Abstract
Stable isotope analyses of rocks and minerals associated with the detachment fault and underlying mylonite zone exposed at Secret Creek gorge and other localities in the Ruby-East Humboldt Range metamorphic core complex in northeastern Nevada provide convincing evidence for meteoric water infiltration during mylonitization. Whole-rock δ18O values of the lower plate quartzite mylonites (≥95% modal quartz) have been lowered by up to 10 per mil compared with structurally lower, compositionally similar, unmylonitized material. Biotite from these rocks has δD values ranging from -125 to -175, compared to values of -55 to-70 in biotite from unmylonitized rocks. Mylonitized leucogranites have large disequilibrium oxygen isotope fractionations (Δ quartz-feldspar up to ∼8 per mil) relative to magmatic values (Δ quartz-feldspar∼1 to 2 per mil)). Meteoric water is the only major oxygen and hydrogen reservoir with an isotopic composition capable of generating the observed values. Fluid inclusion water from unstrained quartz in silicified breccia has a δD value of-119 which provides a plausible estimate of the δD of the infiltrating fluid, and is similar to the isotopic composition of present-day and Tertiary local meteoric water. The quartzite mylonite biotites would have been in equilibrium with such a fluid at temperatures of 480–620° C, similar to independent estimates of the temperature of mylonitization. The relatively high temperatures required for isotopic exchange between quartz and water, the occurrence of fluid inclusion trails and deformed veins in quartzite mylonites, and the spatial association of the low-18O, low-D rocks with the shear zone all constrain isotopic exchange to the mylonitic (plastic) deformation event. These observations suggest thata significant amount of meteoric water infiltrated the shear zone during mylonitization to depths of at least 5 to 10 km below the surface. The depth of penetration of meteoric fluids into the lower plate mylonites was at least 70 meters below the detachment fault. In contrast, the upper-plate unmylonitized fault slices are dominated by brittle fracture and are often intensely veined (carbonates) or silicified (volcanic rocks and breccias). The fluids associated with the veining and silicification were also meteoric as evidenced by low δ18O values of the veins, which are often 10 per mil lower than the adjacent carbonate matrix, and the exceptionally low δ18O values (down to-4.4) of the breccias. Several previous studies have documented the infiltration of meteoric fluids into the brittley deformed upper plate rocks of core complexes, but this study provides convincing evidence that surface fluids have penetrated lower plate rocks undergoing plastic deformation. It is proposed that infiltration took place as the shear zone began the transition from plastic flow to brittle fracture while the lower plate rocks were being uplifted. During this period, plastic flow and brittle fracture were operating simultaneously, perhaps allowing upper plate meteoric fluids to be seismically pumped down into the lower plate mylonites.
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References
Bickle MJ, McKenzie D (1987) The transport of heat and matter by fluids during metamorphism. Contrib Mineral Petrol 95:384–392
Blattner P, Lassey KR (1989) Stable isotope exchange fronts, Damköler numbers and fluid to rock ratios. Chem Geol 78:381–392
Buck WR (1988) Flexural rotation of normal faults. Tectonics 7:959–973
Chiba H, Chacko T, Clayton RN, Goldsmith JR (1989) Oxygen isotope fractionations involving diopside, forsterite, magnetite, and calcite: application to geothermometry. Geochim Cosmochim Acta 53:2985–2995
Clayton RN, O'Neil JR, Mayeda TK (1972) Oxygen isotope exchange between quartz and water. J Geophys Res 77:3057–3067
Clayton RN, Goldsmith JR, Mayeda TK (1989) Oxygen isotope fractionations in quartz, albite, anorthite, and calcite. Geochim Cosmochim Acta 53:725–733
Craig H (1961) Isotopic variations in meteoric waters. Science 133:1702–1703
Criss RE, Taylor HR Jr (1986) Meteoric-hydrothermal systems. In: Valley JW, Taylor HP Jr, O'Neil JR (eds) Stable isotopes in high temperature geological processes. Rev Mineral 16:373–424
Criss RE, Gregory RT, Taylor HP Jr (1987) Kinetic theory of oxygen isotope exchange between minerals and water. Geochim Cosmochim Acta 51:1099–1108
Dallmeyer RD, Snoke AW, McKee EH (1986) The Mesozoic-Cenozoic tectonothermal evolution of the Ruby Mountains-East Humboldt Range, Nevada: a cordilleran metamorphic core complex. Tectonics 5:931–954
Davis SH (1980) Structural characteristics of metamorphic core complexes, southern Arizona. Geol Soc Am Mem 153:35–78
Dokka RK, Mahaffie MJ, Snoke AW (1986) Thermochronologic evidence of major tectonic denudation associated with detachment faulting, northern Ruby Mountains-East Humboldt Range, Nevada. Tectonics 5:995–1006
England PC, Richardson SW (1977) The influence of erosion upon mineral facies of rocks from different metamorphic environments. J Geol Soc London 134:201–213
Etheridge MA, Wall VJ, Cox SF (1984) High fluid pressure during regional metamorphism and deformation: implications for mass transport and deformation mechanisms. J Geophys Res 89:4344–4358
Etheridge MA, Wall VJ, Vernon RH (1983) The role of the fluid phase during regional metamorphism and deformation. J Metamorph Geol 1:205–226
Friedman I, O'Neil JR (1977) Compilation of stable isotope fractionation factors of geochemical interest. US Geol Survey Prof Pap 440-KK
Giletti BJ (1985) The nature of oxygen transport within minerals in the presence of hydrothermal water and the role of diffusion. Chem Geol 53:197–206
Giletti BJ, Yund RA (1984) Oxygen diffusion in quartz. J Geophys Res 89:4039–4046
Gregory RT, Criss RE (1986) Isotopic exchange in open and closed systems. In: Valley JW, Taylor HP Jr, O'Neil JR (eds) Stable isotopes in high temperature geological processes. Rev Mineral 16:91–127
Gregory RT, Criss RE, Taylor HR Jr (1989) Oxygen isotope exchange kinetics of mineral pairs in closed and open systems: application to problems of hydrothermal alteration of igneous rocks and Pre-Cambrian iron formations. Chem Geol 75:1–42
Hacker BR, Yin A, Christie JM, Snoke AW (1990) Differential stress, strain rate, and temperatures of mylonitization in the Ruby Mountains, Nevada: implications for the rate and duration of uplift. J Geophys Res 95:8569–8580
Hurlow HA, Snoke AW, Hodges KV (1991) Temperature and pressure of mylonitization in a Tertiary extensional shear zone, Ruby Mountains-East Humboldt Range, Nevada: Tectonic implications. Geology 19:82–86
Kerrich R (1988) Detachment zones of Cordilleran metamorphic core complexes: thermal, fluid and metasomatic regimes. Geol Rundschau 77:157–182
Kerrich R, Hyndman D (1986) Thermal and fluid regimes in the Bitteroot lobe Sapphire block detachment zone, Montana: Evidence from 18O/16O and geologic relations. Geol Soc Am Bull 97:147–155
Kerrich R, Rehrig W (1987) Fluid motion associated with Tertiary mylonitization and detachment faulting: 18O/16O evidence from the Picacho metamorphic core complex, Arizona. Geology 15:58–62
Kistler RW, Ghent ED, O'Neil JR (1981) Petrogenesis of garnet two-mica granites in the Ruby Mountains, Nevada. J Geophys Res 86:10591–10606
Knipe RJ (1989) Deformation mechanisms-recognition from natural tectonites. J Struct Geol 11:127–146
Koons PO (1987) Some thermal and mechanical consequences of rapid uplift: an example from the Southern Alps, New Zealand. Earth Planet Sci Lett 86:307–319
LaTour TE, Barnett RL (1987) Mineralogical changes accompanying mylonitization in the Bitteroot dome of the Idaho batholith: Implications for timing of deformation. Geol Soc Am Bull 98:356–363
Lister GS, Snoke AW (1984) S−C mylonites. J Structural Geol 6:617–638
Matsuhisa T, Goldsmith JR, Clayton RN (1979) Oxygen isotope fractionation in the system quartz-albite-anorthite-water. Geochim Cosmochim Acta 43:1131–1149
McCaig AM (1984) Fluid-rock interaction in some shear zones from the Central Pyrenees. J Metamorph Geol 2:129–141
McCaig AM (1988) Deep fluid circulation in fault zones. Geology 16:867–870
McCaig AM, Wickham SM, Taylor HP Jr (1990) Deep fluid circulation in Alpine shear zones, Pyrenees, France; field and oxygen isotope studies. Contrib Mineral Petrol 106:41–60
McCrea JM (1950) On the isotopic chemistry of carbonates and a paleotemperature scale. Chem Phys 18:849–857
Miller EL, Gans PB, Garing J (1983) The Snake range decollement: an exhumed mid-Tertiary ductile-brittle transition. Tectonics 2:239–263
Noble LF (1941) Structural features of the Virgin Spring area, Death Valley, California. Geol Soc Am Bull 52:941–1000
Norton D (1984) A theory of hydrothermal systems. Ann Rev Earth Planet Sci 12:155–177
O'Neil JR (1987) Preservation of C, H, O isotopic ratios in the low temperature environment. In: Kyser TK (ed) Stable isotope geochemistry of low temperature fluids. MAC Shortcourse Handbook, vol 13, pp 85–128
O'Neil JR, Silberman ML (1974) Stable isotope relations in epithermal Au−Ag deposits. Econ Geol 69:902–909
O'Neil JR, Clayton RN, Mayeda TK (1969) Oxygen isotope fractionation in divalent metal carbonates. J Chem Phys 51:5547–5558
Peters MT, Wickham SM (1989) Petrographic and petrologic evidence for high-temperature fluid infiltration in the East Humboldt Range, northeastern Nevada. Geol Soc Am Abstr with Progr 21:327
Rehrig WA, Reynolds SJ (1980) Geologic and geochronologic reconnaissance of a northwest-trending zone of metamorphic core complexes in southern and western Arizona. In: Crittenden MD, Coney PJ, Davis GH (eds) Cordilleran metamorphic core complexes. Geol Soc Am Mem 153:131–158
Reynolds SJ, Lister GS (1987) Structural aspects of fluid-rock interactions in detachment zones. Geology 15:362–366
Roddy MS, Reynolds SJ, Smith BM, Ruiz J (1988) K-metasomatism and detachment-related mineralization, Harcuvar Mountains, Arizona. Geol Soc Am Bull 100:1627–1639
Sharma T, Clayton RN (1965) Measurement of 18O/16O ratios of total oxygen from carbonates. Geochim Cosmochim Acta 29:1347–1353
Sharp ZD, O'Neil JR, Essene EJ (1988) Oxygen isotope variations in granulite-grade iron formations: constraints on oxygen isotope diffusion and retrograde isotopic exchange. Contrib Mineral Petrol 98:490–501
Sheppard SMF, Nielsen RL, Taylor HP Jr (1969) Oxygen and hydrogen isotope ratios of clay minerals from porphyry copper deposits. Econ Geol 64:755–777
Sheppard SMF (1986) Characterization and isotopic variations in natural waters. In: Valley JW, Taylor HP Jr, O'Neil JR (eds) Stable isotopes in high temperature geological processes. Rev Mineral 16:165–183
Sibson RH (1983) Continental fault structure and the shallow earthquake source. J Geol Soc London 140:747–767
Sibson RH, Moore JMM, Rankin AH (1975) Seismic pumping — hydrothermal fluid transport mechanism. J Geol Soc Lond 131:653–659
Smith BM, Reynolds SJ, Day HW, Bodnar RJ (1991) Deep-seated fluid involvement in ductile-brittle deformation and mineralization, South Mountains metamorphic core complex, Arizona. Geol Soc Am Bull 103:559–569
Snoke AW (1980) Transition from infrastructure to suprastructure in the northern Ruby Mountains, Nevada. In: Crittenden MD, Coney PJ, Davis GH (eds) Cordilleran metamorphic core complexes. Geol Soc Am Mem 153:287–333
Snoke AW, Howard KA (1984) Geology of the Ruby Mountains-East-Humboldt Range Nevada — a Cordilleran metamorphic core complex. In: Lintz Jr (ed) Western geological excursions, vol 4. Geological Society of America 1988 Annual Meeting, Reno, Nevada, pp 260–303
Snoke AW, Lush AP (1984) Polyphase Mesozoic-Cenozoic deformational history of the northern Ruby Mountains-East Humboldt Range, Nevada. In: Lintz J Jr (ed) Western geological excursions. Geological Society of America 1988 Annual Meeting, Reno, Nevada, pp 232–260
Snoke AW, McGrew AJ, Valasek PA, Smithson SB (1990) A crustal cross-section for a terrain of superimposed shortening and extension: Ruby Mountains-East Humboldt Range metamorphic core complex, Nevada. In: Salisbury MH, Fountain DM (eds) Exposed cross sections of the continental crust. Kluwer Academic Publishers, Boston, pp 103–135
Suzuoki T, Epstein S (1976) Hydrogen isotope fractionation between OH-bearing silicate minerals and water. Geochim Cosmochim Acta 40:1229–1240
Taylor HP Jr, Epstein S (1962) Relationships between 18O/16O ratios in coexisting minerals of igneous and metamorphic rocks. Part I: principles and experimental results. Bull Geol Soc Am 73:461–480
Taylor HP Jr (1977) Water/rock interactions and the origin of H2O in granitic batholiths. J Geol Soc Lond 133:509–558
Wickham SM, Taylor HP Jr, Snoke AW (1987) Fluid-rock-melt interaction in metamorphic core complexes; a stable isotope study of the Ruby Mountains-East Humboldt Range, Nevada. GSA Abstr with Progr 19, 463
Wickham SM, Peters MT (1990) An oxygen isotope discontinuity in high-grade rocks of the East Humboldt Range, Nevada. Nature 345:150–153
Wickham SM, Taylor HP Jr, Snoke AW, O'Neil JR (1991) An oxygen and hydrogen isotope study of high-grade metamorphism and anatexis in the Ruby Mountains-East Humboldt Range Core Complex, Nevada. In: Taylor HP Jr, O'Neil JR, Kaplan IR (eds) Stable isotope geochemistry: a tribute to Samuel Epstein. The Geochemical Society, Special Publication No. 3, pp 373–390
Willden R, Kistler RW (1969) Geologic map of the Jiggs Quadrangle, Elko County, Nevada. US Geological Survey Map GQ-859, Washington, DC
Wright JE, Snoke AW (1986) Mid-Tertiary mylonitization in the Ruby Mountain-East Humboldt Range metamorphic core complex, Nevada. Geol Soc Am Abstr with Progr 18:795
Wright LA, Troxel BW (1973) Shallow-fault interpretation of Basin and Range structure, southwestern Great Basin. In: de Jong KA, Scholton B (eds) Gravity and tectonics. Wiley, New York, pp 397–407
Yin A (1989) Origin of regional, rooted low-angle faults: a mechanical model and its tectonic implications. Tectonics 8:469–482
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Fricke, H.C., Wickham, S.M. & O'Neil, J.R. Oxygen and hydrogen isotope evidence for meteoric water infiltration during mylonitization and uplift in the Ruby Mountains-East Humboldt Range core complex, Nevada. Contrib Mineral Petrol 111, 203–221 (1992). https://doi.org/10.1007/BF00348952
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DOI: https://doi.org/10.1007/BF00348952