Cystammina sveni Gradstein & Kaminski, 1997

Fig. 089. Paratype of Cystammina sveni Gradstein & Kaminski, 1997. ODP Hole 643A, Vøring Slope.
Sample 643A-56X-3, 56-61 cm. Redrawn after Kaminski et al. (1990)

ORIGINAL DESIGNATION: Cystammina sveni Gradstein & Kaminski, 1997

TYPE REFERENCE: Gradstein, F.M., & Kaminski, M.A. 1997. New species of Paleogene Deep-Water Agglutinated Foraminifera from the North Sea and Norwegian Sea. Annales Societatis Geologorum Poloniae, 67, 217-229.

TYPE SPECIMEN: Holotype is housed in the Micropaleontology Collection of the British Museum of Natural History, London. The holotype is registered in slide PF 62946. Additional paratypes are registered as PF 67229-67230.

TYPE LEVEL: The type level is the interval of Paleocene green clays at 2560 m in well Elf Aquitaine 6406/8-1.

TYPE LOCALITY: Offshore mid Norway. Additional syntypic material is from the Central North Sea.

DIAGNOSTIC FEATURES: Test globose, streptospirally coiled with 3 or 3.5 chambers per whorl. The chambers are elongate to spherical, rapidly increase in size and strongly embrace in a tight, involute manner; there are 2 or 2-3 chambers visible on one side and 3 or 3-4 on the other. The wall is smooth, very finely agglutinated, and often well silicified; the aperture is an areal slit with a distinct lip.

SIZE: Specimens range between 0.10 and 0.36 mm in diameter. The holotype is 0.26 mm in maximum diameter.

Praecystammina aff. globigerinaeformis Krashenninikov. Gradstein & Berggren, 1981, p. 258-259, pl. 9, figs. 11-15 [Paleocene, North Sea].
Cystammina globigerinaeformis (Krashenninikov). Miller et al., 1982, p. 21, pl. 2, figs. 13, 17, 21 [Eocene, Labrador Sea].
Ammosphaeroidina sp. Kaminski et al. 1989. pl. 5, fig. 4 [Eocene, Labrador Sea].
Cystammina pauciloculata (Brady). Charnock & Jones, 1990, pl. 16, fig. 4a-c [Paleocene, North Sea].
Praecystammina sp. Kaminski et al., 1990, p. 370, pl. 7, figs. 4a,b, 5 [Eocene, Norwegian Sea].

OBSERVED OCCURRENCES: Cystammina sveni was described from Paleocene green clays at 2560 m in the Elf Aquitaine 6406/8-1 well. Additional syntypic material is from Paleocene green clays between 5450 and 5850 ft in the Conoco (UK) 211/19-1 well, Viking Graben. Additional specimens were found from the Paleocene in wells Statoil 7120/7-3 at 1320 - 1380m, 7117/9-2 at 1380m and 7119/9-1 at 1450m, western Barents Sea (Nagy et al., 1997). Offshore mid Norway the species was found in the lower Eocene of ODP Hole 643A, Cores 643A-54X to -56X, and in Hydro 6407/7-1 at 1730m and Saga 6407/2-3 at 1820m. In the Viking and Central grabens it occurs in wells Hydro 34/8-1 at 1898m, Saga 34/4-5 at 1920m, Mobil (UK) 9/13-1 at 6600m, Mobil (UK) 9/13-3A at 5810m, Mobil (UK) 9/13-5 at 7260m, Total (UK) 9/10B-1 at 2345m, Total (UK) 3/25-1 at 2430m, Danish North Sea A-2 at 5940 ft, Danish North Sea E-1 at 6680 ft., BP (UK) 15/20-1 at 1770m, BP 15/20-2 at 1905m, Shell (UK) 22/6-1 at 7660 ft., Phillips (UK) 22/14-1x at 7650 ft., Shell (UK) 29/3-1 at 8790 ft., Shell (UK) 30/19-1 at 8890 ft., and Saga 2/2-4 at 2620m. In the North Sea and offshore Norway, the species occurs in Zones NSR2, NSR4, and NSR5A, Late Paleocene to early part of Middle Eocene. Gillmore (1991) illustrated a specimen as "Praecystammina globigerinaeformis Krashenninikov" from the Early-Middle Eocene of well 21/30-1 (6210 ft.) in the Central North Sea. Its range extends downward into Middle Campanian strata (lower Tritaxia dubia Zone, Gradstein et al., 1999), offshore mid Norway.
In Trinidad rare specimens occur in Zone P4, Late Paleocene of the Lizard Springs Formation. It is also observed in flysch-type agglutinated assemblages of Maastrichtian to Early Eocene age in the Atlantic region, Labrador Shelf, Alpine-Carpathian region, northern Spain, and northern Morocco; and in Late Paleocene to Middle Eocene abyssal assemblages of DSDP Site 112 and of ODP Site 647 in the Labrador Sea.

KNOWN STRATIGRAPHIC RANGE: The species is typical for Paleocene middle bathyal or deeper marine sediments, with rare specimens in upper bathyal strata; it is rare in Campanian. It ranges into the Middle Eocene in middle bathyal or deeper continental margin strata, and abyssal sediments from DSDP/ODP sites.

BATHYMETRY: Bathyal to abyssal

REMARKS: Cystammina sveni most closely resembles the modern species Cystammina pauciloculata (Brady). The latter is less tightly coiled, with 4 to 5 chambers visible form the exterior and has more elongated chambers. Transitional morphotypes between the two taxa occur, and the two taxa may be phylogenetically related, with C. pauciloculata extending to the Recent. Cystammina sveni probably derived from the Late Cretaceous Praecystammina globigerinaeformis Krashenninikov.
Praecystammina globigerinaeformis Krashenninikov differs from C. sveni in having a less tightly coiled, more evolute test, chamber that increase in size more slowly, more (3-5) chambers visible per whorl, and an aperture that is round in juveniles, becoming oval to a slit like in more developed specimens.

ILLUSTRATIONS: Plate 89 - Cystammina sveni Gradstein & Kaminski, 1997
Fig. 1a-c. Paleocene, offshore Norway, Saga petroleum well 6406/8-1, 2560 m, Holotype, BM(NH) PF62946; Fig. 2a,b. Paratype. Mobil 35/11-1, 1330 m; Fig. 3. Paratype. Saga 6406/8-1, 2560 m; Fig. 4a,b. Paleocene, Viking Graben Conoco (UK) 211/19-1, 5630', SWC; Fig. 5. Conoco (UK) 211/19-1, 5630', SWC; Fig. 6. Paratype. Saga 6406/8-1, 2560 m. All specimens are from Paleocene green clays.