Biological Marker Distributions Research Articles

Differences in Clinical Course and Management of Sars-CoV2 Infection in Patients with Chronic Lymphocytic Leukemia between the Sequential Pandemic Phases: An Eric Study

BACKGROUND. Infection by SARS-CoV2 remains a worldwide health burden. Previous studies by the ERIC (European Research Initiative on CLL) showed that patients with chronic lymphocytic leukemia (CLL) have a very-high risk of severe Coronavirus disease 19 (COVID19). In particular, age, CLL-directed treatment, and cardiac failure were identified as significant risk factors of overall survival (OS). Since the beginning of 2020 different treatment strategies have been used to fight COVID19 and different SARS-CoV2 variants alternated during the pandemic, however very few studies analyzed their impact on patients with CLL. AIMS. The aims of this study were to investigate different manifestations, treatments and outcome of COVID19 in patients with CLL/SLL (small lymphocytic lymphoma), and MBL (monoclonal B-cell lymphocytosis). METHODS. This is a retrospective international multicenter ERIC study from Jan 2020 till May 2022. CLL diagnosis, COVID-19 management, review of medical history, and assessment of patient status were performed by local investigators following international guidelines. Ninety institutions participated in the study. Statistical analyses were conducted using R software. During the pandemic we identified 4 phases: 1st Jan 2020 - Jun 2020, 2nd Jul 2020 - Feb 2021, 3rd Mar 2021 - Dec 2021 and 4th Jan 2022 - May 2022. RESULTS. We gathered data from 1540 patients (93.8% CLL, 4.1% SLL and 2.1% MBL), 65% males, the median age at COVID19 was 69 years, median CIRS score was 4 (IQR 2-7), 49.6% were treated in the last 12 months before COVID19, 38.8% was on treatment at COVID19 onset (BTK inhibitor-based 51.1%, BCL2 inhibitor-based 20.7%, chemo/chemoimmunotherapy 21.5%, 6.7% others). Overall, 34.4% of patients was managed at home, 49.9% needed hospitalization and 15.7% was admitted to the intensive care unit (ICU). After a median follow-up of 2.7 months, the infection was resolved in 1124/1540 (73%) cases, while 23% died and 3.6% were still under medical observation. Distribution of patients among time is shown in Fig. 1A. Three hundred and four (19.8%) patients were infected during the 1st, 737 (48%) during the 2nd, 137 (8.9%) during the 3rd and 357 (23.3%) during the last 4th phase. Comparing the features of patients infected in different phases, age at COVID19 and distribution of biological markers were similar, but more patients in the latter phases suffered from arrhythmias (8.2% vs 10.5% vs 16.1% vs 14.2%, p=0.01), chronic renal disease (3.9% vs 5.9% vs 8.9% and 11.1%, p=0.003) and other malignancies (0.3% vs 1.8% vs 2.2% vs 3.6%, p=0.04). Vaccinated patients (0% vs 0.4% vs 45.7% vs 89.1%, p<0.001) and those treated for CLL in the last 12 months (44.1% vs 44.1% vs 55.7% vs 66.1%, p<0.001) were also more common in the last phases. COVID19 signs and symptoms differed between early and late phases, with less fever (p<0.001) and dyspnea (p=0.028) but more fatigue (p<0.001), cough (p<0.001), headache (p<0.001), anosmia/ageusia (p<0.001) and myalgia/arthralgia (p<0.001) in the later phases. COVID19 management also changed over time, with less patients receiving a SARS-CoV2 therapy (87.6% vs 74.7% vs 78.1% vs 67.9%, p<0.001). In particular, hydroxychloroquine, azithromycin, steroids and anti-IL6/IL6R were more commonly used in the first 2 phases while antiviral and monoclonal antibodies (mAb) were mainly employed in the last 2 phases. Less patients were hospitalized (84.5% vs 67.3% vs 60.3% vs 45.8%, p<0.001), needed ICU admission (20.6% vs 17.2% vs 13.3% vs 8.1%, p<0.001) or died (29.8% vs 25.5% vs 21.8% vs 15.8%, p=0.002) through these phases. These improvements in patients' management led to an increase of OS, with 2-month OS of 70%, 74%, 81% and 83% for patients diagnosed during the 1st, 2nd,3rd and 4th phase (p=0.0015, Fig. 1B). CONCLUSION. We analyzed one of the largest series of patients with CLL infected by SARS-CoV2 over more than 2 years of COVID19 pandemic. Patients infected during the most recent phases, though carrying a higher comorbidity burden, were less frequently hospitalized, only rarely needed ICU admission and died due to the SARS-CoV2 infection in a lower proportion compared to initial phases. The improvement in COVID-19 management with effective antiviral drugs, mAb and the high rate of vaccination together with the change in SARS-CoV2 variants over time may have played an important role in this outcome. AV, LS, TC, AK, CD and GK equally contributed. KS and PG are both last authors. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Brain location and tumor biological markers in high- and low-grade gliomas.

Recent studies suggest gliomas location may be correlated with specific biological signatures. Our purpose was to focus on the possible correlation between MGMT metilation status and Ki67 positivity with patient age, glioma location and lateralization. We performed a retrospective evaluation to assess the correlation between MGMT metilation status and Ki67 index positivity with patient age, glioma location and lateralization. The study included 174 supratentorial gliomas. Of these, 144 tumors were high grade gliomas (HGGs), and 30 tumors were low grade gliomas (LGGs). In HGG group we detected an association between tumor location and MGMT status. Those GBMs located in the frontal lobe were significantly associated with MGMT methylated status (MGMT+) and Ki67<30% than those GBMs located in other sites; while those GBMs located in the temporal lobe were associated with MGMT unmethylated (MGMT-) status. In anaplastic gliomas, we found an association between the involvement of the frontal lobe with MGMT+ status and Ki67<30%. In LGG group, our results showed that both frontal and temporal lobe were associated with a Ki67<30% and there was a predictive value for MGMT methylation status when patient age increased. Our findings suggest there is a high variability in anatomical distribution of biological glioma markers and this high heterogeneity may have a clinical role. Moreover, our study supports the idea that frontal lobe HGGs may be biologically favorable. Considering that as all glioma with lobar location are more amenable to radical surgical resection, it may be assumed that frontal tumor can have a better prognosis, and we have shown, to our knowledge for the first time, this is true both for HGG and for LGG.

Geochromatographic migration of oil pollution from a heating plant to river sediments

Many pollution sources are difficult to identify because pollutants are transported far away into complex environments. In particular, the mechanisms of petroleum migration in sediments are poorly known. Here, we studied two sediments from the circuit of a heating plant and three sediments located at 100, 200 and 300 m away from the plant. Saturated hydrocarbons were isolated and group composition was determined by column chromatography. n-Alkanes, terpanes and steranes were analyzed by gas chromatography-mass spectrometry. Results show that the amount of short n-alkanes increases during migration, which indicates the migration mechanism. Results on steranes reveal a geochromatographic migration of the oil, where the fastest eluting stereoisomers display the longest migration path. Changes in the distribution of biological markers are explained by migration in water.

A simple method for isolating rat brain mitochondria with high metabolic activity: Effects of EDTA and EGTA

Isolated mitochondria are widely used in metabolic and oxidative stress studies for neurodegenerative diseases. In the present work, the influence of EGTA and EDTA has been tested on a sucrose-based differential centrifugation protocol in order to establish the optimal concentrations to be used in this process. Our results showed alterations in both active and resting respiration, which were dependent on both the addition of EDTA or EGTA to the isolation buffer and the chelator concentration used. However, the addition of chelator to the isolation medium does not modify the mitochondria structure as assessed by both distribution of biological markers and electron micrography in the final pellet. Our results endorse this protocol as the method of choice for metabolic and oxidative stress experiments with fresh isolated rat brain mitochondria.

Petroleum composition in the Cuu Long Basin (Mekong Basin) offshore southern Vietnam

The Cuu Long Basin (Mekong Basin) is a rift basin off southern Vietnam, and the most important petroleum producing basin in the country. However, information on petroleum type and characteristics has hitherto been largely unavailable to the public. This paper presents petroleum geochemical data on nine oil samples from four different producing fields in the Cuu Long Basin: the Dragon (Rong), Black Lion (Sutu-Den), Sunrise (Rang Đong) and White Tiger (Bach Ho) Fields. The oils are highly paraffinic with bimodal normal alkane distributions and show moderate pristane to phytane ratios and a conspicuous hyperbolic decrease in abundance with increasing carbon number of hopane homologues from C 30 to C 35. The TPP-index of Holba et al. (Holba, A.G., Dzou, L.I., Wood, G.D., Ellis, L., Adam, P., Schaeffer, P., Albrecht, P., Greene, T., Hughes, W.B., 2003. Application of tetracyclic polyprenoids as indicators of input from fresh–brackish water environments. Organic Geochemistry 34, 441–469) is equal to 1 in all samples which in combination with tricyclic triperpane T26/T25 ratios >1 and the n-alkane and hopane distributions mentioned above provide a strong indication of an origin from lacustrine source rocks. This is supported by the absence of marine C 30 desmethyl steranes (i.e. 24- n-propylcholestanes) and marine diatom-derived norcholestanes. Based on the overall biological marker distributions, the lakes probably belonged to the overfilled or balanced-fill types defined by Bohacs et al. (Bohacs, K.M., Carroll, A.R., Neal, J.E., Mankiewicz, P.J., 2000. Lake-basin type, source potential, and hydrocarbon character. An integrated sequence-stratigraphic–geochemical framework. AAPG Studies in Geology 46, 3–34). The oils were generated from source rocks at early- to mid-oil-window maturity, presumably Oligocene lacustrine shales that are present in the syn-rift succession. Oils from individual fields may, however, be distinguished by a combination of biological marker parameters, such as the oleanane index, the gammacerane index, the relative abundance of tricyclic terpanes, the proportions of diasteranes and 28-norspergulane, complemented by other parameters. The oils of the Cuu Long Basin show an overall similarity to the B-10 oil from the Song Hong Basin off northern Vietnam, but are markedly different from the seepage oils known from Dam Thi Nai on the coast of central Vietnam.

Origin of oils in the Velebit oil–gas field, SE Pannonian Basin, Serbia – Source rocks characterization based on biological marker distributions

Twenty five crude oil samples from Velebit oil–gas field (SE Pannonian Basin, Serbia) were investigated in order to define the depositional environment, lithology, thermal maturity and depth of burial of the corresponding source rocks. Saturated biomarkers ( n-alkanes, isoprenoids, steranes and triterpanes) were determined using gas chromatography (GC) and gas chromatography–mass spectrometry–mass spectrometry (GC–MS–MS). Source and maturity parameters were calculated from the distribution and abundance of biomarker compounds and principal component analysis (PCA) was used to interpret their relationships. The Velebit crude oils were generated from siliciclastic source rocks containing a mixture of terrestrial and marine organic matter that was deposited under a predominantly reducing environment, probably in the distal marine portion of a delta. Maturation parameters indicated significant thermal maturity corresponding to peak oil generation. Age-diagnostic biomarker ratios suggest that the source of Velebit oils may be Upper Cretaceous, older than most oils in the Pannonian Basin, which are generated from Tertiary sources. These source rocks are thought to be at a present-day depth of approximately 3000 m, within or in close proximity to, the oil field.

Application of biological markers for the identification of oil-type pollutants in recent sediments: Alluvial formation of the Danube river, Oil refinery Pancevo

The purpose of this paper was to examine to which extent the abundance and distribution of certain biological markers may be used for the identification of oil-type pollutants in recent sediments and ground waters. The samples were taken from the area of the Oil Refinery Pancevo (alluvial formation of the Danube River). The organic matter of the investigated samples was isolated using an extraction method with chloroform. The group composition and usual biological markers were analyzed in the obtained extracts. n-Alkanes and acyclic isoprenoids, pristane and phytane were analyzed using gas chromatographie (GC) analysis of saturated hydrocarbons. Polycyclic alkanes of the sterane and terpane type were analyzed using gas chromatography-mass spectrometry (GC-MS), i.e. by analyzing the carbamide non-adduct of the total alkane fraction (Single Ion Monitoring SIM-technique). The obtained results indicate that n-alkanes can be used for the identification of oil-type pollutants (for example, if the oil-pollutant is biodegraded or present in very low concentrations), and steranes and triterpanes can be used as very reliable indicators of oil-type pollution in recent sediments and ground waters.

The Mupe Bay oil seep: a detailed organic geochemical study of a controversial outcrop

Abstract The oil seep in an intraformational conglomerate at Mupe Bay has attracted much interest as providing possible evidence of oil generation in the Wessex Basin by the early Cretaceous (Wealden). Previous organic geochemical studies investigating whether oils of different maturity exist in the clasts and matrix of the conglomerate have been complicated by the effects of heavy biodegradation of the oil. In this work, we present detailed molecular organic geochemical data from a significantly larger suite of samples than has been previously studied. These have been screened using a multivariate statistical approach to identify those samples which have been least influenced by biodegradation. Conventional molecular maturity parameters applied to the subset of samples which have suffered no detectable modification to their biological marker (hopane and sterane) distributions indicate that the oil in the clasts is of exactly the same maturity as that in the matrix. However, this observation does not preclude two phases of staining, although it remains to be proven that the clasts contained oil at the time of their deposition.

Biodegradation of seep oils in the Wessex Basin — a complication for correlation

Abstract A detailed organic geochemical investigation of seep oils from the Dorset coast has revealed notable variation in both the extent and pathways of biodegradation. All the seep samples analysed from Mupe Bay, Stair Hole (near Lulworth Cove) and Osmington Mills have had their n -alkanes and acyclic isoprenoid alkanes removed, but some samples are more extensively degraded, with partial loss of steranes and/or hopanes. At Mupe Bay (conglomerate matrix samples; see Parfitt &amp; Farrimond 1977 this volume) the hopanes have been preferentially attacked, whilst at Stair Hole the steranes appear heavily degraded although there has been no alteration to the hopane distribution. 25-Norhopanes were not detected in any of the samples. Biological marker distributions of seep oils which have suffered no hopane or sterane biodegradation are compared with those of three reservoired oils from the area (Wytch Farm and Kimmeridge fields). Molecular parameters indicate significant variation in source rock facies and maturity within the oils of the Wessex Basin.

The oil potential of Mid-Jurassic coals in northern Egypt

Abstract Geochemical analysis of selected coals indicates that some of the Jurassic coals in Egypt have oil-generating potential. Other coals have just gas potential, but may have already generated oils as they are now post-mature for oil generation. Petrographic analysis of the coals reveals a composition dominated by vitrinite, but with variable liptinite contents and the occurrence of fluorescent vitrinite in some coals. It is not clear which components of the coal are responsible for the oil potential; it is probable that liptinite, hydrogen-rich vitrinites and a fine-grained groundmass of algal origin all contribute. A combination of Rock-Eval Hydrogen Indices and pyrolysis-gc P2 fingerprints provides the best method for determination of the oil- or gas-prone nature of the coals. Attempts at correlating oils to source rock extracts illustrate the problem of oil-source correlations involving a rapidly varying source rock environment. The bitumen extracts from the coals reveal variable characteristics which reflect facies variations in the coals. Several of the coals have unusual saturated hydrocarbon and biological marker distributions that are atypical of humic coals and give a poor correlation to the waxy oils from the Meleiha field. The best oil-source rock correlation is with a carbonaceous shale, not a coal, but it is likely the oils were derived from large volumes of source rock including coals and carbonaceous shales. As the coals have unusual extract characteristics, any oils derived from a more localized environment in the coal swamp may show very unusual geochemical characteristics, and would not be recognized immediately as being derived from terrestrial coals.

The interrelationship of biological marker maturity parameters and molecular yields during contact metamorphism

Jurassic siltstone samples were collected, on a centimetre scale, as a function of increasing distance from a dolerite dyke (Isle of Skye, northwest Scotland). The constant origin and type of the organic matter in this single lithological horizon is indicated by organic petrological observations as well as organic geochemical analyses. Therefore, changes in biological marker distributions, with distance from the dyke contact, can be unequivocally correlated with the thermal influence of the intrusion. The vitrinite reflectance ( R 0 Average) values of these samples increase gradually from 0.35% to 3.60% as the dyke contact is approached. Four classical biological marker maturity parameters ( 20S (20S + 20R) , TA (TA + MA) , C 20 (C 20 + C 28) , and 22S (22S + 22R) ). have been measured from GCMS analyses of the sample extracts. Changes in these molecular parameters were compared with changes in the concentrations of the individual biological marker compounds, expressed relative to mass of rock extracted. This comparison revealed that these molecular parameters are not governed by the conventional productreactant relationships (chiral isomerisation, aromatisation or side-chain cracking reactions) operating solely in the free saturated or aromatic hydrocarbon structures. Release/formation from macromolecular and/or functionalised moieties (hydrocarbon or non-hydrocarbon) followed by compound loss provide an alternative paradigm in all four cases in this particular thermal regime. Direct chiral isomerisation in the free sterane or homohopane cannot, however, be completely ruled out as a contributor to an admixture of processes. Similarly, aromatisation in the free hydrocarbon fraction may account for a proportion of the triaromatic steroids.

An organic geochemical study of bitumens and their potential source rocks from the South Pennine Orefield, Central England

Bitumens associated with PbZn mineralisation hosted by upper Dinantian limestones in the South Pennine Orefield (Derbyshire, Central England) were characterised in terms of maturity as well as source/correlation parameters, and compared with hydrocarbons from the East Midlands oilfield and bitumens from the Cheshire Basin. Potential source rocks from within the Dinantian sequence and from the lower Namurian mudstones of adjacent Carboniferous sedimentary basins were characterised in a similar fashion. The bitumens from both Derbyshire and Cheshire show a range of effects due to biodegradation and water washing, from partial to complete removal of n-alkanes, isoprenoids and polyaromatic hydrocarbons. The bitumen/oil suite (Derbyshire bitumens, Cheshire bitumens and East Midlands oils) show mature biological marker distributions. Whilst the Derbyshire bitumens and East Midlands oils generally correlate well with each other, bitumens from Cheshire show distinct differences. On the grounds of maturity and source/correlation biological marker characteristics, it is possible to suggest likely source rocks for the Derbyshire bitumens and East Midlands oils. Using a “multiparameter approach”, lower Namurian mudstones from the Widmerpool Gulf, along with those from the Gainsborough and Goyt Troughs, are not regarded as source rocks. The lower Namurian mudstones from the Edale Gulf correlated with the East Midlands oils and Derbyshire bitumens on the basis of a restricted number of biological marker compound classes. Bulk and molecular maturity parameters also indicate that these particular formations could have generated hydrocarbons. More local contributions to the Derbyshire bitumens may have been made by some of the organic-rich mudstones within the Dinantian succession.

The Habitat of Petroleum in the Brazilian Marginal Basins: A Paleoenvironmental and Biological Marker Approach

A geochemical survey of Brazilian marginal basins using a wide selection of oils and source rocks ranging from Lower Cretaceous to Tertiary in age, has been undertaken. The aims were to review and assess the hydrocarbon source potential, characterize the depositional paleoenvironment of the source rocks and to correlate reservoired oils with their putative source rocks. This approach was based mainly on the distribution and absolute concentrations of biological markers. Integration of the results with geological and paleontological data Provides recognition and differentiation of six source rock systems deposited in the following environments: lacustrine freshwater, lacustrine brackish to saline water marine deltaic with carbonate influence. The analyses of the oil samples reveal significant differences among groups which enable a correlation with putative source rocks laid down in all the six of the above depositional environments. Presently, the Brazilian marginal basins have a potential reserve of about 40 billion barrels of oil-in-place, with 95% of them being sourced by rift-phase lacustrine environments. This study also provides a framework of bulk, elemental, and especially environmental and biological marker characteristics which can be compared with samples from other basins of the world.

Dinosteranes (4,23,24-trimethylsteranes) and other biological markers in dinoglagellate-rich marine sediments of Rhaetian age

Alkane biological marker distributions and concentrations have been determined in 18 samples from a section of Rhaetian age from the Bristol Trough and a quantitative micropalaeontological analysis carried out. Taking into account previous geological investigations of the sequence, three “end-member” depositional settings have been recognised from changes in total organic carbon content, the biological markers and the micropalaeontological composition. These depositional environments are attributed as follows. The first, which occurs in the lower part of the section, corresponds to deposition in a supratidal/sabkha-type setting with the major organic input being of allochthonous origin. The second, also in the lower part of the section, indicates the occurrence of periods of marine incursion, with enhanced salinity resulting from evaporation. In the upper part of the section marginal marine conditions are apparent, with higher organic carbon, biological marker and amorphous organic matter contents at the top, suggesting the establishment of more stable conditions of oxygen depletion. Some sediments in the sequence are notable for containing an abundance of cysts of Rhaetogonyaulax rhaetica, one of the oldest marine dinoflagellates. Comparison of microfossil abundances with hydrocarbon abundances extends the circumstantial evidence for the Dinophyceae being the major biological source of dinosteranes (4,23,24-trimethylcholestanes) and some other 4-methyl steranes in marine sediments. The presence of dinosteranes and their 24-ethyl counterparts extends the stratigraphic range of occurrence of such components back to the Rhaetian. C 31 methyl steranes in the sediments from the second depositional setting are tentatively assigned a 4,22,23,24-tetramethyl-sterane skeleton and a dinoflagellate origin.

Geochemistry of selected crude oils from Sabah and Sarawak

A total of 35 crude oils from 15 fields from offshore Sabah and Sarawak have been analysed and characterised using liquid and gas chromatography, and gas chromatography-mass spectrometry. The normal alkane distribution shows that the oils are of three different types, namely, i) normal, non-waxy crude oils; ii) waxy oils (high proportion of C20+ n-alkanes); iii) biodegraded oils (less abundance ofn-alkanes relative to isoprenoids). Biological marker distributions (i.e. steranes and triterpanes) show that the oils were derived from terrigenous source rocks containing mixtures of different types of landplant derived organic matter, including resins. Features of these distributions include the presence of relatively high concentrations of 18n (H)-oleanane, a number of resin-derived compounds, a predominance of C29 steranes compared to the relatively low concentrations of C28 and C27 steranes, and the absence of CSD steranes in all the samples. Source rock matter for these oils were probably deposited under peat swamp environments, as indicated by the high pristanelphytane (>3.0) and pristanelnC17 (>1.0) ratios. Biological marker distributions indicate that the oils were generated from source rocks having maturities of 0.5% to at least 0.8% VRe (Vitrinite Reflectance Equivalent).

Hydrothermal petroleum generation in Red Sea sediments from the Kebrit and Shaban deeps

Petroleum impregnated sediments and massive sulfides have been found in two deeps of the northerns Red Sea. Biological marker distributions in extracts and polar fraction degradation products were analyzed in order to elucidate the source of the petroliferous material. Two organic phases could be distinguished according to their source and maturity. The amounts of n-alkanes show a marked decrease with depth, whereas the concentrations of various branched and cyclic hydrocarbons increase, resulting in a humpof unresolvable compounds in a depth as shallow as 300 cm. Changes in concentrations and distributions of hopanoids in the Kebrit Deep sediments indicate a rapid increase of maturity with depth. The deepest core section (300 cm) and the masive sulfide reveal comparable maturation indices typical for mature oils. By chemical degradation of the polar fractions a series of C 40-isoprenoids was obtained, which reveals a considerable contribution from methanogenic and thermophilic archapbacteria to the immature organic matter. The data suggest that petroliferous material ofthermogenic origin migrates through the younger sequences, superimposes the autochthonous organic substances in the sediments and furthermore, forms asphaltic impregnations in the massive sulfides.

Analysis, structure and geochemical significance of organically-bound sulphur in the geosphere: State of the art and future research

This paper reviews the developments of the 1980s in the characterisation of organically-bound sulphur in the geosphere and summarises the geochemical significance of the results obtained by these studies. The identification of more than 1500 novel OSC (organic sulphur compounds) with structures related to biochemical precursors in mostly immature sediments and crude oils has led to a better understanding of the process by which inorganic sulphur is incorporated into organic matter. The sulphur enrichment of organic matter probably takes place via “quenching” of functionalised lipids by sulphur at the early stages of sediment diagenesis or even in the water column. This results in the formation of OSC with specific structures which may be applied as palaeoenvironmental indicators. Hydrocarbon biological marker distributions may be heavily biased by diverting functionalised potential hydrocarbon precursors in OSC. Thermal evolution of sedimentary organic matter also affects the composition of OSC and when these changes are completely understood these compounds may be applied as maturity parameters as well. Recent developments in the characterisation of organically-bound sulphur present in macromolecular substances, i.e. kerogen, asphaltenes and high-molecular-weight fractions of crude oils and bitumens, show that the sulphur-containing moieties in these substances are formed in a similar way to the low-molecular-weight OSC. Sulphur incorporation into functionalised lipids in an intermolecular fashion should be considered as an important pathway for the formation of macromolecular substances. The abundance of organic sulphur in these substances also has a marked influence on their thermal evolution. Hiatuses in our present knowledge are numerous and stimulate future studies. Priorities are: the unravelling of the actual mechanisms of sulphur incorporation into organic matter and a better understanding of the diagenetic pathways of OSC and sulphur-containing macromolecular substances.

Use of biological marker distributions to study thermal history of the Permian Kupferschiefer of the Lower Rhine Basin

In the Central European Zechstein Basin, the Permian Kupferschiefer has been deposited under marine anoxic conditions. From a lagoon at the southwest border of the Zechstein Sea, today part of the Lower Rhine Basin, 30 core samples have been studied by means of organic geochemical methods. Within the area investigated, the depth of the Kupferschiefer horizon increases from about 350 m in the south to about 1000 m in the north. Furthermore, the Kupferschiefer has been thermally affected in the western part by the intrusive body of the so-called Krefeld High. This geological situation opens the possibility to investigate differences of short term and long term temperature effects on the biological marker distribution within a sediment layer of a largely uniform facies type. Depth related changes in the hopane, sterane and diasterene/diasterane distributions are compared to those changes induced by the Krefeld High. The composition of aromatic steroid hydrocarbons is used to discuss time-temperature effects. It is shown that depth related values of maturation parameters can only be interpreted by taking into account post-depositional tectonic events. Samples from tectonic horst structures show higher maturation values than one would expect from the present day depth.

Late cretaceous anoxic events in the Brazilian continental margin

A combined geochemical and micropalaeontological study of Cenomanian to Maastrichtian pelitic sediments from the Brazilian continental margin has been undertaken. The organic carbon contents, Rock-Eval pyrolysis results and biological marker distributions, together with the taxonomic selection and distribution patterns of microfossil assemblages indicate that intermittent anoxic events occurred in the Brazilian marginal basins during the Cenomanian-Santonian with deposition taking place in progressively deeper waters from neritic to bathyal. Such events are characterised by the following: 1. (i) a predominance among the benthonic foraminifera of low-diversity, small-sized specimens (mainly composed of gavelinellids, buliminids and nodosariids) indicating “dysaerobic” bottom conditions; 2. (ii) levels with virtually no benthonic foraminifera and a well-developed planktonic biota (foraminifera, radiolarians and diatoms) indicating “anaerobic” bottom conditions with oxygenated surface waters; 3. (iii) the occurrence of organic rich calcareous mudstone sediments; 4. (iv) features in the biological marker distributions such as high concentrations of 28,30-bisnorhopane and 25,28,30-trisnorhopane (up to 130 ppm), a predominance of phytane over pristane, and medium to high concentrations of nickel and vanadyl porphyrins (up to ca 5700 ppm). The widely recognized Cenomanian-Turonian and Santonian “oceanic anoxic events” (Schlanger and Jenkyns, 1976; Ryan and Cita, 1977 and Jenkyns, 1980) are therefore manifest in the Cassiporé, Ceará, Sergipe/Alagoas and Campos basins within the Brazilian continental margin, as is the presence of such events in the Coniacian. In contrast, the Campanian-Maastrichtian appears to be a time interval when deposition under oxygenated conditions produced sediments with low organic carbon contents and poor hydrocarbon source potential, containing highly diversified and abundant calcareous and agglutinated benthonic foraminifera.

Recognition and Source Correlation of Migrated Hydrocarbons in Upper Jurassic Hareelv Formation, Jameson Land, East Greenland

Organic geochemical analysis of an interbedded shale-sandstone sequence from the Upper Jurassic Hareelv Formation, Jameson Land, East Greenland, has revealed oil shows in the sandstones, consistent with petroleum generation and migration. A comparison of the molecular characteristics of extractable material from the sandstones with those of kerogen and bitumen from the shales indicates that the most likely origin of these shows is generation within the shales with expulsion and short-range migration into the sandstones. This conclusion is based on comparisons of biological marker distributions, stable carbon isotopic compositions of extractable material and kerogen, and pyrolysate compositions of kerogen and asphaltenes. Oil from a seep in the Savoia Halvo region south of Jameson Land can be correlated to the Jurassic sandstone oil shows based on similar isotopic compositions and asphaltene pyrolysate distributions. Impregnation of both sandstones and shales throughout the sequence by products generated at higher maturities is considered unlikely, but cannot be ruled out by the existing data. The molecular characteristics of the sandstone hydrocarbons exhibit a striking similarity to those of oils from the mid-Norway region. The similar geologic ages of the Hareelv Formation and the Kimmeridge Clay of northwestern Europe, which is the acknowledged source of the mid-Norway oils, and the geographic proximity of the two regions at the time of early North Atlantic rifting indicate that hydrocarbons from these present-day distant regions have been generated from very similar organic facies, deposited under similar environmental conditions. These results are significant in that in addition to stratigraphic correlation of depositional sequences on both margins of the early rifted North Atlantic, the hydrocarbons generated from source rocks contained in these sequences now can als be geochemically correlated. The results also suggest that Jurassic hydrocarbon source facies deposited throughout the early North Atlantic are geochemically similar, a trait imparted to their generation products.