Search

Remnants of some of the planet’s most ancient life forms, stromatolites in the late Mesoproterozoic sea of the Chattisgarh Basin, India, preserve a conspicuous sinuous pattern. They occur as successive biostromes, 10–30 cm thick, separated by 2–5-cm-thick marly layers and discrete bioherms up to several metres thick and 20 m across. Stromatolite columns in the Chandi Formation are 5–10 cm high, sinuous, inclined and straight, with both branched and non-branched types. These stromatolites are composed of calcite micrite and show well defined light and dark laminae with evidence of erosion between lamina sets. The column sinuosity probably originated as a response to changes in direction and strength of currents. Successive flat beds of stromatolite (biostromes), separated by marl/clay horizons, impart a rhythmic pattern to the succession. The Chandi sinuous stromatolite columns resemble those occurring in China, North America and Siberia, of a comparable age, suggesting that similar marine conditions of stromatolite formation might have been operating in the late Mesoproterozoic seas worldwide. However, the petrographic and sedimentological analyses of these stromatolites indicate their development throughin situproduction of carbonate with some trapping and binding of detrital sediment. As a result of the presence of terrigenous material within the stromatolites, whole-rock geochemical analyses for trace elements and rare earth elements cannot be used for interpretation of seawater chemistry and the redox conditions at the time.

Although it has been suggested that viruses may induce precipitation of carbonate, the exact mechanisms involved and the roles they might play in the nucleation of carbonates are still unknown. Experimental evidence is reported here demonstrating that bacteriophages are an important factor in calcium carbonate formation. Short-term experiments were designed to induce viral-mediated mineral precipitation at different fluid compositions. The precipitates obtained, analysed with fluorescence and electron microscopes and X-Ray diffraction, and evaluated by statistics, clearly show that bacteriophages strongly affect the process of carbonate precipitation. We demonstrate that as a result of the coalescence of the phages, the carbonate precipitates form large aggregates consisting of spheroids. The spheroids are constructed of angular nanoparticles resembling viral-like particles. In control experiments spheroids were also observed; however, they consist of irregular nanoparticles and additionally they do not form large aggregates. We also demonstrate that bacteriophages strongly influence the mineral composition of the precipitates, with vaterite being the dominant form, and they likely control vaterite stability.

Modern-day ocean circulation behaves as a complex forced convective system that is characterized by the decrease in water temperature but increase in water density with depth. The dissolved oxygen content – which initially decreases due to biological oxygen demand – also increases with depth. In contrast to the present-day scenario, we propose that during the Archaean and Proterozoic eons inverted profiles could have developed such that, with depth, ocean water temperature increased and density and dissolved oxygen decreased. These inverted temperature and density profiles resulted in palaeo-ocean circulation behaving as a free convective system. It is proposed that this free convection, which may have been stable, or chaotic and subject to secondary instabilities, hindered the deep oxygenation of the palaeo-ocean. It may not be coincidental that the great oxygenation event (GOE) and Huronian glaciations are contemporaneous, in a similar way that the Neoproterozoic oxygenation event (NOE) is known to have been associated with glaciations. The global-scale external forcing required to switch the natural convective system to its present-day configuration is suggested to have been associated with Neoproterozoic glaciations and the subsequent lowering of ocean water salinity that accompanied them. We propose that this inverted the ocean water density gradient, allowing the oxygenation of the oceans for the first time. It is beyond the scope of this work to model the complex natural convection system, but we hope that geophysicists and numerical modellers will quantitatively evaluate the hypothesis proposed here to validate or refute our proposition.

Framboidal pyrite has been a matter of interest of many studies due to its abundance in a wide range of environments, and as a marker of redox conditions. However, the clear origin of framboidal pyrite remains unresolved. The paper discusses the possible role of bacteriophages (bacterial viruses) in the precipitation of sulphide minerals (FeS and CuS) and their impact on the formation of framboid-like structures. Here, two bacteriophages (Enterobacteria phage P1 and Pseudomonas phage Φ6), which differ significantly in the shape and physicochemical properties, were used. Our observations suggest that viruses can attract ions from the solution and thus change the electrochemical properties of precipitated minerals. Moreover, we showed that bacteriophages P1 can lead to the formation of finer mineral particles of FeS and CuS, whereas the framboid-like structures were found only in experiments with precipitation of FeS. However, Pseudomonas phage Φ6 did not cause formation of similar structures probably due to the presence of lipid envelope. Hence, it is assumed that Enterobacteria phage P1 can promote the formation of the FeS-based framboid-like structures. The proposed four-step conceptualized mechanism of the framboidal-like structure synthesis via viruses is as follows: (i) attraction of ions by capsids, (ii) bacteriophages behave like nuclei for mineral crystallisation, (iii) destabilisation of the colloid (ζ-potential ~ 0), (iv) formation of fine agglomerates.

Corrigendum to: "Hydrous pyrolysis (HP) to simulate the maturation of organic matter (OM) and a variety of organic geochemical analyses and petrographic analyses of OM were performed to establish the origin and depositional environment in the Serpukhovian (Mississippian) and Pennsylvanian coals and carbonaceous shales from the Upper Silesian and Lublin coal basins. OM of coals and shales is dominated by vitrinite- with subordinate liptinite- and inertinite-group macerals, derived from C3 plants. The OM in both coals and shales is of humic origin, deposited in terrestrial, paralic and terrestrial, deltaic and lacustrine environments. The OM is rich in resins related to the presence of waxes derived from the coat of vascular plants. Shales were deposited in a more brackish-lacustrine environment than coals with algae and microbially reworked OM. Shales occurring above coal seams were deposited in more dynamic conditions than shales below seams. Coal sedimentation occurred in a stagnant setting reflected in the presence of paleosols and diverse plant groups. After heating at HP 330 °C and 360 °C, various new vitrinite forms appear, and semicoke, in the OM. The distributions of some biomarkers and polycyclic aromatic hydrocarbons are characteristic of specific macerals, and their ratios are controlled by OM type and thermal maturity related to the conditions of the HP experiments. This behaviour can be related to OM of type III and chemical reactions at two maturation stages. No significant geochemical or genetic differences in the OM of coals or shales from either basin are evident".

Framboidal pyrite has been a matter of interest of many studies due to its abundance in a wide range of environments and being a marker of redox conditions. However, the clear origin of framboidal pyrite remains unresolved. Our studies are preliminary laboratory investigations on the influence of the shape and physicochemical properties of bacteriophages on the synthesis of framboid-like structures. This paper discusses the possible role of bacteriophages (bacterial viruses) in the precipitation of sulfide minerals (FeS and CuS) and their impact on the formation of framboid-like structures. Here, two bacteriophages (Escherichia phage P1 and Pseudomonas phage Φ6), which differ significantly in shape and physicochemical properties, were used. Our observations suggest that viruses may bind ions from the solution. Moreover, we showed that bacteriophages P1 can lead to the formation of finer mineral particles of FeS and CuS, whereas the framboid-like structures were found only in experiments with precipitation of FeS. However, the lipid-enveloped Pseudomonas phage Φ6 did not cause the formation of similar structures. It is assumed that Escherichia phage P1 can promote the formation of FeS-based framboid-like or spherical structures. The proposed four-step conceptualized mechanism facilitating the framboid-like structure synthesis via viruses is as follows: (i) binding of ions by capsids, (ii) bacteriophages behaving like a crystallization surface, (iii) destabilization of the colloid (ζ potential ± 0), and (iv) formation of fine agglomerates and subsequent formation of small crystallites. Further studies are required to find all factors that may be affected by bacteriophages during sulfide precipitation. In addition, it is important to consider viruses present in sedimentation environments, despite possible difficulties in laboratory culturing. The consideration of such viruses may make laboratory testing more valid in terms of sedimentation environments.

The Morag Field is a small oilfield underlying the Maureen Field in UK Block 16/29a. Black oil is trapped within Upper Permian, Morag Member, vuggy and fractured dolomite rafts between 9300 and 10 600 ft true vertical depth subsea. The dolomite reservoir occurs at the top of a Zechstein salt dome. Morag was discovered in 1979 by well 16/29a-A1, the first platform well drilled for the overlying Maureen Field with its Paleocene sandstone reservoir. Morag was produced via a single well (16/29a-A1) between 1991 and 1994. Three more platform wells were drilled into the Permian interval prior to Maureen Field start up but only one penetrated oil-bearing dolomite (16/29a-A2). An additional well (16/29a–A23Z) was drilled into the Morag Field in 1993. The well encountered Morag Member at virgin pressure and tested oil at high flow rate but then the well failed due to mechanical problems. Oil in place was calculated to be about 24 MMbbl in four independent fault blocks. Ultimately 16/29a-A1 delivered 2.6 MMbbl from a fault block calculated to have held 6.7 MMbbl stock tank oil initially in place.

Methanotrophic bacteria (MB) are an important group of microorganisms, involved in the greenhouse gas (GHG) cycles. They are responsible for the utilization of methane, one of the main GHGs, which is released in large amounts (via biogenic and abiogenic processes) during coal formation. This study aimed to determine the main factors affecting the distribution of the MB in two lignite-bearing series of the Turow and Belchatow coal basins. Distribution of MB in the lignite profiles was studied using methanotroph-specific lipid biomarkers such as amino-bacteriohopanepolyols (NH-BHPs) and C-3 methylated BHPs. BHP results were combined with physical and chemical properties of the studied sediments. In general, lignites were richer in BHPs than the mineral samples, which points to the important role of the intrinsic methane cycling. NH-BHP speciation confirmed that the methanotrophic community of the studied sediments was a combination of both type I and, especially, type II methanotrophs. Based on geological data, it was suggested that elevated temperature during diagenesis intensifies decomposition of methanotroph-specific biomarkers (aminopentol and 3-Me BHT). It was found that the tested BHPs can derive from both fossil and living MB. The presence of metabolically active methanotrophs should therefore be accounted for during studies aimed at using lignite deposits as a source of methane.

Due to changes in the energy market, it is projected that lignite excavation will be reduced in the near future. Cessation of exploitation is associated with restitution of natural water conditions and flooding of the resources left in the mines. Flooded lignite mines are a potential source of greenhouse gases (GHG) (CH4, CO2 and N2O), which should be monitored due to growing environmental concerns. Here, we aim to recognize GHG release from the lignites collected from the main deposits of Poland, Slovenia and Serbia. GHG production was studied along with a range of physical and chemical parameters that are crucial for microbial growth and activity. The microcosm experiments showed that the main gas emitted from the lignites was carbon dioxide. Daily CO2 production was highly variable. The highest values were recorded for detroxylitic lignite collected from the Konin deposit (402.05 nmol CO2 g-1 day-1) while the lowest were for the Kolubara xylitic lignite (19.64 nmol CO2 g-1 day-1). Methane production was much lower and ranged from nearly zero to 66.75 nmol g dry mass-1 d-1. Nitrous oxide production was not detected. It was found that CO2 production, being a general measure of microbial activity, was positively affected by NO3- concentration and redox potential. With respect to methane formation, the lower atmospheric oxygen exposure of the sample from the Velenje underground mine compared to the samples from the opencast mines has been identified as a possible cause of the high methane production. The overall global warming potential (GWP) of the gases released by xylitic lignite was lowest among the samples. Preferential extraction of the detritic lignites is suggested as a means to reduce GHG emissions from the abandoned lignite mines.

The distribution of archaeal isoprenoidal glycerol dialkyl glycerol tetraethers (isoGDGTs) has been increasingly used to characterize the archaeal community and to reconstruct palaeoenvironmental change. However, except for temperature, other environmental factors controlling the distribution of isoGDGTs remain to be explored. Environmental factors generally vary with depth along peat and soil profiles (PP and SP), which can provide unique opportunities to determine the impact of factors other than temperature on the distribution of archaeal ether lipids (AEL) in these settings. Here, we investigated the changes in AEL in two PPs and two red (ferralsol) SPs from southern China and determined the relationship of their distributions with peat and soil depth. The isoGDGT distribution in the two PPs and two SPs all show a significant dependence on depth. Crenarchaeol, which is likely to be produced by Thaumarchaeota, dominates in the upper parts of PPs and SPs, whereas GDGT-0 or isoGDGTs containing cyclopentyl moieties are the most abundant compounds in the deeper parts of these profiles. The change in the AEL distribution can be best characterized by %Cren (the proportion of crenarchaeol in total isoGDGTs) and MI (Methane Index), which are closely related to the water content in PPs and SPs. This suggests that %Cren and MI have potential for tracing the water content and, in turn, the redox conditions in paleosols and peats. The most remarkable differences in the AEL between PPs and SPs are the increased abundance of AEL, e.g., GDGT-5 (isoGDGTs with five cyclopentyl moieties), butanetriol dialkyl glycerol tetraethers (BDGTs), H-shaped isoGDGTs, methylated H-shaped isoGDGTs (Me-H-GDGTs) and the decreased abundance of hydroxylated isoGDGTs (OH-GDGTs) with depth in the two PPs, whereas these lipids are absent from the two SPs. This implies that the former group of lipids is likely derived from anaerobic archaea whereas OH-GDGTs and crenarchaeol are primarily of Thaumarchaeotal origin. The response of AEL to in situ environmental variables in the PPs and SPs reveals that the living archaea reside in the deep SPs and PPs and thus caution should be taken when applying these lipids to the high-resolution palaeoenvironmental reconstructions.

Microbial coal gasification is of great interest due to the necessity to develop more environmentally friendly methods of energy production. The two main lignite deposits in Poland (Belchatow and Turow) have been studied for their natural methanogenic potential. The biological origin of gases occurring in the investigated strata was confirmed by carbon stable isotope fractionation. Methanogenesis was examined via long-term anaerobic microcosm incubations which were performed using coal extracted from upper- and lower- most parts of the deposits at 10 to 40 °C. Present-day methane formation was distinguished from physical desorption by application of 2-bromoethane sulphonate (BES), an inhibitor of terminal methane formation steps. Furthermore, glycerol dialkyl glycerol tetraethers (GDGTs), were used to reconstruct the palaeoenvironmental conditions and explain how the lignite environment affects the methanogenic consortia. The data obtained reveal that microbial degradation of lignite occurs in the uppermost layers of the coal seam at the Belchatow lignite mine. Methane release was up to 0.064 ng CH4 g−1 day−1 at 30 °C. Biomarker analysis shows high abundance of GDGT-0 confirming the presence of methanogenic Archaea and implies that pH was an important factor regulating the development and activity of organic matter-degrading microbiota under neutral conditions as the most favourable for the methanogens. Inactivation of methanogenic pathways by BES led to stimulation of bacterial respiration, which suggests the presence of an active bacterial community, putatively involved in the decomposition of lignin. The biomarker analysis, depicting metabolic capabilities of the microbiota (especially GDGT-0 and GDGT-0/crenarchaeol ratio) and recognition of palaeoenvironmental conditions, is a useful tool to determine the methanogenic potential of coals.

Hydrous pyrolysis (HP) to simulate the maturation of organic matter (OM) and a variety of organic geochemical analyses and petrographic analyses of OM were performed to establish the origin and depositional environment in the Serpukhovian (Mississippian) and Pennsylvanian coals and carbonaceous shales from the Upper Silesian and Lublin coal basins. OM of coals and shales is dominated by vitrinite- with subordinate liptinite- and inertinite-group macerals, derived from C3 plants. The OM in both coals and shales is of humic origin, deposited in terrestrial, paralic and terrestrial, deltaic and lacustrine environments. The OM is rich in resins related to the presence of waxes derived from the coat of vascular plants. Shales were deposited in a more brackish-lacustrine environment than coals with algae and microbially reworked OM. Shales occurring above coal seams were deposited in more dynamic conditions than shales below seams. Coal sedimentation occurred in a stagnant setting reflected in the presence of paleosols and diverse plant groups. After heating at HP 330 °C and 360 °C, various new vitrinite forms appear, and semicoke, in the OM. The distributions of some biomarkers and polycyclic aromatic hydrocarbons are characteristic of specific macerals, and their ratios are controlled by OM type and thermal maturity related to the conditions of the HP experiments. This behaviour can be related to OM of type III and chemical reactions at two maturation stages. No significant geochemical or genetic differences in the OM of coals or shales from either basin are evident.

The Palaeoproterozoic Vempalle Formation of the Cuddapah Basin, India, significantly adds to our understanding of the evolution of Precambrian marine carbonate systems and the redox state of the Earth's early oceans. A facies-microfacies-diagenetic-geochemical examination of samples from a ∼1000-m long exposure in a freshly-cut canal section shows that 10–15% of precursor limestone is still preserved in the Vempalle Formation in the form of remnant patches of calcimicrite and ooids with calcite spar cement. The ooids, preserving primary radial and concentric fabrics and radial fractures, are considered to have been originally precipitated as calcite, which may have been low-Mg. In places the preserved calcite spar, that is partially replaced by fabric-destructive dolomite, shows Type I calcite twin lamellae. Petrographic observations demonstrate that Vempalle Formation dolomite formed through very early precipitation, which in stromatolites preserved microbial filaments, as well as through fabric-destructive dolomitization during shallow to moderate burial. Vempalle Formation dolomite is characterized by micritic dolomite crystals which suggest rapid early dolomitization of lime mud and micritic calcite from a supersaturated Mg-Ca-rich solution, probably near-surface or during shallow burial. Depletion of Na and Sr contents of Vempalle Formation dolomite along with negative δ 18 O values indicate dolomite recrystallisation during burial and further replacement. Dolomite δ 13 C values of −0.5 to 2‰ are likely inherited original marine values. Geochemical proxies (trace elements and rare earths) imply that Cuddapah Basin seawater and dolomitizing fluids were anoxic and ferruginous but not euxinic. Geochemical analyses also indicate that the burial diagenetic fluids evolved from Eu-enriched seawater that probably resulted from continental rifting around 1.9–2.0 Ga. This probable ocean chemistry is in contrast with the anoxic, ferruginous and extremely high Mg/Ca “dolomite oceans” that prevailed during Proterozoic time. The Vempalle dolomite shows more similarities with dolomitised Phanerozoic platform carbonates than typical Precambrian dolomite with its well-preserved textures and burial dolospar cements.

Understanding early organic matter alteration and preservation in marine carbonate-evaporite systems could improve understanding of carbon cycling and hydrocarbon source rock prediction in such environments. It is possible that organic-rich microbial mats are important contributors to preserved hydrocarbons, and to explore this we examined changes in lipid composition in such a mat from a mesohaline intertidal lagoon, eastern Qatar. The mat reaches > 5 cm thickness over a carbonate mud substrate, rich in seagrass, gastropods and other small bioclasts. Clear lamination, with distinct downward colour changes from green to pink to brown, reflects different microbial mat communities. The layers contain spheroids of probable dolomite, the precipitation of which was plausibly bacterially-mediated. Lipids [n-alkanes, fatty acids (FAs), hopanoids, isoprenoid hydrocarbons, dialkyl glycerol diethers (DAGEs), and isoprenoid (0 to 4) and branched (Ia to IIIa) GDGTs] reflect the diverse mat-building phototrophic, heterotrophic and chemoorganotrophic microorganisms, as well as some likely allochthonous material (i.e. steroids, n-alkanols, high molecular weight n-alkanes). The lipids clearly document the change in microbial community, with phytene being the predominant hydrocarbon in the phototrophic surface layer. Oxygen and pH drop significantly 0.2 cm below the mat surface, coincident with the predominance of Deltaproteobacteria and increased concentrations of archaeal and bacterial glycerol dialkyl glycerol tetraether lipids andC15/C16 and C16/C17 dialkyl glycerol ether lipids in the deeper layers. Archaeol, likely of methanogen origin, is most abundant in the deepest layer. Allochthonous inputs occur throughout the mat, including abundant steroids, especially dinosterol and dinostanol, that are possibly related to periodic algal (dinoflagellate) blooms in the Arabian Gulf. Both n-alkanes and n-alkanols appear to be derived from seagrass. Organic matter contents decrease in the deepest mat; this suggests an overall low preservation potential of OM in intertidal mesohaline-hypersaline mats of the Arabian Gulf, which in turn suggests that these are not the major source of hydrocarbons in microbially-dominated carbonate-evaporite systems.

The study evaluates pore systems in samples of tight Upper Permian Zechstein 2 Carbonate (Z2C) facies from widely dispersed locations in the eastern and western parts of the Southern Permian Basin, NW Europe. Samples of Z2C drill cores comprising platform to shallow-basin deposits were examined by petrographic techniques, porosity measurement and SEM analysis, in order to acquire a better understanding of porosity development and pore microstructure. Four carbonate lithofacies were identified by core-scale and thin-section analyses: subtidal / intertidal planar stromatolites and thrombolites; slope facies (laminated dolo- and lime-mudstones and grain-dominated turbidites); toe-of-slope / lower slope facies (laminated lime mudstones with turbidite beds); and shallow-basin (embayment) facies (laminated lime mudstones and hemipelagic deposits). Porosity ranges from 0.08% to 9.6% and is lowest in the subtidal / intertidal planar and columnar stromatolites. The highest porosities, in the slope and shallow-basin (embayment) lithofacies, probably resulted from catagenetic processes and microbial activity. High porosity in subtidal thrombolites is related to the original pore network. SEM analyses showed that pores are present within organic matter, pyrite framboids and microfossils, and between crystals. Subtidal / intertidal planar and columnar stromatolites and thrombolites have a high proportion of nanopores, probably resulting from microbial activity. Although porosity development is a combined function of the presence of organic matter and mineral components, together with sediment fabric and fractures, it is mostly a result of the early diagenetic transformation of mineral phases, microbial activity, and evaporite and carbonate dissolution.

We report on the discovery of oil from the Boulby Mine and its likely productive source rock from Yorkshire in NE England, located to the west (

In the Zielin oilfield in the Polish part of the Southern Permian Basin, oil and gas are produced from an Upper Permian Main Dolomite (Ca2) isolated platform. The paleohigh developed on a volcanic cone formed in Early Rotliegend time. Based on microfacies analysis of Ca2 reservoir rocks from four wells (Zielin-1, -2, -3 and -3KBis), four microfacies types are distinguished: peloidal dolomitized wackestone, intraclastic dolomitized rudstone and floatstone, biogenic boundstone, and intraclastic-bioclastic dolomitized packstone. In view of the lack of source rocks on the Zielin paleohigh revealed by Rock–Eval analyses, this isolated carbonate platform is regarded as a reservoir for migrating hydrocarbons. Biomarker analyses of two crude oils and nine carbonate rocks from the Zielin isolated carbonate platform and five crude oils from surrounding wells of the nearest Gorzow, Cychry, and Namyślin platforms indicate an origin for the oils from oil–prone type II kerogen, sourced from organic matter deposited under anoxic/suboxic conditions in a carbonate environment. Compared to organic matter extracted from the rock samples, oils from the Zielin-2 and 3KBis wells are characterized by higher values of the pristane/phytane (Pr/Ph) and dibenzothiophene/phenanthrene (DBT/P) ratios, lower relative concentrations of polyalkylaromatics, as well as a higher maturity evaluated from the methylphenanthrene (MPI-1) and methyldibenzothiophene (MDR) indices. The molecular composition of sesquiterpanes, n-alkylbenzenes, and polyalkylnaphthalenes revealed a diverse specificity within the oils analyzed and allowed their separation into two groups. Oils Rozansko-4, Zielin-2, Zielin-3KBis, and Namyślin-1 represent group I, whereas Barnowko-3, Mostno-2 and Cychry-2 group II. From the gradient direction in the n-decane/naphthalene ratio and maturity for respective crude oils belonging to group I, it is concluded that the oils accumulated in the Zielin atoll migrated from NW to SE following subsidence and tilting of the platform in this part of the Main Dolomite basin.

In a modern peritidal microbial mat from Qatar, both biomediated carbonates and Mg‐rich clay minerals (palygorskite) were identified. The mat, ca 5 cm thick, shows a clear lamination reflecting different microbial communities. The initial precipitates within the top millimetres of the mat are composed of Ca–Mg–Si–Al–S amorphous nanoparticles (few tens of nanometres) that replace the ultrastructure of extracellular polymeric substances. The extracellular polymeric substances are enriched in the same cations and act as a substrate for mineral nucleation. Successively, crystallites of palygorskite fibres associated with carbonate nanocrystals develop, commonly surrounding bacterial bodies. Micron‐sized crystals of low‐Mg calcite are the most common precipitates, together with subordinate aragonite, very high‐Mg calcite/dolomite and ankerite. Pyrite nanocrystals and framboids are present in the deeper layers of the mat. Calcite crystallites form conical structures, circular to triangular/hexagonal in cross‐section, evolving to crystals with rhombohedral terminations; some crystallite bundles develop into dumb‐bell and stellate forms. Spheroidal organo‐mineral structures are also common within the mat. Nanospheres, a few tens of nanometres in diameter, occur attached to coccoid bacteria and within their cells; these are interpreted as permineralized viruses and could be significant as nuclei for crystallite‐crystal precipitation. Microspheres, 1 to 10 μm in diameter, result from intracellular permineralization within bacteria or the mineralization of the bacteria themselves. Carbonates and clay minerals are commonly aggregated to form peloids, tens of microns in size, surrounded by residual organic matter. Magnesium silicate and carbonate precipitation are likely to have been driven by pH – saturation index – redox changes within the mat, related to microenvironmental chemical changes induced by the microbes – extracellular polymeric substances – viruses and their degradation.

Geochemical analyses were used to classify 39 Zechstein (Late Permian, Lopingian) Main Dolomite (Ca2) crude oil samples from fields in the eastern and southern sector of the Southern Permian Basin (SPB) of Europe and to provide new insights into the origin of the oil. Geochemical data indicate that Ca2 oils were generated in the early-to-late oil window and are mostly non-waxy oils. Various biomarker and stable carbon isotopic ratios were used to identify source and depositional settings for source rocks of Ca2 oils arranged within 10 distinct oil groups. Specifically, the geochemical analyses and oil-oil correlations revealed a set of characteristic biomarkers including an even-over-odd predominance (EOP) for the C20-30 n-alkanes, C40 carotenoid occurrence (isorenieratane, chlorobactane, β-isorenieratane), bisnorhopane/hopane (BNH/H) ratios >0.1, high abundances of C35 homohopanes and elevated concentrations of C32 and C34 homohopanes, a predominance of C29 homologues among 4-desmethyl steranes in the majority of oil samples, and a high abundance of diasteranes. Stable carbon isotopes and biomarkers provided ample evidence that Ca2 oils were generated from predominantly algal-rich marly carbonate/evaporite source rocks located in the lower slope/shallow-basin and lagoonal facies of the Ca2 basin, all deposited under suboxic-anoxic (euxinic) conditions. In the case of all higher maturity oils, the source rocks could not be reliably identified but high (>2) C24Tet/C23 values suggest a carbonate-evaporite depositional setting.

Evidence for photic zone euxinia (PZE) in ancient oceans is widespread and commonly associated with global climate change and biotic events. However, evidence of PZE in marginal settings is commonly extrapolated to infer basin-scale characteristics. To explore the relationship between euxinia in marginal settings and the wider basin in one Palaeozoic context, we have conducted a detailed spatial and temporal examination the palaeowater-column redox state from the Polish sector of the Southern Permian Basin (SPB) during deposition of the Zechstein (Lopingian) second carbonate (Main Dolomite) cycle. Sediments from toe-of-slope, slope and hypersaline lagoonal settings of the northeastern margin of the SPB contain abundant chlorobactane, isorenieratane and their likely degradation products (C 15 to C 31 2,3,6-aryl isoprenoids). These indicate that part of the photic zone was euxinic during significant intervals of the Main Dolomite deposition. Further evidence for strongly anoxic conditions includes the occurrence of C 28 -bisnorhopane, high concentrations of pentakishomohopanes (i.e. high homohopane indices), and the occurrence of framboidal and native sulphur crystals in slope facies. However, a lack of these signatures in basinal settings indicates that strongly reducing conditions were restricted to the slope, and toe-of-slope locations. Even in these settings, however, highly variable homohopane indices and concentrations of isorenieratene and chlorobactene derivatives, as well as the presence of benthic fauna and bioturbation, indicate that anoxia fluctuated throughout deposition of the Main Dolomite, likely on a variety of timescales. Sterane distributions are also variable, suggesting a dynamic ecosystem, likely exhibiting a strong response to environmental forcing. Overall, it appears that high but episodic primary bioproductivity of organic matter was concentrated on the northeastern slope and restricted lagoons leading to the formation of source rocks for petroleum; however, the temporal and geographical restriction of anoxia appears to have prevented the accumulation of large or more widespread quantities of organic matter, and in fact TOC contents exhibit poor correlation with ecological and anoxia indicators. This model indicates that strong evidence for PZE in shelf and slope facies need not be associated with widespread, basin-scale anoxia, with implications for organic matter burial, carbon cycling and biotic crises.

The shale-gas potential of mid-Carboniferous mudrocks in the Bowland-Hodder unit in the Cleveland Basin (Yorkshire, northern England) was investigated through the analysis of a cored section from the uppermost part of the unit in the Malton-4 well using a multidisciplinary approach. Black shales are interbedded with bioturbated and bedded sandstones, representing basinal-offshore to prodelta – delta-front lithofacies. The total organic carbon (TOC) content of the shales ranges from 0.37 to 2.45 wt %. Rock-Eval pyrolysis data indicate that the organic matter is mainly composed of Type III kerogen with an admixture of Type II kerogen. Tmax (436–454°C), 20S/(20S+20R) C29 sterane ratios, and vitrinite reflectance values indicate that organic matter is in the mid- to late- mature (oil) stage with respect to hydrocarbon generation. Sedimentological and geochemical redox proxies suggest that the black shales were deposited in periodically oxic-dysoxic and anoxic bottom waters with episodic oxic conditions, explaining the relatively low TOC values. The Rock-Eval parameters indicate that the analysed mudrocks have a limited shale-gas potential. However, burial and thermal history modelling, and VRr data from other wells in the region, indicate that where they are more deeply-buried, the Bowland-Hodder shales will be within the gas window with VRr > 1.1 % at depths in excess of 2000 m. Therefore although no direct evidence for a high shale-gas potential in the Cleveland Basin has been found, this cannot be precluded at greater depths especially if deeper horizons are more organic rich.

Zechstein 2 (Z2) carbonate microbialites flourished under arid paleoclimatic conditions in the Late Permian. Microbial carbonates from the Roker Formation outcrop in northeast England, with its subsurface equivalent being the Main Dolomite from northwest–central Poland. The Z2 carbonate deposits developed in supratidal through deep subtidal zones and consist of various stromatolites and thrombolites. Planar stromatolites and thrombolites characterize intertidal and supratidal facies, and biohermal stromatolites with oolitic grainstone and crinkled stromatolites typify shallow subtidal facies. The Z2 subtidal and/or intertidal microbialites with oolites form complexes more than 10 m (33 ft) thick and are important reservoir facies for hydrocarbons. Subtidal (slope) and intertidal (lagoonal) microbial mudstone and wackestone have poor reservoir properties but contain total organic carbon as much as 2 wt. % and are considered as potential source rocks. The thermal maturity assessed from C27 17-trisnorhopane (Tm) and C27 18-trisnorhopane (Ts) as the Ts/(Ts + Tm) ratio, C30 moretane/hopane ratio, sterane ratio expressed as 20S/(20S + 20R), and /( + ) ratio shows to indicates a mature character of organic matter with respect to oil generation.

The idea of this volume arose from our proposal to the palaeoclimatic session held at the European Geosciences Union General Assembly 2011 Conference in Vienna (Austria). Although the original scope was broader, the included contributions focus on palaeoenvironmental changes during the late Palaeozoic. Late Palaeozoic history is especially important in that it records an increase of tectonics/diastrophism, frequent sea-level fluctuations and climatic changes, all finally leading to the most geocratic time of Earth’s history with the formation of the supercontinent Pangaea. This volume includes a number of articles that discuss the fossil record around the Late Palaeozoic Ice Age, and its decline during the Carboniferous with its unusual plant proliferation soon after, when the hottest and driest period in Earth’s history (in the Permian) caused the development of huge ‘sand seas’ on the land. Finally, a biotic event, the largest mass extinction in Earth History at the Permian–Triassic transition, ends the Palaeozoic world. This volume addresses two key issues – the palaeoclimate and depositional cycles – both of which have a strong impact on the record of palaeoenvironmental changes and the understanding of environmental perturbations. The vigorous current debate on the future climate of the globe inevitably increases our interest in past climates. From a geological perspective, climatic perturbations occurred many times before humans were on the planet. Climate varies on several timescales, depends on many high-order factors including tectonic uplift and the orbital wandering of the Earth, and as a result it changes through time. Consequently, palaeoclimatic reconstructions are growing in their importance as they enable us to use the past as a key to the future. The Earth’s system experiences various cycles of very different origin, scale, frequency, amplitude, phase and basic level. From a geological perspective, the cyclicity appears unidirectional, like Brownian motion. However, in the past, the complex interaction of these cycles has led to catastrophic changes in Earth’s systems, such as those during the late Palaeozoic, when palaeoclimatic and geotectonic cycles coincided. These cycles are also influencing our lives, and will do so in our future, so their impact needs to be understood. The geological archives record both the climatic and cyclic phenomena on local to regional scales, including in the late Palaeozoic, as documented in this volume. Understanding these records will improve our predictions about climate phenomena in the future. They also show that the present climatic perturbations are insignificant from a geological point of view. Changes in the late Palaeozoic Earth system are illustrated in this volume by case studies of fossil records from North and South America, East and South Asia, South Africa and Australia, and as regional reviews (section one). The methods include palaeoenvironmental analysis, including palaeobiological, sedimentological, stratigraphic (sequence stratigraphy), palaeomagnetic and geochemical methods. They describe various environmental settings from palaeodeserts, through marine-associated giant salt pans, to shallow to deep marine records. The articles report new data from less known study areas, provide up-to-date data ordering, and expand our knowledge of the evolution of marine and terrestrial environments, climatic changes and biotic events in late Palaeozoic time. This special publication is divided into five chapters, the first comprising articles focused on the broad descriptive character of Late Carboniferous to Early Triassic palaeoclimatic changes and stratigraphy (with the latest part of this period in Europe, i.e. Zechstein). Subsequent articles include more detailed studies of the geological periods grouped into the latest Devonian to Early Carboniferous (section two), Late Carboniferous to Early Permian (section three), Middle to Late Permian (section four), and finally the Permian–Triassic transition (section five). A brief synopsis of individual papers is given below. Wopfner (2012) reviews Westphalian–Early Triassic palaeoclimatic conditions between Samfrau (comprising the southern margins of South America and South Africa, extending via Antarctica

Biomarker, palaeontological and isotopic evidence suggests that the Late Permian carbonate seas, i.e. the Northern (NPB) and Southern (SPB) Permian basins of northern Pangea, were characterized by significant spatial and temporal variations in the palaeowater-column redox state. This is particularly the case with regard to the deposition of the Lopingian Zechstein cycle 2 carbonate rocks. A shelf to basin reconstruction of environmental conditions was achieved by analysing nearly 400 core samples from 49 wells. This allowed an evaluation of the spatial variations in facies and broad oceanographic conditions at the basin scale. Specifically, in the lower slope and shallow-basin facies of the northern margin of the SPB (present-day northern Poland and eastern Germany), highly variable concentrations of the green sulphur bacterial biomarkers chlorobactane and isorenieratane (and their likely degradation products, C15 to C31 2,3,6-aryl isoprenoids, indicative of photic zone euxinia) and homohopane indices (indicative of anoxia), combined with the presence of a benthic fauna and bioturbation, indicate a variable but occasionally anoxic/euxinic water column. Locally in lagoonal facies in the northern and southern margin of the SPB, euxinic conditions also developed but these were likely associated with localised conditions or benthic production in association with microbialites. The presence of gammacerane in the eastern SPB (south-eastern Germany and eastern Poland) suggests elevated salinities there, compatible with the restricted configuration of the basin. However, a lack of these signatures in basinal settings of the eastern SPB indicates that strongly reducing conditions were restricted to the lower slope and shallow-basin locations and restricted lagoons, and were not developed in the basin centre. Moreover, this anoxia/euxinia in marginal settings is restricted to the north-eastern part of the SPB. The south-eastern part of the SPB (SE Poland), in contrast, is devoid of evidence for PZE. The southern margin of the SPB is also characterized by generally oxic-suboxic conditions, with local anoxia limited to more restricted embayments, and elevated salinities limited to restricted oxic-anoxic lagoons. In the western SPB (NE England and adjacent offshore) and the NPB (Outer Moray Firth, offshore Scotland) the water columns were oxic-suboxic. Overall, it appears that high but episodic primary bioproductivity of organic matter was concentrated on (or even limited to) the lower slopes of the SPB's north-eastern margin and the restricted lagoons and shallow basin of its southern margin, leading to the formation of source rocks for petroleum in these areas. In addition, the temporal and geographical restriction of anoxia appears to have prevented the accumulation of large and more widespread quantities of organic matter; in fact TOC contents exhibit a poor correlation with ecological and anoxia indicators. Crucially, this work confirms that the strong evidence for PZE observed in shelf and lower slope/shallow-basin facies of the north-eastern SPB need not be associated with widespread, basin-scale anoxia; this conclusion has implications for organic matter burial, carbon cycling and biotic crises during other times in Earth history.

The Raipur Group of the Chattisgarh Basin preserves two major Late Mesoproterozoic carbonate platforms. The lower platform is about 490-m thick, separated from the upper platform (~ 670 m thick) by a 500-m thick calcareous shale. Carbonate strata cover almost 40% of the Chattisgarh Basin outcrop and represent two major platform types: a) a non-stromatolitic ramp (the Charmuria/Sarangarh Limestone) and b) a platform developed chiefly in the intertidal to shallow subtidal environment with prolific growth of stromatolites (the Chandi/Saradih Limestone). The first platform consists primarily of the black Timarlaga limestone that is locally replaced by early diagenetic dolomite. This carbonate platform experienced strong storm waves and was subsequently drowned by a major transgression, during which extensive black limestone–marl rhythmite was deposited, followed by deposition of the Gunderdehi Shale. The carbonate factory was later re-established with development of an extensive stromatolite-dominated Charmuria/Sarangarh platform that ranged from restricted embayment to open-marine conditions. Sea-level change played a major role in controlling the broad facies pattern and platform evolution. The δ13C signatures of the Chattisgarh limestones, falling within a relatively narrow range (0 to + 4‰) are typical for Upper Mesoproterozoic carbonate rocks. δ18O values, however, have a greater range (− 5.7 to − 13.3‰) indicating significant diagenetic alteration of some samples. Likely dysoxic or anoxic conditions prevailed during deposition of the black Timarlaga limestone and well-oxygenated conditions during deposition of the Gunderdehi Shale and Saradih/Chandi stromatolite. The lack of 17β,21α (moretanes) and high Tmax values suggest mature organic matter in the non-stromatolitic ramp. A paucity of diagnostic eukaryotic steroids indicates that algae were rare in the Chattisgarh Basin. A high content of hopanes supports a generally bacterially-dominated Proterozoic ocean in which various stromatolites flourished.

Various microbialite lithofacies were common in the shallow-water environments which flourished under highly saline and arid climate conditions in the Polish part of the Zechstein (Upper Permian) Main Dolomite (Ca2) carbonates. Data came from detailed analysis of 78 cores from wells located at the southern and northern margins of the Main Dolomite basin in west Poland. Microbialite lithofacies are represented by columnar, planar and domal stromatolites, clotted thrombolites and biolaminites developed in high-to-low energy environments within the upper slope, lower parts of oolitic barrier/shoal, restricted lagoon, and tidal flat and tidal channel zones. In barrier environments ooids were predominant whereas in lagoonal settings microbial oncoids and peloids were common. In basinal settings laminated dolomudstones formed which are regarded as hemipelagic and are partly pelagic microbial in origin. Microbial communities coexisted with algae and developed mainly within shallow marine environments. Microbialites are built of cyanobacterial filaments and organo-mineral coccoidal forms possibly of bacterial origin. Organic geochemistry data confirm that organic matter was transformed by cyanobacteria and bacteria which may have played a main role in hydrocarbon generation. This is confirmed by C29 to C35 hopanes, Pr/Ph ratio below 1.0, and the presence of gammacerane as typical for Ca2 profiles. The role and occurrence of algae, as confirmed by C29-steranes, in hydrocarbon generation was possibly minor. Thus it is concluded that the Main Dolomite microbialites could be the likely source rocks for hydrocarbons, with calculated original TOC values from 0.8 to ca 2.0 wt. %. These units also form the reservoir rocks, with porosities reaching 20%.

Here we discuss the duration and position of Upper Rotliegend and Zechstein stratigraphic units in relation to the absolute time scale, and reinterpret a carbon isotope (δ 13 C) global event recorded from Late Permian (Lopingian/Guadalupian) marine deposits. Based on δ 13 C isotope correlation (chemostratigraphy) and of climatic evidence related to the end-Guadalupian global marine and terrestrial crisis, the Guadalupian/Lopingian boundary is proposed as the boundary between both the European Upper Rotliegend (URII)/Zechstein sediments and the parallel south-west USA Ochoan/Bell Canyon Formation units. The Zechstein deposition was strongly influenced by climatic oscillations, and the marine ingressions recorded in the North German Basin and North American Delaware Basin are presumed to have resulted from the same eustatic sea-level changes in western and northern coasts of the Northern Pangaea Supercontinent. Existing constraints on the age of the Upper Rotliegend II (UR II) deposits are imposed by the uncertainty of the chronostratigraphic boundary of the Kupferschiefer and by a time marker that is Illawarra, the boundary of the reversed polarity megachron (Kiaman) and mixed polarity megachron. Three options (A, B, C) have been discussed, which are connected with a time span comprising deposition of the UR II rocks, assuming that the time span needed for the Dethlingen/Lower Notec formations and Hannover/Upper Notec formations is about 6 myr. The time left for the deposition of the Parchim/Lower Drawa, Mirow/Upper Drawa deposits and the time hidden in the erosional gaps and hiatuses range from 1.6 myr to 4 myr or even 8 myr. These were based on the time interval related to the Kiaman Reversed Polarity megachron, which can contain more transient normal polarity zones than currently accepted. The presence and absolute dating of all such magnetozones is difficult to determine because they are represented in continental strata characterized by numerous, poorly time-constrained erosional gaps. The proposed option C is provisionally integrated with magnetostratigraphic results and shows an alternative stratigraphical scheme for the Upper Rotliegend. This alternate Upper Rotliegend stratigraphy helps correlate rocks (deposited in dry arid climatic conditions) in the lower part of the Upper Rotliegend II of the Southern Permian Basin (Havel and Drawa subgroups) with similar rocks in the Delaware Basin (attributed to formations within the Leonardian Regional Series).

The Upper Permian Main Dolomite in the Zechstein 2 cyclothem in the Gorzow Block (part of the Zechstein Basin in western Poland) contains both hydrocarbon source and reservoir rocks, and is sealed both above and below by evaporites. In this paper we propose a new sequence stratigraphic model for the development of potential reservoir rocks in toe-of-slope locations. Data came from detailed analyses of 35 cores from wells in and at the margins of the Wielkopolska platform, a palaeogeographic element composed of Main Dolomite carbonates. In basinal areas, the Main Dolomite carbonates begin with a transgressive interval overlain by laminated dolomudstones interpreted as transgressive facies. The TST begins in the upper part of the underlying Alg anhydrites. The dolostones are underlain by a ravinement surface on the platform, and by a maximum regressive surface in toe-of-slope and basinal locations. In well Gorzow Wielkopolski-2, a hardground marks the maximum flooding surface. Overlying the TST deposits are thick intervals of intraclast-oolitic grainstones and floatstones which are interpreted as highstand deposits and indicate “highstand shedding”. Toe-of-slope facies are composed of alternating laminated dolomudstones, intraclast-oolitic grainstones, packstones and floatstones which make up submarine fans (prisms) interpreted as falling stage facies which are capped by dolomudstones. A subaerial unconformity was recognized on the platform, and a slope onlap surface on the slope and toe-of-slope, respectively. In platform areas, the Main Dolomite begins with thin intervals containing microbial complexes deposited during the early HST, which pass into thick oolitic grainstones (HST to late HST) and terminate as microbial-to-oolitic wackestone and mudstone complexes interpreted as falling stage facies. Thrombolitic bioherms constitute a reference horizon which can be correlated between wells in the study area. The beginning of the LST occurs in the upper part of the Main Dolomite. The boundary between lowstand and transgressive deposits was identified in the lower part of the Basal Anhydrite and is marked by sabkha and salina facies, respectively, where an erosional ravinement surface and maximum regressive surface were identified. Thus, the upper part of the underlying Upper Anhydrite and the upper part of the Main Dolomite deposits form a second depositional sequence in the study area. The depositional environment of the Main Dolomite platform carbonates was variable, and was influenced by the topography of the pre-existing evaporitic platform. The newly proposed sequence stratigraphic model emphasises the role of forced regressive submarine fans as potential hydrocarbon accumulations and traps in the toe-of-slope area.

Abstract Organic-rich mesohaline microbial mats occur in the intertidal zone of a lagoonal area developed to the lee of a coastal spit in Mesaieed, Eastern Qatar. The mats grow on a substrate of seagrass-rich carbonate mud with cerithid and monachid gastropods and other small bioclasts, reaching a thickness >3.5 cm. The mats are well laminated with different microbial communities, from cyanobacteria to sulphur bacteria, reflected in the distinct colour changes from green to pink to brown. The mat layers contain spheroids of dolomite, the precipitation of which was plausibly mediated by bacteria. The lipids reflect the biomass of the principal mat-building phototrophic and heterotrophic microorganisms. A variety of hydrocarbons, including n-alkanes, diploptene, and isoprenoids such as phytane, phytene, phytadiene and squalene were detected, in varying concentrations amongst the particular mat layers. In particular, n-heptadecane, likely derived from cyanobacteria, dominated the n-alkane distribution at a depth of 0–0.1 mm. The concentration and abundance of n-alkanes increase with depth through the mat, likely representing the early diagenetic initiation of hydrocarbon generation. Therefore, understanding early diagenetic organic matter alteration and preservation in marine mixed carbonate-evaporite-siliciclastic systems, as well as the processes operating in the early stages of diagenesis, could improve understanding of the hydrocarbon potential of such systems. This will help considerably in the prediction of hydrocarbon occurrence in frontier, as well as mature, petroleum carbonate-evaporite basins. Introduction Carbonate rocks are an important source of petroleum deposits, both as reservoir rocks and possibly also as source rocks. Evaporitic environments are one of the most productive sedimentary settings for organic matter, as evidenced by prolific hydrocarbon production from many evaporite-carbonate formations (Warren 2006 with references). This arises not only from the unique reservoir properties of plaform carbonates but also from early diagenetic transformations of organic matter and mineral diagenesis (e.g. Gautier et al., 1985; Wakeham & Ertel 1988). Previously Emery (1956) and Evans (1966) showed that organic carbon contents in modern evaporitic deposits in the Persian Gulf range from 0.5–1.5 wt%. Later, Vita-Finzi & Phethean (1980) reported higher values between 0.15–3.34 wt%, of muds in the inlets of the Musandam Peninsula near the entrance of the Persian Gulf. Shearman & Skipwith (1965) suggested that the mucilaginous jackets which surround most shallow-water carbonate grains may indeed be the source of much of the kerogen in carbonate rocks. Kenig et al. (1989, 1991), together with Baltzer et al. (1994), analysed the organic matter in shallow-water lagoonal and intertidal sediments of Abu Dhabi. Three different organo-sedimentary facies were distinguished, with distinct organic signatures that persist after burial and which are related to the rate of change of sea-level, substrate morphology and rates of sedimentation. Both Kenig et al. (1991), and later Kendall et al. (2002), pointed out the source potential of these microbial mats.

A recently investigated Zechstein Limestone (Ca1, Wuchiapingian) bryozoan fauna from the Polish part of the Southern Permian Basin (SW Poland) is dominated volumetrically and taxonomically by fenestellids. In total six species from five genera are recognized, comprising two species of trepostomes belonging to Dyscritella Girty, 1911 and four fenestellids attributed to Kingopora Morozova, 1970, Kalvariella Morozova, 1970, Acanthocladia King, 1849 and Spinofenestella Termier and Termier, 1971. The greatest biodiversity of the bryozoans in the Ca1 profiles studied is within the slope facies where large, fan-shaped and funnel-shaped reticulate fenestellid colonies up to 10 cm high dominate. In contrast, bryozoans in the marginal (proximal) parts of the basin mostly comprise trepostomes, represented by encrusting plate-like or coil-shaped colonies of Dyscritella Girty, and commonly broken branched colonies of Acanthocladia King. The changes in the biotic composition of the bryozoans and the presence of a dominant colony growth form in the stratigraphical profile of the Ca1 reflect the depositional environment and water energy. These factors stimulate the successive stages of the development of the biota and their settlement, marked by the rich productid-fenestellid assemblages typical of the offshore setting, with the maximum depth in the middle part of the Ca1 in the Grodziec Syncline. The proximal tempestites and foreshore facies of the upper part of the Ca1 (Leszczyna Syncline) terminate the sedimentary cycle of the Ca1, with the remnant, broken bryozoans of Acanthocladia and fenestellids. The relationship between the taxonomic composition, colony growth-patterns, associated biota, and sedimentary structures points to slow sedimentation rate on slope and basin floor of the Ca1 carbonate platform. The fenestellids which are dominated in the studied biota by the reticulate and pinnate colonies of Spinofenestella, Kingopora, Kalvariella and Acanthocladia mark a close palaeogeographical link with the Zechstein (Ca1) bryozoans of Great Britain, Germany and the southern Baltic region.

The color varieties of spodumene (green spodumene, kunzite) from Nilaw mine (Nuristan, Afghanistan) have been investigated by microthermometry and Raman spectroscopy analyses. These minerals are rich in primary and secondary fluid inclusions. Measured values of temperature homogenization (T(h)) and pressure (P) for selected fluid-inclusion assemblages (I-IV) FIA in green spodumene and (I-II) FIA in kunzite ranges from 370 to 430°C, 1.16 to 1.44 kbar and 300 to 334°C, 0.81 to 1.12 kbar, respectively. The brine content and concentration varies from 4.3 to 6.6 wt.% eq. NaCl. Numerous and diverse mineral phases (quartz, feldspars, mica, beryl, zirconium, apatite, calcite, gypsum) present in this mineral as solid inclusions were studied by Raman microspectroscopy. Raman spectra of selected fluid, organic and solid inclusions were collected as line or rectangular maps and also depth profiles to study their size and contents. There appeared very interesting calcite (156, 283, 711 and 1085 cm(-1)), beryl (324, 397, 686, 1068 and 3610 cm(-1)), topaz (231, 285, 707, 780 and 910 cm(-1)) and spodumene (355, 707 and 1073 cm(-1)) inclusions accompanied by fluid and/or organic inclusions (liquid and gas hydrocarbons) with bands at 2350 cm(-1) (CO(2), N(2)), 2550 cm(-1) (H(2)S) and 2900 cm(-1) (C(2)H(6)-CH(3)). Some solid inclusions contain carbonaceous matter (D-band at ca. 1320 cm(-1) and/or G-band at ca. 1600 cm(-1)).