scholarly journals Trace Element and Stable Isotope Geochemistry of Lwamondo and Zebediela Kaolins, Limpopo Province, South Africa: Implication for Paleoenvironmental Reconstruction

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 93
Author(s):  
Avhatakali Raphalalani ◽  
Georges-Ivo Ekosse ◽  
John Odiyo ◽  
Jason Ogola ◽  
Nenita Bukalo
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Stable Isotope ◽  
Trace Element ◽  
Continental Crust ◽  
Rare Earth Element ◽  
Earth Element ◽  
Paleoenvironmental Reconstruction ◽  
Δ18o And Δd ◽  
Ree Patterns

The aim of the present study was the paleoenvironmental reconstruction of the prevailing environment under which the Lwamondo and Zebediela kaolin deposits were formed. Hence, this study reports deuterium and oxygen stable isotope values and trace and rare earth element concentrations for two samples of kaolin. Upper continental crust-normalised trace-element patterns reveal that large ion lithophile elements and high-field-strength elements are generally depleted in Lwamondo and Zebediela kaolins, whereas transition trace elements are generally enriched in these kaolins. Upper continental crust-normalised rare earth element (REE) patterns show that there is a slight enrichment of heavy REEs (HREEs) compared to light REEs (LREEs) in these kaolins. The δ18O and δD stable isotope values for kaolinite from Lwamondo ranged from 17.4‰ to 19.1‰ and from −54‰ to 84‰, respectively, whereas those values for kaolinite from Zebediela varied from 15.6‰ to 17.7‰ and from −61‰ to –68‰ for δ18O and δD, respectively. The REE patterns and the content of other trace elements indicate ongoing kaolinitisation in the Lwamondo and Zebediela kaolins with minimum mineral sorting. The sources of the kaolins varied from basic to acidic and these were derived from an active margin tectonic setting. Lwamondo kaolin was deposited in an oxic environment whereas Zebediela kaolin was deposited under suboxic/anoxic conditions. Based on the δ18O and δD values of the kaolinite, they formed in a supergene environment at temperatures generally below 40 °C.

The tonalite–trondhjemite–granodiorite (TTG) to granodiorite–granite (GG) transition in the late Archean plutonic rocks of the central Wyoming Province

2006 ◽  
Vol 43 (10) ◽  
pp. 1419-1444 ◽  
Author(s):  
Carol D Frost ◽  
B Ronald Frost ◽  
Robert Kirkwood ◽  
Kevin R Chamberlain
Keyword(s):  
Rare Earth ◽  
Continental Crust ◽  
Rare Earth Element ◽  
Earth Element ◽  
Gradual Transition ◽  
Heavy Rare Earth Element ◽  
Isotopic Compositions ◽  
Similar Range ◽  
Wyoming Province ◽  
Ree Patterns

The 2.95–2.82 Ga quartzofeldspathic gneisses and granitoids in the Bighorn, western Owl Creek, and northeastern Wind River uplifts in the central Wyoming Province include low-K tonalite–trondhjemite–granodiorite (TTG) and high-K granodiorite–granite (GG) rocks. Both types of granitoids were intruded contemporaneously, although TTGs are more abundant in the older gneisses. The TTG suite consists of calcic to marginally calc-alkalic rocks that straddle the boundaries between metaluminous and peraluminous and between ferroan and magnesian compositions. Rare-earth element (REE) patterns of these rocks may be highly fractionated with low heavy rare-earth element (HREE) contents and modest to absent Eu anomalies but may also be less strongly HREE depleted. These rocks do not represent first-generation continental crust: most have unradiogenic Nd and radiogenic 207Pb/204Pb isotopic compositions that require the incorporation of isotopically evolved sources. The GG suite has compositions that are transitional between Archean TTG and modern, continental margin calc-alkalic rocks. The GG suite is characterized by higher alkali contents relative to CaO than the TTG suite and higher K/Na ratios but exhibits a similar range in REE patterns. The Nd, Sr, and Pb isotopic compositions of the GG suite are slightly less variable but lie within the range of those of the TTG suite. We interpret them as having a source similar to that of the TTG, perhaps forming by partial melting of preexisting TTG. The shift from TTG-dominated to GG-dominated continental crust was a gradual transition that took place over several hundred million years. Clearly subduction-related calc-alkalic magmatism is not recognized in the Wyoming Province prior to 2.67 Ga.

scholarly journals Rare Earth Element and Incompatible Trace Element Abundances in Emeralds Reveal Their Formation Environments

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 513
Author(s):  
Raquel Alonso-Perez ◽  
James M. D. Day
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Rare Earth Element ◽  
Earth Element ◽  
Regional Metamorphism ◽  
Incompatible Trace Element ◽  
Plate Tectonic ◽  
Element Abundances ◽  
Type Ia ◽  
Ree Patterns

Emeralds require the unusual association of typically compatible elements (Cr, V), with incompatible Be to form, and occur in complex tectonic settings associated with sediments (type IIB; Colombia) or, more commonly, with magmatism and regional metamorphism (IA). Precise rare earth element (REE) and incompatible trace element abundances are reported for a global suite of emeralds, enabling the identification of the environments in which they formed. Type IIB emeralds have nearly flat continental crust normalized REE patterns (La/YbCC = ~2), consistent with a sedimentary source origin. Type IA emerald REE patterns have upturns in the heavy REE (La/YbCC = ~0.3), a feature also shared with South African emeralds occurring in Archaean host rocks. Modeling of type IA emerald compositions indicates that they form from magmatic fluids of sedimentary (S)-type granite melts interacting with Cr, V-rich mafic–ultramafic crustal protoliths. This geochemical signature links emerald formation with continental suture zones. Diamonds, rubies, and sapphires have been considered as ‘plate tectonic gemstones’ based on mineral inclusions within them, or associations with plate tectonic indicators. Emeralds are distinct plate tectonic gemstones, recording geochemical evidence for origin within their mineral structure, and indicating that plate tectonic processes have led to emerald deposit formation since at least the Archaean.

Rare earth element patterns of carbonado and yakutite: evidence for their crustal origin

1993 ◽  
Vol 57 (389) ◽  
pp. 607-611 ◽  
Author(s):  
Ken Shibata ◽  
Hikari Kamioka ◽  
Felix V. Kaminsky ◽  
Vassili I. Koptil ◽  
Darcy P. Svisero
Keyword(s):  
Trace Elements ◽  
Rare Earth ◽  
Neutron Activation ◽  
Rare Earth Element ◽  
Earth Element ◽  
Meteorite Impact ◽  
Abundance Patterns ◽  
Eu Anomaly ◽  
Crustal Origin ◽  
Monocrystalline Diamond

AbstractCarbonado and yakutite are both porous aggregates of polycrystalline micrometre-size diamond, with very different characters from those of monocrystalline diamond. The genesis of carbonado is very controversial, whereas yakutite is thought to have been formed by meteorite impact. Neutron activation analyses of trace elements in carbonado and yakutite indicate that their rare earth element (REE) abundance patterns have common characteristics: heavy REEs are not much depleted and a negative Eu anomaly is observed. These patterns are quite different from those of kimberlite and monocrystalline diamond and are similar to those of crustal materials such as shale, supporting the hypothesis of a crustal origin for carbonado and yakutite.

Rare Earth Element and Trace Element Features of Gold-bearing Pyrite in the Jinshan Gold Deposit, Jiangxi Province

2010 ◽  
Vol 84 (3) ◽  
pp. 614-623 ◽  
Author(s):  
Guangzhou MAO ◽  
Renmin HUA ◽  
Jianfeng GAO ◽  
Kuidong ZHAO ◽  
Guangming LONG ◽  
...  
Keyword(s):  
Rare Earth ◽  
Trace Element ◽  
Gold Deposit ◽  
Rare Earth Element ◽  
Earth Element ◽  
Jiangxi Province ◽  
Gold Bearing
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