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Sackett is located at 28.63°N and 89.56°W, about 12 miles east of the Mississippi Canyon. The bank is nearly circular and covers an area of 7.07 square km. It is a shelf-edge topographic feature capped by carbonate sediments, which include sand, debris, algal nodules, rock ledges and drowned coral reefs. Turbidity conditions induced by the outflow of the Mississippi River has severely retarded carbonate productivity at Sackett Bank. It is however a relatively stable bank since most of the faults do not displace the seafloor. The biotic community includes coralline algal nodules, coralline algal reef patches, sponges and other invertebrates and some reef species.
Location on Continental Shelf: Outer-Shelf Bank
Coordinates: 28.63° N 89.56° W
Nearest Largest City: New Orleans, Louisiana, USA
Area of Coverage: 7 km2
Minimum Depth: 63 m
Maximum Depth: 100 m
Biotic communities at Sackett Bank, although composed of species found commonly on other shelf edge banks in the northwestern Gulf, are less diverse and less abundant than are those on other banks. The epibenthic biota seems to occupy the position somewhere between those of the South Texas fishing banks (such as Southern Bank and South Baker Bank) and those of other shelf edge carbonate banks in the northwestern Gulf of Mexico (such as the Flower Gardens). Living coralline algal populations are more substantial than those found on the South Banks but are much less developed than those of most other shelf edge banks. Drowned reef patches are quite large, up to 3m high and 12 m across. The primary invertebrates clinging to or encrusting the drowned reefs are comatulid crinoids, encrusting sponges, the saucer-shaped agariciid and small patches of coralline algae. Fish are not particularly abundant on the drowned reefs although various reefs fishes and schools of vermilion Snapper are seen frequently.
Structurally, Sackett Bank is a nearly symmetrical diapir with a non-reflective core and well stratified and faulted upturned beds on its flanks. Its crest is broad and relatively flat at a depth of about 63 m and its base lies at a depth of about 100 m. The substrate of the 67 to 73 m terrace is basically a carbonate rubble-strewn sandy bottom with significant amounts of silt and clay. The mud contents of sediments at Sackett Bank are observed to increase with increasing depth. Two gas seeps are incident in the core of the bank; one on the north side and the other on the south side. The fault patterns on Sackett Bank are mostly oriented in a near east-west direction except for the southwest flank of the bank where they are oriented northwest-southeast. Sackett Bank is observed to have claystone or siltstone at its bottom.
Rezak, R., T.J. Bright and D.W. McGrail. 1985. Reefs and Banks of the Northwestern Gulf of Mexico: their geological, biological, and physical dynamics. Wiley, New York, NY, USA, 259 p.
USGS - Northwestern Gulf of Mexico
Keywords: Coralline algae, Reef patch, Fish, Bank, Gas seep
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