Figures and Tables

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Introduction

The reconstruction of geological processes on early Earth that can be extended to a proper understanding of planetary differentiation requires large and diverse geochemical data sets of the oldest rock record. In recent years, the composition of Hadean mantle domains preserved under Eo- to Paleoarchean cratons and their compositional heterogeneity have been revealed by compilations of long lived (¹⁷⁶Lu-¹⁷⁶Hf, ¹⁴⁷Sm-¹⁴³Nd, ¹⁸⁷Re-¹⁸⁷Os) and short lived (¹⁸²Hf-¹⁸²W, ¹⁴⁶Sm-¹⁴²Nd; Willbold et al., 2011

Willbold, M., Elliott, T., Moorbath, S. (2011) The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment. Nature 477, 195–198. https://doi.org/10.1038/nature10399

; Morino et al., 2017

Morino, P., Caro, G., Reisberg, L., Schumacher, A. (2017) 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 and Planetary Science Letters 463, 136–150. https://doi.org/10.1016/j.epsl.2017.01.044

) isotope data. The Hf-W system, in particular, can provide insights into both the earliest silicate or metal-silicate differentiation, due to the short half-life (8.9 Myr; Vockenhuber et al., 2004

Vockenhuber, C., Oberli, F., Bichler, M., Ahmad, I., Quitté, G., Meier, M., Halliday, A.N., Lee, D.-C., Kutschera, W., Steier, P., Gehrke, R.J., Helmer, R.G. (2004) New Half-Life Measurement of ¹⁸²Hf: Improved Chronometer for the Early Solar System. Physical Review Letters 93, 172501. https://doi.org/10.1103/PhysRevLett.93.172501

) and contrasting incompatibilities during melting due to their lithophile (Hf) versus siderophile (W) affinities (e.g., König et al., 2011

König, S., Münker, C., Hohl, S., Paulick, H., Barth, A.R., Lagos, M., Pfänder, J., Büchl, A. (2011) The Earth’s tungsten budget during mantle melting and crust formation. Geochimica et Cosmochimica Acta 75, 2119–2136. https://doi.org/10.1016/j.gca.2011.01.031

).

The ¹⁸²Hf-¹⁸²W isotope system has been applied to trace Earth’s accretion, terrestrial core formation and addition of a late veneer to Earth (Kleine et al., 2002

Kleine, T., Münker, C., Mezger, K., Palme, H. (2002) Rapid accretion and early core formation on asteroids and the terrestrial planets from Hf–W chronometry. Nature 418, 952–955. https://doi.org/10.1038/nature00982

; Willbold et al., 2011

Willbold, M., Elliott, T., Moorbath, S. (2011) The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment. Nature 477, 195–198. https://doi.org/10.1038/nature10399

). The variability of ¹⁸²W/¹⁸⁴W ratios relative to the modern mantle (expressed in parts per million as μ¹⁸²W) in terrestrial Archean rocks has been explained by different hypotheses that consider early silicate differentiation during the lifetime of ¹⁸²Hf (Rizo et al., 2016

Rizo, H., Walker, R.J., Carlson, R.W., Touboul, M., Horan, M.F., Puchtel, I.S., Boyet, M., Rosing, M.T. (2016) Early Earth differentiation investigated through ¹⁴²Nd, ¹⁸²W, and highly siderophile element abundances in samples from Isua, Greenland. Geochimica et Cosmochimica Acta 175, 319–336. https://doi.org/10.1016/j.gca.2015.12.007

; Touboul et al., 2012

Touboul, M., Puchtel, I.S., Walker, R.J. (2012) ¹⁸²W Evidence for Long-Term Preservation of Early Mantle Differentiation Products. Science 335, 1065–1069. https://doi.org/10.1126/science.1216351

; Tusch et al., 2022

Tusch, J., Hoffmann, J.E., Hasenstab, E., Fischer-Gödde, M., Marien, C.S., Wilson, A.H., Münker, C. (2022) Long-term preservation of Hadean protocrust in Earth’s mantle. Proceedings of the National Academy of Sciences 119, e2120241119. https://doi.org/10.1073/pnas.2120241119

) or incomplete homogenisation of an isotopically heterogeneous early mantle (Willbold et al., 2011

Willbold, M., Elliott, T., Moorbath, S. (2011) The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment. Nature 477, 195–198. https://doi.org/10.1038/nature10399

). Coupled and decoupled μ¹⁸²W-μ¹⁴²Nd isotope compositions (active for the ∼50 and ∼500 Ma of Earth history) from ancient rocks from well studied areas such as the North Atlantic, Pilbara and Kaapvaal cratons and the Canadian Shield (e.g., Tusch et al., 2021

Tusch, J., Münker, C., Hasenstab, E., Jansen, M., Marien, C.S., Kurzweil, F., Van Kranendonk, M.J., Smithies, H., Maier, W., Garbe-Schönberg, D. (2021) Convective isolation of Hadean mantle reservoirs through Archean time. Proceedings of the National Academy of Sciences 118, e2012626118. https://doi.org/10.1073/pnas.2012626118

; Reimink et al., 2018

Reimink, J.R., Chacko, T., Carlson, R.W., Shirey, S.B., Liu, J., Stern, R.A., Bauer, A.M., Pearson, D.G., Heaman, L.M. (2018) Petrogenesis and tectonics of the Acasta Gneiss Complex derived from integrated petrology and ¹⁴²Nd and ¹⁸²W extinct nuclide-geochemistry. Earth and Planetary Science Letters 494, 12–22. https://doi.org/10.1016/j.epsl.2018.04.047

and references therein) have been used to postulate that these isotope variations represent a regional rather than a global signal.

This study reports the first μ¹⁸²W values of Paleo- to Mesoarchean igneous rocks from coeval greenstone belts and surrounding granitoid-tonalite trondhjemite granite (TTG) terranes in the western part of the Dharwar Craton, India, which are further compared with their W/Th ratios and stable W (δ^186/184W values) isotope ratios to estimate the influence of secondary W. These μ¹⁸²W values, combined with previously reported μ¹⁴²Nd values, provide constraints on early silicate mantle differentiation and its subsequent homogenisation with time. The isotope signatures elucidate the poorly understood processes of Hadean differentiation in the mantle sources of rocks from the Dharwar Craton. Furthermore, the combined ¹⁸²Hf-¹⁸²W and ¹⁴⁶Sm-¹⁴²Nd isotope systematics offer insights into the timing and extent of effective mixing over different timescales between early mantle source reservoirs and late accreted material(s) prior to the onset of modern plate tectonics.

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Results

The geological background of the western Dharwar Craton, India, and details of the samples taken for this study are presented in detail in the Supplementary Information (Fig. S-1, Table S-1).

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The protocols for W separation and the acquisition of isotope data (¹⁸²W and stable W) are described in the SI (Methods; Fig. S-2). The average μ¹⁸²W values of all samples of felsic, mafic and komatiitic compositions from the western Dharwar Craton are analytically unresolved relative to the W standard solution NIST^® SRM^® 3163 (Fig. 1a, Tables 1, S-2 and S-3) and display modern BSE-like μ¹⁸²W. Remarkably, the results for the Dharwar Craton stand in contrast to μ¹⁸²W values reported from other cratons worldwide, which generally show statistically significant heterogeneity (Fig. 1b) with positive and negative μ¹⁸²W relative to the modern BSE reference value. The modern BSE-like μ¹⁸²W for the samples from the western Dharwar Craton could be a primary isotope signature inherited from the mantle source or may be the result of late addition of W that modified their primary μ¹⁸²W signatures.

The δ^186/184W values of selected samples with high W/Th (Table S-4) range from −0.088 ± 0.018 ‰ to 0.264 ± 0.018 ‰ (Tables 1, S-5). The W abundances of samples range from 0.096 to 125 ppm (Table S-4). The geochemical trace element abundances of all samples taken for this study are presented in detail in the SI (Fig. S-3).

Sample	Age (Ma)a	182Hf-182W systematicsb			Elemental W	Stable W systematics	146Sm-142Nd systematicsc
		No. of measurements (n)	μ182W (6/4)d	μ182W (6/3)e	W/Th	δ186/184W ± 2 s.d. (‰)f	μ142Nd± 2 s.e.m.g
Felsic rocks
SG 34.1	3385±13	9	+1.6±2.2	−1.0±2.6	0.0262		+3.8±3.5
HNL 6.3	3200±18	11	−2.6±3.2	−5.5±2.9	0.0296		+0.5±2.3
HNL 6.1	3200	10	+1.9±3.6	−0.6±4.0	0.0564
GHH 22.4	3197±11	13	−1.8±1.9	−2.5±2.3	0.0274		+6.9±2.1
SG 29.1	3178±10						+2.1±2.1
SG 32.2	3163±10	9	−1.7±3.1	−3.8±4.1	0.0260		+5.7±3.7
SG 32.1	3160±12						+0.7±2.1
CHK 36.1	3049±21						+4.3±2.1
GHH 22.1	3026±26						+0.1±3.7
GHH 22.3	3010±25						+2.9±3.7
SG 30.3	3327±16	11	+1.2±3.2	+0.9±3.9	0.0356		−3.0±2.4
SG 30.2	3325±30						−4.5±2.8
replicate							−6.4±2.8
CHK 38.1	3335±20						−2.8±2.4
replicate							−5.6±2.8
Mafic and komatiitic rocks
GHH 19.2	3179±180	13	+1.4±3.0	+1.2±2.8			+2.3±2.4
replicate		24	−0.6±2.1	−1.7±2.0
GHH 20.2	3179±180	13	−0.4±2.5	−0.6±2.9	1562.5	+0.264±0.018	+2.7±2.4
replicate		25	−1.1±1.7	−1.1±1.9
SG 24.1	3179±180	14	+0.5±2.5	+1.8±2.6	5.23	+0.175±0.018	+4.1±2.7
SG 24.3	3179±180	12	+3.0±4.1	+2.2±3.7	0.138	+0.120±0.018	+2.4±2.8
BB 8.3	3244±10	8	−3.3±3.3	−4.2±6.0	1.65	−0.088±0.018	+1.1±2.4
BB 8.4	3244±10						+2.4±3.7
BB 8.5	3244±10	18	−0.4±2.1	−2.1±2.1	0.576	+0.187±0.018	+1.5±2.8
GHH 21.1	3179±180						+7.7±3.7
BB 37.5	2873±150						+2.3±2.8

^aU-Pb, Sm-Nd and Lu-Hf ages from Ravindran et al. (2021Ravindran, A., Mezger, K., Balakrishnan, S., Berndt, J. (2021) Hf-Nd isotopes from ultramafic and mafic rocks in the western Dharwar Craton, India, record early Archean mantle heterogeneity. Lithos 404–405, 106491. https://doi.org/10.1016/j.lithos.2021.106491, 2023)Ravindran, A., Mezger, K., Balakrishnan, S., Berndt, J., Ranjan, S., Upadhyay, D. (2023) Formation of Paleo- to Meso-Archean continental crust in the western Dharwar Craton, India: Constraints from U–Pb zircon ages and Hf-Pb-Sr isotopes of granitoids and sedimentary rocks. Chemical Geology 615, 121196. https://doi.org/10.1016/j.chemgeo.2022.121196.
^b182W isotope measurements from the current study.
^c142Nd isotope measurements compiled from Ravindran et al. (2024)Ravindran, A., Peters, B.J., Mezger, K., Hasenstab-Dübeler, E., Maya, J.M., Schönbächler, M. (2024) Distinct Hadean Mantle Sources of Felsic and Mafic Terranes Juxtaposed in the Paleoarchean. Geochemistry, Geophysics, Geosystems 25, e2024GC011834. https://doi.org/10.1029/2024GC011834.
^dMass-bias correction by ¹⁸⁶W/¹⁸⁴W = 0.92767.
^eMass-bias correction by ¹⁸⁶W/¹⁸³W = 1.9859.
^fUncertainties (2 s.d. = 0.018 ‰) based on long term external reproducibility of rock standard.
^gStandard Error of the Mean calculated from the average s.e.m. of standards.

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Discussion

The effect of secondary processes on μ ¹⁸² W. Globally, significantly large μ¹⁸²W anomalies were reported predominantly in Precambrian mafic to komatiitic rocks, often with variable W/Th ratios (Fig. 1b; see detailed description in SI). The felsic samples and one komatiitic sample from the Dharwar craton have mantle-like or near-canonical W/Th ratios (0.02–0.24; König et al., 2011

König, S., Münker, C., Hohl, S., Paulick, H., Barth, A.R., Lagos, M., Pfänder, J., Büchl, A. (2011) The Earth’s tungsten budget during mantle melting and crust formation. Geochimica et Cosmochimica Acta 75, 2119–2136. https://doi.org/10.1016/j.gca.2011.01.031

; Table 1), whereas the others display higher or supra-canonical W/Th, suggesting that they accumulated W after emplacement. With the exception of a few komatiites, the W/Th and W abundances of samples lie in the range of modern mantle and arc rocks (Fig. 2a). There is no correlation between the measured μ¹⁸²W and the measured concentrations of W and W/Th ratios of the samples, which is also the case for mafic-komatiitic rocks both with mantle-like (canonical) and variable W/Th (Fig. 2a,b). Additionally, the δ^186/184W values of the samples with high W/Th do not correlate with their respective μ¹⁸²W values (Fig. 2c), which likely reflect derivation from distinct processes (SI). The μ¹⁸²W values of serpentinised or enriched ultramafic rocks such as komatiitic rocks with non-canonical W/Th ratios (Fig. 2b, Tables S-1, S-4), likely resulting from W mineralisation at ca. 3.2 Ga (Fig. 2a; SI), are similar to that of the other samples. However, the δ^186/184W values of all these rocks are distinct from the modern mantle, clearly displaying evidence for metasomatism (Figs. 2c, S-4, SI; cf. Kurzweil et al., 2020

Kurzweil, F., Münker, C., Hoffmann, J.E., Tusch, J., Schoenberg, R. (2020) Stable W isotope evidence for redistribution of homogeneous ¹⁸²W anomalies in SW Greenland. Geochemical Perspectives Letters 14, 53–57. https://doi.org/10.7185/geochemlet.2024

).

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It can be noticed that the komatiite sample with a δ^186/184W value close to the Earth’s mantle (Fig. 2c) also has canonical W/Th (Fig. 2b), which could indicate that these proxies are connected, even though there is no correlation (Fig. 2d). The μ¹⁸²W value of this sample, however, is similar to that of the other samples possessing higher δ^186/184W and W/Th compared to the mantle. A correlation of μ¹⁸²W values of samples with their δ^186/184W values could be indicative of homogenisation of μ¹⁸²W irrespective of time, which is not visible among the samples from this study (Fig. 2c). Since all samples have very similar μ¹⁸²W values, it is unlikely that late addition of W modified the radiogenic ¹⁸²W compositions, and the metasomatising agents or surrounding granitoids (SI) thus must have had μ¹⁸²W values similar to the protolith with magmatic W/Th (Fig. S-4). This result supports an interpretation, where μ¹⁸²W values are robust signatures of the mantle source of the analysed rocks.

Origin of ¹⁸² W- ¹⁴² Nd decoupling. Some of the Archean cratons worldwide had undergone Hf/W fractionation from either magma ocean crystallisation, silicate differentiation or late accretion. Different amounts of added extraterrestrial components during the late veneer could create anomalous μ¹⁸²W in the Earth’s mantle (Willbold et al., 2011

Willbold, M., Elliott, T., Moorbath, S. (2011) The tungsten isotopic composition of the Earth’s mantle before the terminal bombardment. Nature 477, 195–198. https://doi.org/10.1038/nature10399

; Touboul et al., 2012

Touboul, M., Puchtel, I.S., Walker, R.J. (2012) ¹⁸²W Evidence for Long-Term Preservation of Early Mantle Differentiation Products. Science 335, 1065–1069. https://doi.org/10.1126/science.1216351

). The Eoarchean mantle sources of rocks from some cratons were interpreted to exhibit a missing late veneer signature (μ¹⁸²W average = +12.7 ± 1.2; cf. Tusch et al., 2021

Tusch, J., Münker, C., Hasenstab, E., Jansen, M., Marien, C.S., Kurzweil, F., Van Kranendonk, M.J., Smithies, H., Maier, W., Garbe-Schönberg, D. (2021) Convective isolation of Hadean mantle reservoirs through Archean time. Proceedings of the National Academy of Sciences 118, e2012626118. https://doi.org/10.1073/pnas.2012626118

). The rocks from the Dharwar Craton, however, show neither of these properties with no μ¹⁸²W anomalies relative to the modern mantle (Fig. 1b), which could imply that the mantle source of these rocks received the full late veneer component.

Alternatively, early variability of μ¹⁸²W in terrestrial rocks could result from early silicate differentiation of the Earth during the lifetime of ¹⁸²Hf. Early Hadean silicate differentiation (≥4.5 Ga) would result in depleted mantle domains with high Hf/W and Sm/Nd, and enriched domains with low Hf/W and Sm/Nd, resulting in a positive correlation between μ¹⁸²W and μ¹⁴²Nd values (e.g., Touboul et al., 2012

Touboul, M., Puchtel, I.S., Walker, R.J. (2012) ¹⁸²W Evidence for Long-Term Preservation of Early Mantle Differentiation Products. Science 335, 1065–1069. https://doi.org/10.1126/science.1216351

). Due to the core affinity of W compared to Hf, addition of a core component with negative μ¹⁸²W to the mantle source (e.g., Brandon and Walker, 2005

Brandon, A.D., Walker, R.J. (2005) The debate over core–mantle interaction. Earth and Planetary Science Letters 232, 211–225. https://doi.org/10.1016/j.epsl.2005.01.034

; Archer et al., 2023

Archer, G.J., Budde, G., Worsham, E.A., Stracke, A., Jackson, M.G., Kleine, T. (2023) Origin of ¹⁸²W Anomalies in Ocean Island Basalts. Geochemistry, Geophysics, Geosystems 24, e2022GC010688. https://doi.org/10.1029/2022GC010688

) may also occur. However, neither of these isotope effects are observed in the rocks from the Dharwar Craton (Fig. 3a).

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In Figure 3, the μ¹⁴²Nd values of samples from the western Dharwar Craton (Ravindran et al., 2024

Ravindran, A., Peters, B.J., Mezger, K., Hasenstab-Dübeler, E., Maya, J.M., Schönbächler, M. (2024) Distinct Hadean Mantle Sources of Felsic and Mafic Terranes Juxtaposed in the Paleoarchean. Geochemistry, Geophysics, Geosystems 25, e2024GC011834. https://doi.org/10.1029/2024GC011834

) are plotted relative to their ¹⁴⁷Sm-¹⁴³Nd isotope systematics (Fig. 3b) and their emplacement ages (Fig. 3c). Overall, the μ¹⁴²Nd anomalies are small or negligible compared to the modern mantle (Fig. 3), aligning with those of some Paleo- to Mesoarchean rocks, but distinct from the ¹⁴²Nd anomalies recorded in Eoarchean rocks (μ¹⁴²Nd = −18 to +19.3; Fig. 3c). Figure 3b illustrates two distinct slopes in the combined ^146,147Sm-^142,143Nd isotope systematics, indicating two Hadean mantle differentiation events (Ravindran et al., 2024

Ravindran, A., Peters, B.J., Mezger, K., Hasenstab-Dübeler, E., Maya, J.M., Schönbächler, M. (2024) Distinct Hadean Mantle Sources of Felsic and Mafic Terranes Juxtaposed in the Paleoarchean. Geochemistry, Geophysics, Geosystems 25, e2024GC011834. https://doi.org/10.1029/2024GC011834

). Highly silicic and remelted granitoids of trondhjemitic composition from the craton (cf. Ravindran et al., 2023

Ravindran, A., Mezger, K., Balakrishnan, S., Berndt, J., Ranjan, S., Upadhyay, D. (2023) Formation of Paleo- to Meso-Archean continental crust in the western Dharwar Craton, India: Constraints from U–Pb zircon ages and Hf-Pb-Sr isotopes of granitoids and sedimentary rocks. Chemical Geology 615, 121196. https://doi.org/10.1016/j.chemgeo.2022.121196

) exhibit negative μ¹⁴²Nd values (Fig. 3b) in contrast to more positive μ¹⁴²Nd in other samples. The different μ¹⁴²Nd values reflect different ages of previous mantle extraction events, also suggesting the possible presence of an enriched Hadean reservoir that differentiated in the Hadean, possibly by ∼4.38 Ga.

The observed decoupling of μ¹⁸²W and μ¹⁴²Nd in other cratons was suggested to be due to a missing late veneer (Tusch et al., 2019

Tusch, J., Sprung, P., van de Löcht, J., Hoffmann, J.E., Boyd, A.J., Rosing, M.T., Münker, C. (2019) Uniform ¹⁸²W isotope compositions in Eoarchean rocks from the Isua region, SW Greenland: The role of early silicate differentiation and missing late veneer. Geochimica et Cosmochimica Acta 257, 284–310. https://doi.org/10.1016/j.gca.2019.05.012

), addition of a restite component extracted from a Hadean protocrust that had formed right after magma ocean solidification (Tusch et al., 2022

Tusch, J., Hoffmann, J.E., Hasenstab, E., Fischer-Gödde, M., Marien, C.S., Wilson, A.H., Münker, C. (2022) Long-term preservation of Hadean protocrust in Earth’s mantle. Proceedings of the National Academy of Sciences 119, e2120241119. https://doi.org/10.1073/pnas.2120241119

), or crystal-liquid fractionation in an early magma ocean (Puchtel et al., 2016

Puchtel, I.S., Blichert-Toft, J., Touboul, M., Horan, M.F., Walker, R.J. (2016) The coupled ¹⁸²W-¹⁴²Nd record of early terrestrial mantle differentiation. Geochemistry, Geophysics, Geosystems 17, 2168–2193. https://doi.org/10.1002/2016GC006324

). All these models are unlikely for the Dharwar Craton due to the BSE-like μ¹⁸²W and anomalous μ¹⁴²Nd. The most likely explanation is protracted silicate differentiation before or after ¹⁸²Hf was extinct.

Modern mantle-like μ ¹⁸² W signatures in Dharwar rocks. Archean felsic and basaltic-komatiitic rocks from the Dharwar Craton have modern mantle-like μ¹⁸²W values, but also record Sm/Nd fractionation at ∼4.38 Ga, likely from a chondritic reservoir (Bouvier and Boyet, 2016

Bouvier, A., Boyet, M. (2016) Primitive Solar System materials and Earth share a common initial ¹⁴²Nd abundance. Nature 537, 399–402. https://doi.org/10.1038/nature19351

). The absence of μ¹⁸²W variations in the rocks from the Dharwar Craton could be (1) due to late silicate differentiation after the life time of ¹⁸²Hf (after ca. 4.5 Ga) or (2) due to early Hf/W fractionation (≥4.5 Ga) erased by re-homogenisation of the source material before Sm/Nd fractionation at ∼4.38 and ∼4.15 Ga. A vigorous homogenisation of the mantle by rapid stirring, as a result of high mantle temperatures, or meteorite bombardment immediately after early silicate differentiation in the magma ocean was suggested recently (e.g., Marchi and Korenaga, 2025

Marchi, S., Korenaga, J. (2025) The shaping of terrestrial planets by late accretions. Nature 641, 1111–1120. https://doi.org/10.1038/s41586-025-08970-8

; Rosas and Korenaga, 2018

Rosas, J.C., Korenaga, J. (2018) Rapid crustal growth and efficient crustal recycling in the early Earth: Implications for Hadean and Archean geodynamics. Earth and Planetary Science Letters 494, 42–49. https://doi.org/10.1016/j.epsl.2018.04.051

). Alternatively, homogenising the mantle within the first 100 Myr of Earth history has been considered less likely if stirring of the Hadean mantle was sluggish, for example if the upper depleted mantle layer was too thin to allow mantle overturns and mixing, and thereby homogenisation (e.g., Bédard, 2018

Bédard, J.H. (2018) Stagnant lids and mantle overturns: Implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geoscience Frontiers 9, 19–49. https://doi.org/10.1016/j.gsf.2017.01.005

). Only after the period of possible massive bombardment (i.e. after ≥4.1 Ga) did the Earth probably become stable enough to simultaneously maintain different geodynamic modes (e.g., Bédard, 2018

Bédard, J.H. (2018) Stagnant lids and mantle overturns: Implications for Archaean tectonics, magmagenesis, crustal growth, mantle evolution, and the start of plate tectonics. Geoscience Frontiers 9, 19–49. https://doi.org/10.1016/j.gsf.2017.01.005

).

Variations in μ¹⁸²W and μ¹⁴²Nd in the global record (Figs. 1b, 3c) suggest that early silicate differentiation in the early Hadean (>4.5 Ga) could have fractionated both Sm/Nd and Hf/W. However, uniform, BSE-like μ¹⁸²W sustained in Paleo-Mesoarchean mantle derived melts and differentiated rocks from the Dharwar Craton indicate that this differentiation from the accessible rock record was not global, but rather local. Any effects of differentiation on the mantle source of the rock suites from the Dharwar Craton is not directly visible. This implies that parts of the mantle remained untouched and others had distinct differentiation histories following core formation (cf. Boukaré et al., 2025

Boukaré, C.-É., Badro, J., Samuel, H. (2025) Solidification of Earth’s mantle led inevitably to a basal magma ocean. Nature 640, 114–119. https://doi.org/10.1038/s41586-025-08701-z

).

Progressive post-Hadean homogenisation of the mantle is evident in a loss of anomalous ¹⁴²Nd signals during the Paleo-Mesoarchean and their absence in ∼2.0 Ga old mantle derived rocks (e.g., Puchtel et al., 2025

Puchtel, I.S., Hellmann, J.L., Rizo, H., Blichert-Toft, J., Stepanova, A.V., Samsonov, A.V., Walker, R.J. (2025) Bulk silicate Earth-like ¹⁴²Nd and ¹⁸²W mantle component sampled by 2.0 Ga Onega Basin picrites, Fennoscandia. Geochimica et Cosmochimica Acta 393, 133–154. https://doi.org/10.1016/j.gca.2025.01.013

). This contrasts with μ¹⁸²W variability that persists throughout geological history, even until present day in the sources of OIBs (cf., Archer et al., 2023

Archer, G.J., Budde, G., Worsham, E.A., Stracke, A., Jackson, M.G., Kleine, T. (2023) Origin of ¹⁸²W Anomalies in Ocean Island Basalts. Geochemistry, Geophysics, Geosystems 24, e2022GC010688. https://doi.org/10.1029/2022GC010688

; e.g., Deccan Traps, Pakulla et al., 2025

Pakulla, J.J., Tusch, J., Hasenstab-Dübeler, E., Ravindran, A., Jansen, M.W., Leitzke, F.P., Gadpallu, P., Duraiswami, R.A., Münker, C. (2025) The spatio-temporal evolution of ¹⁸²W and ¹⁴²Nd in the Deccan-La Réunion plume. Earth and Planetary Science Letters 653, 119225. https://doi.org/10.1016/j.epsl.2025.119225

). This apparent decoupling of μ¹⁴²Nd and μ¹⁸²W (SI) implies that the radiogenic ¹⁸²W variability in Phanerozoic lavas is likely the result of more recent contributions of ¹⁸²W to the mantle, possibly by addition of core, late veneer or proto-crust materials.

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Conclusions

The μ¹⁸²W values of rocks from the Dharwar Craton are some of the oldest reported rocks with modern BSE-like signatures, which implies that ancient and younger juvenile material from the region was derived from a mantle source that did not preserve any evidence for magma ocean crystallisation or other silicate differentiation events within the lifetime of ¹⁸²Hf. The uniform BSE-like μ¹⁸²W of rocks from the Dharwar Craton contrasts with contemporaneous or slightly older rocks from other Archean terranes (3.6–3.2 Ga; Tusch et al., 2021

Tusch, J., Münker, C., Hasenstab, E., Jansen, M., Marien, C.S., Kurzweil, F., Van Kranendonk, M.J., Smithies, H., Maier, W., Garbe-Schönberg, D. (2021) Convective isolation of Hadean mantle reservoirs through Archean time. Proceedings of the National Academy of Sciences 118, e2012626118. https://doi.org/10.1073/pnas.2012626118

; Mei et al., 2020

Mei, Q.-F., Yang, J.-H., Wang, Y.-F., Wang, H., Peng, P. (2020) Tungsten isotopic constraints on homogenization of the Archean silicate Earth: Implications for the transition of tectonic regimes. Earth and Planetary Science Letters 278, 51–64. https://doi.org/10.1016/j.gca.2019.07.050

; Leitzke et al., 2024

Leitzke, F.P., Pakulla, J.J., Tusch, J., Ravindran, A., Gordilho-Barbosa, R., Zincone, S.A., Hellers, M., Martins, A.A., Spreafico, R.R., Yang, R., Wombacher, F., Barbosa, J.S.F., Münker, C. (2024) Evidence for a missing late veneer from ¹⁸²W and ¹⁴²Nd systematics in the Archean São Francisco Craton. Earth and Planetary Science Letters 647, 119022. https://doi.org/10.1016/j.epsl.2024.119022

) that exhibit either positive or negative μ¹⁸²W linked to early silicate differentiation or a missing late veneer contribution, neither of which is evident in the source rocks of the Dharwar Craton. Therefore, these rock suites either escaped both processes negating mantle-wide differentiation or survived a rapid early Hadean homogenisation, and show that domains with modern BSE-like μ¹⁸²W were already present early in the geological record. Collectively, our findings highlight that early mantle differentiation and homogenisation were spatially heterogeneous processes, and that not all mantle reservoirs followed a uniform evolutionary trajectory following core formation (SI). The Dharwar Craton thus represents a unique archive of early mantle evolution, underscoring the importance of regional studies in reconstructing the complexities of early Earth history.

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Acknowledgements

We thank Prof. S. Balakrishnan for assistance during field work in Karnataka, India and Maya J.M for contributing samples that were used for constructing the ¹⁴²Nd-¹⁴³Nd isochron. We are also grateful to Manuela Fehr for providing help during method development at ETH Zurich and to Mario Fischer-Gödde for assistance during MC-ICPMS measurement sessions at University of Cologne. We also thank Xiaoyu Zhou, Niklas Kallnik and Tristan Bongartz for assistance in the Cologne lab during W isotope work. Funding for this study was provided by Alexander von Humboldt and Swiss National Science Foundation (SNSF) Mobility Fellowships awarded to AR, a SNSF Ambizione fellowship to BJP (PZ00P2_186064), a SNSF project (200021_208079) to MS and by ETH Zürich. We are grateful to the two reviewers for their constructive comments, which improved the manuscript significantly. We also thank the Editor Helen Williams for her insightful suggestions that further polished the manuscript.

Editor: Helen Williams

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References

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Supplementary Information

The Supplementary Information includes:

• Geological Background
• Methods
• Trace Element Abundances
• Effects of Secondary W
• Hadean Mantle Heterogeneities
• Tables S-1 to S-6
• Figures S-1 to S-4
• Supplementary Information References

Download the Supplementary Information (PDF)

Download Tables S-2 to S-4 (xlsx)