Geochemistry, Mineralogy and Ore Content of Alkaline Granite Magmatism of East Sayan Zone (On the Example of Zashikhinsky Deposit)

2021 ◽  
pp. 63-80
Author(s):  
N. V. Alymova ◽  
N. V. Vladykin
Keyword(s):  
Alkaline Granite ◽  
Granite Magmatism

Early permian age of nepheline syenites of the Korgere-Daba massif (Sangilen highlands, Tuva)

2019 ◽  
Vol 485 (2) ◽  
pp. 194-197
Author(s):  
A. V. Nikiforov ◽  
E. B. Salnikova ◽  
V. V. Yarmolyuk ◽  
A. B. Kotov ◽  
A. M. Sugorakova ◽  
...  
Keyword(s):  
Nepheline Syenite ◽  
Early Permian ◽  
Alkaline Granite ◽  
Granite Magmatism ◽  
Alkaline Massif

This paper reports on geochronological U–Pb studies of baddeleyite from nepheline syenite of the Korgere–Daba alkaline massif, which is the largest massif within the Sangilen Highlands (Tyva). The established age of rocks, 295 ± 1 Ma, indicates that, in the Early Permian, undersaturation by silica magmatism occurred in the region in addition to the alkaline-granite magmatism (Ulug–Tanzek, etc.). This age furthermore points to the need to make corrections in the conceptions of a petrophysical type for the Devonian Sangilen complex, which is traditionally distinguished in this region. Until now, the Korgere–Daba massif has been considered in this regard.

Contribution of alkaline granite magmatism to the formation of the Khangai batholith: Geological and geochronological evidence

2013 ◽  
Vol 452 (2) ◽  
pp. 992-996 ◽  
Author(s):  
V. V. Yarmolyuk ◽  
A. M. Kozlovsky ◽  
E. B. Sal’nikova ◽  
A. B. Kotov ◽  
A. V. Travin ◽  
...  
Keyword(s):  
Alkaline Granite ◽  
Granite Magmatism ◽  
Geochronological Evidence

scholarly journals Early mesozoic alkaline magmatism of the western framing of the Mongol-Okhotsk belt: age and structural position

2019 ◽  
Vol 488 (1) ◽  
pp. 62-66
Author(s):  
V. V. Yarmolyuk ◽  
A. M. Kozlovsky ◽  
E. B. Sal`nikova ◽  
G. Eenzhin
Keyword(s):  
Melting Zone ◽  
Igneous Rocks ◽  
Alkaline Magmatism ◽  
Formation Processes ◽  
Alkaline Granite ◽  
Structural Position ◽  
The North ◽  
Early Mesozoic ◽  
Southern Border ◽  
Granite Magmatism

A zonal igneous area appeared at the western end of the Mongol-Okhotsk belt in the early Mesozoic. Its central part forms a giant Khentey-Dauria batholith, which from the north and west is framed by rift-like structures with bimodal and alkaline granite magmatism. The geochronological studies of the peralkaline granites of the Choyr and Gal-Shara massifs were carried out. These massifs belong to the North Gobi (southern) border of the batholith. The age of the first was 215 million years, the age of the second was 213 million years. It is shown that associations involving alkaline igneous rocks are fairly well developed in the North Gobi zone. They are controlled by faults and grabens of the northeast strike. Thus, it was established that the formation of the zonal magmatic area was characterized by a specific mode. In its central part, which corresponds to the zone of the Mongol-Okhotsk suture, anatexis and batholite formation processes took place, and the periphery was involved in the processes of rifting. The data obtained indicate the closure of the western part of the Mongol-Okhotsk trough before the formation of the zonal magmatic area. The structure of the magmatic area was determined by the mechanisms of the plume-lithospheric interaction in the region characterized by a collision suture (anatectic melting zone) and its less tektonic tense framing (rifting zones).

scholarly journals Petrogenesis of a late-stage calc-alkaline granite in a giant S-type batholith: geochronology and Sr–Nd–Pb isotopes from the Nomatsaus granite (Donkerhoek batholith), Namibia

2021 ◽  
Author(s):  
S. Aspiotis ◽  
S. Jung ◽  
F. Hauff ◽  
R. L. Romer
Keyword(s):  
Partial Melting ◽  
Mineral Assemblage ◽  
Central Zone ◽  
Calc Alkaline ◽  
Pb Isotope ◽  
Alkaline Granite ◽  
Ti Oxides ◽  
Eu Anomaly ◽  
Environment Characteristic ◽  
Southern Central

AbstractThe late-tectonic 511.4 ± 0.6 Ma-old Nomatsaus intrusion (Donkerhoek batholith, Damara orogen, Namibia) consists of moderately peraluminous, magnesian, calc-alkalic to calcic granites similar to I-type granites worldwide. Major and trace-element variations and LREE and HREE concentrations in evolved rocks imply that the fractionated mineral assemblage includes biotite, Fe–Ti oxides, zircon, plagioclase and monazite. Increasing K2O abundance with increasing SiO2 suggests accumulation of K-feldspar; compatible with a small positive Eu anomaly in the most evolved rocks. In comparison with experimental data, the Nomatsaus granite was likely generated from meta-igneous sources of possibly dacitic composition that melted under water-undersaturated conditions (X H2O: 0.25–0.50) and at temperatures between 800 and 850 °C, compatible with the zircon and monazite saturation temperatures of 812 and 852 °C, respectively. The Nomatsaus granite has moderately radiogenic initial 87Sr/86Sr ratios (0.7067–0.7082), relatively radiogenic initial εNd values (− 2.9 to − 4.8) and moderately evolved Pb isotope ratios. Although initial Sr and Nd isotopic compositions of the granite do not vary with SiO2 or MgO contents, fSm/Nd and initial εNd values are negatively correlated indicating limited assimilation of crustal components during monazite-dominated fractional crystallization. The preferred petrogenetic model for the generation of the Nomatsaus granite involves a continent–continent collisional setting with stacking of crustal slices that in combination with high radioactive heat production rates heated the thickened crust, leading to the medium-P/high-T environment characteristic of the southern Central Zone of the Damara orogen. Such a setting promoted partial melting of metasedimentary sources during the initial stages of crustal heating, followed by the partial melting of meta-igneous rocks at mid-crustal levels at higher P–T conditions and relatively late in the orogenic evolution.

Timing of Paleoproterozoic granitoid magmatism along the northwestern Superior Province margin: implications for the tectonic evolution of the Thompson Nickel BeltThis article is one of a series of papers published in this Special Issue on the theme of Geochronology in honour of Tom Krogh.

2011 ◽  
Vol 48 (2) ◽  
pp. 325-346 ◽  
Author(s):  
N. Machado ◽  
L. M. Heaman ◽  
T. E. Krogh ◽  
W. Weber ◽  
M. T. Corkery
Keyword(s):  
Sensu Stricto ◽  
Crustal Thickening ◽  
Superior Province ◽  
Granitoid Magmatism ◽  
Continental Block ◽  
Granitic Magmatism ◽  
Peak Metamorphism ◽  
Granite Magmatism ◽  
Superior Craton ◽  
Superior Margin

The U–Pb geochronology of three granitoid plutons and three granitic pegmatite dykes, largely from the Thompson Nickel Belt located along the northwestern Superior craton margin, was investigated to place constraints on the timing of felsic magmatism associated with closure of the Manikewan Ocean and final continent–continent collision to form the Trans-Hudson Orogen. These data indicate that 1840–1820 Ma granite magmatism along the Superior margin was more active than previously thought and that some magmatism extended beyond the Thompson Nickel Belt sensu stricto, including the 1836 ± 3 Ma Mystery Lake granodiorite, 1822 ± 5 Ma Wintering Lake granodiorite, and the 1825 ± 8 Ma Fox Lake granite located in the Split Lake Block. Granitic pegmatites within the Thompson Nickel Belt were emplaced late in the collisional history in the period 1.79–1.75 Ga and include a 1770 ± 2 Ma dyke exposed at the Thompson pit, a 1767 ± 6 Ma dyke at the Pipe Pit, and a 1786 ± 2 Ma dyke located at Paint Lake. The final stage of crustal amalgamation in the eastern Trans-Hudson Orogen involved Superior Province crustal thickening and partial melting forming 1.84–1.82 Ga granite magmas and then final collision at ∼1.8 Ga between the Superior Province and a continental block to the west consisting of the previously amalgamated Sask and Hearne cratons. Heating of the Superior craton margin and granitic magmatism continued past peak metamorphism (1790–1750 Ma); this thermal event is represented by the emplacement of numerous late pegmatite dykes and evidenced by cooling dates recorded by metamorphic minerals (e.g., titanite) in reworked Archean gneisses and Proterozoic intrusions.

CASSERITE U-Pb GEOCHRONOLOGY OF THE SANTA BÁRBARA TIN DISTRICT, RONDÔNIA TIN PROVINCE, BRAZIL

2021 ◽  
Author(s):  
Frederico Sousa Guimarães ◽  
Rongqing Zhang ◽  
Bernd Lehmann ◽  
Alexandre Raphael Cabral ◽  
Francisco Javier Rios
Keyword(s):  
Inductively Coupled Plasma ◽  
Rare Metal ◽  
Santa Barbara ◽  
Rare Metal Granite ◽  
Inductively Coupled ◽  
Granite Emplacement ◽  
Amazonian Craton ◽  
Plasma Mass Spectrometry ◽  
Granite Magmatism ◽  
Intrusive Suite

Abstract The Mesoproterozoic Rondônia Tin Province of the Amazonian craton records a protracted history of about 600 m.y. of successive rare-metal granite intrusions and hosts the youngest known event of tin-granite emplacement of the craton—a rare-metal granite suite known as the Younger Granites of Rondônia intrusive suite. The ~1 Ga suite is currently interpreted as intracratonic magmatism resulting from a Grenvillian-age orogeny during the assembly of Rodinia. The Santa Bárbara massif is a tin-granite system of the Younger Granites of Rondônia intrusive suite that hosts Sn-Nb-Ta-W–bearing endogreisen and stockwork, as well as important placer deposits. The Santa Bárbara mine produces about 800 to 1,000 t Sn/year from placers and weathered greisen and represents about 20% of the tin mine output of the Rondônia Tin Province. Here, we report laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) cassiterite U-Pb ages of 989 ± 3 and 987 ± 6 Ma for the Santa Bárbara greisen and the cassiterite-quartz vein system, respectively. Alluvial cassiterite from placer mining has a U-Pb age of 995 ± 4 Ma, which is, within uncertainty, indistinguishable from those of primary cassiterite. These ages agree well with the previously published zircon and monazite U-Pb ages for the Santa Bárbara granite (978 ± 13 and 989 ± 13 Ma), which indicate a coeval relationship between hydrothermal tin mineralization and granite magmatism. The previously suggested 20- to 30-m.y. time span between granite magmatism and hydrothermal tin mineralization, which was based on mica K-Ar and Ar-Ar age data, is likely due to younger thermal disturbance of the isotopic systems.

Release of Uranium from Uraninite in Granites Through Alteration: Implications for the Source of Granite-Related Uranium Ores

2021 ◽  
Author(s):  
Long Zhang ◽  
Zhenyu Chen ◽  
Fangyue Wang ◽  
Noel C. White ◽  
Taofa Zhou
Keyword(s):  
Uranium Concentration ◽  
Geochemical Data ◽  
Uranium Deposits ◽  
Bulk Rock ◽  
Calc Alkaline ◽  
Alkaline Granite ◽  
Compositional Evolution ◽  
High K ◽  
Backscattered Electron ◽  
Uranium Sources

Abstract Uraninite is the main contributor to the bulk-rock uranium concentration in many U-rich granites and is the most important uranium source for granite-related uranium deposits. However, detailed textural and compositional evolution of magmatic uraninite in granites during alteration and associated uranium mobilization have not been well documented. In this study, textures and geochemistry of uraninites from the Zhuguangshan batholith (South China) were investigated by scanning electron microscopy (SEM) and electron probe microanalysis (EPMA). The geochemical data indicate that the Longhuashan and Youdong plutons are peraluminous leucogranite, the Changjiang pluton is highly fractionated high-K calc-alkaline granite, and the Jiufeng pluton belongs to a high-K calc-alkaline association. Uraninites from the Longhuashan and Youdong granites have lower concentrations of ThO2 (0.9–4.0 wt %) and rare earth elements (REE)2O3 (0.1–1.0 wt %) than those from the Changjiang and Jiufeng granites (ThO2 = 4.4–7.6 wt %, REE2O3 = 0.7–5.1 wt %). Uraninites observed in the Longhuashan, Youdong, Changjiang, and Jiufeng granites yielded chemical ages of 223 ± 3, 222 ± 2, 157 ± 1, and 161 ± 2 Ma, respectively. The samples (including altered and unaltered) collected from the Longhuashan, Youdong, and Changjiang granites are characterized by highly variable whole-rock U concentrations of 6.9 to 44.7 ppm and Th/U ratios of 0.9 to 7.0, consistent with crystallization of uraninite in these granites being followed by uranium leaching during alteration. Alteration of uraninite, indicated by altered domains developing microcracks and appearing darker in backscattered electron (BSE) images compared to unaltered domains, results in the incorporation of Si and Ca and mobilization of U. In contrast, the least altered samples of the unmineralized Jiufeng granite have low U concentrations (5.3–16.4 ppm) and high ΣREE/U (13.6–49.4) and Th/U ratios (2.1–5.6), which inhibit crystallization of uraninite, as its crystallization occurs when the U concentration is high enough to exceed the substitution capacity of other U-bearing minerals. These results indicate that the Longhuashan, Youdong, and Changjiang granites were favorable uranium sources for the formation of uranium deposits in this area. This study highlights the potential of uraninite alteration and geochemistry to assist in deciphering uranium sources and enrichment processes of granite-related uranium deposits.

Geochronology and geochemistry of igneous rocks in the southeastern Lesser Xing’an Range, northeastern China: petrogenesis and implications for the early Mesozoic tectonic evolution

2020 ◽  
Vol 57 (4) ◽  
pp. 506-523
Author(s):  
Jin-hua Qin ◽  
Cui Liu ◽  
Jin-fu Deng
Keyword(s):  
Field Strength ◽  
Inductively Coupled Plasma ◽  
High Field ◽  
Magma Mixing ◽  
Tectonic Setting ◽  
Alkali Feldspar ◽  
Igneous Rocks ◽  
Geochemical Data ◽  
High Field Strength ◽  
Alkaline Granite

We present systematic U–Pb age data collected by laser ablation multi-collector inductively coupled plasma mass spectrometry, precise geochemical data, and Nd isotope data for igneous rocks from the southeastern Lesser Xing’an Range (SE LXR). The results indicate that the formation ages as follows: Maojiatun alkaline granite, 207.2 ± 0.84 Ma and 204.6 ± 0.93 Ma; Diorite porphyrite, 164.5 ± 0.97 Ma; and Tieli syenogranite, 186.7 ± 1.50 Ma. The alkaline granite has high silicon, potassium, alkali, and FeOT contents; it is enriched in high field strength elements, Zr, Hf, Th, Rb, and U; is depleted in Ba, Sr, Nb, Ta, P, Ti, etc.; and has high ratios of 10000Ga/Al. It shows an A2-type granite affinity. The Tieli alkali-feldspar granite has high total alkali contents and is enriched in high field strength elements and rare earth elements and depleted in Sr, Ba, Ti, and P, and shows varying degrees of alkalinity. Rocks from SE LXR display similar εNd (t) values with corresponding to Nd model ages of 1095 to 813 Ma. The igneous rocks from the SE LXR are proposed to be derived from melting of the Neoproterozoic lower crust and potential magma mixing with ancient crystalline basement. The formation of the Maojiatun alkaline granite occurred in response to a postorogenic event following the closure of the Paleo-Asian Ocean. However, the SE LXR exhibited an extensional back-arc tectonic setting in the Early Jurassic. The Middle Jurassic diorite porphyrite could be related to the temporary stagnation of the westward subduction of the Paleo-Pacific plate.

scholarly journals Widespread Permian granite magmatism in Lower Austroalpine units: significance for Permian rifting in the Eastern Alps

2020 ◽  
Vol 113 (1) ◽  
Author(s):  
Sihua Yuan ◽  
Franz Neubauer ◽  
Yongjiang Liu ◽  
Johann Genser ◽  
Boran Liu ◽  
...  
Keyword(s):  
Tectonic Setting ◽  
Eastern Alps ◽  
Geochemical Data ◽  
Calc Alkaline ◽  
Three Samples ◽  
High K ◽  
Icp Ms ◽  
Granite Magmatism ◽  
Austroalpine Unit ◽  
Granite Suite

Abstract The Grobgneis complex, located in the eastern Austroalpine unit of the Eastern Alps, exposes large volumes of pre-Alpine porphyric metagranites, sometimes associated with small gabbroic bodies. To better understand tectonic setting of the metagranites, we carried out detailed geochronological and geochemical investigations on the major part of the porphyric metagranites. LA–ICP–MS zircon U–Pb dating of three metagranites sampled from the Grobgneis complex provides the first reliable evidence for large volumes of Permian plutonism within the pre-Alpine basement of the Lower Austroalpine units. Concordant zircons from three samples yield ages at 272.2 ± 1.2 Ma, 268.6 ± 2.3 Ma and 267.6 ± 2.9 Ma interpreted to date the emplacement of the granite suite. In combination with published ages for other Permian Alpine magmatic bodies, the new U–Pb ages provide evidence of a temporally restricted period of plutonism (“Grobgneis”) in the Raabalpen basement Complex during the Middle Permian. Comparing the investigated basement with that of the West Carpathian basement, we argue that widespread Permian granite magmatism occurred in the Lower Austroalpine units. They belong to the high-K calc-alkaline to shoshonitic S-type series on the base of geochemical data. Zircon Hf isotopic compositions of the Grobgneis metagranites show εHf(t) values of − 4.37 to − 0.6, with TDM2 model ages of 1.31–1.55 Ga, indicating that their protoliths were derived by the recycling of older continental crust. We suggest that the Permian granitic and gabbroic rocks are considered as rifted-related rocks in the Lower Austroalpine units and are contemporaneous with cover sediments.

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