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Atlantic Deep-water Response to the Early Pliocene Shoaling of the Central American Seaway.

Bell DB, Jung SJ, Kroon D, Hodell DA, Lourens LJ, Raymo ME - Sci Rep (2015)

Bottom Line: We find that NADW formation was vigorous prior to 4.7 Ma and showed limited subsequent change.Hence, the overall structure of the deep Atlantic was largely unaffected by the early Pliocene CAS shoaling, corroborating other evidence that indicates larger changes in NADW resulted from earlier and deeper shoaling phases.This finding implies that the early Pliocene shoaling of the CAS had no profound impact on the evolution of climate.

View Article: PubMed Central - PubMed

Affiliation: School of Geosciences, University of Edinburgh, Edinburgh, UK.

ABSTRACT
The early Pliocene shoaling of the Central American Seaway (CAS), ~4.7-4.2 million years ago (mega annum-Ma), is thought to have strengthened Atlantic Meridional Overturning Circulation (AMOC). The associated increase in northward flux of heat and moisture may have significantly influenced the evolution of Pliocene climate. While some evidence for the predicted increase in North Atlantic Deep Water (NADW) formation exists in the Caribbean and Western Atlantic, similar evidence is missing in the wider Atlantic. Here, we present stable carbon (δ(13)C) and oxygen (δ(18)O) isotope records from the Southeast Atlantic-a key region for monitoring the southern extent of NADW. Using these data, together with other δ(13)C and δ(18)O records from the Atlantic, we assess the impact of the early Pliocene CAS shoaling phase on deep-water circulation. We find that NADW formation was vigorous prior to 4.7 Ma and showed limited subsequent change. Hence, the overall structure of the deep Atlantic was largely unaffected by the early Pliocene CAS shoaling, corroborating other evidence that indicates larger changes in NADW resulted from earlier and deeper shoaling phases. This finding implies that the early Pliocene shoaling of the CAS had no profound impact on the evolution of climate.

No MeSH data available.


Related in: MedlinePlus

Time series of δ13C data (‰ vs Vienna Pee Dee Belemnite) from all sites shown in Fig. 1.Data has been resampled at common 10 kyr time steps (linear integration). Horizontal black lines show average δ13C values for the time slice intervals 5.0–4.7 Ma (Pre CAS shoaling) and 4.2–3.6 Ma (Post CAS shoaling). Arrows indicate approximate modern δ13C values for each site location48. Note that data for Site 607 has been resampled at 10 kyr intervals, as is available from32, while data from Site 704 prior to 4.2 Ma is displayed as symbols in order to highlight the low resolution and stratigraphic uncertainty. Data references are given in Table 1.
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f4: Time series of δ13C data (‰ vs Vienna Pee Dee Belemnite) from all sites shown in Fig. 1.Data has been resampled at common 10 kyr time steps (linear integration). Horizontal black lines show average δ13C values for the time slice intervals 5.0–4.7 Ma (Pre CAS shoaling) and 4.2–3.6 Ma (Post CAS shoaling). Arrows indicate approximate modern δ13C values for each site location48. Note that data for Site 607 has been resampled at 10 kyr intervals, as is available from32, while data from Site 704 prior to 4.2 Ma is displayed as symbols in order to highlight the low resolution and stratigraphic uncertainty. Data references are given in Table 1.

Mentions: Timeseries of benthic δ13C and δ18O data from all Atlantic sites are presented in Figs 4 and 5, respectively, while site locations and data references are given in Table 1. The benthic δ18O stack of Lisiecki and Raymo49 (hereafter LR04) is also shown in Fig. 5 next to each record so that stratigraphic alignment can be seen. In order to directly assess the impact of the early Pliocene shoaling phase, we also compare average Atlantic deep-water conditions for time slices on either side of the period 4.7–4.2 Ma (Fig. 6).


Atlantic Deep-water Response to the Early Pliocene Shoaling of the Central American Seaway.

Bell DB, Jung SJ, Kroon D, Hodell DA, Lourens LJ, Raymo ME - Sci Rep (2015)

Time series of δ13C data (‰ vs Vienna Pee Dee Belemnite) from all sites shown in Fig. 1.Data has been resampled at common 10 kyr time steps (linear integration). Horizontal black lines show average δ13C values for the time slice intervals 5.0–4.7 Ma (Pre CAS shoaling) and 4.2–3.6 Ma (Post CAS shoaling). Arrows indicate approximate modern δ13C values for each site location48. Note that data for Site 607 has been resampled at 10 kyr intervals, as is available from32, while data from Site 704 prior to 4.2 Ma is displayed as symbols in order to highlight the low resolution and stratigraphic uncertainty. Data references are given in Table 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507445&req=5

f4: Time series of δ13C data (‰ vs Vienna Pee Dee Belemnite) from all sites shown in Fig. 1.Data has been resampled at common 10 kyr time steps (linear integration). Horizontal black lines show average δ13C values for the time slice intervals 5.0–4.7 Ma (Pre CAS shoaling) and 4.2–3.6 Ma (Post CAS shoaling). Arrows indicate approximate modern δ13C values for each site location48. Note that data for Site 607 has been resampled at 10 kyr intervals, as is available from32, while data from Site 704 prior to 4.2 Ma is displayed as symbols in order to highlight the low resolution and stratigraphic uncertainty. Data references are given in Table 1.
Mentions: Timeseries of benthic δ13C and δ18O data from all Atlantic sites are presented in Figs 4 and 5, respectively, while site locations and data references are given in Table 1. The benthic δ18O stack of Lisiecki and Raymo49 (hereafter LR04) is also shown in Fig. 5 next to each record so that stratigraphic alignment can be seen. In order to directly assess the impact of the early Pliocene shoaling phase, we also compare average Atlantic deep-water conditions for time slices on either side of the period 4.7–4.2 Ma (Fig. 6).

Bottom Line: We find that NADW formation was vigorous prior to 4.7 Ma and showed limited subsequent change.Hence, the overall structure of the deep Atlantic was largely unaffected by the early Pliocene CAS shoaling, corroborating other evidence that indicates larger changes in NADW resulted from earlier and deeper shoaling phases.This finding implies that the early Pliocene shoaling of the CAS had no profound impact on the evolution of climate.

View Article: PubMed Central - PubMed

Affiliation: School of Geosciences, University of Edinburgh, Edinburgh, UK.

ABSTRACT
The early Pliocene shoaling of the Central American Seaway (CAS), ~4.7-4.2 million years ago (mega annum-Ma), is thought to have strengthened Atlantic Meridional Overturning Circulation (AMOC). The associated increase in northward flux of heat and moisture may have significantly influenced the evolution of Pliocene climate. While some evidence for the predicted increase in North Atlantic Deep Water (NADW) formation exists in the Caribbean and Western Atlantic, similar evidence is missing in the wider Atlantic. Here, we present stable carbon (δ(13)C) and oxygen (δ(18)O) isotope records from the Southeast Atlantic-a key region for monitoring the southern extent of NADW. Using these data, together with other δ(13)C and δ(18)O records from the Atlantic, we assess the impact of the early Pliocene CAS shoaling phase on deep-water circulation. We find that NADW formation was vigorous prior to 4.7 Ma and showed limited subsequent change. Hence, the overall structure of the deep Atlantic was largely unaffected by the early Pliocene CAS shoaling, corroborating other evidence that indicates larger changes in NADW resulted from earlier and deeper shoaling phases. This finding implies that the early Pliocene shoaling of the CAS had no profound impact on the evolution of climate.

No MeSH data available.


Related in: MedlinePlus