U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY PLANKTIC FORAMINIFER CENSUS DATA FROM NORTHWIND RIDGE CORES PI-88-AR P3, PI-88-AR P7, AND PI-88-AR P9, ARCTIC OCEAN Open-File Report 93-218 By Kevin M. Foley and Richard Z. Poore This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards (or with the North American Stratigraphic Code). Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Kevin M. Foley Mail Stop 906, National Center U.S. Geological Survey Reston, VA 22092 Tel: (703) 648-5285 FAX: (703) 648-5420 email: kfoley@usgs.gov Richard Z. Poore Mail Stop 906, National Center U.S. Geological Survey Reston, VA 22092 FAX: (703) 648-6647 email: rpoore@usgs.gov INTRODUCTION The U.S. Geological Survey recovered 9 piston cores from the Northwind Ridge in the Canada Basin of the Arctic Ocean from a cruise of the USCGC Polar Star during 1988. Locations of these core sites are given in table 1 and shown in figures 1 and 2. Preliminary analysis of the cores suggests sediments deposited on Northwind Ridge preserve a detailed record of glacial and interglacial cycles for the last few hundred-thousand to one million years. This report includes quantitative data on foraminifers and selected sediment size-fraction data in 98 samples from Northwind Ridge core PI-88AR P3, 51 samples from core PI-88-AR P7 and 117 samples from core PI-88-AR P9. These foraminifer data will be the basis for future interpretive studies. METHODS The samples were washed in distilled water, wet sieved to three size fractions; >63um, 63um - 2mm and >2mm. The material from each size fraction was dried at 50 degrees C and weighed. The 63um - 2mm and the >2mm fractions were combined after weighing. The >63um fraction was dry-sieved at 150um. The >150um size fraction of samples with abundant planktic foraminifers was split with a Carpco microsplitter to obtain representative aliquots of 300 - 350 planktic foraminifers. Foraminifers were sorted, identified and glued to standard micropaleontological slides and data were used to calculate abundances. All foraminifers >150um were removed and counted from samples which contained less than 350 planktic foraminifers. These data were used for planktic census and abundance estimates. Table 1. Latitude, longitude, and water depth of Northwind Ridge cores 3, 5, 7, and 9. Core Latitude Longitude Depth ---------------------------------------------- PI-88-AR P3 74.593 N 157.660 W 1909m PI-88-AR P5 74.622 N 157.884 W 1089m (see USGS OFR 91-346) PI-88-AR P7 74.629 N 157.386 W 3515m PI-88-AR P9 75.023 N 158.237 W 945m Figure 1 Map of Northwind Ridge showing the location of cores PI-88-AR P3, PI-88-AR P7, and PI-88-AR P9. (adapted from Phillips et al., 1992) Figure 2 Map of central Arctic Ocean showing location of figure 1. (adapted from Gilbert and Clark, 1983) COUNTING CATEGORIES Taxa included in the counting categories are summarized below. In general, our taxonomic concepts follow Parker (1962, 1967). dpach Neogloboquadrina pachyderma (Ehrenberg) right coiling. This category is restricted to specimens with 4 chambers in the ultimate whorl. Right-coiling specimens that have more than 4 chambers in the ultimate whorl are tabulated as "dupac". dupac This category is used for specimens of right-coiling Neogloboquadrina with more than 4 chambers in the ultimate whorl. spach Neogloboquadrina pachyderma (Ehrenberg) left-coiling. other unidentified planktic specimens and specimens resembling Turborotalita quinqueloba. total plank Total number of planktic foraminifers in the counting split or stripped from sample. total benth Total number of benthic foraminifers in the counting split or stripped from sample. ACKNOWLEDGEMENTS We thank Larry Phillips for providing the sedimentological data and processed residues from core 3, core 7 and core 9. We also thank Jennifer Pugin, Gail Slevin, Mary Gallagher and Dede Pitts for technical assistance. REFERENCES Gilbert, M. W. and Clark, D. L., 1983. Central Arctic Ocean paleoceanographic interpretations based on Late Cenozoic calcareous dinoflagellates. Marine Micropaleontology. v.7, p. 385-401. Parker, F.L., 1962, Planktonic foraminiferal species in Pacific sediments, Micropaleontology, v.8, p. 219-254. Parker, F.L., 1967, Late Tertiary biostratigraphy (Planktonic Foraminifera) of tropical Indo-Pacific deep-sea cores: Bulletins of American Paleontology, v. 52, p. 115-208. Phillips, R.L.,Grantz, A., Mullen, M.W., Rieck, H.J., McLaughlin, M. W. and Selkirk, T.L., 1992, Summary of the lithostratigraphy and stratigraphic correlations in piston cores from Northwind Ridge, Arctic Ocean, from USCGC Polar Star, 1988. U.S. Geological Survey Open-File Report 92-426, p. 3. APPENDIX Explanation of column headings in the files Core/raw/nwr3.txt, Core/raw/nwr7.txt, and Core/raw/nwr9.txt: sample Sample identifier. depth1 Depth in cm of the top of the sampled interval. depth2 Depth in cm of the bottom of the sampled interval. wt<62um Weight in grams of that part of the sample passing through the 62um sieve. wt%<62um Percentage of the total sample weight represented by the material passing through the 62um sieve. wt62um-2mm Weight in grams of that part of the sample passing through the 2mm sieve but retained on the 62um sieve. wt%62um-2mm Percentage of the total sample weight represented by the material passing through the 2mm sieve but retained on the 62um sieve. wt>2mm Weight in grams of that part of the sample retained on the 2mm sieve. wt%>2mm Percentage of the total sample weight represented by the material retained on the 2mm sieve. total wt Total weight of the sample. 1/split Proportion of the sample from which specimens were counted; a value of 1 indicates all of the sample was used to derive the counts, a value of 2 indicates half of the sample was used, and so on. spach Neogloboquadrina pachyderma (Ehrenberg) left coiling. dpach Neogloboquadrina pachyderma (Ehrenberg) right- coiling. This category is restricted to specimens with 4 chambers in the ultimate whorl. Right- coiling specimens that have more than 4 chambers in the ultimate whorl are tabulated as "dupac". dupac This category is used for specimens of right- coiling Neogloboquadrina with more than 4 chambers in the ultimate whorl. other Deformed planktic specimens and specimens resembling Turborotalita quinqueloba. total plank Total number of planktic foraminifers in the counting split. total benth Total number of benthic foraminifers in the counting split. plank/gram>150um The total number of planktic foraminifers >150um in the sample divided by the weight of the sample in grams. benth/gram>150um The total number of benthic foraminifers >150um in the sample divided by the weight of the sample in grams. (end)