scholarly journals Iron Isotopes Constrain the Metal Sources of Skarn Deposits: A Case Study from the Han-Xing Fe Deposit, China

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 951
Author(s):  
Bin Zhu ◽  
Hongfu Zhang ◽  
M. Santosh ◽  
Benxun Su ◽  
Pengfei Zhang ◽  
...  
Keyword(s):  
Major Elements ◽  
Ore Deposits ◽  
Magmatic Fluid ◽  
Skarn Deposit ◽  
Mass Balance Calculation ◽  
Positive Correlation ◽  
Fe Isotopes ◽  
Magmatic Fluids ◽  
Skarn Deposits

Magmatic fluids and leaching of rocks are regarded as the two sources of magmatic hydrothermal deposits, but their relative contributions to the metals in the deposits are still unclear. In this study, we combine major elements and Fe isotopes in two sets of rocks from the Han-Xing iron skarn deposit in China to constrain the iron sources. The positive correlation between the δ56Fe and ∑Fe2O3/TiO2 of altered diorites (∑Fe2O3 refers to the total iron) demonstrates that heavy Fe isotopes are preferentially leached from diorites during hydrothermal alteration. However, except for the pyrite, all the rocks and minerals formed in the skarn deposit are enriched in the light Fe isotope relative to the fresh/less altered diorites. Therefore, besides the leaching of rocks, the Fe isotopically light magmatic fluid also provides a large quantity of iron for this deposit. Based on the mass balance calculation, we conclude that iron from magmatic fluid is almost 2.6 times as large as that from the leaching of rocks. This is the first study to estimate the relative proportions of iron sources for Fe deposits by using Fe isotopes. Here, we propose that the high δ56Fe of magmatic intrusions combining the positive correlation between their ∑Fe2O3/TiO2 and δ56Fe could be taken as a fingerprint of exsolution or interaction with magmatic fluids, which contributes to the exploration of magmatic hydrothermal ore deposits.

scholarly journals Iron Isotope Fractionation during Skarn Cu-Fe Mineralization

Minerals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 444
Author(s):  
Song Xue ◽  
Yaoling Niu ◽  
Yanhong Chen ◽  
Yining Shi ◽  
Boyang Xia ◽  
...  
Keyword(s):  
Hydrothermal System ◽  
Isotope Fractionation ◽  
Inverse Correlation ◽  
Ore Deposits ◽  
Equilibrium Line ◽  
Skarn Deposit ◽  
Fe Isotopes ◽  
Pyrite Formation ◽  
Skarn Deposits ◽  
Pathway Effect

Fe isotopes have been applied to the petrogenesis of ore deposits. However, the behavior of iron isotopes in the mineralization of porphyry-skarn deposits is still poorly understood. In this study, we report the Fe isotopes of ore mineral separations (magnetite, pyrite, chalcopyrite and pyrrhotite) from two different skarn deposits, i.e., the Tonglvshan Cu-Fe skarn deposit developed in an oxidized hydrothermal system and the Anqing Cu skarn deposit developed in a reduced hydrothermal system. In both deposits, the Fe isotopes of calculated equilibrium fluids are lighter than those of the intrusions responsible for the skarn and porphyry mineralization, corroborating the “light-Fe fluid” hypothesis. Interestingly, chalcopyrite in the oxidized-Tonglvshan skarn deposit has lighter Fe than chalcopyrite in the reduced-Anqing skarn deposit, which is best understood as the result of the prior precipitation of magnetite (heavy Fe) from the ore fluid in the oxidized-Tonglvshan systems and the prior precipitation of pyrrhotite (light Fe) from the ore fluid in the reduced-Anqing system. The δ56Fe for pyrite shows an inverse correlation with δ56Fe of magnetite in the Tonglvshan. In both deposits, the Fe isotope fractionation between chalcopyrite and pyrite is offset from the equilibrium line at 350 °C and lies between the FeS-chalcopyrite equilibrium line and pyrite-chalcopyrite equilibrium line at 350 °C. These observations are consistent with the FeS pathway towards pyrite formation. That is, Fe isotopes fractionation during pyrite formation depends on a path from the initial FeS-fluid equilibrium towards the pyrite-fluid equilibrium due to the increasing extent of Fe isotopic exchange with fluids. This finding, together with the data from other deposits, allows us to propose that the pathway effect of pyrite formation in the Porphyry-skarn deposit mineralization is the dominant mechanism that controls Fe isotope characteristics.

U-Pb dating of skarn garnets from Bulgarian deposits

2020 ◽  
Author(s):  
Rossitsa Vassileva ◽  
Valentin Grozdev ◽  
Irena Peytcheva ◽  
Albrecht von Quadt ◽  
Maria Stifeeva
Keyword(s):  
Age Determination ◽  
Major Elements ◽  
Ore Deposits ◽  
Skarn Deposit ◽  
Garnet Composition ◽  
Icp Ms ◽  
Tectonic Zones ◽  
Skarn Deposits ◽  
Hydrothermal Ore Deposits

<p>Calcic garnets from grossular-andradite (grandite) series have proven their ability to record the conditions and timing of their formation processes. Typically these minerals occur in skarn systems, together with other calc-silicates (diopside, epidote) and commonly host economic Cu, Zn-Pb-Ag, Au, Sn, W or Mo mineralization. Based on the U-content in the garnet structure, we used in-situ LA-ICP-MS U-Pb geochronology to determine the age record in more than 15 skarn deposits from different tectonic zones in Bulgaria. The data is partly complemented with ID-TIMS dating. The mineralogical, geochemical and petrological characteristics of the materials were described additionally. Both contact and infiltration skarns were studied.</p><p>The obtained data revealed that the garnet composition in terms of major elements does not affect the precision of age determination. Both andradite and grossular members yield age data with very high accuracy. The dating results, however, depend on the geochemical signature of the garnets and especially on the U-content and U/Pb ratio. Our data shows that skarn samples from the vicinities of magmatic bodies or along contacts of causative pegmatite veins usually have increased U-incorporation from several to more than 70 ppm, as suggested by their proximal position to the source. The contact skarn garnets formed by intrusion of silicate melts (or pegmatites) onto carbonate-rich hosts mostly produce precise ages, which are in good agreement with the geochronological zircon data about the magmatism in the studied regions (e.g. Central Pirin, Teshevo, Plana, Gutsal, Rila-West Rhodope, Sv. Nikola etc. plutons). The infiltration skarns, though, generally reveal ages with low accuracy and significant errors, mainly due to U-content below 1 ppm. The reason for the low U-concentration and U/Pb ratio is either connected with a primary U-deficit and its depletion in the garnet-precipitating fluids with time and space but might be also related to garnet retrograde hydrothermal alteration.</p><p>The time span of the Bulgarian skarn garnets is closely connected with the causative magmatic bodies. The studied skarns reveal Paleogene (~30-42 Ma - Central Pirin and Teshevo plutons and pegmatites from Rila-West Rhodope batholith; Djurkovo, Murzian and Zvezdel Pb-Zn deposits; ~ 58 Ma - skarns from Western Rila Mts., ~ 68 Ma – Babyak Mo-Ag-Au-W-Bi-Cu-Pb-Zn deposit), Cretaceous (~ 76 Ma- Gutsal pluton, 81 Ma - scheelite bearing skarns from the Plana pluton, 86 Ma – Iglika skarn deposit) and Paleozoic (~ 303 Ma – Martinovo Fe-skarn deposit) ages. Given the occurrence of Ca-garnet in contact rocks and hydrothermal ore deposits, our results highlight the potential of grandite as a powerful U-Pb geochronometer for dating magmatism and skarn-related mineralizations.</p><p><em>Acknowledgements.</em> The study is partly supported by the DNTS 02/15 bilateral project between Bulgaria and the Russian Federation, financed by the Bulgarian National Science Fund.</p>

scholarly journals The Role of Magmatic and Hydrothermal Fluids in the Formation of the Sasa Pb-Zn-Ag Skarn Deposit, Republic of Macedonia

Geosciences ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 444
Author(s):  
Sabina Palinkaš ◽  
Zlatko Peltekovski ◽  
Goran Tasev ◽  
Todor Serafimovski ◽  
Danijela Šmajgl ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Water Activity ◽  
Base Metal ◽  
Ore Deposits ◽  
Molar Ratio ◽  
Low Oxygen ◽  
Skarn Deposit ◽  
Ground Waters ◽  
Mineral Assemblages ◽  
Skarn Deposits

The Sasa Pb-Zn-Ag deposit belongs to the group of distal base metal skarn deposits. The deposit is located within the Serbo-Macedonian massif, a metamorphosed crystalline terrain of Precambrian to Paleozoic age. The mineralization, hosted by Paleozoic marbles, shows a strong lithological control. It is spatially and temporally associated with the calc-alkaline to shoshonitic post-collisional magmatism that affected the Balkan Peninsula during the Oligocene–Miocene time period and resulted in the formation of numerous magmatic–hydrothermal ore deposits. The mineralization at the Sasa Pb-Zn-Ag deposit shows many distinctive features typical for base metal skarn deposits including: (1) a carbonate lithology as the main immediate host of the mineralization; (2) a close spatial relation between the mineralization and magmatic bodies of an intermediate composition; (3) a presence of the prograde anhydrous Ca-Fe-Mg-Mn-silicate and the retrograde hydrous Ca-Fe-Mg-Mn ± Al-silicate mineral assemblages; (4) a deposition of base metal sulfides, predominately galena and sphalerite, during the hydrothermal stage; and (5) a post-ore stage characterized by the deposition of a large quantity of carbonates. The relatively simple, pyroxene-dominated, prograde mineralization at the Sasa Pb-Zn-Ag skarn deposit represents a product of the infiltration-driven metasomatism which resulted from an interaction of magmatic fluids with the host marble. The prograde stage occurred under conditions of a low water activity, low oxygen, sulfur and CO2 fugacities and a high K+/H+ molar ratio. The minimum pressure–temperature (P–T) conditions were estimated at 30 MPa and 405 °C. Mineralizing fluids were moderately saline and low density Ca-Na-chloride bearing aqueous solutions. The transition from the prograde to the retrograde stage was triggered by cooling of the system below 400 °C and the resulting ductile-to-brittle transition. The brittle conditions promoted reactivation of old (pre-Tertiary) faults and allowed progressive infiltration of ground waters and therefore increased the water activity and oxygen fugacity. At the same time, the lithostatic to hydrostatic transition decreased the pressure and enabled a more efficient degassing of magmatic volatiles. The progressive contribution of magmatic CO2 has been recognized from the retrograde mineral paragenesis as well as from the isotopic composition of associated carbonates. The retrograde mineral assemblages, represented by amphiboles, epidote, chlorites, magnetite, pyrrhotite, quartz and carbonates, reflect conditions of high water activity, high oxygen and CO2 fugacities, a gradual increase in the sulfur fugacity and a low K+/H+ molar ratio. Infiltration fluids carried MgCl2 and had a slightly higher salinity compared to the prograde fluids. The maximum formation conditions for the retrograde stage are set at 375 °C and 200 MPa. The deposition of ore minerals, predominantly galena and sphalerite, occurred during the hydrothermal phase under a diminishing influence of magmatic CO2. The mixing of ore-bearing, Mg-Na-chloride or Fe2+-chloride, aqueous solutions with cold and diluted ground waters is the most plausible reason for the destabilization of metal–chloride complexes. However, neutralization of relatively acidic ore-bearing fluids during the interaction with the host lithology could have significantly contributed to the deposition. The post-ore, carbonate-dominated mineralization was deposited from diluted Ca-Na-Cl-bearing fluids of a near-neutral pH composition. The corresponding depositional temperature is estimated at below 300 °C.

Spectral characteristics of minerals associated with skarn deposits: a case study of Weondong skarn deposit, South Korea

2015 ◽  
Vol 20 (2) ◽  
pp. 167-182 ◽  
Author(s):  
Yongsik Jeong ◽  
Jaehyung Yu ◽  
Sang-Mo Koh ◽  
Chul-Ho Heo ◽  
Jeonga Lee
Keyword(s):  
South Korea ◽  
Spectral Characteristics ◽  
Skarn Deposit ◽  
Skarn Deposits

Laser ablation ICP-MS titanite U–Th–Pb dating of hydrothermal ore deposits: A case study of the Tonglushan Cu–Fe–Au skarn deposit, SE Hubei Province, China

2010 ◽  
Vol 270 (1-4) ◽  
pp. 56-67 ◽  
Author(s):  
Jian-Wei Li ◽  
Xiao-Dong Deng ◽  
Mei-Fu Zhou ◽  
Yong-Sheng Liu ◽  
Xin-Fu Zhao ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Hubei Province ◽  
Ore Deposits ◽  
Skarn Deposit ◽  
Icp Ms ◽  
Hydrothermal Ore Deposits

scholarly journals Mafic magma as metal source for Sb-W-Hg mineralisation? A case study of the early Carboniferous mafic magmatic event from the French Armorican Variscan belt

2021 ◽  
Author(s):  
Anthony Pochon ◽  
Giada Iacono-Marziano ◽  
Saskia Erdmann ◽  
Eric Gloaguen ◽  
Johann Tuduri
Keyword(s):  
Fluid Inclusions ◽  
Mafic Magma ◽  
Early Carboniferous ◽  
Magmatic Fluid ◽  
Variscan Belt ◽  
Metal Enrichment ◽  
Metal Source ◽  
Mafic Magmatism ◽  
Magmatic Fluids

<p>A possible genetic link between Sb-W-Hg mineralisation (vein-type and stratabound) and mafic magmatism has been proposed for the Variscan belt during the early Carboniferous, but this hypothesis remains to be rigorously assessed. The metal enrichment of the fluids producing Variscan Sb-W-Hg deposits may be ascribed to (i) crystallization of metal-rich primary mafic magma, and/or (ii) exsolution of metal-rich magmatic fluids and their local concentration, and/or (iii) an efficient hydrothermal leaching of surroundings sedimentary rocks by fluid release due to contact metamorphism. The aim of this project is thus to estimate the contribution of mafic magmas as the metal source of Sb-W-Hg deposits. Our case study focuses on the Saint-Jean-du-Doigt gabbro from the Variscan Armorican belt, Brittany, France. We have characterized the Sb-, W-, and Hg-carrier minerals (<em>e.g. </em>Fe-Ti oxides) and volatile-bearing minerals (<em>e.g.</em> apatite) to quantify the metal content and volatile inventory during purely magmatic and magmatic-hydrothermal processes. Abundant primary amphibole and biotite, and the presence of pegmatoids indicate that the melt was likely to be enriched in volatile. An alteration gradient is observed from the base of the intrusion towards its roof. Moreover, high temperature replacement mineral reactions (<em>e.g. </em>saussuritization) mainly occur in the upper part of the intrusion, suggesting that magmatic fluids were accumulated toward the top of the intrusion. Cathodoluminescence and apatite compositions are taken to record the magmatic-hydrothermal transition and hydrothermal alteration. Apatite ranges in composition between fluorapatite and fluor-hydroxyapatite, but the latter is largely more frequent. A high volatile content of the silicate melt is suggested by the high proportion of negative-shaped fluid inclusions into ilmenite (up to 15 % crystal volume), which hint at a primary magmatic origin. SEM, EPMA and LA-ICP-MS investigations show that magmatic fluid inclusions contain significant amounts of Sb and W. Our results highlight that metals (<em>i.e.</em> Sb, W) were partly partitioned into the fluid phase during magma crystallization and degassing. In addition, trace element content of ilmenite also records metal enrichment from the base to the intrusion roof, probably due to magma degassing and deuteric/metasomatic processes. We therefore propose that mafic magmatism is a potential metal source of the early Carboniferous Sb-W-Hg mineralization event and should be considered as possible sources for other Sb-W-Hg province worldwide. This work was funded by the ANR (ANR-19-MIN2-0002) and author’s institutions in the framework of the ERA-MIN2 AUREOLE project (https://aureole.brgm.fr).</p>

New potential pyrrhotite and pentlandite reference materials for sulfur and iron isotope microanalysis

2021 ◽  
Author(s):  
Lei Chen ◽  
Yu Liu ◽  
Yang Li ◽  
Qiuli Li ◽  
Xian-Hua Li
Keyword(s):  
Reference Materials ◽  
Sulfide Minerals ◽  
Ore Deposits ◽  
Iron Isotope ◽  
S Isotopes ◽  
Fe Isotopes

Pyrrhotite and pentlandite are the most common Fe sulfide minerals in magmatic ore deposits and meteorites. Multiple S isotopes pairing with Fe isotopes of bulk Fe sulfides have proven to...

scholarly journals The Correlation between Toll Road Development and the Improvement of Local Economy (Case Study: The Soroja Toll Road)

2020 ◽  
Vol 3 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Lisna Rahayu ◽  
Desiree Marlyn Kipuw ◽  
Keyword(s):  
Gross Domestic Product ◽  
Small And Medium Enterprises ◽  
Local Economy ◽  
Positive Correlation ◽  
Toll Road ◽  
Road Development ◽  
Surrounding Areas ◽  
Medium Enterprises ◽  
Wheeled Vehicles

Most studies assume that road development will improve the economy in the region, as reflected by an increase in Gross Domestic Product (GDP). However, GDP is macro in nature and tends to be biased if we ask who benefits from its increase. To identify whether road development has a positive correlation with the improvement of local economy, hence this study was conducted in a micro context by taking the development of the Soroja Toll Road in Indonesia as a case study. With a length of 10.57 km, connecting Bandung Regency and Bandung City, the newly constructed Soroja Toll Road has a strategic function in supporting activities in the Bandung Metropolitan Area (BMA) and is predicted giving implication on increasing Small and Medium Enterprises (SMEs) profit surrounding its corridor. However, a toll road cannot entirely be seen as a public goods, because not all people have access to this type of infrastructure. Only the users of four-wheeled vehicles and those who can afford to pay the toll charge can access the toll road. This study was aimed at identifying the correlation between the developments of the Soroja Toll Road with the improvement of local economy (SMEs) in its surrounding areas. Based on the analysis result, this study indicates that the presence of the Soroja Toll Road had a bigger positive correlation with the increased profit of medium-sized industries than small-sized industries due to their ability to capture a broader market.

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