New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes
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New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes. / Edgar, K. M.; Wilson, P. A.; Sexton, P. F.; Gibbs, S. J.; Roberts, A. P.; Norris, R. D.
In: Palaeogeography Palaeoclimatology Palaeoecology, Vol. 297, No. 3-4, 20.11.2010, p. 670-682.Research output: Contribution to journal › Article › peer-review
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T1 - New biostratigraphic, magnetostratigraphic and isotopic insights into the Middle Eocene Climatic Optimum in low latitudes
AU - Edgar, K. M.
AU - Wilson, P. A.
AU - Sexton, P. F.
AU - Gibbs, S. J.
AU - Roberts, A. P.
AU - Norris, R. D.
PY - 2010/11/20
Y1 - 2010/11/20
N2 - The Middle Eocene Climatic Optimum (MECO) was a warming event that interrupted the long-term Eocene cooling trend. While this event is well documented at high southern and mid-latitudes, it is poorly known from low latitudes and its timing and duration are not well constrained because of problems of hiati, microfossil preservation and weak magnetic polarity in key sedimentary sections. Here, we report the results of a study designed to improve the bio-, magneto- and chemostratigraphy of the MECO interval using high-resolution records from two low-latitude sections in the Atlantic Ocean, Ocean Drilling Program (ODP) Sites 1051 and 1260. We present the first detailed benthic foraminiferal stable isotope records of the MECO from the low latitudes as well as the biostratigraphic counts of Orbulinoides beckmanni and new magnetostrati-graphic results. Our data demonstrate a similar to 750 kyr-long duration for the MECO characterized by increasing delta(13)C and decreasing 6180, with minimum 6180 values lasting similar to 40 kyr at 40.1 Ma coincident with a short-lived negative delta(13)C excursion. Thereafter, 6180 and delta(13)C values recover rapidly. The shift to minimum 6180 values at 40.1 Ma is coincident with a marked increase in the abundance of the planktonic foraminifera O. beckmanni, consistent with its inferred warm-water preference. O. beckmanni is an important Eocene biostratigraphic marker, defining planktonic foraminiferal Zone E12 with its lowest and highest occurrences (LO and HOs). Our new records reveal that the LO of O. beckmanni is distinctly diachronous, appearing similar to 500 kyr earlier in the equatorial Atlantic than in the subtropics (40.5 versus 41.0 Ma). We also show that, at both sites, the HO of O. beckmanni at 39.5 Ma is younger than the published calibrations, increasing the duration of Zone E12 by at least 400 kyr. In accordance with the tropical origins of O. beckmanni, this range expansion to higher latitudes may have occurred in response to sea surface warming during the MECO and subsequently disappeared with cooling of surface waters. (C) 2010 Elsevier B.V. All rights reserved.
AB - The Middle Eocene Climatic Optimum (MECO) was a warming event that interrupted the long-term Eocene cooling trend. While this event is well documented at high southern and mid-latitudes, it is poorly known from low latitudes and its timing and duration are not well constrained because of problems of hiati, microfossil preservation and weak magnetic polarity in key sedimentary sections. Here, we report the results of a study designed to improve the bio-, magneto- and chemostratigraphy of the MECO interval using high-resolution records from two low-latitude sections in the Atlantic Ocean, Ocean Drilling Program (ODP) Sites 1051 and 1260. We present the first detailed benthic foraminiferal stable isotope records of the MECO from the low latitudes as well as the biostratigraphic counts of Orbulinoides beckmanni and new magnetostrati-graphic results. Our data demonstrate a similar to 750 kyr-long duration for the MECO characterized by increasing delta(13)C and decreasing 6180, with minimum 6180 values lasting similar to 40 kyr at 40.1 Ma coincident with a short-lived negative delta(13)C excursion. Thereafter, 6180 and delta(13)C values recover rapidly. The shift to minimum 6180 values at 40.1 Ma is coincident with a marked increase in the abundance of the planktonic foraminifera O. beckmanni, consistent with its inferred warm-water preference. O. beckmanni is an important Eocene biostratigraphic marker, defining planktonic foraminiferal Zone E12 with its lowest and highest occurrences (LO and HOs). Our new records reveal that the LO of O. beckmanni is distinctly diachronous, appearing similar to 500 kyr earlier in the equatorial Atlantic than in the subtropics (40.5 versus 41.0 Ma). We also show that, at both sites, the HO of O. beckmanni at 39.5 Ma is younger than the published calibrations, increasing the duration of Zone E12 by at least 400 kyr. In accordance with the tropical origins of O. beckmanni, this range expansion to higher latitudes may have occurred in response to sea surface warming during the MECO and subsequently disappeared with cooling of surface waters. (C) 2010 Elsevier B.V. All rights reserved.
KW - Middle Eocene Climatic Optimum
KW - Site 1051
KW - Site 1260
KW - Planktonic foraminifera
KW - Biostratigraphy
KW - Magnetostratigraphy
KW - PALEOCENE THERMAL MAXIMUM
KW - FORAMINIFERAL BIOSTRATIGRAPHY
KW - PLANKTONIC-FORAMINIFERA
KW - MAGNETIC STRATIGRAPHY
KW - EVENTS
KW - CALIBRATION
KW - SEDIMENTS
KW - PACIFIC
KW - GUBBIO
KW - CORES
U2 - 10.1016/j.palaeo.2010.09.016
DO - 10.1016/j.palaeo.2010.09.016
M3 - Article
VL - 297
SP - 670
EP - 682
JO - Palaeogeography Palaeoclimatology Palaeoecology
JF - Palaeogeography Palaeoclimatology Palaeoecology
SN - 0031-0182
IS - 3-4
ER -