The complex life cycle of oceanic lithosphere: A study of Yarlung-Zangbo ophiolitic peridotites, Tibet
Introduction
Multiple mantle processes (e.g., lithospheric recycling, convective mixing, melt extraction and mantle metasomatism) have worked together to change the structure and composition of the mantle (cf., Hofmann, 1997, Herzberg, 2004, Bodinier and Godard, 2014, Becker and Dale, 2016). These processes are linked to plate tectonics and are crucial for understanding the geochemical evolution and geodynamic mechanism of the Earth’s upper mantle. Much progress has been made in the study of mantle geochemistry, such as the composition of the primitive mantle (e.g., Becker et al., 2006, Day et al., 2017), the scales and causes of mantle heterogeneity (e.g., Rampone and Hofmann, 2012, O’Driscolla et al., 2018), the isotopic mismatch between oceanic crust and mantle (e.g., Alard et al., 2005, Xiong et al., 2020), and even the mixing history of late accretion (e.g., Morgan et al., 2001, van de Löcht et al., 2018). However, the link between mantle processes and tectonic evolution remains unclear because of the difficulty in directly observing the mantle.
With often well-preserved mantle profiles and field context, ophiolitic peridotites provide an opportunity to study mantle processes and tectonic events recorded in them. Ophiolites represent slivers of oceanic lithosphere obducted onto continental margins (Dilek and Furnes, 2014). Compared to mantle xenoliths and abyssal peridotites, they may convey more information about tectonic environments (Pearce, 2014) and can contain an entire record from formation, accretion to modification of lithosphere (e.g., Xiong et al., 2016, Scott et al., 2019). However, ophiolitic peridotites are often strongly serpentinized. Unlike lithophile elements and their radioactive isotopes, the absolute and relative abundances of the highly siderophile elements (HSE, here including: Os, Ir, Ru, Pt, Pd and Re) and the Re-Os isotope system are relatively resistant to secondary alteration processes. Moreover, the fractionation of the HSE and the long-term evolution of the 187Re-187Os decay system have the potential to identify mantle processes which link to different tectonic events (Pearson et al., 2004, Rudnick and Walker, 2009).
The mantle section of Yarlung-Zangbo ophiolites (YZO) in southern Tibet (Fig. 1A) is an ideal place to build the connection between mantle processes and tectonic evolution due to excellent profile and the context provided by previous work on geochronology and geochemistry. Uranium-Pb zircon dating of basalts, diabases, gabbros and plagiogranites indicates that the crustal component formed mainly at ∼130–120 Ma (e.g., Hébert et al., 2012, Dai et al., 2013, Wu et al., 2014, Xiong et al., 2016). Whole-rock and mineral major and trace element geochemistry of mantle and crustal rocks has led to diverse interpretations of formation at mid-ocean ridge (MOR; e.g., Nicolas et al., 1981, Wu et al., 2014, Liu et al., 2014), intra-oceanic supra-subduction zone (SSZ; e.g., Malpas et al., 2003, Dai et al., 2013, Maffione et al., 2015), or from MOR to SSZ (e.g., Zhou et al., 2005, Hébert et al., 2012, Gong et al., 2016, Xiong et al., 2017).
In combination with petrology, mineralogy and whole-rock geochemistry, we utilize HSE abundances and Re-Os isotopic compositions to trace the evolution of YZO mantle peridotites. We report the geochemistry and isotopes of 52 ophiolitic peridotites from 3 localities (Purang, Baigang, Zedang; Fig. 1B) along the Yarlung-Zangbo suture zone to supplement 85 published Re-Os data from another 4 localities (Cuobuzha, Dongbo, Dazhuqu and Luobusa; Fig. 1B). We recognize three major mantle processes from this compilation, including: mixing of the convective upper mantle and the recycled ancient sub-continental lithospheric mantle (SCLM), followed by a regional melt extraction to form the oceanic lithosphere which was subsequently involved in a forearc setting and then infiltrated by S-saturated (or BMS (base metal sulfides)-rich) melts. This phenomenon is reported on a ∼2000 km scale for the first time, which provides important constraints on the multi-stage evolution in the life cycle of ophiolitic oceanic lithosphere.
Section snippets
Geological background and samples
The Tibetan Plateau is divided into several blocks by major tectonic boundaries from north to south, including the A'nemaqin-Kunlun, Jinshajiang, Bangong-Nujiang (BNSZ), and Yarlung-Zangbo suture zones (YZSZ) (Fig. 1A; Yin and Harrison, 2000, Dai et al., 2013). The YZSZ extends for more than 2000 km across the southern Tibet and marks the boundary between the Tethyan Himalaya from the Greater Indian continent and the Lhasa terrane from the Asian continent. The BNSZ extends for more than 1200 km
Analytical methods
Detailed analytical procedures used to produce the data in this study, as well as analytical precision and accuracy, are provided in the Electronic Annex. All analyses were conducted at China University of Geosciences, Beijing, and here we briefly summarize the methods: (1) Whole-rock major element compositions were determined by an inductively coupled plasma optical emission spectrometer (ICP-OES) and the analytical precision is 1–3% (e.g., Song et al., 2015); (2) Whole-rock trace element
Whole-rock major and trace element compositions
Whole-rock major and trace element compositions of the Purang and Zedang samples were reported by Su et al., 2015, Xiong et al., 2017, respectively, and thus they are not described in detail here but summarized along with other YZO ophiolites in Tables S1 and S2. All Baigang harzburgites have very high LOI values (11.8–14.8 wt.%) owing to strong serpentinization, and their anhydrous whole-rock major element compositions are reported in Table 1 and Fig. 2. These peridotites have low Al2O3
Serpentinization and weathering
Ophiolitic peridotites commonly experience serpentinization and/or weathering subsequent to their formation. The YZO peridotites also exhibit evidence for various degrees of alteration. For instance, the LOI values (near zero to 14.8 wt.%; Table S1) and the amounts of serpentine and magnetite increase for peridotites from the eastern to the western and central YZO. Although these alteration processes usually have little effect on relative abundances of most major and trace elements in
Conclusions
The YZO peridotites are dominated by depleted harzburgites with minor lherzolites. Three mantle processes are recognized in these peridotites: mixing of asthenospheric mantle (with a TRD age primary mode at ∼0.25 Ga) and ancient SCLM (TRD of ∼1.0–2.2 Ga), followed by large-scale melt extraction to form mixed oceanic lithosphere which was subsequently infiltrated by S-saturated melts. We propose a multi-stage subduction model to account for the origin of these peridotites during the evolution of
Acknowledgements
This study was supported by funding from the Second Tibetan Plateau Scientific Expedition and Research Program (STEP) (2019QZKK0801), the National Natural Science Foundation of China (Nos. 41822301, 41790451, 41730214, 41873032 and 91755205), China “1000 Youth Talents Program” and the 111 project (B18048). We thank Gongcheng Tian for assistance in the field, and Peter A. Cawood, Jin-Gen Dai, and Xiao-Han Gong for discussion. We are grateful to Associate Editor Rich Walker for his efficient
References (95)
- et al.
Detrital zircon U-Pb ages along the Yarlung-Tsangpo suture zone, Tibet: implications for oblique convergence and collision between India and Asia
Gondwana Res.
(2011) - et al.
Highly siderophile element composition of the Earth’s primitive upper mantle: constraints from new data on peridotite massifs and xenoliths
Geochim. Cosmochim. Acta
(2006) - et al.
Orogenic, ophiolitic, and abyssal peridotites
(2014) - et al.
Petrology and geochemistry of peridotites in the Zhongba ophiolite, Yarlung Zangbo Suture Zone: implications for the early cretaceous intra-oceanic subduction zone within the Neo-Tethys
Chem. Geol.
(2011) - et al.
Rapid forearc spreading between 130 and 120 Ma: evidence from geochronology and geochemistry of the Xigaze ophiolite, southern Tibet
Lithos
(2013) - et al.
186Os–187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os-rich alloys
Geochim. Cosmochim. Acta
(2017) - et al.
Osmium isotope compositions of detrital Os-rich alloys from the Rhine river provide evidence for a global Mesoproterozoic mantle depletion event
Earth Planet. Sci. Lett.
(2016) - et al.
Laboratory partitioning of platinum-group elements (PGE) and gold with application to magmatic sulfide–PGE deposits
Lithos
(1999) - et al.
Recycling of ancient subduction-modified mantle domains in the Purang ophiolite (southwestern Tibet)
Lithos
(2016) - et al.
Ancient melt extraction from the oceanic upper mantle revealed by Re–Os isotopes in abyssal peridotites from the Mid-Atlantic ridge
Earth Planet. Sci. Lett.
(2006)
The Indus-Yarlung Zangbo ophiolites from Nanga Parbat to Namche Barwa syntaxes, southern Tibet: first synthesis of petrology, geochemistry, and geochronology with incidences on geodynamic reconstructions of Neo-Tethys
Gondwana Res.
Re-Os isotopic constraints on the evolution of the Bangong-Nujiang Tethyan oceanic mantle, Central Tibet
Lithos
Re-evaluating digestion methods for highly siderophile element and 187Os isotope analysis: evidence from geological reference materials
Chem. Geol.
Boninites as windows into trace element mobility in subduction zones
Geochim. Cosmochim. Acta
Preservation of ancient Os isotope signatures in the Yungbwa ophiolite (southwestern Tibet) after subduction modification
J. Asian Earth Sci.
Limited recycling of crustal osmium in forearc mantle during slab dehydration
Geology
Formation of gabbronorites in the Purang ophiolite (SW Tibet) through melting of hydrothermally altered mantle along a detachment fault
Lithos
Processes controlling highly siderophile element fractionations in xenolithic peridotites and their influence on Os isotopes
Earth Planet. Sci. Lett.
The longevity of Archean mantle residues in the convecting upper mantle and their role in young continent formation
Earth Planet. Sci. Lett.
The composition of the Earth
Chem. Geol.
Osmium isotopic compositions of mantle xenoliths: a global perspective
Geochim. Cosmochim. Acta
Basaltic liquids and harzburgitic residues in the Garrett Transform: a case study at fast-spreading ridges
Earth Planet. Sci. Lett.
Re–Os isotope systematics and platinum group element fractionation during mantle melt extraction: a study of massif and xenolith peridotite suites
Chem. Geol.
Stabilisation of Archaean lithospheric mantle: a Re-Os isotope study of peridotite xenoliths from the Kaapvaal craton
Earth Planet. Sci. Lett.
A global overview of isotopic heterogeneities in the oceanic mantle
Lithos
Interpreting ages from Re–Os isotopes in peridotites
Lithos
Continent stabilisation by lateral accretion of subduction zone-processed depleted mantle residues; insights from Zealandia
Earth Planet. Sci. Lett.
Ancient depleted mantle as a source of boninites in the Izu-Bonin-Mariana arc: evidence from Os isotopes in Cr-spinel and magnetite
Chem. Geol.
Global continental and ocean basin reconstructions since 200 Ma
Earth Sci. Rev.
Multiple events in the Neo-Tethyan oceanic upper mantle: evidence from Ru–Os–Ir alloys in the Luobusa and Dongqiao ophiolitic podiform chromitites, Tibet
Earth Planet. Sci. Lett.
Melt/mantle mixing produces podiform chromite deposits in ophiolites: implications of Re–Os systematics in the Dongqiao Neo-tethyan ophiolite, northern Tibet
Gondwana Res.
The formation of pangea
Tectonophysics
Iron and magnesium isotope fractionation in oceanic lithosphere and sub-arc mantle: Perspectives from ophiolites
Earth Planet. Sci. Lett.
Distinctive melt activity and chromite mineralization in Luobusa and Purang ophiolites, southern Tibet: constraints from trace element compositions of chromite and olivine
Sci. Bull.
Subarctic physicochemical weathering of serpentinized peridotite
Earth Planet. Sci. Lett.
Os, Sr, Nd, and Pb isotope systematics of southern African peridotite xenoliths: implications for the chemical evolution of subcontinental mantle
Geochim. Cosmochim. Acta
Petrogenesis of boninitic lavas from the Troodos Ophiolite, and comparison with Izu–Bonin–Mariana fore-arc crust
Earth Planet. Sci. Lett.
Major and trace element composition of the depleted MORB mantle (DMM)
Earth Planet. Sci. Lett.
Southward trench migration at ∼130–120 Ma caused accretion of the Neo-Tethyan forearc lithosphere in Tibetan ophiolites
Earth Planet. Sci. Lett.
Sulfide in dunite channels reflects long-distance reactive migration of mid-ocean-ridge melts from mantle source to crust: a Re-Os isotopic perspective
Earth Planet. Sci. Lett.
Controls on platinum-group elemental distributions of podiform chromitites: a case study of high-Cr and high-Al chromitites from Chinese orogenic belts
Geochim. Cosmochim. Acta
The origin and pre-Cenozoic evolution of the Tibetan Plateau
Gondwana Res.
The Lhasa Terrane: record of a microcontinent and its histories of drift and growth
Earth Planet. Sci. Lett.
In situ Os isotopes in abyssal peridotites bridge the isotopic gap between MORBs and their source mantle
Nature
Structure and evolution of the Himalaya-Tibet orogenic belt
Nature
Distribution and processing of highly siderophile elements in cratonic mantle lithosphere
Rev. Mineral. Geochem.
Re–Pt–Os isotopic and highly siderophile element behavior in oceanic and continental mantle tectonites
Rev. Mineral. Geochem.
Cited by (45)
Circum-cratonic mantle archives the cumulative effects of plume and convergence events
2023, Geochimica et Cosmochimica ActaMantle peridotites of ophiolites rarely preserve reliable records of paleo-oceanic lithospheric mantle
2023, Earth-Science ReviewsRejuvenation of the lithospheric mantle beneath the orogens: Constraints from elemental geochemistry and Os isotopes in mantle xenoliths
2023, Geochimica et Cosmochimica Acta