Abstract:Unified Archean continental core is of great significance to the study of the tectonic evolution of Precambrian continental crust. The Archean continental core in the eastern block of the North China Craton is greatly affected by the Tan-Lu fault, including the early NNE-trend sinistral strike-slip movement in the southern segment of the Tan-Lu fault and the later NE-trend sinistral strike-slip movement in the southern segment of the Tan-Lu fault. This study restores the original pattern of the Archean continental crust in the eastern block of the North China Craton before the development of the Tan-Lu fault. The structural recovered ancient terrane and the gneissic foliations of the rocks all show the NNW-trending feature. Based on our structural analysis of the Gongchangling BIF area, a large number of thrust structures suggestive of a horizontal movement were developed in the ore-bearing Archean supercrustal rocks. Combined with geochronological age-dating of this Archean structure in the Gongchangling BIF, this paper further reveals that lateral compression structures (horizontal movement) may have occurred in the North China Craton at the end of the Neoarchean.

Abstract:In recent years, geologists have paid more and more attention to the potential of tungsten and tin metallogenic of Caledonian batholith in Nanling metallogenic belt. In order to evaluate the tungsten and tin metallogenic potential of the Penggongmiao pluton in Hunan Province, mineralization age of the Shiniuxian tungsten deposit, diagenetic age and geochemical characteristics of biotite granodiorite from the Penggongmiao pluton are analyzed in this paper. The LA-ICP-MS zircon and monazite U-Pb ages of the coarse-grained biotite granodiorite of the Penggongmiao pluton are 436.1±2.5 Ma (MSWD=1.9, n=19) and 436.8±2.8 Ma (MSWD=2.7, n=20), respectively, while the muscovite ³⁹Ar/⁴⁰Ar isotopic dating of the Shiniuxian tungsten deposit has a plateau age of 150.2±1.2 Ma (MSWD=0.42). The results show that the diagenesis of rocks occurred in Early Silurian, while the mineralization of tungsten is dated to late Jurassic, and there are the products of different magmatic activities. Compared to the typical tungsten-tin granite in Nanling metallogenic belt, the Penggongmiao granite has low degree of differentiation and low content of ore-forming elements. In addition, the Penggongmiao granites are mainly derived from the poor-clay metasandstone of the upper crust, while the typical tungsten-tin granites are usually derived from the rich-clay of the upper crust material. The above evidences indicate that the mineralization potential of the Caledonian Penggongmiao pluton is limited. Finally, on the basis of comprehensive previous research results, the authors point out that the metallogenic potential of the Late Jurassic granite dikes or stocks in and around the Penggongmiao batholith should be evaluated by integrating geophysical, geochemical, structural and alteration information.

Abstract:The basement properties and crustal growth of the Humber belt of Newfoundland Island in the Appalachian orogenic belt, Canada, have been the focus in recent years. In particular, the age composition and isotopic characteristics of the Indian Head Range block in the southwestern part of Newfoundland are significant for dividing and comparing the tectonic attributes of the regional basement. In this paper, the zircon U-Pb dating of the monzogranite pluton in the Indian Head Range block shows that the pluton has a late Mesoproterozoic age (1 149 ±4 Ma), which provides new age evidence for the existence of the Greenville magmatic events in the block. The results of the Nd-Hf isotope study show that the εNd value of the monzogranite is -2.3, the εHf value varies from +1.93 to +3.65, and the t_DM2 age ranges from 1.84 to 1.73 Ga. Combined with previous studies, the authors believe that three stages of granitic magmatic events of~1.5 Ga,~1.15 Ga, and~1.0 Ga occurred in each block in the Humber belt, which have similar Hf model ages, suggesting that they all originated from the reconstruction of Paleoproterozoic juvenile crustal materials. The Greenville basement blocks in the Humber belt are all in-situ basements, and have the same magmatic-tectonic evolution history with the eastern margin of the far end of Laurentian continent. The results of this study provide new constraints on the affinity and crustal growth of the Greenwell basement in the Humber belt, and provide a basis for the traceability and comparison of ancient micro-continents in the Appalachian orogen.

Abstract:Huanggangliang volcanic-extrusive uplift in the southern Da Hinggan Mountains is composed of the rhyolitic crystalline tuff of the ash flow facies, the dome of the extrusive facies (rhyolite porphyroclastic lava), porphyritic monzogranite of the superficial intrusive facies. Their SHRIMP zircon U-Pb ages are 140.27±0.93 Ma, 140.41±0.92 Ma and 141.75±0.96 Ma respectively, which were produced by magmatic activities in Early Cretaceous. The isotopic ages of the three lithofacies are consistent within the error range, indicating that there is no obvious discontinuity between the three lithofacies, and they are the products of continuous action of thick rich crystal magma (crystal mush). These volcanic-intrusive complexes belong to the high-K calc-alkaline series, and are mainly peraluminous and quasi-aluminous rocks, their εNd(t) change little which range from -0.43 to -0.08, and the corresponding two-stage Nd model ages range from 0.98 to 0.96 Ga, suggesting that originated from the same source region. The contents of SiO₂ and K₂O in magmatic products decreased continuously from early to late, and there is a certain complementary relationship between the compositions of different lithofacies, suggesting that rhyolitic crystalline tuff and rhyolite porphyroclastic lava may be discharged/emplaced layer by layer by magma chamber of composition zonation, and the residual magma is filled into the ring fissure of volcanic root and surrounding to form porphyritic monzogranite. The volcano-intrusive complex have the characteristics of A-type granite, which are characterized by LILE (Rb, Th, U, etc.) enrichment and HFSE (Ti, Nb, Ta, etc.) strong depletion, and enriched LREE patterns with strong negative Eu anomaly, and its genesis may be related to partial melting of the overlying crust induced by the upwelling of asthenosphere mantle or mafic magma underplating in the Early Cretaceous.

Abstract:Vesta is the largest silicate asteroid in the solar system, and its rock samples (HED meteorites) are among the oldest magmatic rocks in the solar system, possibly recording important information about the earliest geological fluid activities of terrestrial planets. For the first time in this work, a thicker and longer Fe-rich olivine vein was found in a piece of unbreccia equilibrium Eucrite NWA 11592. Through detailed research of petrographic and geochemical characteristics of the NWA 11592 meteorite, NWA 11592 is classified as basaltic unbreccia Eucrite, with an impact metamorphism degree of at least S4 and a thermal metamorphism degree of type 6. The Fe-rich olivine veins in NWA 11592 is most likely to be the precipitation products of H₂O-bearing fluids along the fractures. The reaction system should be open and relatively oxidized (f_O2 up to IW+0.9), and it should occur at a burial depth of > 4 km in the shallow crust of Vesta. The infiltration of H₂O-bearing fluids not only occurs more on the surface or near the surface of Vesta, but may also occur in the shallow crust of Vesta's interior.

Abstract:Enrichment of rare earth associated with phosphate ore is an important source to obtain rare earth resources. The phosphorite type rare earth deposits are widely distributed in China. The ore has high recovery value because of its high-content rare earth, which makes the deposits become the associated rare earth resources second only to the independent rare earth deposits. The article mainly does research on the rare earth distribution in the phosphate ore of Anning in Yunnan. The study shows that the total amount of rare earth oxides in the ores is between 72×10^-6 and 1 050×10^-6. The statistical comparison confirms that the concentrations of rare earth elements are positively correlated with the phosphorus content in the phosphate ore. In addition, observing by optical microscope and electron microscope, there are few independent rare earth minerals in Anning phosphate mine, and only independent rare earth minerals (probably monazite and allanite)are found in part of glauconite. The results of LA-ICP-MS indicate that the concentration of rare-earth elements in collophane is between 770×10^-6 and 920×10^-6, and the concentration of rare-earth elements in dolomite is lower than 34×10^-6. The average concentration of rare earth elements in quartz is about 180×10^-6. The concentration of rare earth elements in glauconite is as high as 2 947.27×10^-6~3 159.87×10^-6 due to the existence of independent rare earth minerals. The whole research results show that the rare earth elements in Anning phosphate deposits mainly exist in collophane in the form of isomorphic substitution.

Abstract:The Mesoproterozoic Changzhougou Formation is the first set of sedimentary cover on the metamorphic crystalline basement of the Yanshan area in the northern margin of North China Craton. It unconformably covers all kinds of Neoarchean gneiss. Based on the field geological survey, grain size analysis and geochemical analysis test were carried out on the sandstone of Changzhougou Formation, to disclose the paleoenvironment, paleoclimate, material source, tectonic environment, and basin properties during this period. The results of rock assemblages, sedimentary structure, and grain size analysis indicate that the sedimentary environment evolution of Changzhougou Formation is alluvial fans, braided rivers, and clastic tidal flats, from bottom to top. The geochemical characteristics of sandstones in Changzhougou Formation are characterized by high SiO₂, Al₂O₃, K₂O, and low TiO₂, Fe₂O₃, FeO, and MgO contents with high maturity. The chemical alteration index (CIA) varies from 52.00 to 73.23, and the chemical weathering index (CIW) ranges from 93.04 to 98.68. Due to the influence of potassium replacement, combined with A-CN-K diagram, Th/U-Th diagram, and paleoclimate discrimination diagram, the provenance may have experienced strong weathering, implying warm and humid paleoclimate. The ratios of Cr/Zr, Th/Sc, Ba/Sr, Rb/Sr, and La/Th-Hf diagrams indicate the provenance of Changzhougou Formation from the upper crustal environment, and the sediments were sourced predominantly from felsic rocks. The discrimination diagram of the tectonic setting shows that the sandstone of Changzhougou Formation was formed in the craton basin, that is, the Yanliao Aulacogen might be produced in the internal rift of the craton. In addition, the ratios of Tb/Yb, La/Sc, La/Th, and Th/Sc indicate a few obvious mantle materials in the sandstones. Therefore, the Yanliao Aulacogen is presumed to be the coastal-epicontinental sea formed on the continental crust basement of the North China Craton, not to the extent of continental crust rupture and oceanic crust occurrence.

Abstract:Carbonates are ubiquitous, forming in a wide range of settings including caves, soils, the oceans, during burial from hydrothermal fluids, and along faults, with recording the processes of fluid occurrence. Thus, accurate ages of the minerals are necessary to understand the lifespan of fluid events. However, low uranium carbonates are difficult to date using traditional U series dating and isotope dilution due to ultra-low concentrations, the lack of ideal standards and the time-consuming process. With the recent advent of in-situ high precision analysis techniques, LA-ICP-MS has made significant progress in obtaining more accurate dating results with the advantages of high spatial resolution and rapid data acquisition and has been widely used in different geological fields. Herein, this paper investigates the research progress for carbonate U-Pb dating and introduces and discusses the related fundamentals and methodologies of the U-Pb dating system. The new technique with untapped potential for solving numerous geochronological problems from the timing of faulting and the age of sedimentation, ore deposits and diagenesis are furthermore reviewed in the present study. The applications mentioned have enriched the understanding of the formation and evolution of the crust and resolved some complicated evolution history in geosciences. In the future, it is promising that applying the U-Pb dating of carbonates and rare earth element analysis will be a significant development direction and provide new insights into carbonate geochronology studies. It is worth noting that the widespread use of U-Pb geochronology is the premise of application success.

Abstract:Recrystallization is a ubiquitous diagenetic process during dolomite formation, which is always characterized as a multi-stage dynamic system. The origin of dolomite, which is referred to as the "dolomite problem", has puzzled geologists. One of the most important reasons is that dolomite in dolomites recrystallization results in information, such as the petrological and geochemical characteristics, being covered during the process of dolomite formation. The recrystallization of dolomite in ancient strata of the geologic historical period and in modern sediment, the changes in petrological and geochemical characteristics observed in modern simulation experiments on dolomite recrystallization were systematically summarized through the investigation of previous national and international studies on recrystallization. Subsequently, the main conditions and factors influencing dolomite recrystallization are expounded, and the changes in the diagenetic environment during the diagenetic process, the stages of dolomite recrystallization, and the main variation character are analyzed. In addition, the significance of dolomite recrystallization is summarized. The purpose of this review is to provide an overview of and guidelines for research on dolomite recrystallization and benefit the study of the "dolomite problem" and carbonate diagenesis.

Abstract:Earthworms decompose ingested earth materials through interactions of small molecular organic acids with minerals to accelerate soil weathering. This process is difficult to be assessed in vivo because the average residence time of soils inside earthworm gut is on the scales of 12 hours, too short for minerals to exhibit sizable and visible dissolution features. In present study, earthworm weathering of calcite (CaCO₃) and K-feldspar (KAlSi₃O₈) is investigated in vitro using a mixed organic acid solution at pH 7 mimicking the composition and pH conditions of gut fluid. Experimental results showed that the dissolution rates experienced one order of magnitude increase relative to that in pure water, suggesting the occurrence of organic ligand-promote weathering. The observed correlation of dissolved cation concentrations to mineral particle sizes for calcite but not feldspar suggests the former dissociates directly in accordance with the stoichiometry while the latter dissolves following an incongruent pathway. Based upon this understanding, we further examined the dissolution kinetics using the initial rate method for feldspar and the shrink core model in conjunction with the Hixson-Crowell equation for calcite. The theoretical analyses indicate feldspar dissolution initiates as K⁺ release from mineral surfaces whereas calcite weathering is chiefly limited by the rate of reactant diffusion in solutions. These findings are in agreement with the known mechanistic framework for calcite and feldspar dissolution, but showcase the importance of ligands, instead of protons, to earthworm digestion of minerals in vivo.

Abstract:The Huangshui Creek in Shimen, Hunan Province was seriously contaminated by historical realgar mining area. Discussing the diel variation of arsenic in creeks and the diurnal regularity of algal-arsenic mineral water-rock interaction is of great significance for understanding the migration behavior of arsenic in the watershed and controlling contamination. In this research, the diel variations of arsenic concentration and its hydrochemical parameters were investigated in the field,and the algae species in the Huangshui Creek were separated in laboratory, and the growth of algae and the kinetics of arsenic release from arsenic minerals(realgar) were studied under simulated photosynthesis. The results showed that the arsenic concentration in the creek ranged from 0.8 to 1.1 mg/L, decreased at night and increased during the day, and the arsenic stratification effect was the most obvious at the lake mouth. The changes of temperature, pH value, dissolved oxygen and carbonate content were consistent with those of arsenic concentration, but the changes of chlorophyll a and bicarbonate content were opposite to those of arsenic concentration; The algae species in the Huangshui Creek were abundant and had been separated such as Chlorella, Spirogyra, Scenedesmus, etc. In the experiment, compared with pure realgar, low concentration algae can promote the release of 182.1 mg As (Ⅲ) and 459.3 mg As (Ⅴ) per gram of realgar after 48 hours of action. There was a significant absorption phenomenon in medium concentration algae, and As (Ⅲ) was better than As (Ⅴ). High concentration algae promoted the release of realgar and significantly increased the release of As (Ⅴ), which was 2.9 times that of pure realgar. The experimental results showed that the diel variation can also change the concentration and valency states of arsenic, and the presence of algae played an important role.

Abstract:In order to explore the influence of natural clay minerals and organic matter on the migration and retention of nano emulsified oil in porous media, kaolinite and montmorillonite, as well as humic acid, a typical representative of organic matter, were selected to carry out a batch of experiment on the adsorption of nano emulsified oil by single mineral, organic matter and organic mineral complex. The adsorption mechanism was discussed by means of full analysis of specific surface area, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR),X-ray diffraction (XRD) and other techniques. The experimental results showed that the adsorption of nano emulsified oil by the media was in accordance with Freundlich model. The adsorption capacity of single mineral and humic acid to nano emulsified oil is as follows:montmorillonite>humic acid>kaolinite, the adsorption capacity of organic mineral composite samples is as follows:montmorillonite-humic acid>kaolinite-humic acid, which are larger than their corresponding single samples, and the phenomenon of "1+1>2" appears, indicating that the more complex the medium composition is, the greater the degree of adsorption and retention of nano emulsified oil is. Further analysis confirmed that nano emulsified oil was mainly adsorbed on the surface of minerals and humic acid through hydrogen bond and hydrophobicity, and the surface structure and properties are the dominant factors in the adsorption process of kaolinite and montmorillonite, so montmorillonite has stronger adsorption capacity, and the adsorption of humic acid is mainly realized through the aggregation between particles. For the composite samples, the adsorption is mainly realized by hydrogen bonding, ligand exchange and hydrophobicity. Combination of humic acid and mineral can increase the sorption sites and enhance the hydrophobicity of mineral surface, thus promoting the sorption. The co-adsorption and cumulative adsorption of humic acid and nano emulsified oil increased with the increase of emulsified oil concentration, which made the adsorption promotion of kaolinite humic acid stronger. With the increase of the concentration of emulsified oil, the humic acid and sorption sites that play the role of "bridge" decreased, which weakened the promoting effect of montmorillonite. The experimental results lay a foundation for further evaluation of migration and retention of nano emulsified oil in porous media.

Abstract:At present, about 80 percent of rough sapphire mined from the Mogok mine in Myanmar must be optimized before being put into the market, mainly heat treatment. In this paper, the sapphire from Baw-mar mine, Mogok, Myanmar is heat treated with different temperature regimes, and electron microprobe, X-ray powder crystal diffractometer (XRD), ultraviolet-visible-near infrared spectrometer, fourier infrared spectrometer and laser raman spectrometer were used to compare the spectroscopic characteristics before and after heat treatment. The results show that after heat treatment at 1 300℃, all XRD peaks of sapphire with 2θ<60° begin to shift to low angle direction, and the ratio of unit cell parameter c/a decreases with the increase of heat treatment temperature, which is presumed to be related to the distortion of its crystal at high temperature. The main chromogenic elements of sapphire in Baw-mar mining area are Fe, Ti and V, among which Fe and Ti together cause it to be blue, V makes it slightly green, and the gray color of some samples is mainly caused by Ni. After the heat treatment, the charge transfer of Fe²⁺-Ti⁴⁺ is enhanced, and the charge transfer of Fe²⁺-Fe³⁺ is weakened, resulting in an enhanced 585 nm ultraviolet absorption band and a weakened absorption peak at 746 and 764 nm. At the same time, the color of the sample turns blue and the gray tone weakens. In the infrared spectra, the sample appears at 1 988, 2 123 cm^-1 diaspore hydroxyl frequency doubled vibration absorption peaks and 3 619, 3 696 cm^-1 kaolinite outer hydroxyl and inner hydroxyl vibration absorption peaks. After the heat treatment, the diaspore and kaolinite are completely dehydrated, and the crystal structure is destroyed, resulting in the disappearance of all the hydroxyl absorption peaks. After heat treatment at 1 100℃, the Raman peak at 1 324 cm^-1 appeared and gradually increased with the increase of temperature. It is speculated that it is caused by the reaction of molten borax and Al₂O₃ at high temperature to form glassy substances along the cracks and enter the interior of the sapphire. The research in this paper also provides ideas and basis for further discussion of its color changing process.