The origin of the Canary Island Seamount Province - New ages of old seamounts

Abstract

The Canary Island Seamount Province forms a scattered hotspot track on the Atlantic ocean floor ~1300 km long and ~350 km wide, perpendicular to lithospheric fractures, and parallel to the NW African continental margin. New 40Ar/39Ar datings show that seamount ages vary from 133 Ma to 0.2 Ma in the central archipelago, and from 142 Ma to 91 Ma in the southwest. Combining 40Ar/39Ar ages with plate tectonic reconstructions, I find that the temporal and spatial distribution of seamounts is irreconcilable with a deep fixed mantle plume origin, or derivation from passive mantle upwelling beneath a mid-ocean ridge. I conclude that shallow mantle upwelling beneath the Atlantic Ocean basin off the NW African continental lithosphere flanks produced recurrent melting anomalies and seamounts from the Late Jurassic to Recent, nominating the Canary Island Seamount Province as oldest hotspot track in the Atlantic Ocean, and most long-lived preserved on earth.

Back to Gondwanaland: can ancient vicariance explain (some) Indian Ocean disjunct plant distributions?

“…We set this calibration to 21 Myr ago, which represents an estimate of the age of the current terrestrial habitat [23]. However, the Canary Island Seamount Province dates as far back as 142 Myr ago [25] and the degree of emergence during this time is uncertain. Using 21 Myr ago therefore represents a bias against inferring vicariance, with older maximum constraints less likely to reject the hypothesis.…”

Three-armed rifts or masked radial pattern of eruptive fissures? The intriguing case of El Hierro volcano (Canary Islands)

“…1). Its morphology has been moulded by three amphitheatres (El Golfo, Las Playas and El Julan) that correspond to the headwall scarps of giant landslides (Carracedo et al, 1999(Carracedo et al, , 2001Longpré et al, 2011;Masson, 1996;Masson et al, 2002;Urgeles et al, 1996Urgeles et al, , 1997.…”

Assessment of the Mineral Resource Potential of Atlantic Ferromanganese Crusts Based on Their Growth History, Microstructure, and Texture

“…The seamount (Figure 1) is located off the passive continental margin of West Africa. K-Ar and Ar-Ar dating of volcanic rocks from Tropic Seamount suggest it was active from 119 Ma until 114 Ma, although some smaller, late-stage eruptive activity may have persisted until 60 Ma [22], since which time the volcano has subsided with the summit now at a depth of around 1100 m. While the absolute oldest possible age for FeMn crust precipitation is the age of the volcano, FeMn crust growth is thought to have been occurring for at least the last 12 Ma on sediment-free slopes and areas of the summit and 76 Ma elsewhere [23][24][25]. More recently, Marino et al [26] identified crusts as old as 99 Ma from near the summit of Tropic Seamount.…”

“…Phosphatized samples consisting primarily of carbonate fluorapatite were also dredged off the eastern flank. Measured bulk contents were 13-28 wt% Fe, [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] wt% Mn, and 0-0.72 wt% Co. Growth rates estimated using the Co-chronometer were between 1.19 mm/Ma and 2.66 mm/Ma [19]. Bathymetry data is taken from GEBCO [27].…”