From rifting to oceanic spreading in the Gulf of Aden: a synthesis
... direction of the Afar hotspot. In the areas with non-volcanic margins (in the east), the faults marking the end of rifting trend parallel to the inherited grabens. Only the transfer faults crosscut the inherited grabens, and some of these faults later developed into transform faults. The most import ...
... direction of the Afar hotspot. In the areas with non-volcanic margins (in the east), the faults marking the end of rifting trend parallel to the inherited grabens. Only the transfer faults crosscut the inherited grabens, and some of these faults later developed into transform faults. The most import ...
COMPOSITION, STRUCTURE AND EVOLUTION OF THE
... Pindos Ocean and large scale thrusting, creating compressional structures, especially a thickened crust, generated by the evolution of a nappe pile (Jolivet et al. 2009, Cao et al. 2013) This first event ended approximately 50 - 40 Ma ago (Schenk et al. 2005). The relicts of the related Meso - Helle ...
... Pindos Ocean and large scale thrusting, creating compressional structures, especially a thickened crust, generated by the evolution of a nappe pile (Jolivet et al. 2009, Cao et al. 2013) This first event ended approximately 50 - 40 Ma ago (Schenk et al. 2005). The relicts of the related Meso - Helle ...
Exhumation processes - Perso-sdt
... Downloaded from http://sp.lyellcollection.org/ by guest on February 15, 2013 ...
... Downloaded from http://sp.lyellcollection.org/ by guest on February 15, 2013 ...
hofstra university 1c field guidebook a geological transect from new
... faults are accompanied by recrystallization and reorientation of newly formed metamorphic minerals. More on metamorphic textures below - for now let's discuss some geometric aspects of structural geology. If layers are folded into convex upward forms we call them anticlines. Convexdownward fold for ...
... faults are accompanied by recrystallization and reorientation of newly formed metamorphic minerals. More on metamorphic textures below - for now let's discuss some geometric aspects of structural geology. If layers are folded into convex upward forms we call them anticlines. Convexdownward fold for ...
Imaging subduction from the trench to 300 km depth beneath the
... mantle of the subducted slab is almost always >8.5 km s−1 , which requires the ca. 120 Myr slab to be unusually cold. The low Vp/Vs within the subducted plate closely parallels the lower plane of the dipping seismic zone. It most likely indicates fluid resulting from dehydration of serpentine in the ...
... mantle of the subducted slab is almost always >8.5 km s−1 , which requires the ca. 120 Myr slab to be unusually cold. The low Vp/Vs within the subducted plate closely parallels the lower plane of the dipping seismic zone. It most likely indicates fluid resulting from dehydration of serpentine in the ...
Georgian Bay Geological Synthesis, Grenville Province: Explanatory
... Van Schmus and Zeitz 1986). Cutting this province is a northwesterly trending belt of gravity and aeromagnetic anomalies interpreted to represent the buried portion of the 1100 Ma Midcontinent Rift (Sutcliffe 1991). The Grenville Front marks the northwest limit of penetrative Grenvillian metamorphis ...
... Van Schmus and Zeitz 1986). Cutting this province is a northwesterly trending belt of gravity and aeromagnetic anomalies interpreted to represent the buried portion of the 1100 Ma Midcontinent Rift (Sutcliffe 1991). The Grenville Front marks the northwest limit of penetrative Grenvillian metamorphis ...
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 ...
A geological model for the structure of ridge segments in slow
... The axes of mid-oceanridges are offset by discontinuities and Laughton, 1977], and adjacentspreadingaxes often overwhich divide the oceancrust into spreadingsegments(Figure lap, with crustal ridges or septa cutting acrossthe discontinu1) [Macdonald et al., 1991]. First-order discontinuities in ities ...
... The axes of mid-oceanridges are offset by discontinuities and Laughton, 1977], and adjacentspreadingaxes often overwhich divide the oceancrust into spreadingsegments(Figure lap, with crustal ridges or septa cutting acrossthe discontinu1) [Macdonald et al., 1991]. First-order discontinuities in ities ...
Metamorphic Intro
... • Metamorphism often continues after major deformation ceases – Metamorphic pattern is simpler than the structural one ...
... • Metamorphism often continues after major deformation ceases – Metamorphic pattern is simpler than the structural one ...
Protoridge_Three-Dimensional Seismic Imaging of a
... velocity model from the Main Ethiopian rift clearly images mid-crustal intrusions in this active, transitional rift setting, supporting breakup models based on dike intrusion and magma supply. The most striking features of our velocity model are anomalously fast, elongate bodies (velocity, Vp ;6.5–6 ...
... velocity model from the Main Ethiopian rift clearly images mid-crustal intrusions in this active, transitional rift setting, supporting breakup models based on dike intrusion and magma supply. The most striking features of our velocity model are anomalously fast, elongate bodies (velocity, Vp ;6.5–6 ...
Deep-Seated Mass Rock Creep Along The Karakoram
... laterally rotating in the manner of opening scissors. This can be inferred by the preservation and final position of the slide mass at the river side (Plate 3). Moreover, as the slide appears to be derived from the margin of a large glacially moulded rock, a roche-moutonn6e (left part of Plate 4) it ...
... laterally rotating in the manner of opening scissors. This can be inferred by the preservation and final position of the slide mass at the river side (Plate 3). Moreover, as the slide appears to be derived from the margin of a large glacially moulded rock, a roche-moutonn6e (left part of Plate 4) it ...
univERsity oF copEnhAGEn
... A chemically distinct composition of the Archean lithosphere, which is depleted in Ti and Ca and has high Mg/Fe ratio (e.g. Boyd, 1989), suggests that it formed under unique conditions, which did not exist in the post-Archean time. Campbell and Griffiths (1992) argue that basal plume accretion could ...
... A chemically distinct composition of the Archean lithosphere, which is depleted in Ti and Ca and has high Mg/Fe ratio (e.g. Boyd, 1989), suggests that it formed under unique conditions, which did not exist in the post-Archean time. Campbell and Griffiths (1992) argue that basal plume accretion could ...
Lasting mantle scars lead to perennial plate tectonics
... boundary) (for example, refs 4–6). ML scars are well established in the geological record (for example, refs 1,4,6) but they have not received the same attention as, for example, the reactivation of faults within the Earth’s crust7 for localizing intraplate deformation. Experiments on rock propertie ...
... boundary) (for example, refs 4–6). ML scars are well established in the geological record (for example, refs 1,4,6) but they have not received the same attention as, for example, the reactivation of faults within the Earth’s crust7 for localizing intraplate deformation. Experiments on rock propertie ...
Westward propagation of the North Anatolian fault into the northern
... North Anatolian fault and a 17 mm/yr velocity between Anatolia and Eurasia. This is somewhat less than the 22 ± 3 mm/yr observed around Marmara with GPS (Straub et al., 1997). Moreover, the 5 m.y. displacement field in Marmara is strikingly consistent with the Anatolia extrusion kinematics derived a ...
... North Anatolian fault and a 17 mm/yr velocity between Anatolia and Eurasia. This is somewhat less than the 22 ± 3 mm/yr observed around Marmara with GPS (Straub et al., 1997). Moreover, the 5 m.y. displacement field in Marmara is strikingly consistent with the Anatolia extrusion kinematics derived a ...
Important Notice
... The granulite and upper amphibolite grade rocks of the Kapuskasing structural zone (KSZ) in Ontario represent an exposure of Archean crust that has been uplifted along a southeast verging thrust fault system. ...
... The granulite and upper amphibolite grade rocks of the Kapuskasing structural zone (KSZ) in Ontario represent an exposure of Archean crust that has been uplifted along a southeast verging thrust fault system. ...
Chapter 1 Introduction 1.1. Purpose of the investigation
... University of Pretoria etd – Ghavami-Riabi, R (2007) University of Pretoria etd – Ghavami-Riabi, R (2007) ...
... University of Pretoria etd – Ghavami-Riabi, R (2007) University of Pretoria etd – Ghavami-Riabi, R (2007) ...
Meso- and Cenozoic Tectonics of the Central Asian Mountain Belt
... evolution of Central Asia; (2) Cenozoic mountain building and intramontane basin formation in the Altay-Sayan area; (3) comparison of the tectonic evolutionary paths of the Altay, Baikal, and Tien Shan regions; (4) Cenozoic tectonics and mantle-plume magmatic activity; and (5) the geodynamics and te ...
... evolution of Central Asia; (2) Cenozoic mountain building and intramontane basin formation in the Altay-Sayan area; (3) comparison of the tectonic evolutionary paths of the Altay, Baikal, and Tien Shan regions; (4) Cenozoic tectonics and mantle-plume magmatic activity; and (5) the geodynamics and te ...
Tertiary Igneous Rocks of Northeastern Cache Valley, Idaho
... to determine the types of igneous structures involved. ...
... to determine the types of igneous structures involved. ...
GEOLOGY OF MINNESOTA: A Centennial Volume
... Hornblende Peridotite in Ely Greenstone ....................................................... . Differentiated Mafic-Ultramafic Bodies in Newton Lake Formation ................................. . Similarities to Ultramafic Rocks in Northwestern Ontario ........................................... . ...
... Hornblende Peridotite in Ely Greenstone ....................................................... . Differentiated Mafic-Ultramafic Bodies in Newton Lake Formation ................................. . Similarities to Ultramafic Rocks in Northwestern Ontario ........................................... . ...
Structural development of the Mid-Tertiary Doi Suthep Metamorphic
... schist, suggest peak metamorphic grades in the amphibolite facies. The generally medium- to coarse-grained textures also suggest a high metamorphic grade. This interpretation is consistent with relations farther south, in the Doi Inthanon area. There, metasedimentary rocks form a thick mantle over a ...
... schist, suggest peak metamorphic grades in the amphibolite facies. The generally medium- to coarse-grained textures also suggest a high metamorphic grade. This interpretation is consistent with relations farther south, in the Doi Inthanon area. There, metasedimentary rocks form a thick mantle over a ...
Lithospheric structure of the Rio Grande rift
... ago22. Even so, this suggests RGR formational strain rates of only 10216 to 10215 s21 (0.56 to 1 mm yr21). This low strain rate, along with increased temperature, may have enabled ductile deformation of the lithosphere, producing the observed symmetric region of laterally distributed pure-shear defo ...
... ago22. Even so, this suggests RGR formational strain rates of only 10216 to 10215 s21 (0.56 to 1 mm yr21). This low strain rate, along with increased temperature, may have enabled ductile deformation of the lithosphere, producing the observed symmetric region of laterally distributed pure-shear defo ...
A Geochemical Classification for Feldspathic Igneous Rocks
... enrichment (Osbourn, 1959). Miyashiro (1974) established a boundary between volcanic rocks that underwent an iron-enrichment trend and those that did not, which he identified as ‘tholeiitic’ and ‘calc-alkalic’ respectively. (Note: to eliminate confusion, we place the terms ‘tholeiitic’ and ‘calc-alk ...
... enrichment (Osbourn, 1959). Miyashiro (1974) established a boundary between volcanic rocks that underwent an iron-enrichment trend and those that did not, which he identified as ‘tholeiitic’ and ‘calc-alkalic’ respectively. (Note: to eliminate confusion, we place the terms ‘tholeiitic’ and ‘calc-alk ...
Vertical stretching and crustal thickening at Nanga Parbat, Pakistan
... For these workers the tectonic construction of topography and the erosional exhumation of the massif relate to displacements on the Liachar Thrust and the kinematically-related Liachar Shear Zone (the deformation zone in the hanging wall to the Liachar Thrust). Subsequently, researchers have mapped ...
... For these workers the tectonic construction of topography and the erosional exhumation of the massif relate to displacements on the Liachar Thrust and the kinematically-related Liachar Shear Zone (the deformation zone in the hanging wall to the Liachar Thrust). Subsequently, researchers have mapped ...
BANDED GNEISSES OF EIGHT LOCALITIES G eneral S tatemen t.
... The writer did not visit any of the Pyrenees localities. Available time permitted only the examination of numerous specimens and photographs of the gneisses and associated rocks and discussions of their occurrences, characteristics, and problems relating to their geneses with Professor Raguin and Dr ...
... The writer did not visit any of the Pyrenees localities. Available time permitted only the examination of numerous specimens and photographs of the gneisses and associated rocks and discussions of their occurrences, characteristics, and problems relating to their geneses with Professor Raguin and Dr ...
Petrography and illite crystallinity of the Lesser Himalayan
... Illite crystallinity Crystallinity of illite in pelitic rocks usually signifies the degree of ordering of crystal lattice of these minerals (Kübler, 1967). The crystallinity of illite increases with increasing metamorphic grade. Systematic changes in the shape of peaks of these minerals on X-ray dif ...
... Illite crystallinity Crystallinity of illite in pelitic rocks usually signifies the degree of ordering of crystal lattice of these minerals (Kübler, 1967). The crystallinity of illite increases with increasing metamorphic grade. Systematic changes in the shape of peaks of these minerals on X-ray dif ...
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.