A Paleontological Synthesis of ODP Leg 210, Newfoundland Basin

Abstract

Sediments recovered from Ocean Drilling Program Leg 210 Hole 1276A range in age from Early Cretaceous (earliest Albian) to Paleogene (earliest Oligocene). In this study, samples were processed and analyzed for micropaleontological and palynological content, as well as sedimentary components. Core recovery from this site was good (85% between 800 and 1725.16 meters below seafloor), and the majority of samples processed yielded microfossils of some nature. Although none of the major groups are consistently present in all samples, calcareous nannofossils, agglutinated benthic foraminifers, and radiolarians do occur in many samples. The best age constraints for Hole 1276A are provided by calcareous nannofossils and dinoflagellate cysts. Age-diagnostic planktonic foraminifers are more commonly found in redeposited turbidite sandstones rather than in the autochthonous pelagic mudrocks. The depositional environments of the sediments have been interpreted as varying in oxygenation but having been deposited at abyssal depths (>2000 m) near or below the calcite carbonate depth (CCD). Almost uninterrupted deepwater deposition since the Aptian is evidenced both by the evolutionary succession of biota recovered from the sediments and by the sedimentary history of turbidites and gravity flow deposits derived from neritic and bathyal sources on the adjacent margin. A condensed interval recorded in the Turonian–Maastrichtian is likely associated with sediment starvation at times of high global sea level. A disconformity and condensed interval in the lower middle Eocene (~48.5–43.7 Ma) is associated with a change in global sea level and may be associated with invigorated deepwater current activity. Anoxic conditions affected the deep seafloor of the North Atlantic during Oceanic Anoxic Event 1Urquhart, E., Gardin, S., Leckie, R.M., Wood, S.A., Pross, J., Georgescu, M.D., Ladner, B., and Takata, H., 2007. A paleontological synthesis of ODP Leg 210, Newfoundland Basin. In Tucholke, B.E., Sibuet, J.-C., and Klaus, A. (Eds.), Proc. ODP, Sci. Results, 210: College Station, TX (Ocean Drilling Program), 1–53. doi:10.2973/ odp.proc.sr.210.115.2007 2RSMAS, University of Miami, 4600 Rickenbacker Causeway, Miami FL 33149, USA. eurquhart@rsmas.miami.edu 3CNRS UMR 5341, Universite Pierre et Marie Curie, 4 Place Jussieu, Case 104, Paris Cedex 05 75353, France. 4Department of Geosciences, University of Massachusetts, 611 North Pleasant Street, Amherst MA 01003, USA. 512155 Lucille Lane, Anchorage AK 99515, USA. 6Institute of Geosciences, Johann Wolfgang Goethe University, Allee 1, Frankfurt D-60438, Germany. 7University of Saskatchewan, Department of Geological Sciences, 114 Science Place, Saskatoon SK S7N 5E2, Canada. Present address: Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4, Canada. 8Total Biostratigraphic Services, Inc., 7000 Ute Court, Ocean Springs MS 39564, USA. 9Research Center for Coastal Lagoon, Shimane University, 1060 Nishikawatsu, Matsue 690-8504, Japan. Initial receipt: 2 March 2007 Acceptance: 10 July 2007 Web publication: 27 July 2007 Ms 210SR-115 E. URQUHART ET AL. LEG 210 PALEONTOLOGICAL SYNTHESIS 2 (OAE) 1b (earliest Albian, ~112 Ma) and OAE2 (Cenomanian–Turonian boundary interval, ~93.5 Ma). Cooling during the early Turonian followed the vast carbon burial associated with OAE2 based on calcareous nannofossil assemblages. The recovery of a nearly complete Cretaceous– Paleogene boundary transition represents one of the deepest-water records of the end-Cretaceous event known. Another important paleontological discovery from Hole 1276A was the redeposited large-size benthic foraminifers of Campanian–Maastrichtian and latest Paleocene– early Eocene ages, which point to a nearby source of shallow, warmwater carbonates during these two periods of global warmth. INTRODUCTION Ocean Drilling Program (ODP) Leg 210 Site 1276 is located in the deep Newfoundland Basin, east of the Grand Banks and south of the Flemish Cap (45°24.3198′N, 44°47.1496′W) in 4549 m of water (Tucholke, Sibuet, Klaus, et al., 2004). The site was cored in the interval from 800.0 to 1736.9 meters below seafloor (mbsf) with 85% core recovery. The principal scientific objectives of ODP Leg 210 focused on the rifting and postrift sedimentation of the Newfoundland continental margin in relation to the conjugate Iberian continental margin. They represent nonvolcanic rifted margins, and ODP Leg 210 is the first coring on the western side of the rift. Site 1276 was drilled on transitional crust adjacent to oceanic crust of probable Barremian age based on the interpretation of magnetic Anomaly M3 (Tucholke, Sibuet, Klaus, et al., 2004) (Fig. F1). Site 1277 was drilled on a shallow basement high ~40 km southeast of Site 1276. Secondary drilling objectives of ODP Leg 210 included the paleoceanographic history at the northern edge of the central North Atlantic as the gateway to the northern North Atlantic began to open during the Early Cretaceous. The Cretaceous–Paleogene interval was a time of major paleoceanographic events including oceanic anoxic events of the mid-Cretaceous, the Cretaceous/Paleogene boundary, and the Paleocene/Eocene Thermal Maximum. In addition, seafloor spreading and ocean gateway deepening and widening at both ends of the central North Atlantic played a major role in changing surface and deepwater circulation during this time. From Hole 1276A we recovered a 936.9-m-thick succession of mudrock, shale, and interbedded turbidite sandstone and other gravity flow deposits spanning ~80 m.y. of the mid-Cretaceous to early Oligocene (~113–33 Ma). Despite the pervasive redeposited nature of the sedimentary succession cored at Site 1276, the paleontological findings reported here provide a robust temporal framework for the largely uninterrupted record of changing paleoenvironmental conditions of the surface ocean and in the deep Newfoundland Basin. This synthesis incorporates new paleontological results since the publication of the Leg 210 Initial Reports volume (Tucholke, Sibuet, Klaus, et al., 2004). It provides a detailed revision of the calcareous nannofossil biostratigraphy, as well as an updated discussion of sedimentation history and comprehensive summary of North Atlantic paleoceanography based on paleontological data from Site 1276. Site 1277 is not included in this analysis because of the paucity of sediment and lack of age-diagnostic fossils. 54°W 52° 50° 48° 46° 44° 42° 40° 5000 4000 300