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1.
南黄海柱状沉积物中烃类化合物的地球化学特征及其对沉积环境的指示 总被引：1，自引：1，他引：0
重点探讨了南黄海柱状沉积物中烃类化合物的分子组成特征及其对沉积环境的指示意义,结果显示,沉积柱中总有机碳（TOC）和总氮（TN）具有较好的正相关性,无机氮的影响较弱,这可能跟本区受径流输入的陆源物质的影响较弱有关。上层样品（0～10 cm）中长链正构烷烃占优势,奇偶优势显著,反映了陆源高等植物贡献;藿烷、甾烷的组成则显示该段样品中有机质具有较高的热成熟度;且姥鲛烷（Pr）/植烷（Ph）比值大于1.0,指示沉积环境以氧化为主,这相对不利于海洋源有机质的保存,从而凸显了陆源有机质的贡献。在10～20 cm之间,沉积环境由相对偏氧化向偏还原过渡;20 cm以下表现为强还原性的沉积环境,有机质成熟度较低。中、下层样品中正构烷烃多呈现双峰分布,短链烷烃具有一定的偶奇优势,这可能主要跟海洋浮游生物、藻类及微生物的贡献有关。与渤海烃类化合物的沉积记录进行对比,发现渤海沉积柱中烃类化合物主要跟历史时期不同来源物质的输入及人类活动的影响有关,而南黄海沉积柱中烃类化合物的特征则主要反映了沉积环境和微生物作用对有机质的埋藏保存有重要影响。 相似文献
2.
A large predominance of docosane, a wide range of n-alkanes otherwise possessing an odd/even ratio and a complex mixture of branched/cyclic hydrocarbons has been isolated from polythene vial closures. One of two types of polythene feedstock granules of a type used in the manufacture of laboratory plastic ware gave similar results with the exception that the n-alkane homology possessed a slight even/odd predominance; the other type produced a small amount of alkanes in which the normals had a more pronounced even/odd predominance. These findings are noteworthy on two counts. Firstly, docosane has been reported to be a predominant member of the homologous n-alkanes isolated from a series of sediments and indeed its predominance has been suggested as a measure of the maturity of these sediments. Secondly, odd/even alkane homologies are usually regarded, in geochemical analyses, as being biological environmental indicators. 相似文献
3.
对采自西峰油田三叠系延长组六个油砂样品中游离烃、束缚烃的饱和烃、芳烃和氯仿馏分进行了系统的分析。在氯仿馏分中检测出一系列异常丰富的正构烷基酮化合物，其碳数分布范围C13～ C33,具有强烈的奇碳优势。研究表明:正构烷基酮的演化受热演化（成熟度）的影响，在成熟度较低的束缚烃中，主要分布正构烷基 2 酮；而在成熟度较高的游离烃中，主要为正构烷基 3,4,5,6（或更高） 酮异构体。表现为随着成熟度的增加，正构烷基酮的羰基(∶CO)由2位向更高位迁移的趋势。正构烷基酮的形成是由于菌藻类和高等植物类脂中的脂肪酸，在粘土矿物等催化作用下，经β 氧化后脱羧基而形成。在束缚烃和游离烃中正构烷基酮的分布特征，可用于油气成藏差异的研究。 相似文献
4.
不同类型沉积物中脂肪酸的分布、演化和生烃意义 总被引：14，自引：2，他引：14
对近代海洋沉积物、泥炭、福山凹陷第三系泥岩、茂名盆地第三系油页岩和辽河盆地东部凹陷第三系沉积岩剖面等样品中脂肪酸类型和分布特征进行了分析与研究。结果表明以低等浮游动植物为主的沉积中，二元肪酸丰度相对比一元酸占优势。随深程度增加，沥青中脂肪酸高碳数相对减少，低碳数相对增高，偶碳估势逐渐消失。在辽河盆地东部凹陷埋深２２６６ｍ的泥岩中发现脂肪酸仍具有偶碳优势，证明沉积有机质中偶碳脂肪酸优势可以保存到生油高峰前的较高演化阶段，对低熟原油烷烃的生成和具奇碳优势有重要意义。 相似文献
5.
《Geochimica et cosmochimica acta》1987,51(6):1457-1466
Aliphatic and aromatic hydrocarbons in sediments of the middle and lower Mississippi Fan and two intraslope basins in the Gulf of Mexico are derived from terrestrial organic matter and thermogenic, mature hydrocarbons. The terrestrial hydrocarbon component consists primarily of terrigenous, plant biowaxes (n-alkanes with 21 to 33 carbons). The occurrence of thermogenic hydrocarbons in immature near-surface sediments, their molecular distributions and concentration variations with depth suggest that the majority of these mature hydrocarbons have migrated from a source much deeper in the sediment column. A portion of the thermogenic hydrocarbons may be derived from recycled material and includes phenanthrene, methyl phenanthrenes, chrysene and benzopyrenes. The migrated, thermogenic hydrocarbons include normal and isoprenoid alkanes with less than 21 carbons, naphthalene, methyl naphthalenes, ethyl naphthalenes and other aromatics of similar volatility (i.e., biphenyl, acenaphthene and fluorene). Triterpane, sterane and aromatized sterane distributions suggest that the thermogenic hydrocarbons at both sites have a common source and are overprinted with immature sediment hydrocarbons. The biomarker distributions and carbon isotopic compositions of the thermogenic hydrocarbons are atypical for petroleum produced in the Gulf of Mexico. Molecular distributions of the hydrocarbons are constant, regardless of the present depth of occurrence, suggesting that they have migrated in a separate phase. The upward migration of hydrocarbons from deeper sources is a wide-spread phenomenon in the Gulf of Mexico with several documented cases of massive seepage (visible oil) as well as the more diffuse permeation of Pleistocene sediments of the Mississippi Fan and two intraslopes reported here. 相似文献
6.
Biomarker molecules are valuable for the elucidation of ancient microbial ecosystems and the characterization of petroleum source rocks. For such studies, acquisition of reliable hydrocarbon data and proof of their syngeneity are essential. However, contamination of geological samples with anthropogenic petroleum products during drilling, storage and sampling can be particularly problematic because these hydrocarbons may over-print an original indigenous biomarker profile. To evaluate the extent of contamination of drill core and outcrop material, we studied the distribution of hydrocarbons in 26 rocks from different locations in the world. All rocks had petroleum products on their exterior surfaces. Twenty-two samples also contained surficial hydrocarbons derived from polyethylene plastic, including branched alkanes with quaternary carbon centers (BAQCs) and alkylcyclopentanes with pronounced even-over-odd carbon number preference. Using three examples from the Paleoproterozoic Tawallah and McArthur Groups in northern Australia, we show how indigenous biomarkers can be recognized by comparing hydrocarbon distributions between exterior rock surfaces and the rock interior, and how infiltration of allochthonous hydrocarbons can be assessed through the spatial distribution of characteristic polyethylene derived hydrocarbons in the rock. The methods outlined in this paper give confidence in the interpretation of biomarkers in particularly sensitive applications such as the first occurrences of certain organisms in the geological record and the provenance of organic matter in meteorites. 相似文献
7.
I. A. Nemirovskaya 《Geochemistry International》2008,46(4):378-385
Aliphatic and polycyclic aromatic hydrocarbons were examined in the surface layer of bottom sediments from the eastern part of the Sakhalin shelf (the materials were sampled in the summer of 2002). The concentrations of hydrocarbons were determined to have changed since the beginning of the development of oil fields (compared with earlier years). According to the distribution of markers in the hydrocarbon compositions, the bottom sediments are dominated by allochthonous (terrigenous) hydrocarbons, which are the most stable compounds. The presence of transformed anthropogenic oil alkanes, which have never been found before, may be indicative of the increasing pollution of the region. 相似文献
8.
Enis Darilmaz 《Environmental Earth Sciences》2017,76(5):220
The sources and spatial distributions of aliphatic hydrocarbon concentrations were investigated in surficial sediments of the Northern Cyprus (Gemi Konagi, Girne and Gazi Magusa Areas). Aliphatic hydrocarbon levels were determined with a gas chromatography–mass spectrometer. Total aliphatic hydrocarbon (n-alkanes, Σ25; isoprenoids, Σ2) concentrations in the sediments were found in the range of 1107–6360 ng/g. Results indicated that the sediments were mainly dominated by odd numbered n-alkanes (n-C10–n-C34), maximizing at n-C17, n-C29 and n-C31. Statistical analyses and diagnostic ratios have been used to determine the possible sources and origins of aliphatic hydrocarbons. Aliphatic hydrocarbons were showed biogenic character at all sampling areas and were found mainly originated from terrestrial, marine and both terrestrial-marine plants at Gemi Konagi, Gazi Magusa and Girne, respectively. 相似文献
9.
《Geochimica et cosmochimica acta》1987,51(5):1273-1284
Polycyclic aromatic hydrocarbon (PAH) and aliphatic hydrocarbon concentrations have been determined for sediments and associated pore waters collected at 2 sites (11 stations) in Puget Sound, Washington (northwest U.S.A.). These sediments have been contaminated to varying degrees by hydrocarbons from a creosote plant and from various combustion sources. PAH were not detected in pore waters of sediments whose PAH were primarily derived from combustion and natural sources, even though pore water concentrations predicted from sediment concentrations and two-phase equilibrium partitioning models were above detection limits from most PAH. Equilibrium partition coefficients calculated from field aqueous and solid phase data from an area contaminated with creosote agreed with laboratory-derived coefficients to within a factor of ± 4. Pore water concentrations of creosote-derived aliphatic hydrocarbons increase with increasing concentration in bulk sediments. However, pore water concentrations of natural and contaminant aliphatic hydrocarbons are much higher than predicted by solubility data, possibly due to association with nonfilterable dissolved organic matter and colloids. Other major factors controlling hydrocarbon pore water concentrations include differential hydrocarbon sources, specific particle associations and solubility. 相似文献
10.
Fatty acid and hydrocarbon distributions in surficial sediments from ten locations in southern Lake Huron indicate both aquatic and terrigenous recent biological sources of these geolipid materials. Normal alkanoic acids appear to be derived primarily from aquatic sources whereas normal alkanes are from multiple origins. Geolipid distributions are determined by the nature of the biogenic source and are modified during transport and deposition. Sediments receiving urban runoff in Saginaw Bay contain large amounts of non-biogenic hydrocarbons of a petroleum or industrial nature. 相似文献
11.
Terminal Proterozoic mid-shelf benthic microbial mats in the Centralian Superbasin and their environmental significance. 总被引：1，自引：0，他引：1
G A Logan C R Calver P Gorjan R E Summons J M Hayes M R Walter 《Geochimica et cosmochimica acta》1999,63(9):1345-1358
A combined sedimentological and biogeochemical study has been conducted on several Terminal Proterozoic mid-shelf microbial mat facies from the Centralian Super-basin. Isotopic and organic geochemical analysis of the bitumen and kerogen indicated that two sources of organic matter from 'planktonic' and 'benthic microbial-mat' populations contributed to the sediment. The 'planktonic' source provided a suite of n-alkanes with C20, whereas, the 'benthic' source contributed an overlay of n-alkanes >C20 with a strong even preference, together with mid-chain methyl alkanes. Kerogen and biomarkers derived from the microbial mat were found to be depleted in 13C relative to planktonic material. Pyrite in the microbial mats was also found to be depleted in 34S compared to surrounding facies. The combination of these observations suggested that the mats may have been at least partly composed of sulfide oxidising bacteria. These organisms have specific environmental tolerances that set limits on palaeo-environment. Their requirement for oxygen indicates that the water column above the mid-shelf could not have been anoxic. Accordingly, from the results and age determinations reported here, it would appear that mid-shelf environments of the Centralian Superbasin of Australia were seeing significant levels of oxygen through the Ediacarian. 相似文献
12.
Surface sediments from 20 stations on the Scotian Shelf, collected on a transect from Halifax to Emerald Bank and around Sable Island, have been analyzed for hydrocarbon content and composition by gas chromatography and fluorescence spectrophotometry. Some samples were taken near abandoned exploratory drilling sites in the Sable Island area. Hydrocarbons appear to be mainly derived from biogenic terrestrial sources as evidenced by an inverse correlation of concentration with increasing distance from the mainland and a strong odd carbon preference in the n-alkanes. Contribution from petroleum sources, while minor, was most noticeable between Halifax and Emerald Bank. There is also evidence that the hydrocarbon composition at abandoned exploratory drilling sites has been slightly altered. 相似文献
13.
Patrick Gearing Juanita Newman Gearing Thomas F. Lytle Julia Sever Lytle 《Geochimica et cosmochimica acta》1976,40(9):1005-1017
Hydrocarbon results from gas chromatography of 60 recent sediment and 10 benthic algae samples delineate two distinct shelf environments in the northeastern Gulf of Mexico.Sediments off Florida (shell hashes and sands) have moderate amounts of lipids/total sediment (average 113ppm ± 80%) but low hydrocarbon levels (average 3.06 ppm ± 41%). Aliphatic hydrocarbons are dominated by a series of branched or cyclic, unsaturated C25 isomers. The major n-alkane is n-C17. The n-alkane and isoprenoid patterns are consistent with a marine hydrocarbon source.Sediments closer to the Mississippi River (silts and clays) contain large amounts of lipids (average 232 ppm ± 53%) and hydrocarbons (average 11.7 ppm ± 55%) to total sediment. Aliphatic hydrocarbons are mainly odd carbon number high molecular weight n-alkanes, indicating a terrigenous hydrocarbon source. Isoprenoids are present in greater abundance than in sediments off Florida (n-C17/ pristane and n-C18/phytane ratios ~2to 3). Relatively large amounts of n-C16, together with an even distribution of n-alkanes in the range C14–C20 and a substantial unresolved envelope all point to a fossil fuel input to the Mississippi samples.Samples off the Alabama coast show intermediate characteristics. 相似文献
14.
Walter E. Reed 《Geochimica et cosmochimica acta》1977,41(9):1231-1245
Modern sediments of Mono Lake show marked variation in lipid composition with depositional environment. Constituents derived from the drainage basin, characterized by high molecular weight alkane hydrocarbons (C25–C31), and the steroids β-sitosterol and brassicasterol, predominate in near-shore environments. In the deepest part of the lake, sediments exhibit a combination of externally-derived constituents, and lipids derived from the lake biota; the latter characterized by low molecular-weight alkanes and alkenes (C15–C17), phytane, and the steroids ergost-7-en-3β-ol and 24-ethylcholest-7-en-3-β-ol. Steranes, 4-methylsteranes, and the C18 and C19 isoprenoids appear to be forming in the intensely reducing bottom sediments at the present time.The compositions of samples from the Pleistocene succession of Mono Basin suggest that sample-to-sample variation within the same stratum is negligible so long as unweathered samples from the same depositional environment are compared. Sediments having equivalent lithologies may or may not have similar compositions, but sediments having similar fossil contents do show similar lipid compositions. Subaerial weathering of sediments causes a marked decrease in the amount of extractable organic material, as well as distinct changes in its hydrocarbon composition. Specifically, weathered sediments exhibit a decrease in relative content of low molecular weight hydrocarbons and a relative increase in nC22.Organic composition of sediments from the Pleistocene stratigraphie column cannot be correlated with depth of burial. Compositional changes with stratigraphie position are probably related to paleo-ecological factors such as population or productivity rather than depth of burial. Lithology and organic composition provide mutually-corroborating evidence regarding glacial advances in the adjacent Sierra Nevada Mountains. During glaciations, the lake sediments are rich in sandstones, and the organic composition shows a predominance of externally-derived debris, with no evidence for contributions from the lake biota. 相似文献
15.
《Geochimica et cosmochimica acta》1987,51(10):2681-2697
Numerous Ordovician oils worldwide are known to show unusual and distinctive distributions of hydrocarbons which, it has been suggested, are derived from a “unique benthonic mat-forming non-photosynthetic prokaryotic organism”, Gloeocapsomorpha prisca Zalessky 1917, which is the major contributor of organic matter. Organic matter-rich sediments from the Canning and Amadeus Basins of Australia, known to contain G. prisca fossils and to have the characteristic predominance of odd carbon number (C13–C19) n-alkanes, were investigated to determine other hydrocarbon distributions. Sediments from both basins contained abundant n-alkylcyclohexanes with odd carbon number predominance (C13–C19) and methyl-n-alkylcyclohexanes (C14–C20) which, in immature sediments, showed an even carbon number predominance. The isomer distribution of these latter compounds was determined by direct comparison with synthetic standards. The sediments from both basins also contained very similar distributions of steranes and pentacyclic triterpanes and the derived kerogens had a characteristically light carbon isotope signature.Pyrolysis of a G. prisca-rich kerogen yielded a hydrocarbon mixture with a similar composition to the sediment extract, except that there was a marked increase in the relative abundance of pristane, phytane, alkylcyclohexanes, steranes and hopanes relative to n-alkanes. We argue on the basis of the geological, geochemical and palynological data that G. prisca was probably planktonic, photosynthetic and very possibly eukaryotic and that the striking character of Ordovician oils and sediments derive from bacterial and other diagenetic imprints superimposed on the primary signature of this organism. 相似文献
16.
天津地区河流沉积物中中等分子量正构烷烃的分布特征 总被引：4，自引：0，他引：4
分析了天津地区几条具不同环境功能特征的河流沉积物中正构烷烃的组成，重点介绍了中低分子量正构烷烃的分布特征，并通过与表层土壤、大气降尘及TSP中正构烷烃的分布特征的对比，分析了中等分子量正构烷烃的成因。分析表明，天津地区主要河流沉积物和大气降尘中正构烷烃普遍具有正十七烷（nC17）明显优势的特征，nC17单体烃同位素值也相对偏低，与来源于化石燃料的正构烷烃化合物存在明显的差别。在土壤和TSP中不存在这一现象，表明正十七烷化合物来源水体中的低等水生生物体，推测主要来源于藻类生物。由于这类化合物含量明显高于其他化合物，具有环境地球化学意义。 相似文献
17.
A Recent unconsolidated lacustrine sediment was separated into five size fractions which were characterized by microscopy and XRD. Higher plant detritus predominated in the coarsest fractions, but decreased in proportion in the intermediate ones in which algal debris was predominant. The overall proportion of organic debris decreased from coarse to fine fractions. Quartz and feldspar were most abundant in the intermediate size fractions, while the coarsest fraction contained chlorite with some kaolinite and quartz, and the finest fraction was composed mainly of illite.Concentrations (per fraction dry weight) of solvent extract, total long chain hydrocarbons and total fatty acids decreased from coarse to fine fractions, with the exception of the finest fraction, in which they showed an increase. The change in relative abundance of higher plant to algal debris in the coarse and intermediate size fractions was paralleled by a decrease in the relative abundance of n-C29 and n-C31 alkanes and an increase in the relative abundance of -C17 alkane. There was a progressive decrease in n-alkane carbon preference index, and a progressive increase in the unresolved envelope of hydrocarbons with decreasing grain size. The unresolved hydrocarbons, which probably originate from biodegraded lubricating oil, appear to be associated with the clay fraction. Fractionation in this way and lipid analysis of the separate fractions may give more definitive information about input sources than analysis of unfractionated sediments. 相似文献
18.
19.
Normalized gas chromatograms of the normal alkane fraction extracted from 22 surface sediment samples from a salt marsh near Georgetown, South Carolina were submitted to an unmixing algorithm. This algorithm identified four end-number contributors, three of which very closely resemble n-alkane patterns from dominant plant species. The fourth end-member is apparently a mixture. Proportioning of the n-alkane patterns of the sediments suggests that the patterns reflect contributions from living surface plant material and dead plant material brought in by tides. The successful unmixing of complex patterns of alkanes from marsh sediments suggests a valuable new technique for the interpretation of chromatographic data. 相似文献
20.
油藏储层中不同赋存状态烃类地球化学特征:Ⅰ链烷烃--以鄂尔多斯盆地三叠系延长组为例 总被引：4，自引：0，他引：4
通过对鄂尔多斯盆地西峰油田三叠系延长组六个油砂样品中游离烃、封闭烃、碳酸盐胶结物烃、束缚烃和石英颗粒包裹体烃的分步分离和抽提,并对每类烃的不同馏分进行GC-MS分析。根据所分析样品的成岩作用序列,结合样品的结构特征,表明这一方法是可行的。通过对不同赋存状态链烷烃的研究表明,研究区正构烷烃峰型为单峰型,碳数分布广,具较弱的奇碳优势。烃类的母质类型显示为Ⅰ-Ⅱ型干酪根,形成于开阔水体条件下还原的淡水湖相环境。Pr/Ph比值、CPI值,在不同赋存状态烃中差异比较明显,大体上从游离烃、封闭烃、胶结物烃、束缚烃到包裹体烃有减小的趋势。结合其族组分特征,反映了油气演化的阶段性及其成藏期次和油藏微观的不均一性。 相似文献