A billion-year shift in the formation of Earth’s largest ore deposits
Edited by Kenneth Farley, California Institute of Technology, Pasadena, CA; received March 20, 2024; accepted June 18, 2024
Significance
The Earth’s largest and most economically significant iron deposits (Pilbara Craton, Western Australia) have been directly dated, revealing that they are up to a billion years younger than previously estimated. They also appear to have formed within a geological timeframe that coincided with the breakup and formation of supercontinents. It is thought that the trigger for this mineralizing event operated at the scale of an entire craton, when plate amalgamation and formation of a supercontinent provided the appropriate energy, hydrothermal fluid flow, and focus across the entire region.
Abstract
Banded iron formations (BIFs) archive the relationship between Earth’s lithosphere, hydrosphere, and atmosphere through time. However, constraints on the origin of Earth’s largest ore deposits, hosted by BIFs, are limited by the absence of direct geochronology. Without this temporal context, genetic models cannot be correlated with tectono-thermal and atmospheric drivers responsible for BIF upgrading through time. Utilizing in situ iron oxide U–Pb geochronology, we provide a direct timeline of events tracing development of all the giant BIF-hosted hematite deposits of the Hamersley Province (Pilbara Craton, Western Australia). Direct dating demonstrates that the major iron ore deposits in the region formed during 1.4 to 1.1 Ga. This is one billion to hundreds of millions of years later than previous age constraints based upon 1) the presence of hematite ore clasts in conglomerate beds deposited before ~1.84 Ga, and 2) phosphate mineral dating, which placed the onset of iron mineralization in the Province at ~2.2 to 2.0 Ga during the great oxidation event. Dating of the hematite clasts verified the occurrence of a ~2.2 to 2.0 Ga event, reflecting widespread, but now largely eroded iron mineralization occurring when the Pilbara and Kaapvaal cratons were proximal. No existing phosphate mineral dates overlap with obtained hematite dates and therefore cannot be related to hematite crystallization and ore formation. New geochronology conclusively links all major preserved hematite deposits to a far younger (1.4 to 1.1 Ga) formation period, correlated with the amalgamation of Australia following breakup of the Columbia supercontinent.
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Banded iron formations (BIFs) form through the deposition of iron species oxidized in the water column and therefore represent a deep time record of the ancient interplay between the hydrosphere, atmosphere, and lithosphere (1, 2). Postdepositional BIF oxidation via hydrothermal and supergene fluid-driven upgrading processes that sequentially remove silica and carbonate and oxidize iron is required to form iron ore, a foundational commodity for society. The timing and cause of these processes are enigmatic (3–5) and compounded by indirect temporal constraints (6–8), which were recently challenged by hematite geochronology (9). New developments in iron oxide U–Pb geochronology allows direct, robust dating of iron ore, which can resolve fundamental questions relating to when and why mineralization occurred at cratonic scales (10).
In the Hamersley Province of the Pilbara Craton (Western Australia), the Archean Marra Mamba and Archean to earliest Proterozoic Brockman Iron Formations host numerous martite–microplaty hematite deposits (Fe > 64 wt%), where “martite” refers to the pseudomorphic replacement of magnetite by hematite and “microplaty” refers to a texture of hematite. The timing of iron upgrading in these BIFs was first inferred from the presence of widespread hematite ore clasts within conglomerate beds in the western Hamersley Range, which were believed to be derived from the major hematite deposits in the region based on comparable mineralogy and texture (Fig. 1). The overlying bimodal June Hill volcanics constrain the age of these conglomerate beds and their contained hematite clasts to >1.84 Ga (3, 7). Subsequent U–Pb dating of 40 xenotime and 5 monazite grains associated with microplaty hematite at only the Mt. Tom Price deposit revealed that eight phosphate generations were precipitated broadly between ca. 2.15 and 0.85 Ga. These were indirectly linked to multiple cycles of microplaty hematite mineralization over the same timescale (8).
Fig. 1.
We build on a previous study from the Chichester Range (9), which showed that the Marra Mamba BIF hosting distinct Cenozoic martite-goethite ores contained pockets of higher grade (>60% wt% Fe) martite-microplaty hematite, which were dated at 1.26 to 1.22 Ga. Furthermore, nanoscale transmission electron microscopy on microplaty hematite and martite showed that U and Pb were lattice bound and not hosted as inclusions as might be expected, whereas low T (U–Th)/He thermochronology revealed broad cratonic denudation between 0.57 and 0.38 Ga. Conversely, here we present a new U–Pb dataset from seven locations, including all major hematite deposits (i.e., Mt. Whaleback, Mt. Tom Price, Paraburdoo) found in the Brockman Iron Formation within the Hamersley Province, Western Australia.
This represents the broadest study of geochronology from the Hamersley Province, and the only direct dating of ore from these deposits. We report U–Pb ages for hematite ore clasts from conglomerate beds, confirming indeed the occurrence of an early, ~2.2 to 2.0 Ga period of iron ore upgrading, which could be genetically linked with iron ore locations in South Africa that were directly associated with the 2.06 Ga Bushveld superplume event (11). However, results from 235 individual hematite spot analyses also provide direct, reproducible dates of an upgrading event that took place several hundred million years later. In fact, all hematite samples yield intercept dates between 1.1 and 1.4 Ga, with hematite from three different areas of the Mt. Tom Price deposit yielding a relatively precise intercept date at 1387 ± 30 Ma (n = 105). Conversely, no xenotime or monazite dates are recorded in this timeframe but are recorded several hundred million years later at ~0.85 Ga.
These data provide the first direct temporal constraints on the genesis of the Hamersley metallogenic camp, which is one of the largest hydrothermal ore systems on the planet. The two recorded periods of iron enrichment in the Hamersley Province (at 2.2 to 2.0 and 1.4 to 1.1 Ga) can be correlated with iron mineralization elsewhere in the world and are confined to periods of supercontinent assembly and breakup. Given the size of the multiple world-class iron deposits that are concentrated here, it is necessary to envisage that the trigger for this mineralizing event operated at the craton scale, when plate amalgamation and formation of a supercontinent provided the appropriate energy, hydrothermal fluid flow, and focus across the entire region (12). The interplay between tectonic cycles and iron mineralization is demonstrated using unique, direct geochronology, which redetermines the origins of high-grade ores in Earth’s largest iron ore province.
Results
Samples.
Eight samples were collected from outcrops and diamond drill cores intersecting two conglomerate beds hosting hematite ore clasts (Mt. McGrath Formation and Three Corner Bore; Fig. 2 A and B) and four operating hematite mines all hosted within the Brockman Iron Formation, which hosts most of the mineralization in the region (Figs. 1 and 2 C–H). These deposits differ from previous hematite age constraints from the Chichester Ranges deposit (9), which is hosted by the Marra Mamba Iron Formation and is distinct in mineralization grade, economic significance, style, and location to the systems in the Brockman Iron Formation. We also report on one distinctive sample of granoblastic hematite from the Channar iron deposit (Fig. 2G), which has clearly been recrystallized by contact metamorphism via an intruding gabbroic dike. The U–Pb zircon age from the nearby dike is 750 ± 10 Ma (3) and represents an independent test for the accuracy of the hematite dates presented in this study. Altogether, the sample set is a representative collection of martite-microplaty hematite mineralization across the Hamersley Province (Figs. 1 and 2).
Fig. 2.
Hematite U–Pb Geochronology.
All U–Pb Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) sample dates are presented as lower intercepts on Tera-Wasserburg diagrams (Fig. 3). Each diagram contains an inset of an optical photomicrograph showing the location of U–Pb LA–ICP–MS spot locations within martite-microplaty hematite grains and aggregates, as detailed below:
•
Hematite ore clasts (Fig. 3 A and B): Samples are U poor but clearly form Paleoproterozoic intercept trajectories within the expected 2.2 to 2.0 Ga period;
•
Giant hematite deposits (Fig. 3 C–E): All samples are far more radiogenic than the ore clasts and all define clear Mesoproterozoic trajectories between ~1.4 and ~1.1 Ga. At Mt. Tom Price (Fig. 2C), three separate samples from different locations in the deposit have been amalgamated into one diagram. Individual location intercepts are SE Prongs = 1377 ± 49 Ma (n = 50; MSWD = 3.5); S Ridge Deep = 1398 ± 55 Ma (n = 33; MSWD = 2.6) and S Ridge = 1171 ± 137 Ma (n = 22; MSWD = 1.1). The combined intercept date for all samples is 1387± 30 Ma (n = 105, MSWD = 3.8).
•
Metamorphosed hematite ore (Fig. 3F): This sample from the Channar deposit was the most radiogenic, providing a near concordant date. Lower U analyses with large uncertainties cloud the lower intercept, so a weighted mean from the individual 206Pb/238U dates is preferred at 744.4 ± 8.8/25.3 Ma (n = 26; MSWD = 8.3).
Fig. 3.
Discussion
Age, Origin, and Evolution of the Hamersley Province Hematite Deposits.
BIFs in the Pilbara and Kaapvaal cratons share a common stratigraphy, formed between 2.60 and 2.45 Ga as they were proximal during deposition (1) on the margins of an apparent supercontinent named Vaalbara/Superior [(13); Fig. 4]. This supercontinent began to break up at ~2.2 Ga (14), with the separation of the Kaapvaal and Pilbara cratons by ~2.0 Ga (15). As eroded ore-grade clasts occur within conglomerate beds in the Pilbara (Fig. 3 A and B) and within the Waterberg Group in South Africa (16), where hematite ore clasts are mineralogically and geochemically comparable to those found in the nearby Thabazimbi hematite deposit (17), data from this study indeed confirm the hypothesis that both cratons did host hematite ore mineralization at ~2.0 Ga. Together with other types of magmatic-hydrothermal mineralizing events that formed in the same timeframe that are found in both the Kaapvaal and Pilbara, as well as in the adjacent Yilgarn cratons, it has been previously proposed that they may be genetically linked to the emplacement of the ~2.06 Bushveld large igneous province (11).
Fig. 4.
Data from this study indicate that a second and more economically important phase of hematite iron ore mineralization is recorded within the Pilbara Craton in a time window between ~1.4 and 1.1 Ga (Fig. 4). However, unlike the localized ~2.0 Ga event recorded by the widespread occurrence of hematite ore clasts, which was potentially associated with the breakup of Vaalbara and the influence of the Bushveld large igneous province, this Mesoproterozoic event was most likely associated with the assembly of another supercontinent, when the north, south, and west Australian cratons amalgamated to form Rodinia (23).
Hematite sampled across different deposits all fall between the 1.4 to 1.1 Ga time interval, with samples yielding individual intercepts at 1.1, 1.17, 1.29, 1.38, and 1.4 Ga. This spread in dates implies temporal variations across both the region and within individual deposits. However, the low precision and high common Pb coupled with low U contents of hematite samples means that although resolving individual events responsible for ore upgrading during 1.4 to 1.1 Ga may not be possible, there is nonetheless a strong indication that multiple mineralizing events may have occurred during this period. The large difference in observed initial U content between the conglomerates, BIF-hosted ore and metamorphosed samples are further evidence that the initial fluids may have had differing composition, resulting in hematite upgrading in different periods.
The most robust BIF-hosted ore dataset (i.e., the highest 238U/206Pb), which was all derived from samples collected at Mt. Tom Price, produced intercepts at 1377 ± 49 Ma and 1398 ± 55 Ma. Interestingly, the S ridge sample yields a younger date than the other two areas of the deposit (1171 ± 137 Ma), despite being texturally similar to material in S ridge deep. However, the uncertainty of this sample is large and contains the least spot analyses (n = 22) and therefore is more likely to be unreliable or inaccurate rather than robustly younger. The more robust dates from Mt. Tom Price at 1377 and 1398 Ma diverge significantly from that yielded by phosphate minerals previously dated at Mt. Tom Price, whereby 40 xenotime and 5 monazite grains were determined to have precipitated from 2.15 to 0.85 Ga (8). It should be noted that only ~30 of 40 analyzed grains were used in the age interpretation, and that ~five grains contained spots over 2 Ga (Fig. 3G). The stark difference between the dates recorded in iron oxide and accessory hydrothermal minerals demonstrates that phosphates and hematite are recording different events, as xenotime continued to precipitate ~450 Ma after hematite.
One line of argument to explain the difference in dates could be sampling of multiple hematite domains or mixtures of materials within the laser beam, or else a form of “mixing” of hematite U–Pb systematics whenever a new batch of fluid interacted with hematite. However, clear linear arrays for all samples all forming around the same time indicate that this cannot be the case. In fact, Tera-Wasserburg diagrams would appear scattered if fluid was constantly introducing or removing U and common Pb from individual grains. Furthermore, if the U–Pb systematics in hematite were entirely reset by new fluids, they would record the latest xenotime precipitation event at 0.85 Ga, but this is not the case.
What is more likely is that fluid was instead continuously dissolving and reprecipitating phosphate minerals, as reflected in Fig. 3G, whereby concordant xenotime dates smear along the concordia curve, and individual grains contain multiple spot analyses recording spreads of over 1 billion years (Fig. 3H). It is also important to stress that phosphorous (P) makes up at most 0.05% of studied orebodies (24); this figure includes P contained in apatite, which is a much more common accessory phase than xenotime, rendering its modal abundance within the ore insignificant. Xenotime was searched for in the specimens that were selected for U–Pb hematite analyses for age comparison, but none was observed in any of the samples used in this study.
Conversely, we suggest that the phosphate ages record events of dissolution of apatite in altered BIF, followed by continual cycles of reprecipitation and dissolution by infiltrating meteoric water during orogenic events (4, 25, 26). This hypothesis is supported by the fact that no xenotime dates overlap with any of the ages of hematite from the orebodies investigated in this study, and that from just 40 xenotime grains it is possible to outline such a large array of dates for up to eight separate “hydrothermal events.” It is well known that the U–Pb system in xenotime may be efficiently reset through fluid-mediated reactions, even at low temperature (27). Furthermore, the simple dissolution and reprecipitation of xenotime in iron oxide bearing–orebodies is not a new finding. This is also observed in the Olympic Dam iron oxide-Cu-Au province, whereby well-constrained hematite grains retain a primary age of 1590 Ma [relating to the ~1592 Ma host volcanics and granites; (28)], whereas coexisting phosphate minerals yield an array of younger dates within the same deposits (29), which are correlated with later hydrothermal events which could not reset primary hematite U–Pb systematics.
There are no constraints on the closure (resetting) temperature of the U–Pb system in hematite, although it is expected to be akin to magnetite [magnetite Pb closure T ∼ 550 °C; (30)]. Therefore, it is highly doubtful that the 1.4 to 1.1 Ga hematite U–Pb ages are the result of U–Pb isotope resetting during a high-T event. Moreover, there is no evidence of high-T events within the deposits or across the Hamersley Province between 1.4 to 1.1 Ga that could have induced high-T resetting of U–Pb isotope systematics (e.g., felsic or mafic intrusions and regional metamorphism). Furthermore, the presence of a younger ~0.85 Ga xenotime age recorded in Mt. Tom Price ores is not reflected in hematite ages, meaning that any fluid flow at this time responsible for precipitating xenotime could not have “reset” the hematite dates.
Finally, the clearly metamorphosed, recrystallized, and therefore U–Pb reset hematite from the Channar deposit (Fig. 3E) demonstrates that the hematite geochronometer is capable of yielding robust U–Pb dates, as the 744.4 ± 8 Ma hematite 206Pb/238U weighted mean age is indistinguishable from the 750 ± 10 Ma zircon age obtained on the proximal dike (3). We therefore suggest that the indirect dating of xenotime should not be considered a benchmark in defining the crystallization age of hematite ores across the entire Hamersley Province, as it is more likely that trace amounts of phosphates were added to iron ore deposits during various orogenic events, rather than billions of tons of hematite being U–Pb reset by cratonic scale hydrothermal events. The low n sample set derived from a single location in ref. 8 is likely a red herring, which is not genetically associated with hematite precipitation and therefore, iron ore formation.
It is however clear that the xenotime–monazite dates record the various orogenic events in the Pilbara Craton. These events are represented by strong deformation (mostly tight folding) in mineral deposits within the Hamersley Province. However, microplaty hematite ores never have a fabric associated with these events. In fact, microplaty hematite ores nearly uniformly lack a tectonic fabric, suggesting that they postdated all orogenic events that had some influence in the Hamersley basin, including the Ophthalmia (ca. 2200 to 2000 Ma) and Capricorn Orogenies (ca. 1800 to 1750 Ma). This also means that the older xenotime ages recorded at Mt. Tom Price are not associated with mineralization.
The Link between Iron Ore Genesis and Geodynamics.
Magmatic and hydrothermal mineral systems, enriched, for example, in copper, nickel, and platinum-group elements, have had their formation ascribed as cyclical and related to supercontinent cycles (e.g., ref. 31). The new hematite U–Pb dataset here indicates that it is possible to establish a direct link between the genesis of giant iron ore deposits and global geodynamics (32), which are necessary to create and focus the energy drivers, hydrothermal fluids and chemical gradients required to enrich billions of tons of rock to >64% Fe over cratonic scales. In this framework, the driver for the ~2.0 Ga mineralizing event recorded in the Kaapvaal and Pilbara cratons in the form of eroded ore-grade clasts within the Waterberg Group in the former (16) and within conglomerate beds in the latter (Fig. 3 A and B), may have been the emplacement of the Bushveld superplume (11), which most likely contributed to dismembering the Vaalbara supercontinent. In the case of the giant ore deposits in the Hamersley Province at ~1.4 to 1.1 Ga, the scenario is different. It is possible that the geodynamic framework that led to widespread mineralization in the Hamersley Province could have been associated with plate assembly (West and South Australian cratons and potentially the West and North Australian cratons) and not with breakup, which most likely happened prior to ~1.4 Ga in the area (23).
This inference raises the interesting possibility that microplaty hematite may have formed during compressional reactivation of older (normal) faults originated prior to the deposition of the lower Wyloo Group [Fig. 1 and (33, 34)]. One theory was that these faults were reactivated (extensionally) just prior to the deposition of the Mt. McGrath Formation (Fig. 1) but postemplacement of the 2008 Ma dikes, which are hydrothermally altered by hypogene processes that formed the proto-ores of the main deposits (3, 4, 7, 35). Conversely, the new dates presented in this study suggest that reactivation may have occurred much later, with the formation of the microplaty hematite in a compressional setting, during the ~1.4 to 1.1 Ga assembly of Rodinia. The uplift associated with the proposed geodynamic framework would support recently proposed multistage structurally controlled hydrothermal alteration models for the giant hematite deposits of the Pilbara Craton (3, 36, 37).
In this framework, an early hypogene hydrothermal event potentially related to extension would have been overprinted by supergene alteration, with coupled dissolution-transfer-precipitation involving rather cold, metal-diluted, meteoric water (25, 36). For meteoric water to penetrate down the fault zones, these rocks had to be exposed at or near to the surface. Hence, a genetic link with continent assembly and uplift is preferred here, although it is acknowledged that the breakup of the Nuna supercontinent at ~1.6 to 1.3 Ga largely coincides with the amalgamation of the West, South, and North Australian cratons into Rodinia (23) and the plate reorganization that followed this global series of events.
These very broad timescales and tectonic processes are invoked for ore formation and speculated upon. However, the take-home message stemming from the dataset is that all the largest hematite deposits in the Hamersley Province formed in a timeframe up to a billion years later than previously described. This implies that the main pulse of ore formation did not occur during the great oxidation event (2.42 to 2.06 Ga), but rather during the Mesoproterozoic (at 1.4 to 1.1 Ga), which is considered to be a period of environmental stasis with low levels of atmospheric oxygen (38) and orogenic quiescence (39). The large-scale tectonism and O2-rich environment necessary for the transformation of billions of tons of BIF into oxidized ore further supports a balanced, rather than boring billion years during the mid-Proterozoic (40), where environmental and tectonic conditions were conducive to large scale ore formation, reinforced by some of the world’s other largest iron oxide deposits, including the supergiant Olympic Dam iron-oxide Cu–Au deposit forming during this period (28). The identification that the formation of these giant iron oxide ore deposits correlates with changes in supercontinent cycle can contribute to the delineation of future predictive exploration targets through, focusing on BIFs primarily located near cratonic and lithospheric suture zones.
In conclusion, we present hematite U–Pb data from eight locations across the Pilbara Craton, demonstrating that iron ore mineralization formed over two major periods separated by around ~1 billion years. The first phase is preserved within ore-grade conglomerate pebble beds at 2.2 to 2.0 Ga, which represent a now long-eroded record of iron-enrichment processes, which can be traced across both the Pilbara and Kaapvaal cratons, where shared BIF stratigraphy and hematite conglomerate pebbles beds still exist. Such conglomerates were previously bracketed by minimum ~1.84 Ga zircon U–Pb ages and used to constrain the age of the giant hematite orebodies actively mined today across the Hamersley Province. The data shown in this investigation suggest that all major high-grade microplaty hematite iron ore deposits are unrelated to the >1.84 Ga Fe-enrichment event and are instead related to a broad but highly effective mineralizing period between ~1.4 and 1.1 Ga. Importantly, two major recognized periods of iron ore formation coincide with major periods of continental breakup and assembly, whereas the main iron enrichment episode across the Hamersley Province did not coincide with the great oxidation event.
Materials and Methods
All instruments used in this study are housed in the John de Laeter Centre, Curtin University, Perth. One-inch round polished blocks were imaged using reflected light microscopy. Laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS) U–Pb data were collected using a 193 nm RESOlution–LR excimer laser coupled to an Agilent 8900–QQQ ICP–MS. Data collection parameters followed those outlined in ref. 41. A spot diameter of 28 to 50 μm was employed depending on sample grain size allowances; MR-HFO (hematite) was the primary reference material for hematite normalization, with 91,500 (zircon), OG1 (zircon), and GJ–1 (zircon) used as secondary reference materials to assess instrument accuracy. Data were reduced using IOLITE (42) and presented with IsoplotR (43). All LA–ICP–MS U–Pb hematite and standard data can be found in SI Appendix, Table S1.
Data, Materials, and Software Availability
All study data are included in the article and/or SI Appendix.
Acknowledgments
This is a contribution to the “MRIWA 557” project supported by Bureau Veritas, BHP, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Fortescue Mining Group (FMG), Rio Tinto, Roy Hill, and Minerals Research Institute of Western Australia (MRIWA) and by the Australian Research Council through the Centre of Excellence for Core to Crust Fluid Systems (CE1100001017). Research in the GeoHistory Facility was enabled by AuScope (auscope.org.au) and the Australian Government via the National Collaborative Research Infrastructure Strategy. We thank Paulo Vasconcelos, an anonymous reviewer, and the editor for invaluable comments which greatly improved this manuscript.
Author contributions
L.C.-D., M.F., H.D., S.H., E.R., and B.I.A.M. designed research; L.C.-D., M.D., N.J.E., and K.R. performed research; L.C.-D., H.D., E.R., M.D., N.J.E., and B.I.A.M. contributed new reagents/analytic tools; L.C.-D., E.R., M.D., N.J.E., and K.R. analyzed data; and L.C.-D., M.F., H.D., S.H., and E.R. wrote the paper.
Competing interests
The authors declare no competing interest.
Supporting Information
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Copyright © 2024 the Author(s). Published by PNAS. This article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND).
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All study data are included in the article and/or SI Appendix.
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Received: March 20, 2024
Accepted: June 18, 2024
Published online: July 23, 2024
Published in issue: July 30, 2024
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Acknowledgments
This is a contribution to the “MRIWA 557” project supported by Bureau Veritas, BHP, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Fortescue Mining Group (FMG), Rio Tinto, Roy Hill, and Minerals Research Institute of Western Australia (MRIWA) and by the Australian Research Council through the Centre of Excellence for Core to Crust Fluid Systems (CE1100001017). Research in the GeoHistory Facility was enabled by AuScope (auscope.org.au) and the Australian Government via the National Collaborative Research Infrastructure Strategy. We thank Paulo Vasconcelos, an anonymous reviewer, and the editor for invaluable comments which greatly improved this manuscript.
Author contributions
L.C.-D., M.F., H.D., S.H., E.R., and B.I.A.M. designed research; L.C.-D., M.D., N.J.E., and K.R. performed research; L.C.-D., H.D., E.R., M.D., N.J.E., and B.I.A.M. contributed new reagents/analytic tools; L.C.-D., E.R., M.D., N.J.E., and K.R. analyzed data; and L.C.-D., M.F., H.D., S.H., and E.R. wrote the paper.
Competing interests
The authors declare no competing interest.
Notes
This article is a PNAS Direct Submission.
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A billion-year shift in the formation of Earth’s largest ore deposits, Proc. Natl. Acad. Sci. U.S.A.
121 (31) e2405741121,
https://doi.org/10.1073/pnas.2405741121
(2024).
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