A new model of lunar crust: asymmetry in crustal composition... Tomoko Arai , Hiroshi Takeda , Akira Yamaguchi
... some rocks enriched in alkali elements, termed alkali-suite rocks. There is another outstanding group, called KREEP, which is extremely enriched in alkalis and incompatible trace elements, such as K, rare earth elements (REEs) and P. They occur as impact melt rocks and basalts. The isotopic ages of ...
... some rocks enriched in alkali elements, termed alkali-suite rocks. There is another outstanding group, called KREEP, which is extremely enriched in alkalis and incompatible trace elements, such as K, rare earth elements (REEs) and P. They occur as impact melt rocks and basalts. The isotopic ages of ...
PDF (Chapter 11. Evolution of the Mantle)
... Most models of petrogenesis assume that basic and ultrabasic magmas are formed by varying degrees of partial melting of fertile peridotite in the upper mantle. In these models the degree of partial melting and crystal fractionation and the depth of origin are the main variables in controlling the c ...
... Most models of petrogenesis assume that basic and ultrabasic magmas are formed by varying degrees of partial melting of fertile peridotite in the upper mantle. In these models the degree of partial melting and crystal fractionation and the depth of origin are the main variables in controlling the c ...
Igneous Environments
... 6. Magma that reaches the surface erupts as lava (molten rock that flows on the surface) or as volcanic ash. Volcanic ash forms when dissolved gases in the magma expand and blow the magma apart into small fragments of volcanic glass. Any igneous rock that forms on the surface is called an extrusive r ...
... 6. Magma that reaches the surface erupts as lava (molten rock that flows on the surface) or as volcanic ash. Volcanic ash forms when dissolved gases in the magma expand and blow the magma apart into small fragments of volcanic glass. Any igneous rock that forms on the surface is called an extrusive r ...
Bedrock geology in New England submarine canyons
... lithology and relationships of the older rocks is best in Heezen Canyon, where our sampling was most successful. Our visual observations in Oceanographer Canyon, however, provided the clearest understanding of the younger Pliocene-Recent deposits. Our data and interpretations are synthesized in Figu ...
... lithology and relationships of the older rocks is best in Heezen Canyon, where our sampling was most successful. Our visual observations in Oceanographer Canyon, however, provided the clearest understanding of the younger Pliocene-Recent deposits. Our data and interpretations are synthesized in Figu ...
Mountain Building Processes in Four-Dimensions (4D-MB)
... landscape evolution in mountain belts. 4D-MB challenges conventional wisdom by recognising that in the Alps (Fig. 1) links between Earth’s surface and mantle can only be explained by integrating 3D imaging of the entire crust-mantle system with geologic observations and modeling to enable us to look ...
... landscape evolution in mountain belts. 4D-MB challenges conventional wisdom by recognising that in the Alps (Fig. 1) links between Earth’s surface and mantle can only be explained by integrating 3D imaging of the entire crust-mantle system with geologic observations and modeling to enable us to look ...
Age, Origin and Emplacement of Diamonds
... disciplines related to the physical, chemical, and mineralogic properties of diamonds, the roclzs in which they crystallize, as well as the roclzs that brought them to the surface and in which they now are found as primary deposits. Clearly, such a broad survey is beyond the scope of this article. T ...
... disciplines related to the physical, chemical, and mineralogic properties of diamonds, the roclzs in which they crystallize, as well as the roclzs that brought them to the surface and in which they now are found as primary deposits. Clearly, such a broad survey is beyond the scope of this article. T ...
Age and tectonic setting of the Tysfjord gneiss granite, Efjord, North
... ment Region, is dated at 1742 ± 46 Ma by the Rb-Sr whole-rock method. lts 87Sr/86Sr initial ratio of 0.71151 ± 0. 00247 is distinctly higher than the initial ratios of the plutons of the Rombak Window as well as the mangeritic rocks of the Hamarøy and Lofoten areas, suggesting that no simple comagma ...
... ment Region, is dated at 1742 ± 46 Ma by the Rb-Sr whole-rock method. lts 87Sr/86Sr initial ratio of 0.71151 ± 0. 00247 is distinctly higher than the initial ratios of the plutons of the Rombak Window as well as the mangeritic rocks of the Hamarøy and Lofoten areas, suggesting that no simple comagma ...
6 Metamorphic Rocks
... in a plastic or semiplastic state. The degree of plastic deformation possible during metamorphism is best seen by comparing the shapes of pebbles in a conglomerate with the shapes of pebbles in metamorphosed rock. In a metamorphosed rock, the original spherical pebbles in the conglomerate have been ...
... in a plastic or semiplastic state. The degree of plastic deformation possible during metamorphism is best seen by comparing the shapes of pebbles in a conglomerate with the shapes of pebbles in metamorphosed rock. In a metamorphosed rock, the original spherical pebbles in the conglomerate have been ...
Spatial, temporal and geochemical evolution of
... The isotopic signatures and trace element characteristics of these granitoids indicate that both lithospheric and asthenospheric mantle melts appear to have contributed to source region of the RMG, SCG and NATPG magmas. The compositional variations observed in these granitoids are interpreted as a r ...
... The isotopic signatures and trace element characteristics of these granitoids indicate that both lithospheric and asthenospheric mantle melts appear to have contributed to source region of the RMG, SCG and NATPG magmas. The compositional variations observed in these granitoids are interpreted as a r ...
Constraining the extent of crust–mantle coupling in central Asia
... the mantle align with the left-lateral maximum shear directions in the crustal deformation field in Tibet, but are not in Yunnan. Our results have the following implications. First, the coherence between crust and mantle deformation in Tibet implies strong crust–mantle mechanical coupling, since thi ...
... the mantle align with the left-lateral maximum shear directions in the crustal deformation field in Tibet, but are not in Yunnan. Our results have the following implications. First, the coherence between crust and mantle deformation in Tibet implies strong crust–mantle mechanical coupling, since thi ...
Durham Research Online
... plot. Dots represent the break-off mode (filled dots for the intermediate behaviour, outlined also by the grey banded area) and squares represent the delamination mode. and Schmeling, 1998] are in agreement with our results. Similarly, Baes et al. [2011] found that delamination occurs for values of l ...
... plot. Dots represent the break-off mode (filled dots for the intermediate behaviour, outlined also by the grey banded area) and squares represent the delamination mode. and Schmeling, 1998] are in agreement with our results. Similarly, Baes et al. [2011] found that delamination occurs for values of l ...
Mountain building and mantle dynamics
... Jolivet et al., 2003; Brun and Faccenna, 2008]. Such mountains are characterized by low elevation, small crustal thickness, and the presence of extensional structures [Royden, 1993a; Doglioni et al., 1999], dissecting their inner portion and exhuming deeper crustal layers [Brun and Faccenna, 2008]. ...
... Jolivet et al., 2003; Brun and Faccenna, 2008]. Such mountains are characterized by low elevation, small crustal thickness, and the presence of extensional structures [Royden, 1993a; Doglioni et al., 1999], dissecting their inner portion and exhuming deeper crustal layers [Brun and Faccenna, 2008]. ...
Global map of solid Earth surface heat flow
... in the unioned polygons; and then also the median of the heat flow value in the union polygons in a grid cell. The method in this case is slightly different in that the union of the grid and geology is joined to the heat flow measurements and not the reverse, and the medians are evaluated outside the ...
... in the unioned polygons; and then also the median of the heat flow value in the union polygons in a grid cell. The method in this case is slightly different in that the union of the grid and geology is joined to the heat flow measurements and not the reverse, and the medians are evaluated outside the ...
Geologic Structures
... leads to the formation of sandstone. Even though it would take too long for us to watch a specific layer of sandstone form, we can infer that the processes occur slowly—step by step—over great periods of time. If we measure current rates of geologic change, we must accept the idea that most rocks ar ...
... leads to the formation of sandstone. Even though it would take too long for us to watch a specific layer of sandstone form, we can infer that the processes occur slowly—step by step—over great periods of time. If we measure current rates of geologic change, we must accept the idea that most rocks ar ...
AZTEC QUADRANGLE NEW MEXICO AND COLORADO
... uranium and thorium content; and by semiquantitative emission spectrometry for 45 other elements. Results of these analyses are shown in Appendix B1. Raw data for the Aztec Quadrangle from the National Hydrogeochemical Stream and Sediment Reconnaissance (HSSR) program conducted by Los Alamos Scienti ...
... uranium and thorium content; and by semiquantitative emission spectrometry for 45 other elements. Results of these analyses are shown in Appendix B1. Raw data for the Aztec Quadrangle from the National Hydrogeochemical Stream and Sediment Reconnaissance (HSSR) program conducted by Los Alamos Scienti ...
PDF (Chapter 23. The Upper Mantle)
... as bulk silicate Earth (BSE) and differed from it only by the extraction of the continental crust, or that the most depleted - low in LIL, U, Th, K - midocean-ridge basalts plus their depleted refractory residues - unaltered abyssal peridotites- constitute the entire upper mantle. Traditionally, geo ...
... as bulk silicate Earth (BSE) and differed from it only by the extraction of the continental crust, or that the most depleted - low in LIL, U, Th, K - midocean-ridge basalts plus their depleted refractory residues - unaltered abyssal peridotites- constitute the entire upper mantle. Traditionally, geo ...
A trace element perspective on the source of ocean island basalts
... We analyze the first-order observations, basic concepts and explicit/implicit assumptions built into the three major hypotheses for the enriched component(s) in the source of ocean island basalts (OIB) in terms of incompatible trace elements: (1) subducted ocean crust (SOC), (2) subducted continenta ...
... We analyze the first-order observations, basic concepts and explicit/implicit assumptions built into the three major hypotheses for the enriched component(s) in the source of ocean island basalts (OIB) in terms of incompatible trace elements: (1) subducted ocean crust (SOC), (2) subducted continenta ...
Tectonic Setting and Regional Geology of the KSZ
... I would like to express my deep thanks and gratitude to PD Dr. Heinz Schandelmeier for supervision, encouragement, advises and for his guidance and discussion in the fieldwork phase of the study. He is also thanked for the sacrifices he made to make the fieldwork less risky. These thanks are also ex ...
... I would like to express my deep thanks and gratitude to PD Dr. Heinz Schandelmeier for supervision, encouragement, advises and for his guidance and discussion in the fieldwork phase of the study. He is also thanked for the sacrifices he made to make the fieldwork less risky. These thanks are also ex ...
Age of the Earth
The age of the Earth is 4.54 ± 0.05 billion years (4.54 × 109 years ± 1%). This age is based on evidence from radiometric age dating of meteorite material and is consistent with the radiometric ages of the oldest-known terrestrial and lunar samples.Following the development of radiometric age dating in the early 20th century, measurements of lead in uranium-rich minerals showed that some were in excess of a billion years old.The oldest such minerals analyzed to date—small crystals of zircon from the Jack Hills of Western Australia—are at least 4.404 billion years old. Comparing the mass and luminosity of the Sun to those of other stars, it appears that the Solar System cannot be much older than those rocks. Calcium-aluminium-rich inclusions – the oldest known solid constituents within meteorites that are formed within the Solar System – are 4.567 billion years old, giving an age for the solar system and an upper limit for the age of Earth.It is hypothesised that the accretion of Earth began soon after the formation of the calcium-aluminium-rich inclusions and the meteorites. Because the exact amount of time this accretion process took is not yet known, and the predictions from different accretion models range from a few millions up to about 100 million years, the exact age of Earth is difficult to determine. It is also difficult to determine the exact age of the oldest rocks on Earth, exposed at the surface, as they are aggregates of minerals of possibly different ages.