Petrogenesis of Middle Triassic intermediate-mafic igneous rocks in East Kunlun, Northern Tibet: Implications for the crust growth and Paleo-Tethyan orogeny

Yan, Dongdong; Xiong, Fuhao; Ma, Changqian; Hou, Mingcai; Zhao, Han

doi:10.1016/j.geogeo.2022.100096

Cited by 4 publications

(5 citation statements)

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“…The studied rhyolite exhibits higher whole-rock Mg # values (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53) and zircon ɛHf values (−0.6 to 3.0) than the coeval rhyolite porphyry (Mg # = 22-40; ɛHf = −7.3 to -3.8), implying their different origins or magmatic evolutionary processes.…”

Section: Origin Of the Felsic Volcanic Rocksmentioning

confidence: 88%

“…Granitoids and their eruptive equivalents are usually divided into I-, S-, M-, and A-type granitic rocks based on their petrogenetic mechanisms. In general, I-type granitic rocks are usually derived by the crust-mantle interaction or partial melting of metamorphic igneous rocks [14,44], S-type granitic rocks are formed by melting of aluminum-rich metasedimentary rocks associated with collision or post-collision setting [45], M-type granitic rocks are mainly derived by fractional crystallization of mantle-derived magma, while A-type granitic rocks mainly originated from various magma sources in extensional environment [16]. Revealing the petrogenetic types of granitoids and their volcanic equivalents is the key to understanding their petrogenesis and geodynamic implications.…”

Section: Petrogenetic Type Of the Felsic Volcanic Rocksmentioning

confidence: 99%

“…Similarly, the relatively high ratios of Al2O3/(FeOtot + MgO) and CaO/(MgO + FeOtot) suggest that the studied rhyolite is mainly derived from a metagreywacke source (Figure 11c,d). However, the rhyolite has high contents of SiO2 (71.7-74.3 wt%) and high values of Mg # (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53). This, as well as their juvenile or depleted zircon Lu-Hf isotopes, suggests that mantle materials, rather than pure crustal melts, contributed to their origins (Figure 11a).…”

Section: Origin Of the Felsic Volcanic Rocksmentioning

confidence: 99%

“…The εHf(t) values of zircons from the rhyolite (−0.6 to 3.0) are much higher than the Triassic granitoids derived from ancient continental crust in the EKOB (average εHf(t) values of −5.5; [62,63]) but close to the rocks derived from the enriched mantle or crust-mantle Similarly, the relatively high ratios of Al 2 O 3 /(FeO tot + MgO) and CaO/(MgO + FeO tot ) suggest that the studied rhyolite is mainly derived from a metagreywacke source (Figure 11c,d). However, the rhyolite has high contents of SiO 2 (71.7-74.3 wt%) and high values of Mg # (43)(44)(45)(46)(47)(48)(49)(50)(51)(52)(53). This, as well as their juvenile or depleted zircon Lu-Hf isotopes, suggests that mantle materials, rather than pure crustal melts, contributed to their origins (Figure 11a).…”

Section: Origin Of the Felsic Volcanic Rocksmentioning

confidence: 99%

“…The rhyolites have similar Hf isotopic compositions with Early Triassic mafic rocks derived from enriched mantle in East Kunlun. (~240Ma gabbro:εHf(t) = −1.8-−0.6 [44]), indicating a significant addition of mantle material probably derived from enriched lithospheric mantle. Rhyolites are LILE enriched and HFSE depleted and show obvious Nb-Ta-Ti troughs in primitive mantle-normalized trace element variation diagrams, exhibiting geochemical features of arc-related magmas, which implies an enrichment mechanism that was related to subducted components.…”

Section: Origin Of the Felsic Volcanic Rocksmentioning

confidence: 99%

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Petrogenesis of Early Triassic Felsic Volcanic Rocks in the East Kunlun Orogen, Northern Tibet: Implications for the Paleo-Tethyan Tectonic and Crustal Evolution

et al. 2023

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The felsic volcanic rocks in orogenic belts are vital probes to understand the tectonic evolution and continental crust growth. Here, we present a comprehensive study on the zircon U–Pb geochronology, whole-rock geochemistry, and zircon Lu-Hf isotopes of Early felsic volcanic rocks from the Hongshuichuan Formation, East Kunlun Orogen, Northern Tibet, aiming to explore their petrogenesis and implications for the Paleo-Tethyan orogeny and crustal evolution. The studied felsic volcanics comprise rhyolite porphyry and rhyolite, exhibiting coeval zircon U–Pb ages of ca. 247–251 Ma. Rhyolite porphyries show metaluminous to peraluminous nature (A/CNK = 0.88–1.24) with high SiO2 contents (72.1–78.9 wt%) and moderate Mg# values (22–40), and they display enrichment of LREE with (La/Yb)N ratios of 6.02–17.9 and depletion of high field strength elements. In comparison, the rhyolites are strongly peraluminous (A/CNK = 1.09–1.74) with high SiO2 contents (71.7–74.3 wt%) and high Mg# values (43–52) and are also enriched in LREE ((La/Yb)N of 6.65–18.4) and depleted in HFSE (e.g., Nb, Ta, Ti). Combining with their different zircon Lu-Hf isotopes, i.e., enriched isotopes for the rhyolite porphyries (εHf(t) = −7.3 to −3.8) and depleted Hf isotopes for the rhyolites (ɛHf = −0.6 to +3.0), we interpret that the studied rhyolite porphyries and rhyolites were derived by partial melting of Mesoproterozoic metagreywacke sources followed by plagioclase-dominated fractional crystallization, but the latter shows the significant contribution of crust–mantle magma mixing. The mixed mantle-derived magma comes from an enriched lithospheric mantle source that had been metasomatized by subduction-related fluids. Combining with other geological evidence, we propose that the studied Early Triassic felsic volcanic rocks were formed in a subduction arc setting, and the reworking of ancient continental crust with crust–mantle magma mixing is the major mechanism of crustal evolution in the East Kunlun Paleo-Tethyan orogenic belt.

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