{"title":"Paleoenvironmental Shifts Across the Upper Cretaceous-Palaeocene Succession in Eastern Tethys, Pakistan","authors":"Amir Shahzad, Thierry Adatte","doi":"10.1002/gj.5173","DOIUrl":"https://doi.org/10.1002/gj.5173","url":null,"abstract":"<div>\u0000 \u0000 <p>The Cretaceous-Paleogene (K/Pg) transition is a global mass extinction event that affected the paleoenvironment, palaeogeography, and biota of the Earth. In this study, we investigated the sedimentary record of the K/Pg transition in the Hazara Basin, a part of Eastern Tethys in Pakistan, using an integrated approach of sedimentology, micropaleontology, geochemistry, and mineralogy. We identified eight biozones based on benthic and planktonic foraminifera, ranging from Middle Cenomanian to Thanetian in age. We also recognised 10 microfacies, reflecting different depositional settings from middle-outer ramp to inner ramp and shoreface environments across the K/Pg transition. We used geochemical proxies and indices to infer the paleoredox conditions, paleosalinity, paleotemperature, detrital input, and paleoproductivity of the basin. We found that oxygenated conditions prevailed across the K/Pg transition, with normal salinity in marine settings and lower salinity in continental settings. The Sr/Ca and Mn/Ca ratios indicated moderate paleotemperature and low terrigenous input, except for shale intervals with higher detrital input. The chemical weathering proxies showed moderate to intense weathering in the source area. The organic matter was mainly of type-III and type-IV, with low total organic carbon and hydrogen index values. The clay mineralogy was dominated by kaolinite, indicating warm and humid conditions, followed by smectite, chlorite, and illite. The K/Pg boundary could not be constrained by the fossil record due to the absence of Late Maastrichtian and Danian fauna in the Hazara region, which may be attributed to tectonic uplift, erosion, and non-deposition of sediments during the collision of the Indian Plate and Kohistan Island Arc. However, the boundary could be recognised by the facies change corresponding to lateritic and oolitic haematite at the base of the early Palaeocene Hangu Formation.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 9","pages":"2281-2310"},"PeriodicalIF":2.2,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013067","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}
Adeeb Ahmed, Mohammed Hail Hakimi, Samina Jahandad, Aref Lashin, Afikah Rahim, Waqas Naseem, Danis K. Nurgaliev, Muhammad Asif Khan, Muhammad Nofal Munir
{"title":"Geochemical Characteristics and 1-D Basin Modelling Study of the Early Cretaceous and Paleogene Succession in the Southern Indus Basin, Southern Pakistan","authors":"Adeeb Ahmed, Mohammed Hail Hakimi, Samina Jahandad, Aref Lashin, Afikah Rahim, Waqas Naseem, Danis K. Nurgaliev, Muhammad Asif Khan, Muhammad Nofal Munir","doi":"10.1002/gj.5169","DOIUrl":"https://doi.org/10.1002/gj.5169","url":null,"abstract":"<div>\u0000 \u0000 <p>Early Cretaceous and Paleogene shale and limestone sediments in the southern Indus Basin were investigated by geochemical data and 1-D basin modelling. Most of the shales from the Early Cretaceous and Paleogene formations exhibit total organic carbon (TOC) content between 0.51 wt. % and 6.06 wt. %, overall, indicating organic matter richness capable of generating hydrocarbons. However, the limestone samples of the Paleogene formations have lower TOC values in the range of 0.36–0.97 wt.%, inferring poor to fair petroleum source rock. The studied shale and limestone sections exhibit also varying hydrogen indices (HI) ranging from 27 to 430 mg HC/g TOC and different kerogen pathways, ranging from Type II to Type IV. Generally, most of the samples with the Lower Cretaceous and Paleogene formations consist mainly of hydrogen-poor Type III and IV kerogens, with HI values range from 27 to 206 mg HC/g TOC, while some other samples belonging to the Paleogene formations exhibit Types II and II/III kerogen (HI from 219 to 430 mg HC/g TOC). The dominance of such kerogen shows the presence of oil- and gas-prone source rocks, with high potential for gas generation. Maturity-related indicator of Rock-Eval T<sub>max</sub> shows different thermal maturity levels, ranging from immature to post-mature. Most of the Lower Cretaceous Goru shales are more mature than other Paleogene sediments, and rank from main oil to gas generation windows, reaching the generation efficiency. This is probably attributed to the deep burial of the Goru Formation reaching a depth up to 4050 m. Therefore, the preliminary geochemical results of the Goru shale unit were integrated into a basin modelling analysis using three exploratory wells to simulate the timing of oil and gas generation. In this case, the simulated basin models reveal that the Goru source rock system currently attained the main oil and gas generation windows, with computed vitrinite reflectance values between 0.75 and 2.00 Easy %Ro. The simulated models indicate that commercial amounts of oil have been generated from the Goru source rock system since the early Palaeocene, as demonstrated by the TR ratio of up to 62%. Moreover, oil was cracked into thermogenic gas during the late Eocene to present-day, with computed vitrinite reflectance of up to 2.00 Easy %Ro. The oil and gas generation was increased with increasing the burial depth, thus, an intensive hydrocarbon exploration and production program is highly recommended in the deeper stratigraphic succession of the Goru source rock system in the southern Indus Basin.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 9","pages":"2213-2231"},"PeriodicalIF":2.2,"publicationDate":"2025-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145012288","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":"The Geological Characteristics of Low-Permeability Sandstone Uranium Deposit in Ordos Basin, North China: Implications of Cause of Low Permeability and Corresponding In Situ Leaching Methods","authors":"Tongpan Wu, Xuebin Su, Lixin Zhao, Chunru Hou, Qingliang Wang, Chunze Zhou, Yuhan Zou, Guoping Jiang","doi":"10.1002/gj.5155","DOIUrl":"https://doi.org/10.1002/gj.5155","url":null,"abstract":"<div>\u0000 \u0000 <p>This study delves into the low-permeability sandstone uranium deposits in China's Ordos Basin, examining the Daying and Bayinqinggeli deposits. Employing x-ray diffraction, clay mineral analysis, x-ray fluorescence, core porosity, gas permeability tests, micrometre computed tomography (CT), and scanning electron microscopy (SEM), the research reveals the low-permeability genesis of these uranium deposits. The findings highlight a high presence of clay minerals, with Daying from 11.5% to 31.5%, and Bayinqinggeli at about 10%. Dense calcareous interlayers are common, with carbonate minerals like calcite and dolomite filling pore spaces and cementing rock-forming minerals, reducing pore sizes and ineffective connectivity, creating dead pore spaces and lowered permeability. The study concludes that the high montmorillonite content and calcareous cementation are the main causes of low permeability, providing a theoretical basis for future permeability enhancement and sustainable exploitation of uranium resources.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 7","pages":"1721-1735"},"PeriodicalIF":1.4,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635553","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}
Dhaval R. Maru, Vijendra Kumar, Kul Vaibhav Sharma, Quoc Bao Pham, Anant Patel
{"title":"Integrating GIS, MCDM, and Spatial Analysis for Comprehensive Flood Risk Assessment and Mapping in Uttarakhand, India","authors":"Dhaval R. Maru, Vijendra Kumar, Kul Vaibhav Sharma, Quoc Bao Pham, Anant Patel","doi":"10.1002/gj.5172","DOIUrl":"https://doi.org/10.1002/gj.5172","url":null,"abstract":"<div>\u0000 \u0000 <p>This study presents a comprehensive approach to flood risk assessment and mapping in the Uttarakhand region, India, by integrating geographic information system (GIS) and multi-criteria decision-making (MCDM). The methodology involves using digital elevation models (DEMs) to categorise elevation into five classes, slope analysis to evaluate the role of terrain steepness and drainage density assessment to identify areas less susceptible to flooding. Average annual rainfall data, classified from meteorological stations, land use/land cover patterns and distances from rivers and roads, were analysed within a GIS framework to assess flood susceptibility. The analytic hierarchy process (AHP) was employed to assign weights to these criteria and generate a flood risk index (FRI) map. Key findings indicate that extensive moderate-to-high-risk zones are present, particularly in the lower regions of Uttarakhand. The weighted overlay analysis using GIS and AHP effectively identified areas at greater risk of flooding. The results offer valuable insights for flood risk management, land-use planning and disaster preparedness, highlighting the need for targeted interventions to enhance flood resilience in the region.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 9","pages":"2263-2280"},"PeriodicalIF":2.2,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013303","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":"Chinese Digital Economy and Urban Green Innovation Quality and Efficiency: The Threshold Effect Analysis Based on Chinese Cities Agglomeration","authors":"Li Yue, Yuan Yin, Yuxuan Cao, Fayyaz Ahmad","doi":"10.1002/gj.5168","DOIUrl":"https://doi.org/10.1002/gj.5168","url":null,"abstract":"<div>\u0000 \u0000 <p>This paper takes 277 Chinese cities data from 2011 to 2020 and measures the quality of green innovation and efficiency of green innovation based on super-efficiency SBM model. This paper uses the fixed effect model to analyse the digital economy on the influence of the quality and efficiency of urban green innovation, and uses the threshold effect model to test the threshold effect gathered in this effect. This paper found that the digital economy can promote urban green innovation quality and efficiency. The conclusion is still valid after robustness tests, such as recalculating the level of the digital economy and adjusting the sample time interval. Heterogeneity test shows that digital economy has a more obvious effect on improving the quality of green innovation in central and western cities, non-resource cities, cities with high-level innovation and cities with low-level enterprise density, while it has a more obvious effect on improving the efficiency of green innovation in eastern cities, non-resource cities, cities with high-level innovation and cities with high-level enterprise density. Furthermore, digital economy can enhance the quality and efficiency of urban green innovation by increasing the degree of urban economic agglomeration, talent agglomeration, industrial agglomeration and financial agglomeration. Additionally, the quality of green innovation, the improvement effect of the digital economy is stronger when the degree of economic agglomeration exceeds the threshold. Finally, when the degree of economic and financial agglomeration exceeds the threshold, the improvement of green innovation efficiency caused by the digital economy is stronger. Therefore, the government should improve the infrastructure of the digital economy, pay attention to the role of agglomeration, develop the digital economy according to local conditions and promote urban green innovation.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 9","pages":"2195-2212"},"PeriodicalIF":2.2,"publicationDate":"2025-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013186","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}
Kai Qi, ZhanLi Ren, Junping Cui, Qian Ma, Guangyuan Xing
{"title":"Zircon U–Pb Geochronology and Hf Isotope, Whole-Rock Geochemistry and Sr–Nd Isotopes of the Late Jurassic–Early Cretaceous Intrusive Rocks From North Shanxi Province: Insight on Petrogenesis and Magmatic Process in the Central North China Craton","authors":"Kai Qi, ZhanLi Ren, Junping Cui, Qian Ma, Guangyuan Xing","doi":"10.1002/gj.5145","DOIUrl":"https://doi.org/10.1002/gj.5145","url":null,"abstract":"<div>\u0000 \u0000 <p>The Late Jurassic to Early Cretaceous was a critical transformative period for the North China Craton (NCC), marked by a tectonic shift from compression to extension and the formation of numerous Yanshanian magmatic intrusions across Shanxi Province. This article presents zircon U–Pb geochronology and Hf isotope, whole-rock geochemistry and Sr–Nd isotopic compositions of Late Jurassic to Early Cretaceous intrusive rocks from the Hunyuan area in northern Shanxi Province. The Chakou, Liulengshan and Zhongzhuangpu intrusions yield zircon U–Pb ages of 150.9 ± 1.7 Ma, 137.9 ± 2.0 Ma and 115.4 ± 0.6 Ma, respectively. The Chakou monzogranites exhibit typical features of high-K calc-alkaline I-type granites, and they are enriched in Rb, Ba, K and U, and depleted in Nb and Ta. The Sr and Nd isotopes of these samples show (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> values ranging from 0.7062 to 0.7103 and <i>ε</i>\u0000 <sub>Nd</sub>(<i>t</i>) values between −8.8 and −8.7. Additionally, zircon rims show highly variable <i>ε</i>\u0000 <sub>Hf</sub>(<i>t</i>) values, spanning from −12.7 to −8.1. Geochemistry and isotopes suggest that the Chakou monzogranites originated primarily from the partial melting of the lower crust. The Liulengshan quartz syenites exhibit low SiO<sub>2</sub> and high K<sub>2</sub>O contents, classifying them as shoshonitic I-type quartz syenites. They are enriched in LREE and LILE, depleted in HFSE with a weak negative Eu anomaly, and display moderate <i>ε</i>\u0000 <sub>Nd</sub>(<i>t</i>) values between −17.1 and −17.0. Zircon Hf isotope composition is relatively uniform, with <i>ε</i>\u0000 <sub>Hf</sub>(<i>t</i>) values ranging from −22.6 to −20.4. We propose that the quartz syenites from Liulengshan were formed by mixed products of mantle-derived and crust-derived magmas, with the latter being dominant. The Zhongzhuangpu biotite monzogranites are petrologically and geochemically uniform, showing enrichment in Pb and Ta, and strong depletion in Sr, Ba and Eu. We consider that they originated from the partial melting of crustal materials. Collectively, our data indicate that continuous crustal extension, thinning and asthenospheric upwelling facilitated partial melting of both lithospheric mantle and crustal materials. These processes were the primary drivers behind the formation of intrusions in the NCC during the Late Jurassic to Early Cretaceous.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 7","pages":"1576-1600"},"PeriodicalIF":1.4,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635563","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":"Impact of Tropical Cyclone Yaas on Coastal Regions of Odisha and West Bengal, India: An Assessment Using Sentinel Datasets","authors":"Bahadur Das, Dipanwita Dutta, Ratnadeep Ray","doi":"10.1002/gj.5153","DOIUrl":"https://doi.org/10.1002/gj.5153","url":null,"abstract":"<div>\u0000 \u0000 <p>Coastal areas are increasingly susceptible to frequent cyclones driven by climate change. This leads to severe flooding, habitat loss, economic damage and community displacement, necessitating urgent adaptation measures. In this context, the present study aims to assess the impact of tropical cyclone Yaas on the coastal districts of Odisha and West Bengal combining SAR and optical satellite data. The Sentinel-1 data was used for flood inundation analysis, allowing for the identification and mapping of areas affected by the cyclonic flooding. In addition, Sentinel-2 data was employed for land use and land cover (LULC) analysis, enabling the evaluation of the cyclone's impact on various land cover classes. A fuzzy Analytic Hierarchy Process (AHP) was applied to analyse the changes in forest canopy cover. By integrating these diverse datasets and analyses, the study provides a holistic understanding of the cyclone's impact on the coastal region's environment and land cover. The findings reveal that the Yaas cyclonic flood affected an area of 2528.70 sq. km, accounting for 6.8% of the total region. In the coastal areas of West Bengal, more than 24% of cropland was affected particularly in the districts of Purba Medinipur, North 24 Parganas, Hoogly, Howrah and South 24 Parganas. In Odisha state, the most affected cropland areas were Bhadrak (945.11 sq. km) and Kendrapara (557.90 sq. km), while the districts of Bhadrak, Balasore, Jajpur, Khordha and Cuttack experienced the greatest impact on built-up areas. The findings of this comprehensive study contribute to a deeper understanding of the magnitude and extent of tropical cyclone Yaas's impacts. This study can be useful for the development of effective mitigation and adaptation strategies that is, restoration of mangrove forests, introduction of salt-tolerant crops and upgrading of existing embankments and levees to enhance the resilience of the coastal communities.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 5","pages":"1029-1045"},"PeriodicalIF":1.4,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143914652","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":"Geospatial Assessment and Mapping Landslide Susceptibility for the Garo Hills Division, Meghalaya, India","authors":"Naveen Badavath, Smrutirekha Sahoo","doi":"10.1002/gj.5166","DOIUrl":"https://doi.org/10.1002/gj.5166","url":null,"abstract":"<div>\u0000 \u0000 <p>Creating accurate and effective Landslide Susceptibility (LS) maps can aid disaster prevention and mitigation efforts and provide sufficient public safety. The primary aim of this study is to develop an LS map for the Garo Hills region in Meghalaya, India, using the weight of evidence (WoE), frequency ratio (FR), and Shannon entropy (SE) methods. A comprehensive landslide inventory catalogued 98 events from 2000 to 2023 for the analysis, and nine key geographical and environmental parameters were prepared. Conducted multicollinearity and correlation analysis to identify and mitigate collinearity issues between factors. The model's performance was analysed through the area under the curve (AUC) value of receiver operating characteristic (ROC) curves and three recent landslides. The results showed that FR method achieved the highest accuracy, with successive rate curve (SRC) AUC and predictive rate curve (PRC) AUC values of 0.860 and 0.940, respectively, and classified susceptibility at three sites as high, moderate, and low. The WoE method effectively identified three landslides site in high and very high susceptibility zones, achieving SRC AUC and PRC AUC values of 0.844 and 0.915, respectively. The SE method showed robust performance in predicting landslide-prone areas, with PRC AUC comparable to other methods (0.913), though its SRC AUC (0.771) was lower. Developed maps revealed that high and very high susceptibility zones account for approximately 10% and 3% of the study area, predominantly near roads, steep slopes, and higher elevations. The information in this study is valuable for civilians and the government authorities involved in hazard monitoring and management.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 5","pages":"1184-1201"},"PeriodicalIF":1.4,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143914727","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":"Chronology, Geochemical Characterisation and Tectonic Background of Early Cretaceous Volcanic Rocks in the Lengjimanda Plate, Da Hinggan Mountains","authors":"Wang ShiChang, Hao YuJie, Tang Zhen, Shi Lu","doi":"10.1002/gj.5151","DOIUrl":"https://doi.org/10.1002/gj.5151","url":null,"abstract":"<div>\u0000 \u0000 <p>The Lengjimanda Plate in the central Da Hinggan Mountains is mainly composed of a series of acid volcanic rocks such as rhyolites and rhyolitic crystal tuffs of the Early Cretaceous Baiyingaolao and Guanghua formations. LA-ICP-MS zircon U–Pb dating indicates that rhyolites of the Baiyingaolao Formation formed between 140 and 137 Ma, while rhyolites of the Guanghua Formation formed between 129 and 128 Ma. Rocks of the Baiyingaolao Formation exhibit the characteristics of high silica contents, alkali enrichment and aluminium depletion, thus resembling A-type granites. They show significant fractionation of light and heavy rare earth elements with a pronounced negative Eu anomaly. They zircon <sup>176</sup>Hf/<sup>177</sup>Hf ratios range from 0.282932 to 0.252800, with an average <i>ε</i>\u0000 <sub>Hf</sub>(<i>t</i>) value of +1.28; (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>\u0000 <i>i</i>\u0000 </sub> ranges from 0.68848 to 0.70068, with ε<sub>Nd</sub>(<i>t</i>) ranging from +1.4 to +3.7; and <i>t</i>\u0000 <sub>DM2</sub> ranges from 629 to 817 Ma, indicating magma derived from newly formed young crustal material after the closure of the Mongolian-Okhotsk Ocean. The volcanic rocks of the Guanghua Formation have characteristics that are similar to I-Type granites, with silica and alkali enrichment and Ca and Mg depletion. They also show a right-skewed “V”-shaped pattern in their REE distribution curves, with a strong negative Eu anomaly. The zircon <sup>176</sup>Hf/<sup>177</sup>Hf ratios range from 0.282887 to 0.282986, with an average <i>ε</i>\u0000 <sub>Hf</sub>(<i>t</i>) value of +8.78; (<sup>87</sup>Sr/<sup>86</sup>Sr)<sub>i</sub> ranges from 0.70060 to 0.70096, with <i>ε</i>\u0000 <sub>Nd</sub>(<i>t</i>) ranging from +3.0 to +3.8; and <i>t</i>\u0000 <sub>DM2</sub> ranges from 616 to 677 Ma, indicating the partial melting of depleted mantle-derived mafic lower crustal material, influenced by the closure of the Mongolian-Okhotsk Ocean and subduction of the ancient Pacific Plate.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 7","pages":"1653-1681"},"PeriodicalIF":1.4,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144635199","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}
Wei Dang, Menhui Qian, Haikuan Nie, Jun Liu, Kefeng Du, Yubo Feng, Yankai Xue, Xin Zhang
{"title":"Oil Storage Capacity in Organic-Rich Chang 7 Shale, Ordos Basin: Comparing Evaluation Methods and Controlling Factors","authors":"Wei Dang, Menhui Qian, Haikuan Nie, Jun Liu, Kefeng Du, Yubo Feng, Yankai Xue, Xin Zhang","doi":"10.1002/gj.5167","DOIUrl":"https://doi.org/10.1002/gj.5167","url":null,"abstract":"<div>\u0000 \u0000 <p>This study examines the oil storage capacity and controlling factors of organic-rich Chang 7 shale in the Ordos Basin, using multistep Rock-Eval pyrolysis (MREP) and liquid hydrocarbon vapour adsorption (LHVA) techniques. The research evaluates the effectiveness of these techniques in determining oil content and identifies key geological and geochemical factors impacting free and adsorbed oil. Analyses of geochemical, mineralogical, and pore structure characteristics reveal that Chang 7 shale, with high total organic carbon (TOC) content and oil-prone kerogen, along with moderate thermal maturity, is a high-quality hydrocarbon source rock. A strong linear correlation between MREP and LHVA results demonstrate the reliability of both methods for assessing adsorbed oil content, though discrepancies emphasise the impact of hydrocarbon loss during sample preparation. Statistical analysis indicates TOC content (> 2%, with > 4% especially favourable) and thermal maturity (<i>R</i>\u0000 <sub>o</sub> = 0.7%–1.0%) as the critical factors for shale oil accumulation and key indicators for identifying sweet spots. These findings improve the understanding of oil occurrence processes in shale and offer practical insights for optimising shale oil exploration and development.</p>\u0000 </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 9","pages":"2176-2194"},"PeriodicalIF":2.2,"publicationDate":"2025-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145013026","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}