A new UHP metamorphic complex in the ~1.8 Ga Nagssugtoqidian Orogen of West Greenland
-
William E. Glassley
,
John A. Korstgård
Abstract
The Nagssugtoqidian Orogen is a ca. 1.8 Ga belt of east-west trending, highly deformed rocks that bisects central Greenland. Although a variety of data have suggested this belt marks the location of a continent-continent collision zone, evidence of subduction has been lacking. We report here mineralogical evidence from four samples within a well-defined lithologic unit of metabasic and metasedimentary ocean floor rocks of a previously unrecognized UHP metamorphic episode. The UHP episode is recorded by remnants of orthopyroxene exsolved from majoritic garnet, graphitized diamond, exsolution of rutile from garnet and pyroxenes, exsolution of magnetite from olivine, and complex exsolution textures in ortho- and clinopyroxenes (including omphacite). Associated with these mineralogical features is an unusual occurrence of quartz needles in Mn-rich fayalite. From textural characteristics, we infer that the quartz needles exsolved from the fayalite. To our knowledge, olivine with exsolved silica has not been reported. We note, however, that experimental studies have shown that b-spinel can incorporate excess silica. We therefore speculate these quartz needles may be silica that exsolved from Mn-rich ahrensite, the Fe analog of ringwoodite, upon decompression and inversion to fayalite. If correct, this occurrence would be the first reported sample of naturally occurring olivine (fayalite) that inverted from ahrensite. Corroborating an early UHP history are reaction relationships that delineate a path through high-pressure and high-temperature conditions during decompression. P-T conditions inferred for the UHP episode are ~7 GPa at ~975 °C. The unusually low T for this UHP system at ~1.8 Ga may reflect either very rapid subduction rates at that time, or unexpectedly cool mantle conditions. Preservation of the UHP assemblages probably is due, in large part, to the exceptionally low aH2O during decompression and cooling. These UHP rocks establish that the location of the subduction and suture zones that must have existed prior to and during the collision of continents was along what is now the northern edge of the Nordre Strømfjord shear zone.
© 2014 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
- Highlights and Breakthroughs
- An alternative to alteration and melting processes in the Earth: Reaction between hydrogen (H2) and oxide components in the Earth in space and time
- The crystallographic and petrogenetic significance of pegmatite phosphates
- Small grains and big implications: Accessory Ti- and Zr-minerals as petrogenetic indicators in HP and UHP marbles
- What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates
- Natural Fe-bearing oxides and sulfates from the Rio Tinto Mars analog site: Critical assessment of VNIR reflectance spectroscopy, laser Raman spectroscopy, and XRD as mineral identification tools
- Dissolution rates of amorphous Al- and Fe-phosphates and their relevance to phosphate mobility on Mars
- Stability and spectroscopy of Mg sulfate minerals: Role of hydration on sulfur isotope partitioning
- Synthesis and characterization of the Mars-relevant phosphate minerals Fe- and Mg-whitlockite and merrillite and a possible mechanism that maintains charge balance during whitlockite to merrillite transformation
- Minerals in the Human Body
- Determination of the concentration of asbestos minerals in highly contaminated mine tailings: An example from abandoned mine waste of Crètaz and Èmarese (Valle d’Aosta, Italy)
- Spinels Renaissance: The past, present, and future of those ubiquitous minerals and materials
- Pressure-volume equation of state for chromite and magnesiochromite: A single-crystal X-ray diffraction investigation
- The systematics of the spinel-type minerals: An overview
- Chemistry and Mineralogy of Earth’s Mantle
- Formation of SiH4 and H2O by the dissolution of quartz in H2 fluid under high pressure and temperature
- Identifying the spin transition in Fe2+-rich MgSiO3 perovskite from X-ray diffraction and vibrational spectroscopy
- Mantle-derived guyanaite in a Cr-omphacitite xenolith from Moses Rock diatreme, Utah
- Pluton assembly and the genesis of granitic magmas: Insights from the GIC pluton in cross section, Sierra Nevada Batholith, California
- First-principles molecular dynamics simulations of MgSiO3 glass: Structure, density, and elasticity at high pressure
- A new UHP metamorphic complex in the ~1.8 Ga Nagssugtoqidian Orogen of West Greenland
- Visible and short-wave infrared reflectance spectroscopy of REE fluorocarbonates
- Volatile abundances of coexisting merrillite and apatite in the martian meteorite Shergotty: Implications for merrillite in hydrous magmas
- Sb5+ and Sb3+ substitution in segnitite: A new sink for As and Sb in the environment and implications for acid mine drainage
- First-principles elasticity of monocarboaluminate hydrates
- Substitution of Ti3+ and Ti4+ in hibonite (CaAl12O19)
- Exploring the effect of lithium on pegmatitic textures: An experimental study
- XANES measurements of Cr valence in olivine and their applications to planetary basalts
- Z-contrast imaging and ab initio study on “d” superstructure in sedimentary dolomite
- Influence of temperature, pressure, and chemical composition on the electrical conductivity of granite
- Ti- and Zr-minerals in calcite-dolomite marbles from the ultrahigh-pressure Kimi Complex, Rhodope mountains, Greece: Implications for the P-T evolution based on reaction textures, petrogenetic grids, and geothermobarometry
- Ab initio thermodynamic and thermophysical properties of sapphirine end-members in the join Mg4Al8Si2O20-Mg3Al10SiO20
- The relation between Li ↔ Na substitution and hydrogen bonding in five-periodic singlechain silicates nambulite and marsturite: A single-crystal X-ray study
- Natural analogs of belite sulfoaluminate cement clinkers from Negev Desert, Israel
- Australian sedimentary opal-A and its associated minerals: Implications for natural silica sphere formation
- The 2H and 3R polytypes of sabieite, NH4Fe3+(SO4)2, from a natural fire in an oil-bearing shale near Milan, Ohio
- Letter
- Te-rich raspite, Pb(W0.56Te0.44)O4, from Tombstone, Arizona, U.S.A.: The first natural example of Te6+ substitution for W6+
- New Mineral Names
- Book Review
Articles in the same Issue
- Highlights and Breakthroughs
- An alternative to alteration and melting processes in the Earth: Reaction between hydrogen (H2) and oxide components in the Earth in space and time
- The crystallographic and petrogenetic significance of pegmatite phosphates
- Small grains and big implications: Accessory Ti- and Zr-minerals as petrogenetic indicators in HP and UHP marbles
- What Lurks in the Martian Rocks and Soil? Investigations of Sulfates, Phosphates, and Perchlorates
- Natural Fe-bearing oxides and sulfates from the Rio Tinto Mars analog site: Critical assessment of VNIR reflectance spectroscopy, laser Raman spectroscopy, and XRD as mineral identification tools
- Dissolution rates of amorphous Al- and Fe-phosphates and their relevance to phosphate mobility on Mars
- Stability and spectroscopy of Mg sulfate minerals: Role of hydration on sulfur isotope partitioning
- Synthesis and characterization of the Mars-relevant phosphate minerals Fe- and Mg-whitlockite and merrillite and a possible mechanism that maintains charge balance during whitlockite to merrillite transformation
- Minerals in the Human Body
- Determination of the concentration of asbestos minerals in highly contaminated mine tailings: An example from abandoned mine waste of Crètaz and Èmarese (Valle d’Aosta, Italy)
- Spinels Renaissance: The past, present, and future of those ubiquitous minerals and materials
- Pressure-volume equation of state for chromite and magnesiochromite: A single-crystal X-ray diffraction investigation
- The systematics of the spinel-type minerals: An overview
- Chemistry and Mineralogy of Earth’s Mantle
- Formation of SiH4 and H2O by the dissolution of quartz in H2 fluid under high pressure and temperature
- Identifying the spin transition in Fe2+-rich MgSiO3 perovskite from X-ray diffraction and vibrational spectroscopy
- Mantle-derived guyanaite in a Cr-omphacitite xenolith from Moses Rock diatreme, Utah
- Pluton assembly and the genesis of granitic magmas: Insights from the GIC pluton in cross section, Sierra Nevada Batholith, California
- First-principles molecular dynamics simulations of MgSiO3 glass: Structure, density, and elasticity at high pressure
- A new UHP metamorphic complex in the ~1.8 Ga Nagssugtoqidian Orogen of West Greenland
- Visible and short-wave infrared reflectance spectroscopy of REE fluorocarbonates
- Volatile abundances of coexisting merrillite and apatite in the martian meteorite Shergotty: Implications for merrillite in hydrous magmas
- Sb5+ and Sb3+ substitution in segnitite: A new sink for As and Sb in the environment and implications for acid mine drainage
- First-principles elasticity of monocarboaluminate hydrates
- Substitution of Ti3+ and Ti4+ in hibonite (CaAl12O19)
- Exploring the effect of lithium on pegmatitic textures: An experimental study
- XANES measurements of Cr valence in olivine and their applications to planetary basalts
- Z-contrast imaging and ab initio study on “d” superstructure in sedimentary dolomite
- Influence of temperature, pressure, and chemical composition on the electrical conductivity of granite
- Ti- and Zr-minerals in calcite-dolomite marbles from the ultrahigh-pressure Kimi Complex, Rhodope mountains, Greece: Implications for the P-T evolution based on reaction textures, petrogenetic grids, and geothermobarometry
- Ab initio thermodynamic and thermophysical properties of sapphirine end-members in the join Mg4Al8Si2O20-Mg3Al10SiO20
- The relation between Li ↔ Na substitution and hydrogen bonding in five-periodic singlechain silicates nambulite and marsturite: A single-crystal X-ray study
- Natural analogs of belite sulfoaluminate cement clinkers from Negev Desert, Israel
- Australian sedimentary opal-A and its associated minerals: Implications for natural silica sphere formation
- The 2H and 3R polytypes of sabieite, NH4Fe3+(SO4)2, from a natural fire in an oil-bearing shale near Milan, Ohio
- Letter
- Te-rich raspite, Pb(W0.56Te0.44)O4, from Tombstone, Arizona, U.S.A.: The first natural example of Te6+ substitution for W6+
- New Mineral Names
- Book Review
