Miocene post-collisional shoshonites and their crustal xenoliths, Yarlung Zangbo Suture Zone southern Tibet: Geodynamic implications

Hébert, Réjean; Guilmette, Carl; Dostál, J.; Bezard, Rachel; Lesage, Guillaume; Bédard, Émilie; Wang, Chengshan

doi:10.1016/j.gr.2013.05.013

Cited by 33 publications

(6 citation statements)

References 37 publications

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“…2; minor occurrences also occur in the eastern part of the belt; Miller et al, 1999;Wang et al, 2014a;Williams et al, 2004;Zhou et al, 2004Zhou et al, , 2009 (Guo et al, 2013;Miller et al, 1999;Wang et al, 2014a, b;Williams et al, 2004). Petrogenesis of these volcanic rocks is under debate, and their magmas have been interpreted to be derived from the Indian middle-lower crust (Hébert et al, 2014), enriched lithospheric mantle (e.g. Miller et al, 1999;Williams et al, 2004;Zhao et al, 2009), or India plate melt (± fluid)-modified mantle wedge (Guo et al, 2013).…”

Section: Alkaline Volcanismmentioning

confidence: 99%

The role of Indian and Tibetan lithosphere in spatial distribution of Cenozoic magmatism and porphyry Cu–Mo deposits in the Gangdese belt, southern Tibet

Wang

Richards

Zhou

et al. 2015

Earth-Science Reviews

130

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Section: Alkaline Volcanismmentioning

confidence: 99%

The role of Indian and Tibetan lithosphere in spatial distribution of Cenozoic magmatism and porphyry Cu–Mo deposits in the Gangdese belt, southern Tibet

Wang

Richards

Zhou

et al. 2015

Earth-Science Reviews

130

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“…Noteworthy, paleogeographic reconstructions propose that the Australpine block was located eastward (Ballèvre et al, 2018;Dallagiovanna et al, 2009;Spiess et al, 2010;von Raumer et al, 2003) with respect to the South Alpine, and this in turns means that the hypothesized subduction was dipping toward west beneath the South Alpine continental margin, conforming to petrological and geological features of modern westward subductions (Carminati & Doglioni, 2012;Doglioni et al, 1999). The hypothesis is coherent with the potassic character of the studied Permo-Triassic volcanism, as shoshonite series are typically widespread in volcanic arcs facing high-angle subductions (Beccaluva et al, 2013;Ishizuka et al, 2010;Leslie et al, 2009) and/or in postcollisional settings (Bianchini et al, 2008;Conticelli et al, 2007Conticelli et al, , 2009Hébert et al, 2014;Yang et al, 2012). Accordingly, the "crustal" isotopic fingerprint of the studied Permo-Triassic volcanic products conforms to the typical characters of basic magmas generated in final stages of subduction, as typically demonstrated by the circum-Tyrrhenian Plio-Quaternary volcanism that was developed on the wake of "mature" westward subduction (Bianchini et al, 2008;Conticelli et al, 2007Conticelli et al, , 2009.…”

Section: 1029/2017tc004950mentioning

confidence: 56%

Basic Dykes Crosscutting the Crystalline Basement of Valsugana (Italy): New Evidence of Early Triassic Volcanism in the Southern Alps

2018

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Basic dykes crosscutting the crystalline basement in Valsugana (Southern Alps, Italy) have been investigated for the first time in the framework of the known tectonomagmatic cycles. Petrographic observations and bulk rock analyses suggest a serial affinity variable between calc-alkaline (subordinate) and shoshonitic (prevalent), which are generally ascribed to a convergent plate setting. This is confirmed by Sr-Nd-Pb isotopic analyses that display extreme values that are often observed in postcollisional settings. A bulk rock Rb-Sr pseudoisochron suggests an age of the magmatism around 260 Ma, whereas K-Ar datings yield ages between 227 and 251 Ma, suggesting that these dykes plausibly represent a transition between the Permian and the Triassic volcanic episodes that are known in neighboring sectors of the Southern Alps. Considering that Permo-Triassic active subduction beneath the South Alpine is scarcely constrained, we ascribe the metasomatism of the related mantle sources to the Variscan cycle, proposing that magma genesis was delayed with respect to the time of the active subduction(s). According to recent reconstructions, parts of southeastern Europe, including the South Alpine domain, were formed by the breakup of the northern Gondwana margin from the Late Cambrian, in connection with important transtensional movements, leaving rifted continental basins or narrow oceanic seaways. In our view, the subduction processes that induced metasomatism in mantle sources of the South Alpine region occurred in the connection with the subsequent (Carboniferous?) consumption of lithosphere of these basins, a framework that is compatible with pervasive recycling of continental crust components within the mantle wedge. Then, calc-alkaline/shoshonite magmatism was triggered in the Early Triassic by postcollisional extensional tectonics that followed the Variscan orogenic cycle. the authors attributed the whole spectrum of these dykes to a hypothetic "alpine magmatism." This interpretation was probably influenced by the study of a single magmatic occurrence known as the lamprophyre of Calceranica, which was dated as Upper Cretaceous (71 ± 2 Ma) by Galassi et al. (1994). To cross-check this hypothesis, we collected new samples from dykes located close to the towns of Pergine and Levico and carried out petrographic investigation and major and trace element bulk rock analyses. Moreover, in order to provide further constraints, we carried out carbon (C), strontium (Sr), neodymium (Nd), and lead (Pb) isotopic analyses, as well as K-Ar dating.

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“…The Gangdese magmatic belt, referred to as the southern Gangdese belt or southern Lhasa subterrane by Zhu et al (2011), is located at the southern margin of the Lhasa Terrane and predominantly comprises intermediate-acid intrusions and volcano-sedimentary rocks. The southern subterrane which formed due to the northward subduction of the Yarlung Zangbo Tethyan lithosphere (Chu et al, 2006;Guo, Wilson, Zhang, Cheng, & Zhang, 2013;Zhu, Wang, Cawood, Zhao, & Mo, 2016) is characterized by widespread Gangdese granitoid batholiths and the Palaeocene-Eocene Linzizong volcanic succession with minor sedimentary cover (Wu, et al, 2014a;Zhang et al, 2010).In this subterrane, three kinds of post-collisional magmatic rocks (i.e., the mantle-derived ultrapotassic rocks, potassic volcanic rocks, and adakitic intrusions) were mainly developed 30-8 Ma (Chen, Xu, Wang, Kang, & Li, 2010;Guo & Wilson, 2012;Hébert et al, 2014;Zhao et al, 2009). The collision-type adakite-like intrusions formed smallvolume plugs or dikes, which intrude or crosscut the sedimentary formations (Chung et al, 2009), and some of these adakite-like intrusions are the main Cu-bearing porphyries (Hou et al, 2013).…”

Section: Regional Backgroundmentioning

confidence: 99%

Petrogenesis and geodynamic implications of the intrusions related to the Pusangguo skarn Cu‐dominated polymetallic deposit in Tibet: Constraints from geochronology, geochemistry, and Sr–Nd–Pb–Hf isotopes

Lang

Zhang³

et al. 2020

Geological Journal

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Pusangguo is a high‐grade skarn‐type Cu‐dominated polymetallic deposit and the only large‐sized Cu‐Pb‐Zn‐(Co‐Ni) deposit in the Gangdese metallogenic belt (GMB); the magmatic rocks associated with this deposit are poorly documented, and their petrogenesis and geodynamic setting are unclear. To explore these issues, we present zircon U–Pb ages along with Hf isotopic, whole‐rock geochemical, and Sr–Nd–Pb isotopic data for Pusangguo biotite granodiorite (PBG) and Pusangguo diorite porphyrite (PDP) in this deposit. Zircon U–Pb dating for these rocks indicates that they were emplaced during the Miocene (13.6–14.6 Ma). Geochemically, both PBG and PDP show characteristics of adakites, with intermediate SiO2 (65.55–67.30 wt% and 60.56–58.27 wt%, respectively), relatively high Al2O3 (15.28–15.85 wt% and 17.71–16.71 wt%, respectively) and Sr (599–723 ppm and 687–1,616 ppm, respectively) and low Y and Yb. In addition, they show relatively low ratios of (87Sr/86Sr)i and (206Pb/204Pb)i, (207Pb/204Pb)i and (208Pb/204Pb)i and relatively low values of εNd(t) and εHf(t). The Sr‐Nd‐Pb‐Hf isotopes of PBG and PDP are similar to those of the Miocene adakitic rocks associated with the porphyry–skarn deposits in the GMB, indicating that they were predominantly generated by partial melting of the thickened juvenile Lhasa Terrane lower crust and the PDP were likely to be generated through mixing between the magma parental to the PBG and a mafic end‐member. By combining our results with the previously reported results, we suggest that the model of delamination of the overthickened mantle lithosphere of Lhasa Terrane and convective upwelling of mantle asthenosphere which may involve Indian continental lithosphere.

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Miocene post-collisional shoshonites and their crustal xenoliths, Yarlung Zangbo Suture Zone southern Tibet: Geodynamic implications

Cited by 33 publications

References 37 publications

The role of Indian and Tibetan lithosphere in spatial distribution of Cenozoic magmatism and porphyry Cu–Mo deposits in the Gangdese belt, southern Tibet

The role of Indian and Tibetan lithosphere in spatial distribution of Cenozoic magmatism and porphyry Cu–Mo deposits in the Gangdese belt, southern Tibet

Basic Dykes Crosscutting the Crystalline Basement of Valsugana (Italy): New Evidence of Early Triassic Volcanism in the Southern Alps

Petrogenesis and geodynamic implications of the intrusions related to the Pusangguo skarn Cu‐dominated polymetallic deposit in Tibet: Constraints from geochronology, geochemistry, and Sr–Nd–Pb–Hf isotopes

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