Results 41 to 50 of about 1,213,951 (200)

Petrography and mineral chemistry of Rosário-16 Kimberlite: an inference of P, T, and fO2 for an ultramafic alkaline assemblage in Southern Brazil [PDF]

Brazilian Journal of Geology
Rosário-16 (R-16) is a hypabyssal transitional kimberlite, divided into two volcanic pipes, R-16-A and R-16-B, within the Kimberlite Province of Rosário do Sul (KPRS), southeast of the Paraná Basin (PB), southeast Brazil. The saprolite outcrops, within a
Andrea Brum da Silva, Larissa Colombo Carniel, Rommulo Vieira Conceição, Gláucia Nascimento Queiroga, Andrea Sander, Marco Paulo de Castro   +5 more
doaj   +2 more sources

Covariation of Slab Tracers, Volatiles, and Oxidation During Subduction Initiation

Geochemistry, Geophysics, Geosystems, 2021
Subduction‐related lavas have higher Fe3+/∑Fe than midocean ridge basalts (MORB). Hypotheses for this offset include imprint from subducting slabs and differentiation in thickened crust.
Maryjo Brounce, Mark K. Reagan, Katherine A. Kelley, Elizabeth Cottrell, Kenji Shimizu, Renat Almeev   +5 more
doaj   +1 more source

Crystallization conditions of two adjacent epidote + diopside-bearing granitic stocks, northeastern Brazil

Anais da Academia Brasileira de Ciências, 2021
The Tamboril and Olho d’Água granitic stocks are part of the abundant calc-alkalic magmatic epidote-bearing granitic rocks in the Cachoeirinha–Salgueiro Terrane (CST) in the Transversal Zone Domain, northeastern Brazil. The equigranular Olho d’Água stock
RENAN SIQUEIRA, ALCIDES N. SIAL, VALDEREZ P. FERREIRA   +2 more
doaj   +1 more source

Quantification of Sulfur Speciation in Apatites: Comparison of the XAS, XPS and EPMA Techniques

Geostandards and Geoanalytical Research, EarlyView.
Key Points Sulfur speciation in apatites has been determined by S K‐edge X‐ray absorption near‐edge structure (XANES) spectroscopy, S 2p X‐ray photoelectron spectroscopy (XPS) and electron probe microanalysis (EPMA). XANES provides the most sensitive and accurate quantification of sulfur speciation.
Yuzhou Feng, Yuanming Pan, Leo Ka Long Cheung, Reza Deevsalar, Jason Maley, Huayong Chen, Haoran Dou, Mohsen Shakouri, Qunfeng Xiao   +8 more
wiley   +1 more source

Distribution and rare earth element abundances of apatite in Bennu samples determined by synchrotron X‐ray fluorescence spectroscopy

Meteoritics &Planetary Science, EarlyView.
Abstract Apatite is often the most rare earth element (REE)‐enriched mineral in chondritic meteorites. REE enrichment and fractionation levels in apatite grains can give insight into the aqueous fluids in which they formed and the conditions prevailing within the host body. In this study, we applied synchrotron X‐ray fluorescence (SXRF) spectroscopy to
B. J. Tkalcec, P. Tack, T. Baert, J. Herthogs, B. Vekemans, B. Bazi, E. De Pauw, M. Di Michiel, G. Falkenberg, J. Garrevoet, G. Libourel, M. Portail, V. Guigoz, C. Collin, H. C. Connolly Jr., D. S. Lauretta, L. Vincze, F. E. Brenker   +17 more
wiley   +1 more source

Competing effects of hydrogen, carbon, and sulfur degassing on the redox evolution of rising melts on terrestrial (exo)planets

Astronomy & Astrophysics
Context. Volcanic degassing is a key process controlling the formation and chemical evolution of secondary atmospheres on terrestrial planets. The redox state of ascending magma, commonly expressed as oxygen fugacity (fO2), strongly influences the ...
Brachmann C., Noack L., Gaillard F.
doaj   +1 more source

Constraining Ore-Forming Processes Using Magnetite-Titanomagnetite Chemistry: A Case Study of the Mamuniyeh Cu Mineralization System, Urumieh-Dokhtar Magmatic Arc

Journal of Economic Geology
The low-sulfidation epithermal copper mineralization in the Mamouniyeh area occurs as silica-sulfide-oxide veins hosted by monzonitic, gabbroic intrusions, and andesite.
Mohammad Goudarzi, Hassan Zamanian, Urs Klötzli, David Lentz, Matee Ullah   +4 more
doaj   +1 more source

The effect of oxygen fugacity on the evaporation of boron from aluminoborosilicate melt [PDF]

European Journal of Mineralogy
We present the results of B2O3 evaporation experiments from Ca- and Mg-bearing aluminoborosilicate melts. Our experiments were conducted at 1245 to 1249 ∘C and 1350 to 1361 ∘C for different run times (60–1020 min), and at oxygen fugacities (logfO2 ...
S. Flemetakis, S. Flemetakis, C. J. Renggli, P. Pangritz, J. Berndt, S. Klemme   +5 more
doaj   +1 more source

The use of predominance area diagrams (PAD) to determine the oxygen and sulfur fugacities prevailing during historical metallurgical processes: the case of fifteenth to seventeenth century copper slags from Polichno (Old Polish industrial district)

Heritage Science
The study presents the first use of predominance area diagrams (PADs) to determine oxidation–reduction conditions during reconstructing historical copper smelting processes.
Krzysztof Kupczak, Rafał Warchulski, Aleksandra Gawęda, Marta Ślęzak, Piotr Migas   +4 more
doaj   +1 more source

Contrasting apatite geochemistry between ore-bearing and ore-barren intrusions of the giant Kalmakyr gold-rich porphyry Cu deposit, Tien Shan, Uzbekistan

Frontiers in Earth Science, 2023
The Kalmakyr deposit in Uzbekistan is one of the world’s largest gold-rich porphyry Cu deposits, and mineralization was proposed to be closely associated with the emplacement of the latest intrusive phases, that is, granodiorite porphyry.
Yangtao Liu, Xiaobo Zhao, Chunji Xue, Chunji Xue, Bakhtiar Nurtaev, Jing Chen   +5 more
doaj   +1 more source