Mesozoic Calcareous Nannofossils, Deep Sea Drilling Project Sites 415 and 416, Moroccan Basin

A zonation is presented for the oceanic late Middle Jurassic to Late Jurassic of the Atlantic Ocean. The oldest zone, the Stephenolithion bigotii Zone (subdivided into a Stephanolithion hexum Subzone and a Cyclagelosphaera margerelii Subzone), is middle Callovian to early Oxfordian. The Vagalapilla stradneri Zone is middle Oxfordian to Kimmeridgian. The Conusphaera mexicana Zone, subdivided into a lower Hexapodorhabdus cuvillieri Subzone and a Polycostella beckmannii Subzone, is the latest Kimmeridgian to Tithonian. Direct correlation of this zonation with the boreal zonation established for Britain and northern France (Barnard and Hay, 1974; Medd, 1982;Hamilton, 1982) is difficult because of poor preservation resulting in low diversity for the cored section at Site 534 and a lack of Tithonian marker species in the boreal realm.Correlations based on dinoflagellates and on nannofossils with stratotype sections (or regions) give somewhat different results. Dinoflagellates give generally younger ages, especially for the Oxfordian to Kimmeridgian part of the recovered section, than do nannofossils.

Section: Introductionsupporting

confidence: 67%

Jurassic Calcareous Nannofossil Zonation, an Overview with New Evidence from Deep Sea Drilling Project Site 534

Roth¹,

Medd²,

Watkins³

1983

“…Site 415 (Hole 415A) is located in the Agadir Submarine Canyon, south of Sites 370 and 416. Cepek et al (1980) assign these Cretaceous sediments to the Lithraphidites alatus and/or Eiffellithus turriseiffeli zones of Cenomanian to late Albian age but question the presence of the L. alatus Zone within the interval because only a few L. alatus occurred in one sample. The inter- val from the L. alatus to the E. turriseiffeli zones corresponds approximately to the L. acutum and E. turriseiffeli zones of Manivit et al (1977).…”

Section: Hiatusesmentioning

confidence: 98%

“…Hole 416A was drilled in the Morocco Basin very near Site 370. The hole has a limited Albian-lower Aptian section (Cepek et al, 1980) with several barren samples between the short mid-Albian and lower Aptian intervals. The zones used for this short interval are those of Thierstein (1973).…”

Section: Hiatusesmentioning

confidence: 99%

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Cretaceous Nannofossils from the Northwest African Margin, Deep Sea Drilling Project Leg 79

Wiegand¹

1984

Deep Sea Drilling Project Leg 79 recovered Cretaceous nannofossils at two localities, Sites 545 and 547. Species diversity of the Cretaceous coccoliths is high, and the assemblages range in age from early Valanginian-early Hauterivian to latest Maestrichtian.Site 545 and portions of Site 547 can be combined to form a composite section ranging from the upper Aptian-lower Albian to the middle to upper Cenomanian. As defined by nannofossil events, this section represents a complete record of sedimentary deposition. The interval appears to be the most extensive and complete Cretaceous section yet drilled off the Northwest African margin.The Campanian and Maestrichtian sediments found at Site 547 (Hole 547A) are the youngest Cretaceous strata found on the Northwest African margin. Like the middle Cretaceous sections, the uppermost Maestrichtian of this interval also represents a complete record of sedimentation.

“…Site 416 (Hole 416A) ( Fig. 1) penetrated approximately 45 m of the uppermost Jurassic (Cepek et al, 1980), but no other DSDP cruises in the area have recovered Jurassic coccoliths. A biostratigraphic study of Lower and Middle Jurassic nannofossils in Portugal (Fig.…”

Section: Genus Hexalithus Gardet 1955mentioning

confidence: 99%

Jurassic Nannofossils from the Northwest African Margin, Deep Sea Drilling Project Leg 79

Wiegand¹

1984

Sites 544, 545, and 547, drilled on DSDP Leg 79, recovered Jurassic calcareous nannofossils. Lower Jurassic (Sinemurian-lower Pliensbachian) nannofossils are found in Hole 547B; these are the oldest yet recovered by deep sea drilling. Three other Jurassic intervals are delineated by nannofossil biostratigraphy: the Lower-Middle Jurassic in Hole 547B; the Lower-Middle Jurassic in Hole 545; and the Upper Jurassic in Hole 547B. Low species diversity makes age determinations difficult for these portions of the Jurassic. Two new genera, Calcivascularis and Orthogonoides, have been described from these Lower Jurassic sediments.