Lozar, Francesca M. and Mussa, Massimo (2006): Silicoflagellate biostratigraphy, Hole 1149A (ODP Leg 185, Nadezhda Basin, Northwestern Pacific)

ODP 185
ODP 185 1149


Lozar, Francesca M.
Consiglio Nazionale delle Ricerche, Centro di Studi Sulla Geodinamica della Cantene Collisionali, Turin, Italy

Mussa, Massimo
Boston University, United States

Silicoflagellate biostratigraphy, Hole 1149A (ODP Leg 185, Nadezhda Basin, Northwestern Pacific)
In: Ludden, John N. (editor), Plank, Terry (editor), Escutia, Carlota (editor), Abrams, Lewis J., Alt, Jeffrey C., Armstrong, Robin N., Barr, Samantha, Bartolini, Annachiara, Cairns, Graeme, Fisk, Martin R., Guerin, Gilles, Haveman, Shelley A., Hirono, Tetsuro, Honnorez, Jose, Kelley, Katherine A., Larson, Roger L., Lozar, Francesca M., Murray, Richard W., Pletsch, Thomas K., Pockalny, Robert A., Rouxel, Olivier, Schmidt, Angelika, Smith, David C., Spivack, Arthur J., Staudigel, Hubert, Steiner, Maureen B., Valentine, Robert B., Proceedings of the Ocean Drilling Program; scientific results, Izu-Mariana Margin; covering Leg 185 of the drilling vessel JOIDES Resolution; Hong Kong, People's Republic of China, to Yokohama, Japan; Sites 801 and 1149; 12 April-14 June 1999
Texas A&M University, Ocean Drilling Program, College Station, TX, United States
Silicoflagellate assemblages have been studied from Hole 1149A (northwestern Pacific, Ocean Drilling Program Leg 185) in a continuous record of pelagic clay from lithologic Unit I. The biostratigraphic framework of D. Bukry, adapted in this work, is calibrated to tropical and subtropical fossil floras. Four biozones and three subzones have been recognized (from the lower Pliocene Dictyocha fibula Zone to the Quaternary Dictyocha aculeata aculeata Zone), and their zonal boundaries have been calibrated to the magnetostratigraphic scale. In particular, the boundary between the Dictyocha perlaevis delicata and the Dictyocha perlaevis ornata Subzones approximates the Pliocene/Pleistocene boundary. The identification of three closely spaced climatic events (the asperoid/fibuloid reversal at 75.11 meters below seafloor [mbsf], the sharp decrease in abundance of Distephanus sp. at 70.05 mbsf, and the last occurrence of Distephanus boliviensis at 68.46 mbsf) indicates the increased strength of the warm Kuroshio Current in the interval between 3.3 and 2.8 Ma, due to the final closure of the Central American Seaway and leading to the present-day hydrodynamic regime. The beginning of the acme of Mesocena quadrangula at 37.01 mbsf ( approximately 1.1 Ma) also shows a sharp warming in surface waters.
Coverage:Geographic coordinates:
West:143.2100East: 143.2100

Stratigraphy; biostratigraphy; biozones; Cenozoic; climate change; currents; depositional environment; Invertebrata; Kuroshio; Leg 185; microfossils; Nadezhda Basin; Neogene; North Pacific; Northwest Pacific; ocean currents; Ocean Drilling Program; ODP Site 1149; Pacific Ocean; paleo-oceanography; paleoenvironment; Pliocene; Protista; Silicoflagellata; species diversity; Tertiary; West Pacific;