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Due to the scarcity of rock samples, the Hadean Era predating 4 billion years ago (Ga) poses challenges in understanding geological processes like subaerial weathering and plate tectonics that are critical for the evolution of life. The Jack Hills zircon from Western Australia, the primary Hadean samples available, offer valuable insights into magma sources and tectonic genesis through trace element signatures. However, a consensus on these signatures has not been reached. To address this, we developed a machine learning classifier capable of deciphering the geochemical fingerprints of zircon. This allowed us to identify the oldest detrital zircon originating from sedimentary-derived "S-type" granites. Our results indicate the presence of S-type granites as early as 4.24 Ga, persisting throughout the Hadean into the Archean. Examining global detrital zircon across Earth's history reveals consistent supercontinent-like cycles from the present back to the Hadean. These findings suggest that a significant amount of Hadean continental crust was exposed, weathered into sediments, and incorporated into the magma sources of Jack Hills zircon. Only the early operation of both subaerial weathering and plate subduction can account for the prevalence of S-type granites we observe. Additionally, the periodic evolution of S-type granite proportions implies that subduction-driven tectonic cycles were active during the Hadean, at least around 4.2 Ga. The evidence thus points toward an early Earth resembling the modern Earth in terms of active tectonics and habitable surface conditions. This suggests the potential for life to originate in environments like warm ponds rather than extreme hydrothermal settings. [ABSTRACT FROM AUTHOR]

The recycling of subcontinental lithospheric mantle back into the asthenosphere during continental breakup is potentially a major but underappreciated process in plate tectonics. Here, we report major and trace elements for detrital peridotite minerals in carbonate breccias dredged from the Marion Rise, Southwest Indian Ridge. With an emphasis on the trace elements of the relatively abundant orthopyroxene detrital grains, the results show that a portion of pyroxene grains was likely derived from a mantle source that experienced hydrous melting and slab‐derived melt metasomatism above a subduction zone. This finding provides a novel view into the mantle geochemistry at midocean ridges, as well as evidence that Marion Rise is at least partially supported by chemically buoyant recycled refractory mantle wedge material. [ABSTRACT FROM AUTHOR]

True polar wander (TPW), or planetary reorientation, is the rotation of solid Earth (crust and mantle) about the liquid outer core in order to stabilize Earth's rotation due to mass redistribution. Although TPW is well-documented on Earth presently with satellites and for multiple planets and moons in the Solar System, the prevalence of TPW in Earth history remains contentious. Despite a history of controversy, both the physical plausibility of TPW on Earth and an empirical basis for it are now undisputed. Lingering resistance to the old idea likely stems from the fact that, like plate tectonics, TPW may influence much of the Earth system, thus acknowledging its existence requires rethinking how many different datasets are interpreted. This review summarizes the development of TPW as a concept and provides a framework for future research that no longer regards TPW like a ghost process that may or may not exist, but as an integral part of the Earth system that can relate shallow and deep processes that are otherwise only mysteriously linked. Specifically, we focus on the temporal regularity of large TPW, and discuss its relationship with the supercontinent–megacontinent cycle based on previous studies. We suggest the assembly of mega-continents has a close linkage to large TPW. Meanwhile, supercontinent tenure and breakup have a close linkage to fast TPW. The effects of TPW on sea level changes, paleoclimate, biological diversity, and other facets of the Earth system are presented and require interdisciplinary tests in the future. [ABSTRACT FROM AUTHOR]

Interpretation of Earth's oldest preserved crustal archive, the Jack Hills zircon of Western Australia, has been controversial in terms of the onset of plate tectonics. We conduct timeseries analysis on hafnium isotopes of the Jack Hills zircon and reveal an array of statistically significant cycles that are reminiscent of plate-tectonic subduction. At face value, such cycles may suggest early Earth conditions similar to those of today--the uniformitarian hypothesis that plate tectonics was essentially operational since "day one". On the other hand, in the context of expected secular changes due to planetary evolution and geological observations, the cycles could instead imply that modern plate-tectonic subduction inherited mantle convective harmonics already facilitated by an early phase of stagnant-lid delamination--the "lid-toplates" hypothesis. Either way, any model for the nature of plate tectonics must incorporate conditions operating during Hadean time, either by initiation of plate tectonics then or by later inheritance of preexisting cycles of mantle convection. [ABSTRACT FROM AUTHOR]

Since the Archean, secular change in orogenic style is demonstrated through evolution of metamorphic conditions and geochemical proxies. Linked to orogenic style is the amount of crustal thickening and elevation, whereas orogenic vigor is related to the supercontinent cycle. An array of Proterozoic orogens spanned the assembly of supercontinents Columbia and Rodinia, but the vigor of orogenesis is debated, with proposals for both Mesoproterozoic quiescence and climax. We show mid‐Proterozoic orogenesis occurred globally and was broadly continuous; furthermore, orogens exhibit elevated metamorphic thermobaric ratios with large volumes of high‐temperature felsic magmatic rocks. These features reflect higher mantle heat flux leading to increased mid‐crustal flow and lower elevation. In this context, proposals that geochemical proxies for crustal thickness record orogenic quiescence are inconsistent with the geological record. Alternatively, secular change in crustal thickness is attributed to orogenic style, namely the prevalence of hot, thin, and low orogens in the mid‐Proterozoic. Plain Language Summary: Orogenesis is the process whereby tectonic plates converge and mountain systems are created. In the case of the Andes and Himalayas, orogenesis resulted in significant thickening of the continental crust. Recent attempts to provide geochemical proxies for crustal thickness have allowed geologists to track the thickness of the crust through geologic time. One period of time in particular between 1850 and ∼850 million years ago—the mid‐Proterozoic—was characterized as having relatively thin crust. Some have argued this is evidence for a period of "orogenic quiescence." However, the geologic record is rife with ancient orogenic belts during this time as evidenced by the metamorphic and igneous rock records. In particular, the metamorphic rocks display higher than normal temperature/pressure ratios indicating unusually hot crust. We propose that the thin crust at this time is a product of high temperatures resulting in greater crustal flow and therefore lower mountain ranges. Key Points: The mid‐Proterozoic was characterized by unusually hot orogenesisElevated orogenic temperatures limited crustal thickening and promoted crustal flow and hinterland extensionSecular change in orogenic process explains independent estimates of variation in Proterozoic crustal thickness [ABSTRACT FROM AUTHOR]

True polar wander (TPW), or planetary reorientation, is well documented for other planets and moons and for Earth at present day with satellites, but testing its prevalence in Earth's past is complicated by simultaneous motions due to plate tectonics. Debate has surrounded the existence of Late Cretaceous TPW ca. 84 million years ago (Ma). Classic palaeomagnetic data from the Scaglia Rossa limestone of Italy are the primary argument against the existence of ca. 84 Ma TPW. Here we present a new high-resolution palaeomagnetic record from two overlapping stratigraphic sections in Italy that provides evidence for a ~12° TPW oscillation from 86 to 78 Ma. This observation represents the most recent large-scale TPW documented and challenges the notion that the spin axis has been largely stable over the past 100 million years. The authors present a high-resolution palaeomagnetic record for a Late Cretaceous limestone in Italy. They claim that their record robustly shows a ~12° true polar wander oscillation between 86 and 78 Ma, with the greatest excursion at 84–82 Ma. [ABSTRACT FROM AUTHOR]

Paleogeography can be reconstructed using various crust- or mantle-based reference frames that make fundamentally different assumptions. The various reconstruction models differ significantly in continental paleolongitude, but it has been difficult to assess which models are more valid. We suggest here a "LLSVP test", where an assumed correlation between present-day large low velocity shear-wave provinces and the paleogeography of supercontinent Pangea at breakup ca. 200 million years ago can be used to assess the relative accuracy of published reconstructions. Closest correlations between continental paleolongitude and the African LLSVP are achieved with mantle-based reference frames (moving hotspots and true polar wander), whereas shallower crust-based reference frames are shown to be invalid. The relative success of mantle-based frames, and thus the importance of the depth of reference frame, supports the notion that mantle convection is largely vertical compared to the horizontal plate motion of tectonics. Image 1 • Different reference frames for resolving continental paleolongitude are compared. • Lower mantle structures (LLSVPs) can be used to test between competing models. • Mantle-based references frames achieve better agreement with LLSVPs. [ABSTRACT FROM AUTHOR]

Charles Darwin suspected that the Cambrian "explosion" might be an artifact of fossil preservation. A more recent, initially controversial hypothesis that repeated true polar wander (TPW) triggered the Ediacaran-Cambrian explosion of animal life has been supported by numerous paleomagnetic and geochronologic refinements. These data imply ~75° of TPW between 535 and 515 million years ago, coinciding with the paleontologically observed rise in metazoan diversity and disparity. We show here that this evolutionary trend is explained simply by the well known ecology-driven increase of diversity in low latitudes, coupled by other ecological effects as well as the enhanced deposition of sedimentary rocks during TPW-driven sea-level transgressions. During the Cambrian TPW event, Laurentia and parts of Gondwanaland moved into the equatorial zone while experiencing local TPW-induced transgressions; these areas dominate the paleontological record of the time. Although diversity might thus be considered partly artifactual, TPW acted on Cambrian biogeography to increase net diversity; and enhanced rates of origination and extinction also could increase disparity, especially if Early Cambrian TPW occurred at a time when genetic regulatory networks were critically poised for expansion and exaptation. [ABSTRACT FROM AUTHOR]

Laurentia, the core of Paleo- to Mesoproterozoic supercontinent Nuna, has remained largely intact since assembly 2.0 to 1.8 billion years ago [Ga]. For earlier times, previous paleomagnetic data on poorly dated Paleoproterozoic mafic intrusions yielded ambiguous estimates of the amount of separation between key cratons within Nuna such as the Slave and Superior. Recent developments in paleomagnetism and U-Pb baddeleyite geochronology, including new results reported herein, yield sufficiently precise data to generate partial apparent polar wander paths for both the Slave and Superior craton from 2.2 to 2.0 Ga. Our new apparent polar wander comparison confirms earlier speculations that processes similar to plate tectonics, with relative motion between the Slave and Superior cratons, were operative leading up to the final assembly of supercontinent Nuna. [ABSTRACT FROM AUTHOR]

Hotspot tracks represent plate motions relative to mantle sources, and paleomagnetic data from magmatic units along those tracks can quantify motions of those mantle anomalies relative to the Earth's magnetic field and rotational axis. The Ediacaran Period is notable for rapid and large paleomagnetic apparent polar wander (APW) for many continents. Whereas magmatic units attributed to the "Sutton" mantle plume suggest a practically stationary hotspot track, paleolatitudes of Laurentia for that interval vary dramatically; geologic and paleomagnetic data are at odds unless true polar wander (TPW) is invoked to explain a majority of APW. Here we test the plume-TPW hypothesis by generating the predicted Sutton hotspot track for a stationary plume under a moving plate along the Laurentian margin during the interval from 615 to 530 Ma. Our model is the first to provide a kinematic framework for the extensive large igneous province associated with opening the Iapetus Ocean. [ABSTRACT FROM AUTHOR]

Based on the history of Mesozoic-Cenozoic plate motions, as well as simple dynamical considerations, a "speed limit" for tectonic plates has been suggested at ~20 cm/yr. Previous paleomagnetic data from the Early Cambrian of Gondwana are conflicting but generally imply rapid motions approaching that limit. Herein we describe results from a continuous paleomagnetic sampling of Lower to Middle Cambrian strata from the Amadeus Basin, central Australia. We find characteristic remanence directions that show an ~60° declination shift through the section. Assuming a tectonically assembled Gondwana supercontinent by Early Cambrian time, this large vertical-axis rotation of its Australian sector corresponds to an equally large translation across paleolatitudes for its Brazilian and West African sectors. Analysis of all high-quality paleomagnetic data from Gondwana both confirms and constrains the 60° rotation to have occurred toward the end of Early Cambrian time, at rates exceeding 16 +12/-8 cm/yr. These observations suggest that either nonuniformitarian plate tectonics or an episode of rapid true polar wander occurred during the Cambrian "explosion" of animal life. [ABSTRACT FROM AUTHOR]

The mechanism and timing of crustal growth and differentiation on early Earth are debated. Evidence of crustal differentiation is detectable as deviations from Earth's assumed chondritic uniform reservoir (CHUR) as crust is extracted from the mantle leading to a melt-depleted reservoir. For the long-lived zircon Lu-Hf system, no incontrovertible evidence of significant mantle depletion >3.8 Ga exists. We conduct combined U-Pb and Lu-Hf isotopic analyses for the detrital zircon from the Caozhuang supracrustal sequence in North China. The zircon Hf isotopic compositions are broadly scattered along the CHUR evolution line. However, given the possibility of potential systematic biases in zircon petrogenesis and the unique tectonic setting of early Earth, we posit that magmatism controlled by the nascent forms of plate tectonics during the Eoarchean could have likely hidden the degree of ancient crust-mantle differentiation. The non-depleted zircon Hf isotopes observed in North China and globally during early Earth may in verity imply the existence of ubiquitous depleted mantle domains at that time. [ABSTRACT FROM AUTHOR]

• Kyanite relics are identified from typically cordierite/sillimanite-bearing LMP pelitic granulites. • At least some LMP pelitic granulites are retrograded from HP types. • The linear distribution of HP pelitic granulites within the Jiaobei terrane is defined. • The JLJB is a continental orogenic belt formed through processes similar to modern plate margins. The pelitic granulites along the Paleoproterozoic Jiao-Liao-Ji belt (JLJB) are dominated by cordierite/sillimanite-bearing low- to medium-pressure (LMP) conditions. Recent studies have recognized a few typical high-pressure (HP) pelitic granulites without retrograde cordierite from the Jiaobei terrane, the southern part of the JLJB. The relationship between the dominant LMP and rare HP pelitic granulites is not well constrained, and whether the LMP types are retrograde products of the HP ones remains uncertain. This uncertainty precludes a full understanding of the original spatial distribution of HP pelitic granulites and the tectonic affinity of the JLJB. We identify in this study for the first time, relict kyanite and the mineral assemblage of kyanite + K-feldspar + rutile + garnet from typically cordierite/sillimanite-bearing LMP pelitic granulites within the Jiaobei terrane. Integrated results from petrology, pseudosection modeling, geothermobarometry, and zircon and monazite U-Pb geochronology suggest that these LMP pelitic granulites experienced an earlier HP granulite-facies metamorphism possibly at ~1.95 Ga, with minimum P-T conditions of 13–14 kbar and 860–870 °C. Subsequently, these rocks underwent near isothermal decompression to 4–7 kbar and >840 °C, followed by isobaric cooling to ~600 °C and 4–6 kbar. The decompression and cooling triggered LMP granulite-facies retrogression at ~1.85 Ga that eclipsed the earlier HP granulite-facies records. The clockwise P-T-t path defined is consistent with those reported from typical HP pelitic and mafic granulites elsewhere in the Jiaobei terrane. The results confirm that at least some portions of the typically cordierite/sillimanite-bearing LMP pelitic granulites are retrograded from the HP types. This greatly expands the spatial distribution of HP pelitic granulites and suggests a linear HP granulite-facies metamorphic belt within the Jiaobei terrane. The linear distribution of HP pelitic granulites whose protoliths are sedimentary rocks from Earth's surface and the consistent clockwise P-T-t paths require Paleoproterozoic subduction, collision, and exhumation processes similar to those operating in modern plate tectonics. Our results from the JLJB thus provide new metamorphic constraints on the nature of Paleoproterozoic plate tectonics, and have implications for other Precambrian high-grade terranes worldwide where pelitic granulites are dominated by LMP types. [ABSTRACT FROM AUTHOR]

The article reports on science research based on geology which informs about the seismological evidence for the earliest global subduction network with earliest evidence for subduction, which have been localized, does not signify when plate tectonics global phenomenon. Topics include investigated Paleoproterozoic time, for which seismic evidence is available from multiple continents; and high-density seismic array in North China to image the crustal structure that exhibits a dipping Moho.

The mid-Proterozoic (ca. 1850–850 Ma) is a peculiar period of Earth history in many respects: ophiolites and passive margins of this age are rare, whereas anorthosite and A-type granite suites are abundant; metamorphic rocks typically record high thermobaric (temperature/pressure) ratios, whereas ultrahigh pressure (UHP) rocks are rare; and the abundance of economic mineral deposits features rare porphyry Cu-Au and abundant Ni-Cu and Fe-oxide Cu-Ag (IOCG) deposit types. These collective observations have been used to propose that a stagnant-lid, or single-lid, tectonic regime operated at this time, between periods of plate tectonics in the Paleoproterozoic and Neoproterozoic. In our reappraisal of the mid-Proterozoic geological record, we not only assess the viability of the single-lid hypothesis for each line of evidence, but also that of the plate tectonic alternative. We find that evidence for the single-lid hypothesis is equivocal in all cases, whereas for plate tectonics the evidence is equivocal or supporting. We therefore find no reason to abandon a plate tectonic model for the mid-Proterozoic time period. Instead, we propose that the peculiarities of this enigmatic interval can be reconciled through the combination of two processes working in tandem: secular mantle cooling and the exceptionally long tenure and incomplete breakup of Earth's first supercontinent, where both of these phenomena had a dramatic effect on lithospheric behaviour and its resulting imprint in the geological record. • Evidence for single-lid vs plate tectonic modes in the mid-Proterozoic are reviewed. • The evidence is equivocal or in favour of plate tectonics in all cases. • The mid-Proterozoic geological record can be explained by two processes. • These are the long tenure and incomplete break-up of the Columbia supercontinent. • In combination with differing plate geodynamics that result from a warmer mantle. [ABSTRACT FROM AUTHOR]