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... RECEIVED JUNE 30, 2001; REVISED TYPESCRIPT ACCEPTED APRIL 11, 2002 The Ueno Basalts of central Japan comprise a monogenetic volcanic cone complex that was active between 2·76 and 1·34 Ma. Basalts were erupted at more than 14 centers scattered over a region 40 km in diameter. Alkali basalt was erupte ...
... RECEIVED JUNE 30, 2001; REVISED TYPESCRIPT ACCEPTED APRIL 11, 2002 The Ueno Basalts of central Japan comprise a monogenetic volcanic cone complex that was active between 2·76 and 1·34 Ma. Basalts were erupted at more than 14 centers scattered over a region 40 km in diameter. Alkali basalt was erupte ...
Geochemical evidence for interaction between oceanic crust and
... Cenozoic basalts are widely distributed along the coastal provinces and adjacent offshore shelf from the northernmost in Heilongjiang province to the southernmost in Hainan island, and constitute the eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary ...
... Cenozoic basalts are widely distributed along the coastal provinces and adjacent offshore shelf from the northernmost in Heilongjiang province to the southernmost in Hainan island, and constitute the eastern China volcanic belt. A close spatial relationship between Paleogene basalts and sedimentary ...
Igneous Environments
... then solidification of the magma into igneous rock. With such a history, igneous systems are best described from the bottom up. Begin with number one at the bottom of this figure. 6. Magma that reaches the surface erupts as lava (molten rock that flows on the surface) or as volcanic ash. Volcanic ash f ...
... then solidification of the magma into igneous rock. With such a history, igneous systems are best described from the bottom up. Begin with number one at the bottom of this figure. 6. Magma that reaches the surface erupts as lava (molten rock that flows on the surface) or as volcanic ash. Volcanic ash f ...
Insights into extensional processes during magma assisted rifting
... volcanic event (see Bosworth et al., 2005 for more detailed discussion). In southern Ethiopia, the initiation of rifting is thought to be ~18–20 Ma (WoldeGabriel et al., 1990; 1991; Ebinger et al., 1993; Yemane et al., 1999; Bonini et al., 2005). The most recently rifted (5–12 Ma) portion of the Mai ...
... volcanic event (see Bosworth et al., 2005 for more detailed discussion). In southern Ethiopia, the initiation of rifting is thought to be ~18–20 Ma (WoldeGabriel et al., 1990; 1991; Ebinger et al., 1993; Yemane et al., 1999; Bonini et al., 2005). The most recently rifted (5–12 Ma) portion of the Mai ...
structural geology of the western branch of the east african rift
... The East African Rift System (EARS) is a classic example of continental rifting and provides an excellent framework to study extensional magmatism and the evolution of several central volcanic systems which have formed along the rift from the Tertiary to Recent. Many of the volcanic structures have ...
... The East African Rift System (EARS) is a classic example of continental rifting and provides an excellent framework to study extensional magmatism and the evolution of several central volcanic systems which have formed along the rift from the Tertiary to Recent. Many of the volcanic structures have ...
emplacement of viscous mushes in the jinchuan ultramafic
... the University of Indiana (olivine) and at the Université de Paris VI (CAMPARIS) (olivine and other minerals). At Indiana University, we used an accelerating voltage of 15 kV, a beam current of 20 nA and 20 seconds counting intervals for the major elements in the olivine. Nickel in olivine was deter ...
... the University of Indiana (olivine) and at the Université de Paris VI (CAMPARIS) (olivine and other minerals). At Indiana University, we used an accelerating voltage of 15 kV, a beam current of 20 nA and 20 seconds counting intervals for the major elements in the olivine. Nickel in olivine was deter ...
Granitoids in Poland, AM Monograph No
... streaks or veins within the tonalites. Biotite and plagioclase composing the granodiorite are arranged parallelly to the borders of the veins. Detailed study of the granodiorite magma evolution was presented by Pietranik et al. (2006). The granodiorite is very rich in small, dark enclaves of mica sc ...
... streaks or veins within the tonalites. Biotite and plagioclase composing the granodiorite are arranged parallelly to the borders of the veins. Detailed study of the granodiorite magma evolution was presented by Pietranik et al. (2006). The granodiorite is very rich in small, dark enclaves of mica sc ...
Perspectives on the origin of plagiogranite in ophiolites from oxygen
... 8 different ophiolites and one dacite sampled along the East Pacific Rise using Secondary Ion Mass Spectrometry (SIMS). The δ18O values of 202 magmatic zircons from ophiolites range from 3.9 to 5.6‰ (n = 244 spots; average 4.9 ± 0.6‰; 2SD), extending ~1‰ below typical zircon in equilibrium with mantl ...
... 8 different ophiolites and one dacite sampled along the East Pacific Rise using Secondary Ion Mass Spectrometry (SIMS). The δ18O values of 202 magmatic zircons from ophiolites range from 3.9 to 5.6‰ (n = 244 spots; average 4.9 ± 0.6‰; 2SD), extending ~1‰ below typical zircon in equilibrium with mantl ...
39. crustal structure along the leg 152 drilling transect
... shelf) that become replaced seaward by breakup-related lavas and younger sediments (Figs. 1, 2). The rift lavas (the SDRS) therefore onlap the Precambrian (Archean to early Proterozoic) basement (Figs. 2–4). The onlap zone forms a crustal monoclinal, seaward flexure. This is different from the two n ...
... shelf) that become replaced seaward by breakup-related lavas and younger sediments (Figs. 1, 2). The rift lavas (the SDRS) therefore onlap the Precambrian (Archean to early Proterozoic) basement (Figs. 2–4). The onlap zone forms a crustal monoclinal, seaward flexure. This is different from the two n ...
Izu detachment hypothesis: A proposal of a unified cause for... event and the Tokai slow event
... Since the middle of 2000, two spectacular tectonic events have occurred in and south of central Honshu, Japan. The first one is the seismo-magmatic activity associated with the eruption of Miyakejima in the Izu islands starting on June 26, 2000. The Izu islands, consisting of Miyakejima, Niijima, Ko ...
... Since the middle of 2000, two spectacular tectonic events have occurred in and south of central Honshu, Japan. The first one is the seismo-magmatic activity associated with the eruption of Miyakejima in the Izu islands starting on June 26, 2000. The Izu islands, consisting of Miyakejima, Niijima, Ko ...
Zuni–Bandera volcanism, Rio Grande, USA — Melt formation in
... (REE) solid: melt partitioning. 2. Geological setting Located in west central New Mexico (Fig. 1), the ZBVF comprises a sequence of mixed tholeiite and alkali basalt lava flows, spatter ramparts, scoria cones, small shields, maars, and collapse pits erupted through Proterozoic continental crust over ...
... (REE) solid: melt partitioning. 2. Geological setting Located in west central New Mexico (Fig. 1), the ZBVF comprises a sequence of mixed tholeiite and alkali basalt lava flows, spatter ramparts, scoria cones, small shields, maars, and collapse pits erupted through Proterozoic continental crust over ...
IJNlliEl\$.lTY OF ICl:`LAND - Nordic Volcanological Center
... fissure swarm (Bjornsson et al. 1977). This activity has been characterized by alternating inflations and deflations of the volcano, and episodic widenings of the fissure swarm (Fig. 1). The inflation of the volcano progresses at a rate of 0.5 to 1.0 cm per day for one to seven months between deflat ...
... fissure swarm (Bjornsson et al. 1977). This activity has been characterized by alternating inflations and deflations of the volcano, and episodic widenings of the fissure swarm (Fig. 1). The inflation of the volcano progresses at a rate of 0.5 to 1.0 cm per day for one to seven months between deflat ...
Formation and stability of magmatic segments in the Main Ethiopian
... developing rifts until around 11 Ma (Kieffer et al., 2004). The volcanic units overlying uplifted Mesozoic marine sequences now form a ∼ 2500 m-high plateau on both sides of the southern Red Sea and western Gulf of Aden (Fig. 1). The long-lived volcanism and high relief indicates that the upper mant ...
... developing rifts until around 11 Ma (Kieffer et al., 2004). The volcanic units overlying uplifted Mesozoic marine sequences now form a ∼ 2500 m-high plateau on both sides of the southern Red Sea and western Gulf of Aden (Fig. 1). The long-lived volcanism and high relief indicates that the upper mant ...
nature ano evolution of the subcontinental mantle lithosphere below
... Ultramafic xenoliths found in the Pleistocene Pali-Aike alkali basalts, the southernmost outcropping of the Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicat ...
... Ultramafic xenoliths found in the Pleistocene Pali-Aike alkali basalts, the southernmost outcropping of the Patagonian Plateau lavas of southern South America, inelude both garnet-bearing and garnet-free Iherzolites, harzburgites, and orthopyroxenites. Mineral geothermometry and geobarometry indicat ...
Kistufell: Primitive Melt from the Iceland Mantle
... O-depletion and low 207Pb/204Pb, which distinguish depleted Icelandic lavas from North Atlantic N-MORB (Hemond et al. 1993; Chauvel & Hemond, 2000). Identifying the source of these geochemical anomalies is not trivial, however. Although excess Sr and 18O-depletion in other ocean-island basalts (OIB) ...
... O-depletion and low 207Pb/204Pb, which distinguish depleted Icelandic lavas from North Atlantic N-MORB (Hemond et al. 1993; Chauvel & Hemond, 2000). Identifying the source of these geochemical anomalies is not trivial, however. Although excess Sr and 18O-depletion in other ocean-island basalts (OIB) ...
4.4 billion years of crustal maturation: oxygen isotope ratios of
... other Phanerozoic examples (O’Neil and Chappell 1977; O’Neil et al. 1977). As early as 3.1 Ga, granite plutons are estimated to represent 20% of Archean exposure (Condie 1993) including many that are peraluminous (Sylvester 1994) and might contain a sedimentary component. However, we avoid widespre ...
... other Phanerozoic examples (O’Neil and Chappell 1977; O’Neil et al. 1977). As early as 3.1 Ga, granite plutons are estimated to represent 20% of Archean exposure (Condie 1993) including many that are peraluminous (Sylvester 1994) and might contain a sedimentary component. However, we avoid widespre ...
Triggering of the largest Deccan eruptions by the Chicxulub impact
... eruptions of the Deccan continental flood basalt province suggest that these three events may have occurred within less than about a hundred thousand years of each other. Partial melting induced by the Chicxulub event does not provide an energetically plausible explanation for this coincidence, and ...
... eruptions of the Deccan continental flood basalt province suggest that these three events may have occurred within less than about a hundred thousand years of each other. Partial melting induced by the Chicxulub event does not provide an energetically plausible explanation for this coincidence, and ...
LITHOGEOCHEMISTRY OF ULTRAMAFIC, GABBROIC AND
... UNIT Agb – GABBRO Mafic rocks range from gabbro to leucogabbro and locally to olivine gabbro and occur as rare, small plutons and thin sills within the gneisses as well as cm- and m-scale layers within large ultramafic sills. The largest gabbro body is in the north-central study area, exposed along ...
... UNIT Agb – GABBRO Mafic rocks range from gabbro to leucogabbro and locally to olivine gabbro and occur as rare, small plutons and thin sills within the gneisses as well as cm- and m-scale layers within large ultramafic sills. The largest gabbro body is in the north-central study area, exposed along ...
Rankin et al AJS 2007
... volcanic-free Albee. However, punky-weathering, fine- to medium-grained rocks, containing as much as 30 percent carbonate, abundant chlorite, and 10 percent muscovite, are commonly interlayered with sedimentary rocks of the Albee Formation. Abundant relict plagioclase, some twinned, is discernable i ...
... volcanic-free Albee. However, punky-weathering, fine- to medium-grained rocks, containing as much as 30 percent carbonate, abundant chlorite, and 10 percent muscovite, are commonly interlayered with sedimentary rocks of the Albee Formation. Abundant relict plagioclase, some twinned, is discernable i ...
41. Comparison of the Chemical and Magnetic Stratigraphy of DSDP
... 39 "W; 583 m) and 395 (22 ° 45 'N, 46 ° 05 'W; 572 m) provides an opportunity to compare the origin of a major portion of Layer 2 at two places on the Mid-Atlantic Ridge. The sites are similar in that basement at each consists dominantly of relatively few chemically distinct basaltic units (18 in Ho ...
... 39 "W; 583 m) and 395 (22 ° 45 'N, 46 ° 05 'W; 572 m) provides an opportunity to compare the origin of a major portion of Layer 2 at two places on the Mid-Atlantic Ridge. The sites are similar in that basement at each consists dominantly of relatively few chemically distinct basaltic units (18 in Ho ...
A case for mantle plumes
... for sceptics, that the existence of plumes in the Earth’s mantle can be inferred fairly directly from well-known observations and a minimum of assumptions, without the benefit of any theory. There are also robust arguments, relying on few assumptions, that thermal plumes are to be expected in the si ...
... for sceptics, that the existence of plumes in the Earth’s mantle can be inferred fairly directly from well-known observations and a minimum of assumptions, without the benefit of any theory. There are also robust arguments, relying on few assumptions, that thermal plumes are to be expected in the si ...
Ar– Ar ages of intrusions in East Greenland: Rift-to
... Igneous Province. The alkaline intrusions mainly crop out in tectonic and magmatic lineaments orthogonal to the rifted margin and occur up to 100 km inland. The area south of the Kangerlussuaq Fjord includes at least four tectonic lineaments and the intrusions are confined to three time windows at 5 ...
... Igneous Province. The alkaline intrusions mainly crop out in tectonic and magmatic lineaments orthogonal to the rifted margin and occur up to 100 km inland. The area south of the Kangerlussuaq Fjord includes at least four tectonic lineaments and the intrusions are confined to three time windows at 5 ...
Mechanics of active magmatic intraplating in the Rio Grande Rift
... of the largest active intrusions in the Earth’s continental crust, using interferometric synthetic aperture radar (InSAR) observations and finite element simulations. InSAR data spanning 15 years (1992–2007) indicate that the magma body is associated with a steady crustal uplift at a rate of about 2 ...
... of the largest active intrusions in the Earth’s continental crust, using interferometric synthetic aperture radar (InSAR) observations and finite element simulations. InSAR data spanning 15 years (1992–2007) indicate that the magma body is associated with a steady crustal uplift at a rate of about 2 ...
Mackenzie Large Igneous Province
The Mackenzie Large Igneous Province (MLIP) is a major Mesoproterozoic large igneous province of the southwestern, western and northwestern Canadian Shield in Canada. It consists of a group of related igneous rocks that were formed during a massive igneous event starting about 1,270 million years ago. The large igneous province extends from the Arctic in Nunavut to near the Great Lakes in Northwestern Ontario where it meets with the smaller Matachewan dike swarm. Included in the Mackenzie Large Igneous Province are the large Muskox layered intrusion, the Coppermine River flood basalt sequence and the massive northwesterly trending Mackenzie dike swarm.As a large igneous province, it is an extremely large area of related igneous rocks that were emplaced over an extremely short geological time span. The igneous rocks comprising the Mackenzie Large Igneous Province originated from processes not associated with normal plate tectonics and seafloor spreading. It is one of the several large igneous provinces scattered throughout the Canadian landscape, which can be thousands of kilometres in volume and area. The Mackenzie Large Igneous Province is also one of the largest Proterozoic magmatic provinces on Earth, as well as the world's largest and best-preserved continental flood basalt terrain. Igneous rocks of the Mackenzie Large Igneous Province are generally mafic in composition, including basalt and gabbro.Even though the Mackenzie Large Igneous Province is classified as a large igneous province like other extremely large accumulations of igneous rocks on Earth, it is much larger than large igneous province standards. The standard size classification for large igneous provinces is a minimum areal extent of 100,000 km2 (39,000 sq mi). However, the Mackenzie dike swarm itself occupies an area of at least 2,700,000 km2 (1,000,000 sq mi), making the Mackenzie Large Igneous Province larger than the Ontong Java Plateau in the southwestern Pacific Ocean and the U.S. state of Alaska.