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Multiple Spill-Points and Inherited Structural Controls from Lacustrine Carbonates: the MayráN Basin, Late Neogene, Northeast Mexico

Amezcua, Natalia 1; Gawthorpe, Rob 1; Macquaker, Joe 2
1 Basin Studies and Petroleum Geoscience, University of Manchester, Manchester, United Kingdom.
2 Department of Earth Sciences, Memorial University of Newfoundland, St. John's, NF, Canada.

The Mayrán Basin in northeast Mexico is a late Neogene carbonate-dominated lacustrine basin, composed of a series of down-stepping, terrace-like sub-basins. The undeformed Mayrán sedimentary successions overlie with angular unconformity on Late Cretaceous rocks that were folded and faulted during Laramide-age deformation in the Palaeogene.

The down-stepping pattern of the Mayrán basin fill is related to a northward descent in structural level of the Laramide-age folds, creating sub-basins at different elevations. The sub-basins depocentres were restricted from east to west by the double plunging character of the major Laramide-age folds. While the larger folds controlled the main sub-basin development, the internal complexity of the folds also exerts a control on facies variability and may further compartmentalise the sub-basins. The sub-basins pattern also act as a siliciclastic filter from south to north. The southern most basin, closest to the source of siliciclastic sediment contain a range of alluvial deposits, whereas the more distal sub-basins in the north are carbonate dominated.

During relative lake-level highstand sub-basins were connected through multiple spill-points, with two styles of deposition related to relative potential accommodation and lake level across adjacent depocentres: i) prograding carbonate (tufa) clinoforms, and ii) parallel stratified lacustrine carbonate. Episodes of relative lake-level lowstand resulted in sub-basin isolation, and are recorded by gypsum bearing facies and subaereal exposure surfaces, reflecting major changes in the hydrological balance of the basin. Periods of abrupt lake expansion are well represented by flooding surfaces.

The inherited structural and geomorphic evolution of the Cretaceous bedrock were important controls on the establishment and geometry of the Mayrán Basin. Major controls for basin fill and stratigraphic architecture were driven by autochthonous factors (as carbonate sediment production), while climate is considered to be the main allochthonous control.


AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009