Mantle heterogeneity: isotopic and trace element evidence from Nunivak Island Alaska

The alkaline rocks of Carboniferous to Permian age in the Midland Valley province range in composition from hypersthene-normative, transitional basalts to strongly undersaturated basanitic and nephelinitic varieties. They were formed by varying degrees of equilibrium partial melting of a phlogopite peridotite mantle. Ba, Ce, Nb, P, Sr and Zr were strongly partitioned into the liquid during melting; K and Rb were retained by residual phlogopite for small degrees of melting only. The composition of the mantle source is inferred to have been broadly similar to that from which oceanic alkaline basalts are currently being generated. It was, however, heterogeneous as regards distribution of the incompatible trace elements, with up to fourfold variations in elemental abundances and ratios. The mantle beneath the province may be divisible into several areas, of some hundreds of square kilometres each, which retained a characteristic incompatible element chemistry for up to 50 Ma and which imparted a distinctive chemistry to all the basic magmas generated within them.

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Mantle heterogeneity beneath the Cenozoic volcanic provinces of central Victoria inferred from trace-element and Sr, Nd, Pb and Hf isotope data

Australian Journal of Earth Sciences ◽

10.1080/08120090500139448 ◽

2005 ◽

Vol 52 (2) ◽

pp. 243-260 ◽

Cited By ~ 24

Author(s):

B Paul ◽

JM Hergt ◽

JD Woodhead

Keyword(s):

Trace Element ◽

Hf Isotope ◽

Mantle Heterogeneity ◽

Central Victoria ◽

Isotope Data

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Mantle heterogeneity during the formation of the North Atlantic Igneous Province: Constraints from trace element and Sr-Nd-Os-O isotope systematics of Baffin Island picrites

Geochemistry Geophysics Geosystems ◽

10.1029/2004gc000743 ◽

2004 ◽

Vol 5 (11) ◽

pp. n/a-n/a ◽

Cited By ~ 54

Author(s):

A. J. R. Kent ◽

E. M. Stolper ◽

D. Francis ◽

J. Woodhead ◽

R. Frei ◽

...

Keyword(s):

Trace Element ◽

North Atlantic ◽

Baffin Island ◽

Mantle Heterogeneity ◽

The North ◽

Igneous Province ◽

O Isotope ◽

The North Atlantic ◽

North Atlantic Igneous Province ◽

Isotope Systematics

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Isotopic and trace element evidence from lavas, bearing on mantle heterogeneity beneath Kenya

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1980.0214 ◽

1980 ◽

Vol 297 (1431) ◽

pp. 259-271 ◽

Cited By ~ 75

Keyword(s):

Trace Element ◽

Incompatible Element ◽

General Trend ◽

Source Region ◽

Mantle Heterogeneity ◽

Pb Isotope ◽

Nd Isotope ◽

Northern Kenya ◽

Incompatible Elements ◽

Light Rare Earth Elements

Nd, Sr and Pb isotope data, together with new major and trace element data are presented for lavas from northern Kenya. A general trend towards silica saturation and decreasing incompatible element contents is observed from the Miocene to the present day. Significantly, the abundances of different incompatible elements decrease The Nd, Sr and Pb isotope compositions of the basic lavas are similar to those observed on the Atlantic ocean islands. Comparison of the Sm/Nd ratios required to produce the Nd isotope ratios with those observed in the rocks indicates that light rare earth elements (r.e.e.) have probably been added to the source region of the lavas comparatively recently. A model involving recent metasomatism of the subcontinental mantle beneath Kenya, which could account for the correlated silica undersaturation and incompatible element content of the lavas, is proposed.

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