A slab break-off model for mafic–ultramafic igneous complexes in the East Kunlun Orogenic Belt, northern Tibet: insights from early Palaeozoic accretion related to post-collisional magmatism

Jin, Yan; Sun, Fengyue; Li, Liang; Yang, Yanqian; Zhang, Dexin

doi:10.1080/00206814.2018.1501618

Cited by 12 publications

(3 citation statements)

References 75 publications

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“…According to the Cr# values of spinel (0.28–0.40; Zhou et al ., 2016; Jia et al ., 2021), relatively high degree partial melting of the depleted mantle source for Shitoukengde was estimated to be 11.3–14.8% (average 13.4%) by using the formula mentioned above. The ε Hf ( t ) values of the Sulurian‐Devonian mafic–ultramafic complexes in the EKOB are generally positive, including Xiarihamu (Wang, 2014; Li et al ., 2015; Peng et al ., 2016), Akechukesai (Yan et al ., 2020), Shuixiannan (Yan et al ., 2019b), and Maxingdawannan (Yan et al ., 2019c). They still reveal the origin of primary magma derived from the depleted mantle, although the primary magma suffers from crustal contamination.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, the subducted oceanic crust certainly broke‐out due to the asymmetrical pulling force and a slab window formed (Li et al ., 2018). The suboceanic asthenospheric mantle passed through the slab window and upwelled, which led to relatively high degree partial melting (about 13.4%) of partial decompression melting, and produced a great amount of primary mafic–ultramafic magma with sufficient Ni–Cu–PGE (Wang et al ., 2014; Li et al ., 2018; Yan et al ., 2019b. Since the primary magma was positioned in the deep magma chamber, the magma underwent significant crustal assimilation and contamination (about 12–16%), and a large number of S, Si, and other crustal components were dissolved in magma (Figure 15).…”

Section: Discussionmentioning

confidence: 99%

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The parental magma composition, crustal contamination process, and metallogenesis of the Shitoukengde Ni‐Cu sulfide deposit in the Eastern Kunlun Orogenic Belt, NW China

Zhang

Tan

et al. 2021

Resource Geology

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Shitoukengde is an important magmatic Ni–Cu sulfide deposit in the Eastern Kunlun Orogenic Belt (EKOB). It comprises several mafic–ultramafic complexes and contains different kinds of mafic–ultramafic rocks. Lherzolite and olivine websterite are the most significant Ni–Cu‐hosted rocks. The No. I complex hosts six Ni–Cu ore bodies, and the depth of the intrusion has great exploration potential. Therefore, geochronology, geochemistry, and mineral chemistry of the Shitoukengde deposit were studied to constrain its mineralization time, parental magma composition, and crustal contamination process. Zircon U–Pb dating of olivine websterite shows the magmatic origin (Th/U = 0.40–1.05) and an age of 418.1 ± 8.7 Ma (MSWD = 0.01), which is coeval with the Xiarihamu, Akechukesai, and other Cu–Ni deposits in the EKOB. Geochemically, the mafic–ultramafic rocks are characterized by low SiO2, TiO2, and Na2O + K2O and high MgO (9.49–36.02%), with Mg# values of 80–87. They are relatively enriched in LREE and LILEs (e.g., K, Rb, and Th), with weakly positive Eu anomalies (δEu = 0.83–2.26), but depleted in HFSEs (e. g., Ta, Nb, Zr, and Ti). Based on the electron microprobe analyses, all of the olivines are chrysolite (Fo = 81–86), and the pyroxenes are dominated by clinoenstatite (En = 80–84) and augite (En = 49–55) in the mafic–ultramafic rocks. Therefore, the composition of parental magma is estimated to be picritic basaltic magma with SiO2 and MgO concentrations of 54.47 and 13.95%, respectively. The zircon εHf(t) values of olivine websterite vary from −0.8 to 4.6, with a TDM1 of 0.84–1.06 Ga, indicating that the parental magma was derived from relatively high degree partial melting (about 13.4%) of a depleted mantle source and experienced significant crustal contamination (about 12–16%). We propose that crustal assimilation, rather than fractional crystallization, played a key role in triggering the sulfide saturation of the Shitoukengde deposit, and the metallogenesis of “deep liquation–pulsing injection” is the key mechanism underlying its formation. The parental magma, before intruding, underwent liquation and partial crystallization at depth, partitioning into barren, ore‐bearing, and ore‐rich magma and ore pulp, and was then injected multiple times, resulting in the formation of the Shitoukengde Ni–Cu deposit.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The parental magma composition, crustal contamination process, and metallogenesis of the Shitoukengde Ni‐Cu sulfide deposit in the Eastern Kunlun Orogenic Belt, NW China

Zhang

Tan

et al. 2021

Resource Geology

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“…Each provides important information on the chemical history of the maficultramafic parental mantle source and its tectonic setting. Among these mafic-ultramafic intrusions, Xiarihamu intrusion contains super-large nickel deposits [13], and Shitoukengde and Binggounan also have nickel mineralization [14][15][16]22,[25][26][27], making the East Kunlun region a favorable area for magmatic copper-nickel sulfide deposits [12].…”

Section: Introductionmentioning

confidence: 99%

Petrogenesis of the Dalaku’an Mafic–Ultramafic Intrusion in the East Kunlun, Xinjiang: Constraints from the Mineralogy of Amphiboles

Fan,

Deng,

Xia

et al. 2024

Minerals

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The Dalaku’an mafic–ultramafic intrusion, located in the western segment of the East Kunlun, presents conducive conditions for the magmatic Cu-Ni sulfide deposits. According to the detailed petrographic observation, the amphiboles within distinct rock types were analyzed by EPMA analysis. The crystallization conditions, such as temperature, pressure, oxygen fugacity, and water content of the magma, were calculated to explore the genesis of the intrusion. The amphiboles were divided into three types: Amp-I, characterized by low silicon content but enrichment of aluminum, titanium, and alkali, predominantly comprising Tschermakitic hornblende and Magnesio-hornblende with mantle-derived traits; Amp-II, exhibiting elevated silicon content but diminished levels of aluminum, titanium, and alkali, primarily constituted of Magnesio-hornblende; whereas Amp-III manifests as Actinolitic hornblende, indicative of crustal origins. The calculated temperatures of amphiboles ranged between Amp-I (955–880) °C, Amp-II (852–774) °C, and Amp-III (761–760) °C; the pressures ranged between Amp-I (454–274) MPa, Amp-II (194–93) MPa, and Amp-III (101–84) MPa; the oxygen fugacities (△NNO) ranged between Amp-I (0.93–2.17), Amp-II (1.55–2.52), and Amp-III (1.89); and the water contents (H2Omelt) ranged from (6.69–8.67) to (5.90–7.32). The magma experienced multiple stages of crystallization and underwent complex magma evolution at different depths. The high oxygen fugacity and water content could be attributed to the subduction of the oceanic crust. The magma source of the Dalaku’an intrusion was metasomatized by fluids from subducting plates, thereby originating within a post-collision extension.

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Discovery of the Early Paleozoic Akechukesai high-Mg diorites in the western segment of East Kunlun Orogenic Belt and its constraints on the mechanism of break-off from Proto-Tethys oceanic subducted slab

Wang

Sun

Li³

et al. 2021

Geosci J

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A slab break-off model for mafic–ultramafic igneous complexes in the East Kunlun Orogenic Belt, northern Tibet: insights from early Palaeozoic accretion related to post-collisional magmatism

Cited by 12 publications

References 75 publications

The parental magma composition, crustal contamination process, and metallogenesis of the Shitoukengde Ni‐Cu sulfide deposit in the Eastern Kunlun Orogenic Belt, NW China

The parental magma composition, crustal contamination process, and metallogenesis of the Shitoukengde Ni‐Cu sulfide deposit in the Eastern Kunlun Orogenic Belt, NW China

Petrogenesis of the Dalaku’an Mafic–Ultramafic Intrusion in the East Kunlun, Xinjiang: Constraints from the Mineralogy of Amphiboles

Discovery of the Early Paleozoic Akechukesai high-Mg diorites in the western segment of East Kunlun Orogenic Belt and its constraints on the mechanism of break-off from Proto-Tethys oceanic subducted slab

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