The Paleomagnetism of Sediments Acquired from the Goban Spur on Deep Sea Drilling Project Leg 80

Abstract

Paleomagnetic results from sediments acquired from the continental margin at DSDP Sites 548, 549, 550, and 551 are described. Where possible, the results were used to construct a polarity reversal stratigraphy for the sections sampled, thus enabling the biostratigraphic dating of the sediments to be refined. Several sections in this study were found to be suitable for magnetostratigraphic work, in particular the upper Paleocene to middle Eocene sediments from Site 549, which contained rich faunal assemblages. These sediments are underlain by a thick sequence of Cretaceous sediments that formed during the Long Cretaceous normal polarity interval. Sediments that formed during the later part of this magnetically quiet interval were also recovered at Site 550. Three short reverse polarity intervals were also recovered at this site; they lie directly over basement and are thought to represent a mixed-polarity interval of late Albian age. They may therefore provide important evidence concerning the age of the earliest sediments at this site.In addition, measurements of the magnetic susceptibility and intensity of remanent magnetism proved to be of interest. A significant decrease in the susceptibility and intensity values close to the early/middle Eocene boundary was noted at Sites 548 and 549. This decrease may be correlated with the results from Holes 400A and 401, which were drilled on DSDP Leg 48 in the northeast Bay of Biscay. The decrease may represent an abrupt reduction in the supply of terrigenous material at the end of the early Eocene, reflecting, perhaps, a change in sediment transport processes at that time.

The silicoflagellate zonation around the paleocene‐eocene boundary in Northern Europe

“…The lowermost ash layer investigated by Sharma was -13, and thus his data are not useful for a correlation of the top of Polarity Chron 25 in the upper part of NP9 at Site 550, where it occurs considerably below ashlayer-17. Sharma's findings are in contra- GFF116 (1994) Meeting proceedings "Stratigraphy of the Paleocene" 61 diction with those of Townsend (1985), who showed no extra reversals in 24BR in the "superlog for Site 550", but one thin, normal interval in Section 32.1 close to the top of the ash layers in his fig. 16 and, in his table 4, another additional thin, normal interval in Section 33.4, still above ash layer-17.…”

A possible link between the geomagnetic field and catastrophic climate at the Paleocene-Eocene thermal maximum

“…Records of the Paleocene-Eocene magnetic reversal are also indicated globally in data from the Bighorn Basin in Wyoming, United States (Tauxe et al, 1994), Deep Sea Drilling Project (DSDP) Site 550 in the northern Atlantic Ocean (Townsend, 1985), and DSDP Site 690 in the southernmost Atlantic Ocean (Spiess, 1990), though only one or two reversal signatures are recognized in the PETM section. Synchronous appearance of the Paleocene-Eocene magnetic reversal in both hemispheres has been confi rmed.…”

A late Paleocene-early Eocene NW European and North Sea magnetobiochronological correlation network

“…1996) Site 550 (Porcupine Abyssal Plain, SW of seaward edge of Goban Spur, NE Atlantic) (Fig. 3) Subchrons C24n.ln, C24n.3n and ?Chron C25n (partim) bracket a relatively long (62.85m) Chron C24r (Townsend 1985) making this a supposedly ideal site for detailed, integrated magnetobiostratigraphy (Table 1).…”

“…This ash does not occur at the corresponding level in Hole 550 at the base of NP9. It is uncertain whether the magnetic reversal between 419.51-425.5 m (Snyder & Waters 1985;Townsend 1985) corresponds to the Chron C25n/C24r boundary as indicated by Snyder & Waters 1985). The lowest occurrence of D. multiradiatus, normally associated with a level within Chron C25n, is at 424.85 m (Mtiller 1985) in an (unsampled) interval of unknown polarity.…”