--> Abstract: 50 Years Of The Turbidite Paradigm (1948-1998): Deep-Water Processes And Facies Models -- A Critical Perspective, by G. Shanmugam; #90928 (1999).

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SHANMUGAM, G.
Mobil Technology Company, Dallas, TX

Abstract: 50 Years of the Turbidite Paradigm (1948-1998): Deep-Water Processes and Facies Models -- A Critical Perspective

The International Geological Congress (Great Britain) in 1948, when the origins of graded bedding and submarine canyons were discussed, may be considered to mark the advent of the turbidite paradigm. The 50s, 60s, and 70s were periods of model building; however, a major crisis on the meaning of turbidity current started as early as 1965. In the 80s, fundamental questions were raised regarding the Bouma Sequence, fan models, and turbidite facies scheme. Furthermore, results of COMFAN I revealed the complexity of modern and ancient fan systems. The 90s are a period of abandonment of fan models, reinterpretation of deep-water massive sands, debate over high-density turbidity currents, and experiments on sandy debris flows.

If existing three turbidite models (e.g., the Bouma Sequence, the Lowe Sequence, the Stow-Shanmugam Sequence) are meaningful, then a complete turbidite bed should contain a total of 16 divisions. However, no one has ever documented such a complete turbidite bed. The plethoric family of "traction carpets" has proliferated into nine models (e.g., flowing-grain layers, inertia-flow layer, laminar sheared layer, fluidized flowing grain layer, avalanching flow etc.). In spite of this multiplicity of models, many fundamental problems still remain. Submarine fan models with turbidite channels and lobes have controlled our thinking for nearly 35 years, but many of us now realize that these fan models are obsolete. Recent abandonment of suprafan lobe concept has left the popular sequence stratigraphic fan models with mounded seismic geometry with a shaky foundation.

In the 21st century, a paradigm shift is in order. This shift will involve emerging of a new paradigm that will be more inclusive in terms of slope processes (i.e., mass movements and bottom currents) and products than just basinal turbidity currents and fan models. Science is a journey, whereas facies models are the final destination.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas