Newly identified Middle&amp;ndash;Late Permian mafic&amp;ndash;ultramafic intrusions in the southeastern margin of the Central Asian Orogenic Belt: Petrogenesis and its implications

Hao, Libo; Wei, Qiaoqiao; Zhao, Yuyan; Lu, Jilong; Zhao, Xinyun

doi:10.2343/geochemj.2.0339

Cited by 3 publications

(4 citation statements)

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“…The Re-Os isotopic compositions indicated that the magmatic source was contaminated by a small amount of crustal material, and subsequent crystal fractionation resulted in the Cu-Ni F I G U R E 1 1 Models of the tectonic evolution of subduction, thickening of lower crust, and delamination in the Palaeo-Asian oceanic tectonic regime during the middle-Late Triassic. NCC: North China Craton; XMOB: Xing'an-Mongolia Orogenic Belt mineralization (Hao et al, 2015;Wu et al, 2004). In the present study, the later period of Middle Triassic quartz diorites could be derived from the partial melting of a thickened lower crust accompanied by the final closure of the PAO.…”

Section: Implications For the Late Triassic Large-scale Ni-cu Mineral...mentioning

confidence: 57%

“…Nevertheless, it is widely recognized that the primary mafic magma was a lithospheric mantle‐derived basalt resulting from the upwelling of asthenosphere due to lithospheric delamination during post‐orogenic processes. The Re–Os isotopic compositions indicated that the magmatic source was contaminated by a small amount of crustal material, and subsequent crystal fractionation resulted in the Cu–Ni mineralization (Hao et al, 2015; Wu et al, 2004). In the present study, the later period of Middle Triassic quartz diorites could be derived from the partial melting of a thickened lower crust accompanied by the final closure of the PAO.…”

Section: Discussionmentioning

confidence: 99%

“…However, the mafic‐ultramafic magmatism prior to the Late Triassic Ni–Cu sulphide deposits is important to understand the large‐scale mineralization in east CAOB. Especially, the Re–Os isotopic compositions indicated that the magmatic source was contaminated by a small amount of crustal material, and subsequent crystal fractionation resulted in the Cu–Ni mineralization (Hao et al, 2013; Hao, Wei, Zhao, Lu, & Zhao, 2015; Wu et al, 2004). In this study, we examined the mafic–ultramafic and felsic rocks from the Piaohechuan, Zhangxiang, and Qinglongcun plutons in central and eastern Jilin Province.…”

Section: Introductionmentioning

confidence: 99%

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Prelude to Late Triassic Ni–Cu sulphide mineralization in the eastern Central Asian Orogenic Belt: Geochronological and geochemical constraints from Middle Triassic mafic‐ultramafic magmatism in central and eastern Jilin Province, NE China

Xue

Sun

et al. 2022

Geological Journal

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The Hongqiling-Piaohechuan region in the east Central Asian Orogenic Belt (CAOB) is an economically important Ni-Cu sulphide mineralization region in China. It is widely accepted that these Ni-Cu sulphide deposits mainly formed during the Late Triassic period. The early Middle Triassic mafic-ultramafic plutons are therefore key in understanding the mineralization process. Here, we report the laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) U-Pb dating of zircon and geochemical data for two Middle Triassic mafic-ultramafic plutons and one felsic pluton in central and eastern Jilin Province, NE China. The mafic-ultramafic plutons are composed of gabbronorite and olivine websterite. Zircon dating results indicate that these mafic-ultramafic plutons crystallized at 243 ± 1 to 245 ± 1 Ma in the Middle Triassic. The coeval felsic pluton is mainly quartz diorite. Zircon dating results indicate that the felsic pluton crystallized at 239.7 ± 0.63 Ma in the later period of Middle Triassic. The mafic-ultramafic plutons are low in SiO 2 (43.49-49.66 wt%), depleted in K 2 O (0.28-2.74 wt%) and Na 2 O (0.70-1.18 wt%). They have low rare earth element (REE) abundances without Eu anomalies, exhibit depletion in high-field-strength elements (HFSEs), and hold various ε Hf (t) values (À15.3 to +2.9). These findings suggest that the primary magma of mafic-ultramafic plutons was derived from the partial melting of the depleted lithospheric mantle, metasomatized by subducted-slab-derived fluids/melts. Remarkably, these mafic-ultramafic plutons have extremely high 956 ppm, respectively).The coeval quartz diorites have 59.55-64.86 wt% of SiO 2 , 3.02-4.21 wt% of K 2 O and 3.97-4.49 wt% of Na 2 O. They are enriched in light REEs (LREEs) and large-ion lithophile elements (LILEs); depleted in heavy REEs (HREEs) and HFSEs, and they have ε Hf (t) values in the range À6.4 to +2.9. Additionally, the felsic rocks exhibit adakitic-features with high Sr/Y (28.5-58.7) and (La/Yb) N (4.9-12.2) ratios, implying the thickening crustal sources of the North China Craton (NCC) and CAOB, respectively. The above findings, combined with the regional geological data, suggest that the Middle Triassic mafic-ultramafic plutons are the prelude to the large-scale Late Triassic mineralization. This was induced by the thickening event of the later period of Middle Triassic felsic rocks, accompanying the final closure of the Palaeo-Asian Ocean (PAO) in the eastern CAOB.

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Section: Implications For the Late Triassic Large-scale Ni-cu Mineral...mentioning

confidence: 57%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Prelude to Late Triassic Ni–Cu sulphide mineralization in the eastern Central Asian Orogenic Belt: Geochronological and geochemical constraints from Middle Triassic mafic‐ultramafic magmatism in central and eastern Jilin Province, NE China

Xue

Sun

et al. 2022

Geological Journal

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“…The formation of the ore-bearing mafic-ultramafic intrusions in the CAOB has been suggested to have taken place in several different tectonic settings, including: (1) in association with a mantle plume (Zhou et al 2004;Pirajno et al 2008;Liu et al 2016), (2) Alaskan-type complexes, which form in subduction zones (Han et al 2007;Xiao et al 2009), and (3) a post-collisional extensional environment (Wu et al 2004;Tang et al 2011;Sun et al 2013b, c;Hao et al 2015).…”

Section: Tectonic Setting and Its Evolutionmentioning

confidence: 99%

Petrology, mineral chemistry, and geochemistry of Late Triassic Ni–Cu ore-bearing mafic–ultramafic intrusions, Hongqiling, northeastern China: petrogenesis and tectonic implications

Wang

Song

2019

Can. J. Earth Sci.

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The Hongqiling magmatic Ni–Cu sulfide deposit, situated on the southern margin of the eastern Central Asian Orogenic Belt (CAOB), is composed of over 30 mafic–ultramafic intrusions. These ore-bearing intrusions are composed mainly of harzburgite, lherzolite, websterite, orthopyroxenite, and norite (gabbro). The constituent minerals are olivine, diopside, bronzite, calcic-hornblende, plagioclase, and spinel with orthopyroxene as a dominant mineral in these intrusions. These ore-bearing intrusions are not Alaskan-type complexes. Spinel and clinopyroxene both exhibit different chemical compositions from those in the Alaskan-type complexes. The rocks that make up the intrusions have high contents of MgO (average value = 25.20 wt.%) and low TiO2 (average value = 0.58 wt.%). The high MgO contents of the minerals and the high Mg# (71) of the calculated melt in equilibrium with olivine demonstrate that the parental magma of the Hongqiling mafic–ultramafic intrusions was a high-Mg tholeiitic magma. The Hongqiling ore-bearing mafic–ultramafic intrusions and the calculated “trapped liquids” for the olivine-orthopyroxene cumulate rocks are all enriched in large-ion lithophile elements and depleted in high field strength elements. The Ce/Pb, Ta/La, Th/Yb, and (La/Sm)PM values and the depletion of Nb and Ta suggest that the magma experienced crustal contamination. The Hongqiling ore-bearing intrusions display many similarities with mafic–ultramafic intrusions that formed in a post-collisional extensional environment in the western CAOB (e.g., Huangshanxi). Common features include their whole-rock compositions and mineral chemistry. Combined with the evolutionary history of the eastern segment of the CAOB, we believe that the Late Triassic Hongqiling mafic–ultramafic intrusions formed in a post-collisional extensional environment.

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Linking Selective Alteration, Mineral Compositional Zonation and Sulfide Melt Emplacement in Orogenic-Type Magmatic Ni–Cu Sulfide Deposits

Cui

Wang

et al. 2022

Journal of Petrology

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The chemical characteristics of magmatic Ni-Cu sulfide deposits in orogenic settings differs from those in cratons as they are characterized by extensive alteration, presence of hydrous minerals, and typical normal mantle sulfur isotopes. How these characteristics are related to the mode of formation of the Ni-Cu sulfide deposits is still unknown. Here, we present petrological and mineralogical investigations of the Hongqiling Ni-Cu sulfide deposit, a typical representative of such numerous deposits in the Central Asian Orogenic Belt. Observations at various scales of field outcrops, hand specimens, thin sections and microscopes reveal that alterations are selectively exposed in silicate minerals, particularly olivine and pyroxenes that are close to ore bodies and sulfides. Such selective alteration is also related to sulfide type and abundance, and ore texture in the rocks/ores. It is worth noting that alteration of olivine and pyroxenes becomes weak when hydrous minerals (hornblende and phlogopite) are present. Profile analyses demonstrate that the olivine grains enclosed in or in contact with sulfides have compositional zonation with Fe, Mn, Sc and Zn concentrations higher in closer to the contacts with sulfides relative to the cores and contacts with other silicates, while those grains in sulfide-barren rocks show relatively homogeneous compositions. Similarly, the hornblende grains in contact with sulfide show distinctly compositional variations. Sulfides in rocks and ores are all free of alteration and have mantle-like sulfur isotopic compositions (pyrrhotite δ34S = -1.53 to 0.38 ‰; pentlandite δ34S = -1.28 to 0.25 ‰; chalcopyrite δ34S = -1.77 to 0.24 ‰). These features suggest that the selective alterations occurring in early crystallized phases were induced by sulfide melt intrusion and crystallization, instead of late-stage processes as previously thought. The sulfide melts segregated at the early stage of the magma evolution were presumably hydrous and buoyant in the silicate magma and therefore were transported upward and penetrated into silicate grains. The hydrous fluids were independent of the subducted material and metamorphic origin, and contained no significant crustal component in the late Triassic. Finally, when sulfides crystallized, fluids would be released from the sulfide melts to hydrate surrounding mineral phases and rocks, because sulfides theoretically don’t accommodate hydrous components. The fluids also enhanced compositional exchanges between sulfides and silicates and accounted for the crystallization of hydrous minerals. From this perspective, fluids play a critical role in sulfide melt transportation and silicate compositional alteration, and selective alteration can be considered as a significant indicator of mineralization and exploration in mafic-ultramafic intrusions.

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Newly identified Middle–Late Permian mafic–ultramafic intrusions in the southeastern margin of the Central Asian Orogenic Belt: Petrogenesis and its implications

Cited by 3 publications

References 40 publications

Prelude to Late Triassic Ni–Cu sulphide mineralization in the eastern Central Asian Orogenic Belt: Geochronological and geochemical constraints from Middle Triassic mafic‐ultramafic magmatism in central and eastern Jilin Province, NE China

Prelude to Late Triassic Ni–Cu sulphide mineralization in the eastern Central Asian Orogenic Belt: Geochronological and geochemical constraints from Middle Triassic mafic‐ultramafic magmatism in central and eastern Jilin Province, NE China

Petrology, mineral chemistry, and geochemistry of Late Triassic Ni–Cu ore-bearing mafic–ultramafic intrusions, Hongqiling, northeastern China: petrogenesis and tectonic implications

Linking Selective Alteration, Mineral Compositional Zonation and Sulfide Melt Emplacement in Orogenic-Type Magmatic Ni–Cu Sulfide Deposits

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