Results 21 to 30 of about 388 (174)

Petrology and geochemistry of a U and Th enriched nephelinite from Mt. Nyiragongo, Zaire: Its bearing on ancient mantle metasomatism [PDF]

Bulletin of the Geological Society of Finland, 1985
Unusual large Pb isotope variations found by Vollmer and Norry (1983 a) in nephelinites from Nyiragongo and related volcanoes date a 500 Myr old U(Th)/Pb fractionation.
R. Vollmer, P.H. Nixon, E. Condliffe
doaj   +1 more source

Spatial and temporal distribution, geochemical characteristics of carbonatites and their relationship with U–REE mineralization in the Xiaoqinling area, Shaanxi Province

Dizhi lixue xuebao
[ Objective ] Carbonatites, as magmatic-origin rocks, are crucial source rocks for uranium, rare earth, and other minerals. They are widely distributed in the Xiaoqinling region of Shaanxi, giving rise to numerous large to super-large carbonatite ...
KANG Qingqing, CHEN Zhengle, PAN Jiayong, LI Peng, LIU Yulong, LI Lei, JIANG Hongjun, GAO Cheng   +7 more
doaj   +1 more source

Fluids in the Siilinjärvi carbonatite complex, eastern Finland: Fluid inclusion evidence for the formation conditions of zircon and apatite [PDF]

Bulletin of the Geological Society of Finland, 1995
In the studied zircon and apatite crystals, data recorded two different compositional types of fluid inclusions: Type 1 H2O-CO2 low salinity inclusions (XCO2 = 0.42 to 0.87; XNaCl = 0.001 to 0.005) with bulk densities of 0.73 to 0.87 g/cm3, and Type 2 ...
M. Poutiainen
doaj   +1 more source

GEOCHRONOLOGY OF THE CHADOBETS ALKALINE ULTRAMAFIC CARBONATITE COMPLEX (SIBERIAN CRATON): NEW U-Pb AND Ar-Ar DATA

Геодинамика и тектонофизика, 2021
The Chadobets alkaline ultramafic carbonatite complex is located on the Siberian craton within the southern boundary of the Permian-Triassic plume activity.
I. R. Prokopyev, A. G. Doroshkevich, A. V. Malyutina, A. E. Starikova, A. V. Ponomarchuk, D. V. Semenova, S. A. Kovalev, I. A. Savinsky   +7 more
doaj   +1 more source

THE PROBLEM OF CARBONATITES AND CARBONATITE COMPLEXES

Geological Journal, 2016
На підставі аналізів авторських та літературних даних зроблено висновок про те, що первинний склад більшості карбонатитів був лужнокарбонатний типу карбонатитів і туфів вулкану Олдоіньо-Лентаї (з високим вмістом Na2CO3, K2CO3, CaCO3 і підпорядкованим – MgCO3, FeCO3).
openaire   +3 more sources

Carbonatitic Lavas [PDF]

Nature, 1962
Recently, von Knorring and du Bois described a vesicular lava of high carbonate content from western Uganda which shows close geochemical affinities with intrusive carbonatites. They stated: "It must be emphasized that the lavas examined are fresh and unaltered and that the carbonated nature cannot be attributed to alteration after solidification ...
Wyllie, P. J., Tuttle, O. F.
openaire   +2 more sources

RELATION BETWEEN δ¹³С, δ¹⁸О AND REE CONTENT IN CARBONATITES OF THE TOMTOR COMPLEX, SAKHA REPUBLIC (YAKUTIA)

Геодинамика и тектонофизика
The paper reports the comprehensive study of phosphorus-rare metal (polymineral) carbonatites (I) and rare metal (ankerite) carbonatites (II) of the Tomtor massif based on ICP-MS, XRF, XRF-SI, SEM methods and isotope determination of C, O and 86Sr/87Sr ...
V. A. Ponomarchuk, E. V. Lazareva, S. M. Zhmodik, A. V. Travin, A. V. Tolstov   +4 more
doaj   +1 more source

Insight into differentiation in alkalic systems: Nephelinite-carbonate-water experiments aimed at Ol Doinyo Lengai carbonatite genesis

Frontiers in Earth Science, 2022
Ol Doinyo Lengai (ODL, Tanzania, East African Rift) is the only known volcano currently erupting carbonatite on Earth with 30 yr. cycles alternating between quiescent carbonatite effusion and explosive, compositionally-zoned silicate eruptions.
Craig C. Lundstrom, Rick Hervig, Tobias P. Fischer, Mayandi Sivaguru, Leilei Yin, Zhenhao Zhou, Xiaobao Lin, Rodrigo Grossi-Diniz   +7 more
doaj   +1 more source

Stable (C, O, S) isotopes and whole-rock geochemistry of carbonatites from Alto Paranaíba Igneous Province, SE Brazil

Brazilian Journal of Geology
: The present work investigates the relationship between whole-rock geochemistry and stable isotope composition from carbonatites belonging to the Tapira, Araxá, Salitre, Serra Negra, Catalão I, and Catalão II alkaline-carbonatite complexes of the Alto ...
Caroline Siqueira Gomide, José Affonso Brod, Lucieth Cruz Vieira, Tereza Cristina Junqueira-Brod, Ivan Alejandro Petrinovic, Roberto Ventura Santos, Elisa Soares Rocha Barbosa, Luis Henrique Mancini   +7 more
doaj   +1 more source

Facial accessory of high-titanium magnezium-ferruginous micas as one of evaluation criteria of metamorphic and magmatic rocks rare-metall specialization

Литосфера, 2015
Type-chemical features of high-titanium magnezium-ferruginous micas of granulites, mafite-ultramafites, alkaline rocks, and carbonatites are considered.
A. I. Belkovsky
doaj   +2 more sources