Late Triassic rifting and volcanism on the northeastern Indian margin: A new phase of Neo-Tethyan seafloor spreading and its paleogeographic implications
Introduction
The Tethys Himalaya zone preserves Paleozoic to Eocene sedimentary successions deposited on the northern margin of the Indian subcontinent facing the Neo-Tethys Ocean in the north (Gansser, 1964). Understanding the paleogeographic configuration of the Tethys Himalaya is therefore important for reconstructing the tectono-sedimentary history of the northern Indian margin and the evolution of Neo-Tethys.
Paleogeographic studies on the Late Triassic of the Tethys Himalaya had suffered from notable uncertainties. One major issue is represented by the presence in southern Tibet of the huge Langjiexue Group submarine fan deposystem deposited in continental-slope to rise environments (Li et al., 2003a, Li et al., 2003b; Li et al., 2004; Zhang et al., 2014; Zhang et al., 2015; Zhang et al., 2017; Wang et al., 2016a; Wang et al., 2016b). As provenance features of detritus from the Langjiexue Group differ significantly from those of most Tethys Himalayan terrigenous rocks, their provenance and depositional mechanism has been strongly disputed (Dai et al., 2008; Li et al., 2011; Li et al., 2014; Li et al., 2016a; Li et al., 2016b; Cai et al., 2016; Wang et al., 2016a; Wang et al., 2016b; Cao et al., 2018; Fang et al., 2018; Liu et al., 2020). A similar unit is represented by the Lamayuru complex and associated volcanic rocks, exposed in the Ladakh region of the northwestern Himalaya (Thakur, 1981; Robertson and Degnan, 1993; Robertson and Sharp, 1998; Robertson, 2007). The Lamayuru unit was deposited onto the distal Indian passive continental margin south of a Permian-Triassic Neo-Tethyan spreading axis (Robertson, 1998). In the more proximal shelfal environments of the Tethys Himalayan zone, accelerated tectonic subsidence, terrigenous influx, increased sedimentation rates, and transgression-regression cycles are well documented from southern Tibet (Jadoul et al., 1998; Meng et al., 2019) to Nepal (Garzanti et al., 1992, Garzanti et al., 1994a; Garzanti et al., 1994b) and the Spiti-Zanskar Synclinorium in the northwestern Himalaya (Garzanti et al., 1995).
The depositional pattern of the Upper Triassic Tethys Himalaya succession points to regional extension all along the northern Indian margin (Gaetani and Garzanti, 1991; Garzanti, 1993). The paleogeographic and tectonic significance of this extensional event, and its associated intraplate magmatism, however, are still incompletely understood and have been variably interpreted as the result of drifting of the Lhasa Block away from Gondwana (Metcalfe, 2002, Metcalfe, 2009) or as tectonic rejuvenation of the northern Gondwana margin (Sciunnach and Garzanti, 2012).
This paper presents data from the Upper Triassic mixed carbonate-terrigenous succession exposed in the Nanggarze area of southern Tibet and provides evidence of abundant bimodal mafic/felsic volcanic detritus indicating penecontemporaneous magmatic activity. Our aim is to discuss the geodynamic process that triggered such a magmatism and to shed new light on the paleogeographic implications of compositional and facies changes recorded by the sedimentary succession deposited onto the passive continental margin of northern India at Late Triassic time.
Section snippets
Geological background
The Neo-Tethys was a roughly E-W oriented paleo-ocean developed during Late Paleozoic to the earliest Cenozoic time and between the Laurasia landmass to the north and the Gondwana megacontinent to the south (Şengör, 1984). It was formed as a result of rifting along the north margin of Gondwana, and was closed due to the collision between Indian and Eurasian continents (The Indian subcontinent is a part of Gondwana and was broken away from the later in the Early Cretaceous; Hu et al., 2010).
Methods
The Tela Formation exposed near the Tela village was studied in detail and mapped in the field. Distribution of exposures, attitude of strata, rock type, and sedimentary structures were investigated and marked on a contour topographic base map (Fig. 2). The stratigraphic column was logged meter by meter, and samples were collected for laboratory study. Sedimentary facies were interpreted based on sedimentary structures and carbonate microfacies. Provenance analysis was carried out by
Stratigraphy and sedimentary facies
The Tela Formation was first defined by Wang et al. (1983) and described as exotic blocks within the Yamdrok mélange. During the 1:250000 regional geological mapping, the unit was subsequently revealed to represent a thrust slice covering an area > 20 km2. Our field investigation indicated that the Tela Formation is a tectonic unit juxtaposed with the Zongzhuo mélange in the north (Yamdrok mélange of Liu and Aitchison, 2002) and with Tethys Himalayan Jurassic–Cretaceous strata in the south (
Petrography of terrigenous clastics
The Tela Formation includes two different lithologies containing terrigenous detritus with different composition and zircon-age spectra. Sandy limestones found through the upper part of the Lower Member and the lower part of the Upper Member (Fig. 2) contain exclusively volcanic-derived mafic to felsic rock fragments and plagioclase accounting for 2–37% of framework grains, the rest being represented by bioclasts, ooids, and peloids (Figs. 6a–g, and 7). Angular to subrounded volcanic rock
Late Triassic rifting and volcanism along the northern margin of eastern Gondwana
Plagioclase, mafic and felsic volcanic rock fragments in sandy limestones of the Tela Formation and UPb detrital-zircon ages of ~229–223 Ma indicate penecontemporaneous bimodal magmatic activity (Fig. 8a-e). The lack of quartz and recycled sedimentary and metamorphic detritus suggests that the volcanic source was isolated from the main continent, and that was transported from nearby volcanic centers to shallow marine environments as airfall tuffs or by wave- and storm-induced currents. The
Conclusions
Integrated stratigraphic, petrographic, geochronologic and geochemical data from the Upper Triassic Tela Formation of the eastern Tethys Himalaya in southern Tibet shed new light on the paleogeographic and paleogeodynamic evolution of eastern Gondwana. Volcanic detritus in the Tela Formation indicates penecontemporaneous bimodal magmatism along the northeastern Indian margin. UPb dating of zircons firmly constrains this volcanic event as latest Carnian to early Norian (~229–223 Ma). The
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
We are deeply grateful to the Editor Thomas Algeo, Reviewer Alastair Robertson, Huan Li, and an anonymous reviewer for their very useful comments and constructive criticism. We thank Zhi-Chao Liu, Xiumian Hu, Yiwei Xu and Weiwei Xue for their help in the field, Yue-Heng Yang for help in the laboratory. This work was supported by the Basic Science Center Program (41888101), the National Natural Science Foundation of China (42072133, 41672109) and the Youth Innovation Promotion Associate Project
References (107)
- et al.
Evidence for early (>44 Ma) Himalayan crustal thickening, Tethyan Himalaya, southeastern Tibet
Earth Planet. Sci. Lett.
(2008) Correction of common lead in U–Pb analyses that do not report 204Pb
Chem. Geol.
(2002)- et al.
The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system
Earth Planet. Sci. Lett.
(1997) - et al.
Late Triassic paleogeographic reconstruction along the Neo-Tethyan Ocean margins, southern Tibet
Earth Planet. Sci. Lett.
(2016) - et al.
Late Triassic sedimentary records in the northern Tethyan Himalaya: tectonic link with greater India
Geosci. Front.
(2018) Terra Australis Orogen: rodinia breakup and development of the Pacific and Iapetus margins of Gondwana during the Neoproterozoic and Paleozoic
Earth Sci. Rev.
(2005)- et al.
Identification and discrimination of altered and metamorphosed volcanic rocks using immobile elements
Chem. Geol.
(1978) The significance of the Himalayan suture zone
Tectonophysics
(1980)Stratigraphy and sedimentary history of the Nepal Tethys Himalayan passive margin
J. Asian Earth Sci.
(1999)Petrographic classification of sand and sandstone
Earth Sci. Rev.
(2019)
The modern Nile sediment system: processes and products
Quat. Sci. Rev.
Pangean (Late Carboniferous–Middle Jurassic) paleoenvironment and lithofacies
Paleogeogr. Paleoclimatol. Paleoecol.
The Hf isotope composition of cratonic mantle: LAM-MC-ICPMS analysis of zircon megacrysts in kimberlites
Geochim. Cosmochim. Acta
Upper Jurassic–Lower Cretaceous stratigraphy in south-eastern Tibet: a comparison with the western Himalayas
Cretac. Res.
Provenance of Lower Cretaceous Wölong volcaniclastics in the Tibetan Tethyan Himalaya: implications for the final breakup of eastern Gondwana
Sediment. Geol.
The timing of India-Asia collision onset – facts, theories, controversies
Earth Sci. Rev.
Middle-Late Triassic bimodal intrusive rocks from the Tethyan Himalaya in South Tibet: geochronology, petrogenesis and tectonic implications
Lithos
The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U–Pb zircon geochronology
Chem. Geol.
The Tethys Himalayan passive margin from Late Triassic to Early Cretaceous (South Tibet)
J. Asian Earth Sci.
Provenance of late Triassic sediments in central Lhasa terrane, Tibet and its implication
Gondwana Res.
Stratigraphy of deep-water Cretaceous deposits in Gyangze, southern Tibet, China
Cretac. Res.
Multiple sources of the Upper Triassic flysch in the eastern Himalaya Orogen, Tibet, China: implications to palaeogeography and palaeotectonic evolution
Tectonophysics
Provenance and tectonic setting of Upper Triassic turbidites in the eastern Tethyan Himalaya: implications for early-stage evolution of the Neo–Tethys
Earth Sci. Rev.
Late Triassic crustal growth in southern Tibet: evidence from the Gangdese magmatic belt
Gondwana Res.
Permian tectonic framework and palaeogeography of SE Asia
J. Asian Earth Sci.
Gondwana dispersion and Asian accretion: tectonic and palaeogeographic evolution of eastern Tethys
J. Asian Earth Sci.
Triassic marine biogeography constrains the palaeogeographic reconstruction of Tibet and adjacent areas
Palaeogeogr. Palaeoclimatol. Palaeoecol.
Rift-related sedimentation and volcanism of the north-Indian margin inferred from a Permian–Triassic exotic block at Lamayuru, Indus suture zone (Ladakh Himalaya) and regional comparisons
J. Asian Earth Sci.
Mesozoic deep-water slope/rise sedimentation and volcanism along the North-Indian passive margin: evidence from the Karamba Complex, Indus suture zone (Western Ladakh Himalaya)
J. Asian Earth Sci.
Subsidence history of the Tethys Himalaya
Earth Sci. Rev.
Plešovice zircon-a new natural reference material for U–Pb and Hf isotopic microanalysis
Chem. Geol.
Gondwanaland from 650–500 Ma assembly through 320 Ma merger in Pangea to 185–100 Ma breakup: supercontinental tectonics via stratigraphy and radiometric dating
Earth Sci. Rev.
Petrogenesis of Middle–Late Triassic volcanic rocks from the Gangdese belt, southern Lhasa terrane: implications for early subduction of Neo-Tethyan oceanic lithosphere
Lithos
Upper Triassic turbidites of the northern Tethyan Himalaya (Langjiexue Group): the terminal of a sediment-routing system sourced in the Gondwanide Orogen
Gondwana Res.
Hf isotopic compositions of the standard zircons and baddeleyites used in U–Pb geochronology
Chem. Geol.
Cenozoic tectonic evolution of the Himalayan orogen as constrained by along-strike variation of structural geometry, exhumation history, and foreland sedimentation
Earth Sci. Rev.
Geological studies in the Indus Sutures Zone of Ladakh (Himalayas)
Late Anisian radiolarian assemblages from the Yarlung-Tsangpo Suture Zone in the Jinlu area, Zedong, southern Tibet: implications for the evolution of Neotethys
Island Arc
Halobia fauna from Zedong of South Xizang with a discussion on the Halobia assemblages in China
Acta Palaeontol. Sin.
Eleganuculana, new genus, and some other bivalves from the Upper Triassic of Kangmar in Xizang
Acta Palaeontol. Sin.
Nd isotopic compositions of the Tethyan Himalayan Sequence in southeastern Tibet
Sci. China Ser. D Earth Sci.
Principles of Tidal Sedimentology
Interpreting provenance relations from detrital modes of sandstones
Tectonics and sea-level changes recorded in Late Triassic Sequences at rifted margins of eastern and western Tethys (Northwest Australia, Leg 122; Western Europe)
Classification of carbonate rocks according to depositional textures
AAPG Mem.
A Late Devonian reef tract on northeastern Banks Island
NWT Bull. Can. Petrol. Geol.
Mesozoic seismic stratigraphy and tectonic evolution of the western Exmouth Plateau
Proc. Ocean Drill. Progr. Sci. Results
Provenance of the Langjiexue Group to the south of the Yarlung-Tsangpo Suture Zone in southeastern Tibet: insights on the evolution of the Neo-Tethys Ocean in the Late Triassic
Int. Geol. Rev.
Microfacies of Carbonate Rock: Analysis, Interpretation and Application
Multicyclic history of the northern India continental margin (NW Himalaya)
Am. Ass. Petr. Geol. Bull.
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