Weaver, P.P.E., Schmincke, H.-U., Firth, J.V., and Duffield, W. (Eds.), 1998 Proceedings of the Ocean Drilling Program, Scientific Results, Vol. 157 83 8. CALCAREOUS NANNOFOSSIL BIOSTRATIGRAPHY OF SITE 953, CANARY BASIN, NORTHEASTERN NORTH ATLANTIC 1 JoAnne Sblendorio-Levy 2 and Richard W. Howe 3 ABSTRACT Site 953 in the Northeastern Atlantic, northeast of Gran Canaria, recovered an essentially complete Pleistocene to middle Miocene biostratigraphic record. Quantitative analysis of the calcareous nannofossils identified 57 calcareous nannofossil events. Forty-seven of these events have been tied, where possible, to the paleomagnetic record (Schmincke, Weaver, Firth, et al., 1995; B. Herr, pers. comm., 1996) and to the radiometric ages generated by Bogaard (Chap. 19, this volume) for this site. INTRODUCTION Location and Setting Site 953 is located at 28°39.012′N, 15°8.670′E in the North Atlantic in 3577.8 m of water (Fig 1). It is situated 45 km northeast of Gran Ca- naria, 100 km west of Fuerteventura, and 100 km east of Tenerife. It is the most distally located site on the flanks of Gran Canaria and thus seems to have been spared some of the major slumped intervals and un- conformities present at Sites 954, 955, and 956. High-resolution seis- mic survey data indicate no structural or other major complications at this site (Shipboard Scientific Party, 1995). Site 953 penetrated 1158.70 m of sediment and recovered an apparently complete strati- graphic section from the Pleistocene to the middle/lower Miocene (Zone CN3) as indicated by the nannofossil biostratigraphy. A fair pa- leomagnetic record for the Pliocene and a good paleomagnetic record for the Pleistocene and upper and middle Miocene was recovered down to 873.7 meters below sea floor (mbsf; Schmincke, Weaver, Firth, et al., 1995). Additional stratigraphic control was provided by 40 Ar/ 39 Ar dates from volcanic material present in Site 953 (Bogaard, Chap. 19, this volume). All in all, Site 953 is an excellent candidate for calcareous nannofossil biostratigraphy and for comparison with other geographic areas. Preparation Techniques and Examination Standard nannofossil smear-slide techniques were used to prepare samples. Unprocessed sediment was distributed on 50 × 22 mm #1 cover slips using wooden toothpicks. Samples were dried and mount- ed on glass slides using Norland Optical Adhesive 61 mounting me- dium. Samples were examined at 900× and 1500× magnification, using a Nikon Optiphot2-pol microscope equipped with polarizing and phase-contrast optics. For each sample, a minimum of 350 individu- als were counted at 1500× magnification. This ensures that species as rare as 1% will be counted with a 95% confidence level (Dennison and Hay, 1967). Fluctuations in nannofossil populations are revealed with this type of counting method. After counting, additional fields of view were scanned at both 1500× and 900× to ensure that rare, stratigraphically important species had been encountered. Abundance and Preservation A qualitative estimate of the abundance of nannofossils relative to other particles on the slide was made for each sample. The categories used were very high (VH), high (H), moderate (M), low (L), very low (VL), and barren (B). A visual estimate of the preservational state of the nannofossils was also made for each sample. The categories used were good (G), moderate (M), and poor (P). See full definitions in Schmincke, Weaver, Firth, et al. (1995). Nannoplankton Zonation The nannoplankton biostratigraphy of Site 953 is tied to the well- defined zonations of Bukry (1973), Okada and Bukry (1980), and Martini (1971). Also included in this biostratigraphic summary of Site 953 are more recently defined datum events occurring within the Okada and Bukry (1973) and the Martini (1971) zonations. Many of these events have been summarized in Young et al. (1994). Time Scale The revised integrated magnetobiochronologic time scale of Berggren et al. (1995) was used for this paper. BIOSTRATIGRAPHY OF SITE 953 Pleistocene The CN zones of Bukry (1973) and Okada and Bukry (1980), as well as the events outlined by Gartner (1977) and Raffi et al. (1993) 1 Weaver, P.P.E., Schmincke, H.-U., Firth, J.V., and Duffield, W. (Eds.), 1998. Proc. ODP, Sci. Results, 157: College Station, TX (Ocean Drilling Program). 2 6111 Yarwell, Houston, TX 77096, U.S.A. (Present address: Exxon Exploration Company, P.O. Box 4778, Houston, TX 77210-4778) jsblevy@hal-pc.org 3 Challenger Division for Seafloor Processes, Southampton Oceanography Centre, Southampton, Hampshire SO14 3ZH, United Kingdom (Present address: Department of Geology and Geophysics, University of Western Australia, Nedlands WA 6907, Austra- lia). Site 950 Site 951 Site 953 22.8. 0:00 21.8. 0:00 5.8. 0:00 Site 956 10° 15° 20° 25° 30°W 30° 25° 5° Madeira Canary Islands Madeira Abyssal Plain Site 952 Africa Site 955 Site 954 35° N Figure 1. Location of Site 953 off Northwest Africa.