The trace element geochemistry of clinopyroxenes from pyroxenites in the Lewisian of NW Scotland: insights into light rare earth element mobility during granulite facies metamorphism

2011 ◽  
Vol 163 (2) ◽  
pp. 319-335 ◽  
Author(s):  
Hugh Rollinson ◽  
Philip Gravestock
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Earth Element ◽  
Granulite Facies ◽  
Trace Element Geochemistry ◽  
Light Rare Earth ◽  
Element Mobility ◽  
Element Geochemistry ◽  
Granulite Facies Metamorphism ◽  
Facies Metamorphism

scholarly journals Unraveling the origins and P-T-t evolution of the allochthonous Sobrado unit (Órdenes Complex, NW Spain) using combined U–Pb titanite, monazite and zircon geochronology and rare-earth element (REE) geochemistry

Solid Earth ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 2303-2325
Author(s):  
José Manuel Benítez-Pérez ◽  
Pedro Castiñeiras ◽  
Juan Gómez-Barreiro ◽  
José R. Martínez Catalán ◽  
Andrew Kylander-Clark ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Inductively Coupled Plasma ◽  
Earth Element ◽  
Granulite Facies ◽  
Variscan Orogeny ◽  
Nw Spain ◽  
Granulite Facies Metamorphism ◽  
Magmatic Arc ◽  
Facies Metamorphism

Abstract. The Sobrado unit, within the upper part of the Órdenes Complex (NW Spain) represents an allochthonous tectonic slice of exhumed high-grade metamorphic rocks formed during a complex sequence of orogenic processes in the middle to lower crust. In order to constrain those processes, U–Pb geochronology and rare-earth element (REE) analyses of accessory minerals in migmatitic paragneiss (monazite, zircon) and mylonitic amphibolites (titanite) were conducted using laser ablation split stream inductively coupled plasma mass spectrometry (LASS-ICP-MS). The youngest metamorphic zircon age obtained coincides with a Middle Devonian concordia monazite age (∼380 Ma) and is interpreted to represent the minimum age of the Sobrado high-P granulite facies metamorphism that occurred during the early stages of the Variscan orogeny. Metamorphic titanite from the mylonitic amphibolites yield a Late Devonian age (∼365 Ma) and track the progressive exhumation of the Sobrado unit. In zircon, cathodoluminescence images and REE analyses allow two aliquots with different origins in the paragneiss to be distinguished. An Early Ordovician age (∼490 Ma) was obtained for metamorphic zircons, although with a large dispersion, related to the evolution of the rock. This age is considered to mark the onset of granulite facies metamorphism in the Sobrado unit under intermediate-P conditions, and related to intrusive magmatism and coeval burial in a magmatic arc setting. A maximum depositional age for the Sobrado unit is established in the late Cambrian (∼511 Ma). The zircon dataset also record several inherited populations. The youngest cogenetic set of zircons yields crystallization ages of 546 and 526 Ma which are thought to be related to the peri-Gondwanan magmatic arc. The additional presence of inherited zircons older than 1000 Ma is interpreted as suggesting a West African Craton provenance.

Rare earth and trace element geochemistry of a fragment of jurassic seafloor, Point Sal, California

1977 ◽  
Vol 41 (10) ◽  
pp. 1419-1430 ◽  
Author(s):  
Martin Menzies ◽  
Douglas Blanchard ◽  
Joyce Brannon ◽  
Randy Korotev
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Trace Element Geochemistry ◽  
Element Geochemistry

scholarly journals Tectonic Exhumation of the Central Alps Recorded by Detrital Zircon in the Molasse Basin, Switzerland

2020 ◽  
Author(s):  
Owen A. Anfinson ◽  
Daniel F. Stockli ◽  
Joseph C. Miller ◽  
Andreas Möller ◽  
Fritz Schlunegger
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Detrital Zircon ◽  
Late Eocene ◽  
Tectonic Activity ◽  
Trace Element Geochemistry ◽  
Molasse Basin ◽  
Age Group ◽  
Central Alps ◽  
Element Geochemistry

Abstract. Eocene to Miocene sedimentary strata of the Northern Alpine Molasse Basin in Switzerland are well studied, yet they lack robust geochronologic and geochemical analysis of detrital zircon for provenance tracing purposes. Here, we present detrital zircon U-Pb ages coupled with rare earth and trace element geochemistry (petrochronology) to provide insights into the sedimentary provenance and to elucidate the tectonic activity of the central Alpine Orogen from the late Eocene to mid Miocene. Between 35–22.5 ± 1 Ma, the detrital zircon U-Pb age signatures were dominated by age groups of 300–370 Ma, 370–490 Ma, and 490–710 Ma, with minor Proterozoic age contributions. In contrast, from 21.5 ± 1 Ma to ~ 13.5 Ma (youngest preserved sediments), the detrital zircon U-Pb age signatures were dominated by a 252–300 Ma age group, with a secondary abundance of the 370–490 Ma age group, and only minor contributions of the 490–710 Ma age group. The Eo-Oligocene provenance signatures are consistent with interpretations that initial basin deposition primarily recorded exhumation and erosion of the Austroalpine orogenic cover and minor contributions from underlying Penninic units, containing reworked detritus from Variscan, Caledonian, and Cadomian orogenic cycles. The dominant 252–300 age group from the younger Miocene deposits is associated with the exhumation of Variscan-aged crystalline rocks of upper-Penninic basement units. Noticeable is the lack of Alpine-aged detrital zircon in all samples with the exception of one late Eocene sample, which reflects Alpine volcanism associated with incipient continent-continent collision. In addition, the rare earth and trace element data from the detrital zircon, coupled with zircon morphology and U/Th ratios, point to primarily igneous and rare metamorphic sources of zircon. The observed change in detrital input from Austroalpine to Penninic provenance in the Molasse Basin at ~ 22 Ma appears to be correlated with the onset of synorogenic extension of the Central Alps. Synorogenic extension accommodated by slip along the Simplon fault zone promoted updoming and exhumation the Penninic crystalline core of the Alpine Orogen. The lack of Alpine detrital zircon U-Pb ages in all Oligo-Miocene strata also shows that the Molasse Basin drainage network was not accessing the prominent Alpine age intrusions and metamorphic complexes located in the southern portion of the Central Alps.

scholarly journals Mineralogical and geochemical characterisation of the Kipawa syenite complex, Quebec: implications for rare-earth element deposits

2022 ◽  
Author(s):  
S Matte ◽  
M Constantin ◽  
R Stevenson
Keyword(s):  
Rare Earth ◽  
Rare Earth Element ◽  
Earth Element ◽  
Crustal Contamination ◽  
Hydrothermal Activity ◽  
Trace Element Geochemistry ◽  
Element Geochemistry ◽  
Gneissic Granite ◽  
Icp Ms ◽  
Regional Tectonic

The Kipawa rare-earth element (REE) deposit is located in the Parautochton zone of the Grenville Province 55 km south of the boundary with the Superior Province. The deposit is part of the Kipawa syenite complex of peralkaline syenites, gneisses, and amphibolites that are intercalated with calc-silicate rocks and marbles overlain by a peralkaline gneissic granite. The REE deposit is principally composed of eudialyte, mosandrite and britholite, and less abundant minerals such as xenotime, monazite or euxenite. The Kipawa Complex outcrops as a series of thin, folded sheet imbricates located between regional metasediments, suggesting a regional tectonic control. Several hypotheses for the origin of the complex have been suggested: crustal contamination of mantle-derived magmas, crustal melting, fluid alteration, metamorphism, and hydrothermal activity. Our objective is to characterize the mineralogical, geochemical, and isotopic composition of the Kipawa complex in order to improve our understanding of the formation and the post-formation processes, and the age of the complex. The complex has been deformed and metamorphosed with evidence of melting-recrystallization textures among REE and Zr rich magmatic and post magmatic minerals. Major and trace element geochemistry obtained by ICP-MS suggest that syenites, granites and monzonite of the complex have within-plate A2 type anorogenic signatures, and our analyses indicate a strong crustal signature based on TIMS whole rock Nd isotopes. We have analyzed zircon grains by SEM, EPMA, ICP-MS and MC-ICP-MS coupled with laser ablation (Lu-Hf). Initial isotopic results also support a strong crustal signature. Taken together, these results suggest that alkaline magmas of the Kipawa complex/deposit could have formed by partial melting of the mantle followed by strong crustal contamination or by melting of metasomatized continental crust. These processes and origins strongly differ compare to most alkaline complexes in the world. Additional TIMS and LA-MC-ICP-MS analyses are planned to investigate whether all lithologies share the same strong crustal signature.

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