"postorogenie" magmatism
... postdate deformed orogenie granites, some formed later, by as much as 40 m.y. This time lag between magmatic pulses does not necessarily imply any lag between the end of deformation and the first appearance of nondeformed granites. Features such as miarolitic cavities, granophyric intergrowths, and ...
... postdate deformed orogenie granites, some formed later, by as much as 40 m.y. This time lag between magmatic pulses does not necessarily imply any lag between the end of deformation and the first appearance of nondeformed granites. Features such as miarolitic cavities, granophyric intergrowths, and ...
- NERC Open Research Archive
... Land and southern Graham Land, with sparser outcrops in eastern Graham Land. The metamorphic basement is most extensive in Palmer Land, with orthogneisses, paragneisses, amphibolites and metasediments recording amphibolite- to granulite-facies metamorphism in NW Palmer Land, and lower grade amphibol ...
... Land and southern Graham Land, with sparser outcrops in eastern Graham Land. The metamorphic basement is most extensive in Palmer Land, with orthogneisses, paragneisses, amphibolites and metasediments recording amphibolite- to granulite-facies metamorphism in NW Palmer Land, and lower grade amphibol ...
Geophysical and Geochemical Constraints at Converging Plate
... temperatures or melting. Geophysical models, thus, must provide a special mechanism for generation of melting either within the underthrusting slab or in the surrounding mantle. (b) The heat flow pattern in the region of subduction provides another boundary condition. Distinct zones of low and high ...
... temperatures or melting. Geophysical models, thus, must provide a special mechanism for generation of melting either within the underthrusting slab or in the surrounding mantle. (b) The heat flow pattern in the region of subduction provides another boundary condition. Distinct zones of low and high ...
A unique lower mantle source for Southern Italy volcanics
... high U/Pb (HIMU) end-members [Gasperini, D., Blichert-Toft, J., Bosch, D., Del Moro, A., Macera, P., Albarède, F., 2002. Upwelling of deep mantle material through a plate window: Evidence from the geochemistry of Italian basaltic volcanics, J. Geophys. Res. 107, 2367–2386], whereas an alternative vi ...
... high U/Pb (HIMU) end-members [Gasperini, D., Blichert-Toft, J., Bosch, D., Del Moro, A., Macera, P., Albarède, F., 2002. Upwelling of deep mantle material through a plate window: Evidence from the geochemistry of Italian basaltic volcanics, J. Geophys. Res. 107, 2367–2386], whereas an alternative vi ...
phosphate rock - NSW Department of Primary Industries
... continent and range in age from Precambrian to Recent, although almost all exploited deposits are Phanerozoic in age (Bartels & Gurr 1994). About 80% of phosphate rock used commercially is obtained from marine sedimentary deposits (phosphorites) (Harben & Kužvart 1996). Large resources of phosphates ...
... continent and range in age from Precambrian to Recent, although almost all exploited deposits are Phanerozoic in age (Bartels & Gurr 1994). About 80% of phosphate rock used commercially is obtained from marine sedimentary deposits (phosphorites) (Harben & Kužvart 1996). Large resources of phosphates ...
Constraints on the Lithospheric Structure of Venus from Mechanical
... on the basis of Venera lander results that show surface rocks ...
... on the basis of Venera lander results that show surface rocks ...
II . K
... with sharp contact on underlying tuffaceous rocks. The basal few millimetres of the flows generally show very fine, streaky, eutaxitic-like banding which rapidly grades, with devitrification, into the massive zone. Fiamme are found at the bases of flows at only a few localities. It can be seen that ...
... with sharp contact on underlying tuffaceous rocks. The basal few millimetres of the flows generally show very fine, streaky, eutaxitic-like banding which rapidly grades, with devitrification, into the massive zone. Fiamme are found at the bases of flows at only a few localities. It can be seen that ...
Geology of the Eagle Mountains, Hudspeth County, Texas
... Eagle Mountains and the associated highlands, Devil Ridge and Indio Mountains, trending generally northwest to northnorthwest, are surrounded by "bolsons" or intermontane basins partly filled with alluvium and are an extension into southeastern Hudspeth County of the eastern part of a long, narrow, ...
... Eagle Mountains and the associated highlands, Devil Ridge and Indio Mountains, trending generally northwest to northnorthwest, are surrounded by "bolsons" or intermontane basins partly filled with alluvium and are an extension into southeastern Hudspeth County of the eastern part of a long, narrow, ...
Deep-Seated Mass Rock Creep Along The Karakoram
... smooth ridge. As one can see on the picture (Plate 1) it abruptly rises to more than 5m at the downslope side and still seems to move by rotating out of the slope and turning down to the valley. The lack of varnish at the rim suggests an ongoing movement. At any rate this curious rock represents a c ...
... smooth ridge. As one can see on the picture (Plate 1) it abruptly rises to more than 5m at the downslope side and still seems to move by rotating out of the slope and turning down to the valley. The lack of varnish at the rim suggests an ongoing movement. At any rate this curious rock represents a c ...
Physical Geology Laboratory Manual - e
... Minerals are defined to be naturally occurring, inorganic, crystalline substances. A mineral's name is a class name that refers simultaneously to two criteria: chemical composition and symmetry of internal crystal structure. Symmetry of internal crystal structure is fixed for each mineral. Chemical ...
... Minerals are defined to be naturally occurring, inorganic, crystalline substances. A mineral's name is a class name that refers simultaneously to two criteria: chemical composition and symmetry of internal crystal structure. Symmetry of internal crystal structure is fixed for each mineral. Chemical ...
Master Degree in Applied Geological Sciences
... The course is aimed at providing students with concepts and tools to understand the structural complexity of inorganic solids, by using examples of minerals and technological materials. Starting point is the description of the ideal crystal, then the course describes the transformation and deformati ...
... The course is aimed at providing students with concepts and tools to understand the structural complexity of inorganic solids, by using examples of minerals and technological materials. Starting point is the description of the ideal crystal, then the course describes the transformation and deformati ...
Early Ordovician rifting of Avalonia and birth of the Rheic Ocean: U
... thick and formed between 635 and 570 Ma. West to east, these rocks include the Marystown, Love Cove and Harbour Main groups, which have calk-alkaline to transitional and island arc (arc-rift) tholeiitic affinities. Radiogenic isotopic analysis of these rocks yield the following U–Pb ages: 631 2 Ma ...
... thick and formed between 635 and 570 Ma. West to east, these rocks include the Marystown, Love Cove and Harbour Main groups, which have calk-alkaline to transitional and island arc (arc-rift) tholeiitic affinities. Radiogenic isotopic analysis of these rocks yield the following U–Pb ages: 631 2 Ma ...
Formation of plate boundaries: The role of mantle volatilization
... forearc mantle is embedded in a suture zone of a supercontinent (left) and in a rifted margin or relict arc (upper). Any thermal event like an upwelling plume shrinks the serpentinized forearc mantle by dehydration, which weakens its boundaries by the release of pressurized water (see text). If the ...
... forearc mantle is embedded in a suture zone of a supercontinent (left) and in a rifted margin or relict arc (upper). Any thermal event like an upwelling plume shrinks the serpentinized forearc mantle by dehydration, which weakens its boundaries by the release of pressurized water (see text). If the ...
Crustal contamination of mafic magmas: evidence from a
... agreement that mafic mantle-derived magmas experience some degree of crustal contamination during ascent and/or residence in crustal magma chambers (Mohr, 1987). The crust is both a density filter and a source of incompatible elements (Lightfoot et al., 1991) and it may act as a site of extensive an ...
... agreement that mafic mantle-derived magmas experience some degree of crustal contamination during ascent and/or residence in crustal magma chambers (Mohr, 1987). The crust is both a density filter and a source of incompatible elements (Lightfoot et al., 1991) and it may act as a site of extensive an ...
Ascent of the ultrahigh-pressure Western Gneiss Region, Norway.
... (Mposkos and Kostopoulos, 2001) and the inferred decomposition of dolomite to aragonite + magnesite at Kokchetav (Zhu and Ogasawara, 2002) and in the Tian Shan (Zhang et al., 2003) (but see Klemd et al., 2003) require exhumation of bona fide continental crust from depths >150–250 km and further high ...
... (Mposkos and Kostopoulos, 2001) and the inferred decomposition of dolomite to aragonite + magnesite at Kokchetav (Zhu and Ogasawara, 2002) and in the Tian Shan (Zhang et al., 2003) (but see Klemd et al., 2003) require exhumation of bona fide continental crust from depths >150–250 km and further high ...
Karson, J.A., and Lawrence, R.M., 1997. Tectonic setting of
... length of a well-defined ridge segment parallel to a prominent neovolcanic ridge. It terminates in a segment boundary zone to the south marked by a bathymetric depression whose trace extends obliquely off axis northwestward into older crust where serpentinites have also been dredged. The seΦentinite ...
... length of a well-defined ridge segment parallel to a prominent neovolcanic ridge. It terminates in a segment boundary zone to the south marked by a bathymetric depression whose trace extends obliquely off axis northwestward into older crust where serpentinites have also been dredged. The seΦentinite ...
Older crust underlies Iceland
... The requirement for older, submerged crust beneath the younger lavas is in full agreement with the crustal accretion model of Palmason (1973, 1980). This model shows how the volcanic pile subsides beneath the weight of new erupted lavas as crustal accretion proceeds. Lavas may flow for long distance ...
... The requirement for older, submerged crust beneath the younger lavas is in full agreement with the crustal accretion model of Palmason (1973, 1980). This model shows how the volcanic pile subsides beneath the weight of new erupted lavas as crustal accretion proceeds. Lavas may flow for long distance ...
week6min.2002
... Less abundant than hematite but richer in Fe (and easier to separate economically from the gangue minerals surrounding it, because of its magnetism), magnetite is an important ore mineral when it occurs in massive aggregates. It is also rather common as small scattered crystals in many magmatic, met ...
... Less abundant than hematite but richer in Fe (and easier to separate economically from the gangue minerals surrounding it, because of its magnetism), magnetite is an important ore mineral when it occurs in massive aggregates. It is also rather common as small scattered crystals in many magmatic, met ...
Seismic re¯ection image revealing offset of Andean subduction
... shallow part of this re¯ector (down to 70 km) to the subduction shear zone and the Nacza plate oceanic crust. The deepest, `brightest' part of the Nazca re¯ector is slightly ¯atter, and could either image the top of the subduction shear zone or be located a few kilometres above it. The downdip incre ...
... shallow part of this re¯ector (down to 70 km) to the subduction shear zone and the Nacza plate oceanic crust. The deepest, `brightest' part of the Nazca re¯ector is slightly ¯atter, and could either image the top of the subduction shear zone or be located a few kilometres above it. The downdip incre ...
2. - Teacher Friendly Guides
... science is a subject to be explored in one’s own neighborhood, examining the detailed sequence of rocks for the history that has gone on under our feet. What is not possible from only one location is making sense of why this particular sequence of events took place when and where it did, particularl ...
... science is a subject to be explored in one’s own neighborhood, examining the detailed sequence of rocks for the history that has gone on under our feet. What is not possible from only one location is making sense of why this particular sequence of events took place when and where it did, particularl ...
faulting - The Web site cannot be found
... Because most rocks are brittle at low temperature and low confining (lithostatic) pressure, virtually every rock at or near the Earth’s surface exhibits evidence of brittle failure, i.e. deformation-induced loss of cohesion. Brittle failure results from the irreversible and very rapid propagation an ...
... Because most rocks are brittle at low temperature and low confining (lithostatic) pressure, virtually every rock at or near the Earth’s surface exhibits evidence of brittle failure, i.e. deformation-induced loss of cohesion. Brittle failure results from the irreversible and very rapid propagation an ...
Lasting mantle scars lead to perennial plate tectonics
... of stress build-up shifts to produce pseudo-subduction of the crust into the ML. The implementation of wet anorthite for the LC generates a layer that is not primed for failure (even with regions of designated weakness). The wet anorthite flow law generates a weak LC that plays no role in the deforma ...
... of stress build-up shifts to produce pseudo-subduction of the crust into the ML. The implementation of wet anorthite for the LC generates a layer that is not primed for failure (even with regions of designated weakness). The wet anorthite flow law generates a weak LC that plays no role in the deforma ...
Review and Practice for the Earth Science SOL
... Spend time reading the Essential Questions shown with each unit. See if you can answer the questions that are being asked. If you are having difficulty answering questions in a particular unit, spend more time reviewing those sections in the pages that discusses each topic. Analyze the Sample SOL Qu ...
... Spend time reading the Essential Questions shown with each unit. See if you can answer the questions that are being asked. If you are having difficulty answering questions in a particular unit, spend more time reviewing those sections in the pages that discusses each topic. Analyze the Sample SOL Qu ...
(VMS) Deposits - Department of Natural Resources
... generally a very effective VMS exploration technique in Newfoundland. If you can’t sell your prospect as it is, consider doing a small soil geochemical survey to demonstrate untested potential. Geophysical Anomalies: EM, IP, magnetic and gravity surveys are the most common geophysical methods used i ...
... generally a very effective VMS exploration technique in Newfoundland. If you can’t sell your prospect as it is, consider doing a small soil geochemical survey to demonstrate untested potential. Geophysical Anomalies: EM, IP, magnetic and gravity surveys are the most common geophysical methods used i ...
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.