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Publication
New K-Ar ages, chemical analyses and magnetic data of rocks from the Islands of Santa Maria (Azores), Porto Santo and Madeira (Madeira Archipelago) and Gran Canaria (Canary Islands)
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Advisor(s)
Abstract(s)
K/Ar determination, major and trace element chemical analyses and magnetic data are reported for rocks from Santa Maria (Azores), Madeira and Porto Santo, and Gran Canaria. Based on these data, the age of the basement of Santa Maria is believed to have formed between about 5.2 and 4.6 Ma, the unconformably overlying pillow complex interbedded with fossiliferous calcarenites about 3.8 to 3.3 Ma with the capping subaerial basalt being part of the same magmatic phase. The major erosional phase levelling the basement is thus approximately synchronous with the major Pliocene regression (R2) m Gran Canaria (Lietz and Schminke, 1975), possibly indicating a widespread eustatic event. The upper part of the submarine, partly fossiliferous series of Porto Santo was dated as ca. 12 to 13 Ma and the Quaternary age for the major basalt formation in Eastern Madeira (Watkins and Abdel Monem, 1971) is confirmed. The agess of several formations on Gran Canaria were slightly revised.
Chemical differences between basement (shield l) and later posterosional series on Gran Canaria are reemphasized by the new data, while such differences are much less pronounced between the basement and younger series on Santa Maria.
Description
Keywords
Geology Volcanic Rocks Canary Islands Madeira Archipelago Santa Maria Island (Azores) Azores
Pedagogical Context
Citation
FERRAUD, G.; SCHINCKE, H.-U. ; LIETZ,J. ; GOSTAUD, J. ; PRITCHARD, G. and BLEIL, U. (1984). New K-Ar ages, chemical analyses and magnetic data of rocks from the Islands of Santa Maria (Azores), Porto Santo and Madeira (Madeira Archipelago) and Gran Canaria (Canary Islands). "Arquipélago. Série Ciências da Natureza", 5: 213-240.