Volcanoes and Igneous Activity Earth - Chapter 4
... Traces or remains of prehistoric life Are the most important inclusions Help determine past environments Used as time indicators Used for matching rocks from different places ...
... Traces or remains of prehistoric life Are the most important inclusions Help determine past environments Used as time indicators Used for matching rocks from different places ...
Plate Tectonics
... floor. They commonly offset active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. A few, however, occur on land. The San Andreas is one of the few transform faults exposed on land. The San Andreas fault zone, which is about 1,300 km long and in p ...
... floor. They commonly offset active spreading ridges, producing zig-zag plate margins, and are generally defined by shallow earthquakes. A few, however, occur on land. The San Andreas is one of the few transform faults exposed on land. The San Andreas fault zone, which is about 1,300 km long and in p ...
Precambrian Research Geochemical and numerical constraints
... geochemical observations and numerical models. Based on a geochemical dataset of 295 granitoid samples from the Karelian and Kola cratons of the Fennoscandian Shield, we divide Neoarchean juvenile (extracted from oceanic crust or mantle) granitoids into three groups: (1) low-HREE (heavy rare earth e ...
... geochemical observations and numerical models. Based on a geochemical dataset of 295 granitoid samples from the Karelian and Kola cratons of the Fennoscandian Shield, we divide Neoarchean juvenile (extracted from oceanic crust or mantle) granitoids into three groups: (1) low-HREE (heavy rare earth e ...
Weathering and Erosion Study Guide
... 14. Which statement best explains how water mechanically breaks down rocks? A. Water expands when it freezes (Ice Wedging) B. Water does not break down rocks C. Acids in water react with chemicals in the rock D. All of the above 15. Which of the following things will most likely experience oxidation ...
... 14. Which statement best explains how water mechanically breaks down rocks? A. Water expands when it freezes (Ice Wedging) B. Water does not break down rocks C. Acids in water react with chemicals in the rock D. All of the above 15. Which of the following things will most likely experience oxidation ...
This article appeared in a journal published by Elsevier. The
... reflecting the presence of stilpnomelane—the only aluminum-bearing phase. This stratigraphic scheme (Wolff, 1917) was designed to aid in understanding how various kinds of hematite-rich ores are distributed in the iron-formation. Except for the Intermediate Slate—a tuffaceous unit at the Lower Cherty–L ...
... reflecting the presence of stilpnomelane—the only aluminum-bearing phase. This stratigraphic scheme (Wolff, 1917) was designed to aid in understanding how various kinds of hematite-rich ores are distributed in the iron-formation. Except for the Intermediate Slate—a tuffaceous unit at the Lower Cherty–L ...
Chukchi arctic continental margins: tectonic evolution, link to the
... and Cretaceous ages. They chiefly relate to granitemetamorphic domes that formed at the end of the Early Cretaceous (Gel’man, 1995; Bering Strait.., 1987). Most of orthogneisses are deformed granites of Cretaceous age (108-104 Ma, U-Pb SHRIMP zircon ages). Zircons of only two samples yielded ages of ...
... and Cretaceous ages. They chiefly relate to granitemetamorphic domes that formed at the end of the Early Cretaceous (Gel’man, 1995; Bering Strait.., 1987). Most of orthogneisses are deformed granites of Cretaceous age (108-104 Ma, U-Pb SHRIMP zircon ages). Zircons of only two samples yielded ages of ...
Continental Drift Reading
... decay in salt water, an ocean thousands of miles wide would be a major obstacle. The presence of the same flora on these far-flung continents is further evidence that the continents were all together in the past. In addition, it is difficult to explain why the fern would populate areas with climatic ...
... decay in salt water, an ocean thousands of miles wide would be a major obstacle. The presence of the same flora on these far-flung continents is further evidence that the continents were all together in the past. In addition, it is difficult to explain why the fern would populate areas with climatic ...
geology of the tavan har area, gobi, mongolia
... Eastern Gobi, Mongolia” The impact crater of the northeastern Tavan Har region is located in greenschist facies metamorphic rocks with both felsic and mafic protoliths. The crater has a diameter of 1.75 km and covers an area of 137 hectares. At least two episodes of deformation have affected the cou ...
... Eastern Gobi, Mongolia” The impact crater of the northeastern Tavan Har region is located in greenschist facies metamorphic rocks with both felsic and mafic protoliths. The crater has a diameter of 1.75 km and covers an area of 137 hectares. At least two episodes of deformation have affected the cou ...
Sa˜o Luıs Craton and Gurupi Belt
... NW–SE cross-cutting structures. Structures dipping at low to moderate angles to SSW, with down-dip or oblique lineations, are mostly confined to the northwestern portion of the belt. These structures record tectonic transport from SW to NE, ...
... NW–SE cross-cutting structures. Structures dipping at low to moderate angles to SSW, with down-dip or oblique lineations, are mostly confined to the northwestern portion of the belt. These structures record tectonic transport from SW to NE, ...
PETLAB3-14
... thick flows without their field context. If contacts are exposed, sills can be distinguished from flows by the presence of symmetric finer-grained quenched margins, as opposed to the thick upper quench and thin lower quench zones of flows. Cross cutting field relationships are indicative of dykes. H ...
... thick flows without their field context. If contacts are exposed, sills can be distinguished from flows by the presence of symmetric finer-grained quenched margins, as opposed to the thick upper quench and thin lower quench zones of flows. Cross cutting field relationships are indicative of dykes. H ...
Journal of Maps
... The Dent Blanche unit is believed to correspond to the Ivrea Palaeozoic basement (Southern Alps) dismembered and involved in the Alpine subduction and collision (Carraro et al., 1970). The Dent Blanche unit includes lenses of mylonitized pre-Alpine and Mesozoic metasedimentary cover (i.e., Roisan Zo ...
... The Dent Blanche unit is believed to correspond to the Ivrea Palaeozoic basement (Southern Alps) dismembered and involved in the Alpine subduction and collision (Carraro et al., 1970). The Dent Blanche unit includes lenses of mylonitized pre-Alpine and Mesozoic metasedimentary cover (i.e., Roisan Zo ...
2 Regional Geological Setting
... as dating early diagenesis, whereas the latter refers to the metamorphic event. Thus, ages obtained from the marble by Frimmel (2000b) indicate that it is younger than the felsic volcanic metavolcanic rocks from the Rosh Pinah Formation (see below). However, the absolute isochron ages of the marbles ...
... as dating early diagenesis, whereas the latter refers to the metamorphic event. Thus, ages obtained from the marble by Frimmel (2000b) indicate that it is younger than the felsic volcanic metavolcanic rocks from the Rosh Pinah Formation (see below). However, the absolute isochron ages of the marbles ...
Opening and closure of an island arc
... sediments has been determined as recycled components from orogens, prevalently from the cratonic area to the north-east. They were transported and deposited mostly by turbidity currents. Folding is manifold, from a simple singural deformation up to three or four stages of refolding (Willner, 1990). ...
... sediments has been determined as recycled components from orogens, prevalently from the cratonic area to the north-east. They were transported and deposited mostly by turbidity currents. Folding is manifold, from a simple singural deformation up to three or four stages of refolding (Willner, 1990). ...
Gabbro
... It is often stated that Earth's oceanic crust is made-up of basalt. The word "basalt" is used because the rocks of the oceanic crust have a "basaltic" composition. However; only a thin surface veneer of oceanic crust is basalt. The deeper rocks of the oceanic crust are generally coarser-grained gabb ...
... It is often stated that Earth's oceanic crust is made-up of basalt. The word "basalt" is used because the rocks of the oceanic crust have a "basaltic" composition. However; only a thin surface veneer of oceanic crust is basalt. The deeper rocks of the oceanic crust are generally coarser-grained gabb ...
the North American Cordillera: from Baja to British Columbia Growth
... material was stripped from the eastern zone relative to the western zone during this time, with denudation on the order of 1 mm a-1. Erosion, coupled with local thrust faulting (Schmidt 2000), was by far the most important denudation mechanism; only one Late Cretaceous extensional fault has been fou ...
... material was stripped from the eastern zone relative to the western zone during this time, with denudation on the order of 1 mm a-1. Erosion, coupled with local thrust faulting (Schmidt 2000), was by far the most important denudation mechanism; only one Late Cretaceous extensional fault has been fou ...
MGS_ES_2_revised2
... entered and retreated from the State during several separate phases and along four distinct routes. The early Wisconsinan-stage ice sheets traveled via the Red Lakes, Rainy Lake, and the Lake Superior-Minneapolis lowland routes. Later, ice advanced along the Red River of the North and the Minnesota ...
... entered and retreated from the State during several separate phases and along four distinct routes. The early Wisconsinan-stage ice sheets traveled via the Red Lakes, Rainy Lake, and the Lake Superior-Minneapolis lowland routes. Later, ice advanced along the Red River of the North and the Minnesota ...
Strain localization along the Main Boundary Thrust (MBT) zone in
... The southward tapering Himalayan tectonic wedge is sliding over the upper boundary of the subducting Indian crust that act as the basal low angle detachment fault, known as the Main Himalayan Thrust (MHT). It is now established that at least four crustal-scale south verging thrust faults, such as Ma ...
... The southward tapering Himalayan tectonic wedge is sliding over the upper boundary of the subducting Indian crust that act as the basal low angle detachment fault, known as the Main Himalayan Thrust (MHT). It is now established that at least four crustal-scale south verging thrust faults, such as Ma ...
Chemical sedimentary rocks
... Paired metamorphic facies are common in subduction zone tectonic environments. Ocean floor basalts exposed to variable pressures and temperatures form well-foliated greenschists and amphibolites, or weakly-foliated blueschists and eclogites. ...
... Paired metamorphic facies are common in subduction zone tectonic environments. Ocean floor basalts exposed to variable pressures and temperatures form well-foliated greenschists and amphibolites, or weakly-foliated blueschists and eclogites. ...
GY111 Earth Materials
... • All regional metamorphic rocks contain a foliation- in low grade (Low T) rocks the grains are microscopic so you can’t “see” the foliation • Cleavage in rocks is the tendency to split ...
... • All regional metamorphic rocks contain a foliation- in low grade (Low T) rocks the grains are microscopic so you can’t “see” the foliation • Cleavage in rocks is the tendency to split ...
chemical composition and origin of the shock metamorphic rocks of
... It seems probable that in addition to fossil meteorite impact craters there are also many other crater-like, circular or semicircular structures. Of these, the »polygonal structures» described by Amstutz (1964) and Zimmermann and Amstutz (1965) which are supposed to have been produced by periodic fa ...
... It seems probable that in addition to fossil meteorite impact craters there are also many other crater-like, circular or semicircular structures. Of these, the »polygonal structures» described by Amstutz (1964) and Zimmermann and Amstutz (1965) which are supposed to have been produced by periodic fa ...
Minerals and Rocks
... Continental crust comprises the major landmasses on Earth that are exposed to the atmosphere. It is less dense (2.7 g/cm3) and much thicker than oceanic crust. Where continental crust extends to very high elevations, such as in mountain ranges, it also descends to great depths below the surface. Con ...
... Continental crust comprises the major landmasses on Earth that are exposed to the atmosphere. It is less dense (2.7 g/cm3) and much thicker than oceanic crust. Where continental crust extends to very high elevations, such as in mountain ranges, it also descends to great depths below the surface. Con ...
Morocco, 23-27 March 2015
... The Zenaga inlier, located south of the South Atlas Fault, represents the northern margin of the Palaeoproterozoic continental terrane (West African Craton) in the Southwest separated by the “Major Fault of the Anti-Atlas” which was considered as the northern limit of the West African Cration. This ...
... The Zenaga inlier, located south of the South Atlas Fault, represents the northern margin of the Palaeoproterozoic continental terrane (West African Craton) in the Southwest separated by the “Major Fault of the Anti-Atlas” which was considered as the northern limit of the West African Cration. This ...
Southwest Scotland: A landscape fashioned by geology
... Some of the rocks derived from great depth consist of minerals that are not very stable at the Earth's surface and so have been altered to 'serpentinite', so-called because of the sinuous patterns of red, green and brown that run through the rock and which were thought to be reminiscent of snake ski ...
... Some of the rocks derived from great depth consist of minerals that are not very stable at the Earth's surface and so have been altered to 'serpentinite', so-called because of the sinuous patterns of red, green and brown that run through the rock and which were thought to be reminiscent of snake ski ...
Formation of Magma and Igneous Rocks Basalt
... explosions and are classified by fragment size and degree of consolidation. • Ultramafic, mafic, intermediate, and felsic (silicic) are compositional categories of magma/rocks. • Rapid cooling leads to aphanitic rocks and slow cooling produces coarser grained phaneritic rock. Porphyritic texture con ...
... explosions and are classified by fragment size and degree of consolidation. • Ultramafic, mafic, intermediate, and felsic (silicic) are compositional categories of magma/rocks. • Rapid cooling leads to aphanitic rocks and slow cooling produces coarser grained phaneritic rock. Porphyritic texture con ...
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.