scholarly journals A mantle metasomatic injection event linked to Permo-Carboniferous lamprophyre magmatism and associated rare metal ore deposition (Sn-W-Mo-Sc-In-Li, Ag(-Au)-In-base metal) in the eastern European Variscides

2019 ◽  
Keyword(s):  
Base Metal ◽  
Rare Metal ◽  
Eastern European ◽  
Ore Deposition ◽  
European Variscides

A Lower Palaeozoic shallow water sequence in the eastern European Variscides (SW Poland): provenance and depositional history

1994 ◽  
Vol 83 (1) ◽  
pp. 5-19 ◽  
Author(s):  
Ryszard Kryza ◽  
Krzysztof Turniak ◽  
Andrzej Muszyński ◽  
Jan A. Zalasiewicz
Keyword(s):  
Shallow Water ◽  
Eastern European ◽  
Depositional History ◽  
Lower Palaeozoic ◽  
Sw Poland ◽  
European Variscides

Metasomatic High Field Strength Element, Tin, and Base Metal Enrichment Processes in Lithium Pegmatites from Southeast Ireland

2020 ◽  
Author(s):  
David Kaeter ◽  
Renata Barros ◽  
Julian F. Menuge
Keyword(s):  
Field Strength ◽  
Base Metal ◽  
Late Stage ◽  
High Field ◽  
Early Stage ◽  
Rare Metal ◽  
Textural Features ◽  
High Field Strength ◽  
Rare Element ◽  
Element Partitioning

Abstract Compared to average crustal abundances, high field strength elements (HFSEs) including Zr, Nb, Hf, Ta, and U are commonly enriched in rare element pegmatites. Albite-spodumene pegmatites may show economic grades of these elements, along with Sn, primarily in oxide minerals. Processes leading to enrichment and precipitation of HFSEs in these rocks are not well understood. Here, we characterize the textures and geochemistry of minerals of HFSEs, tin, and base metals in the Leinster albite-spodumene pegmatites. We use these data to infer processes for enrichment and precipitation of these metals during pegmatite crystallization, especially subsolidus processes. The Leinster albite-spodumene pegmatites are located within the East Carlow deformation zone on the eastern flank of the Caledonian S-type Leinster batholith, southeast Ireland. The final crystallization stages of these pegmatites are characterized by autometasomatism and hydrothermal overprint leading to in situ greisenization and precipitation of massive, commonly replacive, albitites. Cassiterite and HFSE minerals (columbite-tantalite and zircon) crystallized predominantly during these late stages. Crystals of HFSE minerals that precipitated during the early magmatic stages commonly exhibit evidence of resorption and additional growth during later stages. Others, such as microlite and uraninite, only crystallized during metasomatism or from hydrothermal fluids. Base metal sulfides are among the last precipitates from these fluids. We present a detailed paragenetic sequence for the Leinster albite-spodumene pegmatites and show that late-stage aqueous fluids transported HFSEs, especially after all the melt had crystallized. Tantalum enrichment seems to have been controlled by processes affecting the entire crystallizing medium, as opposed to fractional crystallization of columbite-tantalite. The textures and parageneses described in the present and our previous work are well explained by element partitioning between coexisting liquids with characteristics similar to those described in published melt-melt-fluid immiscibility models for rare element pegmatites but do not exclude other models for early-stage pegmatite evolution. The chemical and textural features of columbite-tantalite and cassiterite in the Leinster albite-spodumene pegmatites are seen in similar rare element pegmatites and rare metal granites elsewhere, suggesting wide applicability of the processes interpreted for Leinster. Late-stage processes of the type that affected the lithium pegmatites at Leinster may either enhance or reduce economic potential: ore metal tenor may be increased because late-stage columbite-tantalite is generally richer in Ta, and/or ore metals may be lost from pegmatites to country rocks. Lithium pegmatites, including the ones at Leinster, are commonly associated spatially with Sn-W veins and greisens and share some geochemical and textural features, such as evidence of widespread albitization. We propose that lithium pegmatites are transitional products regarding the interrelated dimensions time, temperature, and depth in S-type granite-related Li-Sn-W mineralizing systems.

Pragmatic Language Performance of Children Adopted Internationally

2019 ◽  
Vol 28 (2) ◽  
pp. 501-514
Author(s):  
Deborah A. Hwa-Froelich ◽  
Hisako Matsuo
Keyword(s):  
Social Communication ◽  
False Belief ◽  
Pragmatic Language ◽  
Eastern European ◽  
Language Performance ◽  
Emotion Identification ◽  
False Belief Understanding ◽  
Quasi Experimental ◽  
Pragmatic Communication ◽  
Eastern European Countries

Purpose Pragmatic language is important for social communication across all settings. Children adopted internationally (CAI) may be at risk of poorer pragmatic language because of adverse early care, delayed adopted language development, and less ability to inhibit. The purpose of this study was to compare pragmatic language performance of CAI from Asian and Eastern European countries with a nonadopted group of children who were of the same age and from similar socioeconomic backgrounds as well as explore the relationship among emotion identification, false belief understanding, and inhibition variables with pragmatic language performance. Method Using a quasi-experimental design, 35 four-year-old CAI (20 Asian, 15 Eastern European) and 33 children who were not adopted were included in this study. The children's pragmatic language, general language, and social communication (emotion identification of facial expressions, false belief understanding, inhibition) were measured. Comparisons by region of origin and adoption experience were completed. We conducted split-half correlation analyses and entered significant correlation variables into simple and backward regression models. Results Pragmatic language performance differed by adoption experience. The adopted and nonadopted groups demonstrated different correlation patterns. Language performance explained most of the pragmatic language variance. Discussion Because CAI perform less well than their nonadopted peers on pragmatic communication measures and different variables are related to their pragmatic performance, speech-language pathologists may need to adapt assessment and intervention practices for this population.

Revisiting the passivation of stainless steels and other passive CRAs

2018 ◽  
Vol 106 (1) ◽  
pp. 107 ◽  
Author(s):  
Jean- Louis Crolet
Keyword(s):  
Electrical Conductivity ◽  
Metal Ions ◽  
Base Metal ◽  
Stainless Steels ◽  
Electronic Conductivity ◽  
Transport Processes ◽  
General Knowledge ◽  
Inorganic Polymers ◽  
Faraday Cage

All that was said so far about passivity and passivation was indeed based on electrochemical prejudgments, and all based on unverified postulates. However, due the authors’ fame and for lack of anything better, the great many contradictions were carefully ignored. However, when resuming from raw experimental facts and the present general knowledge, it now appears that passivation always begins by the precipitation of a metallic hydroxide gel. Therefore, all the protectiveness mechanisms already known for porous corrosion layers apply, so that this outstanding protectiveness is indeed governed by the chemistry of transport processes throughout the entrapped water. For Al type passivation, the base metal ions only have deep and complete electronic shells, which precludes any electronic conductivity. Then protectiveness can only arise from gel thickening and densification. For Fe type passivation, an incomplete shell of superficial 3d electrons allows an early metallic or semimetallic conductivity in the gel skeleton, at the onset of the very first perfectly ordered inorganic polymers (- MII-O-MIII-O-)n. Then all depends on the acquisition, maintenance or loss of a sufficient electrical conductivity in this Faraday cage. But for both types of passive layers, all the known features can be explained by the chemistry of transport processes, with neither exception nor contradiction.

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