Trace Element Geochemistry and Petrogenesis of Basalts from Deep Sea Drilling Project Sites 556-559 and 561-564

Hertogen, J.; Sachtleben, Th.; Schminkey, H.-U.; Jenner, G.A.

doi:10.2973/dsdp.proc.82.122.1985

Cited by 5 publications

(3 citation statements)

References 19 publications

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“…North of the Hayes Transform, basalts show increasing enrichments in (La/Sm) cn ratios as the Azores region is approached. Such variation in basalt geochemistry along with Sr-Nd-Pb isotopic evidence indicates depleted upper mantle south of the Hayes Transform and both depleted and enriched upper mantle north of the Hayes Transform (Schilling, 1975;White and Schilling, 1978;Schilling et al, 1983;Hamelin et al, 1984;Bougault et al, 1985;Drake et al, 1985;Dupré et al, 1985;Hertogen et al, 1985;Jenner et al, 1985;Rideout and Schilling, 1985;Weaver et al, 1985;Smith, 1994). Spidergrams (Fig.…”

Section: Trace-and Rare-earth-element Geochemistrymentioning

confidence: 94%

“…The basaltic liquid lines of descent were calculated using the FORTRAN program "BA-SALT" from Weaver and Langmuir (1990), which determines mineral/melt equilibria over a range of pressures. Calculated liquid lines of descent from an actual sample and from its predicted parental melt both coincide using the algorithm of Weaver and Langmuir (1990) Schilling (1975), Langmuir et al (1977), Dungan et al (1978), White and Bryan (1977), Schilling et al (1983), Brannon (1985), Hertogen et al (1985), Rideout and Schilling (1985), Frey et al (1993), Smith (1994), and Meyer and Bryan (1996). Figure 6.…”

Section: Parental Melts and Calculated Liquid Lines Of Descentmentioning

confidence: 99%

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Geochemistry of basaltic rocks from the TAG hydrothermal mound (26°08'N), Mid-Atlantic Ridge

Smith¹,

Humphris²

1998

Proceedings of the Ocean Drilling Program

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Variably altered basalts, hydrothermal clays, and metabasaltic clasts were recovered during the Ocean Drilling Program (ODP) Leg 158 from the TransAtlantic Geotraverse (TAG) hydrothermal mound at 26°08′N, 44°49′W, on the Mid-Atlantic Ridge. These basaltic samples exhibit whole-rock chemical changes resulting from hydrothermal alteration of mid-ocean ridge basalt (MORB) at the edges of the TAG mound and within the stockwork zone. Relatively unaltered basalts are used to constrain the petrogenetic history of the magmas in the TAG region. The whole-rock compositions of basalts have relatively narrow ranges of Mg-numbers of 62.6-64.5, olivine compositions (Fo 85.8 −Fo 86.3), and (La/Sm) cn ratios of 0.66−0.73, but rather variable CaO/Al 2 O 3 ratios of 0.70−0.77 and Na 2 O contents of 2.29−2.73 wt%. These Leg 158 basaltic whole-rock compositions have major-, trace-, and rare-earth-element characteristics similar to the glasses from this region. Fractional crystallization modeling using pseudoternary projections and liquid lines of descent calculations indicate that the Leg 158 basalts have probably undergone moderate pressure fractionation of olivine, then olivine + plagioclase at 4 to 6 kb, followed by rapid ascent from the upper mantle with very short crustal residence times. Multiple parental melt compositions are indicated by partial melting and fractional crystallization models. Maximum extents of partial melting in the upper mantle are estimated to be between ~11% and ~25% which is a larger variation than near the Kane Transform (MARK) area at ~10 to ~15%. The maximum extents of partial melting along the Mid-Atlantic Ridge show an overall decline from the Azores hotspot region (38°N) to the region south of the Hayes Transform (33°N), the TAG region (26°N), and Mid-Atlantic Ridge near the Kane Transform (MARK) area (23°N). Melt production and accumulation processes along the TAG segment, however, provide variability on the local scale.

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Section: Trace-and Rare-earth-element Geochemistrymentioning

confidence: 94%

Section: Parental Melts and Calculated Liquid Lines Of Descentmentioning

confidence: 99%

Geochemistry of basaltic rocks from the TAG hydrothermal mound (26°08'N), Mid-Atlantic Ridge

Smith¹,

Humphris²

1998

Proceedings of the Ocean Drilling Program

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“…Enriched basalts characterized by more radiogenic Sr, Pb, and less radiogenic Nd isotopic compositions, light REE enriched patterns, are found in anomalous ridge segments, with very high heat flow and elevated topography. They occur from 34°N to 49°N being centered on the Azores platform and Famous zone (White and Schilling, 1978;Langmuir et al, 1977;Weaver et al, 1987;Hertogen et al, 1985;Drake et al, 1985;Bougault et al, 1985) and north of 49°N being centered on Iceland (from 49° to 63°N) (Schilling, 1973(Schilling, , 1975Schilling et al, 1983;Wood et al, 1979).…”

Section: Morb and Mar Basaltsmentioning

confidence: 99%

Geochemistry of Zero-Age N-MORB from Hole 648B, ODP Legs 106-109, M.A.R., 22°N

Donato¹,

Joron²,

Treuil³

et al. 1990

Proceedings of the Ocean Drilling Program

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Legs 106-109 achieved the first basaltic bare-rock drill hole, on a small volcano (Serocki volcano) located on the flanks of the rift valley in the MAR about 70 km south of the Kane fracture zone. Because of severe technical difficulties only 50.5 m of basalt below seafloor was recovered. Geochemical analysis shows that the recovered basalts display typical N-MORB characteristics as expected in this segment of the Mid-Atlantic ridge. The lava flows display rather equivalent geochemical characteristics all over the drilled section and show the imprint of a previous magmatic differentiation suffered by the magmas before their emission, indicative of a fractional crystallization of plagioclase-bearing cumulates. The incompatible and alkali element content of these 648B magmas is very low, a feature which resembles those of other N-MORB. The geochemical characteristics of these basalts look closely similar to those of basalts from the same flow line emitted respectively 10 m.y. (Hole 395, Legs 45-46), and 110 m.y. (Hole 417A, Legs 51-53) ago, supporting the persistence in this ridge segment of a mantle source with depleted characteristics over the last 110 m.y., but with some variations in the degree of depletion of the source along this period. Although these rocks appear fresh, the imprint of an incipient low temperature alteration can be noticed in a few samples, as evidenced by slight increases of alkali, U elements, and 87 Sr/ 86 Sr isotopic compositions.

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Oceanic ridge crest processes

Rona¹

1987

Reviews of Geophysics

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Oceanic ridge crest processes constitute a vigorous frontier of multidisciplinary research with global ramifications in the earth, atmospheric and biologic sciences. This deep ocean frontier is gradually opening in response to investigations which are elucidating the role of these processes in the lithosphere, hydrosphere, atmosphere and biosphere, and the application of advanced instrumental and interpretive techniques which are increasing the quality and quantity of data. These techniques include crustal drilling with borehole logging (Deep Sea Drilling Project reports), high‐resolution bathymetry (Sea Beam, etc.), side‐scan sonar (SeaMARC I and II, GLORIA, etc.), imagery with video and photography, multichannel seismics, determination of water column properties (CTD with rosette sampler, etc.), and submersible applications.

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Trace Element Geochemistry and Petrogenesis of Basalts from Deep Sea Drilling Project Sites 556-559 and 561-564

Cited by 5 publications

References 19 publications

Geochemistry of basaltic rocks from the TAG hydrothermal mound (26°08'N), Mid-Atlantic Ridge

Geochemistry of basaltic rocks from the TAG hydrothermal mound (26°08'N), Mid-Atlantic Ridge

Geochemistry of Zero-Age N-MORB from Hole 648B, ODP Legs 106-109, M.A.R., 22°N

Oceanic ridge crest processes

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