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  • 1
    Book
    Book
    Stable isotope geochemistry : a tribute to Samuel Epstein (1991)
    San Antonio, Tex. : Geochem. Soc.
    Details Availability
    Keywords: geochemistry ; isotope geology ; Biografie ; Konferenzschrift ; Isotopengeochemie ; Stabiles Isotop ; Geowissenschaften ; Anwendung ; USA ; Geochemiker ; Epstein, Samuel 1919-2001
    Type of Medium: Book
    Pages: xvi, 516 p , Ill., graph. Darst , 27 cm
    ISBN: 0941809021
    Series Statement: Special publication / Geochemical Society 3
    DDC: 551.9
    RVK:
    RB 10115
    Language: English
    Note: 1 Portrait von S.Epstein ; Subject Index
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  • 2
    Electronic Resource
    Electronic Resource
    Possible non-equilibrium oxygen isotope effects in mantle nodules, an alternative to the Kyser-O'Neil-Carmichael18O/16O geothermometer (1986)
    Springer
    Contributions to mineralogy and petrology 93 (1986), S. 114-119 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Kyser, O'Neil, and Carmichael (1981, 1982) measured theδ 18O values of coexisting minerals from peridotite nodules in alkali basalts and kimberlites, interpreting the nodules as equilibrium assemblages. Using Ca-Mg-Fe element-partition geothermometric data, they proposed an empirical18O/16O geothermometer: T(°C)=1,151−173Δ−68Δ 2, whereΔ is the per mil pyroxene-olivine fractionation. However, this geothermometer has an unusual “crossover” at 1,150 °C, and in contrast to what might be expected during closed-system equilibrium exchange, the most abundant mineral in the nodules (olivine) shows a much greater range inδ 18O (+4.4 to +7.5) than the much less abundant pyroxene (all 50 pyroxene analyses from spinel peridotites lie within the interval +5.3 to +6.5). Onδ 18O-olivinevs. δ 18O-pyroxene diagrams, the mantle nodules exhibit data arrays that cut across theΔ 18O=zero line. These arrays strongly resemble the non-equilibrium quartzfeldspar and feldspar-pyroxeneδ 18O arrays that we now know are diagnostic of hydrothermally altered plutonic igneous rocks. Thus, we have re-interpreted the Kyser et al. data as non-equilibrium phenomena, casting doubt on their empirical geothermometer. The peridotite nodules appear to have been open systems that underwent metasomatic exchange with an external, oxygen-bearing fluid (CO2, magma, H2O, etc.); during this event, the relatively inert pyroxenes exchanged at a much slower rate than did the coexisting olivines and spinels, in agreement with available exchange-rate and diffusion measurements on these minerals. This accounts for the correlation betweenΔ 18O pyroxene-olivine and the whole-rockδ 18O of the peridotites, which is a major difficulty with the equilibrium interpretation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00963589
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  • 3
    Electronic Resource
    Electronic Resource
    Stable isotope constraints on the origin and depth of penetration of hydrothermal fluids associated with Hercynian regional metamorphism and crustal anatexis in the Pyrenees (1987)
    Springer
    Contributions to mineralogy and petrology 95 (1987), S. 255-268 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Late Carboniferous (Hercynian) tectonism in the Pyrenees generated extremely steep thermal gradients at 8–14 km depth in the continental crust, producing andalusite- and sillimanite-grade metamorphism and partial melting of Lower Paleozoic metasediments under water-rich conditions. At the same time, amphibolite- and granulitefacies “basal gneisses” were equilibrated under dryer conditions at pressures of 4 to 7 kbar (14–25 km depth), beneath these higher-level rocks. We present 95 new oxygen isotopic analyses of samples from the Agly, St. Barthelemy, Castillon and Trois Seigneurs Massifs, highlighting contrasting 18O/16O systematics at different structural levels in the Hercynian crust, here termed Zones 1, 2, and 3. The unmetamorphosed, fossiliferous, Paleozoic shales and carbonates of Zone 1 have typical sedimentary δ 18O values, mostly in the range +14 to +16 for the pelitic rocks and +20 to +25 for the carbonates. The metamorphosed equivalents of these rocks in Zone 2 all have strikingly uniform and much lower δ 18O values; the metapelites mostly have δ 18O=+10 to +12, and interlayered metacarbonates from the Trois Seigneurs Massif have δ 18O of about +12 to +14. Typically, the Zone 3 “basal gneisses” are isotopically heterogeneous with variable δ 18O values ranging from +6 in mafic lithologies to +22 in carbonate-rich lithologies. Steep gradients in δ 18O (as much as 10 per mil over a few cm) are preserved at the margins of some metacarbonate layers. These data indicate that the Zone 3 gneisses were infiltrated by much smaller volumes of metamorphic pore fluids than were the overlying Zone 2 rocks, and that circulation of surface-derived H2O (either seawater or formation waters, as evidenced by high δD values) was mainly confined to the Paleozoic supracrustal sedimentary pile. This is compatible with an overall reduction of interconnected porosity with increasing depth, but perhaps even more important, the extensive partial melting at the base of Zone 2 may have produced a ductile, impermeable barrier to downward fluid penetration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371841
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  • 4
    Electronic Resource
    Electronic Resource
    Stable isotopic evidence for large-scale seawater infiltration in a regional metamorphic terrane; the Trois Seigneurs Massif, Pyrenees, France (1985)
    Springer
    Contributions to mineralogy and petrology 91 (1985), S. 122-137 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Oxygen isotopic analyses of 95 metamorphic and igneous rocks and minerals from a Hercynian metamorphic sequence in the Trois Seigneurs Massif, Pyrenees, France, indicate that all lithologies at higher metamorphic grades than the “andalusite in” isograd have relatively homogeneous δ 18O values. The extent of homogenization is shown by the similarity of δ 18O values in metacarbonates, metapelites and granitic rocks (+11 to +13), and by the narrow range of oxygen isotopic composition shown by quartz from these lithologies. These values contrast with the δ 18O values of metapelites of lower metamorphic grade (δ 18O about +15). Homogenization was caused by a pervasive influx of hydrous fluid. Mass-balance calculations imply that the fluid influx was so large that its source was probably high-level groundwaters or connate formation water. Hydrogen isotopic analyses of muscovite from various lithologies are uniform and exceptionally heavy at δD=−25 to −30, suggesting a seawater origin. Many lines of petrological evidence from the area independently suggest that metamorphism and anatexis of pelitic metasediment occurred at depths of 6–12 km in the presence of this water-rich fluid, the composition of which was externally buffered. Deep penetration of surface waters in such environments has been hitherto unrecognized, and may be a key factor in promoting major anatexis of the continental crust at shallow depth. Three types of granitoid are exposed in the area. The leucogranites and the biotite granite-quartz diorite are both mainly derived from fusion of local Paleozoic pelitic metasediment, because all these rocks have similar whole-rock δ 18O values (+11 to +13). The post-metamorphic biotite granodiorite has a distinctly different δ 18O (+9.5 to +10.0) and was probably derived from a deeper level in the crust. Rare mafic xenoliths within the deeper parts of the biotite granite-quartz diorite also have different δ 18O (+8.0 to +8.5) and possibly represent input of mantle derived magma, which may have provided a heat source for the metamorphism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377760
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  • 5
    Electronic Resource
    Electronic Resource
    18O/16O ratios in ash-flow tuffs and lavas erupted from the central Nevada caldera complex and the central San Juan caldera complex, Colorado (1986)
    Springer
    Contributions to mineralogy and petrology 92 (1986), S. 146-156 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Oxygen isotope compositions were measured on 129 quartz, feldspar, and biotite phenocrysts from ash-flow tuffs and lava domes erupted from the Oligocene central Nevada and central San Juan caldera complexes. Most of the ash-flow tuffs are compositionally zoned with low-phenocryst rhyolite bases and high-phenocryst quartz-latite tops, but both within individual units and throughout each of the eruptive sequences at each locality, the δ 18O values are remarkably constant. δ 18O values of the central Nevada magmas range from +9.1 to +9.8 per mil: These values are high and indicate the involvement of high-18O geosynclinal sediments in the melting process. Magmatic δ 18O values decrease by only about 0.4 per mil from the initial eruption sequence to the middle eruptive, the giant Monotony Tuff (3000 km3). The initial higher δ 18O values are reestablished in the late eruptive sequence, but decrease again by about 0.4 per mil in the latest ring-fracture eruptions. δ 18O values in the central San Juan magmas range from +6.8 to +7.5: These values are relatively low and indicate involvement of lower cratonal crust and upper mantle in the melting process. Magmatic δ 18O values decrease by about 0.4 per mil from the early sequence (Fish Canyon, Carpenter Ridge, and Mammoth Mountain Tuffs) to the late sequence (Wason Park, Nelson Mountain, and Snowshoe Mountain Tuffs). 18O/16O fractionations among phenocrysts in both Nevada and Colorado are much smaller than among corresponding minerals in plutonic granitic rocks. These fractionations also decrease from stratigraphically lower to higher samples in each cooling unit, so the 18O/16O data agree with other evidence that these represent quenched equilibrium at magmatic temperatures, and that prior to eruption the tops of the magma chambers were cooler than the deeper portions. In striking contrast to what is observed in Iceland and in the late-Tertiary to Quaternary southwest Nevada and Yellowstone caldera complexes, we have found no evidence for any low-18O rhyolitic magmas. Thus, low-18O rhyolitic magmas must be less common than heretofor believed, and their origin must be a result of special circumstances involving the timing, depth, and intensity of meteoric-hydrothermal activity. We tentatively suggest that extensional tectonics and regional rifting may be one of the prerequisites for their development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00375290
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  • 6
    Electronic Resource
    Electronic Resource
    Non-equilibrium, metasomatic18O/16O effects in upper mantle mineral assemblages (1986)
    Springer
    Contributions to mineralogy and petrology 93 (1986), S. 124-135 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Kyser, O'Neil, and Carmichael (1981, 1982) measured theδ 18O values of coexisting minerals from peridotite nodules in alkali basalts and kimberlites, interpreting the nodules as equilibrium assemblages. Based mainly on the systematics revealed inδ 18O-olivinevs. δ 18O-pyroxene diagrams, we have re-interpreted the Kyser et al. data as non-equilibrium phenomena. On suchδ-δ diagrams, the mantle nodules exhibit data arrays that cut across theΔ 18O=zero line; these arrays strongly resemble the non-equilibrium quartz-feldspar and feldspar-pyroxeneδ 18O arrays that we now know arediagnostic of hydrothermally altered plutonic igneous rocks. Thus, the peridotites appear to have been open systems that underwent metasomatic exchange with an external, oxygen-bearing fluid (CO2 magma, H2O, etc.); during this event, the relatively inert pyroxenes exchanged at a much slower rate than did the coexisting olivines and spinels. This accounts for the correlation betweenΔ 18O pyroxene-olivine and the whole-rockδ 18O of the peridotites, which is a major difficulty with the equilibrium interpretation. The metasomatic18O-enrichments of the peridotites can be related to metasomatic enrichments in LIL elements and the development of amphibole and phlogopite. This type of precursor metasomatic activity can explain the development of alkali basalt magmas, as well as leucitites and nephelinites (all of which tend to be slightly18O-rich relative to MORB, withδ 18O=+6 to +7.5). Fluids with appropriateδ 18O values to explain the open-system metasomatic effects can be produced by exchange with ancient subducted oceanic crust (eclogite). However, fluid/rock ratios of about 0.4 to 2.5 are required, indicating that this cannot be a mantle-wide phenomenon. Also, these non-equilibrium effects are apparently transient phenomena, probably associated with the eruptive events that brought the nodules to the surface; at characteristic mantle temperatures, the effects would likely disappear in a few tens of millions of years, or less, implying that the ultramafic nodules are not typical samples of the upper mantle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00963591
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  • 7
    Electronic Resource
    Electronic Resource
    87Sr/86Sr and 18O/16O isotopic systematics and geochemistry of granitoid plutons across a steeply-dipping boundary between contrasting lithospheric blocks in western Idaho (1992)
    Springer
    Contributions to mineralogy and petrology 109 (1992), S. 355-372 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A spatially abrupt geochemical boundary is preserved within four plutonic complexes along the western margin of the Cretaceous Idaho Batholith near McCall, Idaho. These intrusives ranging in composition from tonalite to granite were emplaced across a regional boundary between accreted oceanic-arc terranes and the continental margin, and their isotopic, major-element, and trace-element geochemistry provide detailed information about this change in crustal characteristics at depth, indicating that the boundary is nearly vertical and extends deep into the lithosphere. The Hazard Creek complex, emplaced west of the transition in wall-rock lithology, has initial 87Sr/86Sr (Ri) less than 0.7045 and δ18O greater than 7.5, indicating little or no continental crust in its source region; however, elevated δ18O requires some incorporation of rocks formed or altered at the earth's surface. A large shift in Ri and δ18O is observed across the 5–8 km wide Little Goose Creek complex, which was emplaced across the wall-rock boundary. This is interpreted as mixing between: (1) a basaltic or andesitic magma with low K2O and high Na2O, Al2O3, and Sr, similar to that forming the Hazard Creek complex; and (2) materials similar to Precambrian sedimentary sedimentary rocks with low Sr, high δ18O (+15) and high Ri (0.83 at 100 Ma). The Payette River complex, emplaced east of the wall-rock boundary, exhibits at least one additional component with low δ18O (+6), moderate Ri (0.708) and mafic composition. This component is inferred to be old basaltic material in the lower crust or upper mantle similar to that inferred to be a minor part of the Peninsular Ranges Batholith in SE California (Silver et al. 1979; Hill et al. 1986). The easternmost complex in the Idaho transect is made up of granites that may contain a component of granitic cratonal basement. The entire west-to-east geochemical transition from oceanic-arc magmas to cratonal magmas takes place over a lateral distance of less than 20 km. Although the zone of transitional protolith dominated by metasedimentary rocks is unusually narrow and may have been in part tectonically removed, the striking geochemical similarities between this traverse and several other transects across much broader areas of Nevada and California suggest that the craton itself was not rifted apart, but that juxtaposition of the accreted oceanic-arc terranes occurred along the preexisting craton margin. The data confirm that the isotopic geochemistry of granitoid plutons can be used as a probe of deep lithospheric character, and that major lateral variations in the lithosphere on the order of one to two kilometers in width can be recognized in favorable circumstances.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283324
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  • 8
    Electronic Resource
    Electronic Resource
    O18/O16 ratios of the Johnny Lyon granodiorite and Texas Canyon quartz monzonite plutons, Arizona, and their contact aureoles (1971)
    Springer
    Contributions to mineralogy and petrology 32 (1971), S. 138-146 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract O18/O16 ratios have been measured for 29 quartz samples, 6 whole-rocks, 3 muscovites, and 1 K-feldspar from two adjacent granitic plutons of vastly different age (about 1660 m.y, and 70 m.y.) intruded into the same type of country rock, the Precambrian Pinal schist. Sample traverses were made across 3 different contact zones of these intrusive bodies. Except for 2 quartz veins with δO18=+11.0 and + 12.3, all quartz samples collected more than 15 cm from the margin of the Early Tertiary Texas Canyon pluton are isotopically exceedingly uniform with δO18=9.47±0.11. Four quartz samples collected more than 10 m from the margin of the Precambrian Johnny Lyon pluton have δO18=10.43±0.08. Compared with previous studies of this type, only relatively minor O18-enrichments have occurred in the border zones of the plutons. This is in part because the original δO18 differences between the metasedimentary rocks and the intrusives are relatively small (only 3 to 6‰), but is mainly due to the lack of H2O in the contact zones during intrusion as a result of the general impermeability and prior dehydration of the schist. There is no isotopic evidence for significant influx of “external” H2O into either of the plutons during their crystallization and cooling. However, in roof-zones where metasedimentary rocks overlie the plutons there is a strong δO18 lowering in the contact metamorphic aureoles, indicating upward expulsion of low-O18 “magmatic” H2O into these rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383056
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  • 9
    Electronic Resource
    Electronic Resource
    Temperatures of serpentinization of ultramafic rocks based on O18/O16 fractionation between coexisting serpentine and magnetite (1971)
    Springer
    Contributions to mineralogy and petrology 32 (1971), S. 165-185 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Five lizardite-chrysotile type serpentinites from California, Guatemala and the Dominican Republic show oxygen isotope fractionations of 15.1 to 12.9 per mil between coexisting serpentine and magnetite (δO18 magnetite=−7.6 to −4.6 per mil relative to SMOW). Nine antigorites (mainly from Vermont and S. E. Pennsylvania) show distinctly smaller fractionations of 8.7 to 4.8 per mil (δO18 magnetite=−2.6 to +1.7 per mil). Two lizardite and chrysotile serpentinites dredged from the Mid-Atlantic Ridge exhibit fractionations of 10.0 and 12.4 per mil (δO18 magnetite=−6.8 and −7.9 per mil, respectively), whereas an oceanic antigorite shows a value of 8.2 per mil (δO18 magnetite=−6.2). These data all clearly indicate that the antigorites formed at higher temperatures than the chrysotilelizardites. Electron microprobe analyses of magnetites from the above samples show that they are chemically homogeneous and essentially pure Fe3O2. However, some magnetites from certain other samples that show a wide variation of Cr content also give very erratic oxygen isotopic results, suggesting non-equilibrium. An approximate serpentine-magnetite geothermometer curve was constructed by (1) extrapolation of observed O18 fractionations between coexisting chlorites and Fe-Ti oxides in low-grade pelitic schists whose isotopic temperatures are known from the quartz-muscovite O18 geothermometer, and (2) estimates of the O18 fractionation factor between chlorite and serpentine (assumed to be equal to unity). This serpentine-magnetite geothermometer suggests approximate equilibrium temperatures as follows: continental lizardite-chrysotile, 85° to 115° C; oceanic lizardite and chrysotile, 130° C and 185° C, respectively; oceanic antigorite, 235° C; and continental antigorites, 220° to 460° C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00643332
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  • 10
    Electronic Resource
    Electronic Resource
    Deep fluid circulation in alpine shear zones, Pyrenees, France: field and oxygen isotope studies (1990)
    Springer
    Contributions to mineralogy and petrology 106 (1990), S. 41-60 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A combined field, stable isotope, and whole-rock chemical study was made on late Cretaceous to Tertiary metasomatic shear zones cutting Hercynian gneisses in the Aston Massif, Pyrenees, France. Mylonitisation occurred during the early stages of Alpine compression under retrograde conditions at 400–450°C and about 10 km depth. Whole-rock δ18O values of (+11 to +12‰ in the gneisses) was lowered to +5 to +9‰ in the shear zones, with the quartz-muscovite 18O/16O fractionations of about 2 to 4‰ essentially unchanged. These 18O/16O systematics, together with δD muscovite=-40 to-50‰ indicate that large volumes of formation waters or D-rich meteoric waters passed through the shear zones during deformation. The same fluids also redistributed major elements, as shown by the correlation of δ18O shift with muscovitisation and albitisation reactions in granitic wall rocks. However, even though δ18O was universally lowered within the shear zones, the 18O/16O ratios were not homogenised, nor do they correlate in detail with the presence or absence of muscovitisation, suggesting that fluid flow was probably fracture-controlled and episodic. Field mapping shows that, along the length of a particular shear zone, muscovitisation of granite gneiss dies out 150m above the contact with underlying sillimanite gneiss. Thus, muscovitisation and albitisation of granite gneiss in shear zones and their wall rocks probably occurred during re-equilibration of acidic, chloride-rich, aqueous fluids that had previously moved upward within the shear zones through underlying sillimanite gneiss. Extremely high material-balance fluid-rock ratios (∼103) are required to explain the extent of muscovitisation along this shear zone, implying integrated fluid mass fluxes of about 108 kg/m2; this is probably close to the maximum value for other shear zones in the network. Similar volumes of a more chemically evolved fluid must have passed through the unmuscovitised mylonites, showing that the absence of alteration cannot necessarily be used to infer low values of fluid flux. For reasonable pressure gradients and time scales of fluid movement, effective permeabilities of 10-15 to 10-17 m2 are required. Such values can be accounted for by short-lived, widely-spaced cracks produced during seismic activity. A model is presented in which formation waters were seismically pumped down an underlying, shallow, southward-dipping decollement and then upward through the steeply-dipping shear zone network.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00306407
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