Re-evaluation of the age model for North Atlantic Ocean Site 982; arguments for a return to the original chronology

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doi: 10.5194/cp-9-2391-2013
Author(s): Lawrence, K. T.; Bailey, I.; Raymo, M. E.
Author Affiliation(s): Primary:
Lafayette College, Department of Geology and Environmental Geosciences, Easton, PA, United States
Other:
University of Southampton, United Kingdom
Lamont-Doherty Earth Observatory, United States
Volume Title: Climate of the Past
Source: Climate of the Past, 9(5), p.2391-2397. Publisher: Copernicus, Katlenburg-Lindau, International. ISSN: 1814-9324
Note: In English. Includes supplement, http://www.clim-past.net/9/2391/2013/cp-9-2391-2013-supplement.pdf; published in Climate of the Past Discussion: 29 April 2013, http://www.clim-past-discuss.net/9/2217/2013/cpd-9-2217-2013.html; accessed in May, 2014. 23 refs.; illus., incl. sketch map
Summary: Recently, the veracity of the published chronology for the Pliocene section of North Atlantic Ocean Drilling Program Site 982 was called into question. Here, we examine the robustness of the original age model as well as the proposed age model revision. The proposed revision is predicated on an apparent misidentification of the depth to the Gauss-Matuyama (G/M) polarity chronozone reversal boundary (2.581 Ma) based on preliminary shipboard paleomagnetic data, and offers a new chronology that includes a hiatus between ∼3.2 and 3 Ma. However, an even more accurate shore-based, u-channel-derived polarity chronozone stratigraphy for the past ∼2.7 Ma supports the shipboard composite stratigraphy and demonstrates that the original estimate of the depth of the G/M reversal in the Site 982 record is correct. Thus, the main justification forwarded to support the revised chronology no longer exists. We demonstrate that the proposed revision results in a pronounced anomaly in sedimentation rates proximal to the proposed hiatus, erroneous assignment of marine-isotope stages in the Site 982 Pliocene benthic stable oxygen isotope stratigraphy, and a markedly worse correlation of proxy records between this site and other regional paleoclimate data. We conclude that the original chronology for Site 982 is a far more accurate age model than that which arises from the published revision. We strongly recommend the use of the original chronology for all future work at Site 982.
Year of Publication: 2013
Research Program: DSDP Deep Sea Drilling Project
IODP Integrated Ocean Drilling Program
IPOD International Phase of Ocean Drilling
ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Atlantic Ocean; Benthic environment; Cenozoic; Chronology; Chronostratigraphy; DSDP Site 607; DSDP Site 609; DSDP Site 610; DSDP Site 611; Deep Sea Drilling Project; East Pacific; Equatorial Pacific; Expedition 306; Expeditions 303/306; Foraminifera; Gauss Chron; IODP Site U1314; IPOD; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Leg 111; Leg 162; Leg 94; MIS 2; MIS 6; Matuyama Chron; Microfossils; Mid-Atlantic Ridge; Neogene; North Atlantic; North Pacific; Northeast Atlantic; Northeast Pacific; O-18/O-16; ODP Site 677; ODP Site 982; ODP Site 984; Ocean Drilling Program; Oxygen; Pacific Ocean; Paleo-oceanography; Paleoclimatology; Paleomagnetism; Paleotemperature; Pliocene; Protista; Reykjanes Ridge; Rockall Bank; Rockall Plateau; Rockall Trough; Sea-surface temperature; Sedimentation; Sedimentation rates; Stable isotopes; Tertiary; Upper Cenozoic
Coordinates: N573100 N573100 W0155200 W0155200
Record ID: 2014084215
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from Copernicus Gesellschaft, Katlenburg-Lindau, Germany