The effects of cooling rate on texture and pyroxene chemistry in DSDP Leg 34 basalt: A microprobe study

Coish, R. A.; Taylor, L. A.

doi:10.1016/0012-821x(79)90048-7

Cited by 104 publications

(41 citation statements)

References 8 publications

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“…The crystallization path of Ca-rich pyroxene is controlled by a number of chemical and physical factors which include temperature and degree of undercooling of the host melt, volatiles, pθ 2 , and cotectic crystallization of other phases (Barberi et al, 1971). The influence of cooling rate or degree of undercooling on the composition of pyroxene has been reported by many authors (e.g., Donaldson et al, 1975;Lofgren et al, 1974;Coish and Taylor, 1979). High degrees of undercooling promote rapid metastable crystallization of pyroxenes which become strongly subcalcic (e.g., Muir and Tilley, 1964;Smith and Lindsley, 1971;Yamakawa, 1971).…”

Section: Groundmassmentioning

confidence: 92%

“…Subcalcic pyroxenes from the glassy selvages of pillow basalts and spilites (Mevel and Velde, 1976) from the chilled margins of dykes (Mattey, 1979), sills (Yamakawa, 1971;Coish and Taylor, 1979), and lavas (Fodor et al, 1975) are characteristically enriched in TiO 2 and A1 2 O 3 relative to calcic pyroxenes which have crystallized more slowly in the interiors of these bodies. The contents of TiO 2 and A1 2 O 3 in Hole 425 subcalcic augites, however, are generally lower than in the calcium-rich counterparts in the same sample (e.g., compare Analyses 7 and 10 or 11 and 14, Table 5).…”

Section: Groundmassmentioning

confidence: 99%

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Geochemistry and Mineralogy of Basalts from the Galapagos Spreading Center, Deep Sea Drilling Project Leg 54

Mattey¹,

Muir²

1980

Initial Reports of the Deep Sea Drilling Project

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Basalts drilled at Site 424 and Hole 425 near the Galapagos Spreading Center at 86°W are moderately evolved basalts and ferrobasalts characteristic of the non-rifted ridges in the eastern Pacific. Three distinct chemical types occur at Hole 425, but only one type, a ferrobasalt, occurs in all four holes at Site 424. Despite strong enrichment of Fe, Ti, Zr, and the rare-earth elements, these basalts are similar to depleted mid-ocean ridge basalts and were therefore generated within a depleted mantle source. Electron-microprobe mineral analyses were obtained on several samples; one from Site 424 was intensively studied. The variations in groundmass pyroxene compositions within the single sample are almost equivalent to the entire variation observed in all the Galapagos basalts. Phenocryst compositions are used to model least-squares crystal fractionation among the basalts. Although satisfactory fits to major-oxide compositions can be obtained by fractionating mainly plagioclase and clinopyroxene plus minor olivine, this fails to account for the levels of certain trace elements in the most evolved basalts of Hole 425. Instead of fractionation, we believe that mixing of ferrobasalts with more primitive basalts explains these variations more satisfactorily.

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Section: Groundmassmentioning

confidence: 92%

Section: Groundmassmentioning

confidence: 99%

Geochemistry and Mineralogy of Basalts from the Galapagos Spreading Center, Deep Sea Drilling Project Leg 54

Mattey¹,

Muir²

1980

Initial Reports of the Deep Sea Drilling Project

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“…The trend of decreasing Cr with decreasing Mg# in Figure 2 is the result of fractionation (Grove and Bryan, 1983). Differences between the abundance of Cr, Ti, and Al in phenocrysts and microphenocrysts/spherulites is likely to be the result of kinetic effects during quenching (Coish and Taylor, 1979;Gamble and Taylor, 1980). However, phenocrysts have higher Mg#, and lower TiO 2 , and A1 2 O 3 , <0.35% and <3.5%, respectively, than microphenocrysts (Fig.…”

Section: Clinopyroxenementioning

confidence: 95%

Petrology of Chilled Dike Margins Recovered from Hole 504B, Leg 140

McNeill¹

1995

Proceedings of the Ocean Drilling Program, 137/140 Scientific Results

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“…The prominent substitution corresponds to the increase of iron at the expense of Ca and Mg, the Mn and Ti contents remaining approximately constant. The Al patterns are complex: the decrease of A1 VI in the internal part of the crystal may be attributed to crystallization under decreasing pressures, although the abrupt variations of A1 IV and the increase of A1 VI in the external part would perhaps indicate changes in cooling rates (Coish and Taylor, 1979;Gamble and Taylor, 1980) presumably connected with the emplacement process.…”

Section: Pyroxenesmentioning

confidence: 99%

Strongly Depleted Tholeiites from the Rockall Plateau Margin, North Atlantic: Geochemistry and Mineralogy

Joron¹,

Bougault²,

Maury³

et al. 1984

Initial Reports of the Deep Sea Drilling Project

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The Leg 81 basalts, drilled either from the margins ("dipping reflectors" sequence: Holes 552, 553A, and 554A) or from the "continental" side (Hole 555) of the Rockall Plateau microcontinent, are strongly light rare-earth element (LREE) depleted oceanic tholeiites. The basalts from the four holes are almost similar. Most of their primary characteristics have been preserved, although they have suffered alteration by seawater. From the petrological and mineralogical points of view, they resemble deep-ocean-floor basalts but show some peculiarities (occurrence of pigeonite and ilmenite as normal components of the groundmass differentiation sequences toward ferrobasalts). Their geochemical characteristics are dominated by their extreme depletion in the most hygromagmaphile elements (Th, Ta, La, and Nb), the concentrations of which are sometimes lower than the corresponding chondritic values. Leg 81 basalts are thus clearly different from continental tholeiites (flood basalts): Possible equivalents in the Thulean Tertiary Magmatic Province include the LREE-depleted tholeiites from the Upper Basaltic Series of the Faeroe Islands and the Preshal Mhor basalt type from the British Tertiary Province.

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The effects of cooling rate on texture and pyroxene chemistry in DSDP Leg 34 basalt: A microprobe study

Cited by 104 publications

References 8 publications

Geochemistry and Mineralogy of Basalts from the Galapagos Spreading Center, Deep Sea Drilling Project Leg 54

Geochemistry and Mineralogy of Basalts from the Galapagos Spreading Center, Deep Sea Drilling Project Leg 54

Petrology of Chilled Dike Margins Recovered from Hole 504B, Leg 140

Strongly Depleted Tholeiites from the Rockall Plateau Margin, North Atlantic: Geochemistry and Mineralogy

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