Search

Abstract Accurate evaluations of beta dose rates are crucial in luminescence and electron spin resonance (ESR) thermochronology. Most igneous rocks are heterogeneous and have complex mineralogical structures that render them unsuitable for the conventional methods of beta dose rate calculations based on infinite matrix assumptions. The recently developed software DosiVox-2D provides a Monte-Carlo approach for calculating beta dose rates in realistic heterogeneous geometries. In this paper, we present 2D simulations of uniform and layered igneous rocks. For the modelling, mineral distribution maps were obtained by QEM-EDS (quantitative evaluation of minerals using energy dispersive spectroscopy) and radionuclide concentrations in minerals were determined by laser ablation (LA) ICP-MS. The results show that the skewness of beta dose rate distributions in quartz reduces as the K concentration in a rock increases, and the estimation of the beta dose rate can be critically influenced by the U and Th concentrations and distributions. Highlights • QEMSCAN® provides realistic 2D mineral mapping for heterogeneous rocks. • A single set of radionuclide concentrations cannot be representative for some U and Th enriched minerals. • Selections of representative slices, mapping resolution and size are essential to obtain reliable beta dose rate. • Beta dose rate calculation can be critically influenced by the U and Th concentrations and distributions. • DosiVox-2D enables to estimate beta dose rate in single-grain level. [ABSTRACT FROM AUTHOR]

Abstract Many samples used for luminescence and ESR dating show complex mineralogical structures, resulting in heterogeneous beta dose rates. Ideally, the beta dose rate distribution could be reconstructed using softwares like DosiVox, which can both upload 3D-scans recorded with X-ray tomography and distributions of radioactive elements. However, some minerals often exhibit only small X-ray contrasts making them difficult to distinguish in 3D-scans. For example, quartz and plagioclase have closely similar X-ray characteristics, which limit the applicability of this approach. Here, we introduced a Monte Carlo simulation of beta particles in two dimensions, in order to calculate the dose rate from 2D images. The simulation results are compared between 2D modelling, 3D modelling and standard calculation. The implications for beta dose rate heterogeneity in grains are discussed. Using the "DosiVox-2D" software, we show that 2D scans may characterize complex heterogeneous 3D beta dose rate distributions. This approach could lead to a better understanding of micro-dosimetric phenomena and the improvements in the accuracy of dose rate calculation for heterogeneous samples. Highlights • We set up a new method of beta dose rate modelling for trapped charge dating. • A 2D representation of the sample is created from mineral mapping. • Beta dose rate is simulated in 2D and calculated for the different minerals. • 2D-modelling provides equivalent results to those of 3D-modellings. • 2D-modelling is easier to set up than 3D-modellings although less accurate. [ABSTRACT FROM AUTHOR]

Phosphorus is the central ingredient in fertilizer that allows modern agriculture to feed the world's population. This element, also critical in a host of industrial applications, is a nonrenewable resource that is sourced primarily from the phosphatic mineral apatite, hosted in sedimentary and igneous ores. World phosphate resources are estimated by the U.S. Geological Survey at ca. 300,000 Mt, of which 95% are sedimentary and 5% are igneous. Current known USGS reserve estimates are sufficient for a maximum of 200 to 300 years; the exploration and discovery of new resources, enhanced mining technologies, and new technologies aimed at the recovery and recycling of P from sewage and agricultural runoff will all contribute to extending P production. Igneous ores are generally associated with Phanerozoic carbonatites and silica-deficient alkalic intrusions that typically average 5 to 15 wt % P2O5, which can be beneficiated to high-grade concentrates of at least 30 wt % P2O5 with few contaminants. Carbonatites are typically the smallest and youngest parts of a carbonatite-alkaline rock complex that formed during fractional crystallization of a calcic parental alkaline silicate melt, or from liquid immiscibility of a carbonate-rich nephelinite that underwent magmatic fractionation and differentiation during ascent from the mantle source. Fluorapatite generally crystallizes early, near the liquidus, and over a small temperature interval below the apatite saturation temperature that varies strongly with temperature, SiCL and CaO concentrations, and the aluminosity of the melt. Carbonatite-alkaline rock complexes commonly possess a concentric, zonal structure thought to reflect caldera volcanism. Pathfinder elements in soils, sediments, tills, and vegetation include Nb, rare earth elements (REEs), P, Ba, Sr, F, U, and Th, and in water, F, Th, and U are indicators. Remote sensing techniques with the ability to identify minerals rich in CO3, REEs, and Fe2+ that are characteristic of carbonatites are also important exploration tools that may provide vectors to ore. Sedimentary phosphorite is a marine bioelemental sedimentary rock that contains >18 wt % P2O5. While small peritidal phosphorites formed in Precambrian coastal environments, economically significant upwelling- related phosphorite did not accumulate until the late Neoproterozoic and continued through the Phanerozoic. Coastal upwelling delivered deep, P-rich waters to continental shelves and in epeiric seas to drive phospho-genesis and form the largest phosphorites on Earth. High-grade deposits formed as a result of hydraulic concentration of phosphate grains to form granular beds with minimal gangue. The amalgamation of these beds into decameter-thick, stratiform ore zones is generally focused along the maximum flooding surface, which is a primary exploration target in upwelling-related phosphorite. In addition to P, other elements concentrated in igneous and sedimentary phosphorites are Se, Mo, Zn, Cu, and Cr, which are important agricultural micronutrients. Other saleable by-products include U and REEs. The U concentration in sedimentary phosphorite is generally between 50 and 200 ppm, but can be as high as 3,000 ppm, making it an increasingly important source of U for the nuclear industry. The concentration of REEs in some sedimentary phosphorites is comparable to the world's richest igneous and Chinese clay-type REE deposits. The source of the dissolved P in upwelling ocean water is ultimately derived from the chemical weathering of continental rocks, the process that links igneous and sedimentary phosphorites through time and space. The covarying temporal relationship of igneous and sedimentary deposits suggests that plate tectonics and the concentration of apatite in a progressively more felsic crust underpins the feedback processes regulating the biogeochemical cycling of P Critical to the generation of greenfield exploration targets is the recognition that large P deposits emerged in the late Neoproterozoic. The geological environments conducive for exploration can be constrained from an understanding of ore-forming processes by the use of complementary petrological techniques, including fieldwork, petrography, sedimentology, sequence stratigraphy, and geochemistry. [ABSTRACT FROM AUTHOR]

In recent years, the Journal of Palaeogeography (Chinese Edition and English Edition) continually received manuscripts, in which some authors are from China and some are from Pakistan, Lithuania, Morocco, South Africa, etc. The authors of these manuscripts, according to the viewpoint and method of Miall's paper (1985), selected rocks from each bed in the clastic sections of their study areas and induced some rock types, such as conglomerates, sandstones and fine-grained stones, and considered them as lithofacies. It does not conform to the definition of lithofacies. I wrote some papers, i.e., Feng (2018, 2019, 2020), to point out the problems and hope that the authors worldwide, especially Chinese authors, will not continually cite, spread and follow Miall's paper (1985) viewpoint and method blindly. Prof. Miall is the first person who considered rocks (in fact, the sediments) as lithofacies and proposed a facies analysis method. His viewpoint and facies analysis method confused the definition of facies and facies analysis method. My current paper is a special article to discuss the principal problems of Miall's paper (1985), i.e., he considered the sediments as lithofacies and utilized lithofacies to analyze facies, but not to discuss the contributions and less strictness of architectural elements of his paper. Here, I have to declare that the facies in my current paper is the facies of sedimentary petrology, but not of other geological disciplines, such as igneous petrology, metamorphic petrology, palaeontology, stratigraphy, geophysics, geochemistry. Certainly, the definitions of facies and lithofacies are controversial. My current paper will adhere to the policy of "A hundred flowers blossom and a hundred schools of thought contend". I hope that through academic discussions, contends and geological practice, these problems will be solved gradually. [ABSTRACT FROM AUTHOR]

Abstract: Paper uniformity, commonly referred to as formation, depends to a large degree on the uniform distribution of pulp fibers in a sheet of paper. Fiber flocculation impairs paper formation. The size and strength of fiber flocs is determined mainly by two factors: (i) the number of fiber contact points between fibers in a floc and (ii) the bond strength at these contacts. The contact number between fibers can be expressed in terms of the crowding number, which is determined by fiber concentration and fiber dimensions. For the bond strength at the contact points, we developed a bridging strength model, based on interactions between a single fiber and neighboring fibers in a floc, taking into account the surface coverage of the components of the flocculating systems (retention aids) on the fiber surface. The model explains the effects of retention aids on floc strength and formation fairly well. Fillers in the wet end of a paper machine weaken the fiber flocs, possibly by transferring polymer from fiber to filler surfaces. Implications of the model for the control of paper uniformity on a paper machine are discussed. [Copyright &y& Elsevier]

Dual-energy computed tomography (CT) provides a better material classification capability than traditional CT. A scintillator is an essential component that determines the optical resolution, detective quantum efficiency, and energy separation of the dual-layer dual-energy CT system. In this paper, we propose a new dual-layer scintillator combination composed of CsI:Tl and LYSO:Ce for dual-energy CT imaging. The x-ray attenuation physical process of CsI:Tl and LYSO:Ce combination is simulated on Geant4. The energy distribution and luminescence of different thicknesses of the scintillator combination are investigated by simulation experiments. Then, the optimal thicknesses of the combination are designed based on simulation results. Furthermore, a dual-layer dual-energy CT system using the scintillator combination is built, and practical dual-energy imaging experiments are implemented in the system. Simulation results indicate that the CsI:Tl and LYSO:Ce combination can effectively realize dual-energy detection. The optimal thickness is 100 μm for CsI:Tl and 500 μm for LYSO:Ce. Practical experiments show that the dual-energy CT system using the CsI:Tl and LYSO:Ce combination has low noise. Materials of the metal mixture sample and the igneous rock sample are correctly separated using the dual-energy data obtained by the CsI:Tl and LYSO:Ce combination. Therefore, the CsI:Tl and LYSO:Ce combination is expected to be used in dual-energy CT imaging studies of complex materials, such as metals, bones, and rocks. [ABSTRACT FROM AUTHOR]

Developments in ultradeep azimuthal resistivity (UDAR) technology has recently progressed from their application in high-angle and horizontal wells to low-angle and vertical wells. This has presented the opportunity to assess their suitability as derisking tools because of their ability to look ahead of the bit, up to c. 100 ft (c. 30.5 m). Dominated by a complex interplay of structure, sedimentation, and volcanic activity, the NE Atlantic Margin presents a challenging environment to plan and drill wells safely and within planned budget, with many wells drilled within the Faroe–Shetland Basin (FSB) currently the most expensive to-date within the United Kingdom continental shelf (UKCS). The limited number of wells drilled in the FSB and their geographical sparsity relative to those of other areas of the UKCS, make offset analysis and derisking a challenge. The often-unpredictable distribution of igneous rocks throughout the basin presents significant challenges in the planning and drilling of oil and gas wells. Up to 88% of igneous intrusions within the FSB are estimated to be below seismic resolution, which alongside variation in composition, presents significant issues related to drilling safely, efficiently and successfully. Within this paper, we investigate the use of UDAR technology and how they could be deployed in areas of complex volcanic geology such as the West of Shetland (WoS). This paper reviews the nature of the drilling experiences within the FSB to date, the impact it has on exploration, and how improvements in drilling technology could help decrease nonproductive time (NPT). [ABSTRACT FROM AUTHOR]

Archaeometry can help archaeologists in many ways, and one of the most common archaeometric objectives is provenance analysis. Volcanic rocks are often found in archaeological sites as materials used to make grinding tools such as millstones and mortars or as building materials. Petrographic characterization is commonly applied to identify their main mineralogical components. However, the provenance study of volcanic stones is usually undertaken by comparing geochemical data from reference outcrops using common descriptive statistical tools such as biplots of chemical elements, and occasionally, unsupervised multivariate data analysis like principal component analysis (PCA) is also used. Recently, the use of supervised classification methods has shown a superior performance in assigning provenance to archaeological samples. However, these methods require the use of reference databases for all the possible provenance classes in order to train the classification models. The existence of comprehensive collections of published geochemical analyses of igneous rocks enables the use of the supervised approach for the provenance determination of volcanic stones. In this paper, the provenance of volcanic grinding tools from two archaeological sites (Iulia Libica, Spain, and Sidi Zahruni, Tunisia) is attempted using data from the GEOROC database through unsupervised and supervised approaches. The materials from Sidi Zahruni have been identified as basalts from Pantelleria (Italy), and the agreement between the different supervised classification models tested is particularly conclusive. In contrast, the provenance of the materials from Iulia Libica remained undetermined. The results illustrate the advantages and limitations of all the examined methods. [ABSTRACT FROM AUTHOR]

Rock abrasivity is one of the main factors affecting the wear of rock-cutting tools, which is usually quantified by the CERCHAR Abrasivity Index (CAI). Researchers and engineers study tool wear and predict tool life based on the CAI of rocks. However, there is still a lack of a dataset on rock properties, especially the abrasivity of various rocks. This paper reports the abrasive dataset of 10 kinds of rocks, including sedimentary rocks, metamorphic rocks, and igneous rocks, with the aid of the CERCHAR Abrasivity Test and digital measurement techniques. The dataset comprises rock abrasivity data, point cloud data for visualization, scratch photos, CERCHAR Abrasivity Test force data, and mechanical properties (uniaxial compressive strength) of rock samples. This dataset facilitates future research on rock abrasivity and rock-cutting tool wear. [ABSTRACT FROM AUTHOR]

A structural analysis of Cretaceous alkaline dykes swarm associated with the central segment of the Asunción Rift is reported here. Dykes are generally single near-vertical tabular bodies, less than 5m wide, although multiple and composite intrusions also occur. Many of these small bodies have been emplaced into Paleozoic sedimentary rocks and exhibit a regional NW-SE orientation pattern. Petrographical and geochemical data allow recognition of two different lineages of potassic dykes: a silicaundersaturated suite ranging from basanite to phonolite (B-P) and a silica-saturated suite ranging from alkali basalt to trachyte (AB-T). The morphological features, the regional en-échelon distribution, and the NW-SE orientation pattern suggest that the dykes were injected along fractures and faults, under a transtensional tectonic regime with σ1 NW/horizontal, σ2/vertical, and σ3 NE/horizontal.Detailed analysis, combining dyke petrography, orientation pattern, and relative chronology reveals a rotation from WNWtoward NNW during dyke emplacement. In terms of the paleostress field orientation, the evidence indicates that the dykes were diachronically formed under a similar stress condition. Finally, the pattern of orientation documented for the Cretaceous alkaline dykes of the Asunción Rift is consistent, temporally and spatially, with the phases of regional deformation that occurred during the process of the Atlantic Ocean opening. [ABSTRACT FROM AUTHOR]

High-grade highly deformed gneisses crop out continuously along the Masanteo peninsula in the Cabo Ortegal nappe (NW Spain). The rock sequence formed by quartzofeldspathic gneisses and mafic rocks records two partial melting events: during the Early Ordovician (ca. 480-488Ma.), at the base of the Qz-Fsp gneisses, and immediately after eclogization (ca. 390.4±1.2 Ma), during its early Variscan exhumation. Despite the strain accumulated during their final exhumation in which a pervasive blastomylonitic S2 foliation was developed, primary sedimentary layering in Qz-Fsp gneisses is well preserved locally at the top of the sequence. This first stage of the exhuma tion process occurred in ~10Ma, during which bulk flattening of the high-grade rock sequence was accommodated by anastomosing shear bands that evolved to planar shear zones. Strain was progressively localized along the boundaries of the migmatitic Qz-Fsp gneisses. A SE-vergent ductile thrust constitutes the base of gneisses, incorporating eclogite blocks-in-matrix. A NW-vergent detachment placed the metasedimen tary Qz-Fsp gneisses over the migmatitic Qz-Fsp gneisses. A difference in metamorphic pressure of ca. 0.5GPa is estimated between both gneissic units. The high-grade deformation reduced substantially the thickness of the gneissic rock sequence during the process of exhumation controlled by change in the strain direction and the progressive localization of strain. The combined movement of the top detachment and basal thrust resulted in an extrusion of the migmatites within the nappe, directed to the SE in current coordinates. [ABSTRACT FROM AUTHOR]

AG-MP-1M anion exchange resin is commonly used to separate and purify Cd from geological and environmental samples. However, a second column using anion exchange, TRU Spec, or BPHA extraction resins is also required to further purify Cd from the residual Sn for high-precision Cd isotope ratio measurements. In this study, a new and efficient single-stage separation method using AG-MP-1M (100–200 mesh) anion exchange resin was developed to separate Cd from geological and environmental samples for high-precision Cd isotope ratio measurements. Most of the Sn (>99%) is effectively stripped from the resin using a 2 M HCl + 4 M HF mixed eluent, unlike commonly used separation protocols with AG-MP-1M anion exchange resin, which only removes ∼65% of the Sn using HCl eluent. Furthermore, potential residual Sn is retained on the resin by elution of 0.04 M HCl + 2 M HF and 0.005 M HCl + 2 M HF, which allows quantitative collection of the Cd fraction (∼99.5%) without Sn tailing. The single-stage purification procedure takes advantage of the different affinities of Sn on AG-MP-1M anion exchange resin at different HCl and HF concentrations in mixed HCl + HF solutions, which allows direct and effective separation of Cd from Sn and other complex sample matrices. We used this procedure and the double-spike MC-ICP-MS method to determine the δ114/110CdNIST SRM 3108 values for Mn nodule, igneous rock, shale, soil, and sediment reference materials, and obtained results that agree within analytical uncertainty with the values reported in previous studies. In addition, the δ114/110CdNIST SRM 3108 values of soil (GSS-1a), sediment (GSD-4a), and dolomite (GSR-12) standard reference materials are reported for the first time in this paper. The described purification procedure allows efficient and rapid Cd isotopic analysis in different types of geological and environmental samples. [ABSTRACT FROM AUTHOR]

Mesozoic igneous rocks are widely distributed in the South China Sea (SCS) and its adjacent areas and are exposed in the SCS, South China, Hainan, Indochina, Taiwan, the Philippines, and Borneo; these rocks are mostly dominated by granitoids. This paper presents a complete map of the Mesozoic igneous rocks of the SCS and its adjacent areas. This paper also presents an analysis of geological survey and published data in terms of seismic profiles, ages, geochemistry and isotopic systematics of the Mesozoic igneous complexes of the SCS and its adjacent areas. Three periods of igneous activity can be distinguished: (1) Permian – Triassic that spans from 250–201 Ma; (2) Jurassic (201–145 Ma); and (3) Latest Jurassic/Cretaceous to Maastrichtian (145–66 Ma), of which the Cretaceous is the best preserved and could possibly be the most widespread. Triassic igneous rocks are distributed in the northwestern and southern SCS (Qiongdongnan Basin, Yinggehai-Song Hong Basin, Beibu Gulf Basin, the Dangerous Grounds, and the Reed Bank); Jurassic igneous rocks are distributed in the northern and southern SCS (Pearl River Mouth Basin, Qiongdongnan Basin, Yinggehai-Song Hong Basin, Beibu Gulf Basin, and the Reed Bank); and Cretaceous igneous rocks are distributed in the northern, western and southern SCS. The igneous activity of the SCS is mostly distributed in the continent slope. Mesozoic igneous rocks of the SCS include at least 350 rock masses: the smallest being 0.182 km2, the largest being 5,5,502 km2, and the total area covering 688,539 km2. Mesozoic magmatism in the SCS and its adjacent areas migrated oceanward (southeastward). Our new seismic profiles and the wells from the literature highlight that Jurassic granites occur not only inland of South China but also in coastal South China and the northern and southern SCS. The YING6 well in the northern SCS encountered andesite with an age of 68.24 Ma, which is the youngest age found for the SCS Mesozoic volcanic rocks. The XY1 well in the western SCS encountered granite with an age of 68.9 Ma, which is the youngest age found for the SCS Mesozoic intrusive rocks. The WZ12-3-1 well in the northern SCS encountered granite with an age of 243.3 Ma, which is the oldest age found for the SCS Mesozoic intrusive rocks. The encountered dacite ages (219.1 ± 1.4 Ma) of the NK-1 well in the southern SCS were the oldest ages found for the SCS Mesozoic volcanic rocks. The thickest Mesozoic igneous rocks (>1022.5 m) were encountered in the NK-1 well. Igneous rocks in the SCS and its adjacent areas are closely related to tectonic movements such as faults, plate movement, and mantle-derived igneous fluid ascent. They are controlled by the subduction of the Tethys lithospheric and Paleo-Pacific domains. [ABSTRACT FROM AUTHOR]

This document is an editorial from the journal "Contributions to Mineralogy & Petrology." It announces changes in the journal's editorial board, including the retirement of Prof. Tim Grove as the Executive Editor and the appointment of Prof. Dante Canil as the new Executive Editor. It also mentions the stepping down of Profs Mark Ghiorso and Timm John as Associate Editors and the addition of Christy Till and Ralf Dohmen as new Associate Editors. The editorial encourages the community to continue submitting articles that contribute to our understanding of the Earth's crust, mantle, and core. The document also highlights the high scientific quality of papers published in the journal, with an average of 61.7 citations per article. [Extracted from the article]

The paper presents isotopic U–Pb zircon data (LA-ICP-MS method) for the main types of high-potassic intrusive rocks of the Chorukh-Dairon W–Mo(–Cu–Au) skarn deposit situated in the Kurama segment of the Middle Tien Shan near the largest porphyry Cu–Mo–Au deposits of the Almalyk mineralized cluster. Together with the other Au, W, Mo and Cu deposits, all these deposits are parts of the extended Late Paleozoic metallogenic belt of Tien Shan. The concordant isotopic U–Pb zircon data obtained for the rocks of successive intrusion phases in the Chorukh-Dairon pluton span from about 298 Ma to 290 Ma. This interval included crystallization of monzodiorite (295.1 ± 3.3 Ma), quartz syenite (294.7 ± 2.3 Ma), quartz monzonite (294.1 ± 2.1 Ma), and monzogranite (293.0 ± 3.0 Ma). These dates correspond to the pluton emplacement at the Late Carboniferous-Early Permian boundary and highlight its younger age compared to the productive high-potassic intrusions of the porphyry Cu–Mo–Au deposits in the Almalyk mineralized cluster, the latter assigned to the Late Carboniferous (about 337–313 Ma and partially to 308–297 Ma). By contrast to the latter, which were intruded in the subduction-related environment, the emplacement of the high-potassic rock of the Chorukh-Dairon pluton occurred in the transitional subduction-related to post-collisional environment or even under an actual post-collisional regime. This allows distinguishing two pulses of ore-bearing Carboniferous-Permian high-potassic calc-alkaline to shoshonitic series magmatism in the Middle Tien Shan. Consistently, there is a metallogenic evolution in the region that was expressed in the transition from porphyry Cu–Mo–Au deposits associated with subduction-related potassic magmatism, and likely evolving toward epithermal Au-Ag deposits, to essentially tungsten (W–Mo–Cu–Au) deposits associated with younger potassic magmatism occurring rather in the post-collisional environment. [ABSTRACT FROM AUTHOR]

The Qinghai-Tibetan Plateau and its surrounding areas have a long and complex tectonic evolutionary history. Cratons and blocks, such as northern India, Lhasa, Qiangtang, Qaidam and Central Qilian, and their in-between orogenic belts constitute the main part of the Qinghai-Tibetan Plateau. During the Cambrian Period, most of these cratons and blocks were on the northwestern periphery of Gondwana, and were associated with the surrounding blocks, e.g. Arabian, Central Iran, Afghanistan, Tarim, Alxa, North China, South China and Sibumasu through the Proto-Tethys Ocean. The Cambrian stratigraphic sequences on these stable blocks are composed of mixed siliciclastic and carbonate rocks deposited in the shallow-water marine environments, and contain the trilobite assemblages of shelf facies. The Cambrian stratigraphic sequences in the Qilian tectonic belts, however, are characterized by the intermediate-basic igneous rocks and silicates formed in the Proto-Tethys Ocean, and contain the trilobite assemblages of deep-water slope facies. Combining with previous data, field observations and newly discovered fossils through funding by the Second Tibetan Plateau Scientific Expedition and Research, the general characteristics of the Cambrian strata in different tectonic units of the Qinghai-Tibetan Plateau and its surrounding areas have been summarized in this paper. Furthermore, efforts have been made to subdivide and correlate the Cambrian strata across these areas by utilizing available biostratigraphic and geochronological data. As a result, a comprehensive litho- and biostratigraphy chart has been compiled. Finally, from the biogeographic perspective, this paper also provides a brief overview of the Cambrian paleogeographical reconstruction of the major tectonic blocks, and discusses the problems associated with the evolution of the Proto-Tethys tectonic belt. [ABSTRACT FROM AUTHOR]

Magmatism is a very important manifestation of the deep activity of the Earth. The geochronology and geochemistry of the Zhaojinggou monzogranite pluton indicate that magmas were derived from the late Paleoproterozoic to Mesoproterozoic lower crustal mafic materials. It was established a magma plumbing system that provides new constraints for magma evolution. [Extracted from the article]

The article discusses the mesoproterozoic continental flood rhyolite province, the Gawler Range Volcanics (GRV) in South Australia. It presents a viable mechanism for sustaining a large volume felsic igneous province and suggests that the GRV province represents an end member of the Large Igneous Province clan. It notes that the low viscosity of the felsic magmas has produced a unique igneous system on a scale which is either not present or poorly preserved elsewhere on the planet.

Copyright of Egitania Sciencia is the property of Egitania Sciencia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The southern Great Xing'an Range is located in the eastern Central Asian Orogenic Belt, where voluminous igneous rocks developed during the Late Mesozoic period. The east slope of the southern Great Xing'an Range has been the topic of numerous debates on the level of influence of the Mongol-Okhotsk and the Paleo-Pacific regimes in the Late Mesozoic period. Therefore, this area is a suitable region in which to study the temporal changes in magma sources and tectono-magmatic evolution. In this paper, whole-rock geochemical data, zircon U-Pb geochronology, and zircon Hf isotope studies were carried out on the granitoids in the east slope area of the southern Great Xing'an Range. LA-ICP-MS zircon U-Pb dating revealed the ages of four granitoid samples: 135.0 ± 0.6 Ma, 130.7 ± 1.4 Ma, 130.4 ± 1.0 Ma, and 127.6 ± 0.8 Ma, respectively. The Hf isotope values 176Hf/177Hf = 0.282751–0.283015, εHf (t) = +2.0~+11.5, and T2DM = 583~1442 Ma suggest that the magma was generated by partial melting of Meso- and Neoproterozoic accreted and thickened low crust. The whole-rock geochemical data implied that these granitoids are A-type granite and their formation is closely linked to the subduction of the Paleo-Pacific Ocean plate. These geochemical, isotopic, and geochronological data suggest that the Early Cretaceous magmatism in the east slope area of the southern Great Xing'an Range formed in an extensional back-arc tectonic setting associated with the slab roll-back of the Paleo-Pacific plate subduction. [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]

This paper completes the examination of results of the study of lithogeochemical characteristics of a pilot collection of the Riphean–Vendian sandstones, siltstones, and claystones (last one based on the interpretation of results) in Belarus. Data on the age of detrital zircon published in recent years suggest that Upper Precambrian rocks of this region were sourced from the Osnitsk–Mikashevichi and the Trans-Scandinavian igneous belts, the Volyn–Brest large igneous province, rapakivi granites, as well as various rock associations of Sarmatia, Danopolonian orogen and Svecofennides. Based on the lithogeochemical characteristics, the distribution of data points of the studied clastic rocks on discriminant diagrams provides insight into the possible provenance, paleogeodynamic, paleogeographic, and paleoclimatic settings and suggests several conclusions. The considered Riphean–Vendian stratons in Belarus are composed mainly of erosion products of within-plate granitoids, as well as various island-arc and syncollisional felsic igneous rocks. The share of erosion products of mafic rocks among them generally does not exceed 30%. It is significant mainly in the Volyn Group rocks (erosion products of the Volyn–Brest large igneous province), as well as in some samples of the Nizov, Selyavy, and Kotlin formations (fragments of mafic rocks from other provenances?). The source-to-sink transport was accomplished mainly by large rivers. Paleogeodynamic settings varied from quite active to quite passive. The paleoclimate in catchment areas was most likely arid/semiarid in the Riphean. In the Vendian, it was humid and varied from subtropical in the Early Vendian (except the Glusk Formation) to tropical in the Late Vendian. The obtained results also make it possible to show some peculiarities of the known methods and techniques of paleoclimate reconstruction. [ABSTRACT FROM AUTHOR]

X-ray spectra are pivotal for understanding chemical bonding and atomic interactions in materials. Particularly, valence-to-core (VtC) electronic transitions and satellite peaks within X-ray spectra provide insights into valence states and chemical environments. This study focuses on the multi-vacancy satellite peaks, Si KβIII and KβIV, and their application in analyzing silicate minerals in igneous rocks. A wavelength dispersive X-ray fluorescence (WD-XRF) spectrometer, commonly employed for chemical analysis of geological samples, was utilized in this study. The Si KβIII and KβIV peaks were selected due to their VtC transitions and multi-vacancy origin, offering enhanced sensitivity to the chemical environment. We examined 41 certified reference materials (CRMs) of igneous rocks, demonstrating the capaβility of these satellite peaks to reveal detailed chemical and structural information. A strong correlation was found βetween the chemical composition of silicate minerals and the intensities along with chemical shifts of the Si KβIII and KβIV peaks. We developed a regression model to predict mineral concentrations, validating the method with CRMs. The results suggest that the spectral region of the Si KβIII and KβIV peaks serves as a distinctive fingerprint for identifying silicate minerals in igneous rocks. [ABSTRACT FROM AUTHOR]

Knowing accurate values of rock engineering parameters in hard rock condition is the key in estimating and adjusting TBM performance. In this study, TBM penetration per revolution (Pr) as driving parameter, TBM operational parameters including cutterhead torque (Tq), field penetration index (FPI), thrust force (Th), cutter load (Fn), cutterhead rotational speed revolution per minute (RPM), and also cutterhead diameter as a mechanical machine specification are used to predict geomechanical parameters including rock quality designation (RQD) and unconfined compressive strength (UCS) based on reverse analysis in three types of strong rocks (Tuff, Andesite, Diorite) along the Southern lot of Kerman water transfer tunnel; KrWCT. A soft computing method called least squares-support vector machine (Ls-SVM), is trained using operating and driving data as well as rock engineering parameters gathered from the KrWCT project which is excavated in hard rock condition using double shield TBM. Due to the lack of access to the excavation face in mechanized tunneling, the collection of geomechanical data on the rock mass is possible only through the examination of excavated material and limited inspections during cutterhead repairs. Therefore, this paper has tried to predict and classify the rock engineering factors using some indicators related to machine performance, mechanical specification, and TBM operational parameters. Among the data collected during the pre-construction and construction phases of the project, the dataset was classified into 42 zones, and the reasonable distribution intervals of the main tunneling factors corresponding to each zone were defined. New empirical equations are developed to estimate the properties of igneous rocks based on linear and non-linear multivariable regression (MR). Several loss functions were used to assess the performance and precision of the applied methods. The results of the proposed models indicate an acceptable and reliable accuracy. Highlights: TBM data predicts rock engineering properties in complex geological condition. Forecasting RQD and UCS in deep tunnels through strong rocks using reverse analysis. Developing empirical models for calculating UCS and RQD based on statistical analysis. Detailed analysis of Ls-SVM supervised network for rock geomechanical prediction. Examining model accuracy with various statistical indices and loss functions. [ABSTRACT FROM AUTHOR]

Presents abstracts of the articles published in the "Journal of Japanese Forestry Society," vol. 86, no. 4. "Effects of seawater spraying on Quercus acutissima and soil of their woodland"; "Validation of models on "Forest Fire Emergency Measure Simulation": a case study of Kagamihara City"; "The effect of moss height on survival and growth of Picea jezoensis seedlings on fallen logs"; "Surface erosion from landslide site in weathered granite area and the analysis by using USLE".

This issue includes seven papers on Cadomian rocks from Bulgaria/Serbia through Turkey to eastern Iran (Figure 2). The most important exposures of Cadomian basements are found in the Strandja Zone, the Istanbul Zone, and the Anatolide-Tauride Block in Turkey, and NW Iranian Block and Central Iranian Microcontinent in Iran (Figure 2). Keywords: Cadomian belt; Pan-African orogeny; Turkey; Iran EN Cadomian belt Pan-African orogeny Turkey Iran 2385 2388 4 10/04/22 20221001 NES 221001 The Cadomian belt (ca. 600-500 Ma) extends from North America through Europe to Iran (Figure 1). [Extracted from the article]

The Prototethyan Ocean has been suggested as an Early Paleozoic Ocean developed at the Gondwana northern margin. However, its spatial pattern, subduction style and closure time in SW Yunnan and SE Asia still remain unknown. The Prototethyan evolution in SW Yunnan and SE Asia and its internal connection with the South China Kwangsian (Ordo-Silurian) intracontinental orogenesis are also poorly constrained. By summarizing and analyzing the Early Paleozoic geological records in the Sibumasu and Indochina blocks, the eastern South China and SW Japan, this paper proposes the existence of a giant Ordo-Silurian igneous belt along the Gondwana northern margin. A preliminary limitation has been obtained regarding the source nature and migration pattern of the igneous belt. Our data allow us to propose a model of the Early Paleozoic Andean-type active continental margin along the East Gondwana northern margin. This is the foundation to determine the southward subduction of the southern branch of the eastern Prototethyan Ocean underneath the Sibumasu and Indochina blocks along the Yunxian-Menghai (SW Yunnan)-Thailand Peninsula and the Tam Ky-Phouc Son suture in Central Vietnam, respectively, and the eastward linkage with the Early Paleozoic Osaka subduction zone in SW Japan across the peripheral Sanya area. These data synthetically indicate an easterly-diachronous and propagating Andean-type Cambrian (Furongian)-Silurian (Llandovery) orogenesis along the Gondwana northern margin from Nepal, NW India, South Tibet, Qiangtang to Central Vietnam across South Indochina and Sibumasu. This paper reconstructs the Early Paleozoic locations of the Sibumasu and Indochina fragments, as well as SW Japan and South China continent in the Gondwana northern margin, and proposes the far-field effect on the South China Kwangsian intra-continental orogenesis from the subduction of the Early Paleozoic Prototethyan southern branch. [ABSTRACT FROM AUTHOR]

Rock is constantly subjected to stress and thermal conditions. Thermal-induced micro-cracks will be generated as a result of different thermal expansion gradations between different minerals. This characteristic was investigated in this paper by studying the micro-properties of Sudbury norite via CT scanning and the image processing method. A novel filtering method, maximum–minimum shadow filtering (MMSF), was developed in this study to highlight the thermal-induced micro-cracks in Sudbury Igneous Complex (SIC) norite after different temperature treatments. Based on quantitative analysis, the areal percentages of biotite, felspar, quartz, and small amounts of metal minerals were determined. It was also found that small-scale micro-cracks were first observed in the middle of biotite grains at a temperature of 400 °C. The cracks further propagated and extended with the temperature increase. In addition, the orientations of cracks either remained at the same distribution or became more evenly distributed with the rising temperature. A linear relationship was found between the average porosity of SIC norite and the temperature. Moreover, the anisotropic properties between vertical and horizontal directions of norite were also noticeable. Overall, the paper presented a quantitative study on the effects of thermal treatment and the anisotropic properties of SIC norite. Methodology and findings from this paper will be a significant reference for future studies regarding the thermal impacts on norite and similar rocks. [ABSTRACT FROM AUTHOR]

The reasons for the formation of rare minerals and mineral assemblages during metamorphism and metasomatosis are found to be the atypical composition of the protolith, the structural–textural heterogeneity, restricted mass transfer, and high temperatures. This is often observed under shallow conditions (pressure up to 3 kbar) during additional heating of rocks by igneous intrusions. In this paper, these questions are discussed with a series of domestic examples, the processes of mineral formation in which are studied in detail. [ABSTRACT FROM AUTHOR]

The Mg‐spinel‐bearing rocks are an essential component of the lunar crust. They are widely distributed on the Moon's near and far sides. The study of petrogenesis provides a rare opportunity to understand the early lunar crust‐mantle interaction. Northwest Africa 12279 is a unique Mg‐spinel‐bearing troctolitic anorthosite lunar meteorite that is unbrecciated and pristine. The modal content of the spinel‐bearing troctolitic component is ∼95%. Five hundred sixty spinels larger than 100 μm are investigated in this paper, and 38 of them are found to contain magma melt inclusions. These magma melt inclusions represent the mixed composition between mantle melt and crust material during the crystallization of a spinel. They generally show an immiscible liquid phase separation, which can be divided into a magnesium‐rich and silica‐rich phase. The former is similar in chemical composition to the lunar mantle's peridotite or plutonic ultramafic Mg‐suite. The mantle melt reacts successively with Ferroan Anorthosites in the crust to crystallize Mg‐spinel, plagioclase, olivine, pyroxene, and silica phases. The large grains of euhedral Mg‐spinels with homogeneous chemical composition indicate they are the products of equilibrium crystallization, while plagioclase, olivine, pyroxene, and silica phase are the products of differentiated crystallization of mixed magma. This reaction may represent a typical process of lunar Mg‐suite. This work is the first to find petrological evidence that the melt from the lunar mantle intrudes into the crust and then undergoes a liquid phase immiscible separation to form the Mg‐spinel‐bearing troctolitic anorthosite. Plain Language Summary: Northwest Africa 12279 (weight 1,830 g) is the only known pristine and unbrecciated lunar spinel‐bearing troctolitic anorthosite, including lunar meteorites and returned samples. These pristine samples are indispensable for understanding Moon's history and chemical evolution. The spinel‐bearing rocks are an essential component of the lunar crust. They are widely distributed on the Moon's near and far sides. The study of petrogenesis provides a rare opportunity to understand the early lunar crust‐mantle interaction. Five hundred sixty spinels larger than 100 μm are investigated in three polished thin sections, and 38 contained magma melt inclusions. These magmatic inclusions represent the mixed composition between early mantle melt and crust material during the crystallization of a spinel. This work is the first to find evidence that the melt from the lunar mantle intrudes into the crust. The magnesium‐rich melt from the mantle assimilates with ferroan anorthosite (an igneous rock is composed of >90 vol.% plagioclase rich in calcium with minor iron‐rich pyroxene and olivine) from the early crust to form an Mg‐spinel‐bearing hypabyssal igneous rock. Key Points: Northwest Africa (NWA) 12279 is a unique lunar meteorite that is both unbrecciated and pristineThe magmatic melt inclusion in Mg‐spinel represents the mixed composition between lunar mantle melt and anorthositic crustThe formation of Mg‐spinel in NWA 12279 results from the interaction between the mantle material and the anorthositic crust of the Moon [ABSTRACT FROM AUTHOR]

Indonesia is surrounded by three tectonic plates: the Eurasian, Indo−Australian, and Pacific plates. The plates have caused Indonesia to have many volcanoes, both active and inactive, resting, or no longer active. One of the volcanoes belonging to the formed “Rest” category is the ancient Lawu volcano. The mountain is 10,000 radiocarbon years old or approximately 11,430 ​± ​130 calendar years ago, which is part of the Holocene age. The Lawu volcano erupted on November 28, 1885. This paper discusses the study of magnetic minerals in the case of pyroclastic flows originating from Mount Lawu. The values obtained in magnetic susceptibility are 47.53 ​× ​10−6 ​m³/kg to 79.41 ​× ​10−6 ​m³/kg. The results of this susceptibility measurement indicate the presence of igneous rocks resulting from pyroclastic flow. Furthermore, the vibrating sample magnetometer test showed an S−type (ferromagnetic) hysteresis curve, and the value of Mr/Ms (remanence ratio) define was below 0.5, which realized a multi-domain configuration. This ferromagnetic characteristic is attributed to the iron-based mineral (10.4%–17.1%) from the evaluation of X−Ray Fluorescence. The magnetite mineral confirmed in the X-Ray Diffractometer test is the largest source of magnetism in the sample. [ABSTRACT FROM AUTHOR]

This paper considers the results of the mineralogical and chemical study of sandstones and U–Pb isotope dating of detrital zircons from the Paleozoic–Early Mesozoic deposits of the Laoeling–Grodekovo terrane in western Primorye. It is shown that the sandstones of different age of the terrane differ markedly in their mineralogical and geochemical parameters and, hence, were derived from different sources. The sandstones of the Kordonka Formation are made up of fragments of basic and intermediate volcanic rocks of the oceanic island arc, as well as igneous and sedimentary rock associations of the oceanic island-arc basement. Eroded stable cratons and uplifted blocks representing crystalline basement inliers that are either flanked by rift zones or occurring along transform faults exerted a strong effect on the accumulation of sandstones of the Reshetnikovka, Barabash and Mangugai formations. The main suppliers of detritus were felsic igneous rocks with minor input from ancient sedimentary rocks. The rift margins and the eroded ensialic arc provided clastic material for the rocks of the Talmi Formation. The U–Pb geochronological studies of detrital zircons made it possible to constrain the age and possible position of igneous complexes that supplied clastic material to the sedimentary basins of the terrane. The sandstones were found to contain detrital zircons with concordant ages from 2553 to 205 Ma, which are dominated by Paleozoic zircons divided into several age groups. The zircons of Precambrian and Triassic ages are far fewer. In general, the revealed age ranges of detrital zircons from sandstones of the Laoeling–Grodekovo terrane agree fairly well with the known stages of granitoid magmatism in the eastern part of the Central Asian Orogenic Belt. [ABSTRACT FROM AUTHOR]

The assembly and break-up of supercontinents have been hot research topics in international earth sciences because they represent a breakthrough in reconstructing the history of continental evolution and deepening the theory of plate tectonics, which is of indispensable importance to the development of earth sciences. With the continuous enrichment of paleomagnetic, paleontological, chronological, and geochemical data in the last two decades, the evolution of the supercontinent from Columbia to Rodinia has gradually gained unified understanding, and the reconstruction of the major plates within the supercontinent has basically been constrained. In contrast, the reconstruction of microplates, such as South China, Tarim, and Kabul, is controversial and has now become a popular topic and frontier area of supercontinent reconstruction. Hainan lies at the southern tip of South China, and a few Proterozoic units are exposed on the island. At present, Hainan is often taken as a part of the Cathaysia Block. However, due to the lack of exposed Mesoproterozoic igneous and supercrustal rocks in Cathaysia, the reconstruction model of the Cathaysia Block and even the South China Craton based solely on Mesoproterozoic units in Hainan are distinct from those based on units in the Yangtze Block and younger Proterozoic units within the Cathaysia Block, which makes the paleoposition of the South China Craton controversial. In this paper, we provide new detrital zircon U–Pb age data for the Baoban Complex, Hainan, together with the available data to comment on the affinities between Hainan and the Yangtze and Cathaysia Blocks in the Proterozoic, and on this basis, we can reconstruct the South China Craton within the Proterozoic supercontinents. [ABSTRACT FROM AUTHOR]

The formation of metamorphic zircon after baddeleyite is a well-known reaction that can be used to date the metamorphism of igneous silica-undersaturated rocks. By contrast, metamorphic minerals formed after igneous zirconolite have rarely been reported. In this paper, we document metamorphic titanite + zircon pseudomorphs formed from the metamorphic breakdown of igneous zirconolite in syenodiorite and syenite, in the southeastern Sveconorwegian Province, Sweden. Water-rich fluid influx during tectonometamorphism in epidote–amphibolite-facies metamorphic conditions caused the release of silica during a metamorphic reaction involving igneous feldspar and pyroxene and the simultaneous breakdown of igneous Zr-bearing phases. Typical titanite + zircon intergrowths are elongated or platy titanite crystals speckled with tiny inclusions of zircon. Most intergrowths are smaller than 15 µ m; some are subrounded in shape. Locally, bead-like grains of titanite and zircon are intergrown with silicate minerals. The precursor igneous zirconolite was found preserved only in a sample of near-pristine igneous syenodiorite, as remnant grains of mainly < 2 µ m in size. Two somewhat larger crystals, 8 and 12 µ m, allowed semiquantitative confirmation using microprobe analysis. Analogous with zircon pseudomorphs after baddeleyite, titanite + zircon pseudomorphs after zirconolite potentially offer dating of the metamorphic reaction, although the small size of the crystals makes dating with today's techniques challenging. The scarcity of reports of zirconolite and pseudomorphs reflects that they are either rare or possibly overlooked. [ABSTRACT FROM AUTHOR]

The East Kunlun Orogenic Belt is located in the western part of the Central Orogenic Belt of China, with a large number of Triassic igneous rocks parallel to the Paleo-Tethys ophiolite belt, which provides a large amount of geological information for the tectonic evolution of the Paleo-Tethys Ocean. The granitoids studied in this paper are located in the Ela Mountain area in the eastern part of the East Kunlun Orogenic Belt. Zircon U-Pb dating results show that these different types of granitoids were crystallized in the Triassic. The 247.5 Ma porphyritic granites from Zairiri (ZRR) displayed calc-alkaline I-type granite affinities, with the zircon εHf(t) values being mainly positive (−0.5 to + 3.8, TDM2 of 1309–1031 Ma), indicating that they are derived from the partial melting of the juvenile crust and mixed with ancient crustal components. The 236.8 Ma Henqionggou (HQG) granodiorites and 237.5 Ma Daheba (DHB) granodiorites are high-K calc-alkaline I-type granite, and both have mafic microgranular enclaves (MMEs), showing higher and more varied Mg# (39.73–62.73), combined with their negative Hf isotopes (εHf(t) = −2.6 to −1.6, TDM2 = 1430–1369 Ma), suggesting that their primary magmas were the products of partial melting of the Mesoproterozoic lower crust that mixed with mantle-derived rocks. The 236.4 Ma DHB porphyritic diorites showed characteristics of high-K calc-alkaline I-type granitoids, with moderate SiO2 contents, medium Mg# values (40.41–40.65), with the Hf isotopes (εHf(t) = −2.9 to −0.5; TDM2 = 1451–1298 Ma) indistinguishably relative to contemporaneous host granodiorites and MMEs. The petrographic and geochemical characteristics indicate that the porphyritic diorites are the product of well-mixed magma derived from the Mesoproterozoic lower crust and lithospheric mantle. Based on the results of this paper and previous data, the chronology framework of Late Permian–Triassic magmatic rocks in the eastern part of the East Kunlun Orogenic Belt was constructed, and the magmatic activities in this area were divided into three peak periods, with each peak representing an extensional event in a particular tectonic setting, for example, P1 (slab roll-back in subduction period; 254–246 Ma), P2 (slab break-off in transition period of subduction and collision; 244–232 Ma), P3 (delamination after collision; 230–218 Ma). [ABSTRACT FROM AUTHOR]

This paper presents a complete map of the Mesozoic volcanic-plutonic complexes in the Taiwan Strait and its adjacent areas in terms of seismic profiles, ages, geochemistry, isotopic systematics, and published data. Two periods of igneous activity in the Taiwan Strait can be distinguished by seismic profiles: Jurassic (200.4–148.2 Ma); and Latest Jurassic/Cretaceous to Maastrichtian (144–66 Ma), of which the Cretaceous is the best preserved and could possibly be the most widespread. Mesozoic magmatic activity with the NE-striking distribution was migrating southeastward (oceanward). LA-MC-ICPMS zircon U – Pb dating yields the age data of 109.5 ± 0.4 Ma for PTDH1 granodiorite and 92.6 ± 0.4 Ma for PTDH4 rhyolite in the Taiwan Strait, respectively. The 581.66-m-thick Upper Jurassic volcanic rocks of the Chuan2 well are the thickest Mesozoic igneous rocks in the Taiwan Strait. The petrogenetic discrimination diagram of the Cretaceous volcanic-plutonic complexes along the coast of South China and the Taiwan Strait generally is belonging to volcanic arc or intraplate type calc-alkaline rock series. The high potassium calc-alkaline rock series of the Cretaceous volcanic-plutonic complexes that is most widely distributed in the coastal areas of South China and the Taiwan Strait. They are controlled by the subduction of the Palaeo-Pacific domain. [ABSTRACT FROM AUTHOR]

Abstract—The paper presents the results of rock magnetic studies and relative paleointensity determinations from sediments of Lake Shira, Khakassia. Carrier minerals of natural remanent magnetization (NRM) were identified through hysteresis loop parameter measurements, thermomagnetic and X-ray diffraction (XRD) analyses. The sediment age was determined by radiocarbon dating; according to age estimates, the studied sediment sequence covers approximately the past 9100 years. To obtain high-quality relative paleointensity results, the determinations were made on linear segments of the pseudo-Arai‒Nagata diagrams. The quality was assessed by the criteria of the number of points in the calculations of slope, quality criterion (q), NRM fraction destroyed in the paleointensity determination interval, and relative paleointensity determination error (σ). According to the rock magnetic studies and XRD analysis, the magnetic carriers are mainly single-domain (SD) and pseudo-single-domain (PSD) magnetite and hematite. The comparison of the obtained relative paleointensity data with model paleointensities calculated for the Shira coordinates from the various models (CALS10K.1b (Korte et al., 2011), PFM9k.1 (Nilsson et al., 2014), HFM.OL1.AL1, CALS10k.2 ARCH10k.1 (Constable et al., 2016)), with absolute paleointensities and with the collection of results from the studies of sedimentary and igneous rocks and archaeomagnetic objects has shown that these data are in good agreement and share common trends. This provides grounds for applying this approach to paleointensity determination from bottom sediments of modern lakes using the pseudo-Thellier method. [ABSTRACT FROM AUTHOR]

The Jurassic igneous rocks on Sumatra Island are important for investigating the Mesotethyan evolution and regional correlation in Southeast Asia. This paper presents new laser ablation-multicollector-inductively coupled plasma-mass spectrometry zircon U-Pb-Hf geochronological and isotopic, whole-rock elemental, and Sr-Nd isotopic data for the newly identified Glebruk dolerite and andesite in North Sumatra. New zircon dating results suggest that these mafic-intermediate volcanic rocks, with ages of 150-146 Ma, were formed during the Late Jurassic. The Glebruk dolerite and andesite belong to the calc-alkaline series, are enriched in the light rare earth elements, and exhibit depletion in Nb, Ta, and Ti. Thus, they resemble arc-like volcanic rocks. They have low (87Sr/86Sr)i ratios of 0.7038-0.7048 and strong positive eNd(t) and eHf(t) values of +6.4 to +7.5 and +4.8 to +18.6, respectively. Their geochemical signatures suggest that these Late Jurassic volcanic rocks were derived from a depleted mantle wedge that was metasomatized by the slab-derived melts. The Glebruk volcanic rocks were formed in a continental arc setting in response to the Late Jurassic northward subduction of the Woyla Ocean beneath West Sumatra. Our results and regional geological observations suggest that the Mesotethyan subduction-related igneous rocks could extend from South Qiangtang through West Yunnan to North Sumatra. The Woyla Ocean could represent the southern extension of the Mesotethyan Ocean. [ABSTRACT FROM AUTHOR]

Detrital single‐grain zircon U–Pb geochronology is a powerful tool for provenance studies if information on the source rocks is available. This paper proposes a new source‐rock classification tool that uses the degree of annealing of radiation damage in detrital zircon; the annealing is expressed by the relationship between the width (full‐width at half‐maximum; FWHM) of the v3[SiO4] Raman band at ~1008 cm−1 and the calculated α‐dose. The host rocks of the zircons are classified into three types according to their emplacement process and/or thermal history: volcanic and rapidly cooled plutonic and high‐grade metamorphic rocks (type 1); rocks with hydrothermal zircons (type 2); slowly cooled igneous and metamorphic rocks (type 3). We construct a naive Bayes prediction model by training it with a collection of zircons of known types. The unknown zircons are assigned a probability of derivation from a specific host‐rock type. This classification scheme is best used as an accessory tool in provenance studies that apply detrital zircon U–Pb geochronology. [ABSTRACT FROM AUTHOR]

Eocene igneous rocks along the Gangdese belt in southern Tibetan Plateau are important for understanding the India–Eurasia collision and Tibetan Plateau uplift. These magmatic rocks are widely considered to be related to roll-back or break-off of the Neotethyan slab during northward subduction. However, Eocene rhyolites in the northwestern Gangdese belt (SW Qiangtang margin) do not fit either the rollback or breakoff models. This paper investigates these Early Eocene lavas and compares them with contemporaneous igneous rocks along the Gangdese belt via detailed field observations, petrology, zircon geochronology, zircon Lu–Hf isotopes and whole-rock geochemistry. These felsic lavas form large outcrops in western Tibet and have two zircon U–Pb ages of 54.71 ± 0.14 Ma and 54.74 ± 0.27 Ma. They have high SiO2 and alkali contents, FeO*/MgO, and Ga/Al ratios as well as strongly negative Eu anomalies and slightly positive zircon εHf(t) values (+2.5 to +4.4). Both Ti-in-zircon and Zr saturation thermometers confirm high magmatic temperatures (~900°C). They are ferroan, A-type rhyolites. Furthermore, the distinctive low εHf(t) values imply that these rhyolites are likely partial melting products of the southwestern Qiangtang Terrane. The lithosphere in this region undergone long-term shortening and thickening since 80–95 Ma. Pre-thickened lithosphere may be a prerequisite for the Early Eocene delamination, and the simultaneous inducement is a far-field tectonic effect from the India–Eurasia collision. We suggest that: (1) India collided with Eurasia before 55 Ma and triggered delamination to form the Shiquanhe A-type rhyolites on the southwestern Qiangtang margin thereafter; and (2) tectonic stresses related to India–Eurasia collision during the Eocene were transmitted efficiently over large distances. [ABSTRACT FROM AUTHOR]

The paper presents petrographic, mineralogical, and geochemical data on dunites, pyroxenites, peridotites, and gabbroids of the Kamchatsky Mys ophiolite. These data were acquired to distinguish cogenetic assemblages of igneous rocks, gain an insight into their geodynamic settings, and test various criteria of genetic links between the different magmatic rocks of ophiolites. The ultramafic and mafic rocks are shown to belong to two series, which differ in the compositions of the primary minerals, bulk rocks, and estimated trapped melts. The rocks of these series are found out to have been produced by geochemically different melts in different geodynamic settings, and during different episodes of mantle magmatism. The rocks of the high-Ti series (gabbro of the Olenegorsk massif, dunite and melanogabbro xenoliths in them, and vein gabbro in these xenoliths) crystallized from N-MORB melts in an oceanic spreading center. The rocks of the low-Ti series (dunite, pyroxenite, and gabbro veins in the residual spinel peridotites of the Mount Soldatskaya massif, as well as pyroxenite, peridotite, and gabbro alluvium and diluvium in the central and western parts of the peninsula) crystallized from water-rich boninite melts in relation to initial subduction magmatism. Taken into account the absence of boninite lavas from the Kamchatsky Mys ophiolite, the plutonic ultramafic rocks (including the rocks of the veins) might be the only evidence of subduction boninitic magmatism in the ophiolites. It was demonstrated that conclusions about the geodynamic settings of plutonic ultramafic and mafic rocks and recognition of cogenetic relations of these rocks with spatially associated basalts are more reliable when derived from the compositions of the trapped melts, which are estimated from their bulk geochemistry and primary mineral compositions, than when they are based on the mineral compositions only. [ABSTRACT FROM AUTHOR]

The X oilfield is the first sandstone reservoir under the influence of igneous rock, which is discovered and put into development in Bohai Sea. Compared with the conventional sandstone reservoir, the oilfield is affected by magmatic activity, the reservoir heterogeneity is serious and the micro pore structure is complex, which results in the poor correlation between mobility calculated by traditional methods and specific oil production index. In order to predict oil well productivity and guide oilfield well location deployment, the quantitative transformation of sandstone reservoir affected by igneous rock is studied in this paper. According to the distribution mode of igneous rock in the reservoir, a permeability model of quantitative characterization for sandstone reservoir permeability is established, in which the influences of heat conduction, reservoir skeleton deformation and stress sensitivity are considered, and then the igneous rock influence on the ground temperature field of surrounding rock is simulated by ANSYS software. According to the relationship between porosity and permeability, the quantitative transformation effect of igneous rock thermal effect on sandstone reservoir is quantitatively characterized. The reservoir temperature field variation law, different baking types and igneous rock thickness influence on the transformation degree of sandstone reservoir are analyzed. Finally, the X oilfield is taken as an example to verify the research method, and the second batch of wells location deployment is successfully guided. The results show that the thermal effect of igneous rock reduces the permeability of reservoir, and the temperature of reservoir increases first and then decreases with time, the rising speed is faster than the falling speed, with the increase in distance from igneous rock, the maximum temperature of reservoir shows a downward trend, in the case of baking on both sides, the heat of igneous rock is greater, which makes the temperature of surrounding reservoir rise more, and the transformation effect on reservoir is more obvious. The influence range of igneous rock thickness on permeability is basically the same, but with the increase in thickness, igneous rock has a greater influence on surrounding rock. The research example of the X oilfield shows that the existence of igneous rock reduces the reservoir physical properties of development wells by 1.2–5.9 times. The correlation between igneous rock physical properties and specific oil production index corrected by this method can reach 0.9478. By avoiding igneous rock, the comparative production of the second batch of development wells is 1.5 times that of the first batch of development wells. [ABSTRACT FROM AUTHOR]

The heterogeneity of reservoir micro-pores and the multifractal nature of their geometric morphology control the migration of oil and gas in porous media and affect the characteristics of oil and gas accumulation and productivity at the macro-scale. In this paper, based on high-resolution x-ray microscope computer tomography (XCT), combined with fractal and multifractal analysis, the microscopic pore-throat characteristics of 12 igneous rocks cylindrical core igneous rocks in the Huanghua Depression, China, were analyzed. A new DW interpretation chart (D = box-counting dimension; W = width of multifractal spectrum) based on fractal and multifractal analysis is presented to characterize the complexity of pore-throats in igneous rocks and to describe the influence of secondary transformation behavior on pore-throat microstructure. We found that microscopic pore-throat structures of different types of igneous rocks have significantly different fractal and multifractal characteristics. In addition, the complexity of pore-throat microstructure is indicative of the evolution dynamics of reservoir performance. The permeability of igneous rocks with simple microscopic pore-throat structures and strong heterogeneity is more sensitive to changes in porosity, and it is beneficial to the formation of high permeability oil–gas reservoirs. These results show the effect of igneous rock microstructure on macro-reservoirs and will provide a new perspective for the in-depth study of complex igneous oil–gas reservoirs. [ABSTRACT FROM AUTHOR]

The article reports that the current issue of the jounal is on New Zealand's acid rock drainage research. The journal will publish more papers and more pages than ever before. They also have more manuscripts submitted, reviewed, edited, and electronically published than ever. The journal have over 30 papers that have been published on-line.

Copyright of Tunel is the property of Ceska Tunelarska Asociace ITA-AITES, z.s and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, a novelty-free software to assess an efficient CIPW Norm (± 0.006 wt.% in differences between input and output data) is presented. The package is available in the official repository for user-contributed R packages (CRAN: Comprehensive R Archive Network). The software is able to handle big data sets and considers minor and trace element compositions. The algorithm can calculate odd minerals in igneous rocks, such as cancrinite and calcite, adjust the Fe+3/Fe+2 ratio in different standard approaches, and recalculate the compositions of the rocks in an anhydrous basis (100 ± 0.003 wt.% volatile-free adjusted). Furthermore, the package calculates several petrological parameters, and the graphical outputs are displayed following IUGS scheme standards. The prime aspect of shinyNORRRM is the symbiosis of native R functions with the R package's shiny (Web Application Framework for R) to run the norm in a user-friendly interface. shinyNORRRM can be executed in any operating system and requires no previous programming knowledge, thus promising to be the universal computational program in this matter. The output data are printed in the standard comma-separated values (*.csv) format, which is highly compatible with general spreadsheet editors. In this work, the algorithm of our program is validated using already compiled whole-rock geochemical databases. [ABSTRACT FROM AUTHOR]

The present paper focuses on the geology, petrography, and geochemistry of the well-known Dokhan volcanics encountered in the northern part of the Eastern Desert of Egypt. The basalts, andesites, rhyolites, and agglomerates exposed at the Makhar Seal (flood plain) as well as Wadi Abu Zoghot, Wadi El-Ghafiryia, Wadi Al-Radah Luman, Wadi Al-Ushsh, Wadi Umm Sidrah, and Gabal Ghuwayrib are herein examined as sources of coarse aggregate in concrete mixes. A representative total of 28 samples—collected from different Dokhan volcanics—was studied in terms of field geology, petrography, and geochemistry wherein a variety of experiments related to construction material validation apply. The petrographic examination revealed that the studied Dokhan volcanics consist of basic, intermediate, and acidic volcanic igneous rocks. These rocks are represented through basalts, andesites, imperial porphyry, dacites, rhyodacites, rhyolites, and their pyroclastics. Furthermore, the applied geochemical analysis indicated that the studied Dokhan volcanics are alkaline to sub-alkaline, calc-alkaline and classified as basalts, basaltic andesites, andesites, trachyandesites, trachydacites, trachytes, and rhyolites, indicating an initial potential as aggregate for concrete mixes. Finally, the results obtained from incorporating Dokhan volcanics as aggregates in concrete mixes demonstrated a significant improvement in regard to the properties of the comprising concrete mixes. Herein, a higher compressive strength was witnessed after 28 days for Dokhan volcanic concrete, when compared to concrete comprising dolomite aggregate, amounting to an average increase that exceeded 36%. [ABSTRACT FROM AUTHOR]

• Unification of Lomnitz type creep laws has been achieved. • A novel generalized fractional calculus is well-defined. • Physical interpretations of such generalized fractional constitutive relation are also provided. This paper is dedicated to achieving the unification of the scattered Lomnitz type creep laws. Thereupon, a novel generalized fractional calculus, that is, Katugampola-like fractional calculus is well-defined and employed as an effective tool, along with some fundamental qualities as by-products. By virtue of the hereditary theory of viscoelasticity and Volterra integral equation method, a compatible stress-strain relation with memory effects and time-varying viscosity established results in a unified Lomnitz creep law. Then, a comparative analysis on the creep function and relaxation function inherited from the unified Lomnitz creep law is exhibited via reasoning and numerical simulation. Besides, physical interpretation of such unified Lomnitz creep law is also provided with the aid of the modified spring-dashpot model of Maxwell type. Results carried out in this paper might provide a full characterization of the creep of igneous rocks to meet some special theoretical and experimental requirements. [ABSTRACT FROM AUTHOR]