scholarly journals Metasomatic Reactions between Archean Dunite and Trondhjemite at the Seqi Olivine Mine in Greenland

Minerals ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 85 ◽  
Author(s):  
Laura Whyatt ◽  
Stefan Peters ◽  
Andreas Pack ◽  
Christopher L. Kirkland ◽  
Tonci Balic-Zunic ◽  
...  
Keyword(s):  
Isotope Analysis ◽  
Fluid Phase ◽  
Granulite Facies ◽  
Zircon Crystal ◽  
Compositional Gradient ◽  
Granulite Facies Metamorphism ◽  
Icp Ms ◽  
Ultramafic Complex ◽  
Facies Metamorphism

A metasomatic zone formed between the contact of a 2940 ± 5 Ma intrusive trondhjemite sheet in the Archean dunite of the Seqi Ultramafic Complex, SW Greenland, consists of three distinct mineral zones dominated by (1) talc, (2) anthophyllite, and (3) phlogopite. These zones supposedly resulted from a process of dissolution of olivine by silica rich fluid residual from the trondhjemite magma, with crystallization of secondary minerals along a compositional gradient in the fluid phase. A zircon crystal inclusion in a large (4 cm) olivine porphyroblast was dated in situ via LA-ICP-MS U–Pb isotope analysis, yielding a weighted mean 207Pb/206Pb age of 2963 ± 1 Ma, which coincides with granulite facies metamorphism and potential dehydration. Considering phase relations appropriate for the dunite composition, we deduced the talc forming conditions to be at temperatures of 600–650 °C and at a pressure below 1 GPa. This is supported by oxygen isotope data for talc, anthophyllite and phlogopite in the metasomatic zone, which suggests formation in the temperature range of 600–700 °C from fluids that had a δ18O of ~8‰ and a Δ’17O0.528 of about −40 ppm, i.e., from fluids that could have been derived from the late stage trondhjemite sheet.

New constraints on metamorphism in the Highjump Archipelago, East Antarctica

2016 ◽  
Vol 28 (6) ◽  
pp. 487-503 ◽  
Author(s):  
Naomi M. Tucker ◽  
Martin Hand
Keyword(s):  
Granulite Facies ◽  
East Antarctica ◽  
Partial Replacement ◽  
Granulite Facies Metamorphism ◽  
Metasedimentary Rocks ◽  
Facies Metamorphism ◽  
Antarctic Expedition ◽  
Higher Temperature ◽  
Temperature And Pressure

AbstractThe age and conditions of metamorphism in the Highjump Archipelago, East Antarctica, are investigated using samples collected during the 1986 Australian Antarctic expedition to the Bunger Hills–Denman Glacier region. In situ U-Pb dating of monazite from three metasedimentary rocks yields ages between c. 1240–1150 Ma and a weighted mean 207Pb/206Pb age of 1183±8 Ma, consistent with previous constraints on the timing of metamorphism in this region and Stage 2 of the Albany–Fraser Orogeny in south-western Australia. This age is interpreted to date the development of garnet ± sillimanite ± rutile-bearing assemblages that formed at c. 850–950°C and 6–9 kbar. Peak granulite facies metamorphism was followed by decompression, evidenced largely by the partial replacement of garnet by cordierite. These new pressure–temperature determinations suggest that the Highjump Archipelago attained slightly higher temperature and pressure conditions than previously proposed and that the rocks probably experienced a clockwise pressure–temperature evolution.

scholarly journals Dating Prograde Amphibolite and Granulite Facies Metamorphism Using In Situ Monazite U‐Pb SHRIMP Analysis

2007 ◽  
Vol 115 (6) ◽  
pp. 691-705 ◽  
Author(s):  
C. J. Forbes ◽  
D. Giles ◽  
P. G. Betts ◽  
R. Weinberg ◽  
P. D. Kinny
Keyword(s):  
Granulite Facies ◽  
Granulite Facies Metamorphism ◽  
Facies Metamorphism

scholarly journals Supplemental Material: Building a continental arc section: Constraints from Paleozoic granulite-facies metamorphism, anatexis, and magmatism in the northern margin of the Qilian Block, northern Tibet Plateau

2021 ◽  
Author(s):  
Yinbiao Peng ◽  
Yu Shengyao ◽  
et al.
Keyword(s):  
Volcanic Rocks ◽  
Granulite Facies ◽  
Tibet Plateau ◽  
Granulite Facies Metamorphism ◽  
Northern Margin ◽  
Icp Ms ◽  
Continental Arc ◽  
Facies Metamorphism ◽  
Data Tables ◽  
Representative Samples

Tables S1–S4: Representative electron microprobe data; Tables S5–S16: Zircon U‐Th‐Pb LA‐ICP‐MS data for nine representative samples; Tables S17–S22: LA‐MC‐ICP‐MS Lu‐Hf isotope data for 6 representative samples; Table S23: Major and trace element compositions of plutons and volcanic rocks.

scholarly journals Supplemental Material: Building a continental arc section: Constraints from Paleozoic granulite-facies metamorphism, anatexis, and magmatism in the northern margin of the Qilian Block, northern Tibet Plateau

2021 ◽  
Author(s):  
Yinbiao Peng ◽  
Yu Shengyao ◽  
et al.
Keyword(s):  
Volcanic Rocks ◽  
Granulite Facies ◽  
Tibet Plateau ◽  
Granulite Facies Metamorphism ◽  
Northern Margin ◽  
Icp Ms ◽  
Continental Arc ◽  
Facies Metamorphism ◽  
Data Tables ◽  
Representative Samples

Tables S1–S4: Representative electron microprobe data; Tables S5–S16: Zircon U‐Th‐Pb LA‐ICP‐MS data for nine representative samples; Tables S17–S22: LA‐MC‐ICP‐MS Lu‐Hf isotope data for 6 representative samples; Table S23: Major and trace element compositions of plutons and volcanic rocks.

Iron-titanium oxides as an indicator of the role of the fluid phase during the cooling of granites metamorphosed to granulite grade

1980 ◽  
Vol 43 (329) ◽  
pp. 623-631 ◽  
Author(s):  
Hugh R. Rollinson
Keyword(s):  
Fluid Phase ◽  
Granulite Facies ◽  
Granitic Rocks ◽  
Titanium Oxides ◽  
Cooling History ◽  
Granulite Facies Metamorphism ◽  
North West ◽  
Facies Metamorphism ◽  
History Of

SummaryA detailed electron probe study of irontitanium oxide intergrowths from slowly cooled granitic rocks from the granulite grade, Archaean Scourian complex of north-west Scotland has yielded a wealth of information about magmatic and metamorphic temperatures, subsolidus cooling, and the behaviour of the fluid phase during cooling. Five stages are documented in the cooling history of granites and trondhjemites which include: (i) magmatic-subsolidus cooling (1035 °C–890 °C); (ii) granulite facies metamorphism and the accompanied expulsion of a hydrous fluid phase (890 °C–830 °C); (iii) subsolidus cooling following the peak of the granulite facies metamorphism (830 °C–660 °C); (iv) the localized reintroduction of water into the rocks during retrogression (660 °C–530 °C) and (v) subsolidus cooling and re-equilibration in the presence of a finite amount of H2O (530 °C–320 °C).

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