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Article: IBM-type forearc magmatism in the Qilian Orogen records evolution from a continental to an intra-oceanic arc system in the Proto-Tethyan Ocean

TitleIBM-type forearc magmatism in the Qilian Orogen records evolution from a continental to an intra-oceanic arc system in the Proto-Tethyan Ocean
Authors
Issue Date2022
Citation
Gondwana Research, 2022, v. 110, p. 197-213 How to Cite?
AbstractForearc magmatism in IBM-type intra-oceanic arc systems is crucial for understanding the processes of subduction initiation and subsequent evolution of the arc system. Here we report a forearc volcanic sequence exposed in the Danghe-Nanshan, at the westernmost end of the South Qilian Accretionary Belt of the Qilian Orogen, NW China. Based on petrography and bulk-rock composition, three types of volcanic rocks (boninite, high-Mg basaltic andesite and andesite) and arc-related felsic plutons are identified. These rocks show correlating trends of trace elements and isotopes. The high-Cr spinels and clustered Ti/V ratios indicate that the boninite and high-Mg basaltic andesite magmas were derived from highly refractory peridotite sources in a forearc setting, whereas the andesite and felsic plutons were formed by fractionation of clinopyroxene and plagioclase from primary magma. Notably, slab-derived components have limited involvement in magma generation. Variation of fluid mobile/immobile element contents and Sr-Nd isotopic mixing calculations suggest less than 1% incorporation of subducted slab-derived fluids into the boninite source, whereas ∼1–3 % fluids and ∼3–7 % partial melts from the slab contributed to the high-Mg basaltic andesite and andesite, respectively. Therefore, an abnormally high mantle potential temperature (>1429 ℃) was required for boninite production because there were little aqueous fluids involved. Zircon U-Pb dating reveals these forearc magmas formed at ∼450 Ma. Combined with the regional tectonics and published data in this region, we suggest that these magmas record a tectonic process of arc system from active continental margin to newly formed intra-oceanic subduction zone during trench retreat of the Proto-Tethys Ocean.
Persistent Identifierhttp://hdl.handle.net/10722/317329
ISSN
2023 Impact Factor: 7.2
2023 SCImago Journal Rankings: 1.742
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorWen, T-
dc.contributor.authorSong, S-
dc.contributor.authorWang, C-
dc.contributor.authorAllen, MB-
dc.contributor.authorDong, J-
dc.contributor.authorFeng, D-
dc.contributor.authorSu, L-
dc.date.accessioned2022-10-07T10:18:33Z-
dc.date.available2022-10-07T10:18:33Z-
dc.date.issued2022-
dc.identifier.citationGondwana Research, 2022, v. 110, p. 197-213-
dc.identifier.issn1342-937X-
dc.identifier.urihttp://hdl.handle.net/10722/317329-
dc.description.abstractForearc magmatism in IBM-type intra-oceanic arc systems is crucial for understanding the processes of subduction initiation and subsequent evolution of the arc system. Here we report a forearc volcanic sequence exposed in the Danghe-Nanshan, at the westernmost end of the South Qilian Accretionary Belt of the Qilian Orogen, NW China. Based on petrography and bulk-rock composition, three types of volcanic rocks (boninite, high-Mg basaltic andesite and andesite) and arc-related felsic plutons are identified. These rocks show correlating trends of trace elements and isotopes. The high-Cr spinels and clustered Ti/V ratios indicate that the boninite and high-Mg basaltic andesite magmas were derived from highly refractory peridotite sources in a forearc setting, whereas the andesite and felsic plutons were formed by fractionation of clinopyroxene and plagioclase from primary magma. Notably, slab-derived components have limited involvement in magma generation. Variation of fluid mobile/immobile element contents and Sr-Nd isotopic mixing calculations suggest less than 1% incorporation of subducted slab-derived fluids into the boninite source, whereas ∼1–3 % fluids and ∼3–7 % partial melts from the slab contributed to the high-Mg basaltic andesite and andesite, respectively. Therefore, an abnormally high mantle potential temperature (>1429 ℃) was required for boninite production because there were little aqueous fluids involved. Zircon U-Pb dating reveals these forearc magmas formed at ∼450 Ma. Combined with the regional tectonics and published data in this region, we suggest that these magmas record a tectonic process of arc system from active continental margin to newly formed intra-oceanic subduction zone during trench retreat of the Proto-Tethys Ocean.-
dc.languageeng-
dc.relation.ispartofGondwana Research-
dc.titleIBM-type forearc magmatism in the Qilian Orogen records evolution from a continental to an intra-oceanic arc system in the Proto-Tethyan Ocean-
dc.typeArticle-
dc.identifier.emailWang, C: cwang531@hku.hk-
dc.identifier.doi10.1016/j.gr.2022.06.016-
dc.identifier.hkuros337420-
dc.identifier.volume110-
dc.identifier.spage197-
dc.identifier.epage213-
dc.identifier.isiWOS:000831588400001-

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