Early Miocene intensification of the North African hydrological cycle: Multi‐proxy evidence from the shelf carbonates of Malta.

Zammit, R., Lear, C.H., Samankassou, E., Lourens, L.J., Micallef, Aaron , Pearson, P.N. and Bialik, O.M. (In Press / Accepted) Early Miocene intensification of the North African hydrological cycle: Multi‐proxy evidence from the shelf carbonates of Malta. Open Access Paleoceanography and Paleoclimatology . Art.Nr. e2022PA004414. DOI 10.1029/2022PA004414.

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Abstract

During the Miocene (23.0 to 5.3 Ma) North Africa experienced both humid and arid intervals, but the underlying cause of these transitions is unknown. Earth’s climate was characterised by a unipolar icehouse with a dynamic Antarctic ice sheet, which may have influenced regional hydrology through atmospheric teleconnections. However, the Miocene also witnessed the restriction of the Mesopotamian Seaway, which may have had significant climatic impacts. The Maltese il-Blata section (Central Mediterranean) comprises Late Oligocene to Early Miocene marine deposits previously used to constrain the timing of the Mesopotamian Seaway restriction using the εNd tracer. The location of this section also makes it sensitive to climatic changes in the North African region, and biogeochemical changes in the central Mediterranean. Here, we present lithological and geochemical records of the il-Blata section. We find a marked shift in lithology and an increase in sedimentation rate coeval with the Early Miocene (∼19 to 20 Ma) restriction of the Mesopotamian Seaway. Concomitant changes in bulk sediment CaCO3, Sr/Ca, K/Al, Ti/Al, Zr/Al, and Si/Ti support a major humid climate transition and associated intensification of river systems over western North Africa. We propose that these changes in North African hydroclimate reflect either a tipping point effect in a gradually warming global climate, or are the result of the initial restriction of the Mesopotamian Seaway, perhaps through consequent changes in Atlantic Meridional Overturning Circulation and the West African Monsoon. We also suggest the restriction of the Mesopotamian Seaway inhibited phosphorite deposition at low latitudes.

Key Points

- The climate over the central Mediterranean shifted from a cool-arid to a humid regime during the Early Miocene around 19.0 Ma

- The transition to more humid conditions may have been a consequence of the first Miocene restriction of the Mesopotamian Seaway (MSR-1)

- Circulation changes in the proto-Mediterranean coupled with changes in the sedimentation may have terminated regional phosphorite episodes

Document Type: Article
Keywords: Aquitanian-Burdigalian transition, Tethys Seaway, Globigerina Limestone Formation, Mediterranean, West African Monsoon, Maltese Islands
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-GDY Marine Geodynamics
Main POF Topic: PT3: Restless Earth
Refereed: Yes
Open Access Journal?: No
Publisher: AGU (American Geophysical Union), Wiley
Date Deposited: 20 Sep 2022 12:19
Last Modified: 21 Sep 2022 07:03
URI: https://oceanrep.geomar.de/id/eprint/57047

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