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  • 1
    Electronic Resource
    Electronic Resource
    Geochronology and palaeomagnetism of a late Proterozoic island arc terrane from the Red Sea Hills, northeast Sudan
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 114 (1992), S. 1-15 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(92)90148-O
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  • 2
    Electronic Resource
    Electronic Resource
    The Pan-African continental margin in northeastern Africa: evidence from a geochronological study of granulites at Sabaloka, Sudan
    Amsterdam : Elsevier
    Earth and Planetary Science Letters 85 (1987), S. 91-104 
    Details
    ISSN: 0012-821X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0012-821X(87)90024-0
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  • 3
    Electronic Resource
    Electronic Resource
    Trace element and isotopic composition of baddeleyite (1995)
    Springer
    Mineralogy and petrology 53 (1995), S. 155-164 
    Details
    ISSN: 1438-1168
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Description / Table of Contents: Zusammenfassung Baddeleyit vom Palabora Igneous Complex, Südafrika, gehört zu den reinsten natürlichen Vorkommen von ZrO2. Dies wurde durch Analysen mit verschiedenen Methoden wie Mikrosonde, Neutronenaktivierung, Funken- und Thermionenmassenspektrometrie bestätigt. HfO2 ist mit 1.87 die einzige andere Hauptkomponente, auch die Konzentrationen der anderen HFSE sind relativ hoch im Vergleich zu den anderen Elementen, die nur wenige ppm erreichen. Die REE bilden ein U-förmiges Muster, das als Ausdruck einer stark LREE angereicherten Komponente im Ausgangsgestein gedeutet wird. Das hohe87Sr/86Sr-Initialverhältnis von 0.713085 und das negative ɛNdt von -10.7 belegen, daß diese Komponente über einen langen Zeitraum vor der Bildung des Palabora Igneous Complex angereichert gewesen war. Diese Daten deuten an, daβ der Baddeleyit aus einem Magma kristallisierte, das aus einem angereicherten Mantelreservoir stammte, ähnlich dem, das bei der Bildung der Gruppe 11 Kimberlite beteiligt war.
    Notes: Summary Baddeleyite from Palabora Igneous Complex, South Africa, is among the purest natural ZrO2 phases. This has been demonstrated by using various methods, i.e. microprobe, neutron activation, spark source and thermal ion mass spectrometry. HfO2 with 1.87% is the only other major component. The concentrations of other HFSE are also relatively high, compared to most other elements, that reach only a few ppm. The REE display a U-shaped pattern that is interpreted to be superimposed by a strongly LREE enriched source component. The high87Sr/86Sr initial of 0.713085 and the negative ɛNdt of −10.7 prove that this component was LILE enriched for a long time prior to the formation of the Palabora Igneous Complex. These data indicate that the baddeleyite crystallized from a magma which was derived from an enriched mantle reservoir, similar to that involved in the formation of group II kimberlites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01171953
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  • 4
    Electronic Resource
    Electronic Resource
    Precambrian basement around Wadi Halfa, Sudan: a new perspective on the evolution of the East Saharan Craton (1994)
    Springer
    International journal of earth sciences 83 (1994), S. 564-577 
    Details
    ISSN: 1437-3262
    Keywords: Precambrian ; Geochronology ; Geochemistry ; Crustal evolution ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This paper provides new geochemical and isotopic data on the evolution of the western foreland to the Nubian shield of north-east Africa. There is abundant evidence for early to middle Proterozoic crust west of the River Nile, but this was severely affected by the Pan-African (≈ 500–900 Ma) orogenic cycle. The results are reported of Rb-Sr whole rock and zircon evaporation geochronological studies and whole rock Sm-Nd and feldspar Pb isotopic analyses for four rock units around Wadi Halfa in northernmost Sudan. These results indicate the presence of heterogeneous pre-Pan-African crustal components, preserved in mylonitic gneisses and in conglomerates that unconformably overlie the gneisses. Several episodes of crust formation, inferred from zircon ages, are preserved in the gneisses : 2.6, 2.4, 2.0, 1.7, 1.2 and 0.72 Ga. Nd model ages for the same units are invariably older than the zircon ages, yet still record a predominantly late Archaean and Palaeoproterozoic history, with depleted mantle model ages between 1.3 and 2.8 Ga. The earliest recorded Pan-African magmatic event is about 720 Ma and dates the beginning of collisional deformation. A younger Pan-African volcanic sequence (≈ 650 Ma) has isotopic compositions of Sr and Nd compatible with derivation from late Prote rozoic asthenospheric mantle. A ≈ 530 Ma anorogenic ‘A-type’ granite also has isotopic compositions suggesting derivation from a primitive source. The inferred tectonic evolution began with rifting to form an oceanic re-entrant. This was followed by subduction leading to collision at about 700 Ma, accompanied by post-orogenic rifting at about 650 Ma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01083228
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  • 5
    Electronic Resource
    Electronic Resource
    Precambrian basement around Wadi Haifa, Sudan: a new perspective on the evolution of the East Saharan Craton (1994)
    Springer
    International journal of earth sciences 83 (1994), S. 564-577 
    Details
    ISSN: 1437-3262
    Keywords: Precambrian ; Geochronology ; Geochemistry ; Crustal evolution ; Africa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This paper provides new geochemical and isotopic data on the evolution of the western foreland to the Nubian shield of north-east Africa. There is abundant evidence for early to middle Proterozoic crust west of the River Nile, but this was severely affected by the Pan-African (≈ 500–900 Ma) orogenic cycle. The results are reported of Rb-Sr whole rock and zircon evaporation geochronological studies and whole rock Sm-Nd and feldspar Pb isotopic analyses for four rock units around Wadi Halfa in northernmost Sudan. These results indicate the presence of heterogeneous pre-Pan-African crustal components, preserved in mylonitic gneisses and in conglomerates that unconformably overlie the gneisses. Several episodes of crust formation, inferred from zircon ages, are preserved in the gneisses : 2.6, 2.4, 2.0, 1.7, 1.2 and 0.72 Ga. Nd model ages for the same units are invariably older than the zircon ages, yet still record a predominantly late Archaean and Palaeoproterozoic history, with depleted mantle model ages between 1.3 and 2.8 Ga. The earliest recorded Pan-African magmatic event is about 720 Ma and dates the beginning of collisional deformation. A younger Pan-African volcanic sequence (≈ 650 Ma) has isotopic compositions of Sr and Nd compatible with derivation from late Prote rozoic asthenospheric mantle. A ≈ 530 Ma anorogenic ‘A-type’ granite also has isotopic compositions suggesting derivation from a primitive source. The inferred tectonic evolution began with rifting to form an oceanic re-entrant. This was followed by subduction leading to collision at about 700 Ma, accompanied by post-orogenic rifting at about 650 Ma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194162
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  • 6
    Electronic Resource
    Electronic Resource
    Late proterozoic island arc volcanics from Gebeit, Red Sea Hills, north-east Sudan (1994)
    Springer
    International journal of earth sciences 83 (1994), S. 547-563 
    Details
    ISSN: 1437-3262
    Keywords: Red Sea Hills ; Sudan ; Arabian-Nubian Shield ; Late Proterozoic ; Island arc volcanics ; Geochronology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The area of Gebeit Mine in the northern Red Sea Hills, Sudan, is built up of voluminous volcanic rocks and minor volcaniclastic and clastic sequences. According to their chemical and modal compositions the Gebeit volcanics can be devided into four groups: (a) cpx-physic basalts with clinopyroxene and plagioclase as the dominant phenocrysts and minor opaques; (b) hbl-physic basalts with hornblende, clinopyroxene, plagioclase and subordinate magnetite including one rare dacite; (c) pl-phyric andesites with plagioclase phenocrysts in a matrix that is rich in magnetite; and (d) aphyric basalts. The compositional variation within the distinct volcanic groups can only partly be explained by fractional crystallization, and more than one magma source reservoir is required. Mineral and whole rock Sm/Nd data for the cpx-physic and hbl-physic basalts yield an isochron age of 832 ± 26 Ma (ɛNdT = 6.74 ± 0.19, MSWD = 0.12) which is interpreted as the age of eruption. The ɛNdt values for the aphyric basalts and pl-physic andesites range from 6.7 to 8.3, indicating the involvement of different depleted magma sources. The Nd and Sr isotopic data rule out any significant influence of older continental crust in the formation of the Gebeit volcanics and indicate an intraoceanic origin. This implies that the Gebeit terrane is a segment of juvenile crust that originated in a subduction-related environment and supports the arc accretion model for the Arabian-Nubian Shield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01083227
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  • 7
    Electronic Resource
    Electronic Resource
    Late proterozoic island arc volcanics from Gebeit, Red Sea Hills, north-east Sudan (1994)
    Springer
    International journal of earth sciences 83 (1994), S. 547-563 
    Details
    ISSN: 1437-3262
    Keywords: Red Sea Hills ; Sudan ; Arabian-Nubian Shield ; Late Proterozoic ; Island arc volcanics ; Geochronology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The area of Gebeit Mine in the northern Red Sea Hills, Sudan, is built up of voluminous volcanic rocks and minor volcaniclastic and clastic sequences. According to their chemical and modal compositions the Gebeit volcanics can be devided into four groups: (a) cpx-physic basalts with clinopyroxene and plagioclase as the dominant phenocrysts and minor opaques; (b) hbl-physic basalts with hornblende, clinopyroxene, plagioclase and subordinate magnetite including one rare dacite; (c) pl-phyric andesites with plagioclase phenocrysts in a matrix that is rich in magnetite; and (d) aphyric basalts. The compositional variation within the distinct volcanic groups can only partly be explained by fractional crystallization, and more than one magma source reservoir is required. Mineral and whole rock Sm/Nd data for the cpx-physic and hbl-physic basalts yield an isochron age of 832 ± 26 Ma (ɛNdT = 6.74 ± 0.19, MSWD = 0.12) which is interpreted as the age of eruption. The ɛNdt values for the aphyric basalts and pl-physic andesites range from 6.7 to 8.3, indicating the involvement of different depleted magma sources. The Nd and Sr isotopic data rule out any significant influence of older continental crust in the formation of the Gebeit volcanics and indicate an intraoceanic origin. This implies that the Gebeit terrane is a segment of juvenile crust that originated in a subduction-related environment and supports the arc accretion model for the Arabian-Nubian Shield.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194161
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  • 8
    Electronic Resource
    Electronic Resource
    Further evidence for an early Carboniferous (∼340 Ma) age of high-grade metamorphism in the Saxonian granulite complex (1998)
    Springer
    Geologische Rundschau 86 (1998), S. 751-766 
    Details
    ISSN: 0016-7835
    Keywords: Key words Saxonian granulite complex ; Zircon geochronology ; High-grade metamorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  U–Pb and Pb–Pb zircon ages for metamorphic zircons from granulites in the Saxonian granulite complex are reported, using the SHRIMP ion microprobe, conventional multigrain and single-gain techniques and the evaporation method. This is complemented by a Pb–Pb evaporation age for a post-granulite granite emplaced into the schist mantle around the granulites during uplift of the complex. We also demonstrate that zircon ages are not reset during high-grade metamorphism, as commonly argued, but have a very high closure temperature and usually preserve the isotopic composition reflecting the time of their formation. Multifaceted zircons from four granulite samples that probably grew close to the peak of high-grade metamorphism yielded identical U–Pb and Pb–Pb ages of ∼340 Ma which support previously published data and unambiguously show that the granulites formed during a lower Carboniferous event and not in the early Palaeozoic or Precambrian as previously suggested. Older cores in some of the metamorphic zircons reveal early Palaeozoic components at 470–485 Ma that we interpret as ages reflecting magmatic crystallization of the granulite precursors. One sample suggests an inherited component as old as ∼1700 Ma. The post-granulite granite has a Pb–Pb evaporation age of 333.1±1.0 Ma, and the short time interval between granulite metamorphism and granite intrusion implies that uplift, crustal extension and cooling of the granulite complex occurred rapidly after peak metamorphic conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009939
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  • 9
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    Unknown
    Late Proterozoic and Silurian basement units within the Serbo-Macedonian Massif, northern Greece: the significance of terrane accretion in the Hellenides (2007)
    In:  Geological Society Special Publication 260: 35-50.
    Details
    Publication Date: 2007-10-08
    Description: The Serbo-Macedonian Massif (SMM) is a large, elongate basement complex in the Internal Hellenides, which stretches from Serbia to the Chalkidiki Peninsula in northern Greece. As a result of similarities in lithology and structural grain, the SMM has long been considered part of the adjacent Rhodope Massif. Recent work, however, based on precise geochronological and geochemical data, has revealed that the SMM is not a homogeneous crustal entity but made up of several crustal units, only one of which is related to the Rhodope Massif. One of these units, the Pirgadikia Unit, occurs as a tectonic sliver in a melange zone bordering the western margin of the SMM that separates it from the adjacent Vardar Zone. The Pirgadikia Unit consists of leucocratic mylonitic para- and orthogneisses. According to trace-element and Sr-isotope data, the orthogneisses originated in a magmatic arc setting. Dating of this unit by the Pb-Pb single-zircon evaporation method yielded Pan-African ages of 555.8{+/-}2.6 Ma on a paragneiss collected near the village of Taxiarchis, and two ages of 570.0{+/-}7.0 Ma and 587.6{+/-}3.4 Ma on orthogneisses from the quayside at Pirgadikia village. The rocks enveloping this Late Precambrian basement complex are gneisses of the Vertiskos Unit. This unit, which is regarded as a distinct terrane, occupies the northwestern part of the Greek SMM and consists of Silurian orthogneisses with a magmatic arc signature and subordinate metasediments. Orthogneisses of the Vertiskos Unit adjacent to the mylonites of the Pirgadikia Unit gave Pb-Pb ages of between 428.2{+/-}1.2 Ma and 433.0{+/-}2.1 Ma. One of these samples was additionally dated by the conventional U-Pb method. This sample has three concordant zircon grains confirming a Silurian intrusion age and two inherited cores pointing to an older basement into which precursor rocks to the Silurian gneisses were intruded. The upper intercept of a Concordia plot yielded an age of c. 2.5 Ga, which is a common age in the cratons of Gondwana. The Pan-African age of the Pirgadikia Unit and the inherited ages of the Vertiskos Unit support the notion that these units are terranes derived from Gondwana. They were finally accreted to the Hellenic orogen during the closure of one of the branches of the Tethys Ocean. The presence of exotic terranes in the Internal Hellenides contradicts the hypothesis that this part of the Hellenides formed a stable hinterland during the Alpine phase and thus the Hellenides can be considered an accretionary orogen.
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  • 10
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    Unravelling the magma plumbing systems of El Reventador and Sumaco active volcanoes (Sub-Andean zone, Ecuador) through a comprehensive stratigraphic and petrological study of the extrusive sequences. Cities On Volcanoes 4 (2006)
    In:  Quito, Ecuador
    Details
    Publication Date: 2006
    Keywords: TF II ; Task Force II ; New tectonic causes of volcano failure
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