Lithosphere最新文献

{"title":"Effective Etch Times of Fossil Fission Tracks in Geological Apatite Samples and Impact on Temperature-Time Modeling","authors":"Florian Trilsch, Hongyang Fu, R. Jonckheere, Lothar Ratschbacher","doi":"10.2113/2023/lithosphere_2023_339","DOIUrl":"https://doi.org/10.2113/2023/lithosphere_2023_339","url":null,"abstract":"\u0000 Apatite fission-track modeling reconstructs the low-temperature histories of geological samples based on measurements of the lengths of etched confined fission tracks and counted surface tracks. The duration for which each confined track was etched can be calculated from its width given the apatite etch-rate νR. We measured νR as a function of crystallographic orientation for fourteen samples from the igneous and metasedimentary basement of Tian Shan, Central Asia, to optimize the track-length distribution for modeling the thermal histories of apatites with varying chemical compositions. To first order, νR scales with the size of the track intersections with the mineral surface in the range of Dpar = 1.4–2.6 µm. We use νR for calculating the effective etch time tE of confined tracks measured after 20–60 seconds of immersion in 5.5 M HNO3 at 21°C. Considering only tracks within a predetermined etch-time window improves the reproducibility of the track-length distributions. Because an etch-time window allows excluding under- and over-etched tracks, sample immersion times can be optimized to increase the number of confined tracks suitable for modeling. Longer immersion times also allow the longest-etched tracks to develop a clear geometrical outline from which the orientation of the apatite c-axis can be inferred. We finish by comparing thermal histories obtained with a conventional 20-second immersion protocol, without tE selection, with those using the length of tracks within the range of tE = 15–30 seconds. Overall, the alternative models fit better to independent AHe data than the conventional ones.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141376917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation on the Impact Fracture Mechanism of Rock in Microgravity Environment Using the Continuum-Discontinuum Element Method","authors":"Qunlei Zhang, Jin Fang, Chun Feng, Mintao Jia, Pengda Cheng, Shuang Wang","doi":"10.2113/2024/lithosphere_2023_323","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_323","url":null,"abstract":"\u0000 In-depth analysis of asteroid samples will provide a key scientific basis for understanding its evolution history, resource utilization, and life origin. Obtaining rock samples from asteroids is getting more and more attention. However, successful sampling in asteroid is difficult due to extremely complex environmental conditions. In this paper, the dynamic processes of rock failure by sampling device are investigated by a continuum-discontinuum element method (CDEM) to instruct the rock sampling in asteroid. The deformation and failure of rock samples under different conditions (impact speeds, impact positions, rock cut-slot numbers, cut-slot spacings, cut-slot depths and cut-slot widths, etc.) are analyzed, and the relationships between the rock failure and hammer impact method are obtained. The results show that the cut-slot formed by grinding wheel increases the free surface of rock sample, which is beneficial to impact fracture and asteroid sampling. The relative distance between cut-slot free surface and impact position significantly affects the rock fracture under impact loading. The fracture degree of rock with single cut-slot is obviously smaller than that of rock with double cut-slots, the cut-slot scheme of double grinding wheels is more suitable for asteroid sampling. Under the impact loading, the rock fracture is negatively correlated with the cut-slot spacing formed by double grinding wheel cutting, the effective spacing of double cut-slots is 12 mm. The fracture unit number of rock varies nonlinearly with an increase of the depth from impact position, there is an optimal cut-slot depth corresponding to a certain impact velocity, and the rock crushing efficiency of asteroid sampling can be improved as the cut-slot depth matches the crack propagation depth.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141101185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement of the Consistency and Connectivity of the Ant-tracking Algorithm via 3D U-Net with Dual-Threshold Iteration","authors":"Seunghun Choi, Min Je Lee, Yonggwon Jung, Juan Lee, Jineon Kim, Yongchae Cho","doi":"10.2113/2024/lithosphere_2024_118","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2024_118","url":null,"abstract":"\u0000 The ant-tracking algorithm is commonly used to extract faults in geological structures. However, obtaining 3D ant-tracking data requires the calculation of various volume attributes. To obtain satisfactory data, it is necessary to iterate through the parameters of these attributes to achieve reasonable continuity. Moreover, due to the numerous parameters involved, the algorithm can produce different outputs with each execution. In this study, we aimed to enhance the performance of the ant-tracking algorithm by combining it with a basic U-Net structure. The input and corresponding labels to the model are \"cubic shaped\" 3D data segmented from the original 3D seismic volume to facilitate cross-validation with distinct regions. We used the label data as the single ant-tracking result to minimize the operator’s bias by executing the ant-tracking with several different parameters and executors and then taking the average. An evaluative comparison of three different loss functions (MAE, RMSE, and MSE) was conducted to identify the optimal function for training the model. Across five out of the six metrics, MSE function demonstrated predominant performance, leading to its adoption. Apart from this, a significant number of misinterpreted faults led us to propose the post-processing algorithm named \"Dual-Threshold Iteration.\" It was initially used to extract fine blood vessels branching out from large vessels in medical image segmentation and adapted in our work to ensure a high level of continuity while ignoring worthless noise. Comparison with the F1 score and the number of 3D-connected components confirmed that the proposed method could generate reduced bias and smoothly connected fault structures.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107524","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconstructing a Super-Eruption From the Upper Ordovician Period in the Eastern Pyrenees, Spain","authors":"Joan Martí, J. Casas, Josep A. Muñoz","doi":"10.2113/2024/lithosphere_2024_100","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2024_100","url":null,"abstract":"\u0000 The Pyrenean basement rocks, NE of the Iberian Peninsula, southwestern Europe, include evidence of several pre-Variscan magmatic episodes which indicate the complex geodynamic history of this segment of the northern Gondwana margin from late Neoproterozoic to Early-Palaeozoic times. One of the most significant magmatic episodes was late Mid-early Upper Ordovician (Darriwilian-Katian) age that produced several granitic bodies and volcanic rocks interbedded with Sandbian-Katian sediments. This magmatism is well represented in the Ribes de Freser area (Freser valley, Bruguera and Campelles localities, eastern Pyrenees), where these Ordovician magmatic rocks were affected by an irregularly distributed Variscan deformation and mainly by severe Alpine tectonics, which originated the superposition of several structural units. We present a palinspatic reconstruction of this Alpine deformation (80-20 Ma), that permitted us to infer the geometry, facies distribution, original position, thickness, and significance of these volcanic rocks. This reconstruction allows us to interpret the volcanic rocks cropping out at the Freser valley, Bruguera, and Campelles areas as intra-caldera deposits representing a minimum preserved volume of the order of 100 km3. This may confirm the existence of super-eruptions of Upper-Ordovician age in that sector of the eastern Pyrenees and emphasizes the extent of the Upper-Ordovician felsic volcanism in this sector of the northern Gondwana margin, probably developed in an extensional scenario linked to the development of the Rheic Ocean during Gondwana margin breakup.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141107118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the Attenuation Characteristics of Frequency Domain Parameters in Different Rock Medium","authors":"Xiling Liu, Huini Liu, Feng Xiong, Qin Xie, Yuchen Zhong, Qi Hao","doi":"10.2113/2024/lithosphere_2024_113","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2024_113","url":null,"abstract":"\u0000 This study examines the frequency attenuation characteristics of elastic waves in marble, granite, and red sandstone through laboratory tests and numerical simulations based on ABAQUS software on eight rock samples. The correlation between the distance of the decay of the peak frequency and the petrophysical and mechanical parameters is also analyzed. The results show that elastic waves undergo stepwise attenuation of their peak frequency during laboratory attenuation tests. This finding was confirmed by numerical simulations. As elastic waves propagate through a rock medium, the amplitude of the high-frequency peak area near the excitation frequency decreases rapidly, while the proportion of low-frequency signals increases. As the propagation continues, the signal spectrum is dominated by low-frequency components, resulting in a stepwise attenuation of the peak frequency. It has been observed that the step decay distance of the peak frequency of elastic waves varies with the degree of particle bonding, which can be used to characterize the attenuation properties of elastic waves in a medium.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141119513","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exploring the Influence of Seismic Source and Improvement Methods on Tunnel Seismic Prediction","authors":"Xinglin Lu, Wei Wang, Chao Yang, Xuquan Hu, Xian Liao, Zhihong Fu","doi":"10.2113/2024/lithosphere_2023_334","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_334","url":null,"abstract":"\u0000 Tunnel seismic advanced prediction method is essential for detecting abnormal bodies ahead of the tunnel face and minimizing risks during tunnel construction. Selecting the seismic source plays a crucial role in influencing the precision and effectiveness of data acquisition. At present, tunnel seismic data is usually collected using explosive and sledgehammer sources. Nevertheless, the various sources are located in different positions within the tunnel excavation zone, resulting in distinct characteristics observed on the surface and reflected waves in the acquired tunnel seismic data. The explosive source has minimal surface wave interference, but it is expensive. However, the sledgehammer source is economical yet plagued by inadequate energy and substantial surface wave disruption. Regrettably, there is a lack of research on seismic sources in tunnels, which impairs the precise interpretation of forecasting conclusions from these sources. This paper seeks to investigate how various sources impact tunnel seismic prediction and suggests a new method that integrates data acquisition and processing from these sources. The explosive source is used once, while the sledgehammer source is used 24 times. Cross-correlation calculations are conducted to enhance the resolution of sledgehammer source data, reducing surface wave interference, based on seismic data obtained from the explosive source. Extensive numerical simulations and tunnel experiments support the validity of this method, highlighting its potential to lower data acquisition expenses and enhance tunnel seismic prediction accuracy.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141122204","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Regional Shallow Décollement at the Front of the Mexican Fold and Thrust Belt: Microstructure of the Santiago Shale","authors":"Lenin. I. Valdéz-Barrera, Mariano Cerca, Jubier A. Jiménez-Camargo, César A. Cortés-Prado","doi":"10.2113/2024/4031438","DOIUrl":"https://doi.org/10.2113/2024/4031438","url":null,"abstract":"\u0000 This contribution analyses the role played by the mechanical properties of a decollément shale layer in the evolution of the Mexican Fold and Thrust Belt (MFTB). The mobility of overpressured shales can accommodate large strains by grain-scale plastic mechanisms, and affect the folding and thrusting styles of the overburden. Research on shale deformation mechanisms is necessary to improve the knowledge of these processes and their influence on the structural style of fold and thrust belts. The ductile behavior of rocks involving grain-scale plasticity was documented in the Jurassic Santiago shale sequence using geological mapping, microstructural observations on thin-oriented sections, and scanning electron microscopy (SEM) imaging. Structural styles such as detachment folding, fault-bend folding, and shale-cored fold-thrusts were observed at the regional scale. At the outcrop scale, the shale developed strong foliation and pencil cleavage, with immersed packstone boudins. Observed structures include thrusting, soft and open folds, and buckle folding. In thin section, the ductile textures include a strong penetrative foliation with lenticular and wavy-parallel laminae composed of carbonates, ribbons of reoriented clays and organic matter (clay+OM), s-c structures, porphyroblasts microtextures, development of oblique cleavage concerning folded foliation (crenulation cleavage), and carbonates dissolution. The Santiago shale shows also evidence of brittle deformation including calcite-filled fractures and cataclastic gouges. X-ray diffraction (XRD) analysis of the clay size fraction suggests that the authigenic calcareous shale was deformed in conditions of the deep diagenetic zone (between 100 and 200°C) and fluid overpressure (>70 MPa). The results help to improve the understanding of ductile microstructure and its role in shale deformation cretaceous cover, promoting the formation of localized fault propagation folds in the overburden. This study aims to open new perspectives in the kinematics and rheology interpretations for this sector of the MFTB, highlighting the role of the décollement layers during the progression of the orogen.","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140982185","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Typical Rock Physical Characteristics, Mechanical Properties, and Failure Modes of the Laoheba Phosphate Mining Area in the Sichuan Basin, China","authors":"Ming Zou, Zheming Zhu, Weiting Gao, Tao Peng, Meng Wang","doi":"10.2113/2024/lithosphere_2023_348","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_348","url":null,"abstract":"The Laoheba Phosphate Mine Area in the Sichuan Basin stands as one of China’s primary locations for phosphate extraction, boasting a diverse array of rock types and complex rock layers. In recent years, frequent geological disasters, notably landslides, have occurred in the mining area. The safe extraction of phosphate rock faces significant challenges, necessitating an in-depth exploration of the physical and mechanical properties of the rocks within the mining area. This study employs nuclear magnetic resonance (NMR) and X-ray diffractometer (XRD) testing on six typical rock specimens, contrasting and analyzing their physical traits, thus unveiling the impact of rock composition and microstructure on their mechanical properties. The MTS815 Flex Test GT rock mechanics testing system was employed to perform uniaxial compression, triaxial compression, Brazilian disk splitting, and triaxial penetration tests. The study systematically examined the mechanical characteristics of typical rocks in the mining area. The correctness of the experiments was mutually validated by four types of tests. Finally, an analysis of rock failure modes and patterns was conducted. Research suggests that phosphate ore exhibits the highest porosity and permeability. Phosphate ore exhibits significant development of original joints and cracks internally, along with numerous defects, leading to its minimal compressive and tensile strength. Phosphate ore is typically situated in regions of weakened rock mass strength. Real-time monitoring of confining pressure is essential during mining operations to prevent the collapse of surrounding rock formations. The findings of this study offer theoretical backing for secure mining operations in the Laoheba Mining Area of the Sichuan Basin while also furnishing fundamental physical and mechanical parameters for regional geomechanical analysis.The Sichuan Basin is situated in southwestern China. The mining area lies on the southwestern edge of the Sichuan Basin. The phosphate ore layer is found in the lower strata of the Cambrian System. The mining area boasts a diverse range of rock types. The rocks exhibit unique compositions. Their physical and mechanical features differ from those of ordinary rocks. We conducted research on six typical rocks selected from the mining area. Geological exploration and investigation into the physical and mechanical properties of rocks are essential prerequisites for the safe exploitation of phosphate mines.With the exploration and development of mineral resources, and the increasing scale of various underground rock engineering projects, higher demands have been placed on the design and construction of geotechnical engineering. In recent years, there has been a surge in accidents in rock engineering, drawing attention to the safety of underground rock engineering. The physical and mechanical properties of rocks are closely associated with the stability of rock engineering. Therefore, investigating thes","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140933153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Strontium Isotopic Variations of Authigenic Calcite in Clastic Strata Record Its Sediment Provenance and Fluid−Rock Interactions","authors":"Xun Kang, Jingqiang Tan, Feng Lu, Ruipu Hu, Wenxuan Hu","doi":"10.2113/2024/lithosphere_2024_120","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2024_120","url":null,"abstract":"Strontium isotopes of authigenic carbonate potentially record sediment provenance, fluid sources, and fluid–rock interactions, little was studied on this topic in clastic strata. This study investigated clastic rocks containing authigenic calcite in the Lower Triassic Baikouquan Formation in the Junggar Basin, northwestern China. Mineral compositional and fluid inclusion analyses were conducted to constrain the precipitation processes of authigenic calcite, and the Sr contents and isotope ratios of the calcite were also measured. The authigenic calcite was precipitated at 80–140°C as the final product of thermochemical oxidation of hydrocarbons and thus has high Mn contents and highly negative δ13CVPDB values (as low as −70‰). The calcite also exhibits anomalously low 87Sr/86Sr values (0.704827, 0.706612), which are lower than contemporaneous seawater and published 87Sr/86Sr values of carbonate cements in clastic sediments, and also much lower than 87Sr/86Sr values (0.722027, 0.736750) of alkali feldspar in the strata. These low 87Sr/86Sr values record the low 87Sr/86Sr of the dominant rocks in the provenance area, such as volcanic rocks. During diagenesis, especially mesodiagenesis, the charging of hydrocarbon-bearing fluids promoted abundant dissolution of orthoclase in the alkali feldspar detritus, releasing radiogenic 87Sr into the pore waters, and eventually increasing the 87Sr/86Sr values in the late-stage calcite that precipitated after this reaction. This inference is consistent with the positive correlation between the calcite 87Sr/86Sr ratios and the dissolution intensity of orthoclase. In regions that do not undergo hydrocarbon-charging and where orthoclase remains stable, the lower 87Sr/86Sr ratios of the calcite generally record the provenance. For authigenic calcite associated with intense fluid–rock interactions, the higher 87Sr/86Sr ratios reflect the enhanced dissolution intensity of 87Sr-rich minerals such as orthoclase. Therefore, combined with a petrological study, Sr isotopes of authigenic carbonate in clastic sediments can trace sediment provenance and intensity of fluid–rock interactions.Strontium isotope composition is a robust tracer of sediment provenance [1], fluid sources [2, 3], and fluid–rock reactions [4, 5]. The 87Sr/86Sr signature of ancient seawater can serve as a proxy for understanding the tectonic evolution of the Earth system [6, 7] as well as a tool for stratigraphic correlation [8-10]. The 87Sr/86Sr of seawater records the relative importance of two major strontium fluxes: (a) the riverine input of radiogenic Sr due to continental weathering and (b) the “mantle Sr” from hydrothermal circulation at mid-ocean ridges [1, 10]. Strontium isotopic composition of pore water mainly reflects fluctuations of fluid sources, pathways, mixing [2, 3], and fluid–rock reactions [4, 5]. Therefore, Sr isotope was also used in studies investigating the evolution of hydrology and paleohydrology [2, 11], diagenetic reactions, a","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrology and Stable Isotopes of Patchy Dolostone of Ediacaran Dengying Formation in South Qinling, Central China: Implication for the Diagenetic History","authors":"Pengfei Zuo, Haihua Cheng, A. J. C. Magalhães, Jiangtao Sun, Liang Qiu, Zihan Xiao, Yiming Dong","doi":"10.2113/2024/lithosphere_2023_324","DOIUrl":"https://doi.org/10.2113/2024/lithosphere_2023_324","url":null,"abstract":"Dolostone, with its complex diagenetic history, has long been debate. The formation of patchy dolostone, which consists of various types of dolomites, is particularly controversial due to the superimposed diagenetic events. In this study, we conducted mineralogical and stable isotope geochemical analyses of the Ediacaran patchy dolostone from the Dengying Formation in South Qinling to elucidate the diagenetic processes involved. Microscopic examination reveals that the patchy dolostone can be classified into three types: Type I, composed of micritic to powdery crystalline dolomite (D1) and fine crystalline dolomite (D2); Type II, primarily consisting of medium-coarse crystalline dolomite (D3) along with D2; and Type III, characterized by the presence of saddle dolomite (SD) and D1. Cathodoluminescence and electron probe microanalysis indicate that D2 and D3 are enriched in Mn and Fe, whereas SD is depleted in Sr and Na compared to D1. Backscattered electron images reveal a prevalence of apatite, particularly in Type III dolostone. Calcite and quartz extensively replace the dolomites. Carbon and oxygen isotopes indicate that D1 has the highest δ13C and δ18O values, while D2 and D3 show negative shifts, and SD exhibits the lowest values. These observations suggest that the transition from D1 to D2 and D3 is due to recrystallization processes during burial. The formation of SD is likely the result of hydrothermal activity. Consequently, the patchy dolostone experienced three main stages of diagenesis, which included the recrystallization of D1 and the formation of SD. Considering the vertical distribution of the patchy dolostone and the occurrence of hyperkarst breccia dolostone, it is reasonable to infer that sea level variations are the primary cause of the formation of patchy dolostone.The Ediacaran represents a pivotal era in Earth’s history, characterized by remarkable geological, oceanic, and biological changes [1, 2]. During this period, various types of dolostones were extensively developed [3]. Dolostone, which serves as a rock unit documenting the intricate history of sedimentation and diagenesis, has long been a subject of debate and extensive research in geology [4-8]. Various conceptual models, such as the evaporation pump, brine seepage reflux, mixed-water dolomitization, and hydrothermal dolomitization, have been proposed based on these investigations [9-16]. The development of thick dolostone is controlled by external factors, including the paleoclimate background, relative sea-level changes, and tectonic activity [17-20]. This is particularly significant when studying shallow-marine carbonate, where multiple occurrences of these factors may occur during penecontemporaneous or early burial periods, leading to various dolomitization processes. Patchy dolostone, a unique sedimentary fabric characterized by “patchy” sedimentary records and a complex diagenetic evolution [21-24], is controversial for hydrothermal genesis [25, 26] or earl","PeriodicalId":18147,"journal":{"name":"Lithosphere","volume":null,"pages":null},"PeriodicalIF":2.4,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141503459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}