scholarly journals Mineral Geochemistry of Basaltic Rocks from IODP Expeditions 334 and 344: Implications for Magmatic Processes of Cocos Ridge Segment Being Subducted Beneath the Middle America Trench

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 769
Author(s):  
Quanshu Yan ◽  
Zhenmin Ge
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Early Stage ◽  
Spreading Center ◽  
Complete Replacement ◽  
Basaltic Rocks ◽  
Middle America Trench ◽  
Integrated Ocean Drilling Program ◽  
Middle America ◽  
Galapagos Plume

The Cocos Ridge, which is subducted beneath the Central American Volcanic Arc, has a complex tectonic evolution history due to plume-ridge interaction between the Galápagos plume and the Cocos—Nazca spreading center. This study presents major and trace element analyses of plagioclase and clinopyroxenes hosted by Cocos Ridge basaltic rocks that were drilled in three holes (U1381A, U1381C and U1414A) of Sites U1381 and U1414 on the Cocos Ridge close to the Middle America Trench during the Integrated Ocean Drilling Program (IODP) Expeditions 334 and 344. The results show that (1) plagioclases are mainly bytownite and labradorite with subordinate andesine, which are enriched in light rare earth elements (LREE) and some large-ion lithophile elements (LILE) and exhibit marked positive Eu anomalies; and (2) that clinopyroxenes are augites, which are depleted in highly incompatible elements such as LREE and LILE, have nearly flat heavy rare earth elements patterns (HREE) and lack Eu anomalies in chondrite-normalized rare earth element (REE) diagrams. During the ascent to the surface, the primary magmas experienced fractional crystallization of plagioclase, clinopyroxene, Ti-Fe oxides and possibly olivine (complete replacement of olivine by secondary minerals). The crystallization temperatures of plagioclase phenocrysts and microlites are 1050 to 1269 °C, and 866 to 1038 °C, respectively, and the pressures of plagioclase phenocrysts are 0.3–0.7 GPa. The crystallization temperatures of clinopyroxene phenocrysts/micro-phenocrysts is 1174–1268 °C, similar to those of plagioclase phenocrysts, suggesting some of clinopyroxene and plagioclase phenocrysts cotectic crystallized during early stage of magmatic evolution. In addition, the equilibrium pressures of clinopyroxene phenocrysts/micro phenocrysts are 0.02–0.97 GPa, implying that the clinopyroxene started to crystallize within the mantle, and magma evolution has undergone an early crystallization stage with clinopyroxene and no plagioclase.

Metasomatic Processes in the Lithospheric Mantle Beneath the No. 30 Kimberlite (Wafangdian Region, North China Craton)

2019 ◽  
Vol 57 (4) ◽  
pp. 499-517 ◽  
Author(s):  
Ren Z. Zhu ◽  
Pei Ni ◽  
Jun Y. Ding ◽  
Guo G. Wang ◽  
Ming S. Fan ◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
North China Craton ◽  
Lithospheric Mantle ◽  
North China ◽  
Compositional Data ◽  
Early Stage ◽  
Mantle Metasomatism ◽  
Element Data

AbstractThis paper presents the first major and trace element compositions of mantle-derived garnet xenocrysts from the diamondiferous No. 30 kimberlite pipe in the Wafangdian region, and these are used to constrain the nature and evolution of mantle metasomatism beneath the North China Craton (NCC). The major element data were acquired using an electron probe micro-analyzer and the trace element data were obtained using laser ablation inductively coupled plasma-mass spectrometry. Based on Ni-in-garnet thermometry, equilibrium temperatures of 1107–1365 °C were estimated for peridotitic garnets xenocrysts from the No. 30 kimberlite, with an average temperature of 1258 °C, and pressures calculated to be between 5.0 and 7.4 GPa. In a CaO versus Cr2O3 diagram, 52% of the garnets fall in the lherzolite field and 28% in the harzburgite field; a few of the garnets are eclogitic. Based on rare earth element patterns, the lherzolitic garnets are further divided into three groups. The compositional variations in garnet xenocrysts reflect two stages of metasomatism: early carbonatite melt/fluid metasomatism and late kimberlite metasomatism. The carbonatite melt/fluids are effective at introducing Sr and the light rare earth elements, but ineffective at transporting much Zr, Ti, Y, or heavy rare earth elements. The kimberlite metasomatic agent is highly effective at element transport, introducing, e.g., Ti, Zr, Y, and the rare earth elements. Combined with compositional data for garnet inclusions in diamonds and megacrysts from the Mengyin and Wafangdian kimberlites, we suggest that these signatures reflect a two-stage evolution of the sub-continental lithospheric mantle (SCLM) beneath the NCC: (1) early-stage carbonatite melt/fluid metasomatism resulting in metasomatic modification of the SCLM and likely associated with diamond crystallization; (2) late-stage kimberlite metasomatism related to the eruption of the 465 Ma kimberlite.

scholarly journals Rare Earth Elements and Sr Isotope Ratios of Large Apatite Crystals in Ghareh Bagh Mica Mine, NW Iran: Tracing for Petrogenesis and Mineralization

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 833
Author(s):  
Narges Daneshvar ◽  
Hossein Azizi ◽  
Yoshihiro Asahara ◽  
Motohiro Tsuboi ◽  
Mahdi Hosseini
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Early Stage ◽  
Alkali Feldspar ◽  
Sr Isotope ◽  
Nw Iran ◽  
Apatite Crystals ◽  
Type Granite ◽  
Alteration Minerals ◽  
Ree Pattern

The 320 Ma Ghareh Bagh mica mine is the only active mica mine in northwest Iran, and hosts Mg-bearing biotite (phlogopite) with apatite, epidote, and calcite. Chemical investigation of apatite infers the high abundances of the rare earth elements (REEs up to 5619 ppm), higher ratios of the LREE/HREE ((La/Yb)N = 28.5–36.7)) and high content of Y (236–497 ppm). REE pattern in the apatite and host A-type granite is almost the same. Ghareh Bagh apatite formed from the early magmatic-hydrothermal exsolved fluids at the high temperature from the Ghushchi alkali feldspar granite. The apatite crystals came up as suspension grains and precipitated in the brecciated zone. The early magmatic-hydrothermal fluids settle phlogopite, epidote, chlorite, K-feldspar and albite down in the brecciation zone. Due to the precipitation of these minerals, the late-stage fluids with low contents of Na+, Ca2+ and REE affected the early stage of alteration minerals. The high ratios of 87Sr/86Sr (0.70917 to 0.70950) are more consistent with crustal sources for the apatite large crystals. The same ages (320 Ma) for both brecciated mica veins and host alkali feldspar granites infer the apatite and paragenesis minerals were related to host granite A-type granite in the Ghareh Bagh area.

Understanding the regularities of recovering non-ferrous and rare earth metals from standard test solutions by flotation and solvent sublation

2020 ◽  
pp. 14-19
Author(s):  
O. L. Lobacheva ◽  
◽  
N. V. Dzhevaga ◽  
A. S. Danilov ◽  
◽  
...  
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Early Stage ◽  
Low Cost ◽  
Standard Test ◽  
Postgraduate Students ◽  
Ion Flotation ◽  
Exchange Processes ◽  
Industrial Solutions ◽  
Experimental And Theoretical Studies

This paper describes the results of experimental and theoretical studies that looked at ion exchange processes in liquid phase systems containing nonferrous metals, rare earth elements and a surfactant — i.e. sodium dodecylsulphate (NaDS). Ion flotation processes are considered in reciprocal systems containing Co+2 and Ni+2. There is a number of reasons for choosing the above salts: – The problem of removing cations of heavy metals (in particular, Co+2 and Ni+2) from water is of relevance; – At рН 7, these ions do not form hydroxides or hydroxide residue; – Co+2 and Ni+2 bond with NaDS to form easily soluble salts; – Quite a few low-cost analysis techniques are known that can detect these ions. Ion flotation processes were also examined in systems containing rare earth elements, NaCl and surfactants. The influence of Cl– ions on the distribution coefficient in Sm+3 and Eu+3 containing systems was studied by comparing instability constants typical of chlorine compounds and hydroxides. It was found that a rising concentration of NaCl is associated with a rising pH of cations of the rare earth elements of interest at the early stage of recovery and during the peak recovery. The paper considers an innovative technique to examine systems with rare earth elements and surfactants — i.e. solvent sublation. The authors examine the possibility of recovering ions of lanthanides (e.g. erbium) by solvent sublation using NaDS as a collector and isooctyl alcohol as an extractant. Many researchers believe the latter to be the best agent for such studies. The concentration of Er+3 in the standard test solutions was 0.001 mol/l. As the process develops, the concentration of extracted ions asymptotically approaches the value that is typical of a system approaching its steady state. It was established that in these conditions the maximum recovery for Er+3 is reached at рН of 8.0. This research study was funded through a scholarship granted by the President of the Russian Federation to young researchers and postgraduate students under the following project: SP-347.2019.1 “Ion flotation as an innovative and efficient technique to recover rare earth elements while concentrating dilute industrial solutions with possible identification of elements”.

Rare-earth elements in high-alumina basaltic rocks from Sardinia

1976 ◽  
Vol 18 (4) ◽  
pp. 251-262 ◽  
Author(s):  
J. Dostal ◽  
C. Dupuy ◽  
C. Coulon
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
High Alumina ◽  
Basaltic Rocks

Le Complexe d'Ascot des Appalaches du sud du Québec: pétrologie et géochimie

1989 ◽  
Vol 26 (12) ◽  
pp. 2407-2420 ◽  
Author(s):  
Alain Tremblay ◽  
Réjean Hébert ◽  
Mario Bergeron
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Continental Crust ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Geochemical Composition ◽  
Basaltic Rocks ◽  
End Members ◽  
Light Rare Earth Elements ◽  
Felsic Rocks

This paper reviews new geochemical data obtained from Ordovician volcanics in the Ascot Complex of the Quebec Appalachians. The Ascot Complex is divided into three distinctive lithotectonic assemblages: the Sherbrooke, Eustis, and Stokes domains. The Sherbrooke Domain includes basalts, pyroclastic breccias, and felsic tuffs. The Eustis Domain is composed of volcanoclastic and pyroclastic rocks. The Stokes Domain is an assemblage of rhyolitic tuffs and basalts. The geochemical composition of the volcanics varies between basaltic and rhyolitic end members. Basaltic rocks are arc tholeiites (La/Yb = 0.5–2). Some basalts found in the Sherbrooke Domain show a composition very close to that of frontal-arc boninites (La/Yb = 1–2) and are depleted of rare-earth elements. Felsic rocks from the Sherbrooke Domain are poorer in light rare-earth elements (La/Yb = 0.5–0.7) than those from the Stokes Domain (La/Yb > 2). All of the felsic rocks are characterized by a negative Eu anomaly (Eu*/Eu = 1.3–3). The Stokes felsites are derived from an enriched magma contaminated by a continental crust component. The Sherbrooke Domain felsites are derived from a source impoverished in incompatible elements and enriched in high-partition-coefficient elements. Volcanic rocks from Sherbrooke and Eustis are thought to represent an incipient intra-oceanic arc. The rocks of the Stokes assemblage represent a more mature section of the same arc, explaining the contamination of generated magmas by continental crust components. The modern architecture of the Ascot Complex is essentially tectonic and may not correspond to the initial internal structure of this Ordovician arc. [Journal Translation]

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