Stratigraphic placement and age of modern humans from Kibish
... from essentially the same level as the hominid, but they and others have questioned the reliability of the age5,6. Omo II was found on the surface at PHS (Paul’s Hominid Site), which Butzer14 mapped about 2.6 km northwest of KHS. A map drawn at the time by Paul Abell (discoverer of Omo II), together ...
... from essentially the same level as the hominid, but they and others have questioned the reliability of the age5,6. Omo II was found on the surface at PHS (Paul’s Hominid Site), which Butzer14 mapped about 2.6 km northwest of KHS. A map drawn at the time by Paul Abell (discoverer of Omo II), together ...
Plate boundary deformation between the Pacific and North America
... One of the consequences of plate tectonics is that a spreading ridge will eventually approach a subduction zone. The problem whether the possible break-up of the approaching ridge will lead to the development of independent micro-plates, or not, is still unresolved. Some 4 million years ago the inte ...
... One of the consequences of plate tectonics is that a spreading ridge will eventually approach a subduction zone. The problem whether the possible break-up of the approaching ridge will lead to the development of independent micro-plates, or not, is still unresolved. Some 4 million years ago the inte ...
Michael John O`Hara. 22 February 1933
... trench after being shelled. He returned to the UK and met Mike’s mother, Winifred Dorothy Avis, on the up train to London: she regularly caught the Waterloo train at Staines station at the last minute, and Mike’s father, who was a passenger on the train, delayed the train’s departure by holding the ...
... trench after being shelled. He returned to the UK and met Mike’s mother, Winifred Dorothy Avis, on the up train to London: she regularly caught the Waterloo train at Staines station at the last minute, and Mike’s father, who was a passenger on the train, delayed the train’s departure by holding the ...
The discovery of a conjugate system of faults in the Wharton Basin
... shears observed by Geersen et al. (25) further north in the outer rise area that might have been influenced by the plate bending, but some of the Riedel shears striking 330° to 360° might be genetically related to the 335°-striking normal faults that we observe in our study. Similarly, faults west o ...
... shears observed by Geersen et al. (25) further north in the outer rise area that might have been influenced by the plate bending, but some of the Riedel shears striking 330° to 360° might be genetically related to the 335°-striking normal faults that we observe in our study. Similarly, faults west o ...
Numerical lithospheric modelling: rheology, stress and deformation
... procedures, together with the sources of error are explained. Last a brief summary of each original paper including conclusions is given. Understanding rheological conditions through the entire lithosphere and even deeper is the key for understanding the deformation of the earth's interior. Thus, in ...
... procedures, together with the sources of error are explained. Last a brief summary of each original paper including conclusions is given. Understanding rheological conditions through the entire lithosphere and even deeper is the key for understanding the deformation of the earth's interior. Thus, in ...
Crustal contamination of mafic magmas: evidence from a
... rift-related mafic dike swarms are essential for understanding generation of such extensive mafic magmatism, and they may be used to identify mantle plumes (Ernst and Buchan, 1997, 2001). There is general agreement that mafic mantle-derived magmas experience some degree of crustal contamination duri ...
... rift-related mafic dike swarms are essential for understanding generation of such extensive mafic magmatism, and they may be used to identify mantle plumes (Ernst and Buchan, 1997, 2001). There is general agreement that mafic mantle-derived magmas experience some degree of crustal contamination duri ...
Ar– Ar ages of intrusions in East Greenland: Rift-to
... denoted “recalculated”. Mixing with a third component (atmospheric Ar) will displace isotopic compositions from the binary mixing line, most notably at low temperature steps, and these compositions are not used in the regression. Excess argon is more likely to be encountered in intrusive rocks than ...
... denoted “recalculated”. Mixing with a third component (atmospheric Ar) will displace isotopic compositions from the binary mixing line, most notably at low temperature steps, and these compositions are not used in the regression. Excess argon is more likely to be encountered in intrusive rocks than ...
Early opening history of the North Atlantic — I. Structure
... magnetic anomaly, but this position does not correspond to any break in the strong acoustic reflector seen here; on the contrary, the escarpment must lie at least 25 k m to the SE, where penetration to this reflector is lost at about 2.3 s TWT. On profile S3 there is a data gap on the airgun record ...
... magnetic anomaly, but this position does not correspond to any break in the strong acoustic reflector seen here; on the contrary, the escarpment must lie at least 25 k m to the SE, where penetration to this reflector is lost at about 2.3 s TWT. On profile S3 there is a data gap on the airgun record ...
A geological model for the structure of ridge segments in slow
... also show similar patternsof asymmetry;the IC residualgravity anomaliesvary widely but range 10-50 mGal higher than their OC counterparts. With the exception of a second-order discontinuityat 33ø35'S, however, the IC/OC gravity asymmetry generally is less pronouncedthan in the North Atlantic. The ob ...
... also show similar patternsof asymmetry;the IC residualgravity anomaliesvary widely but range 10-50 mGal higher than their OC counterparts. With the exception of a second-order discontinuityat 33ø35'S, however, the IC/OC gravity asymmetry generally is less pronouncedthan in the North Atlantic. The ob ...
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... sections should have deformed the accretionary prism or other parts of the crust in the shallow part of the subduction zone hanging wall (e.g., Taira, 2001). The first signs of this collision should define when the NE Philippine Sea plate began to be subducted beneath SW Japan. Understanding migrati ...
... sections should have deformed the accretionary prism or other parts of the crust in the shallow part of the subduction zone hanging wall (e.g., Taira, 2001). The first signs of this collision should define when the NE Philippine Sea plate began to be subducted beneath SW Japan. Understanding migrati ...
Recent Refinements in Geophysical Constraints on Lunar Origin
... A common feature of the Clementine and Lunar Prospector gravity models is that highland regions are characterized by low-amplitude anomalies that reflect a state of isostatic compensation of surface topography. In principle, such compensation may be achieved either by an Airy mechanism (thickness va ...
... A common feature of the Clementine and Lunar Prospector gravity models is that highland regions are characterized by low-amplitude anomalies that reflect a state of isostatic compensation of surface topography. In principle, such compensation may be achieved either by an Airy mechanism (thickness va ...
Receiver function constraints on crustal seismic velocities and
... with a Vp of 4.5 km/s extending to a depth of ∼6 km toward the RSR axis with a thinned upper crust of approximately 4 km thickness. The refraction profile, however, did not traverse the entire graben and hence did not obtain a viable variation of crustal structure across the rift axis. Refraction res ...
... with a Vp of 4.5 km/s extending to a depth of ∼6 km toward the RSR axis with a thinned upper crust of approximately 4 km thickness. The refraction profile, however, did not traverse the entire graben and hence did not obtain a viable variation of crustal structure across the rift axis. Refraction res ...
7. Migrated Multichannel Seismic-Reflection Records across the
... tens to hundreds of meters, as was seen in the central and southern areas (Figs. 3 and 4). The upper slope is separated from the middle slope by a large curvilinear fault (Bourgois et al., 1986) whose subsurface expression was masked in earlier reprocessed versions of CDP-3 (Miller et al., 1986). Al ...
... tens to hundreds of meters, as was seen in the central and southern areas (Figs. 3 and 4). The upper slope is separated from the middle slope by a large curvilinear fault (Bourgois et al., 1986) whose subsurface expression was masked in earlier reprocessed versions of CDP-3 (Miller et al., 1986). Al ...
For several decades single-component seismic reflection methods
... to map the bedrock up to the depth of 20-25 meters, three high resolution seismic reflection profiles were carried out. The data were acquired using a Strata Visor with 48channel, 40 Hz geophones and a weight drop system as seismic source. Seismic reflection data were recorded using a CMP (common mi ...
... to map the bedrock up to the depth of 20-25 meters, three high resolution seismic reflection profiles were carried out. The data were acquired using a Strata Visor with 48channel, 40 Hz geophones and a weight drop system as seismic source. Seismic reflection data were recorded using a CMP (common mi ...
Gulf of Mexico tectonic history: Hotspot tracks, crustal
... geophysical data, such as seismic refraction, gravity, and magnetics (Pindell, 1985, 1994; Christenson, 1990; Marton and Buffler, 1994). Determining the tectonic events that contributed to the formation and evolution of the Gulf of Mexico depends on an ability to define the size, shape, and extent o ...
... geophysical data, such as seismic refraction, gravity, and magnetics (Pindell, 1985, 1994; Christenson, 1990; Marton and Buffler, 1994). Determining the tectonic events that contributed to the formation and evolution of the Gulf of Mexico depends on an ability to define the size, shape, and extent o ...
d ated 2010
... (Ritter, 1978) and geochemical investigations of the De Hoop volcanics indicate that this more simple alternative scheme is not ruled out on petrological grounds. At present there is no radiometric data on the De Hoop volcanics that could give any indication of their true age. As a result, there app ...
... (Ritter, 1978) and geochemical investigations of the De Hoop volcanics indicate that this more simple alternative scheme is not ruled out on petrological grounds. At present there is no radiometric data on the De Hoop volcanics that could give any indication of their true age. As a result, there app ...
What is Basin Modeling
... lithosphere and asthenosphere. This is because the vertical motions in sedimentary basins are responses to deformations of this zone. Lithosphere: is the rigid outer shell of the Earth, comprising the crust and upper part of the mantle. It is of particular interest to note the difference between the ...
... lithosphere and asthenosphere. This is because the vertical motions in sedimentary basins are responses to deformations of this zone. Lithosphere: is the rigid outer shell of the Earth, comprising the crust and upper part of the mantle. It is of particular interest to note the difference between the ...
north american diamond deposits
... The 1967 Arkansas General Assembly passed legislation which became Act 128 designating diamond as the official gem of the State. To qualify as gem-grade, diamond must meet several criteria. It should be large enough to cut a stone whose value is more than the cost of cutting and the cost of the roug ...
... The 1967 Arkansas General Assembly passed legislation which became Act 128 designating diamond as the official gem of the State. To qualify as gem-grade, diamond must meet several criteria. It should be large enough to cut a stone whose value is more than the cost of cutting and the cost of the roug ...
Seismic Waves from the Outer and the Inner Core
... it may well be true from various considerations, among which the observed amplitudes of P’ played an important role. In any case, the assumption of such an hypothesis allowed Jeffreys to obtain travel-time values for PKIKP waves in agreement with those given by observation. Gutenberg in the followin ...
... it may well be true from various considerations, among which the observed amplitudes of P’ played an important role. In any case, the assumption of such an hypothesis allowed Jeffreys to obtain travel-time values for PKIKP waves in agreement with those given by observation. Gutenberg in the followin ...
here - W. Steven Holbrook
... native to arcs and therefore must be acquired during later tectonic and magmatic events. These differences in internal structure and bulk composition indicate that, if island arcs serve as building blocks of continental crust, their properties are significantly altered during or after accretion to a ...
... native to arcs and therefore must be acquired during later tectonic and magmatic events. These differences in internal structure and bulk composition indicate that, if island arcs serve as building blocks of continental crust, their properties are significantly altered during or after accretion to a ...
Future accreted terranes: a compilation of island arcs, oceanic
... Creek terranes were thrust and subsequently transported hundreds of kilometers inland over a Proterozoic metasedimentary wedge (Snyder et al., 2009; van der Velden and Cook, 2005; Cook et al., 2004). Other notable examples of accretion via flake tectonics include the Alps (Oxburgh, 1972) and the Arc ...
... Creek terranes were thrust and subsequently transported hundreds of kilometers inland over a Proterozoic metasedimentary wedge (Snyder et al., 2009; van der Velden and Cook, 2005; Cook et al., 2004). Other notable examples of accretion via flake tectonics include the Alps (Oxburgh, 1972) and the Arc ...
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.