Rocks Section 1: Classifying Rocks »Grain Size
... Formation of Metamorphic Rocks 2 major ways in which Metamorphic rocks form: » 1) Convergent Plate Boundaries– When two tectonic plates collide, extreme pressures and temperatures are applied to rocks. ...
... Formation of Metamorphic Rocks 2 major ways in which Metamorphic rocks form: » 1) Convergent Plate Boundaries– When two tectonic plates collide, extreme pressures and temperatures are applied to rocks. ...
From mud to granite: The Cooma metamorphic sequence
... There are rock outcrops along the Snowy Mountains highway that provide easy access. The complex is elongate North-South, parallel to the regional structure and the elongation of plutons of the Murrumbidgee Batholith immediately to the north, to which the metamorphic complex is probably related (Rich ...
... There are rock outcrops along the Snowy Mountains highway that provide easy access. The complex is elongate North-South, parallel to the regional structure and the elongation of plutons of the Murrumbidgee Batholith immediately to the north, to which the metamorphic complex is probably related (Rich ...
Atlantic volcanic margins: a comparative study
... and structural features developed during continental extension and break-up. We suggest that four main crustal zones can be recognized on volcanic margins. This tectono-magmatic zonation implies a history of development where tectonic and magmatic styles and dimensions depend on the interaction of l ...
... and structural features developed during continental extension and break-up. We suggest that four main crustal zones can be recognized on volcanic margins. This tectono-magmatic zonation implies a history of development where tectonic and magmatic styles and dimensions depend on the interaction of l ...
CHAPTER 3 - NATURAL HERITAGE VALUES 3.1 The Geoheritage
... Huronian strata that border Lake Temiskaming belong to the world‐renowned Gowganda Formation, universally regarded as a classic example of one of at least four episodes of continental glaciation that took place before the last Ice Age (Fig. 3.7). The ice sheet responsible for the deposition of the ...
... Huronian strata that border Lake Temiskaming belong to the world‐renowned Gowganda Formation, universally regarded as a classic example of one of at least four episodes of continental glaciation that took place before the last Ice Age (Fig. 3.7). The ice sheet responsible for the deposition of the ...
Black and white version - Dartmoor National Park
... leaving very bumpy areas most of which are now overgrown. Whole hillsides were scarred with gullies where the tinners broke the tin ore out of the granite. They used picks and shovels and running water to sort through the rock. Every where people were busy and not just looking for tin; peat was cut ...
... leaving very bumpy areas most of which are now overgrown. Whole hillsides were scarred with gullies where the tinners broke the tin ore out of the granite. They used picks and shovels and running water to sort through the rock. Every where people were busy and not just looking for tin; peat was cut ...
Chapter 21: Metamorphism
... Some gneisses have large eye-shaped grains (commonly feldspar) that are derived from preexisting large crystals by shear (as described in Section 23.1). Individual grains of this sort are called auge (German for eye), and the (German) plural is augen. An augen gneiss is a gneiss with ...
... Some gneisses have large eye-shaped grains (commonly feldspar) that are derived from preexisting large crystals by shear (as described in Section 23.1). Individual grains of this sort are called auge (German for eye), and the (German) plural is augen. An augen gneiss is a gneiss with ...
Plate rotation during continental collision and its relationship with
... motion reversal in the subduction channel and the initiation of eduction is thought to have happened at about 405 Ma [Brueckner and Cuthbert, 2013] after which the WGC cooled to Ar40-Ar39 closure temperatures of white mica by 397–380 Ma [Walsh et al., 2013]. The youngest Ar-Ar ages are broadly coinc ...
... motion reversal in the subduction channel and the initiation of eduction is thought to have happened at about 405 Ma [Brueckner and Cuthbert, 2013] after which the WGC cooled to Ar40-Ar39 closure temperatures of white mica by 397–380 Ma [Walsh et al., 2013]. The youngest Ar-Ar ages are broadly coinc ...
(2016). A joint local and teleseismic tomography study of
... region surrounding the NMSZ. Interpretations of potential field data and active source reconnaissance seismic refraction and reflection experiments suggest significant crustal heterogeneity beneath the embayment related to a long and complex geological history of rifting, uplift, and subsidence [Mooney ...
... region surrounding the NMSZ. Interpretations of potential field data and active source reconnaissance seismic refraction and reflection experiments suggest significant crustal heterogeneity beneath the embayment related to a long and complex geological history of rifting, uplift, and subsidence [Mooney ...
Experimental_laboratory_files/2004_The source of Granites
... with low 87Sr86/Sr initial ratios are generated from a crustal source that has this particular composition. Comparison with Archaean crust array (Fig. 1a) suggests that tonalites of the lower crust (e.g. Weaver & Tarney 1981) are good candidates to produce Sr isotopic ratios intermediate between man ...
... with low 87Sr86/Sr initial ratios are generated from a crustal source that has this particular composition. Comparison with Archaean crust array (Fig. 1a) suggests that tonalites of the lower crust (e.g. Weaver & Tarney 1981) are good candidates to produce Sr isotopic ratios intermediate between man ...
Geology - Geostud
... conversion (blue) directly underneath, indicating a high-velocity layer. This conversion pair is generally linear with some irregularity, which could reflect real features, such as structural or compositional heterogeneity. To the west, near 28°W (40 km), this structure intersects with the Moho conv ...
... conversion (blue) directly underneath, indicating a high-velocity layer. This conversion pair is generally linear with some irregularity, which could reflect real features, such as structural or compositional heterogeneity. To the west, near 28°W (40 km), this structure intersects with the Moho conv ...
Slide 1
... modern arcs, an upper mid-crust with Vp 6.0-6.5 km/s is present, corresponding to velocities calculated for exhumed arc upper mid-crust lithologies. If we presume that modern arcs and exhumed arcs all contain upper mid-crust with intermediate to felsic plutonic rocks (an unsubductable nucleus), we m ...
... modern arcs, an upper mid-crust with Vp 6.0-6.5 km/s is present, corresponding to velocities calculated for exhumed arc upper mid-crust lithologies. If we presume that modern arcs and exhumed arcs all contain upper mid-crust with intermediate to felsic plutonic rocks (an unsubductable nucleus), we m ...
The north Pyrenean Front and related foreland basin along the Bay
... sediments filling the Bay of Biscay abyssal plain, and deforms a North Pyrenean foreland basin located in front of the Cantabrian continental slope. Also shifted to the north with respect to the Basque-Parentis domain, this foreland basin lies on the top of the crust of the Bay of Biscay abyssal pla ...
... sediments filling the Bay of Biscay abyssal plain, and deforms a North Pyrenean foreland basin located in front of the Cantabrian continental slope. Also shifted to the north with respect to the Basque-Parentis domain, this foreland basin lies on the top of the crust of the Bay of Biscay abyssal pla ...
Extrusive Igneous Rocks, part 1
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
Extrusive Igneous Rocks, part 1
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
fossil record
... • In the process of forming an unconformity, – deposition began 12 million years ago (MYA), – continuing until 4 MYA – For 1 million years erosion occurred – removing 2 MY of rocks – and giving rise to – a 3 million year hiatus ...
... • In the process of forming an unconformity, – deposition began 12 million years ago (MYA), – continuing until 4 MYA – For 1 million years erosion occurred – removing 2 MY of rocks – and giving rise to – a 3 million year hiatus ...
Lab 4 - Basalt, Diabase, Andesite, Dacite
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
... • "The word has come to mean a pre-Tertiary basalt in Germany, a decomposed basalt in England, and a dike-rock with ophitic texture in the United States and Canada" ...
The Salinian terrane and Franciscan Complex of the Bodega Bay area
... dismembered sequences of graywacke, shale, and lesser amounts of mafic volcanic rocks, thinbedded chert, and rare limestone. These rocks also occur with serpentinite and tectonic pods of blueschist in mélange zones that are the locus of much shearing within the Franciscan and that generally separate ...
... dismembered sequences of graywacke, shale, and lesser amounts of mafic volcanic rocks, thinbedded chert, and rare limestone. These rocks also occur with serpentinite and tectonic pods of blueschist in mélange zones that are the locus of much shearing within the Franciscan and that generally separate ...
What is the meaning of ophiolites? - Creation Ministries International
... ocean crust and upper mantle material from some time in the recent past; some have been used with great success to estimate many properties of current ocean crust.23 I suggest that ophiolites represent pre-Flood ocean crust. If this is the case, is it possible that the current ocean crust is really ...
... ocean crust and upper mantle material from some time in the recent past; some have been used with great success to estimate many properties of current ocean crust.23 I suggest that ophiolites represent pre-Flood ocean crust. If this is the case, is it possible that the current ocean crust is really ...
Karson, J.A., and Lawrence, R.M., 1997.
... Extensive exposures of gabbroic rocks, inferred to represent mid-crustal intervals of the oceanic crust, crop out on the western median valley wall of the spreading segment of the Mid-Atlantic Ridge immediately south of the Kane Transform. Surface exposures of the gabbroic rocks have been mapped by ...
... Extensive exposures of gabbroic rocks, inferred to represent mid-crustal intervals of the oceanic crust, crop out on the western median valley wall of the spreading segment of the Mid-Atlantic Ridge immediately south of the Kane Transform. Surface exposures of the gabbroic rocks have been mapped by ...
CHAPTER 4 DISCUSSION
... magnetized, after intrusion of granodiorite (225Ma) and at approximately same age as adakitic syenite porphyry intrusion (208Ma). Re/Os age analyzed by molybdenite is older than K/Ar age by granodiorite and syenite porphyry. This probably indicates that crystallization of molybdenite started after t ...
... magnetized, after intrusion of granodiorite (225Ma) and at approximately same age as adakitic syenite porphyry intrusion (208Ma). Re/Os age analyzed by molybdenite is older than K/Ar age by granodiorite and syenite porphyry. This probably indicates that crystallization of molybdenite started after t ...
Modern Plate Tectonics
... because they are locations where plates converge on, or push against, each other. ...
... because they are locations where plates converge on, or push against, each other. ...
Modern Plate Tectonics
... Island Arcs parallel many oceanic trenches: arcshaped chains of volcanic islands (e.g., Japan) due to the rising magma from melting subducted crust. ...
... Island Arcs parallel many oceanic trenches: arcshaped chains of volcanic islands (e.g., Japan) due to the rising magma from melting subducted crust. ...
Earth`s first two billion years—The era of internally
... volcanic rocks commonly are assumed to be mostly ensimatic, but no ophiolites or other physical evidence for eruption on oceanic mantle have been found: only felsic gneisses have ever been seen as basement beneath supracrustal rocks in either outcrop or geophysics. If oceanic lithosphere existed dur ...
... volcanic rocks commonly are assumed to be mostly ensimatic, but no ophiolites or other physical evidence for eruption on oceanic mantle have been found: only felsic gneisses have ever been seen as basement beneath supracrustal rocks in either outcrop or geophysics. If oceanic lithosphere existed dur ...
The Rock Cycle
... rock is very lightweight because of its low density. It is usually light gray. Which rock is dark gray or black? This rock makes up the ocean floor. ...
... rock is very lightweight because of its low density. It is usually light gray. Which rock is dark gray or black? This rock makes up the ocean floor. ...
An Alternative EARTH - Geological Society of America
... overlie only ancient felsic basement. Pre–3.5 Ga rocks in cratons are polycyclic felsic migmatites and gneisses dominated by hydrous (biotite > hornblende) tonalite, trondhjemite, and granodiorite (TTG) and containing abundant small to huge enclaves of ultramafic, mafic, and anorthositic rocks (Fig. ...
... overlie only ancient felsic basement. Pre–3.5 Ga rocks in cratons are polycyclic felsic migmatites and gneisses dominated by hydrous (biotite > hornblende) tonalite, trondhjemite, and granodiorite (TTG) and containing abundant small to huge enclaves of ultramafic, mafic, and anorthositic rocks (Fig. ...
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.