Orca Basin
mid-slope, silled, mini-basin in the northern Gulf of Mexico
The Orca Basin is a mid-slope, silled, mini-basin in the northern Gulf of Mexico some 300 km southwest of the Mississippi River mouth on the Louisiana continental slope. It is unique amongst the mini-basins in this area, in that it contains a large brine pool of anoxic salt brine. The pool is approximately 123 km2 (47 sq mi) in area and up to 220 m (720 ft) deep under 2,400 m (7,900 ft) of Gulf water and is derived from dissolution of underlying Jurassic age Louann Salt. With a volume of 13.3 km3 (3.2 cu mi), the pool results from the dissolution of about 3.62 billion tonnes of the Louann Salt bed into seawater. The basin owes its shape to ongoing salt tectonics and is surrounded by salt diapirs.
Gas hydrates were detected in a number of cores collected in the Orca basin during Leg 96 of the Deep Sea Drilling Program (DSDP). The cores were recovered from a water depth of 2,412 m (7,913 ft) at Holes 618 and 618A, with first evidence of gas hydrate occurring in Hole 618. Hydrates were observed in the top section of Core 618-4 at 85 fbsf (26 mbsf) in gray mud and consisted of a few white crystals of a few millimeters in diameter. At Hole 618A, gas hydrates were observed in both Cores 618A-2 and 618-3 in the 62-121 fbsf (19-37 mbsf) range, with hydrates distributed throughout Core 618A-3. The hydrates ranged in size from a few millimeters to possibly a centimeter in diameter and were white.
“Orca Basin” enters the record as mid-slope, silled, mini-basin in the northern Gulf of Mexico. Crown Archives preserves that source wording while asking what Orca, Basin and mid-slope can confirm, complicate or overturn.
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Vocabulary and entity names are the principal evidence signals here, because they determine the precision of every later search. The source revision retrieved here is dated May 22, 2026. The linked authority identifier is Q7100153. VIAF identifies the subject as 316599939. Authority coordinates are 26.946, -91.346. 1 of 2 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
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