Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by John, C. M. Articles by Adatte, T. Search for Related Content GeoRef GeoRef Citation

Mixed carbonate-siliciclastic record on the North African margin (Malta)—coupling of weathering processes and mid Miocene climate

Cédric M. John^,1, Maria Mutti^,1 and Thierry Adatte^,2

¹ Institut für Geologie und Paläontologie, University of Stuttgart, D-70174 Stuttgart, Germany
² Institut de Géologie, Université de Neuchâtel, CH-2007 Neuchâtel, Switzerland

We investigated rock outcrops spanning the middle Miocene, global climate-cooling step on the Maltese Islands in order to reconstruct continental weathering rates and terrigenous fluxes, as well as to explore the coupling between these later, regional climate and carbonate accumulations. Sedimentation at this location was dominated during the Oligocene and early Miocene by a transitional platform to slope carbonates but progressively switched to a clay-rich carbonate slope system in the middle Miocene. Around 13 Ma, an abrupt change toward clay-dominated marls occurred, and marl deposition persisted until the Tortonian (ca. 12 Ma), when a shallow-water carbonate ramp was reestablished. Clay mineralogy and bulk-rock oxygen isotope analyses suggest that the deposition of the Blue Clay formation was mainly caused by global climate change and related change in the rate of continental weathering.

A significant negative correlation (R² = 0.65) exists between the carbonate content and the ¹⁸O record. This, combined with the variation of mass accumulation rate of terrigenous material, suggests that shorter-term periods of globally cooler climate (Mi events) were associated with higher rates of accumulation in continental-derived material. Since during the Miocene Malta was attached to the North African Margin, we propose that the observed trends were due to a regional increase in rainfall during cooler periods, which consequently increased continental weathering and runoff. We further suggest that this pattern was linked to the perturbation of atmospheric fronts due to an increased thermal gradient during the Miocene. Thus, regional increase in rainfall might have been linked to the northward migration of the Intertropical Convergence Zone (ITCZ).

Key Words: Miocene • climate • weathering • clay mineralogy • continental margin • Malta

This article has been cited by other articles:

				S. Kender, V.L. Peck, R.W. Jones, and M.A. Kaminski Middle Miocene oxygen minimum zone expansion offshore West Africa: Evidence for global cooling precursor events Geology, August 1, 2009; 37(8): 699 - 702. [Abstract] [Full Text] [PDF]

				P.A. Gatt, J. Cassar, and A.J. Vella Discussion of 'Methodology to identify badly weathering limestone using geochemistry: case study on theLower Globigerina Limestone of the Maltese Islands' byJ. Cassar & A.J. Vella Quarterly Journal of Engineering Geology and Hydrogeology, 36, 85-96 Quarterly Journal of Engineering Geology and Hydrogeology, May 1, 2007; 40(2): 187 - 192. [Full Text] [PDF]

				A. C. Knoerich and M. Mutti Missing Aragonitic Biota and the Diagenetic Evolution of Heterozoan Carbonates: A Case Study from the Oligo-Miocene of the Central Mediterranean Journal of Sedimentary Research, May 1, 2006; 76(5): 871 - 888. [Abstract] [Full Text] [PDF]

				M. Mutti, C. M. John, and A. C. Knoerich Chemostratigraphy in Miocene heterozoan carbonate settings: applications, limitations and perspectives Geological Society, London, Special Publications, January 1, 2006; 255(1): 307 - 322. [Abstract] [PDF]

				J. Halfar and M. Mutti Global dominance of coralline red-algal facies: A response to Miocene oceanographic events Geology, June 1, 2005; 33(6): 481 - 484. [Abstract] [Full Text] [PDF]

				K. B. Follmi, C. Badertscher, E. de Kaenel, P. Stille, C. M. John, T. Adatte, and P. Steinmann Phosphogenesis and organic-carbon preservation in the Miocene Monterey Formation at Naples Beach, California--The Monterey hypothesis revisited Geological Society of America Bulletin, May 1, 2005; 117(5-6): 589 - 619. [Abstract] [Full Text] [PDF]

				J. R. Price, M. A. Velbel, and L. C. Patino Rates and time scales of clay-mineral formation by weathering in saprolitic regoliths of the southern Appalachians from geochemical mass balance Geological Society of America Bulletin, May 1, 2005; 117(5-6): 783 - 794. [Abstract] [Full Text] [PDF]

				C. M. John and M. Mutti Relative Control of Paleoceanography, Climate, and Eustasy over Heterozoan Carbonates: A Perspective from Slope Sediments of the Marion Plateau (ODP LEG 194) Journal of Sedimentary Research, March 1, 2005; 75(2): 216 - 230. [Abstract] [Full Text] [PDF]