Organic Geochemistry最新文献

Mid-infrared spectroscopy as a tool to monitor molecular changes in fens upon restoration 中红外光谱作为监测沼泽恢复后分子变化的工具

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-02-07 DOI: 10.1016/j.orggeochem.2026.105154

Keunbae Kim , Ben Aernouts , Willem-Jan Emsens , Judith Schellekens , Rudy van Diggelen , Camiel Aggenbach , Erik Verbruggen , Boris Jansen , María J.I. Briones , Karen Vancampenhout

Peatlands are crucial components of the global carbon (C) cycle but have been extensively degraded by drainage. Rewetting is a common practice to restore drained peatlands, yet its effectiveness and impacts on belowground soil organic carbon (SOC) dynamics remain uncertain. To effectively monitor restoration outcomes, affordable, time-efficient, and informative tools are essential. Pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) provides detailed soil organic matter (SOM) characterization, but its high cost, time-intensive nature, and technical complexity limit its routine use. In contrast, mid infrared (MIR) spectroscopy, combined with chemometrics, can offer a promising alternative. This study evaluated the potential of MIR spectroscopy for: (1) reproducing the relative contribution of chemical groups as derived from py-GC/MS, (2) estimating SOC decomposability, and (3) monitoring belowground changes when undrained peatlands are drained or drained peatlands are rewetted. Our results indicated that MIR spectroscopy can effectively estimate specific chemical groups, including benzenes (R²_P = 0.89), carbohydrates (R²_P = 0.85), N-containing compounds (R²_P = 0.76), and n-alkenes (R²_P = 0.74), with fair predictions for lignins (R²_P = 0.68) and phenols (R²_P = 0.64). SOC decomposability, expressed as basal respiration per SOC, was also reasonably estimated (R²_CV = 0.74). MIR spectra significantly differed between undrained and drained fens (P < 0.05), whereas rewetted fens did not differ from either condition (Ps > 0.05). Partial least squares−discriminant analysis further identified the functional groups most responsive to hydrological changes. Overall, MIR spectroscopy represents a cost- and time-efficient tool for assessing SOM composition and carbon stability in fens, supporting data-driven peatland restoration.

泥炭地是全球碳(C)循环的重要组成部分，但由于排水，泥炭地已经大面积退化。复湿是泥炭地恢复的常用方法，但其有效性及其对地下土壤有机碳动态的影响尚不明确。为了有效地监测恢复结果，价格合理、时间高效和信息丰富的工具是必不可少的。热解-气相色谱/质谱法（py-GC/MS）提供了详细的土壤有机质（SOM）表征，但其高成本、耗时和技术复杂性限制了其常规应用。相比之下，中红外光谱（MIR）与化学计量学相结合，可以提供一个有希望的替代方案。本研究评估了MIR光谱在以下方面的潜力：(1)再现由py-GC/MS得出的化学基的相对贡献；(2)估算有机碳分解；(3)监测不排水泥炭地排水或排水泥炭地再湿润时地下变化。结果表明，MIR光谱可以有效地估计特定的化学基团，包括苯（R2P = 0.89）、碳水化合物（R2P = 0.85）、含n化合物（R2P = 0.76）和正烯烃（R2P = 0.74），对木质素（R2P = 0.68）和酚类（R2P = 0.64）有较好的预测。以每有机碳的基础呼吸表示的有机碳分解率也得到了合理的估计（R2CV = 0.74）。未排水和排水泥鳅的MIR光谱差异显著（P < 0.05），而复湿泥鳅的MIR光谱在两种情况下均无差异（P < 0.05）。偏最小二乘判别分析进一步确定了对水文变化最敏感的官能团。总的来说，MIR光谱是评估沼泽中SOM成分和碳稳定性的一种成本和时间效率高的工具，支持数据驱动的泥炭地恢复。

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引用次数: 0

Diagenetic and functionalized steroids in Oligocene marine mammal bones from Hokkaido, Japan 日本北海道渐新世海洋哺乳动物骨骼中的成岩甾体和功能化类固醇

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-01-27 DOI: 10.1016/j.orggeochem.2026.105141

Raman Umamaheswaran , Takuto Ando , Tatsuya Shinmura , Ken Sawada

The preservation and diagenesis of lipids in sedimentary rocks have been studied and recorded in extensive detail. However, their presence and alteration in fossil bones is yet to be fully elucidated. Marine mammal bone fossils, particularly those of cetaceans, are increasingly being studied as a result of their relatively high organic matter content and the abundance of suitable fossil specimens, making them attractive targets for such analyses. The current study focuses on the preservation of steroids and their diagenetic pathways in the bones of three Oligocene marine mammals from Hokkaido, Japan — the desmostylians Ashoroa laticosta and Behemotops katsuiei, and a whale bone. We found that the whale bone displayed preservation of biogenic cholesterol and a higher predominance of diagenetically intermediary compounds such as A-ring monoaromatic steroids, a seco-cholestatriene isomer, cholesta-3,5-diene, and cholestenes, along with cholestanes. However, the desmostylian bones showed comparatively mature distribution of steroids with predominance of diagenetically stable geolipids. To the best of our knowledge, such intermediary steroidal compounds have not been hitherto recovered from bone fossils.

沉积岩中脂类的保存和成岩作用已被广泛详细地研究和记录。然而，它们在化石骨骼中的存在和变化尚未完全阐明。海洋哺乳动物的骨骼化石，特别是鲸类的骨骼化石，由于其相对较高的有机质含量和丰富的合适化石标本，使它们成为这种分析的有吸引力的目标，因此越来越多地被研究。目前的研究重点是在日本北海道的三种渐新世海洋哺乳动物的骨骼中保存类固醇及其成岩途径，这三种哺乳动物分别是：海鞘动物Ashoroa laticosta和巨兽katsuiei，以及鲸鱼的骨骼。我们发现，鲸骨显示出生物源胆固醇的保存，并具有较高的成岩中间化合物的优势，如a环单芳香类固醇、二聚胆甾醇异构体、胆甾醇-3,5-二烯、胆甾醇以及胆甾醇。然而，桥柱骨显示相对成熟的类固醇分布，以成岩稳定的地脂为主。据我们所知，到目前为止还没有从骨骼化石中发现这种中间甾体化合物。

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引用次数: 0

Phosphorus limitation drives the deterministic assembly of dissolved organic matter and microbial activity in surface waters of urban lakes 磷限制驱动城市湖泊地表水溶解有机物和微生物活动的确定性组合

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-01-31 DOI: 10.1016/j.orggeochem.2026.105150

Wei Yu , Pingping Fan , Haiquan Yang , Wenhao Li , Guomin Han , Jifei Hou , Rui Liang , Jingan Chen , Jie Li , Xuede Li

In recent decades, global warming and human-induced imbalances in nitrogen (N) and phosphorus (P) inputs have exacerbated P limitation in urban lake ecosystems. However, it remains unclear whether this change in nutrient stoichiometry affects the molecular assembly processes and microbial degradation pathways of dissolved organic matter (DOM) in the surface waters of urban lakes. In this study, the molecular composition and assembly processes of DOM in surface waters of urban lakes in response to P limitation were investigated using a combination of ultraviolet–visible spectroscopy (UV–Vis), excitation-emission matrix fluorescence spectroscopy (EEM), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and macrogenomic techniques. The results showed that P-limited conditions (N:P > 22.6) simultaneously increased DOM humification and aromaticity and inhibited its bioavailability. In response to nutrient stress, microbes may preferentially mineralize protein-like DOM via oxidoreductase- and transferase-mediated pathways. In addition, Lentisphaerota exhibits significantly stronger associations with DOM molecules under P-limited systems, and DOM assembly patterns shift toward a deterministic direction. The results deepen our understanding of the biogeochemical fate of DOM in urban lakes and provide new insights into the pathways of microbial-mediated DOM transformation.

近几十年来，全球气候变暖和人为造成的氮、磷输入失衡加剧了城市湖泊生态系统磷的限制。然而，目前尚不清楚这种营养化学计量的变化是否会影响城市湖泊地表水中溶解有机物（DOM）的分子组装过程和微生物降解途径。采用紫外-可见光谱（UV-Vis）、激发-发射矩阵荧光光谱（EEM）、傅里叶变换离子回旋共振质谱（FT-ICR MS）和宏观基因组技术，研究了城市湖泊地表水DOM的分子组成和组装过程对P限制的响应。结果表明，磷限制条件（N:P > 22.6）增加了DOM腐殖化和芳香性，抑制了其生物利用度。在对营养胁迫的反应中，微生物可能通过氧化还原酶和转移酶介导的途径优先矿化蛋白质样DOM。此外，在p限制体系下，Lentisphaerota与DOM分子的关联显著增强，DOM的组装模式向确定性方向转变。这些结果加深了我们对城市湖泊DOM生物地球化学命运的理解，并为微生物介导的DOM转化途径提供了新的见解。

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引用次数: 0

Thermal alteration of the aliphatic biopolymer cutan: implications for composition and degradation 脂肪族生物聚合物皮的热变化：对组成和降解的影响

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-01-31 DOI: 10.1016/j.orggeochem.2026.105149

Klaas G.J. Nierop , Joeri Kaal

Cutan is the operationally defined residual fraction of cuticles after solvent extraction and hydrolysis. We investigated the thermal behaviour as a consequence of charring experiments of cutan isolated from Agave americana and Clivia miniata. While both cutan fractions exhibited almost identical weight loss patterns as a function of charring temperature, the molecular degradation and transformations differed, mainly reflected by higher carboxylic acid contents released and retained in the cutan residues of C. miniata, whereas cutan of A. americana comprised and released more hydroxy-containing moieties. The extractable fractions after charring yielded initially the building blocks of cutan, but with progressive heating defunctionalisation (removal of hydroxy and carboxylic acid groups) mainly n-1-alkenes and n-alkanes were produced. The lack of polyaromatic condensation products upon charring indicates the highly saturated character of cutan under severe conditions.

角质层是角质层经过溶剂萃取和水解后的残留部分。我们研究了美洲龙舌兰和Clivia的皮炭的热行为。两种皮渣随炭化温度的变化失重模式基本相同，但分子降解和转化不同，主要表现为在紫荆芥皮渣中释放和保留的羧酸含量较高，而美洲荆芥皮渣中含有和释放的含羟基部分较多。炭化后的可提取馏分最初产生了皮的基本成分，但随着逐渐加热的去功能化（去除羟基和羧基），主要产生了n-1-烯烃和正构烷烃。炭化后缺乏多芳缩合产物，表明在恶劣条件下，皮质具有高度饱和的特性。

引用次数: 0

Primary and secondary steroid acids in crude oils: Implications for geological fate of steroids 原油中的一级和二级类固醇酸：对类固醇地质命运的影响

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-02-04 DOI: 10.1016/j.orggeochem.2026.105142

Can Xie , Gangtian Zhu , Jochen J. Brocks , Yuguang Hou

The origin of steroid acids in sedimentary rocks remains a subject of debate. This study presents a comprehensive analysis of steroid acids in a series of genetically related crude oils with varying maturities and biodegradation ranks. Molecular structures of the steroid acids were tentatively identified based on mass spectra and comparison with standards. The results show that the steroid acids can be classified into two types. The first type, characterized by a carboxyl or carboxyalkyl group at C-3 of the A-ring, is enriched in low-maturity oils, indicating that it was generated during early diagenesis. The second type, characterized by a carboxyl group at the end of the side chain on the D-ring, only occurs in oils with specific biodegradation ranks, implying that these steroid acids originate during oil biodegradation. Based on these findings, the first and second types are named primary steroid acids and secondary steroid acids, respectively. Both types of steroid acids may originate from microbial reworking of steroid precursors. Primary steroid acids originate either prior to or simultaneously with the formation of steranes, whereas secondary steroid acids originate during later biodegradation of steranes. The patterns of carboxyl substitution in steroid biotransformation during early diagenesis versus in-reservoir biodegradation exhibit significant differences, which might serve as clues for investigating microbial communities and their metabolic activities under different geological conditions.

沉积岩中类固醇酸的来源仍然是一个有争议的问题。本研究对一系列不同成熟度和生物降解等级的遗传相关原油中的类固醇酸进行了综合分析。通过质谱分析和与标准品的比较，初步鉴定了甾体酸的分子结构。结果表明，甾体酸可分为两类。第一类烃源岩在a环C-3处以羧基或羧基烷基为特征，富含低成熟度油，表明其形成于早期成岩作用。第二类甾体酸在d环侧链末端有一个羧基，只存在于具有特定生物降解等级的油中，这意味着这些甾体酸是在油的生物降解过程中产生的。基于这些发现，第一类和第二类分别被命名为一级类固醇酸和二级类固醇酸。这两种类型的类固醇酸都可能源于微生物对类固醇前体的改造。一级类固醇酸在甾烷形成之前或同时产生，而二级类固醇酸在甾烷生物降解后期产生。早期成岩作用与储层降解过程中甾体生物转化过程中羧基取代的模式存在显著差异，这可能为研究不同地质条件下微生物群落及其代谢活动提供线索。

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引用次数: 0

The sources of the Paleozoic petroleum systems in the Tarim Basin as revealed by geochemistry of oils and extracts from ultra-deep reservoirs 塔里木盆地古生代含油气系统的地球化学特征及超深层油藏的油气提取物

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-02-13 DOI: 10.1016/j.orggeochem.2026.105158

Zhiwei Gao , Miaoqi Cheng , Qian Deng , Haizu Zhang , Zewen Liao , Yongge Sun

The sources of Paleozoic petroleum systems in the Tarim Basin remain a subject of ongoing controversy. To clarify this long-standing uncertainty, we analyzed crude oils from the Cambrian subsalt belt and drill cuttings from the Cambrian Yuertus Formation, with a primary focus on the LunTan 1 oil from the deepest reservoir within the Cambrian subsalt structure. For comparison, we used the previously proposed Middle–Upper Ordovician (O_2–3) end-member source oil (YM2) as a reference. Sequential extraction revealed that Bitumen III (adsorbed hydrocarbons on clay/kerogen) was free of drilling mud contamination and its molecular compositions and n-alkane carbon isotopes were comparable to those of routinely extracted organic matter, and thus was employed in the present study. Regardless of thermal maturity effects, sterane and hopane distributions in the crude oils strongly correlate with those in the Yuertus shale. The presence of aryl isoprenoids in the crude oils indicates deposition under euxinic conditions. The n-alkane carbon isotopes of the crude oils range from −34‰ to −36‰, aligning with the estimated δ¹³C values of n-alkanes derived from the Yuertus shale (–32‰ to −36‰), but they are significantly depleted compared to those in the typical O_2–3 source rocks (−30‰ to −31‰). Given the close geochemical affinity between most Paleozoic oils and the YM2 oil, we suggest that the Yuertus shale is the primary source rock for these petroleum systems. However, caution is warranted in oil-source correlations due to geochemical variations between the two black rock series within the Yuertus Formation and potential in-reservoir alterations.

塔里木盆地古生界含油气系统的来源一直是一个争论不休的问题。为了澄清这一长期存在的不确定性，我们分析了寒武系盐下带的原油和寒武系Yuertus组的钻屑，并将重点放在寒武系盐下构造最深储层的轮滩1号原油上。为了进行比较，我们以先前提出的中-上奥陶统（O2-3）端元源油（YM2）作为参考。连续提取表明，沥青III（吸附在粘土/干酪根上的碳氢化合物）不受钻井泥浆污染，其分子组成和正烷烃碳同位素与常规提取的有机质相当，因此被用于本研究。不考虑热成熟度效应，原油中甾烷和藿烷的分布与Yuertus页岩中甾烷和藿烷的分布具有很强的相关性。原油中芳基类异戊二烯的存在表明是在缺氧条件下沉积的。原油正构烷烃碳同位素分布范围为- 34‰~ - 36‰，与Yuertus页岩正构烷烃的δ13C值（-32‰~ - 36‰）一致，但与典型O2-3烃源岩正构烷烃的δ13C值（- 30‰~ - 31‰）相比，正构烷烃的δ13C值明显下降。考虑到大多数古生代原油与YM2原油的地球化学亲和性，我们认为Yuertus页岩是这些含油气系统的主要烃源岩。然而，由于Yuertus组内两个黑色岩系之间的地球化学变化和潜在的储层蚀变，需要谨慎进行油源对比。

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引用次数: 0

Organic signatures from modern and ancient seagrass in coarse-grained sediments near Poel Island, Baltic Sea 波罗的海Poel岛近古海草粗粒沉积物的有机特征

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-04-01 Epub Date: 2026-01-16 DOI: 10.1016/j.orggeochem.2026.105129

Volker Thiel, Manuel Reinhardt, Maria Thirase, Alina Klick, Volker Karius

Seagrass meadows are regarded to play an important role in mitigating climate change by acting as a sink of organic carbon (C) in their underlying sediments. This study investigates the C sequestration potential of seagrass in coarse-grained nearshore deposits near Poel Island in the southwestern Baltic Sea. Four ∼60 cm long sediment cores from Zostera marina meadows were analyzed for the nature and quantity of particulate organic C. Emphasis was placed on the questions (i) whether seagrass coverage would lead to an enhanced C storage in this high-energy proximal setting, and (ii) whether the stored C has a seagrass origin or derives from other, marine or terrestrial sources. We observed that total organic C (TOC) contents in the rhizosphere of seagrass vegetated areas are currently very low (0.05–0.22%) and similar to unvegetated areas. However, a several-cm-thick, dark brown layer, residing at a depth of 40–60 cm, was strongly enriched in TOC (up to 17%) and contained most of the organic matter stored in the sediment profiles studied. A combination of lipid biomarkers, scanning electron microscopy, ¹⁴C age dating, and ¹³C measurements in TOC and individual lipids revealed that the organic matter in this layer originated from seagrass. This material was abruptly buried ∼2000 years ago, possibly because of a storm event. Our findings highlight that event-driven burial of seagrass biomass can provide a critical pathway for Blue Carbon storage over relevant (10²–10³ yrs) timespans in coarse-grained proximal sediments.

海草草甸被认为在减缓气候变化方面发挥着重要作用，因为它作为有机碳(C)的汇在其下层沉积物中。本文研究了波罗的海西南部Poel岛近岸粗粒度沉积物中海草的碳封存潜力。研究人员分析了来自Zostera滨海草甸的4个~ 60 cm长的沉积物岩心，分析了颗粒有机碳的性质和数量。重点放在了以下问题上：(i)海草覆盖是否会导致这种高能近端环境中碳储存的增强，以及（ii）储存的碳是来自海草还是来自其他海洋或陆地来源。结果表明，目前海草植被区根际总有机碳（TOC）含量很低（0.05 ~ 0.22%），与无草区相似。然而，在40-60 cm深度的几厘米厚的深棕色层中，TOC含量高达17%，并且包含了所研究的沉积物剖面中储存的大部分有机质。脂质生物标志物、扫描电镜、碳同位素年龄测定、碳同位素测定和单个脂质的碳同位素测定结果表明，该层的有机质来源于海草。这些物质可能是在大约2000年前因风暴事件而被突然掩埋的。我们的研究结果强调，事件驱动的海草生物量埋藏可以为粗粒度近端沉积物在相关（102-103年）时间跨度内的蓝碳储存提供关键途径。

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引用次数: 0

Novel diamondoid detection technique using pMRM (GC-MS/MS): Enabling source rock-oil-condensate correlations 采用pMRM （GC-MS/MS）的新型金刚石检测技术：实现源岩-油-凝析油相关性

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-03-01 Epub Date: 2026-01-14 DOI: 10.1016/j.orggeochem.2025.105125

Ibrahim Atwah , Maram Alsaif

Lower and higher diamondoids persist from early oil generation into high-maturity condensates and can fingerprint fluids when classical biomarkers are depleted. However, routine measurement of higher diamonoids has been limited by their trace abundances and poor fragmentation. A method based on pseudo-Multiple Reaction Monitoring (pMRM) on gas chromatography coupled to triple quadrupole tandem mass spectrometry (GC-MS/MS) was developed to detect and quantify diamondoids using nine diverse petroleum and rock-extract samples. In pMRM, the molecular ion was monitored in the first and third quadrupoles while a modest collision energy was applied in the collision cell to suppress interferences. Relative to selected ion monitoring, signal-to-noise for higher diamondoids increased markedly, enabling confident peak detection in the late-elution window. Optimal collision energies followed cage size, approximately 20 electron-volts for triamantane, 40 for tetramantanes, and 50 for pentamantanes and cyclohexamantane. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were assessed to be 0.01 and 0.05 ng ml⁻¹, respectively. Utilizing pMRM, many crude oils were suitable for direct injection (“dilute and shoot”), whereas rock extracts, heavy and biodegraded crudes, and some condensates benefited from a silica-gel preparation step. In those cases, approximately 60 mg of sample was sufficient to prepare a saturated, n-alkane free fraction suitable for detecting higher diamondoids using pMRM. The pMRM method demonstrated high analytical reproducibility across chemically diverse matrices including rock extracts, crude oils, and condensates, with relative standard deviations for normalized higher diamondoids typically below 10% over a three month monitoring period, confirming the stability and robustness of Quantitative Extended Diamondoid Analysis (QEDA) measurements using the pMRM approach. These results indicate that pseudo multiple reaction monitoring enables routine, high sensitivity measurement of higher diamondoids and provides molecular fingerprints that support oil-oil, oil-condensate, and condensate-source rock correlations, which were previously difficult to achieve due to the inherent compositional variability among these sample types.

从早期生油到高成熟的凝析油，低和高的金刚石持续存在，当经典生物标志物耗尽时，它们可以作为流体的指纹。然而，由于其痕量丰度和破碎性差，对高级类金刚石的常规测量受到限制。建立了一种基于气相色谱-三重四极杆串联质谱（GC-MS/MS）的伪多重反应监测（pMRM）方法，对9种不同的石油和岩石提取物样品进行了diamondoids的检测和定量。在pMRM中，分子离子在第一和第三四极进行监测，同时在碰撞单元中施加适度的碰撞能量以抑制干扰。相对于选定的离子监测，高diamondids的信噪比显著增加，从而在洗脱后期窗口中实现可靠的峰检测。最佳碰撞能量遵循笼形尺寸，三烷约为20电子伏，四烷约为40电子伏，五烷和环己烷约为50电子伏。方法的检出限和定量限分别为0.01和0.05 ng ml−1。利用pMRM，许多原油适合直接注入（“稀释后注入”），而岩石提取物、重质原油和生物降解原油以及一些凝析油则受益于硅胶制备步骤。在这些情况下，大约60毫克的样品足以制备饱和的、无正构烷烃的馏分，适用于使用pMRM检测较高的金刚石。pMRM方法在包括岩石提取物、原油和凝析油在内的多种化学基质中具有很高的分析重现性，在三个月的监测期内，标准化高diamondids的相对标准偏差通常低于10%，证实了使用pMRM方法进行定量扩展diamondids分析（QEDA）测量的稳定性和鲁棒性。这些结果表明，伪多重反应监测能够实现常规的、高灵敏度的高diamondoids测量，并提供支持油-油、油-凝析油和凝析油-烃源岩相关性的分子指纹图谱，而这在以前由于这些样品类型之间固有的成分变异性而难以实现。

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引用次数: 0

Experimental evidence on the bitumen role of the metal enrichment in the Erdaokan Ag-Pb-Zn deposit 二道坎银铅锌矿床沥青对金属富集作用的实验证据

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-03-01 Epub Date: 2026-01-17 DOI: 10.1016/j.orggeochem.2026.105128

Shun-Feng Yan , Xiao-Min Zheng , Lin Li , Hai-Yan Zheng , Mao-Wen Yuan , M. Santosh , Sheng-Rong Li

This study investigates the role of bitumen in the metallogenesis of the Erdaokan Ag-Pb-Zn deposit. Using in situ high-pressure diamond anvil cell (DAC) experiments, natural metal-rich bitumen from the deposit was reacted with water up to 623 K. Optical microscopy revealed that bitumen transitions into a mobile, partially dissolved phase at high temperature. Upon subsequent cooling to ∼473 K, new spherical particles precipitated from the fluid. Raman spectroscopy identified these new precipitates as metal halides. This finding is geochemically consistent with the Pb-rich nature of the source bitumen and the Ag-Pb-Zn signature of the deposit. Significantly, the experimental precipitation temperature (∼473 K) aligns closely with the upper temperature boundary of the natural mineralization stage derived from fluid inclusion studies (∼464 K). These results provide direct experimental evidence that bitumen can function as an active ore fluid, capable of transporting metals at high temperatures and precipitating them as intermediate metal halides during cooling. This mechanism is interpreted as a key process in the enrichment and formation of the Erdaokan deposit.

研究了沥青在二道坎银铅锌矿床成矿中的作用。利用原位高压金刚石砧池（DAC）实验，将该矿床的天然富金属沥青与623 K的水反应。光学显微镜显示沥青在高温下转变为可移动的部分溶解相。随后冷却至~ 473 K时，新的球形颗粒从流体中析出。拉曼光谱鉴定这些新的沉淀为金属卤化物。这一发现与源沥青的富铅化特征和矿床银铅锌特征相一致。值得注意的是，实验降水温度（~ 473 K）与流体包裹体研究（~ 464 K）得出的自然矿化阶段的上限温度边界非常接近。这些结果提供了直接的实验证据，证明沥青可以作为一种活性矿石流体，能够在高温下输送金属，并在冷却过程中作为中间金属卤化物沉淀金属。这一机制被解释为二道坎矿床富集形成的关键过程。

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引用次数: 0

Thermal evolution characteristics of dibenzothiophene, dibenzofuran and fluorene and their homologues and their geochemical implications 二苯并噻吩、二苯并呋喃和芴及其同系物的热演化特征及其地球化学意义

IF 2.5 3区地球科学 Q2 GEOCHEMISTRY & GEOPHYSICS

Organic Geochemistry

Pub Date : 2026-03-01 Epub Date: 2026-01-21 DOI: 10.1016/j.orggeochem.2026.105136

Xueyou Tan , Sijia Nie , Xijun Wang , Wei Peng , Xu Wang , Suyang Cai , Jingwen Zheng , Xiaoyong Wang , Zhushi Ge , Liangliang Ren , Jiang Wei

The dibenzothiophene (DBT or SF), dibenzofuran (DBF or OF) and fluorene (F) series compounds are characterized by high structural stability and are widely used in sedimentary environment discrimination and maturity assessment. However, their diagnostic parameters can be overprinted by thermal effects at high maturity. To investigate this, we conducted closed-system pyrolysis experiments (275–450℃) on a saline lacustrine source rock from the Paleogene Shahejie Formation and analyzed the products using gas chromatography-mass spectrometry (GC–MS). Specific results show that: (1) The DBT series dominated throughout, with reaction pathways shifting from methylation below 325℃ to demethylation above this threshold. (2) The DBF series exhibited lower thermal stability with a “decrease–increase–decrease” pattern, whereas the F series was more stable at medium to high temperatures. (3) Traditional proxies like the DBT/P–Pr/Ph cross-plot showed an environment trend from marine to coal-derived with increasing temperature, which misrepresents the constant high-salinity, reducing conditions of the source rock, highlighting a significant maturity overprint. In contrast, a new discrimination diagram based on parameters derived from the combined DBT, DBF, and F series effectively minimized thermal interference, consistently and correctly indicating the original depositional environment. This demonstrates the greater robustness of the ‘3Fs’ series over individual compounds for paleoenvironment reconstruction, especially in high-maturity samples.

二苯并噻吩（DBT或SF）、二苯并呋喃（DBF或OF）和芴(F)系列化合物具有较高的结构稳定性，广泛应用于沉积环境判别和成熟度评价。然而，它们的诊断参数可能在高成熟度时被热效应套印。为此，我们对古近系沙河街组咸化湖相烃源岩进行了封闭系统（275 ~ 450℃）热解实验，并采用气相色谱-质谱（GC-MS）分析了热解产物。具体结果表明：(1)DBT系列在整个过程中占主导地位，反应途径从325℃以下的甲基化转向325℃以上的去甲基化。(2) DBF系列表现出较低的热稳定性，表现为“减少-增加-减少”的模式，而F系列在中高温下更稳定。(3) DBT/ P-Pr /Ph交叉图等传统指标显示，随着温度的升高，烃源岩环境呈现由海相到煤源的变化趋势，曲解了烃源岩持续的高盐度、低盐度条件，突出了明显的成熟度叠加。相比之下，基于DBT、DBF和F系列组合参数的新识别图有效地减少了热干扰，一致且正确地指示了原始沉积环境。这表明，对于古环境重建，特别是在高成熟度样品中，“3Fs”系列比单个化合物具有更强的鲁棒性。

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