Shock metamorphism of siliceous volcanic rocks of the El`gygytgyn
... been recognized and confirmed more than 20 years ago, an endogenic origin for this structure was once again proposed during the 1990s by Beliy (1982, 1998). In recent years, the post-impact geological and climatic history of the area around El’gygytgyn crater and, especially, its sedimentary record, ...
... been recognized and confirmed more than 20 years ago, an endogenic origin for this structure was once again proposed during the 1990s by Beliy (1982, 1998). In recent years, the post-impact geological and climatic history of the area around El’gygytgyn crater and, especially, its sedimentary record, ...
Geology and Landforms Factsheet - the Dartmoor National Park
... geology. Most of Dartmoor consists of a single type of rock - granite. This granite was intruded during the late Carboniferous/ early Permian Period (around 280 million years ago) into the area we now know as Devon and Cornwall. From the Isles of Scilly to Dartmoor, a number of granite domes are lin ...
... geology. Most of Dartmoor consists of a single type of rock - granite. This granite was intruded during the late Carboniferous/ early Permian Period (around 280 million years ago) into the area we now know as Devon and Cornwall. From the Isles of Scilly to Dartmoor, a number of granite domes are lin ...
thrust systems - The Web site cannot be found
... - Collision tectonics involves thickening and imbrication of the crust and lithospheric mantle when the ocean closes. Hence an orogenic belt is generally aligned along a zone of continental collision. Deformation produces excess topography (mountain range) that erosion modifies and destroys on a lon ...
... - Collision tectonics involves thickening and imbrication of the crust and lithospheric mantle when the ocean closes. Hence an orogenic belt is generally aligned along a zone of continental collision. Deformation produces excess topography (mountain range) that erosion modifies and destroys on a lon ...
The rift-related mafic dyke complex of the Rohkunborri Nappe, Indre
... Rohkunborri and Njunis areas. In these areas the dolerite swarm intrudes a succession of carbonate rocks and subordinate sandstones, siltstones and quartzites. The sedimentary rocks, the Njunis Group, are supposed to represent the outermost part of the clastic wedge deposited during Neoproterozoic-e ...
... Rohkunborri and Njunis areas. In these areas the dolerite swarm intrudes a succession of carbonate rocks and subordinate sandstones, siltstones and quartzites. The sedimentary rocks, the Njunis Group, are supposed to represent the outermost part of the clastic wedge deposited during Neoproterozoic-e ...
The VMS Model: Advances and Application to Exploration Targeting
... deposits are major sources of Cu and Zn and, to a lesser extent, Pb, Ag, Au, Cd, Se, Sn, Bi and minor amounts of other metals, such as indium (Franklin et al., 2005). The metal contents and tonnage of VMS deposits are log normally distributed but, as indicated by geometric means that range from 2.7 ...
... deposits are major sources of Cu and Zn and, to a lesser extent, Pb, Ag, Au, Cd, Se, Sn, Bi and minor amounts of other metals, such as indium (Franklin et al., 2005). The metal contents and tonnage of VMS deposits are log normally distributed but, as indicated by geometric means that range from 2.7 ...
Near-Ultrahigh Pressure Processing of Continental Crust: Miocene
... most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures ...
... most abundant minor phases. Hydrous phases (biotite and phengite in felsic granulites and basaltic eclogites, amphiboles in mafic and sanidine eclogites) and plagioclase form minor inclusions in garnet or kyanite. Solid-phase thermobarometry reveals recrystallization at mainly ultrahigh temperatures ...
Christiansen, EH, and Keith, JD, 1996, Trace
... magma (crystals plus liquid). After magma segregation, restitic mineral phases may become dissolved at lower pressure or after continued reaction with the melt. However, restite unmixing is probably not important in the generation of the observed elemental trends in rhyolites and granites, except so ...
... magma (crystals plus liquid). After magma segregation, restitic mineral phases may become dissolved at lower pressure or after continued reaction with the melt. However, restite unmixing is probably not important in the generation of the observed elemental trends in rhyolites and granites, except so ...
Evolution of the continental crust
... crust is generated, and the amounts of residual crustal material recycled back into the mantle. The degree of differentiation can be estimated from the compositions of model new crust and the upper continental crust19. Calculations reveal that the upper crust reflects ,14% partial melting, or the an ...
... crust is generated, and the amounts of residual crustal material recycled back into the mantle. The degree of differentiation can be estimated from the compositions of model new crust and the upper continental crust19. Calculations reveal that the upper crust reflects ,14% partial melting, or the an ...
here - GeoPRISMS
... spectrum of stages of continental breakup, with increased emphasis on the interplay between surface processes, sedimentation, and continental evolution. It will include early-stage rifts but also the study of passive margins, which archive the entire history of rift zone construction and evolution. ...
... spectrum of stages of continental breakup, with increased emphasis on the interplay between surface processes, sedimentation, and continental evolution. It will include early-stage rifts but also the study of passive margins, which archive the entire history of rift zone construction and evolution. ...
A Pictorial Guide to Metamorphic Rocks in the Field
... planes of easy breaking. These are controlled by planes of particularly weak atomic bonds in the crystal lattice, spaced at an atomic scale. For rocks, cleavage in its most primitive sense refers to similar parallel-aligned planes or curved surfaces along which the rock breaks easily. Slate (Fig. 2. ...
... planes of easy breaking. These are controlled by planes of particularly weak atomic bonds in the crystal lattice, spaced at an atomic scale. For rocks, cleavage in its most primitive sense refers to similar parallel-aligned planes or curved surfaces along which the rock breaks easily. Slate (Fig. 2. ...
A. M. Celâl ŞENGÖR, Boris A. NATAL`IN, Gürsel
... extension related to the late Altaid strike-slip activity and they too have alkalic magmatism associated with them. Some of the alkalic granites not related to the late strike-slip activity may have been related to slab fall-off after terminal collisions, although this is now difficult to document w ...
... extension related to the late Altaid strike-slip activity and they too have alkalic magmatism associated with them. Some of the alkalic granites not related to the late strike-slip activity may have been related to slab fall-off after terminal collisions, although this is now difficult to document w ...
On the Structure and Seismotectonics of the Kuril Arc Trench System
... Abstract—Based on the new regional catalog of focal mechanisms for 396 strong (M ≥ 6.0) earthquakes in the KurilOkhotsk region and Japanese one in part for the period of 1964–2009 and with the data of seismic continuous profiling and multichannel commondepth point sounding by reflection method use ...
... Abstract—Based on the new regional catalog of focal mechanisms for 396 strong (M ≥ 6.0) earthquakes in the KurilOkhotsk region and Japanese one in part for the period of 1964–2009 and with the data of seismic continuous profiling and multichannel commondepth point sounding by reflection method use ...
Kinematics of the South Atlantic rift
... significant rotation of the extension direction to NE–SW. From base Aptian onwards diachronous lithospheric breakup occurred along the central South Atlantic rift, first in the Sergipe–Alagoas/Rio Muni margin segment in the northernmost South Atlantic. Final break-up between South America and Africa ...
... significant rotation of the extension direction to NE–SW. From base Aptian onwards diachronous lithospheric breakup occurred along the central South Atlantic rift, first in the Sergipe–Alagoas/Rio Muni margin segment in the northernmost South Atlantic. Final break-up between South America and Africa ...
Geological framework and mineralization of Papua New Guinea
... terranes along the northern margin of the Australian Plate (Dow, 1977; Hall, 2002; Klootwijk et al., 2003; Quarles van Ufford and Cloos, 2005; Davies, 2009). The thickness and strength of the Australian basement, along with the presence of large extensional structures formed during rifting of the ma ...
... terranes along the northern margin of the Australian Plate (Dow, 1977; Hall, 2002; Klootwijk et al., 2003; Quarles van Ufford and Cloos, 2005; Davies, 2009). The thickness and strength of the Australian basement, along with the presence of large extensional structures formed during rifting of the ma ...
Mechanisms for folding of high-grade rocks in extensional tectonic
... may alternate with areas of contraction during block rotation between transcurrent faults at an arcuate margin (Garfunkel and Ron, 1985; Geist et al., 1988). Local contractional or extensional sites also ...
... may alternate with areas of contraction during block rotation between transcurrent faults at an arcuate margin (Garfunkel and Ron, 1985; Geist et al., 1988). Local contractional or extensional sites also ...
UHP metamorphism in garnet peridotite, Cuaba unit, Rio San Juan
... Four attributes suggest low-P/T (UHT) conditions: (1) Sequence of mineral assemblages, (2) nature of associated rocks, (3) Cr-in-clinopyroxene, Mg2Si2O6-in-clinopyroxene thermobarometry (>1.8 Gpa, >900 ˚C), and (4) tectonic setting. However, the thermobarometry is questionable because of low Cr in c ...
... Four attributes suggest low-P/T (UHT) conditions: (1) Sequence of mineral assemblages, (2) nature of associated rocks, (3) Cr-in-clinopyroxene, Mg2Si2O6-in-clinopyroxene thermobarometry (>1.8 Gpa, >900 ˚C), and (4) tectonic setting. However, the thermobarometry is questionable because of low Cr in c ...
- AMS Tesi di Dottorato
... is the top of a peridotitic massif that extends in the direction of the active transform fault and it is now a left overstep undergoing transpression. Markers of sea level dated by 14C estimate a rate of uplift of the St. Paul Massif of about 1.5 mm/a for the last 6000 years. During my PhD, a multid ...
... is the top of a peridotitic massif that extends in the direction of the active transform fault and it is now a left overstep undergoing transpression. Markers of sea level dated by 14C estimate a rate of uplift of the St. Paul Massif of about 1.5 mm/a for the last 6000 years. During my PhD, a multid ...
Mechanisms of crustal growth in large igneous
... emplaced during a relatively short time span. Some authors have used sedimentary records (White and Lovell, 1997) and wide-angle seismic surveys (Al-Kindi et al., 2003) to argue that magma underplating may also occur during this early stage. During trap emplacement, tectonic extension is usually sma ...
... emplaced during a relatively short time span. Some authors have used sedimentary records (White and Lovell, 1997) and wide-angle seismic surveys (Al-Kindi et al., 2003) to argue that magma underplating may also occur during this early stage. During trap emplacement, tectonic extension is usually sma ...
palaeozoic porphyry molybdenum-tungsten deposit in the myszków
... Abstract. The Myszków porphyry molybdenum-tungsten deposit is one of several porphyry copper-type deposits that have been identified within a poorly defined belt of Precambrian to Palaeozoic rocks in south-central Poland. It is in a complex of Proterozoic (Vendian) to early Palaeozoic (Early Cambria ...
... Abstract. The Myszków porphyry molybdenum-tungsten deposit is one of several porphyry copper-type deposits that have been identified within a poorly defined belt of Precambrian to Palaeozoic rocks in south-central Poland. It is in a complex of Proterozoic (Vendian) to early Palaeozoic (Early Cambria ...
The Southern Mountains Zone, Isle of Rum, Scotland
... deep within the now exhumed Rum volcano, were interpreted to result from in situ subterranean fracturing and abrasion of country rock by explosive throughpassage of gas from a crystallizing rhyodacitic magma (Bailey, 1945; Hughes, 1960; Dunham, 1968) (Fig. 2). Zones of undisrupted country rock, some ...
... deep within the now exhumed Rum volcano, were interpreted to result from in situ subterranean fracturing and abrasion of country rock by explosive throughpassage of gas from a crystallizing rhyodacitic magma (Bailey, 1945; Hughes, 1960; Dunham, 1968) (Fig. 2). Zones of undisrupted country rock, some ...
Geology and Geomorphology of the European Alps
... thrusting and the evolution of an E–SE-dipping subduction zone (Pfiffner 1992). The second alpidic orogenesis occurred during the Upper Eocene and Oligocene, when the African and European Plates collided with N–S-directed plate motions. The Penninic Ocean disappeared at that time and the Alps as a w ...
... thrusting and the evolution of an E–SE-dipping subduction zone (Pfiffner 1992). The second alpidic orogenesis occurred during the Upper Eocene and Oligocene, when the African and European Plates collided with N–S-directed plate motions. The Penninic Ocean disappeared at that time and the Alps as a w ...
Kinematics of the South Atlantic rift
... of the pre-breakup evolution of the conjugate West AfricanBrazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic pre-salt sag basin and the São Paulo High. W ...
... of the pre-breakup evolution of the conjugate West AfricanBrazilian margins. Our model suggests a causal link between changes in extension direction and velocity during continental extension and the generation of marginal structures such as the enigmatic pre-salt sag basin and the São Paulo High. W ...
Rhenium^Osmium Isotope and Platinum-Group Element
... Combined volumes estimated for the structural components of the Mackenzie LIP indicate that it is one of the most extensive LIPs recognized. The geology and structure of the Muskox intrusion has been described in detail previously (Findlay & Smith,1965; Irvine & Smith, 1967; Francis, 1994) and its s ...
... Combined volumes estimated for the structural components of the Mackenzie LIP indicate that it is one of the most extensive LIPs recognized. The geology and structure of the Muskox intrusion has been described in detail previously (Findlay & Smith,1965; Irvine & Smith, 1967; Francis, 1994) and its s ...
Plate-kinematics and crustal dynamics of circum
... The American margins of the Caribbean comprise basins and accreted terranes recording a polyphase tectonic history. Plate kinematic models and reconstructions back to the Jurassic show that Mesozoic separation of the Americas produced passive margins that were overridden diachronously from west to e ...
... The American margins of the Caribbean comprise basins and accreted terranes recording a polyphase tectonic history. Plate kinematic models and reconstructions back to the Jurassic show that Mesozoic separation of the Americas produced passive margins that were overridden diachronously from west to e ...
Mesa Central of México: Stratigraphy, structure, and Cenozoic
... Mesa Central is located in central-northern México, a semiarid region. Most geological studies in this region have focused on the exploration and exploitation of ore deposits, mainly precious metals. The works published in the nineteenth century, and in the beginnings of the twentieth, describe the ...
... Mesa Central is located in central-northern México, a semiarid region. Most geological studies in this region have focused on the exploration and exploitation of ore deposits, mainly precious metals. The works published in the nineteenth century, and in the beginnings of the twentieth, describe the ...
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.