--> ABSTRACT: Sandy-Body Types in the Tide-dominated Fly River Delta, PNG, by R. W. Dalrymple, E. K. Baker, M. Hughes, and P. T. Harris; #91021 (2010)

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Sandy-Body Types in the Tide-dominated Fly River Delta, PNG

DALRYMPLE, R. W.,  E. K. BAKER, M. HUGHES,  and P. T. HARRIS

Tide-dominated deltaic systems have been inferred to exist in a number of Cretaceous units in the western U.S. and Canada, including the Clearwater Fm. (Alberta), the Sego Sst. (Utah), and even the Shannon Sst. (Wyoming). The tide-dominated Fly River (spring tidal range 3.6-5 m), Papua New Guinea, provides a possible analogue, although it appears to be muddier than any of the Cretaceous examples. Four sand facies are recognized. 1) Channel-floor sands of the tidal-fluvial transition (landward of the delta plain) lack mud drapes but contain abundant mud clasts, derived from adjacent channel-bank facies. 2) Current-parallel, elongate bars in the distributary channels contain rhythmically interlaminated, rippled sands and massive muds. These deposits exhibit an upward-coarsening - upward-lining trend, due to the preferential formation of fluid muds in the bottom of the channels. A lateral-accretion architecture predominates. 3) Erosion occurs on the floor of channels abandoned due to delta switching and on the outside of channel bends. The sands concentrated in these areas lack mud layers, but contain abundant mud pebbles in association with cross bedding. 4) The elongate (coast-normal), distributary-mouth bars consist of clean, well sorted sand containing cross bedding and HCS. Mud layers are rare, due to mud resuspension by waves. Their deposits commonly rest on an erosion surface and fine upward overall, because of lateral migration of the bars. Overall, the tidal-fluvial and DMB sands probably form the best reservoirs. 

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.