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==Barrier Islands==

==Barrier Islands==

Barrier islands form thick, well-sorted sand bodies with a tabular geometry ([[Figure 192]]). They typically comprise a composite of beach, dune, and upper shoreface sandstones (Galloway, 1986). Barrier islands can be continuous for tens of kilometers along strike but may only be a few kilometers wide. Local heterogeneity can be provided by tidal channel inlet deposits. These form crosscutting lenticular pods, disrupting the layer-cake continuity of the barrier island body. Recent barrier island sediments on the South Carolina coast provide a modern analog and are described in detail by Sexton and Hayes (1996).

[[File:M91FG192.JPG|thumb|300px|{{figure number|7}}Generalized map and cross sections showing major environments and facies associations of a barrier island-lagoonal system (from McCubbin, 1982). Reprinted with permission from the AAPG.]]

[[File:M91FG192.JPG|thumb|300px|192. Generalized map and cross sections showing major environments and facies associations of a barrier island-lagoonal system (from McCubbin, 1982). Reprinted with permission from the AAPG.]]

Barrier islands form thick, well-sorted sand bodies with a tabular geometry ([[:File:M91FG192.JPG|Figure 7]]). They typically comprise a composite of beach, dune, and upper shoreface sandstones (Galloway, 1986). Barrier islands can be continuous for tens of kilometers along strike but may only be a few kilometers wide. Local heterogeneity can be provided by tidal channel inlet deposits. These form crosscutting lenticular pods, disrupting the layer-cake continuity of the barrier island body. Recent barrier island sediments on the South Carolina coast provide a modern analog and are described in detail by Sexton and Hayes (1996).

Ambrose et al. (1997) gave an example from an oil field in Venezuela where sweep has resulted from preferential water encroachment along the sandstone-rich core of the barrier island depositional axis with bypassed oil remaining along the landward pinch-out edge.

Ambrose et al. (1997) gave an example from an oil field in Venezuela where sweep has resulted from preferential water encroachment along the sandstone-rich core of the barrier island depositional axis with bypassed oil remaining along the landward pinch-out edge.