scholarly journals Gabbro, plagiogranite and associated dykes in the supra-subduction zone Evros Ophiolites, NE Greece

2008 ◽  
Vol 146 (1) ◽  
pp. 72-91 ◽  
Author(s):  
NIKOLAY BONEV ◽  
GÉRARD STAMPFLI
Keyword(s):  
Subduction Zone ◽  
Tectonic Setting ◽  
Basaltic Magma ◽  
Mantle Peridotite ◽  
Mafic Rocks ◽  
The North ◽  
Petrology And Geochemistry ◽  
Tensile Fractures ◽  
High Level ◽  
Mafic Lavas

AbstractThe incomplete Evros ophiolites in NE Greece form a NE–SW-oriented discontinuous belt in the Alpine orogen of the north Aegean. Field data, petrology and geochemistry are presented here for the intrusive section and associated mafic dykes of these ophiolites. Bodies of high-level isotropic gabbro and plagiogranite in the ophiolite suite are cross-cut by NE–SW-trending boninitic and tholeiitic–boninitic affinity dykes, respectively. The dykes fill tensile fractures or faults, which implies dyke emplacement in an extensional tectonic regime. The tholeiitic–transitional boninitic gabbro is REE- and HFS-depleted relative to N-MORB, indicating derivation from melting of a refractory mantle peridotite source. Associated boninitic dykes are slightly LREE-enriched, showing mineral and whole-rock geochemistry similar to the gabbro. The plagiogranite is a strongly REE-enriched high-silica trondhjemite, with textures and composition typical for an oceanic crust differentiate. Plagiogranite-hosted tholeiitic and transitional boninitic dykes are variably REE-enriched. Geochemical modelling indicates origin of the plagiogranite by up to 75 % fractional crystallization of basaltic magma similar to that producing the associated tholeiitic dykes. All mafic rocks have high LILE/HFSE ratios and negative Ta–Nb–Ti and Ce anomalies, typical for subduction zone-related settings. The mafic rocks show a similar trace-element character to the mafic lavas of an extrusive section in Bulgaria, suggesting they both form genetically related intrusive and extrusive suites of the Evros ophiolites. The field occurrence, the structural context, the petrology and geochemical signature of the studied magmatic assemblage provide evidence for its origin in a proto-arc (fore-arc) tectonic setting, thus tracing the early stages of the tectono-magmatic evolution of Jurassic arc-marginal basin system that has generated the supra-subduction type Evros ophiolites.

Stratigraphy and eruptive history of the Late Devonian Mount Pleasant Caldera Complex, Canadian Appalachians

1997 ◽  
Vol 134 (1) ◽  
pp. 17-36 ◽  
Author(s):  
S. R. McCUTCHEON ◽  
H. E. ANDERSON ◽  
P. T. ROBINSON
Keyword(s):  
Fractional Crystallization ◽  
Basaltic Magma ◽  
Late Devonian ◽  
Crustal Material ◽  
Basaltic Rocks ◽  
Stratigraphic Subdivision ◽  
Mount Pleasant ◽  
History Of ◽  
High Level ◽  
Mafic Lavas

Stratigraphic, petrographic and geochemical evidence indicate that the volcano-sedimentary rocks of the Late Devonian Piskahegan Group, located in the northern Appalachians of southwestern New Brunswick, represent the eroded remnants of a large epicontinental caldera complex. This complex – the Mount Pleasant Caldera – is one of few recognizable pre-Cenozoic calderas and is divisible into Exocaldera, Intracaldera and Late Caldera-Fill sequences. The Intracaldera Sequence comprises four formations that crop out in a triangular-shaped area and includes: thick ash flow tuffs, thick sedimentary breccias that dip inward, and stocks of intermediate to felsic composition that intrude the volcanic pile or are localized along caldera-margin faults. The Exocaldera Sequence contains ash flow tuffs, mafic lavas, alluvial redbeds and porphyritic felsic lavas that comprise five formations. The Late Caldera-Fill Sequence contains rocks that are similar to those of the outflow facies and comprises two formations and two minor intrusive units. Geochemical and mineralogical data support the stratigraphic subdivision and indicate that the basaltic rocks are mantle-derived and have intraplate chemical affinities. The andesites were probably derived from basaltic magma by fractional crystallization and assimilation of crustal material. The various felsic units are related by episodes of fractional crystallization in a high-level, zoned magma chamber. Fractionation was repeatedly interrupted by eruption of material from the roof zone such that seven stages of caldera development have been identified. The genesis of the caldera is related to a period of lithospheric thinning that followed the Acadian Orogeny in the northern Appalachians.

Chromite chemistry as an indicator of petrogenesis and tectonic setting of the Ranomena ultramafic complex in north-eastern Madagascar

2016 ◽  
Vol 155 (1) ◽  
pp. 109-118 ◽  
Author(s):  
C. ISHWAR-KUMAR ◽  
V.J. RAJESH ◽  
B.F. WINDLEY ◽  
T. RAZAKAMANANA ◽  
T. ITAYA ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Tectonic Setting ◽  
Basaltic Magma ◽  
Parental Magma ◽  
Tholeiitic Basalt ◽  
Ultramafic Complex ◽  
Layered Gabbro ◽  
Arc Setting ◽  
Melt Composition ◽  
High Degree

AbstractThe Ranomena ultramafic complex in NE Madagascar consists of layered gabbro, harzburgite, orthopyroxenite, clinopyroxenite, garnet websterite and chromitite-layered peridotite. This study of the Ranomena chromite chemistry aims to better understand the petrogenesis and palaeotectonic environment of the complex. The chromite from the Ranomena chromitite is unzoned/weakly zoned and has a Cr# (Cr/(Cr + Al)) of 0.59–0.69, a Mg# (Mg/(Fe + Mg)) of 0.37–0.44, and low Al2O3(15–23 wt %) suggesting derivation from a supra-subduction zone arc setting. Calculation of parental melt composition suggests that the parental magma composition of the Ranomena chromitite was similar to that of a primitive tholeiitic basalt formed at a high degree of mantle melting, suggesting the parental melt composition was equivalent to that of an island-arc tholeiite (IAT). The parental magma of the Ranomena chromite had a FeO/MgO ratio of 0.9 to 1.8, suggesting arc derivation. The parental magma was Al- and Fe-rich, similar to a tholeiitic basaltic magma. The composition of orthopyroxene from the chromitite indicates a crystallization temperature range of 1250–1300°C at 1.0 GPa. The chemistry of the chromite in the Ranomena chromitite further suggests that the complex formed in a supra-subduction zone arc tectonic setting.

scholarly journals A CONCEPTUAL MODEL FOR THE ORIGINS OF GEOTHERMAL AND VOLCANIC ACTIVITY IN THE NORTH ISLAND OF NEW ZEALAND

2009 ◽  
Vol 50 (3) ◽  
pp. 421-425
Author(s):  
ALEX MCNABB
Keyword(s):  
New Zealand ◽  
Subduction Zone ◽  
Volcanic Activity ◽  
Subduction Zones ◽  
Basaltic Magma ◽  
Plate Edge ◽  
The North ◽  
Geothermal Fields ◽  
Geothermal Activity ◽  
Primary Hypothesis

AbstractThe current geothermal and volcanic activity in the North Island of New Zealand is explained as a consequence of Pacific and Australian plate interactions over the last 20 million years. The primary hypothesis is that the Kermadec subduction zone has for the last 20 million years or more been retreating in a south-easterly direction at about five centimetres per year. It is surmised that this motion and interaction with another subduction zone almost at right angles to it under the North Island resulted in plate tearing due to the incompatibility of the plate geometry where these subduction zones interacted. The nature and consequences of this plate tearing are partially revealed in published maps of the plate currently under the North Island. If the subducted parts of this plate, as shown in Eiby’s maps, [G. A. Eiby, “The New Zealand sub-crustal rift”, New Zeal. J. Geol. Geophy.7 (1964) 109–133] are straightened, then the plate edge lies on a curve giving a rough picture of their position before being torn and subducted by the Kermadec trench motion. This map of the tear suggests the shape of the edge of a missing plate segment torn from the plate, and implies a rotation of the upper North Island, clockwise approximately 20 degrees, about a point just south of the Thames estuary. A consequence of this plate tearing is that the solid retreating crustal wave generating magma pressure beneath the crest of the solid wave has the potential to inject significant basaltic magma into the crust through the tears. These intrusive magma fluxes have the ability to generate geothermal fields and rhyolitic lavas from crustal melts. This could explain the geothermal activity along the Coromandel peninsula five to seven million years ago, the ignimbrite outcrops about Lake Taupo and the current geothermal and volcanic activity stretching from Taupo to Rotorua.

Her Majesty Queen Rania Al Abdullah

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Education System ◽  
Ministry Of Education ◽  
Childhood Experiences ◽  
The Sustainable Development ◽  
American University ◽  
The North ◽  
The World ◽  
Development Goals ◽  
High Level ◽  
Education And Development

“The real treasure is in the minds of our children, and all we have to do is extract it.” Her Majesty Queen Rania Al Abdullah writes in website Queen Rania Foundation For Education And Development www.qrf.org/en. Rania Al Yassin was born on August 31, 1970. She obtained her Bachelor’s degree in Business Administration from the American University of Cairo in 1991. She applied this, first, to a banking career in Jordan and, later, to the information technology sector. After marrying Prince Abdullah bin Al Hussein on June 10, 1993, they went on to have four children: Prince Hussein, Princess Iman, Princess Salma, and Prince Hashem. In addition to being a wife and mother, Queen Rania works hard to lift the lives of Jordanians by supporting their endeavours and helping to create new opportunities for them. Locally, she is committed to breathe new life into the public education system; empower communities and women especially through microfinance initiatives; protect children and families; and drive innovation, technology and entrepreneurship, especially amongst young people. Internationally, Queen Rania is an advocate for tolerance, compassion and bridge building between people of all cultures and backgrounds. Her efforts to simultaneously challenge stereotypes of Arabs and Muslims, and promote greater understanding and acceptance between people of all faiths and cultures, have won her global recognition. Her Majesty’s passion is education. She believes that every Jordanian girl and boy, and all children, should have access not only to stimulating classrooms and modern curricula, but inspiring teachers and technology that can connect Jordan’s children to the world and the world to Jordan’s children. Her efforts in the education sector complement the work of the Ministry of Education through initiatives such as the Jordan Education Initiative, the Queen Rania Teachers Academy, Madrasati, Edraak and others. To realize these and so much more, Queen Rania has encouraged private sector partners to drive improvements and strengthen the foundations of Jordan’s education system. Queen Rania is also a global voice for access to quality education for children around the world. In 2009, Her Majesty championed the 1 Goal campaign for education; she is Honorary Chair of the UN Girl’s Education Initiatives and has advocated access to education in forums and gatherings around the world. Her work and her efforts to improve the learning opportunities for children have been recognized at the highest levels, nationally, regionally and internationally. Additionally, through her position on their boards, Her Majesty contributes to the work of the United Nations Fund and the World Economic Forum. She is the Eminent Advocate for UNICEF; and she was part of the UN appointed High Level Panel who advised on the shape and content of the Sustainable Development Goals which aim to improve the lives of millions of people before 2030. In recognition of her work, Her Majesty has humbly accepted many awards, locally, regionally and globally. These include the Walther Rathenau Award from the Walther RathenauInstitut in Germany for her efforts to greater peace and understanding; the James C. Morgan Global Humanitarian Award from Tech Awards, USA; the Arab Knight of Giving Award from Arab Giving Forum, UAE; the North South Prize by the North South Prize, Portugal; as well as the YouTube Visionary Award. Her Majesty authored several books primarily for children including the Sandwich Swap, which was inspired by her own childhood experiences.

scholarly journals Statherian (ca. 1714–1680 Ma) Extension-Related Magmatism and Deformation in the Southwestern Korean Peninsula and Its Geological Significance: Constraints from the Petrological, Structural, Geochemical and Geochronological Studies of Newly Identified Granitoids

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 557
Author(s):  
Byung-Choon Lee ◽  
Weon-Seo Kee ◽  
Uk-Hwan Byun ◽  
Sung-Won Kim
Keyword(s):  
Korean Peninsula ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Ductile Deformation ◽  
Southwestern Part ◽  
The North ◽  
Deformation Event ◽  
Geochemical Analyses ◽  
A Minor ◽  
T Values

In this study, petrological, structural, geochemical, and geochronological analyses of the Statherian alkali feldspar granite and porphyritic alkali feldspar granite in the southwestern part of the Korean Peninsula were conducted to examine petrogenesis of the granitoids and their tectonic setting. Zircon U-Pb dating revealed that the two granites formed around 1.71 Ga and 1.70–1.68 Ga, respectively. The results of the geochemical analyses showed that both of the granites have a high content of K2O, Nb, Ta, and Y, as well as high FeOt/MgO and Ga/Al ratios. Both granites have alkali-calcic characteristics with a ferroan composition, indicating an A-type affinity. Zircon Lu-Hf isotopic compositions yielded negative εHf(t) values (−3.5 to −10.6), indicating a derivation from ancient crustal materials. Both granite types underwent ductile deformation and exhibited a dextral sense of shear with a minor extension component. Based on field relationships and zircon U-Pb dating, it was considered that the deformation event postdated the emplacement of the alkali feldspar granite and terminated soon after the emplacement of the porphyritic alkali feldspar granite in an extensional setting. These data indicated that there were extension-related magmatic activities accompanying ductile deformation in the southwestern part of the Korean Peninsula during 1.71–1.68 Ga. The Statherian extension-related events are well correlated with those in the midwestern part of the Korean and eastern parts of the North China Craton.

Fertility in Cheviot ewes. 2. The effect of level of pre-mating nutrition on ovulation rate and early embryo mortality in North and South Country Cheviot ewes in moderately-good condition at mating

1979 ◽  
Vol 29 (1) ◽  
pp. 17-23 ◽  
Author(s):  
R. G. Gunn ◽  
J. M. Doney ◽  
W. F. Smith
Keyword(s):  
Food Intake ◽  
Good Condition ◽  
Early Embryo ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Restricted Feeding ◽  
Embryo Mortality ◽  
The North ◽  
Breed Difference ◽  
High Level

ABSTRACTIn two experiments over 2 years, 57 North Country Cheviot and 82 South Country Cheviot hill ewes were differentially group-fed indoors over a 2-month period to achieve either good or moderate body con- dition. Over 5 weeks prior to mating, ewes in good condition were brought down in condition by restricted feeding and ewes in mod- erate condition were raised in condition by a high level of feeding. The ewes were thus in moderately-good condition at mating. After mating, ewes were maintained in this condition until killed either on return to service or at 29 ± 8 days for counts of corpora lutea and viable embryos.Ovulation rate in each breed was positively related to the level of pre-mating food intake at the condition level studied. Embryo mortality, as ova loss, was not influenced overall by the level of pre-mating food intake but loss of multiple-shed ova was greater than that of single-shed ova in ewes which had been on restricted feeding before mating. Although a greater proportion of ewes in the North Country Cheviot breed were not pregnant at slaughter, this could not be identified as a breed difference since the breeds were studied in different years.

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