Organic Geochemistry最新文献

{"title":"Geochemistry Articles – August 2025","authors":"","doi":"10.1016/j.orggeochem.2025.105079","DOIUrl":"10.1016/j.orggeochem.2025.105079","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"211 ","pages":"Article 105079"},"PeriodicalIF":2.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733062","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 – July 2025","authors":"","doi":"10.1016/j.orggeochem.2025.105055","DOIUrl":"10.1016/j.orggeochem.2025.105055","url":null,"abstract":"","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"211 ","pages":"Article 105055"},"PeriodicalIF":2.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145733061","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":"Generation and maturation of diamondoids for petroleum reservoirs in the Tarim Basin, NW China","authors":"Shuang Yu ,&nbsp;Yuanyuan Bian ,&nbsp;Chenxi Zhou ,&nbsp;Wenyu Huang ,&nbsp;Haizu Zhang ,&nbsp;Zhongyiao Xiao ,&nbsp;Changchun Pan","doi":"10.1016/j.orggeochem.2025.105080","DOIUrl":"10.1016/j.orggeochem.2025.105080","url":null,"abstract":"<div><div>Diamondoid generation and maturation behaviors in natural system remain unresolved. Oils/condensates from the Tarim Basin have elevated diamondoid concentrations. Diamondoid concentrations and maturity ratios for 167 oils/condensates from the Tarim Basin were used to document diamondoid generation and maturation in combination with the maturity frameworks of the deep source rocks. These samples include 29 Kuqa condensates from the Kuqa Depression, and 45 Tabei oils/condensates from the Tabei (Northern Tarim) Uplift and neighboring slope area and 93 Tazhong oils/condensates from the Tazhong (Central Tarim) Uplift and neighboring slope area of the cratonic region. The main observations are: (1) Concentration distributions of 4- + 3-methyldiamantane (4 + 3MD) for the Kuqa condensates and the Tabei and Tazhong oils/condensates are consistent with the maturity frameworks of the Triassic source rocks in the Kuqa Depression and the Cambrian source rocks in the cratonic region of the Tarim Basin from basin modeling, respectively. Concentrations of total adamantanes (As), total diamantanes (Ds) and 4 + 3MD have a close linear positive correlation with each other for these studied oils/condensates. These results suggest that diamondoids were generated at increasing rate with increasing maturity of these deep source rocks and did not decompose in these source rocks at maturity up to %Ro 4.0–4.5 in the Tarim Basin. (2) The effectiveness of the nine diamondoid maturity ratios (MAI, MDI, DMAI-1, DMAI-2, TMAI-1, TMAI-2, DMDI-1, DMDI-2 and EAI) increases, while the influence of source facies on these maturity ratios, in particular on the last three ratios (DMDI-1, DMDI-2 and EAI) decreases with increasing maturity of the source rocks based on Pearson correlation coefficients (<em>r</em>) between each other among the nine maturity ratios and concentrations of As, Ds and 4 + 3MD and As/Ds ratio. (3) The maturities of the deep source rocks for the studied samples decrease in the sequence of the Kuqa condensates &gt; the Tazhong oils/condensates &gt; the Tabei oils/condensates based on the maximum values and ranges of the nine diamondoid maturity ratios and the <em>r</em> values between each other among the nine maturity ratios, concentrations of As, Ds and 4 + 3MD. and the As/Ds ratio. This sequence provides a constraint in basin modeling on the relative maturities of the Triassic source rocks in the Kuqa Depression and Cambrian source rocks in the cratonic region.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"211 ","pages":"Article 105080"},"PeriodicalIF":2.5,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145098726","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":"Organic matter enrichment in black shales: How important are clay minerals?","authors":"Bei Liu ,&nbsp;Maria Mastalerz ,&nbsp;Juergen Schieber ,&nbsp;David Bish","doi":"10.1016/j.orggeochem.2025.105058","DOIUrl":"10.1016/j.orggeochem.2025.105058","url":null,"abstract":"<div><div>Clay minerals possess large surface areas and have long been thought to contribute to organic matter (OM) enrichment in black shales through the adsorption of OM in clay mineral interlayers. In this study, we review OM types and their modes of occurrence in fresh muddy sediments and their lithified counterparts, black shales, as well as the potential role of clay-OM interactions during black shale deposition. Solid OM (tens of nanometer- to hundreds of micrometer-scale particles) is the dominant form of OM in fresh muddy sediments and black shales and is too large to be accommodated in the interlayer region (&lt;5 nm) of smectite and interstratified illite/smectite. For this reason alone, it is implausible that an interlayer adsorption mechanism would be responsible for bulk organic carbon preservation in black shales. OM and clay minerals in nature are instead physically associated via the formation of floccules and aggregates, which serve to retard the microbial degradation of OM. The association of OM and clay minerals argues for a reevaluation of the impact of clay minerals on organic carbon preservation in the sedimentary systems and the global carbon cycle.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105058"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145218389","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":"Environmental indications and controls of bacterial membrane lipids in a tropical peatland from Panama","authors":"V. Schneider ,&nbsp;J.M.W. Antoszkiewicz ,&nbsp;M. Vreeken ,&nbsp;S.M.K. Cheung ,&nbsp;Z. Zeng ,&nbsp;D.Agudo Atencio ,&nbsp;A.V. Gallego-Sala ,&nbsp;J. Blewett ,&nbsp;R.D. Pancost ,&nbsp;B.D.A. Naafs","doi":"10.1016/j.orggeochem.2025.105094","DOIUrl":"10.1016/j.orggeochem.2025.105094","url":null,"abstract":"<div><div>Lipid biomarkers are widely used to trace microbial activity and environmental changes, yet gaps remain in our understanding of their environmental occurrence, including in tropical peatlands. We analyzed the bacterial lipid abundance in a series of 2 m long peat cores from the Republic of Panama, focusing on the diether glycerol with C_15:0 <em>n</em>-alkyl chains (C_15:0 DEG), 13,16-dimethyl octacosanedioic acid (<em>iso</em>-diabolic acid: <em>iso</em>-DA), and branched Glycerol Dialkyl Glycerol Tetraethers (brGDGTs) and combined these with novel genomic data from the same cores. In addition to understanding these compounds’ environmental occurrence, we present the first environmental insights into the co-occurrence of brGDGT-Ia with its potential precursors C_15:0 DEGs and <em>iso</em>-DA. Our results show that <em>iso</em>-DA is found only in the occasionally dry top peat layer and is absent in water-saturated peat horizons. We suggest that the production of <em>iso</em>-DA in this peatland dependents on oxygen availability, likely due to the metabolism of the source organisms and consistent with limited available culture data of acidobacteria. In contrast, C_15:0 DEGs and brGDGTs (mainly in the form of brGDGT-Ia) persist across all depths with increasing concentrations at greater depths. Although these contrasting trends in abundance could reflect the greater persistence of ether lipids relative to acyl/acid lipids due to differences in preservation rates, they could also suggest that <em>iso</em>-DA is not a major precursor in the biosynthetic pathway of brGDGTs in these settings. When combined with novel genomic data, we show that acidobacteria, one of the few known <em>iso</em>-DA and brGDGT producers, were detected at all sites and depths, forming a stable proportion of the prokaryotic community. Their consistent presence aligns more with the brGDGT and C_15:0 DEG distribution than <em>iso</em>-DA. Combining the results from our study with experimental evidence, it appears that multiple pathways for brGDGT biosynthesis exist in tropical peats, with the phylogenetic and environmental control on their expression yet to be elucidated.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105094"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145620423","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":"Hopanoid breakdown products (HBPs) and their influence on tetracyclic and tricyclic terpane (cheilanthane) oil-source rock parameters","authors":"Tharika Liyanage ,&nbsp;Lennart M. van Maldegem ,&nbsp;Janet Hope ,&nbsp;Philippe Schaeffer ,&nbsp;Pierre Adam ,&nbsp;Hans Peter Nytoft ,&nbsp;Dianne Edwards ,&nbsp;Jochen Brocks","doi":"10.1016/j.orggeochem.2025.105085","DOIUrl":"10.1016/j.orggeochem.2025.105085","url":null,"abstract":"<div><div>Tricyclic and tetracyclic terpane ratios are used as biomarker proxies for depositional environments and to classify crude oils and source rocks. However, the biological precursors and diagenetic drivers of these proxies are not well understood. This study reports on the discovery of tricyclic and tetracyclic breakdown products of pentacyclic hopanoids that co-elute with 14α-C₁₉ and βα-C₂₀–C₂₂ cheilanthanes and C₂₄ tetracyclic terpane in gas chromatograms. This includes hopanoid breakdown products (HBPs) that are identical to 14α-C₁₉ cheilanthane and C₂₄ tetracyclic terpane, biomarkers that are commonly used as indicators of terrigenous organic matter in source rocks and their derived hydrocarbon products. These HBPs were generated by pyrolysis of C₃₀ diplopterol, a common compound found in the cell membranes of almost all hopanoid-producing bacteria, some lichens and higher plants. HBPs are common in rock-extracted bitumens and crude oils from the Neoproterozoic to the Cenozoic and across a wide range of thermal maturities. Comparison of the relative abundance of HBPs and cheilanthanes against commonly used tricyclic and tetracyclic terpane parameters shows that HBPs can drive or strongly influence terpane-based paleoenvironmental proxies. This study begins to rationalise why some of these parameters indicate specific depositional environments and proposes new ratios that quantify the impact of HBPs on biomarker proxies.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105085"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145474236","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":"Paleoenvironmental and diagenetic effects on porphyrin distributions in the End-Devonian Exshaw Formation, Western Canada","authors":"Sanjukta Dhar,&nbsp;James M. Fulton","doi":"10.1016/j.orggeochem.2025.105090","DOIUrl":"10.1016/j.orggeochem.2025.105090","url":null,"abstract":"<div><div>Porphyrin distributions were studied across 20 locations in the Western Canada Sedimentary Basin, particularly focusing on sediments deposited at the base of the Exshaw Shale, spanning the Devonian-Carboniferous boundary and contemporaneous with the Hangenberg mass extinction. Locations along a north–south transect represent thermally immature kerogen, while locations from east to west show a gradient of increasing thermal maturity. The study aimed to identify regional variability in <em>syn</em>-depositional environmental conditions and post-burial diagenesis influencing porphyrin preservation along the two transects. The relative abundance of three major categories of vanadyl porphyrins – cycloalkanoporphyrins, bicycloalkanoporphyrins, and etioporphyrins from the different sites exhibit notable spatial diversity, with the primary factor affecting their distribution being thermal maturity. Effects of paleoredox conditions and degree of organic matter decomposition were evaluated using trace element enrichments, thermal Rock Eval data, sterane and homohopane maturity indices.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105090"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575910","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":"Magma-induced thermal alteration in Devonian organic-rich rocks (Paraná Basin, Brazil): molecular transformations and clay-catalyzed maturation","authors":"Lucas Pinto Heckert Bastos ,&nbsp;René Rodrigues ,&nbsp;Carmen Lucia Ferreira Alferes ,&nbsp;Debora Bonfim Neves da Silva ,&nbsp;Danielle da Costa Cavalcante ,&nbsp;Guilherme Brugger Lemos ,&nbsp;Sergio Bergamaschi ,&nbsp;Egberto Pereira","doi":"10.1016/j.orggeochem.2025.105083","DOIUrl":"10.1016/j.orggeochem.2025.105083","url":null,"abstract":"<div><div>Several studies have examined how high heating rates influence the molecular composition of organic matter, particularly in geological settings where magma interacts with organic-rich rocks. In Brazil, such interactions have been extensively documented in the Paraná Basin. However, the behavior of geochemical proxies under intense thermal stress, as well as the natural chemical products generated through the thermal cracking of organic matter, are not yet fully understood. In this study, a combination of bulk and molecular geochemical data from 233 m of Devonian strata in the Paraná Basin—intersected by two dolerite sills measuring 3.0 m and 0.86 m in thickness—was used to assess the extent and effects of magmatic heating on originally immature organic matter. The work includes a large dataset of total organic carbon and Rock-Eval pyrolysis along with thermal-maturity-related molecular geochemical proxies. The thermal evolution of organic matter was better assessed using methylated aromatic hydrocarbons, as saturate hydrocarbons are less resistant to high temperatures and may not respond well to rapid heating. The borehole profile was subdivided into four stages (I–IV) based on the response of geochemical proxies to thermal stress. The intermediate zone (Stages II and III) showed elevated MPI-1 (methylphenanthrene index) values and distorted saturate hydrocarbon ratios. Additionally, samples from this high thermal stress zone of the sills showed a significantly higher abundance of dimethyl alkanes—compared to less altered samples dominated by monomethyl alkanes. Multiple alkyl substitutions have been naturally favored in high-temperature zones by acidic clay mineral catalysis and sustained thermal stress, potentially from percolating hydrothermal fluids. The thermal alteration zone exceeds the expected halo from the two sills intersecting the borehole, which is interpreted as resulting from the percolation of hydrothermal fluids and/or a complex igneous body geometry.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105083"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145128188","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":"Isolation of 2,3,6- & 2,3,4-trimethyl aryl isoprenoids using argentation silica gel column chromatography for compound-specific isotopic analysis","authors":"Tian Ao ,&nbsp;Xianxin Meng ,&nbsp;Hong Lu ,&nbsp;Youping Zhou ,&nbsp;Ping’an Peng","doi":"10.1016/j.orggeochem.2025.105089","DOIUrl":"10.1016/j.orggeochem.2025.105089","url":null,"abstract":"<div><div>Trimethyl aryl isoprenoids (TMAIPs) provide significant insights into the biological and geochemical processes in modern and ancient aquatic environments. Obtaining carbon isotope (δ¹³C) data for these carotenoid-derived biomarkers can greatly enhance their interpretative value, as non-sulfur bacterial sources can be distinguished by their carbon isotope compositions from sulfur bacterial sources. However, δ¹³C measurement for individual TMAIPs is particularly challenging due to their low relative abundance in complex hydrocarbon mixtures. We present an argentated (with silver nitrate) silica gel column chromatography (Ag-CC)-based method for isolation of TMAIPs in the aromatic hydrocarbon fraction of crude oils. The effectiveness of the method was demonstrated by the successful isolation of the co-occurring 2,3,6- &amp; 2,3,4- TMAIPs in two crude oil samples sourced from the hypersaline lacustrine environment of the Jianghan Basin in China, enabling reliable δ¹³C and δ²H analysis for the TMAIPs and other target biomarkers such as <em>n</em>-alkyl benzenes. The δ¹³C values of the 2,3,6-TMAIPs (−19.4‰ to −17.2‰) were found to be significantly higher than those of the 2,3,4-TMAIPs (−25.9‰ to −20.8‰), but the δ²H values of the 2,3,6-TMAIPs (−187.4‰ to −171.7‰) were significantly lower than those of the 2,3,4-TMAIPs (−140.3‰ to −106.7‰). Future work should be focused on the elucidation of the controlling factors of the TMAIPs isotopic compositions (promised by the new technique) and their broader geological implications.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105089"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575909","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":"Composition and distributional patterns of C3- and C4-alkylbenzenes in oils and source rocks from Meso–Neoproterozoic to Cenozoic","authors":"N.V. Oblasov ,&nbsp;I.V. Eftor ,&nbsp;I.V. Goncharov ,&nbsp;S.V. Fadeeva","doi":"10.1016/j.orggeochem.2025.105091","DOIUrl":"10.1016/j.orggeochem.2025.105091","url":null,"abstract":"<div><div>This study presents the results of an investigation into the distribution patterns of C₃- and C₄-alkylbenzenes in oils derived from hydrocarbon source rocks of varying geological age and origin. The study utilized analytical results from 515 oil samples collected from wells at 199 fields across various petroleum basins of Eurasia, most of which are located in Russia (including the West Siberian Basin, Siberian Platform (or Eastern Siberia), Northwestern Greater Caucasus, Middle Caspian, Sakhalin, Volga-Ural Basin, Timan-Pechora Basin, and the Baltic Basin (Kaliningrad), Belarus (Pripyat Trough), and Africa (Eastern Algeria). These samples cover a wide range of oil ages and genetic diversity. The obtained results significantly advance our understanding of the relationships between C₃- and C₄-alkylbenzene compositions in oils and the following factors: redox conditions during deposition of the source organic matter, photic zone anoxia in the depositional basin, type of primary producers, age of source rocks, and catagenesis. Linear discriminant analysis (LDA) was applied to characterize C₃- and C₄-alkylbenzene distributions in two variants based on: 1) genetic grouping of oils and 2) grouping by Pr/Ph values and <em>tert</em>-butylbenzene content. To enable global application of LDA models, we publish key foundational data − including analytical workflow, minimum/maximum relative concentration ranges, and discriminant function coefficients − enabling researchers to apply this framework to any petroleum basin worldwide. C₄-alkylbenzenes are benzene derivatives of terpenoids and may have direct biological origins or originate from higher molecular weight components (e.g., aryl carotenoids). Consequently, they exhibit superior discriminative power for classifying oils into genetic groups compared to C₃-alkylbenzenes. Oils with the most distinctive C₄-alkylbenzene composition originate from (1) the Bazhenov Formation (West Siberia), (2) Domanik deposits of the Volga-Ural and Timan-Pechora basins, (3) non-marine Jurassic sequences in Western Siberia and the Greater Caucasus northwest, and (4) reservoirs of the Nepa-Botuoba Anteclise (Siberian Platform). The study revealed significant concentrations of <em>tert</em>-butylbenzene, which were detected in oils from: the Baikit Anteclise (Riphean age), Baltic Syneclise (Cambrian–Ordovician–Silurian), selected Algerian fields (Silurian–Devonian) and in isolated Palaeozoic-sourced oils of Western Siberia. Components that have a decisive influence on the position of the oils in the discriminant function coordinates were identified; these components can characterize source organic matter, its age, and redox conditions.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"210 ","pages":"Article 105091"},"PeriodicalIF":2.5,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145575911","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}