Fluid inclusions in granulites and eclogites from the Bergen Arcs, Caledonides of W. Norway

1990 ◽  
Vol 54 (375) ◽  
pp. 145-158 ◽  
Author(s):  
T. Andersen ◽  
H. Austrheim ◽  
E. A. J. Burke
Keyword(s):  
Fluid Inclusions ◽  
Shear Zones ◽  
Granulite Facies ◽  
Mole Percent ◽  
Molar Volumes ◽  
Granulite Facies Metamorphism ◽  
Laser Raman ◽  
Granulite Metamorphism ◽  
Facies Metamorphism ◽  
Eclogite Facies

AbstractThe Grenvillian granulite-facies complex on Holsnøy island, Bergen Arcs, W. Norway, has been metamorphosed at eclogite-facies conditions during the Caledonian orogeny (ca. 425 Ma). The granulite-eclogite facies transition takes place along shear zones and fluid pathways. Mineral thermobarometry indicates PT conditions of 800–900°C and 8–10 kbar for the Proterozoic granulite facies metamorphism and 700–800°C and 16–19 kbar for the eclogite-forming event. Quartz in the granulite facies complex contains CO2 fluid inclusions with less than 2.5 mole percent N2; the molar volumes are compatible with the PT conditions of the Proterozoic granulite metamorphism. Quartz in pegmatitic quartz + omphacite and quartz + phengite/paragonite veins coeval with shear-zone eclogites contain N2 ± CO2 fluid inclusions. Combined laser Raman microanalysis and microthermometry show that the least disturbed inclusions have XCO2 = 0.1–0.3, and molar volumes less than 40 cm3/mole, which may agree with the PT conditions during Caledonian high-pressure metamorphism. Younger, low-density N2 and N2-H2O fluid inclusions are the results of decrepitation and redistribution of early inclusions during the retrograde PT evolution of the eclogites.

Melt-related metasomatism in mafic granulites of the Quetico subprovince, Ontario: constraints from O-Sr-Nd isotopic and fluid inclusion data

1999 ◽  
Vol 36 (9) ◽  
pp. 1449-1462 ◽  
Author(s):  
Y Pan ◽  
M E Fleet ◽  
F J Longstaffe
Keyword(s):  
Fluid Inclusions ◽  
Diffusion Processes ◽  
Spatial Association ◽  
Central Zone ◽  
Granulite Facies ◽  
Nd Isotope ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Isotope Data ◽  
Facies Metamorphism

Mafic granulites in the Archean Quetico subprovince, north of Manitouwadge, Ontario, occur as isolated lenses or discontinuous layers in spatial association with tonalitic leucosomes in metasedimentary rocks and exhibit concentric zoning from a biotite-rich margin to an orthopyroxene-rich outer zone and a clinopyroxene-rich central zone, with internal orthopyroxene-bearing leucosomes and, rarely, patches of relict amphibolites within the clinopyroxene-rich zone. Microstructural and microchemical evidence suggests that the mafic granulites formed from amphibolites by combined infiltration-diffusion processes in the presence of a P-F-bearing silicate melt ((P2O5)melt = 0.24-0.28 wt.%) and a CO2-rich (hypersaline?) fluid. The whole-rock and mineral δ18O values of the mafic granulites (8-9‰ V-SMOW) indicate oxygen-isotope equilibration between amphibolites (6.6-6.9‰) and associated tonalitic leucosomes (9.5-10‰) at 700-800°C. Strontium- and Nd-isotope data and U-Pb zircon ages confirm isotopic homogenization at the leucosome-amphibolite boundaries during the peak granulite-facies metamorphism at about 2650 Ma. Texturally, early CO2-rich fluid inclusions in quartz and garnet yield P-T conditions similar to those of the peak granulite-facies metamorphism. Hypersaline fluid inclusions occur in textural coexistence with the early CO2-rich inclusions, but are invariably low in homogenization temperatures (178-234°C). This study shows that silicate melts not only provide a conduit for CO2-rich fluids but also interact directly with country rocks for the formation of granulites. Also, the O-Sr-Nd isotope data show that the documented mobility of rare-earth elements in the Quetico granulite zone is localized in scale and related to anatexis of local metasedimentary rocks during the granulite-facies metamorphism.

Fluid and mineral inclusions in corundum from gem gravels in Sri Lanka

1989 ◽  
Vol 53 (373) ◽  
pp. 539-545 ◽  
Author(s):  
A. A. de Maesschalck ◽  
I. S. Oen
Keyword(s):  
Sri Lanka ◽  
Fluid Inclusions ◽  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Source Areas ◽  
Mineral Inclusions ◽  
Primary Fluid ◽  
Facies Metamorphism ◽  
Secondary Fluid

AbstractMineral and fluid inclusions were studied in seven gem corundums from gravels of three areas in Sri Lanka. All fluid inclusions are pure CO2. Microthermometry results on primary fluid inclusions suggest formation of corundum under granulite facies metamorphism (>630°C, 5.5 kbar). Secondary fluid inclusions indicate different retrograde events of post-metamorphic cooling and uplift for different source areas.

A Discussion on global tectonics in Proterozoic times - Late Proterozoic cratonization in southwest Saudi Arabia

1976 ◽  
Vol 280 (1298) ◽  
pp. 517-527 ◽  
Keyword(s):  
Saudi Arabia ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Granulite Facies ◽  
Greenschist Facies ◽  
Arabian Shield ◽  
Granulite Facies Metamorphism ◽  
Quartz Monzonite ◽  
Facies Metamorphism ◽  
Global Tectonics

Early cratonal development of the Arabian Shield of southwestern Saudi Arabia began with the deposition of calcic to calc-alkalic, basaltic to dacitic volcanic rocks, and immature sedimentary rocks that subsequently were moderately deformed, metamorphosed, and intruded about 960 Ma ago by dioritic batholiths of mantle derivation (87Sr/86Sr = 0.7029). A thick sequence of calc-alkalic andesitic to rhyodacitic volcanic rocks and volcanoclastic wackes was deposited unconformably on this neocraton. Regional greenschistfacies metamorphism, intensive deformation along north-trending structures, and intrusion of mantle-derived (87Sr/86Sr = 0.7028) dioritic to granodioritic batholiths occurred about 800 Ma. Granodiorite was emplaced as injection gneiss about 785 Ma (87Sr/86Sr = 0.7028- 0.7035) in localized areas of gneiss doming and amphibolite to granulite facies metamorphism. Deposition of clastic and volcanic rocks overlapped in time and followed orogeny at 785 Ma. These deposits, together with the older rocks, were deformed, metamorphosed to greenschist facies, and intruded by calc-alkalic plutons (87Sr/86Sr = 0.7035) between 600 and 650 Ma. Late cratonal development between 570 and 550 Ma involved moderate pulses of volcanism, deformation, metamorphism to greenschist facies, and intrusion of quartz monzonite and granite. Cratonization appears to have evolved in an intraoceanic, island-arc environment of comagmatic volcanism and intrusion.

scholarly journals Zircon U–Pb Dating and Lu-Hf Isotope of the Retrograded Eclogite from Chicheng, Northern Hebei Province, China

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xu Kong ◽  
Xueyuan Qi ◽  
Wentian Mi ◽  
Xiaoxin Dong
Keyword(s):  
Regional Metamorphism ◽  
Granulite Facies ◽  
Amphibolite Facies ◽  
Metamorphic Event ◽  
Isotopic Data ◽  
Metamorphic Condition ◽  
Eu Anomaly ◽  
Facies Metamorphism ◽  
Eclogite Facies ◽  
Plagioclase Gneiss

We report zircon U–Pb ages and Lu-Hf isotopic data from two sample of the retrograded eclogite in the Chicheng area. Two groups of the metamorphic zircons from the Chicheng retrograded eclogite were identified: group one shows characteristics of depletion in LREE and flat in HREE curves and exhibit no significant Eu anomaly, and this may imply that they may form under eclogite facies metamorphic condition; group two is rich in HREE and shows slight negative Eu anomaly indicated that they may form under amphibolite facies metamorphic condition. Zircon Lu-Hf isotopic of εHf from the Chicheng eclogite has larger span range from 6.0 to 18.0, which suggests that the magma of the eclogite protolith may be mixed with partial crustal components. The peak eclogite facies metamorphism of Chicheng eclogite may occur at 348.5–344.2 Ma and its retrograde metamorphism of amphibolite fancies may occur at ca. 325.0 Ma. The Hongqiyingzi Complex may experience multistage metamorphic events mainly including Late Archean (2494–2448 Ma), Late Paleoproterozoic (1900–1734 Ma, peak age = 1824.6 Ma), and Phanerozoic (495–234 Ma, peak age = 323.7 Ma). Thus, the metamorphic event (348.5–325 Ma) of the Chicheng eclogite is in accordance with the Phanerozoic metamorphic event of the Hongqiyingzi Complex. The eclogite facies metamorphic age of the eclogite is in accordance with the metamorphism (granulite facies or amphibolite facies) of its surrounding rocks, which implied that the tectonic subduction and exhumation of the retrograded eclogite may cause the regional metamorphism of garnet biotite plagioclase gneiss.

Sign in / Sign up

Export Citation Format

Share Document