Precambrian Research Articles

Rambling through the Precambrian time: geological challenges of Dr. Paul F. Hoffman, the laureate of Kyoto Prize 2024

Rambling through the Precambrian time: geological challenges of Dr. Paul F. Hoffman, the laureate of Kyoto Prize 2024

The carbon release triggered by 1.32 Ga sill emplacement and its potential environmental implications

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.

Validation of Advanced Kinematic Model of Earth-Moon System by Observed Length of Day Curve

NASA’s press release of ‘Moon having receded by 1 m from Earth in a quarter of century’ on the Silver Jubilee Anniversary (20 July 1994) of Man’s landing on Moon led to the development of the Kinematic Model(KM) of evolving Earth-Moon System. Best fit KM parameters are adopted for the analysis of evolving E-M system, The present length of day of Earth is assumed to be 24 hours, orbital period of Moon divided by spin period of Earth=LOM/LOD=27.322 and the age of Moon=4.467Gy. Using this best fit model parameters the velocity of recession of Moon is derived as 2.3cm/y as compared to 3.7cm/y by Lunar Laser Ranging experiment.KM is used to plot lengthening of day(LOD) curve from pre-cambrian period (2.5Gy ago) to the present time. This theoretical plot is superimposed on the observed lengthening of day curve. The observed plot is generated from the observed length of day in different geologic epochs by John West Wells, Charles P.Sonnet & Chan and Kaula & Harris by the study of coral fossils, ancient tidalites and marine creatures respectively. The superposition gives more than 25% mismatch in remote past around 2.5Gya. This KM did not consider the obliquity angle 23.44° of Earth and the inclination angle of 5.14° of Lunar Orbital Plane with respect to Ecliptic plane. The classical KM assumed monotonic spiral expansion of Moon from Earth as shown in Figure 1. A recent paper “Tidal evolution of Moon in high angular momentum, high obliquity Earth” has revolutionized the Earth-Moon modeling and paved the way for near-match between observated and theoretical LOD curve. In the new scenario Moon’s tidal evolution is anything but sedate and monotonic. It experienced a bumpy launch through gravitational sling shot at the first geo-synchronous orbit of 15,000Km. Moon was gravitationally catapulted and launched on an expanding spiral path but this expansion was turbulent, chaotic and got stalled at times due to huge lunar obliquity tides during Laplace Plane transition and due to Cassini state transition as shown in Figure 2. Only after Moon settles down in Cassini state II that it resumes its monotonic and sedate spiral expansion as envisaged in the classical picture but this spiral expansion was at accelerated pace so as to reach 3,84,499Km orbital radius in 4.5Gy. It transits in fits , in chaotic and turbulent phase, for 3.3Gy whereas it spends1.2Gy in bounded state therefore this new model is referred to as ‘Fits and Bound’ model of E-M system. On this time scale the modern time recession rate comes to be 3.7cm/y. If this accelerated time frame is adopted then we get near-exact match between theory and observed LOD curve with worst mis-match being -4%. In this accelerated time frame, all E-M system parameters are obtained and it is self consistent model with velocity of recession = 3.7cm/y, LOM/LOD = 27.322 and near match between theory and observed LOD curve and spending 3.3Gy in turbulent and stalled evolutionary phase and spending 1.2Gy in the present accelerated phase. This gives the final vindication to the advanced KM.

Utilization of GIS Model Mapping to Detect Fault Segments in Mesopotamian Foredeep Basin

The Mesopotamia Basin is widely recognized as a significant aggradation geomorphological entity, characterized by the dominance of fluvial, lacustrine, and aeolian landforms. The geographical scope of this study spans a specific region within the Mesopotamian Basin, specifically including Nasiriyah and Basrah located in the southern region of Iraq. It comprises a collection of Joint and fault systems that serve as indicators of various tectonic occurrences that have influenced the Arabian plate from the pre-Cambrian era up till the present day. The major goal of this model is to mapping and detects fault segments to get information about the large faults existing which is not recognized by prior work. A Geographic Information System (GIS) model was employed to create three digital layers, namely Lineament, drainage patterns, and lithological contact. These layers were established using several sources of information. The initial step of the GIS demonstration includes the input information, and the subsequent includes the selection of the equation for this model to specify the vulnerability of faulting segments in the research sector. Moderate to large lineaments (fault lines) were identified the results suggest an additional (26,15) new fault segment line numbers for the areas Nasiriyah and Basrah respectively which were not known by the fault map over the research sector, these fault lines reflect crustal structures (large length lineaments), as well as analysis lineaments from satellite images, enables obtaining a miscellany of terrain applications, such as the selection of landfill sites, determining terrain stability, dam sites, and many other applications

Heavy Li isotopic compositions of the terminal Ediacaran dolostones in the Tarim Basin and their possible link to dolomitizations

Dolostones are promising archives for recording paleo-seawater Li isotope compositions, and are especially important for the Cambrian and Precambrian periods when limestones are scarce. However, the effect of dolomitization on carbonate Li isotopes is unclear, limiting their application in tracking (Pre-)Cambrian seawater Li isotopes. Research on Li isotopes in dolostone sections may resolve this issue. We present the Li isotope compositions of dolostones from the terminal Ediacaran Chigebrak Formation (NW Tarim Basin). The dolostone Li isotopes are ∼17 ± 5 ‰ heavier than contemporaneous seawater, indicating significant Li isotope fractionations during dolomite formation. Given that the formation of clay minerals may enrich the porewater with heavier Li isotopes and promote the dolomite formation, we argue that the clay-catalyzed dolomite formation would probably result in heavier Li isotope compositions of dolomites. Moreover, assuming a fixed fractionation factor (∼15 ‰) for the clay-catalyzed dolomitizations, we obtain the seawater δ7Li variations in the terminal Ediacaran, which show similar declining trends with the carbonate 87Sr/86Sr record. Using a simple ocean Li-Sr box model, we propose a reduced weathering scenario during the terminal Ediacaran (∼549 Ma) to explain the seawater Li-Sr isotope covariations. Our study suggests considerable fractionations of Li isotopes (∼17 ± 5 ‰) during clay-catalyzed dolomite formation and a reduced-weathering scenario during the terminal Ediacaran. This large Li isotope fractionation factor indicates the Li isotope fractionation factors during dolomitizations may vary widely and should be considered based on the type of dolomitization. More comparative studies on Li isotopes among coeval carbonates are expected to further explore the potential of dolostones in recording paleo-seawater Li isotopes.

A paradigm shift in Precambrian research driven by big data

The enigmatic nature of the Precambrian era poses ongoing challenges for researchers seeking to uncover its secrets. With the exponential growth of scientific data, there exists a vast repository of information through which these mysteries can be explored. However, this data is often derived from fragmented investigations of geological phenomena within specific disciplinary domains and limited spatiotemporal boundaries, resulting in untapped potential for extracting undiscovered knowledge. To address this limitation, the field of big data science provides a foundation for multidisciplinary research on the geological evolution of the Precambrian. By harnessing the power of large-scale data integration and analysis, valuable insights into this pivotal era in Earth's history can be revealed. This paper offers a comprehensive overview of big data types in geoscience and elucidates common analysis methods. Through a case study focused on the North China Craton (NCC), we demonstrate the application of conjoint analysis to a dataset comprising rock and mineral geochemistry data. Employing local singularity analysis and wavelet analysis on zircon age frequency and Hf isotopic time series, we reveal a persistent long-term periodicity of 800–500 million years since 3.5 billion years ago. This finding indicates a co-evolution between the NCC and the global supercontinent cycle dating back to the Archean period. To investigate the formation of the NCC, we employ machine learning-based crustal thickness evolution reconstruction, which highlights arc formation during subduction as the primary factor, with regional mantle activities playing a secondary role in the convergence. Combining spatio-temporal evolution analysis of magmatic intensity and εHf(t) values, we infer that the development of the NCC primarily resulted from a prolonged process of accretion targeting the Eastern Block (the primary continent nuclei) through the incorporation of diverse arc massifs. This examination of the NCC serves as an example of how data collection, processing, and utilization can enhance our understanding of formational and evolutionary processes, signaling a paradigm shift in Precambrian research driven by the integration of big data.

Crustal and tectonic structure of Northern Mozambique inferred by 2D gravity modeling

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.

Carbonate Resources in Viet Nam: Exploiting, Processing and Using

Vietnam has a carbonate rock distribution area of about 60,000 km2, accounting for nearly 20% of the territory's area. Carbonate rocks in Vietnam are located in many different stratigraphy, their ages from Pre Cambrian to Triassic. Carbonate rocks in Vietnam include limestone, marble, and dolomite. Carbonate rock has been made up for hundreds of millions of years. However, the use of carbonate rock resources in Vietnam is inconsequential, reducing its value. The author of the article introduces an overview of carbonate rock resources in Vietnam, and the reality of exploiting and processing carbonate resources in Vietnam. Since then, gave warnings about illogical in the use of carbonate rock resources. At the same time, it also makes recommendations for the rational use of carbonate rock resources for sustainable development.

An Absentological Analysis of the Trace: Pre-Cambrian Arche-Writing, and Jacques Derrida’s Realism

The first trace-fossil in the history of terrestrial life dates to the pre-Cambrian era. Left by an unknown species around 542 million years ago, Treptichnus are fossilized mud burrows, remaining as a geological testament to the early stages of complex life on Earth. Because of the impossibility of any empirical knowledge relating to these unfossilizable creatures, which presumably lacked a skeletal structure, any philosophical treatment of this paleobiological matter of fact must necessarily engage in speculation. Absentology as a speculative epistemontological register allows us to conceptualize these strange burrows as a key event. Following Jacques Derrida’s concept of"arche-writing", our essay presents an absentological reading of the forever unknowable unfossilized animal species. Arche-writing for Derrida is an abstract mode of writing that precedes speech and actual written language, hence this constitutes a concept that can be used for prelinguistic modes of expression. The trace fossils left by these unknown creatures constitute a type of prewriting, as well as the dawn of work, representing a crucial step in the evolution of complex life on this planet. A fossil that is not the animal itself, but rather a trace referring to an unknown organic singularity, this is the absent scene of arche-writing. A more realist Derrida emerges from this encounter, for whom extra-textual elements are even more relevant than explicit language.

Precambrian tsunamis in the light of the modern data

Background. In the geological history of the Earth, tsunami events attract particular research attention. Such events are assumed to have taken place already since the Precambrian period. However, the information on Precambrian tsunamis requires systematic generalization. Aim. To generalize the data published on Precambrian tsunamis with a particular focus on their age, distribution, and possible triggers. The character of information about these natural catastrophes also presents interest. Materials and methods. A bibliographical review was conducted based on the developed systematization criteria. The information was collected with the Scopus database. A total of 39 sources (articles in the leading scientific journals) were analyzed. Results. The evidence of tsunami events was obtained for a large part of the Precambrian interval for different regions of the planet. The highest concentrations of the studied catastrophes were established for the end-Early Archean and the Early Proterozoic. Cosmic impacts and earthquakeswere indicated among the triggers. The oldest tsunamis were commonly interpreted by analyzing the composition and textures of rocks. These interpretations frequently proposed no alternative explanations. Discussion. The available information on Precambrian tsunamis lacks completeness. Two hypotheses were formulated, those assuming the influence of the varied frequency of cosmic impacts and the initiation of lithospheric plate tectonics on the occurrence of tsunamis in the Precambrian. Conclusion. Previous studies suggest a wide manifestation of tsunami events in the Precambrian. Further research in this direction seems promising, both for Russian and foreign geologists.

Microbially induced sedimentary structures from the Ediacaran of Anti-Atlas, Morocco

The Eastern Anti-Atlas of Morocco hosts an early Ediacaran turbiditic series (Saghro Group) (630–600 Ma) unconformably overlain by thick late Ediacaran (580–550 Ma) terrestrial volcano-clastic formations (Ouarzazate Supergroup), with thin and geographically limited paralic shallow marine sedimentary rocks.This paper presents the first description of structures related to the former presence of extensive microbial mats developed in marine, fluvial, and lacustrine environments during the Ediacaran in the Eastern Anti-Atlas. These microbially induced sedimentary structures (MISS) are largely found in well-laminated fine- to coarse-grained sandstone and sandy-carbonate. They also cover vast bedding planes and occur in almost all sedimentary successions. MISS types include: gas domes, wrinkle structures, reticulate patterns, overflips and roll-ups, multidirectional linear ridges, sand cracks and biolaminated deposits. Based on morphology and petrographic macro and microfabrics, these microbially induced structures are very similar to those of modern photosynthetic cyanobacteria mats. Together with previously reported stromatolites, these newly reported microbial mat structures could have played an important ecological role in stabilizing siliciclastic sediments, as well as sustaining localized zones of high oxygen production in the Ediacaran marine and terrestrial paleoenvironments of the Anti-Atlas. The widespread geographic distribution and consistent occurrence of microbially induced sedimentary structures (MISS) in fluvial and lacustrine sediments present compelling paleontological evidence supporting the extensive greening of the land surface during the late Precambrian period.

Dating Precambrian sedimentary carbonate strata by in situ U–Pb isotopes of dolomite

Precambrian sedimentary carbonate succession ages are challenging due to the lack of suitable fossil records and mineral chronometers and techniques. Here we present the first result for in situ LA-ICP-MS U–Pb dolomite dating from the Dengying Formation in the Mayuan area, Shaanxi Province, South China. The sample yields a date of 565.0 ± 5.5 Ma (2σ, MSWD = 2.8, n = 47). This age agrees well with regional Ediacaran successions in the Yangtze Block. The new ages are considered alongside regional correlations of Ediacaran successions in South China and help to re-evaluate the chronostratigraphic framework of the Dengying and Doushantuo Formation. It also opens a new window for dating those blind sedimentary carbonate strata, particularly during the Precambrian era.

Spatially heterogeneous lithospheric architecture of the Cambay rift basin and adjoining Aravalli-Delhi Fold Belt, western India – A synthesis of magnetotelluric results

The Cambay rift basin (CRB) evolution has been associated with separation of the Indian continent from the African continent and subsequent interaction with the Réunion mantle plume, which resulted in significant alternations in the regional lithospheric structure of western India, more prominently in the CRB due to its proximity to the plume track. In our continued effort to delineate the lithospheric structure of the CRB and adjoining regions, we acquired magnetotelluric (MT) data at 31 sites along a profile across the CRB and analyzed these. The 2D geoelectric model derived from this dataset reveals a collage of conductive and resistive formations. The resistive blocks indicate the Archaean lithosphere on the west, the uplifted crust within the CRB, and various structural units of the Precambrian Era on the east providing evidence for continuation of the Aravalli-Delhi Fold Belt trend beneath the CRB into Saurashtra. The conductive anomalies beneath the CRB infer the magmatic underplating associated with thermal influx derived from the upper mantle as a result of the Réunion plume interaction. Integration of previous geophysical and present results infers a spatially heterogeneous lithosphere possibly representing an assemblage the Archaean and Proterozoic lithospheres beneath the CRB. The Proterozoic lithosphere is more vulnerable to the impact of the Réunion plume due to its weak nature in comparison to the Archaean lithosphere. The Archaean lithosphere on the western side of CRB indicates initial stage of rifting, whereas Proterozoic lithosphere infers second stage coeval with the Deccan volcanic eruption. The heterogeneity in sedimentary thickness within the CRB spatially correlates with the contact of Archaean and Proterozoic lithospheres, which might have played a role in the formation of the basin structure, and sediment deposition.

Decratonised lithosphere associated with mantle plume upwelling in the Singhbhum craton, eastern India based on geophysical and geodynamic perspective

The mode of crustal and lithospheric mantle evolution of cratonic blocks and their subsequent deformation and decratonisation due to regional plate tectonics and continued intraplate geodynamic process, are not well understood. This is especially true for the highly complex Eoarchean Singhbhum craton, located in the eastern part of the Indian shield, which underwent prolonged episodes of intraplate volcanism, mafic dyke intrusions, rifting, collision and widespread sedimentation lasting for over two billion years, leaving behind noticeable imprints in the crust and mantle lithosphere. Our detailed analysis of the geophysical characteristics indicates high crustal velocities and presence of a pronounced metasomatised zone between the depth 14 km and 30 km, which is characterised by drop in Vs from 3.93 km/s to 3.76 km/s. This zone is further followed by 14 km thick high velocity magmatic crust above the Moho. A substantial part of the upper crust has been eroded away from this craton due to thermal-induced uplifting and massive crustal exhumation, caused by the multiple hot mantle plume interactions during Precambrian period, in which mantle potential temperature and pressure reached as high as 1700 oC and 4.4 GPa respectively. This craton is conspicuously associated with highly positive gravity anomalies (up to +10mGal), which are well correlated with high elevation and the location of mafic volcanic suites. It is also characterised by an unusually thin lithosphere (∼ 60-128 km), high Moho temperatures (910°C) and high dose of heat flow (47mW/m2) emanating from the mantle, which conforms with the estimated low effective elastic thickness of ∼30 km. Transient effects of the paleo-thermal anomalies possibly still persist due to periodic rejuvenation of surrounding rift valleys and suture zones. Eventually, this craton now shows geophysical characters of more or less a mobile belt, not of a typical craton. Since, almost 150-200 km thick mantle lithosphere from the bottom has been eroded away from this region due to persistent thermo-geodynamic activities and mantle upwelling induced rise of mantle isotherms, our study does not favour the idea of cratonic stability and preservation of deep continental roots.

Deformation Episodes in Iron Formation of Eastern Province of North Odisha Iron Ore Craton, Eastern India

Banded Iron Formation (BIF), a bi-component rock of the Precambrian period is exposed along with iron ore in distinct geographical entities encircling the North Odisha Iron Ore Craton (NOIOC) in Odisha – Jharkhand states, eastern India. Iron formation of the eastern province is confined to Badampahar-Gorumahisani-Sulaipat belt. The litho assemblages belonging to this Iron Ore Group comprise of banded cherty quartzite, banded magnetite quartzite, banded magnetite grunerite quartzite, tremolite-actinolite schist and fuchsite quartzite. Deformations in phases affected the BIF members and associated rocks of the area resulting in successive fold structures. The first generation folds (F1) are characteristically tight and isoclinal having NE plunging axes. The second phase fold (F2) structures in the area with reference to first fold are co-axial, upright and tight to open in nature profusely overprinting the F1 folds are parallel to the general trend (NE-SW) of the belt. Axial plane of the third phase folds (F3) are gentle and broad warps having NW-SE trending axial planes and are found to be the last traceable ones in the area. trending in NW-SE direction are found to be the last traceable ones in the area having gentle and broad warps. The co-axial F1 and F2 folds along the general trend (NE-SW) of the belt are superposed by NW-SE trending F3 fold, which exhibits a geometric configuration as F1 // F2 F3. Such type of multiphase deformed terrain has produced many interference fold patterns in minor scale out of superposition i.e. dome and basin structures, hook shaped patterns, eyed fold and S, Z, and M shaped folds. The paper discusses the episodes of structural events and their signatures in the interference fold patterns in the eastern province of the NOIOC. Keywords: Banded Iron Formation, Badampahar-Gorumahisani-Sulaipat Belt, Deformation Episodes, NOIOC

Influence of Different Types of Clay Minerals on the Shape and Form of Silica-Carbonates (Biomorphs) of Ca(II), Ba(II), and Sr(II)

The array of atmospheric and chemical conditions that prevailed during the Precambrian era favored the origin of life in our planet. The minerals and rocks that existed in that era catalyzed the synthesis of the first biomolecules. It has been shown that mineral clays possess the best-suited mineral surface to study the polymerization of protobiomolecules because they catalyze the binding of monomers to form peptides and nucleic acids and foster the binding between them. Inorganic structures exist formed by silica-carbonates of calcium, barium, or strontium, called biomorphs, which emulate the morphological structure of diverse organisms. Some of these morphologies resemble several of the microfossils found in the Precambrian cherts. Notwithstanding, it has not been documented yet whether biomorphs are a consequence of the dissolution of clays in alkaline environments (rich in alkaline earth metals) during the initial stages of the Earth, which would favor the hypothesis that the biomorphs or cherts existed since that time. To know whether biomorphs could have been embedded within minerals or in diverse types of clays and contributed to the synthesis of protobiomolecules, we aimed at synthesizing biomorphs in the presence of different clays of natural origin in two synthesis conditions that resemble both the atmosphere of the Precambrian era and that of the current time, regarding the CO2 concentration. Our results revealed that in the condition emulating the Precambrian, polymorphs of calcite, aragonite, and vaterite were formed. The barium and strontium biomorphs adopted the morphology of radiolarians, diatoms, and foraminifers in this same condition, indicating that they could be the first structure of these organisms. Results also revealed that the clays present in the Precambrian together with the prevailing environmental conditions played a preponderant role as catalyzers in the structural morphology, chemical composition, and crystalline habit adopted by the first organisms. Biomorphs could have been the first inorganic structures with a structural order and characteristic shape (preserving biomolecules in their interior when they were formed) that were synthetized in the early era of our planet, but they have not been dated as a fossil registry.

Mineralization Based on CSAMT and SIP Sounding Data: A Case Study on the Hadamengou Gold Deposit in Inner Mongolia

The Hadamengou deposit is the largest gold deposit in Inner Mongolia. However, given that the sources of ore-forming alkaline magmatic hydrothermal solutions and ore-controlling structures are still controversial, the theories behind the genesis of the deposit have been controversial. In this study, four controlled-source audio magnetotellurics (CSAMT) and spectral induced polarization (SIP) profiles in the mining area were used to obtain the underground resistivity model and the pseudo section map of the apparent frequency dispersivity based on fine inversion. In the resistivity model, there are two high-resistivity blocks with resistivity greater than 3000 Ω m and three low-resistivity channels with resistivity less than 50 Ω m. Combined with the regional geological and drilling data, it is inferred that the high-resistance bodies, R4 and R5, may be alkaline magmatic intrusions related to multiple stages of magmatic hydrothermal activities, ranging from the Precambrian to Yanshanian periods. The highly conductive channels, C3, C5, and C4, may represent the Baotou-Hohhot fault, secondary faults, and ductile shear zone, respectively, which were formed in the Precambrian era and underwent multiple activations during the Hercynian to Yanshanian period. According to the spatial relationship, it is inferred that the ductile shear zone is an important ore-controlling and ore-hosting structure. However, the Baotou–Hohhot fault may be a pre-metallogenic fault rather than an ore-controlling fault. By comparing the resistivity model with the pseudo section of the apparent frequency dispersivity, it was found that all the known gold veins are located in the superimposed area of low resistivity and high-frequency dispersivity. It is speculated that the ductile shear zone outside the alkaline magmatic rock with the superimposed characteristics of low resistivity and high-frequency dispersivity is the favorable area for mineralization.

Protection of the DNA from Selected Species of Five Kingdoms in Nature by Ba(II), Sr(II), and Ca(II) Silica-Carbonates: Implications about Biogenicity and Evolving from Prebiotic Chemistry to Biological Chemistry.

The origin of life on Earth is associated with the Precambrian era, in which the existence of a large diversity of microbial fossils has been demonstrated. Notwithstanding, despite existing evidence of the emergence of life many unsolved questions remain. The first question could be as follows: Which was the inorganic structure that allowed isolation and conservation of the first biomolecules in the existing reduced conditions of the primigenial era? Minerals have been postulated as the ones in charge of protecting theses biomolecules against the external environment. There are calcium, barium, or strontium silica–carbonates, called biomorphs, which we propose as being one of the first inorganic structures in which biomolecules were protected from the external medium. Biomorphs are structures with different biological morphologies that are not formed by cells, but by nanocrystals; some of their morphologies resemble the microfossils found in Precambrian cherts. Even though biomorphs are unknown structures in the geological registry, their similarity with some biological forms, including some Apex fossils, could suggest them as the first “inorganic scaffold” where the first biomolecules became concentrated, conserved, aligned, and duplicated to give rise to the pioneering cell. However, it has not been documented whether biomorphs could have been the primary structures that conserved biomolecules in the Precambrian era. To attain a better understanding on whether biomorphs could have been the inorganic scaffold that existed in the primigenial Earth, the aim of this contribution is to synthesize calcium, barium, and strontium biomorphs in the presence of genomic DNA from organisms of the five kingdoms in conditions emulating the atmosphere of the Precambrian era and that CO2 concentration in conditions emulating current atmospheric conditions. Our results showed, for the first time, the formation of the kerogen signal, which is a marker of biogenicity in fossils, in the biomorphs grown in the presence of DNA. We also found the DNA to be internalized into the structure of biomorphs.

Will Earth's next supercontinent assemble through the closure of the Pacific Ocean?

Earth's known supercontinents are believed to have formed in vastly different ways, with two endmembers being introversion and extroversion. The former involves the closure of the internal oceans formed during the break-up of the previous supercontinent, whereas the latter involves the closure of the previous external superocean. However, it is unclear what caused such diverging behavior of supercontinent cycles that involved first-order interaction between subducting tectonic plates and the mantle. Here we address this question through 4D geodynamic modeling using realistic tectonic set-ups. Our results show that the strength of the oceanic lithosphere plays a critical role in determining the assembly path of a supercontinent. We found that high oceanic lithospheric strength leads to introversion assembly, whereas lower strength leads to extroversion assembly. A theoretically estimated reduction in oceanic crustal thickness, and thus its strength, during Earth's secular cooling indicates that introversion was only possible for the Precambrian time when the oceanic lithosphere was stronger, thus predicting the assembling of the next supercontinent Amasia through the closure of the Pacific Ocean instead of the Indian-Atlantic oceans. Our work provides a new understanding of the secular evolution of plate tectonics and geodynamics as the Earth cooled.

The Effect of DNA from Escherichia Coli at High and Low CO2 Concentrations on the Shape and Form of Crystal-line Silica-Carbonates of Barium (II)

The synthesis of nucleic acids in the Precambrian era marked the start of life, with DNA being the molecule in which the genetic information has been conserved ever since. After studying the DNA of different organisms for several decades, we now know that cell size and cellular differentiation are influenced by DNA concentration and environmental conditions. However, we still need to find out the minimum required concentration of DNA in the pioneer cell to control the resulting morphology. In order to do this, the present research aims to evaluate the influence of the DNA concentration on the morphology adopted by biomorphs (barium silica-carbonates) under two synthesis conditions: one emulating the Precambrian era and one emulating the present era. The morphology of the synthetized biomorphs was assessed through scanning electron microscopy (SEM). The chemical composition and the crystalline structure were determined through Raman and IR spectroscopy. Our results showed that DNA, even at relatively low levels, affects the morphology of the biomorph structure. They also indicated that, even at the low DNA concentration prevailing during the synthesis of the first DNA biomolecules existing in the primitive era, these biomolecules influenced the morphology of the inorganic structure that lodged it. On the other hand, this also allows us to infer that, once the DNA was synthetized in the Precambrian era, it was definitely responsible for generating, conserving, and directing the morphology of all organisms up to the present day.