期刊
PALEOCEANOGRAPHY
卷 30, 期 2, 页码 133-149出版社
AMER GEOPHYSICAL UNION
DOI: 10.1002/2014PA002736
关键词
Cretaceous; carbon cycle; Milankovitch forcing; carbon isotopes; greenhouse; paleoclimate
资金
- Ministry of Education [LH12041]
- Czech Science Foundation [P210/10/1991]
- Academy of Sciences of the Czech Republic [RVO67985530]
- UK Natural Environment Research Council (NERC) [NE/H020756/1]
- NSF [EAR-0959108]
- Natural Environment Research Council [NE/H020756/1] Funding Source: researchfish
- NERC [NE/H020756/1] Funding Source: UKRI
Carbon sources and sinks are key components of the climate feedback system, yet their response to external forcing remains poorly constrained, particularly for past greenhouse climates. Carbon-isotope data indicate systematic, million-year-scale transfers of carbon between surface reservoirs during and immediately after the Late Cretaceous thermal maximum (peaking in the Cenomanian-Turonian, circa 97-91 million years, Myr, ago). Here we calibrate Albian to Campanian (108-72 Myr ago) high-resolution carbon isotope records with a refined chronology and demonstrate how net transfers between reservoirs are plausibly controlled by similar to 1 Myr changes in the amplitude of axial obliquity. The amplitude-modulating terms are absent from the frequency domain representation of insolation series and require a nonlinear, cumulative mechanism to become expressed in power spectra of isotope time series. Mass balance modeling suggests that the residence time of carbon in the ocean-atmosphere system isby itselfinsufficient to explain the Myr-scale variability. It is proposed that the astronomical control was imparted by a transient storage of organic matter or methane in quasi-stable reservoirs (wetlands, soils, marginal zones of marine euxinic strata, and potentially permafrost) that responded nonlinearly to obliquity-driven changes in high-latitude insolation and/or meridional insolation gradients. While these reservoirs are probably underrepresented in the geological record due to their quasi-stable character, they might have provided an important control on the dynamics and stability of the greenhouse climate.
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