Organic Geochemistry最新文献

{"title":"Obituary for Prof. Dr. Dietrich Welte (1935–2025)","authors":"","doi":"10.1016/j.orggeochem.2025.105047","DOIUrl":"10.1016/j.orggeochem.2025.105047","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"209 ","pages":"Article 105047"},"PeriodicalIF":2.5,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145061217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Secondary alteration and probable sources of oils and condensates in Jurassic reservoirs of the Turpan Depression, Turpan-Hami Basin, NW China","authors":"Bin Cheng ,&nbsp;Guocong Sun ,&nbsp;An Xie ,&nbsp;Jie Sun ,&nbsp;Xinxin Bo ,&nbsp;Xin Tian","doi":"10.1016/j.orggeochem.2025.105052","DOIUrl":"10.1016/j.orggeochem.2025.105052","url":null,"abstract":"<div><div>The identification of secondary alteration processes in Jurassic reservoirs of the Turpan Depression and the contribution of petroleum from Permian sources remains largely unexplored. This study, based on geochemical analyses of representative oil and condensate samples, systematically integrates carbon isotope data, biomarkers, C₅-C₇ light hydrocarbon, and diamondoids compositions to identify secondary alterations and assess the contribution of hydrocarbons derived from Permian source rocks. The results reveal that the Jurassic oil reservoirs of wells Y7 and Qt1 have undergone extensive biodegradation, followed by subsequent oil mixing processes with slight to moderate biodegraded oils and fresh, unaltered oils, respectively. Evaporative fractionation is frequently observed in the Jurassic reservoirs, although the degree of its occurrence varies considerably. Reservoirs in the Shengbei sub-sag experienced more intense alteration compared to those in other sub-sags, with the Sb3 and Sb5 reservoirs exhibiting the highest degrees of alteration. Thermal maturity evaluations, based on saturated, aromatic, and light hydrocarbons, reveal that most samples range from peak to late oil-generation stages. Some light oils and condensates have progressed toward the condensate/wet gas stage because of higher maturity charging events. Correlation analysis indicates the coexistence of three end-member oil and condensate families within the Jurassic reservoirs, those generated from Jurassic coal-measure source rocks, those derived from Jurassic Qiketai source rocks, and those originating from Middle Permian source rocks, further suggesting that the Permian-origin hydrocarbons have made a substantial contribution to the Jurassic reservoirs in some regions, despite being generated at varying thermal maturity stages. Overall, the Jurassic oil reservoirs in the Turpan Depression have undergone multiple secondary alteration processes and experienced complex charging events from both Jurassic and Permian source rocks, resulting in a highly complicated hydrocarbon accumulation mechanisms.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105052"},"PeriodicalIF":2.5,"publicationDate":"2025-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144724532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical implications of the carbon isotope compositions of individual polycyclic aromatic compounds in coals from the Junggar and Ordos basins, NW China","authors":"Ziao Geng ,&nbsp;Meijun Li ,&nbsp;Shuichang Zhang ,&nbsp;Shengbao Shi ,&nbsp;Wenqiang Wang ,&nbsp;Lei Zhu ,&nbsp;Tiantian Li ,&nbsp;Jianfeng Zhang","doi":"10.1016/j.orggeochem.2025.105049","DOIUrl":"10.1016/j.orggeochem.2025.105049","url":null,"abstract":"<div><div>This study analyzes the δ¹³C values of various polycyclic aromatic compounds (PACs), including dibenzofuran, and methyldibenzofurans in two sets of coals from the Junggar and Ordos basins in NW China. The results reveal that the δ¹³C values of individual PACs are primarily influenced by the source of degraded organic matter rather than thermal maturity. The significant differences in δ¹³C values (−11.7 ‰) between dibenzofuran (DBF) and its methylated homologues (MDBFs) imply different sources. DBF is primarily derived from higher plants, while MDBFs have multiple sources from both lichens and higher plants. However, the δ¹³C values of DBF and MDBF in predominantly pyrogenic samples are relatively similar. This is due to two factors: (1) The kinetic isotope effect leads to preferential demethylation of ¹²C-enriched MDBF isomers, and the residual MDBFs are consequently enriched in ¹³C isotopes. The DBF produced by this process is enriched in ¹²C isotope, leading to depletion of δ¹³C for DBF in the combustion products. (2) Greater higher plant than lichen inputs result in higher δ¹³C values of MDBFs also potentially causes lower δ¹³C values in DBF. These two factors combine to produce similar δ¹³C values for DBF and MDBFs in samples heavily affected by wildfires.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105049"},"PeriodicalIF":2.6,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144687102","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry Articles – June 2025","authors":"","doi":"10.1016/j.orggeochem.2025.105048","DOIUrl":"10.1016/j.orggeochem.2025.105048","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"209 ","pages":"Article 105048"},"PeriodicalIF":2.5,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry articles – May 2025","authors":"","doi":"10.1016/j.orggeochem.2025.105043","DOIUrl":"10.1016/j.orggeochem.2025.105043","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"209 ","pages":"Article 105043"},"PeriodicalIF":2.5,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multiple sources of petroleum in the Panyu lower uplift evidenced by catalytic hydropyrolysis of petroleum asphaltenes","authors":"Guangli Wang ,&nbsp;Ying Xu ,&nbsp;Yang Yang ,&nbsp;Zhirong Zhang ,&nbsp;Yuhong Liao","doi":"10.1016/j.orggeochem.2025.105045","DOIUrl":"10.1016/j.orggeochem.2025.105045","url":null,"abstract":"<div><div>Catalytic hydropyrolysis (HyPy) is an effective method for the release of covalently bound biomarkers from geo-macromolecules (e.g., kerogen or asphaltenes). It is particularly valuable for samples that lack geochemical proxies resulting from extensive maturation or secondary alteration. In this study, HyPy was carried out on asphaltene fractions isolated from crude oils collected from 10 reservoirs of various depths in the Panyu lower uplift in the central Pearl River Mouth Basin, South China Sea. Significant quantities of biomarkers and polycyclic aromatic hydrocarbons (PAHs) were released, and their molecular and isotopic compositions were obtained. The results suggest that these bound compounds were not affected by secondary alteration processes, such as biodegradation in shallow reservoirs or water washing in deeper ones. The δ¹³C values of the HyPy products were 1.2 ‰–2.2 ‰ more enriched than those of the original bulk oils, and are inconsistent with traditional δ¹³C patterns (the asphaltene fraction generally has the most enriched δ¹³C value among petroleum fractions). These reservoirs, therefore, may represent a composite petroleum system involving contributions from multiple source rocks rather than a single source as previously interpreted. This hypothesis is also supported by the molecular and biomarker signatures of the products, which showed elevated proportions of C₁₁–C₁₆ <em>n</em>-alkanes and C₁₉ tricyclic terpanes, and a marked dominance of 24-ethylcholestanes (ranging from 52 % to 79 % of total steranes), significantly exceeding the C₂₇ and C₂₈ homologues. A substantial input of organic matter from vascular plants, much higher than that of the presumed source rocks of the Eocene Wenchang Formation, was found. Therefore, the earlier petroleum charges to the Panyu lower uplift may be associated with the Eocene–Oligocene Enping Formation interbedded with coaly source rock intervals. In contrast, the maltenes of the oil samples were rich in 4-methylsteranes, dinosteranes, and triaromatic dinosteroids, as well as minor oleananes, which closely resemble the biomarker signatures of lacustrine source rocks from the Eocene Wenchang Formation. These findings support a dual contribution to the petroleum reservoirs across the Panyu lower uplift, where the major oils concerned with the coaly source rocks of the Enping Formation and the lacustrine shale source rocks of the Wenchang Formation were likely responsible for potential large hydrocarbon accumulations.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105045"},"PeriodicalIF":2.6,"publicationDate":"2025-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144489968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the reliability of H-brGDGTs as terrestrial paleothermometers in Plio-Pleistocene fluvio-lacustrine deposits from Northern China","authors":"Shi Qian ,&nbsp;Huan Yang ,&nbsp;Jie Wu ,&nbsp;Shucheng Xie ,&nbsp;Qinmian Xu","doi":"10.1016/j.orggeochem.2025.105046","DOIUrl":"10.1016/j.orggeochem.2025.105046","url":null,"abstract":"<div><div>Branched glycerol monoalkyl glycerol tetraethers (brGMGTs, or H-brGDGTs), lipids that occur widely in anoxic sediments of peatlands, lakes, and oceans, have been proposed as new tools for paleotemperature reconstructions in lakes and peatlands. However, their reliability has not been widely assessed, particularly in sediment cores. Here, we report the H-brGDGT distributions in the Xiong'an (XA) 3 sediment core from North China, spanning 5.5 million years (Ma), to evaluate their reliability as a terrestrial paleothermometer. Seven major H-brGDGTs are consistently abundant throughout the sediment core. Their isomerization index (IR_H) values, characteristic of river and lake environments, suggest H-brGDGTs were predominantly produced <em>in situ</em> with negligible soil input. Their abundances and distributions are strongly related to a widely used paleothermometer, MBT′_5ME (methylation index of branched tetraethers for 5-methylated branched GDGTs), likely indicating their temperature dependence. An H-brGDGT-based temperature proxy, H-MBT′, which includes only the H-1020c and H-1034b isomers, was found to track temperature in both published modern peat/lake H-brGDGT data set and the XA3 sediment core. H-MBT′ reconstructed temperature trend is consistent with the brGDGT temperature record in the sediment core as well as global climate signals, revealing stable warmth during 5.5–2.6 Ma, abrupt cooling at ∼2.6 Ma coinciding with the onset of Northern Hemisphere Glaciation (NHG), and oscillating decline during 2.2–0 Ma. Our results validate H-brGDGTs as a potential paleothermometer in aquatic systems but highlight the need for the selection of proper H-brGDGT-based temperature proxies and environment-specific calibrations to refine accuracy.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105046"},"PeriodicalIF":2.6,"publicationDate":"2025-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144579680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sulfur ions reduce the activation energy of steranes and terpanes under hydrothermal action","authors":"Rongzhen Qiao,&nbsp;Meijun Li,&nbsp;Donglin Zhang,&nbsp;Hong Xiao","doi":"10.1016/j.orggeochem.2025.105044","DOIUrl":"10.1016/j.orggeochem.2025.105044","url":null,"abstract":"<div><div>Steranes and terpanes, as key biomarkers in oils and source rock extracts, provide valuable information about their biological origins, depositional environment, and thermal maturity. The distribution patterns of steranes and terpanes in ultra-deep oil reservoirs within the Shuntuoguole low uplift are complex. The intensity of hydrothermal activity and the influence of sulfur ions were assessed based on the conversion of “Biphenyl–Dibenzothiophene–Phenanthrene” series compounds. The results reveal that the southern sections of F5, F12, and F4 exhibit relatively strong hydrothermal activity (F number: No. number fault zone). The southern sections of F5, F1, and F4 are more significantly impacted by sulfur ion activity under the hydrothermal action. Studies indicate that sterane and terpene concentrations decrease due to sulfur ion activity under the hydrothermal action. Tricyclic terpanes, cholestanes, C_31-35 homohopanes, C₃₀ hopane, C₂₉ diahopane, and pregnane exhibit low stability under the influence of sulfur ion activity in the hydrothermal action. Notably, although tricyclic terpanes, cholestanes, and pregnane show low stability, they are not preferentially depleted. Combined analysis of the relative Gibbs free energies of C₃₀ diahopane and C₃₀ hopane showed that sulfur ions do not promote pyrolysis by altering the degradation pathways of steranes and terpanes. Instead, sulfur ions likely lower the pyrolysis threshold by reducing the activation energy, preserving the relative stability of steranes and terpanes. This study advances the understanding of organic–inorganic interactions in hydrothermal systems.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105044"},"PeriodicalIF":2.6,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144338788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Occurrence of nucleoside-bacteriohopanepolyol in high latitude soils: evidence of environmental controls on bacterial lipid membrane distributions","authors":"Keith F. O’Connor ,&nbsp;Melissa A. Berke ,&nbsp;Cindy De Jonge ,&nbsp;Ellen C. Hopmans ,&nbsp;Lori A. Ziolkowski ,&nbsp;Darci Rush","doi":"10.1016/j.orggeochem.2025.105026","DOIUrl":"10.1016/j.orggeochem.2025.105026","url":null,"abstract":"<div><div>Recently, the analysis of non-derivatised bacteriohopanepolyols (BHPs) by ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS²) revealed a broad structural diversity in this lipid class. Multiple unique BHPs with nucleoside-type polar head groups (Nu-BHPs) were identified in soils. Nu-BHPs had previously been identified in high abundances in soil organic matter, but only by analysing acetylated BHPs, which hindered their structural elucidation. In this study, we apply the UHPLC-HRMS² analysis method for the first time to a soil transect to re-examine the distribution of Nu-BHPs, their environmental dependencies, and their proxy potential. The presence and distribution of Nu-BHPs was examined in 17 surface soils along a ∼800 km transect in northern Alaska. Our results indicate that certain Nu-BHPs show significant correlation with environmental parameters, such as temperature and soil pH. The variation in 9 Nu-BHPs is captured using a novel ratio, and a regional calibration for warmest quarter soil temperature (WQST) was developed using a linear regression approach (R² = 0.72). Other calibrations developed for summer air and mean annual temperatures also show strong positive correlations. As BHPs are ubiquitous in soils globally, this study highlights the potential benefit of complementing established organic proxies for soil pH and temperature (e.g., branched tetraether lipids) with calibrations based on Nu-BHPs. Nevertheless, the mechanism behind the environmental dependencies of these BHPs remains unknown. Further work to explore the proxy potential as well as the bacterial sources of these lipids should be undertaken, for instance by sampling soils along relevant (soil pH and temperature) gradients.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"208 ","pages":"Article 105026"},"PeriodicalIF":2.6,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144272111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Abundance of phytanyl and n-alkyl toluenes in petroleum from the Lower Saxony Basin (Germany) provides information on maturity, palaeosettings and sources","authors":"Georg Scheeder,&nbsp;Christian Ostertag-Henning,&nbsp;Martin Blumenberg","doi":"10.1016/j.orggeochem.2025.105025","DOIUrl":"10.1016/j.orggeochem.2025.105025","url":null,"abstract":"<div><div>Alkyl benzenes and toluenes are common in petroleum and shales. In addition to the series of <em>n</em>-alkylated benzenes and toluenes, the phytanyl toluene (and −benzene) is often abundant. In the present study, <em>n</em>-alkyl toluenes and phytanyl toluene were detected in more than 180 petroleum oils with different maturation histories and from two different source rocks, the Jurassic Posidonia Shale and the Cretaceous Wealden Shale (from the Lower Saxony Basin; Germany). A novel ratio of C₂₂-C₂₄ <em>meta</em>-substituted <em>n</em>-alkyl (combined in the ratio as “<em>n</em>”) to phytanyl (“<em>iso</em>”) toluenes is proposed as a thermal maturity indicator. Our data show that the relative proportion of phytanyl toluene to <em>n</em>-alkyl toluenes systematically decreases with maturity and therefore the “<em>n</em>/(<em>n</em> + <em>iso</em>)” toluene index increases. The relative change is due to both the processes of catalytic formation of <em>n</em>-alkyl toluenes and destruction of phytanyl toluene. The applicability of this ratio was confirmed using closed gold capsule pyrolysis maturation experiments with Posidonia Shale (for a maturation range from EASY%Ro of 0.78 to 1.4 %). The correlation is most pronounced in petroleum produced from the Posidonia Shale. For oils from the Wealden shales, the correlation is less clear due to the generally low phytanyl toluene contents. Comparisons of the “<em>n</em>/(<em>n</em> + <em>iso</em>)” toluene index with maturity-dependent biomarker ratios indicated its potential to record thermal maturity over a wide range. The occurrence of phytanyl toluene also appears to record a poorly understood (microbial) source, which was more abundant in the marine-euxinic depositional system of the Posidonia Shale than that of the brackish-marine Wealden shales.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"207 ","pages":"Article 105025"},"PeriodicalIF":2.6,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144123964","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}