--> Albian to Maastrichtian Sequence Stratigraphy of Central Colombia: Implications for Eustasy and Tectonics in an Evolving Continental Margin, by T. Villamil; #90986 (1994).

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Abstract: Albian to Maastrichtian Sequence Stratigraphy of Central Colombia: Implications for Eustasy and Tectonics in an Evolving Continental Margin

Tomas Villamil

Several detailed stratigraphic sections of the Colombian Cretaceous were correlated using a high-resolution chronostratigraphic framework. Facies interpretations were combined with chemostratigraphy, biofacies analyses and relative accommodation space plots to produce a three-dimensional sequence stratigraphic model. The sequence stratigraphic hypothesis was interpreted in terms of relative sea level and as the result of the interaction of variations in sediment supply, tectonics and eustasy. The tectonic component was "filtered" using new tectonic models of Pindell (in press and this session). The variations in sedimentation rate were assessed by only considering sequence boundaries and flooding surfaces that could be correlated between

all sections. The Colombian margin was almost passive from the lower Albian to the Campanian with only the gradual eastward migration of the peripheral bulge of the Proto-Caribbean Plate affecting accommodation space. Campanian-Present subduction and terrane accretion overwhelmed eustasy in relative sea level behavior.

Four sequence boundaries were observed regionally from the lower Albian to the Santonian and more than four in the Santonian to Campanian. An Early and a late Cenomanian sequence boundary as well as a late Coniacian-Santonian boundary can be traced all over Colombia, these are believed to be eustatic in origin, the others probably tectonic, eustatic or a combination. High-frequency sequences were not detected in the Colombian Cretaceous; parasequences, however, appear to be responding to a Milankovitch-type cyclical influence.

The pitfalls of the study lie on the depositional setting--distal offshore facies--and on the difficulty on interpreting facies in an extremely high paleo-upwelling regime.

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