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New isotopic data are presented in this paper that make it possible to determine the stratigraphic position of the Talja Formation on the regional stratigraphic scale of the Early Precambrian. The U‒Th‒Pb age of 1926 ± 7 Ma obtained for the first time for metarhyodacites of the Talja Formation indicates that this formation is coeval to the Kaskama Formation, which, together with the similar isotope–geochemical composition of the type varieties of the Kaskama and Talja formations (komatiitic basalts, aluminous metabasalts, and metarhyodacites), significantly expands the understanding of the extent of the area composed of the Paleoproterozoic Kalevian Superhorizon within the Kola–Norwegian region of the Fennoscandian shield. [ABSTRACT FROM AUTHOR]

Macrofossils of the Vendian soft-bodied organisms were found for the first time in the Vizinga and Ust'-Palega formations of the Upper Precambrian in Chetlasskii Kamen Hill (Middle Timan, Arkhangelsk oblast). Representatives of palaeopascichnids, aspidellamorphs, and possible frondomorphs, trace fossils, and microbially induced arumberiamorph structures were identified among molds and three-dimensional casts of fossils. Previously we revealed Vendian macrofossils in the Upper Precambrian in Dzhezhim-Parma Hill (South Timan, Komi Republic). The discovery of one more locality of various Ediacaran fossils in the middle part of the Timan Ridge significantly expands their paleogeography and also clarifies the time frame of deposition of the Vizinga and Ust'-Palega formations, the position of which in the Upper Precambrian section of Central Timan was debatable. [ABSTRACT FROM AUTHOR]

Many intracontinental basins form as broad depressions through prolonged, slow subsidence of the continental lithosphere. Such long-lived basins can record lithospheric processes over hundreds of millions of years, serving as important archives of lithospheric evolution. Since continental amalgamation in the Mesoproterozoic, the lithosphere beneath the intracontinental Canning Basin has been subject to several tectonic events, with extensive crustal reworking evidenced through different upper crust data sets. However, knowledge of the structure of the subcontinental lithospheric mantle is lacking. As a consequence, understanding the coupled evolution between surface and deep lithospheric processes, crucial to resolving basin formation, development and survival, remains problematic. Here, we combine geochemical, geophysical and petrophysical data within a thermodynamic modelling framework to determine the thermochemical properties, rheology, density and seismic structure of the lithospheric and sublithospheric mantle beneath the Canning Basin. The results indicate a thick, rigid lithosphere with a maximum thickness of 185 km and strength of ca. 1 × 1013 Pa m, and an anomalously Fe-enriched subcontinental lithospheric mantle with a Mg# of 88.6. This mantle structure is not consistent with pre-collisional fragments or a Precambrian collisional setting and may reflect magmatic refertilization during high-volume mafic magmatic events. Potential candidate events are the ∼1070 Ma Warakurna, ∼825 Ma Gairdner and ∼510 Ma Kalkarindji Large Igneous Provinces. The youngest of these is temporally and spatially correlated with and therefore interpreted to have influenced the Canning Basin formation. We propose that refertilization caused a negatively buoyant subcontinental lithospheric mantle and prolonged subsidence and preservation of the basin, while the strong lithosphere ensured lithospheric stability and longevity. [ABSTRACT FROM AUTHOR]

The two basic approaches to elucidating how life began both date from Darwin. The first, that of the experimentalists, stems from Darwin's famous "warm little pond" letter to Joseph Hooker of 1871. This approach, an attempt to replicate the sequential events leading to life's origin, is exemplified by the "primordial soup" hypothesis of A.I. Oparin (1924) and J.B.S. Haldane (1929); the Miller–Urey laboratory synthesis of amino acids under possible primitive Earth conditions (1953); and Joan Oró's nonbiological synthesis of the nucleic acid adenine (1959). The second approach, that of the observationalists who search for relevant evidence in the geological record, dates from Darwin's 1859 On the Origin of Species, in which he laments the "inexplicable" absence of a pre-Cambrian fossil record. Darwin's concern spurred a century of search that was ultimately rewarded by Stanley Tyler's 1953 discovery of diverse microscopic fossils in the ~1900 Ma Gunflint Chert of southern Canada. Tyler's find was soon followed by a cascade of discoveries worldwide; the establishment of a new field of science, Precambrian paleobiology; and, more recently, the discovery of 3400 and ~3465 Ma Paleoarchean microfossils, establishing that primordial life evolved early, far, and fast. Though progress has been made, much remains to be learned in the foci of this Origin of Life 2024 volume, for which this essay is the history-reviewing "stage setter". [ABSTRACT FROM AUTHOR]

The complex body-trace fossils of Vendian soft-bodied biota have been found for the first time in the Central Urals during the study of the Vilukha and Sinii Kamen members of the Chernyi Kamen Formation of the Upper Vendian Sylvitsa Group (Kos'va River area, Perm Krai of Russia). These sedimentary sequences were exposed along the valley of the Shirokovskii Reservoir. Among the fossils, the chuariomorpha-like species Beltanelliformis konovalovi, previously described from the Konovalovka Member of the Chernyi Kamen Formation, was identified. However, the morphological analysis of the new fossil material revealed a number of principal differences from representatives of the genus Beltanelliformis Menner, 1974. It was shown that the taxon B. konovalovi, most likely, does not belong to this genus and probably needs further revision, and, in turn, the fossil locality at the Shirokovskii Reservoir allows us to establish a new area with fossils of the Precambrian mobile organisms. [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]

The provenance of Precambrian detritus in the Junggar and Altai terranes provides crucial constraints on the peri-Siberian accretionary tectonic evolution in the middle Paleozoic. The Precambrian detrital zircons have no coeval magmatic equivalents in the Junggar terrane but show U–Pb age spectra and εHf(t) values comparable to those in the Altai terrane. The correlations suggest that the old detrital materials in the Junggar and Altai terranes were most likely derived from the Siberia craton and adjacent Tuva-Mongolian microcontinent. Paleozoic zircons in the Junggar terrane display a εHf(t) pattern from large spread to dominantly positive values at ca. 420–410 Ma. Such an abrupt change points to an accretionary tectonic transition from an advancing to retreating mode during mid-Paleozoic time, synchronous with similar tectonic switch occurring in the Altai terrane. Taking into account the temporal and spatial relations in sedimentation, tectonism and arc magmatism, we propose that the Junggar terrane had once collided onto the peri-Siberian Altai terrane to receive abundant old detritus from the Siberian continent in the Silurian–early Devonian. They were subsequently separated at ca. 420–410 Ma, possibly due to the slab rollback of the subducting Paleo-Asian Ocean (PAO) plate. These results constrain an Early Paleozoic tectono-paleogeographic boundary of the CAOB along the North Tianshan–Solonker suture zone, and also imply a long-lived PAO subduction was responsible for the Neoproterozoic to Paleozoic accretionary orogenesis at the margins of southern Siberia, eastern Kazakhstan, and northern Gondwana. [ABSTRACT FROM AUTHOR]

Abstract 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.

The Shunbei 5 (SB5) strike-slip fault, situated in the central Tarim basin, is distinguished by its considerable length, significant variations in planar orientation, and intricate multi-stage tectonic evolution. This study delves into the geometric, kinematic, and dynamic features of both the southern and northern parts of the SB5 fault, utilizing the latest seismic data from the Fuman Oilfield, and examines the factors influencing the fault's planar deflection. The fault can be categorized into three structural deformation layers based on lithological features and fault features: the deep structural deformation layer below TЄ3), characterized by basement rifting and limited strike-slip activity; the middle structural deformation layer (TЄ3-TO3), marked by vigorous strike-slip movements and the dominance of flower structures; and the shallow structural deformation layer (TO3-TP), featuring echelon-type normal faults and boundary graben faults, specifically in the southern SB5 fault. The fault activity is more pronounced in its southern SB5 fault compared to the northern, with the weakest activity at the TЄ 3 interface and the peak at the TO3 interface. The southern SB5 fault transitions to sinistral slip at the TO3 interface, while the northern SB5 fault shifts from dextral to sinistral slip at the TC interface, highlighting variable slip directions across different interfaces. Rifts are extensively distributed within the Precambrian basement along the SB5 fault. The initial strike-slip fault rupture, which is primarily localized in these areas, exerts a significant influence on the formation of the S-shaped fault plane. This process involves four distinct evolution stages: the embryonic stage of strike-slip activity during the Middle- Late Cambrian; the intense strike-slip fault activity stage during the Middle-Late Ordovician; the reactivation stage of deep strike-slip fault in the Silurian; and the connection and reactivation stage during the Devonian-Carboniferous. [ABSTRACT FROM AUTHOR]

The Manyovu redbeds are an up to 600 m succession of fine-grained, siliciclastic strata in northwestern Tanzania and are part of the Neoproterozoic Bukoban Supergroup. Previous authors estimated the age of the Manyovu redbeds to be Neoproterozoic or older based on the K-Ar dates of underlying volcanic rocks (ca. 800 Ma). However, no other age constraints exist for these Neoproterozoic units. U-Pb detrital zircon results from six stratigraphic intervals of the Manyovu units, including both sandstone and siltstone samples, indicate maximum depositional ages as young as 614 ± 6 Ma, almost 200 m.y. younger than the underlying volcanics, with primary detrital contributions from Pan-African orogens, which indicates that these units are syn-tectonic accumulations associated with the assembly of Greater Gondwana/Pannotia. Detrital zircon spectra and modal compositions reveal that the sediment that formed these strata was sourced from a range of terranes, including continental blocks (i.e., Tanzania Craton), magmatic arcs (i.e., Mozambique Belt and Arabian-Nubian Shield), and recycled orogens (e.g., Ubendian-Usagaran belts). Together, these data indicate that the Manyovu redbeds accumulated following the Marinoan Snowball Earth event (ca. 635 Ma) and record the initiation of collision along the Mozambique Belt during Pan-African orogenesis and the formation of greater Gondwana. [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]

The study of the mineralogical and geochemical features of placer gold and the mechanisms of its distribution in the territory east of the Siberian platform, overlain by a thick cover of Mesozoic–Cenozoic deposits, where traditional methods of searching for gold fields are not effective, allowed researchers, for the first time, to establish the stages of ore formation and to predict the types of gold deposits and their location. The identified indicators of placer gold (morphology, granulometry, chemical composition, micro-inclusions, and internal structures) indicate that ore occurrences in both the Precambrian and Mesozoic stages of ore formation were primary sources of placer gold. The identification of characteristic indicators in placer gold for certain types of gold deposits allowed researchers to prove the formation of gold ore sources east of the Siberian platform for the first time: low-sulfide quartz gold, gold–ferruginous quartzite, gold–copper–porphyry, and gold–platinoid formations are found in the Precambrian stage of ore formation and gold–silver, gold–sulfide–quartz, and gold–rare metal formations are found in the Mesozoic stages of ore formation. Thus, for the first time, based on a huge amount of factual material, it is proved that the mineralogical and geochemical features of placer gold carry enormous information about both the endogenous origin of gold (stages of ore formation—Precambrian and Mesozoic) and the expected type of formation of the predicted deposits. It is established that the predicted type of ore sources corresponds to a certain geological and structural position; this contributes to a more correct selection of methods for searching for ore and placer gold deposits in closed territories and assessing their prospects. In general, the application of the mineralogical method for the first time makes it possible to develop criteria for predicting resources and types of gold deposits, and to assess the prospects of gold mining potential in platform areas at a new level of knowledge. [ABSTRACT FROM AUTHOR]

The origins of magnetite-apatite deposits are controversial, and the crux of the debate is what types of fluids form these rocks. We present evidence from 20 magnetite-apatite deposits worldwide showing ubiquitous involvement of molten salts. The studied deposits are distributed globally, from various tectonic settings, and from Precambrian to Quaternary in age. In every case, water-poor polycrystalline melt inclusions in ore-stage minerals are dominated by sulfate, chloride, and carbonate components plus variable proportions of calc-silicates, phosphates, and iron ± titanium oxides that re-melt between 285 °C and 1100 °C. These fluids are very different from what is generally expected in most geologic settings, but their ubiquitous presence in magnetite-apatite rocks indicates that molten salts are widespread and essential to the formation of these deposits. [ABSTRACT FROM AUTHOR]

Magmatic activity is one of the important pathways for the delivery of deep Earth carbon to the surface. The massive carbon release in this process can have significant impacts on atmospheric-oceanic environment. Previous studies have done a lot of work on the relationship between Phanerozoic magmatic activity and carbon release, but there is relatively limited attention has been given to investigating the association between Precambrian magmatic activity and carbon release. The Yanliao Large Igneous Province at 1.32 Ga exhibits extensive development of sills, and the reaction between sills and surrounding rocks triggers the release of carbon. Simultaneously, the magmatic activity during this period is considered as the final response to the breakup of the Columbia supercontinent, coinciding with the occurrence of the Mesoproterozoic Oxygenation Event To explore the connection between this magmatic activity and global carbon cycling, environmental changes and planetary evolution, nine representative stratigraphic columns are selected from the Yanliao area. We use the SILLi 1.0 1D model by utilizing the one-dimensional finite element method (FEM) to simulate and estimate the amount of carbon release triggered by sill emplacement. The simulation results indicate that the emplacement of sills increased the surrounding rock temperature and vitrinite reflectance, leading to a decrease in the total organic carbon (TOC) content. A large amount of organic carbon and inorganic carbon was released, which was initiated by the reaction between sills and surrounding rocks, with a total carbon release up to 1.24 x 1013 tons. The estimated CO2 equivalent released during this magma activity episode is expected to be greater than 4.58 x 1013. In Mesoproterozoic strata, the emplacement of sills activates carbon within the lithosphere could have implications for the global environment. Further work needs to be done in other ancient cratons that possess Lower Riphean strata to find additional evidence of the impact of this magmatic event on the Earth system. From this study, it is evident that magmatic activity during the Precambrian period could promote the activation of carbon in crustal sediments and influence global environment, which can a reference for people to understand the planetary evolution process. [ABSTRACT FROM AUTHOR]

The history of Earth's carbon cycle reflects trends in atmospheric composition convolved with the evolution of photosynthesis. Fortunately, key parts of the carbon cycle have been recorded in the carbon isotope ratios of sedimentary rocks. The dominant model used to interpret this record as a proxy for ancient atmospheric CO2 is based on carbon isotope fractionations of modern photoautotrophs, and longstanding questions remain about how their evolution might have impacted the record. Therefore, we measured both biomass (εp) and enzymatic (εRubisco) carbon isotope fractionations of a cyanobacterial strain (Synechococcus elongatus PCC 7942) solely expressing a putative ancestral Form 1B rubisco dating to ≫1 Ga. This strain, nicknamed ANC, grows in ambient pCO2 and displays larger εp values than WT, despite having a much smaller εRubisco (17.23 ± 0.61‰ vs. 25.18 ± 0.31‰, respectively). Surprisingly, ANC εp exceeded ANC εRubisco in all conditions tested, contradicting prevailing models of cyanobacterial carbon isotope fractionation. Such models can be rectified by introducing additional isotopic fractionation associated with powered inorganic carbon uptake mechanisms present in Cyanobacteria, but this amendment hinders the ability to accurately estimate historical pCO2 from geological data. Understanding the evolution of rubisco and the CO2 concentrating mechanism is therefore critical for interpreting the carbon isotope record, and fluctuations in the record may reflect the evolving efficiency of carbon fixing metabolisms in addition to changes in atmospheric CO2.

Consideration is given to results of geochemical analysis of organic matter and oils of the Proterozoic (the RF-V complex) and the Paleozoic (the pay intervals D2, D3, C1-2) of the eastern part of the Volga-Urals petroleum basin. The obtained data is corroborated by results of 2D basin modeling along four regional profiles two of which are situated in the Kama and two in the Belaya parts of the Kama-Belaya aulacogen. An update is given to earlier data on degree of catagenetic alteration of oil/gas source rocks of the Riphean-Vendian play, maps of catagenesis are constructed. New evidence is provided concerning presence of Precambrian oils in the Paleozoic plays. The oils under investigation are mixed – those formed from generation products of the Precambrian (Riphean, Vendian) and Paleozoic (Devonian and Early Carboniferous) source rock intervals. The results of modeling have shown that the principal source rock intervals in the RF-V play of the Kama part of the Kama-Belaya aulacogen are deposits of the Kaltasy formation of the Lower Riphean and the Vereshchagino formation of the Upper Vendian, while in the Belaya part these are rocks of the Kaltasy, Kabakov, Olkhovo, Priyutovo, Shikhan and Leuza formations of the Riphean and the Staropetrovo formation of the Vendian. It is found that the interval of the main oil and gas window increases in the southeastward direction. In both depressions of the Kama-Belaya aulacogen, a single oil play is distinguished that functions within the stratigraphic interval from the Riphean to the Lower Carboniferous. As the principal petroleum source rock intervals within this play, Riphean-Vendian deposits are considered, reservoirs are confined to the Riphean carbonate complex, Upper Vendian and Middle Devonian clastic deposits, while the Upper Devonian – Tournaisian deposits serve as the upper seal.

Detrital zircon dating allows us to elucidate the age and provenance of siliciclastic strata of the Sarydjaz and Ichkebash formations in the Middle Tianshan of eastern Kyrgyzstan, previously thought to be of the Middle or Late Ordovician age. New data indicate that the upper part of the Ichkebash Formation contains Lower Silurian sediments, previously unknown in this region. The Kanachu Formation, which lies stratigraphically above, is also not older than the Silurian in age. The absence of marine fauna at these levels apparently reflects the predominant development of deltaic facies. The paleocurrent indicators and the ages of detrital zircons point to its provenance in the North Tianshan (NTSh). Grains with ages from the Late Cambrian to the Silurian, synchronous with the main stage of the Early Paleozoic magmatism in the NTSh, predominate in the Ichkebash Formation. The occurrence of Precambrian detrital zircons in all dated samples and especially in the Sarydjaz Formation indicates the erosion of Precambrian rocks. The provenance most likely located in the Chu-Kendyktas Massif, where the Precambrian detrital zircons in the Neoproterozoic and Early Paleozoic metasedimentary rocks demonstrate a similar distribution of the ages. The foredeep in the Middle Tianshan was formed in the Late Ordovician and Early Silurian generally subsynchronously with the main orogenic event in the NTSh. [ABSTRACT FROM AUTHOR]

There are numerous Neoarchean metasedimentary rock packages in the Slave craton, and they serve as important archives of tectonic processes. Little is documented on the Neoarchean sedimentary packages of the Winter Lake greenstone belt of the central Slave craton, however, and their interpretation can aid in the understanding of the final stages of Slave craton amalgamation. This project investigates the depositional environments and tectonic settings of the Itchen Formation and Sherpa Formation of the Winter Lake greenstone belt. Our study provides constraints for reconstructing the Neoarchean evolution of the central Slave craton through bedrock mapping and facies analysis. The Itchen Formation consists of submature mudstone, siltstone, and sandstone, with preserved graded bedding, planar bedding, and flame structures. Unconformably overlying the Itchen Formation is the Sherpa Formation, which is dominated by polymictic conglomerates and coarse-grained sandstones with preserved cross-bedding, imbricated clasts, and scour surfaces. The Itchen Formation is interpreted to have been deposited in a convergent basin (i.e., retro-arc foreland basin), where two facies associations outline turbidite and suspension sedimentation consistent with submarine fan deposition on a continental slope and a basin floor environment. By contrast, the Sherpa Formation has three facies associations representing dominantly alluvial–fluvial environments in terrestrial–marine–lacustrine settings deposited in pull-apart basins resulting from transtensional forces associated with the Beniah fault zone. [ABSTRACT FROM AUTHOR]

Phosphorus plays a crucial role in controlling biological productivity, but geological estimates of phosphate concentrations in the Precambrian ocean, during life's origin and early evolution, vary over several orders of magnitude. While reduced phosphorus species may have served as alternative substrates to phosphate, their bioavailability on the early Earth remains unknown. Here, we reconstruct the phylogenomic record of life on Earth and find that phosphate transporting genes (pnas) evolved in the Paleoarchean (ca. 3.6-3.2 Ga) and are consistent with phosphate concentrations above modern levels (> 3 µM). The first gene optimized for low phosphate levels (pstS; <1 µM) appeared around the same time or in the Mesoarchean depending on the reconstruction method. Most enzymatic pathways for metabolising reduced phosphorus emerged and expanded across the tree of life later. This includes phosphonate-catabolising CP-lyases, phosphite-oxidising pathways and hypophosphite-oxidising pathways. CP-lyases are particularly abundant in dissolved phosphate concentrations below 0.1 µM. Our results thus indicate at least local regions of declining phosphate levels through the Archean, possibly linked to phosphate-scavenging Fe(III), which may have limited productivity. However, reduced phosphorus species did not become widely used until after the Paleoproterozoic Great Oxidation Event (2.3 Ga), possibly linked to expansion of the biosphere at that time. Phosphorus is an essential nutrient which may have influenced Earth's early biosphere. This study interrogates genomic records, finding potentially phosphate depleted conditions toward the end of the Archean when enzymes for scavenging reduced phosphorus compounds spread throughout the tree of life. [ABSTRACT FROM AUTHOR]

Bostonite rocks are widely spread in the Central Eastern Desert (CED) of Egypt, they are found in the form of sills or dykes injected in the Precambrian rocks. Postgeosynclinal (Hammamat) sediments were intruded by Postorogenic bostonites. The study of this area, using ground geophysical methods, aimed at tracking the radioactive mineralization under the surface, based on the possible association of this radioactive mineralization with some other mineralizations such as sulphides. The application of the self-potential survey shows that the highest negative anomalies are associated with the South El-Atshan bostonite sill and its contact zones. The depths to the centres of some selected anomalies range from 5.7 m to 24 m, half-widths oscillate from 6 to 32 m, with shallow dips towards the west and east directions. The horizontal-loop electromagnetic (HLEM) survey, which was conducted using four frequencies, revealed the presence of two conductive bodies. These conductive bodies possess narrow widths and depths, ranging from 25 m to 27 m, dipping towards the west direction with shallow angles of 25◦ and 40◦, respectively. In addition, the induced polarization (IP) profile shows high chargeability values reaching more than 7.9 mV/V at depths starting from about 10 m to about 35 m. This zone corresponds to a high-resistance zone that may reflect a subsurface disseminated mineralization. The integration of the results obtained using the three techniques makes it possible to determine the most appropriate zones for the development of exploration in the area of investigation. [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]

The greenhouse gas methane (CH4) contributed to a warm climate that maintained liquid water and sustained Earth’s habitability in the Precambrian despite the faint young sun. The viability of methanogenesis (ME) in ferruginous environments, however, is debated, as iron reduction can potentially outcompete ME as a pathway of organic carbon remineralization (OCR). Here, we document that ME is a dominant OCR process in Brownie Lake, Minnesota (midwestern United States), which is a ferruginous (iron-rich, sulfate-poor) and meromictic (stratified with permanent anoxic bottom waters) system. We report ME accounting for ≥90% and >9% ± 7% of the anaerobic OCR in the water column and sediments, respectively, and an overall particulate organic carbon loading to CH4 conversion efficiency of ≥18% ± 7% in the anoxic zone of Brownie Lake. Our results, along with previous reports from ferruginous systems, suggest that even under low primary productivity in Precambrian oceans, the efficient conversion of organic carbon would have enabled marine CH4 to play a major role in early Earth’s biogeochemical evolution. [ABSTRACT FROM AUTHOR]

The deeply buried, northeastern segment of the fold-and-thrust belt of the Outer Carpathians is contoured by synorogenic sediments (Upper Oligocene-Lower Miocene) of tectonically multiplied thicknesses, which mask the deep-seated structures. Integration of archival mappings and profiles of deep wells with the new generation of geological-seismic cross-sections reveals the unconformable position of asymmetric folds and duplexes built of synorogenic sediments, resting upon the older flysch formations (Cretaceous-Lower Paleogene). These structures are cut by a system of dislocated, monovergent, imbricated overthrusts, deeply rooted in the outer zones of thrust folds. These zones are associated with deep-seated, high-amplitude (up to several kilometres), Meso-Paleozoic and Precambrian faults originated by subduction of the European Platform. As revealed by geological reinterpretation of MT-1 magnetotelluric soundings, the time/space identification of longitudinal, compressional sutures rotated by transversal, transpressional faults suggests a segmented model of subduction of the platform basement. Its coincidence with the reconstructed kinematic evolution of sedimentary covers justifies the origin of the inversion tectonics of the Central Depression of the Outer Carpathians as a result of the heterogenic structure of the consolidated basement. [ABSTRACT FROM AUTHOR]

The paper deals with the fossil cyanobacterial films from the Lower Proterozoic (Livvian) shungite in Karelia, Russia. The films were previously described as a formal species Cyathotes nigoserica Makarikhin. They were formed by bacteria and possibly by fungi, which inhabited the littoral or supralittoral (the tidal zone). These organisms were adapted to the existence in temporally (possibly, long-lasting) dry conditions, which is proved by the development of dense coatings protecting their bodies from dehydration. This basically bacterial community influenced intensely the mineral substrate, changed its structure, and enriched it with biogenic constituents, thus forming an archaic soil microprofile. The research revealed the following signs of ancient soil formation: surface transformation of the mineral substrate texture by the vital activity of terrestrial organisms (bacteria, fungi) with the formation of a specific cellular topographic pattern,; changes in the internal structure of the substrate and the appearance of wedge-shaped fracture casts in the underlying matrix; redistribution of inorganic compounds during the formation of a paleosurface microprofile (the increasing content of silicon oxide in the upper part with a simultaneous reduction in the amount of iron oxides). [ABSTRACT FROM AUTHOR]

The lower age boundary of the Upper Precambrian basal sequences of the Polar Urals (Nyarovei Group) is determined on the basis of mass U–Pb (LA-ICP-MS) dating of detrital zircon. The upper boundary of the basal sequence is determined from U–Pb (LA-ICP-MS) dating of zircon from overlapping volcanic rocks of the Nemyurgan Formation. It is thus established that the Nyarovei Group formed during a narrow period in the end of the Late Riphean (~750–650 Ma). The recognition of the group as a Middle Riphean straton is erroneous. A dominant role in the formation of the Nyarovei Group was played by erosion products of adjacent blocks of crystalline rocks, the fragments of which probably include the polymetamorphic complexes in the Kharbei–Marunkeu Anticlinorium of the Polar Urals. [ABSTRACT FROM AUTHOR]

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Topical issues on the prospects of the Voronezh Anteclise for detection of natural hydrogen occurrences are considered. The most important factor of natural hydrogen localization is the surface of the Precambrian basement. The vault itself is surrounded by a system of depressions and aulacogens, which is generally favorable for the formation of gas emanations. The presence of ultramafic and mafic rocks, distributed at different structural and age levels, is an additional material factor of the localization of natural hydrogen. The trappean formations of the Novogol Complex and the Upper Devonian basalt covers are most promising. Four gas transportation systems of different ages can be distinguished within the Voronezh Anteclise (Losevka Suture Zone; Tim- Yastrebovka and Belgorod-Mikhailovka Paleoproterozoic rift structures; depressions and aulacogens formed in the Upper Proterozoic; and structures formed in the Upper Devonian). The Precambrian–Phanerozoic unconformity surface is a transportation system and a major mega-trap, but it is "perforated" because of many circumments, through which a significant part of hydrogen is lost. This paper characterizes the surface circular and oval subsidence structures, their possible origin, and their role in hydrogen degassing. Phenomena accompanying circumments include "bleaching" of chernozems, desertification, and increased concentrations of noble metals, primarily platinum group elements (PGEs). The analysis of the mineragenic factors controlling the transportation and accumulation of natural hydrogen within the anteclise, in general, shows very high prospects for the structure considered. [ABSTRACT FROM AUTHOR]

Magmatic activity is one of the important pathways for the delivery of deep Earth carbon to the surface. The massive carbon release in this process can have significant impacts on atmospheric-oceanic environment. Previous studies have done a lot of work on the relationship between Phanerozoic magmatic activity and carbon release, but there is relatively limited attention has been given to investigating the association between Precambrian magmatic activity and carbon release. The Yanliao Large Igneous Province at 1.32 Ga exhibits extensive development of sills, and the reaction between sills and surrounding rocks triggers the release of carbon. Simultaneously, the magmatic activity during this period is considered as the final response to the breakup of the Columbia supercontinent, coinciding with the occurrence of the Mesoproterozoic Oxygenation Event To explore the connection between this magmatic activity and global carbon cycling, environmental changes and planetary evolution, nine representative stratigraphic columns are selected from the Yanliao area. We use the SILLi 1.0 1D model by utilizing the one-dimensional finite element method (FEM) to simulate and estimate the amount of carbon release triggered by sill emplacement. The simulation results indicate that the emplacement of sills increased the surrounding rock temperature and vitrinite reflectance, leading to a decrease in the total organic carbon (TOC) content. A large amount of organic carbon and inorganic carbon was released, which was initiated by the reaction between sills and surrounding rocks, with a total carbon release up to 1.24 × 1013 tons. The estimated CO2 equivalent released during this magma activity episode is expected to be greater than 4.58 × 1013. In Mesoproterozoic strata, the emplacement of sills activates carbon within the lithosphere could have implications for the global environment. Further work needs to be done in other ancient cratons that possess Lower Riphean strata to find additional evidence of the impact of this magmatic event on the Earth system. From this study, it is evident that magmatic activity during the Precambrian period could promote the activation of carbon in crustal sediments and influence global environment, which can a reference for people to understand the planetary evolution process.

The article unravels a confusing history of ideas about the age of the Garevka granite pluton, which is considered as a reference object for the Precambrian of the Yenisei ridge. Initially, the Paleoproterozoic (1750 Ma) age of granite was determined by M.I. Volobuev and co-authors half a century ago using Pb/U isotope analyses of zircons and orthites. This dating is widely used up to recent to substantiate the Early Precambrian age of the metamorphic rocks of the Trans-Angara region. In 2003, V.A. Vernikovsky and his colleagues published data on the Neoproterozoic (752±3 Ma) age of the massif, obtained with modern technique of isotopic analysis. However, some of experts on the geology of the Yenisei ridge considered both isotopic ages correct, believing that the eastern part of the massif comprises Paleoproterozoic gneissic granite. Our investigation revealed the following: V.A. Vernikovsky and M.I. Volobuev indeed have collected their granite samples at the western and at the eastern parts of the pluton correspondingly. Krasnoyarsk geologists map the Garevka pluton as part of the Neoproterozoic Glushikha granite suite, but use to apply its Paleoproterozoic dating to substantiate the early Precambrian age of the host rocks. M.I. Volobuev obtained ten mainly discordant Pb/U analyses of the Garevka granites, and six of them form an explicable combination consistent with the age of 1750 Ma. The only concordant analysis with a known sampling point is decisive for the entire system. Thus, to fix the problem, it was necessary to reproduce this analysis using modern isotope techniques. We have dated (SHRIMP) a granite sample collected at the same point. In addition, three more samples from different parts of the massif were analysed to exclude the possible presence of ancient domains in it. The isotope ratios of all analysed zircons form a concordant cluster with an age of 762±7 Ma. The Garevka pluton comprises a separate mappable body composed of biotite leucogranites with fluorite. Granites do not replace some older rocks, but crystallized from the melt, ascended from deep crust. The question about possible Paleoproterozoic age of the Garevka granite pluton or any part of it is closed. Ideas about the wide distribution of Archean and Paleoproterozoic gneisses in the Trans-Angara region require additional geochronological verification. To date, the presence of such rocks has been reliably established here only at two local points.

Abstract 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.

The intensifying exploration for deep-buried oil and gas reserves in the southwestern Tarim Basin accelerates the necessity to understand how the structure and evolution of the Precambrian basement affect the development and distribution of Precambrian strata. However, the lack of systematic and comprehensive understanding of the structural characteristics of the Precambrian basement in the southwestern Tarim Basin restricts further advancements in the exploration of ultra-deep oil and gas reserves in this area. Based on the previous research results, this study analyzed the lithology, age, structure, and evolution of the Precambrian basement in the southwestern Tarim Basin by utilizing integrated research methods of geology and geophysics and in combination with the U-Pb dating results of the Precambrian basement. The results reveal that the structure of the Precambrian basement in the Bachu uplift region is characterized by Paleozoic strata overlying directly on the Paleo-proterozoic metamorphic rocks/granites. In the Maigaiti slope and southwestern depression, it exhibits a typical three-tier structure: the Paleoproterozoic metamorphic rocks/granites at the bottom, overlain by sedimentary build-ups from the rifting to depression evolution of the Nanhua-Sinian system. Evolution of the Precambrian basement in the southwestern Tarim Basin was primarily transpired in five phases: continental rifting in the Columbia supercontinent (> 1.1 Ga), assembly of the southwestern Tarim block and the Australian plate (about 1.0 Ga), assemblage between the northern and southern Tarim blocks (900-800 Ma), Nanhua rifting period (760-640 Ma), and Sinian depression period (< 635 Ma). The uplift and downwarping structures during the Nanhua rifting period dictated the development of the Sinian-Lower Cambrian sedimentary strata. In-depth research into the structure and evolution of the Precambrian basement in the southwestern Tarim Basin, as presented in this study, provides important theoretical basis for deep oil and gas exploration in the region, and helps to promote further development of ultra-deep oil and gas exploration.

New geochronologic and paleomagnetic data from the North American Midcontinent Rift (MCR) reveal the synchronous emplacement of the Beaver River diabase, the anorthosite xenoliths within it, and the Greenstone Flow—one of the largest lava flows on Earth. A U-Pb zircon date of 1091.83 (Formula presented.) 0.21 Ma (2 (Formula presented.)) from one of the anorthosite xenoliths is consistent with the anorthosite cumulate forming as part of the MCR and provides a maximum age constraint for the Beaver River diabase. Paired with the minimum age constraint of a cross-cutting Silver Bay intrusion (1091.61 (Formula presented.) 0.14 Ma; 2 (Formula presented.)), these data tightly bracket the age of the Beaver River diabase to be 1091.7 (Formula presented.) 0.2 Ma (95% CI), coeval with the eruption of the Greenstone Flow (1091.59 (Formula presented.) 0.27 Ma; 2 (Formula presented.))—which is further supported by indistinguishable tilt-corrected paleomagnetic pole positions. Geochronological, paleomagnetic, mineralogical and geochemical data are consistent with a hypothesis that the Beaver River diabase was the feeder system for the Greenstone Flow. The large areal extent of the intrusives and large estimated volume of the volcanics suggest that they represent a rapid and voluminous ca. 1,092 Ma magmatic pulse near the end of the main stage of MCR magmatism.

To evaluate the plate flexure model for the formation of the Appalachian Basin, we investigate the extent to which crustal structure beneath and surrounding the basin was modified by the Palaeozoic orogenic events that created the basin. We jointly invert receiver functions and surface wave dispersion measurements to obtain 1-D crustal Vs profiles for 261 seismic stations located within and around the basin. The average crustal thickness for the region is 44 km, and the crust gradually thins to the east, consistent with previous studies. Four areas of anomalous crust are identified with respect to the eastward thinning of the crust. An area of thick crust is found along the Grenville Front on the western side of the Appalachian Basin where the crust thickens by ∼5–10 km. Moho depths of up to 54 km in this region likely result from suture-thickening. The crust is thinner beneath the Neoproterozoic Scranton rift by ∼5–7 km, coincident with a ∼40 mGal Bouguer gravity high. Across the Neoproterozoic Rome Trough, the crust thins by ∼4–5 km, coincident with a ∼10 mGal Bouguer gravity high. Density models for these rifts show that the rift-related crustal thinning is sufficient to explain the gravity anomalies. The Vs models obtained for stations in the rifts indicate little, if any, mafic layering in the mid-crust and only a modest amount of mafic layering in the lower crust. In the northwestern portion of the Appalachian Basin in northeastern Ohio and northwestern Pennsylvania within the Elzevir block, another area of anomalously thick crust (50–52 km) is found. This region is not associated with any known tectonic structures or boundaries or a gravity anomaly. The lower ∼5–10 km of the crust in this region is characterized by high (>3.9 km s−1) shear wave velocities and thus appears to be mafic. The origin of anomalous crustal structure in all four areas is best attributed to Precambrian tectonic events that predate the formation of the Appalachian Basin, indicating that the crystalline crust beneath and surrounding the basin was not significantly affected by the Palaeozoic basin-forming orogenic events, a finding which supports the use of plate flexure models for understanding basin formation. [ABSTRACT FROM AUTHOR]

The study region in southeastern Brazil is composed of two domains: the Cretaceous onshore Espírito Santo Basin and the Neoproterozoic Araçuaí Orogen. In this region, associations among geological evolution, observed structures and geophysical data are limited. Therefore, this study aimed to further investigate this region using magnetotelluric (MT) data obtained from 22 W-E spanning stations over the Espírito Santo State. Because the dimensionality analysis revealed a substantial 3-D characteristic of the data, a 3-D MT inversion using the ModEM code was performed to generate a regional geoelectric model, and potential and well data were used as qualitative support for the interpretation. The resistivity profile obtained from the model revealed a resistive pattern for the Precambrian terrain and a conductive pattern for the sedimentary rocks of the onshore Espírito Santo Basin. The basement of the basin was delimited in the resistivity model, revealing consistency with the basement depths from the well data. Furthermore, three crustal conductors inserted in a resistive Precambrian orogen were identified. These conductors may be related to the recent circulation of saline fluids associated with plume action during the Upper Cretaceous and Cenozoic. However, the structures in which these fluids circulate exhibit different genesis along the resistivity profile. The conductors to the west of the profile may be related to plutons and dykes associated with the NNW Colatina Lineaments generated by the gravitational collapse of the orogen (530–490 Ma). Conversely, the conductor to the east under the Espírito Santo Basin appears to be related to the primary detachment rift fault generated during the Cretaceous breakup of Gondwana. [ABSTRACT FROM AUTHOR]

A cyclostratigraphic study of the Late Precambrian Zhuya Group (Nikolskoye and Chencha Formations), and Torgo formation in the southern part of the Siberian Platform was carried out to determine the duration of the C-isotope anomaly imprinted in them. The similarity of the ratios of the period lengths of the cyclic components of the magnetic susceptibility in the coeval deposits of the remote sections of the Nikol'skoye and Torgo Formations indicates the connection between the revealed cyclicity and the basin-scale environment changes. According to the astrochronological model, the duration of the formation of the studied intervals of the Nikol'skoye (57 m) and Chencha (147 m) formations was 850 and 2500 ky, respectively. Extrapolation of the data obtained shows that the duration of the C-isotope anomaly of the Zhuya Group in the Vendian reference section on the Ura uplift was about 10 My, which is consistent with most estimates of the Shuram anomaly's duration and its stratigraphic analogues. [ABSTRACT FROM AUTHOR]

The mountain framework of the Denman Glacier is a poorly explored area. However, it is a key region of East Antarctica in the context of studying the Precambrian geological history and geodynamic evolution of the Archean protocratons of the Antarctic Shield and in their comparison with the Archean crust-forming events of other regions of the Earth. Original U–Pb isotope geochronology data from zircons of metamorphic and intrusive rocks sampled from the western side of the Denman Glacier are reported. A geotectonic interpretation of the data was carried out. The Paleoarchean age of crystallization (3355 ± 5.4 Ma) of the magmatic protolith of tonalitic orthogneisses of the Davis granite–gneiss complex was obtained for the first time in this sector of Antarctica. In the Archean time interval, the Davis Paleoarchean protocraton was affected by multistage polymetamorphism in the intervals ~3100–3000 and 2900–2800 Ma ago. A crustal extension associated with the late stage is indicated by syntectonic intrusion of ultramafic dikes and pyroxenite sills (2827 ± 6 Ma). The time when granite veins and subalkaline granitoid plutons formed corresponds to the time of tectono-thermal Pan-African activization in the interval of 550–510 Ma typical for the Rayner Province of East Antarctica. The terrane of Davis craton is similar to the Paleo-Mesoarchean protocratons of East Antarctica, India, and Australia for the time of formation and the evolution of geodynamic processes. [ABSTRACT FROM AUTHOR]

The age of sedimentation (530–520 Ma) of the Teregtig Formation of South Tuva is estimated on the basis of U–Pb dating of detrital zircon grains from terrigenous rocks and Sr chemostratigraphy of carbonate rocks. It is shown that granitoids with an age of 580 Ma were the main source of detrital zircon. The presence of a representative Precambrian detrital zircon population indicates the deposition of sediments of the Teregtig Formation within the continental crustal block with a long evolution. During the accumulation of coarse-grained rocks of the Teregtig Formation, this part of the eroded area also comprised rocks of the Agardag ophiolite massif, which is evident from numerous angular clasts of olivine, pyroxenes, and Cr-spinels in the conglomerate matrix. [ABSTRACT FROM AUTHOR]

The assembly and break-up of supercontinents have been hot research topics in international earth sciences because they represent a breakthrough in reconstructing the history of continental evolution and deepening the theory of plate tectonics, which is of indispensable importance to the development of earth sciences. With the continuous enrichment of paleomagnetic, paleontological, chronological, and geochemical data in the last two decades, the evolution of the supercontinent from Columbia to Rodinia has gradually gained unified understanding, and the reconstruction of the major plates within the supercontinent has basically been constrained. In contrast, the reconstruction of microplates, such as South China, Tarim, and Kabul, is controversial and has now become a popular topic and frontier area of supercontinent reconstruction. Hainan lies at the southern tip of South China, and a few Proterozoic units are exposed on the island. At present, Hainan is often taken as a part of the Cathaysia Block. However, due to the lack of exposed Mesoproterozoic igneous and supercrustal rocks in Cathaysia, the reconstruction model of the Cathaysia Block and even the South China Craton based solely on Mesoproterozoic units in Hainan are distinct from those based on units in the Yangtze Block and younger Proterozoic units within the Cathaysia Block, which makes the paleoposition of the South China Craton controversial. In this paper, we provide new detrital zircon U–Pb age data for the Baoban Complex, Hainan, together with the available data to comment on the affinities between Hainan and the Yangtze and Cathaysia Blocks in the Proterozoic, and on this basis, we can reconstruct the South China Craton within the Proterozoic supercontinents. [ABSTRACT FROM AUTHOR]

The northern region of Mozambique has a complex geological history, with an evolution that spans from the Precambrian Era to the Phanerozoic Era. In this work, we have integrated gravity and geothermal data to delineate the geotectonic evolution of the region, by estimating the thickness of the crust and the lithosphere through which was essential to generate a representative crustal model. It was necessary to complement the knowledge of structural geometry and tectonic evolution of the region. The data used in this study are the Bouguer and geoid anomalies, topography data, and radiogenic heat. These data were pre-processed, topography and geoid anomaly data were filtered by low-pass filter in the frequency and harmonic domains to remove undesirable effects associated with the sources. The data were used to estimate the thickness of the crust and lithosphere, as well as to determine the mean density distribution within the mantle. This was achieved by using a one-dimensional approach, considering the principle of local isostatic compensation, associated with equations governing the distribution of temperature in the crust. The Bouguer anomaly was used to generate a representative crustal 2D model of this region. The results showed that the crust is thinner in Nampula and Cabo Delgado provinces, with thickness ranging from 27 to 31 km, whereas in Niassa varies between 33 and 39 km. The analysis of lithospheric thickness indicates that the provinces of Nampula and Cabo Delgado present a thinning of the lithosphere, with values ranging from 150 to 165 km. Rather than Niassa province which exhibits a thicker lithosphere, ranging from 165 to 195 km. The obtained results underwent a comparative analysis with prior investigations, unveiling a noteworthy concurrence among these findings. [ABSTRACT FROM AUTHOR]

Stromatolites, among the earliest fossils in Earth's history, are widely distributed on the margins of the North China Precambrian carbonate platform. The formation processes of stromatolites reveal the biomineralization and evolution of early life in the Precambrian. The well-preserved stromatolitic dolostones recorded in the Ganjingzi Formation are developed around Yuanjiagou village, in southern Liaoning Province. The morphology of the Ganjingzi stromatolites manifests in stratiform, columnar, and domal forms. A tripartite lamina structure including light laminae and two types of dark laminae is observed in thin sections. The origins of dark laminae were related to microbial metabolism, while the light laminae were the result of the recrystallization of synsedimentary marine cement. Hardground substrate and carbonate fragments were suitable for microbes to colonize, suggesting that microbes can adapt to various current energy settings. A comparison of the growth environment, morphology, and laminae features between the Ganjingzi stromatolites and modern carbonate stromatolites from Hamelin Pool and Lagoa Vermelha suggest that the Ganjingzi stromatolites may have been formed in a restricted tidal-flat setting with high salinity and evaporation. The role of microbes that form modern stromatolites in inducing precipitation of carbonate or binding sediments, might contribute to the formation of the Ganjingzi stromatolites. The formation process of the Ganjingzi stromatolites indicates that the microbial communities, favorable substrate, and synsedimentary marine cement were the key factors in promoting the development of the Neoproterozoic stromatolites on the northeastern margin of the North China Craton. [ABSTRACT FROM AUTHOR]

The Ediacaran–Cambrian rocks on the northeastern edge of the Saghro inlier experienced polycyclic tectono-thermal events, which are reported here based on a multiscale structural analysis, from field measurements to fluid inclusion planes. Three striking populations were identified, cutting across both the Ediacaran and Cambrian formations. These tectonic structures were generated during four tectonic events. (i) E-W-striking structures that host ore mineralized bodies (sulfide, oxide, quartz, and barite). They display a polyphase tectonic history, caused by a dextral movement in response to a NW–SE-oriented shortening, leading to the formation of quartz gashes and veins. This tectonic event took place during the Neovariscan. These E–W-striking structures were subsequently reactivated during the Mesozoic time under a sinistral strike-slip regime as a result of NE–SW shortening syn-kinematic with barite mineralization. (ii) NE–SW-striking strike-slip structures (dextral or sinistral) crosscut the E–W-striking veins. These faults are related to the NW–SE-oriented shortening that occurred during the Neogene. (iii) The last tectonic episode, related to the N–S shortening, took place during the late Neogene to the Quaternary period. It resulted in NW–SE to N–S-striking structures that were related to dextral and sinistral strike-slip movements, which crosscut the preexisting E–W structures. [ABSTRACT FROM AUTHOR]

The ca. 1.83 Ga Trans-Hudson orogeny resulted from collision of an upper plate consisting of the Hearne, Rae, and Slave provinces with a lower plate consisting of the Superior province. While the geologic record of ca. 1.83 Ga peak metamorphism within the orogen suggests that these provinces were a single amalgamated craton from this time onward, a lack of paleomagnetic poles from the Superior province following Trans-Hudson orogenesis has made this coherency difficult to test. We develop a high-quality paleomagnetic pole for northeast-trending diabase dikes of the post-Penokean orogen East-Central Minnesota Batholith (pole longitude: 265.8°; pole latitude: 20.4°; A95: 4.5°; K: 45.6 N: 23) whose age we constrain to be 1,779.1 ± 2.3 Ma (95% CI) with new U-Pb dates. Demagnetization and low-temperature magnetometry experiments establish dike remanence be held by low-Ti titanomagnetite. Thermochronology data constrain the intrusions to have cooled below magnetite blocking temperatures upon initial emplacement with a mild subsequent thermal history within the stable craton. The similarity of this new Superior province pole with poles from the Slave and Rae provinces establishes the coherency of Laurentia following Trans-Hudson orogenesis. This consistency supports interpretations that older discrepant 2.22–1.87 Ga pole positions between the provinces are the result of differential motion through mobile-lid plate tectonics. The new pole supports the northern Europe and North America connection between the Laurentia and Fennoscandia cratons. The pole can be used to jointly reconstruct these cratons ca. 1,780 Ma strengthening the paleogeographic position of these major constituents of the hypothesized late Paleoproterozoic supercontinent Nuna.

Detailed geological and petrogeochemical studies carried out using the techniques developed by the authors have made it possible to complete the picture of the formation of supracrustal complexes of the Keivy structure. The studies have shown that the metasedimentary complexes of the Chervurt and Vykhchurt suites were formed mainly due to the material of the underlying strata. In the development of the Vykhchurt Formation, starting from its upper part, the material of the domains surrounding the Keivy takes an active part. The authors have come to the conclusion that at least the middle part of the Keivy section was formed as a result of washing and redeposition of the material of the structure itself, it confirms the conclusions about the presence of redeposited weathering crusts within the Keivy. The results obtained testify to the correctness of the earlier conclusion about the formation of the Keivy structure under conditions most similar to the middle massifs, and to a certain extent explain the formation of a giant deposit of aluminum raw materials within the Keivy.

The Revell batholith is located within the Western Wabigoon terrane of the Superior Province, Northwestern Ontario, Canada, and is a potential site for a deep geological repository (DGR). This batholith is considered to have favourable geoscientific characteristics for hosting a DGR, including a sufficient volume of relatively homogenous rock. The subsurface geometry of the batholith plays an important role in determining its volume, as well as assessing regional-scale hydraulics, rock mechanics, and glacial stress disturbances on the bedrock, which are other important features and processes that can impact the batholith over the timeframes of concern for long-term storage of used nuclear fuel. Subsurface geometry is complicated to unravel, and surface mapping alone is inadequate to obtain the information at depth. However, gravity, magnetic, or seismic data can be used to enhance understanding by approximating the geometry.This study aims to refine the subsurface geometry and distribution of the Revell batholith from a constrained forward and inverse geophysical model, incorporating high-resolution geophysical data together with a compilation of historic and recent geological field data. The Revell batholith was previously cited as a flat-based pluton with a depth of 1.6 km, where our findings suggest the batholith is deeper than previously thought, with an uneven contact geometry at its base that extends slightly deeper than 3.5 km. Model uncertainties were assessed by varying probabilistic constraints on volume overlap/commonality and shape within GeoModeller™. Results indicate that overall batholith-greenstone contact is generally unchanged when the geological constraints are varied, providing a high degree of confidence that the Revell batholith has a sufficient volume of relatively homogeneous bedrock.

New geostructural, petro-geochemical, U–Pb geochronological and paleomagnetic data for sills of metagabbro-dolerites of the Severobyrranga and Yasnenskiy complex specify the paleotectonic position of the Faddey terrane of the Central Taimyr accretionary belt. The structural position of the sills in the rocks of the Oktyabr and Zhdanov formations is indicative of their intrusion before deformations caused by the accretion of the Central Taimyr belt. The U–Th–Pb age of crystallization for the metagabbro-dolerites has been established as 1357 ± 9 Ma. The primary paleomagnetic record reflecting the time of intrusion has not been preserved, but two metachronous components have been identified. The first one corresponds to crust formation processes at ca. 840 Ma due to collision, probably of continent – island arc type involving the cratonic block that included the Faddey and Mamont-Shrenk terranes. These collisional events took place several hundreds of kilometers from the Siberian margin. The second component corresponds to thermal events on the Paleozoic-Mesozoic boundary and reflects the strike-slip deformation in the Kara orogen. [ABSTRACT FROM AUTHOR]

Paleoproterozoic banded iron formation (BIF) iron ore of the Zhengjiapo region of the Changyi metallogenic belt, Eastern Block of North China Craton contains abundant coexisting antiperthite and mesoperthite textures. The antiperthite and mesoperthite occur in felsic domains of the Zhengjiapo BIF ore and enable derivation of peak temperature metamorphic conditions. Thermodynamic phase modeling shows that equilibrium conditions of corresponding textures, considering the related mineral assemblage of Pl + Qz + Kfs + Mag + Opx + L, are in the range of 870–940 °C and 5.0–6.8 kbar. Ternary feldspar thermometry using reintegrated compositions of antiperthite and mesoperthite in the felsic domain of the studied BIF iron ore reveals even higher peak metamorphic temperatures of 1045–1080 °C. The ultra-high temperature–low pressure conditions of Precambrian BIF have not yet been reported from the North China Craton. The documented ultra-high temperature metamorphism of the Zhengjiapo BIF iron ore in the Changyi metallogenic belt indicates that the BIF was involved in the collision-related tectonic process during Paleoproterozoic to have occurred in the Jiao-Liao-Ji orogenic belt. [ABSTRACT FROM AUTHOR]