Time of accumulation of hypersaline anoxic brine in Orca basin (Gulf of Mexico)

Addy, Sunit K.; Behrens, E. William

doi:10.1016/0025-3227(80)90104-8

Cited by 67 publications

(32 citation statements)

References 4 publications

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“…Multiple studies of the sediments underlying Orca Basin have converged on a 7900 to 8500 yr timescale for the establishment of anoxic, hypersaline conditions in the basin (Addy and Behrens, 1980;Leventer et al, 1983;Meckler et al, 2008). For this study, we compared our radiocarbon values with the most recent foram record reported by Meckler et al (2008) because it includes a foraminiferal radiocarbon date in close proximity to the black-gray sediment transition depth and because radiocarbon analysis of individual foraminiferal species has confirmed stratigraphic continuity in this location (Flower et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…This transition, reported in both slope sediments and in deeper basin sediments (Addy and Behrens, 1980;Leventer et al, 1983;Meckler et al, 2008;Northam et al, 1981) has been dated by three methods: radiocarbon analysis of total carbonate (Addy and Behrens, 1980); radiocarbon analysis of foraminifera (Leventer et al, 1983;Meckler et al, 2008); and biostratigraphy (Leventer et al, 1983), yielding similar ages of approximately 7900 to 8500 calendar years for Orca Basin brine.…”

Section: S R Shah Et Al: Carbon Isotopic Evidence For Microbial Comentioning

confidence: 96%

“…Below 2240 m depth, the basin is occupied by an anoxic, hypersaline brine. Both the geochemistry of the brine and composition of underlying sediments indicate the ∼ 200 m thick brine originates from dissolution of a nearby salt exposure and lateral advection of brine to the basin (Addy and Behrens, 1980;Pilcher and Blumstein, 2007;Sheu et al, 1988;Shokes et al, 1977;Trabant and Presley, 1978). This formation mechanism is unlike many other Gulf of Mexico brines that have in situ sources of dissolved ions and reduced gases (Joye et al, 2005(Joye et al, , 2009(Joye et al, , 2010.…”

Section: Introductionmentioning

confidence: 99%

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Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the seawater–brine interface

et al. 2013

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Orca Basin, an intraslope basin on the Texas-Louisiana continental slope, hosts a hypersaline, anoxic brine in its lowermost 200 m in which limited microbial activity has been reported. This brine contains a large reservoir of reduced and aged carbon, and appears to be stable at decadal time scales: concentrations and isotopic composition of dissolved inorganic (DIC) and organic carbon (DOC) are similar to measurements made in the 1970s. Both DIC and DOC are more "aged" within the brine pool than in overlying water, and the isotopic contrast between brine carbon and seawater carbon is much greater for DIC than DOC. While the stable carbon isotopic composition of brine DIC points towards a combination of methane and organic carbon remineralization as its source, radiocarbon and box model results point to the brine interface as the major source region for DIC, allowing for only limited oxidation of methane diffusing upwards from sediments. This conclusion is consistent with previous studies that identify the seawater–brine interface as the focus of microbial activity associated with Orca Basin brine. Isotopic similarities between DIC and DOC suggest a different relationship between these two carbon reservoirs than is typically observed in deep ocean basins. Radiocarbon values implicate the seawater–brine interface region as the likely source region for DOC to the brine as well as DIC

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Section: Discussionmentioning

confidence: 99%

Section: S R Shah Et Al: Carbon Isotopic Evidence For Microbial Comentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Carbon isotopic evidence for microbial control of carbon supply to Orca Basin at the seawater–brine interface

et al. 2013

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“…The only studied example of an interdomal basin is Orca Basin (Shokes et al, 1977;Sackett, et al, 1977Sackett, et al, , 1979Trefry and Presley, 1977;Trabant and Presley, 1978;McKee et al, 1978;Wiesenburg et al, 1979;Addy and Behrens, 1980;Bouma et al, 1980;Bouma, 1982;Feeley, 1982). Orca Basin was drilled during Leg 96 (Site 618) to collect data to test the many inferences implied from these diverse studies.…”

Section: Interdomal Intraslope Basinsmentioning

confidence: 99%

“…Addy and Behrens (1980) carbon dated the black/gray contact in a piston core at 7910 ± 170 yr. old, indicating that brine introduction started at that time. It is likely that brine was introduced several times.…”

Section: Basin Evolution During the Late Wisconsinmentioning

confidence: 99%

Seismic Stratigraphy and Sedimentary Processes in Orca and Pigmy Basins

Bouma¹,

Stelting²

1986

Initial Reports of the Deep Sea Drilling Project

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The diapirically controlled continental slope off Louisiana shows an irregular bathymetry consisting of diapiric highs and intraslope basins. Two types of basins were drilled during Leg 96. Site 619 is located in Pigmy Basin, which is an example of a blocked-canyon intraslope basin. Air-gun records show a basin fill characterized by several sets of cyclic seismic sequences. These are from bottom to top: a semitransparent zone (sandy turbidites?) often with chaotic reflectors (slumps?), overlain by slightly discontinuous, parallel reflectors (muddy turbidites?), and topped by distinct continuous reflectors (hemipelagic and pelagic deposits?). Similar, but thinner, sequences can be observed on higher frequency records. The cores indicate that lithologic variations can be correlated with the seismic characteristics. An angular discontinuity is commonly present between two acoustical sequences. Drilling in Pigmy Basin penetrated the upper two seismic sequences observed on air-gun (80 in.3 ) records. Orca Basin (Site 618), an interdomal basin, is surrounded by diapirs that form a rim preventing bottom-hugging currents from entering. This basin is characterized by a 200-m-thick anoxic brine over the basin floor. The anoxic bottom sediments are underlain by normal gray deposits indicating oxic conditions. Good seismic resolution could not be obtained. It was discovered that a slump mass is located on top of the Holocene sediments. The cores were very gassy, making detailed visual observations impossible.The initial drilling objectives for Site 618 were to core a complete upper Quaternary record for stratigraphic purposes and to study vertical trends in sedimentologic, geotechnical, and geochemical parameters to better understand this type of intraslope basin. Because the objectives could not be met in Orca Basin, the stratigraphic study was conducted in Pigmy Basin and those results were correlated with the sedimentologic studies and the seismic sequences.

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