Clay mineral formation in DSDP Leg 34 basalt

Seyfried, William E.; Shanks, Wayne C.; Dibble, Walter E.

doi:10.1016/0012-821x(78)90183-8

Cited by 79 publications

(59 citation statements)

References 27 publications

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“…The phillipsite associated with these minerals can form under oxidizing conditions, as it has in the recent pelagic sediment of the Pacific. This mineral association differs from that determined for the oxidizing diagenesis of either the recent basalt of the East Pacific and Atlantic mid-oceanic ridges (Bass, 1976;Robinson et al, 1977;Seyfried et al, 1976Seyfried et al, , 1978 or the ancient basalt from the Nauru Basin , where the chief minerals of oxidative diagenesis are hydrous ferric oxides and celadonite. It should also be noted that the oxidative diagenesis in the Costa Rica Rift basalts is not as great in importance as in some other mid-oceanic ridges (e.g., those drilled during Legs 34 and 37).…”

Section: Physical and Chemical Conditions For The Formation Of Secondcontrasting

confidence: 96%

Secondary Minerals in Basalt from the Costa Rica Rift, Holes 501 and 504B, Deep Sea Drilling Project Legs 68, 69, and 70

Kurnosov¹,

Kholodkevich²,

Чубаров³

et al. 1983

Initial Reports of the Deep Sea Drilling Project

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Basalt samples recovered during DSDP Legs 68, 69, and 70 from a 550-meter-thick section in two holes near the Costa Rica Rift (Holes 501 and 504B) were found to contain the following secondary minerals: trioctahedral and dioctahedral smectite, chlorite, mixed-layer clays, talc, hematite, pyrite, foujasite, phillipsite, analcime, natrolite, thomsonite, gyrolite, aragonite, calcite, anhydrite, chalcocite, Fe-hydrosilicate, okenite, apophyllite, actinolite, cristobalite, quartz, and magnesite. A less positive identification of bismutite was made. A mineral rich in Mn and minerals with strong reflections at 12.9 Å and 3.20 Å remain unidentified.Trioctahedral smectite replaces glass and olivine in the basalt groundmass. The other secondary minerals occur in veins. The distribution of the secondary minerals in the basalt section shows both hydrothermal and oxidizing-nonoxidizing zonation.Most of the secondary minerals formed under alkaline, nonoxidizing conditions at temperatures up to 120° C. An acidic regime probably existed in the lowest portion of basalt. Oxidative diagenesis followed nonoxidative diagenesis in the upper part of the section. Oxidative diagenesis is characterized by the absence of celadonite, rare occurrences of dioctahedral smectite, and widespread hematite and phillipsite.

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Section: Physical and Chemical Conditions For The Formation Of Secondcontrasting

confidence: 96%

Secondary Minerals in Basalt from the Costa Rica Rift, Holes 501 and 504B, Deep Sea Drilling Project Legs 68, 69, and 70

Kurnosov¹,

Kholodkevich²,

Чубаров³

et al. 1983

Initial Reports of the Deep Sea Drilling Project

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“…As seawater migrated inward toward the cores of cooling-units, progressive D2 depletion of these solutions inhibited the formation of Fe-hydroxides. An increase in pH resulted, favoring the formation of saponite over Fe-hydroxides [Bass, 1976;Seyfried et al, 1978;Andrews, 1980] and the replacement of plagioclase by Kfeldspar [Alt and Honnorez, 1984]. Decreases in the abundance of Fe-hydroxides and lower whole-rock ferrous/ferric ratios with depth (Figures 2 and 9b) show that 02 in solution was progressively depleted as seawater migrated downward.…”

Section: Crustal Agingmentioning

confidence: 98%

“…seawater led t~ the oxidation of basaltic-Fe and the formation of Fe-hydrox1des, especially in zones of high permeability, such as pillow margins and breccias. Precipitation of Fe-hydroxides produced H+ and lowered the pH of the solutions [Seyfried et al, 1978;Alt and Honnorez, 1984]. As seawater migrated inward toward the cores of cooling-units, progressive D2 depletion of these solutions inhibited the formation of Fe-hydroxides.…”

Section: Crustal Agingmentioning

confidence: 99%

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Patterns and processes of alteration in the lavas and dykes of the Troodos Ophiolite, Cyprus

Gillis¹,

Robinson²

1990

J. Geophys. Res.

114

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Alteration panenu in the lavas and dykes of the Troodos Ophiolite, Cypnu, record a compte~ ~st~ of axial hydrochennal alteration, crustal aging, and.subsequent uplift ~d c;rnptac~ent of ~e ophiolite. ~1eld mappina shows that distribution of five alteration zooes, each ~ith duunct rruneralog•cal, gcochermcal, and hydroloaic characteristics, is influenced by igneous stratigraphy, st~cture~ a~d the nature a.nd thickness of the overlying aedimenu. Paragenetic aequences of ICCOlldary ~erals indicate .that alteration conditions changed proareasively as the crust cooled and moved o(f~Uls. Along spreading axes, low temperatures ~SO"C) were mainuined by the rapid flow of seawater m and out of the lavas, and .only minimal alteration took place. In contrast, lower water/rock ratios and hlgh~r te.mperarures (>200°C) m the dykes promoted extensive seawater·rock interaction. Althou~~ the sharp rue .m ~perarure between the two reJ.imes generally coincides with the lava-dyke transJUoo, late· stage mtrus1ons or hydrothermal upwellina zooes locally cause high·temperarure alteration to extend upward .into the lavas. As a segment of crust moved off·axis, temperatures remained tow in the lavas and proaress1vety decreased, ~rom. >250" 10 <80"C in the dykes. High permeability in the uppermost lavas led to the downward rruarauon of an oxidati~e alteration front whose thickness and spatial distribution was dependent upon the. rate and nature of sedimentation and, thus, the original seafloor morphology. Although field relations sho.w that alteration has a consistent vertical pattern in Troodos, the alteration zooes are not laterally oonunuous, and the stratigraphic depth of their boundaries varies considerably. IN1ROOUC110NEarly studies of the massive sulfide deposits [Constantinou and Govett, 1973) and alteration patterns within the Troodos ophiolite [Gass and Smewing, 1973) contributed greatly to the development of models for oceanic hydrothermal systems [SpooMr et al., 1977; C haprno.n and SpooMr, 1977] and subseafloor metamorphism [Coleman, 1977]. Subsequent discovery of high-temperature vents at mid-ocean ridges [e.g., Edmond et al., 1979), seamounts [MalaJwff et al., 1982], and back arc basins [Horbie et al., 1986] showed that hydrothermal circulation is a fundamental process in many oceanic environments.Mineralogical and chemical zonations within the Troodos massive sulfide ore deposits indicate that they formed from hydrothermal flu1ds whose compositions were remarkably similar to those venting on the seafloor today [Adamides, 1987;Herzig and Friedrich , 1987;Richards et al., 1989). Fluid compositions in Troodos were buffered by epidosites at conditions similar to those inferred for the root-zones of active systems at mid-ocean ridges [Bowers and Taylor, 1985;Richardson et al., 1987;Schiffman et al., 1987;Schiffman and Smith, 1988;Seyfried et al., 1988;Von Damm, 1988] . Because of these and other similarities, the upflow zones of the Troodos hydrothermal systems are thought to be ancient analogues of modem active systems [Oud...

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“…4a), while in the same general area chlorite and spherulitic silica constitute the matrix of an autobrecciated horizon in the lower part of the Cressbrook Dale Lava intersected by the Eyam Borehole. These occurrences are considered to be atypical examples in the South Pennines and may indicate high-temperature sea-water reactions, as described by Seyfried and Bischoff (1981), in contrast with the predominantly subaerial extrusive nature of most of the material, for 'normal' smectite has been developed in the coarse grained tufts above the Cressbrook Dale Lava ( fig. 4b) in this area.…”

Section: *To~l I~n As Feomentioning

confidence: 93%

Clay minerals in the basalts of the South Pennines

Walters

Ineson

1983

Mineral. mag.

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ABSTRACT. X-ray diffraction, electron microprobe and STEM EDAX analyses of basalts from the South Pennines (Derbyshire) indicate that Fe-rich smectites are the dominant alteration products, occurring either as pseudomorphs or infilling veins and vesicles. Previously chlorite has been identified as the common alteration product but its occurrence is very infrequent.MORE than forty basaltic lavas, tufts, and sills interbedded with the Dinantian limestones of the South Pennines have been described by Waiters and Ineson (1981) and the general distribution pattern is shown in fig. 1. For the most part they have suffered extensive deuteric and/or hydrothermal alteration and as such show all the stages of decomposition to the final product a clay mineral assemblage.

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Clay mineral formation in DSDP Leg 34 basalt

Cited by 79 publications

References 27 publications

Secondary Minerals in Basalt from the Costa Rica Rift, Holes 501 and 504B, Deep Sea Drilling Project Legs 68, 69, and 70

Secondary Minerals in Basalt from the Costa Rica Rift, Holes 501 and 504B, Deep Sea Drilling Project Legs 68, 69, and 70

Patterns and processes of alteration in the lavas and dykes of the Troodos Ophiolite, Cyprus

Clay minerals in the basalts of the South Pennines

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