Biostratigraphic, Paleoenvironmental, and Paleomagnetic Synthesis of the Goban Spur Region, Deep Sea Drilling Project Leg 80

Abstract

A composite stratigraphic section based on the four DSDP-IPOD Leg 80 drill sites provides a nearly complete record of syn-rift and post-rift events in the vicinity of Goban Spur. Syn-rift sediments were deposited in marginal marine to outer shelf environments. Above the "breakup" unconformity (hiatus spanning most of the Aptian), post-rift Albian sediments indicate the development of a deep-water seaway in the Goban Spur region. The latest Campanian/Maestrichtian interval records the initiation of rather uniform, widely distributed marine sedimentation throughout the region. Climatic changes, rather than changes in water depth, became conspicuous during the Tertiary. Widespread, nearly synchronous periods of nondeposition or erosion occurred in the Paleocene, middle Eocene, middle Oligocene, and late Miocene. Differences in the sediment record among sites are due to their varying positions (1) along the margin of the developing Atlantic seaway and (2) within their respective half-graben depositional basins.

A magnetostratigraphic calibration of Middle Miocene through Pliocene dinoflagellate cyst and acritarch events in the Iceland Sea (Ocean Drilling Program Hole 907A)

“…De Verteuil and Norris (1996) used the HO of H. obscura to define the top of their DN9 zone in the upper Tortonian (c. 7.5 Ma) of the Salisbury Embayment, eastern U.S.A. A similar position at the top of zone DN9 was reported for the HO from the continental margin of New Jersey Gartner and Shyu, 1996). In eastern North Atlantic DSDP Site 555, the HO was reported within the lower part of nannofossil zone NN11 (upper Tortonian, Edwards, 1984;Backman, 1984), whereas H. obscura ranges to the nannofossil zone boundary NN5/6 in DSDP Hole 548A (Brown and Downie, 1985;Müller, 1985), although here the HO is probably lost within an apparent hiatus separating the upper Middle Miocene from middle Upper Miocene (Snyder et al, 1985). For eastern North Atlantic IODP Holes 1318B and C, Louwye et al (2007b) reported H. obscura in low numbers fairly persistently throughout a Miocene succession that extends into the upper Serravallian.…”

“…A relatively high HO is recorded in eastern North Atlantic DSDP Site 555 (upper Tortonian, Edwards, 1984;Backman, 1984) and eastern North Atlantic DSDP Site 548 (upper Tortonian, Brown and Downie, 1985;Müller, 1985). At the latter site, an apparent hiatus of c. 5.0 Ma separates the upper Middle Miocene from middle Upper Miocene (Snyder et al, 1985) and therefore the HPO (mid-Serravallian, Müller, 1985) from the HO, which is marked by a single occurrence only and hence is potentially reworked. In this context, the true upper range is probably lost within the hiatus.…”

Subsidence patterns in western margin basins: evidence from the Faeroe–Shetland Basin

“…As subsidence rates began to accelerate in the centre of the Faeroe-Shetland Basin, a major unconformity developed across the basin flanks. Mid-Paleocene unconformities have also been reported from the Western Approaches Trough, Porcupine Basin, Goban Spur, Biscay and Vering margins (Murray 1979;Snyder et al 1985;Hillis 1988;Dobson et al 1991;Skogseid et al 1992), again indicating a regional control.…”

Evidence for changes in Mesozoic and Cenozoic oceanic circulation on the south-western continental margin of Ireland: DSDP/IPOD Leg 80

“…13), suggesting the possible influence of contour-currents brought about by introduction of corrosive northern bottom-waters into the Goban Spur region. Such corrosive bottom water could account for the marked decrease in calcareous fossils and the coincident increase in siliceous fossils (sponge spicules, diatoms, silicoflagellates) observed at Site 550 (Snyder et al 1985;Miiller 1985;Karpof et al 1985). The presence of cool surface waters at Site 549 is indicated by well-preserved, low-diversity associations of early Palaeocene planktonic foraminifers and nannofossils (Snyder et al 1985).…”

“…The authors infer from seismic profiles (Figs 3 and 4) that no sediment much older than Barremian was deposited in the deepest parts of the adjacent grabens. The sequence drilled at Site 549 reflects a progressive deepening from hyposaline to open-marine, outer sublittoral palaeoenvironments (Snyder et al 1985;Rat et al 1985;Fig. 5).…”