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

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 appa...

Full description

Bibliographic Details
Published in:Climate of the Past
Main Authors: Lawrence, Kira T., Bailey, I., Raymo, M. E.
Format: Article in Journal/Newspaper
Language:unknown
Published: Climate of the Past 2013
Subjects:
Online Access:http://hdl.handle.net/10385/1377
https://doi.org/10.5194/cp-9-2391-2013
Description
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 similar to 3.2 and 3 Ma. However, an even more accurate shore-based, u-channel-derived polarity chronozone stratigraphy for the past similar to 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.