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| Titel |
Carbon cycles in Late Cretaceous time |
| VerfasserIn |
M. Sprovieri, N. Sabatino, N. Pelosi, S. Batenburg, R. Coccioni, M. Iavarone, S. Mazzola |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250066295
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| Zusammenfassung |
| A refined astronomical tuning of the upper Albian-lower Campanian record is proposed from
the Tethyan pelagic sedimentary sequence of the Bottaccione reference section
(Umbria-Marche Basin, central Italy). Long-term eccentricity cycles filtered from a new
high-resolution bulk sample δ13C signal were tuned to the highly stable 405 kyr cycles of the
insolation target curve. Application of integrated methodologies of non-stationary/non-linear
signals analysis (Intrinsic Mode Functions, WWZ Wavelet, non-linear filtering techniques,
etc.) provided reliable numerical tools to explore the highly complex ~23 Myr long record.
Exploration of the hierarchical pattern organization of lithology in selected parts of
the sedimentary record provided an important constrain for the tuning strategy.
The proposed orbital tuning provides a new and accurate age model for dating
biostratigraphic, magnetic and carbon isotope events. Moreover, the exploration of
long-term cycles (~1.2 to ~7.1 Myr) in the δ13C signal throughout the entire record
offers an unprecedented chance to investigate processes associated to global carbon
cycle dynamics and response to orbital forcing, biogeochemical cycles and sea
level changes. Long-term eccentricity cycles of ~2.5 Myr beat the ~23 Myr long
record although a direct control of this long–term eccentricity component on the
deposition of sediments identified throughout the succession and coeval to the Bonarelli
and mid-Cenomanian anoxic events can be unequivocally excluded. During the
Turonian-Coniacian stratigraphic intervals, cycles of 1.2 Myr primarily modulate the δ13C
curve , fuelling the debate on the potential role of glacio-eustacy on the carbon cycle during
short-intervals of this super-greenhouse period. Finally, cycles of ~7.1, 4.5 and
3.2 Myr modulate the entire δ13C record and represent primary very long-term
oscillation modes of Earth’s climate-ocean system. Although an ultimate driver
of these long-term periodicities is lacking we speculate that the 4.5 and 2.5 Myr
cycles documented in the Late Cretaceous represent homologues of the present
eccentricity grand cycles evolved by chaotic behaviour of solar planets during the
Mesozoic. They could represent appropriate system low-frequency means for geological
correlation and robust constraints on the orbital evolution of the Solar System. |
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