Subcontinental Lithosphere
... vexing problems in geochemistry. The principal observation to be explained is that mantle plumes invariably have less depleted isotopic signatures than MORB, and the isotopic compositions of some indicate net enrichment in incompatible elements. As we saw in the previous lecture, mantle plumes were ...
... vexing problems in geochemistry. The principal observation to be explained is that mantle plumes invariably have less depleted isotopic signatures than MORB, and the isotopic compositions of some indicate net enrichment in incompatible elements. As we saw in the previous lecture, mantle plumes were ...
Serpentinization of the forearc mantle
... land heat £ow data are available for comparison with model predictions, such as Cascadia [22,25] (Fig. 3). On this margin, a correction is needed for the heat £ow reduction e¡ect of rapidly thickening large accretionary prisms (e.g., [26]). After this correction, good agreement has been found betwee ...
... land heat £ow data are available for comparison with model predictions, such as Cascadia [22,25] (Fig. 3). On this margin, a correction is needed for the heat £ow reduction e¡ect of rapidly thickening large accretionary prisms (e.g., [26]). After this correction, good agreement has been found betwee ...
Geological Society, London, Special Publications
... as in a variety of sedimentary rocks of different ages. A number of deposits from active plate margins such as those of the northern Apennine assemblage (Bonatti et al. 1976), Pindos and Othris zones (Robertson & Varnavas 1993), and the Olympic Peninsula deposit (Park 1946) demonstrate their derivat ...
... as in a variety of sedimentary rocks of different ages. A number of deposits from active plate margins such as those of the northern Apennine assemblage (Bonatti et al. 1976), Pindos and Othris zones (Robertson & Varnavas 1993), and the Olympic Peninsula deposit (Park 1946) demonstrate their derivat ...
`emplacement` of an ophiolite?
... ultramafic, gabbro and dyke sections of the Taitao ophiolite in Chile display a mid-ocean ridge basalt (MORB) affinity whereas the geochemistry of extrusive rocks, which are interpreted to have erupted after the spreading centre had intersected with the trench (LeMoigne et al. 1996), indicates a mix ...
... ultramafic, gabbro and dyke sections of the Taitao ophiolite in Chile display a mid-ocean ridge basalt (MORB) affinity whereas the geochemistry of extrusive rocks, which are interpreted to have erupted after the spreading centre had intersected with the trench (LeMoigne et al. 1996), indicates a mix ...
AN EARLY PERMIAN SUBTROPICAL CARBONATE SYSTEM:
... the predominant fossils throughout the extent of these two units, with local occurrences of large fusulinids and colonial corals. This mixed photozoan-heterozoan assemblage is similar to the sediments of modern-day subtropical settings. Although the Raanes and Great Bear Cape have warm-water rocks b ...
... the predominant fossils throughout the extent of these two units, with local occurrences of large fusulinids and colonial corals. This mixed photozoan-heterozoan assemblage is similar to the sediments of modern-day subtropical settings. Although the Raanes and Great Bear Cape have warm-water rocks b ...
as a PDF
... Horizontal rock slices were cut from the field-oriented specimens. Oriented thin sections were made from the slices, which were photographed and mounted between hemispheres on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains ...
... Horizontal rock slices were cut from the field-oriented specimens. Oriented thin sections were made from the slices, which were photographed and mounted between hemispheres on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains ...
The stability of arc lower crust: Insights from the Talkeetna Arc
... -5cannot be used to explore a wide range of compositional space (e.g., major element composition, H2O content, oxidation state). Finally, the laboratory measurements do not allow direct prediction of the mineral assemblage, density and seismic velocity of the same rock composition at a different pr ...
... -5cannot be used to explore a wide range of compositional space (e.g., major element composition, H2O content, oxidation state). Finally, the laboratory measurements do not allow direct prediction of the mineral assemblage, density and seismic velocity of the same rock composition at a different pr ...
res terrae - Oulun yliopisto
... Selvatn syncline (Fig. 6), from which it can be followed to south of Ljosdalsvatnet (Fig. 5a). It also occurs in the Brattefjell area and as small outliers on the Vindeggen group (Laajoki, in print). Its general sedimentology is under study (Köykkä & Laajoki, 2006b). The formation is characterized b ...
... Selvatn syncline (Fig. 6), from which it can be followed to south of Ljosdalsvatnet (Fig. 5a). It also occurs in the Brattefjell area and as small outliers on the Vindeggen group (Laajoki, in print). Its general sedimentology is under study (Köykkä & Laajoki, 2006b). The formation is characterized b ...
Muntean/Einaudi - Nevada Bureau of Mines and Geology
... crop out in north-northeast-trending horst blocks. Four main episodes of mostly andesitic to dacitic arc magmatism occurred in the Maricunga belt from the late Oligocene to the early Pliocene (Kay et al., 1994; Mpodozis et al., 1995). The first (26–20 Ma, late Oligocene to early Miocene) and second ...
... crop out in north-northeast-trending horst blocks. Four main episodes of mostly andesitic to dacitic arc magmatism occurred in the Maricunga belt from the late Oligocene to the early Pliocene (Kay et al., 1994; Mpodozis et al., 1995). The first (26–20 Ma, late Oligocene to early Miocene) and second ...
2014-Wannamaker-Casc.. - University of Alberta
... et al., 2014]. The locked plus transition zone width increases again in northern California [Gomberg et al., 2010; Schmalzle et al., 2014] accompanied by high seismicity in both upper and lower plates, in contrast to forearc seismicity beneath Oregon [McCrory et al., 2012]. The plate here is substan ...
... et al., 2014]. The locked plus transition zone width increases again in northern California [Gomberg et al., 2010; Schmalzle et al., 2014] accompanied by high seismicity in both upper and lower plates, in contrast to forearc seismicity beneath Oregon [McCrory et al., 2012]. The plate here is substan ...
- Wiley Online Library
... et al., 2014]. The locked plus transition zone width increases again in northern California [Gomberg et al., 2010; Schmalzle et al., 2014] accompanied by high seismicity in both upper and lower plates, in contrast to forearc seismicity beneath Oregon [McCrory et al., 2012]. The plate here is substan ...
... et al., 2014]. The locked plus transition zone width increases again in northern California [Gomberg et al., 2010; Schmalzle et al., 2014] accompanied by high seismicity in both upper and lower plates, in contrast to forearc seismicity beneath Oregon [McCrory et al., 2012]. The plate here is substan ...
Acrobat PDF file - 1 Mb (text and Table 1)
... Leg 209 was devoted to drilling mantle peridotites and associated gabbroic rocks along the Mid-Atlantic Ridge from 14° to 16°N. This area was identified at the 1996 Workshop on Oceanic Lithosphere and Scientific Drilling into the 21st Century (OL Workshop) as the ideal region for drilling of a strik ...
... Leg 209 was devoted to drilling mantle peridotites and associated gabbroic rocks along the Mid-Atlantic Ridge from 14° to 16°N. This area was identified at the 1996 Workshop on Oceanic Lithosphere and Scientific Drilling into the 21st Century (OL Workshop) as the ideal region for drilling of a strik ...
DNR White Pass - Yakima Campbell
... Overpass at the base of Vanderbilt grade. Yakima River canyon begins at 3:00. The Yakima River canyon between here and Selah represents a classic example of entrenched meanders. The Yakima River was meandering across a broad basalt plain before the area was deformed into the series of east-west tren ...
... Overpass at the base of Vanderbilt grade. Yakima River canyon begins at 3:00. The Yakima River canyon between here and Selah represents a classic example of entrenched meanders. The Yakima River was meandering across a broad basalt plain before the area was deformed into the series of east-west tren ...
GEOLOGICAL SURVEY OF FINLAND Special Paper 48 2008 GTK
... map production, data management and comprehensive reporting. The work was carried out within three project components: Geological Mapping LOT 2 and LOT 3, and Geochemical and Industrial Mineral (GIM) Surveys. Project LOT 2 was implemented by GTK with the partners ITC (The Netherlands), SGU (Sweden) ...
... map production, data management and comprehensive reporting. The work was carried out within three project components: Geological Mapping LOT 2 and LOT 3, and Geochemical and Industrial Mineral (GIM) Surveys. Project LOT 2 was implemented by GTK with the partners ITC (The Netherlands), SGU (Sweden) ...
Development of the Miocene Manantiales foreland basin , Principal
... part of the upper cycle consists of deposits of an eastward inclined alluvial fan . Ages of the strata were determined from fission-track dating of zircons in four ash layers (17.1 to 11.5 Ma, with 20' uncertainties of 1.4 to 2.9 my) and magnetic polarity stratigraphy in the lower 3,000 m of the sec ...
... part of the upper cycle consists of deposits of an eastward inclined alluvial fan . Ages of the strata were determined from fission-track dating of zircons in four ash layers (17.1 to 11.5 Ma, with 20' uncertainties of 1.4 to 2.9 my) and magnetic polarity stratigraphy in the lower 3,000 m of the sec ...
Mineralogy and Petrology of Tertiary
... Willow Creek lava field. Since there have been twenty or more reversals in the Earth’s magnetic field since Eocene time (Doell and Cox, 1962), specific ages of these lavas cannot be determined from magnetic polarity, but the presence of both normal and reverse magnetization shows that the flows are ...
... Willow Creek lava field. Since there have been twenty or more reversals in the Earth’s magnetic field since Eocene time (Doell and Cox, 1962), specific ages of these lavas cannot be determined from magnetic polarity, but the presence of both normal and reverse magnetization shows that the flows are ...
accepted manuscript
... Rheological and geodynamic controls on the mechanisms of subduction and HP/UHP exhumation of crustal rocks during continental collision: Insights from numerical models. Tectonophysics, Elsevier, 2014, 631, pp.212-250. <10.1016/j.tecto.2014.04.033>.
...
... Rheological and geodynamic controls on the mechanisms of subduction and HP/UHP exhumation of crustal rocks during continental collision: Insights from numerical models. Tectonophysics, Elsevier, 2014, 631, pp.212-250. <10.1016/j.tecto.2014.04.033>.
FOSI BeritaSedimentologi BS 23 March2012
... crust then sank of its own accord and pulled the subduction zone across the Banda Sea area in a horseshoe shape. The overlying arc migrated south and east and the northern margin was largely a strike-slip margin. Backarc spreading occurred NW of the arc in the present Banda Sea. Hall (2002) infers t ...
... crust then sank of its own accord and pulled the subduction zone across the Banda Sea area in a horseshoe shape. The overlying arc migrated south and east and the northern margin was largely a strike-slip margin. Backarc spreading occurred NW of the arc in the present Banda Sea. Hall (2002) infers t ...
workshop report
... that, once formed, felsic middle crust may be almost unsubductable, and represent permanent additions to continental crust. Studies of Hf and O isotopes and U/Pb ages of tens of thousands of zircons have led to nuanced studies of continuous crustal creation and periodic preservation during most of E ...
... that, once formed, felsic middle crust may be almost unsubductable, and represent permanent additions to continental crust. Studies of Hf and O isotopes and U/Pb ages of tens of thousands of zircons have led to nuanced studies of continuous crustal creation and periodic preservation during most of E ...
Temporal variation in relative zircon abundance throughout Earth
... expected from Figure 1c. Delayed zircon saturation in Archean lithologies should result in an even more pronounced dearth of zircons in the Archean volcanic record for magmas of any given silica content consistent with the observations in Eoarchean volcaniclastic metasediments, e.g., Kamber et al. ( ...
... expected from Figure 1c. Delayed zircon saturation in Archean lithologies should result in an even more pronounced dearth of zircons in the Archean volcanic record for magmas of any given silica content consistent with the observations in Eoarchean volcaniclastic metasediments, e.g., Kamber et al. ( ...
Transfer of melts in the sub-arc mantle: Insights from high
... the southern Pacific. Most pacific islands are relatively young and formed by Cenozoic volcanic activity or carbonate platforms. Grande Terre, by contrasts, has a basement made of a Palaeozoic and Mesozoic accretionary complexes. The island is an emerged part of the Norfolk Ridge which, with the Lor ...
... the southern Pacific. Most pacific islands are relatively young and formed by Cenozoic volcanic activity or carbonate platforms. Grande Terre, by contrasts, has a basement made of a Palaeozoic and Mesozoic accretionary complexes. The island is an emerged part of the Norfolk Ridge which, with the Lor ...
Behavior of subducting sediments beneath an arc under a high
... has demonstrated that a high temperature condition required for sediment melting can be developed beneath the Setouchi area (Furukawa and Tatsumi, 1999); and (3) The Setouchi HMAs and basalt can coexist with mantle peridotite (Tatsumi, 1982). Although the mixing process of the mantle peridotite with ...
... has demonstrated that a high temperature condition required for sediment melting can be developed beneath the Setouchi area (Furukawa and Tatsumi, 1999); and (3) The Setouchi HMAs and basalt can coexist with mantle peridotite (Tatsumi, 1982). Although the mixing process of the mantle peridotite with ...
Geophysical assessment of migration and storage conditions of
... (2010) (silicate melt). Because some of these electrical measurements were performed at lower pressure than subduction conditions, the effect of increasing pressure on conductivity was accounted for by applying a correction of −0.15 log unit in electrical conductivity per gigapascal, in agreement wi ...
... (2010) (silicate melt). Because some of these electrical measurements were performed at lower pressure than subduction conditions, the effect of increasing pressure on conductivity was accounted for by applying a correction of −0.15 log unit in electrical conductivity per gigapascal, in agreement wi ...
Mechanical (de-)coupling of the lithosphere in the Valencia Trough
... The rift basin started to open during Late Oligocene over an inverted Mesozoic basin that was subjected to non-deposition and erosion during most of the Paleogene [33]. It appears that the opening was not synchronous all over the basin [34], but that rifting commenced earlier in the northeast (Late ...
... The rift basin started to open during Late Oligocene over an inverted Mesozoic basin that was subjected to non-deposition and erosion during most of the Paleogene [33]. It appears that the opening was not synchronous all over the basin [34], but that rifting commenced earlier in the northeast (Late ...
Thermal structure of the Costa Rica – Nicaragua subduction zone
... NE Costa Rica, relatively smooth Cocos crust, created at the rapid-spreading EPR, is being subducted. That sea floor is characterized by extensive trench-parallel grabens forming just seaward of the trench (Ranero et al., 2003). Southeast of the Nicoya peninsula, relatively rough Cocos crust created ...
... NE Costa Rica, relatively smooth Cocos crust, created at the rapid-spreading EPR, is being subducted. That sea floor is characterized by extensive trench-parallel grabens forming just seaward of the trench (Ranero et al., 2003). Southeast of the Nicoya peninsula, relatively rough Cocos crust created ...
Algoman orogeny
The Algoman orogeny, known as the Kenoran orogeny in Canada, was an episode of mountain-building (orogeny) during the Late Archean Eon that involved repeated episodes of continental collisions, compressions and subductions. The Superior province and the Minnesota River Valley terrane collided about 2,700 to 2,500 million years ago. The collision folded the Earth's crust and produced enough heat and pressure to metamorphose the rock. Blocks were added to the Superior province along a 1,200 km (750 mi) boundary that stretches from present-day eastern South Dakota into the Lake Huron area. The Algoman orogeny brought the Archaen Eon to a close, about 2,500 million years ago; it lasted less than 100 million years and marks a major change in the development of the earth’s crust.The Canadian shield contains belts of metavolcanic and metasedimentary rocks formed by the action of metamorphism on volcanic and sedimentary rock. The areas between individual belts consist of granites or granitic gneisses that form fault zones. These two types of belts can be seen in the Wabigoon, Quetico and Wawa subprovinces; the Wabigoon and Wawa are of volcanic origin and the Quetico is of sedimentary origin. These three subprovinces lie linearly in southwestern- to northeastern-oriented belts about 140 km (90 mi) wide on the southern portion of the Superior Province.The Slave province and portions of the Nain province were also affected. Between about 2,000 and 1,700 million years ago these combined with the Sask and Wyoming cratons to form the first supercontinent, the Kenorland supercontinent.