Bulletin Article

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Although the linkages among surface sediments, geomorphic forms, and hydrodynamics in Holocene ooid tidal sand shoals have been evaluated recently, how these factors are reflected in the geomorphic evolution and stratigraphic record of shoals is less constrained. Yet, such understanding is essential to developing meaningful predictive conceptual models of three-dimensional architecture of ancient reservoir analogs. Integrating remote-sensing imagery, high-frequency seismic data, and core characterization from Lily Bank, a modern tidally dominated Bahamian ooid shoal in which sedimentologic processes are well documented, reveals the stratigraphic record of geomorphic change. An irregular, gently dipping rocky surface (interpreted as the top Pleistocene) with no pronounced topographic high underlies the Holocene oolitic succession. A 6-m (20-ft)–thick poorly sorted, gravelly muddy sand with few ooids overlies this basal surface. This lower interval is overlain by sand with an upward increase in proportion of ooids, sorting, and grain size. The uppermost unit, present only under active bar forms, is well-sorted oolitic medium sand with accretionary foresets. Sediments vary stratigraphically and geomorphically; the lower unit is finer and less well sorted than the upper units, and in the oolitic upper unit, sediment size and sorting on bar crests are distinct from bar flanks. Collectively, these results suggest that a marked antecedent bump is not necessary for occurrence of ooid shoals and that the stratigraphic record of analogous ooid shoal systems may preserve clues of geomorphic position, as well as geobody size and orientation.

Explorer Article

2391
 
Explorer Article

AAPG’s prestigious Distinguished Lecturer program, which offers audiences a chance to hear the latest in geoscience research, understanding and practical applications, kicks-off its new season with three speaking tours planned for September.

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Explorer Emphasis

2629
 
Explorer Emphasis Article

Major 'Caribbean plate' survey by Moscow-based consortium 'Geology Without Limits' to commence soon, will bring together leading scientists from around the world.

Explorer Geophysical Corner

10214
 
Explorer Geophysical Corner

Steeply dipping bedforms and bed sets often develop where sediment accumulates and migrates, and are expressed as clinoform patterns on seismic data. Ground-penetrating radar (GPR) provides ultra-high-resolution images of the internal structure of these sediment accumulations.

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