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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]

This study focuses on a rare sail-shaped macrofossil, Alienum velamenus gen. & sp. nov. from the Jiangchuan Biota in Yunnan Province, China. The new species presented here possesses an unique bipartite body consisting of a wide unbranched, asymmetrical sail-shaped anterior section and a small narrow tail-like posterior section. The macrofossil of the new species is preserved through carbonaceous compression. Its appearance is different from known macroalgae but similar to Vetulicolia from the early Cambrian Chengjiang Biota. The anterior section of the new species, which is broad and smooth, shows only indistinctly arranged suspected gill slits and a nearly horizontal pharyngeal groove, without significant segmented structures. Owing to lack of samples, the specific biological properties and taxa of the new species are still undefined. The discovery of Alienum velamenus indicates that the Jiangchuan Biota is an exceptional lagerstätte with great potential for the preservation of Precambrian early life through carbonaceous compression. Furthermore, the Jiangchuan Biota shows significant differences in species diversity from the Miaohe Biota of the Doushantuo Formation and the Shibantan Biota of the Dengying Formation in the Three Gorges area of Hubei Province. [ABSTRACT FROM AUTHOR]

The Neoproterozoic Bou Azzer Ophiolite, located in the Pan-African orogen of the Anti-Atlas, Morocco, exposes a well-preserved mantle section of the ophiolitic sequence. Although ultramafic rocks are the most common rock types in the sequence, they have received less attention in previous studies. In this work, we investigate the petrogenesis of these ultramafic rocks in detail, including their petrology, mineralogy, and whole rock geochemistry. The mineral assemblages are mainly formed by antigorite with minor lizardite, chlorite, and accessory Cr-spinel. The only preserved primary mantle mineral is Cr-spinel, which shows unaltered cores with Cr# between 0.61 and 0.71 and alteration rims to ferrian chromite and magnetite. Whole rock analyses indicate almost total serpentinization and, locally, strong carbonation (mass loss of ignition between 11.94 and 22.20 wt%). The non-carbonated samples preserve protolith signatures, with decreased MgO/SiO2 suggesting metasomatic processes related to serpentinization. Immobile trace elements compare well with fore-arc peridotites, while melting modelling indicates intense and polyphasic melting events. We propose polyphase melting in a subduction-initiation setting, with a first stage of 14–23% anhydrous melting, forming fore-arc basalts, and a second stage of 15–25% melting with 1 wt% H2O, forming boninites. The Bou Azzer ultramafic rocks represent the fore-arc region of a supra-subduction zone, challenging previous interpretations that suggested a back-arc position. [ABSTRACT FROM AUTHOR]

The Tarim Craton is an ancient Precambrian continental block, and detailed knowledge of its thermo‐tectonic history is crucial for understanding the early history of continental evolution. Abundant layered mafic rocks, which have commonly been regarded as basalts, occur within the Ediacaran Sugetbrak Formation (Fm.) in the Aksu region of the northwestern Tarim Craton. Clear intrusive features have now been discovered, including mafic rocks truncating Ediacaran sedimentary layers, exhibiting an intrusion‐baked margin where they interact with both the overlying and bottom wall rocks, and displaying a fine‐grained transition zone from their interior to their margins. The new findings demonstrate that these mafic rocks within the Aksu Ediacaran strata were not erupted basalts but instead are intrusive diabase dykes. Therefore, these mafic rocks cannot be used to constrain the timing of the Sugetbrak Fm. in the Aksu area, nor as marker layers for regional stratigraphic correlation. Furthermore, the Ediacaran thermo‐tectonic evolution in this region, deduced from the assumption that the mafic rocks are lavas, needs to be revised. [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]

Biological N2 fixation (BNF) is traced to the Archean. The nitrogen isotopic fractionation composition (δ15N) of sedimentary rocks is commonly used to reconstruct the presence of ancient diazotrophic ecosystems. While δ15N has been validated mostly using organisms grown under present-day conditions; it has not under the pre-Cambrian conditions, when atmospheric pO2 was lower and pCO2 was higher. Here, we explore δ15N signatures under three atmospheres with (i) elevated CO2 and no O2 (Archean), (ii) present-day CO2, and O2 and (iii) future elevated CO2, in marine and freshwater, heterocytous cyanobacteria. Additionally, we augment our data set from literature for more generalized dependencies of δ15N and the associated fractionation factor epsilon (ε = δ15Nbiomass – δ15NN2) during BNF in Archaea and Bacteria, including cyanobacteria, and habitats. The ε ranges between 3.70‰ and −4.96‰ with a mean ε value of −1.38 ± 0.95‰, for all bacteria, including cyanobacteria, across all tested conditions. The expanded data set revealed correlations of isotopic fractionation of BNF with CO2 concentrations, toxin production, and light, although within 1‰. Moreover, correlation showed significant dependency of ε to species type, C/N ratios and toxin production in cyanobacteria, albeit it within a small range (−1.44 ± 0.89‰). We therefore conclude that δ15N is likely robust when applied to the pre-Cambrian-like atmosphere, stressing the strong cyanobacterial bias. Interestingly, the increased fractionation (lower ε) observed in the toxin-producing Nodularia and Nostoc spp. suggests a heretofore unknown role of toxins in modulating nitrogen isotopic signals that warrants further investigation. IMPORTANCE Nitrogen is an essential element of life on Earth; however, despite its abundance, it is not biologically accessible. Biological nitrogen fixation is an essential process whereby microbes fix N2 into biologically usable NH3. During this process, the enzyme nitrogenase preferentially uses light 14N, resulting in 15N depleted biomass. This signature can be traced back in time in sediments on Earth, and possibly other planets. In this paper, we explore the influence of pO2 and pCO2 on this fractionation signal. We find the signal is stable, especially for the primary producers, cyanobacteria, with correlations to CO2, light, and toxin-producing status, within a small range. Unexpectedly, we identified higher fractionation signals in toxin-producing Nodularia and Nostoc species that offer insight into why some organisms produce these N-rich toxic secondary metabolites. [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]

Maps of diluvial boundaries for the North American midcontinent are presented by state and by sedimentary basin. The upper diluvial boundary is the base of Ice Age sediments. For most of the study area, the basal diluvial boundary is the erosional unconformity between Precambrian crystalline rock and the Phanerozoic sedimentary record. The exceptions are Proterozoic to Cambrian rifts: the Midcontinent, East Continent, Fort Wayne, Reelfoot, Rough Creek Graben, and Rome Trough rifts. These are remnants of severe crustal disruption at the onset of the Flood, with varying ratios of volcanic and sedimentary fill. This paper focuses on the basal marine diluvial boundary and the upper diluvial boundary, excluding the rifts, showing the volume and distribution of sediments of the Ice Age. Deep Proterozoic rifts will be addressed in Part II. Detailed state maps of the basal diluvial boundary are shown in the appendix. Maps of the study area reveal cratonic basins of varying size, show a thickening of diluvial strata toward the south, and show the extent of Ice Age deposition. All these aid in understanding the work of the Flood in this region. [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]

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]

The paper presents newly obtained and summarizes preexisting data of long-term geochronological and isotope studies of orogenic mesothermal gold deposits in the world's largest Lena metallogenic province and reviews interpretations of their genesis. Geochronologic data indicate that the gold mineralization was formed during three ore-forming Paleozoic events. The early Late Ordovician–Early Silurian (450–430 Ma) event produced the abundant veinlet—disseminated gold–sulfide mineralization in Neoproterozoic carbonaceous terrigenous–carbonate rocks of the Baikal–Patom foldbelt (BPB). The mineralization was formed simultaneously with regional metamorphic processes. The rejuvenation of hydrothermal activity in the BPB resulted in gold-bearing quartz veins, which was produced in the Middle Carboniferous (340–330 Ma) in relation to postcollisional granitoid magmatism. The latest ore-forming event occurred in the Early Permian (290–280 Ma) and affected exclusively in Precambrian structures of the Baikal-Muya foldbelt (BMB). It was synchronous with the development of intraplate alkaline and subalkaline magmatism in the region. Newly obtained and preexisting isotopic-geochemical (87Sr/86Sr, 143Nd/144Nd, Pb–Pb, and δ34S) data indicate that the mesothermal ore-forming systems of northern Transbaikalia were heterogeneous in their isotopic characteristics, which distinguishes them from the ore–magmatic (intrusion-related type) systems. Comparison of the Sr, Nd, and Pb isotopic composition of the ores and rocks, including magmatic rocks coeval with the gold mineralization, indicates that the Precambrian continental crust was the dominant source of mineral-forming components for the hydrothermal systems of the gold deposits. The contribution of the magmatic source to the genesis of the orogenic gold mineralization was limited and is identifiable only for the Early Permian ore-forming systems of the BMB, for which the input of metals from alkaline mafic melts was suggested. [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]

The first of two communications is devoted to the study of lithogeochemical features of the pilot collection of Upper Precambrian sandstone and siltstone samples taken from four boreholes: Bogushevskaya 1, Bykhovskaya, Lepel 1, and Kormyanskaya (Belarus). This article analyzes the general features of their bulk chemical composition and shows the possibilities and limitations for further reconstructions. It has been established that Riphean and Vendian rocks included in the pilot collection, visually identified as sandstones, are actually quartz, feldspar–quartz, and arkosic varieties with different cement types. In terms of geochemical characteristics, the Vendian "siltstones" correspond to the coarse- and fine-grained siltstones and, to a greater extent, mudstones with a predominance of illite, as well as various admixtures of berthierine, kaolinite, and smectite. Based on the comparison of enrichment factor (EF) of the trace element, these rocks are marked by several dissimilarities related to both variations in the source rock composition and sedimentary environment. Data points of the samples on the Zr/Sc–Th/Sc diagram indicate that all of the studied Riphean and Vendian rocks are dominated by the first sedimentation cycle material, suggesting that the lithogeochemical characteristics of the pilot collection rocks quite correctly reflect similar features of the source rock complexes. Therefore, they can be used to reconstruct the paleogeodynamic and paleoclimatic factors that controlled the accumulation of Riphean and Vendian sedimentary sequences in Belarus. [ABSTRACT FROM AUTHOR]

The Belt Supergroup represents one of the thickest sections of Precambrian sedimentary rocks in world. It contains rare features, such as molar-tooth structures, syneresis cracks, and "stromatolites." The rocks were deposited in an intracratonic basin thought to be at least 25 km deep, which could have originated as an impact crater. It is conventionally dated as Mesoproterozoic, about 1.4 Ga. Correlation of formations across the Belt Basin is difficult. The sediment originated predominantly from the west, but since there is no obvious source to the west today, there is much speculation on the land mass that once existed to the west. The place of the Belt Supergroup within Biblical Earth history points to the Flood, especially given the generally conformable contact between the Belt rocks and the overlying Cambrian Flathead Sandstone, a universally accepted Flood rock. Thus, the Belt rocks likely were deposited very early in the Flood. Some of the Belt rocks imply tremendous catastrophism very early in the Flood. [ABSTRACT FROM AUTHOR]

The effects of sediment contribution to the Lesser Antilles island arc have been well explored with whole-rock trace-element chemistry and isotopic studies. To better understand the source of these sediments, we analyzed >400 zircons for U-Pb ages and trace-element chemistry in eight andesiticdacitic ignimbrites and lavas younger than 100 ka from the island of Dominica in the central Lesser Antilles arc. The overwhelming majority of the zircons analyzed were magmatic in origin, with U-Pb ages younger than 10 Ma, but predominantly younger than 300 ka. Zircon trace-element chemistry is consistent with derivation from an oceanicisland arc, and positive eHf(t) values (+5 to +15) support a juvenile depleted mantle source. Rare Precambrian to Eocene xenocrystic zircons (36) were also found in the Dominican volcanics and record sediment dispersal from several different terranes as the Caribbean plate migrated eastward along the northern margin of South America. Although some previous detrital zircon studies in the region suggested zircons younger than 100 Ma were derived from the Great Arc of the Caribbean, the younger Dominican zircon xenocrysts (300-50 Ma) have elevated Th/Yb and U/Yb, as well as variable positive/negative eHf(t) values, inconsistent with an oceanic arc origin. These zircons in Dominica were most likely derived from the Eastern and Central Cordillera of the Andes, which experienced a flare-up in magmatism ca. 65-45 Ma. As the Great Arc of the Caribbean traversed along the South American margin, terrigenous sediments transported via river systems and turbidites accumulated in the forearc basin. Older zircons (1800-300 Ma) have a slightly different chemistry and equivocal source(s), including the Andes, northern Venezuelan coastal ranges, and/or the Guyana Shield. [ABSTRACT FROM AUTHOR]

Three-dimensional inversion of regional long-period magnetotelluric (MT) data reveals the presence of two distinct sets of high-conductivity belts in the Precambrian basement of the eastern U.S. Midcontinent. One set, beneath Missouri, Illinois, Indiana, and western Ohio, is defined by northwest-southeast-oriented conductivity structures; the other set, beneath Kentucky, West Virginia, western Virginia, and eastern Ohio, includes structures that are generally oriented northeast-southwest. The northwest-trending belts occur mainly in Paleoproterozoic crust, and we suggest that their high conductivity values are due to graphite precipitated within trans-crustal shear zones from intrusion-related CO2-rich fluids. Our MT inversion results indicate that some of these structures dip steeply through the crust and intersect the Moho, which supports an interpretation that the shear zones originated as "leaky" transcurrent faults or transforms during the late Paleoproterozoic or the early Mesoproterozoic. The northeast-trending belts are associated with Grenvillian orogenesis and also potentially with Iapetan rifting, although further work is needed to verify the latter possibility. We interpret the different geographic positions of these two sets of conductivity belts as reflecting differences in origin and/or crustal rheology, with the northwest-trending belts largely confined to older, stable, pre-Grenville cratonic Laurentia, and the northeast-trending belts largely having formed in younger, weaker marginal crust. Notably, these high-conductivity zones spatially correlate with Midcontinent fault-and-fold zones that affect Phanerozoic strata. Stratigraphic evidence indicates that Midcontinent fault-and-fold zones were particularly active during Phanerozoic orogenic events, and some remain seismically active today, so the associated high-conductivity belts likely represent long-lived weaknesses that transect the crust. [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]

Natural Hydrogen Gas (H 2) is producing a new golden rush worldwide due to its clean energetic features. The potential of natural hydrogen gas (H 2) in the southernmost regions of Brazil, specifically Rio Grande do Sul and Santa Catarina, remains largely unexplored. We found free H 2 occurrences identified in the intracratonic Mesozoic Paraná Basin, recognized in four formation tests performed in former exploratory wells. The data revealed H 2 concentrations ranging from 0.14% to 8.79%, albeit associated with noncommercial volumes of natural gas. These occurrences of H 2 exhibit a curious negative correlation with Helium (He), distinguishing it from many Eurasian occurrences associated with mantle sources. The Paraná Basin hosts the largest Brazilian coal reserves and organic-rich rocks. We posit that the hydrogen gas presence can be attributed to the maturation processes affecting mainly Rio Bonito, Taciba, and Ponta Grossa formations in this basin. Also, we identified hydrogen system elements in the rift-type Precambrian Camaquã Basin, which host potential source rocks, reservoirs, and seals. Until now, no H 2 measurements have been carried out in this basin. To solve this lack, it is fundamental to execute a systematic sampling survey; it will enable the identification of the potential of H 2 deposits in the Southernmost Brazilian region. This work lays the foundations for future research in the region, which is demanded to realize this economic potential. [Display omitted] • We present a review of the southmost Brazil geology from the perspective of hydrogen geology. • We summarize data from four wells with anomalous values of Hydrogen gas in the Paraná Basin. • We summarize all the elements of a hydrogen system in the Paraná and Camaquã basins. • Paraná Basin shows a concentration of up to 8% of H 2. [ABSTRACT FROM AUTHOR]

The article presents the results of studying and substantiating the age of Late Precambrian volcanosedimentary and plutonic complexes of the northern part of the Ulutau terrane (Northern Ulutau) in western Central Kazakhstan. The obtained age estimates (SHRIMP II, ID-TIMS, LA-ICP-MS) indicate the formation of acidic effusives and granitoids in the second half of the Tonian of the Neoproterozoic ~835‒747 Ma ago. Geochronological and isotope-geochemical data allow us to consider these formations as analogues of stratified and plutonic complexes of Southern Ulutau, which formed in various parts of the lateral series of structures of the Late Precambrian active continental margin. [ABSTRACT FROM AUTHOR]

The formations in the early Paleozoic Joseon Supergroup (mainly carbonates with subordinate siliciclastics) within the Taebaeksan Basin in the Danyang area, South Korea, show an apparent right-side-up homoclinal stratigraphy without repetition or omission of any formation, and it was therefore thought that the NW-dipping formation boundaries are primary depositional contacts. Our detailed examination revealed, however, that the formation boundaries are reverse-slip shear zones parallel to the second-generation foliation (S2) crenulating transposed S0//S1 foliation and that WNW-dipping bedding planes (S0) are only locally preserved. The most penetrative regional planar structure in the area is the NNW-dipping first-generation foliation (S1) that is defined by compositional layering and is parallel to the axial planes of isoclinal F1 folds. Isoclinal to close F1 folds occur on both the mesoscopic and macroscopic scale, whereas tight to close F2 folds occur locally only on the mesoscopic scale. D1 deformation presumably involved a NNW-SSE horizontal contraction and resulted in the buckle folding and transposition of S0. D2 deformation involved a NW-SE contraction, probably at a high angle to the S0//S1 transposed layers, and produced passive shear folding of S0//S1 with S2 crenulation cleavages as discrete shear surfaces. Shearing deformation was strongly localized along some S2 foliation planes, resulting in reverse shear zones that represent the current 'pseudo'-formation boundaries. Based on zircons U-Pb ages, we suggest that the Okdong Fault was initiated from an unconformable boundary between the Precambrian basement gneiss and overlying sediments of the Paleozoic Taebaeksan Basin, probably during the Middle Jurassic. [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 Precambrian terranes of the Eastern Indian Shield (EIS) comprise the Bundelkhand, Singhbhum, and Bastar cratons with intervening Proterozoic mobile belts such as Central Indian Tectonic Zone, Eastern Ghats Mobile Belt, Singhbhum Mobile Belt and Chotanagpur Granite Gneissic Complex; and the Proterozoic Mahanadi Rift, Chhattisgarh and Vindhyan Basins, with significant coverage of Indo-Gangetic Plain sediments in the northern part. This study presents the results of a seismically well-constrained 2-D multi-scale potential field modelling to delineate the lithosphere structure across different Precambrian terranes of the EIS. The joint interpretation of the potential field data reveals that (i) the mobile belts are bounded by the deep crustal faults with denser crust, (ii) presence of thick underplated crust below Singhbhum Craton, Singhbhum Mobile Belt, Chotanagpur Granite Gneissic Complex and the surrounding rift basin, (iii) localised Moho upwarp at a depth of ~ 36–37 km below the Proterozoic basins, and (iv) the Lithosphere-Asthenosphere Boundary (LAB) varying between 90 and 200 km below the EIS region. The distinct crustal structure and deeper LAB (130–200 km) below the mobile belts suggest the Proterozoic amalgamation and lithosphere reworking. Below the Singhbhum Craton, the LAB is observed at a depth of ~ 145–155 km, which is comparatively thinner than other cratonic areas elsewhere. The observed crustal underplating and the thinner LAB below the Singhbhum Craton indicate that the lithospheric erosion and magmatic upwelling was caused by the major Paleo-Mesoproterozoic and Early-Cretaceous large igneous province events. [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]

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.

Here new evidence of the isotope geochronology and the geochemistry from the Yuanmou-Miyi complexes reveal the Precambrian tectono-magmatism geodynamic process in the study area. The Yangtze Block basement with 1.81- ~1.77 Ga and negative εHf(t) values of −7.8 to −0.7 corresponded to the assembly of the Columbia-supercontinent. However, the rifting magmatic event of ~ 1.70 Ga, which caused the continental crust extension-thinning in the study area, may exert influence on the subduction-magmatism in the Grenvillian period. The Yuanmou-Miyi complexes of 1.19- ~1.00 Ga are characterized by (La/Sm)N＞1, depletion in HFSEs, negative anomalies of Nb-Ta, and enrichment of LILEs, which show a genetic link with the subduction-magmatism. The temporal tendency that the magmatism from Yuanmou to Miyi gradually became younger, may be responsible for the subducting direction. The subduction caused the reactivation of the Anninghe-Lvzhijiag fault zone, and created the rupture windows of the subduction slab, leading to upwelling of the deep magma. These granitoids were derived from the partial melting of the mantle wedge, while the small-scale gabbro dikes intruded into the granitoids were likely spillover products from the asthenosphere mantle melts through the rupture windows. [ABSTRACT FROM AUTHOR]

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]

The Precambrian Southern Granulite terrane of south India has a crustal evolution history broadly bracketed between the late Archean and Cambrian with records of polyphase deformation, metamorphism, and magmatism. The Southern Granulite terrane comprises distinct crustal blocks bounded by shear/suture zones that have been variably correlated with supercontinent fragments including Madagascar, Sri Lanka, Africa, Eastern Ghats, and Antarctica. However, the timing and mechanism of assembly of different crustal blocks within the Southern Granulite terrane and its linkages with counterparts in East Gondwana are highly debated. This study aimed to unravel the complex crustal evolutionary pattern of the terrane by generating robust zircon U-Pb/Hf isotopic data from basement charnockites, gneisses, granitoids, and alkaline intrusive units from the central part of Southern Granulite terrane and comparing these results with similar data from different East Gondwanan terranes. The study identified four distinct crustal growth episodes in the Madurai block: (1) Neoarchean-early Paleoproterozoic, (2) Rhyacian-Orosirian, (3) late Tonian, and (4) Ediacaran-Cambrian. Analysis of zircon Hf isotope data revealed that the first two events are marked by juvenile magmatic signatures, whereas the latter two are distinctly associated with intense reworking and remelting of older crust with no significant juvenile input. Our new results combined with existing data from other Gondwanan terranes suggest a common Paleoproterozoic ancestry for the Southern Granulite terrane and its corresponding Gondwanan fragments, proposing a revision to the existing geodynamic models. [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]

The study compares the elemental composition of asphaltenes with the parameters of hydrocarbon biomarkers and Precambrian insoluble organic matter (OM) of the Aldan–Maya depression. The elemental composition of the asphaltenes was found to depend on the pyrolytic characteristics of the OM. Using asphaltene compositions in combination with biomarker parameters, the genetic and catagenetic features of difficult-to-study objects such as Precambrian bitumens can be characterized more accurately and reliably. The elemental composition of the asphaltenes was shown to correlate with the aromatic parameters that reflect the OM maturity. In contrast, the parameters of the asphaltenes show essentially no correlation with biomarker data for the saturated components. [ABSTRACT FROM AUTHOR]

Potwar Basin is one of the hydrocarbon prolific basins but pertains complex deformational style. Maximum production has been taken from Paleocene and Eocene carbonates but deeper reservoirs like Cambrian (Khewra sandstone) and Permian (Tobra formation) are also well producing. Geology of the Northern Potwar deformed zone (NPDZ) is mainly controlled by Pre-Cambrian salt, gently dipping basement and its warp. As we move towards south, salt thickness decreases near the axis of Soan syncline, north of Dhurnal structure. Eastern part of NPDZ is buried one while an emergent fold and thrust front (fault propagating fold) in the western part of NPDZ. Eastern NPDZ has duplex structure with initiation of roof thrust from the Murree Formation and sole thrust from Pre-Cambrian salt. The Southern Potwar platform zone (SPPZ) is less disturbed in comparison with NPDZ in which Pre-Cambrian salt acts as a decollement/lubricating surface over which the Cambrian to Pliocene sequence slides as a single thrust sheet. Due to the combined effect of thick overburden of ~3‒5 km and the decollement, folding and thrusting is significant in the Potwar Basin. In the eastern SPPZ, pop-up and fault propagating folds are prominent while in the western SPPZ, triangular zones, pop-up or detachment folds are significant. [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]

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 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 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]

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]

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]

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]