Fast and slow spreading ridges - Archimer
... quenched lava roofs (about 15 cm thick), generally collapsed and lying on the basaltic seafloor, and by pillars which record the different lava levels of the lakes. These features are indicative of tectonic activity and magma supply in a way ...
... quenched lava roofs (about 15 cm thick), generally collapsed and lying on the basaltic seafloor, and by pillars which record the different lava levels of the lakes. These features are indicative of tectonic activity and magma supply in a way ...
secondary planar structural elements
... Crenulation cleavage is created when an earlier foliation is folded (crenulated) on a meso- to microscale. The small, regular crinkle folds (10-1-101 mm) may be symmetric but are most commonly asymmetric. The crenulation cleavage is defined by the parallel alignment of grains in the limbs of the tig ...
... Crenulation cleavage is created when an earlier foliation is folded (crenulated) on a meso- to microscale. The small, regular crinkle folds (10-1-101 mm) may be symmetric but are most commonly asymmetric. The crenulation cleavage is defined by the parallel alignment of grains in the limbs of the tig ...
Chapter 15. The Hard Rock Cafe
... mantle is basalt and eclogites are the highpressure forms of basalts. The term 'eclogite' refers to rocks composed of omphacite (diopside plus jadeite) and garnet, occasionally accompanied by kyanite, zoisite, amphibole, quartz and pyrrhotite. Natural eclogites have a variety of associations, chemis ...
... mantle is basalt and eclogites are the highpressure forms of basalts. The term 'eclogite' refers to rocks composed of omphacite (diopside plus jadeite) and garnet, occasionally accompanied by kyanite, zoisite, amphibole, quartz and pyrrhotite. Natural eclogites have a variety of associations, chemis ...
isotope geology and fennoscandian lithosphere evolution
... Finland ever since its inception in the early sixties. The main analytical methods used have been U-Pb, Sm-Nd, Rb-Sr, Pb-Pb and light stable isotopes, and with the recent LA-MC-ICPMS instrument installation, the repertoire is increasing. Isotope research has contributed to many joint projects over a ...
... Finland ever since its inception in the early sixties. The main analytical methods used have been U-Pb, Sm-Nd, Rb-Sr, Pb-Pb and light stable isotopes, and with the recent LA-MC-ICPMS instrument installation, the repertoire is increasing. Isotope research has contributed to many joint projects over a ...
Commentary on schematic geological map of Antarctica Scale 1:10
... canics (Mvt , Czv). It is not clear when the terranes were (Carboniferous) for the subsequent metamorphism; no Precambrian ages have been obtained. juxtaposed: the inference (Ganovex Team , 1987) that Devonian granites are present in all three terrane suggests - Second , ince 1970, a considerable re ...
... canics (Mvt , Czv). It is not clear when the terranes were (Carboniferous) for the subsequent metamorphism; no Precambrian ages have been obtained. juxtaposed: the inference (Ganovex Team , 1987) that Devonian granites are present in all three terrane suggests - Second , ince 1970, a considerable re ...
A2 Course Study Guide
... Viscosity is one of those concepts which can be usefully banded about conversationally, but which are mine fields of complexity when used quantitatively. In everyday terms, viscosity describes the sluggishness of fluid; its resistance to being stirred. Notice the term fluid, rather than liquid: the ...
... Viscosity is one of those concepts which can be usefully banded about conversationally, but which are mine fields of complexity when used quantitatively. In everyday terms, viscosity describes the sluggishness of fluid; its resistance to being stirred. Notice the term fluid, rather than liquid: the ...
GLG101online_08A_Metamorphism_MCC_Leighty
... Typically occurs near intrusions (batholiths, dikes, sills, etc.) The bigger the intrusion, the bigger the contact zone ...
... Typically occurs near intrusions (batholiths, dikes, sills, etc.) The bigger the intrusion, the bigger the contact zone ...
GEOLOGICAL RELATIONSHIPS IN NORTHWESTERN FOGO
... (gabbro dated at 424 ± 2 Ma; Dickson et al., 2007), the Fogo Island intrusion (for which sparse U–Pb data suggest an age of ca. 421 Ma; Aydin, 1995), and the Loon Bay granite (ca. 410 Ma; Elliot et al., 1991). Some of these plutonic suites clearly intrude the Badger Group, and others intrude sedimen ...
... (gabbro dated at 424 ± 2 Ma; Dickson et al., 2007), the Fogo Island intrusion (for which sparse U–Pb data suggest an age of ca. 421 Ma; Aydin, 1995), and the Loon Bay granite (ca. 410 Ma; Elliot et al., 1991). Some of these plutonic suites clearly intrude the Badger Group, and others intrude sedimen ...
Structural Controls of the Tuscarora Geothermal Field Elko County
... temperature Great Basin geothermal fields currently in production or development and classified as an accommodation zone. Others include Brady’s, Salt Wells, and McGinness Hills (Faulds et al., 2011). The detailed work at Tuscarora highlights the importance of accommodation zones in controlling geot ...
... temperature Great Basin geothermal fields currently in production or development and classified as an accommodation zone. Others include Brady’s, Salt Wells, and McGinness Hills (Faulds et al., 2011). The detailed work at Tuscarora highlights the importance of accommodation zones in controlling geot ...
Geology and volcanic setting of the Horne deposit, Rouyn
... zone consists of numerous lenses of massive pyrite interbedded with intensely altered felsic volcaniclastic rocks. The No. 5 zone extends for a strike length of more than 1000 m to a depth of at least 2650 m and ranges from approximately 30 m to 140 m in thickness (Sinclair, 1971; Fisher, 1974; Gibs ...
... zone consists of numerous lenses of massive pyrite interbedded with intensely altered felsic volcaniclastic rocks. The No. 5 zone extends for a strike length of more than 1000 m to a depth of at least 2650 m and ranges from approximately 30 m to 140 m in thickness (Sinclair, 1971; Fisher, 1974; Gibs ...
A Comparative Study of the Badger Pass Igneous Intrusion and the
... The igneous rocks of these two areas--the McDowell Springs area and the Badger Pass area--separated by several kilometers of horizontal distance and over one hundred meters of elevation, differ in field appearance, and distinguish themselves through their dissimilar structural relationships to their ...
... The igneous rocks of these two areas--the McDowell Springs area and the Badger Pass area--separated by several kilometers of horizontal distance and over one hundred meters of elevation, differ in field appearance, and distinguish themselves through their dissimilar structural relationships to their ...
1 - Shodhganga
... 4. Carbonatite rocks are rich in monazite and barite. 5. The associated albitite or oligoclasite rocks contain plenty of sphene and allanite which are not common to carbonatite complexes. From the above observations he concludes that the carbonate rocks of Pakkanadu can represent some late phase of ...
... 4. Carbonatite rocks are rich in monazite and barite. 5. The associated albitite or oligoclasite rocks contain plenty of sphene and allanite which are not common to carbonatite complexes. From the above observations he concludes that the carbonate rocks of Pakkanadu can represent some late phase of ...
Petrology and tectonics of Phanerozoic continent formation: From
... be linked in space and time. Subduction of the Farallon plate beneath North America during the Triassic to early Cretaceous was characterized by trench retreat and slab rollback because old and cold oceanic lithosphere was being subducted. This generated an extensional subduction zone, which created ...
... be linked in space and time. Subduction of the Farallon plate beneath North America during the Triassic to early Cretaceous was characterized by trench retreat and slab rollback because old and cold oceanic lithosphere was being subducted. This generated an extensional subduction zone, which created ...
Gravity modeling of the lithosphere in the Calatrava
... to understand better the aforementioned geodynamic scenarios for the origin of the CVP, we address here the study of the lithosphere in the CVP and its vicinity by means of gravity analysis and 2+1/2D modeling. Gravity modeling results do not support the rifting model adopted for the intraplate volc ...
... to understand better the aforementioned geodynamic scenarios for the origin of the CVP, we address here the study of the lithosphere in the CVP and its vicinity by means of gravity analysis and 2+1/2D modeling. Gravity modeling results do not support the rifting model adopted for the intraplate volc ...
GEOLOGY OF PRE-MESOZOIC BEDROCK OF THE AMHERST
... places and in other places by east-dipping normal faults of small displacement (Wheeler, 1937; Krynine, 1950). The northern basin, called the Montague (Emerson, 1917; Goldstein,1976) or Deerfield basin (Chandler, 1978), extends 24 km northward from Amherst to the vicinity of Bernardston, Massachuset ...
... places and in other places by east-dipping normal faults of small displacement (Wheeler, 1937; Krynine, 1950). The northern basin, called the Montague (Emerson, 1917; Goldstein,1976) or Deerfield basin (Chandler, 1978), extends 24 km northward from Amherst to the vicinity of Bernardston, Massachuset ...
Flat versus steep subduction: Contrasting modes for the formation
... designed with three major domains (from left to right, Fig. 1): (1) a procontinental domain, (2) an oceanic domain, and (3) a retro-continental domain. The spontaneous deformation of the upper surface of the lithosphere, i.e. topography, is calculated dynamically as an internal free surface by using ...
... designed with three major domains (from left to right, Fig. 1): (1) a procontinental domain, (2) an oceanic domain, and (3) a retro-continental domain. The spontaneous deformation of the upper surface of the lithosphere, i.e. topography, is calculated dynamically as an internal free surface by using ...
Paper 3.2 Mb pdf - Miles F Osmaston
... wall, builds a subcreted triangular section extending far down the back wall, much further than hitherto thought possible. So this part exhumes the most, breaking through the “roof” above as a fault-line prone to strike-slip (Insubric, Møre-Trøndelag, Median Tectonic Line). In the Alps, and followin ...
... wall, builds a subcreted triangular section extending far down the back wall, much further than hitherto thought possible. So this part exhumes the most, breaking through the “roof” above as a fault-line prone to strike-slip (Insubric, Møre-Trøndelag, Median Tectonic Line). In the Alps, and followin ...
Perspectives on the origin of plagiogranite in ophiolites from oxygen
... with diverse primary magmatic δ18O values forming proximal to the magmatic center where crustal growth is occurring. To constrain the magmatic δ18O of a wide range of silicic rocks in oceanic crust and evaluate their petrogenesis, we characterized the δ18O of zircons in 22 plagiogranite samples (ton ...
... with diverse primary magmatic δ18O values forming proximal to the magmatic center where crustal growth is occurring. To constrain the magmatic δ18O of a wide range of silicic rocks in oceanic crust and evaluate their petrogenesis, we characterized the δ18O of zircons in 22 plagiogranite samples (ton ...
Towards absolute plate motions constrained by lower
... lower mantle and link these to the mountain building zones from which they are likely to have originated. Assuming that these remnants sank vertically through the mantle, we reconstruct the longitude at which they were subducted. Our estimates for the location of the subduction zones are offset by u ...
... lower mantle and link these to the mountain building zones from which they are likely to have originated. Assuming that these remnants sank vertically through the mantle, we reconstruct the longitude at which they were subducted. Our estimates for the location of the subduction zones are offset by u ...
Generation of high-silica rhyolite: A Nd, Sr, and O isotopic study of
... all erupted within a period shorter than 5-10 ky. About 75 ky ago, a new group of ring domes (e.g., Sample 174) erupted at the southern margin of the lake. Subsequent uplift due to magmatic insurgence caused the lake to drain and culminated about 60 ky ago in eruption of aphyric lavas (e.g., Sample ...
... all erupted within a period shorter than 5-10 ky. About 75 ky ago, a new group of ring domes (e.g., Sample 174) erupted at the southern margin of the lake. Subsequent uplift due to magmatic insurgence caused the lake to drain and culminated about 60 ky ago in eruption of aphyric lavas (e.g., Sample ...
Dipping reflector sequences in the vicinity of the continent
... identified over the northwestern edge of the plateau confirms the oceanic (and thus predominantly basaltic) nature of the suprabasement material. The implications of the interpretations of both of these workers for the definition of the legal continental 'shelf' however, (sensu article 76, of the LO ...
... identified over the northwestern edge of the plateau confirms the oceanic (and thus predominantly basaltic) nature of the suprabasement material. The implications of the interpretations of both of these workers for the definition of the legal continental 'shelf' however, (sensu article 76, of the LO ...
Generation of new continental crust by sublithospheric silicic
... of the most debated topic in relation to the generation of the rocks forming the continental crust is given in the next section with the aim of offering a reference framework on the problem of continental crust generation. 2. Taylor's andesite model: An overview on the origin of upper and lower cont ...
... of the most debated topic in relation to the generation of the rocks forming the continental crust is given in the next section with the aim of offering a reference framework on the problem of continental crust generation. 2. Taylor's andesite model: An overview on the origin of upper and lower cont ...
Tectono-stratigraphic framework of Neoproterozoic to Cambrian
... carbonate-rich strata were deposited in shallow marine settings, with episodic influx of siliciclastic sediment derived from basement exposed during regressions. Stratigraphic thickness-age relations of Neoproterozoic to early Paleozoic strata are consistent with two episodes of rifting concentrated ...
... carbonate-rich strata were deposited in shallow marine settings, with episodic influx of siliciclastic sediment derived from basement exposed during regressions. Stratigraphic thickness-age relations of Neoproterozoic to early Paleozoic strata are consistent with two episodes of rifting concentrated ...
Metamorphic chemical geodynamics of subduction zones
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
... Nb/U, Rb/Cs), that is, ratios for which values for mantlederived lavas (arc lavas, ocean island basalts) reflect the values of their source regions rather than reflecting later ...
Great Lakes tectonic zone
The Great Lakes tectonic zone is bounded by South Dakota at its tip and heads northeast to south of Duluth, Minnesota, then heads east through northern Wisconsin, Marquette, Michigan, and then trends more northeasterly to skim the northern-most shores of lakes Michigan and Huron before ending in the Sudbury, Ontario, Canada, area.During the Late Archean Era the Algoman orogeny added landmass to the Superior province by volcanic activity and continental collision along a boundary that stretches from present-day South Dakota, U.S., into the Lake Huron region near Sudbury, Ontario, Canada.This crustal boundary is the Great Lakes tectonic zone. It is 1,400 km (870 mi) long, and separates the older Archean gneissic terrane to the south from younger Late Archean greenstone-granite terrane to the north.The zone is characterized by active compression during the Algoman orogeny (about 2,700 million years ago), a pulling-apart (extensional) tectonics (2,450 to 2,100 million years ago), a second compression during the Penokean orogeny (1,900 to 1,850 million years ago), a second extension during Middle Proterozoic time (1,600 million years ago) and minor reactivation during Phanerozoic time (the past 500 million years).Collision began along the Great Lakes tectonic zone (GLTZ) with the Algoman mountain-building event and continued for tens of millions of years. During the formation of the GLTZ, the gneissic Minnesota River Valley subprovince was thrust up onto the Superior province's edge as it consumed the Superior province's oceanic crust. Fragmentation of the Kenorland supercontinent began 2,450 million years ago and was completed by 2,100 million years ago. The Wyoming province is the continental landmass that is hypothesized to have rifted away from the southern Superior province portion of Kenorland, before moving rapidly west and docking with the Laurentia supercontinent 1,850 to 1,715 million years ago. Sedimentation from the GLTZ-rifting environment continued into the Penokean orogeny, which is the next major tectonic event in the Great Lakes region. Several earthquakes have been documented in Minnesota, Michigan's Upper Peninsula and Sudbury in the last 120 years along the GLTZ.