Geochemical Analyses Research Articles

Sediment source-to-sink patterns along the southeast China coast during the late Quaternary: New insights from sediment geochemistry and OSL ages in Ningde Bay

The geomorphology and environmental conditions of the southeast China coast are significantly influenced by sediment discharge from the Yangtze River, a major river located to the north. Nonetheless, the extent to which the Yangtze River affects sediment transport processes from source to sink along the southeast coast remains unclear. Our recent findings in coastal/marine deposits from the late Quaternary period (MIS5e, MIS3, and MIS1) in Ningde Bay offer new perspectives on this issue. Provenance discrimination of the late Quaternary boreholes was carried out using sediment geochemical analysis and OSL dating of fine- and medium-grained quartz. The results indicate varying provenances during sea-level fluctuation, with distal Yangtze River origins during MIS5e, MIS3, and MIS1, and a local source during MIS4. The findings also suggest that the southward transport of Yangtze sediments along the southeast China coast has occurred since MIS5e. However, OSL ages of the fine-grained quartz in the MIS3 deposit range from approximately 90 to 140 kyr, notably older than those of medium-grained quartz (40–80 kyr). This remarkable age discrepancy indicates that Yangtze-derived sediments previously deposited on the shelf of the East China Sea during MIS5 were reworked and transported southward in MIS3. This phenomenon can be elucidated by the insufficient supply of Yangtze sediments during MIS3, which could be linked to the weakened East Asian monsoon. This new source-to-sink pattern for the southeast China coast is characterized by a compensating mechanism of inner shelf old sediment in response to the inadequate supply of Yangtze sediments. This study contributes to a better understanding of the significant impacts of reduced Yangtze sediment input on its distal sedimentary systems over time.

Geochemistry of shales of middle Permian Barren Measures Formation, West Bokaro Basin, India: implications on provenance, paleodepositional and paleoclimatic conditions

Geochemical analyses of fine-grained clastic sedimentary rocks, such as shales, are significant since they portray the nature of the control factors from source to sink in a sedimentary basin, and help characterizing the heterogeneity in potential source and/or reservoir rocks. Bulk rock geochemistry (including major element oxides, trace elements and rare earth elements) of 20 shale samples from the Permian Barren Measures Formation, West Bokaro Basin, Peninsular India, is presented to decipher the provenance, paleo-weathering, paleotectonic, paleo-depositional and paleoredox conditions of the basin within the Lower Gondwana paleogeographic framework. X-ray diffraction (XRD) peaks and scanning electron microscopy (SEM) reveals an abundance of quartz, muscovite and clay minerals, viz., illite, kaolinite, etc., with less abundant feldspar and glauconite. The concentrations of the major element oxides, the trace elements and rare earth elements (REEs) of the shale samples are compared with predefined standards such as PAAS and UCC. The CIA (chemical index of alteration) and the A–CN–K values, based on the ratios of the major element oxides, signify intense chemical weathering. The ratios of Sr/Cu versus Rb/Sr and K2O/Al2O3 versus Ga/Rb, and high ΣREE values indicate a temperate paleoclimate. Ratios of the major element oxides (e.g., K2O/Na2O versus SiO2) suggest a passive tectonic setting. The Eu/Eu∗ and (Gd/Yb)n values depict predominantly post-Archean granitic and gneissic source rocks. The ratios of trace elements, viz., Th/Sc, Th/Co, Th/Cr, La/Sc and Eu/Eu∗, and the distribution pattern of the REEs (higher LREE in comparison to HREE) attest to a felsic-intermediate source from a nearby provenance. The redox sensitive trace elements, such as V and Ni, indicate a dysoxic condition that prevailed during deposition. The ratios of Fe2O3 versus MgO and Log (MgO/Al2O3) versus Log (K2O/Al2O3), and the ternary plots of Fe2O3–MgO–SiO2/Al2O3 suggest a non-marine to deltaic transitional environment. Such evidence of marine influences during the sedimentation of the Permian Barren Measures Formation confirms the fluvio-marine transgressive paleogeography inferred from sedimentological and paleontological inputs from the Gondwana Basins in Peninsular India, and opens up a scope for regional correlations of paleogeographic changes during the Middle Permian (Guadalupian) across the Gondwanaland.

Favorable Diagenesis and Pore Evolution of The Qi-2 Member Reservoir in the Hechuan-Tongnan Area

Abstract This article takes the Qi-2 member dolomite reservoir in the Hechuan-Tongnan area as the research object, and combines research methods such as drilling cores, thin section analysis, CT scanning, and geochemical analysis to deeply explore the pore structure characteristics, diagenetic characteristics, and influencing factors on pore evolution of the Qi-2 member dolomite reservoir. This results indicate that: ①The Qi-2 member should develop two types of reservoir spaces: pores and fractures. The reservoir space is mainly composed of intercrystalline dissolved pores (0.5∼5%), dissolved fractures and dissolved cavities (2∼4%). The intercrystalline pores are relatively evenly distributed, and the fractures improve the connectivity of pores. The reservoir space of the poor gas layer is mainly composed of biocast pores and intragranular dissolved pores (1∼2%), which are relatively isolated; ② The matrix pores of the Qi-2 member are relatively evenly distributed, with a radius of 200μm~600μm is the main focus. The throat radius is mainly 20μm~60μm fine throats.③According to the effect of diagenesis on pore evolution of dolomite reservoir in Qi-2 formation, it can be divided into constructive and destructive. The formation of reservoir space is mainly caused by quasi-syngenetic atmospheric fresh water erosion, and the matrix pores are mainly intercrystalline pores and intercrystalline dissolved pores. The early dolomitization is the key factor of pore preservation. The geological study of dolomite reservoir of the Qixia Formation in the Daqing exploration area has been enhanced, providing strong basis for reservoir prediction and deployment in the later stage.

A Study on the Paleoclimate and Sedimentary Environment of the Upper Kuli Formation in the Hailar Basin

Abstract The Kuli Formation in the Hailar Basin has a wide distribution range, complex and variable lithology, and oil and gas indications during field investigations, which has great research significance and value. In order to better understand the paleoclimate and sedimentary environment of the Upper Kuli Formation, this article uses three methods for the first time: heavy mineral analysis, sporopollen fossils identification, and inorganic element analysis. Based on the characteristics of heavy mineral assemblages, sporopollen fossils identification, and element analysis correspond to the five bottom layer combinations of heavy mineral analysis, analyzing their respective combination characteristics and change patterns. With a more comprehensive perspective and higher time resolution, Cross validation improves the accuracy and credibility of its inference. The results indicate that the Upper Kuli Formation can be divided into five combinations from bottom to top. The paleoclimate underwent a transition from a humid environment to a drier environment. The sedimentary environment has undergone a transition from a deep-water environment to a shallow water environment, transitioning from dynamic, rapid sedimentation, and strong terrestrial influences to a sedimentary environment dominated by more static water, chemical precipitation, and diagenesis. This study combines different geological and geochemical analysis methods to provide strong basis for inferring the paleoclimate and sedimentary environment of the Upper Kuli Formation. The research results are of great significance for interpreting geological changes such as paleoclimate change and ecosystem evolution.

Organic petrographic and geochemical insights into organic matter derived from land plants and marine algae in the Lark Formation, Danish North Sea

Climatic fluctuations from the Eocene to the Miocene highlight the importance of investigating the paleoenvironment of the latest Eocene to the Middle Miocene Lark Formation in the Danish North Sea. This study investigates immature sedimentary organic matter in the Lark Formation using 54 cuttings samples and one core sample collected from seven wells in the eastern North Sea Basin. Organic petrography and molecular geochemistry analyses were performed to determine the variations in the quantity and origin of allochthonous and autochthonous organic matter. Additionally, the study assesses the impact of climate fluctuations on marine productivity in the eastern North Sea Basin and land plant vegetation at the basin margins during the latest Eocene to the Middle Miocene.The organic matter in the Lark Formation originated from mixed sources, primarily land plants, with a secondary contribution from marine algae. This is indicated by the maceral composition and the types and abundance of aliphatic and aromatic hydrocarbon biomarker compounds. Moreover, the presence of diterpenoids (gymnosperm biomarkers) and non-hopanoid triterpenoids (angiosperm biomarkers) reveals that the allochthonous organic matter originated from conifers and angiosperms.Climatic impacts on land plants and marine algae during the latest Eocene to the Middle Miocene are revealed by several parameters: the Averaged Chain Length (ACL) of land plant waxes, the proportion of coniferous contribution (C/(C + A)), and the whole rock volume percentages of huminite, inertinite (H + I, vol%) and liptinite (L, vol%). The shifts to cooler and drier climates highlighted the cold adaptation of onshore conifers and resulted in the input of higher molecular weight waxy components into the sediments. However, under these conditions, reduced precipitation and runoff resulted in lower amounts of terrigenous organic matter supplied to the basin. Additionally, the drop in water temperature and the warm-affinity of local algae assemblage led to reduced marine productivity. Together, these factors contributed to an overall decrease in organic richness. In contrast, during shifts to warmer and more humid climates, the trend reversed. The contribution of conifers to the floral assemblage diminished, but higher amounts of terrigenous organic matter were transported to the basin due to increased precipitation and runoff. This was accompanied by warmer water temperatures, boosting the productivity of organic-walled microplankton in the marine environment and contributing to greater organic richness.

Geochemical state of small rivers of Syrym District of West Kazakhstan region (on the example of the Rivers Buldyrty, Yesenankaty, Shiderty, Olenty)

Despite the fact that small rivers are called Small, their importance in terms of ecology is high. This is because the condition of large rivers will depend on smaller rivers. The degradation of small rivers negatively affects the state, is an important and urgent task. The purpose of the study was to geochemically analyze the composition of the waters of small rivers in the Syryms district and assess their quality. Water samples were taken from each river ecological state of medium and large rivers, because they feed at the expense of these small rivers. It is easy to see that every day the waters of these rivers are receding and the banks are expanding. Currently, one of the main tasks that environmental science sets for itself is to monitor the ecological state of water bodies. In connection with the conditions of increasing anthropogenic factors, determining the ecological state of small rivers plays an important role in maintaining the composition of the natural ecosystem. Small rivers are very sensitive to anthropogenic factors and react to these factors in the opposite way. The study of the chemical composition of small river waters, as well as their ecological state, is an important and urgent task. The aim of the study is a geochemical analysis of the composition of small river waters in the Syrymsky district and an assessment of their quality. Water samples were taken from each river to determine the composition of the water quality. The cameral stage was held in the laboratory of environmental and biogeochemical testing of M. Utemisov West Kazakhstan University. Chemical analysis was carried out using the widely used methods GOST 26449.1 — 85. After analyzing the indicators of water samples taken from the research area, it was found that the maximum raual concentration level did not exceed, except for the total hardness.

Climate-driven versus anthropogenic induced erosion of the last 3000 years from an ancient lake in the Southern Phokis Plain (Desfina), Greece

The timing and causes for erosional events at the Kastrouli (Greece) archeological site – a Late Myceneaen with reuse in later periods – are presented. Two borehole sediment cores (max 6 m depth), collected from the footsteps of the settlement hill plain, were studied. Sedimentary analysis and luminescence dating techniques investigate and identify periods of soil aggradation in this record. Moreover, optically stimulated luminescence (OSL) dating confirmed the concept of an ancient lake during Kastrouli settlement times. Macroscopic overview of the stratigraphic structure for each core, included lithological and textural evaluation of the core sediments, assessments of grain size, and determination of the geochemical and mineralogical composition of the sediments. X-ray powder diffraction (XRPD), X-ray fluorescence (XRF), and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) techniques were applied for the mineralogical and geochemical analysis. OSL ages from seven sediment horizons spanned from the Ottoman period to archaic times. All lithological findings correlate with the results of the electrical tomography survey conducted in same area. Extrapolation of the Logarithmic fitting of the data back in time of prehistoric Late Mycenaean era of Kastrouli verifies a lake deeper than 10 m, with a considerable enhancement in soil aggradation of 1.2 cm/year. Attempts to dry out the area are evidenced by the hydraulic works found in two engineering sinkholes. Sedimentation changes had occurred in the local environment over the last 2500 years, and soil aggradation underwent significant fluctuations in the two studied cores. The Roman period (a wet period) and the Byzantine period experienced high aggradation rates. By contrast, soil aggradation rates in southern Phokis (Kastrouli region) have remained exceedingly low from the Ottoman era (circa 13th century) to the present. In the context of the Phokis case study, it appears that the sedimentation rates, driven by climate, have strengthened anthropogenic activities.

Petrogenesis of Metamorphic Rock in the Mukito Formation at Sorawolio Region, Bau-Bau City, Buton Island, Southeast Sulawesi Province, Indonesia

The petrogenesis study of the metamorphic rocks of the Mukito Formation was carried out in the Sorawolio area, Bau-Bau City, Buton Island, Southeast Sulawesi Province, Indonesia. This research area is included in the southern part of the Buton sheet with coordinates S 5⁰23'40.8'' and E 122⁰43'44.9''. The aim of this research is to determine the petrogenesis of metamorphic rocks which includes determining the rock type, facies, type of metamorphism and protolith. The research methods used include megascopic and microscopic analysis of rocks in the form of petrographic analysis which includes identification of mineral content and rock texture and geochemical analysis in the form of XRF tests to determine the main oxide elements in metamorphic rock samples. Data obtained from the results of petrographic analysis show that the research area consists of several types of metamorphic rock, namely serpentinite, phyllite, chlorite schist, hornblende schist and amphibolite. The metamorphic rocks in the research area are included in the greenschist facies and amphibolite facies with regional metamorphism types as well as protoliths from igneous rocks in the form of basalt rock which were formed in the tholeiitic oceanic-island tectonic environment which is a convergent complex characterized by continental origin in the magma series in the form of the tholeiitic series and calc -alkaline series.

Provenance Characteristics from the Mesozoic to Cenozoic Era and Their Implications for Basin-Mountain System Evolution in the Southwestern Junggar Basin: Insights from Field Outcrop Observations in the Tostai Area

The Mesozoic-Cenozoic formations in the southwestern Junggar Basin are a key target for oil and gas exploration. However, complex provenance conditions hinder comprehensive understanding of sedimentary reservoirs. Based on petrology and elemental geochemistry analysis of field outcrops in the Tostai area. Research was conducted on the tectonic background, sediment transport distances, compositions of parent rocks and evolutionary Characteristics of Provenance Conditions in the provenance areas. It is generally believed that there have been three notable shifts in basin-mountain relationships during this period. Initially, from the Triassic to Jurassic, the Northern Tianshan magmatic rock area predominated as the primary provenance, with decreasing basin-mountain proximity and predominantly magmatic rock sediment composition indicating near provenance. Subsequently, heightened Cretaceous tectonic activity in the Tianshan Mountains led to significant uplift of metamorphic rock regions in the Middle Tianshan Mountains, gradually becoming the provenance for the study area. This increased distance between provenance and sedimentary areas, marked by a substantial presence of metamorphic rocks in sediments indicating far provenance. Lastly, the Cenozoic Himalayan movement resulted in vigorous uplift of the magmatic rock area in the northern Tianshan Mountains, reestablishing it as the primary provenance. This minimized basin-mountain distance, leading to deposition of near-provenance transported alluvial fans, braided rivers, and predominantly magmatic rock sediments.

Paleoenvironmental conditions across the Coniacian-Santonian in the Kometan Formation, northeastern Iraq: Insights from planktonic foraminifera distribution, mineralogy and geochemistry

The paleoenvironmental conditions during the Coniacian-Santonian interval within the Kometan Formation in northeastern Iraq have been analyzed through the distribution of depth-related planktonic foraminifera in the carbonate rocks (limestone and marly limestone) of the Kometan Formation using standard washing method for soft samples and thin section method for hard samples supported by mineralogical investigations, geochemical analysis and stable isotopic δ13C and δ18O data. The findings indicate that saline marine waters and a hot, dry to semi-arid climate with low to medium oxygen conditions were conducive to deposition, which was characterized by high organic productivity due to marine transgression. The study revealed that the distribution of shallow water forms (SWF) of globular-shaped foraminifera, compared to deep water forms (DWF) of keeled-shaped genera, along with δ13C data from the late Turonian-early Campanian succession, indicated a relatively low sea level throughout the Late Turonian period. The water level began to rise in the early Coniacian, continuing gradually until the late Coniacian, when a noticeable increase in sea level was observed. This elevated sea level persisted through the early and late Santonian periods, before starting to drop. A slight marine transgression was noted at the beginning of the early Campanian period, followed by a significant drop in sea level. During the late Turonian, a subtropical climate prevailed. Temperature increased during the early to middle Coniacian, decreased slightly at the beginning of the late Coniacian, and then rose again at the end of the late Coniacian, indicating a shift from tropical to subtropical climatic conditions. Similar hot climatic conditions persisted in a tropical-subtropical climate during the early to late Santonian and early Campanian, with a relative temperature drop near the end of the early Campanian. No evidence of an oceanic anoxic event (OAE3) was found in the Kometan Formation during the late Coniacian–early Santonian period. The hypothesized event, based on biostratigraphy, facies analysis, stable isotopes, geochemical evidence, and field study, was limited to demonstrating an increase in the ratio of keeled chamber planktonic foraminifera compared to globular chamber ones. This ratio increase of the keeled chamber types is believed to result from a deepening sedimentary environment due to rising sea levels, creating organic matter-rich beds with high productivity and relatively low oxygen conditions during the Coniacian-Santonian boundary.

Spectral induced polarization of corrosion of sulfur modified Iron in sediments

Spectral induced polarization (SIP) responses are not well understood within the context of remediation applications at contaminated sites. Systematic SIP studies are needed to gain further insights into the complex electrical response of dynamic, biogeochemical states to enable the use of SIP for subsurface site characterization and remediation monitoring. Although SIP measurements on zero valent iron have been previously published, the SIP response for sulfur modified iron (SMI), a similar potential subsurface reductive amendment, has not yet been reported. Hence, the purpose of this laboratory-scale study was to evaluate SIP for nonintrusive monitoring of SMI under relevant subsurface conditions. SMI was separately mixed with silica sand or sediments from the Hanford Site (Washington, USA) and then packed into columns for geochemical and SIP analysis for up to 77 days under fully saturated conditions. SMI exhibited distinguishable phase peaks between 0.1 and 1.0 Hz, which changed in magnitude based on content and were detected as low as 0.3 wt%. In the initial days, the complex conductivity, phase maxima, and chargeability increased while the peak locations shifted to higher frequency (decreasing relaxation times), suggesting an initial increase in polarization and concurrent decrease in the length scales (potentially due to changes in particle size and mineralogy). Then, after 77 days, the phase maxima and chargeability decreased with a concurrent increase in relaxation times, suggesting that over longer periods, less polarizable phases are forming and particle size or connectivity of polarizable phases is increasing. These results demonstrated a unique SIP response to SMI transformations that might be applied to monitoring of SMI emplaced as a subsurface barrier or injected in the field.

Unraveling the polymetamorphism of calc-silicate rocks from 639 to 561 Ma in the Western Gondwana (Passo Feio Complex, Dom Feliciano Belt, South Brazil) based on U-Pb dating in titanite, apatite and zircon

Titanite is a valuable tool for studying polymetamorphism and understanding the evolution of orogenic belts as it potentially records different stages of metamorphic evolution. The combination of geochronology and Zr-in-titanite geothermometry has been widely used in petrochronology studies. However, there is ongoing debate regarding the significance of ages and temperatures obtained from titanite. Here, we conducted the first integrated titanite, zircon, and apatite UPb study, along with Zr-in-titanite geothermometry, on calc-silicate rocks from a polymetamorphic complex of the central Dom Feliciano Belt (Western Gondwana). Our aim was to investigate the impact of various metamorphic events on titanite grains. We carried out a geochronological, geochemical, and petrographic analysis of a calc-silicate sequence of the Passo Feio Complex, which was intruded by the Caçapava do Sul Granitic Complex (CSGC). The metamorphic complex experienced regional, contact, and hydrothermal metamorphism during the Neoproterozoic, but the ages and conditions of these metamorphic events remain widely debated. UPb analyses on over one hundred titanite grains from a K-feldspar-diopside schist revealed three distinct titanite populations. The older group, dated at 639 ± 3/7 Ma (2s; n = 19), was associated with the regional metamorphism event (M1), likely initiated by the primary collision of the Dom Feliciano Belt. The intermediate group exhibited an age of 596 ± 1/6 Ma (2s; n = 91). Given the presence of high-K magmatism and a carbonatite intrusion in the study area, producing zircon UPb ages around 600 Ma, this group was associated with contact metamorphism (M2), belike influenced by these intrusive igneous activities. The youngest titanite population showed an age of 566 ± 3/6 Ma (2s; n = 6), which closely aligns, within analytical error, with the age of 561 ± 1/6 Ma (2s; n = 46) obtained from UPb dating on apatite sourced from a diopside-phlogopite schist. The younger ages observed in both titanite and apatite are attributed to alterations resulting from interactions with hydrothermal fluids (M3) during the cooling phase of the CSGC. Chemical analyses conducted with an electron microprobe assessed the Zr concentrations in fifty titanite grains, examining both bright and dark zones observed in back-scattered electron images. The lowest temperature recorded among the 50 grains was 629 °C, which corresponds to dark BSE zones. In the light zones, the minimum temperature was 639 °C. While temperatures estimated using the Zr content in titanite may not correspond precisely with UPb ages, combining titanite ages with those from other accessory minerals like zircon and apatite, along with microstructural analysis, can provide a more comprehensive understanding of orogenic belt evolution.

Fault characterization and its significance on hydrocarbon migration and accumulation of western Tazhong Uplift, Tarim Basin: Insight from seismic, geochemistry, fluid inclusion and in situ U-Pb dating

Understanding the mechanisms of deep hydrocarbon accumulation is of paramount importance in the field of petroleum geology. Studying deep hydrocarbon accumulation mechanisms contributes to the development of effective reservoir management strategies and efficient extraction techniques. In this study, fluid inclusion observation, homogenization temperatures, in situ calcite U-Pb dating, geochemical analyses and seismic data were applied to investigate the hydrocarbon charging history of the western Tazhong Uplift, and the migration pathways were further analyzed to establish the history of oil and gas accumulation in the study area. The results reveal three distinct episodes of oil and gas charging processes in the western Tazhong Uplift. The first episode, determined by in situ calcite U-Pb dating bearing primary oil inclusions, occurred during the late Caledonian to early Hercynian orogeny. This episode is characterized by yellowish fluoresce color oil inclusions. The second episode involved a complex variation of the thermal maturity of oil. Mature oil, with oil inclusions preferentially fluorescing yellow-green color, was charged into the reservoirs near the Tazhong No.1 fault. Subsequently, the high mature oil characterized by blue-fluorescing oil inclusions was charged. At the same time, the mature oil migrated vertically into the reservoir away from the Tazhong No.1 fault along the strike slip faults. The third charging process is dominant by high mature oil in the Southwest of the western Tazhong Uplift, whereas the gas intrusion occurred in the area near the Shuntuoguole Low Uplift. Furthermore, the strike slip faults and reverse faults were distinguished based on the seismic profiles and coherence diagram. The intersections of strike slip faults and Tazhong No.1 fault developing more fractures served as oil and gas charging points. The oil production revealed that the strike slip faults acted as important hydrocarbon migration pathways. This study provides valuable insights into the processes of hydrocarbon accumulation and offers further evidence for deep oil exploration in the region.

Детские игровые площадки Саратова: анализ эколого-геохимической ситуации

In a modern large city, it is mandatory to have playgrounds in residential areas. The level of social well-being and well-being of urban space is also assessed by the presence of a children’s playground in each residential courtyard. However, from a city-ecological point of view, is it advisable to organize parking on boulevards, in small squares, in courtyards next to car parks? In order to understand this, the state regulatory requirements and standards for the organization of children’s playgrounds in a large industrial city were studied; The territories of playgrounds were identified, the location of which raises doubts about the correctness of their placement; a geochemical analysis of natural environments was performed – the surface layer of air, soils and soils, snowcover on the territory of playgrounds and adjacent zones. An assessment was made of the compliance of of the geochemical analysis results with existing standards for the placement of playgrounds in urban space and urban planning solutions were proposed to optimize the locations of playgrounds created contrary to existing standards.

GEOCHEMICAL ANALYSES OF EOCENE OILS IN DEEPLY BURIED SANDSTONE RESERVOIRS IN THE DONGYING DEPRESSION, BOHAI BAY BASIN, NE CHINA

We report the results of organic geochemical analyses of 19 crude oil samples from reservoir sandstones in the 4th Member of the Eocene Shahejie Formation from wells in the Minfeng Sag, Dongying Depression, Bohai Bay Basin (NE China). In addition, 42 Shahejie Formation core samples of dark‐coloured mudstones, including 28 extracts, were analysed. Geochemical data included Rock‐Eval measurements, gas chromatography, GC‐MS and diamondoid analyses.Maceral analyses showed that mudstones in the 4th Member of the Shahejie Formation (“Es4”) contain Types I and II1 kerogen. The member can be divided into upper (Es4s) and lower (Es4x) intervals. Oil‐prone Es4s rock samples have good to excellent hydrocarbon‐generating potential based on calculated initial TOC values; Rock‐Eval Tmax values indicate that they are sufficiently mature for hydrocarbon generation. Analytical results suggest that both Es4s and Es4x mudrocks are potential source rocks for oils produced at fields in the Minfeng Sag.Analysed crude oils from the Minfeng Sag were classified into three genetic groups. Group I oils are mature to highly mature and have undergone a moderate degree of thermal cracking. They are characterized by a low β‐carotane/nC25 ratio and C30 4‐methylsterane index (4MI); high values of oleanane index (oleanane /C30‐hopane), C27 diasterane/C27 regular sterane (C27Dia/C27), regular sterane/17α hopane and gammacerane/C30 hopane (G/H); and medium pristane/phytane ratios (Pr/Ph). This suggests that Group I oils are mostly derived from source rocks in the upper part of the Es4x unit which are interbedded with evaporites. Group II oils are mature and have high 4MI and Pr/Ph ratios, low oleanane index, regular sterane/17α hopane and C27Dia/C27 ratios, and mediumβ‐carotane/nC25 and G/H. These features are similar to those of Es4s source rocks, indicating their genetic correlation. Group III oils show the lowest maturity and highβ‐carotane/nC25 and regular sterane/17α hopane, and low oleanane index, Pr/Ph and 4MI. Previously‐published data indicates that oils similar to those in Group III were mainly sourced by Es4s mudstones.

Life history and ancestry of the late Upper Palaeolithic infant from Grotta delle Mura, Italy

The biological aspects of infancy within late Upper Palaeolithic populations and the role of southern refugia at the end of the Last Glacial Maximum are not yet fully understood. This study presents a multidisciplinary, high temporal resolution investigation of an Upper Palaeolithic infant from Grotta delle Mura (Apulia, southern Italy) combining palaeogenomics, dental palaeohistology, spatially-resolved geochemical analyses, direct radiocarbon dating, and traditional anthropological studies. The skeletal remains of the infant – Le Mura 1 – were directly dated to 17,320-16,910 cal BP. The results portray a biological history of the infant’s development, early life, health and death (estimated at ~72 weeks). They identify, several phenotypic traits and a potential congenital disease in the infant, the mother’s low mobility during gestation, and a high level of endogamy. Furthermore, the genomic data indicates an early spread of the Villabruna-like components along the Italian peninsula, confirming a population turnover around the time of the Last Glacial Maximum, and highlighting a general reduction in genetic variability from northern to southern Italy. Overall, Le Mura 1 contributes to our better understanding of the early stages of life and the genetic puzzle in the Italian peninsula at the end of the Last Glacial Maximum.

Cenozoic tectono-sedimentary evolution of the external rif chain (Morocco) derived from mineralogical and geochemical analysis of mudrocks

A model of the Cenozoic tectono-sedimentary evolution of the External Rif Chain (Morocco) is provided by means of the study of the mineralogical and geochemical composition of mudrocks. To date there was a lack of homogeneous data and of a complete and extensive study of the whole External Rif Zone (ERZ). Therefore, this work shows the study of the whole ERZ where the most representative stratigraphic sections have been selected. This work provides important information about the geodynamic evolution and the variations in source-area provenance related to the growing of the Rif orogenic belt. Although there is still much work to be done, this study aims to improve the knowledge of the Cenozoic tectono-sedimentary evolution of the entire western ERZ with a homogeneous method, with a focus on the paleogeographic and paleotectonic evolution, the paleoweathering and the source areas deduced from mineralogical and geochemical data of the Cenozoic mudrocks. The bulk mineralogy is mainly characterized by the presence of calcite, quartz and dolomite plus ankerite. Feldspars have few percentages. The clay minerals are principally represented by mixed-layer illite/smectite (I/S). Illite and kaolinite are in little amount. Femic minerals, mixed-layer chlorite/smectite (C/S) and chlorite are the most abundant. The I/S features suggest a different thermal condition for the three domains. The chemical composition indicates that the mudrocks can be described as mixtures of carbonates with aluminosilicate components. The Al/Ti, Th/Cr, Th/Sc, La/Th and La/Sc ratios, the Cr/V vs. Y/Ni plot, the V-Ni-Th∗10 and La-Th-Sc ternary diagrams indicate a predominantly felsic source with a minor mafic input more evident in the Paleocene-Eocene samples of the External Intrarif and Mesorif. The External Rif Zones changed in the Cenozoic from a passive margin to a complex foreland system with the incoming of the Alpine tectonic phases. In general, the felsic contribution should be linked to the foreland area consisting in the Middle Atlas and Mesetas massifs made of a crystalline domain. This margin probably presented an intermediate narrow oceanic branch in the External Intrarif-Mesorif boundary that surprisingly should start to close during Paleogene times providing the mafic contribution. This Paleogene tectonic activity in these domains is corroborated by the thermal maturity indicating late diagenesis. The chemical weathering indices, such as the CIA (Chemical index of Alteration) and its modifications, show medium-high values and thus suggest generally moderate paleoweathering conditions in agreement with the predominant amount of I/S.

Petrochemistry and Tectonic Setting of the Phroa-Wiang Pa Pao Granitic Rocks, Chiang Mai, and Chiang Rai Provinces, Central Granitic Belt of Thailand

The Phrao-Wiang Pha Phao granitic rocks are crop out along Highway Number 1150 (Phrao-Wiang Pa Pao) in Chiang Mai and Chiang Rai provinces. The geologic investigation as field observation, lithology, petrography, geochemistry, and tectonic interpretation applied for this study. The least-altered 19 rock samples were collected and performed in stained rock slabs for modal analysis and standard thin sections for petrographic analysis. Based on the Quartz-Alkali Feldspar-Plagioclase diagram for plutonic rocks, the rock samples in the Phrao area are granodiorite, and one is biotite-monzogranite, while most of the rock samples in the Wiang Pa Pao area are biotite-monzogranite. The petrographic investigation for rock samples indicated that granitic samples have medium to coarse-grained and show porphyritic texture. The orthoclase phenocrysts are sitting in the groundmass and are composed of quartz, plagioclase, and orthoclase feldspar, with a minor amount of biotite, muscovite, apatite, zircon, titanite, and opaque minerals. The granitic samples can be classified as granodiorite to monzogranite, which is high-K calc-alkalic affinity and peraluminous S-type based on geochemistry. Based on the normative mineralogy calculation, the rock samples were composed mainly of normative quartz, plagioclase, and orthoclase, with minor corundum, hypersthene, magnetite, ilmenite, apatite, zircon, and chromite. The S-type granitoid supported by normative corundum and Na2O/K2O ratios less than 0.49 at Na2O ranging from 1.53 - 2.35 wt %. Their tectonic setting of formation appears to be a post-orogenic environment (post-collisional granite) of the Sibumasu and the Indochina blocks. The Phrao Phrao-Wiang Pha Phao granitic rocks are a part of the Central Granitic Belt and are related to tin-tungsten deposits with rare earth elements. HIGHLIGHTS Tectonic setting of the Phroa-Wiang Pa Pao Granitic Rocks, Thailand. Petrography and modal analysis The geochemistry analysis by XRF and CIPW normative calculation. The Central Granitic Belt in Thailand. GRAPHICAL ABSTRACT

Estimating rare earth elements at various scales with bastnäsite indices for Mountain Pass

Numerous researchers are exploring innovative ways to map rare earth elements (REEs) critical to components in high technology devices precisely, and one approach that has made significant advances in recent years involves imaging spectroscopy. This research focuses on the utilization of this technique to map REEs across the Sulfide Queen mine and Birthday claim area located in Mountain Pass, California, where the highest concentrations of REEs within a carbonatite deposit in the United States have been reported. New spectral indices based on reflectance measurements of eleven representative ore samples under visible illumination in a laboratory setting were developed and applied to data collected by eight airborne and spaceborne imaging spectrometers. The results show that these indices can effectively detect REEs in any rock formation where an adequate amount of rare earth fluorocarbonates have accumulated. Identification can be achieved using airborne and spaceborne hyperspectral sensors with a spatial resolution of up to 30 m. Geochemical analyses confirm that a REE+Y ore grade of 3.25 wt% or greater is sufficient for detection using these indices.

Ore genesis of the Chazangcuo Cu-Pb-Zn deposit in Tibet: evidence from mineralogy, fluid inclusions, S-Pb isotopes, and elemental geochemistry

The Chazangcuo copper-lead-zinc deposit (hereafter referred to as the Chazangcuo deposit) is situated in the northern portion of the western section of the Gangdese polymetallic metallogenic belt in Tibet, with ore bodies strictly governed by Linzizong Group magmatic rocks and EW-trending faults. This study aims to ascertain the mineralization periods, sources of ore-forming materials, metallogenic physicochemical conditions, and genesis of this deposit. Based on comprehensive field geological surveys, sampling, and microscopic examination of petrological and mineralogical characteristics, we perform qualitative and quantitative geochemical analyses of major elements, trace elements, and rare earth elements (REEs), fluid inclusions, and sulfur and lead isotopes. The findings reveal that the mineralization process of the Chazangcuo deposit can be divided into three periods and four stages: the magmatic-hydrothermal, hydrothermal, and supergene mineralization periods sequentially, which consist of the mineralization stages of quartz-pyrite-sphalerite, medium-low-temperature hydrothermal sulfides, chlorite-carbonate minerals, and supergene oxidation in a chronological order. The ore-forming fluids prove to be medium-low-temperature low-density fluids, and the ore-forming materials are characteristic of upper crustal-derived materials. The ore-forming environment is a medium-low mineralization temperature, a shallow and weakly reducing environment. Overall, the Chazangcuo deposit is identified as a medium-low-temperature magmatic-hydrothermal deposit. The metallogenic model has the vertical zoning characteristics of lead-zinc in the upper part and copper in the lower part.