Compositional heterogeneity of Archean mantle estimated from Sr and Nd isotopic systematics of basaltic rocks from North Pole, Australia, and the Isua supracrustal belt, Greenland
Introduction
Geochemical differences between mid-ocean ridge basalt (MORB) and ocean island basalt (OIB) are key to understanding the structure and differentiation history of the Earth’s mantle (e.g., Hofmann, 2003). Present-day MORBs have relatively high 143Nd/144Nd ratios and low 87Sr/86Sr, 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb ratios compared to OIBs, with some overlap in multi-dimensional spaces (Iwamori and Nakamura, 2015). Typically, these rocks also have distinct trace-element abundances and patterns, with lower abundances of more incompatible elements in MORBs. These characteristics indicate that a geochemically heterogeneous mantle has developed throughout Earth’s history via: (i) extraction of continental crustal components to create a depleted mantle as a MORB source; and (ii) recycling of various components, including subducted oceanic crusts, lithospheric mantle, and lower mantle/core components, that constitute rising plumes as OIB sources (e.g., Hofmann, 2003). The mechanisms by which such distinct source materials are physically distributed in the mantle are extensively debated. For example, shallow/deep origins of MORB/OIB source mantles might lead to layered mantle whereas shallow/deep melting of uniformly heterogeneous mantle involving marble cake mantle might have occurred (Ito and Mahoney, 2005). In any case, the differences between MORB and OIB in terms of geodynamic setting are key to discriminate the two distinct mantle sources; i.e., a depleted mantle source as a counterpart of continental crust, which is vastly melted adiabatically by passive upwelling of an average mantle of potential temperature beneath mid-ocean ridges associated with divergence of the plates (for MORB; McKenzie and Bickle, 1988), and an enriched or primitive mantle source as a recycled crustal component or undifferentiated mantle, which is melted by decompression melting of actively upwelling mantle plume of a relatively high potential temperature (for OIB; Watson and McKenzie, 1991). As long as a similar geodynamic system with plate tectonics and mantle convection with plumes operates, MORB and OIB may serve as geochemical probes looking into the mantle sources.
The geochemistry of Archean basaltic rocks is, therefore, important for providing direct information on the early evolution and near-initial conditions of the crust-mantle system. Numerous studies have focused on Archean rocks exposed in Canada (Bowring et al., 1989, Collerson et al., 1991, Koshida et al., 2016, Morino et al., 2017), Greenland (Nutman et al., 1997, Polat et al., 2002, Nutman et al., 2007, Rizo et al., 2012, Furnes et al., 2014), Australia (Fletcher et al., 1984, Van Kranendonk et al., 2003, Tessalina et al., 2010), and South Africa (Hegner et al., 1984, Blichert-Toft and Arndt, 1999, Puchtel et al., 2014). Much of this work has focused on isotopic analyses to understand the mantle evolution (e.g., Shirey and Hanson, 1986, Bennett et al., 1993, McCulloch, 1994, McCulloch and Bennett, 1994, Vervoort et al., 1996). These studies have shown that the Archean rocks show a wide compositional range including isotopic ratios (e.g., εNd ranging between −9 and +6 at 2.5 Ga, Bowring and Housh, 1995) and that the mantle has developed rapidly. The presence of highly enriched crustal materials (e.g., high µ signatures at 3.8 Ga, Kamber et al., 2003, and low 142Nd/144Nd values at 1.5 Ga, Upadhyay et al., 2009) and highly depleted early Archean rocks (e.g., an εNd value of approximately 3 at 3.8 Ga, Collerson et al., 1991, Bennett et al., 1993) indicate a significant degree of differentiation in the early Earth. Furthermore, the Sm-Nd system observed in several samples is indicative of post-magmatic processes (Polat et al., 2003).
To better understand the early geochemical evolution of the mantle, we report new geochemical analyses for Archean basaltic rocks from the North Pole region (NP) of the Pilbara Craton (3.5 Ga), Western Australia, and the Isua supracrustal belt (ISB), southern West Greenland (3.7–3.8 Ga). These rocks have similar lithostratigraphies to modern oceanic plates, from basaltic lava through pelagic sedimentary rocks to terrigenous sedimentary rocks. The basaltic rocks were, therefore, classified into MORB-type and OIB-type rocks based on their geological occurrence (Komiya et al., 2002a, Komiya et al., 2004). We measured the trace-element and isotopic compositions (87Sr/86Sr and 143Nd/144Nd) of the MORB-type and OIB-type rocks in NP and the ISB to assess the geochemical evolution of the Earth’s mantle during the Archean.
Section snippets
North Pole region
North Pole is located in the East Pilbara Craton, Western Australia (Fig. 1A). North Pole is underlain by the Mesoarchean monzogranite batholith and a greenstone belt that forms a domal structure due to the intrusion of the monzogranite at 3459 Ma (Thorpe et al., 1992). The Archean greenstone belt consists of predominant basaltic rock, subdominant bedded-chert intercalated with barite layers, and minor components of felsic volcanics, clastic sedimentary rocks, and siliceous dikes (Hickman, 1983
MORB- and OIB-type basalts in the North Pole area
On the basis of the classifications described in Section 2, we selected six NP-MORBs (sample IDs: E67, E148, E151, E152, E166, and E168) and six NP-OIBs (sample IDs: E109, E126, E137, E313, G275, and 95NP164) for further examination. All of the samples contain relatively unaltered and unmetamorphosed phenocrysts of clinopyroxene and magnetite together with relict minerals and/or pseudomorphs of phenocryst of plagioclase, with some chlorite, actinolite, epidote, albite, and magnetite as
Geochemical characteristics of the MORB and OIB-type rocks in the North Pole area
Trace element compositions of the NP basalts are shown in Table 1 and the primitive mantle normalized spidergrams are shown in Fig. 3A. These plots show highly-scattered Rb, Ba, K, Pb, and Sr mobile elements in comparison to immobile high field strength elements (HFSE) and rare earth elements (REE). In particular, the NP-OIBs are more variable in the mobile elements than the NP-MORBs; both positive and negative spikes are shown on the spidergrams of the NP-OIBs for Ba and K. Both basalts show
Secondary alteration of ancient basalts and their primary composition
The NP basalts show large positive spikes in Rb and Sr (Fig. 3A). Moreover, the partitioning of Rb and Sr between clinopyroxene and melt, respectively, is strongly deviated from the equilibrium relationships in the mantle-basalt-andesite system (Fig. 4B). This indicates significant modification from their original composition, which is consistent with the estimated isochron ages; the Rb-Sr isochron age for all of the samples in the 87Rb/86Sr–87Sr/86Sr diagram (Fig. 5A) is 3271 ± 0.0136 Ma
Conclusion
We analyzed the Sr and Nd isotopic compositions of the Archean MORBs and OIBs from the North Pole area of Pilbara (3460 Ma), Western Australia, and the Isua supracrustal belt (~3800 Ma), Greenland. These Archean basalts are thought to preserve their original REEs and Nd isotopic compositions based on (i) the strong correlation between 147Sm/144Nd and 143Nd/144Nd ratios; (ii) the consistency between isochron ages and U-Pb ages; and (iii) the equilibrium partitioning among relict igneous
Acknowledgements
The authors would like to thank Dr. J-I. Kimura, Dr. Q. Chang, Dr. T. Hanyu, and Dr. M. Hamada for their technical support and advice concerning analysis. We also thank Dr. M. Uno, Dr. T. Nishizawa, and K. Chiba for their help and discussion, and anonymous reviewers for their constructive comments and encouragements. We would like to thank Editage (www.editage.com) for English language editing.
Funding
This work was supported by JSPS KAKENHI [Grant Numbers 26247091; 26220713] from Japan Society for the Promotion of Science (JSPS).
References (124)
- et al.
Remnants of an Early Archean (>3.75 Ga) sea-floor, hydrothermal system in the Isua Greenstone Belt
Precambrian Res.
(2001) - et al.
Dacitic ocelli in mafic lavas, 3.8–3.7 Ga Isua greenstone belt, West Greenland: geochemical evidence for partial melting of oceanic crust and magma mixing
Chem. Geol.
(2009) - et al.
Intermediate P/T-type regional metamorphism of the Isua Supracrustal Belt, southern west Greenland: The oldest Pacific-type orogenic belt?
Tectonophysics
(2015) - et al.
The 1993 atomic mass evaluation: (1) Atomic mass table
Nucl. Phys. A
(1993) - et al.
The 1995 update to the atomic mass evaluation
Nucl. Phys. A
(1995) - et al.
Neoproterozoic contaminated MORB of Wadi Ghadir ophiolite, NE Africa: Geochemical and Nd and Sr isotopic constraints
J. Afr. Earth Sci.
(2011) - et al.
Archean depleted mantle: Evidence from Nd and Sr initial isotopic ratios of carbonatites
Geochim. Cosmochim. Acta
(1987) - et al.
Nd isotopic evidence for transient, highly depleted mantle reservoirs in the early history of the Earth
Earth Planet. Sci. Lett.
(1993) - et al.
The Nd and Hf isotopic evolution of the mantle through the Archean. Results from the Isua supracrustals, West Greenland, and from the Birmian terranes of West Africa
Geochim. Cosmochim. Acta
(1999) - et al.
Hf isotopes compositions of komatiites
Earth Planet. Sci. Lett.
(1999)
A two-stage model for the formation of the granite-greenstone terrains of the Kalgoorlie-Norseman area, Western Australia
Earth Planet. Sci. Lett.
The Sm-Nd age of Kambalda volcanics is 500 Ma too old! Earth Planet
Sci. Lett.
Nd and Sr isotopic crustal contamination patterns in an Archean meta-basic dyke from northern Labrador
Geochim. Cosmochim. Acta
Episodic continental growth and supercontinents: a mantle avalanche connection? Earth Planet
Sci. Lett.
Sm-Nd geochronology of greenstone belts in the Yilgarn Block, Western Australia
Precambrian Res.
Four billion years of ophiolites reveal secular trends in oceanic crust formation
Geosci. Front.
Isua supracrustal belt (Greenland) a vestige of a 3.8 Ga suprasubduction zone ophiolite, and the implications for Archean geology
Lithos
Sr-Pb-Nd isotopic evidence that both MORB and OIB sources contribute to oceanic island arc magmas in Fiji
Earth Planet. Sci. Lett.
Growth and recycling of early Archean continental crust: geochemical evidence from the Coonterunah and Warrawoona Groups, Pilbara Craton, Australia
Tectonophysics
Age of the Archean Talga-Talga Subgroup, Pilbara Block, Western Australia, and early evolution of the mantle: new Sm-Nd isotopic evidence
Earth Planet. Sci. Lett.
Sm-Nd Dating of Archean basic and ultrabasic volcanics
Earth Planet. Sci. Lett.
Pb-Sr-Nd isotopic data of Indian Ocean ridges: new evidence of large-scale mapping of mantle heterogeneities
Earth Planet. Sci. Lett.
Sm-Nd studies of Archean metasediments and metavolcanics from West Greenland and their implications for the Earth's early history
Earth Planet. Sci.
Eoarchean tectonics: new constraints from high pressure-temperature experiments and mass balance modelling
Precambrian Res
Age and isotope geochemistry of the Archean Pongola and Usushwana suites in Swaziland, southern Africa: a case for crustal contamination of mantle-derived magma
Earth Planet. Sci. Lett.
Flow and melting of a heterogeneous mantle: 2. Implications for a chemically nonlayered mantle
Earth Planet. Sci. Lett.
Isotopic heterogeneity of oceanic, arc and continental basalts and its implications for mantle dynamics
Gondwana Res.
Evidence for subduction at 3.8 Ga: geochemistry of arc-like metabasalts from the southern edge of the Isua Supracrustal Belt
Chem. Geol.
Chemical separation of Nd from geological samples for chronological studies using 146Sm-142Nd and 147Sm-143Nd systematics
Anal. Chim. Ac.
Experimental determination of element partitioning between silicate perovskites, garnets and liquids: Constraints on early differentiation of the mantle
Earth Planet. Sci. Lett.
Continental recycling and true continental growth
Russian Geol. Geophys.
Petrology and geochemistry of mafic rocks in the Acasta Gneiss Complex: Implications for the oldest mafic rocks and their origin
Precambrian Res.
Determination of initial 87Sr/86Sr and 143Nd/144Nd in primary minerals from mafic and ultramafic rocks: Experimental procedure and implications for the isotopic characteristics of the Archean mantle under the Abitibi greenstone belt
Canada. Geochim. Cosmochim. Acta
Primitive 87Sr/86Sr from an Archean barite and conjecture on the Earth's age and origin
Earth Planet. Sci. Lett.
Progressive growth of the Earth’s continental crust and depleted mantle: Geochemical constraints
Geochim. Cosmochim. Acta
Constraints on the age of the Warrawoona Group, eastern Pilbara Block
Western Australia. Precambrian Res.
Chemical stratification in the post-magma ocean Earth inferred from coupled 146,147Sm–142,143Nd systematics in ultramafic rocks of the Saglek block (3.25–3.9 Ga; northern Labrador, Canada)
Earth Planet. Sci. Lett.
Protoliths of the 3.7–3.8 Ga Isua greenstone belt
West Greenland. Precambrian Res.
Growth fault control of Early Archaean cherts, barite mounds and chert-barite veins, North Pole Dome, Eastern Pilbara, Western Australia
Precambrian Res.
~3710 and ≥3790 Ma volcanic sequences in the Isua (Greenland) supracrustal belt; structural and Nd isotope implications
Chem. Geol.
New 1:20 000 scale geological maps, synthesisand history of investigation of the Isua supracrustal belt and adjacentorthogneisses, southern West Greenland: a glimpse of Eoarchean crust formationand orogeny
Precambrian Res.
Detrital zircon sedimentary provenance ages for the Eoarchean Isua supracrustal belt southern West Greenland: juxtaposition of an imbricated ca. 3700Ma juvenile arc against an older complex with 3920–3760Ma components
Precambrian Res.
Cross-examining Earth’s oldest stromatolites: Seeing through the effects of heterogeneous deformation, metamorphism and metasomatism affecting Isua (Greenland) ~3700 Ma sedimentary rocks
Precambr. Res.
Alteration and geochemical patterns in the 3.7–3.8 Ga Isua greenstone belt
West Greenland. Precambrian Res.
Boninite-like volcanic rocks in the 3.7–3.8 Ga Isua greenstone belt, West Greenland: geochemical evidence for intra-oceanic subduction zone processes in the early Earth
Chem. Geol.
Contrasting geochemical patterns in the 3.7–3.8 Ga pillow basalt cores and rims, Isua greenstone belt, Southwest Greenland: Implications for postmagmatic alteration processes
Geochim. Cosmochim. Acta
A review of structural patterns and melting processes in the Archean craton of West Greenland: Evidence for crustal growth at convergent plate margins as opposed to non-uniformitarian models
Tectonophysics
Insights into early Earth from the Pt–Re–Os isotope and highly siderophile element abundance systematics of Barberton komatiites
Geochim. Gosmochim. Acta
Recycled ocean crust and sediment in Indian Ocean MORB
Earth Planet. Sci. Lett.
Major episodic increases of continental crustal growth determined from zircon ages of river sands: implications for mantle overturns in the early Precambrian
Phys. Earth Planet. Inter.
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2021, Precambrian ResearchCitation Excerpt :A holistic understanding of the arc-generated history of the Archean can only be achieved by considering both these components. The geochemical characteristics of Eoarchean to Neoarchean volcanic and intrusive rocks and their geodynamic implications were discussed in detail in many recent studies (Dilek and Furnes, 2011; Polat et al., 2011a; Arndt, 2013; Turner et al., 2014; Furnes et al., 2014; Blichert-Toft et al., 2015; Wang et al., 2015; Grosch and Slama, 2017; Hildebrand et al., 2018; Hastie and Fitton, 2019; Nakamura et al., 2020; Van de Löcht et al., 2020; Sobolev et al., 2019; Lowrey et al., 2019; Gamal El Dien et al., 2020; Ning et al., 2020; Sotiriou and Polat, 2020). While we do recognize a secular cooling in the average mantle potential temperature, like the studies mentioned above, we take a generally uniformitarian approach to interpret the geochemical signatures of individual magmatic suites in Archean igneous rocks because they fall within the range on Earth's present-day thermal range, as explained below.
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