Phase Chemistry Studies on Gabbro and Peridotite Rocks from Site 334, DSDP Leg 37

Symes, R. F.; Bevan, J. C.; Hutchison, Robert

doi:10.2973/dsdp.proc.37.167.1977

Cited by 7 publications

(19 citation statements)

References 1 publication

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“…This is consistent with the discussion of mineralogical variability for the Mid-Atlantic Ridge peridotites (e.g., Michael and Bonatti, 1985;Bonatti et al, 1992). It is noted that the spinel compositions around Cr# = 29 are slightly higher than those from Site 670 in the MARK area (Fujii, 1990;Juteau et al, 1990;Komor et al, 1990), and lower than those from Site 395 in the western flank of Mid-Atlantic Ridge in the MARK area (Arai and Fujii, 1979;Sinton, 1979), Site 334 (DSDP Leg 37) in the FAMOUS area (Clarke and Loubat, 1977;Sigurdsson, 1977;Symes et al, 1977), and some fracture zones around Mid-Atlantic Ridge (Prinz et al, 1976;Bonatti et al, 1992;Cannat et al, 1992).…”

Section: Characteristics Of Chemical Composition Of Primary Mineralssupporting

confidence: 76%

“…Abbreviations as in Table 1. Clarke and Loubat, 1977;Sigurdsson, 1977;Symes et al, 1977;Arai and Fujii, 1979;Sinton, 1979;Fujii, 1990;Juteau et al, 1990;Komor et al, 1990;Bonatti et al, 1992;Cannat et al, 1992). A highly uniform composition of primary spinel cores (Mg# = 70-75 and Cr# = 27-31) is conspicuous in Hole 920D spinel harzburgites and lherzolites (Fig.…”

Section: Spinelmentioning

confidence: 99%

“…Data sources for clinopyroxenes from Mid-Atlantic Ridge (Prinz et al, 1976;Clark and Loubat, 1977;Symes et al, 1977;Arai and Fujii, 1979;Sinton, 1979;Fujii, 1990;Hebert et al, 1990;Juteau et al, 1990;Komor et al, 1990;Bonatti et al, 1992;Cannat et al, 1992); American-Antarctic Ridge (AAR) and Southwest Indian Ridge (SWIR; Dick, 1989); and those related to the pre-oceanic rifting during the early stage of continental breakup (preoceanic rifts) from Saint Paul's Rocks (Melson et al, 1972), Galicia Margin (Evans and Girardeau, 1988;Kornprobst and Tabit, 1988), Zabargad (Bonatti et al, 1986;Piccardo et al, 1988), southwest Australia (Nicholls et al, 1981), and Antarctic Seamount B (Niida and Yuasa, 1995). …”

Section: Modification Of Peridotites By Magma Channeling Magma Channementioning

confidence: 99%

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Mineralogy of MARK peridotites: replacement through magma channeling examined from Hole 920D, MARK area

Nilia¹

1997

Proceedings of the Ocean Drilling Program, 153 Scientific Results

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Peridotites drilled at Site 920 of Ocean Drilling Program Leg 153 in the Mid-Atlantic Ridge near the Kane Transform (MARK) area were examined to understand the mode of magma channeling and modification of the upper mantle peridotites. This paper presents mineralogical data from a slow-spreading ocean ridge for peridotites that have been modified by magma channeling and for those that are free from the modification.The chemical compositions of primary minerals in spinel harzburgite and lherzolite are highly uniform. Olivine core compositions concentrate around Fo = 91.0 and NiO = 0.37 wt%. Spinel cores also have a small compositional range of Mg# = 70-75 and Cr# = 27-31. Orthopyroxenes with Mg# = 90.5-91.6 have A1 2 O 3 contents of 3.17 to 4.77 wt%. TiO 2 and Na 2 O contents in primary clinopyroxenes are extremely low, less than 0.15 and 0.11 wt%, respectively. These results suggest that the MARK peridotites represent moderately depleted upper mantle peridotite. The chemical compositions of primary minerals are modified where the peridotites are crosscut by gabbro and pyroxenite dikes and veins. Such peridotites are enriched in FeO* and TiO 2 , and depleted in MgO, NiO, and A1 2 O 3 .Spatial variations in chemical composition of minerals were examined across channels in Samples 153-920D-10R-2 (Piece 4, 35-41 cm) and 153-920D-13R-2 (Piece 7, 136-143 cm). Primary minerals in spinel harzburgite are enriched in FeO* and TiO 2 within narrow replacement bands next to websterite veins. No evidence for melt extractions was detected in the harzburgite wall, indicating that the replacement occurred as a one-way modification process by melt addition from the channeling magma. The Fo-NiO systematics for the modified olivines support a model of open-system reaction between the wall harzburgite and the infiltration melt with a highly evolved composition. All of the results emphasize that the final magma channeling occurred in "cold" peridotites at a shallow level of the upper mantle.

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Section: Characteristics Of Chemical Composition Of Primary Mineralssupporting

confidence: 76%

Section: Spinelmentioning

confidence: 99%

Section: Modification Of Peridotites By Magma Channeling Magma Channementioning

confidence: 99%

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Mineralogy of MARK peridotites: replacement through magma channeling examined from Hole 920D, MARK area

Nilia¹

1997

Proceedings of the Ocean Drilling Program, 153 Scientific Results

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“…Based on the composition of their constituent minerals, the layered rocks were subdivided into ultrabasic, eucritic and gabbroic cumulates (Wager and Brown 1968). The ultrabasic cumulates comprise peridotite, or olivine-cumulate, and allivalite, or feldsparolivine ( ± pyroxene) cumulate, the cumulus feldspar ranging from about An 90 -81 .…”

Section: Introductionmentioning

confidence: 99%

“…2) (Weedon 1961;Hutchison 1966a), which is truncated by the outer margin of the funnel-shaped intrusion . Layered allivalite, Unit 1 is banked on to the marginal, unlayered White Allivalite (Hutchison 1968), and overlies peridotite and dunite. These ultrabasic layered rocks (Fig.…”

Section: Introductionmentioning

confidence: 99%

The Cuillin layered igneous complex—evidence for multiple intrusion and former presence of a picritic liquid

Hutchison

Bevan

1977

SJG

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SYNOPSISMuch of the western Cuillin is formed by part of a funnel-shaped intrusion comprising layered ultrabasic rocks which range upwards from dunite to peridotite to allivalite (feldspar-olivine cumulate). The funnel-shaped intrusion has a marginal border group on which allivalites are banked. Recent mapping indicates that a peridotite mass previously regarded as a sill, is part of this layered sequence, and that inner, ultrabasic cumulates to the E are merely a downthrown portion of the same funnel-shaped mass. The eastern rocks were cut by a later pyroxene-rich magma from which feldspar-olivine-pyroxene cumulates were formed. In the lower dunite-peridotite-allivalite series (Unit 1), cumulus olivine and feldspar range from Fo 9 0 -8 6 and An 91 _ 85 , respectively. In the upper unit (Unit 2) of feldspar-olivine-pyroxene cumulates cryptic variation is more complex; feldspar cores are An 84 -83 , and olivines range from Fo 7 7 -6 7 .The high level of the Cuillin complex suggests that there was insufficient room for a layered basic intrusion some 10,000 metres thick. Evidence is presented for successive pulses of ultrabasic magma, indicating that the complex as a whole comprises intrusions of tholeiitic affinity ranging broadly with time from ultrabasic to gabbroic, rather than a tectonically disrupted single, layered basic intrusion.

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“Na and Cr contents in clinopyroxenes from peridotites: a possible discriminant between ‘sub-continental’ and ‘sub-oceanic’ mantle”—a reply to G. Sen

Kornprobst¹,

Ohnenstetter²,

Ohnenstetter³

1982

Earth and Planetary Science Letters

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Phase Chemistry Studies on Gabbro and Peridotite Rocks from Site 334, DSDP Leg 37

Cited by 7 publications

References 1 publication

Mineralogy of MARK peridotites: replacement through magma channeling examined from Hole 920D, MARK area

Mineralogy of MARK peridotites: replacement through magma channeling examined from Hole 920D, MARK area

The Cuillin layered igneous complex—evidence for multiple intrusion and former presence of a picritic liquid

“Na and Cr contents in clinopyroxenes from peridotites: a possible discriminant between ‘sub-continental’ and ‘sub-oceanic’ mantle”—a reply to G. Sen

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