A quantitative analysis of calcareous nannofossils across a late Oligocene paleolatitude transect of the North Atlantic Ocean

Author(s): Clark, William B.; Watkins, David K.
Author Affiliation(s): Primary:
University of Nebraska at Lincoln, Department of Earth and Atmospheric Sciences, Lincoln, NE, United States
Volume Title: Geological Society of America, 2018 annual meeting & exposition
Source: Abstracts with Programs - Geological Society of America, 50(6); Geological Society of America, 2018 annual meeting & exposition, Indianapolis, IN, Nov. 4-7, 2018. Publisher: Geological Society of America (GSA), Boulder, CO, United States. ISSN: 0016-7592 CODEN: GAAPBC
Note: In English
Summary: Samples from ODP Sites 926, 628, 563, U1406, 647, and 918, were analyzed quantitatively across a paleolatitude transect of the North Atlantic Ocean to determine the paleolatitudinal distribution of calcareous nannofossils in the Late Oligocene and the effects of that distribution on biostratigraphic resolution. Detrended Correspondence Analysis (DCA), a Temperature index (TI), and the Shannon Diversity Index (H), were used to examine the paleoenvironmental gradients which exerted the most control over the distribution of species and their abundances. The temperature index correlates significantly to the first axis of the DCA, suggesting that thermal controls were the most important factor in the distribution of late Oligocene nannofossils in the North Atlantic. Shannon Diversity and the percent abundance of the taxon Reticulofenestra minuta correlates significantly to DCA 2, suggesting that surface water mass fertility was an important secondary controlling factor during the Late Oligocene. A biochronological analysis utilizing Unitary Associations (UA) divided the assemblage into 6 UAs, correlating with existing biostratigraphic schemes. UA 3 and UA 4, defined by the base of Sphenolithus calyculus, was not used consistently in current biostratigraphy, and offers an additional bioevent for the Upper Oligocene. The absence of UA 5 at Hole 926B reveals a disconformity that was not identified previously. Current zonation schemes cannot be accurately applied to the North Atlantic Ocean north of 53° latitude. The best biostratigraphic resolution in the late Oligocene North Atlantic is restricted to the upper mid latitudes Sites 628, 563, and U1406. These latitudes, from 27-40°, represent the warm gyre center and the temperate western gyre perimeter.
Year of Publication: 2018
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 12 Stratigraphy, Historical Geology and Paleoecology; Assemblages; Atlantic Ocean; Biogeography; Biostratigraphy; Biozones; Ceara Rise; Cenozoic; Correspondence analysis; DSDP Site 563; Deep Sea Drilling Project; Equatorial Atlantic; Expedition 342; IODP Site U1406; IPOD; Integrated Ocean Drilling Program; Irminger Basin; Labrador Sea; Leg 101; Leg 105; Leg 152; Leg 154; Leg 82; Little Bahama Bank; Microfossils; Mid-Atlantic Ridge; Nannofossils; North Atlantic; ODP Site 628; ODP Site 647; ODP Site 918; ODP Site 926; Ocean Drilling Program; Oligocene; Paleogene; Reticulofenestra minuta; Sphenolithus; Sphenolithus calyculus; Statistical analysis; Tertiary; Upper Oligocene
Coordinates: N402059 N402100 W0513859 W0513900
N333831 N333832 W0434602 W0434603
N273139 N273139 W0781857 W0781857
N034309 N034309 W0425430 W0425430
Record ID: 2019014421
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States