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Ca2+, Mg2+, and Sr2+ are elements with similar ionic and hydrochemical characteristics, yet the microbial mineralization behavior in their coexisting environments is seldomly explored. In this study, the cyanobacterium Synechocystis sp. PCC6803 was used to induce the precipitation of minerals in mediums with various Mg/Ca and Sr/Ca ratios (Ca2+ = 0.01 M). The medium hydrochemistry, including cell density, solution pH, and alkalinity, was recorded periodically. The bio-precipitates were characterized with X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), Fourier Translation Infrared spectroscopy (FT-IR), and Thermal Gravimetric Analyzer (TGA). The results show the growth of Synechocystis sp. PCC6803 was inhibited by increasing ionic strength, although the final alkalinity and pH values of the medium were not affected. Two crystalline minerals, calcite (CaCO3) and strontianite (SrCO3) were precipitated in the mediums with low ionic strength; these were transformed from early amorphous precipitates by a dissolution and re-precipitation mechanism. The morphology of the precipitated cyanobacterial strontianite changed from columnar to dumbbell shape and finally into a spherulite shape. High concentrations of Sr2+, like Mg2+, prolonged the stabilization of amorphous carbonate precipitates. The acidic amino acids (Glu and Asp) in the EPS of Synechocystis sp. PCC6803 cultured in mediums with high Sr2+ and high Mg2+ concentrations increased significantly, compared to those cultured in a medium with no Sr2+ or Mg2+ (p < 0.005) ions. The negative binding energy calculated by Density Functional Theory (DFT) on the binding between the two acidic amino acids (Glu and Asp) and ion-H2O complexes (Ca[H2O]62+, Mg[H2O]62+, and Sr[H2O]62+), indicating that they are all thermodynamically-favored processes. Consequently, lower energy was needed in their subsequent precipitation and nucleation within the EPS of Synechocystis sp. PCC6803. This inferred process was also supported by the appearance of amorphous particles in the EPS of Synechocystis sp. PCC6803. [ABSTRACT FROM AUTHOR]

The Jiaodong Peninsula is the most important gold mineralization area in China, and the formation of gold deposits is closely related to granitoids. The isotopic ages of the Early Cretaceous granodiorites in the northwestern Jiaodong Peninsula are concentrated in the range of 111~123 Ma, and are coeval with the formation of the gold deposits in the area. However, the studies on the geotectonic settings of the granodiorites, especially their petrogenesis and relationship with gold deposits in the northwestern Jiaodong Peninsula, are scarce. Based on field and petrographic observations, geochemistry, EPMA analysis, zircon U-Pb chronology, and Sr-Nd isotopes of the Early Cretaceous Zhouguan granodiorite in the Jiaodong area, the formation age of Zhouguan granodiorite is determined as 115 Ma ± 0.77 Ma; the analysis of EPMA shows that biotite is mainly composed of Fe-biotite and Mg-biotite, with its MgO content ranging from 9.797% to 11.635%. The crystallization temperature of biotite is in the range of 500 °C~625 °C and the emplacement depth of the rock mass is 3.98~8.71 km. The amphibole in the mass mainly includes magnesiohornblende, pargasite, and magnesiosadanagaite; among them, the former two are of crustal origin, while magnesiosadanagaite is of mantle origin. The crystallization pressure and depth of the former two are in the range of 0.75~3.02 kbar and 2.81~11.4 km, respectively, while the crystallization pressure and depth for the latter is 4.64 kbar and 17.53 km, respectively. The (87Sr/86Sr) values range from 0.710424 to 0.711074 and the (143Nd/144Nd) values range from 0.511530 to 0.511808. The parental magma of the Zhouguan granodiorite is highly oxidized with high-water content that is favorable for Au enrichment. Combined with the Nb-Y and Yb-Ta diagrams, a model describing the formation of Zhouguan granodiorite is proposed. [ABSTRACT FROM AUTHOR]

In the Upper Ediacaran Dengying Formation of the Sichuan Basin, the presence of abundant, well-preserved microbial carbonates provides a unique opportunity to study Precambrian paleoceanography and microbial carbonate origins. Particularly, the underexplored coated grain dolostones of this formation, characterized by distinct microbially induced fabrics and intragranular dissolution, offer crucial insights for understanding late Ediacaran microbial mineralization and diagenetic sequences. Utilizing selected typical samples, we conducted detailed petrographic and geochemical analyses, revealing a dynamic interplay between microbial processes and sedimentary dynamics. We observe the coexistence of constructive micrite envelopes with microbially induced fabrics such as clots and laminations, highlighting microbial biomineralization's key role in fabric formation. The sedimentary dynamics critically determines the formation processes of the coated grains: low-energy settings foster grain agglomeration and consolidation through clot precipitation between grains, while high-energy settings favor smaller grains binding to microbial mats. Geochemically, micrite envelopes play an essential role in preserving distinct rare earth element (REE) signatures. The weak negative Ce anomalies and positive Eu anomalies within these envelopes point to a suboxic to anoxic depositional environment, directly indicative of the microenvironmental conditions conducive to microbial mineralization processes. Furthermore, our study sheds light on the structural evolution of coated grains with hollow nuclei, proposing that their internal pore formations are influenced by both mineral instability and selective dissolution by meteoric freshwater. These findings not only provide fresh insights into complex diagenetic processes in the Dengying Formation but also substantially advance our understanding of early microbial life and environmental adaptations during the Precambrian. • Revealed the relationship between micrite envelopes and microbially induced fabrics • Proposed a novel formation mechanism for coated grain dolostone in the Dengying Fm. • Investigated the diverse environmental responses of microbiolite fabrics • Established micrite envelopes as dependable records of seawater REE compositions [ABSTRACT FROM AUTHOR]

• Accurately construct the three-dimensional lowest energy stable coal model. • Wetting mechanism of "anisotropic potential attraction and competitive adsorption". • Provide model and theoretical support for the optimization of dust spraying agent. Understanding the molecular structure of coal is crucial for gaining insights into the wetting mechanism of coal dust, thus enabling the precise and efficient management of coal dust. After determining the structural information and functional group composition of the coal samples, we continuously adjusted the positions of the groups and the linkages to construct a planar molecular model. Our findings indicate that the Daliuta coal molecule is primarily composed of aromatic carbons, with aliphatic carbons existing in branched form or linked to aromatic rings. The main type of oxygen is carbonyl oxygen, and the molecular formula for Daliuta coal was determined to be C 286 H 263 N 3 O 50 S. We optimized and annealed the molecular model geometrically, causing the aliphatic bonds in the molecule to undergo numerous deflections and folds, whereas the aromatic structure tended to arrange itself in a laminar pattern due to van der Waals interactions. Given the large number of oxygen-containing functional groups, the electrostatic potential energy contributes significantly to the non-bonding energy, ensuring the stability of the structure. Finally, we obtained the global energy-minimum three-dimensional macromolecular model, establishing the polymerized structure of the coal molecule with a density of 1180 kg/m3. Additionally, we quantitatively analyzed the region of weak interactions between the electrostatic potential on the surface of the coal at the molecular and intramolecular levels. This analysis helped elucidate potential adsorption sites, providing theoretical guidance for modeling the targeted preparation of a spraying dust-reducing agent suitable for this type of coal. [ABSTRACT FROM AUTHOR]

[Display omitted] • (1) Trachydacites have zircon U-Pb ages of 116 Ma and were coeval with the most extensive thinning of the North China Craton. • (2) 116 Ma trachydacites were related to subduction of Yangtze Craton and Paleo-Pacific plate. • (3) The mantle source underneath the southeastern North China Craton was modified by the subduction of the Yangtze Craton. The North China Craton has witnessed a large-scale lithospheric thinning event in the Mesozoic. The volcanic rocks of the Qingshan Group formed during the destruction of the North China Craton, therefore retaining important information to the deep processes in this region. Zircon U-Pb dating and geochemical analyses have been carried out on volcanic rocks of the Qingshan Group collected from southeastern margin of the Jiaolai Basin. In combination with previously published data on the volcanic rocks of the Qingshan Group, the newly acquired data show that: (1) the volcanic rocks of Qingshan Group in Mashan have SiO 2 content of 62.82 ∼ 66.3 wt% and total alkali content (K 2 O + Na 2 O) of 7.64 ∼ 9.34 wt%. According to TAS diagram, they belong to trachydacite which experienced strong fractionation between LREEs and HREEs with depletion of HFSEs and enrichment of LILEs. (2) The crystallization age of trachydacite in Mashan is 116.4 ± 2.3 Ma (MSWD = 1.9, n = 9). The magma originated from the partial melting of the ancient lower crust and the enriched lithospheric mantle metasomatized by the fluids/melts released from the subducted slab of the Yangtze Craton. (3) The formation age of magmatic rocks in western Shandong is generally earlier than that in eastern Shandong, while the lower crust delamination in western Shandong preceded that in eastern Shandong. The occurrence of magmatism in eastern Shandong is probably attributed to the delamination process in western Shandong as well as the ongoing tectonic activities along the Tan-Lu fault zone. The lithospheric thinning of the North China Craton was mainly controlled by the change of the subduction angle of the Paleo-Pacific plate, and is probably influenced by the continuous activity of the Tan-Lu fault zone in eastern Shandong. [ABSTRACT FROM AUTHOR]

Manganese (Mn) is a common trace element in dolomite, yet its precise role in dolomite precipitation, if any, has not been explored. This study aims to investigate carbonate mineral formation in the presence of extracellular polymeric substances produced by Bacillus licheniformis Y 1 in 14 cross-over experiments within the MgCl 2 -CaCl 2 -MnCl 2 system. The study involved the analysis and comparison of water chemistry, mineralogy and bacterial metabolites. The findings indicate that B. licheniformis Y 1 induces the formation of Mg-free calcite and low-Mg calcite in Mn-free solutions (Mg/Ca < 2). The addition of 0.001 mol/L Mn2+ results in the precipitation of Mg-rich calcite. In the presence of a relatively high Mg2+ content in the solution (Mg/Ca > 6), B. licheniformis Y 1 in a Mn-free solution induces the formation of aragonite and dypingite, whereas the addition of 0.001 mol/L Mn2+ leads to the formation of Mn-bearing dolomite in the precipitate. Notably, at Mg/Ca = 6, an increase in Mn2+ content of the fluid to 0.002 and 0.003 mol/L yields Mn-rich dolomite. The Mn-bearing dolomite exhibits a regular spherical aggregate morphology with diameters ranging from 15 to 60 μm. The 2θ position of the (104) crystal face is close to that of dolomite, and the thermal decomposition temperature is lower than that of calcite. XPS results show that Mn O bonds exist on the mineral surface. Acidic amino acids such as glutamic acid as well as humic acid in EPS, especially fulvic acid analogues, actually rise with increasing Mn2+ concentration and contain a large number of functional groups including carboxyl groups. Molecular dynamics simulations show that fulvic acid can effectively promote the dehydration of Mg-water complexes, thus promoting the formation of dolomite. These experiments indicate that the presence of Mn ions in the solution, along with bacteria and EPS, promote the precipitation of protodolomite. [Display omitted] [ABSTRACT FROM AUTHOR]

The assembly process of Organic Matter (OM) from single molecules to polymers and the formation process of Ca– CO 3 ion-pairs are explored at the micro-scale, and then the relationship between OM and carbonate based on the results of microbially-induced carbonate precipitation (MICP) laboratory experiments is established at the macro-scale. Molecular dynamics (MD) is used to model the assembly of OM (a) in an aqueous solution, (b) on surfaces of calcite (10 1 ‾ 4) crystals and (c) on defective calcite (10 1 ‾ 4) crystal surfaces. From the MICP experiments, carbonate minerals containing abundant OM were precipitated and were characterized by Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). The results of the MD show that OM is assembled into polymers in all three simulation systems. Although the Ca–CO 3 ion-pairs and OM were briefly combined, the aggregation assembly of OM molecules and the precipitation of carbonate calcium are not related in the long run. The highly specific surface area of the defective calcite shows an increase in the adsorption of OM. The van der Waals forces, which are primarily responsible for controlling the assembly of OM molecules, increase with the degree of aggregation. According to the MICP experiments, OM is enriched on the mineral surfaces, and more OM is found at the steps of defective crystals with their larger surface areas. Through MD and MICP laboratory experiments, this work systematically describes the interaction of OM and carbonate minerals from the micro to the macro scales, and this provides insight into the interaction between OM and carbonates and biogeochemical processes related to the accumulation of OM in sediments. • The interaction between organic matter and carbonate during sedimentation is examined from the micro to macro scale • The assembly of OM and the formation of Ca–CO 3 ion pairs in an aqueous solution are transitory • The adsorption of organic matter is increased by surface defects in the calcite [ABSTRACT FROM AUTHOR]

Microalgae are one of the important sources of organic matter which, if preserved well in sediments, can generate hydrocarbons during burial diagenesis. However, the preservation mode of microalgal organic matter within product aggregates induced by marine microalgae has rarely been examined. Herein, a strain of eukaryotic marine microalgae, Chlorella sp. MASCC-0008, was used to conduct biomineralization experiments in an f/2 medium with a 0.02 mol/L Ca2+ ion concentration and various Mg2+ ion concentrations of 0.05, 0.06, 0.07 and 0.10 mol/L. It was found that the soluble organic matter of the microalgae contains amino acids and fulvic acids which can attract and absorb cations. With an increase in Mg2+ ion concentration in the experimental group with Chlorella sp., the aragonite content of the mineral precipitates increased whereas the calcite content decreased. In contrast, calcite was the sole mineral precipitated in the control experiments with no Chlorella sp.. Due to the porous structure of minerals, their organic matters were preferred to be preserved in aragonite aggregates compared to calcite aggregates. The TOC content of the minerals aggregates is the highest (0.45%) and the hydrocarbon generation potential (S 1 + S 2) of organic matter is the greatest (3.66 mg/g) in those precipitated in the medium with a Mg2+ ion concentration of 0.10 mol/L. Microalgal organic matter has significant hydrocarbon generation potential due to its effective preservation in the product aggregates formed by the microalgal biomineralization. Squalene is the most abundant alkene detected in the pyrolytic products. These results suggest that microalgae can induce precipitation of carbonate minerals, a process that facilitates the sequestration of organic matter within the product aggregates precipitated, thus potentially preserving this microalgal organic matter into the burial diagenetic realm where, if conditions are appropriate, hydrocarbons may be developed. [ABSTRACT FROM AUTHOR]

In this study, we conducted sandstone petrography analyses and determined detrital zircon U–Pb ages and Hf isotopes for sandstones collected at different stratigraphic levels of the lowest strata of the Laiyang Group. All results nearly point to an evolutionary trend for the source regions of the strata. The detrital zircon U–Pb results reveal multiple age groups at 140–123 Ma, 810–700 Ma, and 2,500–1,750 Ma, but variable age proportions for two sandstones (19LY‐01Z and ‐05Z) collected at lowermost and middle levels of strata, respectively, but only one unimodal age mode at ca. 1,850 Ma for the uppermost sandstone 19LY‐09Z. Provenance analysis illustrates that the lower strata likely include two source regions, including the Jiaobei Terrane and the Sulu orogen, whereas the upper strata appeared to have one dominant source region (i.e., Jiaobei Terrane). Framework modes of sandstones display that lower samples contain more metamorphic lithic fragments, which corresponds to the recycled orogenic field in the Q‐F‐L diagram, while middle‐upper samples are enriched in feldspars but deficient in lithics and plot in the basement uplift field of the Q‐F‐L diagram. This compositional variation reflects an evolution of the source regions from the Sulu Orogen to the Jiaobei Terrane, completely consistent with the observation of an increase in the amount of detrital zircons sourced from the Jiaobei Terrane, but decreasing detrital zircons from the Sulu Orogen in an upward order. This shift in the provenance of sediments reflects two tectonic events including exhumation of the Sulu Orogen to the surface before sedimentation of the Laiyang Group, and a rapid uplift of the Jiaobei Terrane after ca. 125 Ma following removal of lithospheric mantle. [ABSTRACT FROM AUTHOR]

The petrography, major, and trace elements concentration of the sandstones from the Zhanjin Formation in Qiwu area, south Qiangtang Basin, have been studied to determine their provenance, intensity of paleo-weathering and depositional tectonic setting. Petrography indicates that the composition and texture maturity of the sandstones are moderate. The detrital composition of Zhanjin Formation samples are dominated by quartz (70.1–80.3, average 74.1%) and feldspar (18.3–26.5, average 21.9%), but is low in lithic fragment (1.4–8.6, average 3.9%). The sandstone can be classified as arkose and litharenite arkose. The detrital model composition reflects that these sandstones are probably derived from a passive continental margin. The index of chemical variability (ICV), and Th/Sc vs. Zr/Sc discrimination diagram suggests that the compositional maturity and recycling were moderate to low. The index of alteration (CIA) and the A–CN–K diagram indicated that the intensity of weathering in the source area was low. The Al2O3/TiO2 vs. SiO2, Th/Sc, Co/Th, La/Sc, Cr/Th ratio values of the Zhanjin sandstones indicated that the sandstones were mainly derived from felsic source rocks. The Gondwana passive continental margin belt is probably the primary provenance area as evidenced by petrography and geochemistry features of the Zhanjin Formation. All kinds of tectonic discrimination diagrams based on major elements showed a rift setting for Zhanjin sandstones, which is consistent with the general views of study areas. [ABSTRACT FROM AUTHOR]

The interaction between bacteria and minerals is very complicated and has been intensively studied in the laboratory and the field in the last few decades, but the processes and mechanisms of biomineralization and mineral precipitation are still not fully understood and need to be explored further. In the present work, biomineralization experiments were undertaken using Klebsiella pneumoniae LH1, collected from a natural surface environment in an area of outcrops of Cambrian dolomite, in a culture medium with various Mg/Ca molar ratios (0, 3, 6 and 12). The mineral precipitates obtained were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FTIR), laser scanning confocal microscopy (LSCM) and X-ray photoelectron spectroscopy (XPS). Cells were analyzed with a scanning transmission electron microscope (STEM), high resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED). The composition of amino acids in extracellular polymeric substances (EPS) was also determined. In the experiments it was found that the production of ammonia and the presence of carbonate anhydrase promoted the increase of the medium pH and that minerals are nucleated on the EPS, which consist chiefly of amino acids and negatively-charged organic functional groups. With increasing Mg/Ca ratios, the mineral phases changed, including calcite (100%) at Mg/Ca molar ratio of 0, monohydrocalcite (36.05%) + dypingite (63.95%) at Mg/Ca molar ratio of 3, monohydrocalcite (29.72%) + dypingite (15.48%) + nesquehonite (54.80%) at Mg/Ca molar ratio of 6, and monohydrocalcite (14.2%) + dypingite (1.0%) + nesquehonite (84.80%) at Mg/Ca molar ratio of 12. Some intracellular amorphous calcium- and magnesium-rich inclusions were also detected in K. pneumoniae LH1, suggesting intracellular biomineralization accompanying the extracellular mineral precipitation. This study provides further understanding of the biomineralization processes of microorganisms. [ABSTRACT FROM AUTHOR]

Although micrites (abiotic limestone) and thrombolites (typical biotic limestone), according to the sedimentation and biological action, can be primarily distinguished from intuitively field observation and rock slices analysis. However, further analysis of thermal decomposition unique characteristics to distinguish them has rarely been reported. Here, the comparative studies of thermal decomposition behavior between micrites and thrombolites were carefully investigated using thermogravimetric analyzer in nitrogen atmosphere at multi-heating rates of 5, 10, 20 and 30 K min−1 from 323.15 to 1273.15 K. Moreover, the mineralogical compositions were both analyzed by powder X-ray diffraction followed by the results of calcite acting as the basic constituent for further verified. The kinetic model function and kinetic parameters were calculated by Flynn–Wall–Ozawa, Kissinger–Akahira–Sunose and Popescu methods, respectively. The results showed that the kinetic parameter activation energy (E) of thrombolites was obviously higher than that of micrites, which suggests the former have a higher crystallinity. In addition, the results of difference significance analysis showed extremely significant differences (P < 0.01) via statistical analysis using SPSS v19.0 for the E values between micrites and thrombolites calculated by different methods. These above results further confirmed that the thermal stability and crystallinity of thrombolites were obviously higher under the inducing effects by typical microorganisms. This provided very important useful information for understanding the mechanisms of abiotic and biotic limestones formed in nature; in particular, the thermal analysis of thrombolites maybe also provides an important guiding significance for both indoor and outdoor similar studies. [ABSTRACT FROM AUTHOR]

To better understand the geodynamic evolution of northeastern China during the Late Mesozoic, we analyzed zircon U–Pb geochronological, Lu–Hf isotopic, and geochemical data for Early Cretaceous volcanic rocks from the southeastern margin of the Songliao Basin. Newly identified A-type rhyolite and trachyandesite yielded zircon 206Pb/238U ages of ca. 123 Ma and 117 Ma, respectively. The rhyolites are high in SiO2 (72.24–78.89 wt%) and total alkali (K2O + Na2O = 8.81–10.03 wt%), and low in MgO (0.10–0.26 wt%), CaO (0.32–0.36 wt%), Ni (0.08–2.69 ppm), and Cr (0.39–4.87 ppm) concentrations, with negative Nb, Ta, and Sr anomalies. They are enriched in light rare earth elements (LREEs) and large-ion lithophile elements (LILEs) and depleted in high-field-strength elements (HFSEs); the calculated Zr saturation temperatures are high (828–915 °C). The A-type rhyolites possess variable zircon εHf(t) values ranging from + 5.69 to + 10.49. Petrogenetic analysis leads us to propose that the A-type rhyolites were probably formed by partial melting of a Neoproterozoic–Early Paleozoic juvenile lower crust. The trachyandesites have Nb/Ta (14.9–17.25), Zr/Hf (35.04–42.75), Rb/Sr (0.25–0.40), and Lu/Yb (0.14–0.15) ratios that are similar to those of mantle-derived magma, indicating a mantle source. They have εHf(t) values of + 4.71 to + 7.29 and show enrichment in LILEs and LREEs, and weak depletion in HFSEs, suggesting that the parent magma originated from partial melting of a depleted lithospheric mantle, and was subsequently metasomatized by subduction-related fluids, followed by extensive fractional crystallization during the magma evolution. Combined with the temporal and spatial distribution of Late Mesozoic igneous rocks from the southeastern margin of the Songliao Basin, we propose that Early Cretaceous volcanic rocks formed in an extensional tectonic setting that was closely related to rollback of the Paleo-Pacific (Izanagi) oceanic slab. [ABSTRACT FROM AUTHOR]

We report zircon U-Pb geochronologic and geochemical data for the post-collisional volcanic rocks from the Batamayineishan (BS) Formation in the Shuangjingzi area, northwestern China. The zircon U-Pb ages of seven volcanic samples from the BS Formation show that the magmatic activity in the study area occurred during 342-304Ma in the Carboniferous. The ages also indicate that the Palaeo-KaramailiOcean had already closed by 342Ma. Moreover, the volcanic rocks also contained 10 inherited zirconswith ages ranging from 565 to 2626 Ma, indicating that Precambrian continental crust or microcontinents with accretionary arcs are two possible interpretations for the basement underlying the East Junggar terrane. The sampled mafic-intermediate rocks belong to the medium-K to high-K calc-alkaline and shoshonitic series, and the formation of these rocks involved fractional crystallization with little crustal contamination. These Carboniferous mafic-intermediate rocks show depletions in Nb and Ta and enrichments in large ion lithophile elements (e.g. Rb, Ba, U, and Th) and light rare earth elements. The low initial 87Sr/86Sr values (0.7034-0.7042) and positive εNd(t) values (+2.63 to +6.46) of these rocks suggest that they formed from depleted mantle material. The mafic-intermediate rocks were most likely generated by 5-10% partial melting of a mantle source composed primarily of spinel lherzolite withminor garnet lherzolite that had been metasomatized by slab-derived fluids and minor slab melts. In contrast, the felsic rocks in the BS Formation are A-type rhyolites with positive εNd(t) values and young model ages. These rocks are interpreted to be derived from the partial melting of juvenile basaltic lower crustal material. Taken together, the mafic-intermediate rocks formed in a post-collisional extensional setting generated by slap breakoff in the early Carboniferous (342-330 Ma) and the A-type rhyolites formed in a post-collisional extensional setting triggered by the upwelling asthenosphere in the late Carboniferous (330-304 Ma). [ABSTRACT FROM AUTHOR]

The formation of carbonates is not yet a well-understood process that is biogenic or abiotic origin remains controversial. To obtain further insights on the controls of Mg incorporation in carbonates formed via biogenic process, the impacts of cyanobacteria Synechocystis sp. PCC6803 on carbonates precipitation have been investigated in BG11 medium at different Mg/Ca molar ratios in the laboratory. Initial concentration of Ca was 0.01 M and Mg/Ca molar ratio was 0, 2, 4, and 6, respectively. The results showed that pH values in the experimental group increased rapidly, greater than those in the control group. Ca concentration decreased greatly while Mg concentration was almost unchanged in these two groups. There were significant differences in the sizes, shapes, elemental compositions, and surface morphologies of the mineral precipitates between control group and experimental group analyzed by polarizing microscopy, scanning electron microscopy and energy dispersive X-ray detector. X-ray diffraction result showed that calcite was induced at Mg/Ca molar ratio of 0 and aragonite was induced at Mg/Ca molar ratio of 4 and 6. X-ray diffraction and selected-area electron diffraction results showed the minerals at Mg/Ca molar ratio of 2 were calcite and aragonite. The cracks on the surface of aragonite crystals may be a characteristic of biogenetic aragonite. Thermogravimetric analysis of the carbonate minerals showed that the thermal stability decreased gradually with increasing Mg/Ca molar ratios. These results are useful for further understanding of the formation mechanism of biogenic carbonates in natural condition. [ABSTRACT FROM AUTHOR]

The article focuses on the study using Detrital Zircon Geochronology conducted on sandstones from Kaishantun (KST) Formation and Kedao (KD) Group in Yanbian Area, to ascertain the final closure of the Paleo-Asian Ocean (PAO) in the eastern segment of Central Asian Orogenic Belt (CAOB) in North East China. Tables and Diagrams are presented to support the study.

The biomineralization of struvites is becoming a very popular research subject. In this study, struvite crystals were precipitated and characterized in the presence of the bacterialLeclercia adcarboxglatastrain JLS1 that was isolated from a typical dolostone sample. The JLS1 strain was identified asL. adcarboxglatausing physiological and biochemical identification methods and by 16S rDNA phylogenetic analysis. The minerals obtained from the culture medium using experimental samples inoculated withL. adcarboxglataJLS1 were not found in the control samples without the bacteria. The experimentally derived minerals were determined to be pure struvites that exhibited primarily a uniform, prismatic-shaped morphology of various sizes. The results of the X-Ray Powder Diffraction (XRD) analysis of the minerals revealed that the preferred orientation and lattice distortion were characteristic of struvite crystals. In the experiments conducted using theL. adcarboxglatait was also found that the phosphate, ammonium and magnesium ions in solution were consumed to form the struvites in an alkaline environment. The results of this study can provide important insights into the understanding of the biomineralization process of microbial struvites and wastewater treatment applications, as well as the genesis and therapy of kidney stones. [ABSTRACT FROM PUBLISHER]

In order to simulate the precipitation process of microbial limestone at the offshore of the ancient ocean, different calcites induced bySynechocystis sp. PCC6803 in culture media with low Mg/Ca ratios (0.01 M Ca2+, Mg/Ca = 0, 0.2, 0.4, 0.6) were investigated, and the characteristics of intracellular and extracellular biomineralization were described. Carbonic anhydrase activity ofSynechocystis sp. PCC6803 in different culture medium was further detected. The ultrathin slices ofSynechocystis sp. PCC6803 cells were analyzed by transmission electron microscope (TEM) and selected area electron diffraction (SAED). Then the precipitates were analyzed by polarizing microscope, scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometer (EDS). The results showed that the biomineralization precipitates ofSynechocystis sp. PCC6803 under low Mg/Ca ratios were mainly calcites with different morphologies. The CA accelerated the pivotal rate limiting step of the calcite precipitation. It was also found that the morphology, microstructure, particle size, preferred orientation, crystallinity and cell volume of calcites changed gradually with the increasing Mg2+concentrations. What is more important, it was found thatSynechocystis sp. PCC6803 had the ability of intracellular biomineralization without crystal structure. The intracellular biomineralization product could be divided into two types. This study can provide some useful information for further understanding the characteristics and mechanisms of biomineralization and even the diagenetic environment research of microbial limestone. [ABSTRACT FROM PUBLISHER]

Although various complicated methods have always been made attempts, it is still well difficult to efficiently distinguish between the biogenic and abiogenic minerals in geological area up to now. In present study, the thermal decomposition unique characteristics of microbial calcites (MC), induced by cyanobacteria Synechocystis sp. PCC6803, were compared with those of chemical calcites (CC) prepared by the reaction of sodium carbonate (NaCO) with calcium chloride (CaCl). Two samples were firstly analyzed by scanning electron microscope and X-ray diffraction, and were further investigated thermal decomposition behaviors using a thermogravimetric analyzer at different heating rates of 278.15, 283.15, 293.15, and 303.15 K min from 323.15 to 1273.15 K, respectively, then kinetic parameters were calculated via Popescu, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa methods, and then the kinetics mechanism functions were deduced by Popescu method. The results showed that these two kinds of precipitates were actually both calcite crystals although the surface morphologies were quite different. Whereas thermal decomposition kinetics mechanism function of MC can be described as Avrami-Erofeev equation ([−ln(1 − α)]), while CC corresponded to Contracting sphere (volume) ([1 − (1 − α)]), the results also showed that the average activation energy of MC and CC was 217.9 and 170.5 kJ mol, respectively; that is, MC has higher thermal stability, which should be originated from the inducing effects and the different precipitation conditions provided by Synechocystis sp. PCC6803. These above results provided useful information not only for efficiently distinguishing between the biogenic and abiogenic minerals in geological area, and also for better understanding the microbial mineralization. [ABSTRACT FROM AUTHOR]

We present zircon U–Pb dating, whole-rock geochemistry, and Sr–Nd isotope results for the Upper Permian–Upper Triassic volcanic rocks to constrain the timing of the final closure of the eastern segment of the Palaeo-Asian Ocean. The volcanic rocks were mainly collected from the Yanbian area in eastern Jilin Province, northeastern China. The zircon U–Pb dating results indicate that the samples can be classified as Upper Permian–Lower Triassic basalts (ca. 262–244 Ma) and Upper Triassic dacites (ca. 216 Ma). The whole-rock geochemical results indicate that the rocks predominately belong to the medium-K and high-K calc-alkaline series. The basalts are enriched in large ion lithophile elements (LILEs, e.g. Ba and K) and depleted in high field strength elements (HFSEs, e.g. Nb and Ta), with weak positive Eu anomalies. The dacites are enriched in LILEs (e.g. Rb, Ba, Th, and K) and light rare earth elements (LREEs) and marked depletion in some HFSEs (e.g. Nb, Ta, and Ti), with significant negative Sr, P, and Eu anomalies. Moreover, the Upper Permian–Lower Triassic basalts have low initial87Sr/86Sr ratios (0.7037–0.7048) and highεNdvalues (4.4–5.4). In contrast, the Upper Triassic dacites possess relatively high initial87Sr/86Sr ratios (0.7052) compared with their lowεNdvalues (1.4). The basaltic magma likely originated from the partial melting of a depleted mantle wedge metasomatized by subduction-related fluids, and the felsic magmas likely originated from the partial melting of a dominantly juvenile source with a minor component of ancient crust. Taken together, the Upper Permian–Lower Triassic basalts (ca. 262–244 Ma) are arc basalts that formed in an active continental margin setting, and the Upper Triassic dacites (ca. 216 Ma) are A-type granitic rocks that formed in an extensional setting. Therefore, the final closure of the Palaeo-Asian Ocean occurred during the Middle–Late Triassic. [ABSTRACT FROM PUBLISHER]

This study illustrates features of the Cambrian oncoids and provides a comparison with other microbial-related carbonate grains found in the Cambrian succession of the North China epeiric platform. Based on cortex structures, four types of oncoids were distinguished: thin-cortex (superficial) oncoids, laminated-cortex oncoids, clotted-cortex oncoids, and full-cortex (without nucleus) oncoids. Thin- and clotted-cortex oncoids are often associated with oolites, laminated-cortex oncoids are present within oolitic-bioclastic grainstones, and full-cortex oncoids occur in bioturbated wackestones. The oncoids with nucleus-cortex structures are easily distinguished from other carbonate grains due to the lack of nucleus-cortex structures, and from microbial-related ooids which have more circular shape and more continuous cortex than oncoids. Oncoids without nucleus and with only crudely laminated cortex (i.e., full-cortex oncoids) can be differentiated from microbialite intraclasts and microbial lumps by the following evidences: (1) microbialite intraclasts, either rounded or angular, are characterized by margins that sharply truncate the included calcified microbes or carbonate grains and, in addition, intraclast-bearing conglomerates commonly show clear sedimentary structures such as cross-stratification and normal grading; (2) microbial aggregates have irregular but smooth margins, and rather chaotic inner structures. [ABSTRACT FROM AUTHOR]

This article presents a study of struvite formation in liquid medium induced by the sulfate-reducing bacteriumAcinetobacter calcoaceticusSRB4, a strain isolated from river sediment. We identified the bacterial strainA. calcoaceticusSRB4 and analyzed its micromorphology. The minerals formed were studied with an electroprobe microanalyzer, Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy, selected-area electron diffraction, X-ray diffraction, thermogravimetry, differential thermogravimetry, and differential scanning calorimetry.Acinetobacter calcoaceticusSRB4 was found to induce struvite precipitation, whereas sterile control cultures did not. Many transparent stick-shaped struvite precipitates were distributed at the bottom of the conical flasks in the experimental group. Most bacteria were spherical and a large quantity of spherical struvite particles (less than 200 nm in diameter) adhered to the bacterial surface. An electron probe microanalysis showed that the precipitates contained C, O, P, Mg, and other elements. Fourier transformation infrared spectra showed that the precipitates contained crystalline water, NH4+, and PO43−groups. X-ray diffraction spectra showed that the precipitates were struvite crystals, with preferential orientation and lattice distortion. Thermogravimetry showed that the weight loss was caused by the evaporation of crystalline water at temperatures lower than 136°C and the release of ammonia from struvite at temperatures of 136–228.5°C. In this article, we discuss the possible mechanism of struvite formation and the possible role played byA. calcoaceticusSRB4. Our study extends our understanding of the phosphate biomineralization mechanism and should prove useful in recycling phosphorus in wastewater. [ABSTRACT FROM AUTHOR]

This article presents a research study on the deposition process of Ca2+induced bySynechocystissp. PCC6803 in BG11 liquid medium with different Ca2+concentrations and different pH. The changes of Ca2+concentrations were measured by using atomic absorption method and the corresponding dynamical models were studied. Minerals and cells were analyzed by high resolution transmission electron microscope, selected area electron diffraction, scanning electron microscope, energy dispersive X-ray spectroscope, X-ray diffraction. The selected area electron diffraction patterns were analyzed by Digital Micrograph 3.7 software. The result showed that Ca2+concentrations decreased faster in the experimental group. The changes of calcium carbonate precipitation were fitting to an exponential model. PH 7 and Ca2+concentration of 1.5 g/L were most conducive to calcium carbonate precipitation in the corresponding gradient range. The result of high-resolution transmission electron microscopy showed that minerals in the experimental group differed obviously from that of the control group in the surface morphology, but both of them were calcites. It also showed that a certain number of minute calcites adhesion to the outer surfaces ofS.PCC6803 cells. The result of scanning electron microscopy displayed that many sunken holes emerged on the surfaces of the prismatic calcium carbonate minerals. The results of X-ray diffraction proved that minerals induced byS.PCC6803 were calcites with preferential orientation. This article discusses the process of carbonate formation and the possible role played byS. PCC6803. It may be useful to further study the mechanism of microbial carbonates deposition in the field of geology. [ABSTRACT FROM PUBLISHER]

Calcium carbonate (CaCO) crystals in their preferred orientation were obtained in BG11 culture media inoculated with Synechocystis sp. PCC6803 (inoculated BG11). In this study, the features of calcium carbonate deposition were investigated. Inoculated BG11 in different calcium ion concentrations was used for the experimental group, while the BG11 culture medium was used for the control group. The surface morphologies of the calcium carbonate deposits in the experimental and control groups were determined by scanning and transmission electron microscopy. The deposits were analyzed by electronic probe micro-analysis, Fourier transform infrared spectrum, X-ray diffraction, thermal gravimetric analysis and differential scanning calorimetry. The results show that the surfaces of the crystals in the experimental group were hexahedral in a scaly pattern. The particle sizes were micrometer-sized and larger than those in the control group. The deposits of the control group contained calcium (Ca), carbon (C), oxygen (O), phosphorus (P), iron (Fe), copper (Cu), zinc (Zn), and other elements. The deposits in the experimental group contained Ca, C, and O only. The deposits of both groups contained calcite. The thermal decomposition temperature of the deposits in the control group was lower than those in the experimental group. It showed that the CaCO deposits of the experimental group had higher thermal stability than those of the control group. This may be due to the secondary metabolites produced by the algae cells, which affect the carbonate crystal structure and result in a close-packed structure. The algae cells that remained after thermal weight loss were heavier in higher calcium concentrations in BG11 culture media. There may be more calcium-containing crystals inside and outside of these cells. These results shall be beneficial for understanding the formation mechanism of carbonate minerals. [ABSTRACT FROM AUTHOR]

Cement content of carbonate in tight sandstone near section is much higher than that of the normal sandstones far away from the fault of well Xia503, in the Huimin sag in Linnan sub-depression. In order to understand the origin and its impact on fault sealing, analyses of the whole-rock minerals, casting thin sections, cathodoluminescence, isotope and physical properties are conducted on cores from well Xia503. It is found that δC varies from 0.1‰ to 0.6‰ with the average value of 0.42‰, δO varies from ∼13.5‰ to ∼12.3‰ with the average of ∼13.1‰, and C-O isotope plotting points are distributed in the low to moderate temperature area of the hydrothermal dolomite. According to the occupied relationship, cathodoluminescence, and C-O isotope feature, the carbonate cementation could be divided into four stages: calcites, dolomite, ankerite, and ferrocalcite. It is discovered that the carbonate cementation is negatively related to reservoir physical property, with the porosity of 4.8%, permeability of 0.37 mD, and displacement pressure of 1.97 MPa in the tight sandstone, which have increased by almost one order of magnitude compared to the porosity of 14.3%, permeability of 3.73 mD, and displacement pressure of 0.27 MPa in the normal sandstone, which is far away from the fault. Regardless of the lithology of the counterpart wall of the fault, only the displacement pressure difference caused by carbonate cementation between the tight sandstone and the normal sandstone could seal 41 m high oil column. [ABSTRACT FROM AUTHOR]

Calcite with laminate structure was successfully prepared by culturing Synechocystis sp. PCC6803 with different concentrations of calcium chloride (CaCl) in BG11 media. S. PCC6803 was examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser confocal scanning microscope (LCSM) and energy dispersive spectroscopy (EDS). The effects of Ca concentrations and pH values on calcification were investigated and the micro morphs of the CaCO crystals were observed by means of SEM. These results showed that CaCO crystals could be more easily formed with increasing the concentration of CaCl in S. PCC6803 culture solution. S. PCC6803 could largely bind calcium ions, most of which were present in extracellular polymeric substances and on the cell wall. Inside the cells there were a lot of circular areas rich in calcium ions without the crystallization of calcium. Some cells produced a thicker gelatinous sheath outside of the translucent organic thin layer. And the cells inside also produced major changes that the original chloroplasts were almost transformed into starch grains whose sizes were from 0.5 to 1 μm with relatively uniform in sizes. At the same time the cell sizes significantly reduced to only about 8-9 μm almost changing to half of its original diameters. The calcite crystals with a highly preferred orientation induced by S. PCC6803 were observed with X-ray diffraction (XRD). A critical implication was that S. PCC6803 could induce bio-calcification and then mediate the further growth of CaCO crystals in the biological system. [ABSTRACT FROM AUTHOR]

The Raohe accretionary complex (RHC) is located at the eastern of northeast China and adjacent to Russian Far East. As a part of the Circum-Pacific Orogenic Belt, it is the unique region of the accretionary orogenic belt, which is associated with the subduction process of the Panthalassic-Pacific Plate (PPP). We synthesize the detrital zircon ages of terrigenous clastic rocks of the RHC and tectonic units along the East Asian Continental Margin (EACM) to clarify its provenance. Then we place the docking position of the RHC adjacent to the South China Block, and determine that the final accretion of the RHC occur during the later Late Jurassic (~150 Ma) according to combination for ages of stitching plutons and terrigenous clastic rock. Integrating with the published global-scale plate kinematic frame, we restored the pre-docking motion path of the RHC using the Gplates software. The reconstructed scenario shows that it is a long distance of at least 1000 km between the proto-RHC and continent margin when the basaltic volcanism occurred subaqueously within the abyssal basin of the PPP. This model also provides a probability that the proto-RHC and the proto-Yuejingshan accretionary complexes have the same drift history, before their simultaneous emplacement into the continental margin. • The Raohe accretionary complex accreted onto the southeast margin of the South China Block at ~150 Ma. • The Middle Jurassic pillow basalts erupted subaqueously within the Izanagi plate. • The Nadanhada Terrane is one geologic unit as relicts of oceanic crust and its overlayers. [ABSTRACT FROM AUTHOR]

Numerous shallow-marine limestone layers of the Furongian (Late Cambrian) Chaomidian Formation in the Jiulongshan section (Shandong Province, China) are breccias. Some of these breccias show abundant vertical to sub-vertical clasts. Typically, these clasts end abruptly at the contact plane with the overlying deposit, either abutting the overlying sedimentary bed or via an erosional plane that truncates the clasts. A few exposures show concentrations of clasts that must have been uplifted to the extent that they transgressed the then sedimentary surface or (possibly) penetrated the overlying sediment which, in this case, consists of muds or marls. The clasts tend to show clusters with respect to the enclosing fabric. All clasts are parallel to each other in a specific cluster, while the various clusters may show different orientations of the clasts. It is deduced that both the exceptional position and the exceptional orientation of the clasts must be ascribed to the upward movement of the clasts under the influence of pore water escaping under high pressure through fluidized sediment. [ABSTRACT FROM AUTHOR]

The precise age of slab rollback of the Paleo-Pacific Plate during Early Cretaceous has been contentious. In this study, we have conducted LA-ICP-MS zircon U-Pb dating, major and trace elements, and Sr-Nd isotopes analyses on the late Early Cretaceous diabase porphyries, andesitic basalts and basanites in the Yanbian area (NE China). Zircon U-Pb dating of basanites, andesitic basalts, and diabase porphyries yielded weighted average ages of 104 ± 1.9 Ma (MSWD = 0.55, n = 5), 106 ± 1.6 Ma (MSWD = 0.68, n = 6), and 111 ± 2 Ma (MSWD = 16, n = 3), respectively. The whole-rock geochemical results indicate that the late Early Cretaceous rocks predominantly belong to the low-K tholeiitic and medium-K calc-alkaline series. The diabase porphyries and andesitic basalts are characterized by large ion lithophile elements (e.g. Ba, K, and Sr) enrichment and high field strength elements (e.g. Nb and Zr) depletion with weak positive Eu anomalies, low initial 87Sr/86Sr ratios (0.70361–0.70394) and high εNd (t) values (5.96–7.87). The tectonic discrimination diagrams show that the diabase porphyries and andesitic basalts formed in the continental Island arc environment related to subduction of the Paleo-Pacific Plate in the late Early Cretaceous. In contrast, the basanites are enriched in Ba, Th, and U and depleted in K, Sr, and Ti, with weak negative Eu anomalies. The basanites display high magnesium values (Mg# = 0.79), which are approaching the primary magma. They have low Ti values (TiO2 = 1.45%) and Al values (A12O3 = 9.98–10.15%) and high Co values (78.1–80.2 ppm) and Ni values (549.5–585.5 ppm). The basanites formed in the intraplate extensional tectonic setting and were the products of lithospheric thinning and mantle upwelling during the late Early Cretaceous. The spatial-temporal relationship of late Early Cretaceous magmatic rocks in NE China suggests a slab rollback from high-angle subduction to low-angle subduction of the Paleo-Pacific Plate at ca. 106 Ma. [ABSTRACT FROM AUTHOR]

Deep-seated cracked gas exploration was achieved great breakthrough in Es of the Minfeng area on the northern slope of the Dongying Sag. Carbon isotopic and molecular compositions studies revealed the characteristics of wet gas and a normal trend of carbon isotopic composition. Empirical cutoff points of δC and δC and light hydrocarbon compositions distinguished the cracking gas as sapropelic gas. Variations in i/ nC, i/ nC and δC further confirmed that the gas was cracked from residual kerogen. Source characteristics indicated that the gas was derived from mature-highly mature source rocks of Es with kerogen type II being dominant mixed with some oil-cracking gas. Burial history modeling indicated that there were two hydrocarbon charging periods in Es reservoirs. The first period refers to the Guantao-Minghuazhen stage dominated by oil charging, while the second period refers to the Minghuazhen stage and has been dominated by cracked gas charging till now. [ABSTRACT FROM AUTHOR]

undant aromatic fractions were detected in oils from the Linnan subsag, including aphthalenes, phenanthrenes, triaromatic steroids, biphenyl, fluorenes, dibenzothiophenes, dibenzofuranes, as well as some typical higher plant-sourced compounds, such as pyrene, benzopyrene, fluoranthene, chryaene, benzofluoranthrene, perylene and cadalene. Occurrences of biomarkers indicate that oils from the Linnan subsag are typical terrestrially genetic oils. Developed in the depositional environment is a strong reduction condition typical of brackish-saline lake. Thermal evolution has entered into the mature-high mature stage. [ABSTRACT FROM AUTHOR]

Treating eutrophic water by struvite biomineralization has been studied for many years due to its much lower costs than physicochemical methods. In this study, an eco-friendly method applying biological processes to precipitate phosphate, magnesium and ammonium ions as struvite using free and immobilized Bacillus cereus MRR2 bacteria was studied. The results showed that the higher alkalinity and supersaturation derived from alkaline phosphatase and ammonia released by the bacteria facilitated struvite nucleation. The biogenesis of coffin-like and tetragonal-pyramid-shaped struvite was proved by the presence of diversified organic functional groups and secondary protein structures, as well as different C 1S and S 2p peaks through XRD, Rietveld refinement, SEM-EDS, FTIR and XPS analyses. STEM and element mapping results showed that the ammonium, phosphate and magnesium ions had diffused from the outside to the inside of the cell. The optimal immobilization conditions of Bacillus cereus MRR2 were obtained by a response surface methodology (12.3% bacteria amount, 8.3% activated carbon, 0.3% polyvinyl alcohol, 2% sodium alginate, 4% calcium chloride, 3% boric acid solution and 24 h cross-linking time). The removal ratio of phosphate, magnesium and ammonium ions by immobilized bacteria in 15 days reached 90.1%, 95.6% and 95.7%, respectively, much higher than the 73.3%, 83.8% and 89.1% values using free bacteria. The application of immobilized Bacillus cereus MRR2 will provide a simple eco-friendly and economic method for simultaneous removal of phosphate, magnesium and ammonium ions and also for continuous struvite recovery, which can supply a reference for the treatment of eutrophic water. [Display omitted] • Alkaline phosphatase and ammonia together resulted in pH increase up to 9.0. • Struvite could be recycled in eutrophic water treatment by Bacillus cereus. • The optimal immobilization condition of Bacillus cereus strain was further studied. • Phosphate and ammonium decreased by 90.1% and 95.7% by immobilized bacteria. • Treating eutrophic water by immobilized bacteria can obtain higher economic profit. [ABSTRACT FROM AUTHOR]

The effect of barium ions on the biomineralization of calcium and magnesium ions is often overlooked when utilizing microbial-induced carbonate precipitation technology for removing barium, calcium, and magnesium ions from oilfield wastewater. In this study, Bacillus licheniformis was used to bio-precipitate calcium, magnesium, and barium ions. The effects of barium ions on the physiological and biochemical characteristics of bacteria, as well as the components of extracellular polymers and mineral characteristics, were also studied in systems containing coexisting barium, calcium, and magnesium ions. The results show that the increasing concentrations of barium ions decreased pH, carbonic anhydrase activity, and concentrations of bicarbonate and carbonate ions, while it increased the contents of humic acids, proteins, polysaccharides, and DNA in extracellular polymers in the systems containing all three types of ions. With increasing concentrations of barium ions, the content of magnesium within magnesium-rich calcite and the size of minerals precipitated decreased, while the full width at half maximum of magnesium-rich calcite, the content of O-C=O and N–C=O, and the diversity of protein secondary structures in the minerals increased in systems containing all three coexisting ions. Barium ions does inhibit the precipitation of calcium and magnesium ions, but the immobilized bacteria can mitigate the inhibitory effect. The precipitation ratios of calcium, magnesium, and barium ions reached 81–94%, 68–82%, and 90–97%. This research provides insights into the formation of barium-enriched carbonate minerals and offers improvements for treating oilfield wastewater. [ABSTRACT FROM AUTHOR]

This paper presents a new detailed study including zircon U-Pb-Hf isotopic, whole-rock geochemical and Sr-Nd isotopic analyses of conglomerate and granitic pebbles from the molasse deposits in central Jilin Province, NE China. These data are used to better constrain the Late Permian–Triassic tectonic evolution regarding particularly the final closure of the Paleo-Asian Ocean (PAO) along the Changhun-Yanji suture (CYS). Zircon U-Pb data indicate that the granitic pebbles formed in the end-Permian (254–253 Ma). The youngest detrital zircon age of 231 Ma from the conglomerate, and presence of the overlying Upper Triassic Sihetun Formation suggests that the molasse deposits on the Jin′gui Island formed during the Late Triassic. The end-Permian granitic rocks display high SiO2 (66.07–74.77 wt %), with low MgO (0.55–2.05 wt %) and Mg# (31.61–43.64) values, together with depleted Hf and Nd isotopic values (εHf(t) = +1.61 to +11.62; εNd(t) = +3.3 to +4.2; (87Sr/86Sr)i = 0.706458–0.706842) and juvenile second-stage Hf model ages (1148–512 Ma), suggesting that they were probably generated by the partial melting of a Meso-Neoproterozoic juvenile metabasaltic lower crust. They are characterized by enrichments in large ion lithophile elements (LILEs) and depletions in high field strength elements (HFSEs), with affinities to igneous rocks forming in a subduction-related setting. This, combined with regional coeval subduction-related magmatic rocks, indicates that the PAO still existed along the CYS. In addition, the identification of Late Triassic molasse deposits on the Jin′gui Island in this study, coupled with occurrences of many Early Triassic syn-collisional granitoids along the CYS, indicates that the final closure of the PAO took place prior to the Late Triassic. [ABSTRACT FROM AUTHOR]

The Late Paleozoic–Early Mesozoic tectonic evolution of the Changchun-Yanji suture (CYS) was mainly associated with the Paleo-Asian and Mudanjiang tectonic regimes. However, the spatial and temporal overprinting and variations of these two regimes remains are still dispute. In order to evaluate this issue, in this contribution, we present new zircon U-Pb ages and a whole-rock geochemical and zircon Hf isotopic dataset on a suite of metamorphic rocks, including gneisses, actinolite schist, leptynites, and biotite schists, from tectonic mélanges in northern Liaoning and central Jilin provinces, NE China. Based on zircon LA-ICP-MS U-Pb dating results, protoliths show wide ranges of aging spectrum, including Paleoproterozoic (2441 Ma), Early Permian (281 Ma), Late Permian (254 Ma), and Late Triassic (230 Ma). The Permian protoliths of leptynites from the Hulan Tectonic Mélange (HLTM) and gneisses from the Kaiyuan Tectonic Mélange (KYTM) exhibit arc-related geochemical signatures, implying that the Paleo-Asian Ocean (PAO) did not close prior to the Late Permian. The Late Triassic protoliths of gneisses from the KYTM, in combination with previously reported coeval igneous rocks along the CYS, comprises a typical bimodal igneous suite in an E–W-trending belt, suggesting a post-orogenic extensional environment. Consequently, we infer that the final closure of the PAO took place during the Early–Middle Triassic. The Early Permian protoliths of biotite schists from the HLTM are alkali basaltic rocks and contain multiple older inherited zircons, which, in conjunction with the geochemical features of the rocks, indicate that they were generated in a continental rift related to the initial opening of the Mudanjiang Ocean (MO). Data from this contribution and previous studies lead us to conclude that the MO probably opened during the Middle Triassic, due to the north–south trending compression caused by the final closure of the PAO. [ABSTRACT FROM AUTHOR]

Biological processes have been widely employed in the treatment of industrial and municipal wastewater due to costs being lower than using physicochemical methods. The present investigation reports a simple and environmentally friendly method applying biological processes to precipitate calcium (Ca) and magnesium (Mg) ions as carbonates and phosphate using free and immobilized Lysinibacillus fusiformis DB1-3 bacteria isolated from a petroleum sample. The results show that the concentrations of Ca2+ and Mg2+ ions at different Mg/Ca molar ratios decreased by 93.58–91.46% and 62.55–58.29% when using free bacteria, and 95.56–94.86% and 58.22–70.25% when using immobilized bacteria. It took the free bacteria 30 days and the immobilized bacteria 6 days to remove Ca2+ and Mg2+ ions to such a degree. The Ca2+ and Mg2+ ions are biomineralized into calcite, Mg-rich calcite, aragonite and struvite by the bacteria. No minerals were detected in a control group without any bacteria. FESEM-EDS, FTIR, TG-DTG, DSC and stable carbon isotope analyses were performed to further prove the biogenesis of these minerals. Carbonic anhydrase (CA) and alkaline phosphatase (ALP) play important roles in the formation of these biominerals. The nanoparticles forming on the extracellular polymeric substances (EPS) and intracellular Ca and Mg inclusions were analyzed by HRTEM, SAED, STEM and elemental mapping. The fluorescence intensity illustrates that Ca2+ ions can enter the cell by diffusion but the presence of Mg2+ ions inhibits this process. This is one of the few studies in which Ca2+ and Mg2+ ions have been bio-precipitated by free and immobilized L. fusiformis bacteria in the treatment of wastewater polluted by these ions. • The immobilized DB1-3 bacteria had stronger ability to precipitate Ca2+ and Mg2+. • 95.56% of Ca2+ and 70.25% of Mg2+ was mineralized to CaCO 3 and struvite by DB1-3. • CA, NH 3 , and ALP released by DB1-3 bacteria could increase pH to 9.2 in the fluid. • EPS of DB1-3 bacteria were the nucleation sites for the biotic minerals. • DB1-3 may be useful in the treatment of wastewater polluted by Ca2+ and Mg2+. [ABSTRACT FROM AUTHOR]

The late Ediacaran period encompasses widespread glacial deposits and early animal radiation. The temporal and spatial context of these events is not well established. The possible links between the glacial deposits and late Ediacaran fossils are critical for understanding the co-evolution of early animals and marine environments. This study presents a detailed geochemical reconstruction from the Tuerkeng Formation on the western margin and the Dongpo Formation on the southern margin along the North China Craton (NCC). The two fossiliferous late Ediacaran formations cover a critical interval between the end of the Zhengmuguan-Luoquan glaciation and the occurrence of late Ediacaran tubular fossils (e.g., Shaanxilithes). The two formations' similar and intermediate CIA values indicate moderate weathering under a warm and humid climate. Stratigraphic covariation of water-insoluble elements in samples from Tuerkeng and Dongpo formations suggest a rapid input of terrestrial materials at the beginning of deglaciation, and these terrestrial materials continued to be input into the shallow marine environment along the western and southern margins of NCC during the deposition of the two formations. Accompanied by the continental weathering and erosion of fresh rocks during the postglacial period of late Ediacaran, abundant nutrients as well as the terrigenous materials would be continuously transported into the continental margin seawater, which may ultimately lead to the rise of the Ediacaran biota. Our results provide new insights into paleoenvironment conditions along the continental margin of NCC and highlight the critical role of the postglacial terrigenous input in the evolution of early animals. • The two studied formations' CIA values indicate moderate weathering under a warm and humid climate. • Our data show an increasing terrigenous input into the NCC's continental margin seawater during the late Ediacaran. • Our results highlight the critical role of the postglacial terrigenous input in the evolution of early animals. [ABSTRACT FROM AUTHOR]

Microbially induced manganese carbonate precipitation has been utilized for the treatment of wastewater containing manganese. In this study, Virgibacillus dokdonensis was used to remove manganese ions from an environment containing 5% NaCl. The results showed a significant decrease in carbonic anhydrase activity and concentrations of carbonate and bicarbonate ions with increasing manganese ion concentrations. However, the levels of humic acid analogues, polysaccharides, proteins, and DNA in EPS were significantly elevated compared to those in a manganese-free environment. The rhodochrosite exhibited a preferred growth orientation, abundant morphological features, organic elements including nitrogen, phosphorus, and sulfur, diverse protein secondary structures, as well as stable carbon isotopes displaying a stronger negative bias. The presence of manganese ions was found to enhance the levels of chemical bonds O–C=O and N–C=O in rhodochrosite. Additionally, manganese in rhodochrosite exhibited both + 2 and + 3 valence states. Rhodochrosite forms not only on the cell surface but also intracellularly. After being treated with free bacteria for 20 days, the removal efficiency of manganese ions ranged from 88.4 to 93.2%, and reached a remarkable 100% on the 10th day when using bacteria immobilized on activated carbon fiber that had been pre-cultured for three days. The removal efficiency of manganese ions was significantly enhanced under the action of pre-cultured immobilized bacteria compared to non-pre-cultured immobilized bacteria. This study contributes to a comprehensive understanding of the mineralization mechanism of rhodochrosite, thereby providing an economically and environmentally sustainable biological approach for treating wastewater containing manganese. [ABSTRACT FROM AUTHOR]

Even though biomineralization induced by bacteria has been studied for many years, some unsolved problems are still present in the biomineralization, especially the intracellular biomineralization, which should be further explored. In this study, the Bacillus subtilis Daniel-1 strain was identified by 16S rDNA homology, used to induce calcium carbonate biomineralization at various Mg/Ca molar ratios (0, 2, 4, 6, and 8). The results showed that pH still increased at the decline stage in the bacterial growth process, and could increase to about 8.69, resulting from the influence of carbonic anhydrase activity and ammonia. X-ray diffraction (XRD) results showed that calcite, Mg-rich calcite, and aragonite minerals were induced in the extracellular biomineralization process. The diversified morphologies and the presence of fatty acids, protein, and other organic substances in calcium carbonate analyzed by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) proved the biogenesis of these minerals. The stable carbon isotope values (–19.37‰ to −19.79‰) and oxygen isotope values (–6.37‰ to −8.91‰) presented in this study were relatively negative, also confirmed the biogenesis of the minerals. Magnesium carbonate contents in Mg-rich calcite increased from 8.79% to 25.71% with increasing Mg/Ca ratios. Aragonite could be grown not only in cell surface but also inside the cell by analyzing ultrathin slices of bacteria with HRTEM-EDS-SAED. Aragonite in cell surface was elongated whereas intracellular aragonite was granular. To the best of our knowledge, the intracellular biotic crystalline aragonite has rarely been reported. This study is helpful to further understand the mechanism of carbonate mineral biomineralization, and may also provide useful evidence for further studies on intracellular crystal structures. [ABSTRACT FROM AUTHOR]

The South China Block is one of the largest continental blocks located on the East Asian continent. The early Palaeozoic Wuyi–Yunkai orogen of the South China Block (known as the Caledonian orogen in Europe) is a major orogenic belt in East Asia and represents the first episode of extensive crustal reworking since Neoproterozoic time. Although this orogen is key to deciphering the formation and evolution of the South China Block, details about the orogen remain poorly defined. The Songshutang and Wushitou ultramafic–mafic units in southern Jiangxi Province, South China, have 206Pb–238U ages of c. 437 Ma, suggesting a Silurian formation age. All the Songshutang and Wushitou ultramafic–mafic rocks show relatively flat chondrite-normalized rare earth element patterns, depletions in Nb, Ta, Zr, Hf and Ti, and low ϵNd(t) values from −9.12 to −5.49 with negative zircon ϵHf(t) values from −10.84 to −2.58, resembling a typical arc magma affinity. Geochemical and isotopic data indicate that the newly identified ultramafic–mafic rocks, along with the reported Silurian mafic rocks in South China, possibly originated from the similar partial melting of an ancient subducted slab, fluid/sediment and metasomatized lithospheric mantle with varying degrees of fractional crystallization. In conjunction with other records of magmatism and metamorphism in South China, a late-orogenic extensional event led to the melting of the sub-continental lithospheric mantle in Silurian time and generated ultramafic–mafic rocks with a limited distribution along the Wuyi–Yunkai orogen and widespread late-orogenic granitic plutons in the South China Block. [ABSTRACT FROM AUTHOR]

Biomineralization induced by microorganisms has become a hot spot in the field of carbonate sedimentology; however, the mechanisms involved still need to be explored. In this study, the bacterium Bacillus subtilis J2 (GenBank MG575432) was used to induce the precipitation of calcium carbonate minerals at Mg/Ca molar ratios of 0, 3, 6, 9, and 12. Bacillus subtilis J2 bacteria released ammonia to increase pH, but the ammonia released only made the pH increase to 8.25. Carbonic anhydrase was also produced to catalyze the hydration of carbon dioxide, and this process released carbonate and bicarbonate ions that not only increased pH but also elevated carbonate supersaturation. The biominerals formed at a Mg/Ca molar ratio of 0 were spherulitic, elongated, dumbbell-shaped, and irregularly rhombohedral calcite; at a Mg/Ca molar ratio of 3, the biominerals were calcite and aragonite, the weight ratio of calcite decreased from 26.7% to 15.6%, and that of aragonite increased from 73.3% to 84.4% with increasing incubation time. At higher Mg/Ca molar ratios, the biominerals were aragonite, and the crystallinity and thermal stability of aragonite decreased with increasing Mg/Ca molar ratios. FTIR results showed that many organic functional groups were present on/within the biominerals, such as C–O–C, N–H, C=O, O–H, and C–H. HRTEM-SAED examination of the ultra-thin slices of B. subtilis J2 bacteria showed that nano-sized minerals with poor crystal structure had grown or been adsorbed on the EPS coating. The EPS of the B. subtilis J2 strain contained abundant glutamic acid and aspartic acid, which could be deprotonated in an alkaline condition to adsorb Ca2+ and Mg2+ ions; this made EPS act as the nucleation sites. This study may provide some references for further understanding of the mechanism of biomineralization induced by microorganisms. [ABSTRACT FROM AUTHOR]

Carbonate precipitation induced by microorganisms has become a hot topic in the field of carbonate sedimentology, although the effects of magnesium on biomineral formation have rarely been studied. In experiments described here, magnesium sulfate and magnesium chloride were used to investigate the significant role played by Mg2+ on carbonate precipitation. In this study, Staphylococcus epidermidis Y2 was isolated and identified by 16S ribosomal DNA (rDNA) homology comparison and ammonia, pH, carbonic anhydrase, carbonate, and bicarbonate ions were monitored during laboratory experiments. The mineral phase, morphology, and elemental composition of precipitates were analyzed by XRD and SEM-EDS. Ultrathin slices of bacteria were analyzed by HRTEM-SAED and STEM. The results show that this bacterium releases ammonia and carbonic anhydrase to increase pH, and raise supersaturation via the large number of carbonate and bicarbonate ions that are released through carbon dioxide hydration catalyzed by carbonic anhydrase. The crystal cell density of monohydrocalcite is lower in a magnesium chloride medium, compared to one of magnesium sulfate. Crystals grow in the mode of a spiral staircase in a magnesium sulfate medium, but in a concentric circular pattern in a magnesium chloride medium. There was no obvious intracellular biomineralization taking place. The results presented here contribute to our understanding of the mechanisms of biomineralization, and to the role of Mg2+ in crystal form. [ABSTRACT FROM AUTHOR]

Biomineralization has become a research hotspot and attracted widespread attention in the field of carbonate sedimentology. In this study, precipitation of carbonate minerals was induced by Bacillus licheniformis DB1-9 bacteria, (identity confirmed with its phylogenetic tree), to further explore the biomineralization mechanisms. During experiments, lasting up to 24 days with varying Mg/Ca molar ratios and regular monitoring of conditions, ammonia and carbonic anhydrase are released by the bacteria, resulting in a pH increase. Carbonic anhydrase could have promoted carbon dioxide hydration to produce bicarbonate and carbonate ions, and so promoted supersaturation to facilitate the precipitation of carbonate minerals. These include rhombohedral, dumbbell-shaped, and elongated calcite crystals; aragonite appears in the form of mineral aggregates. In addition, spheroidal and fusiform minerals are precipitated. FTIR results show there are organic functional groups, such as C–O–C and C=O, as well as the characteristic peaks of calcite and aragonite; these indicate that there is a close relationship between the bacteria and the minerals. Ultrathin slices of the bacteria analyzed by HRTEM, SAED, EDS, and STEM show that precipitate within the extracellular polymeric substances (EPS) has a poor crystal structure, and intracellular granular areas have no crystal structure. Fluorescence intensity and STEM results show that calcium ions can be transported from the outside to the inside of the cells. This study provides further insights to our understanding of biomineralization mechanisms induced by microorganisms. [ABSTRACT FROM AUTHOR]

The discovery of cyanobacteria fossils in microbialite prompts the investigation of carbonate biomineralization using cyanobacteria. However, the impact of coexisting magnesium and iron in microbialite on carbonate biomineralization has been overlooked. Here, Synechocystis sp. PCC 6803 was used to induce calcium carbonate in the presence of coexisting magnesium and ferric ions. The findings demonstrate that cell concentration, pH, carbonic anhydrase activity, and carbonate and bicarbonate concentrations decreased with increasing concentrations of magnesium and calcium ions. Ferric ions yielded a contrasting effect. The levels of deoxyribonucleic acid, protein, polysaccharides, and humic substances in extracellular polymeric substances increased in the presence of separated or coexisting calcium, magnesium, and ferric ions. Magnesium ions inhibited calcium ion precipitation, whereas ferric ions exhibited the opposite effect. Protein secondary structures became more abundant and O-C=O and N-C=O contents increased with increasing ion concentrations by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses. Scanning electron microscopy revealed that ferric ions lead to rougher surfaces and incomplete rhombohedral structures of calcite, whereas magnesium ions promoted greater diversity in morphology. Magnesium ions enhanced the incorporation of ferric ions. This work aims to further understand the effect of magnesium and ferric ions on calcium carbonate biomineralization induced by cyanobacteria. [ABSTRACT FROM AUTHOR]

Understanding hydrocarbon microseepage mechanism is important for interpreting hydrocarbon anomalies in the surface geochemical exploration. An experiment was developed to simulate the vertical microseepage of hydrocarbons with multiple lithological layers. The results revealed that the microseepage below the water table was dominated by buoyancy of microbubbles with diffusion as a secondary mechanism, however, it was dominated by diffusion with little effect by gas convection above the water table. The micro-fractures were the dominant channels for microseepage. A phenomenological model was developed to quantify the vertical microseepage in different media and provided a better tool in a field environment. [ABSTRACT FROM AUTHOR]

Extensive studies have led to a common understanding of how organic molecules affect the phase, morphology and crystal structure of carbonate minerals. However, further analyses of crystal structures and the unique thermal decomposition characteristics of calcite affected by glycine have rarely been reported. Here, glycine was added as an additive to investigate the biomimetic mineralization of calcites at different glycine concentrations and pH values by virtue of the titration method. The sample characteristics were first analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and laser grain size analysis to investigate the morphology, crystal structure and grain size distribution, respectively. The results indicate that the precipitates are calcites, although SEM and XRD analyses indicated significant differences regarding surface morphology, cell density and cell volume. In addition, taking into account the complexation of Ca2+ with glycine, the samples removed from the precipitation system at different time intervals also confirm the presence of vaterite. More importantly, comparative studies of thermal decomposition between calcites under different conditions were carefully investigated using thermogravimetric analysis at different heating rates of 5, 10, 20, and 30 °C min−1 from 100 to 1000 °C. The kinetic parameters of average activation energy (E) and pre-exponential factor (A) were calculated by the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods to verify that the calcite has a lower crystallinity, activation energy and enthalpy change (ΔH) with glycine incorporation. Thus, this study provides important new insight into the effects of glycine in inducing the biomimetic mineralization of calcite, especially the crystal structural and thermodynamic characteristics. [ABSTRACT FROM AUTHOR]

The North Qilian Orogenic Belt is on the northeastern margin of the Tibetan Plateau. It is connected with the Alxa Block in the north and the Tethyan orogenic assemblage in the south. The Lower Silurian Angzanggou Formation, deposited in the northern area of the North Qilian Orogenic Belt, is the most important for revealing the architecture and orogenic processes of the North Qilian Belt. Provenance analysis of the Angzanggou Formation can reveal not only the tectonic evolution of the central orogenic belt of China but also Palaeozoic Asia plate reconstructions. Petrographic analysis indicated that the compositional and textural maturity of the sandstones was low. The detrital composition of the Angzanggou Formation samples consists of quartz (8–14 %), feldspar (6–29 %) and lithic fragments (56–86 %). The sandstones could be classified as litharenites or feldspathic litharenites. The detrital modal composition suggests that these sandstones were probably deposited in a fore-arc basin. The element ratios and some discrimination diagrams based on geochemistry indicate that felsic and intermediate rocks were the main source rocks. The SiO2/Al2O3 ratio, the index of chemical variability and the Th/Sc versus Zr/Sc discrimination diagram suggest that the compositional maturity and degree of recycling were moderate to low. The index of alteration (CIA) and the A–CN–K diagram indicate the intensity of weathering was moderate. The discrimination diagrams based on major and trace elements and petrographic discrimination diagrams imply that the Angzanggou Formation rocks were derived from a continental island arc, and a sedimentary cover probably overlaid the volcanic arc. Therefore, we infer that during Early Silurian time the North Qilian Belt sediments accumulated in a fore-arc basin. [ABSTRACT FROM AUTHOR]

This paper focuses on the depositional processes and environmental changes during initial marine flooding recorded in the lower Cambrian succession of the North China Platform in Shandong Province, China. In order to understand imbalance of accommodation and sediment supply in the initial stage of basin-fill, a detailed analysis of sedimentary facies was made for the lowermost siliciclastic deposits of the Liguan Formation. It reveals ten siliciclastic lithofacies in three large-scale outcrops (Jinhe, Anqianzhuang, and Zhangjiapo sections). These facies are grouped into four facies associations, representing siliciclastic foreshore-shoreface (S1), siliciclastic offshore (S2), distributary mouth bars (S3), and coastal plain (S4). The siliciclastic components occur in a linear belt, emanating from a major drainage system in the northeastern part of the platform. Deposition of siliciclastic sediments was largely controlled by regional topography of the unconformable surface and shoreline configuration as well as strong effect of waves and currents. With ensued rise in sea level and decrease in siliciclastic sediment supply, carbonate sediments prevailed, filling the accommodation created by epeirogenic subsidence and sediment loading. [ABSTRACT FROM AUTHOR]

Fine-grained sediments from the Late Triassic Yanchang Fm. in the Ordos Basin (central China) were studied by core analysis and geophysical logging. Part of the mudstones in this formation are stratified, part of them are unstratified; the various mudstones can be subdivided into eight types on the basis of their structures and textures. They represent a variety of environments, ranging from delta fronts and subaqueous fans to deep-water environments. Part of the sediments were reworked and became eventually deposited from subaqueous gravity flows, such as mud flows, turbidity currents and hyperpycnal flows that easily developed on the clay-rich deltaic slopes. The sediments deposited by such gravity flows show abundant soft-sediment deformation structures. Understanding of such structures and recognition of fine-grained sediments as gravity-flow deposits is significant for the exploration of potential hydrocarbon occurrences. Because fine-grained deposits become increasingly important for hydrocarbon exploration, and because the sediments in the lacustrine Yanchang Formation were deposited by exactly the same processes that play a role in the accumulation of deltaic and prodeltaic fine-grained sediments, the sedimentological analysis provided here is not only important for the understanding of deep lacustrine sediments like the Yanchang Formation, but also for a better insight into the accumulation of fine-grained prodeltaic deep-marine sediments and their potential as hydrocarbon source rocks and reservoir rocks. [ABSTRACT FROM AUTHOR]