Iron porphyrins in coal from the United States

Iron porphyrins have been isolated from seven U.S. humic coals of various geological ages. Mass spectrometry shows that for the higher rank coals the porphyrins comprise an homologous series of alkyl derivatives (C₂₇-C₃₂). Mesoheme is detected in a Cretaceous lignite from Montana.     

Biomarker patterns in a time-resolved holocene/terminal Pleistocene sedimentary sequence from the Guadiana river estuarine area (SW Portugal/Spain border)

The vertical distribution of terrestrial and phytoplankton biomarker compounds in a sediment core from the coastal estuarine zone of the Guadiana river (southwest border between Portugal and Spain) was determined by gas chromatography–mass spectrometry. Significant downcore fluctuations were observed in the patterns of the most abundant alkyl series (n-alkanes and n-fatty acids), as well as in several biomarker ratios. In addition, a specific contribution from conifers is reflected in the presence of a resin acid series that first appears 6500 years BP. The observed changes in the lipid assemblage within the Holocene suggest recent variations in the planktonic and terrigenous supply, which are attributed mainly to the evolution of the circulation pattern in the estuary and to the alteration of vegetation cover within the Guadiana drainage basin. Our data suggest that on a 10³–10⁴ year time-scale, little or no diagenetic change occurred with respect to the compounds in question.     

Microanalysis of primary fluid inclusions in halite: constraints for an evaporitic sedimentation modeling. Application to the Mulhouse Basin (France)

The chemistry of the waters from which the evaporitic minerals crystallized in the lower part of the Salt IV unit of the Mulhouse Basin (France) has been investigated. The lithological and fluid inclusion data have been compared to the output data of the mass transfer program NEWEQUI which simulates the change in brine composition during its evaporation advancement. The results show that the evolution of the composition of the brine is compatible with the calculated sequence of evaporation of a parent water corresponding to a seawater modified by CaCl₂-rich hydrothermal water. In the studied sequence fluid inclusion data provide useful constraints for reconstructing the paleoenvironment controlling the evaporitic sedimentation. They also provide data on the water stratification in the basin and on its connectivity with the open sea, and important parameters controlling the productivity (possible sources for the nutrients) and the preservation of organic matter in the sediment.     

Iron porphyrins in the Permian Kupferschiefer of the lower Rhine Basin, N.W. Germany

Immature samples of the Permian Kupferschiefer from the Lower Rhine Basin in N.W. Germany were analysed for tetrapyrrole pigment type and abundance. The sediment, thought to have been deposited in a marine regime with enhanced salinity, was found to contain high concentrations of metalloporphyrins. The porphyrins are complexed to nickel (Ni) and oxovanadium (V=0), but high abundances of iron (Fe) porphyrins were also detected using UV/visible spectroscopy and mass spectrometry. The presence in the latter of series of aetioporphyrins, cycloalkanoporphyrins, di-cycloalkanoporphyrins and benz-cycloalkanoporphyrins was confirmed by accurate mass measurements; HPLC co-injection of deoxophylloerythroetioporphyrin (C₃₂ DPEP) with the demetallated iron porphyrins indicated its presence in the sediment as an iron complex. The study provides the first evidence for the occurrence of Fe porphyrins in geological samples other than coals and lignites, and reports the highest concentrations in sedimentary organic matter to date.     

C25 and C30 biogenic alkenes in a sediment core from the upper anoxic basin of the Pettaquamscutt River (Rhode Island,U.S.A.)

Concentration profiles of five C₂₅ and C₃₀ biogenic alkenes in a sediment core collected from the upper anoxic basin of the Pettaquamscutt River have been determined. The five alkenes were identified usin gas chromatography/mass spectrometry as three isomeric C₂₅ dienes, a C₂₅ triene and a bicyclic C₃₀ diene. All five compounds exhibit subsurface concentration maxima, thought to result from either preservation of a past increase in alkene production or a current bacterial in situ production at depth. Similarities exist in the concentrations of two alkenes common to this core and a core from upper Narragansett Bay, despite significant differences in the origin and content of sedimentary organic matter (as inferred from organic carbon and δ ¹³C measurements) at each location. These observations support the proposed bacterial in situ synthesis of alkenes. Other alkenes, whose concentration in sediments had been previously correlated with the incidence of marine organic matter, were not detected in the upper basin sediments. Their absence is consistent with the range of organic carbon δ ¹³C values measured, which indicate that the component originating from marine sources is small. A comparison of organic carbon and δ ¹³C values in this core with those previously reported from a core collected in an adjoining basin indicate that the sedimentary regimes at the two sites differ despite their close proximity and similar hydrography.     

Distribution and significance of chlorophyll derivatives and oxidation products during the spring phytoplankton bloom in the Celtic Sea April 2002

The abundances and distributions of chlorophyll a and its common transformation products have been profiled by high performance liquid chromatography during the disruption, re-establishment, growth and senescence of a phytoplankton bloom in the Celtic Sea during April 2002. Transformation products of chlorophyll a indicative of herbivory of the phytoplankton bloom have been identified using atmospheric pressure chemical ionisation liquid chromatography-multistage mass spectrometry and chlorophyll oxidation products, formed by autoxidation, are present in increasing abundance in samples collected during the later stages of bloom development. The formation of oxidation products during the earliest stages in the chlorophyll transformation pathway identifies water column processes as sources of these early intermediates in the formation of geologic aetioporphyrins and/or cycloalkanoporphyrins.     

Aliphatic hydrocarbons in the bitumens of the Puertollano oil shales

The aliphatic fraction of the bitumens from 3 bands of the Puertollano oil shale field have been studied by gas chromatography and gas chromatography/mass spectrometry. Previous work published over the last years reached different conclusions about the origin of the organic matter in the Puertollano oil shales. A reappraisal of some of the biomarkers was then needed for a better understanding of the aliphatic hydrocarbons assemblage. The identified compounds, mainly n-alkanes in the medium to high boiling point region, acyclic isoprenoids and hopane-related compounds point towards a predominant algal/bacterial input. No unequivocally higher plant derived biomarkers have been detected in significant amounts, suggesting that the bulk of the organic matter derive from authocthonous organisms living in the basin. The biomarker maturity ratios indicate that the 3 Puertollano oil shales have similar maturities and are close to the onset of oil generation, assessing a slightly higher maturity than that determined by petrographic techniques.     

辽宁金羊盆地羊D1井油砂地球化学特征及意义

在中国地质调查局沈阳地质调查中心实施的"羊D1"井的中侏罗统髫髻山组火山岩中见多处油气显示,取得了油气新发现。对该井已发现的2件油砂样品中的原油采用气相色谱-质谱技术(GC-MS)进行了分析测试,结果显示,2个油砂样品的地球化学特征一致,表现为链烷烃呈现出单峰态的分布,主峰碳数分别为C_(21)和C_(22),无明显奇碳数优势,姥植比值低;萜类化合物表现为,三环萜烷以C_(23)为主峰呈正态分布,C_(24)四环萜烷与C_(26)三环萜烷丰度相当,伽马蜡烷含量较高;甾类化合物表现为规则甾烷相对含量关系为C_(27)C_(29)C_(28),以C_(27)甾烷占优势的不对称"V"形分布。这些指标总体指示,原油为成熟油,对应烃源岩沉积于偏还原性的湖相环境,母质来源主要为藻类等低等水生生物,陆源高等植物也具有一定贡献。通过和周边的北票组烃源岩进行油岩对比研究发现,油砂样品中的原油可能来自于盆地内下伏的下侏罗统北票组烃源岩的贡献。研究结果说明,北票组在金羊盆地分布广泛,其烃源岩可能具有较好的生油潜力,金羊盆地是一个具有勘探潜力的含油气盆地。     

Tetrapyrrole pigments in United States humic coals

Analyses of forty-two United States humic coals have revealed a striking divergence between chlorophyll diagenesis in coals when compared to the more widely studied marine sediments, shales, asphalts and petroleums. Porphyrins of humic coals have been found to be dominated by the ETIO-series, to lack members above C-32, and, in lower ranked samples (e.g. Sub-bituminous-B, high volatile C) to exhibit mass spectral envelopes with unique even-carbon number predominances. The weighted average mass, as well as the carbon number maximum (viz. mode), of these coal porphyrin homologies has been found to decrease as rank increases. The generation of porphyrins of the ETIO-series is suggested as occurring both during early coal formation, including oxidative scission of the isocyclic ring at the phorbide stage, and later during the catagenic alteration of surviving DPEP-series porphyrins. A preliminary study of chlorophyll diagenesis in a South Florida peat partially substantiates this suggestion and has further shown that the coal porphyrins can be derived from bacterial, as well as higher plant, chlorophylls.     

Holocene History of the Chocó Rain Forest from Laguna Piusbi, Southern Pacific Lowlands of Colombia

A high-resolution pollen record from a 5-m-long sediment core from the closed-lake basin Laguna Piusbi in the southern Colombian Pacific lowlands of Chocó, dated by 11 AMS¹⁴C dates that range from ca. 7670 to 220¹⁴C yr B.P., represents the first Holocene record from the Chocó rain forest area. The interval between 7600 and 6100¹⁴C yr B.P. (500–265 cm), composed of sandy clays that accumulated during the initial phase of lake formation, is almost barren of pollen. Fungal spores and the presence of herbs and disturbance taxa suggest the basin was at least temporarily inundated and the vegetation was open. The closed lake basin might have formed during an earthquake, probably about 4400¹⁴C yr B.P. From the interval of about 6000¹⁴C yr B.P. onwards, 200 different pollen and spore types were identified in the core, illustrating a diverse floristic composition of the local rain forest. Main taxa are Moraceae/Urticaceae,Cecropia,Melastomataceae/Combretaceae,Acalypha, Alchornea,Fabaceae,Mimosa, Piper, Protium, Sloanea, Euterpe/Geonoma, Socratea,andWettinia.Little change took place during that time interval. Compared to the pollen records from the rain forests of the Colombian Amazon basin and adjacent savannas, the Chocó rain forest ecosystem has been very stable during the late Holocene. Paleoindians probably lived there at least since 3460¹⁴C yr B.P. Evidence of agricultural activity, shown by cultivation ofZea maissurrounding the lake, spans the last 1710 yr. Past and present very moist climate and little human influence are important factors in maintaining the stable ecosystem and high biodiversity of the Chocó rain forest.     

Extracts of impact breccia samples from Sudbury, Gardnos, and Ries impact craters and the effects of aggregation on C60 detection

Fullerenes have been detected in carbonaceous chondrite meteorites and in breccia samples from meteorite impact craters, but questions have been raised about contradictory results from similar samples and the sensitivities and accuracies of different analytical methods. We analyzed samples from three impact craters and detected C₆₀ in samples from several locations; we also observed differences in the detection capabilities of various analytical techniques used in the search for fullerenes. The presence of C₆₀ in rocks from the Onaping Formation of the Sudbury impact crater was confirmed. Low levels of C₆₀ were also detected for the first time in samples from the Gardnos (Norway) and Ries (Germany) impact structures.We detected C₆₀ in these samples using surface-enhanced laser desorption/ ionization (SELDI), but the related technique of microprobe laser-desorption, laser-ionization mass spectrometry (μL²MS) did not observe C₆₀ above detection limits. We attribute the absence of μL²MS signal to aggregate formation caused by phthalic acid esters, which appear to easily contaminate samples either during storage or demineralization in plastic containers. The μL²MS technique is incapable of detecting aggregated C₆₀, but aggregation does not suppress detection in SELDI. Phthalate-induced aggregation did, however, enhance SELDI detection of C₆₀ in some cases, and we suggest that this enhancement may help explain previously reported differences in C₆₀ detection from natural samples between laser desorption mass spectrometry (LDMS, a technique analogous to SELDI that has detected fullerenes in meteorite and impact breccia samples) and high-pressure liquid chromatography (HPLC). This work highlights the effects of phthalates and other indigenous compounds or contaminants on certain mass spectrometric techniques and lends support to the idea that several complementary analytical methods should be employed to investigate complex natural samples.     

Structures and profiles of novel sulfur-linked chlorophyll derivatives in an Antarctic lake sediment

High performance liquid chromatography-mass spectrometry has permitted the identification of a homologous series of novel alkylsulfide derivatives of chlorophyll a containing between one and five carbon atoms, in sediment from a coastal Antarctic lake. The sulfur-containing compounds are present in varying abundance in stratigraphic horizons representing a phase when the lake was a marine basin. Throughout this marine phase photic zone anoxia is recorded by the presence of bacteriochlorophyll c and d-derivatives. Distributional variations between sulfurised and non-sulfurised chlorophyll a-derivatives throughout the sediment section studied indicate that the extent of sulfurisation is not controlled by chlorophyll a abundance alone.     

Structural variations in derivatives of the bacteriochlorophylls of Chlorobiaceae: impact of stratigraphic resolution on depth profiles as revealed by methanolysis

Bacteriochlorophylls c and d, recovered from two sedimentary sequences, were converted to bacteriophaeophorbide methyl esters by methanolysis and analysed by atmospheric pressure chemical ionisation liquid chromatography-multistage mass spectrometry (APCI LC-MSⁿ). The distributions in both settings, a moderately consolidated sediment from Kirisjes Pond, Antarctica, and in a finely laminated microbial mat from Les Salines de la Trinitat, Spain, show significant variations within a narrow depth interval. The overall bacteriophaeophorbide c to d ratios in the two sediments are different, as are the ratios of particular C-3¹ diastereoisomers, indicating distinct differences between the bacterial communities that contributed to each sediment. Furthermore, a shift towards more extensive alkylation in homologues within each sediment is consistent either with changing environmental conditions in the depositional environments, or development-related changes in the structure of the bacterial community, leading to increased competition for light or nutrients.     

The petroporphyrins of a Cretaceous oil

The petroporphyrins of a Cretaceous crude oil, La Paz, from western Venezuela are shown to be a mixture of etio and DPEP homologues (C₂₇-C₃₉) maximising at C₃₀ and C₃₁, respectively. Minor amounts of rhodoporphyrins (C₃₀-C₃₉) are also present. Thin-layer chromatography afforded fractions which have been shown by mass spectrometry to contain up to 80% of a single-molecular-weight species. Oxidative degradation of La Paz petroporphyrins to maleimides and mass-spectrometric study of t.l.c. fractions indicate that some of these porphyrins are to a great extent incompletely substituted. Dealkylation reactions have presumably played an important role in their geologic history. Furthermore, the relative simplicity of the alkyl substitution pattern of the La Paz petroporphyrins suggests that transalkylation reactions have not taken place to any significant extent.The fraction of petroporphyrins isolated from the asphaltenes contains a higher proportion of the DPEP homologues than do the total petroporphyrins isolated from the original crude oil.     

An investigation of the structure of abelsonites from the Uinta Basin of Utah

Abelsonite has been obtained from five widely separated cores in the Green River Formation of Utah. Each occurrence was in fractures or bedding plane partings of lean oil shales. High resolution mass spectra show that the abelsonite samples are vitually identical from core to core and consist largely of the nickel complex of a C-31 porphyrin of DPEP type. ¹H-NMR spectra of some of the samples have been recorded and are compared with spectra of several model nickel porphyrin complexes. From these spectra it is deduced that abelsonite is largely the nickel complex of a nor-DPEP. Abelsonite is believed to differ from nickel DPEP in having a methyl substituent in place of an ethyl substituent at either carbon 3 or 8. Abelsonite is shown not to have a hydrogen substituent on any pyrrolic carbon. A chlorophyll origin of abelsonite is thus indicated. Abelsonite appears to have been introduced into the fractures and bedding planes of the rocks in which it is found subsequent to their lithification, as porphyrins different from abelsonite were extracted from shales associated with abelsonite.     

Bacteriohopanepolyol biomarker composition of organic matter exported to the Arctic Ocean by seven of the major Arctic rivers

Bacteriohopanepolyols (BHPs) are a diverse group of membrane lipids produced by a wide variety of bacteria and can be used as molecular biomarkers for bacterial processes and populations in both modern and ancient environments. A group of BHPs, including adenosylhopane and structurally related compounds, have been identified as being specific to soils, enabling the transport of terrestrial organic matter (terrOM) to the marine realm to be monitored. Estuary surface sediment samples were obtained from the five Great Russian Arctic Rivers (GRARs; Ob, Yenisey, Lena, Indigirka and Kolyma) and river sediments were obtained from two North American Rivers (Yukon and Mackenzie). Analysis of the BHP signatures, using high performance liquid chromatography–tandem mass spectrometry (HPLC–MSⁿ), indicated the presence of 15 different BHPs originating from a variety of different bacteria, as well as a significant presence of terrestrially derived OM. Total BHP abundance and the contribution of the “soil-marker” BHPs to the total BHP pool increased eastwards among the GRAR sediments. This suggests increasing terrestrial OM or increased preservation of OM as a result of shorter periods of permafrost thawing. The North American rivers showed greatly differing BHP levels between the Yukon and Mackenzie rivers, with a greater BHP input and thus a relatively higher soil OM contribution from the Yukon. The Indigirka River basin in the eastern Siberian Arctic appeared to be the epicentre in the pan-Arctic BHP distribution trend, with the highest “soil-marker” BHPs but the lowest tetrafunctionalised BHPs. Aminobacteriohopanepentol, an indicator of aerobic methane oxidation, was observed in all the sediments, with the source being either the marine environment or methane producing terrestrial environments.     

Organic matter accumulation during the Holocene in the Guadalquivir marshlands (SW Spain)

The distribution of biomarker compounds and magnetic susceptibility observed in the sediment from a 20 m core drilled in the marshlands of the estuarine region of the Guadalquivir River (southwest coast of Spain) has allowed us to reconstruct the palaeoenvironmental evolution of this area during the Holocene. Several organic compounds (n‐alkanes, n‐ketones, n‐alkanols, n‐alkanoic acids and organic sulphur), as well as different biomarker ratios, have been used to show changing environmental conditions through time. These geochemical proxies suggest good preservation of the organic matter, although some diagenesis has occurred to particular organic compounds, especially the n‐alkanoic acids. Our data indicate a major allochthonous supply of terrestrial plants, with less influence from aquatic plants or algae through the core. There are markedly different palaeoenvironmental conditions between the uppermost 5 m (last 6 ka cal. B.P.) and the rest of the core. From 5 m (ca 6 ka cal. B.P.) to 19 m (ca 8 ka cal. B.P.) depth the palaeoenvironmental conditions were almost constant. Based on organic sulphur content and n‐alkane content logs, anoxic conditions prevailed from 8 to 6 ka cal. B.P., while oxic conditions with enhanced convection of water (prevalence of fluvial input), and consequently a greater organic matter supply, predominated in the upper 5 m of the core. Similarly, little variation in the magnetic susceptibility profile below 5 m indicates stable environmental conditions, while in the upper 5 m conditions shifted to one with elevated water input and clastic sediment supply. This is linked to palaeofloral alterations in the Guadiamar/Guadalquivir drainage basins and/or anthropogenic effects. We propose that from ca 8 to 6 ka cal. B.P. a stable landscape physiognomy in the surroundings of the estuarine area of the Guadalquivir River, with a predominance of pines and grassland. However, over the last 6 ka cal. B.P. a variation in the terrestrial plant biomarker compounds suggests an alternation of relatively dry and humid phases and/or the impact of human populations on altering the vegetation community have occurred. Copyright © 2007 John Wiley & Sons, Ltd.     

Paleophytochemical Constituents from the Pliocene Fossil Wood of Pinus Armandii from Longling,Yunnan

Specimens of fossil wood preserved lignified in Pliocene brown coal and identified as Pinus armandii Francher come from an opencast coalmine at Longling in western Yunnan Province, China. Phytochemical investigation of the fossil wood isolated using liquid column chromatography seven compounds （1-7） including a new fluorene derivative named 11,11-dimethyl-11H-benzo[b]fluorene. A further 28 volatiles were detected by gas chromatography-mass spectrometry （GC-MS）. Spectroscopic investigation methods, including MS and 1D and 2D-NMR techniques elucidated the structure of the seven compounds. Two types of natural products, isopimara and stilbene commonly occuring in extant and Pliocene fossil P. armandii indicate phytochemical fidelity during burial under certain circumstances in sediments. Discovery of stilbenes that can inhibit the activities of wood-destroying fungi in the Pliocene P. armandii prompts the assumption that the chemical preservation of this Pliocene fossil wood of P. armandii in brown coal might contribute to the presence of inner natural inhibitors against wood-destroying fungi.     

Evidence of the transgression lake of the Subei basin during Late Cretaceous and Paleocene and its geological significance

Based on analysis of the well drilling core from Subei basin, the authors conclude that during the Late Cretaceous and Paleocene, Subei basin was linked with the sea and the deposit was affected by transgression. The cause of marine transgression may be that since Late Cretaceous and Paleocene tension power had predominated ground-stress conditions of the East China Sea and developed a series of half-graben-like basins filled by a huge thick sediment of the Early Tertiary in the shelf of Huabei-Bohai gulf, Subei-South Yellow Sea and East China Sea. Consequently, seawater transgressed from the East China Sea to the Yellow Sea and linked halfgraben-like basins on the shelf to the sea within a short period. During the sedimentation of the Late Cretaceous Taizhou Formation and Paleocene Funing Formation, the Subei basin had formed the ostracoda-enriched dark shale, including predominantly the whole basin E₁ f ₂ Formation and E₁ f ₄ Formation and local K₂ t ₂ Formation, which became the main source rocks of the basin. The evidence of paleontology, minerals in rocks and geochemistry can help confirm the environment of the lake basin that developed during the Late Cretaceous and Paleocene. We generally designate this environment as “near sea lake basin” and the sea-transgressed layer and member as “transgression lake basin”.Whereas, it is generally called “inland lake and river alluvium plain” during the sedimentation of the Eocene Dainan Formation and Sanduo Formation. This research is not only significant to the paleogeographic reconstruction of the Subei basin during the Late Cretaceous and Paleocene, but also important in understanding the development and distribution of the source rocks and evaluating the potential of oil and gas generation. __________ Translated from Acta Sedimentologica Sinica, 2007, 25(3): 380–385 [译自: 沉积学报]     

A late Quaternary sedimentary record of steryl alkyl ethers from offshore southeastern Australia

Steryl alkyl ethers (SAEs) have been reported from marine sediments ranging from Holocene to Lower Cretaceous and their production has been linked to upwelling of cold, nutrient-rich water. However, the lack of continuous stratigraphic records for them has complicated validation of the precise connection of their production, sedimentary distribution and survival to climatic conditions. Here, we report an SAE record that spans the last ca. 135 ka from a core taken offshore southeastern Australia in the Murray Canyons Group region. The SAEs are composed predominantly of C₂₇–C₃₀ steroid moieties with one or two double bonds, ether-bound to C₁₀–C₁₁ alkyl moieties. Some of the SAEs are identical to those reported in marine sediments, whereas others have not been identified previously. They do not exhibit any systematic change in distribution over the past 110 ka but sediments older than 110 ka possess a different assemblage, with a higher amount of constituents containing a C₁₁ alkyl moiety. The SAE accumulation rate increases rapidly during glacial episodes and for intervals characterized by a sharp decline in sea-surface temperature. The results suggest that SAEs may be related to marine eukaryotes that thrive when there is an influx of cold, deep waters in the Murray Canyons Group region, likely triggered by stronger westerlies over southeastern Australia forcing deeper water to reach the surface during glacials.