Alteration of basalts from site 396 B, DSDP: Petrographic and mineralogic studies

Böhlke, John K.; Honnorez, J.; Honnorez-Guerstein, B-M

doi:10.1007/bf00376628

Cited by 68 publications

(41 citation statements)

References 27 publications

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“…This low-temperature process generally results in an increase of H 2 O + , H 2 O~, and K 2 O concentrations and Fe 2 O 3 /FeO ratios, because of the high oxidation ability of the sea water. At the same time, these and some other papers (e.g., Böhlke et al, 1980) evidence a gradual transition between the halmyrolysis and genuinely hydrothermal and metamorphic processes. For example, many secondary minerals (calcite, Fe-Mn-hydroxides, smectite, zeolites, etc.)…”

Section: Secondary Alterationsupporting

confidence: 65%

“…The observed secondary alteration of the Hole 504B basement rocks is in many aspects similar to those produced by rock and sea-water interaction at low temperatures (e.g., Site 396, Mid-Atlantic Ridge; Honnorez et al, 1979;Böhlke et al, 1980). However, the development of Fe-hydroxides, calcites, and K-rich clay minerals (nearly celadonites) occurs only in the upper 300 meters of the drilled basement section.…”

Section: Discussionmentioning

confidence: 75%

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Major- and Trace-Element Chemistry of Hole 504B Basalts and Their Alteration Products (Costa Rica Rift, Deep Sea Drilling Project Leg 70)

Sharaskin¹,

Migdisov²,

Rostschina³

et al. 1983

Initial Reports of the Deep Sea Drilling Project

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Major and trace element compositions of basalts from the lower part of Hole 504B indicate their cogenetic nature. The cored sequence of interlayered pillow lavas and massive lava flows was produced by eruption of lavas, slightly variable in composition. Plagioclase and olivine crystallization in a shallow magma chamber, followed by small-scale fractionation at higher levels, is responsible for these variations. Except in highly fractured zones within the basement, there are systematic variations in the style and degree of rock alteration with depth. Trace element characteristics of altered rocks and secondary minerals indicate that progressive changes in sea water composition occurred as it reacted with basaltic crust.

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Section: Secondary Alterationsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 75%

Major- and Trace-Element Chemistry of Hole 504B Basalts and Their Alteration Products (Costa Rica Rift, Deep Sea Drilling Project Leg 70)

Sharaskin¹,

Migdisov²,

Rostschina³

et al. 1983

Initial Reports of the Deep Sea Drilling Project

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“…The "black halos" they describe are similar to the dark bands in Hole 648B. However, Bohlke et al (1980) reported low-level oxidative alteration in the gray interiors of their samples, in contrast to the entirely fresh interiors of the Hole 648B samples. Their "gray-interior-zone" alteration represents an additional alteration stage that does not exist in Site 648 samples.…”

Section: Summary and Interpretationmentioning

confidence: 74%

“…The alteration is similar to that reported by Laverne and Vivier (1983) from < l-m.y.-old basalts south of the Galapagos Spreading Center. Near the MARK area, the most comparable alteration study is that of Bohlke et al (1980) at Site 396. The "black halos" they describe are similar to the dark bands in Hole 648B.…”

Section: Summary and Interpretationmentioning

confidence: 99%

Site 648

1988

Proceedings of the Ocean Drilling Program

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Site 648 provided a unique view of the internal structure of an axial rift valley volcano. The uppermost 30 m consists of pillow la vas, which built the volcanic edifice. The lower lithologic units con sist of a vesicular basalt underlain by a massive holocrystalline ba salt. These lower units probably represent massive flows that ponded inside Serocki Volcano.Site 648 basalts are moderately evolved normal mid-ocean ridge basalt, saturated with olivine and plagioclase, which are geochemically similar to basalts from the 22°-25°N region. All basalts recov ered at Site 648 are fresh; incipient alteration occurs along fractures. Alteration minerals are smectite and amorphous iron-hydroxyoxide. BACKGROUND AND OBJECTIVES

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“…Since the hole was begun in 1979, secondary alteration has been studied by many researchers (Adamson, 1983;Alt et al, 1983Alt et al, , 1985Alt et al, , 1986Honnorez et al, 1983;Kurnosov et al, 1983;Noack et al, 1983;Boronikhin, 1983a, 1983b;Ishizuka, 1989;Bohlke, 1980;Hart, 1973;Mével, 1980). Their data were used, along with data from other deep-penetration holes in the oceanic basement (Bass, 1976;Pertsev and Rusinov, 1980;etc.…”

Section: Introductionmentioning

confidence: 99%

Metasomatic and Metamorphic Peculiarities of the Diabase Dike Alteration in Hole 504B, Leg 140

Pertsev¹,

Kurdyukov²

1996

Proceedings of the Ocean Drilling Program, 148 Scientific Results

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The diabase dikes recovered during Leg 140 display four types of mineralogical alteration: (1) chlorite + amphibole + titanite; (2) chlorite + amphibole + ilmenite; (3) epidote + prehnite + anhydrite; (4) zeolites + smectite. The first two types represent both background and vein alteration. The third and fourth types are locally overprinted on the previous types. The third type exhibits oxidative features, whereas the fourth formed with cooling of the dike complex. Some veins and patches of strong alteration are surrounded by infiltrate-metasomatic halos, which suggest a difference in fluid pressure in pores and fractures. The temperature of the main alteration types ranged between 350° and 400°C. Noticeable temperature fluctuations in space and time were caused by alternating heating and cooling resulting from intrusions of younger dikes within short time intervals.

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Alteration of basalts from site 396 B, DSDP: Petrographic and mineralogic studies

Cited by 68 publications

References 27 publications

Major- and Trace-Element Chemistry of Hole 504B Basalts and Their Alteration Products (Costa Rica Rift, Deep Sea Drilling Project Leg 70)

Major- and Trace-Element Chemistry of Hole 504B Basalts and Their Alteration Products (Costa Rica Rift, Deep Sea Drilling Project Leg 70)

Site 648

Metasomatic and Metamorphic Peculiarities of the Diabase Dike Alteration in Hole 504B, Leg 140

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