Abstract: Nannofacies: A New Tool In Environmental Interpretations

Isbelia Duran

In the present work, five new associations are defined on the basis not only of nannofloral characteristics, but also of the other components present in the residues.

The residues usually contain organic matter remains and mineral material. The criteria used to define and recognize the proposed associations are the composition and texture (mainly grain size, sorting and preservation) of these materials.

Associations I and II correspond to coastal and fluviomarine environments, being generally characterized by absence of planktonic organisms (nannoplankton and foraminifera), occasional occurrence of remains from benthic organisms, abundant organic matter and abundant detritic pyrite. Associations III, IV, and V represent marine environments (hemipelagic with continental influx, hemipelagic and pelagic, respectively), and are characterized by varying percentages of the different planktonic organisms, presence of organic matter, and occurrence of minerals like glauconite and authigenic pyrite.

These associations allow improving considerably the quality and the spectrum of information supplied by the nannoplanktologist to the interpretation groups, and constitutes a new, very useful tool for environmental interpretations.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela