Kyanite eclogite thermobarometry and evidence for thrusting of UHP over HP metamorphic rocks, Nordøyane, Western Gneiss Region, Norway
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Michael P. Terry
,
Peter Robinson
Abstract
Quantitative estimates of metamorphic conditions are combined with previously reported structural analysis to develop the thermotectonic evolution of two separate lithotectonic units metamorphosed during the Late Silurian-Early Devonian collision between Baltica and Laurentia. A structurally higher plate, regionally correlated with the Blåhø Nappe, contains kyanite eclogites associated with microdiamond-bearing kyanite-garnet-graphite gneiss on the north coast of Fjørtoft and correlated with kyanite eclogites at Nogva, Flemsøya. The kyanite eclogites, containing the assemblage kyanite- garnet-omphacite-coesite (now polycrystalline quartz pseudomorphs) ± zoisite ± phengite, yield conditions of 820 °C and 34-39 kbar at Fjørtoft and of 820 °C and 30-36 kbar at Nogva, best characterized by two recently recalibrated geothermobarometers. The conditions at Fjørtoft overlap the diamond-graphite phase boundary and represent the first quantitative petrologic determination of UHP diamond-forming conditions in crustal rocks outside the Dabie Mountains, China and the Kokchetav Massif, Kazahkstan. In a structurally lower plate, eclogitized mylonite with the assemblage kyanite-garnet-omphacite-quartz-oligoclase, produced from the mid-Proterozoic Haram Gabbro that has intruded diorite country rock, yields 780 °C and 18 kbar. This result agrees with other normal HP estimates by Mørk (1985) from partially to completely eclogitized gabbro in the same unit on Flemsøya. We propose that the UHP plate reached a maximum depth of 125 km and then experienced 65 km of exhumation during top-southeast thrusting that brought it into contact with the HP plate. Following this, both plates were exhumed together until reaching a depth of 37 km where they experienced extensive amphibolite-facies re-equilibration and top-west or left-lateral shearing. Temporal details of these histories were determined by monazite U-Th-Pb geochronology described in a companion paper
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Patterns of mineral occurrence in metamorphic rocks
- A double magmatic heat pump at the core-mantle boundary
- High-temperature contact metamorphism of calc-silicate xenoliths in the Kiglapait Intrusion, Labrador
- Multiple pyroxene and amphibole assemblages in the amphibolite facies: Bulk compositional controls
- Margarite-corundum phyllites from the Appalachian orogen of South Carolina: Mineralogy and metamorphic history
- Continuous metamorphic gradient documented by graphitization and K-Ar age, southeast Otago, New Zealand
- Kyanite eclogite thermobarometry and evidence for thrusting of UHP over HP metamorphic rocks, Nordøyane, Western Gneiss Region, Norway
- Monazite geochronology of UHP and HP metamorphism, deformation, and exhumation, Nordøyane, Western Gneiss Region, Norway
- Solubilities of noble metals in Fe-containing silicate melts as derived from experiments in Fe-free systems
- Water speciation in silicate glasses and melts: Langmuir limited site model
- The ab initio study of the stability of low temperature Al/Si ordered albite, NaAlSi3O8
- The heat capacity of MgCr2O4, FeCr2O4, and Cr2O3 at low temperatures and derived thermodynamic properties
- Thermodynamics of the R3̅ to R3̅c phase transition in the ilmenite-hematite solid solution
- An ab initio study of hydrogarnets
- Short-range order in synthetic aluminous tremolites: An infrared and triple-quantum MAS NMR study
- In-situ Raman spectroscopy of quartz: A pressure sensor for hydrothermal diamond-anvil cell experiments at elevated temperatures
- Modification of the hydroxyl surface of potassium acetate intercalated halloysite between 25 and 300 °C
- On the occurrence of anomalous fission tracks in apatite and titanite
- Reactivity of surface sites on fractured arsenopyrite (FeAsS) toward oxygen
- Surface area and porosity of primary silicate minerals
- Charge contrast imaging of geological materials in the environmental scanning electron microscope
- Chemical fine structure of Franciscan jadeitic pyroxene from Ward Creek, Cazadero area, California
- Crystal structure of CaMg2Al6O12, a new Al-rich high pressure form
- The crystal structure of “Tetragonal Almandine-Pyrope Phase” (TAPP): A reexamination
- The crystal structure of tetranatrolite from Mont Saint-Hilaire, Québec, and its chemical and structural relationship to paranatrolite and gonnardite
- Elyite, Pb4Cu(SO4)O2(OH)4·H2O: Crystal structure and new data
- Dukeite, Bi3+24Cr86+O57(OH)6(H2O)3, a new mineral from Brejaúba, Minas Gerais, Brazil: Description and crystal structure
- Pseudosinhalite is a structural isotype of chondrodite
- Structure type and bulk modulus of Fe3S, a new iron-sulfur compound
- Single crystal elasticity of lawsonite
- In situ measurement of viscosity of liquids in the Fe-FeS system at high pressures and temperatures
Articles in the same Issue
- Patterns of mineral occurrence in metamorphic rocks
- A double magmatic heat pump at the core-mantle boundary
- High-temperature contact metamorphism of calc-silicate xenoliths in the Kiglapait Intrusion, Labrador
- Multiple pyroxene and amphibole assemblages in the amphibolite facies: Bulk compositional controls
- Margarite-corundum phyllites from the Appalachian orogen of South Carolina: Mineralogy and metamorphic history
- Continuous metamorphic gradient documented by graphitization and K-Ar age, southeast Otago, New Zealand
- Kyanite eclogite thermobarometry and evidence for thrusting of UHP over HP metamorphic rocks, Nordøyane, Western Gneiss Region, Norway
- Monazite geochronology of UHP and HP metamorphism, deformation, and exhumation, Nordøyane, Western Gneiss Region, Norway
- Solubilities of noble metals in Fe-containing silicate melts as derived from experiments in Fe-free systems
- Water speciation in silicate glasses and melts: Langmuir limited site model
- The ab initio study of the stability of low temperature Al/Si ordered albite, NaAlSi3O8
- The heat capacity of MgCr2O4, FeCr2O4, and Cr2O3 at low temperatures and derived thermodynamic properties
- Thermodynamics of the R3̅ to R3̅c phase transition in the ilmenite-hematite solid solution
- An ab initio study of hydrogarnets
- Short-range order in synthetic aluminous tremolites: An infrared and triple-quantum MAS NMR study
- In-situ Raman spectroscopy of quartz: A pressure sensor for hydrothermal diamond-anvil cell experiments at elevated temperatures
- Modification of the hydroxyl surface of potassium acetate intercalated halloysite between 25 and 300 °C
- On the occurrence of anomalous fission tracks in apatite and titanite
- Reactivity of surface sites on fractured arsenopyrite (FeAsS) toward oxygen
- Surface area and porosity of primary silicate minerals
- Charge contrast imaging of geological materials in the environmental scanning electron microscope
- Chemical fine structure of Franciscan jadeitic pyroxene from Ward Creek, Cazadero area, California
- Crystal structure of CaMg2Al6O12, a new Al-rich high pressure form
- The crystal structure of “Tetragonal Almandine-Pyrope Phase” (TAPP): A reexamination
- The crystal structure of tetranatrolite from Mont Saint-Hilaire, Québec, and its chemical and structural relationship to paranatrolite and gonnardite
- Elyite, Pb4Cu(SO4)O2(OH)4·H2O: Crystal structure and new data
- Dukeite, Bi3+24Cr86+O57(OH)6(H2O)3, a new mineral from Brejaúba, Minas Gerais, Brazil: Description and crystal structure
- Pseudosinhalite is a structural isotype of chondrodite
- Structure type and bulk modulus of Fe3S, a new iron-sulfur compound
- Single crystal elasticity of lawsonite
- In situ measurement of viscosity of liquids in the Fe-FeS system at high pressures and temperatures
