Chemical composition and evolution of the garnets in the Astamal Fe-LREE distal skarn deposit, Qara-Dagh–Sabalan metallogenic belt, Lesser Caucasus, NW Iran

Baghban, Saeid; Hosseinzadeh, Mahnaz; Moayyed, Mohsen; Mokhtari, Mir Ali Asghar; Gregory, Daniel D.; Nia, Hosein Mahmoudi

doi:10.1016/j.oregeorev.2016.02.020

Cited by 17 publications

(11 citation statements)

References 18 publications

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“…The detection limit for most elements is below 0.01 wt%. Chemical formulae and endmember contents of the garnets were calculated following the methods of Deer, Howie, and Zussman (1966), and the ferrous and ferric iron contents were estimated based on ideal stoichiometric composition (Baghban et al, 2016).…”

Section: Methodsmentioning

confidence: 99%

“…However, Baghban et al (2016) reported coarse-grained, homogeneous garnets (5-30 mm across) with a narrow compositional range along the growth lines in a skarn deposit.…”

Section: Introductionmentioning

confidence: 99%

“…Garnet in skarn systems is usually characterized by concentric oscillatory zoning and continuous bell‐shaped chemical zoning (Dziggel, Wulff, Kolb, Meyer, & Lahaye, ; Zhai et al, ) which are controlled by either internal (e.g., surface adsorption, mineral diffusion, and growth rate) or external mechanisms (e.g., changes in P, T, X of fluids; Gaspar et al, ; Halden, ). However, Baghban et al () reported coarse‐grained, homogeneous garnets (5–30 mm across) with a narrow compositional range along the growth lines in a skarn deposit.…”

Section: Introductionmentioning

confidence: 99%

“…As a geochemical tracer, garnet in metamorphic and magmatic systems is usually characterized by HRE-enriched and LREE-depleted REE pattern (Bai & van Groos, 1999;Chen, Zhou, Zheng, Chen, & Hu, 2015;Dragovic, Samanta, Baxter, & Selverstone, 2012;Yang et al, 2013) and high Lu/Hf and Sm/Nd ratios (Hensen & Zhou, 1995;Smit, Scherer, & Mezger, 2013). Garnet is also a common mineral in skarntype deposits (Baghban et al, 2016;Meinert, 1992;Peng et al, 2015;Zhai et al, 2014) and is generally composed of andradite-grossular solid solution series, displaying variable REE patterns (Gaspar, Knaack, Meinert, & Moretti, 2008;Ismail et al, 2014;Zuo et al, 2015). Garnet in skarn-type deposits is generally precipitated during the prograde stage and is typically spatially related to magmatic intrusions Somarin, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Garnet composition as an indicator of skarn formation: LA‐ICP‐MS and EPMA studies on oscillatory zoned garnets from the Haobugao skarn deposit, Inner Mongolia, China

et al. 2018

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Oscillatory zoned garnets are widespread in the Haobugao skarn‐type copper–lead–zinc–iron polymetallic deposit, and they can record garnet growing process in the early stages of metallogenesis. In order to investigate the skarn‐forming process and hydrothermal fluid evolution of the Haobugao deposit, major, trace, and rare earth element (REE) contents of oscillatory zoned garnets were analysed by electron probe microscope analysis (EPMA) and laser‐ablation inductively‐coupled plasma mass spectrometry (LA‐ICP‐MS) techniques. Three distinct generations of garnets were identified: the first generation garnets (Grt I) are Fe‐rich, euhedral, fine‐ to coarse‐grained, isotropic, show characteristic concentric oscillatory zoning, and have light rare earth element (LREE)‐enriched and heavy rare earth element (HREE)‐depleted REE patterns, with strong positive Eu anomalies and low ΣREE concentrations. The second generation garnets (Grt II) are Al‐rich, anhedral to subhedral, anisotropic, with abundant oscillatory zoning alone the growth lines, and have LREE‐depleted and HREE‐enriched REE patterns, with negligible Eu anomalies and relatively higher ΣREE concentrations. The third generation garnets (Grt III) are anhedral, anisotropic and generally occurred at the rim of pre‐existing Grt I or beside fractures that cut through the pre‐existing Grt I crystals. All these three generations garnets show oscillatory zoning under an optical microscope and have different compositions from each other, but there's limited chemical zoning (such as bell‐shaped zoning of major elements) in each individual garnet crystal. The texture and composition characteristics of the garnets indicate that the Grt I is precipitated rapidly from high temperature and oxidized magmatic fluids by advective metasomatism, in a high water/rock ratio condition; the Grt II is precipitated from low temperature residual fluids that were in equilibrium with the host rock by diffusive metasomatism, in a low water/rock ratio condition; and the Grt III is formed by retrograde hydrothermal‐metasomatic alteration of pre‐existing garnets. The incorporation of REE into garnet is controlled by its crystal chemistry and fluid composition, dominated by the YAG (yttrium aluminium garnet) ‐type substitution mechanism ()X2+−1VIIIREE3++1VIIISi4+−1IVZ3++1IV.

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Section: Methodsmentioning

confidence: 99%

“…However, Baghban et al (2016) reported coarse-grained, homogeneous garnets (5-30 mm across) with a narrow compositional range along the growth lines in a skarn deposit.…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Garnet composition as an indicator of skarn formation: LA‐ICP‐MS and EPMA studies on oscillatory zoned garnets from the Haobugao skarn deposit, Inner Mongolia, China

et al. 2018

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“…There are many iron skarns in Iran. Some economically important well-known iron skarn deposits in Iran are as: Sangan [1] Gelali, Baba Ali, Khosro Abad and Shahrak [2] and Astamal [3] [4]. According to this, Saheb Fe-Cu skarn deposit is North-West Iran and coordinated 34˚46' to 35˚46' east longitude and 36˚16' to 36˚17' north latitude (part of Sanandaj-Sirjan zone is enclosed).…”

Section: Introductionmentioning

confidence: 99%

Mineralization, Mineralogy and Geochemistry of Saheb Fe-Cu Deposit of Saqqez (Kurdestan), NW Iran

Zandi¹,

Rad²,

Gourabjeripour³

et al. 2018

OJG

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The Saheb Fe-Cu skarn deposit is located in the Sanandaj-Sirjan metamorphic belt, SE Saqqez, western Iran and has been formed along the contact between the Oligo-Miocene aged Saheb granitoid and the Permian aged impure calcareous rocks and includes endoskarn and exoskarn. Exoskarn is widely developed and includes garnet and epidote skarn zones. The majority of mineralized zones are concentrated in garnet skarn. The relatively oxidizing mineralogical assemblage of the Saheb skarn includes garnet (andradite-grossular), pyroxene (diopside-hedenbergite), magnetite and hematite. Magnetite is the main and abundant ore mineral throughout the ore deposit. Based on field evidences and microscopic studies of skarn zone samples, two stages of prograde and retrograde alteration are distinguishable. According to the results of sample analysis of Saheb skarn intrusive body by XRF and ICP-MS techniques, the combination of this body is chiefly granite to granodiorite-diorite and belongs to the I-type granitoids, metaluminous and K-rich calc-alkaline series. The Saheb granitoid is related to the VAG (Volcanic Arc Granite) tectonic setting.

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Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

Wang,

Liu,

Lai

et al. 2023

Geological Journal

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The Lamasu deposit is the first large copper (Cu) deposit with ~0.6 Mt Cu reserve in the Chinese Western Tianshan Orogen (NW China). The Cu orebodies are mainly hosted in the exoskarn of the Proterozoic Kusongmuqieke Group. Now, the metallogenic mechanism of newly discovered skarn Cu orebodies (0.5 Mt Cu) remains poorly constrained. In this study, we conducted LA‐ICP‐MS U–Pb isotope dating, EPMA and LA‐ICP‐MS geochemical analyses on different generations of garnet from Lamasu to elucidate the magmatic hydrothermal evolution and its timing. Garnets from the Lamasu exoskarn can be divided into three types: reddish‐brown coarse‐grained Grt‐I, light brown fine‐grained Grt‐II and yellowish‐green heterogranular Grt‐III, with U–Pb age of 389.1 ± 2.0 Ma, 387.1 ± 1.8 Ma and 387.0 ± 2.3 Ma, respectively. These dates represent the oldest Cu mineralization age in the Chinese Western Tianshan, coeval with the Middle Devonian subduction of the North Tianshan oceanic plate. Grt‐I to Grt‐III particles are mainly andradite with minor grossularite, and they have different REE compositions. The Grt‐I has total REE contents (∑REE) of 101.47 to 262.87 ppm, with steeply right‐inclining REE distribution patterns (LREE/HREE of 3.81 to 68.50) and positive Eu anomaly. The Grt‐II core has ∑REE of 163.49–249.52 ppm, LREE/HREE of 2.00–4.71, and negative Eu anomaly. The Grt‐II rim has ∑REE of 46.34–99.99 ppm, with LREE/HREE of 18.06–177.23, and positive Eu anomaly. The ∑REE of Grt‐III range from 31.71 to 219.02 ppm, with flat REE distribution pattern and positive Eu anomaly, and the LREE/HREE ranges from 2.16 to 9.07. These garnets have similar trace element compositions, featured by LILE‐depletions (e.g., Rb, Ba and Sr) and HFSE enrichments (e.g., Th, U, Nb and Ce). Micro‐texture and geochemical composition of garnets indicate that the Lamasu magmatic hydrothermal system could have changed from an open to a closed environment, and from infiltration metasomatism to diffusive metasomatism, which formed Grt‐I, Grt‐II and Grt‐III successively. These garnets generally formed in a relatively oxidized fluid environment, which inhibited early sulphide precipitation and favoured for Cu enrichment during the ore fluid evolution.

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Chemical composition and evolution of the garnets in the Astamal Fe-LREE distal skarn deposit, Qara-Dagh–Sabalan metallogenic belt, Lesser Caucasus, NW Iran

Cited by 17 publications

References 18 publications

Garnet composition as an indicator of skarn formation: LA‐ICP‐MS and EPMA studies on oscillatory zoned garnets from the Haobugao skarn deposit, Inner Mongolia, China

Garnet composition as an indicator of skarn formation: LA‐ICP‐MS and EPMA studies on oscillatory zoned garnets from the Haobugao skarn deposit, Inner Mongolia, China

Mineralization, Mineralogy and Geochemistry of Saheb Fe-Cu Deposit of Saqqez (Kurdestan), NW Iran

Genesis of the Lamasu large skarn Cu deposit, northern Xinjiang: Constraints from garnet U–Pb dating, micro‐textural and geochemical analyses

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