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| Detailed Reference Information |
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Geldmacher, J., Hoernle, K., van den Bogaard, P., Zankl, G. and Garbe-Schoenberg, D. (2001). Earlier history of the > or =70-Ma-old Canary Hotspot based on the temporal and geochemical evolution of the Selvagen Archipelago and neighboring seamounts in the eastern North Atlantic. Journal of Volcanology and Geothermal Research 111(1-4): 55-87. |
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Major element, trace element and Sr-Nd-Pb isotope data, combined with (super 40) Ar/ (super 39) Ar age determinations, of volcanic rocks from the Selvagen Islands and neighboring seamounts in the eastern North Atlantic reveal the earlier history of the > or =70 Ma old Canary hotspot. A basanitic to phonolitic late shield stage intrusive complex (29 Ma) is exposed on Selvagem Pequena. The evolution of Selvagem Grande can be divided into three magmatic phases: a tephritic to phonolitic late shield stage intrusive complex (24-26 Ma) and two rejuvenated or post-erosional stages (8-12 and 3.4 Ma) consisting of alkali basalt, basanite and rare phonolite. During the early to mid-Miocene volcanic hiatus (12-24 Ma), the top of the volcano was beneath sea level as evidenced by marine carbonate sediments (13-24 Ma, dated through correlation of (super 87) Sr/ (super 86) Sr with the seawater Sr isotope curve). The geochemistry of the shield stage lavas indicates that they derive from plume sources, whereas the post-erosional lavas are derived from metasomatized lithospheric sources. Five sampled seamounts to the east and northeast of the islands range in composition from alkali basalt and basanite to phonolite. Samples from Dacia, Conception Bank and Lars were dated at 9, 17 and 68 Ma, respectively. Geochemical data suggest that the dredged samples come from the post-erosional stage of volcanism, and therefore, the dates represent minimum ages for the seamount volcanoes. The elevation of erosional platforms formed at wave base decrease from Selvagen Grande (approximately 100 m above sea level) to Lars seamount (approximately 900 m below sea level), suggesting a southwest to northwest age progression and that all of these seamounts are older than the Selvagen Islands. Trace element and Sr-Nd-Pb isotopic composition of the Selvagen Islands and neighboring seamounts are consistent with their origin from the Canary plume. Interaction of the weak Canary mantle plume with a slow moving plate appears to be responsible for generating a 450-km-wide, irregular hotspot track extending 800 km from the youngest Canary Island of Hierro in the southwest to Lars seamount in the northeast. |
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| BACKGROUND DATA FILES |
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Appendix A.1: Dredge Haul Locations |
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Appendix A.2: Sample Preparation & Analytical Techniques |
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Table A1a |
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Table A1b |
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Table A1c |
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Table A1d |
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Table A2a |
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Table A2b |
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40Ar/39Ar Age Determinations |
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Keywords
absolute age, alkali basalts, alkaline earth metals, Ar/Ar, Atlantic, Ocean, Atlantic Ocean Islands, basalts, basanite, Canary Islands, Cenozoic, chemical ratios, dates, emplacement, geochemistry, hot, spots, igneous rocks, isotope ratios, isotopes, lead, lithofacies, magmatism, major elements, mantle, mantle plumes, metals, Miocene, Neogene, North Atlantic, ocean floors, Pb-208/Pb-206, plate tectonics, seamounts, Selvagen Islands, Sr-87/Sr-86, stable isotopes, strontium, Tertiary, volcanic rocks, 18 Solid-earth geophysics, 12 Stratigraphy |
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Publisher
Elsevier Science
P.O. Box 211
1000 AE Amsterdam
The Netherlands
(+31) 20 485 3757
(+31) 20 485 3432
nlinfo-f@elsevier.com |
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