scholarly journals Genetic relationships between skarn ore deposits and magmatic activity in the Ahar region, Western Alborz, NW Iran

2014 ◽  
Vol 65 (3) ◽  
pp. 209-227 ◽  
Author(s):  
Habib Mollai ◽  
Georgia Pe-Piper ◽  
Rahim Dabiri
Keyword(s):  
Carbonate Rocks ◽  
Genetic Relationships ◽  
Ore Deposits ◽  
Igneous Rocks ◽  
Volatile Components ◽  
Magmatic Activity ◽  
Nw Iran ◽  
Tectonic Processes ◽  
Skarn Deposits ◽  
Alborz Range

Abstract Paleocene to Oligocene tectonic processes in northwest Iran resulted in extensive I-type calc-alkaline and alkaline magmatic activity in the Ahar region. Numerous skarn deposits formed in the contact between Upper Cretaceous impure carbonate rocks and Oligocene-Miocene plutonic rocks. This study presents new field observations of skarns in the western Alborz range and is based on geochemistry of igneous rocks, mineralogy of the important skarn deposits, and electron microprobe analyses of skarn minerals. These data are used to interpret the metasomatism during sequential skarn formation and the geotectonic setting of the skarn ore deposit related igneous rocks. The skarns were classified into exoskarn, endoskarn and ore skarn. Andraditic garnet is the main skarn mineral; the pyroxene belongs to the diopside-hedenbergite series. The skarnification started with pluton emplacement and metamorphism of carbonate rocks followed by prograde metasomatism and the formation of anhydrous minerals like garnet and pyroxene. The next stage resulted in retro gradation of anhydrous minerals along with the formation of oxide minerals (magnetite and hematite) followed by the formation of hydrosilicate minerals like epidote, actinolite, chlorite, quartz, sericite and sulfide mineralization. In addition to Fe, Si and Mg, substantial amounts of Cu, along with volatile components such as H2S and CO2 were added to the skarn system. Skarn mineralogy and geochemistry of the igneous rocks indicate an island arc or subduction-related origin of the Fe-Cu skarn deposit.

Composition of minerals from the skarn deposits Väster Silvberg (Sweden) and Tumurtijn-ovoo (Mongolia): Indications of different element supply in submarine hydrothermal-sedimentary ore genesis

2019 ◽  
Vol 196 (2) ◽  
pp. 135-148
Author(s):  
Wolfram Gottesmann ◽  
Bärbel Gottesmann
Keyword(s):  
Carbonate Rocks ◽  
Iron Ore ◽  
Ore Deposits ◽  
Chemical Compositions ◽  
Ore Formation ◽  
Volcanic Material ◽  
Iron Ore Deposits ◽  
Ore Minerals ◽  
Skarn Deposits ◽  
Composition Of Minerals

We compare chemical compositions of the main minerals from two submarine exhalative sulfide-bearing manganiferous iron-ore deposits, i.e.Väster Silvberg in Sweden (VS) and Tumurtijn-ovoo in Mongolia (TO). At VS, much Al is present in garnet (Fe-spessartine) and biotite, whereas at TO the ore-associated garnets are Al-poor (andradite) and minerals not associated with ore minerals are Al-rich (grossular, vesuvianite). The low-Al of andradite at TO agrees with the low-Al of volcanic ore-forming solutions from the modern oceans. The Al-rich minerals at both TO and VS indicate the assimilation of Al-rich volcanic material in both deposits. The elements Ca and Mg show opposite distributions: at VS much Mg is incorporated in kutnahorite, knebelite, biotite, and Mn-actinolite, Mg-rich minerals are absent at TO; in contrast, the garnets at TO contain more Ca than the garnets at VS. We explain these differences by the different carbonate minerals constituting the accompanying carbonate rocks at the two deposits, namely calcite and dolomite at VS, and only calcite at TO. These minerals primarily resulted from evaporation of seawater. Also during times, when they did not form massive carbonate rocks, they settled to the seafloor in minor amounts. There, they were partially combined with volcaniclastic Al-rich input. When the ore solutions spread on the seafloor and percolated through the bottomset they mixed with the seafloor mud producing ore-bearing sediments as precursors of Al-rich, Mg-rich skarn ores at VS and Al-poor, Mg-poor, Ca-rich skarn ores at TO. As a result, three sources supplied elements for the skarn-ore formation at the investigated deposits: volcanic ore solutions, Al-rich volcanic material and evaporitic carbonates of different composition.

Potassium–Argon Ages of Igneous Rocks from the Area near Hedley, Southern British Columbia

1972 ◽  
Vol 9 (12) ◽  
pp. 1632-1639 ◽  
Author(s):  
J. C. Roddick ◽  
E. Farrar ◽  
E. L. Procyshyn
Keyword(s):  
British Columbia ◽  
Igneous Rocks ◽  
Magmatic Activity ◽  
Radiometric Ages

K–Ar ages are reported for 19 samples collected from the Hedley, Okanagan, and Similkameen Complexes located in the vicinity of Hedley, British Columbia. Although the zoned nature of amphiboles collected from the Hedley Complex makes interpretation of their radiometric ages difficult, it is suggested that the Hedley Complex was intruded at least 165 m.y. ago and was a part of the same magmatic activity that gave rise to both the Okanagan and Similkameen batholithic complexes. These latter complexes yield ages ranging from 141 m.y. to 184 m.y.

Estimation of copper ore deposit parameters – case study of Rudna Mine mining block R-1 (SW part of Poland) using geostatistics

2021 ◽  
Author(s):  
Barbara Namysłowska-Wilczyńska
Keyword(s):  
Carbonate Rocks ◽  
Mineral Resources ◽  
Ore Deposits ◽  
Upper Permian ◽  
Spatial Analyses ◽  
Copper Ore ◽  
Cu Content ◽  
Copper Mineralization ◽  
Rock Formations ◽  
Mineralized Zone

<p>This geostatistical study investigates the variation in the basic geological parameters of the lithologically varied deposit in mining block R-1 in the west (W) part of the Rudna Mine (the region Lubin – Sieroszowice, SW part of Poland).</p><p>Data obtained from the sampling (sample size N = 708) of excavations in block R-1 were the input for the spatial analyses. The data are the results of chemical analyses of the Cu content in the (recoverable) deposit series, carried out on channel samples and drilled core samples, taken systematically at every 15-20 m in the headings.</p><p>The deposit profile comprises various rock formations, such as: mineralized Weissliegend sandstones, intensively mineralized upper Permian dolomitic-loamy and loamy copper-bearing schists and carbonate rocks: loamy dolomite, striped dolomite and limy dolomite, of various thickness. No schists formed in some parts of block R-1, which are referred to as the schistless area. The deposit series here is considerably less mineralized (comparing with other mining blocks) even though the mineralization thickness of the sandstone and carbonate rocks reaches as much as 20 m.</p><p>The variation in the Cu content and thickness of the recoverable deposit and the estimated averages Z* of the above parameters were modelled using the variogram function and the ordinary (block) kriging technique. The efficiency of the estimations was characterized.</p><p>As part of the further spatial analyses the Z<sub>s</sub> values of the analysed deposit parameters were simulated using the conditional turning bands simulation. Confidence intervals for the values of averages based on the estimated averages Z* and averages <strong> </strong>based on the simulated values (realizations) Z<sub>s</sub>, showing the uncertainty of the estimations and simulations, were calculated.</p><p>The results of the analyses clearly indicate the shifting of the mineralized zone (the mineralizing solutions), sometimes into the sandstones while spreading throughout the floor of calcareous-dolomitic formations and sometimes into the carbonate rocks, partly entering the roof layers of sandstones. It can be concluded that the process of deposit formation and copper mineralization variation had a multiphase character and the lateral and vertical relocation of the valuable metal ores could play a significant role.</p><p>The combination of various geostatistical techniques - estimation and simulation - will allow for more effective management of natural resources of mineral resources, including copper ore deposits.</p>

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 II.—The Fundamental Problems of Petrogenesis, or the Origin of the Igneous Rocks

1911 ◽  
Vol 8 (6) ◽  
pp. 248-257 ◽  
Author(s):  
Franz Lœwinson-Lessing
Keyword(s):  
Physical Chemistry ◽  
Experimental Investigation ◽  
Fundamental Problem ◽  
Genetic Relationships ◽  
Point Of View ◽  
Igneous Rocks ◽  
Detailed Observation

The question of the origin of igneous rocks, their diversity and genetic relationships, represents that fundamental problem of petrography which has been for many years the object of inquiry for petrologists as well as for geologists and chemists. Whilst the amount and scope of detailed observation were growing, the methods of experimental investigation improved, and as the eruptive rocks came to be studied from the point of view of physical chemistry, so the petrogenetical horizon became larger and wider. Thus, on the basis of numerous minute and detailed observations were built broad generalizations that gave rise to new problems.

The final closure of the Vardar Ocean: paleomagnetic, AMS and structural results

2020 ◽  
Author(s):  
Emö Márton ◽  
Marinko Toljić ◽  
Vesna Lesić ◽  
Vesna Cvetkov
Keyword(s):  
Upper Cretaceous ◽  
National Development ◽  
Upper Jurassic ◽  
Igneous Rocks ◽  
Magmatic Activity ◽  
Ministry Of Education ◽  
Bedding Planes ◽  
The Republic ◽  
Final Closure ◽  
Oceanic Domain

<p>The Vardar zone divides units of African affinity from units of the European margin. It is characterized by extensional opening of an oceanic domain during the Triassic and Jurassic followed by divergent simultaneous obduction of the oceanic litoshphere over the continental units in the Upper Jurassic. However, a stripe of the oceanic domain persisted till the Cretaceous and Paleogene convergence. The remnants of the last closing part of the Vardar ocean are found in the Sava zone.</p><p>In this paper recently published and new paleomagnetic, AMS results in combination with structural observations will be presented from Upper Cretaceous sediments and Oligocene –Lower Miocene igneous rocks representing the areas bordering the Sava zone from the western and eastern sides, respectively and from the upper Cretaceous flysch deposited in the Sava zone.</p><p>In the areas W and E of the Sava zone, respectively, the primary remanences of the igneous rocks point to post-Oligocene CW rotation of about 30°. The sediments carry secondary magnetizations, imprinted during magmatic activity. Compared to the areas flanking it, the sediments of the Sava zone were intensively folded during the Upper Cretaceous and Paleogene and the paleomagnetic signals, which exhibit smeared distribution close to the present N, are of post-folding age. The AMS foliation and bedding planes are sub-parallel, thus the deformation must have been weak. Fold axes and AMS lineations are roughly N-S oriented, pointing to the deformational origin of the AMS lineations. These observations form the Sava zone will be discussed in the context of the post-Oligocene CW rotation of the flanking areas and the general NE-SW orientation of the compressional stress field outside of the zone.</p><p>Acknowledgement. This work was financially supported by the National Development and Innovation Office of Hungary, project K 128625 and by the Ministry of Education and Science of the Republic of Serbia, project 176015.</p>

The complexity of carbonate porosity distribution in the Upper Marrat Formation, Central Saudi Arabia

2020 ◽  
Author(s):  
Saleh Ahmed ◽  
Luis González ◽  
Johannes Jozef Gerardus Reijmer ◽  
Ammar ElHusseiny
Keyword(s):  
Saudi Arabia ◽  
Carbonate Rocks ◽  
Early Jurassic ◽  
Arabian Plate ◽  
Permeability Evolution ◽  
Depositional Processes ◽  
Bedding Planes ◽  
Tectonic Processes ◽  
Porosity And Permeability ◽  
The Impact

<p>In terms of reservoir properties distribution carbonate rocks are very heterogeneous. Moreover, the types of porosity in carbonate rocks is very diverse. In our study of the Upper Marrat Formation near Khasm-adh-Dhibi (central Saudi Arabia) we have documented the pore system complexity and are deconvolving the impact of various post-depositional processes on porosity and permeability evolution of the formation. The Upper Marrat Formation is exposed in the central part of the Arabian plate in a north-south elongated mountain belt. It forms the lower part of the thick Jurassic petroleum-rich succession. The sediments forming the Upper Marrat Formation were deposited during the Early Jurassic time, the Toarcian. The Upper Marrat Formation shows fossiliferous biomicrite to sparse biomicrite carbonates with an evaporite deposit at the top. It is bounded by clayey units at both the top and the base. In general, because of the muddy matrix of the Upper Marrat, sediments are very tight and show low permeability. During the last 175 My, the Upper Marrat has been subjected to a series of diagenetic and tectonic processes. The initial micro- and intergranular porosity was reduced due to early compaction and cementation, however, during later diagenesis and tectonism, porosity and permeability were enhanced. The dominant diagenetic porosity in the Upper Marrat sediments is vuggy porosity, followed by fabric selective intragranular porosity. Many of the horizons in the Upper Marrat are heavily burrowed and mostly filled with sand-sized grains showing a higher porosity than the matrix. Dolomite is limited to evaporite strata and contain extensive inter-crystalline porosity produced during dolomite formation. Tectonism has enhanced porosity through the development of micro- and macro-fractures.  The different sized and orientated micro-fractures are important while they enhance permeability by connecting different pore types. Then extensive macro-fracture network has a major impact on the reservoir qualities, both porosity and permeability. The heavily fractured formation shows numerous fractures sets with NNE to SSW and ENE to WNW orientations. Fractures are mostly vertical to near-vertical; they are nearly all open, and often crosscut beds, or end at bedding planes. These fractures are the most abundant porosity type and their connectivity results in a very high permeability. In conclusion, initial porosity and permeability, and subsequent diagenetic and tectonic processes reduced and enhanced the porosity and permeability development of the sediments of the Early Jurassic Upper Marrat Formation.</p>

Geochemical significance and Formation of Suçatı Pb-Zn Deposits – Eastern Taurides

2020 ◽  
Author(s):  
Ali Erdem Bakkalbasi ◽  
Hatice Nur Bayram ◽  
Mustafa Kumral ◽  
Ali Tugcan Unluer
Keyword(s):  
Carbonate Rocks ◽  
Field Studies ◽  
Hydrothermal Activity ◽  
Ore Deposits ◽  
Central Anatolia ◽  
Lower Permian ◽  
Ore Minerals ◽  
Geochemical Significance ◽  
Mvt Deposits ◽  
Marine Platform

<p><strong>Geochemical significance and Formation of  Suçatı Pb-Zn Deposits – Eastern Taurides</strong></p><p>Hatice Nur Bayram<sup>(1)*</sup>, Ali Erdem Bakkalbaşı <sup>(1)*</sup>, Mustafa Kumral<sup>(1)</sup>, Ali Tuğcan Ünlüer<sup>(1)</sup></p><p><sup>(1)</sup>Istanbul Technical University, Department of Geological Engineering, Istanbul/Turkey</p><p>(*E-mail: [email protected])</p><p> </p><p>The Middle Tauride Orogenic Belt is a productive enviroment in terms of Pb-Zn ore deposits, mostly associated with Permian aged dolomitized, shallow marine platform type carbonate rocks. There have been many studies on the origin of the ore deposits in the region, there are two important approaches that stand out for the formation of the ore deposits: the first theory is hydrothermal deposits with magmatic origin, and the other theory is Missisippi Valley-type (MVT) deposits related with the carbonate rocks commonly found in the region. Field studies at the Suçatı (Kayseri – Yahyalı, Central Anatolia, Turkey, East of Aladağlar extension of the Taurides) ore district in the Aladağ geologic unit indicate that the deposits in the region are associated with Paleo-Tethys limestones, fossiliferous limestones and dolomitic limestones. Mineralization is related to Lower Permian aged carbonate rocks include primary mineralization ore minerals as galena, sphalerite, smithsonite and goethite and as a product of hydrothermal activity, calcite mineral filled within fractures and cracks represents gangue minerals. As a result of geochemical analysis of the samples collected from the ore zones, PbO values range between 25.93% - 0.012%, ZnO values range between 51.01% - 0.042%, Fe<sub>2</sub>O<sub>3</sub> values range between 42.81% - 10.21%. In conclusion hydrothermal activities closely related with compressional and extentional tectonic regimes took place in multiphase mineralization.</p><p> </p><p><strong>Keywords:</strong> Pb-Zn Deposits, MVT, Taurides, Yahyalı</p>

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