Hydrothermal and Hydrogenous Ferro-Manganese Deposits: Do They form a Continuum? The Rare Earth Element Evidence

Fleet, Andrew

doi:10.1007/978-1-4899-0402-7_23

Cited by 30 publications

(30 citation statements)

References 6 publications

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“…This work has also shown that hydrothermal sediments exhibit highly characteristic interelement ratios among the REEs, and these ratios Values from Fleet (1983), Graybeal and Heath (1984), Ruhlin and Owen (1986b) , Owen and Olivarez (1988) , and Olivarez and Owen (1989b). b Values from Fleet (1983), Dymond et al (1984), and Palmer and Elderfield (1986).…”

Section: Identification Of Geochemical End Membersmentioning

confidence: 69%

“…Comparisons involving REE ratios are shown in Table 7 because recent studies have found that hydrothermal precipitates are highly efficient scavengers of REEs from both hydrothermal vent fluids and from the ambient seawater that mixes with hydrothermal fluids Owen, 1986a, 1986b;Owen and Olivarez, 1988;Olivarez and Owen, 1989). This work has also shown that hydrothermal sediments exhibit highly characteristic interelement ratios among the REEs, and these ratios Values from Fleet (1983), Graybeal and Heath (1984), Ruhlin and Owen (1986b) , Owen and Olivarez (1988) , and Olivarez and Owen (1989b). b Values from Fleet (1983), Dymond et al (1984), and Palmer and Elderfield (1986).…”

Section: Identification Of Geochemical End Membersmentioning

confidence: 89%

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Geochemistry of Broken Ridge Sediments

Owen¹,

Zimmerman²

1991

Proceedings of the Ocean Drilling Program

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The present study involves the analysis and interpretation of geochemical data from a suite of sediment samples recovered at ODP Hole 752A. The samples encompass the time period that includes the lithospheric extension and uplift of Broken Ridge, and they record deposition below and above the mid-Eocene angular unconformity that denotes this uplift. A Q-mode factor analysis of the geochemical data indicates that the sediments in this section are composed of a mixture of three geochemical end members that collectively account for 94.2% of the total variance in the data. An examination of interelement ratios for each of these end members suggests that they represent the following sedimentary components: (1) a biogenic component, (2) a volcanogenic component, and (3) a hydrothermal component. The flux of the biogenic component decreases almost thirtyfold across the Eocene unconformity. This drastic reduction in the deposition of biogenic materials corresponds to the almost complete disappearance of chert layers, diatoms, and siliceous microfossils and is coincident with the uplift of Broken Ridge. The volcanogenic component is similar in composition to Santonian ash recovered at Hole 755A on Broken Ridge and is the apparent source of the Fe-stained sediment that immediately overlies the angular unconformity. This finding suggests that significant amounts of Santonian ash were subaerially exposed, weathered, and redeposited and is consistent with data that suggest that the vertical uplift of Broken Ridge was both rapid and extensive. The greatest flux of hydrothermal materials is recorded in the sediments immediately below the angular unconformity. This implies that the uplift of Broken Ridge was preceded by a significant amount of rifting, during which faulting and fracturing of the lithosphere led to enhanced hydrothermal circulation. This time sequence of events is consistent with (but not necessarily diagnostic of) the passive model of lithospheric extension and uplift.

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Section: Identification Of Geochemical End Membersmentioning

confidence: 69%

Section: Identification Of Geochemical End Membersmentioning

confidence: 89%

Geochemistry of Broken Ridge Sediments

Owen¹,

Zimmerman²

1991

Proceedings of the Ocean Drilling Program

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“…Iron oxyhydroxides associated with hydrothermal deposits are typically enriched in REE; however, their patterns are generally parallel to seawater ( Fig. 1; Fleet, 1983). REE profiles of hydrothermal anhydrite from porphyry copper deposits show that LREE are preferentially incorporated into the anhydrite structure (Morgan and Wandless, 1980); however, the importance of anhydrite precipitation at the Snake Pit must still be evaluated.…”

Section: Discussionmentioning

confidence: 99%

Trace Element and Sr-Isotopic Contents of Hydrothermal Clays and Sulfides from the Snake Pit Hydrothermal Field: ODP Site 649

Gillis

Smith

Ludden

1990

Proceedings of the Ocean Drilling Program

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Several meters of unconsolidated hydrothermal sediment were recovered from the Snake Pit hydrothermal field during ODP Leg 106. Polymetallic sulfides comprise most of the sediment with minor fragments of massive sulfide, organic debris, clay minerals, and fresh glass shards. Trace element and Sr-isotope contents of hydrothermal clays and sulfides from Holes 649B and 649G indicate that these minerals precipitated from a mixed hydrothermal fluid-seawater solution. Evaluation of the REE mineral data and the Snake Pit hydrothermal fluids shows that the REE distribution coefficients between the hydrothermal fluids and clay-sulfide mixes range from 100-500. This indicates that hydrothermal fluids originating in the root-zone of the Snake Pit hydrothermal system may be modified by the precipitation of hydrothermal minerals, either in the shallow subsurface or within chimney structures. Contrasting REE profiles of clay-sulfide aggregates and massive sulfides from Holes 649B and 649G may be accounted for by spatial and/or temporal variations in redox conditions in the plumbing system.

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“…The rare earth element distribution patterns of recent metalliferous sediments are broadly similar to those of deep-ocean seawater (Bender et al, 1971;Dymond et al, 1974;Piper and Graef, 1974;Toth, 1980;Fleet, 1983). The patterns show comparatively little variation despite strong fractionation of the REE (particularly Ce and Eu) at various depths in the water column (Elderfield and Greaves, 1982).…”

Section: Rare Earth Elementsmentioning

confidence: 75%

Pb and Sr Isotope and Rare Earth Element Composition of Selected Metalliferous Sediments from Sites 597 to 601, Deep Sea Drilling Project Leg 92

Barrett¹,

Taylor²,

Jarvis³

et al. 1986

Initial Reports of the Deep Sea Drilling Project

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Most of the Pb isotope data for the Leg 92 metalliferous sediments (carbonate-free fraction) form approximately linear arrays in the conventional isotopic plots, extending from the middle of the field for mid-ocean ridge basalts (MORB) toward the field for Mn nodules. These arrays are directed closely to the average values of Mn nodules, the composition of which reflects the Pb isotope composition of seawater (Reynolds and Dasch, 1971). Since the Leg 92 samples are almost devoid of continentally derived detritus, it can be inferred that the more radiogenic end-member is seawater. The less radiogenic end-member lies in the very middle of the MORB field, and hence can be considered to reflect the Pb isotope composition of typical ocean-ridge basalt. The array of data lying between these two end-members is most readily interpreted in terms of simple linear mixing of Pb from the two different end-member sources. According to this model, eight samples from Sites 599 to 601 contain 50 to 100% basaltic Pb. Five of these samples have compositions that are identical within the uncertainty of the analyses. We use the average of these five values to define our unradiogenic end-member in the linear mixing model. The ratios used for this average are Sr isotope ratios show a significant range of values, from 0.7082 to 0.7091. The lower ratios are well outside the value of 0.70910 ± 6 for modern-day seawater (Burke et al., 1982). However, most values correspond very closely to the curve of 87 Sr/ 86 Sr versus age for seawater, with older samples having progressively lower 87 Sr/ 86 Sr ratios. The simplest explanation for this progressive reduction is that recrystallization of the abundant biogenic carbonate in the sediments released older seawater Sr which was incorporated into ferromanganiferous phases during diagenesis.Leg 92 metalliferous sediments have total rare earth element (REE) contents that range on a carbonate-free basis from 131 to 301 ppm, with a clustering between 167 and 222 ppm. The patterns have strong negative Ce anomalies. Samples from Sites 599 to 601 display a slight but distinct enrichment in the heavy REE relative to the light REE, whereas those from Sites 597 to 598 show almost no heavy REE enrichment. The former patterns (those for Sites 599 to 601) are interpreted as indicating moderate diagenetic alteration of metalliferous sediments originating at the EPR axis; the latter reflect more complete diagenetic modification.

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Hydrothermal and Hydrogenous Ferro-Manganese Deposits: Do They form a Continuum? The Rare Earth Element Evidence

Cited by 30 publications

References 6 publications

Geochemistry of Broken Ridge Sediments

Geochemistry of Broken Ridge Sediments

Trace Element and Sr-Isotopic Contents of Hydrothermal Clays and Sulfides from the Snake Pit Hydrothermal Field: ODP Site 649

Pb and Sr Isotope and Rare Earth Element Composition of Selected Metalliferous Sediments from Sites 597 to 601, Deep Sea Drilling Project Leg 92

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