The Role of Partial Melting in the 15-Ma Geochemical Evolution of Gran Canaria: A Blob Model for the Canary Hotspot

Abstract

The subaerial portion of Gran Canada, Canary Islands, was built by three cycles of volcanism: a Miocene Cycle (8-5-15 Ma), a Pliocene Cycle (1-8-60 Ma), and a Quaternary Cycle (1-8-0 Ma). Only the Pliocene Cycle is completely exposed on Gran Canaria; the early stages of the Miocene Cycle are submarine and the Quaternary Cycle is still in its initial stages. During the Miocene, SiO 2 saturation of the mafic volcanics decreased systematically from tholeiite to nephelinite. For the Pliocene Cycle, SiO 2 saturation increased and then decreased with decreasing age from nephelinite to tholeiite to nephelinite. SiO 2 saturation increased from nephelinite to basanite and alkali basalt during the Quaternary. In each of these cycles, increasing melt production rates, SiO 2 saturation, and concentrations of compatible elements, and decreasing concentrations of some incompatible elements are consistent with increasing degrees of partial melting in the sequence melilite nephelinite to tholeiite. The mafic volcanics from all three cycles were derived from CO 2-rich garnet lherzolite sources. Phlogopite, ilmenite, sulfide, and a phase with high partition coefficients for the light rare earth elements (LREE), U, Th, Pb, Nb, and Zr, possibly zircon, were residual during melting to form the Miocene nephelinites through tholeiites; phlogopite, ilmenite, and sulfide were residual in the source of the Pliocene-Quaternary nephelinites through alkali basalts. Highly incompatible element ratios (e.g.

Flow of Canary mantle plume material through a subcontinental lithospheric corridor beneath Africa to the Mediterranean: REPLY

“…(Fig. 1A) (Geldmacher et al, 2005;Hoernle and Schmincke, 1993;Hoernle et al, 1991;Lundstrom et al, 2003). The age progression can be explained by movement of the lithosphere above a deeper upwelling using the same Euler pole and angular plate velocity as other volcanic chains in the Atlantic Ocean.…”

Seismic properties of the upper mantle beneath Lanzarote (Canary Islands): Model predictions based on texture measurements by EBSD

“…Schmincke, 1982;Holik et al, 1991;Watts, 1994;Hoernle et al, 1995, Neumann et al, 1995Carracedo et al, 1998;Dañobeitia and Canales, 2000;Rhodes and Davies, 2001). However, numerous inconsistencies between the evolution of the Canary Islands and the classical hot spot scheme have been reported by Hoernle and Schmincke (1993). To explain these differences, these authors suggested that the Canary Islands plume corresponds to a "blob type" (Allègre et al, 1984) hot spot, whereas others (Anguita and Hernán, 2000) proposed a unifying model partly reconciling three of the historically cited hypotheses, thus giving more weight to the regional tectonics.…”

Late Cenozoic Global Pulsations in Hotspot Magmatism and their Possible Interplay with Plate Tectonics, Earth's Core and Climate

“…9). Cape Verde and the Canaries show an increase in magmatism since about 3 Ma, but it is likely that the peak occurred at 0.5 Ma (refs [13][14][15][16][17]. The Madeira Province shows the same trend, with increasing magmatism since 3.5 Ma, probably reaching a peak at about 1 Ma (ref.…”