Samples 180-1114A-1R-CC to 2R-1, 30-32 cm, contain abundant, well-preserved nannofossils. Samples 180-1114A-2R-1, 35-37 cm, to 7R-CC contain mostly few to common nannofossils with some almost barren intervals. Preservation ranges from poor to good (mostly moderate). From Core 180-1114A-8R to 32R (in which the last sediment was recovered) nannofossils are mostly rare with some barren or almost barren intervals. Preservation is poor to moderate (mostly poor).
Sediment contained in Sample 180-1114A-1R-CC is in Zone NN20 through Subzone NN21A, based on the presence of Gephyrocapsa omega and Emiliania huxleyi (very rare) and the absence of Pseudoemiliania lacunosa (Fig. F38; Table T7). A lithified pebble under the sediment in the bottom of Sample 180-1114A-1R-CC contains Helicosphaera sellii and is, therefore, assigned to Subzones NN19C-D or older. Sample 180-1114A-2R-1, 30-32 cm (light green mud) contains the same assemblage and is also Subzones NN19C-D or older. This sample rests unconformably on Sample 180-1114A-2R-1, 35-37 cm (grayish black mudstone), which is Subzone NN19B or older based on the first downhole occurrence of C. macintyrei. The abundance and preservation of nannofossils decline markedly below this level, and specific zonal markers are absent. We found only rare, poorly preserved discoasters (including Discoaster cf. D. brouweri) in Samples 180-1114A-12R-CC and 31R-1, 22-24 cm, indicating Subzone NN18 or older.
In the low-oxygen benthic environments of this hole, planktonic foraminifers are thought to have been partly dissolved, and the residues represent incomplete assemblages. Because some of the key species are fairly resistant to dissolution, a stratigraphy could be determined for this hole.
Planktonic foraminifers were abundant and their preservation was good in Samples 180-1114A-1R-CC and 2R-1, 30-32 cm; common to abundant and with moderate to poor preservation in Samples 180-1114A-3R-2, 47-49 cm, 8R-CC, 19R-CC, 25R-CC, 29R-CC, 12-14 cm, and 31R-1, 22-24 cm; and few to rare with moderate to poor preservation in 2R-CC through 6R-CC, 9R-CC through 11R-CC, 13R-CC, 16R-CC, 18R-CC, 20R-CC, 22R-CC, 23R-CC, 26R-CC, and 30R-CC. The core-catcher samples of the following cores were barren of planktonic foraminifers: Cores 180-1114A-4R, 7R, 12R, 14R, 15R, 21R, 24R, 27R, and 29R through 32R. No core-catcher samples were obtained for Cores 180-1114A-17R and 28R.
Planktonic foraminiferal zonation for Site 1114 is summarized in Figure F38, and Table T8 shows the stratigraphic distribution of species.
Sample 180-1114A-1R-CC is placed in late Pleistocene-Holocene planktonic Zone N23, based on the presence of Bolliella calida and pink Globigerinoides ruber, whose presence indicates an age no younger than 120 ka.
Samples 180-1114A-2R-1, 30-32 cm, through 13R-CC, are placed in the lower part of Zone N22, based on the presence of Globorotalia truncatulinoides, G. tosaensis, and Globigerinoides fistulosus. Sample 180-1114A-2R-1, 30-32 cm, contains the last-appearance datum (LAD) of G. fistulosus (1.6 Ma), and Sample 180-1114A-13R-CC, 9-12 cm, contains the first-appearance datum (FAD) of G. truncatulinoides (2.58 Ma), which marks the base of the zone.
Sections between Samples 180-1114A-14R-CC and 31R-1, 22-24 cm, are assigned to Zone N21, based on the presence of G. tosaensis and G. crassaformis and the absence of G. truncatulinoides.
Dentoglobigerina altispira (LAD 3.09 Ma) and Sphaeroidinella dehiscens s.s. (FAD = 3.25 Ma) are present in Sample 180-1114A-31R-1, 22-24 cm. This is the lowest fossiliferous sample overlying the metamorphic basement and is no older than middle Pliocene (~3.25 Ma), based on the presence of S. dehiscens s.s.
The foraminiferal assemblage at the sediment/water interface was not retained in this hole, which was drilled in a water depth of 407 m. A middle bathyal water depth (500-2000 m) is indicated by the benthic foraminifers of Pleistocene age in Cores 180-1114A-1R and 2R, although the species represented in the samples varied as specified below.
Sample 180-1114A-1R-CC (Zone N23) contained Globocassidulina subglobosa, Ceratobulimina pacifica, Cibicidoides rugosus, Eggerella bradyi, Gyroidina altiformis, Laticarinina pauperata, Martinottiella sp., Oridorsalis umbonatus, Parrelloides bradyi, Sphaeroidina bulloides, and Uvigerina asperula. Sample 180-1114A-2R-2, 30-32 cm (Zone N21), contained Bolivinita quadrilatera, Bulimina aculeata, B. striata, Cassidulina neocarinata, Uvigerina bradyana, and Valvulineria sp.
From Sample 180-1114A-2R-CC through 25R-CC (Zone N21), the benthic assemblages are dominated by Globobulimina spp. These foraminifers are known to inhabit sediments with relatively high organic content deposited under low-oxygen conditions. In some cases, as in Samples 180-1114A-3R-2, 47-49 cm, 8R-CC, and 25R-CC, the globobuliminids are accompanied by Ceratobulimina pacifica and other typical middle bathyal species, whereas, in other instances only a species of Valvulineria, a crushed multilocular agglutinated species, and Bathysiphon accompany the globobuliminids. The environment of deposition is interpreted as one of fluctuating low oxygen possibly associated with the boundaries of the oceanographic oxygen minimum at upper bathyal to upper middle bathyal depths, or of a basinal situation with restricted circulation.
Detrital sands of volcanogenic origin in Samples 180-1114A-18R-CC, 26R-CC, and 27R-CC contain only rare specimens of the inner neritic (<50 m) transported species Asterorotalia gaimardii and Elphidium craticulatum.
Sample 180-1114A-31R-1, 22-24 cm (Zone N21), the lowest fossiliferous sample overlying the metamorphic basement, contains diverse benthic foraminifers, among them Gyroidina sp., Martinottiella sp., and Uvigerina hispida, which are indicative of middle bathyal depths. Rotalia sp. may have been introduced into this sample through downslope transport.
We estimated an average sedimentation rate based on nannofossil and foraminifer datum events at Site 1114 (Fig. F39). The average sedimentation rate for the horizon from 6.95 to 266.62 mbsf is calculated to be at least 176 m/m.y.