| Autor: |
Zhou, Yuxin, Lisiecki, Lorraine E., Lee, Taehee, Gebbie, Geoffrey, Lawrence, Charles |
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| Zdroj: |
Geophysical Research Letters; 7/16/2024, Vol. 51 Issue 13, p1-10, 10p |
| Abstrakt: |
Benthic δ18O stacks are the benchmarks by which paleoceanographic data are stratigraphically aligned and compared. However, a recent study found that between 1.8 and 1.9 million years ago (Ma) several Ceara Rise records differed substantially from the widely used LR04 global stack. Here, we use new Bayesian stacking software to construct regional stacks and demonstrate a geographical divergence in benthic δ18O features from 1.8 to 1.9 Ma. The pattern of isotopic stage features observed in the Ceara Rise is widespread throughout the Atlantic and differs notably from Pacific records. We propose that this regional difference in isotopic stages may be the result of relatively strong precession forcing and weaker obliquity forcing between 1.8 and 1.9 Ma. In accordance with the Antiphase Hypothesis, our results highlight a period of apparent sensitivity to regional precession forcing that is masked during most of the 41‐Kyr world due to the amplitude modulation of obliquity forcing. Plain Language Summary: To determine the age of deep‐sea sediments, often the oxygen isotope ratios of microfossils are measured and compared to a previously compiled global benchmark. Recently, one of the most widely used oxygen isotope benchmarks has been challenged based on a comparison with several Atlantic records. In this study we assess several lines of evidence including utilizing newly available data and software. We confirm the challenge to the global oxygen isotope benchmark and find that it is more widespread than originally realized. Particularly, we find that oxygen isotope records display different patterns between the Atlantic and Pacific Oceans from 1.8 to 1.9 million years ago (Ma). We propose that this difference is the result of the opposing seasonal solar radiation anomalies received by the northern and southern hemispheres, which exhibited particularly large amplitudes during this time. Our study adds supporting evidence to a hypothesis that explains the dominant frequency of oxygen isotopic cycles from 1.2 to 2.6 Ma. Key Points: New Atlantic and Pacific benthic δ18O stacks show different patterns between 1.8 and 1.9 MaThe Atlantic‐Pacific difference in this portion of the 41‐Kyr world may be caused by regional sensitivity to relatively strong precessionRegional benthic δ18O stacks are preferable to global stacks for stratigraphic alignment [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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