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The uplift rates calculated for Tasmania by Shin (2013) are not supported by the data presented in his paper. The OSL ages obtained indicate a Last Glacial age and fluvial origin for many of the deposits analysed. OSL ages obtained on sediments at Mary Ann Bay in southern Tasmania confirm recent research indicating a Last Glacial age and aeolian deposition of the sands rather than marine (Last Interglacial) deposition. Anomalously high uplift rates for southern Tasmania, proposed by earlier researchers and Shin (2013), are discounted. [ABSTRACT FROM AUTHOR]

One was the Planetary Boundaries framework, introduced by Johan Rockström and colleagues in 2009, which aims to provide a natural-science based framework for describing a Holocene-like state of the Earth System and the intrinsic boundaries of the Earth System that should not be transgressed if such a stable state is to be maintained (Rockström et al. [10]). Introducing the Anthropocene: The human epoch: This article belongs to Ambio's 50th Anniversary Collection. The other is the polycentric governance systems approach introduced by the late Elinor Ostrom ([9]), which, in the context of the S et al. paper, was proposed as a more appropriate governance system for the Anthropocene than the present governance systems that are driving us deeper towards a planetary crisis. The SCM paper foreshadowed the debate on the start date for the Anthropocene, which became prominent from 2009 with the formation then of the Anthropocene Working Group to explore the Anthropocene as a potential new interval in the Geologic Time Scale (AWG [1]). [Extracted from the article]

The paper presents new isotopic U–Pb data (LA-ICP-MS method) of zircon from the main types of intrusive rocks at the Kuru-Tegerek gold-copper-molybdenum skarn deposit situated in the Chatkal segment of the Middle Tien Shan. This and other gold, copper, tungsten and molybdenum deposits are parts of the extended Late Paleozoic metallogenic belt of Tien Shan. The concordant isotopic U–Pb values obtained for zircon autocrysts from the rocks of sequential intrusive phases span over the interval from approximately 323 to 311 Ma. This interval comprises the crystallization of gabbro-diorite (from 323.5 ± 2.5 Ma to 323.2 ± 6.8 Ma) and tonalite (from 321.4 ± 3.8 Ma to 311 ± 3.8 Ma). The age dates obtained for these zircon autocrysts correspond to the emplacement of these moderate-potassic intrusions in the Late Carboniferous and are almost coincident with the isotopic dates previously known for the high-potassic intrusions of the porphyry Cu–Au–Mo deposits of the Almalyk mineralized cluster (Kurama segment of the Middle Tien Shan), which were also emplaced in the Late Carboniferous (about 330–310 Ma). This corresponds to the subduction tectonic regime occurred in this region in relation to the steep-dipping (in the Kurama segment) or flat (in the Chatkal segment) subduction of a tectonic plate toward the north, under the structures of the Kazakhstan–North Tien Shan continental massif and accreted segments of the Middle Tien Shan. The intrusive rocks studied at the Kuru-Tegerek deposit contain also zircon xenocrysts (including these in the core of complex crystals) with the isotopic U–Pb age of some 1.9–2.1 Ga. These dates are in agreement with the age of metamorphic rocks in the Tarim craton basement and indicate the presence of the ancient continental crust in this segment of the Middle Tien Shan. [ABSTRACT FROM AUTHOR]

This large and relatively poorly studied part of the Karelian craton was cloaked in many geological mysteries, into which Vyacheslav Stepanovich and Viktoria Vladimirovna delved when working at the Institute of Geology of the Karelian Research Center, Academy of Sciences of the Soviet Union (and then Russia). In the year of 2020, Yana Vyacheslavovna Bychkova (nee Kulikova), Viktoria Vladimirovna Kulikova, and Vyacheslav Stepanovich Kulikov, a family of geologists, passed away. Vyacheslav Stepanovich Kulikov, Viktoria Vladimirovna Kulikova, and Yana Vyacheslavovna Bychkova (Kulikova). [Extracted from the article]

Speleothems are unique archives of information on climate, geomagnetism, and environmental conditions of the past, and have been successfully used for paleoclimatic and paleomagnetic studies in the last two decades. The uniqueness of these geological objects lies in the peculiarities of their formation and preservation of a wide range of geochemical, geological and geophysical proxies, and, most importantly, in the ability to obtain time series of the corresponding characteristics in an unprecedentedly accurate resolution using isotope-geochronological dating methods and incremental chronology. This paper presents the first results of dating the Vor speleothem from the Vorontsovskaya Cave (Krasnodar region), which preserved a record of the geomagnetic excursion, obtained by 230Th/U α-spectrometry, 14C dating, and incremental chronology. Such studies have been carried out in Russia for the first time. Despite the limitations of using the methods of isotope geochronology, it was possible to obtain an upper limit on the age of the excursion, which probably occurred no earlier than 5500–6000 years ago. By the method of incremental chronology, the duration of the main phase of the excursion Vor – 871 ± 16 years – was determined with great accuracy. [ABSTRACT FROM AUTHOR]

Within any scientific disciplines, a large amount of data are buried within various literature depositories and archives, making it difficult to manually extract useful information from the datum swamps. The machine-learning extraction of data therefore is necessary for the big-data-based studies. Here, we develop a new text-mining technique to reconstruct the global database of the Precambrian to Recent stromatolites, providing better understanding of secular changes of stromatolites though geological time. The step-by-step data extraction process is described as below. First, the PDF documents of stromatolite-containing literatures were collected, and converted into text formation. Second, a glossary and tag-labeling system using NLP (Natural Language Processing) software was employed to search for all possible candidate pairs from each sentence within the papers collected here. Third, each candidate pair and features were represented as a factor graph model using a series of heuristic procedures to score the weights of each pair feature. Occurrence data of stromatolites versus stratigraphical units (abbreviated as Strata), facies types, locations, and age worldwide were extracted from literatures, respectively, and their extraction accuracies are 92%/464, 87%/778, 92%/846, and 93%/405 from 3 750 scientific abstracts, respectively, and are 90%/1 734, 86%/2 869, 90%/2 055 and 91%/857 from 11 932 papers, respectively. A total of 10 072 unique datum items were identified. The newly obtained stromatolite dataset demonstrates that their stratigraphical occurrences reached a pronounced peak during the Proterozoic (2 500–541 Ma), followed by a distinct fall during the Early Phanerozoic, and overall fluctuations through the Phanerozoic (541–0 Ma). Globally, seven stromatolite hotspots were identified from the new dataset, including western United States, eastern United States, western Europe, India, South Africa, northern China, and southern China. The proportional occurrences of inland aquatic stromatolites remain rather low (∼ 20%) in comparison to marine stromatolites from the Precambrian to Jurassic, and then display a significant increase (30%–70%) from the Cretaceous to the present. [ABSTRACT FROM AUTHOR]

A set of low-grade clastic metamorphic and carbonate rocks, and greenschists outcropping in the southwestern (SW) margin of the North China Craton (NCC), was originally classified as the Paleoproterozoic Xiong'er Group according to stratigraphic correlation. To verify the age, this paper carried out detrital zircon U–Pb LA-ICP-MS dating of low-grade clastic metamorphic rocks exposed in the Changqing area at the SW margin of the Ordos Block in the SW part of the NCC. Results from detrital zircon dating indicate that the metamorphic and carbonate rocks can be classified into the Neoproterozoic Nanhua System, which is the only Nanhua System stratum in this block so far, and it probably could provide new clues to Rodinia break-up and Snowball Earth of the NCC. The nine peak ages of the low-grade clastic metamorphic rocks reflected its relatively complex provenance, and almost all major geological events experienced by the NCC basement since the Neoarchean, but some age peaks were difficult to correspond to that of the NCC, indicating that the southwestern part of the Ordos Block was also affected by the Qinling and Qiliang orogenic belts during Nanhua System of Neoproterozoic. Combined with provenance analysis, it was revealed that the current southwest boundary of the Ordos Block was the previous southwest boundary of the Ordos Block during the Qingbaikou-Nanhua Period of the Neoproterozoic. [ABSTRACT FROM AUTHOR]

Metallogeny is the science of ore and mineral deposit formation in geological space and time. Metallogeny is interdisciplinary by nature, comprising elements of natural science disciplines such as planetology to solid state physics and chemistry, and volcanology. It is the experimental forefront of research and bold thinking, based on an ever-growing foundation of solid knowledge. Therefore, metallogeny is not a closed system of knowledge but a fast-growing assemblage of structured and unstructured information in perpetual flux. This paper intends to review its current state and trends. The latter may introduce speculation and fuzziness. Metallogeny has existed for over 100 years as a branch of Earth Science. From the discovery of plate tectonics (ca. 1950) to the end of the last century, metallogeny passed through a worldwide phase of formally published 'metallogenetic' maps. In the last decades, a rapidly growing number of scientists, digitization and splendid new tools fundamentally boosted research. More innovations may be expected by the growing use of an evolving systematic 'Geodata Science' for metallogenic research by an increasingly global human talent pool. Future requirements for metallic and mineral raw materials, especially the critical natural elements and compounds that are needed for the nascent carbon-free economy, already drive activities on stock markets and in the resource industry. State geological surveys, academia and private companies embrace the challenges. The new age requires intensified metallogenic backing. In this paper, principles of metallogeny are recalled concerning concepts and terms. A metallogenic classification of ore and mineral deposits is proposed, and the intimate relations of metallogenesis with geodynamics are sketched (ancient lid tectonics and modern plate tectonics). Metallogenic models assemble a great diversity of data that allow an ever better understanding of ore formation, foremost by illuminating the geological source-to-trap migration of ore metals, the petrogenetic and geodynamic–tectonic setting, the spatial architecture of ore deposits and the nature and precise timing of involved processes. Applied metallogeny allows companies to choose strategy and tactics for exploration investment and for planning the work. Based on comprehensive metallogenic knowledge, mineral system analysis (MSA) selects those elements of complex metallogenic models, which are detectable and can guide exploration in order to support applications such as mineral prospectivity mapping, mineral potential evaluation and targeting of detailed investigations. MSA founded on metallogenic models can be applied across whole continents, or at the scale of regional greenfield search, or in brownfields at district to camp scale. By delivering the fundamental keys for MSA, supported by unceasing innovative research, the stream of new metallogenic insights is essential for improving endowment estimates and for successful exploration. [ABSTRACT FROM AUTHOR]

The scientific question of precisely determining the northern boundary of the Qinling Orogenic Belt (QOB) with regard to the southern segment of the North China Craton (S-NCC) has been controversial and unresolved, as it is heavily covered by loess and lacks some geological evidence. In order to identify the concrete northern boundary of the QOB, this paper first reports the metabasalt discovered in the Qianhe River Basin in Northwestern China, on the foundation of petrography, mineralogy, geochronology and geochemistry analyses. Detailed regional geological survey presents that the Qianhe metabasalt (QMB) is in unconformable contact with the Mesoproterozoic Gaoshanhe Group. Moreover, there is the new laser ablation (LA) inductively coupled plasma mass spectrometry (ICP-MS) U-Pb dating for magmatic zircons that yielded a weighted mean age of 450 ± 9 Ma, revealing that the QMB occurred in the Late Ordovician rather than that in the Mesoproterozoic period as previously considered. Both major and trace elements show that the samples are characterized by the back-arc basin (BAB) basalt affinity. In addition, combined with the regional geology analysis, it stands to reason that the QMB is very similar to those of Ordovician Caotangou Group along the northern QOB (N-QOB). Accordingly, it is illuminated that the QMB belonging to the N-QOB, is more likely originated from the back-arc basin setting, and truly defines the QOB's northern boundary in this segment, which has prominent geoscientific significance for determining the tectonic boundary in the heavily loess-covered regions. [ABSTRACT FROM AUTHOR]

Conodonts, as a biotic group, next to ammonoids, pollen and spores, crustaceans and vertebrates, provide proxy clues for environment and age assessments of the rocks in which they occur. Conodonts are widely used for Triassic marine biostratigraphy. However, there are various discussions about their multielement taxonomy and evolutionary lineages (e.g., generation, speciation). Although first studies reported that most Triassic conodont species were unimembrate, studies carried out in the following years maintained that all Triassic conodonts were multimembrate. Although statistical reconstructions of a number of Triassic apparatuses were attempted, the discovery of fused clusters and natural assemblages has subsequently demonstrated that Triassic conodonts are indeed multimembrate, and all of the elements exist together in the same apparatus. The present paper aims to clarify the evolutionary relationship and array of some Lower Triassic conodonts. Columbitella dagisi n. sp. is described. [ABSTRACT FROM AUTHOR]

This paper documents the zircon U–Pb ages, whole-rock geochemistry, and Sr–Nd–Pb isotopes of the Mesozoic granites in the central part of the North Qilian Orogenic Belt to provide information on the tectonic evolution and crustal accretion process of the Qilian Orogenic Belt. Zircon U–Pb dating yields an age of 215.3 ± 3.1 Ma, indicating that the Beidaban monzogranites formed from Late Triassic. They are characterized by high contents of SiO2, Al2O3, and K2O; are slightly peraluminous (A/CNK = 1.08–1.15); and have mineralogical assemblages of primary biotite and ilmenite, illustrating that they are shoshonitic and peraluminous S-type granite. The Beidaban monzogranites have initial (87Sr/86Sr)i values ranging from 0.71456 to 0.71867 and εNd(t) values ranging from –12.9 to –8.5 with two-stage Nd model ages of 1.69–2.04 Ga, suggesting that they originated from partial melting of the Paleo-Mesoproterozoic (Longshoushan Group) continental crustal metasedimentary rocks. Initial Pb isotopic compositions (206Pb/204Pb = 19.44–21.80; 207Pb/204Pb = 15.76–15.89; 208Pb/204Pb = 39.62–41.26) and geochemical features such as high Th/Ta (9.3–67.4, 37.4 on average) and Rb/Nb (12.5–17.1) are consistent with recycled crustal components. Combined with previous geochronological and geochemical data, we suggest that the Mesozoic granites probably formed in a post-collisional tectonic setting and that the North Qilian Orogen Belt experienced comprehensive intracontinental orogenesis after the closure of the Qilian ocean. [ABSTRACT FROM AUTHOR]

The Lianhuashan metallogenic belt in Eastern Guangdong Province (South China) is the most important Sn polymetallic district in the region, hosting many medium-sized deposits such as the Tashan, Xianshuili, and Jiangxikeng. However, the metallogenic mechanism of these deposits remains hotly debated. In this paper, two types of cassiterites (Cst1 and Cst2) have been identified in the Xianshuili and Jiangxikeng Sn deposits, which are hosted in the biotite-mylonite and garnet-cordierite-muscovite blastomylonite, respectively. The euhedral Cst1 (0.50–1.8 mm) coexists with biotite, feldspar, and quartz. It is platy and zoned with a mosaic structure. The subhedral to anhedral Cst2 (0.02–0.35 mm) coexists with metamorphic minerals such as garnet and cordierite, and it is characterized by well-developed porosity and has no zonation. In-situ U-Pb dating of the Cst1 and Cst2 yielded ages of 149.5±1.0 Ma (MSWD=1.6, n=45) and 125.1±2.3 Ma (MSWD=4.5, n=43), respectively. Cst1 is most likely to be related to the intermediate-felsic magmatism that formed Gaojiping Group, whereas Cst2 has relatively high Ta, Nb, Fe, and W contents with obvious rare earth tetragroup effect, and may have formed by the late Early Cretaceous dynamic metamorphism. Results presented here, when combined with regional geology and geochemistry, led us to suggest that the Mesozoic intermediate-felsic volcanic rocks in the LMB are significantly enriched in Sn and F, with high Sn-polymetallic mineralization potential which likely have contributed to the volcanic-related Cst1. In the late Early Cretaceous period, due to the NW-dipping subduction of the paleo-Pacific plate, the intermediate-felsic volcanic rocks underwent dynamic metamorphism that led to Sn mobilization, migration, and precipitation in the regional ductile shear zones, and eventually generating Sn mineralization. We propose that areas beneath Xianshuili and Jiangxikeng have great potential for discovery of new Sn resources. Our findings likely offer practical importance to regional geological ore prospecting. [ABSTRACT FROM AUTHOR]

Spatio-temporal geological big data contain a large amount of spatial and nonspatial data. It is important to effectively manage and retrieve these existing data for geological research, and understanding the question represents the first step. This paper aims to better understand the problem to improve the retrieval efficiency. In geology, the organization of massive unstructured geological data and the discovery of implicit content based on knowledge and relationships have been realized. However, previous findings are primarily based on spatial and nonspatial dimensions, and the key words searched are often just segmented words. In geological research, the dimension of time is as important as spatial and other nonspatial dimensions. In addition, an individual user's goal may be more than a superficial representation of the problem. In this paper, we first construct the geological event ontology, organize Spatio-temporal big data with this dimension, and expand the concept of geological time. Next, based on geology knowledge, we propose spatio-temporal rules, spatial characteristics, and domain constraint rules to assess the consistency of the ontology and to maximize the relationship between the information and improvements in the efficiency of information retrieval. Then, the ontology question is extended, and the rules between this question and other ontologies are expounded to deepen the understanding of the problem. Finally, we evaluate our contribution over a real geology dataset on a knowledge-driven geologic survey information smart-service platform (GSISSP), which integrates geological thematic ontology, geological temporal ontology, and toponymy ontology. This study reveals a positive impact of the incorporation of multiple ontologies and feature rules, which is meaningful for improving accuracy and comprehensiveness. [ABSTRACT FROM AUTHOR]

The paper reports data on the age and composition of poorly studied Cretaceous clastic rocks of the Lower Amur River area, which are part of the Zhuravlevka–Amur terrane and are attributed to the Berriasian–Valanginian Komsomolsk series. U/Pb dating of detrital zircons yielded reliable dates of 99 and 90 Ma for the Gorin and Pioneer formations, respectively. Thus, a sedimentary complex with a Late Cretaceous sedimentation age was identified for the first time in the Sikhote-Alin orogenic belt based on detrital zircon geochronology. In composition and detrital zircon age distribution pattern, the studied rocks are more similar to sediments of the upper, Hauterivian–Albian part of the Zhuravlevka–Amur terrane section rather than to those of the lower, Berriasian–Valanginian part. In rocks of the Pioneer Formation, the youngest zircon population with an age of about 90 Ma makes up more than 40% of all dated grains. The main source of detrital material of this age was probably proximal andesites hosting the Mnogovershinnoe deposit and granitoids of the Nizhneamurskii Complex. The source of detritus for sediments of the ∼99 Ma Gorin Formation was probably felsic rocks from the Albian–Cenomanian igneous province of Pacific Asia. The discrepancy between the Late Cretaceous age obtained by us and the paleontologically established Berriasian–Valanginian stratigraphic age of the formations requires additional research. New data on the Late Cretaceous age of the Zhuravlevka–Amur sediments of strike-slip marginal-continental basin requires revision of the geologic evolution of the terrane and the entire Sikhote-Alin orogenic belt. [ABSTRACT FROM AUTHOR]

The Weining Beishan area of Ningxia Hui Autonomous Region is located at on the western edge of the Helanshan tectonic belt, which is a tectonic joint among Alxa Block, Ordos Block, and North Qilian orogenic belt. However, the tectonic evolution of this area remains unclear due to the lack of magmatic information. This paper conducted researches on geochronology, geochemistry, and Sr-Nd-Hf isotopes of the diorite porphyrites exposed in the Weining Beishan area. The zircon U-Pb dating yields two ages of 145.0 ± 1.1 and 146.2 ± 1.5 Ma, and the whole-rock geochemical data indicate that the diorite porphyrites are metaluminous to weakly peraluminous and high-K calc-alkaline series. The characteristics of highly initial 87Sr/86Sr ratios (0.708 16 to 0.710 47), negative εNd(t) (−8.9 to −8.4), and negative εHf(t) (−13.8 to −21.2) indicate that the diorite porphyrites originated from partial melting of the middle-lower ancient crust related to the North China Craton. Combined with the regional geology, we suggested that partial melting was triggered by a tectonic activity of deep faults cutting through the crust under the regional stress transformation from compressing to extension during the Late Jurassic–Early Cretaceous, which is probably related to the westward subduction of the Paleo-Pacific Plate. [ABSTRACT FROM AUTHOR]

Abstract—To describe secular geomagnetic variation on geological timescales, statistical models have been widely used in recent decades. Currently, the most popular among these is the TK03 model (Tauxe and Kent, 2004). As other statistical models, TK03 numerically characterizes the amplitude of secular geomagnetic variation and the shape of the distribution of paleomagnetic directions which are thought to directly reflect the directions of the geomagnetic field on the considered interval of geological time. For this purpose, three main parameters are used: the scatter Sb (or S) of the virtual geomagnetic poles, the elongation E of the distribution of paleomagnetic directions, and the elongation direction of the distribution of paleomagnetic directions. The correct use of these parameters to describe paleosecular variation requires the fulfillment of certain, sometimes rather strict conditions. These conditions for parameters Sb and E were considered in a number of previous publications, while the limits and conditions of application of have not been studied in detail so far. The results of mathematical modeling presented in this paper allow us to evaluate the stability of the calculated parameter values as a function of sampling latitude, the number of samples used to determine this parameter, the length of the time series from which this parameter is estimated, as well as the inclination shallowing and the degree of averaging if is estimated from sedimentary rocks. We also consider the extent to which the parameter can be sensitive to the presence and characteristics of the equatorial dipole component in the total geomagnetic field. [ABSTRACT FROM AUTHOR]

The paper presents results of petrographic, geochemical, mineralogical, and isotope-geochronological studies of metagabbro-dolerites of the central part of the Kara Depression, located in the middle course of the Sopcha-Yu River in the Yugorsky Peninsula, Nenets Autonomous District, Russia. Two varieties of metagabbro-dolerites are distinguished: quartz-bearing and quartz-free. The influence of an impact event on rock-forming and accessory minerals is considered. It is proved that the impact event has not modified the isotope system of zircon in the metagabbro-dolerites. The U–Pb (LA-ICP-MS) isotope–geochronological dating of the zircons gives an age of the magmatic minerals within the range of 365.3 to 390.8 Ma, which seems to correspond to the age of the massif. The weighted mean age is 375.5 ± 2.6 Ma and likely corresponds to the age of the Hengur complex. [ABSTRACT FROM AUTHOR]

The roof of coal seams are mostly soft rock with weak cementation. To further study the mechanical characteristics and deformation control scheme of the roadway with weakly cemented siltstone as roof, this paper took Linchang coal mine as the research background and adopted field investigation methods, laboratory experiments, and theoretical analysis. Using a scanning electron microscope, it is found that the weakly cemented siltstone is composed of coarse-grained minerals with a high degree of pore development. According to the analysis, the instability factors of weakly cemented siltstone roadway include the late diagenetic age of rock, the low mechanical strength of rock, and the change of surrounding rock properties by pouring water. The selection of grouting reinforcement materials was studied in detail. The test results show that cement-bonded specimens' strength is lower than that of Marithan polyurethane cement specimens in general. The combined support scheme based on grouting reinforcement is put forward. Field monitoring data show that the designed support scheme can effectively control the surrounding rock deformation of weakly cemented siltstone roadway. [ABSTRACT FROM AUTHOR]

Location of the southwestern suture zone between Yangtze and Cathaysia blocks remains a controversial issue in South China tectonic research. This paper presents new LA-ICP-MS U–Pb geochronological and Hf isotopic data of detrital zircons obtained from the Nanhua System in Yingyangguan region of northeastern Guangxi and discusses their provenance and sedimentary tectonic setting of the Nanhua System. By comparison with the recently published detrital zircon geochronological and Hf isotopic data of the coeval Nanhua System in Longsheng region of northern Guangxi along the southeastern margin of the Yangtze Block and of the Neoproterozoic strata in Cathaysia block, this study attempts to constrain the southwestern suture zone or the boundary between Yangtze and Cathaysia blocks. The Nanhua System in Yingyangguan region includes Tianzidi and Zhengyuanling formations. The U–Pb ages of 107 grains from Tianzidi Formation are peaked at 0.65–0.72 Ga, 0.72–0.80 Ga, 0.90–1.30 Ga, 1.40–2.25 Ga, and 2.35–2.94 Ga. The U–Pb ages of 106 grains from the Zhengyuanling Formation are peaked at 0.65–0.72 Ga, 0.72–0.90 Ga, 0.90–1.30 Ga, 1.40–2.10 Ga, and 2.40–2.92 Ga. Most of the U–Pb ages of detrital zircon grains cluster at 0.90–1.30 Ga, demonstrating a remarkable difference from the coeval Nanhua System in Longsheng region, and suggesting the Cathaysia Block as a major source of sediments for the Nanhua System in the Yingyangguan region. The εHf(t) values of the detrital zircon grains from the Nanhua System of the Yingyangguan region are mostly positive (0–10); they are different from those of the Longsheng region of northern Guangxi where they are mainly negative (− 10 to − 2), but similar to the Cathaysia Block (− 3 to 5). Based on the new detrital zircon U–Pb ages and Hf isotopic data, it is suggested that the southwestern suture zone or the boundary between Cathaysia and Yangtze blocks is located in the area between Yingyangguan and Longsheng area of Guangxi. [ABSTRACT FROM AUTHOR]

The Qimantag in the East Kunlun Orogenic Belt has widespread Triassic magmatic rocks that have received scant attention, with an unresolved issue relating to its petrogenesis and geodynamics. In this paper, we used zircon U–Pb–Hf isotopes and whole-rock geochemistry to trace the petrogenesis and tectonic settings of the moyite and monzogranite from the Qimantag Alananshan, East Kunlun. The moyite and monzogranite are silicic (SiO2 ~ 69.9–76.41%), highly alkali (Na2O + K2O ~ 7.29 to 8.96 wt.%), with Mg# about 10.4–30.34, indicative of a high-K calc-alkaline rock series. The rare earth element patterns diagram is right-leaning, with a negative Eu anomaly (δEu = 0.31–0.68). They are enriched in Rb, K, and light rare earth elements but depleted in Nb, Ta, and Ti, with abundant amphibole, typical of I-type granites. U–Pb on zircon constrained the emplacement of the moyite at 223.9 ± 2.6 Ma and monzogranite at 226.9 ± 2.9 Ma. The εHf(t) values range from − 2.8 to + 0.1 except for one outlier value of − 7.0, corresponding two-stage model age of 1249–1437 Ma. Our combined geochemical and isotopic results indicate that the moyite and monzogranite were derived from partial melting of the lower thicken crust with the contribution from the older basement materials. These rocks formed in a post-collision setting that is transitional between compressive collision and extension orogeny. [ABSTRACT FROM AUTHOR]

Lithium is one of the important strategic energy metals, which is in short supply in China. There are three major types of lithium deposits: brine and salt lake type, highly differentiated granite or pegmatite type, and carbonate-clay type. In recent years, some new types of lithium deposits have also begun to receive great attention and subject recent research. There are many crypto-explosive breccia pipe type deposits in the world, including copper, gold, lead, zinc, tungsten and tin deposits, but little is known about this type of lithium deposit. This paper introduces the latest research results of the Weilasituo Sn−Li−Rb polymetallic deposit in Inner Mongolia (NE China), which occurs in the middle-southern section of the Great Xing'an Range metallogenic belt. A remarkable feature of this deposit is the coexistence of various mineralization types, including granite type Rb and Sn−Zn, hydrothermal crypto-explosive breccia pipe type Li−Rb, quartz vein type Sn−Zn and sulfide vein type Pb−Zn−Ag mineralization. Among them, hydrothermal crypto-explosive breccia pipe type Li-Rb deposit is currently very rare at home and abroad, which is likely a new type of rare metal deposit that worthy of our attention. This paper systematically summarizes the geology, alteration and mineralization, geochemistry, isotopes and geochronology of the Weilasituo deposit, and establishes a new petrogenic and metallogenic model. [ABSTRACT FROM AUTHOR]

The article discusses various papers published within the issue including an article on geochronology of carbonatites, a discussion on the close spatial and temporal association between carbonatites and large igneous provinces and an assessment of the generation of parental liquids.

This paper presents new age estimates and results obtained by the chemostratigraphic study of dolostones of the Billyakh Group, which consists of the Kotuikan and the Yusmastakh formations. The Billyakh Group forms the upper part of the Riphean section of the Anabar uplift in northern Siberia. The stepwise dissolution technique was used for the first time to determine the 87Sr/86Sr, 206Pb/204Pb, and 207Pb/204Pb isotopic ratios in dolostones. The Rb‒Sr systematics was studied by the chemical removal of about a third of the crushed sample (fraction L1) by the preliminary acid leaching in 0.2 N CH3COOH and the subsequent partial dissolution (fraction L2) of the remaining part of the sample in CH3COOH with the same concentration. The Pb‒Pb isotope systematics of dolostones was studied by the six-step dissolution of crushed samples in 0.5 N HBr. These procedures led to the removal of secondary carbonate material and greatly improved the quality of Sr chemostratigraphic and geochronological information. The initial 87Sr/86Sr ratios of the least altered carbonate material (fraction L2) of the Billyakh Group dolostones are 0.70502 ± 0.00029 in the Kotuikan Formation, 0.70519 ± 0.00026 in the lower subformation of the Yusmastakh Formation, and 0.70511 ± 0.00018 in the upper subformation of the Yusmastakh Formation. The Pb‒Pb age of early diagenesis of Kotuikan and Yusmastakh dolostones (1519 ± 18 Ma at MSWD = 1.8) was calculated from the results obtained for carbonate fractions L3–L6. Secondary carbonate fractions L1‒L2 are characterized by a Pb‒Pb age of 1466 ± 54 Ma at MSWD = 0.6. The δ13C values vary from ‒1 to ‒0.4‰ in dolostones of the Kotuikan Formation and from ‒0.4 to +0.8‰ in those of the Yusmastakh Formation (from ‒0.1 to +0.4‰ in the lower subformation and from ‒0.4 to +0.8‰ in the upper subformation). Comparison of these variations, as well as variations in the initial 87Sr/86Sr ratios in dolostones of the Kotuikan Formation and the Lower and Upper Yusmastakh subformations (0.70460‒0.70499, 0.70450‒0.70525, and 0.70462‒0.70523, respectively), does not make it possible to distinguish these units on the basis of chemostratigraphic characteristics. [ABSTRACT FROM AUTHOR]

The paper presents new petrographic and geochemical data from terrigenous rocks and first U–Pb ages of detrital zircons from sandstones of the Tekturmas zone of Junggar-Balkhash suture zone (central Kazakhstan). Petrographically and chemically the samples under study are greywacke sandstones. We performed U–Pb isotope dating of detrital zircons separated from two sandstones sampled in the northern (TK-17) and southern (TK-27) parts at the periphery of the Tekturmas zone. The distribution of U–Pb ages of zircons from sample TK-27 (northern Tekturmas zone) is unimodal with a major peak at 453 Ma. The distribution of U–Pb ages of detrital zircons from TK-17 sample (southern Tekturmas zone) has a bimodal character peaked at 510 and 450 Ma. Both samples contain a small amount of Precambrian zircons. The most probable sources of ca. 450 Ma zircons are andesitic to volcanic rocks of Tekturmas supra-subduction ophiolites. The ca. 500 Ma zircons are also low-rounded like those younger, but no igneous rocks of that age have been identified in the study area. The youngest U–Pb ages of zircons from both samples are similar (438–437 Ma), suggesting the beginning of sedimentation after the Llandovery. The greywacke composition and the poorly sorted, poorly rounded and immature characteristics of the sandstones under study and the clear major peaks of U–Pb detrital zircon ages at an extremely low amount of old zircons suggest their derivation from short-distant sources dominated by Late Cambrian-Early Ordovician and Middle-Late Ordovician supra-subduction igneous complexes. A very limited amount of oldest zircons could come from Precambrian complexes present at the periphery of both sedimentation basins. [ABSTRACT FROM AUTHOR]

The objective of this paper is to evaluate the relationship between the distributions of direct and indirect, surface geochemical indices in the selected part of the Outer Carpathians. The research included analysis of molecular composition of soil gas samples and calcite contents as well as the measurements of magnetic susceptibility and pH of soil samples. The survey contained 96 soil gas samples collected from 1.2 m depth and 96 soil samples taken from interval 0.7–0.8 m depth. The maximum concentrations of methane, total alkanes C2–C5 and total alkenes C2–C4 were: 2100, 10.43 and 0.772 ppm. The magnetic susceptibility values changed from 3.6 to 21.5 x 10–8 m3/kg. The calcium carbonate contents varied from 0.02 to 29.92 wt% and the pH values measured in soil solutions obtained changed from 4.5 to 8.3. Although the results demonstrate no correlation between the direct soil gas anomalies and the indirect geochemical indicators, the integrated profiles in Fig. 7 suggest possible haloes in the calcite/magnetic data that could be related to hydrocarbons migrating from depth. There are, however, various independent mechanisms that might control the appearance of these mineral anomalies. Secondary changes of mineral composition of soils disclosed by the indirect methods, even if controlled by hydrocarbon migration throughout geological time, might cause some closure of migration pathways, influencing the location of active hydrocarbon migration pathways. Comprehensive interpretation of the results obtained by direct and indirect methods in this paper provides another positive example helping to better understand the complicated mechanism of hydrocarbon migration and the potential usefulness of indirect methods suitable for hydrocarbon exploration. [ABSTRACT FROM AUTHOR]

The paper presents results of comprehensive studies of the rock association composing the lower zone of the northeastern part of the Monchetundra mafic massif in the Monchegorsk ore district. The zone consists of orthopyroxenite, plagioorthopyroxenite, and norite, which are variably amphibolized and host numerous gabbroid injections from the upper zone of the massif. The chemical composition of the dominant rock-forming minerals of the rocks was studied. The orthopyroxenes of the lower zone of the Monchetundra massif (LZMM) notably differs from those of the Monchegorsk pluton (Monchepluton) in containing lower aluminum concentrations because of differences in the P–T parameters of their crystallization. According to mineral geothermobarometric data, the LZMM rocks crystallized at 1200–1000°C and approximately 6 kbar, at a depth of about 20 km, whereas the Monchepluton rocks crystallized at an average temperature of 1230°C and a pressure of 3 kbar in shallow conditions. The LZMM rocks are characterized by moderate magnesium and silica contents and by elevated iron and low titanium concentrations, are enriched in the light rare earth elements (LREE) and LILE (Rb, Ba, and Sr) but are depleted by HFSE (Nb and Ta). The behavior of major components in the rocks is similar to that in analogous rocks in the bottom axial part of the Monchetundra massif, lying at its basement. Moreover, all petro- and geochemical parameters of the LZMM rocks are close to those of the analogical rocks of the Monchepluton. The paper presents new U–Pb isotope-geochronological data on individual zircon grains from the LZMM rocks. The age of the orthopyroxenite is 2496.3 ± 2.7 Ma, and that of the norite is 2500 ± 2 Ma, which indicates that these rocks crystallized simultaneously (within the error). The orthopyroxenite has an age of 2452 ± 85 Ma and positive εNd(T) = +1.7, and the model age of the protolith T(DM) is 2.76 Ga according to data on the Sm–Nd of isotopic systematics. The possible parental melt of the rocks may have been komatiite contaminated with crustal material. The obtained results indicate that the Monchetundra massif is a composite intrusion, whose lower zone is similar to the layered intrusions and the upper one is made up of rocks belonging to the gabbro–anorthosite complex. The massif was formed by at least three pulses of magmatic activity (at 2.50, 2.47, and 2.45 Ga). [ABSTRACT FROM AUTHOR]

An Erratum to this paper has been published: https://doi.org/10.1134/S1028334X2306017X [ABSTRACT FROM AUTHOR]

This paper presents the first geochemical, isotope-geochemical (Sm–Nd) and geochronological (U–Pb, LA–ICP–MS) data on acid volcanic rocks collected in the Bogdanikha River basin of the Priamursky fragment of the Nora–Sukhotino terrane in the northeastern South Mongolia–Khingan orogenic belt. In terms of the contents of rock-forming components, the studied volcanic rocks correspond to high-silica and high-alumina rhyolites. The elevated contents of alkalis, Ga, Zr, Nb, and Y, lower concentrations of Ba, Sr, Ti, and Eu, and mantle values of εNd(t) = +3.0...+3.6 allow the rhyolites from the Bogdanikha River basin to be classified as A2-type rhyolites. The concordant age of the youngest zircon population from the rhyolite, according to geochronological (U–Pb, LA—ICP–MS) studies, is 301 ± 4 Ma, which corresponds to the Late Carboniferous. Taking the geochemical features of the studied rhyolites and the existing models for the formation of the South Mongolia–Khingan orogenic belt into account, it is most likely that they formed in a collisional setting as a result of slab break-off. [ABSTRACT FROM AUTHOR]

Various ore deposits, mostly those of gold, tin, copper and mercury, are spatially and temporally associated with Mesozoic magmatic belts in the surroundings of the Kolyma–Omolon terrane in eastern Yakutia. The paper discusses the metallogenic significance of redox conditions in ore–magmatic processes with regard to the proportions of ferrous and ferric oxides in the magmatic rocks. It has been established that igneous rocks of the Main and Northern batholith belts, transverse rows (western continuation of the Kolyma loop), and small zones in the southwestern surroundings of the Main batholith belt crystallized under reducing conditions (ilmenite series). All of the tin and tungsten ore deposits and occurrences are concentrated above the intrusive zone. The ilmenite-series rocks are framed by magnetite-series rocks, which were formed under oxidizing conditions. The accumulations of chalcophile elements are associated with the magnetite-series rocks. The position of the boundary between the Mesozoic ilmenite- and magnetite-series rocks does not depend on the age of the rocks, their crystallization depths, and petrochemical composition. Zoning in the redox conditions had occurred before the formation of the igneous rocks and continued throughout the Cretaceous. [ABSTRACT FROM AUTHOR]

The Horoz granitoid and related felsic sub–volcanics located in the Inner Tauride Belt are key igneous rocks for understanding and investigating the collision and closure orogenic of the Inner Tauride suture of Neo–Tethys. This paper reports a new set of geochemistry, geochronology, and isotope (Pb–S) geochemistry data for the felsic dikes (granite porphyry, granodiorite porphyry, and quartz porphyry) and galena mineralization of Horoz granitoid. These intrusive felsic rocks yield a zircon U–Pb age of 54.74 ± 0.37 Ma, which crystallized in the early Eocene (Ypresian). The host rocks were examined under two groups and these are dike–type igneous rocks and metamorphic rocks, usually marble in character, cut by these acidic rocks. Rare earth elements (REE) and tectonomagmatic discrimination diagrams of felsic intrusive rocks collected from the surface and drillings indicate that these felsic sub–volcanic samples are formed in the volcanic arc (active continental margin) tectonic environment. The ore formations are severely controlled by pluton, dikes, structure and stratum which are lens, layered and dike-type within the fracture or contact zone of the Horoz granitoid and surrounding rocks. The primary mineralization in the study area consists of sulfide minerals consisting of pyrite, chalcopyrite, sphalerite, especially galena and neodiganite. Secondary mineralization consists of oxidized and carbonated minerals such as anglesite, cerussite, hydrozincite, and limonite together with smithsonite and furthermore Au minerals are located in limonites. This mineralization is accompanied by calcite and quartz. The mineralization is located in the karstic cavities developed due to tectonism and the forties on their edges. Sulphur and lead isotope analyses were performed on the galena mineral in order to determine the origin of the sulphur forming the ore minerals. According to the results of the analysis, δ34S values in galena samples vary between 4.7 and 7.00. The values of 206Pb/204Pb (the ratio of 206Pb from 238U to 204Pb) vary in a quite narrow range (18.998–18.563). The mineralization in Bolkar Mountains is thought to be primarily hydrothermal in origin, the mineralization that make up the mineralization are mainly related to Horoz granitoid, and they take their current position due to the oxidation and sulfurization of sulfide mineralization. [ABSTRACT FROM AUTHOR]

Detailed mapping of topography is crucial for the understanding of processes shaping the surfaces of planetary bodies. In particular, stereoscopic imagery makes a major contribution to topographic mapping and especially supports the geologic characterization of planetary surfaces. Image data provide the basis for extensive studies of the surface structure and morphology on local, regional and global scales using photogeologic information from images, the topographic information from stereo-derived digital terrain models and co-registered spectral terrain information from color images. The objective of the Psyche topography and geomorphology investigation is to derive the detailed shape of (16) Psyche to generate orthorectified image mosaics, which are needed to study the asteroids' landforms, interior structure, and the processes that have modified the surface over geologic time. In this paper we describe our approaches for producing shape models, and our plans for acquiring requested image data to quantify the expected accuracy of the results. Multi-angle images obtained by Psyche's camera will be used to create topographic models with about 15 m/pixel horizontal resolution and better than 10 m height accuracy on a global scale. This is slightly better as global imaging obtained during the Dawn mission, however, both missions yield resolutions of a few m/pixel locally. Two different techniques, stereophotogrammetry and stereophotoclinometry, are used to model the shape; these models will be merged with the gravity fields obtained by the Psyche spacecraft to produce geodetically controlled topographic models. The resulting digital topography models, together with the gravity data, will reveal the tectonic, volcanic, impact, and gradational history of Psyche, and enable co-registration of data sets to determine Psyche's geologic history. [ABSTRACT FROM AUTHOR]

The Kara-Bogaz geoblock is interpreted by many researchers as a structure underlain by the Precambrian sialic crust, incorporated in the young (epi-Hercynian) Turan Plate. The paper presents the results of a detailed study of the material composition of igneous and metamorphic rocks making up the basement of the Kara-Bogaz Arch and recovered by deep boreholes. To subdivide and correlate the sections, we employed data of geophysical borehole surveys, including all types of logging. Microscopic examination of rocks was also performed to determine their composition, genesis, and degree of postsedimentation alterations. Data on absolute ages of rocks and paleontological data were also employed. The results of the work of our predecessors have been studied and critically analyzed. It is established that there are no direct indications of the continental crust older than Paleozoic in the basement of the Near-Kara-Bogaz region. The metamorphic units of the Kara-Bogaz Arch are represented by primary sedimentary and volcanosedimentary deposits that were altered at the stage of regional greenschist metamorphism. These rocks are intruded by granitoid bodies corresponding to the final stages of Hercynian tectogenesis. In parts spatially close to intrusions, the degree of secondary alterations in metamorphic rocks increases due to the thermal effect. Amphibolites of the Kara-Bogaz Arch are metamorphosed igneous rocks, which are closely associated with primary terrigenous deposits and have undergone subsequent metamorphosis (greenschist facies regional metamorphism). Gneisses of the discussed region refer to the marginal facies of granitoid plutons that formed as a result of metasomatic reworking of the host strata (protomagmatic gneissic banding). We think that the Kara-Bogaz Arch is a Hercynian megaanticlinorium of the young platform, and this does not exclude the possibility of fragments of more ancient crust in the structure of this arch. The sedimentary–metamorphic and volcanosedimentary rocks making it up and intruded by multiple granitoid bodies are units of the active margin. [ABSTRACT FROM AUTHOR]

This paper relates the quantum-mechanical equilibrium isotopic fractionation correction to the radiocarbon dating method by Eq. 9, and also shows the significant influence of temperature on the method. It is suggested that the correction is a function of the frequencies and temperature of a specific sample and these two variables can be evaluated theoretically by the ab initio quantum calculations and experimentally by analyzing the clumped-isotope ratios in it, respectively. This paper also suggests that the C/C ratio in the atmosphere in geological time can be calculated by Eq. 10. [ABSTRACT FROM AUTHOR]

We consider existing reliable data indicate the depositional age of the uppermost sandstone (Maihar Sandstone) of the Vindhyan Supergroup to be closer to 1000 Ma. We consider the penultimate statement by Pandey et al. (2023) "... the Maihar Sandstone is deposited within the Ediacaran Period" (our italics) is erroneous. In this note, we address both the dubious geochronology and the dubious biostratigraphy called on by Pandey et al. (op. cit.), and comment on the impropriety of changing extant stratigraphy on the basis of either. [ABSTRACT FROM AUTHOR]

Аbstract: The formation of the West Kunlun Orogenic Belt, which is located at the northwest margin of the Greater Tibetan Plateau, is associated with the evolution of Proto- and Paleo-Tethys Oceans from the early-Paleozoic to the Triassic and characterized by intensive magmatism and extensive metallogenesis. This paper presents a detailed study of the LA-ICP-MS zircon U-Pb chronology, zircon Hf isotope geochemistry, and major and trace element composition of the Buziwannan granodiorite and monzogranite in the South Kunlun Terrane. The LA-ICP-MS zircon U-Pb dating shows that the two granites were emplaced in the late Triassic (231.8–226.8 Ma), and are high-K calc-alkaline I-type granodiorite and monzogranite in composition. Zircons from the Buziwannan granites have εHf(T) values ranging from –3.83 to 2.96, with corresponding two-stage Hf model ages (T(DM2)) of 1075–1505 Ma, suggesting the importance of juvenile material in the magma source. The Buziwannan granites show enrichments in LREEs, Rb, Th, U and Hf, and depletions in Sr, Nb, Ta and Eu. The contradiction between continental signature and mantle-like isotopes indicates the granites were generated by the partial melting of residual subducting slab with input of sediments. The ratios of Rb/Sr and (La/Yb)N increase from the granodiorite to monzogranite, while the Sr, Dy and Er values decrease. These data are attributed to fractional crystallization processes. Fractionation of plagioclase, hornblende and biotite produced the variations in major elements and Rb, Sr and Ba, and the distribution of REEs are mainly controlled by fractionation of hornblende and subordinately of zircon. Together with the regional geology, the data infer that the Buziwannan granites and corresponding mineralization formed in a transitional setting from syn-collision to post-collision during the Late Triassic. [ABSTRACT FROM AUTHOR]

The paper presents data on the granitoids of the Yurubchen massif, which make up the basement of the Kamov arch, Baikit uplift in the western part of the Tunguska superterrane of the Siberian craton. Rocks of the massif were recovered by drillholes from depths of 1.8–2.0 km and occupy an area of at least 400 km2. The U–Pb (SHRIMP) zircon age, geochemistry, and isotopic features of rocks of the Yurubchen massif indicate that it comprises granitoids of two groups, which are coeval but spatially separated from one another and differ in petrogenetic characteristics. The granodiorites (2562 ± 16 Ma) have εNd(T) = + 0.9 to +2.1, contain high LREE concentrations, show highly fractionated HREE patterns (GdN/YbN = 3.4–6.2), which could be formed via partial melting of an enriched mafic source with a short crustal history at a depth of at least 45 km, in equilibrium with garnet-bearing residue. In contrast to the granodiorites, the sodic and potassic leucogranites (2563 ± 10 and 2563 ± 18 Ma, respectively) with εNd(T) from –0.3 to –1.7 and less fractionated HREE patterns (GdN/YbN = 1.7–2.3) could be produced by melting a crustal source at shallower depths. Isotopic data on the rock-forming and accessory minerals point to ca. 2.40 Ga (Rb–Sr and Sm–Nd mineral isochrones) and ca. 1.87 Ga (Ar–Ar, biotite) episodes in the postmagmatic history of the Yurubchen massif. The synchronous generation of petrogenetically different granodiorites and leucogranites may be explained by postcollisional lithosphere extension at ca. 2.56 Ga, which resulted in the melting of heterogeneous crustal material of different age at various depths. The closure of the Rb–Sr and Sm–Nd systems at ca. 2.40 Ga was probably related to the termination of the evolution of the Neoarchean collisional orogen and the cooling of the Yurubchen massif to a temperature of ca. 400°C at a depth of 7–10 km. The later episode at ca. 1.87 Ga could be related to the tectonic exhumation of the Archean rocks in the western Tunguska superterrane during the development of the Paleoproterozoic Angara belt. In terms of the stabilization of the Archean continental crust, which was marked by ca. 2.56 Ga postcollisional granitoids, the Tunguska superterrane is younger than the terranes attributed to the Archaean Vaalbara and Superia supercratons but is comparable to crustal blocks in the Slavia supercraton and, perhaps, is a tectonic fragment of this youngest Neoarchean continent. [ABSTRACT FROM AUTHOR]

Reconstruction of the diagenetic evolution of reservoirs is one of the most significant tasks in oil and gas exploration and development. Assessing the accurate timing of diagenetic events is critical to better understand the process of reservoir evolution, but the isotope dating of diagenetic events is technically challenging. This paper uses three case studies in the sedimentary basins in China to demonstrate the promising application of recently developed LA-(MC)-ICPMS in-situ U-Pb geochronology. Our results show that the new U-Pb dating method provides a reliable and efficient chronological approach to determine the absolute ages of diagenetic events. For example, the U-Pb age data of the Cambrian carbonate reservoir in the Tarim Basin reveals three diagenetic events at 526±14, 515±21, and 481±4.6 Ma, respectively. It is worth noting that microscopic observations are particularly important for improving the success rate of U-Pb dating. In addition, the recent progress and future prospects in the in-situ U-Pb dating method are also discussed in this study, suggesting that this method is currently hindered by the lack of international carbonate standards for data correction. [ABSTRACT FROM AUTHOR]

Molasse basin is one of the best-preserved pieces of evidence of the Alpine orogeny. Molasse and flysch sequences deposited during the convergence between the Adriatic and the European continents recorded various geological processes. However, detailed provenance analysis of the foreland basin in the Western Alps is still in need of precise data for molasse strata. This paper provides new detrital zircon U–Pb geochronology results from five sandstone samples to constrain the provenance of the Molasse Basin in the Western Alps. The main populations in zircon age spectra correspond to the four tectonothermal events defined in the Alpine domain: the late Neoproterozoic to early Cambrian magmatic event, the pre-Variscan rifting event, the Variscan orogeny, and the Permian extensional event, respectively. Two magmatic zircons (100 ± 2 Ma and 130 ± 5 Ma) and one metamorphic zircon grain (116 ± 3 Ma) yield Cretaceous age. The metamorphic one was probably originated in the Internal zone. A contribution of the Valaisan unit as part of the source terrane is possible to account for the Cretaceous magmatic zircons. Comparing our results with published detrital zircon age data using multidimensional scaling, we infer that the Austroalpine unit was an essential provenance of the Western Alps Molasse Basin during the late Oligocene and the middle Miocene. During the middle Miocene, the deposition of the Molasse Basin was strongly influenced by the exhumation of the External Massifs and the propagation of the subalpine fold-and-thrust belt. Meanwhile, the French Massif Central was also possible to provide a limited proportion of the material for the basin. [ABSTRACT FROM AUTHOR]

Keywords: Marion Island; Clinopyroxene megacrysts; Volcanics; Geographical location EN Marion Island Clinopyroxene megacrysts Volcanics Geographical location 357 359 3 07/15/20 20200801 NES 200801 Roberts et al. ([9]) document clinopyroxene megacrysts from Marion Island, Antarctic Ocean to present evidence for a late stage shallow origin. This paper makes a valuable contribution in terms of the geochemical characteristics of the clinopyroxene megacrysts and the magmatic evolution of scoria cones on Marion Island. The Marion and Prince Edward Islands are young islands that represent the peaks of Hawaiian type shield volcanoes which has been associated with a mantle plume (McDougall et al. [7]). [Extracted from the article]

Change to rock art has been treated as an unforgiveable act in many contemporary cases; however, rock art in many parts of the world was most likely not created with the intention that it would endure for eternity unaltered. This paper highlights three ways in which the rock art creation process has been 'replicated' in the past and present. These forms of replication behaviours—of form, place, and action—are identified in the case study of the rock art of the Bronze Age and Iron Age Mongolian Altai. Additionally, examples of modern imagery that represent continuity of tradition are also presented. I argue that the cognitive processes suggested by these forms of replication have been influential in forming the rock art record, and they can be used to explore contemporary, regional worldviews. In eastern Eurasia, replication behaviours in rock art reference place-making strategies and regional cosmological traditions that see the landscape as occupied by non-human beings. The goal is to provide a constructive framework by which alteration and change can be considered innate aspects of the archaeological record, as opposed to mere vandalism, in our interpretation of prehistoric rock art. [ABSTRACT FROM AUTHOR]

The paper reports geochemical, geochronological (ID–TIMS zircon U–Pb) and isotope–geochemical (Nd, Pb) study of granitoids of the Kodar complex developed in the western part of the Aldan shield. It has been established that these rocks can be classified as postcollisional A–type rapakivi granites, which together with the mafic–ultramafic rocks of the Chinei complex compose a single magmatic association formed within 1876 ± 4–1859 ± 2 Ma. The massifs of this association are a part of the giant South Siberian magmatic belt over 2500 km in length, which was formed at the final stage (1.88–1.84 Ga) of evolution of the Paleoproterozoic orogen. Globally, this belt is the largest stitching suture, which marks the formation of the Siberian craton and its entrance into the Paleoproterozoic Nuna supercontinent. The formation of the initial magmas of the Kodar granitoids was related to the mantle–crustal interaction during the mixing of primary mafic mantle magmas or their derivatives with anatectic melts derived through partial melting of the Archean lower continental crust of the region under the thermal influence of mafic magma. The crustal component in the source clearly predominates and has a heterogeneous nature. The mantle component is mainly represented by ancient enriched mantle, with the possible contribution of the OIB–type component. [ABSTRACT FROM AUTHOR]

The paper presents results of the first geochronologic study (LA-ICP-MS zircon method) of metasedimentary rocks that host the banded iron formation (BIF) and the metarhyolites (halleflinta) of the Gimoly Group in the Kostimuksha greenstone belt,Karelian Craton. Felsic magmatism that produced the rhyolite sills and dikes was dated at 2759 ± 19–2743 ± 15 Ma. The clearly predominant group of zircons in the schists (metagraywacke) has an isotope age of 2753 ±19 Ma, and scarce zircon grains of these rocks vary in age from 3.1 to 2.8 Ga. Geochemically, zircons from metarhyolites fall into three types (1) Eu-depleted and Ce-enriched, (2) Eu- and Ce-enriched, and (3) LREE- and MREE-enriched. The zircons of geochemical types (1) and (2) are also predominant in the sediments. The morphology and structure of zircon crystals in the rhyolites and sediments are also identical. The rhyolites were thus a major source of zircons for the metagraywacke, which alternates with BIF, while the Mesoarchean rocks played a subordinate role. The BIF of the Gimoly Group in the Kostomuksha Greenstone Belt was formed simultaneously with felsic volcanism at 2760–2740 Ma. [ABSTRACT FROM AUTHOR]

The paper reports petrochemical and isotope data on the ferromanganese ores and host volcanosedimentary rocks of the Taloi–Usoi interfluve of the Ikat terrane, the Central Asian Fold Belt. Obtained data indicate that the formation of the Taloi ferromanganese mineralization was related to the explosive and volcanic activity of synsedimentation suprasubduction volcanism. The age of the volcanogenic rocks is 799 ± 3 Ma. This indicates the manifestation of Neoproterozoic (Riphean) epoch of manganese accumulation related to active continental margin setting in the Transbaikalian segment of the CAFB. [ABSTRACT FROM AUTHOR]

The paper reports major relations and trends determined in the distributions of trace elements and the Sr and Nd isotope composition of leucogranites of the Turga massif in Eastern Transbaikalia. Three varieties of the leucogranites are distinguished: porphyritic biotite granites, equigranular granites with Li-siderophyllite, and amazonite granites that make up small stocks and dikes. All of the rocks define a single Rb–Sr isochron that corresponds to an age of 134 ± 1 Ma at IR(Sr) = 0.71768 ± 22 and MSWD = 1.2, i.e., all of these rocks crystallized within a narrow age span. The porphyritic biotite granites, which are thought to be parental for the leucogranites, crystallized at lower temperatures (710–740°C) than the younger granites with Li-siderophyllite (810–850°C). Moreover, the granites with Li-siderophyllite have elevated Fe concentrations, which is reflected in that their micas are Fe-rich. The leucogranites are enriched in HFSE (270 ± 59 ppm Zr, 337 ± 93 ppm REE, 72 ± 31 ppm Th, and 16 ± 6 ppm U), which is atypical of amazonite granites in the study area. Considered together with very low Sr and low Ti and P concentrations, these compositional features are distinguishing features of A-type granites. The rare-metal granites of the Turga massif are unique in composition: being similar to amazonite granites in mineralized massifs, these rocks carry accessory minerals typical of peralkaline rocks. They contain LREE fluorides and fluorcarbonates (fluocerite, bastnaesite, and parisite), minerals of the pyrochlore and samarskite groups, and minerals of the isostructural group of REE–Y–Zr–Th–U silicate-phosphates. Our data provide grounds for classifying the rare-metal granites of the Turga massif with an unusual transitional geochemical subtype: peraluminous columbite-bearing amazonite granites of elevated alkalinity with peralkaline REE–Nb–Zr–Th–U mineralization. [ABSTRACT FROM AUTHOR]

The Uyandina–Yasachnaya volcanoplutonic belt (UYVB) is located in Northeast Asia. As one of the largest volcanic belts in the region, it extends for 900 km from the headwaters of the Kolyma River in the northwesterly direction. The Late Jurassic UYVB overlaps the folds of the Cherskii collision belt. The UYVB rocks are characterized by highly variable facies indicating the heterogeneous nature of the belt. The UYVB has been studied at the cross section of the Indigirka River. This paper reports the first data on U–Pb dating of zircons and the geochemical features of rocks. The concordant U–Pb age of volcanic rocks is 150 ± 2–152 ± 2 Ma (Kimmeridgian–Volgian of the Late Jurassic). It is concluded that the formation conditions of the volcanic rocks change upward through the section, from those typical of mature island arcs to those more typical of active continental margins. [ABSTRACT FROM AUTHOR]

The 18 papers in this Special Issue of the Journal of Paleolimnology report new records of Holocene environmental and climate change from Arctic lake sediment. At least 15 distinct physical, chemical, and biological properties were analyzed at lakes located across the North American Arctic and subarctic, and northwestern Europe. The studies are notable for their multi-proxy approach (eight present data for at least five different proxies), and for the high quality of their geochronological control. Three of the studies analyzed sediment from more than one lake to test the influence of contrasting physiographic settings on the response of proxies to the same climate forcing. The sedimentary sequences analyzed in seven studies extend beyond 11.5 cal ka, providing evidence for pronounced climate shifts that took place during the late-glacial period. Two-thirds extend beyond 8 cal ka; many of these records were interpreted in terms of the shift in temperature and moisture that occurred during the transition from the warm early to middle Holocene to the cooler late Holocene. These records contribute to the growing network of sites that is needed to reconstruct the spatial pattern of this pronounced paleoclimate transition, and to address how ocean-atmospheric circulation changed with the mean state of climate. [ABSTRACT FROM AUTHOR]

PVT properties of a hydrocarbon reservoir, in addition to estimate oil and gas in place, are required for optimum dynamic reservoir management. In carbonate reservoirs, it is more important as reservoir's fluid properties usually vary laterally or/and vertically. In this paper, summary results of a study which carried out on the reported PVT properties of reservoir 'A' are presented. Reservoir 'A' is a real oil carbonate reservoir which suffers from variation of PVT properties. The oil gravity and GOR (gas-oil ratio) in this reservoir are reported to be in the range of 23°–36° API and 300–1400 SCF/STB (Standard Cubic Feet/Stock Tank Barrel), respectively. These wide ranges of PVT properties raised questions about the accuracy and consistency of PVT laboratory test results, FBDST (Full Bore Drill Stem Test) measured data and reservoir characterization, such as effect of seismic recognized faults and the validity of laboratory PVT measurements which conducted on the reservoir fluid samples gathered from adjacent wells in one zone. So, an extensive, systematic study has been conducted on the available fluid data to check the validity of data and find out an acceptable, logical hypothesis about PVT variation across the reservoir, vertically and/or laterally. This study reveals that the reported laboratory measured PVT analysis, oil API gravity and GOR (gas oil ratio) measured in well tests campaign are valid. The PVT variation is dominantly vertical owing to compositional gravity segregation due to relatively high thickness of reservoir, about 300 m (984 ft). It is also distinguished that seismic detected faults (if exist) do not act as barriers at least at geological time. [ABSTRACT FROM AUTHOR]

Abstract—The time scale of the geomagnetic polarity is the quintessence of our knowledge about the changes in the polarity of the Earth's magnetic field in the geological past. The pattern of the Earth's magnetic field polarity reversals is relatively well known for the Cenozoic, Mesozoic, and Late Paleozoic. However, our understanding of the behavior of geomagnetic polarity in the more ancient epochs is non-systematic and fragmentary. Obtaining the reliable high-quality information for the Lower and Middle Paleozoic should become the next important step.This paper compiles the main data yielded by recent studies on magnetic stratigraphy of the Lower Paleozoic (Cambrian and Ordovician) of the Siberian Platform and other regions conducted by our team and our colleagues. The synthesis of these data allows us to propose a working model of the Early Paleozoic magnetic polarity time scale which embodies the current knowledge about the character of changes in the geomagnetic field polarity on this interval of the geological time. The process of geomagnetic field polarity reversals in the Early Paleozoic is described by the following most important characteristics: (a) the existence of a superchron of reversed polarity during a significant part of the Early and Middle Ordovician (the third Phanerozoic superchron Moyero); (b) a high (probably peaking in the Phanerozoic) frequency of the geomagnetic reversals in the Middle Cambrian; (c) a decrease in the frequency of geomagnetic reversals in Late Cambrian and Tremadocian with the approach of the superchron; (d) the presence of anomalous period in the behavior of the geomagnetic field close to the Phanerozoic/Precambrian boundary; and (e) the absence of a double superchron in the Ordovician (Algeo, 1996). [ABSTRACT FROM AUTHOR]

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