contains small amounts of dissolved gases and silica, the ...
The Geological Concept
... InADictionaryoftheNatural Environment, Monkhouse and Small (1978) define the term "mountain" as follows: "A markedly elevated landform, bounded by steep slopes and rising to prominent ridges or individual summit-peaks. There is no specific altitude, but usually taken to be over 600 m (2000 ft.) in B ...
... InADictionaryoftheNatural Environment, Monkhouse and Small (1978) define the term "mountain" as follows: "A markedly elevated landform, bounded by steep slopes and rising to prominent ridges or individual summit-peaks. There is no specific altitude, but usually taken to be over 600 m (2000 ft.) in B ...
Nitrogen concentration and d N of altered oceanic crust obtained on
... 2005; cf. Scholl and von Huene, in press), limiting any attempts to compare subduction inputs and volcanic outputs for N. Altered oceanic crust subducting into modern trenches is thought to play a key role in the crust-mantle cycling of many volatiles and mobile elements (Philippot et al., 1998; Alt ...
... 2005; cf. Scholl and von Huene, in press), limiting any attempts to compare subduction inputs and volcanic outputs for N. Altered oceanic crust subducting into modern trenches is thought to play a key role in the crust-mantle cycling of many volatiles and mobile elements (Philippot et al., 1998; Alt ...
How do subduction processes contribute to forearc - HAL-Insu
... South American Pacific coasts between 16 and 32°S have been uplifting since the Lower Pleistocene, following a period of stability of the forearc region. Models confirm that local uplift is expected to occur above ridges, this phenomenon being predominant in central Peru where the Nazca Ridge is sub ...
... South American Pacific coasts between 16 and 32°S have been uplifting since the Lower Pleistocene, following a period of stability of the forearc region. Models confirm that local uplift is expected to occur above ridges, this phenomenon being predominant in central Peru where the Nazca Ridge is sub ...
Volcanic Activity - AC Reynolds High
... Basaltic Magma Basaltic magma typically forms when rocks in the upper mantle melt. Most basaltic magma rises relatively rapidly to Earth’s surface and reacts very little with crustal rocks because of its low viscosity. Because basaltic magma contains small amounts of dissolved gases and silica, the ...
... Basaltic Magma Basaltic magma typically forms when rocks in the upper mantle melt. Most basaltic magma rises relatively rapidly to Earth’s surface and reacts very little with crustal rocks because of its low viscosity. Because basaltic magma contains small amounts of dissolved gases and silica, the ...
Crustal Growth by Magmatic Accretion
... the cumulate microstructures, a clinopyroxene core containing well-developed exsolution lamellae, and therefore representative of high-temperature crystallization from magma, is surrounded by an exsolution-free metamorphic clinopyroxene rim with well-preserved Al zoning. This observation suggests th ...
... the cumulate microstructures, a clinopyroxene core containing well-developed exsolution lamellae, and therefore representative of high-temperature crystallization from magma, is surrounded by an exsolution-free metamorphic clinopyroxene rim with well-preserved Al zoning. This observation suggests th ...
Contributions of poroelastic rebound and a weak volcanic arc to the
... to the postseismic deformation of the 2011 Tohoku earthquake has yet to be investigated (Ozawa et al., 2012; Johnson et al., 2012; Diao et al., 2014). It is also known that compaction and heating of the hydrated subduction slab results in fluids migrating into the overlying mantle wedge (Manning, 20 ...
... to the postseismic deformation of the 2011 Tohoku earthquake has yet to be investigated (Ozawa et al., 2012; Johnson et al., 2012; Diao et al., 2014). It is also known that compaction and heating of the hydrated subduction slab results in fluids migrating into the overlying mantle wedge (Manning, 20 ...
State of lithosphere beneath Tien Shan from petrology and electrical
... from P‐T geothermobarometry of xenoliths and from comparison of their electrical conductivity with conductivities obtained from the inversion of magnetotelluric (MT) data. Spinel lherzolite and granulite xenoliths found in basaltic outcrop Ortosuu represent upper mantle and crust beneath southern Ti ...
... from P‐T geothermobarometry of xenoliths and from comparison of their electrical conductivity with conductivities obtained from the inversion of magnetotelluric (MT) data. Spinel lherzolite and granulite xenoliths found in basaltic outcrop Ortosuu represent upper mantle and crust beneath southern Ti ...
Calcium isotopic composition of mantle xenoliths and minerals from
... in the upper mantle. Huang et al. (2010) observed large offsets in D44/40Ca (up to 0.75‰) between opx and cpx from peridotite xenoliths. Such large inter-mineral Ca isotopic fractionation could be attributed to the differences in Ca– O bond length between cpx and opx. Based on firstprinciples calculati ...
... in the upper mantle. Huang et al. (2010) observed large offsets in D44/40Ca (up to 0.75‰) between opx and cpx from peridotite xenoliths. Such large inter-mineral Ca isotopic fractionation could be attributed to the differences in Ca– O bond length between cpx and opx. Based on firstprinciples calculati ...
The role of hydrous phases in the formation of trench parallel
... Karato, 2001; Faccenda et al., 2008; Long and Silver, 2008; Healy et al., 2009; Katayama et al., 2009; Nikulin et al., 2009; Jung, 2011]. These explanations can roughly be divided into two categories. The models in the first category invoke some form of CPO in asthenospheric olivine. For example, the ...
... Karato, 2001; Faccenda et al., 2008; Long and Silver, 2008; Healy et al., 2009; Katayama et al., 2009; Nikulin et al., 2009; Jung, 2011]. These explanations can roughly be divided into two categories. The models in the first category invoke some form of CPO in asthenospheric olivine. For example, the ...
Late 20th Century Tests of the Continental Drift Hypothesis
... In 1960 Harry Hess proposed a new hypothesis about what happens in the ocean. It was based on three emerging observations about the oceanic crust. At the time it was not clear whether these were really observable facts or just some geologists reading too much into their data instead. So Hess’s hypo ...
... In 1960 Harry Hess proposed a new hypothesis about what happens in the ocean. It was based on three emerging observations about the oceanic crust. At the time it was not clear whether these were really observable facts or just some geologists reading too much into their data instead. So Hess’s hypo ...
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.