Coupled evolution of temperature and carbonate chemistry during the Paleocene-Eocene; new trace element records from the low latitude Indian Ocean

TY - JOUR

T1 - Coupled evolution of temperature and carbonate chemistry during the Paleocene-Eocene; new trace element records from the low latitude Indian Ocean

AU - Barnet, James

AU - Littler, Kate

AU - Harper, Dustin

AU - LeVay, Leah J

AU - Edgar, Kirsty

AU - Henehan, Michael

AU - Babila, Tali L.

AU - Ullmann, Clemens

AU - Leng, Melanie J.

AU - Kroon, Dick

AU - Zachos, James

PY - 2020/9/1

Y1 - 2020/9/1

N2 - The early Paleogene represents the most recent interval in Earth's history characterized by global greenhouse warmth on multi-million year timescales, yet our understanding of long-term climate and carbon cycle evolution in the low latitudes, and in particular the Indian Ocean, remains very poorly constrained. Here we present the first long-term sub-eccentricity-resolution stable isotope (δ 13C and δ 18O) and trace element (Mg/Ca and B/Ca) records spanning the late Paleocene–early Eocene (∼58–53 Ma) across a surface–deep hydrographic reconstruction of the northern Indian Ocean, resolving late Paleocene 405-kyr paced cyclicity and a portion of the PETM recovery. Our new records reveal a long-term warming of ∼4–5 °C at all depths in the water column, with absolute surface ocean temperatures and magnitudes of warming comparable to the low latitude Pacific. As a result of warming, we observe a long-term increase in δ 18O sw of the mixed layer, implying an increase in net evaporation. We also observe a collapse in the temperature gradient between mixed layer- and thermocline-dwelling species from ∼57–54 Ma, potentially due to either the development of a more homogeneous water column with a thicker mixed layer, or depth migration of the Morozovella in response to warming. Synchronous warming at both low and high latitudes, along with decreasing B/Ca ratios in planktic foraminifera indicating a decrease in ocean pH and/or increasing dissolved inorganic carbon, suggest that global climate was forced by rising atmospheric CO 2 concentrations during this time.

AB - The early Paleogene represents the most recent interval in Earth's history characterized by global greenhouse warmth on multi-million year timescales, yet our understanding of long-term climate and carbon cycle evolution in the low latitudes, and in particular the Indian Ocean, remains very poorly constrained. Here we present the first long-term sub-eccentricity-resolution stable isotope (δ 13C and δ 18O) and trace element (Mg/Ca and B/Ca) records spanning the late Paleocene–early Eocene (∼58–53 Ma) across a surface–deep hydrographic reconstruction of the northern Indian Ocean, resolving late Paleocene 405-kyr paced cyclicity and a portion of the PETM recovery. Our new records reveal a long-term warming of ∼4–5 °C at all depths in the water column, with absolute surface ocean temperatures and magnitudes of warming comparable to the low latitude Pacific. As a result of warming, we observe a long-term increase in δ 18O sw of the mixed layer, implying an increase in net evaporation. We also observe a collapse in the temperature gradient between mixed layer- and thermocline-dwelling species from ∼57–54 Ma, potentially due to either the development of a more homogeneous water column with a thicker mixed layer, or depth migration of the Morozovella in response to warming. Synchronous warming at both low and high latitudes, along with decreasing B/Ca ratios in planktic foraminifera indicating a decrease in ocean pH and/or increasing dissolved inorganic carbon, suggest that global climate was forced by rising atmospheric CO 2 concentrations during this time.

KW - Indian Ocean

KW - Paleocene-Eocene Thermal Maximum

KW - Paleogene

KW - paleoceanography

KW - paleoclimate

KW - trace elements

UR - http://www.scopus.com/inward/record.url?scp=85086580044&partnerID=8YFLogxK

U2 - 10.1016/j.epsl.2020.116414

DO - 10.1016/j.epsl.2020.116414

M3 - Article

VL - 545

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

SN - 0012-821X

M1 - 116414

ER -