Posamentier, Henry W.1, Roger Walker2
(1) Anadarko Canada Corporation, Calgary, AB
(2) Roger Walker Consulting Inc, Calgary, AB
ABSTRACT: Turbidite Facies Models; Integrating Subsurface and Outcrop
Deep-water depositional environments are characterized by a vast array of facies. To simplify and model this inherent complexity, we propose four depositional elements, each characterized by distinct 3D seismic expression and lithofacies. These elements are 1) channels, 2) levees, 3) frontal splays or lobes, and 4) debris flow lobes, sheets, and channel fills.
Channels range from straight to meandering, and from deeply incised and minimally aggradational to minimally incised and highly aggradational. Channel fills are commonly dominated by amalgamated turbidite deposits of Ta and Tb facies. Sand body geometries commonly reflect the lateral expansion and downstream migration of meander loops associated with moderate to high-sinuosity channels.
Levee deposits tend to thin-down system due to progressive loss of the fine-grained component from the turbidity flow because of continual spillover from channel onto overbank. Levee deposits tend to be thicker and sandier at outer channel bends with thin-bedded turbidite sandstone beds commonly dominated by Tb and Tc facies.
Frontal splays or lobes develop at gradient breaks or on basin floors where levee heights have decreased below a critical height. These features commonly are characterized by shallow (<3-5 m deep) distributary to braided channel networks. Frontal splay deposits are characterized by sheet-bedded sandstones dominated by Ta and Tb facies and can achieve thicknesses >100 m.
Debris flow deposits can take the form of sheets, lobes, and highly-erosive channel fills. Amalgamated debrites can achieve thicknesses >300 m. Debrites commonly are poorly sorted with no significant ordered fabric.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.