An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail Ophiolite, Oman: Evidence for δ<sup>18</sup>O buffering of the oceans by deep (&gt;5 km) seawater‐hydrothermal circulation at mid‐ocean ridges

Gregory, Robert T.; Taylor, Hugh P.

doi:10.1029/jb086ib04p02737

Cited by 883 publications

(493 citation statements)

References 53 publications

(48 reference statements)

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“…The high temperature hydrothermal metamorphism did not extend below the gabbros, and did not affect the deeper ultramafic rocks, as has also been observed in intact ophiolites (e.g. Oman: Gregory & Taylor, 1981). This was explained by the impermeability of deeper parts of the oceanic crust due to closure of open cracks at confining pressures higher than 1 kbar (Boudier & Nicolas, 1985;Paterson, 1978).…”

Section: Discussionmentioning

confidence: 61%

“…rocks underwent hydration. The alteration could potentially be a result of the high permeability of young seafloor allowing sea-water to penetrate and hydrothermally react with the rocks, or of submarine weathering (Gregory & Taylor, 1981;Stakes & O'Neil, 1982;Alt, Muehlenbachs & Honnorez, 1986). Alternatively, the greenschist metamorphic event may have involved hydration (as in the case of alteration of meta-gabbro) or dehydration (deserpentinization).…”

Section: A Major and Trace Element Geochemistrymentioning

confidence: 99%

“…Oxygen isotope analyses have been shown to be powerful indicators of the nature of fluid-rock interaction in ophiolitic suites (e.g. Wenner & Taylor, 1973;Gregory & Taylor, 1981;Muehlenbachs, 1986;Burkhard & O'Neil, 1988), and in this section we will attempt to characterize the 8 18 O 'signatures' of the various components of the Tinos rocks for their implications for fluid-rock interactions.…”

Section: A Major and Trace Element Geochemistrymentioning

confidence: 99%

“…O-enriched fluid could be produced by high temperature oceanic alteration as suggested by Gregory & Taylor (1981).…”

mentioning

confidence: 99%

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The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

et al. 1996

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-The six exposures of the Upper tectonic Unit of the Cycladic Massif occurring on the island of Tinos are shown to comprise a metamorphosed dismembered ophiolite complex. The common stratigraphic section consisting of tens-of-metres-thick tectonic slices of mafic phyllites overlain by serpentinites and gabbros is considered to have been derived by a combination of thrusting during obduction and subsequent attenuation by low-angle normal faults. All rock types show evidence of a phase of regional greenschistfacies metamorphism, which in the case of the phyllites is accompanied by penetrative deformation. The greenschist-facies metamorphism in gabbros is preceded by high temperature sea-floor amphibolite-facies alteration, whereas in the serpentinites, the antigorite + forsterite greenschist-facies assemblage overprinted an earlier low temperature lizardite serpentinite. Trace element patterns of the mafic phyllites and a harzburgitic origin of meta-serpentinites suggest a supra subduction zone (SSZ) affinity for the ophiolitic suite. 5"O values of phyllites, gabbros and serpentinites range from 6 to 15%o. Model calculations indicate that such values are consistent with low temperature (50-200 °C) alteration of parent rocks by sea-water at varying water/rock ratios. This would agree with the early low temperature mineralogy of the serpentinites, but the early high temperature alteration of the gabbros would require the presence of "O-enriched sea-water.The following overall history is suggested for Tinos ophiolitic slices.(1) Oceanic crust was generated at a supra-subduction zone spreading centre with high temperature alteration of gabbros. (2) Tectonic disturbance (its early hot stages recorded in an amphibolitic shear zone at the base of serpentinites) brought the already cooled ultramafics into direct contact with sea-water and caused low-7* serpentinization. (3) Tectonism after cooling involved thrusting which caused repetition and inversion of the original order of the oceanic suite. (4) Regional metamorphism of all the ophiolite components at greenschist-facies conditions (~450 °C) overprinted the early alteration mineralogy. It was probably induced by continued thrusting and piling up of nappes. The Tinos ophiolite, dated as late Cretaceous and genetically related to other low pressure rock-units of the same age in the Aegean, differs in age and degree of dismemberment and metamorphism from ophiolites in mainland Greece.

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Section: Discussionmentioning

confidence: 61%

Section: A Major and Trace Element Geochemistrymentioning

confidence: 99%

Section: A Major and Trace Element Geochemistrymentioning

confidence: 99%

“…O-enriched fluid could be produced by high temperature oceanic alteration as suggested by Gregory & Taylor (1981).…”

mentioning

confidence: 99%

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The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

et al. 1996

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“…Although Gregory and Taylor [1981] showed that this circulation involves a very low water/rock ratio (• 0.2), in the Oman ophiolite its isotopic effects are significant, because they are observed throughout a large part of the lower oceanic crust, at least down to the MOHO. To even a greater degree than the shallow, axial system considered extensively in this study, the deep system also produces marked 180 depletions in the rocks; thus, its effects must also be counter-balanced by an appropriate amount of low-temperature, off-axis hydrothermal activity and submarine weathering.…”

Section: For Example If the 21øn Epr Fluid Composition Given Inmentioning

confidence: 99%

An integrated chemical and stable‐isotope model of the origin of Midocean Ridge Hot Spring Systems

Bowers¹,

Taylor²

1985

J. Geophys. Res.

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228

119

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Chemical and isotopic changes accompanying seawater-basalt interaction in axial midocean ridge hydrothermal systems are modeled with the aid of chemical equilibria and mass transfer computer programs, incorporating provision for addition and subtraction of a wide-range of reactant and product minerals, as well as cation and oxygen and hydrogen isotopic exchange equilibria. The models involve stepwise introduction of fresh basalt into progressively modified seawater at discrete temperature intervals from 100 ø to 350øC, with an overall water-rock ratio of about 0.5 being constrained by an assumed

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Whole planet coupling between climate, mantle, and core: Implications for rocky planet evolution

Foley

Driscoll

2016

Geochem Geophys Geosyst

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Earth's climate, mantle, and core interact over geologic timescales. Climate influences whether plate tectonics can take place on a planet, with cool climates being favorable for plate tectonics because they enhance stresses in the lithosphere, suppress plate boundary annealing, and promote hydration and weakening of the lithosphere. Plate tectonics plays a vital role in the long-term carbon cycle, which helps to maintain a temperate climate. Plate tectonics provides long-term cooling of the core, which is vital for generating a magnetic field, and the magnetic field is capable of shielding atmospheric volatiles from the solar wind. Coupling between climate, mantle, and core can potentially explain the divergent evolution of Earth and Venus. As Venus lies too close to the sun for liquid water to exist, there is no long-term carbon cycle and thus an extremely hot climate. Therefore plate tectonics cannot operate and a long-lived core dynamo cannot be sustained due to insufficient core cooling. On planets within the habitable zone where liquid water is possible, a wide range of evolutionary scenarios can take place depending on initial atmospheric composition, bulk volatile content, or the timing of when plate tectonics initiates, among other factors. Many of these evolutionary trajectories would render the planet uninhabitable. However, there is still significant uncertainty over the nature of the coupling between climate, mantle, and core. Future work is needed to constrain potential evolutionary scenarios and the likelihood of an Earth-like evolution.

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An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail Ophiolite, Oman: Evidence for δ¹⁸O buffering of the oceans by deep (>5 km) seawater‐hydrothermal circulation at mid‐ocean ridges

Cited by 883 publications

References 53 publications

The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

An integrated chemical and stable‐isotope model of the origin of Midocean Ridge Hot Spring Systems

Whole planet coupling between climate, mantle, and core: Implications for rocky planet evolution

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An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail Ophiolite, Oman: Evidence for δ18O buffering of the oceans by deep (>5 km) seawater‐hydrothermal circulation at mid‐ocean ridges

Cited by 883 publications

References 53 publications

The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

The tectono-metamorphic evolution of a dismembered ophiolite (Tinos, Cyclades, Greece)

An integrated chemical and stable‐isotope model of the origin of Midocean Ridge Hot Spring Systems

Whole planet coupling between climate, mantle, and core: Implications for rocky planet evolution

Contact Info

Product

Resources

About

An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail Ophiolite, Oman: Evidence for δ¹⁸O buffering of the oceans by deep (>5 km) seawater‐hydrothermal circulation at mid‐ocean ridges