Radiolarians provide the biostratigraphic framework for Site 1222. Planktonic foraminifers are completely dissolved in all samples investigated. Calcareous nannofossils of early Oligocene age are present in one short interval in Core 199-1222A-7H, and early Eocene calcareous nannofossils are present in chalk attached to a piece of chert in Section 199-1222A-12X-CC.
The biostratigraphic distribution of radiolarians suggests massive reworking and mixed Pliocene assemblages in the uppermost two and a half cores, between 0 and 21 mbsf (Fig. F5). The following two cores, between ~21 and 40 mbsf, contain upper and lower Miocene radiolarian assemblages. Two cores between ~40 and 60 mbsf contain upper and lower Oligocene radiolarian assemblages. Nannofossils are present between ~55 and 60 mbsf, supporting the radiolarian biostratigraphy. This upper part of the section at Site 1222 appears to contain several breaks in sedimentation. Unlike other Leg 199 sites, at Site 1222 a major hiatus is present between earliest Oligocene and middle Eocene time, having a duration on the order of ~5-6 m.y.
Calcareous nannofossils are present from Sample 199-1222A-7H-2, 60 cm, through 7H-CC. Sample 199-1222A-7H-2, 60 cm, contains a severely reduced, dissolution-biased assemblage with remains of Dictyoccites hesslandii, Sphenolithus moriformis, and distal shield rims of Coccolithus pelagicus. Discoaster deflandrei, Discoaster nodifer, and Discoaster tanii are also present; most specimens show calcite overgrowth. The uppermost occurrence of Reticulofenestra umbilicus is observed between Samples 199-1222A-7H-4, 60 cm, and 7H-4, 84 cm. It follows that the transition from nannofossil-bearing sediment to the overlying barren sediment in Core 199-1222A-7H is present just above the CP16c/CP17 (NP22/NP23) zonal boundary.
Nannofossil assemblages are increasingly dissolved through Section 199-1222A-7H-5. Samples 199-1222A-7H-5, 5 cm, and 7H-5, 50 cm, can be referred to Subzone CP16c (NP22), whereas the nannofossils in Sample 199-1222A-7H-5, 100 cm, are too dissolved to say with any confidence whether this sample belongs to Subzone CP16c or CP16a+b (NP21). Sample 199-1222A-7H-5, 147 cm, only contains discoasters, but none of these are the exclusively Eocene forms that characterize Zone CP15 (NP20). Core 199-1222A-7H is barren of calcareous nannofossils below Sample 199-1222A-7H-5, 147 cm, although the core catcher sample contains isolated contaminated pieces of nannofossil ooze belonging to the overlying Oligocene Subzone CP16c (NP22).
Chalk attached to a piece of chert in Section 199-1222A-12X-CC contains nannofossils representing lowermost Subzone 9a (NP10) of the lower Eocene. The assemblage of this sample includes overgrown specimens of Tribrachiatus bramlettei, together with Chiasmolithus bidens, C. pelagicus, Discoaster mohleri, Discoaster multiradiatus, Discoaster nobilis, Ericsonia spp., Neochiastozygus junctus, Neocrepidolithus spp., Placozygus sigmoides, Prinsius bisulcus, Sphenolithus primus, and Toweius pertusus.
Planktonic foraminfers were not found in any core catcher samples from Site 1222.
Core catcher samples from Cores 199-1222A-1H through 12X are barren of benthic foraminifers. However, benthic foraminifers were found at one horizon in Hole 1222B. Sample 199-1222B-1H-CC contains a benthic foraminiferal assemblage characterized by Siphonodosaria abyssorum, Cibicidoides mundulus, Gyroidinoides soldanii, and Oridorsalis umbonatus. C. mundulus is a long-ranging species from late Oligocene to Pleistocene, and this species is abundant at bathyal and abyssal paleodepths (van Morkhoven et al., 1986). This assemblage shows moderate preservation.
The preservation and abundance of radiolarians at this site varied considerably both downhole and within individual cores (Table T2). Reworking of Eocene and Oligocene taxa plus a number of hiatuses within the sedimentary sequence made zonal designation difficult. Zonal boundaries for radiolarians at Site 1222 are listed in Table T3.
Although Cores 199-1222A-1H and 2H contain a few moderately well preserved forms, it was not possible to assign an age to the material. It is probably Quaternary but with an admixture of Eocene and Oligocene. Several samples were taken from within Core 199-1222A-3H on either side of the diatom mats noted by the sedimentologists (see "Subunit IA" in "Lithostratigraphy"). Along with reworked Eocene species, Sample 199-1222A-3H-2, 14-16 cm, contains a mixed assemblage of species indicative of the Pliocene. The presence of Pterocanium prismatium, Anthocyrtidium angulare, and Lamprocyrtis nigriniae suggest Zone RN12, but Stichocorys peregrina is also present, which suggests Zone RN11 or older. Sample 199-1222A-3H-2, 14-16 cm, and subsequent Core 199-1222A-3H samples all contain an abundance of fragments of the diatom Ethomodiscus rex. An age assignment of Zone RN10 is clearer for Samples 199-1222A-3H-2, 110-112 cm; 3H-3, 42-44 cm; and 3H-4, 18-20 cm, with a greater abundance of species such as S. peregrina, Spongaster tetras tetras, and P. prismatium amidst the ever-present reworked Eocene species. We have assigned an age of Zone RN9 to Sample 199-1222A-3H-4, 88-90 cm, because of the presence of Didymocyrtis penultima, the last presence of which marks the RP9/RP10 zonal boundary. Samples from the above-described interval represent the only Pliocene material found during Leg 199.
The next downhole sample for which it is possible to determine an age is Sample 199-1222A-5H-6, 45-47 cm. It belongs to uppermost Oligocene Zone RP22, based on the presence of Lychnocanoma elongata and the absence of Cyrtocapsella tetraperam, but also contains a large amount of reworked Eocene material. Sample 199-1222A-5-CC belongs to Zone RP21. The sample also contains a large number of orosphaerids and, once again, a reworked Eocene fauna. Core 199-1222A-6H and the upper three sections of Core 199-1222A-7H contain only trace amounts of non-age diagnostic radiolarians. Abundance and preservation improves slightly in Samples 199-1222A-7H-4, 45-47 cm, and 7H-5, 45-47 cm. Based on the presence of Dorcadospyris spinosa, Dorcadospyris quadripes, and Theocyrtis tuberosa, we assigned an age of Zone RP20 to these samples, despite the absence of Lithocyclia angusta. In Sample 199-1222A-7H-6, 45-47 cm, it becomes more difficult to distinguish reworked specimens from in-place fauna. The rare and poorly preserved specimens suggest an age of Zone RP18 or younger. Data from the nannofossil assemblage in Sample 199-1222A-7H-5, 100 cm, indicate that an age younger than Zone RP18 is appropriate. There is an ~6-m.y. hiatus before Sample 199-1222A-7H-7, 66-68 cm, which clearly belongs to Zone RP15 as do subsequent downhole samples (199-1222A-7H-CC; 8H-2, 45-46 cm; and 8H-3, 45-47 cm). The rest of the recovered material in Hole 1222A is barren of radiolarians or contains only trace amounts of non-age diagnostic forms.
Material recovered from Hole 1222B shows a similar pattern of disjointed ages, preservation, and radiolarian abundance. Sample 199-1222B-1H-CC contains an abundance of reworked Eocene fauna along with rare late Neogene forms such as Theocorythium vetulum, Didymocyrtis tetrathalamus, and Lamprocyrtis heteroporos. Samples from 199-1222B-2H-4, 36-38 cm; 2H-5, 43-45 cm; and 2H-CC probably belong to Zone RP11. In Samples 199-1222B-5H-CC, 6H-CC, and 7H-3, 45-47 cm, the fauna indicates an age of Zone RP21. Sample 199-1222B-5H-CC is particularly rich in orosphaerids. The remaining downhole samples (199-1222B-7H-5, 100-102 cm; 7H-6, 44-46 cm; and 7H-CC) all could be placed in Zone RP20.