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Natural fibrous gypsum is a kind of high-quality gypsum resources, whose high-value added utilization pathway is to be transformed to α -calcium sulfate hemihydrate (α -HH), a cementitious material that can react with water to form pastes with mechanical strength. In this work, α -HH was prepared from natural fibrous gypsum in KCl mediated glycerol-water solution under mild condition. KCl played a simultaneous function on regulating the phase-transition kinetics, morphology and comprehensive strength of α -HH. Addition of low concentration of KCl prominently retarded the nucleation and growth rate of α -HH and decreased its aspect ratio due to the formation of syngenite on the side faces. While further increase of KCl concentration accelerated the nucleation and growth rate and decreased the crystal sizes. In the presence of 0.04 M KCl, the prepared α -HH presented a hexagonal prism shape with a length / width of 257.69–579.71 μm / 13.13–36.61 μm, and its dry comprehensive strength had reached 38.1 MPa that was comparable to those prepared in commercial, chloride and nitrate system. Altogether, the foreign ion-free glycerol-water solution contributed to transforming natural fibrous gypsum to α -HH with high purity and high mechanical strength. • Transformation of natural fibrous gypsum to α -HH in glycerol-water solution. • Regulation of KCl on phase-transition kinetics, morphology and mechanical strength. • Hexagonal prism shape α -HH with high aspect ratio presents high mechanical strength. • α -HH paste with high mechanical strength has a compact microstructure. [ABSTRACT FROM AUTHOR]

The identification of formation fluid properties of igneous rock reservoirs plays a vital role in the igneous rock oil/gas exploration and development. Due to the complex lithology, low porosity, low permeability and strong heterogeneity of igneous rock reservoirs, conventional geophysical logging evaluation methods are not as accurate as sandstone reservoirs in response to different fluid properties of igneous rock reservoirs. It is difficult to identify the fluid type of the formation. In order to solve this problem, with the rapid development of array acoustic logging technology, this paper proposes a new method for analyzing the time–frequency characteristics of full wave train data based on the large amount of information contained in the array acoustic wave train, hoping to more accurately identify the fluid properties of igneous rock reservoirs. This paper introduces the time slice and frequency slice of Choi–Williams distribution with different IMF components obtained by EMD method and analyzes the characteristics of time slice and frequency slice of reservoirs with different fluid properties, in order to be used for identification of formation fluid types. The results show that the time slices and frequency slices of different IMF components have significantly different characteristics for different formation fluid properties of igneous rocks. This new method can provide geophysical and geological researchers with some new information to more accurately identify the properties of formation fluids. [ABSTRACT FROM AUTHOR]

The Kungurian period in the late Palaeozoic was characterized by a climatic transition from icehouse to greenhouse conditions, during which organisms flourished. Thick carbonate rocks developed in shallow water in most of the low-latitude palaeogeographic areas of the globe in this period. The sedimentary environments have long been considered steady and unidirectional. However, studying the Xuyong section in South China and comparing it with other regions may change this view. In this study, we obtained the lithological and geochemical data for slope facies carbonate rocks, including eight sedimentary microfacies from MF1 to MF8. The results showed transgressions in the Xuyong section characterized by an increase in palaeosalinity, a decrease in seawater temperature, and an increase in reduction. By comparing 13 sections from the same low palaeolatitude, we found that there may be four changes in the carbon isotope and strontium isotope chemical strata. These changes might provide support for a potential global palaeoenvironment event, the Kungurian Carbon Isotopic Excursion. Moreover, although the geochemical characteristics in different regions include good comparability, nonetheless seawater circulation and the palaeoclimate were found to be the main factors influencing the carbon cycle after excluding the influence of tectonic factors and volcanic eruptions. Additionally, we inferred that although thick carbonate rocks were produced in different low-latitude oceans, these carbonate rocks did not necessarily form in the same environment. During periods of tectonic stability, the influence of palaeoclimatic conditions on sedimentary environments cannot be ignored. [ABSTRACT FROM AUTHOR]

Research on the distribution of mantle CO2 should involve comprehensive analysis from CO2 source to accumulation. The crust‐mantle pathway system is the key controlling factor of the distribution of mantle CO2, but has received little attention. The pathway system and controlling factors of CO2 distribution in the Bohai Sea are analyzed using data on fault styles and information on the mantle and lithosphere. The relation between volcanic rocks and the distribution of mantle CO2 is reassessed using age data for CO2 accumulations. The distribution of mantle CO2 is controlled by uplift of the asthenosphere and upper mantle, magma conduits in the mantle and fault systems in the crust. Uplifted regions of the asthenosphere are accumulation areas for CO2. The area with uplift of the Moho exhibits accumulation of mantle CO2 at depth. CO2 was mainly derived from vertical migration through the upper mantle and lower crust. The fault style in the upper crust controls the distance of horizontal migration and the locations of CO2 concentrations. The distribution of mantle CO2 and volcanic rocks are not the same, but both probably followed the same pathways sometimes. Mantle CO2 in the Bohai Sea is concentrated in the Bozhong sag and the surrounding area, particularly in a trap that formed before 5.1 Ma and is connected to crustal faults (the Bozhang faults) and lithospheric faults (the Tanlu faults). [ABSTRACT FROM AUTHOR]

The ecogroup classification based on the growth-form of plants (Eco-Plant model) is widely used for extant, Cenozoic, Mesozoic, and Paleozoic paleoenvironmental reconstructions. However, for most Mesozoic dispersed sporomorphs, the application of the Eco-Plant model is limited because either their assignment to a specific ecogroup remains uncertain or the botanical affinities to plant taxa are unclear. By comparing the unique outline and structure/sculpture of the wall of dispersed sporomorph to the sporomorph wall of modern plants and fossil plants, 861 dispersed Mesozoic sporomorph genera of Bryophytes, Pteridophytes, and Gymnosperms are reviewed. Finally, 474 of them can be linked to their closest parent plants and Eco-Plant model at family or order level. Based on the demands of the parent plants to different humidity conditions, the Eco-Plant model separates between hydrophytes, hygrophytes, mesophytes, xerophytes, and euryphytes. Additionally, due to different temperature demands a separation in megathermic, mesothermic, microthermic, and eurythermic plants is possible. In the Mesozoic, both spore-producing and pollen-producing plants are adapted to different kinds of humidity. The concept to use the spore/pollen ratio to reflect the hygrophytes/xerophytes ratio is therefore questionable. The presented ecogroups for dispersed Mesozoic sporomorphs now allow identifying at least relative plant, paleoenvironmental and paleoclimate changes in Mesozoic sedimentary records. • Linking Mesozoic dispersed sporomorphs to their possible parent plants. • Linking Mesozoic dispersed sporomorphs to humidity and temperature. • Providing a useful method to use Mesozoic dispersed sporomorphs for paleoenvironmental reconstruction. [ABSTRACT FROM AUTHOR]