Interstitial-Water Studies, Deep Sea Drilling Project Sites 415 and 416

Gieskes, Joris M.; Graham, D.; Ellis, Richard C.

doi:10.2973/dsdp.proc.50.133.1980

Cited by 4 publications

(3 citation statements)

References 9 publications

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“…The data in the lower part of the hole, however, suggest that there may be a maximum in chloride between 800-900 m sub-bottom depth. If this observation is correct, then, the profile implies advection or diffusion of chloride through the sediments in a manner similar to that described by Gieskes et al (1980) for Sites 415 and 416, located to the west of the region of diapiric structures (Fig. 1).…”

Section: Site 135mentioning

confidence: 58%

Interstitial Water Studies, Leg 79

Gieskes¹,

Johnston²,

Boehm³

1984

Initial Reports of the Deep Sea Drilling Project

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Interstitial water analyses of samples collected at Sites 544-547 of DSDP Leg 79 are presented. In Site 547 chloride concentrations increase to almost 80% of the halite saturation values. Gypsum occurrences in the sediments immediately overlying the halite deposit can be explained in terms of migration of Ca 2+ and SO^~ from the underlying evaporites. At shallower depths sulfate concentrations decrease rapidly as a result of sulfate reduction processes. The same processes lead to the removal of calcium in the form of calcium carbonate. At Site 547, the chloride concentration depth profile suggests a maximum of dissolved chloride which may be the result of advective flow from nearby (~ 6 km) evaporite salt diapirs.

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Section: Site 135mentioning

confidence: 58%

Interstitial Water Studies, Leg 79

Gieskes¹,

Johnston²,

Boehm³

1984

Initial Reports of the Deep Sea Drilling Project

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“…However, high salinities and chlorinities have been observed in many DSDP sites off the coast of northwestern Africa (Gieskes, 1981) where these high values have been attributed to penetration by saline fluids derived from leaching of underlying evaporites, or the lateral influx of continental ground waters that have previously leached coastal evaporites. Pore waters from Site 415 (Gieskes et al, 1980) display a chlorinity maximum of similar concentration and at a similar depth to that identified at Site 955; low sulfate concentrations at the latter site would imply a halite-dominated source.…”

Section: Chloride and Salinitymentioning

confidence: 72%

Site 955

1995

Proceedings of the Ocean Drilling Program

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Principal results: Site 955, the third of four sites drilled into the volcanic apron peripheral to Gran Canaria, is located in the southern Canary Channel, 56 km southeast of Gran Canaria, 109 km southwest of Fuerteventura, and 125 km west of the African continental margin on the southeastern volcanic apron of Gran Canaria. The site is in line with DSDP Sites 397 and 369, 50 km and 100 km southeast of Site 955, respectively. The site is separated from Site 953 in the northern basin by the submarine ridge (maximum water depth 1550 m) separating Fuerteventura and Gran Canaria. The drill site is in a fairly flat area at a water depth of 2860 m. Although no structural or other complications were indicated on the highresolution pre-site survey data, additional reflection seismic data was acquired on our approach to Site 955. Site 955 is the first of two sites drilled in the southern volcanic apron of Gran Canaria that is open to sediment influx from the African continental margin. One of the objectives was to compare and correlate the volcaniclastic sediments south of Gran Canaria with those to be drilled in the northern basin. Because post-Miocene volcanic activity is absent in the south of the island, the influx of volcaniclastics in the upper part of the sediment column (younger than 10 Ma) is probably small. The major events to be studied include large explosive eruptions that resulted in widespread ash flows and ash falls during Mogan and Fataga volcanism, roughly between 14 and 10 Ma.

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“…It has been proposed, on the base of the co-occurrence in the same depth intervals along the West African margin of palygorskite and of increased magnesium concentration and salinity, that this mineral formed as a result of continuous precipitation of ion-enriched brines (Gieskes, 1981). Considerable evidence points to the possibility that these brines originated on the continents, then moved down the continental slope, where they passed the salt domes of this area and took up salinity before they precipitated some of their dissolved load in the porous sediments (sandstone, porcellanite) where palygorskite was found (e.g., Couture et al, 1978;Gieskes et al, 1980). In fact, traces of palygorskite were found in the porous porcellanites immediately overlying the palygorskite clays at Site 960.…”

Section: Alteration By Lateral Flow Of Salt Brinesmentioning

confidence: 99%

Origin of lower Eocene palygorskite clays in the Côte d'Ivoire-Ghana Transform Margin, eastern equatorial Atlantic

Pletsch¹

1998

Proceedings of the Ocean Drilling Program, 159 Scientific Results

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Palygorskite was identified in lower Eocene clays and porcellanites in Holes 959D, 960A, 960C, and 961A; in upper Albian to Cenomanian clays with chert in Hole 962B; and in undated clays in Holes 962B and 962C of Ocean Drilling Program Leg 159. Palygorskite is particularly abundant in lower Eocene bluish claystones of Sites 960 and 961, which reach 20 to 30 m in thickness. Based on the microscopic texture, the mineralogical purity of the palygorskite clays, and on growth relationships, palygorskite is interpreted to be of authigenic or very early diagenetic marine origin. The lack of typical detrital lithologies or of sedimentary structures related to resedimentation and the scarcity of clearly terrigenous minerals also argues for in situ formation. Micropaleontologic data indicate that palygorskite formation took place in deep-sea environments with no indication of significant shallowing. The transformation of pre-existing clay minerals at or closely below the sediment/seawater interface seems to be responsible for the formation of palygorskite clay on the Côte d'Ivoire-Ghana Transform Margin. Palygorskite frequently occurs in lower Eocene sediments of equatorial to subtropical paleolatitudes. The formation of authigenic palygorskite clays at the Leg 159 drill sites is interpreted to be the result of elevated deep-sea temperatures and Mgand Si-rich deeper waters. The occurrence of authigenic, deep-marine palygorskite in space and time may correspond to the areas and to the time periods, respectively, of warm, saline deep-water production.

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Interstitial-Water Studies, Deep Sea Drilling Project Sites 415 and 416

Cited by 4 publications

References 9 publications

Interstitial Water Studies, Leg 79

Interstitial Water Studies, Leg 79

Site 955

Origin of lower Eocene palygorskite clays in the Côte d'Ivoire-Ghana Transform Margin, eastern equatorial Atlantic

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