Complex Sedimentary Environments Research Articles

Characteristics and controlling factors of glutenite reservoir rock quality of retrogradational fan Delta: A case study of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin

The glutenite reservoir rock of the fan delta facies is associated with a complex sedimentary environment and high heterogeneity, and by far the characteristics and controlling factors of the reservoir rock quality have not been well understood. By comprehensively investigating the lithofacies, petrology, physical properties and diagenesis of the Upper Wuerhe Formation of the Mahu Sag, the Junggar Basin, it is concluded that the Upper Wuerhe Formation develops three major groups of lithofacies, totally consisting of 11 sub-types, and reservoir rock properties of different lithofacies are greatly varied. This research shows that the lithofacies attributed to the tractive current and density current have well-sorted rock particles, low mud content, well-developed secondary dissolved pores, and thus high overall reservoir rock quality. On the contrary, the lithofacies based on debris flow and sheet flow, are observed with high mud content, suppressed development of intergranular and dissolved pores, and thus poor reservoir rock quality. The system tract controls the macro variation of the reservoir rock quality. The best quality is found in the highstand system tract, followed by those of the lake transgression and at last lowstand system tracts. The micro variation of the reservoir rock quality is determined by the mud content, rock particle size and dissolution. The muddy matrix mainly damages the pore connectivity, and presents the strongest correlation with permeability. The reservoir rock with concentrated particle sizes and well-sorted particles has quality better than those of reservoir rocks composed of excessively large or small particles. Dissolution effectively improves the storage capability of the reservoir rock, resulting in an average porosity increment by 4.2%.

Acoustic scattering characteristics and inversions for suspended concentration and particle size above mixed sand and mud beds

The majority of reported field studies, using acoustic backscattering, for the measurement of nearbed suspended sediment processes, have been focussed on field sites with sand size fractions and unimodal size distributions. However, in many sedimentary environments, and particularly for estuaries and rivers, sands and muds coexist in the bed sediment substrate, forming a size regime that is often bimodal in nature. To examine the interaction of sound in these more complex sedimentary environments a numerical study is presented based on observations of sediment size distributions measured in the Dee estuary, UK. The work explores the interpretation of the backscatter signal from a mixed sediment composition in suspension, with mud-sand fractions varying with height above the bed. Consideration is given to the acoustical scattering properties and the inversion of the backscatter signal to extract information on the suspension. In common with most field deployments, the scenarios presented here use local bed sediments for the acoustic inversion of the backscattered signal. The results indicate that in general it is expected that particle size and concentration will diverge from what is actually in suspension, with the former being overestimated and the latter underestimated.

Production behavior evaluation on multilayer commingled stress-sensitive carbonate gas reservoir

Influenced by the complex sedimentary environment, a well always penetrates multiple layers with different properties, which leads to the difficulty of analyzing the production behavior for each layer. Therefore, in this paper, a semi-analytical model to evaluate the production performance of each layer in a stress-sensitive multilayer carbonated gas reservoir is proposed. The flow of fluids in layers composed of matrix, fractures, and vugs can be described by triple-porosity/single permeability model, and the other layers could be characterized by single porosity media. The stress-sensitive exponents for different layers are determined by laboratory experiments and curve fitting, which are considered in pseudo-pressure and pseudo-time factor. Laplace transformation, Duhamel convolution, Stehfest inversion algorithm are used to solve the proposed model. Through the comparison with the classical solution, and the matching with real bottom-hole pressure data, the accuracy of the presented model is verified. A synthetic case which has two layers, where the first one is tight and the second one is full of fractures and vugs, is utilized to study the effects of stress-sensitive exponents, skin factors, formation radius and permeability for these two layers on production performance. The results demonstrate that the initial well production is mainly derived from high permeable layer, which causes that with the rise of formation permeability and radius, and the decrease of stress-sensitive exponents and skin factors, in the early stage, the bottom-hole pressure and the second layer production rate will increase. While the first layer contributes a lot to the total production in the later period, the well bottom-hole pressure is more influenced by the variation of formation and well condition parameters at the later stage. Compared with the second layer, the scales of formation permeability and skin factor for first layer have significant impacts on production behaviors.

Prediction of triaxial drained creep behaviors of interactive marine-terrestrial deposit soils by fractal derivative

The mechanical properties of interactive marine-terrestrial (IMT) deposit soils differ from those of other deposits as a result of the complex sedimentary environments in which they are found. The creep behaviors of IMT deposits in Ningbo, China were studied via triaxial drained creep testing. The theory of fractal derivatives was then applied to develop a fractal merchant model, in which a fractal dashpot replaces the conventional Newtonian dashpot, to characterize the triaxial creep behaviors of IMT deposits. The model results indicate that Ningbo deposits demonstrate typical nonlinear creep behaviors. As the creep time and stress level increase, the creep process shows characteristics of transient creep attenuation and shear contraction. To validate the proposed fractal model, its predictive results were compared with the experimental results and those of conventional and fractional merchant models. It was found that the fractal merchant model results agree closely with the experimental results and that it was more accurate and efficient than the other models even though it applies the same number of parameters and has a simpler computational approach than the fractional merchant model.

Spatial and seasonal variability in grain size, magnetic susceptibility, and organic elemental geochemistry of channel-bed sediments from the Mekong Delta, Vietnam: Implications for hydro-sedimentary dynamic processes

Understanding the relationship between depositional processes and their products in the fluvial–marine transition zone in tide-dominated depositional systems is fundamental to improving environmental and stratigraphic interpretations of long-term sedimentary records. The distributary channels of the Mekong Delta represent a typical example of a complex sedimentary environment characterized by strong fluvial and tidal interactions, and seasonal variability in hydro-sedimentary dynamic processes, particularly the migration of a salt wedge front linked to seasonal fluctuations in freshwater discharge. For this study, we analyzed grain size, magnetic susceptibility, and organic elemental geochemistry of channel-bed surficial sediments collected in 2015 from all distributary channels during the dry season and from the Mekong–Co Chien River during the flood season. This paper reports spatial and seasonal differences in the characteristics of channel-bed surficial sediments, which are closely linked to sediment sources and depositional processes during the dry and flood seasons.Distributary channels are characterized by coarse-grained sediments in the upper reaches and fine-grained sediments in the lower reaches, in both dry and flood seasons, reflecting the difference between the upstream fluvial-dominated environment and the downstream tide-dominated environment. Flood season samples from the Co Chien River show higher magnetic mineral contents and a terrestrial source of organic carbon compared with dry season samples, indicating sourcing from the drainage basin and trapping of suspended materials in the distributary channel due to the barrier effect of the saltwater wedge at the river mouth. Compared with the flood season, during the dry season the mud content was lower in the downstream reach close to the river mouth and higher in the upstream reach of the Co Chien River, and the content of magnetic minerals was lower in both reaches, indicating dissolution of magnetic minerals during early diagenesis. Furthermore, the lower C/N ratios (<10) and slightly enriched δ13C values of the dry season samples from the Co Chien River imply an additional contribution of organic carbon from a marine source. These various features imply a landward import of mud into the Co Chien River induced by stronger salinity intrusion during the dry season. Along the downstream tract of the Bassac River, two mud-dominated reaches were identified during the dry season. The magnetic mineral contents, C/N ratios and δ13C values indicate that the mud-dominated reach near the Bassac River mouth is also supplied from resuspended sediments by estuarine circulation and tidal pumping, whereas the mud in the reach that is transitional from fluvial to tide dominance has a riverine supply. The results suggest that the Mekong distributary channels are important sinks for suspended sediments during both the flood and dry seasons, controlled by a sediment trapping mechanism provided by either estuarine processes or the morphological configuration of the channels, both of which are controlled by fluvial–tidal dynamics. These depositional processes may be compensating for the incision of channels induced by sand mining in recent decades.

Migration of risk elements within the floodplain of the Litavka River, the Czech Republic

Floodplains are one of the most complex sedimentary environments used for the reconstruction of human impacts on fluvial deposition and catchment pollution. Studies of polluted floodplains require an interdisciplinary approach, including tools from geomorphology, geophysics, and geochemistry. The spatial distribution of pollutants can reflect not only pollution history but also post-depositional transfers of pollutants. The Litavka River (SW Czech Republic) was impacted by historical mining and processing of Ag-Pb-Zn-Sb sulfidic ores, which resulted in a severely polluted floodplain. Previous studies revealed that nearly all of the floodplain deposits of the Litavka River downstream from the ore district are polluted, indicating massive floodplain aggradation. Our aim was to decipher the role of aggradation in floodplain development by investigating the pollutant distribution in the floodplain fill. Another important goal was to distinguish polluted (modern) sediments from secondarily polluted sediments (which were previously pristine) caused by extensive lateral and vertical post-depositional chemical migration of risk elements within the floodplain fill.The floodplain topography was characterized via a digital terrain model (DTM); the internal structure of the floodplain was determined by electrical resistivity tomography (ERT). Sediment samples were collected from hand-drilled cores across the floodplain along the ERT line, and their elemental composition and magnetic susceptibility were analysed. Dating of sediments was performed via optically stimulated luminescence (OSL).The concentrations of Zn, Pb and Cd, along with values of magnetic susceptibility decreased with increasing distance from the current river channel. However, the spatial patterns of risk elements were more complicated than expected in a fluvial sedimentary environment. Inter-element relationships of risk elements exhibited a complex pattern, with abundant outliers that required the use of robust regression. The results helped distinguish the geochemical difference between proximal and distal floodplains, and to identify zones of anomalous inter-element ratios attributed to post-depositional element migration. The observed migration was significant, and not only vertical but horizontal, spanning a distance of approximately half the floodplain width. Metal migration explains why unpolluted sediments are practically missing from the floodplain fill of the Litavka River. Use of pollution chemostratigraphy, without considering the possibility of post-depositional migration of risk elements, could lead to overestimation of the volume of younger sediments deposited directly within the floodplain and to overestimation of the role of aggradation processes.

Integrating cone penetration testing into the 1D inversion of multi-receiver EMI data to reconstruct a complex stratigraphic landscape.

Conventional apparent electrical conductivity (σa) inversion approaches are generally oriented towards a smooth soil profile with gradual transitions between large stratigraphic entities. In a sedimentary environment, layered models with abrupt boundaries between the different soil units represent the soil profile accurately. Therefore, a 1D σa depth modeling procedure was developed where vertical constraints were subjected by cone penetration testing (CPT). We employed the σa measurements of a multi-receiver EMI instrument to map the stratigraphy of a 53ha estuarine polder area up to a depth of approximately 6.0 to 6.5m. From a limited number of CPT observations, a 4-layered soil stratigraphy was deduced with a variable topsoil containing small-scale features above a layer of either sandy or clayey estuarine deposits, a peat layer of approximately 1m thickness and a Quaternary coarse sand substrate. The detailed vertical observations from the CPT logs allowed to estimate the inversion parameters to perform a step-wise 1D inversion of the EMI σa data, as to direct the inversion towards a realistic outcome. The depth of the interfaces between either the estuarine sediments and the peat layer and between the peat and the sand were estimated with an average error of approximately 0.5m, hereby assuming that the thickness each layer is at least 1m. Moreover, the variable conductivity of the top 2.0m revealed a wide range of small and/or subtle features. To conclude, integrating the laterally dense σa measurements with a limited amount of detailed vertical observations from CPT logs allowed for a pseudo 3D representation of the soil stratigraphy within a complex sedimentary environment. This information could serve as a proxy for a range of applications which necessitate detailed information about the subsoil.

Hydrocarbon field evaluation: case study of ‘Tadelu’ field shallow offshore Western Niger Delta, Nigeria

Field evaluation in a complex sedimentary environment is always tedious due to problems associated with imaging of the subsurface in such areas. The ‘Tadelu’ field in Western Niger Delta, Nigeria, consists of a series of vertically stacked reservoirs in the Agbada Formation, thus making the field a complex sedimentary environment. The main objective of this study is to perform geophysical and petrophysical interpretations of properties that are typical of a shallow marine, transitional environment, with its attendant pattern of subsurface complexities, using 3D seismic and well log data. The approach adopted in achieving this objective included 3D seismic data interpretation, petrophysical rock typing, fluid typing and contact identification and determination of reservoir properties, onwards to reserve estimation for all the hydrocarbon-bearing reservoirs in the field. Five horizons as well as major and minor faults were mapped in the field, and five structural depth maps of reservoirs A, B, B1, C and C1 were generated within the objective depth interval to define the geometry of the reservoirs. Well log data from four wells in the field were studied to characterize the porosity, shale volume and water saturation of the reservoirs. The gamma ray (GR) logs were normalized and used in the computation of shale volume, while available density logs were used in the computation of porosities. Water saturation was determined using the Waxman–Smits model to take into consideration the shaly nature of the reservoir sands. The combination of porosity, shale volume and water saturation cut-off values was used in calculating net pay and net pay averages. The result of the structural interpretation shows that Tadelu field is characterized by two major faults and synthetic faults. The synthetic faults are dipping in northeast–southwest direction, and the closure formed by their hanging walls constitutes the target area for hydrocarbon in the field. However, within the reservoirs of Tadelu field, the net sand range is from 0.17 to 0.99 ft, having an average porosity in the range of 22 to 27 %. Water saturation average ranged from a minimum of 19 to a maximum of 27 %. Porosity in the field is high on the average due to very good to excellent sand quality. These petrophysical deliverables served as an input in the estimation of reserves. The gross rock volume (GRV) was determined by establishing a cut-off at appropriate contact(s). Reserve estimation was performed for the hydrocarbon-bearing sands and a total proven recoverable oil and gas estimate put at 42.797 MMbbl and 13.256 Bscf, respectively.

GDGT distributions on the East Siberian Arctic Shelf: implications for organic carbon export, burial and degradation

Abstract. Siberian permafrost contains a globally significant pool of organic carbon (OC) that is vulnerable to enhanced warming and subsequent release into the contemporary carbon cycle. OC release by both fluvial and coastal erosion has been reported in the region, but the behaviour of this material in the Arctic Ocean is insufficiently understood. The balance between OC deposition and degradation on the East Siberian Arctic Shelf (ESAS) influences the climate–carbon cycle feedback in this area. In this study we couple measurements of glycerol dialkyl glycerol tetraethers (GDGTs) with bulk geochemical observations to improve knowledge of the sources of OC to the ESAS, the behaviour of specific biomarkers on the shelf and the balance between delivery and removal of different carbon pools. Branched GDGT (brGDGT) concentrations were highest close to river mouths, yet low in "ice complex" permafrost deposits, supporting recent observations that brGDGTs are mostly delivered by fluvial erosion, and may be a tracer for this in complex sedimentary environments. BrGDGT concentrations and the branched and isoprenoidal tetraether (BIT) index reduced quickly offshore, demonstrating a rapid reduction in river influence. Stable carbon isotope ratios changed at a different rate to the BIT index, suggesting not only that OC on the shelf is sourced from fluvial erosion but also that erosion of coastal sediments delivers substantial quantities of OC to the Arctic Ocean. A model of OC export from fluvial, coastal and marine sources is able to recreate the biomarker and bulk observations and provide estimates for the influence of fluvial and coastal OC across the whole shelf. The model shows that coastal erosion delivers 43 % of the OC and 87 % of the mineral sediment to the ESAS, but that rivers deliver 72 % of brGDGTs, indicating that brGDGTs can be used as a proxy for river-derived sediment.

Magnetic mineral inventory of equatorial Atlantic Ocean marine sediments off Senegal-glacial and interglacial contrast

SUMMARY In complex sedimentary environments with different sources of the magnetic particles, it is vital that all factors contributing to and affecting the magnetic signals be well understood for a better constrained interpretation of palaeomagnetic and climatic data. Palaeoclimatically driven signals may be convolved with volcanic and cosmogenic sources, and diagenesis may alter the primary magnetic mineral assemblage. Rock magnetic methods and electron microscopy provide suitable means to characterize magnetic assemblages. In this study of core-retrieved sediments from the last 150 kyr off the coast of Senegal (NW Africa), the occurrence of magnetic spherules of volcanic origin and cosmogenic particles appeared to be insignificant. In glacial stages, ferrimagnetic iron and iron-titanium oxides magnetically dominate with few signs of a diagenetic overprint. Low- and room temperature magnetic results reveal evidence for haematite and goethite while haemoilmenite and titanomagnetite were identified from low-temperature AC susceptibility measurements and SEM observations. In contrast, the interglacial samples appeared to have been severely affected by diagenesis, with pyrite making up over 50 per cent of the iron-bearing phases. The Verwey transition observed at 110 K confirms the presence of magnetite. The glacial and interglacial contrast reveals the close link between northwest African climate and the magnetic mineralogy of the sediments.

The Coastal Zone: Papers in Honor of H. Jesse Walker (review)

Reviewed by: The Coastal Zone: Papers in Honor of H. Jesse Walker Chris Houser The Coastal Zone: Papers in Honor of H. Jesse Walker Donald W. Davis and Miles Richardson (editors). Geoscience and Man, Volume 38. Department of Geography and Anthropology, Louisiana State University, Baton Rouge, Louisiana, 2004. 178 pp., $25.00 paper (ISBN 0-938909-10-X). The Coastal Zone: Papers in Honor of H. Jesse Walker is an edited volume of papers that were presented at the Annual Meeting of the Association of American Geographers, New Orleans, in 2003. The stated goal of the volume was to recognize the contributions of H. J. Walker to the Department of Geography and Anthropology at Louisiana State University, and to the broader research community. The papers, which were solicited by the editors from colleagues, students and friends, were published as part of LSU's Geoscience and Man Series. This is very fitting as H. J. Walker contributed to the Geoscience and Man Series through collective works on coastal resources (1975), coastal research (1976) and research techniques (1977). The cover photograph and the title provide the reader with the impression that the volume is a sketch of a coastal scientist. Indeed, this book covers a wide range of [End Page 142] topics relevant to the coastal zone, and it suffers from the weaknesses that characterize this genre of edited volume. It has ten chapters that span a range of topics from coastal evolution (by Grabau) to GIS modeling needs for Oil Spill Contingency Planning (by Ritchie). The studies range from the theoretical (Namikas), field-based (Psuty and Orme) and descriptive (Meyer-Arendt). Also included is the largely administrative "Louisiana's Oil Spill Research and Development Program" (Davis). The problems with the breadth of topics covered in the volume are made worse by the lack or at least explicit definition of a common thread; the Geoscience and Man Series, including those edited by H. J. Walker (1975, 1976, 1977), typically have an explicit theme. With exceptions, the contributions to the volume did not attempt to frame their discussion in the context of Walker's research or even in the fields (e.g. arctic deltaic systems) where he has made his most significant contributions. Only Meyer-Arendt references works authored by Walker, and Grabau notes the role of Walker in the presented research. In this light, the value of this publication is for the most part in the specific topics discussed by the contributors rather than in the work as a whole; there are individual jewels for a patient reader to find. While the editors did not organize the book in sections, this reader is able to identify commonalities in papers spread throughout the volume. Several of the papers provide interesting reviews of the complexity of coastal systems through time and space. Orme examines the morphodynamics of a small seasonal river mouth in Santa Monica Bay, California, in order to provide an improved understanding of seasonal estuaries to assist coastal management. Variability in the balance of river discharge and wave field leads to interannual variability in the morphodynamics. The results of this study are put into context by Brunsden who provides an overview of how geologic and geomorphic inheritance provides the boundary conditions for the contemporary processes acting at the coast. This dependency on the environmental context creates local and regional scale responses to changes in forcing factors. This is followed by Grabau who considers how the evolution of the Hawaiian Archipelago compares with interior landforms. The inability to fit the islands within an ergodic model is attributed to the removal of sediments to abyssal depths and failures of the submarine slopes; the cycle of erosion is reset to zero. Contemporary processes and morphology are determined by the larger geologic and oceanographic setting. The importance of inherited geomorphologic features is further examined by Psuty. Inherited features along with complex fluvial and coastal process linkages have created interesting morpho-sedimentological units in Barnegat Bay, New Jersey. The end result is a complex sedimentary environment in which sedimentary features are unrelated to the more recent processes of estuarine sedimentation. In a paper dealing with modifications to the coast, DeLaune et al. note that the rapid rate...

Sediment Character in a Micro-Tidal, Harbor-Estuary Environment, Göteborg, Sweden

Harbor-estuaries are complex sedimentary environments where both natural and anthropogenic processes influence the distribution and accumulation of sediments, which in turn is of importance for maintenance dredging and pollution control. This paper uses sediment characteristics from the Gota alv estuary, Sweden to evaluate the natural estuarine processes that persist despite the extensive human impact on the estuary and to separate and characterize depositional sub-environments. The most important harbor processes include maintenance dredging and turbulence from ship traffic, and their influence upon shallow stratigraphy and sediment distribution and deposition is significant. Polymodal particle-size distributions are interpreted to reflect the natural estuarine transport processes. Suspension transport is generally predominant, except in the river and inner harbor where bottom transport and selective deposition of sand occur. Particle-size characteristics divide the estuary into four depositional areas: the river and the inner, middle, and outer harbor. The shallow stratigraphy reveals a hiatus between the firm silty clays and the loose recent sediments. The hiatus in the stratigraphy is probably related to dredging in most areas of the harbor. Significant maintenance dredging and turbulence from ship traffic also influence the accumulation (0–61 cm) of recent sediments, during the 20th century.

Identifying Different Populations of Sulphate-reducing Bacteria within Marine Sediment Systems, Using Fatty Acid Biomarkers

The distribution of lipid fatty acids was studied in marine sediment slurries in which sulphate reduction had been stimulated by the addition of acetate, propionate, lactate or hydrogen. Acetate was directly oxidized to carbon dioxide at the expense of sulphate, propionate was incompletely oxidized to acetate at the expense of sulphate, and lactate was largely fermented (approximately 75%) to propionate and acetate, with the propionate subsequently utilized for sulphate reduction. Changes in the lipid fatty acids within these slurries were interpreted by comparison with the lipid fatty acid profiles of pure cultures of Desulfovibrio desulfuricans, Desulfobacter sp. and Desulfobulbus sp. Desulfobacter sp. seems to be the main acetate-utilizing sulphate-reducing bacterium, as in both the slurry and the original sediment the lipid fatty acids in the C12–C18 range (where bacterial contributions would be expected) were dominated by even chain fatty acids similar to the lipid fatty acid distribution of Desulfobacter sp. Desulfobulbus sp. appears to be responsible for propionate oxidation and also for hydrogen consumption as its biomarker fatty acid n-C17:1 was increased significantly by the addition of either propionate or hydrogen. Surprisingly, the biomarker for Desulfovibrio desulfuricans (br-C17:1) was not stimulated in any of the sediment slurries. The results demonstrate that there are at least two functional groups of sulphate-reducing bacteria in marine systems, and that lipid fatty acid analysis is a useful technique for investigating bacterial distributions within a complex sedimentary environment.

Identifying different populations of sulphate-reducing bacteria within marine sediment systems, using fatty acid biomarkers : Taylor, James and R.J. Parkes, 1985. J. gen. Microbiol., 131(3):631– 642. British Council, 10 Spring Gardens, London SW1A 2BN, UK

The distribution of lipid fatty acids was studied in marine sediment slurries in which sulphate reduction had been stimulated by the addition of acetate, propionate, lactate or hydrogen. Acetate was directly oxidized to carbon dioxide at the expense of sulphate, propionate was incompletely oxidized to acetate at the expense of sulphate, and lactate was largely fermented (approximately 75 %) to propionate and acetate, with the propionate subsequently utilized for sulphate reduction. Changes in the lipid fatty acids within these slurries were interpreted by comparison with the lipid fatty acid profiles of pure cultures of Desuljovibrio desuljhricuns, Desufjobacter sp. and Desuljobulbus sp. Desulfbbucter sp. seems to be the main acetate-utilizing sulphate-reducing bacterium, as in both the slurry and the original sediment the lipid fatty acids in the CI2-Cl8 range (where bacterial contributions would be expected) were dominated by even chain fatty acids similar to the lipid fatty acid distribution of Desulfobacter sp. Desulfbbulbus sp. appears to be responsible for propionate oxidation and also for hydrogen consumption as its biomarker fatty acid n-C, 7 : 1 was increased significantly by the addition of either propionate or hydrogen. Surprisingly, the biomarker for Desulfbvibrio desuljuricans (brC , 7:1 ) was not stimulated in any of the sediment slurries. The results demonstrate that there are at least two functional groups of sulphate-reducing bacteria in marine systems, and that lipid fatty acid analysis is a useful technique for investigating bacterial distributions within a complex sedimentary environment .

Biological and abiological processes in a simulated sedimentary system

Abstract A simulated sedimentary system, capable of being controlled and monitored for a considerable length of time without undue disturbance, has been assembled and applied to specific problems of the genesis of stratiform Pb‐Zn ore deposits. Results have been obtained relevant to: (i) the concentration of Pb and Zn from brines to underlying sediments; (ii) the behaviour of microorganisms in metal‐rich, highly saline environments; (iii) the precipitation diagenesis of calcium and magnesium carbonates; and (iv) the diagenesis of organic matter. The experiment has demonstrated the feasibility of simulating a complex sedimentary environment in the laboratory and has indicated the potential of such systems for the investigation of geobiological problems.