Calcareous nannofossils from the Eocene North Atlantic Ocean (IODP Expedition 342 Sites U1403–1411).

Abstract

Integrated Ocean Drilling Program Expedition 342 (June-July 2012) cored nine sites and 18 holes (Sites U1403-U1411) on the J-Anomaly and the Southeast Newfoundland ridges in the NW Atlantic Ocean. These sites recovered sections ranging from Pleistocene to upper Albian, but the expedition particularly focussed on the recovery of expanded Paleogene successions with high quality microfossil preservation. This was achieved by choosing sites with thick packages of drift-type sediments on topographic highs that would maximise the preservation of carbonate. The expedition suceeded in recovering middle Eocene to lower Oligocene and upper Oligocene to lower Miocene high sedimentation rate sediment sequences with very well preserved microfossils. Highlights of the expedition include the recovery of continuous Eocene/Oligocene and Oligocene/Miocene boundaries, a Cretaceous-Paleogene boundary section with intact spherule layer, and Cenomanian/Turonian section with a 44 cm black shale. Here, we describe notable aspects of the Eocene nannofossil record, including the exceptional preservation and the evolution of several important Eocene groups: Nannotetrina, the Sphenolithus furcatolithoides group, the Reticulofenestra bisecta group and the Coccolithus gigas group. We also present a taxonomic overview of the Eocene nannofossil assemblages from Sites U1403-1411, illustrating 164 taxa and describing 25 new species (Blackites friedrichii, Blackites sextonii, Blackites subtilis, Calcidiscus scullyae, Clausicoccus norrisii, Coccolithus hulliae, Coccolithus opdykei, Cruciplacolithus nishii, Helicosphaera prolixa, Holodiscolithus agniniae, Holodiscolithus lippertii, Holodiscolithus liuii, Holodiscolithus whitesideae, Nannotetrina plana, Nannotetrina ruda, Neococcolithes purus, Neococcolithes radiatus, Pontosphaera brinkhuisii, Pontosphaera hollisii, Pontosphaera romansii, Pontosphaera wilsonii, Reticulofenestra magniscutum, Scyphosphaera interstincta, Semihololithus pseudobiskayae, Syracosphaera octiforma) and five new combinations (Blackites inversus, Pontosphaera zigzag, Reticulofenestra erbae, Reticulofenestra isabellae, Umbilicosphaera elliptica).