10. NEOGENE AND QUATERNARY PLANKTONIC FORAMINIFERAL BIOSTRATIGRAPHYOF THE CANARY ISLAND REGION 1Rosanna Maniscalco 2 and Charlotte A. Brunner 3 |
ABSTRACTWe examined planktonic foraminifers from Sites 953 and 954 in the Canary Island region. Site 953 is stratigraphically the best site with a complete Quaternary to middle Miocene sequence of pelagic and volcaniclastic sediments deposited in the sedimentary basin north of Gran Canaria. At Site 954, on the island flank, several distinct unconformities disrupt the sequence, complicating the biostratigraphy. We adopted the zonation of Berggren (1973, 1977) and Berggren et al. (1983, 1995b) and recognized several of Berggren’s zones, although some difficulties arose because of the absence of many zonal markers from the area and the diachronism of several species. Additionally, preservation is poor in the Miocene, hindering zonal assignment by reducing or eliminating the more solution-susceptible species. We placed the Pliocene/Pleistocene boundary above the last occurrence of Globigerinoides obliquus extremus Bolli and Bermudez following the suggestion of Berggren et al. (1995b), because Globigerinoides fistulosus, whose last occurrence defines the base of Zone PT1, does not occur in our samples. We did not use the first occurrence of Globorotalia truncatulinoides (d’Orbigny) because it is diachronous in the Atlantic Ocean. We consider the highest occurrence of the planktonic foraminifer Globorotalia juanai Bermudez and Bolli a useful datum marker to define the Miocene/Pliocene boundary in the Canary Island region, where the last occurrence of Globoquadrina dehiscens (Chapman, Parr, and Collins), recorded within upper Chron C5n at Sites 953 and 954, and the first occurrence of Globorotalia tumida (Brady), which is rare and sporadic, are not useful for this purpose. |
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