Geochemical investigation of an unusual alteration profile developed at the base of a Carboniferous lava flow, Isle of Bute, Scotland

2008 ◽  
Vol 99 (2) ◽  
pp. 49-59 ◽  
Author(s):  
Grant M. Young
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Lava Flow ◽  
Volcanic Rocks ◽  
Atomic Weight ◽  
Alteration Zone ◽  
Fine Grained ◽  
Heavy Rare Earth Elements ◽  
Chemical Index Of Alteration ◽  
Geochemical Investigation

ABSTRACTAn alteration zone at the base of a Carboniferous lava flow on the island of Bute resembles modern and ancient weathering profiles, but it is ‘upside down’ in the sense that alteration is most intense at the base and decreases upwards. Values for a Chemical Index of Alteration (CIA) increase from fresh lava and corestones downwards to fine-grained structureless material. The altered material is Mg- and Cu-rich, possibly as a result of migration of these elements from underlying sediments. Rare earth elements (REE) display considerable and systematic mobility and fractionation. In general heavy rare earth elements (HREE) are concentrated during alteration, whereas the light rare earth elements (LREE) are lost. Mobility of the REE appears to be related to atomic weight, with La (the lightest REE) being the most depleted through to Lu, which is the most concentrated REE in the highly altered material. Similar systematic fractionation is shown by some weathering profiles developed on mafic igneous rocks. Movement of water into the volcanic rocks was probably driven by a steep thermal gradient between the hot lava and its sedimentary substrate.

Petrogenesis of the Upper Cretaceous volcanism in the Kefken region, Western Pontides, NW Turkey

2021 ◽  
Author(s):  
Turgut Duzman ◽  
Ezgi Sağlam ◽  
Aral I. Okay
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Partial Melting ◽  
Upper Cretaceous ◽  
Volcanic Rocks ◽  
Early Eocene ◽  
Heavy Rare Earth ◽  
Heavy Rare Earth Elements ◽  
Cretaceous Volcanism ◽  
Oceanic Slab

<p>The Upper Cretaceous volcanic and volcaniclastic rocks crop out along the Black Sea coastline in Turkey. They are part of a magmatic arc that formed as a result of northward subduction of the Tethys ocean beneath the southern margin of Laurasia. The lower part of the Upper Cretaceous volcanism in the Kefken region, 100 km northeast of Istanbul, is represented by basaltic andesites, andesites, agglomerates and tuffs, which have yielded Late Cretaceous (Campanian, ca. 83 Ma) U-Pb zircon ages. The volcanic and volcanoclastic rocks are stratigraphically overlain by shallow to deep marine limestones, which range in age from Late Campanian to Early Eocene.  Geochemically, basaltic andesites and andesites display negative anomalies in Nb, Ta and Ti, enrichment in large ion lithophile elements (LILE) relative to high field strength elements (HFSE). Light rare earth elements (LREE) show slightly enrichment relative to heavy rare earth elements (La<sub>cn</sub>/Yb<sub>cn</sub> =2.51-3.63) and there are slight negative Eu anomalies (Eu/Eu* = 0.71-0.95) in basaltic andesite and andesite samples. The geochemical data indicate that Campanian volcanic rocks were derived from the partial melting of the mantle wedge induced by hydrous fluids released by dehydration of the subducted oceanic slab.</p><p>There is also a horizon of volcanic rocks, about 230 m thick, within the Late Campanian-Early Eocene limestone sequence.  This volcanic horizon, which consists of pillow basalts, porphyritic basalts,  andesites and dacites, is of Maastrichtian age based on paleontological data from the intra-pillow sediments and U-Pb zircon ages from the andesites and dacites (72-68 Ma).  The Maastrichtian andesites and dacites are geochemically distinct from the Campanian volcanic rocks. They show distinct adakite-like geochemical signatures with high ratios of Sr/Y (>85.5), high La<sub>cn</sub>/Yb<sub>cn </sub>(16.4-23.7) ratios, low content of Y (7.4-8.6 ppm) and low content of heavy rare-earth elements (HREE). The adakitic rocks most probably formed as a result of partial melting of the subducting oceanic slab under garnet and amphibole stable conditions.</p><p>The Upper Cretaceous arc sequence in the Kefken region shows a change from typical subduction-related magmas to adakitic ones, accompanied by decrease in the volcanism.</p><p> </p><p> </p>

scholarly journals Petrografia, Geoquímica, Análises Isotópicas (Sr, Nd) e Geocronologia Ar-Ar dos Basaltos de Tapirapuã (Tangará da Serra, Mato Grosso, Brasil)

2006 ◽  
Vol 33 (2) ◽  
pp. 71 ◽  
Author(s):  
MÁRCIA APARECIDA DE SANT’ANA BARROS ◽  
ANA MARIA MIZUSAKI ◽  
RICARDO WESKA ◽  
ANDRÉ DE BORBA ◽  
FARID CHEMALE JR ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
North Atlantic ◽  
Volcanic Event ◽  
Mato Grosso ◽  
Fine Grained ◽  
The North ◽  
Tectonic Environment ◽  
Heavy Rare Earth Elements ◽  
Light Rare Earth Elements

 The basaltic flows from Tapirapuã Formation are exposed at Tangará da Serra region, 250 km from Cuiabá (MT) and the thickness can reach 310 meters. The basalts range from massive dark gray, with colunar disjunctions at the base to purple amygdaloidal at the top. They are generally fine-grained, however gabroics portions have been identified. In thin section the Tapirapuã basalts show subophitic texture. Chemical analyses in these rocks suggest tholeiitic compositions, within continental tectonic environment. There is an enrichment of light rare earth elements when compared to heavy rare earth elements. The studied samples have low contents of TiO2 and P2O5 being similar to low P2O5 and TiO2 group from Serra Geral Formation (Paraná Basin). Analyses of Sr and Nd isotopes show the following results: 87Sr/86Sr between 0.703 and 0.707, ∈Nd from –0.01 to + 2.32 and model ages (TDM)= (931 to 1.267 Ma). 40Ar / 39Ar geochronology of plagioclase crystals from Tapirapuã basalts presented a plateau age of 206 ± 6 Ma, in agreement with previous ages obtained from Anari and Tapirapuã sub-provinces. This result places the volcanic event at the limit of the Triassic-Jurassic periods, related to the opening of the North Atlantic.

scholarly journals U-Pb geochronology, Sr-Nd geochemistry, petrogenesis and tectonic setting of Gandab volcanic rocks, northeastern Iran

2017 ◽  
Vol 44 (1) ◽  
pp. 269-286 ◽  
Author(s):  
Azam Entezari Harsini ◽  
Seyed A Mazaheri ◽  
Saeed Saadat ◽  
José F Santos
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earth Element ◽  
Earth Element ◽  
Saturation Index ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Major Elements ◽  
Magmatic Arc ◽  
Heavy Rare Earth Elements

Abstract This paper addresses U-Pb geochronology, Sr-Nd geochemistry, petrogenesis and tectonic setting in the Gandab volcanic rocks. The Gandab volcanic rocks belong to the Sabzevar zone magmatic arc (northeastern Iran). Petrographically, all the studied volcanic rocks indicate porphyritic textures with phenocrysts of plagioclase, K-feldespar, hornblende, pyroxene, and magnetite which are embedded in a fine to medium grained groundmass. As well, amygdaloidal, and poikilitic textures are seen in some rocks. The standard chemical classifications show that the studied rocks are basaltic trachy andesite, trachy andesite, trachyte, and trachy dacite. Major elements reveal that the studied samples are metaluminous and their alumina saturation index varies from 0.71 to 1.02. The chondrite-normalized rare earth element and mantle-normalized trace element patterns show enrichment in light rare earth elements (LREE) relative to heavy rare earth elements (HREE) and in large ion lithophile elements (LILE) relative to high field strength elements (HFSE). As well they show a slightly negative Eu anomaly (Eu/Eu* = 0.72 – 0.97). The whole-rock geochemistry of the studied rocks suggests that they are related to each other by fractional crystallization. LA-MC-ICP-MS U-Pb analyses in zircon grains from two volcanic rock samples (GCH-119 and GCH-171) gave ages ranging of 5.47 ± 0.22 Ma to 2.44 ± 0.79 Ma, which corresponds to the Pliocene period. In four samples analysed for Sr and Nd isotopes 87Sr/86Sr ratios range from 0.704082 to 0.705931 and εNd values vary between +3.34 and +5. These values could be regarded to as representing mantle derived magmas. Taking into account the comparing rare earth element (REE) patterns, an origin of the parental magmas in enriched lithospheric mantle is suggested. Finally, it is concluded that Pliocene Gandab volcanic rocks are related to the post-collision environment that followed the Neo-Tethys subduction.

scholarly journals Post-collisional basalts of the Acampamento Velho Formation, Camaquã Basin, São Gabriel Terrane, southernmost Brazil

2017 ◽  
Vol 47 (3) ◽  
pp. 467-489 ◽  
Author(s):  
Luiz Alberto Vedana ◽  
Ruy Paulo Philipp ◽  
Carlos Augusto Sommer
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Volcanic Rocks ◽  
Two Samples ◽  
Heavy Rare Earth Elements ◽  
Dom Feliciano Belt ◽  
Basic Volcanic ◽  
Porphyritic Texture ◽  
Horizontal Pattern ◽  
Final Evolution

ABSTRACT: The basic volcanic rocks in the Palma region, southern portion of the São Gabriel Terrane, have always been interpreted as generated during the active subduction period of the São Gabriel orogeny (Cryogenian). This terrane was built as the result of the Charrua Ocean closure between 900-680 Ma. The basalts show a subhorizontal igneous flow foliation and porphyritic texture, with plagioclase phenocrysts in a thin matrix composed of plagioclase, augite and magnetite, commonly altered to actinolite, chlorite and epidote. They have amygdales and veinlets reflecting a pervasive hydrothermal phase and are affected by thermal metamorphism related to Jaguari granite intrusion. Two samples were dated by the U-Pb zircon geochronology and yielded crystallization ages of 563±2 Ma and 573±6 Ma. The basalts have transitional composition from tholeiitic to calc-alkaline, metaluminous character, trace elements patterns rich in large-ion lithophile element (LILE) with negative anomalies of Nb, P and Ti, slight enrichment in light rare-earth elements (LREE) and horizontal pattern of heavy rare earth elements (HREE). The data allow interpreting the basalts as belonging to the Acampamento Velho Formation of the Camaquã Basin, and related to the basalts of the Ramada and Taquarembó plateaus. These associations represent the final evolution of the volcanism generated in the post-collisional period of the Dom Feliciano Belt.

scholarly journals Intrinsically weak magnetic anisotropy of cerium in potential hard-magnetic intermetallics

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Anna Galler ◽  
Semih Ener ◽  
Fernando Maccari ◽  
Imants Dirba ◽  
Konstantin P. Skokov ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Magnetic Anisotropy ◽  
High Performance ◽  
Kondo Effect ◽  
Quantitative Description ◽  
Many Body ◽  
Heavy Rare Earth Elements ◽  
Fe Intermetallics ◽  
Full Temperature

AbstractCerium-based intermetallics are currently attracting much interest as a possible alternative to existing high-performance magnets containing scarce heavy rare-earth elements. However, the intrinsic magnetic properties of Ce in these systems are poorly understood due to the difficulty of a quantitative description of the Kondo effect, a many-body phenomenon where conduction electrons screen out the Ce-4f moment. Here, we show that the Ce-4f shell in Ce–Fe intermetallics is partially Kondo screened. The Kondo scale is dramatically enhanced by nitrogen interstitials suppressing the Ce-4f contribution to the magnetic anisotropy, in striking contrast to the effect of nitrogenation in isostructural intermetallics containing other rare-earth elements. We determine the full temperature dependence of the Ce-4f single-ion anisotropy and show that even unscreened Ce-4f moments contribute little to the room-temperature intrinsic magnetic hardness. Our study thus establishes fundamental constraints on the potential of cerium-based permanent magnet intermetallics.

Selective recovery of heavy rare earth elements from apatite with an adsorbent bearing immobilized tridentate amido ligands

2016 ◽  
Vol 159 ◽  
pp. 157-160 ◽  
Author(s):  
Takeshi Ogata ◽  
Hirokazu Narita ◽  
Mikiya Tanaka ◽  
Mihoko Hoshino ◽  
Yoshiaki Kon ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Heavy Rare Earth ◽  
Amido Ligands ◽  
Selective Recovery ◽  
Heavy Rare Earth Elements

Geochemical characteristics and geologic significance of rare earth elements in oil shale of the Yan’an Formation in the Tanshan area, in the Liupanshan Basin, China

2021 ◽  
pp. 1-41
Author(s):  
Lianfu Hai ◽  
Qinghai Xu ◽  
Caixia Mu ◽  
Rui Tao ◽  
Lei Wang ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Oil Shale ◽  
Sedimentary Environment ◽  
Moderate Degree ◽  
Material Source ◽  
Icp Ms ◽  
Ree Distribution ◽  
Heavy Rare Earth Elements ◽  
Degree Of Differentiation

In the Tanshan area, which is at the Liupanshui Basin, abundant oil shale resources are associated with coals. We analyzed the cores, geochemistry of rare earth elements (REE) and trace element of oil shale with ICP-MS technology to define the palaeo-sedimentary environment, material source and geological significance of oil shale in this area. The results of the summed compositions of REE, and the total REE contents (SREE), in the Yan'an Formation oil shale are slightly higher than the global average of the composition of the upper continental crustal (UCC) and are lower than that of North American shales. The REE distribution pattern is characterized by right-inclined enrichment of light rare earth elements (LREE) and relative loss of heavy rare earth elements (HREE), which reflects the characteristics of crustal source deposition. There is a moderate degree of differentiation among LREE, while the differences among HREE are not obvious. The dEu values show a weak negative anomaly and the dCe values show no anomaly, which are generally consistent with the distribution of REE in the upper crust. The characteristics of REE and trace elements indicate that the oil shale formed in an oxygen-poor reducing environment and that the paleoclimatic conditions were relatively warm and humid. The degree of differentiation of REE indicates that the sedimentation rate in the study area was low, which reflected the characteristics of relatively deep sedimentary water bodies and distant source areas. The results also proved that the source rock mainly consisted of calcareous mudstone, and a small amount of granite was also mixed in.

scholarly journals Effect of acid mine drainage on dissolved rare earth elements geochemistry along a fluvial–estuarine system: the Tinto-Odiel Estuary (S.W. Spain)

2012 ◽  
Vol 43 (3) ◽  
pp. 262-274 ◽  
Author(s):  
J. Borrego ◽  
B. Carro ◽  
N. López-González ◽  
J. de la Rosa ◽  
J. A. Grande ◽  
...  
Keyword(s):  
Rare Earth ◽  
Acid Mine Drainage ◽  
Rare Earth Elements ◽  
Mine Drainage ◽  
Drainage System ◽  
Estuarine System ◽  
Mixing Zone ◽  
Heavy Rare Earth ◽  
Acid Mine ◽  
Heavy Rare Earth Elements

The concentration of rare earth elements together with Sc, Y, and U, as well as rare earth elements fractionation patterns, in the water of an affected acid mine drainage system were investigated. Significant dissolved concentrations of the studied elements were observed in the fluvial sector of this estuary system (Sc ∼ 31 μg L−1, Y ∼ 187 μg L−1, U ∼ 41 μg L−1, Σ rare earth elements ∼621 μg L−1), with pH values below 2.7. In the mixing zone of the estuary, concentrations are lower (Sc ∼ 2.1 μg L−1; Y ∼ 16.7 μg L−1; U ∼ 4.8 μg L−1; Σ rare earth elements ∼65.3 μg L−1) and show a strong longitudinal gradient. The largest rare earth elements removal occurs in the medium-chlorinity zone and it becomes extreme for heavy rare earth elements, as observed for Sc. Samples of the mixing zone show a North American Shale normalized pattern similar to the fluvial zone water, while the samples located in the zone with pH between 6.5 and 7.7 show a depletion of light rare earth elements relative to middle rare earth elements and heavy rare earth elements, similar to that observed in samples of the marine estuary.

scholarly journals The isotopic constitution and atomic weights of hafnium, thorium, rhodium, titanium, zirconium, calcium, gallium, silver, carbon, nickel, cadmium, iron and indium

1935 ◽  
Vol 149 (867) ◽  
pp. 396-405 ◽  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Rare Earths ◽  
Mass Spectra ◽  
Mass Number ◽  
Atomic Weight ◽  
Complete Data ◽  
Pure Sample ◽  
Titanium Zirconium ◽  
Similar Element

An account of experiments has already been given by which the analyses of the rare earth elements were completed with the aid of a particularly favourable arrangement of the anode ray apparatus. This paper contains a description of analyses of other elements made with the same setting and also of some others subsequently made to obtain more accurate and complete data on elements whose constitution had already been provisionally settled. Results (72) Hafnium —Many previous attempts to obtain the mass spectra of this element had failed. For the most similar element, zirconium, the only successful results had been obtained from the fluoride. A pure sample of hafnium fluoride had been kindly provided by Professor G. v. Hevesy, one of the discoverers of the element, and this was incorporated into the anode mixture. The first trial was a failure; but after the work on zirconium described below a second attempt was made, this time with resolved, so that only rough estimates of abundance could be obtained. These were as follows:— Mass numbers . . . . . 176 177 178 179 180 % abundance . . . . . . 5 19 28 18 30 These given a mean mass number 178·5. Applying the same correction as with the rare earths we get atomic weight of hafnium = 178·4 ± 0·2 in fair agreement with the International value 178·6.

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