In the samples referred to in these preservational units, 75%-100% of the specimens are classified as porous noncompressed. Both small and large specimens are present, although large tubular forms commonly dominate. The porous wall texture indicates that no significant diagenetic cementation of the agglutinated material has taken place. The tests retain their original shape with no, or only very weak, compressional deformation. In most species the color is white or yellowish, but some are reddish or light brown.
The generally well-preserved nature of the assemblages suggests that they have not been significantly affected by post-mortem transport and resedimentation processes. In accordance with this, the taxonomic composition of the faunas indicates bathyal to abyssal conditions and is consistent with a late Pliocene age.
Tubular taxa are abundant in the Cyclammina pusilla assemblage, common in the Recurvoides turbinatus assemblage, and are present in low numbers in the Ammodiscus tenuis assemblage. The group is generally regarded to be characteristic of deep-water, mainly bathyal environments (Gradstein and Berggren, 1981; Miller et al., 1982; Jones, 1988; Gradstein and Bäckström, 1996). In the C. pusilla assemblage, the tubular group is represented by Rhizammina algaeformis, Rhabdammina discreta, and Rhizammina sp., whereas in the R. turbinatus assemblage, R. algaeformis is dominant. As shown by Schröder (1986), R. algaeformis is abundant in modern bathyal to abyssal faunas of the northwestern Atlantic Ocean (Nova Scotia Rise, Bermuda Rise, and Nares Abyssal Plain). On the Nova Scotia Rise, R. discreta occurs mainly in the depth interval 2750-3550 m.
According to information published by Schröder (1986), Charnock and Jones (1990), and Jones (1994), the following species of the porous noncompressed assemblages are generally confined to bathyal and greater depths in the present-day North Atlantic Ocean: Ammodiscus tenuis, Cyclammina pusilla, Thurammina papillata, Recurvoides turbinatus, Haplophragmoides bradyi, Ammomarginulina foliacea, Karreriella apicularis, Cribrostomoides subglobosus, Technitella legumen, Reophax guttifer, Ammonarginulina recurva, Cyclammina trullissata, and Reophax bilocularis.
In the samples belonging to these faunal units, 75%-100% of the foraminifers show the silicified compressed type of preservation. The specimens are small in size, markedly deformed by compression, and are strongly silicified by diagenetic processes. Their color is usually gray or brownish. The poor preservation and small size of the tests made taxonomic determinations difficult, which explains the extensive use of open nomenclature.
The preservational features of this fauna suggest reworking from pre-existing strata, with subsequent transport and resedimentation in the upper Pliocene lower slope environment. The small and relatively uniform size of the tests (usually 130-200 µm) suggests sorting by a hydrodynamic process.
The redeposited faunal component is dominated by Textulariina genus indet. and T. cf. nana. In addition to the redeposited forms, many samples contain scattered, well-preserved tests of more or less in situ origin belonging to species such as R. algaeformis, C. pusilla, and Repmanina charoides.
The samples grouped in the mixed units contain 25%-75% porous noncompressed specimens, whereas the rest is silicified compressed. These fauna are developed in four thin intervals between silicified compressed units (Fig. 7). The increased frequency of the in situ faunal component in the mixed assemblages suggests periods with reduced influx of material from extrabasinal sources, or increased benthic productivity within the depositional area.