scholarly journals Age, composition and sources of rocks and ores of the Okunevskoe fluorite-leucophanite deposit, Western Sayan: assessment of the contribution of magmatism to ore mineralization

2019 ◽  
Vol 61 (5) ◽  
pp. 37-61
Author(s):  
D. A. Lykhin ◽  
V. V. Yarmolyuk ◽  
A. A. Vorontsov
Keyword(s):  
Rare Metal ◽  
Igneous Rocks ◽  
Early Paleozoic ◽  
Age Composition ◽  
Geochemical Parameters ◽  
Ore Mineralization ◽  
Metallogenic Zone ◽  
Western Sayan ◽  
T Values ◽  
Ore Types

The paper presents data on the structure of the Okunevskoe fluorite-Leucophanite deposit, located within the Early Paleozoic rare-metal East Sayan rare metal metallogenic zone. The deposit is controlled by alkali granitoids, with ore mineralization concentrated at the contact of granitoids and host carbonates. It is represented by leucophanite-fluorite and pyroxene-fluorite ore types. The Ar-Ar age of granitoids is established at ~485Ma. Geochemical characteristics of igneous rocks, ores, and host carbonates are determined. It is shown that in geochemical parameters leucophanite-fluorite ores are close to alkaline granites, while pyroxene-fluorite ores are close to alkaline syenites. The characteristics of the Nd isotop composition in rocks and ores of the deposit are given. Igneous rocks (granitoids and basite dikes) are characterized byNd (t) values from +4 to +5.5. TheNd (t) values in ores range from +1.2 to+4.2, in skarns itis +4.8. The host carbonates have abruptly contrasting valuesNd (t) = 4.2. Based on these data, which demonstrate a high compositional similarity between granitoids and ores, aconclusion is drawn about the leading contribution from magmatic processes to the ore mineralization of the Okunevskoe deposit.

scholarly journals Structure and age of the fluorite-berillium deposit of the field Rainbow, Western Sayan Mountains: to the problem of assessment of metallogenic prospects of the territory

2019 ◽  
Vol 488 (3) ◽  
pp. 282-287
Author(s):  
D. A. Lykhin ◽  
V. V. Yarmolyuk ◽  
A. A. Vorontsov ◽  
A. V. Travin
Keyword(s):  
Carbonate Rocks ◽  
Rare Metal ◽  
Early Paleozoic ◽  
Geochemical Parameters ◽  
Rare Metal Mineralization ◽  
Metallogenic Zone ◽  
Western Sayan ◽  
The Relationship ◽  
Good Agreement ◽  
Geochemical Specialization

The age and geochemical parameters of the muscovite-fluorite-euclase-beryl Raduga deposit, which is located within the Kizir-Kazyr zone of rare-metal magmatism, are determined. In contrast to other deposits and ore occurrences of the zone, represented by alkaline granites characterized by rare metal mineralization, the Raduga deposit is associated with metasomatites in carbonate rocks. The age of the deposit, estimated at 40Ar/39Ar by the muscovite method of beryllium fluorite-muscovite greisens, is 469.3± 4.5Ma. It corresponds to the age of the ore-bearing alkaline granites of the zone. The dikes which occur within the deposit are identical by the composition to the dikes of rare-metal alkaline granitic massifs, one of which is located in a few kilometers from the deposit. The nature of the ore Be-Li mineralization of the deposit is in good agreement with the geochemical specialization of the Early Paleozoic Kizir-Kazyr metallogenic zone. The revealed features of the relationship between Raduga deposit and rare-metal deposits in alkaline granites suggests a variety of mechanisms involved in the formation of rare-metal deposits of the Kizir-Kazyr zone. Thus, it allows to expand approaches for prediction and exploration of rare-metal deposits in the region.

scholarly journals GRANITOIDS, RARE-METAL PEGMATITES AND Ta-Nb MINERALIZATION OF SHPOLIANO-TASHLYK ORE AREA (INGUL MEGABLOCK, UKRAINIAN SHIELD)

2018 ◽  
pp. 24-29
Author(s):  
O. Hrinchenko ◽  
S. Bondarenko ◽  
T. Mironchuk
Keyword(s):  
Rare Metal ◽  
Ukrainian Shield ◽  
Wide Range ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Isomorphic Series ◽  
Single Complex ◽  
Complex Features ◽  
First Time ◽  
Range Of Values

Composition of granites, genetically associated pegmatites and superimposed metasomatites distributed within Shpoliano-Tashlyk ore area (Ingul megablock) is considered. It is established, that on the basis of similarity in their petrographic and petrochemical features granitoids of the area can be related to single complex. Features of ore mineralization are defined by both composition of granitoids (Sgranites) after which rare-metal pegmatites are formed and intensity of superimposed metasomatic alterations. Main minerals-concentrators of Ta and Nb mineralization in granitic pegmatites and metasomatites are represented by minerals of three isomorphic series – columbite-tantalite (Fe,Mn)(Nb,Ta,Ti)2O6, ilmenorutile-struverite (Ti,Nb,Ta)O2 and pyrochlore-microlite (Ca,Na)2Ta2O6(O,B,OH,F). Depending on geological setting such ore minerals as tapiolite, ixiolite, cassiterite, uraninite, nigerite, gahnite are commonly found in association with these minerals. Chemical composion of tantalo-niobates sampled from ore-bearing pegmatites and metasomatites is investigated by microprobe analysis. Most minerals of columbite-tantalite series are characterized by distinct and rhythmic internal zonality and contrasting mosaic structure which are related to considerable heterogeneities of their chemical composition. Within one aggregate mineral phases with wide range of values – from 9,80 to 71,0 % for Ta2O5 and from 10,6 to 70,1 % for Nb2O5 – are established. Among minerals ferruginous varieties which composition relates to Fe-columbite-tantalites (Nb2O5/Ta2O5 = 1–1,2; FeO/MnO = 2,5–6) prevail. Columbite-tantalites are characterised by high contents of admixture elements present (%): TiO2 – to 5,88; WO3 – to 3,70; SnO2 – to 9,20; Sc2O3 – to 5,40. Scandium ores occur as scandium-rich minerals that are mostly confined to the minerals of columbite-tantalite series found in Polohivka ore field. On the Ukrainian Shield high contents of Sc2O3 in tantalo-niobates are established for the first time. Minerals of ilmenorutile-struverite series do not quantitatively yield to minerals of columbite-tantalite series. For minerals of this series Nb2O5/Ta2O5 ratio varies in the range of 0,6-1,4. Among characteristic admixture-elements are prevailed (%): SnO2 – to 3,1, V2O5 – to 5,05; FeO – to 11,51, Cr2O3 – to 1,20. Minerals of pyrochlore-microlite series are of subordinate importance. For the first time by results of U-Pb dating of columbite-tantalites from Mostove ore manifestation (Shpoliano-Tashlyk area) the age of Ta-Nb mineralization is established to be about 1965 ± 25 million years.

Origin of syn-collisional granitoids in the Gangdese orogen: Reworking of the juvenile arc crust and the ancient continental crust

2021 ◽  
Author(s):  
Yu-Wei Tang ◽  
Long Chen ◽  
Zi-Fu Zhao ◽  
Yong-Fei Zheng
Keyword(s):  
Partial Melting ◽  
Continental Crust ◽  
Continental Collision ◽  
Late Eocene ◽  
Igneous Rocks ◽  
Early Eocene ◽  
Southern Tibet ◽  
Crustal Rocks ◽  
Mafic Magmas ◽  
T Values

Granitoids at convergent plate boundaries can be produced either by partial melting of crustal rocks (either continental or oceanic) or by fractional crystallization of mantle-derived mafic magmas. Whereas granitoid formation through partial melting of the continental crust results in reworking of the pre-existing continental crust, granitoid formation through either partial melting of the oceanic crust or fractional crystallization of the mafic magmas leads to growth of the continental crust. This category is primarily based on the radiogenic Nd isotope compositions of crustal rocks; positive εNd(t) values indicate juvenile crust whereas negative εNd(t) values indicate ancient crust. Positive εNd(t) values are common for syn-collisional granitoids in southern Tibet, which leads to the hypothesis that continental collision zones are important sites for the net growth of continental crust. This hypothesis is examined through an integrated study of in situ zircon U-Pb ages and Hf isotopes, whole-rock major trace elements, and Sr-Nd-Hf isotopes as well as mineral O isotopes for felsic igneous rocks of Eocene ages from the Gangdese orogen in southern Tibet. The results show that these rocks can be divided into two groups according to their emplacement ages and geochemical features. The first group is less granitic with lower SiO2 contents of 59.82−64.41 wt%, and it was emplaced at 50−48 Ma in the early Eocene. The second group is more granitic with higher SiO2 contents of 63.93−68.81 wt%, and it was emplaced at 42 Ma in the late Eocene. The early Eocene granitoids exhibit relatively depleted whole-rock Sr-Nd-Hf isotope compositions with low (87Sr/86Sr)i ratios of 0.7044−0.7048, positive εNd(t) values of 0.6−3.9, εHf(t) values of 6.5−10.5, zircon εHf(t) values of 1.6−12.1, and zircon δ18O values of 5.28−6.26‰. These isotopic characteristics are quite similar to those of Late Cretaceous mafic arc igneous rocks in the Gangdese orogen, which indicates their derivation from partial melting of the juvenile mafic arc crust. In comparison, the late Eocene granitoids have relatively lower MgO, Fe2O3, Al2O3, and heavy rare earth element (HREE) contents but higher K2O, Rb, Sr, Th, U, Pb contents, Sr/Y, and (La/Yb)N ratios. They also exhibit more enriched whole-rock Sr-Nd-Hf isotope compositions with high (87Sr/86Sr)i ratios of 0.7070−0.7085, negative εNd(t) values of −5.2 to −3.9 and neutral εHf(t) values of 0.9−2.3, and relatively lower zircon εHf(t) values of −2.8−8.0 and slightly higher zircon δ18O values of 6.25−6.68‰. An integrated interpretation of these geochemical features is that both the juvenile arc crust and the ancient continental crust partially melted to produce the late Eocene granitoids. In this regard, the compositional evolution of syn-collisional granitoids from the early to late Eocene indicates a temporal change of their magma sources from the complete juvenile arc crust to a mixture of the juvenile and ancient crust. In either case, the syn-collisional granitoids in the Gangdese orogen are the reworking products of the pre-existing continental crust. Therefore, they do not contribute to crustal growth in the continental collision zone.

Recycling of Paleo-oceanic crust: Geochemical evidence from Early Paleozoic mafic igneous rocks in the Tongbai orogen, Central China

Lithos ◽  
2019 ◽  
Vol 328-329 ◽  
pp. 312-327 ◽  
Author(s):  
Fei Zheng ◽  
Li-Qun Dai ◽  
Zi-Fu Zhao ◽  
Yong-Fei Zheng ◽  
Zheng Xu
Keyword(s):  
Oceanic Crust ◽  
Igneous Rocks ◽  
Central China ◽  
Early Paleozoic ◽  
Geochemical Evidence

Age and geological position of the Okunyovo rare-metal ore magmatic complex (Western Sayan Mountains)

2017 ◽  
Vol 477 (2) ◽  
pp. 1379-1383 ◽  
Author(s):  
D. A. Lykhin ◽  
V. V. Yarmolyuk ◽  
A. A. Vorontsov ◽  
A. V. Travin
Keyword(s):  
Rare Metal ◽  
Magmatic Complex ◽  
Western Sayan ◽  
Geological Position

Age, composition and tectonic implications of late Ordovician-early Silurian igneous rocks of the Loel Volcanic Belt, NW Laos

2019 ◽  
Vol 61 (15) ◽  
pp. 1940-1956 ◽  
Author(s):  
Yongzhen Long ◽  
Dexian Zhang ◽  
Dezhi Huang ◽  
Xiaoyong Yang ◽  
Shanshan Chen ◽  
...  
Keyword(s):  
Volcanic Belt ◽  
Late Ordovician ◽  
Igneous Rocks ◽  
Age Composition ◽  
Tectonic Implications

scholarly journals Rare-Metal Pegmatite Deposits of the Kalba Region, Eastern Kazakhstan: Age, Composition and Petrogenetic Implications

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 1017
Author(s):  
Sergey V. Khromykh ◽  
Tatiana A. Oitseva ◽  
Pavel D. Kotler ◽  
Boris A. D’yachkov ◽  
Sergey Z. Smirnov ◽  
...  
Keyword(s):  
Phase 1 ◽  
Rare Metal ◽  
Rare Metals ◽  
Geochronological Data ◽  
Age Composition ◽  
Deep Faults ◽  
Mineral Assemblages ◽  
Rare Metal Pegmatite ◽  
Ore District ◽  
Eastern Kazakhstan

The paper presents new geological, mineralogical, and isotope geochronological data for rare-metal pegmatites in the Kalba granitic batholith (Eastern Kazakhstan). Mineralization is especially abundant in the Central-Kalba ore district, where pegmatite bodies occur at the top of large granite plutons and at intersections of deep faults. The pegmatites contain several successive mineral assemblages from barren quartz-microcline and quartz-microcline-albite to Li-Cs-Ta-Nb-Be-Sn-bearing cleavelandite-lepidolite-spodumene. Ar-Ar muscovite and lepidolite ages bracket the metallogenic event between 291 and 286 Ma. The pegmatite mineral deposits formed synchronously with the emplacement of the phase 1 Kalba granites during the evolution of hydrous silicate rare-metal magmas that are produced by the differentiation of granite magma at large sources with possible inputs of F and rare metals with fluids.

Ordo-Silurian assemblage in the Indochina interior: Geochronological, elemental, and Sr-Nd-Pb-Hf-O isotopic constraints of early Paleozoic granitoids in South Laos

2020 ◽  
Vol 133 (1-2) ◽  
pp. 325-346 ◽  
Author(s):  
Yuejun Wang ◽  
Yuzhi Zhang ◽  
Xin Qian ◽  
Vongpaseuth Senebouttalath ◽  
Yang Wang ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
High Field ◽  
Igneous Rocks ◽  
Early Paleozoic ◽  
Isotopic Data ◽  
High Field Strength ◽  
Tectonic Zone ◽  
Type Granite ◽  
Juvenile Crust ◽  
South Tibet

Abstract In order to verify the early Paleozoic accretionary assemblage in the Indochina interior and constrain the Prototethyan tectonic evolution in Southeast Asia, this study presents a set of new U-Pb geochronological, elemental, and Sr-Nd-Pb-Hf-O isotopic data for the fifty-two representative granitoids in South Laos. The granitoids from the Kontum terrane, Tam Ky-Phuoc Son tectonic zone, and southern Truong Son igneous zone in South Laos yield the crystallization ages of 464–485 Ma, 455–471 Ma, and 427–446 Ma, respectively, with a northerly younging trend within the Indochina interior. They are mainly monzogranite with A/CNK = 0.96–1.99 and K2O > Na2O, which are marked by enrichment in large-ion lithophile elements and depletion in high field strength elements with remarkable Nb-Ta, Sr-P, and Ti negative anomalies. Their initial 87Sr/86Sr ratios range from 0.70510 to 0.71559, εNd(t) from −9.5 to −3.0, (206Pb/204Pb)i from 18.65 to 19.72, (207Pb/204Pb)i from 15.66 to 15.80, and (208Pb/ 204Pb)i from 38.84 to 39.79. The corresponding zircon ɛHf(t) and δ18O values are in the range of −10.6 to +1.0 and 6.88‰ to 8.94‰, respectively. In addition, their Sr-Nd-Pb and Hf-O isotopic compositions are generally similar with those of time-equivalent granitoids in South Tibet and SW Yunnan, China, and synchronous mafic-intermediate igneous rocks in South Laos, but distinctive from those of the supracrustal sedimentary-derived South China Paleozoic granite and Lincang-Sukhothai S-type granite. The early Paleozoic granitoids in South Laos might have originated from a mixed source of the wedge-derived juvenile crust coupled with supracrustal materials. All these data synthetically suggest the southward subduction of the Tam Ky-Phuoc Son Ocean and the northerly on-growing Ordo-Silurian accretionary orogenesis within the previously defined “single-ancient” Indochina block. The assemblage of the Indochina block might initiate at ca. 430 Ma in the Silurian and terminate in the Early-Middle Devonian.

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