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19. Coccolith Age Determinations Leg 5, Deep Sea Drilling Project

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19. Coccolith Age Determinations Leg 5, Deep Sea Drilling Project 19. COCCOLITH AGE DETERMINATIONS LEG 5, DEEP SEA DRILLING PROJECT Stefan Gartner, Jr. Rosenstiel School of Marine and Atmospheric Sciences, University of Miami, Miami, Florida By utilizing calcareous nannofossils, the data presented Sample 5-32-3-5, 5-6 cm: here represent age determinations of sediment cores Cyclococcolithus leptoporus, Coccolithus pelagicus, recovered in the Pacific Ocean during Leg 5 of the Deep Discoaster sp., Helicopontosphaera kamptneri, Pseudo- Sea Drilling Project. All determinations were made emiliania lacunosa, cf. Discoaster brouweri, Discoaster with a light microscope on smear slides prepared from surculus. unprocessed samples. Age: Late Pliocene. The accuracy of the age determination differs from one Sample 5-32-4-1, 19-20 cm: sample to the next, owing largely to the differences in Barren of calcareous nannofossils. assemblages. Assemblages containing age diagnostic species may be assigned to a zone. However, some Sample 5-32-4-2, 2-3 cm: samples contain few or no age diagnostic species, in Coccolithus sp., Cyclococcolithus leptoporus, Cocco- which case relatively broader age assignments are made, lithus pelagicus, Reticulofenestra pseudoumbilica. commonly equivalent to the interval represented by a Age: Probably early Pliocene. stage. Stage terms are avoided (except in the late Miocene), however, and it seems more reasonable to Sample 5-32-4-3, 2-3 cm: use such terms as early Miocene or middle Eocene, Reticulofenestra pseudoumbilica, Cyclococcolithus lep- than it is to refer to one or another stage term used for toporus, Coccolithus pelagicus, Discoaster brouweri, the respective intervals. Sphenolithus abies. Age: Probably early Pliocene. In no case is an exhaustive species list given for a sam- ple. For the most part, only those species are recorded Sample 5^32-4-4, 3-4 cm: which actually aid in the age determination of a sam- Barren of calcareous nannofossils. ple. It should be stressed that these results are prelim- inary and, therefore, subject to minor revisions if more Sample 5-32-4-5, 10-12 cm: detailed studies are made. Barren of calcareous nannofossils. Hole 32 Sample 5-32-5-6,9-10 cm: Barren of calcareous nannofossils. Sample 5-32-3-1, 6-7 cm: Discoaster surculus, Discoaster brouweri, Cyclococco- Sample 5-32-6-6, 2-3 cm: lithus leptoporus, Coccolithus pelagicus, cf. Reticulo- aff. Discoaster surculus, Reticulofenestra pseudoum- fenestra pseudoumbilica, Coccolithus pelagicus, Dis- bilica, Discoaster variabilis, Coccolithus pelagicus, cf. coaster pentaradiatus, Discoaster asymmetricus. Cyclococcolithus leptoporus. Age: Middle Pliocene. Age: Late Miocene to early Pliocene, probably early Pliocene. Sample 5-32-3-2,4-5 cm: Discoaster brouweri, cf. Discoaster pentaradiatus, Dis- Sample 5-32-7-1, 5-6 cm: coaster surculus, cf. Reticulofenestra pseudoumbilica. Reticulofenestra pseudoumbilica, Cyclococcolithus lep- Age: Probably as above. toporus. Age: As above. Sample 5-32-3-4, 7 cm: Coccolithus pelagicus, Cyclococcolithus leptoporus, Sample 5-32-8-1, 5-6 cm: Pseudoemiliania lacunosa, cf. Discoaster brouweri, Dis- Barren of calcareous nannofossils. coaster surculus, sample probably mixed middle Plio- cene and early Pleistocene. Sample 5-32-8-3, 5-6 cm: Age: Middle Pliocene to early Pleistocene. Barren of calcareous nannofossils. 495 Sample 5-32-8-6,4-5 cm: Sample 5-33-3-4, 3-4 cm: Barren of calcareous nannofossils. Pseudoemiliania lacunosa, Coccolithus pelagicus, cf. Cyclococcolithus leptoporus. Sample 5-32-9-3, 6-7 cm: Age: Probably early Pleistocene. Barren of calcareous nannofossils. Sample 5-33-3-5, 4-5 cm: Hole 33 Discoaster sp., cf. Coccolithus pelagicus, Cyclococcoli- Sample 5-33-1-1, 11-12 cm: thus leptoporus. Barren of calcareous nannofossils. Age: Neogene. Sample 5-33-1-2,8-9 cm: Sample 5-33-3-6, 10-11 cm: Coccolithus pelagicus, Gephyrocapsa aperta. Coccolithus pelagicus, Cyclococcolithus leptoporus, Age: About middle Pleistocene. Pseudoemiliania lacunosa. Age: Probably early Pleistocene. Sample 5-33-1-3, 12-13 cm: Coccolithus pelagicus, Gephyrocapsa aperta. Sample 5-33-4-1, 13-14 cm: Age: Probably middle Pleistocene. Barren of calcareous nannofossils. Sample 5-33-1-4, 10-11 cm: Sample 5-33-4-3, 3-4 cm: Coccolithus pelagicus, Gephyrocapsa sp. Cyclococcolithus leptoporus, cf. Pseudoemiliania la- Age: Probably middle Pleistocene. cunosa, cf. Discoaster brouweri. Age: Probably late Pliocene. Sample 5-33-1-6,12-13 cm: Barren of calcareous nannofossils. Sample 5-33-4-5, 3-4 cm: Cerαtolithus rugosus, Coccolithus pelagicus, Cyclococ- Sample 5-33-2-1, 12-13 cm: colithus leptoporus, Pseudoemiliania lacunosa, Dis- Cyclococcolithus leptoporus, Helicopontosphaera coaster surculus. kamptneri, Coccolithus pelagicus. Age: Early late Pliocene, Discoaster surculus Zone. Age: Probably Pleistocene. Sample 5-33-5-3, 10-11 cm: Sample 5-33-2-3, 15-16 cm: Cyclococcolithus leptoporus, Discoaster variabilis, Coc- Coccolithus pelagicus, Pseudoemiliania lacunosa, Gephy- colithus pelagicus, Discoaster surculus, Discoaster brou- rocapsa sp., Cyclococcolithus leptoporus. weri, Ceratolithus tricorniculatus, Reticulofenestra Age: Middle Pleistocene. pseudoumbilica. Age: Probably early Pliocene. Sample 5-33-2-4,4-5 cm: Barren of calcareous nannofossils. Sample 5-33-5-6, 3-4 cm: Sample 5-33-2-5,4-5 cm: Coccolithus pelagicus, Reticulofenestra pseudoumbilica, Cyclococcolithus leptoporus, Coccolithus pelagicus, Discoaster variabilis, Discoaster stellulus, Discoaster Gephyrocapsa sp. surculus, Ceratolithus tricorniculatus. Age: Middle Pleistocene, if indigenous. Age: Late Miocene (Messinian) to early Pliocene. Sample 5-33-2-6, 5-6 cm: Sample 5-33-6-6, 15-16 cm: Barren of calcareous nannofossils. Reticulofenestra pseudoumbilica, Discoaster variabilis, Discoaster stellulus, Discoaster surculus. Sample 5-33-3-1, 6-8 cm: Age: Probably late Miocene. Coccolithus pelagicus, Cyclococcolithus leptoporus, Pseudoemiliania lacunosa, "Discolithus"phaseolus. Sample 5-33-8-1,9-10 cm: Age: Early Pleistocene. Discoaster variabilis, Sphenolithus abies, Reticulofenes- tra pseudoumbilica, aff. Discoaster bollii. Sample 5-33-3-2,4-5 cm: Age: Late Miocene, probably Tortonian. Coccolithus pelagicus, Cyclococcolithus leptoporus, Pseudoemiliania lacunosa. Sample 5-33-8-2,10-11 cm: Age: Probably early Pleistocene. Reticulofenestra pseudoumbilica, Discoaster variabilis, Sphenolithus abies, Discoaster brouweri, Cyclococco- Sample 5-33-3-3,3-4 cm: lithus leptoporus. Barren of calcareous nannofossils. Age: Probably as above. 496 Sample 5-33-8-3, 2-3 cm: Hole 34 Discoaster variabilis, Reticulofenestra pseudoumbilica, Sample 5-34-1-1,4-5 cm: aff. Triquetrorhabdulus rugosus. Barren of calcareous nannofossils. Age: Late Miocene. Sample 5-34-1-2, 10-11 cm: Sample 5-33-8-4, 5-6 cm: Barren of calcareous nannofossils. Reticulofenestra pseudoumbilica, Discoaster variabilis, Discoaster aff. D. variabilis, Cyclococcolithus lepto- Sample 5-34-1-3,4-5 cm: porus. Cyclococcolithus leptoporus, Coccolithus pelagicus, cf. Age: Probably middle Miocene. Pseudoemiliania lacunosa, no Discoasters, no Gephy- rocapsa. Sample 5-33-8-5, 5-6 cm: Age: Probably early to middle Pleistocene. Reticulofenestra pseudoumbilica, cf. Discoaster bollii, cf. Discoaster variabilis, Discoaster variabilis. Sample 5-34-1-4, 15-16 cm: Age: Late Miocene, probably Tortonian. Barren of calcareous nannofossils. Sample 5-34-1-5, 15-16 cm: Sample 5-33-8-6, 4-5 cm: Barren of calcareous nannofossils. Discoaster variabilis, Reticulofenestra pseudoumbilica, cf. Discoaster exilis. Sample 5-34-1-6, 9-10 cm: Age: Probably as above. Coccolithus sp., Cyclococcolithus leptoporus, Pseudo- emiliania lacunosa. Sample 5-33-9-3,4-5 cm: Age: Probably early Pleistocene. Barren of calcareous nannofossils. Sample 5-34-2-1, 12-13 cm: Sample 5-33-9-6, 4-5 cm: Cyclococcolithus leptoporus. Barren of calcareous nannofossils. Age: Not determinable. Sample 5-33-10-2, 2-3 cm: Sample 5-34-2-2, 9-10 cm: Reticulofenestra pseudoumbilica, cf. Discoaster exilis, Barren of calcareous nannofossils. cf. Discoaster variabilis, Catinaster caliculus. Age: Late Miocene, Tortonian. Sample 5-34-2-3, 4-5 cm: Barren of calcareous nannofossils. Sample 5-33-10-5, 22-23 cm: Sample 5-34-2-4, 8-9 cm: Discoaster exilis, Reticulofenestra pseudoumbilica. Barren of calcareous nannofossils. Age: Probably as above. Sample 5-34-2-5, 11-12 cm: Sample 5-33-11-2, 5-6 cm: Cyclococcolithus leptoporus, aff. Pseudoemiliania la- Sphenolithus abies. cunosa. Age: Insufficient nannofossils for age determination. Age: Probably early Pleistocene. Sample 5-33-11-3, 12-13 cm: Sample 5-34-2-6,11-12 cm: Barren of calcareous nannofossils. Coccolithus pelagicus, Pseudoemiliania lacunosa, Heli- copontosphaera kamptneri, Cyclococcolithus leptopo- rus. Sample 5-33-12-3, 11-12 cm: Age: Probably early Pleistocene. Reticulofenestra pseudoumbilica, cf. Discoaster exilis. Age: Probably late middle Miocene to early late Sample 5-34-3-1,7-8 cm: Miocene. Cyclococcolithus leptoporus, cf. Discoaster brouweri, Discoaster surculus, Coccolithus pelagicus, Discoaster Sample 5-33-12-6, 4-5 cm: asymmetricus. Barren of calcareous nannofossils. Age: Middle to late Pliocene. Sample 5-33-15-1, 37-38 cm: Sample 5-34-3-2, 10-11 cm: Reticulofenestra pseudoumbilica, Coccolithus pelagi- Coccolithus pelagicus, Cyclococcolithus leptoporus, cus, aff. Coccolithus neogammation, Discoaster exilis. Discoaster asymmetricus. Age: Middle Miocene. Age: Probably as above. 497 Sample 5-34-3-3,7-8 cm: Sample 5-34-5-2, 19-20 cm: Cyclococcolithus leptoporus, Coccolithuspelagicus, Dis- Reticulofenestra pseudoumbilica,
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