ARTICLE https://doi.org/10.1038/s41467-020-20514-4 OPEN Widespread reworking of Hadean-to-Eoarchean continents during Earth’s thermal peak ✉ C. L. Kirkland 1 , M. I. H. Hartnady1, M. Barham 1, H. K. H. Olierook 1, A. Steenfelt2 & J. A. Hollis3 The nature and evolution of Earth’s crust during the Hadean and Eoarchean is largely unknown owing to a paucity of material preserved from this period. However, clues may be found in the chemical composition of refractory minerals that initially grew in primordial 1234567890():,; material but were subsequently incorporated into younger rocks and sediment during lithospheric reworking. Here we report Hf isotopic data in 3.9 to 1.8 billion year old detrital zircon from modern stream sediment samples from West Greenland, which document successive reworking of felsic Hadean-to-Eoarchean crust during subsequent periods of magmatism. Combined with global zircon Hf data, we show a planetary shift towards, on average, more juvenile Hf values 3.2 to 3.0 billion years ago. This crustal rejuvenation was coincident with peak mantle potential temperatures that imply greater degrees of mantle melting and injection of hot mafic-ultramafic magmas into older Hadean-to-Eoarchean felsic crust at this time. Given the repeated recognition of felsic Hadean-to-Eoarchean diluted signatures, ancient crust appears to have acted as buoyant life-rafts with enhanced preservation-potential that facilitated later rapid crustal growth during the Meso-and- Neoarchean. 1 Timescales of Mineral Systems Group, School of Earth and Planetary Sciences, Curtin University, Perth, WA 6102, Australia. 2 The Geological Survey of Denmark and Greenland, Øster Voldgade 10, 1350 Copenhagen K, Denmark. 3 Department of Geology, Ministry of Mineral Resources, Government of ✉ Greenland, P.O. Box 930, 3900 Nuuk, Greenland. email: [email protected] NATURE COMMUNICATIONS | (2021) 12:331 | https://doi.org/10.1038/s41467-020-20514-4 | www.nature.com/naturecommunications 1 ARTICLE NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-20514-4 espite decades of study, fundamental aspects of the fractionation event between parent and daughter elements in the Ddevelopment of Earth’s oldest continental crust remain source magma, can be used to address terrane affinity and rates of enigmatic. Various mechanisms have been proposed to crust production. Deeper into Earth’s history, there is inevitably a explain Archean crust formation including via mantle plumes1, progressively more fragmentary geological record as a con- density foundering and melt generation2, or bolide impacts3. sequence of loss of crystalline basement through crustal rework- Models for crust production over time are also variable, ing and erosion, which serves to reduce the temporal fidelity of depending on the balance between new crust extraction from the any record. However, sedimentary rocks preserve an important mantle versus recycling of old crust into the mantle, with the archive of crustal evolution by storing the denuded remains of equilibrium between these processes either mediated or expressed crystalline source rocks that may no longer be exposed, or even by tectonics4. Crust production rates have thus been regarded as extant. To track crustal evolution, detrital zircon Hf isotopes have key in understanding secular change in tectonic setting5. For proved to be particularly useful because of the mineral’s physical example, early continental crust before 3.0 billion years ago (Ga) and chemical robustness, while also recording time encoded may have formed via vertical processes6 but may additionally source information11,12. have formed via horizontal processes akin to present-day plate In this work, we present a new zircon U-Pb and Hf isotope tectonics7. Pre-existing continental crust may also play an dataset from stream sediment from a Mesoarchean to Neoarch- important role in nucleating further growth8,9. Thus growth of ean part of the North Atlantic Craton (NAC), southwest continental crust is closely coupled with plate tectonics and Greenland that records hitherto unrecognized >3.2 Ga compo- magmatic fractionation, but the rate and mechanism of crust nents (Fig. 1; further details on the geological history of the NAC production toward the present continents remains uncertain. are given in Supplementary Note 1). Combined with global zircon Tracking the evolution of our oldest continental crust has Hf datasets from other Mesoarchean to Neoarchean regions commonly employed radiogenic isotopes such as Lu-Hf, which (Canada, Australia, southern Africa, South America), we resolve magmatic source region characteristics of dated crystalline demonstrate a widespread dilution of Hadean-to-Eoarchean crust basement and can be recast to a measure of mantle extraction10. in the Mesoarchean, coincident with other significant geochem- Such Hf isotope signatures, fundamentally reflecting a ical changes to our planet. These findings have implications for a 52° W 50° W UTM zone 22 N NeoNeoarcheaneoeoarcrcrcheahe n rewrreworkingeworkoro kingng Qarliit Tasersuat GREENL 2 12 3 AN 65.5° N D 11 13 ICE Kimberlite with SH 3.6 Ga zircon E 30 km 5 E T 65° N 10 b 7 D AN 9 L N EE 64.5° N R 5 Pooled sample G Terrane boundary 8 2.6-2.5 Ga 2.8-2.7 Ga North 2.9-2.8 Ga Atlantic Granitoids c. 2.9-2.7 Ga Craton c. 3 Ga 500 km c. 3.2 Ga Crust c. 3.8-3.6 Ga Fig. 1 Lithological age map of the northern part of the North Atlantic Craton. a Lithological age map of the northern part of the North Atlantic Craton showing stream sediment detrital zircon sample locations with sample identification number. Age map based on new field mapping and interpretations discussed in Friend and Nutman67. b Inset shows the location of the study area (black outlined box) with respect to exposures of Archean bedrock (pink hues) in Greenland. 2 NATURE COMMUNICATIONS | (2021) 12:331 | https://doi.org/10.1038/s41467-020-20514-4 | www.nature.com/naturecommunications NATURE COMMUNICATIONS | https://doi.org/10.1038/s41467-020-20514-4 ARTICLE models of early crustal evolution by illustrating the need for Metamorphic features including homogeneous rims are present Hadean-to-Eoarchean precursors to preserve characteristic late on some grains but analyses targeted zones of primary magmatic Archean tonalite–trondhjemite–granodiorite (TTG). texture. Most analyses (>94%) are within 10% discordance limits (Supplementary Note 2). The detrital dataset shows major age peaks at c. 3.2, 3.0 and 2.8–2.7 Ga, with minor components as Results young as 1.8 Ga and as old as c. 3.8 Ga (Fig. 3 and Supplementary Provenance of stream sediment zircons. Stream sediment was Fig. 1). The c. 3.0 Ga detrital zircon age component is ubiquitous systematically sampled at a density of one sample station per throughout the stream sediment samples and directly corre- 20–50 km2 over large parts of Greenland13. Streams with catch- sponds to the dominant age of crystalline rock within the local ment areas <20 km2 were chosen to ensure that most material region15,16 (Fig. 1). A 2.8–2.7 Ga detrital component accounts for deposited at the sampling site was locally derived. Local deriva- a significant percentage of some samples (2, 3, 12). Regional tion has been verified by study of the dispersal of indicator terranes in the NAC have gneisses with zircon components in this minerals from kimberlites in the surrounding surface environ- age range16,17. A minor age component at 3.2 Ga in samples 8 ment14. The 0.1–1 mm grain size fraction of the stream sediment and 9 is consistent with the age of diorite in the southern part of was used for zircon separation. A limited amount of each sample the area (Fig. 1; ref. 18). was available (30–50 g). Hence, to ensure a statistically robust There is a significant proportion of 3.8–3.6 Ga detritus in one number of zircon grains, ~120 g of material was produced by sample (~9%, sample 12), with other samples also showing minor combining 2–4 individual samples from closely spaced catchment proportions of Eoarchean-to-Paleoarchean components (Fig. 3 systems (Fig. 1). Ten resulting composited stream sediment and Supplementary Table 1). Zircon grains >3.2 Ga are rare in the samples were analyzed for U-Pb (Supplementary Data 1) and Lu- Mesoarchean part of the northern NAC; understanding the Hf isotopes (Supplementary Data 2). Reference material values nature of this detritus has significant implications for the earliest are provided in Supplementary Data 3. history and construction of the NAC. The restricted catchment Most zircon grains have rounded terminations consistent with that these samples were acquired from implies a source endemic sedimentary transport. Cathodoluminescence (CL) images are to the NAC. Dated crystalline rocks 25 km east of sample 12, dominated by textures characteristic of primary magmatic genesis at Qarliit Tasersuat, contain similar Neoarchean and Eo- including oscillatory zoning (Fig. 2 and Supplementary Data 4). Palaeoarchean zircon age components19,20. The most feasible 10 - 82: a 2 - 29: b 13b - 39: 3859 ± 41 Ma 3439 ± 42 Ma 3230 ± 40 Ma εHf = +1.0 ± 1.1 10 - 47: (t) εHf(t) = –5.3 ± 0.9 3599 ± 40 Ma εHf(t) = –8.6 ± 1.2 εHf(t) = –2.7 ± 1.4 ca. 3.2 Ga ca. 3.9–3.4 Ga 12 - 61: 3710 ± 46 Ma εHf = –0.2 ± 1.3 9 - 93: 9 - 18: (t) 3246 ± 122 Ma 3200 ± 56 Ma εHf = +4.3 ± 0.9 (t) εHf(t) = +0.5 ± 1.3 c 3 - 96: d 3013 ± 49 Ma 10 - 29: εHf(t) = –1.3 ± 1.1 2715 ± 42 Ma 2 - 19: 2659 ± 84 Ma εHf(t) = –3.7 ± 1.0 εHf(t) = –16.2 ± 0.8 ca. 2.90–2.65 Ga ca. 3.10–2.90 Ga 11 - 41: 5 - 51: 2 - 50: 3002 ± 59 Ma 2920 ± 45 Ma 2699 ± 63 Ma εHf(t) = –14.2 ± 1.1 εHf(t) = +1.3 ± 1.1 εHf(t) = –3.4 ± 1.0 e 10 - 2: 13 - 14: f 11 - 54: 2595 ± 55 Ma 2578 ± 54 Ma 1849 ± 70 Ma εHf = –6.1 ± 1.1 εHf = –15.9 ± 0.9 (t) εHf(t) = –4.3 ± 0.8 (t) ca.