--> Sequence Stratigraphy and Magnetostratigraphy of an Upper Miocene Shallow-Marine to Continental Sedimentary Succession, Northeastern Morocco: Correlation to Mediterranean and Global Events, by K. J. Cunningham, E. K. Franseen, P. Enos, M. R. Farr, and K. Rakic-El Bied; #90986 (1994).

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Abstract: Sequence Stratigraphy and Magnetostratigraphy of an Upper Miocene Shallow-Marine to Continental Sedimentary Succession, Northeastern Morocco: Correlation to Mediterranean and Global Events

Kevin J. Cunningham, Evan K. Franseen, Paul Enos, M.R. Farr, Kruna Rakic-El Bied

A precise high-resolution sequence stratigraphy and magnetostratigraphy has been developed for an upper Miocene carbonate complex in the Melilla Basin, which evolved from a basal bioclastic carbonate ramp to a prograding bioclastic carbonate platform to a prograding fringing-reef complex to a topography-draping sequence composed of grainstones, reefs, and stromatolites (Terminal Carbonate Complex or TCC). Three different scales of depositional sequences that developed within the carbonate complex indicate a complex relative sea-level history. A subaerial unconformity separates the TCC from an overlying upper Miocene mixed carbonate/siliciclastic complex that reflects transition from marine to continental deposition.

The magnetic-reversal stratigraphy is correlated to the geomagnetic polarity time scale with the aide of 40Ar/39Ar dating of volcanic ashes interbedded within the carbonate complex and with foraminifera in basinal strata. The bioclastic carbonate ramp and platform developed in open-marine conditions during Tortonian time. Transition from the bioclastic carbonate platform to fringing reef complex corresponds to a global carbon isotope shift at the Tortonian/Messinian boundary. The TCC was deposited after closure of the Mediterranean, probably during deposition of the Lower Evaporite. The unconformity separating the TCC from the mixed carbonate/siliciclastic complex probably corresponds to intra-Messinian desiccation punctuating the Lower and Upper Evaporites. The ixed carbonate/siliciclastic complex was deposited during the lower reversal of the Gilbert Chron and probably corresponds to Upper Evaporite and Lago Mare episodes.

This new high-resolution stratigraphic framework is providing precise correlations to other areas and new insights on the role of local, regional, and global controls on carbonate sequence development.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994