title: Acigöl rhyolite field, central Anatolia (part II): geochemical and isotopic (Sr–Nd–Pb, δ¹⁸O) constraints on volcanism involving two high-silica rhyolite suites

authors: Siebel, Wolfgang

subjects: Acigöl

abstract: The Acigöl rhyolite field erupted the most recent high-silica rhyolites within the Cappadocian Volcanic Province of central Anatolia, Turkey. It comprises two sequences of domes and pyroclastic rocks with eruption ages of ∼150–200 ka (eastern group) and ∼20–25 ka (western group). Compositionally, the eastern rhyolite group lavas are less evolved (SiO₂ = 74–76 wt%), whereas the western group has higher silica abundance (SiO₂ = ∼77 wt%) with extremely depleted feldspar-compatible trace elements. Within each group, compositional variability is small and ¹⁴³Nd/¹⁴⁴Nd (0.51257–0.51265) and Pb isotope compositions (²⁰⁶Pb/²⁰⁴Pb = 18.87–18.88, ²⁰⁷Pb/²⁰⁴Pb = 15.65–15.67 and ²⁰⁸Pb/²⁰⁴Pb = 38.94–38.98) are homogeneous. The western group rhyolites have δ¹⁸O(zircon) overlapping mantle values (5.7 ± 0.2%), whereas eastern group rhyolites are enriched in d18O by ∼ 0.5%, consistent with a tendency to lower εNd values. By contrast, western group rhyolites have markedly more radiogenic ⁸⁷Sr/⁸⁶Sr ratios (0.7065–0.7091) compared to those of the eastern group (0.7059–0.7065). The presence of angular granitic xenoliths and a correlation between hydration (based on loss on ignition data) and ⁸⁷Sr/⁸⁶Sr in the western lavas, however, indicates that Sr was added during the eruption or posteruption alteration. Isotope constraints preclude the possibility that the rhyolite magmas formed by partial melting of any known regional crystalline basement rocks. Basalts and andesites erupted in the periphery of the Acigöl field are characterised by ⁸⁷Sr/⁸⁶Sr ratios between 0.7040 and 0.7053, ¹⁴³Nd/¹⁴⁴Nd = 0.51259–0.51300, ²⁰⁶Pb/²⁰⁴Pb = 18.85– 18.87, ²⁰⁷Pb/²⁰⁴Pb = 15.646–15.655, ²⁰⁸Pb/²⁰⁴Pb =38.90–38.97. The isotopic and trace element data favour an origin of the rhyolites by mixing of basaltic/andesitic magmas with minor amounts of crustal melts and followed by extensive fractional crystallization.

text: Acigöl rhyolite field, central Anatolia (part II): geochemical and isotopic (Sr–Nd–Pb, δ¹⁸O) constraints on volcanism involving two high-silica rhyolite suites The Acigöl rhyolite field erupted the most recent high-silica rhyolites within the Cappadocian Volcanic Province of central Anatolia, Turkey. It comprises two sequences of domes and pyroclastic rocks with eruption ages of ∼150–200 ka (eastern group) and ∼20–25 ka (western group). Compositionally, the eastern rhyolite group lavas are less evolved (SiO₂ = 74–76 wt%), whereas the western group has higher silica abundance (SiO₂ = ∼77 wt%) with extremely depleted feldspar-compatible trace elements. Within each group, compositional variability is small and ¹⁴³Nd/¹⁴⁴Nd (0.51257–0.51265) and Pb isotope compositions (²⁰⁶Pb/²⁰⁴Pb = 18.87–18.88, ²⁰⁷Pb/²⁰⁴Pb = 15.65–15.67 and ²⁰⁸Pb/²⁰⁴Pb = 38.94–38.98) are homogeneous. The western group rhyolites have δ¹⁸O(zircon) overlapping mantle values (5.7 ± 0.2%), whereas eastern group rhyolites are enriched in d18O by ∼ 0.5%, consistent with a tendency to lower εNd values. By contrast, western group rhyolites have markedly more radiogenic ⁸⁷Sr/⁸⁶Sr ratios (0.7065–0.7091) compared to those of the eastern group (0.7059–0.7065). The presence of angular granitic xenoliths and a correlation between hydration (based on loss on ignition data) and ⁸⁷Sr/⁸⁶Sr in the western lavas, however, indicates that Sr was added during the eruption or posteruption alteration. Isotope constraints preclude the possibility that the rhyolite magmas formed by partial melting of any known regional crystalline basement rocks. Basalts and andesites erupted in the periphery of the Acigöl field are characterised by ⁸⁷Sr/⁸⁶Sr ratios between 0.7040 and 0.7053, ¹⁴³Nd/¹⁴⁴Nd = 0.51259–0.51300, ²⁰⁶Pb/²⁰⁴Pb = 18.85– 18.87, ²⁰⁷Pb/²⁰⁴Pb = 15.646–15.655, ²⁰⁸Pb/²⁰⁴Pb =38.90–38.97. The isotopic and trace element data favour an origin of the rhyolites by mixing of basaltic/andesitic magmas with minor amounts of crustal melts and followed by extensive fractional crystallization.

year: 2011

title: “Why do teachers keep using American films when ours are so good?” The use of New Zealand screen content in New Zealand schools (Commissioned by New Zealand On Air)

authors: Lealand, Geoff

abstract: The purpose of this research is to investigate and report on the use of New Zealand screen content (feature film, short film, television programmes, documentaries, touch-screen apps, online resource portals and other forms of newer media content) in New Zealand formal schooling. The focus is on primary and intermediate schooling and secondary schooling to Year 13, with a particular emphasis on the four key subject areas of English, Media Studies, History and Social Studies in respect of secondary schools

text: “Why do teachers keep using American films when ours are so good?” The use of New Zealand screen content in New Zealand schools (Commissioned by New Zealand On Air) The purpose of this research is to investigate and report on the use of New Zealand screen content (feature film, short film, television programmes, documentaries, touch-screen apps, online resource portals and other forms of newer media content) in New Zealand formal schooling. The focus is on primary and intermediate schooling and secondary schooling to Year 13, with a particular emphasis on the four key subject areas of English, Media Studies, History and Social Studies in respect of secondary schools

year: 2016

title: The issues of the criminal justice system and of resources in Aotearoa/New Zealand

authors: Toki, Valmaine

abstract: Within the seven regions, recognized by the United Nations, various jurisdictions have acknowledged Indigenous rights within their respective constitutions. Although not explicit, some constitutional provisions, such as those included in the Norwegian Constitution, when read together with other articles, provide tentative opportunities for the implementation of an Indigenous legal system and an Indigenous court. Some Constitutions, such as that of Ecuador, are more explicit in providing constitutional recognition of an Indigenous legal system as well as rights to nature and, the interim Constitution of Nepal, courts for Indigenous Peoples.

text: The issues of the criminal justice system and of resources in Aotearoa/New Zealand Within the seven regions, recognized by the United Nations, various jurisdictions have acknowledged Indigenous rights within their respective constitutions. Although not explicit, some constitutional provisions, such as those included in the Norwegian Constitution, when read together with other articles, provide tentative opportunities for the implementation of an Indigenous legal system and an Indigenous court. Some Constitutions, such as that of Ecuador, are more explicit in providing constitutional recognition of an Indigenous legal system as well as rights to nature and, the interim Constitution of Nepal, courts for Indigenous Peoples.

year: 2014