Organic Geochemistry最新文献

{"title":"Sources of bacterial 3-hydroxy fatty acids in Liangzihu Lake from central China: Implications for paleoclimate reconstruction","authors":"Honghai Wang ,&nbsp;Yi Yang ,&nbsp;Canfa Wang ,&nbsp;Shucheng Xie","doi":"10.1016/j.orggeochem.2025.104949","DOIUrl":"10.1016/j.orggeochem.2025.104949","url":null,"abstract":"<div><div>Bacterial 3-hydroxy fatty acids (3-OH-FAs) derived proxies are new tools for paleoclimate reconstruction. However, their effectiveness in temperature reconstruction in lake environments remains unclear. We investigated the compositions of 3-OH-FA and bacterial community across a transect from nearshore soils to water column and surface sediments in the center of Liangzihu Lake (LZH), central China, to elucidate the origins of 3-OH-FA within the lake environments and to evaluate their potential as temperature proxies. The 3-OH-FA in lake center sediments was found to be produced in situ, which can be further supported by the 16S rRNA gene sequencing results. We quantified the input of soil organic matter (OM) in the lake using a δ¹³C_org based two-end member model. The contribution of soil OM ranged from above 50% in nearshore sediments to &lt; 20% in the lake center, reflecting a decreased influence of soil contribution offshore. Moreover, 3-OH-FA based temperature proxies, RAN₁₃ (the ratio of <em>anteiso</em> to <em>normal</em> C₁₃) and RIN₁₇ (the ratio of <em>iso</em> to <em>normal</em> C₁₇) were examined. The temperature estimates derived from the RAN₁₃ were close to the meteorological temperature, whereas the temperature estimates based on RIN₁₇ are lower than the measured temperature. Therefore, our study not only elucidates the sources of 3-OH-FAs within LZH but also evaluates the reliability of associated temperature indices, which provides insights into temperature reconstruction in lake sediment cores.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104949"},"PeriodicalIF":2.6,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474541","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":"Structural properties of organic matter in marine-continental transitional shales and impacts on methane accumulation","authors":"Zhen Qiu ,&nbsp;Dongjun Song ,&nbsp;Jingyu Zhang ,&nbsp;Qin Zhang ,&nbsp;Wen Liu ,&nbsp;Weiliang Kong ,&nbsp;Guangyin Cai ,&nbsp;Wanli Gao ,&nbsp;Tianquan Qu","doi":"10.1016/j.orggeochem.2025.104946","DOIUrl":"10.1016/j.orggeochem.2025.104946","url":null,"abstract":"<div><div>The chemical structure characteristics of organic matter (OM) in marine-continental transitional (MCT) shales and the controls on shale gas accumulation were revealed through analysis of Raman spectroscopy, infrared spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and CO₂ adsorption tests on the Lower Permian Shan-2 shale OM samples from the eastern margin of the Ordos Basin. Organic matter in the high-mature shale is enriched in aromatic groups, with a noticeable condensation and polymerization of the chemical structure after ∼3.0 %R_mc (Raman-based R_o). As %R_mc increases from 2.30 to 3.42, the position of the (002) peak from the stacking of aromatic layers increases from 25.15° to 25.88° in XRD spectra, the spacing between aromatic layers (d₀₀₂) decreases from 0.3540 nm to 0.3444 nm, the calculated graphitization degree (level of OM transforming into graphite) gradually increases, and the carbon layers in the OM evolve from a chaotic shape to a better-oriented state in TEM images, directly indicating an elevated graphitized level. Release of heteroatoms from OM results in reduced average lateral size (L_a) and stacking height (L_c) of the aromatic layer, reaching minimum values at ∼3.0 to 3.2 %R_mc. The stacking of aromatic layers forms some organic micropores, as evidenced by similar micropore size distribution between OM and bulk shale samples, possibly favoring methane accumulation. These findings provide new insights into the factors that affect the gas accumulation characteristics in MCT shales.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104946"},"PeriodicalIF":2.6,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464518","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":"Chemodiversity of soil dissolved organic matter complementally improved by stepwise elution and electrospray ionization modes","authors":"Shasha Zhuo,&nbsp;Rong Qin,&nbsp;Qing-Long Fu","doi":"10.1016/j.orggeochem.2025.104965","DOIUrl":"10.1016/j.orggeochem.2025.104965","url":null,"abstract":"<div><div>The chemodiversity of dissolved organic matter (DOM) molecules can affect the biogeochemical cycling of carbon and nitrogen in terrestrial and aquatic environments. In this study, the negative and positive ion modes of electrospray ionization (ESI(−) and ESI(+), respectively) coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were employed to reveal the chemical composition of seven soil DOM isolates by stepwise elution using different methanol/water solvents. The intensity percentage of CHON molecules in soil DOM detected in the ESI(+) mode was 4.6%–47.3% higher than that for the ESI(−) mode. The O/C ratio, H/C ratio, and the nominal oxidation states of the carbon value of soil DOM molecules linearly correlated (<em>R</em>² &gt; 0.8 for 72% number of stepwise eluted DOM isolates) with the increasing volume of methanol in the SPE elution solvents in dual ion modes, demonstrating the selective fractionation of oxygen-rich and highly polar molecules by methanol-poor solvents. This polarity-dependent fractionation is expected to be universal across different soils. These results suggest that combining the ESI(−) and ESI(+) modes with stepwise elution enables the comprehensive characterization of soil DOM composition, favouring the in-depth understanding of the critical roles of DOM in the biogeochemical cycles of carbon and nitrogen.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104965"},"PeriodicalIF":2.6,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143552904","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 characteristics of ultra-deep natural gases","authors":"Mingming Jiang ,&nbsp;Quanyou Liu","doi":"10.1016/j.orggeochem.2025.104964","DOIUrl":"10.1016/j.orggeochem.2025.104964","url":null,"abstract":"<div><div>As a clean energy source, natural gas occurs at various depths. Natural gas exploration targets have shifted from shallow to ultra-deep reservoirs. Despite the considerable potential of ultra-deep exploration, its development remains limited. To accelerate and improve the exploration of ultra-deep natural gas, it is essential to thoroughly understand the characteristics and origins. Analyzing the geochemical characteristics of both hydrocarbon and non-hydrocarbon gases from ultra-deep reservoirs (depth &gt; 6 km) across various global basins helps identify and classify their characteristics and origins. These gas pools typically contain helium in concentrations below 0.02% or is absent, with hydrogen generally below 2%, indicating that ultra-deep reservoirs may not serve as significant reservoirs for He and H₂. For hydrocarbon gas genesis, thermogenesis is predominant, with illustrative examples from different basins. Concerning CO₂ origins, inorganic processes such as thermochemical sulfate reduction (TSR) and magmatic CO₂ are prevalent, while organic and mixed origins, including organic matter degradation, are less common. The primary origin of H₂S is TSR, with the Mississippi Salt Basin being an exception due to possible contamination from inorganic volcanic gases interacting with hydrocarbon accumulations. Nitrogen’s origin is mainly related to the thermal evolution stage of source rocks. Understanding these gas characteristics provides valuable theoretical insights, which can guide the future exploration and development of ultra-deep natural gas and non-hydrocarbon gases.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104964"},"PeriodicalIF":2.6,"publicationDate":"2025-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464516","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":"Dual-pressure pyrolysis apparatus unravelling how fluid and lithostatic pressure matter in hydrocarbon expulsion","authors":"Weijiao Ma,&nbsp;Yunpeng Wang,&nbsp;Jinzhong Liu,&nbsp;Jinbu Li","doi":"10.1016/j.orggeochem.2025.104932","DOIUrl":"10.1016/j.orggeochem.2025.104932","url":null,"abstract":"<div><div>Improvement in thermal simulation technology will increases the accuracy of predictive geochemistry. A dual-pressure pyrolysis apparatus was developed, to precisely control the fluid pressure and lithostatic pressure during simulated source rock maturation. Two series of pyrolysis experiments were carried out, simulating the same generation process but different expulsion fluid pressure condition. Episodic hydrocarbon expulsion from source rocks under controlled lithostatic pressure and fluid pressure was for the first time observed through thermal simulation experiments. The results were applied to (1) hydrocarbon expulsion efficiency (HEE) analysis, and (2) compositional analysis of oil and gas expelled under different pressures. Results show that HEE is strongly influenced by both fluid and lithostatic pressures. If the oil discharged during depressurization and normal pressure is taken into account, the calculated HEE was 2–31 times the HEE that only considers the high fluid pressure expelled oil. Compared with previous experimental results, HEE under controlled dual pressure is also lower. Therefore, before applying the results of thermal simulation experiments to unconventional and deep oil/gas evaluation, sufficient attention should be paid to the pressure conditions of the experiments. Within the oil window, when the temperature and hydrostatic pressure of source rocks are dropped due to tectonic events such as uplift, they can discharge more oil and gas than before uplift, as a consequence of adjustment of over-pressured fluid to re-equilibrate to the adjacent hydrostatic conditions. In addition, during pressure and temperature reduction, the expelled fluids have a higher gas to oil ratio. This helps to indicate that sedimentary basins that experienced tectonic events still have great exploration potential. The temperature program, pressure setup, expulsion conditions in the two-series experiments is a tentative work tested on a representative source rock from the Triassic Yanchang Formation (Ordos Basin), indicating that control of fluid and lithostatic pressure are essential for improving the accuracy of thermal simulation predictions. The dual-pressure pyrolysis apparatus has high exploration relevance, particularly when quantitative results are integrated with the depositional, tectonic and thermal histories of specific source rocks.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104932"},"PeriodicalIF":2.6,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143464517","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":"Molecular and isotope characterization of hydrocarbon products from organic-sulfur-rich mudstones during closed hydrous-pyrolysis","authors":"Jaime Cesar ,&nbsp;Julito Reyes ,&nbsp;Omid H. Ardakani ,&nbsp;Levi J. Knapp","doi":"10.1016/j.orggeochem.2025.104963","DOIUrl":"10.1016/j.orggeochem.2025.104963","url":null,"abstract":"<div><div>A series of mudstones with varying organic sulfur content were subjected to hydrous pyrolysis and the produced oil and gas were analyzed. The samples come from the late Devonian Duvernay Formation (Canada), the late Miocene Onnagawa Formation (Japan), and the early Jurassic Gordondale Member of the Fernie Formation (Canada), in order of increasing organic sulfur content. Comparison of molecular parameters in the produced oils and residual extracts showed that these have almost identical values, with linear correlation near 1:1, except for polycyclic aromatics such as alkylphenanthrenes and alkyldibenzothiophenes. The excellent correlation suggests that in an ideal scenario, in the absence of long-distance migration, hydrocarbon mixing, and secondary alteration, produced oils and residual bitumen would have very similar molecular properties. In addition, for the same %VR_eqv, samples with higher sulfur content exhibit an apparent higher thermal maturity according to molecular ratios such as Pr/<em>n</em>C₁₈ and C₃₀Hopane/C₃₀Moretane. Generated gases showed source effects on their molecular and carbon isotope composition for the maturity interval analyzed herein (0.57 to 1.42 % VR_eqv). H₂S gas was generated only from the Gordondale samples and the isotope values are presented in this study.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"202 ","pages":"Article 104963"},"PeriodicalIF":2.6,"publicationDate":"2025-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143438187","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":"Aromatic carotenoids and their aryl isoprenoid derivatives in the early Paleozoic rocks and crude oils of the Tarim Basin, China","authors":"Huiyuan Yang ,&nbsp;Jiaquan Zhou ,&nbsp;Jian Ma ,&nbsp;Xingqian Cui","doi":"10.1016/j.orggeochem.2025.104950","DOIUrl":"10.1016/j.orggeochem.2025.104950","url":null,"abstract":"<div><div>Emerging viewpoints suggest dynamic oceanic redox states and notable biotic turnovers in the early Paleozoic, but these aspects remain controversial and require further investigation. The Tarim Basin, which harbors significant marine hydrocarbon source rocks, records a typical phase of marine deposition of the early Paleozoic. In this study, we investigated biomarker compositions and patterns of selected rocks and crude oils of Early Cambrian to Late Ordovician ages from the Tarim Basin, China. Of particular importance are fossilized C₄₀ aromatic carotenoids and their biogenic aryl isoprenoid derivatives, which originate specifically from phototrophic sulfur bacteria inhabiting the euxinic photic zone and are indicative of redox conditions of ancient oceans. The prevalence of 2,3,6-aryl isoprenoids and isorenieratane indicates a biological origin of green sulfur bacteria, implying that the Tarim Basin witnessed euxinia in the subsurface photic zone during a certain period of the early Paleozoic. Along with other biomarker-based proxies, especially steroids and hopanoids, our results from the Tarim Basin suggest the dominance of reducing oceanic water column in the early Cambrian and the late evolution of partially oxygenated water column.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"202 ","pages":"Article 104950"},"PeriodicalIF":2.6,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422292","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 constraints on the hydrocarbon generation and expulsion in source rocks with different primary organic matter compositions: A case study on the Lucaogou Formation in the Jimusaer Sag, Junggar Basin, Northwest China","authors":"Shiju Liu ,&nbsp;Gang Gao ,&nbsp;Xiangyun Shi ,&nbsp;Wenzhe Gang ,&nbsp;Baoli Xiang ,&nbsp;Ming Wang ,&nbsp;Wenzhi Zhao","doi":"10.1016/j.orggeochem.2025.104952","DOIUrl":"10.1016/j.orggeochem.2025.104952","url":null,"abstract":"<div><div>This study investigates the effects of different types of primary organic matters on hydrocarbon generation and expulsion of source rocks. Samples representing three typical source rocks from the Lucaogou Formation in the Jimusaer Sag were collected and analyzed by hydrous pyrolysis, total organic carbon, Rock-Eval, gas chromatography-mass spectrometry, organic petrology, and scanning electron microscopy. Distinct differences in crude oil biomarkers were observed between telalginite- and lamalginite-rich source rocks. Telalginite-rich source rocks exhibit higher abundances of pristane, phytane, <em>β</em>-carotane, gammacerane, and C₂₉ regular steranes, while lamalginite-rich source rocks are characterized by enrichments of C₂₄ tetracyclic terpane, C₂₉ hopane, and C₂₈ regular steranes. These biomarkers provide insights into the primary types of organic matter and their depositional environments with high water salinity of telalginite and low salinity of lamalginite. Hydrous pyrolysis results reveal that telalginite-rich source rocks demonstrate early hydrocarbon generation and a wider oil window than lamalginite-rich source rocks. Compared to lamalginite-rich source rocks, telalginite-rich source rocks produced better quality of crude oil, exhibit a smaller specific surface area of organic matter, and greater development of organic-inorganic pores, which contribute to their higher oil expulsion. These findings are helpful to the understanding of the constraints imposed by different primary organic matters on hydrocarbon generation and expulsion of the source rocks, and the insights have significant implications for exploration and development of the shale oil resources.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"202 ","pages":"Article 104952"},"PeriodicalIF":2.6,"publicationDate":"2025-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143422291","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":"Optimized method for sequential extraction and analysis of polycyclic aromatic hydrocarbons, anhydrosugars and lipid biomarkers in speleothem carbonate and drip waters","authors":"Zhao Wang ,&nbsp;Jonathan D. Smolen ,&nbsp;Michael T. Hren ,&nbsp;Yuval Burstyn ,&nbsp;Isabel P. Montañez ,&nbsp;Jessica L. Oster ,&nbsp;Aida Zyba ,&nbsp;Erica A. Scarpitti","doi":"10.1016/j.orggeochem.2025.104961","DOIUrl":"10.1016/j.orggeochem.2025.104961","url":null,"abstract":"<div><div>Organic molecules such as <em>n</em>-alkyl lipids, terpenoids, anhydrosugars (AHs), and polycyclic aromatic hydrocarbons (PAHs) are found in karst systems, including cave deposits and drip waters, and provide a potential record of surface climate, ecosystem, and fire. However, it is analytically challenging to separate and measure multiple classes of organic compounds in these low-abundance matrices. Here, we present a simple, solid-phase sequential extraction method for the separation and purification of organic matter in carbonates (∼0.5 g, powder) and drip waters (300 mL, freeze-dried). This method offers efficient extraction and separation of hydrocarbons (<em>F_H</em>) (saturated and PAHs) (hexane/dichloromethane; 70/30; v/v) and polar lipid compounds (<em>F_P</em>) (e.g., AHs, sterols, and diterpenoids) (acetone) with a high recovery of standards in <em>F_H</em> (78 ± 7 %, on average) and <em>F_P</em> (90 ± 6 %, on average) across multiple matrices (i.e., speleothems and waters). Acid digestion was applied to the post-initial sequential extraction speleothem samples to fully liberate any remaining molecules trapped in the calcite crystals. We found that ∼10% of <em>n</em>-alkanes (C₂₀-C₃₂) and the smallest PAHs (naphthalene, methylated naphthalene, and fluorene) of total extractable hydrocarbons were left in the acid digestion, indicating that modification of the sequential extraction could be applied based on the target of interests. In total, this sequential solid-phase extraction method provides reliable separation of geochemically significant compound classes across different matrices within karst systems.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"203 ","pages":"Article 104961"},"PeriodicalIF":2.6,"publicationDate":"2025-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143520529","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":"Study on the main controlling factors on the differential accumulation of natural gas in multiple (ultra-)deeply-buried marine strata","authors":"Zezhang Song ,&nbsp;Ziyu Zhang ,&nbsp;Bing Luo ,&nbsp;Wenjin Zhang ,&nbsp;Changqi Liu ,&nbsp;Xingwang Tian ,&nbsp;Dailin Yang ,&nbsp;Luya Wu ,&nbsp;Bingfei Ge ,&nbsp;Shigui Jin ,&nbsp;Jiutao Yuan","doi":"10.1016/j.orggeochem.2024.104918","DOIUrl":"10.1016/j.orggeochem.2024.104918","url":null,"abstract":"<div><div>Ultra-deep natural gas is characterized by significant burial depth, high maturity, limited biomarkers, and complicated gas-source relationships. Ultra-deep gas accumulations generally underwent complex modifications during their long evolution, making it challenging to clarify the controlling factors of gas accumulation. This study focuses on gas accumulations in multiple (ultra-)deep marine carbonate strata, ranging from the Sinian Dengying (Z₂dn) to the Permian Maokou (P₂m) formations, in the Penglai gas area of the central Sichuan Basin. Using unsupervised machine learning algorithms, we conducted clustering analysis on natural gas composition and isotopes (δ¹³C and δ²H). Furthermore, we combined reservoir microscopic analysis, isotope data (δ¹³C of kerogen and solid bitumen; and δ¹⁸O, δ¹³C, and ⁸⁷Sr/⁸⁶Sr of dolomite), and fluid inclusion analysis to determine the main controlling factors that differentiate gas accumulation in multiple marine carbonate strata. The results indicate that: (1) Natural gases from Z₂dn-P₂m strata in the Penglai gas area are mainly dry gas (dryness &gt; 0.996). Specifically, Z₂dn natural gas exhibits high non-hydrocarbon content, low C₂H₆, δ¹³C_C₂H₆, and δ²H_CH₄. Conversely, the Cambrian (Є) natural gas demonstrates the opposite characteristics. The natural gas in P₂m has relatively high C₂H₆, greater δ¹³C_C₂H₆ and δ²H_CH₄ values. (2) The natural gas from Z₂dn-P₂m in the Penglai gas area is oil-cracking gas and mainly sourced from Є₁q. Due to maturity, hydrocarbon gases are dominated by CH₄. He and N₂ are from inorganic, deep Earth sources and show differential enrichment. Influenced by hydrothermal alteration and TSR, H₂S and CO₂ are enriched in Z₂dn. The δ¹³C_C₂_H₆ in natural gas follows the order: Z₂dn &gt; P₂m &gt; Cambrian. The δ¹³C_CH₄ in natural gas follows the order: Z₂dn ≥ P₂m &gt; Cambrian. (3) Overall, the Z₂dn-P₂m differential accumulation in the Penglai gas area is primarily influenced by various factors, including multiple source rocks, deep hydrothermal transformation, and strike-slip faults.</div></div>","PeriodicalId":400,"journal":{"name":"Organic Geochemistry","volume":"201 ","pages":"Article 104918"},"PeriodicalIF":2.6,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378489","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}