Torfajökull: a radiogenic end-member of the Iceland Pb-isotopic array

Stecher, Ole; Carlson, Richard W.; Gunnarsson, Björn

doi:10.1016/s0012-821x(98)00256-8

Cited by 62 publications

(33 citation statements)

References 32 publications

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“…1) Fig. 8 Variation diagram of 87 Sr/ 86 Sr vs. 143 Nd/ 144 Nd ratios for Katla (TIMS whole-rock analyses, this study), Quaternary to Recent Icelandic lavas (Thirlwall et al 2004), Öraefajökull (Prestvik et al 2001), Snaefell (Hards et al 2000), Torfajökull (Stecher et al 1999), and Hekla (Sigmarsson et al 1992). All data were normalised to the reference standards that were measured throughout the course of Katla sample analyses, averaging values of 87 Sr/ 86 Sr=0.710235±9 for NBS 987 standard and 143 Nd/ 144 Nd=0.5118220±8.5 for Johnson Matthey standard.…”

Section: Whole-rock Geochemistrymentioning

confidence: 80%

Bimodal volcanism at the Katla subglacial caldera, Iceland: insight into the geochemistry and petrogenesis of rhyolitic magmas

Lacasse¹,

Sigurdsson

Carey

et al. 2006

Bull Volcanol

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The Katla subglacial caldera is one of the most active and hazardous volcanic centres in Iceland as revealed by its historical volcanic activity and recent seismic unrest and magma accumulation. A petrologic and geochemical study was carried out on a suite of mid-Pleistocene to Recent lavas and pyroclastic rocks originated from the caldera. The whole series is characterised by a bimodal composition, including Fe-Ti transitional alkali basalts and mildly alkalic rhyolites. Variations in trace-element composition amongst the basalts and rhyolites show that their chemical differentiation was mainly controlled by fractional crystallisation and possible assimilation. The petrology and chemistry of the few intermediate extrusive rocks show that they were derived from magma mingling or hybridisation. The absence of extrusive rocks of true intermediate magmatic composition and the occurrence of amphibole-bearing felsic xenoliths support the hypothesis of partial melting of the hydrated basalt crust as the main process leading to the generation of rhyolites. The 143 Nd/ 144 Nd and 87 Sr/ 86 Sr values of Katla volcanic rocks fit the general isotopic array defined by late Quaternary to Recent lavas from Iceland. A few rock specimens are distinguished by low 143 Nd/ 144 Nd values suggesting assimilation and mixing of much older crustal material. Despite their similar whole-rock chemical compositions, the postglacial rhyolitic extrusives differ from the felsic xenoliths by their glass composition and the absence of amphibole. This, together with the general chemical trend of volcanic glasses, indicates that the postglacial rhyolitic extrusives were probably derived by a process involving late reheating and partial melting of crustal material by intrusion of basaltic magmas.

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Section: Whole-rock Geochemistrymentioning

confidence: 80%

Bimodal volcanism at the Katla subglacial caldera, Iceland: insight into the geochemistry and petrogenesis of rhyolitic magmas

Lacasse¹,

Sigurdsson

Carey

et al. 2006

Bull Volcanol

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“…Along-axis variations in trace element ratios and long-lived radiogenic isotopic ratios for the Reykjanes Ridge, Iceland, and the Kolbeinsey Ridge. Literature data shown as small black data points (O'Nions and Pankhurst, 1973;Schilling, 1975;Sun and Jahn, 1975;Cohen et al, 1980;Dupre and Allegre, 1980;Condomines et al, 1981;Schilling et al, 1983Schilling et al, , 1999Neumann and Schilling, 1984;Poreda et al, 1986;Furman et al, 1991;Mertz et al, 1991;Hemond et al, 1993;Devey et al, 1994;Hards et al, 1995;Hardarson and Fitton, 1997;Mertz and Haase, 1997;Salters and White, 1998;Stecher et al, 1999;Hanan et al, 2000;Hilton et al, 2000;Peate et al, 2001;Murton et al, 2002;Haase et al, 2003;Stracke et al, 2003aStracke et al, ,b, 2006Thirlwall et al, 2004;Blichert-Toft et al, 2005 (Figs. 3 and 4).…”

Section: Resultsmentioning

confidence: 99%

Understanding melt generation beneath the slow-spreading Kolbeinsey Ridge using 238U, 230Th, and 231Pa excesses

Elkins

Sims

Prytulak

et al. 2011

Geochimica et Cosmochimica Acta

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“…Katla: Hemond et al [1988Hemond et al [ , 1993; Condomines et al [1981Condomines et al [ , 1983; Sigmarsson et al [1992b]; Furman et al [1991], Park [1990]. Torfajoekull: Stecher et al [1999]. Hekla: Hemond et al [1988Hemond et al [ , 1993, Condomines et al [1981Condomines et al [ , 1983, Sigmarsson et al [1992a], Furman et al [1991], Park [1990].…”

Section: Geochemistry Geophysicsmentioning

confidence: 99%

Theistareykir revisited

Stracke

Zindler

Salters

et al. 2003

Geochem Geophys Geosyst

158

189

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[1] Postglacial basalts from Theistareykir (younger than 10,000 years), northern Iceland, define the depleted end of the spectrum of chemical and isotopic compositions observed in Icelandic volcanics but extend to some of the most enriched chemical and isotopic compositions found in Icelandic tholeiites. A spectacular feature of these basalts is the impressive correlations observed between radiogenic isotope ratios (Sr, Nd, Hf, and Pb) and almost the entire spectrum of major and trace element concentrations and ratios. The radiogenic isotope and major and trace element compositions are little affected by crystal fractionation and are essentially unaffected by interaction with the preexisting crust. The Theistareykir basalts must therefore be relatively close in composition to primary melts from the mantle. Consequently, their chemical and isotopic compositions provide a unique opportunity to investigate the nature of melting beneath Iceland and the geochemical character and origin of the mantle source. Large variations in incompatible element abundances require source heterogeneity, as well as variable extents of melting, to be important factors in determining the final chemical composition of the melts. Melting integrates over a large pressure range and is dominated by melting a depleted peridotite similar to the ambient depleted North Atlantic mantle. The isotopically enriched component is of relatively minor abundance and probably has a lower solidus temperature compared to the depleted component. More than one isotopically enriched component must be involved, but it is difficult to identify the end-member compositions using those of the lavas because of preeruptive averaging and damping of the enriched isotopic signals by mixing with the ambient depleted mantle or melts thereof, suggesting that the isotopic signals in Icelandic melts represent a somewhat muted isotopic signal of the enriched component(s) in the Icelandic source mantle. Comparison of the isotopic arrays of Icelandic basalts with those of global OIB suggests that the dominant enriched

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Torfajökull: a radiogenic end-member of the Iceland Pb-isotopic array

Cited by 62 publications

References 32 publications

Bimodal volcanism at the Katla subglacial caldera, Iceland: insight into the geochemistry and petrogenesis of rhyolitic magmas

Bimodal volcanism at the Katla subglacial caldera, Iceland: insight into the geochemistry and petrogenesis of rhyolitic magmas

Understanding melt generation beneath the slow-spreading Kolbeinsey Ridge using 238U, 230Th, and 231Pa excesses

Theistareykir revisited

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