Tracing the provenance of volcanic ash in Permian–Triassic boundary strata, South China: Constraints from inherited and syn-depositional magmatic zircons
Introduction
The Permian-Triassic boundary (PTB) represents the most severe mass extinction in Earth's history, when 90% of marine invertebrate species and 80% of terrestrial vertebrate families died out (Erwin et al., 2002; Irmis and Whiteside, 2012). Numerous volcanic ash beds are found close to the PTB in South China and have been invoked as evidence for a causative link between volcanic activity and the mass extinction (Xie et al., 2010; Shen et al., 2012). However, the origin of volcanic ash deposits in South China PTB sections remains contentious. Some researchers have proposed that they originated from the Siberian Traps Large Igneous Province (STLIP) (Xu et al., 2007; Shen et al., 2012), whereas others have inferred a source related to intraregional subduction-zone volcanic arcs, e.g., the Ailaoshan-Songma arc (Gao et al., 2013, Gao et al., 2015; Wang et al., 2018) or the Yidun arc in the Kunlun area (He et al., 2014). Although previous studies have used zircon U–Pb ages to show that PTB volcanic activity was synchronous with the mass extinction event (Shen et al., 2011; van de Schootbrugge and Wignall, 2016; Baresel et al., 2017), geochronological evidence alone is not conclusive because volcanism was prevalent on a global scale during the Permian-Triassic transition (Xiao et al., 2009; Metcalfe, 2013; Zi et al., 2013; Metcalfe et al., 2015; Gardiner et al., 2016).
Zircon is a common accessory mineral that is found in a wide variety of igneous rocks, and its refractory chemo-physical nature enables it to survive extreme temperature-pressure conditions and multiple cycles of weathering and erosion, preserving invaluable age and provenance information (Belousova et al., 2002; Grimes et al., 2015). Inherited zircons are exceedingly common in continental igneous rocks (Roddick and Bevier, 1995; Zeck and Williams, 2002) because residual zircons will not dissolve in magmas with a high Zr content (≥100 ppm) (Watson and Harrison, 1983). The age signatures recorded by inherited zircons provide evidence for the age distribution and evolutionary history of the crustal parent material (Zeck and Williams, 2002). Moreover, trace elements of zircons can provide insights into the nature, genesis and tectonic setting of the host magmas (Belousova et al., 2002; Grimes et al., 2015). PTB volcanic ash beds often contain zircons with inherited cores (Gao et al., 2013, Gao et al., 2015; Wang et al., 2018), but their significance has been insufficiently studied to date. In the present study, the age spectra of inherited zircons, as well as the ages and geochemical signatures of syn-depositional magmatic zircons, are integrated with other geological data to trace the provenance of the volcanic ash in PTB strata of South China.
Section snippets
Geological setting and study sections
The South China Craton consists of the Cathaysia Block in the southeast and the Yangtze Block in the northwest, which were assembled during the early Neoproterozoic Jiangnan Orogeny (Fig. 1; Cawood et al., 2017). The modern South China Craton is bordered by the North China Craton to the north (along the Qinling-Dabie orogenic belt), the Songpan-Ganzi Terrane to the west (along the Longmenshan Fault), and the Indochina Craton to the southwest (along the Ailaoshan-Song Ma Suture [ASSMS] Zone), as
Analytical methods
Zircon grains from the samples were separated by conventional magnetic and density separation procedures and then picked by hand under a binocular microscope. About 200 grains were randomly selected, mounted in epoxy and polished to expose the center of zircon crystals. Cathodoluminescence (CL) images were obtained using a JEOL JXA–8100 electron microscope to reveal the morphology and internal textures of the zircon grains. Zircon U–Pb dating and trace-element analyses were conducted at the
Zircon morphology and U–Pb dating
Zircons from volcanic ash beds of the four PTB study sections are mostly euhedral and prismatic, with crystal lengths varying mostly from 50 to 440 μm and aspect ratios from 1:1 to 3:1, and show well-developed core–rim textures. About 50% of the zircon crystals have relict cores, which are mostly round in shape and locally embayed (Fig. 3), reflecting partial dissolution. They are mostly 10–90 μm long and 5–80 μm wide, although their original sizes have been reduced by partial dissolution and
Sources of inherited zircons
Inherited zircons are incorporated into magmas during partial melting of preexisting continental crustal rocks (Watson and Harrison, 1983; Hill and Bickford, 2001). Therefore, the ages recorded by the inherited cores of zircons can be treated similarly to a population of detrital zircon grains and used to directly assess the age structure of basement rocks and other components of magma sources (Zeck and Williams, 2002). The abundant inherited zircons in the PTB volcanic ashes show a wide range
Conclusions
The inherited cores of zircon crystals from multiple volcanic ash layers in South China PTB strata yield an age spectrum highly similar to that of detrital zircons from the South China and Indochina cratons, but distinctly different from that of the Siberian Craton. Trace elements and O and Hf isotope signatures of the syn-depositional (ca. 251 Ma) zircons suggest a convergent margin setting for generation of the highly evolved source melts that produced Permian-Triassic ash layers on the South
Acknowledgments
We should like to thank Dr. Zhiyong Liao, Xiangdong Wang and Qiuling Gao for providing ash bed zircons images of NS, MS and DXK sections from South China. This work was jointly supported by the National Natural Science Foundation of China (41672222) and the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan (MSFGPMR201702). We thank Prof. Isabel Montanez for her editorial handling and Prof. Ian Metcalfe and an anonymous for constructive
References (89)
- et al.
Was the Indosinian orogeny a Triassic mountain building or a thermotectonic reactivation event?
Compt. Rendus Geosci.
(2008) - et al.
Complete biotic and sedimentary records of the Permian–Triassic transition from Meishan section, South China: ecologically assessing mass extinction and its aftermath
Earth Sci. Rev.
(2015) - et al.
Integrated provenance analysis of Carboniferous deposits from Northeastern Siberia: implication for the late Paleozoic history of the Arctic
J. Asian Earth Sci.
(2015) - et al.
Trans-Siberian Permian rivers: a key to understanding Arctic sedimentary provenance
Tectonophysics
(2016) - et al.
Origin of volcanic ash beds across the Permian-Triassic boundary, Daxiakou, South China: petrology and U-Pb age, trace elements and Hf-isotope composition of zircon
Chem. Geol.
(2013) - et al.
Petrogenesis of Triassic granites from the Nanling Range in South China: implications for geochemical diversity in granites
Lithos
(2014) - et al.
Zircon U–Pb geochronology, geochemistry and tectonic implications of Triassic A-type granites from southeastern Zhejiang, South China
J. Asian Earth Sci.
(2014) - et al.
Triassic granites in South China: a geochemical perspective on their characteristics, petrogenesis, and tectonic significance
Earth Sci. Rev.
(2017) - et al.
The closure of Palaeo-Tethys in Eastern Myanmar and Northern Thailand: new insights from zircon U-Pb and Hf isotope data
Gondwana Res.
(2016) - et al.
Early evolution of the Paleoasian Ocean: LA-ICP-MS dating of detrital zircon from late Precambrian sequences of the southern margin of the Siberian craton
Russ. Geol. Geophys.
(2013)
Detrital zircon provenance of early Palaeozoic sediments at the southwestern margin of the Siberian Craton: Insights from U–Pb geochronology
J. Asian Earth Sci.
U–Pb ages of detrital zircons within the Inthanon Zone of the Paleo-Tethyan subduction zone, northern Thailand: new constraints on accretionary age and arc activity
J. Asian Earth Sci.
Triggers of Permo-Triassic boundary mass extinction in South China: the Siberian Traps or Paleo-Tethys ignimbrite flare-up?
Lithos
Drivers for late Paleozoic to early Mesozoic orogenesis in South China: constraints from the sedimentary record
Tectonophysics
Permo-Triassic detrital records of South China and implications for the Indosinian events in East Asia
Palaeogeogr. Palaeoclimatol. Palaeoecol.
Restudy of conodont zonation and evolution across the P/T boundary at Meishan section, Changxing, Zhejiang, China
Glob. Planet. Chang.
Revised conodont zonation and conodont evolution across the Permian-Triassic boundary at the Shangsi section, Guangyuan, Sichuan, South China
Glob. Planet. Chang.
Metasedimentary melting in the formation of charnockite: petrological and zircon U-Pb-Hf-O isotope evidence from the Darongshan S-type granitic complex in southern China
Lithos
Permian arc magmatism in Mindoro, the Philippines: an early Indosinian event in the Palawan Continental Terrane
Tectonophysics
Mid-Silurian back-arc spreading at the northeastern margin of Gondwana: the Dapingzhang dacite-hosted massive sulfide deposit, Lancangjiang zone, southwestern Yunnan, China
Gondwana Res.
The Early Permian active continental margin and crustal growth of the Cathaysia Block: in situ U-Pb, Lu-Hf and O isotope analyses of detrital zircons
Chem. Geol.
Geochemistry and tectonic implications of late Mesoproterozoic alkaline bimodal volcanic rocks from the Tieshajie Group in the southeastern Yangtze Block, South China
Precambrian Res.
Heterogeneous volcanism across the Permian–Triassic Boundary in South China and implications for the Latest Permian Mass Extinction: new evidence from volcanic ash layers in the Lower Yangtze Region
J. Asian Earth Sci.
In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard
Chem. Geol.
Hafnium-neodymium constraints on source heterogeneity of the economic ultramafic-mafic Noril'sk-1 intrusion (Russia)
Lithos
Gondwana dispersion and Asian accretion: tectonic and palaeogeographic evolution of eastern Tethys
J. Asian Earth Sci.
High-precision U-Pb CA-TIMS calibration of Middle Permian to lower Triassic sequences, mass extinction and extreme climate-change in eastern Australian Gondwana
Gondwana Res.
New chronological constraints for Cryogenian to Cambrian rocks in the three Gorges, Weng'an and Chengjiang areas, South China
Gondwana Res.
The timing and extent of the eruption of the Siberian Traps large igneous province: implications for the end-Permian environmental crisis
Earth Planet. Sci. Lett.
U-Pb dating of granites with inherited zircon: conventional and ion microprobe results from two Paleozoic plutons, Canadian Appalachians
Chem. Geol.
U-Pb (SHRIMP II), Lu-Hf isotope and trace element geochemistry of zircons from high-grade metamorphic rocks of the Irkut terrane, Sharyzhalgay Uplift: implications for the Neoarchaean evolution of the Siberian Craton
Gondwana Res.
Linking the Indochina block and Gondwana during the Early Paleozoic: evidence from U-Pb ages and Hf isotopes of detrital zircons
Tectonophysics
West Gondwanaland during and after the Pan-African and Brasiliano orogenies: downslope vectors and detrital-zircon U-Pb and T DM ages and Hf/Nd pinpoint the provenances of the Ediacaran-Paleozoic molasse
Earth-Sci. Rev.
The geochronological and geochemical constraints on the petrogenesis of the Early Mesozoic A-type granite and diabase in northwestern Fujian province
Lithos
Detrital zircon U-Pb geochronology, Lu-Hf isotopes and REE geochemistry constrains on the provenance and tectonic setting of Indochina Block in the Paleozoic
Tectonophysics
Zircon saturation revisited: temperature and composition effects in a variety of crustal magma types
Earth Planet. Sci. Lett.
Where was the Ailaoshan Ocean and when did it open: a perspective based on detrital zircon U–Pb age and Hf isotope evidence
Gondwana Res.
Platinum-group elements of the Meishan Permian-Triassic boundary section: evidence for flood basaltic volcanism
Chem. Geol.
U-Pb isotope geochronology and geochemistry of granites from Hainan Island (northern South China Sea margin): constraints on late Paleozoic-Mesozoic tectonic evolution
Gondwana Res.
Large igneous province and magmatic arc sourced Permian-Triassic volcanogenic sediments in China
Sediment. Geol.
The protracted Permo-Triassic crisis and multi-episode extinction around the Permian–Triassic boundary
Glob. Planet. Chang.
The end-Permian regression in South China and its implication on mass extinction
Earth-Sci. Rev.
Zircon U–Pb chronology and elemental and Sr–Nd–Hf isotope geochemistry of two Triassic A-type granites in South China: implication for petrogenesis and Indosinian transtensional tectonism
Lithos
The source of Mesozoic granitoids in South China: integrated geochemical constraints from the Taoshan batholith in the Nanling Range
Chem. Geol.
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