“ORE MAGMA”. WHAT IS IT FROM THE STANDPOINT OF THE GRANITE ORE-MAGMATIC SYSTEM?

2021 ◽  
pp. 79-85
Author(s):  
V. L. Khomichev ◽  
Keyword(s):  
Basaltic Magma ◽  
Dark Side ◽  
Magmatic System ◽  
Ore Formation ◽  
Scientific Justification

The concept of “ore magma” remains an obscure hypothesis in ore formation. The article considers the process of natural overgrowth of trivial primary basaltic magma into an ore-bearing granite melting and further into the ore-forming “ore magma” as the concentration of volatile and ore components. The dark side of the problem lies in the fact that during the ore formation the “ore magma” liquates into contrasting phases and leaves practically no traces of itself (with rare exceptions). But the concept of the ore magma has received a logical scientific justification from the standpoint of ore-magmatic systems.

The fluid regime of ore formation in the Balei gold-bearing ore-magmatic system (eastern Transbaikalia, Russia)

2010 ◽  
Vol 51 (10) ◽  
pp. 1102-1109 ◽  
Author(s):  
A.M. Spiridonov ◽  
L.D. Zorina ◽  
S.P. Letunov ◽  
V.Yu. Prokof’ev
Keyword(s):  
Magmatic System ◽  
Fluid Regime ◽  
Ore Formation ◽  
Eastern Transbaikalia ◽  
Gold Bearing

VERTICAL ZONING OF THE COPPER-MOLYBDENUM FORMATION OF THE KUZNETSK ALATAU (KHAKASSIA)

2021 ◽  
pp. 3-11
Author(s):  
V. L. Khomichev ◽  
Keyword(s):  
General Model ◽  
Maximum Concentration ◽  
Deep Structure ◽  
Magmatic System ◽  
Ore Formation ◽  
First Approximation ◽  
Geological Features ◽  
Initial Content ◽  
Vertical Zoning

The previously identified zoning of the copper-molybdenum formation based on a comparison of geological features of the Sorskoye, Ipchulskoye and other deposits, is confirmed by a comparison of their deep structure and general model of the ore-magmatic system. As a result, it was possible to determine the distribution of ore matter and the degree of concentration of fluids and metals in the evolutionary chain in the first approximation: the initial granite melt-leucogranite residual chamber – ore-forming apophyse from the chamber. The maximum concentration in apophyse is 1000–2000 times higher than the initial content in an ordinary granite. This makes it possible to consider the fluidized apophyse melt as “ore magma” responsible for the ore formation.

Structure and composition of picritic gabbro-dolerites of the Оctyabrskoye deposit central part

2021 ◽  
pp. 39-47
Author(s):  
Maria Nesterenko
Keyword(s):  
Sulfide Minerals ◽  
Actual Process ◽  
Formation Model ◽  
Magmatic System ◽  
Deposit Formation ◽  
Ore Formation ◽  
Structural Patterns ◽  
Formation Conditions

Issues relating to the genesis and deposit formation conditions in the Norilsk region are still debatable. At present, ore formation model in an open magmatic system is most popular. To study the actual process, the structure and composition of sulfide minerals in the Oktyabrskoye deposit central part were examined in two boreholes, RT-30 and RT-107, that reveal orebodies C-3 and C-4, respectively. Particular attention was paid to the structural patterns of disseminated ores in picritic gabbro-dolerites horizon. It has been established that sulfide inclusions are missing in the upper part of the horizon and their size and quantity gradually increase in depth, so that these inclusions grade into sulfide streaks in the lower part of the horizon. This indicates gravitational sulfide deposition in a closed magmatic system.

Constraints on the Formation of Granite-Related Indium Deposits

2019 ◽  
Vol 114 (5) ◽  
pp. 993-1003 ◽  
Author(s):  
Austin M. Gion ◽  
Philip M. Piccoli ◽  
Philip A. Candela
Keyword(s):  
Hydrothermal System ◽  
Temporal Distribution ◽  
Magnesium Content ◽  
Sensu Stricto ◽  
Spatial And Temporal Distribution ◽  
Magmatic System ◽  
Ore Formation ◽  
Volatile Phase ◽  
Exploration Vectors ◽  
Modern Technologies

Abstract The use of indium in modern technologies has grown in recent decades, creating a growth in indium demand; thus, there is a need to constrain the spatial and temporal distribution of indium-bearing, granite-related deposits. Toward this end, a conceptual model and exploration vectors for the formation of granite-related indium deposits have been developed. The magmatic-hydrothermal system is modeled by consideration of crystal-melt and vapor-melt equilibria. The model calculates the efficiency of removal of indium from a melt into a volatile phase, which may serve as a component of an ore-forming fluid. The results of the model suggest that as the proportion of ferromagnesian minerals increases in the associated granites, the probability of indium ore formation decreases. Further, for a given modal proportion of ferromagnesian minerals, as the modal proportion of amphibole increases, the probability of indium ore formation decreases. Lastly, for a given modal proportion of biotite, as the magnesium content of the biotite increases (as would result from increasing oxidation of the magmatic system), the probability of indium ore formation decreases. Granites with the highest probability of being associated with indium ore formation will typically be part of A- or S-type igneous systems and will likely be highly fractionated (e.g., A-type topaz granites). I-type granites will generally have a lower potential of being associated with indium-bearing deposits. However, some I-type granites may be associated with indium-bearing deposits if the deposits contain granites (sensu stricto) or other related rocks (e.g., alaskites) that lack amphibole or other ferromagnesian phases.

The Aksug Porphyry Cu–Mo Ore-Magmatic System (Northeastern Tuva): Sources and Formation of Ore-Bearing Magma

2021 ◽  
Vol 62 (4) ◽  
pp. 445-459
Author(s):  
A.N. Berzina ◽  
A.P. Berzina ◽  
V.O. Gimon
Keyword(s):  
Trace Element ◽  
Subduction Zones ◽  
Large Scale ◽  
Basaltic Magma ◽  
Igneous Rocks ◽  
Magmatic System ◽  
Copper Mineralization ◽  
Geochemical Parameters ◽  
Depleted Mantle ◽  
Two Stages

Abstract ––Two stages are recognized in the evolution of the Aksug ore-magmatic system (OMS): (1) formation of the Aksug granitoid pluton and (2) emplacement of small ore-bearing intrusions. Intrusive bodies of the two stages are composed of rocks of the same type and bear copper mineralization: poor dispersed and large-scale veinlet-disseminated, respectively. The pluton and small intrusions are formed by gabbroid and granitoid rocks, with similar petrogeochemical characteristics of igneous rocks of the same type. The plutonic gabbroic association includes gabbro, gabbrodiorites, and pyroxene–amphibole diorites/quartz diorites. The small subvolcanic gabbroic intrusions are gabbrodiorite and diorite porphyrites. The trace element patterns of the gabbroids are similar to those of igneous rocks in subduction zones. The gabbroids are characterized by isotope parameters εNd(500) = +6.1 to +7.2 and (87Sr/86Sr)500 = 0.7022–0.7030 and model age TNd(DM) = 0.85–0.74 Ga. As follows from the geochemical parameters, the depleted mantle metasomatized by subduction fluids was the source of basaltic magma. The plutonic granitoid association includes tonalites, plagiogranites, and amphibole diorites/quartz diorites; the small subvolcanic granitoid intrusions are tonalite porphyry and quartz diorite porphyrites. The trace element patterns and Nd and Sr isotope compositions of the granitoids are much similar to those of the gabbroids. According to the geochemical parameters, tonalitic and plagiogranitic magmas formed through the melting of juvenile mafic crust, and dioritic magma resulted from the mixing of basaltic and tonalitic/plagiogranitic magmas. In the course of the OMS formation, metals and volatiles were introduced by basaltic and granitoid magmas from the metasomatized mantle and juvenile mafic crust. The compression setting during the pluton formation hampered the separation of ore-bearing fluids, which led to poor dispersed mineralization. The extension setting during the emplacement of small intrusions favored the intense separation of ore-bearing fluids. The interaction of magma and fluids of the small intrusions with rocks of the pluton was accompanied by the removal of metals from the latter and their involvement in the ore-forming process. This increased the ore potential of the magmatic system and favored the formation of rich mineralization at the final stage of its evolution.

Analysis of 2D and 3D defects associated with precipitation of Cu in silicon

1991 ◽  
Vol 49 ◽  
pp. 870-871
Author(s):  
P.M. Rice ◽  
MJ. Kim ◽  
R.W. Carpenter
Keyword(s):  
Colony Growth ◽  
Dark Field ◽  
Dark Side ◽  
Silicide Phase ◽  
Strain Fields ◽  
Near Surface ◽  
Unknown Composition ◽  
Secondary Precipitates ◽  
20 Nm ◽  
2D And 3D

Extrinsic gettering of Cu on near-surface dislocations in Si has been the topic of recent investigation. It was shown that the Cu precipitated hetergeneously on dislocations as Cu silicide along with voids, and also with a secondary planar precipitate of unknown composition. Here we report the results of investigations of the sense of the strain fields about the large (~100 nm) silicide precipitates, and further analysis of the small (~10-20 nm) planar precipitates.Numerous dark field images were analyzed in accordance with Ashby and Brown's criteria for determining the sense of the strain fields about precipitates. While the situation is complicated by the presence of dislocations and secondary precipitates, micrographs like those shown in Fig. 1(a) and 1(b) tend to show anomalously wide strain fields with the dark side on the side of negative g, indicating the strain fields about the silicide precipitates are vacancy in nature. This is in conflict with information reported on the η'' phase (the Cu silicide phase presumed to precipitate within the bulk) whose interstitial strain field is considered responsible for the interstitial Si atoms which cause the bounding dislocation to expand during star colony growth.

The Dark Side of Sweet Dreams

2006 ◽  
Vol 40 (12) ◽  
pp. 30
Author(s):  
BARBARA J. HOWARD
Keyword(s):  
Dark Side
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