In situ SHRIMP U–Pb dating of monazite integrated with petrology and textures: Does bulk composition control whether monazite forms in low-Ca pelitic rocks during amphibolite facies metamorphism?

Neoproterozoic pegmatite from Skoddefjellet, Wedel Jarlsberg Land, Spitsbergen: Additional evidence forc. 640 Ma tectonothermal event in the Caledonides of SvalbardNeoproterozoic (c. 640 Ma) amphibolite facies metamorphism and deformation have been shown recently to have affected the Isbjørnhamna and Eimfjellet Complex of Wedel Jarlsberg Land in southwestern Spitsbergen. New SHRIMP zircon U-Pb andin situelectron microprobe monazite and uraninite U-Th-total Pb ages are presented here on a pegmatite occurring within the Isbjørnhamna metasedimentary rocks. Although the dated zircons are full of inclusions, have high-U contents and are metamict and hence have experienced notable Pb-loss, the new Cryogenian ages are consistent with the age of regional metamorphism of the host metasediments, providing additional evidence for a clear distinction of the Southwestern Province from the other parts of the Svalbard Caledonides.

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Late Neoproterozoic amphibolite-facies metamorphism of a pre-Caledonian basement block in southwest Wedel Jarlsberg Land, Spitsbergen: new evidence from U–Th–Pb dating of monazite

Geological Magazine ◽

10.1017/s001675680800530x ◽

2008 ◽

Vol 145 (6) ◽

pp. 822-830 ◽

Cited By ~ 34

Author(s):

JAROSLAW MAJKA ◽

STANISLAW MAZUR ◽

MACIEJ MANECKI ◽

JERZY CZERNY ◽

DANIEL K. HOLM

Keyword(s):

Amphibolite Facies ◽

Svalbard Archipelago ◽

Passive Margins ◽

Metamorphic History ◽

Facies Metamorphism ◽

Late Neoproterozoic ◽

The Baltic ◽

New Evidence ◽

Greenschist Facies Metamorphism

AbstractSouthwest Spitsbergen, Wedel Jarlsberg Land, consists of two Proterozoic crustal blocks with differing metamorphic histories. Both blocks experienced Caledonian greenschist-facies metamorphism, but only the southern block records an earlier pervasive M1 amphibolite-facies metamorphism and strong deformational fabric. In situ EMPA total-Pb monazite geochronology from both matrix and porphyroblast inclusion results indicate that the older M1 metamorphism occurred at 643 ± 9 Ma, consistent with published cooling ages of c. 620 Ma (hornblende) and 580 Ma (mica) obtained from these same rocks. This region thus contains a lithostratigraphic profile and metamorphic history which are unique within the Svalbard Archipelago. Documentation of a pervasive late Neoproterozoic Barrovian metamorphism is difficult to reconcile with a quiescent non-tectonic regime typically inferred for this region, based on the occurrence of rift-drift sequences on the Baltic and Laurentian passive margins. Instead, our new metamorphic age implies an exotic origin of the pre-Devonian basement exposed in SW Spitsbergen and supports models of terrane assembly postulated for the Svalbard Archipelago.

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DIVING DEEPER INTO THE PICURIS OROGEN: UPPER AMPHIBOLITE FACIES METAMORPHISM AND BRITTLE DEFORMATION ALONG THE PLOMO SHEAR ZONE

10.1130/abs/2020am-354334 ◽

2020 ◽

Author(s):

Adrian E. Castro ◽

◽

Chloe Bonamici ◽

Christopher G. Daniel ◽

Danielle Shannon Sulthaus

Keyword(s):

Shear Zone ◽

Amphibolite Facies ◽

Brittle Deformation ◽

Facies Metamorphism

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REGIONAL LOW-PRESSURE AMPHIBOLITE-FACIES METAMORPHISM AT THE PIPE II MINE, THOMPSON NICKEL BELT, MANITOBA, AND COMPARISON OF METAMORPHIC ISOGRADS IN METAPELITES AND META-IRON FORMATIONS

The Canadian Mineralogist ◽

10.3749/canmin.49.3.721 ◽

2011 ◽

Vol 49 (3) ◽

pp. 721-747 ◽

Cited By ~ 5

Author(s):

C. G. Coueslan ◽

D. R. M. Pattison ◽

D. K. Tinkham

Keyword(s):

Low Pressure ◽

Amphibolite Facies ◽

Facies Metamorphism ◽

Iron Formations

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Metamorphic evolution and U-Pb zircon SHRIMP geochronology of the Belizário ultramafic amphibolite, Encantadas Complex, southernmost Brazil

Anais da Academia Brasileira de Ciências ◽

10.1590/s0001-37652003000300010 ◽

2003 ◽

Vol 75 (3) ◽

pp. 393-403 ◽

Cited By ~ 20

Author(s):

Léo A. Hartmann ◽

João O.S. Santos ◽

Jayme A.D. Leite ◽

Carla C. Porcher ◽

Neal J. Mcnaughton

Keyword(s):

Ultramafic Rock ◽

Greenschist Facies ◽

Amphibolite Facies ◽

Rio De La Plata ◽

Metamorphic Evolution ◽

Río De La Plata ◽

La Plata ◽

Shrimp Geochronology ◽

Facies Metamorphism ◽

Magnesian Basalt

The integrated investigation of metamorphism and zircon U-Pb SHRIMP geochronology of the Belizário ultramafic amphibolite from southernmost Brazil leads to a better understanding of the processes involved in the generation of the Encantadas Complex. Magmatic evidence of the magnesian basalt or pyroxenite protolith is only preserved in cores of zircon crystals, which are dated at 2257 ± 12 Ma. Amphibolite facies metamorphism M1 formed voluminous hornblende in the investigated rock possibly at 1989 ± 21 Ma. This ultramafic rock was re-metamorphosed at 702±21 Ma during a greenschist facies eventM2; the assemblage actinolite + oligoclase + microcline + epidote + titanite + monazite formed by alteration of hornblende. The metamorphic events are probably related to the Encantadas Orogeny (2257±12 Ma) and Camboriú Orogeny (~ 1989 Ma) of the Trans-Amazonian Cycle, followed by an orogenic event (702±21 Ma) of the Brasiliano Cycle. The intervening cratonic period (2000-700 Ma) corresponds to the existence of the Supercontinent Atlantica, known regionally as the Rio de la Plata Craton.

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

Shock and Vibration ◽

10.1155/2021/1445653 ◽

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.

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X-Ray Fluorescence Analysis of a Gold Ibex and other Artifacts from Akrotiri

HNPS Proceedings ◽

10.12681/hnps.2224 ◽

2019 ◽

Vol 11 ◽

Author(s):

A. G. Karydas ◽

T. Pantazis ◽

C. Doumas ◽

A. Vlachopoulos ◽

P. Nomikos ◽

...

Keyword(s):

Bulk Composition ◽

Fluorescence Analysis ◽

Wall Painting ◽

Inorganic Elements ◽

X Ray ◽

Wide Range ◽

Soldering Technology ◽

Excavation Area

In-situ X-ray fluorescence analysis (XRF) of ancient artifacts from the excavation area was performed using a novel X-ray instrumentation, composed of a portable silicon PIN thermoelectrically cooled X-ray detector, a miniature X-ray source, and portable data acquisition devices. The main objective of the analyses in Akrotiri was to explore the potential of the technique to provide answers to a wide range of archaeometric questions regarding the bulk composition of metal alloys, especially of gold, the characterization of corrosion products in bronze artifacts, identification of inorganic elements which are fingerprints of the minerals used in wall-painting pigments, and of the painting materials and techniques used for the decoration of clay vase surfaces. Among the analysed artifacts are a unique gold ibex, a bronze dagger and blade, various pigments from the wall paintings of room 3 in Xeste 3, decoration pigments from rosettes of faience, a bichrome jug, and other clay vases. The results of the in-situ XRF survey, primarily those of the bulk composition and soldering technology of the gold ibex, are discussed and compared with literature.

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Mapping in the Fiskefjord area, southern West Greenland

Rapport Grønlands Geologiske Undersøgelse ◽

10.34194/rapggu.v110.7797 ◽

1982 ◽

Vol 110 ◽

pp. 55-57

Author(s):

A.A Garde ◽

V.R McGregor

Keyword(s):

Granulite Facies ◽

Amphibolite Facies ◽

Isotopic Age ◽

Supracrustal Rock ◽

Granulite Facies Metamorphism ◽

West Greenland ◽

Facies Metamorphism ◽

Geological Work ◽

Age Determinations

Previous geological work on the 1:100000 map sheet 64 V.l N (fig. 15) includes published maps of smaller areas by Berthelsen (1960, 1962) and Lauerma (1964), mapping by Kryolitselskabet Øresund A/S (Bridgwater et al., 1976) and mapping by GGU geologists for the 1:500000 map sheet Frederikshåb Isblink - Søndre Strømfjord (Allaart et al., 1977, 1978). The Amltsoq and Niik gneisses and Malene supracrustal rock units south and east of Godthåbsfjord have not so far been correlated with rocks in the Fiskefjord area. Godthåbsfjord separates the granulite facies gneisses in Nordlandet from amphibolite facies Nûk gneisses on Sadelø and Bjørneøen; the granulite facies metamorphism occurred at about 2850 m.y. (Black et al., 1973), while no published isotopic age determinations from the Fiskefjord area itself are available.

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Analyses of Eutectoid Phase Transformations in Nb–SilicideIn SituComposites

Microscopy and Microanalysis ◽

10.1017/s1431927604040760 ◽

2004 ◽

Vol 10 (4) ◽

pp. 470-480 ◽

Cited By ~ 17

Author(s):

B.P. Bewlay ◽

S.D. Sitzman ◽

L.N. Brewer ◽

M.R. Jackson

Keyword(s):

Crystal Structure ◽

Phase Transformation ◽

High Temperature ◽

Room Temperature ◽

Bulk Composition ◽

High Strength ◽

Eutectoid Decomposition ◽

Quaternary Alloys ◽

Temperature Fracture

Nb–silicide in situ composites have great potential for high-temperature turbine applications. Nb–silicide composites consist of a ductile Nb-based solid solution together with high-strength silicides, such as Nb5Si3and Nb3Si. With the appropriate addition of alloying elements, such as Ti, Hf, Cr, and Al, it is possible to achieve a promising balance of room-temperature fracture toughness, high-temperature creep performance, and oxidation resistance. In Nb–silicide composites generated from metal-rich binary Nb-Si alloys, Nb3Si is unstable and experiences eutectoid decomposition to Nb and Nb5Si3. At high Ti concentrations, Nb3Si is stabilized to room temperature, and the eutectoid decomposition is suppressed. However, the effect of both Ti and Hf additions in quaternary alloys has not been investigated previously. The present article describes the discovery of a low-temperature eutectoid phase transformation during which (Nb)3Si decomposes into (Nb) and (Nb)5Si3, where the (Nb)5Si3possesses the hP16 crystal structure, as opposed to the tI32 crystal structure observed in binary Nb5Si3. The Ti and Hf concentrations were adjusted over the ranges of 21 to 33 (at.%) and 7.5 to 33 (at.%) to understand the effect of bulk composition on the phases present and the eutectoid phase transformation.

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