Deep-Water
Turbidites and Their Equally Important Shallower Water Cousins
Mutti, Emiliano1, Roberto
Tinterri1, Pierre Muzzi Magalhaes2, Gustavo Basta2
(1) University of Parma, Parma, Italy (2) Petrobras S.A, Rio de Janeiro, Brazil
Most modern turbidite systems form at
depths in excess of a thousand meters and similarly deep-water settings are
generally inferred from exposed or buried ancient systems. These systems are
characteristically made up of a variety of facies deposited by sediment gravity
flows. Sharp-based, graded sandstone beds alternating with generally thinner
mudstone units are probably the most typical deposit of such systems.
Growing evidence shows that almost
identical deposits are equally common and stratigraphically important in
shallower water settings of exposed ancient basin fills. Such sediments, most
of which have long been unfortunately mistaken for storm deposits because of
the common occurrence of HCS or have been assigned a deeper water turbidite
origin, are the most genuine expression of deltaic systems dominated by rivers
in flood and therefore by hyperpycnal flows. These sand-rich depositional
elements commonly grade basinward into thick, delta-slope, mudstone-dominated
successions. The correct recognition of the origin and environment of these
deposits, which is crucial for differentiating flood-dominated deltaic systems
from basinal turbidite systems, can only be accomplished through careful
geological mapping, stratigraphic correlations. and
facies analyses in both the surface and subsurface.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California