Helium isotopes in early Iceland plume picrites: Constraints on the composition of high 3He/4He mantle

Starkey, N. A.; Stuart, Finlay M.; Ellam, Robert M.; Fitton, J. Godfrey; Basu, Sudeshna; Larsen, Lotte Melchior

doi:10.1016/j.epsl.2008.10.007

Cited by 122 publications

(116 citation statements)

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“…There is no evidence for mobilization of other elements (like Ba and U) in this sample. The Pb concentration was not reported for this sample [Starkey et al, 2009]. Finally, the Nb/Ta ratio (11.0) suggests no evidence for contamination by W-carbide, and the positive Nb anomaly in DUR8 appears to be a primary magmatic feature inherited from the high 3 He/ age, and degassing rate overtime [Allègre et al, 1996].…”

Section: Geodynamic Implications For Amentioning

confidence: 99%

“…Melting models applied to the nonchondritic BSE (see Table 3) yield calculated melt spidergrams that are similar to the highest 3 He/ 4 He lava globally (sample DUR8 from Baffin Island) [Starkey et al, 2009]. See section 4 for details.…”

Section: Geodynamic Implications For Amentioning

confidence: 99%

“…[34] Jackson et al [2010] suggested that the highest 3 He/ 4 He lavas erupted globally (up to 50 Ra, ratio to atmospheric), from the Baffin Island flood basalt [Stuart et al, 2003;Starkey et al, 2009], are melts of an early-formed depleted mantle reservoir with high 3 He/ 4 He, which we argue represents the lithophile element composition of a nonchondritic BSE. We explore whether melts of the nonchondritic BSE calculated here (Table 3) can yield trace element patterns that resemble the highest 3 He/ select the highest 3 He/ 4 He lava (DUR8 from Starkey et al, 2009) from Baffin Island and correct the trace element abundances for olivine fractionation by adding equilibrium olivine until the lava is in equilibrium with Fo 90 olivine (see method in Jackson et al [2010]).…”

Section: Melting the Nonchondritic Bse Composition To Make High 3 He/mentioning

confidence: 99%

“…Finally, we show that the trace element budget satisfies geochemical constraints for the formation of continental crust, provides a possible solution to the long-standing ''missing Ar'' paradox, and is consistent with plausible models for the thermal evolution of the Earth, which predict a delayed onset of core convection and dynamo action (section 5). [Stuart et al, 2003;Jackson et al, 2007;Starkey et al, 2009 Allègre et al, 1979;DePaolo and Wasserburg, 1979;DePaolo, 1980;Patchett et al, 1981;Salters and Hart, 1991;Vervoort et al, 1999;Chauvel et al, 2008;Bouvier et al, 2008;Caro and Bourdon, 2010] [12] Armed with estimates for the Nd, Hf and Sr isotopic compositions of a nonchondritic BSE, it is possible to calculate the present-day parent-daughter ratios of these three isotopic systems assuming closed-system isotopic evolution for 4.567 Ga, an age that is consistent with Pb [Jackson et al, 2010] and Xe [Mukhopadhyay, 2012] He lavas from Baffin Island and the associated Iceland hotspot. We follow Caro and Bourdon [2010] and Jackson et al [2010] and assume that the initial Nd, Hf, and Sr isotopic compositions and associated parent-daughter ratios of BSE (or the planetesimals that differentiated before accreting to form the Earth) were chondritic.…”

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confidence: 99%

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Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth

Jackson

Jellinek

2013

Geochem Geophys Geosyst

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[1] The bulk composition of the silicate portion of the Earth (BSE) has long been assumed to be tied to chondrites, in which refractory, lithophile elements like Sm and Nd exist in chondritic relative abundances. However, the Nd from 0.51263 (chondritic) to 0.51300. The new BSE composition is depleted in highly incompatible elements, including K, relative to the chondrite-based BSE, and offers a solution the ''missing '' 40 Ar paradox. This BSE compositional model requires that >83% of the mantle is depleted to form continental crust. It also implies a $30% reduction in BSE U, Th and K, and therefore in the current rate of radiogenic heating and, thus, a proportional increase in the heat flow delivered to surface by plate tectonics. We explore thermal history models including effects related to a newly recognized evolution in the style of plate tectonics over Earth history: The lower radiogenic heat production may delay the onset of core convection and dynamo action to as late as 3.5 Gyr.

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Section: Geodynamic Implications For Amentioning

confidence: 99%

Section: Geodynamic Implications For Amentioning

confidence: 99%

Section: Melting the Nonchondritic Bse Composition To Make High 3 He/mentioning

confidence: 99%

mentioning

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Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth

Jackson

Jellinek

2013

Geochem Geophys Geosyst

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“…The earliest magmatism associated with the ancestral Iceland plume, for example, produced basalts in Baffin Island and West Greenland with compositions very similar to N-and E-MORB (Robillard et al 1992;Starkey et al 2009). (Li et al 2008;Pease et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Geochemical evolution of Dalradian metavolcanic rocks: implications for the break-up of the Rodinia supercontinent

Fettes

Macdonald

Fitton

et al. 2011

JGS

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Temperature fluctuation of the Iceland mantle plume through time

Spice

Fitton

Kirstein

2016

Geochem Geophys Geosyst

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The newly developed Al-in-olivine geothermometer was used to find the olivine-Cr-spinel crystallization temperatures of a suite of picrites spanning the spatial and temporal extent of the North Atlantic Igneous Province (NAIP), which is widely considered to be the result of a deep-seated mantle plume. Our data confirm that start-up plumes are associated with a pulse of anomalously hot mantle over a large spatial area before becoming focused into a narrow upwelling. We find that the thermal anomaly on both sides of the province at Baffin Island/West Greenland and the British Isles at $61 Ma across an area $2000 km in diameter was uniform, with Al-in-olivine temperatures up to $300 C above that of average mid-ocean ridge basalt (MORB) primitive magma. Furthermore, by combining our results with geochemical data and existing geophysical and bathymetric observations, we present compelling evidence for long-term (>10 7 year) fluctuations in the temperature of the Iceland mantle plume. We show that the plume temperature fell from its initial high value during the start-up phase to a minimum at about 35 Ma, and that the mantle temperature beneath Iceland is currently increasing.

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Helium isotopes in early Iceland plume picrites: Constraints on the composition of high 3He/4He mantle

Cited by 122 publications

References 72 publications

Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth

Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth

Geochemical evolution of Dalradian metavolcanic rocks: implications for the break-up of the Rodinia supercontinent

Temperature fluctuation of the Iceland mantle plume through time

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Helium isotopes in early Iceland plume picrites: Constraints on the composition of high 3He/4He mantle

Cited by 122 publications

References 72 publications

Major and trace element composition of the high 3He/4He mantle: Implications for the composition of a nonchonditic Earth

Major and trace element composition of the high 3He/4He mantle: Implications for the composition of a nonchonditic Earth

Geochemical evolution of Dalradian metavolcanic rocks: implications for the break-up of the Rodinia supercontinent

Temperature fluctuation of the Iceland mantle plume through time

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Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth

Major and trace element composition of the high ³He/⁴He mantle: Implications for the composition of a nonchonditic Earth