Xi-yong Sun , Yang Jiao , Qian-li Ma , Jing-hui Fan , Xiao-min Du , Jia-feng Liu , Shao-qiang Wang , Wen-chen Hu
Glaciers, as “solid reservoirs”, are precious resources in arid areas. The study of glaciers is of great significance to the sustainable development and management of agriculture and the economy in northern Xinjiang. The area of glacier distribution on the 1963 topographic map data, 1975 MSS data, 2000 ETM data, 2008 CBERS-2 data, 2014 and 2018 ETM+ were collected as secondary data. According to the remote sensing survey, the glacier areas in Northern Xinjiang are identified during 1963–2018. Based on the evolution of glacier area in the past 55 years, and using two scenarios, the average annual decrease area of a region during the whole 1963–2018 and the period with the minimum reduction area, the glacier areas of Southern Tianshan Mountains, Western Tianshan Mountains, Eastern Tianshan Mountains, the Sawuer Mountains and Altai Mountains in Northern Xinjiang, and the whole northern Xinjiang in 2030, 2040, 2050, and 2100 are examined and predicted. In 2100, the glacier area in Northern Xinjiang may decrease by 43%–59%.
{"title":"Analysis and prediction of glacier evolution trend (2020–2100) in Northern Xinjiang","authors":"Xi-yong Sun , Yang Jiao , Qian-li Ma , Jing-hui Fan , Xiao-min Du , Jia-feng Liu , Shao-qiang Wang , Wen-chen Hu","doi":"10.31035/cg2023005","DOIUrl":"10.31035/cg2023005","url":null,"abstract":"<div><div>Glaciers, as “solid reservoirs”, are precious resources in arid areas. The study of glaciers is of great significance to the sustainable development and management of agriculture and the economy in northern Xinjiang. The area of glacier distribution on the 1963 topographic map data, 1975 MSS data, 2000 ETM data, 2008 CBERS-2 data, 2014 and 2018 ETM+ were collected as secondary data. According to the remote sensing survey, the glacier areas in Northern Xinjiang are identified during 1963–2018. Based on the evolution of glacier area in the past 55 years, and using two scenarios, the average annual decrease area of a region during the whole 1963–2018 and the period with the minimum reduction area, the glacier areas of Southern Tianshan Mountains, Western Tianshan Mountains, Eastern Tianshan Mountains, the Sawuer Mountains and Altai Mountains in Northern Xinjiang, and the whole northern Xinjiang in 2030, 2040, 2050, and 2100 are examined and predicted. In 2100, the glacier area in Northern Xinjiang may decrease by 43%–59%.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 661-671"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721458","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-25DOI: 10.1016/S2096-5192(24)00150-2
{"title":"Editorial Committee of China Geology","authors":"","doi":"10.1016/S2096-5192(24)00150-2","DOIUrl":"10.1016/S2096-5192(24)00150-2","url":null,"abstract":"","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 807-810"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Discovery of tuff in Wujiaping Formation of Upper Permian in the northern Sichuan Basin: Implications for the termination of Emeishan Large Igneous Province","authors":"Yu Yu , Xiao-liang Deng","doi":"10.31035/cg2023142","DOIUrl":"10.31035/cg2023142","url":null,"abstract":"","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 801-802"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-ming Ni , Jing-shuo Zhang , Xiao-kai Xu , Bao-yu Wang
Elemental analysis, nuclear magnetic resonance carbon spectroscopy (13C-NMR), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) experiments were carried out to determine the existence of aromatic structure, heteroatom structure and fat structure in coal. MS (materials studio) software was used to optimize and construct a 3D molecular structure model of coal. A method for establishing a coal molecular structure model was formed, which was “determination of key structures in coal, construction of planar molecular structure model, and optimization of three-dimensional molecular structure model”. The structural differences were compared and analyzed. The results show that with the increase of coal rank, the dehydrogenation of cycloalkanes in coal is continuously enhanced, and the content of heteroatoms in the aromatic ring decreases. The heteroatoms and branch chains in the coal are reduced, and the structure is more orderly and tight. The stability of the structure is determined by the π-π interaction between the aromatic rings in the nonbonding energy EN. Key Stretching Energy The size of EB determines how tight the structure is. The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.
{"title":"Molecular structure characterization of middle-high rank coal via 13C NMR, XPS, and FTIR spectroscopy","authors":"Xiao-ming Ni , Jing-shuo Zhang , Xiao-kai Xu , Bao-yu Wang","doi":"10.31035/cg2022135","DOIUrl":"10.31035/cg2022135","url":null,"abstract":"<div><div>Elemental analysis, nuclear magnetic resonance carbon spectroscopy (<sup>13</sup>C-NMR), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) experiments were carried out to determine the existence of aromatic structure, heteroatom structure and fat structure in coal. MS (materials studio) software was used to optimize and construct a 3D molecular structure model of coal. A method for establishing a coal molecular structure model was formed, which was “determination of key structures in coal, construction of planar molecular structure model, and optimization of three-dimensional molecular structure model”. The structural differences were compared and analyzed. The results show that with the increase of coal rank, the dehydrogenation of cycloalkanes in coal is continuously enhanced, and the content of heteroatoms in the aromatic ring decreases. The heteroatoms and branch chains in the coal are reduced, and the structure is more orderly and tight. The stability of the structure is determined by the π-π interaction between the aromatic rings in the nonbonding energy E<sub>N</sub>. Key Stretching Energy The size of E<sub>B</sub> determines how tight the structure is. The research results provide a method and reference for the study of the molecular structure of medium and high coal ranks.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 702-713"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Water erosion is a serious problem that leads to soil degradation, loss, and the destruction of structures. Assessing the risk of erosion and determining the affected areas has become crucial in order to understand the main factors influencing its evolution and to minimize its impacts. This study focuses on evaluating the risk of erosion in the Assif el mal watershed, which is located in the High Atlas Mountains. The Erosion Potential Model (EPM) is used to estimate soil losses depending on various parameters such as lithology, hydrology, topography, and morphometry. Geographic information systems and remote sensing techniques are employed to map areas with high erosive potential and their relationship with the distribution of factors involved. Different digital elevation models are also used in this study to highlight the impact of data quality on the accuracy of the results. The findings reveal that approximately 59% of the total area in the Assif el mal basin has low to very low potential for soil losses, while 22% is moderately affected and 19.9% is at high to very high risk. It is therefore crucial to implement soil conservation measures to mitigate and prevent erosion risks.
水土流失是一个严重的问题，会导致土壤退化、流失和结构破坏。为了了解影响水土流失演变的主要因素并将其影响降至最低，评估水土流失风险和确定受影响地区已变得至关重要。本研究的重点是评估位于高阿特拉斯山脉的 Assif el mal 流域的侵蚀风险。侵蚀潜力模型（EPM）用于估算土壤流失量，具体取决于岩性、水文、地形和形态等各种参数。地理信息系统和遥感技术被用来绘制侵蚀潜力大的地区及其与相关因素分布的关系图。本研究还使用了不同的数字高程模型，以突出数据质量对结果准确性的影响。研究结果表明，阿西夫埃尔马尔盆地总面积中约有 59% 的地区土壤流失潜力较低或很低，22% 的地区受影响程度一般，19.9% 的地区风险较高或很高。因此，实施土壤保持措施以减轻和预防侵蚀风险至关重要。
{"title":"Estimation and mapping of water erosion and soil loss: Application of Gavrilovic erosion potential model (EPM) using GIS and remote sensing in the Assif el mal Watershed, Western high Atlas","authors":"Kabili Salma , Algouti Ahmed , Algouti Abdellah , Ezzahzi Salma","doi":"10.31035/cg2023058","DOIUrl":"10.31035/cg2023058","url":null,"abstract":"<div><div>Water erosion is a serious problem that leads to soil degradation, loss, and the destruction of structures. Assessing the risk of erosion and determining the affected areas has become crucial in order to understand the main factors influencing its evolution and to minimize its impacts. This study focuses on evaluating the risk of erosion in the Assif el mal watershed, which is located in the High Atlas Mountains. The Erosion Potential Model (EPM) is used to estimate soil losses depending on various parameters such as lithology, hydrology, topography, and morphometry. Geographic information systems and remote sensing techniques are employed to map areas with high erosive potential and their relationship with the distribution of factors involved. Different digital elevation models are also used in this study to highlight the impact of data quality on the accuracy of the results. The findings reveal that approximately 59% of the total area in the Assif el mal basin has low to very low potential for soil losses, while 22% is moderately affected and 19.9% is at high to very high risk. It is therefore crucial to implement soil conservation measures to mitigate and prevent erosion risks.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 672-685"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cong Chen , Yu-chao Gu , Di Zhang , Tao-tao Wu , Ai Li , Yun-sheng Ren , Qing-qing Shang , Jian Zhang , Xiong-fei Bian , Fei Su , Jia-lin Yang , Qiu-shi Sun , Xiao-hai Li , Wan-zhen Liu , Zhen-ming Sun , Sen Zhang , Yu-hui Feng
The Hongqiling large nickel-copper-cobalt deposit (hereafter referred to as the Hongqiling deposit), a typical mafic-ultramafic copper-nickel deposit in China, boasts proven Ni (Ni) resources of approximately 22×104 t, associated copper resources of 2×104 t, and associated cobalt (Co) resources of 0.5×104 t, with Ni reserves ranking 10th among China’s magmatic nickel deposits. Geotectonically, the Hongqiling deposit is situated in the superimposed zone between the Xing’an-Mongolian orogenic belt and the circum-Western Pacific’s active continental margin belt. Its ore-bearing plutons occur within the metamorphic rocks of the Ordovician Hulan Group, with the emplacement of plutons and the locations of orebodies governed by the deep-seated Huifahe fault and its secondary NW-trending Fujia-Hejiagou-Beixinglong-Changsheng fault zone. In the deposit, the rock assemblages of ore-bearing plutons predominantly encompass gabbro - pyroxenite - olivine pyroxenite - pyroxene peridotite (pluton No. 1) and noriteorthopyroxenite-harzburgite (pluton No. 7), with ore-bearing lithofacies consisting primarily of olivine pyroxenite and pyroxenite facies. The Hongqiling deposit hosts stratoid, overhanging lentoid, veined, and pure-sulfide veined orebodies. Its ores principally contain metallic minerals including pyrrhotite, pentlandite, chalcopyrite, violarite, and pyrite. Despite unidentified magma sources of ore-bearing mafic-ultramafic rocks, it is roughly accepted that the magmatic evolution in the Hongqiling deposit primarily involved fractional crystallization and crustal contamination. The ore-forming materials were primarily derived from the upper mantle, mixed with minor crustal materials. The ore-bearing mafic-ultramafic rocks in the deposit, primarily emplaced during the Indosinian (208–239 Ma), were formed in an intense extension setting followed by the collisional orogeny between the North China Plate and the Songnen-Zhangguangcai Range Block during the Middle-Late Triassic. From the perspective of the metallogenic geological setting, surrounding rocks, ore-controlling structures, and rock assemblages, this study identified one favorable condition and seven significant indicators for prospecting for Hongqiling-type nickel deposits and developed a prospecting model of the Hongqiling deposit. These serve as valuable references for exploring similar nickel deposits in the region, as well as the deep parts and margins of the Hongqiling deposit.
{"title":"Geology and mineralization of the Hongqiling large magmatic nickel-copper-cobalt deposit (22×104 t) in Jilin Province, China: A review","authors":"Cong Chen , Yu-chao Gu , Di Zhang , Tao-tao Wu , Ai Li , Yun-sheng Ren , Qing-qing Shang , Jian Zhang , Xiong-fei Bian , Fei Su , Jia-lin Yang , Qiu-shi Sun , Xiao-hai Li , Wan-zhen Liu , Zhen-ming Sun , Sen Zhang , Yu-hui Feng","doi":"10.31035/cg2023106","DOIUrl":"10.31035/cg2023106","url":null,"abstract":"<div><div>The Hongqiling large nickel-copper-cobalt deposit (hereafter referred to as the Hongqiling deposit), a typical mafic-ultramafic copper-nickel deposit in China, boasts proven Ni (Ni) resources of approximately 22×10<sup>4</sup> t, associated copper resources of 2×10<sup>4</sup> t, and associated cobalt (Co) resources of 0.5×10<sup>4</sup> t, with Ni reserves ranking 10<sup>th</sup> among China’s magmatic nickel deposits. Geotectonically, the Hongqiling deposit is situated in the superimposed zone between the Xing’an-Mongolian orogenic belt and the circum-Western Pacific’s active continental margin belt. Its ore-bearing plutons occur within the metamorphic rocks of the Ordovician Hulan Group, with the emplacement of plutons and the locations of orebodies governed by the deep-seated Huifahe fault and its secondary NW-trending Fujia-Hejiagou-Beixinglong-Changsheng fault zone. In the deposit, the rock assemblages of ore-bearing plutons predominantly encompass gabbro - pyroxenite - olivine pyroxenite - pyroxene peridotite (pluton No. 1) and noriteorthopyroxenite-harzburgite (pluton No. 7), with ore-bearing lithofacies consisting primarily of olivine pyroxenite and pyroxenite facies. The Hongqiling deposit hosts stratoid, overhanging lentoid, veined, and pure-sulfide veined orebodies. Its ores principally contain metallic minerals including pyrrhotite, pentlandite, chalcopyrite, violarite, and pyrite. Despite unidentified magma sources of ore-bearing mafic-ultramafic rocks, it is roughly accepted that the magmatic evolution in the Hongqiling deposit primarily involved fractional crystallization and crustal contamination. The ore-forming materials were primarily derived from the upper mantle, mixed with minor crustal materials. The ore-bearing mafic-ultramafic rocks in the deposit, primarily emplaced during the Indosinian (208–239 Ma), were formed in an intense extension setting followed by the collisional orogeny between the North China Plate and the Songnen-Zhangguangcai Range Block during the Middle-Late Triassic. From the perspective of the metallogenic geological setting, surrounding rocks, ore-controlling structures, and rock assemblages, this study identified one favorable condition and seven significant indicators for prospecting for Hongqiling-type nickel deposits and developed a prospecting model of the Hongqiling deposit. These serve as valuable references for exploring similar nickel deposits in the region, as well as the deep parts and margins of the Hongqiling deposit.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 762-796"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jing-jie Li , Sheng Lian , Ming-guo Wang , Huai-sheng Zhang , Tao Yang
The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution, which can scientifically guide rational development and utilization of water resources and planning of ecological environment protection. With the expansion and diversification of human activities, the quality of surface rivers will be more directly affected. Therefore, it is of great significance to pay attention to the hydrochemical characteristics of plateau surface rivers and the influence of human activities on their circulation and evolution. In this study, surface water in the Duoqu basin of Jinsha River located in Hengduan mountain region of Eastern Tibet was selected as the representative case. Twenty-three groups of surface water samples were collected to analyze the hydrochemical characteristics and ion sources based on correlation analysis, piper trigram, gibbs model, hydrogen and oxygen isotopic techniques. The results suggest the following: (1) The pH showed slight alkalinity with the value ranged from 7.25 to 8.62. Ca2+, Mg2+ and HCO3– were the main cations and anions. HCO3-Ca and HCO3-Ca·Mg were the primary hydrochemical types for the surface water of Duoqu River. The correlation analysis showed that TDS had the most significant correlation with Ca2+, Mg2+ and HCO3–. Analysis on hydrogen and oxygen isotopes indicated that the surface rivers were mainly recharged by atmospheric precipitation and glacial melt water in this study area. (2) The surface water had a certain reverse cation alternating adsorption, and surface water ions were mainly derived from rock weathering, mainly controlled by weathering and dissolution of carbonates, and secondly by silicates and sodium rocks. (3) The influence of human activities was weak, while the development of cinnabar minerals had a certain impact on the hydrochemistry characteristics, which was the main factor for causing the increase of SO42–. The densely populated county towns and temples with frequent incense burning activities may cause some anomalies of surface water quality. At present, the Duoqu River watershed had gone through a certain influence of mineral exploitation, so the hydrological cycle and river ecoenvironment at watershed scale will still bound to be change. The results could provide basic support for better understanding water balance evolution as well as the ecological protection of Duoqu River watershed.
{"title":"Hydrochemical characteristics of surface water in Hengduan mountain region of Eastern Tibet and its response to human activities: A case study of Duoqu Basin, Jinsha River","authors":"Jing-jie Li , Sheng Lian , Ming-guo Wang , Huai-sheng Zhang , Tao Yang","doi":"10.31035/cg2023053","DOIUrl":"10.31035/cg2023053","url":null,"abstract":"<div><div>The analysis of hydrochemical characteristics and influencing factors of surface river on plateau is helpful to study water hydrological cycle and environmental evolution, which can scientifically guide rational development and utilization of water resources and planning of ecological environment protection. With the expansion and diversification of human activities, the quality of surface rivers will be more directly affected. Therefore, it is of great significance to pay attention to the hydrochemical characteristics of plateau surface rivers and the influence of human activities on their circulation and evolution. In this study, surface water in the Duoqu basin of Jinsha River located in Hengduan mountain region of Eastern Tibet was selected as the representative case. Twenty-three groups of surface water samples were collected to analyze the hydrochemical characteristics and ion sources based on correlation analysis, piper trigram, gibbs model, hydrogen and oxygen isotopic techniques. The results suggest the following: (1) The pH showed slight alkalinity with the value ranged from 7.25 to 8.62. Ca<sup>2+</sup>, Mg<sup>2+</sup> and HCO<sub>3</sub><sup>–</sup> were the main cations and anions. HCO<sub>3</sub>-Ca and HCO<sub>3</sub>-Ca·Mg were the primary hydrochemical types for the surface water of Duoqu River. The correlation analysis showed that TDS had the most significant correlation with Ca<sup>2+</sup>, Mg<sup>2+</sup> and HCO<sub>3</sub><sup>–</sup>. Analysis on hydrogen and oxygen isotopes indicated that the surface rivers were mainly recharged by atmospheric precipitation and glacial melt water in this study area. (2) The surface water had a certain reverse cation alternating adsorption, and surface water ions were mainly derived from rock weathering, mainly controlled by weathering and dissolution of carbonates, and secondly by silicates and sodium rocks. (3) The influence of human activities was weak, while the development of cinnabar minerals had a certain impact on the hydrochemistry characteristics, which was the main factor for causing the increase of SO<sub>4</sub><sup>2–</sup>. The densely populated county towns and temples with frequent incense burning activities may cause some anomalies of surface water quality. At present, the Duoqu River watershed had gone through a certain influence of mineral exploitation, so the hydrological cycle and river ecoenvironment at watershed scale will still bound to be change. The results could provide basic support for better understanding water balance evolution as well as the ecological protection of Duoqu River watershed.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 630-641"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An-kun Zhao , Dong Wang , Qian Zhang , Zi-hui Lei , Qian Yu , Di Zhang , Ye-xin Zhou
Upper Ordovician–Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China. Due to the complex sedimentary environment adjacent to the Kangdian Uplift, the favorable area for organic-rich shale development is still undetermined. The authors, therefore, focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin. Multiple methods were applied in this study, including thin section identification, scanning electron microscopy (SEM) observations and X-ray diffraction (XRD), and elemental analysis on outcrop samples. Five lithofacies have been defined according to the mineralogical and petrological analyses, including mudstone, bioclastic limestone, silty shale, dolomitic shale, and carbonaceous siliceous shale. The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity. The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization. High dolomite content in the study area is accompanied by high TOC, which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water. And for the area close to the Kangdian Uplift, the shale gas generation capability is comparatively favorable. The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted, and more shale gas resources in the mountainbasin transitional zone might be identified in the future.
上奥陶统-下志留统五峰-龙马溪地层是中国南方页岩气最发育的地层。由于康店隆起附近沉积环境复杂，富含有机质页岩发育的有利区域尚未确定。因此，作者重点研究了五峰-龙马溪页岩的有机质富集机制和沉积环境特征，以期对四川盆地周边边缘地区的有机质富集和有利区域有更全面的认识和新的发现。本研究采用了多种方法，包括薄片鉴定、扫描电子显微镜（SEM）观察和 X 射线衍射（XRD），以及露头样品的元素分析。根据矿物学和岩石学分析，确定了五种岩性，包括泥岩、生物碎屑灰岩、硅质页岩、白云质页岩和碳质硅质页岩。对古环境进行了重建，并确定了有机质富集机制为还原环境和高生产力。根据地球化学特征，五峰期总体为亚缺氧环境，龙马溪早期为还原环境。研究区白云岩含量高，同时总有机碳含量也高，这可能表明生物在较浅的水体中繁衍形成了限制性缺氧环境。而在靠近康店隆起带的地区，页岩气的生成能力相对较好。这些地球化学参数表明，可以锁定新的页岩气勘探有利区域，未来可能会在山盆过渡带发现更多的页岩气资源。
{"title":"Sedimentary environment and organic matter accumulation of Wufeng-Longmaxi shales, southwest Yangtze Plate, China: Insights from geochemical and petrological evidence","authors":"An-kun Zhao , Dong Wang , Qian Zhang , Zi-hui Lei , Qian Yu , Di Zhang , Ye-xin Zhou","doi":"10.31035/cg2022074","DOIUrl":"10.31035/cg2022074","url":null,"abstract":"<div><div>Upper Ordovician–Lower Silurian Wufeng-Longmaxi Formation is the most developed strata of shale gas in southern China. Due to the complex sedimentary environment adjacent to the Kangdian Uplift, the favorable area for organic-rich shale development is still undetermined. The authors, therefore, focus on the mechanism of accumulation of organic matter and the characterization of the sedimentary environment of the Wufeng-Longmaxi Shales to have a more complete understanding and new discovering of organic matter enrichment and favorable area in the marginal region around Sichuan Basin. Multiple methods were applied in this study, including thin section identification, scanning electron microscopy (SEM) observations and X-ray diffraction (XRD), and elemental analysis on outcrop samples. Five lithofacies have been defined according to the mineralogical and petrological analyses, including mudstone, bioclastic limestone, silty shale, dolomitic shale, and carbonaceous siliceous shale. The paleo-environments have been reconstructed and the organic enrichment mechanism has been identified as a reduced environment and high productivity. The Wufeng period is generally a suboxic environment and the early Longmaxi period is a reducing environment based on geochemical characterization. High dolomite content in the study area is accompanied by high TOC, which may potentially indicate the restricted anoxic environment formed by biological flourishing in shallower water. And for the area close to the Kangdian Uplift, the shale gas generation capability is comparatively favorable. The geochemical parameters implied that new favorable areas for shale gas exploration could be targeted, and more shale gas resources in the mountainbasin transitional zone might be identified in the future.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 747-761"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142722183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Wen-yu Wang , Chang-fu Fan , Zhao-jun Song , Hong Wang , Fu Wang
Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments. Its growth and burial process is a carbon sequestration and storage process. Oyster shell may stop growing due to suffer from freeze shock during the winter season within a temperate climate, therefore, in order to study the carbon sequestration capacity of oysters we need to know the water temperature at which the shell suffer from winter freeze shock. This study examines δ18O profiles across consecutive micro-growth layers found in three modern Pacific oyster shells from the northwest coast of Bohai Bay. A total of 165 oxygen isotope values from sequential samples of their left shells showed periodically varying values, and the variation fluctuation of oxygen isotope values was 4.97‰ on average. According to the variation range of the oxygen isotope value of the shell, combined with the sea surface temperature and the sea surface salinity data of the water in which the oysters grew, the water temperature that suffer from winter freeze shock and stops or retards the growth of Pacific oysters in Bohai Bay is about 8.3°C, and the corresponding period is from December to March of the following year. The calcification time of oysters within one year is nearly a month longer than previously thought, therefore, its carbon sink potential is also improved.
{"title":"Pacific oyster (Crassostrea gigas) shell growth duration in a year in Bohai Bay and implication for its carbon sink potential","authors":"Wen-yu Wang , Chang-fu Fan , Zhao-jun Song , Hong Wang , Fu Wang","doi":"10.31035/cg2023054","DOIUrl":"10.31035/cg2023054","url":null,"abstract":"<div><div>Oyster is a bivalve mollusk widely distributed in estuarine and shallow sea environments. Its growth and burial process is a carbon sequestration and storage process. Oyster shell may stop growing due to suffer from freeze shock during the winter season within a temperate climate, therefore, in order to study the carbon sequestration capacity of oysters we need to know the water temperature at which the shell suffer from winter freeze shock. This study examines <em>δ</em><sup>18</sup>O profiles across consecutive micro-growth layers found in three modern Pacific oyster shells from the northwest coast of Bohai Bay. A total of 165 oxygen isotope values from sequential samples of their left shells showed periodically varying values, and the variation fluctuation of oxygen isotope values was 4.97‰ on average. According to the variation range of the oxygen isotope value of the shell, combined with the sea surface temperature and the sea surface salinity data of the water in which the oysters grew, the water temperature that suffer from winter freeze shock and stops or retards the growth of Pacific oysters in Bohai Bay is about 8.3°C, and the corresponding period is from December to March of the following year. The calcification time of oysters within one year is nearly a month longer than previously thought, therefore, its carbon sink potential is also improved.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 653-660"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78237140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ning Zhong , Xian-bing Zhang , Chang-bao Guo , Zhen Yang , Hao Yu , Rui-an Wu , Yang Wang , Hai-bing Li
At least 13 active fault zones have developed in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, and there have been undergone 17 MS ≥ 7.0 earthquakes, the largest earthquake is 1950 Chayu MS 8.5 earthquake, which has very strong seismic activity. Therefore, carrying out engineering construction in the Sichuan-Tibet transport corridor is a huge challenge for geological technological personnel. To determining the spatial geometric distribution, activity of active faults and geological safety risk in the Sichuan-Tibet transport corridor. Based on remote sensing images, ground surveys, and chronological tests, as well as the deep geophysical and current GPS data, we investigated the geometry, segmentation, and paleoearthquake history of five major active fault zones in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, namely the Xianshuihe, Litang, Batang, Jiali-Chayu and Lulang-Yigong. The five major fault zones are all Holocene active faults, which contain strike-slip components as well as thrust or normal fault components, and contain multiple branch faults. The Selaha-Kangding segment of the Xianshuihe fault zone, the Maoyaba and Litang segment of the Litang fault zone, the middle segment (Yigong-Tongmai-Bomi) of Jiali-Chayu fault zone and Lulang-Yigong fault zone have the risk of experiencing strong earthquakes in the future, with a high possibility of the occurrence of MS ≥ 7.0 earthquakes. The Jinsha River and the Palong-Zangbu River, which is a high-risk area for geological hazard chain risk in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor. Construction and safe operation Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, need strengthen analysis the current crustal deformation, stress distribution and fault activity patterns, clarify active faults relationship with large earthquakes, and determine the potential maximum magnitude, epicenters, and risk range. This study provides basic data for understanding the activity, seismicity, and tectonic deformation patterns of the regional faults in the Sichuan-Tibet transport corridor.
{"title":"Geological risk assessment of traffic engineering construction among 7.0–8.5 magnitude earthquake areas: Practice from the Sichuan-Tibet transport corridor in the eastern Tibetan Plateau","authors":"Ning Zhong , Xian-bing Zhang , Chang-bao Guo , Zhen Yang , Hao Yu , Rui-an Wu , Yang Wang , Hai-bing Li","doi":"10.31035/cg2023055","DOIUrl":"10.31035/cg2023055","url":null,"abstract":"<div><div>At least 13 active fault zones have developed in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, and there have been undergone 17 <em>M</em><sub>S</sub> ≥ 7.0 earthquakes, the largest earthquake is 1950 Chayu <em>M</em><sub>S</sub> 8.5 earthquake, which has very strong seismic activity. Therefore, carrying out engineering construction in the Sichuan-Tibet transport corridor is a huge challenge for geological technological personnel. To determining the spatial geometric distribution, activity of active faults and geological safety risk in the Sichuan-Tibet transport corridor. Based on remote sensing images, ground surveys, and chronological tests, as well as the deep geophysical and current GPS data, we investigated the geometry, segmentation, and paleoearthquake history of five major active fault zones in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, namely the Xianshuihe, Litang, Batang, Jiali-Chayu and Lulang-Yigong. The five major fault zones are all Holocene active faults, which contain strike-slip components as well as thrust or normal fault components, and contain multiple branch faults. The Selaha-Kangding segment of the Xianshuihe fault zone, the Maoyaba and Litang segment of the Litang fault zone, the middle segment (Yigong-Tongmai-Bomi) of Jiali-Chayu fault zone and Lulang-Yigong fault zone have the risk of experiencing strong earthquakes in the future, with a high possibility of the occurrence of <em>M</em><sub>S</sub> ≥ 7.0 earthquakes. The Jinsha River and the Palong-Zangbu River, which is a high-risk area for geological hazard chain risk in the Ya’an-Linzhi section of the Sichuan-Tibet transport corridor. Construction and safe operation Ya’an-Linzhi section of the Sichuan-Tibet transport corridor, need strengthen analysis the current crustal deformation, stress distribution and fault activity patterns, clarify active faults relationship with large earthquakes, and determine the potential maximum magnitude, epicenters, and risk range. This study provides basic data for understanding the activity, seismicity, and tectonic deformation patterns of the regional faults in the Sichuan-Tibet transport corridor.</div></div>","PeriodicalId":45329,"journal":{"name":"China Geology","volume":"7 4","pages":"Pages 605-629"},"PeriodicalIF":4.6,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142721456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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