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| Titel |
Precessional and half-precessional climate forcing of Mid-Devonian monsoon-like dynamics |
| VerfasserIn |
D. Vleeschouwer, A. C. Silva, F. Boulvain, M. Crucifix, P. Claeys |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 8, no. 1 ; Nr. 8, no. 1 (2012-02-27), S.337-351 |
| Datensatznummer |
250005377
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| Publikation (Nr.) |
 copernicus.org/cp-8-337-2012.pdf |
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| Zusammenfassung |
| A Devonian magnetic susceptibility (MS) record obtained on limestones
ranging from the Uppermost-Eifelian to the Lower-Givetian and located on the
southern border of the Dinant Synclinorium in Belgium was selected for
time-series analysis. In these carbonate ramp and platform deposits,
spectral analyses highlight persistent, high-frequency cycles in both the
MS-signal and the microfacies curve, reflecting environmental and climate
changes. These metre-scale variations in the MS-signal are interpreted as
changes in the flux of magnetic minerals towards the marine system, most
likely controlled by monsoon rainfall-intensity. By combining chrono- and
biostratigraphic information with theoretical knowledge of sedimentation
rates in different depositional environments, these cycles are interpreted
as astronomically driven and dominated by precession. It is hypothesized
that during precession minima (longitude of the perihelion ≈270°) the trans-equatorial pressure gradient reaches a maximum and intensifies
the northeasterly monsoonal circulation. The consequent increase in moisture
transport towards the continent leads to enhanced precipitation and runoff,
which, in turn, induces a higher flux of detrital material – including magnetic
minerals responsible for the MS-signal – towards the marine system. Moreover,
this unique high-resolution climate signal reveals half-precessional cycles.
These cycles suggest that during precession maxima (longitude of the
perihelion ≈90°) southeasterly monsoonal circulation
strengthened due to an increased inter-hemispheric pressure gradient. |
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