Styles of Fe–Ti–V ore deposits in the Neoproterozoic layered mafic-ultramafic intrusions, south Eastern Desert of Egypt: Evidence for fractional crystallization of V-rich melts

Khedr, Mohamed Zaki; Takazawa, Eiichi; Arai, Shoji; Stern, Robert J.; Morishita, Tomoaki; El-Awady, Amr

doi:10.1016/j.jafrearsci.2022.104620

Cited by 15 publications

(9 citation statements)

References 81 publications

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“…GAN magnetites have a low TiO 2 concentration (0.24 to 6.05 wt%) and a limited range of ulvöspinel values 26 (0.68–18.92 mol%) (Supplement 6 ). FeO t content varies from 66.10 to 91.54wt% due to replacement by Ti, V, Mn, and Mg, and it has low amounts of MnO (0.16–0.39 wt%), and Al 2 O 3 (0.06–6.23 wt%) similar to magmatic magnetite of the Abu Ghalaga intrusion SED, Egypt 14 .…”

Section: Resultsmentioning

confidence: 99%

“…Fe–Ti ores can be generated from two contrasting models such as a result of Fe–Ti oxide crystal sorting from magmas or accumulating of oxide melts that resulted from immiscible separation in magma 12 . In Egypt, mafic layered intrusions are frequently associated with or hosted Fe–Ti oxides 13 , 14 . These intrusions are scarcely exposed in the Southern Eastern Desert (SED) of Egypt, which belongs to the Arabian Nubian Shield (ANS).…”

Section: Introductionmentioning

confidence: 99%

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Integrating mineralogy, geochemistry and aeromagnetic data for detecting Fe–Ti ore deposits bearing layered mafic intrusion, Akab El-Negum, Eastern Desert, Egypt

Kharbish

Eldosouky²,

Amer³

2022

Sci Rep

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This study delineated the Fe–Ti oxide deposit concurrencies on the layered mafic intrusion in Gabal Akab El-Negum (GAN), South Eastern Desert, Egypt, using aeromagnetic mapping and chemical analysis of the hosted mafic rocks and mineralogical studies. Aeromagnetic data was improved using the enhanced horizontal gradient amplitudeto detect the primary structures (edges/contacts/faults) that control the distribution of Fe–Ti ore deposit. GAN layered gabbros are differentiated into troctolite, olivine–, pyroxene–, and hornblende–gabbros. These mafic rocks primarily comprise plagioclase, olivine, pyroxene, and hornblende with Fe–Ti ores (magnetite and ilmenite). The significant variation in Mg# of clinopyroxene between 0.70 and 0.82 indicates the importance of fractional crystallization in developing layered mafic intrusion. Clinopyroxene and plagioclase thermometry yielded low temperatures similar to the fractionated primary basaltic magma. The pairs of magnetite–ilmenite minerals in gabbros provide equilibrium temperatures of 539.44–815.56, and high fO2, reflecting various cooling and subsolidus reequilibration phases of minerals. The enrichment of GAN gabbros in light rare–earth elements relative to heavy rare–earth elements indicates the interaction between the Fe–Ti rich mantle and the fractionated tholeiitic magmas in the back-arc setting, generating Fe–Ti oxide ores.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Integrating mineralogy, geochemistry and aeromagnetic data for detecting Fe–Ti ore deposits bearing layered mafic intrusion, Akab El-Negum, Eastern Desert, Egypt

Kharbish

Eldosouky²,

Amer³

2022

Sci Rep

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“…Titanomagnetite deposits form during the differentiation of a silicate melt as a result of the periodic oxidation of the magma. The reaction between iron-rich olivine (fayalite) crystallizing from magma and the oxygen dissolved in melt is as follows [73][74][75][76][77]:…”

Section: Discussionmentioning

confidence: 99%

Impact of DEMs for Improvement Sentinel 2 Lithological Mapping Utilizing Support Vector Machine: A Case Study of Mineralized Fe-Ti-Rich Gabbroic Rocks from the South Eastern Desert of Egypt

et al. 2023

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Fused remote sensing datasets have greatly contributed to enhancing lithological targets and providing significant information for mineral exploration. For instance, multispectral datasets can discriminate rock units through their unique spectral signatures. Digital Elevation Models (DEMs) could be an effective tool boosting lithological discrimination based mainly on their topographic variations. Consequently, the current study applied the power of the support vector machine (SVM) algorithm and the integrated Phased Array L-type band Synthetic Aperture Radar (PALSAR) DEM and multispectral Sentinel 2 data to: 1—Create an updated lithological map of a poorly mapped arid terrain (Khashir-Ras El-Kharit district, Eastern Desert of Egypt), and 2—Compare and assess the distribution of ferrogabbros with the aim of improving the localization of these rock bodies and investigating their mineral content. Our results enhanced the lithological mapping and revealed a better generalization of mineralized ferrogabbros when the input was a fused DEM with Sentinel 2 compared to the salt and pepper effect observed when adopting the Sentinel 2 solely as the input data. Additionally, the current research strongly recommends detailed exploration programs for Fe-Ti oxide ores within the gabbroic rocks delineated through the resultant thematic map. The ferrogabbros were subjected to a comprehensive analysis involving whole rock geochemistry, XRD, EDX, and light-reflecting investigations, which revealed the existence of magnetite, titanomagnetite, and hematite. The titanomagnetite crystals display subhedral morphology and exhibit fine- to medium-grained surfaces with irregular shapes. X-ray diffraction (XRD) analysis revealed the presence of magnetite and hematite in the concentrated Fe-Ti oxides. Additionally, the whole rock geochemistry highlighted the origin of the ferrogabbros and their proposed tectonic setting as an alkaline to calc-alkaline magma type that developed in a continental arc setting.

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“…Such an increase resulted from the magma evolution under an H2O-unsaturated condition. The H2O content of the magma will gradually increase with the magmatic evolution until it becomes H2Osaturated and the magmatic fluid begins to dissolve from the melt, according to H2O solubility in melts (Figure 8b) [21,22,88,89]. The ƒO2 (ΔFMQ) decreased from ≥ + 3.0 to ~+2.0 during this process.…”

Section: The Magma H 2 O Contents and ƒO 2 Conditions During Upper Cr...mentioning

confidence: 99%

“…Minerals in cogenetic ore-bearing intrusions are sensitive to various factors of the magma processes, such as ƒO 2 , temperature and melt composition. As a result, they serve as a valuable tool for estimating the crystallization conditions and compositions of their equilibrium melt phase, e.g., [14][15][16][17][18][19][20][21][22]. The utilization of multiple minerals is more effective in characterizing the comprehensive magmatic process, as different minerals undergo crystallization at different stages.…”

Section: Introductionmentioning

confidence: 99%

In Situ Mineralogical Constraints on Magmatic Process for Porphyry Deposits in the Upper Crust: A Case from Tongchang–Chang’anchong Porphyry Deposits, SW China

Wang

Zheng

et al. 2023

Minerals

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The magmatic process within upper crust encompasses various contents such as the transition between magmatic and hydrothermal systems and changes in oxygen fugacity (ƒO2), which ultimately play key roles in the formation of porphyry Cu deposits (PCDs). However, tracing these magmatic processes, especially in porphyry systems, is not an easy task. This study reported the detailed process of magmatic fluid exsolution and systematical variation of magmatic ƒO2 within the upper crust of a Tongchang–Chang’anchong porphyry Cu deposit, based on detailed investigations of mineral crystallization sequences and compositional features of the minerals in the fertile porphyries. Results indicate that the fertile porphyries show a high initial ƒO2, with ΔFMQ ≥ +3.0 (ΔFMQ is the deviation of logƒO2 from the fayalite–magnetite–quartz (FMQ) buffer). The magmatic ƒO2 (ΔFMQ) continued to decrease to ~+2 until fluid exsolution occurred at ~790 °C due to wall-rock contamination. The magmatic fluid exsolution process caused a temporary increase in the ƒO2 (to ΔFMQ = ~+3.4). The high magmatic ƒO2 during this process (790–750 °C) resulted in a higher content of ore-forming materials in the exsolved magmatic fluid. When the temperature dropped below 750 °C, the magmatic ƒO2 began to continuously decrease and eventually reached ΔFMQ = ~+0.6. The lower magmatic ƒO2 hindered the further migration of ore-forming materials through the exsolved fluid during this process (< 750 °C). Results of this study indicate that the initial magma during the upper crustal magmatic process of PCDs generally has a high ƒO2, and the contamination of reduced components can significantly decrease the magmatic ƒO2. The early magmatic fluid exsolution process can maintain a high magmatic ƒO2 condition, thereby efficiently extracting ore-forming minerals and producing ore-forming fluids, which is the key to the formation of PCDs. The latter continuous decrease in magmatic ƒO2 during the fluid exsolution process may be the reason preventing the Tongchang–Chang’anchong porphyry Cu deposit to form a giant PCD.

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Styles of Fe–Ti–V ore deposits in the Neoproterozoic layered mafic-ultramafic intrusions, south Eastern Desert of Egypt: Evidence for fractional crystallization of V-rich melts

Cited by 15 publications

References 81 publications

Integrating mineralogy, geochemistry and aeromagnetic data for detecting Fe–Ti ore deposits bearing layered mafic intrusion, Akab El-Negum, Eastern Desert, Egypt

Integrating mineralogy, geochemistry and aeromagnetic data for detecting Fe–Ti ore deposits bearing layered mafic intrusion, Akab El-Negum, Eastern Desert, Egypt

Impact of DEMs for Improvement Sentinel 2 Lithological Mapping Utilizing Support Vector Machine: A Case Study of Mineralized Fe-Ti-Rich Gabbroic Rocks from the South Eastern Desert of Egypt

In Situ Mineralogical Constraints on Magmatic Process for Porphyry Deposits in the Upper Crust: A Case from Tongchang–Chang’anchong Porphyry Deposits, SW China

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