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Fossils of the Ediacara Biota preserve the oldest evidence for complex, macroscopic animals. Most are difficult to constrain phylogenetically, however, the presence of rare, derived groups suggests that many more fossils from this period represent extant groups than are currently appreciated. One approach to recognize such early animals is to instead focus on characteristics widespread in animals today, for example multicellularity, motility, and axial polarity. Here, we describe a new taxon, Quaestio simpsonorum gen. et sp. nov. from the Ediacaran of South Australia. Quaestio is reconstructed with a thin external membrane connecting more resilient tissues with anterior‐posterior polarity, left‐right asymmetry and tentative evidence for dorsoventral differentiation. Associated trace fossils indicate an epibenthic and motile lifestyle. Our results suggest that Quaestio was a motile eumetazoan with a body plan not previously recognized in the Ediacaran, including definitive evidence of chirality. This organization, combined with previous evidence for axial patterning in a variety of other Ediacara taxa, demonstrates that metazoan body plans were well established in the Precambrian. [ABSTRACT FROM AUTHOR]

Although the early‐Precambrian crystalline basement is now only sporadically exposed in the northern and south‐western parts of the Yangtze Block, it is supposed to have a widespread distribution beneath its Neoproterozoic and Phanerozoic covers. Here we present results of regional aeromagnetic data processing in consideration of remanent magnetization to investigate the spatial distribution of the early‐Precambrian basement buried deep under the Upper Yangtze Block and surrounding areas. The direct analytic signal amplitude of the aeromagnetic anomalies, which is less affected by the magnetization direction, reveals a broader basement below the Sichuan Basin, extending far north to the Micang Mountain. A comparison between the direct analytic signal amplitude with the reduction to the pole aeromagnetic anomalies indicates that possible remanent magnetization exists beneath the Micang Mountain near the boundary between the Qinling Orogen and Sichuan Basin. The automatic depth from extreme points transform is then performed on the direct analytic signal amplitude to estimate the depth to the early‐Precambrian crystalline basement. A synthetic model of a magnetic interface with remanent magnetization and random noise shows that the depth from extreme points method is able to resolve variable basement depths. Application of the depth from extreme points method to the direct analytic signal amplitude of the Upper Yangtze Block presents meaningful results about the early‐Precambrian crystalline basement undulations. It is shallow and uplifted beneath the Sichuan Basin, extending north to the Qinling‐Dabie Orogen, probably corresponding to the ancient Chuanzhong palaeo‐uplift. Although it gradually deepens to the east, the deepest basement is buried under the Jiangnan Orogen, which is likely associated with the collision‐induced crustal thickening between the Yangtze and Cathaysia blocks during the assembly of the Columbia supercontinent. Large gas fields around the Sichuan Basin are found at the slopes or depressions between basement uplifts, indicating that the deep marine carbonate rocks in the south and east of Sichuan Basin, particularly those located at the slopes or depressions between ancient basement uplifts, are favourable targets for further petroleum exploration. [ABSTRACT FROM AUTHOR]

West Africa continues to host a growing number of low and intermediate‐magnitude earthquakes (M2‐5) along its passive margins, and its continental interior. Earthquake activity in these regions raises the need to comprehend the causes and the tectonic controls of the seismicity. Unfortunately, such studies are rare. Here, we apply single‐station inversion techniques to constrain fourteen focal mechanisms, computed after compiling a set of high‐quality waveforms. We describe the connection between seismicity, the contemporary stress field, anthropogenic activity and Holocene fault scarps in the region. Our results indicate transpressive stresses acting on the inherited brittle structures in the passive margins. We also observe a compressive regime in the intracontinental failed rifts. We attribute the seismicity to the reactivation of "weak" faults in the Neoproterozoic and Mesozoic failed rifts, the passive transform structures, and the intracratonic Precambrian brittle shear zones. Plain Language Summary: Earthquakes have occurred in West Africa, in the interior and the edges of regions that host several brittle structures. The causes and the mechanisms of this seismicity have not been comprehensively investigated. Hence, the characteristics of the regional tectonics are not fully established. In this study, we resolve the properties of the source of earthquakes, and the regional stress field. Our description of the sources of earthquakes matches the geometry of inherited brittle shear zones and failed rifts. The results indicate a strong influence of transpressive stress transfers from the ocean to the passive margins of West Africa. In the continental interior, especially, the West African Belt, the stress is compressional in the E‐W direction, consistent with stress orientations in adjoining regions. An extensional earthquake is observed in Mali, within the Gourma failed rift. We find that the seismicity of West Africa and the variations of the stress can be explained by the combination of preexisting faults, plate forces, ocean‐continent stress transfer, and density heterogeneity across the geologic domains. Key Points: Improved constraints on stress regimes and stress orientations from inversion of new focal mechanisms of M < 5.5 earthquakesNew focal mechanisms obtained from classical and novel approach based on single station waveform inversionEarthquakes in West Africa are rupturing the passive margin faults, intracontinental failed rift faults, and brittle shear zones [ABSTRACT FROM AUTHOR]

Detrital composition of sandstone is the most important data for siliciclastic studies including sandstone classification, provenance analysis, oil and gas exploration. A large amount of detrital composition data has accumulated over the past decades, however, they are scattered in publications without unified standards. Here we constructed a global dataset of detrital components of sandstones from 646 peer‐reviewed publications using Gazzi‐Dickinson method. A total of 19,861 samples from Precambrian to Quaternary are involved in this dataset. For each sample, we present details on reference information, geographic information, geological background, depositional age and the original data. It is a high‐quality dataset for the information on each sandstone sample from different studies which was standardized. The dataset can be used widely, such as for stratigraphic comparison, provenance analysis, exploring the general laws of the source‐to‐sink process and geological engineering. [ABSTRACT FROM AUTHOR]

We present Earth's Oxygenation and Natural Systematics (EONS): a new, fully coupled biogeochemical model of the atmosphere, ocean, and their interactions with the geosphere, which can reproduce major features of Earth's evolution following the origin of life to the present day. The model, consisting of 257 unique fluxes between 96 unique chemical reservoirs, includes an interactive biosphere, cycles of carbon, nitrogen, phosphorus, and oxygen, and climate. A nominal model run initialized in the Eoarchean resolves emergent surface oxygenation, nutrient limitations, and climate feedbacks. The modeled atmosphere oxygenates in stepwise fashion over the course of the Proterozoic; a nearly billion year lag after the evolution of photosynthesis at 3.5 Ga is followed by a great oxidation event at 2.4 Ga, which appears to be caused by the gradual buildup of organic matter on the continents imposing nutrient limitation on the biosphere by removing key nutrients from the ocean system. The simple climate system shows significant temperature shifts punctuate the oxygenation process, implying that major biological transitions possibly destabilized Earth's climate. This work demonstrates that forward modeling the entirety of Earth's history with relatively few imposed boundary forcings is feasible, that the Earth system is not at steady state, and that our understanding of coupled C‐N‐P‐O cycling as it functions today can explain much of the Earth's evolution. Plain Language Summary: The Earth is an interconnected system of biological, geological, and atmosphere‐ocean chemical systems responding to and influencing one another. We have developed a new model of our planet's chemical evolution, Earth's Oxygenation and Natural Systematics (EONS); this first of its kind model encompasses the entire lifetime of Earth's biosphere and major evolutionary developments therein, including the emergence of oxygen producing organisms and the colonization of continents by plants. Our basic (nominal) model run, starting 4 billion years ago and allowing biogeochemical systems to dynamically evolve until the modern day, agrees with geochemical evidence for rising atmospheric oxygen in magnitude and timing. It successfully reproduces atmosphere‐ocean chemistry and geologic systems in the modern context. Model output implies that the delay in oxygen's rise after the evolution of photosynthesis is caused by gradual burial of organic matter onto continents, depriving biological systems of key nutrients. Results also suggest that developments in the biosphere significantly disrupted Earth's climate. This model is a significant step forward in using coupled systematics to describe Earth's long‐term evolution. This work demonstrates that our planet is an immensely intertwined web of chemical relationships in a constant state of change, but one that can be fundamentally disentangled and understood. Key Points: The first fully coupled evolutionary C‐N‐O‐P box model spanning all major eons produces a surface oxygenation curve consistent with proxiesThe biosphere is a primary driver of Earth system evolution; increasing organic carbon burial and nutrient sequestration delay oxygen's riseThe chemical composition of the atmosphere‐ocean is never in steady state, due to the long timescales of geological and stellar evolution [ABSTRACT FROM AUTHOR]

Cnidarians—the phylum including sea anemones, corals, jellyfish, and hydroids—are one of the oldest groups of predatory animals. Nearly all cnidarians are carnivores that use stinging cells called cnidocytes to ensnare and/or envenom their prey. However, there is considerable diversity in cnidocyte form and function. Tracing the evolutionary history of cnidocytes may therefore provide a proxy for early animal feeding strategies. In this study, we generated a time‐calibrated molecular clock of cnidarians and performed ancestral state reconstruction on 12 cnidocyte types to test the hypothesis that the original cnidocyte was involved in prey capture. We conclude that the first cnidarians had only the simplest and least specialized cnidocyte type (the isorhiza) which was just as likely to be used for adhesion and/or defense as the capture of prey. A rapid diversification of specialized cnidocytes occurred through the Ediacaran (~654–574 million years ago), with major subgroups developing unique sets of cnidocytes to match their distinct feeding styles. These results are robust to changes in the molecular clock model, and are consistent with growing evidence for an Ediacaran diversification of animals. Our work also provides insight into the evolution of this complex cell type, suggesting that convergence of forms is rare, with the mastigophore being an interesting counterexample. Highlights: Cnidarian stinging cells diversified through the Ediacaran, demonstrating that animal predation evolved before the Cambrian explosion. The mastigophore is rare case of a complex cell type evolving more than once. [ABSTRACT FROM AUTHOR]

Earth's deep continental subsurface is a prime setting to study the limits of life's relationship with environmental conditions and habitability. In Precambrian crystalline rocks worldwide, deep ancient groundwaters in fracture networks are typically oligotrophic, highly saline, and locally inhabited by low‐biomass communities in which chemolithotrophic microorganisms may dominate. Periodic opening of new fractures can lead to penetration of surface water and/or migration of fracture fluids, both of which may trigger changes in subsurface microbial composition and activity. These hydrogeological processes and their impacts on subsurface communities may play a significant role in global cycles of key elements in the crust. However, to date, considerable uncertainty remains on how subsurface microbial communities may respond to these changes in hydrogeochemical conditions. To address this uncertainty, the biogeochemistry of Thompson mine (Manitoba, Canada) was investigated. Compositional and isotopic analyses of fracture waters collected here at ~1 km below land surface revealed different extents of mixing between subsurface brine and (paleo)meteoric waters. To investigate the effects this mixing may have had on microbial communities, the Most Probable Number technique was applied to test community response for a total of 13 different metabolisms. The results showed that all fracture waters were dominated by viable heterotrophic microorganisms which can utilize organic materials associated with aerobic/facultative anaerobic processes, sulfate reduction, or fermentation. Where mixing between subsurface brines and (paleo)meteoric waters occurs, the communities demonstrate higher cell densities and increased viable functional potentials, compared to the most saline sample. This study therefore highlights the connection between hydrogeologic heterogeneity and the heterogeneity of subsurface ecosystems in the crystalline rocks, and suggests that hydrogeology can have a considerable impact on the scope and scale of subsurface microbial communities on Earth and potentially beyond. [ABSTRACT FROM AUTHOR]

The combined petrographic, petrological, geochemical and geochronological study of the Neoproterozoic gneisses of the Sarychabyn and Baskan complexes of the Junggar Alataw of South Kazakhstan elucidate the Precambrian tectonic evolution of the Aktau–Yili terrane. It is one of the largest Precambrian crustal blocks in the western Central Asian orogenic belt. The U‐Pb single‐grain zircon ages indicate that granite‐gneisses formed from the same source and crystallised in the early Neoproterozoic ca. 930–920 Ma. The chemical composition of gneisses corresponds to A2‐type granites. The whole‐rock Nd isotopic characteristics (εNd(t) = –4.9 to –1.0 and TNd(DM‐2st) = 1.9 to 1.7 Ga) indicate the involvement of Paleoproterozoic crustal rocks in magma generation. Early Neoproterozoic ca. 930–920 Ma A‐type granitoids in the Aktau–Yili terrane of South and Central Kazakhstan might reflect within‐plate magmatism adjacent to the collisional belt or a local extension setting in back‐arc areas of the continental arc. [ABSTRACT FROM AUTHOR]

3D forward gravity modeling combined with receiver function (RF) analysis characterizes the crustal structures of the southern part of the Mongolian collage. The seismic signals of the 48 stations of the MOBAL2003 and the IRIS‐PASSCAL experiments were analyzed to get the RFs. This analysis revealed a significant difference between the crustal structures of the Hangay dome and the tectonic zones in the south. In addition, seismic stations south of the Hangay dome display significant signals related to the occurrence of a low‐velocity zone at lower crustal level confirmed by the gravity anomalies. Finally, these seismic analysis inputs, the boundaries, the lithologies, and the density values from rock samples of the different tectonic zones constitute the starting points from the 3D forward gravity modeling. The resulting crustal density model indicates: (a) the likely absence of a Precambrian basement block beneath the Hangay dome, (b) an alternation of two low‐velocity/low‐density zones (LVLDZs) with high‐density zones in the Baydrag microcontinent interpreted as fragments of early Tonian plutons, (c) the occurrence of an LVLDZ at the lower crustal level beneath the Lake zone, the Mongol‐Altai Accretionary Wedge, and the Trans‐Altai Zone. Therefore, the combination of the seismic RF with gravity analysis and modeling reveals new crustal structures of the Mongolian collage and enhances the occurrence and the extent of an LVLDZ at lower crustal level. These LVLDZ may demonstrate the existence of the relamination of a hydrous material in southern Mongolian collage. Plain Language Summary: We combined geophysical data sets to obtain a 3D model of the southern part of Mongolia. We found that the relamination of continental rocks in the lower crust may explain successive contrasted layers in this accretionary domain. We used seismic data from 48 stations to create a crustal thickness map and compared it to a 3D modeling of gravity data. We discovered significant differences between the Hangay dome's crust and the rest of the area, including the likely absence of a Precambrian basement block beneath Hangay. We also found a low‐velocity and low‐density zone in the lower crust beneath the southern tectonic zones, which we interpret as the relamination of a previous volcanic arc beneath the younger heterogeneous upper crust. Our results demonstrate the relamination of a hydrous material in the southern part of Mongolia, and question a more regional extent for this crust composition change process. Key Points: Seismic and gravity analyses confirm in 3D the relamination of a hydrous material in southern Mongolian collageWe found no evidence of a Precambrian basement block beneath the Hangay domeFragments of early Tonian plutons are imaged as an alternation of low‐velocity and low‐density layers with high‐density material [ABSTRACT FROM AUTHOR]

Precambrian organic‐walled microfossils (OWMs) are primarily preserved in mudstones and shales that are low in total organic carbon (TOC). Recent work suggests that high TOC may hinder OWM preservation, perhaps because it interferes with chemical interactions involving certain clay minerals that inhibit the decay of microorganisms. To test if clay mineralogy controls OWM preservation, and if TOC moderates the effect of clay minerals, we compared OWM preservational quality (measured by pitting on fossil surfaces and the deterioration of wall margins) to TOC, total clay, and specific clay mineral concentrations in 78 shale samples from 11 lithologic units ranging in age from ca. 1650 to 650 million years ago. We found that the probability of finding well‐preserved microfossils positively correlates with total clay concentrations and confirmed that it negatively correlates with TOC concentrations. However, we found no evidence that TOC influences the effect of clay mineral concentrations on OWM preservation, supporting an independent role of both factors on preservation. Within the total clay fraction, well‐preserved microfossils are more likely to occur in shales with high illite concentrations and low berthierine/chamosite concentrations; however, the magnitude of their effect on preservation is small. Therefore, there is little evidence that bulk clay chemistry is important in OWM preservation. Instead, we propose that OWM preservation is largely regulated by physical properties that isolate organic remains from microbial degradation such as food scarcity (low TOC) and low sediment permeability (high total clay content): low TOC increases the diffusive distances between potential carbon sources and heterotrophic microbes (or their degradative enzymes), while high clay concentrations reduce sediment pore space, thereby limiting the diffusion of oxidants and degradative enzymes to the sites of decay. [ABSTRACT FROM AUTHOR]

Iron (Fe) is an essential element for life, and its geochemical cycle is intimately linked to the coupled history of life and Earth's environment. The accumulated geologic records indicate that ferruginous waters existed in the Precambrian oceans not only before the first major rise of atmospheric O2 levels (Great Oxidation Event; GOE) during the Paleoproterozoic, but also during the rest of the Proterozoic. However, the interactive evolution of the biogeochemical cycles of O2 and Fe during the Archean–Proterozoic remains ambiguous. Here, we develop a biogeochemical model to investigate the coupled biogeochemical evolution of Fe–O2–P–C cycles across the GOE. Our model demonstrates that the marine Fe cycle was less sensitive to changes in the production rate of O2 before the GOE (atmospheric pO2 < 10−6 PAL; present atmospheric level). When the P supply rate to the ocean exceeds a certain threshold, the GOE occurs and atmospheric pO2 rises to ~10−3–10−1 PAL. After the GOE, the marine Fe(II) concentration is highly sensitive to atmospheric pO2, suggesting that the marine redox landscape during the Proterozoic may have fluctuated between ferruginous conditions and anoxic non‐ferruginous conditions with sulfidic water masses around continental margins. At a certain threshold value of atmospheric pO2 of ~0.3% PAL, the primary oxidation pathway of Fe(II) shifts from the activity of Fe(II)‐utilizing anoxygenic photoautotrophs in sunlit surface waters to abiotic process in the deep ocean. This is accompanied by a shift in the primary deposition site of Fe(III) hydroxides from the surface ocean to the deep sea, providing a plausible mechanistic explanation for the observed cessation of iron formations during the Proterozoic. [ABSTRACT FROM AUTHOR]

Bauxitic clays, clayey bauxites and bauxites are residual products formed from the weathering of aluminosilicate‐rich parent rocks under wet and warm conditions. These deposits show a complex interplay between remobilisation of pre‐existing kaolinitic soils and depositional micro‐environments. In the southern Ribeira belt, Brazil, a paleoweathering surface developed on the continental shelf of the Capiru Group passive margin strata and on its basement/source rocks. This weathering cycle gave rise to a paleosol profile on the continental domain and a karstic paleotopography on the emerged carbonate shelf. The surface and karstic nets were later caped and filled with Al‐rich materials, typical of remobilised soils, bauxitic clays, clayey bauxites and pods of karst‐type bauxites. The age of the disconformity is Pre‐Brazilian/Pan‐African, implying a Neoproterozoic age for the weathering surface. In this study, we investigate the relationship among disconformities, paleosols and karst topography to better understand the stratigraphic control, chemical composition and mineralogy of the Al‐rich materials. We interpret this horizon as the remnants of a (meta‐)paleoweathering surface that can serve as a valuable key bed for stratigraphic correlation and paleogeographic reconstructions. We propose that the triggering process for the genesis of the paleosol profiles, bauxitic material and bauxite pods was a coupled mechanism between favourable climate and uplift along the northern margin of the Curitiba–Angola craton, creating a karstic topography that allowed the down‐plain transport of Al‐rich materials. In a later stage, these deposits were metamorphosed, developing a series of Al silicates in unusual paragenesis, typical of Al‐rich protoliths. The presence of these paragenesis, along with the recognition of the disconformity–paleoweathering surface pair, could be a useful tool to understand the paleoenvironmental and paleogeographic evolution of highly deformed terrains. [ABSTRACT FROM AUTHOR]

Fine‐grained, siliciclastic units of the >1642 ± 3.9 Ma late Palaeoproterozoic Limbunya Group, Birrindudu Basin host rich, well‐preserved organic‐walled microfossil assemblages that include members of total‐group eukaryotes. These assemblages include taxa characteristic of this interval such as Tappania plana and Satka favosa, as well as less common taxa such as Gigantosphaeridium fibratum, Gigantosphaeridium floccosum, Kamolineata elongata (= Valeria elongata; new combination), and four new species. The new taxa include Limbunyasphaera operculata gen et sp. nov., the oldest known operculate taxon; the large septate filaments of Siphonoseptum bombycinum gen. et sp. nov.; the platy tubular form Birrindudutuba brigandinia gen. et sp. nov.; and Filinexum torsivum gen. et sp. nov., which bears a spirally twisted wall constructed of bound fibres. Our data show that eukaryotic fossils are particularly abundant in marginal marine environments such as tidal flats and back‐barrier lagoonal settings. This is exemplified by the Blue Hole Formation, which features an especially diverse and complex assemblage. We also present a new within‐formation eukaryotic species richness estimate for the Palaeoproterozoic to Tonian. This estimate indicates that the oldest eukaryote‐bearing units already show species richness levels similar to those of the much younger and more heavily sampled Tonian period. Additionally, these oldest eukaryotic assemblages show significant morphological disparity, particularly in vesicle construction. These high levels of eukaryotic species richness and morphological disparity suggest that although late Palaeoproterozoic units preserve our oldest record of eukaryotes, the eukaryotic clade has a much deeper history. [ABSTRACT FROM AUTHOR]

The Paleoproterozoic was an important stage in the evolution of life and the environment during Earth's history. Understanding astronomical rhythms and solar system behavior in the Paleoproterozoic is often challenging. In this study, ∼190 m high‐resolution magnetic susceptibility (MS) and ∼30 m high‐resolution Ba/Al data are used to conduct cyclostratigraphic analyses of the Chuanlinggou Formation in the Yanliao Rift, North China Craton. Spectral analysis indicates significant peaks at wavelengths of 12.1–7.7, 2.8–1.6, 0.58–0.33, and 0.29–0.22 m, which matches well with the astronomical cycles predicted by Waltham for ∼1,640 Ma. A 9.9‐Myr astronomical time scale is constructed by tuning the MS series to the 405‐kyr‐long eccentricity cycle. The geological records show ∼1.56‐Myr very long eccentricity period and ∼1.0‐Myr very long obliquity period (close to 3(s4 − s3) − 2(g4 − g3) = 0) in the Paleoproterozoic. The sea‐level change curve predicted by dynamic noise models reveals a significant ∼1.0‐Myr period, indicating that sea level fluctuation may have been driven by the very long obliquity period. Bayesian inversion is used to further estimate the evolution of the ancient Earth‐Moon orbital parameters, constraining a precession rate of 87.14 ± 0.25 arcsec/year and an Earth‐Moon distance of 341,530 ± 390 km for the Paleoproterozoic Changcheng System. These results indicate that astronomical orbital forcing may have played an important role in climate and sea‐level changes in the Precambrian, increasing the understanding of the fundamentals of global sea level fluctuations, orbitally driven mechanisms and the chaotic behavior of the Precambrian solar system. Plain Language Summary: Orbital parameters and long‐term behavior have changed during geological history. For the first time, we found new resonance states between Mars and Earth (i.e., a very long eccentricity period of ∼1.56 Myr and a very long obliquity period of ∼1.0 Myr) from the geological records of the Paleoproterozoic Changcheng System in the Yanliao Rift of the North China Craton. The reconstructed sea‐level change curve shows a significant ∼1.0‐Myr period, indicating that sea level fluctuations may have been driven by the very long obliquity period in the Precambrian. The orbital parameters in the Paleoproterozoic are recovered using Ba/Al ratios, and the calculated precession constant is 87.14 ± 0.25 arcsec/year. The Earth‐Moon distance was 341,530 ± 390 km, and the length of day (LOD) was 18.06 ± 0.05 hr, which indicates that lunar recession may have been slower in deep time. These results increase the understanding of astronomical rhythms and the chaotic behavior of the solar system in the Precambrian. Key Points: A new Earth‐Mars resonance state (3(s4 − s3) − 2(g4 − g3) = 0) is revealed from the Precambrian geological recordsThe ∼1.0‐Myr very long obliquity period significantly affected sea level fluctuations under the Mesoproterozoic greenhouse climate [ABSTRACT FROM AUTHOR]

The Susong complex zone is a relatively low‐grade metamorphic unit located in the southern part of the Dabie orogen and preserves a variety of metasedimentary rocks, mostly with epidote–amphibolite facies. However, their depositional age, provenance and tectonic setting of sedimentary protolith remain controversial due to the lack of fossils, precise dating and integrated geochemical investigation. This study has conducted whole‐rock elemental, and zircon U‐Pb SHRIMP dating and Lu‐Hf isotope analyses on three types of representative metasedimentary rocks including garnet‐bearing mica‐quartz schist, graphite‐muscovite‐quartz schist and dolomitic marble from the Susong complex zone. The U‐Pb SHRIMP dating data indicate that the sedimentary protolith of these rocks have the maximum depositional ages of less than 840–750 Ma and have various sedimentary provenances. In combination with zircon Lu‐Hf isotope compositions, the provenance of the metasedimentary rocks in the region is for the first time documented to be mainly derived from four groups of magmatic rocks formed at ∼2.5 Ga, ∼2.0 Ga, ∼1.4 Ga and ∼0.8 Ga in response to four episodes of igneous activity in the northeastern margin of the Yangtze Block. The conventional geothermobarometry combined with rare metamorphic zircon ages indicate that the studied rocks underwent the Late Triassic continental subduction‐related metamorphism with peak epidote–amphibolite facies conditions at P = 0.34–0.91 GPa and T = 427–532°C. In addition, results of the elemental contents (i.e., La, Ce, Th and ΣREE) and ratios (i.e., Eu/Eu* and LaN/YbN) suggest that the protoliths of the metasedimentary rocks were mainly shales, wackes and limestones, most probably related to the Rodinia supercontinent rifting along the northern margin of the Yangtze Block during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

Detrital zircon U–Pb chronology database of Precambrian deposits provides a context for the interpretation of the origin and evolution of ancient crust. Here, we tried to summarize the published literature containing detrital zircon U–Pb ages and Hf isotope data of Precambrian deposits in South China and then established a database, which contains details of information, such as reference, sample ID, locality, rock type, research institution, GPS coordinates, U–Pb ages and εHf(t) values. The data statistics of this paper rely on the OneSediment Working Group of The Deep‐time Digital Earth program (DDE). By November 2022, 610 samples with 38,278 U–Pb ages and 8,798 Lu‐Hf isotope data were collected from 136 papers, and these data can be downloaded from DDE Data Publish & Repository website, https://repository.deep‐time.org/. The purpose of the establishment of the dataset is to provide guidance and convenience for the research direction of future generations in South China and to improve the previous studies through the integrated data to avoid the waste of resources caused by a large number of repeated studies. [ABSTRACT FROM AUTHOR]

To better understand the Paleo‐ to Mesoproterozoic tectonic evolution of the Dabie Orogen in the northern margin of Yangtze Block, we present geochronological data for metasedimentary and metavolcanic rocks in the Huwan complex. A total of 385 detrital zircon LA‐ICP‐MS analyses for metasedimentary rocks yielded three 207Pb/206Pb age populations: 1.50–1.80 Ga, 1.81–1.87 Ga and 1.93–2.0 Ga, providing a maximum depositional timing of ca. 1.50 Ga; while metafelsic volcanic gneisses yielded protolith U‐Pb ages of 1893 ± 54 Ma. The peak ages are remarkably consistent with the tectonothermal events that occurred in the northern Yangtze Block, indicating the presence of Paleo‐ to Mesoproterozoic magmatism in the Dabie Orogen. The age range of 1.93–2.0 Ga correlates with the Paleoproterozoic collision; the age range of 1.81–1.87 Ga coincides with the period of the post‐orogenic extension; and the age range of 1.50–1.80 Ga is interpreted to associate with an extensional regime. Zircon cores with age of 1732–1965 Ma have εHf(t) values ranging from –11.70 to –2.47, indicating that juvenile crust involved in their magma sources. Owing to the similar age spectra, we proposed that the nucleus of the Dabie Orogen was close to the Yangtze Block since the Paleoproterozoic. The Huwan complex has an intimate affiliation to the Yangtze Block, and implies multiple orogenic cycles. It was not only experienced the Paleo‐Tethys ocean subduction and collision, but also recorded Paleo‐ to Mesoproterozoic tectono‐magmatic events in the Dabie Orogen. [ABSTRACT FROM AUTHOR]

The Yili Block in the Western Tianshan orogen is a key area for understanding the early crustal formation and evolution of the Central Asian orogenic belt, due to the widely‐distributed Precambrian rocks. Also, it hosts a lot of medium– to large‐scale sedimentary exhalative (SEDEX) Pb‐Zn deposits that mainly occur in Proterozoic metamorphosed clastic‐carbonate rocks. In this study, LA‐ICP‐MS U‐Pb analyses were carried out on detrital zircons in siltstones of the Precambrian Haerdaban Group in the Haerdaban Pb‐Zn deposit and magmatic zircons in the diorite dyke that cuts through the strata and orebodies. The maximum depositional age of the siltstones was determined to be about 604 Ma, the diorite having formed at approximately 500 Ma. As such, the Haerdaban Group was most likely formed in the Neoproterozoic Sinian, rather than the previously considered Mesoproterozoic Changchengian. Detrital materials of the Haerdaban Group were mostly derived from the Nanhua–Sinian mafic dykes and granitic rocks around Lake Sayram at the northern margin of the Yili Block. It is proposed that the Yili Block, together with the Kazakhstan and Central Tianshan blocks and the Tarim Craton, might all pertain to the same Rodinia supercontinent, which has great potential for targeting large to super‐large SEDEX Pb‐Zn deposits. [ABSTRACT FROM AUTHOR]

Paleogeographic reconstruction of Precambrian terranes reworked by Phanerozoic orogens (e.g., the Tibetan Plateau) results in complex lithotectonic relations due to intracrustal reworking by tectonothermal events. Detrital zircon rare earth element (REE) databases at global (global major river sands) and regional (the Gangdese Mountains, southern Tibet) scales reveal trends in LREEN‾/HREEN‾ $\overline{{\mathrm{L}\mathrm{R}\mathrm{E}\mathrm{E}}_{\mathrm{N}}}/\overline{{\mathrm{H}\mathrm{R}\mathrm{E}\mathrm{E}}_{\mathrm{N}}}$ and Eu/Eu* that effectively record the crustal evolution of the source, including crustal thickness and redox state of the magma that generated the zircons. Regional comparisons of these chemical markers provide a new approach for paleogeographic reconstructions that we apply to study the origin of the Lhasa terrane, southern Tibet. Using Precambrian to early Paleozoic sedimentary and igneous rocks in the Lhasa terrane and compiling detrital zircon analyses from the northern margin of Gondwana, we show that the Lhasa terrane had an African affinity in the Rodinia–Gondwana supercontinent cycles (ca. 1.4–0.4 Ga). Plain Language Summary: Constraining the paleogeographic positions and affinities of continental fragments plays a crucial role in validating the concept of the supercontinent cycle. However, tracking the evolving paleogeographic position of these fragments, especially for those of Precambrian age, has proven difficult. We explore the potential for solving this problem by using detrital zircon rare earth element (REE) abundances, which are controlled by the magma source depth, protolith type, oxygen fugacity, and magmatic water content of parental melts. We reveal correlations between detrital zircon REE abundances and crustal evolution in different tectonic settings based on global and regional detrital zircon databases. We subsequently demonstrate how detrital zircon REE abundances show that the Lhasa terrane in the southern Tibet is a fragment derived from Africa. Our study provides a new perspective on the paleogeographic reconstruction of continental fragments through Earth's history and thus has important implications for supercontinent research. Key Points: Zircon rare earth element (REE) abundances reflect the composition of, and the conditions that generated, the parental meltsTrends in detrital zircon REE effectively preserve a crustal evolution history and provide a new approach for paleogeographic reconstructionThe Lhasa terrane in the southern Tibet had an African affinity in the Rodinia‐Gondwana supercontinent cycles [ABSTRACT FROM AUTHOR]

Secondary converted waves from receiver functions are highly sensitive to physical properties below the Earth's surface. When modeled properly, the waveforms of converted waves offer direct constraints on the impedance contrast, depth, and P‐to‐S velocity ratio pertaining to sedimentary, crustal and mantle interfaces. In this study we introduce a nonlinear waveform inversion algorithm that matches the first 5 s of receiver functions recorded in the Alberta Basin within the Western Canada Sedimentary Basin (WCSB). Our algorithm searches for the optimal thickness of the sedimentary cover and shear velocities of appropriately selected layers within and below it. Combining inversions with forward simulations, we determine the supracrustal stratigraphy from 80 regional broadband seismic stations in the WCSB. The inverted models show east tapering sedimentary layers with their thicknesses ranging from ∼6 km beneath the foothills of the Canadian Rocky Mountains to 3–4 km beneath the Alberta Basin. This finding is consistent with the sedimentary strata determined from regional well‐logging data. The sedimentary layer contains low velocity zones of variable thicknesses and amplitudes that, depending on the locations, may be caused by mechanisms involving deposition, composition or deformation history. Our shear velocity models near the top of the basement complement the existing sonic‐logs or single component seismic data and offer new constraints on the subsidence history of the WCSB. The resolved range of depths (0–14 km) effectively bridges the gap between the vertical scales of well logging (0–6 km) and those of traditional broadband analysis (>10 km) involving receiver functions and surface waves. Plain Language Summary: Our study uses the receiver function (RF)—a function computed from a 3‐component seismogram—to recovery the subsurface structure of the Alberta Basin. We introduce a non‐linear waveform inversion method based on the Genetic Algorithm to match the first 5 s of the RFs recorded by 80 regional broadband seismic stations in the Western Canada Sedimentary Basin (WCSB). Our inverted models of the Precambrian basement, which is the boundary between sedimentary strata and the upper crust, show an east tapering trend. The sedimentary layer of our inverted models contains low velocity zones of variable thicknesses and amplitudes that may be formed by various geological processes during basin subsidence. Our model provides critical information on the seismic structures in the intermediate depth range (0–14 km), effectively bridging the gap between the vertical scales of well logging (0–6 km) and those of traditional broadband analysis (>10 km). Key Points: We recover the sedimentary structure of the Alberta Basin using nonlinear inversion of receiver functionsWe recover low velocity zones in the sedimentary strataWe constrain the Precambrian basement to reveal the subsidence history [ABSTRACT FROM AUTHOR]

The western segment of the suture zone between the Yangtze and Cathaysia blocks, which is the most important tectonic boundary related to the formation and rifting of south China, is enigmatic and not fully understood due to the sporadic exposure of Precambrian strata and ophiolites. Three‐dimensional electrical resistivity models derived from inversion of magnetotelluric data identified a lithospheric‐scale conductive zone extending northeastwards beneath the Youjiang basin, which was interpreted as the western segment of the suture zone. The high conductivity and coincident high magnetic anomalies closely match the location of Carlin‐type gold deposits, which can be explained by fluids and gold‐bearing sulfide minerals in a fossil suture zone. Inconsistent with the southeast‐dip resolved at the eastern segment of the suture zone (the Jiangshan‐Shaoxing fault) in the earlier study, the slightly north‐dipping geometry at the western suture zone implies the reactivation by northward subduction and closure of the Paleo‐Tethys Ocean. Plain Language Summary: Suture zones are tectonic scars that mark the subduction, collision, and amalgamation of different tectonic units. Imaging suture zones is critical because they are first‐order tectonic boundaries and can play a guiding role in continental rifting and breakup. The suture zone between the Yangtze and Cathaysia blocks is the most important tectonic boundary in south China. While the eastern segment of this suture zone is agreed to be located along the Jiangshan‐Shaoxing fault, the western segment of this suture zone is under debate. This study used magnetotelluric method to image the deep earth structure beneath the western boundary of the Yangtze and Cathaysia blocks. We identified a high‐conductivity zone from the subsurface to a depth of 80 km and interpreted this zone as being caused by fluids and gold‐bearing sulfide minerals in a fossil suture zone. The conductivity pattern observed in this suture zone differs from that in the earlier study about the eastern segment of the suture zone. This implies that the western suture zone has been modified after the initial collision of the two continents, perhaps by northward subduction and closure of the Paleo‐Tethys Ocean. Key Points: Magnetotelluric array data were inverted to obtain the lithospheric resistivity structure in southwestern ChinaThree‐dimensional resistivity model images a Precambrian suture beneath the Youjiang basinThe geometry resolved at the suture zone implies the reactivation by northward subduction and closure of the Paleo‐Tethys Ocean [ABSTRACT FROM AUTHOR]

The Fuchuan ophiolite is located in the northeasternmost segment of the Neoproterozoic Jiangnan orogen and consists mainly of harzburgites, with minor dunites, pyroxenite and gabbro veins and dykes. In order to investigate the genesis and tectonic setting of the Fuchuan ophiolite and chromitites, in situ analyses of unaltered chromites and silicates were carried out. Trace element analyses of unaltered chromites from the Fuchuan chromitites indicate the parental magma is of mid‐ocean ridge basalt (MORB)‐like origin, with the Ti/Fe3+#–Ga/Fe3+# diagram of chromites showing that the chromitites are a result of melt/rock interaction of MORB melts with mantle peridotites, and that the Fuchuan harzburgites present the dual features of MORB and supra‐subduction zone peridotites (SSZP). Trace and rare earth element (REE) analyses of olivines and orthopyroxenes from the Fuchuan harzburgites hint at the possibility of mantle metasomatism influenced by SSZ‐subducted fluids. Finally, integrating with previous study, the Fuchuan ophiolite and chromitites might have been formed in a back‐arc spreading ridge between the Yangtze and Cathaysia blocks during the Neoproterozoic. [ABSTRACT FROM AUTHOR]

The Xiejiaba and Fuqiangbei plutons form part of the newly identified Neoproterozoic Niushan complex, which is located in the southern South Qinling belt (SQB). The plutons are compositionally similar, were emplaced at 750–711 Ma, and provide insights into Neoproterozoic tectonism within the South Qinling belt. The Xiejiaba pluton contains diorite, quartz diorite, granodiorite, and granite phases, all of which are sub‐alkaline and have variable major element compositions with negative correlations between SiO2 and MgO, TFe2O3, Al2O3, CaO, TiO2 and P2O5. These rocks are enriched in light rare earth elements (LREEs) and large ion lithophile elements (LILEs) and have negative Nb, Ta, P and Ti anomalies, all of which are indicative of arc‐type magmatism. The Fuqiangbei pluton contains granitoids that are compositionally similar to the rocks in the Xiejiaba pluton. Samples from these plutons have similar ɛNd(t) values (1.24–5.99) but very variable (87Sr/86Sr)i values (0.7010–0.7054). Combining these data with the geochemical data for these rocks suggests that the magmas that formed the Niushan complex were derived from the crust–mantle boundary. This, combined with the results of previous research, suggests that the transition from low pressure‐low temperature to low pressure‐high temperature conditions within a subduction zone caused melting during a period of late subduction and backarc extension. This constrain the timing of subduction within the South Qinling belt and the northern Yangtze Block (YB) to 750–711 Ma, with this Neoproterozoic subduction associated with an ocean to the north overprinting an existing continental rift‐type tectonic setting within the northern margin of the Yangtze Block and the South Qinling belt. [ABSTRACT FROM AUTHOR]

Paleogeographic models provide first‐order insights into Earth's tectonic evolution in deep geologic time. However, there is a lack of objective metrics to distinguish between rival models. Using a recent compilation of reliable Precambrian paleomagnetic data, we quantify the extent of paleomagnetic compliance of existing Ediacaran global reconstruction models. We determine spherical arc distances between modeled paleopositions of the geographic South Pole and reconstructed coordinates of all paleopoles from a continent acquired at various times. We identify significant paleomagnetic bias for a reconstructed location of a continent if arc distances of the majority of high‐quality paleopoles with reliable age constraints are greater than their standard errors at the 95% confidence interval. Our study provides quantifiable measures of paleogeographic bias that allows researchers to make informed decisions when selecting among existing global models as a foundation for interpreting their geologic data. Plain Language Summary: Paleogeographic reconstructions, often presented as black‐box models of the paleolocations of continents, are typically constructed by minimizing paleomagnetic bias while satisfying geologic constraints. Such paleogeographic models are created to fit some informed selection of paleomagnetic and geologic data. However, underfitting (i.e., ignoring specific paleopoles) of paleogeographic models, especially where paleomagnetic data are sparse, is potentially problematic as models may not capture apparent, ancient geomagnetic variations. Geologic observations such as paleoenvironmental, biogeographic, and sedimentary provenance tracers, are commonly used to justify underfitting, but can inadvertently result in paleogeographic models with large paleomagnetic bias. Furthermore, interpretations of geologic constraints are often equivocal or controversial, yielding multiple plausible continental paleopositions. Here we adopt simple metrics to detect the paleomagnetic bias inherent in a selection of recently Ediacaran paleogeographic models, each purported to satisfy first‐order paleomagnetic and geologic (typically paleoenvironmental and tectonostratigraphic) constraints. These simple metrics will allow researchers to assess the trade‐off between paleomagnetic error and geological plausibility inherent in individual paleogeographic models. Key Points: Paleomagnetic bias of a continental reconstruction can be detected from the extent of compliance to available robust paleomagnetic polesWe propose a simple workflow to objectively quantify paleomagnetic bias in reconstruction modelsWe evaluate the paleomagnetic bias of six competing Ediacaran global reconstruction models [ABSTRACT FROM AUTHOR]

We present the whole‐rock and mineral chemical data of the Khasi meta‐mafic/basic‐trondhjemite intrusives (KMI) and meta‐tonalite‐trondhjemite (MTT) that coevally emplaced the Proterozoic Shillong Group (SG) of Shillong Plateau, northeast (NE) India and discuss their petrogenetic‐tectonic origin. The calc‐alkaline to tholeiite KMI are compositionally transitional between hornblende‐gabbro; hornblende‐diorite and minor‐hornblendite. They show Ta–Nb troughs and strong decoupling large‐ion lithophile/high field strength elements (HFSE) signature consistent with subduction zone‐related basic magmas. The calcic to calc‐alkaline, low‐Al2O3, and I‐type metaluminous Fe‐hedenbergite‐trondhjemite (KMT) exhibits similar trace and rare earth elements (REE) distribution to the KMI. The MTT on the other hand are depleted in trace elements and REE, and correspond with the I‐type granitoids, and are comparable to Proterozoic to Phanerozoic tonalite‐trondhjemite‐granodiorites. Gentle negative sloping of REE in KMI ([La/Lu]CN = 4.04 to 6.35) with moderate LREE, suggests partial melting or, fractional crystallization from a transitional source between garnet and spinel lherzolite. Although almost a flat pattern ([La/Lu]CN = 3.70 to 4.05) for MTT entails a high degree of partial melting from sources similar to Archaean Mafic Composite or Archaean Tholeiite. Trace elemental modellings ([Sr/Y] vs. Y and [La/Yb]N vs. YbN) for MTT infer low pressure (<15 kbar) and high degree partial melting of >50% in equilibrium with 10% garnet +90% amphibole residue. A relatively flat REE pattern with some elevated HREE of MTT compared to KMI suggests for depleted source. Bimodal plutonism and the prevalence of meta‐dacite‐rhyolite in SG invokes for tonalite‐trondhjemite‐dacite setting of a continental arc or, active continental margin tectonic setting. Emplacement of KMI initiated in a temporary relax‐extensional phase and MTT in a compressional regime. This is possibly caused by an over‐thickened crust later subjected to orogenic collapse, exhumation‐metamorphism, and decompressional melting. This event might have taken place between 1.0 to 0.5 Ga during the Pan‐African Orogenic crustal growth, linked to the amalgamation of Gondwana. [ABSTRACT FROM AUTHOR]

Precambrian rocks are necessary to understand the tectonic and crustal evolution of the Central Asian Orogenic Belt, especially the tectonic affinities of embedded microcontinents. We conducted a combined analysis of whole‐rock geochemistry, zircon U–Pb geochronology, and Hf isotope on the Mesoproterozoic igneous rocks from the Zhusileng–Hangwula Belt of the northern Alxa area to investigate its tectonic affinity. The zircon ages show that the gneissic granites, metagabbro, and amphibolite formed at 1,433–1,424 Ma, 1,383, and 1,373 Ma, respectively. Furthermore, zircon xenocrysts from the rhyolite in the Zhusileng area exhibit a 206Pb/238U ages cluster at about 1.4 Ga. Geochemically, the gneissic granites are high‐potassium calc‐alkaline granitoids and exhibit light rare earth element‐enriched pattern, pronounced significant negative Eu anomalies, negative Nb–Ta anomalies, positive εHf(t) values (3.2–11.3), and young two‐stage model ages (2.21–1.46 Ga), indicating that they were derived from a magma source of rapid reworking of juvenile mantle‐derived materials with a limited ancient crustal contamination. The FeOT, CaOm and MgO contents of mategabbros and amphibolite are high, but their total rare earth elements are relatively low (TREE = 31.45–32.74). They are characterized by relatively positive zircon εHf(t) values (5.3–11.0), and very young two‐stage model ages (1.98–1.49 Ga), indicating that they were generated from the depleted mantle. Our geochemical data suggest that these Mesoproterozoic rocks in the Zhusileng–Hangwula Belt are consistent with the formation period and tectonic environment of juvenile basement rocks from the Central Tianshan Arc and southern Beishan Orogenic Belt, whereas a Mesoproterozoic correlation with the Tarim Craton is highly unlikely. Thus, we believe that the Zhusileng–Hangwula Belt has an analogous tectonic evolution and a close affinity with the Central Tianshan Arc and southern Beishan Orogenic Belt during the Mesoproterozoic. [ABSTRACT FROM AUTHOR]

During the early Cambrian period metazoan life forms diverged at an accelerated rate to occupy multiple ecological niches on earth. A variety of explanations have been proposed to address this major evolutionary phenomenon termed the "Cambrian explosion." While most hypotheses address environmental, developmental, and ecological factors that facilitated evolutionary innovations, the biological basis for accelerated emergence of species diversity in the Cambrian period remains largely conjectural. Herein, we posit that morphogenesis by self‐organization enables the uncoupling of genomic mutational landscape from phenotypic diversification. Evidence is provided for a two‐tiered interpretation of genomic changes in metazoan animals wherein mutations not only impact upon function of individual cells, but also alter the self‐organization outcome during developmental morphogenesis. We provide evidence that the morphological impacts of mutations on self‐organization could remain repressed if associated with an unmet negative energetic cost. We posit that accelerated morphological diversification in transition to the Cambrian period has occurred by emergence of dormant (i.e., reserved) morphological novelties whose molecular underpinnings were seeded in the Precambrian period. [ABSTRACT FROM AUTHOR]

The Wenjiaping granite, as one of the few Late Jurassic granites in the Songpan–Garzê fold belt (SGFB), can provide an important clue for comprehensively recognizing the tectonic evolution and mineralization of this belt. In this contribution, we present new age and geochemical data for this pluton to better constrain its petrogenesis and discuss the tectonic and metallogenic implications. LA‐ICP‐MS zircon U–Pb dating shows that the Wenjiaping pluton was emplaced at ~159 Ma. The granite contains minor amphibole, and exhibits slightly peraluminous characteristics (A/CNK = 1.03–1.10) and lower initial Sr–Pb isotope ratios than those of the Liwu Group, which excludes the possibility that the Wenjiaping granite was derived from partial melting of the metasedimentary rock‐dominated Liwu Group as previously suggested. Significantly, high Sr/Y (40.93–54.30), LaN/YbN (39.64–56.64), and K2O/NaO (0.77–1.11) ratios, low MgO (0.47%–0.86%) and Cr (25.1–41.3 ppm) contents, and relatively enriched Sr–Nd–Pb–Hf isotope compositions of the Wenjiaping granite are comparable to those of the Late Triassic adakitic rocks in the SGFB, indicating that they probably share a similar source. Combined with previous researches, we propose that large‐scale detachment of the Jianglang dome caused by post‐collisional lithospheric extension in the SGFB‐induced decompressional partial melting of the Precambrian basement rocks can account for the generation of the Late Jurassic Wenjiaping pluton. In addition, our results also suggest that the Wenjiaping pluton probably cannot supply abundant metal elements for the Liwu‐type Cu‐polymetallic deposits in the Jianglang dome, SGFB. [ABSTRACT FROM AUTHOR]

The Alxa Block is the westernmost part of the North China Craton (NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC. However, the Precambrian basement of the Alxa Block is still poorly studied. In this study, we present new in situ LA‐ICP‐MS zircon U‐Pb and Lu‐Hf isotope data from the Diebusige Metamorphic Complex (DMC) which located in the eastern Alxa Block. Field and petrological studies show that the DMC consists mainly of metamorphic supracrustal rocks and minor metamorphic plutonic rocks and has experienced amphibolite‐granulite facies metamorphism. Zircon U‐Pb dating results suggested that the amphibolite sample yields a crystallization age of 2636 ± 14 Ma and metamorphic ages of 2517–2454 Ma and 1988–1952 Ma, proving the existence of exposed Archean rocks in the Langshan area and indicating that late Neoarchean to Paleoproterozoic metamorphic events existed in the Alxa Block. Two paragneiss samples show that the magmatic detrital zircons from the DMC yield 207Pb/206Pb ages ranging from 2.48 Ga to 2.10 Ga with two youngest peaks at 2.13 Ga and 2.16 Ga, respectively, and they were also overprinted by metamorphic events at 1.97–1.90 Ga and 1.89–1.79 Ga. Compilation of U‐Pb ages of magmatic detrital and metamorphic zircons suggested that the main part of the DMC may have been formed at 2.1–2.0 Ga. Zircon Lu‐Hf isotope data show that the source materials of the main part of the DMC were originated from the reworking of ancient Archean crust (3.45–2.78 Ga). The Hf isotope characteristics and the tectonothermal event records exhibit different evolution history with the Khondalite Belt and the Yinshan Block and the other basements of the Alxa Block, indicating that the Langshan was likely an independent terrain before the middle Paleoproterozoic and was subjected to the middle to late Paleoproterozoic tectonothermal events with the Khondalite Belt as a whole. [ABSTRACT FROM AUTHOR]

Constraints on marine phosphate availability and cycling directly inform our understanding of long‐term biological evolution. However, early Earth phosphate records are sparse, biased toward siliciclastic samples, and susceptible to post‐depositional modification. Well‐preserved shallow marine inorganic carbonate precipitates provide a complementary yet understudied record of phosphate cycling. We combined micro‐X‐ray fluorescence mapping, X‐ray absorption, and Nuclear Magnetic Resonance spectroscopy on samples of Precambrian syndepositional herringbone calcite (HBC) and microspar to characterize phosphorus speciation and distribution in these carbonate fabrics. Phosphorus spectroscopy from synthetic calcite, HBC, and microspar, is qualitatively consistent with a disordered distribution of phosphate. These characteristics are diagnostic of calcite‐hosted phosphate, which is pervasive at low concentrations in HBC and microspar. This study provides evidence that ancient, well‐preserved carbonate fabrics retain phosphate sourced from seawater and highlights the potential for an unaltered archive of marine phosphate concentration over geologic time. Plain Language Summary: Phosphorus is a critical nutrient to sustain life on Earth as we know it. Understanding the form and source of phosphorus on the early Earth will enhance our knowledge of the origins and early evolution of life. However, there is no way to directly measure the source, form and abundance of phosphorus in the environment when life was evolving over 2.5 billion years ago. The rock record provides a potential archive to indirectly measure phosphorus from ancient marine environments, yet there are a number of considerations, for example; (a) which minerals are able to record information about marine phosphorus? (b) How do we know those minerals have not been altered over time? In this work, we have identified well‐preserved, unaltered carbonate minerals from ∼2.5 billion and 800 million years ago, that preserve marine phosphate within their mineral structure using micron‐scale techniques. The characterization of this form of phosphorus is important to our understanding of the evolution of the phosphorus cycle over Earth's history. Key Points: Synchrotron analyses identify calcite‐hosted phosphate in well‐preserved Precambrian carbonate fabricsHerringbone calcite and synsedimentary microspar serve as an unaltered archive for ancient marine dissolved inorganic phosphateMicrite retains abundant apatite mineral micro‐inclusions that may bias bulk calcite‐hosted phosphate or P/Ca records [ABSTRACT FROM AUTHOR]

The central midcontinent of the USA's cratonic platform is a region of low elevation and relief underlain by tectonic basins, domes, faults, and monoclines. To investigate potential correlations among shallow crustal structure and crustal thickness, we produced a high‐resolution Moho‐depth map of the region by applying the recently developed H‐κ‐c receiver‐function method to data from EarthScope Transportable‐Array and Flexible‐Array stations. Results indicate that Moho depth varies from 38 to 57 km. Changes of Moho depth and of Vp/Vs ratios do not correlate with Precambrian tectonic boundaries, suggesting that they reflect post‐accretion tectonics. Deeper Moho underlies sedimentary basins, implying a relationship between crustal thickness and lithospheric subsidence. Thicker crust may be due to rift‐related underplating, and thinner crust may have undergone delamination. Some depth changes underlie known faults and fold zones. Since short‐wavelength undulations were detected only under high‐density seismic arrays, they may occur more widely but have yet to be resolved. Plain Language Summary: Studies of the central midcontinent region of the USA, a portion of North America's relatively stable craton, reveal that both the Moho (the crust/mantle boundary) and the surface of the Great Unconformity (the boundary between crystalline basement and overlying Phanerozoic sedimentary cover) have kilometers of relief, even though land‐surface relief in the region is, at most, 0.5 km. To clarify the nature of variations in Moho depth, so as to make it possible to correlate these variations with other geologic features of the shallow continental crust, we applied a new, more robust, method in estimating Moho depth to data from all available EarthScope seismic stations in the region. This effort yielded a new, high‐resolution map of Moho depth. Significantly, we found large undulations (ups and downs) of the Moho both at the regional scale and at the local scale. Some of these undulations correlate with the boundaries of regional basins and domes, as defined by the depth to the Great Unconformity, and others correlate with known faults. The development of thickness variations may reflect geologic events, such as addition of new rock to the base of the crust, or removal of lower crust, which happened after the crust first formed. Key Points: We applied an improved receiver‐function method in central midcontinent of the U.S. to construct a refined Moho‐depth mapOur results indicate Moho depth variations of different wavelengths, some of which correspond with known geological structuresMoho depth variations cross Precambrian boundaries, suggesting a likely post‐accretion tectonic modification of the lithosphere [ABSTRACT FROM AUTHOR]

The Precambrian–Cambrian unconformity boundary is ubiquitous and globally documented, which is of great significance to studying major global scientific issues such as environmental transition, positions of the supercontinent, Cambrian explosion, and global geochemical cycle. However, few studies have been on the palaeogeographic features and provenance changes of the Precambrian–Cambrian unconformity boundary at the southern margin of North China Craton (NCC). This uncertainty hampers us from further understanding the early climate change and plate evolutionary history of the NCC. To improve the knowledge of the palaeogeographic features and provenance changes of the Precambrian–Cambrian unconformity boundary on the southern margin of the NCC, the Luoquan and Xinji formations at the southern margin of the NCC were selected as the research object integrated with sedimentary petrology, trace elements, and detrital zircon geochronology investigation. The results suggest a depositional gap between the Luoquan and Xinji formations. The former is glacial to deglaciation deposits, while the latter is shallow to coastal sediments. Compared with the sedimentary stratum of the South China Craton, the Luoquan Formation lacks at least one transgression and regression cycle. The Xinji Formation has detrital zircon age peaks of 1200, 1100, and 950 Ma, unavailable in the Luoquan Formation. The provenance areas of the Luoquan and Xinji formations have changed, indicating that the provenances of the Luoquan Formation belong to the NCC and part of the provenances of the Xinji Formation belong to the North Qinling Terrane (NQT). The trace element data indicate that the tectonic setting of the Luoquan and Xinji formations has changed from a continental island arc to a passive continental margin. It is suggested that the NCC be involved in the evolution of Rodinia supercontinent, which leads to the change of the provenance and tectonic setting. This research provides an explanation for the Precambrian–Cambrian tectonic history, basin development, stratigraphic correlation, and palaeogeographic reconstruction of NCC. [ABSTRACT FROM AUTHOR]

The Kongling terrane (Huangling dome) outcrops Precambrian metamorphic basement of the Yangtze craton. However, the Precambrian tectonic evolution of the southern Kongling terrane remains poorly constrained. In this contribution, we report zircon geochronology of the metasedimentary rocks from southern Kongling terrane of the Yangtze craton. Zircon U‐Pb dating results yielded magmatic age clusters at ca. 3,000 Ma, ca. 1,520 Ma, ca. 1,150 Ma, ca. 860 Ma, 900–920 Ma, and 980 Ma, and metamorphic age at ca. 2,900 Ma. These data display that the southern Kongling terrane witnessed Mesoarchean magmatism and metamorphic event, Mesoproterozoic and Neoproterozoic magmatism. In combination with previous studies, it is proposed that the Precambrian metamorphic basement of the Yangtze craton was amalgamated by the multi‐stage subduction‐collision processes at ca. 3,000–2,900 Ma, ca. 2,000–1,800 Ma, and ca. 1,100–940 Ma. In addition, the Proterozoic processes were related to the assembly and breakup of Columbia and Rodinia supercontinents. Key Points: The southern Kongling terrane of the Yangtze craton witnessed ca. 3,000 Ma magmatic and ca. 2,900 Ma metamorphic eventsThe SKT experienced Mesoproterozoic and Neoproterozoic magmatism causing by the breakup and amalgamation of the Precambrian supercontinentsThe Precambrian metamorphic basement of the Yangtze craton was formed by multi‐stage subduction‐collision processes [ABSTRACT FROM AUTHOR]

The Mesoproterozoic Baoban Group is the oldest basement in Hainan Island and has played an important role in Columbia (Nuna) supercontinent reconstructions. The Mesoproterozoic granitic intrusions in the Baoban Group are the most widely‐exposed Precambrian magmatic rocks and are the key to understanding the tectonic settings of Hainan Island and its relationship with the South China Block and the Columbia supercontinent. New LA‐ICP‐MS zircon U‐Pb dating on three mylonitic granite samples from the Tuwaishan and Baoban areas yield ages ranging from 1447 Ma to 1437 Ma, representing the absolute timing of the emplacement of the granitic intrusions. Combined with previously published geochronological data for rocks from the Baoban Group and regional mafic intrusions, it is concluded that the Baoban Group formed at 1460–1430 Ma, coeval with the emplacement of the granitic and mafic intrusions. New in‐situ zircon Lu‐Hf isotope analyses for the three mylonitic granite samples yielded positive ∊Hf(t) values, ranging from +0.49 to +8.27, with model ages (TDMC) ranging from 2181 Ma to 1687 Ma, suggesting that the granitic intrusions originated from a mixed source of Paleoproterozoic crust with juvenile crust. New zircon trace element data show characteristics of high Th/U values of 0.24–1.50, steep slopes from LREE to HREE and negative Pr, Eu anomalies with positive Ce, Sm anomalies, representing typical magmatic zircons formed in continental crust. Compared with available magmatic and detrital zircon ages from Precambrian rocks in the Cathaysia Block, Yangtze Block and western Laurentia, it is inferred that Hainan Island was separated from both the Cathaysia Block and the Yangtze Block, instead being connected with western Laurentia in the Columbia supercontinent. Considering the decreasing tendency of basin deposition time along the western margin of Laurentia, it is proposed that Hainan Island was located to the north or northwest of the Belt‐Purcell Supergroup, along the western margin of Laurentia, during the breakup of the Columbia supercontinent. [ABSTRACT FROM AUTHOR]

We have developed a 3‐D shear velocity (Vsv) model of Precambrian terrains of South India with a lateral resolution of 55 km to a depth of 250 km by inversion of fundamental mode Rayleigh wave phase velocity dispersion data in the period of 30–140s, combined with a well‐constrained crustal velocity model from an earlier study. The dispersion data were computed from 748 earthquakes recorded at 85 homogeneously distributed seismographs. Our velocity model shows 150–200 km thick lithosphere in most of the Archean Dharwar craton where Vsv is >4.7 km/s in the depth of 50–100 km and progressively decreases to 4.6 km/s at 120–150 km followed by a constant velocity of 4.5 km/s beyond 150–200 km depth. It correlates well with the results of the petrological studies of kimberlite xenoliths. An extraordinary high shear velocity (up to 4.8 km/s) and thick lithosphere (150 km) are observed beneath the Proterozoic Carbonatite complex, located at the south‐eastern edge of the Dharwar craton. We infer compositional modification of lower lithosphere at the south‐western margin of the Dharwar craton and lithospheric erosion at the Granulite terrain both possibly due to interaction with the Marion mantle plume at ∼90 Ma. The region is underlain by a 2%–3% lower velocity channel at ∼180–220 km depth in the asthenosphere, uncorrelated with the overlying lithosphere, possibly due to relative motion between them. It may be attributed to deep Earth‐processes such as asthenospheric upwelling. Plain Language Summary: South India, comprising the Archean Dharwar craton, Proterozoic Cuddapah basin and Neoproterozoic‐Cambrian Granulite Terrain holds a continuous record of continent evolution since 3.36 Ga. As part of the Scalavia supercontinent ca. 2.6–2.2 Ga, it experienced multiple Wilson cycles of terrain amalgamation and rifting, most recent being India‐Madagascar separation at 90 Ma due to interaction with the Marion mantle plume. It is an excellent site to study craton formation/evolution, effect of mantle plumes on Archean/Proterozoic lithosphere and Proterozoic evolution of metamorphic terrains. We have mapped 3‐D shear wave velocity structure of South India using surface wave imaging at much higher resolution than prior studies. We observe the presence of thick (150–200 km) continental lithosphere below a significant part of Dharwar craton with similar lithosphere beneath Granulite terrain and Proterozoic Carbonatite complex. Due to interaction with the Marion mantle plume, the lower lithosphere below south‐western Dharwar craton is compositionally modified in contrast to thermal erosion of the same below most of Granulite terrain. We observe two opposite surface manifestations of the modified/thinned lithosphere; low heat flow (32 mW/m2), low topography (500 m) at south‐western Dhawar craton and higher surface heat flow (45 mW/m2), higher elevation (over 1,000 m) at the Granulite terrain. Key Points: High‐resolution 3D shear velocity model of the upper mantle of South IndiaSignatures of preserved and modified Archean lithospheres of Dharwar cratonThick craton like lithosphere below Proterozoic carbonatite complex [ABSTRACT FROM AUTHOR]

Apatite is increasingly used in sedimentary provenance studies. However, detrital apatite U–Pb geochronology can be challenging due to the presence of non‐radiogenic Pb, its intermediate closure temperature (~350–550°C) and/or age‐resetting by metamorphic/metasomatic processes. The Lu–Hf system in apatite has a higher closure temperature (~675–750°C) and is, therefore, more robust to thermal resetting. Here we present the first detrital apatite Lu–Hf age spectra. We have developed a laser‐ablation Lu–Hf dating technique, using reaction‐cell mass spectrometry, that allows rapid cost‐effective analysis, required for detrital apatite studies. The method is best suited to Precambrian detritus, permitting greater radiogenic Hf ingrowth. Using samples from Siberia, we demonstrate: (1) excellent correlations between U–Pb and Lu–Hf dates for apatites from igneous protoliths; and (2) that Lu–Hf dating can detect primary age information in metamorphic grains. Hence, when used in tandem with U–Pb zircon and apatite geochronology, Lu–Hf apatite dating provides a powerful new tool for provenance studies. [ABSTRACT FROM AUTHOR]

Deciphering the tectono‐metamorphic evolution of Precambrian terranes can be difficult due to reworking by later superimposed events. Whole‐rock elemental and isotopic geochemistry and zircon U–Pb geochronology are often employed in those studies, but these approaches are often not sensitive to the presence of multiple events and medium‐grade metamorphic episodes. The Rio Apa Terrane (RAT), an allochthonous fragment of the Amazonian Craton, is a crustal block with a well‐characterized crustal evolution but with no detailed thermal constraints for its tectono‐metamorphic evolution. In contrast to previous studies, we show the existence of four tectono‐metamorphic events at c. 1,780, c. 1,625, c. 1,420–1,340, and c. 1,300–1,200 Ma on the basis of apatite, titanite, and rutile U–Pb, in situ white‐mica Rb–Sr, and in situ garnet Lu–Hf geochronology combined with mineral chemistry and phase‐equilibria modelling. The c. 1,780 Ma event is recorded in the basement of the Western domain, representing an extensional event coeval with the development of its Eastern domain in response to the retreat stage of the accretionary system. This is followed by juxtaposition of the Western and Eastern domains along a major crustal boundary at c. 1,625 Ma, which is defined by the magnetic profiles and zircon U–Pb–Hf data across the boundary. The third and fourth events correspond to progressive high‐pressure/medium‐temperature (HP/MT) metamorphism, characterized by an anticlockwise P–T path, suggesting a convergent‐to‐collisional tectonic setting. The RAT was accreted to the adjoining Paraguá Terrane at c. 1,420–1,340 Ma under an isobaric P–T evolution spanning ~530°C to 600°C and ~10.0 kbar. Subsequently, the combined Rio Apa and Paraguá terranes collided with the SW Amazonian Craton at c. 1,300–1,200 Ma, reaching P–T conditions of ~560–580°C and ~10.9–11.7 kbar during crustal thickening. This study reveals for the first time the existence of a HP/MT metamorphic evolution related to the growth of the SW Amazonian Craton as part of an accretionary orogenic system during Rodinia assembly in the Palaeoproterozoic to Mesoproterozoic. [ABSTRACT FROM AUTHOR]

Although many studies focus on catchment classification, hydrologists are challenged to find the most important variables for a meaningful catchment classification, especially in the heterogeneous environment of the Precambrian Shield. This study investigates landscape controls on hydrologic response by conducting a catchment classification of 26 catchments located within two Precambrian Shield watersheds (Sturgeon–French–Nipissing [SNF] and Muskoka) in central and Northeastern Ontario, Canada, using combinations of landscape characteristics (e.g. topography, geology, landcover), hydrometric variables, and stable isotopes of δ18O and δ2H in river flow. Weekly to monthly surveys of δ18O and δ2H in river flow were collected between 2013 and 2019. Flow metrics (e.g. Pardé coefficient and coefficient of variation of streamflow) were generated for 14 of the 26 rivers between 2008 and 2018. Principal component analyses (PCA) and Hierarchical Clustering on Principal Components (HCPC) analyses were used to identify variables controlling catchment clustering according to their similarities for four different scenarios. Despite their similar location along the southern edge of the Precambrian Shield, the 26 catchments generally clustered by watershed (SNF and Muskoka) with some exceptions. Differences in wetland and lake area (%), mean slope, and % area covered by glacialacustrine and glaciofluvial outwash deposits were the most influential variables in catchment classification. A positive correlation between % wetland area and streamflow stable isotope damping ratios suggests greater % wetland area (with shallow and potentially seasonally variable surface areas and/or hydrologic connection) observed in the SNF catchments increases variability in the influence of evaporative enrichment in SNF catchments. The catchment classification analyses in combination with stable isotopes of δ18O and δ2H were functional tools to investigate the combined influences of diverse types of catchment characteristics that lead to differences in hydrometric response. These results could support future studies focusing on generating hydrologic models and representing wetlands connectivity in the region. [ABSTRACT FROM AUTHOR]

Stromatolites and microbialites contain a rich repository of environmental and biological information. Despite extensive research, questions remain regarding the biological, chemical, and physical processes that control stromatolite macro, meso, and microstructure. We report unusual deep water cuspate stromatolites from the Cryogenian Trezona Formation, South Australia, from a mixed siliciclastic–carbonate open marine ramp setting. Cuspate stromatolite horizons develop near the base of decameter‐scale transgression–regression cycles and typically overlie decimeter‐scale irregular erosion surfaces. The cuspate structure within the stromatolites form near vertical, stacked cusp structures in cross section. In plan view, the cusps form cm‐scale sharp parallel ridges oriented perpendicular to the regional downslope direction and perpendicular to the elongation direction of stromatolites. Stromatolites colonized topographic highs of irregular erosion surfaces (often hardgrounds) and grew in carbonate supersaturated, iron‐rich marine waters in low turbidity sediment‐starved settings. Cuspate stromatolites are interpreted as forming in deep water environments during maximum transgression as condensed intervals. Their microbial metabolism may require low light and low oxygen. A deep water origin for the Trezona Formation cuspate stromatolites and other Precambrian cuspate stromatolites suggests a link between the cuspate morphology and physical/chemical (carbonate supersaturated, low light, and low oxygen) conditions of Precambrian deep water marine settings. [ABSTRACT FROM AUTHOR]

Metamorphic P–T conditions, monazite chemical ages and zircon U–Pb ages from the gneisses exposed in the Oki belt, Japan, were integrated to unravel the multi‐stage metamorphic history of the belt. Microstructural observations combined with obtained P–T conditions and metamorphic ages reveal three distinct stages of metamorphism: M1, M2 and M3. The M1 stage occurred c. 1.85 Ga with high‐T granulite‐facies metamorphism (793–803°C and 9.8–12.3 kbar and 738–755°C and 9.1–12.0 kbar in the southwestern and southeastern Oki gneisses, respectively). The age of the M1 stage is well recorded in monazites included in large garnet porphyroblasts and low Th/U metamorphic rims in zircons from the Oki gneisses. The M1 metamorphism was overprinted by c. 230 Ma metamorphism (M2), which occurred at granulite‐facies conditions (817–829°C and 9.0–10.3 kbar) in the southwestern Oki gneisses and at upper amphibolite‐facies conditions (693°C and 5.3 kbar) in the southeastern Oki gneisses. Monazites in small garnets, euhedral zircons and outermost rims of zircons crystallized during this stage. The final metamorphism occurred as retrograde amphibolite‐facies recrystallization (M3) at conditions of 558–638°C and 3.7–4.8 kbar. The inherited cores in zircons yield ages from Paleoarchean to Paleoproterozoic but lack Palaeozoic ages. The detrital zircon distribution and the Paleoproterozoic metamorphic event in the Oki belt support the idea that the Oki gneisses are fragments of a Precambrian terrane rather than Palaeozoic sediments derived from the terrane. Combined with previous studies, we concluded that the c. 1.85 Ga M1 high‐T granulite‐facies metamorphism in the Oki belt could be related to that of the Jiao‐Liao‐Ji belt in the eastern North China block via the northern Gyeonggi and Nangrim Massifs on the Korean Peninsula, whereas the c. 250–230 Ma M2 stage could be associated with collision between the North and South China blocks. The Oki belt geologically corresponds to the northern Gyeonggi Massif in South Korea due to their similar Paleoproterozoic and Triassic tectonothermal events. [ABSTRACT FROM AUTHOR]

This is a review of the formation and tectonic evolution of the continental Asia in Phanerozoic. The continental Asia has formed on the bases of some pre‐Cambrian cratons, such as the Siberia, India, Arabia, North China, Tarim, South China, and Indochina, through multi‐stage plate convergence and collisional collages in Phanerozoic. The north‐central Asia had experienced the expansion and subduction of the Paleo‐Asian Ocean (PAO) in the early Paleozoic and the closure of the PAO in the late Paleozoic and early Mesozoic, forming the PAO regime and Central Asian orogenic belt (CAOB). In the core of the CAOB, the Mongol‐Okhotsk Ocean (MOO) opened with limited expansion in the Early Permian and finally closed in the Late Jurassic–Early Cretaceous. The south‐central Asia had experienced mainly multi‐stage oceanic opening, subduction and collision evolution in the Tethys Ocean, forming the Tethys regime and Himalaya‐Tibetan orogenic belt. In eastern Asia, the plate subduction and continental margin orogeny on western margin of the Pacific Ocean, forms the West Pacific regime and West Pacific orogenic belt. The PAO, Tethys, and West Pacific regimes, together with Precambrian cratons among or surrounding them, made up the major tectonic and dynamic systems of the continental Asia in Phanerozoic. Major tectonic events, such as the Early Paleozoic Qilian, Uralian, and Dunhuang orogeneses, the late Paleozoic East Junggar, Tianshan and West Junggar orogeneses, the Middle to Late Permian Ailaoshan orogeny and North‐South Lhasa collision, the early Mesozoic Indochina‐South China and North‐South China collisions, the late Mesozoic Mongolia‐Okhotsk orogeny, Lhasa‐Qiangtang collision, and intra‐continental Yanshanian orogeny, and the Cenozoic Indo‐Asian, Arab‐Asian, and West Pacific margin collisions, constrained the formation and evolution of the continental Asia. The complex dynamic systems have left large number of deformation features, such as large‐scale strike‐slip faults, thrust‐fold systems and extensional detachments on the continental Asia. Based on past tectonics, a future supercontinent, the Ameurasia, is prospected for the development of the Asia in ca. 250 Myr. [ABSTRACT FROM AUTHOR]

Since the early 1970s, the Dorset Environmental Science Centre (DESC) research catchments have been home to long‐term monitoring and study of terrestrial headwater catchment processes, their linkages to inland aquatic ecosystems and the influence of both natural variation and human activities. Located on the Precambrian Shield in central Ontario, Canada, covered by mixed Great Lakes‐St. Lawrence forest, the 29 catchments, defined by inflows and outflows to eight lakes, have been monitored for streamflow, meteorology and water chemistry, with long‐term datasets spanning from 1976 to the present. These datasets have provided insights into cold region hydrologic processes such as runoff generation, wetland and groundwater–surface water interactions, snow and ice processes, and catchment linkages to lake nutrient budgets and ecology. The datasets have supported catchment transit time estimates, hydrological modelling and cold region intercomparison studies. Starting with early research efforts driven by concerns over impacts from cottage development and acid deposition on soils, rivers and lakes, the DESC catchment datasets have supported study of impacts of stressors of forest harvesting, calcium depletion, road salt application and climate change. Ongoing monitoring of streamflow, meteorology and water chemistry in the DESC catchments continues to offer unique opportunities for investigation of critical zone processes in Precambrian shield catchments, their model representation and anthropogenic impacts. [ABSTRACT FROM AUTHOR]

Many Ediacaran macrofossils are apparently composed of unique pneus (similar, repetitive tubular modules) forming a variety of body shapes by combinations of modular growth regimes. The large‐scale disappearance of Ediacaran macro‐organisms at the end of the Precambrian leaves this now extinct modular body plan only rarely reported from the Cambrian onwards. Mackenzia costalis is an enigmatic and poorly understood soft‐bodied organism from the middle Cambrian, and is a possible surviving member of the Ediacaran macrobiota. Here, we describe a new mackenziid, Paramackenzia canalifera, from the early Cambrian Chengjiang biota, Yunnan Province, south‐west China. It has a body plan comprising longitudinal tubular modules that are radially arranged to form a cylindrical body with a basal attachment. Each tubular module is enclosed by an inner and outer concentric membrane, separated from adjacent modules by a thin lamellar sheet. Infilling sediment and preservation of dark, basal stains at the inner and outer membranes reveal a pore–canal system within the lamellae, connecting the internal cavity to the exterior. This arrangement of tubular modules is similar to that of several macroscopic Ediacaran species, including erniettomorphs and dickinsoniomorphs, which were constructed of serial hydrostatic modules referred to as 'pneus'. The mackenziid pore system is similar to that of sponges and archaeocyathids in function and feeding strategy, but the overall anatomy precludes affiliation to this phylum. We suggest that mackenziids are most likely to be a blastic or diploblastic anatomical grade of stem eumetazoans, similar to other modular Ediacaran macro‐organisms. [ABSTRACT FROM AUTHOR]

The development history of high topography in the northeastern (NE) Tibetan Plateau is essential to test various plateau growth models and understand plateau construction. We present integrated provenance data from the NE Qaidam Basin, south of the Qilian Shan. Results show an increase in carbonate lithics, an increase in Al2O3/SiO2 ratios, a negative shift in εNd values and an appearance of large amounts of Precambrian zircon grains in the period of ca. 13–8 Ma, arguing that the sediment source of the NE Qaidam Basin may have shifted from the East Kunlun Shan to the Qilian Shan during this time interval. We infer that significant topographic growth of the southern Qilian Shan occurred during the middle‐late Miocene. Along with widespread middle to late Miocene deformation records across the Qilian Shan and abruptly shifts on provenance, sedimentary facies and climate indexes in its surrounding basins, present high topography of the NE Tibetan Plateau may have been established since the middle‐late Miocene. [ABSTRACT FROM AUTHOR]

Crystalline basement and Precambrian crustal growth of the continental massifs within the Central Asian Orogenic Belt (CAOB) are still pending problems. Our geological and geochemical investigations identified an Archean (2606 Ma) granitic pluton in the Biliya area of the Erguna Massif. The Neoarchean granitoids show high and positive in‐situ zircon ∊Hf(t) (+0.3 to +10.0), whole‐rock ∊Nd(t) (+4.8) and whole‐rock ∊Hf(t) values (+2.1). They are characterized by high Y + Ce + Zr + Nb (> 220 ppm) and Zr contents and could be classified as A‐type granites. These granitoids are characterized by high Zr saturation temperatures (TZr) (796–836°C). They were derived from partial re‐melting of juvenile mafic lower crust in an intracontinental back‐arc extensional environment. This newly identified Neoarchean granitic pluton may represent the crystalline basement of the several continent massifs within the CAOB, and their high ∊Hf(t)–∊Nd(t) values may also indicate the occurrence of lateral crustal growth events in these massifs during the Neoarchean. [ABSTRACT FROM AUTHOR]

The Late Precambrian Wufoshan Group from the southern North China Craton (NCC) is significant for its contribution to our understanding of the Precambrian evolution of the NCC, which consists of the Lower Ma'anshan, Upper Ma'anshan, Puyu, Luotuopan, and Hejiazhai formations. Detrital zircon U–Pb ages and Lu–Hf isotopes from the Puyu, Luotuopan, and Hejiazhai formations are used in this study to constrain the depositional age and provenance of the Wufoshan Group and crustal evolution of the NCC. The Puyu Formation is characterized by detrital zircon U–Pb age populations of ~2.13 Ga and ~2.50 Ga, similar to the Lower–Upper Ma'anshan formations from the literature. The Luotuopan Formation exhibits age populations of 1.85–2.18 Ga and 2.28–2.98 Ga, with mainly negative εHf(t) values and scattered positive εHf(t) values clustering at two groups of 2.48–2.52 Ga and 2.64–2.97 Ga. The Hejiazhai Formation displays age populations of 0.98–2.00 Ga and 2.51–2.79 Ga with mainly positive εHf(t) values, whose depositional age is constrained as Neoproterozoic era by the youngest graphical detrital zircon age of 976 ± 20 Ma. Provenance studies indicate that the Mesoproterozoic Lower–Upper Ma'anshan and Puyu formations were sourced from the middle Trans‐North China Orogen (TNCO), while the Neoproterozoic Luotuopan and Hejiazhai formations were derived from the southern TNCO and the North Qinling Terrane, respectively. The clastic rock series in the southern NCC is divided into Luotuopan type and Hejiazhai type by detrital zircon U–Pb age pattern and Hf isotopic characteristics, suggesting Late Mesoarchean to Early Palaeoproterozoic (2.47–2.97 Ga) crustal growth in the interior NCC, and Late Palaeoproterozoic to Early Neoproterozoic (0.98–2.08 Ga) crustal growth in the marginal NCC. The crustal evolution of the NCC can be classified into three stages, namely >3.0 Ga continental nuclei generation, the Meso‐Neoarchean massive growth, and the Palaeo‐Mesoproterozoic interior reworking and marginal growth. [ABSTRACT FROM AUTHOR]

The Great Unconformity between the Precambrian basement and the Phanerozoic successions marks a major gap in the stratigraphic records globally. However, previous studies on the time, magnitude, and the spatial distribution of this unconformity in the North China Craton (NCC) mainly focused on the south‐eastern margin and were seldom investigated in the central area. In this study, we report detrital zircon geochronological data of the Huoshan Formation, a siliciclastic stratigraphic unit between the Archean‐Palaeoproterozoic metamorphic basement and Cambrian successions in the central NCC. The youngest age peak of 685 Ma suggests that the Huoshan Formation was formed in the post‐Ediacaran rather than the counterpart of the lower Palaeo‐Mesoproterozoic Changcheng Group. The detrital zircons of the quartz sandstone from the Huoshan Formation show varied age populations of 2,700–2,600 Ma, 2,600–2,500 Ma, 2,200–2,000 Ma, 1,900–1,800 Ma, and 700–600 Ma, which correspond to typical tectono‐thermal events of the NCC. First, the widely developed Precambrian tectono‐thermal events in the NCC were archived in the detrital zircons in the Huoshan Formation, for instance, the crustal growth event at 2,600–2,500 Ma and the 1,850–1,800 Ma magmatic and metamorphic events. Second, the age peaks younger than 1,000 Ma are not distinct in the NCC and are possibly from other terranes. The Great Unconformity represented by the boundary between the Huoshan Formation and the underlying Archean‐Palaeoproterozoic basement suggested a high topography and long‐term denudation in the Lüliang area during the transition from the Proterozoic to the Phanerozoic. [ABSTRACT FROM AUTHOR]

In East Greenland, sedimentation during the Middle Devonian‐earliest Carboniferous interval was characterized by the Old Red Sandstone Molasse Basin deposits. The continental succession recorded folding and intrabasinal unconformities associated with the activation of extensional detachments and core complex formation which post‐dated high‐P granulite facies metamorphism at c. 403 Ma. The extensional collapse responsible for the initiation of the Devonian basin and associated bimodal magmatism must be understood in the context of continued continental convergence during the Early Carboniferous, required by ultrahigh‐pressure metamorphism in North‐East Greenland at c. 355 Ma. Along a small nunatak within the Wordie Gletscher in Payer Land, NE Greenland (lat. 74°N), Precambrian gneisses recording Devonian granulite‐facies metamorphism are in tectonic contact with the molasse deposits along an ESE‐ward dipping thrust fault: the Scotstounhill Thrust. This paper will discuss the role of Devonian contractional structures and contemporaneous extensional faulting and present a new tectonic model that accounts for the exhumation of deep crustal rocks by these coupled mechanisms. [ABSTRACT FROM AUTHOR]

The Cimmerian Terrane, part of which forms the Central Iranian Plateau, is one of several continental fragments produced during the early‐ to mid‐Palaeozoic breakup of the northern margin of Gondwana. Magmatic evidence for the final separation of the Terrane from Gondwana and formation of the intervening Neo‐Tethys Ocean is preserved in the Misho Mountains SW of Marand, NW Iran. A small (~30 km2) body of subalkaline granite intruding Precambrian sedimentary rocks of the Kahar Formation has numerous chemical features that identify it as an A‐type granite, including high Ga/Al, K2O + Na2O, FeOt/(FeOt + MgO) and incompatible elements (LILE and HFSE), and low CaO and P2O5. Such features are consistent with the asthenospheric upwelling above a rising mantle plume. Zircon ages of 350.8 ± 3.0, 345.4 ± 3.2, and 343.6 ± 4.0 Ma measured on three samples of the Misho A‐type granite along with the same granites exposed in the western domain (Herris area, ~306 Ma) reveal that the crystallization process occurred sequentially in different stages. The obtained ages record detachment of the Cimmerian Terrane from Gondwana and the initiation of Neo‐Tethys at least in the Early Carboniferous, significantly earlier than previous researchers have proposed. [ABSTRACT FROM AUTHOR]

Several ribbon‐like continental fragments with Precambrian basement were wrapped within Palaeozoic accretionary complexes in the southwest Central Asian Orogenic Belt (CAOB). Their origins and tectonic evolution are essential for understanding the accretionary orogeny of the CAOB and crustal growth versus continental reworking in Phanerozoic. The southern Yili Block in NW of China is one of the major continental fragments in SW CAOB. In order to better constrain the tectonic settings of the Precambrian basement of the southern Yili Block, we present new data of field structures, whole‐rock geochemical compositions, zircon U–Pb ages and Lu‐Hf isotopic ratios of the Neoproterozoic gneissic granites. Ductile deformation characterized by mylonitic foliations and stretching/mineral lineation is commonly recognized in the gneissic granites, which were cross‐cut by undeformed granitoids and mafic dykes. The gneissic granites yielded zircon U–Pb ages of 968 ± 5 Ma, 948 ± 8 Ma, and 873 ± 9 Ma. These gneissic granites show geochemical features of high potassium, peraluminous, calc‐alkaline series, enrichment of Th, K, Rb and depletion of Ba, Nd, Sr. They show zircon εHf(t) values from −5.5 to 2.0 and two‐stage zircon Hf model ages between 1.7 and 2.1 Ga. These new results indicate that the Neoproterozoic gneissic granites in the southern Yili Block derived from partial melting of meta‐greywackes that most likely had formed in a continental arc setting. A comparison of stratigraphy, magmatism and detrital zircon ages suggests that the southern Yili Block is similar with the northern Yili Block and Chinese Central Tianshan Block in term of Precambrian basement, and these continental fragments might have originated from Neoproterozoic orogenic belts. [ABSTRACT FROM AUTHOR]