Galápagos Hydrothermal Mounds: Stratigraphy and Chemistry Revealed by Deep-Sea Drilling

Natland, James H.; Rosendahl, Bruce R.; Hékinian, Roger; Dmitriev, Y.I.; Fodor, R. V.; Goll, Robert M.; Hoffert, Michel; Humphris, Susan E.; Mattey, D. P.; Petersen, N.; Roggenthen, William; Schrader, Ed L.; Srivastava, Ramesh Kumar; Warren, N.

doi:10.1126/science.204.4393.613

Cited by 34 publications

(48 citation statements)

References 20 publications

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“…Thus no regional hydrothermal sediment blanket exists in the area we drilled. This is contrary to the suggestions of Natland et al (1979) and Rosendahl and Hekinian et al (1980).…”

Section: Discussioncontrasting

confidence: 76%

“…The linear and spatial relationships of the Galapagos hydrothermal mounds sediments with the surrounding pelagic oozes needs clarification in order that previous suggestions (Lonsdale, 1977;Natland et al, 1979;Williams et al, 1979;Schrader et al, 1980;Honnorez, Von Herzen, et al, 1981) as to the nature, origin, and threedimensional framework of the hydrothermal sediments can be resolved. The first complete and undisturbed sediment sections in the hydrothermal mounds were drilled on Leg 70 of the Deep Sea Drilling Project, using the newly developed hydraulic piston corer.…”

Section: Purposementioning

confidence: 99%

“…Away from the mounds the nontronite thins rap- idly, with the furthest extension of nontronitic layers being approximately 50 to 60 meters. No regional layer of hydrothermal sediment exists (Natland et al, 1979). It is interesting that in several mounds and offmounds cores, zones of nontronite-rich mottles are present (Fig.…”

Section: Green Nontronitic Clay Granulesmentioning

confidence: 99%

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Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

Borella¹

1983

Initial Reports of the Deep Sea Drilling Project

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The hydrothermal sediments in the Galapagos mounds area are localized and essentially restricted to the mounds. Hydrothermal nontronites are interbedded with pelagic sediment, which indicates that hydrothermal activity is episodic. The nontronites are thickest on the mounds, thinning away from them rapidly and extending no more than 50 to 60 meters from a mound in any direction. The nontronites also are confined vertically to within the upper one-half to two-thirds of the cores. Manganese-oxide crust fragments are more localized than are the nontronites and do not form any continuous layer.The lack of pelagic sediments on the mounds, the presence of nontronitic mottled zones adjacent to hydrothermal sediment layers (both vertically and laterally), the decrease of siliceous fossil content, and the presence of mostly gradational boundaries between nontronite and pelagic sediment layers suggest that hydrothermal solutions are continually invading and cannibalizing the host pelagic sediment. Replacement and dissolution of pelagic sediment along with direct precipitation of hydrothermal sediments account for the distribution of sediments on a mound.A "relict" brown oxidized surface layer is found at 7 meters sub-bottom and can be correlated from hole to hole. I suggest that this layer is the prominent regional acoustic reflector reported by Lonsdale (1977). The combination of low carbonate accumulation and enrichment of diagenetic Fe and Mn in this zone is probably responsible for altering the acoustic impedance.

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“…Thus no regional hydrothermal sediment blanket exists in the area we drilled. This is contrary to the suggestions of Natland et al (1979) and Rosendahl and Hekinian et al (1980).…”

Section: Discussioncontrasting

confidence: 76%

Section: Purposementioning

confidence: 99%

Section: Green Nontronitic Clay Granulesmentioning

confidence: 99%

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Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

Borella¹

1983

Initial Reports of the Deep Sea Drilling Project

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“…Low abundances of HFS elements and typically flat or light (L)REE depleted REE patterns typical of MORB could be directly transferred by partial melting. Studies of ophiolite complexes (e.g., Bonatti et al, 1976;Spooner et al, 1974) and direct observation at oceanic spreading centers (e.g., Hoffert et al, 1978;Natland et al., 1979) have provided strong evidence for large hydrothermal convection cells at ridge crests. These result in the relatively uniform alteration of Oceanic Layer 2 and Layer 3 to greenschist or amphibolite facies and enrichment of rock in radiogenic (seawater) Sr (Dasch et al, 1973;Hart et al, 1974).…”

Section: L51mentioning

confidence: 99%

The Geochemistry, Mineralogy, and Petrology of Basalts from the West Philippine and Parece Vela Basins and from the Palau-Kyushu and West Mariana Ridges, Deep Sea Drilling Project Leg 59

Mattey¹,

Marsh²,

Tarney³

1981

Initial Reports of the Deep Sea Drilling Project

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“…In addition to the usual measurements of various physical properties and the routine gathering of paleontological and lithological observations, the following specific questions were addressed at Site 508: 1) Is a layer of hydrothermal material present in the sediment column away from the mounds as Natland et al (1979) have postulated?…”

Section: Site 508mentioning

confidence: 99%

Site 508

1983

Initial Reports of the Deep Sea Drilling Project

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Principal results: Six holes were drilled at Site 508. In Hole 508 we cored 35 meters of siliceous foraminifer nannofossil ooze with 99% recovery using the hydraulic piston corer. Semilithified sediment was recovered immediately overlying the basement in Holes 508 and 508C. The sediments do not show a decrease in biogenic silica content with depth and microfossil preservation is better than at the mounds sites. The sedimenfs pore-water chemistry suggests that there is little input of formation waters in this area of presumed recharge. At Hole 5O8B, basement drilling penetrated 10 meters with 5.1 % recovery before drilling was terminated. The basalts recovered are fine-to medium-grained aphyric to sparsely Plagioclase phyric. Alteration rims are common and contain smectites, zeolites(?), and iron-oxyhydroxides. Some samples are slight- ly altered throughout, but no evidence was found of unequivocal hydrothermal alteration.Heat-flow measurements and pore-water sampling were conducted at Hole 5O8A. Principal results: The major purpose was to drill into basement. Sediments were washed to basement, but unfortunately drilling was slow. We abandoned the hole after 10.1 meters of basalt had been drilled with a meager recovery of 5.1 %. A mudline core was taken. Total recovery of sediment plus basalt was 21.4%. HOLE 508BHOLES 508C, 508D, 508E Principal results: Ten meters of sediment were cored above the basement in Hole 508C. This interval was inadvertently washed during Hole 508B drilling. Heat-flow measurements and pore-water sampling were conducted at Holes 5O8D and 508E.

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Galápagos Hydrothermal Mounds: Stratigraphy and Chemistry Revealed by Deep-Sea Drilling

Cited by 34 publications

References 20 publications

Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

Sediment Lithostratigraphy of the Galapagos Hydrothermal Mounds

The Geochemistry, Mineralogy, and Petrology of Basalts from the West Philippine and Parece Vela Basins and from the Palau-Kyushu and West Mariana Ridges, Deep Sea Drilling Project Leg 59

Site 508

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