Degree Of Amalgamation Research Articles

Depositional evolution of a tectonically‐confined proximal‐foredeep deep‐marine system: Miocene Serra Palazzo Formation (Southern Apennines, Italy)

The Miocene Serra Palazzo Formation (SPF) was deposited in a foredeep basin in front of the growing Southern Apennines orogenic wedge. A new detailed facies analysis, based on high‐resolution physical stratigraphy, for a 570 m‐thick interval, has been undertaken in order to reconstruct the depositional history. Two phases of development can be recognized. The older one was characterized by the sedimentation of sandy channel‐lobe transition zone (cltz) deposits with various degrees of amalgamation; roughly in the middle, a 26 m‐thick sandy megaturbidite was deposited. At this time, basin topography, including the inbound slope base and topography due to the orogen‐related flexural subsidence, caused significant flow confinement illustrated by a number of sedimentary features, such as syn‐sedimentary deformation structures, hummocky laminations, and differences in the palaeocurrent directions recorded in the same event bed. The younger phase was characterized by the sedimentation of more‐proximal amalgamated sandy channel deposits, followed upwards by an even more‐proximal sequence of thick levees with thin‐bedded and fine‐grained facies. Tectonics was one of the main controls on the stacking patterns of the submarine fans of the SPF basin. Particularly, the outward thrust migration governed the evolution from the cltz deposits to the levee deposits and it might have caused the repeated waxing‐waning flow cycles recorded in the channel deposits and the changes in bed dip angles in the levee deposits.

Arquitetura estratigráfica dos depósitos fluviais albianos da base da Formação São Mateus no norte da Bacia do Espírito Santo

Os depósitos aluviais da Formação São Mateus (Albiano da Bacia do Espírito Santo, Brasil) consistem em importantes reservatórios. Entretanto, existem poucos trabalhos detalhando a estratigrafia deste intervalo estratigráfico. Em decorrência disso, este trabalho teve por objetivo estabelecer um fatiamento estratigráfico de alta resolução da seção basal desta unidade, a qual é constituída por depósitos fluviais. Diante das dificuldades apresentadas para a correlação estratigráfica desses depósitos, a estratégia de correlação utilizada foi a subdivisão da sucessão aluvial em ciclos estratigráficos. Este método se baseia na variação na razão entre as taxas de criação de acomodação e suprimento sedimentar (A:S) que diretamente controla o grau de amalgamação dos corpos arenosos de canais fluviais. Com isso, foram definidos seis ciclos compostos internamente por tratos de sistemas de alta e baixa acomodação. Esses ciclos refletem a estruturação do arranjo da amalgamação dos canais fluviais com os depósitos externos aos canais através da razão entre a taxa de acomodação (A) e a taxa de influxo sedimentar (S) formando ciclos.

Stratigraphic complexity in fluvial fans: Lower Eocene Green River Formation, Uinta Basin, USA

AbstractIn this study, measured outcrop sections and geolocated photomosaics are integrated with areal mapping of channel dimensions, degree of amalgamation, calculations of channel‐to‐floodplain ratios and sedimentary facies variability to study and quantify the channel and floodplain deposits in the Sunnyside Delta Interval of the Lower Eocene Green River Formation in the Uinta Basin, Utah. Vertically, sand content and bed thickness increases, due to an increase in the channel‐to‐floodplain ratio, channel size and the degree of channel amalgamation. Laterally, the channel‐to‐floodplain ratio, channel size, the degree of channel amalgamation and the sand content in channel facies decreases in the paleo‐downstream direction. Such vertical and lateral transitions identify the Sunnyside Delta Interval as a fluvial fan (or distributive fluvial system). However, the vertical and lateral transitions occur at multiple spatial scales, demonstrating considerable stratigraphic complexity as compared to the existing facies and architectural models suggested for fluvial megafans and distributive fluvial systems. The smallest‐scale transitions are identified as avulsion‐related packages that form the building blocks of the stratigraphy, whereas the intermediate‐ and largest‐scale transitions are suggested to be related to lobe and whole fan progradation respectively. This documented complexity indicates the significance of self‐organization in building fluvial fan stratigraphy, and demonstrates that changes in the degree of channel amalgamation or in channel‐to‐floodplain ratio are not linked to accommodation changes. On facies scale, an abundance of Froude supercritical‐flow and high‐deposition‐rate facies, in‐channel mud deposits, and in‐channel bioturbation and desiccation indicate deposition in rivers with highly variable discharge. Such discharge conditions suggest seasonally and inter‐annually variable precipitation conditions in the US Western Interior in the Early Eocene.

Multi‐scale classification of fluvial architecture: An example from the Palaeocene–Eocene Bighorn Basin, Wyoming

AbstractFluvial channel geometry classification schemes are commonly restricted in relation to the scale at which the study took place, often due to outcrop limitations or the need to conduct small‐scale detailed studies. A number of classification schemes are present in the literature; however, there is often limited consistency between them, making application difficult. The aim of this study is to address this key problem by describing channel body geometries across a depositional basin to ensure that a wide range of architectures are documented. This was achieved by studying 28 locations over 4000 m of vertical succession in Palaeocene‐aged and Early Eocene‐aged deposits within the Bighorn Basin, Wyoming, USA. Five different channel body geometries have been defined based on the external geometric form, and internal arrangement and nature of storey contacts. These include the massive channel body geometry, semi‐amalgamated channel body geometry, internally amalgamated channel body geometry and offset stacked channel body geometry, which are considered to be subdivisions of the sheet geometry of many other classifications. An isolated channel body geometry has also been recognized alongside splay channel and sheet sandstone geometries in the floodplain facies associations. Field evidence, including the stacking style of storey surfaces, suggests that the different geometries form a continuum. The nature and degree of amalgamation at the storey scale are important in producing the different geometries and are related to the degree of channel migration. It is speculated that this is the result of differences in sediment supply and available accommodation. In contrast to previous schemes, the classification scheme presented here recognizes the importance of transitional geometries. This geometrical range has been recognized because of the basin‐scale nature of the study.

The impact of fine-scale turbidite channel architecture on deep-water reservoir performance

This article concentrates on the question, Which parameters govern recovery factor (RF) behavior in channelized turbidite reservoirs? The objective is to provide guidelines for the static and dynamic modeling of coarse reservoir-scale models by providing a ranking of the investigated geologic and reservoir engineering parameters based on their relative impact on RF. Once high-importance (H) parameters are understood, then one can incorporate them into static and dynamic models by placing them explicitly into the geologic model. Alternatively, one can choose to represent their effects using effective properties (e.g., pseudorelative permeabilities). More than 1700 flow simulations were performed on geologically realistic three-dimensional sector models at outcrop-scale resolution. Waterflooding, gas injection, and depletion scenarios were simulated for each geologic realization. Geologic and reservoir engineering parameters are grouped based on their impact on RF into H, intermediate-importance (M), and low-importance (L) categories. The results show that, in turbidite channel reservoirs, dynamic performance is governed by architectural parameters such as channel width, net-to-gross, and degree of amalgamation, and parameters that describe the distribution of shale drapes, particularly along the base of channel elements. The conclusions of our study are restricted to light oils and relatively high-permeability channelized turbidite reservoirs. The knowledge developed in our extensive simulation study enables the development of a geologically consistent and efficient dynamic modeling approach. We briefly describe a methodology for generating effective properties at multiple geologic scales, incorporating the effect of channel architecture and reservoir connectivity into fast simulation models.

Facies and Architectural Asymmetry in a Conglomerate-Rich Submarine Channel Fill, Cerro Toro Formation, Sierra Del Toro, Magallanes Basin, Chile

Abstract Cross-sectional asymmetry is characteristic of sinuous channels in both fluvial and submarine settings. Less well documented are the facies distributions of asymmetric channels, particularly in submarine settings. Exposures of the axial submarine channel-belt in the Magallanes retro-arc foreland basin on Sierra del Toro represent the fill of a 3.5 km wide, 300 m thick channel complex, here termed the “Wildcat,” that displays an asymmetric cross section and facies distribution. Measured sections and mapping demonstrate that facies proportion, degree of amalgamation, and margin architecture vary laterally from east to west across the Wildcat channel complex. The eastern side is characterized by thick-bedded, amalgamated sandstone and clast- and matrix-supported conglomerate that onlap a steep, simple margin adjacent to sandy overbank deposits. The western side contains thin-bedded, sandy and muddy strata that onlap a shallow composite margin adjacent to mud-rich out-of-channel strata. The observed asymmetry is likely due to centrifugal flow forces and was caused by a low-sinuosity right-hand meander bend of the Cerro Toro axial channel-belt. The facies and architecture of the opposing margins indicate that the eastern and western sides constitute the outer and inner bends of the Wildcat channel complex, respectively. The modest cross-sectional asymmetry of the Wildcat complex is likely a product of the low channel-belt sinuosity. The absence of lateral accretion surfaces and deposits suggests that the channel did not migrate during filling. Flows depositing the uppermost channel fill were only weakly confined, resulting in flow divergence and overbank deposition. A depositional model that incorporates the asymmetric facies distributions and the contrasting outer-bend and inner-bend architecture of the Wildcat channel complex is also presented. Similar facies distributions exist in other low-sinuosity submarine channels, and even more extreme facies and cross-sectional asymmetry probably characterize more highly sinuous channels. Data on facies distributions presented here represents a useful resource for constraining numerical and experimental models of the evolution of sinuous submarine channels as well as reservoir models of sinuous submarine channels.

Kommunalreformens konsekvenser: Kommunalpolitikernes rolle, borgernes lokaldemokratiske opfattelse og den administrative organisering

This article reviews the empirical literature on the consequences of the municipal amalgamations under the Danish Municipal Reform of 2007. Specifically, three areas of research are reviewed: the role of local coun- cilors, the perception of local democracy among citizens and administrative organizational changes. First, the research points to lower perceived influence among local councilors of amalgamated councils. However, these trends have not affected the degree of voluntary retirement among councilors or the strong consensual norm of Danish local politics. Second, studies point to substantially reduced internal and external political efficacy among citizens in amalgamated municipalities. Furthermore, the negative effects seem to be dependent on the degree of amalgamation. Third, the amalgamations have had varied impact on organizational changes with increased horizontal division of the administration and the number of citizen service centers on one hand, and at the same time no shift in the use of contracting out or the use of internal contracts. Finally, the article points to consequences of the reform of which we still need to gain a better understanding.

Kommunesammenlægningernes betydning for kommunalpolitikernes motivation

This paper examines the impact of the major Danish municipal amalgamations of 2007 on the motivational bases for politicians in local government. The focus is narrowed down to Public Service Motivation (PSM), a form of altruistic motivation present in the provision of public services. Two subdimensions of PSM, Public Interest and User Orientation, are used. The analysis shows that Public Interest is unaffected by amalgamation degree, while User Orientation is negatively affected. In other words, the councillors, who have experienced the highest degrees of amalgamation, have the lowest degree of User Orientation.

Stratigraphic evolution of an outcropping continental slope system, Tres Pasos Formation at Cerro Divisadero, Chile

AbstractDepositional slope systems along continental margins contain a record of sediment transfer from shallow‐water to deep‐water environments and represent an important area for natural resource exploration. However, well‐preserved outcrops of large‐scale depositional slopes with seismic‐scale exposures and tectonically intact stratigraphy are uncommon. Outcrop characterization of smaller‐scale depositional slope systems (i.e. < 700 m of undecompacted shelf‐to‐basin relief) has led to increased understanding of stratigraphic packaging of prograding slopes. Detailed stacking patterns of facies and sedimentary body architecture for larger‐scale slope systems, however, remain understudied. The Cretaceous Tres Pasos Formation of the Magallanes Basin, southern Chile, presents a unique opportunity to evaluate the stratigraphic evolution of such a slope system from an outcrop perspective. Inherited tectonic relief from a precursor oceanic basin phase created shelf‐to‐basin bathymetry comparable with continental margin systems (∼1000 m). Sedimentological and architectural data from the Tres Pasos Formation at Cerro Divisadero reveal a record of continental margin‐scale depositional slope progradation and aggradation. Slope progradation is manifested as a vertical pattern exhibiting increasing amounts of sediment bypass upwards, which is interpreted as reflecting increasing gradient conditions. The well‐exposed, seismic‐scale outcrop is characterized by four 20 to 70 m thick sandstone‐rich successions, separated by mudstone‐rich intervals of comparable thickness (40 to 90 m). Sedimentary body geometry, facies distribution, internal bedding architecture, sandstone richness and degree of amalgamation were analysed in detail across a continuous 2·5 km long transect parallel to depositional dip. Deposition in the lower section (Units 1 and 2) was dominated by poorly channellized to unconfined sand‐laden flows and accumulation of mud‐rich mass transport deposits, which is interpreted as representing a base of slope to lower slope setting. Evidence for channellization and indicators of bypass of coarse‐grained turbidity currents are more common in the upper part of the > 600 m thick succession (Units 3 and 4), which is interpreted as reflecting increased gradient conditions as the system accreted basinward.

Diamond anniversary greetings from Winnipeg, Manitoba

It does not seem long ago since I served as President of our Society, when, in fact, we were only into our third decade of activity. Several of you who currently read The Canadian Journal of Cardiology were working with me at that time. Others were just dreaming about a career in medicine. And yes, some readers had not even seen the light of day. Whatever your experience, I would like to turn back the pages and share memories from some of the most rewarding years in my career. When I served as president in 1974 to 1976, the notion of simpler, calmer and gentler times applied to our world of cardiology. We had not yet been overwhelmed by the array of technological advances on the horizon. When a new research tool or piece of equipment hit the market, it did not become obsolete once the wrapping was removed. Practices and policies changed from year to year, certainly, but it was not yet an era of relentless upheaval in virtually every aspect of work with patients, hospitals and associates from other fields. Nor were we able to benefit from up-to-the-minute news of our colleagues’ activities across Canada, given that the launch of the Journal was still several years away. All the same, we did make encouraging inroads in cardiac care during the 1970s and maintained Canada’s respected profile throughout the world. During my term, I was fortunate to be part of a talented, hard working and resourceful council. It included nationwide representation from Nova Scotia to British Columbia, and the members pursued a full agenda of timely issues. One of our most significant challenges was to sell our synopsis of standards with respect to coronary care units and cardiac surgical intensive care units to the federal government. Dr Claude Labrosse of the Sherbrooke University Hospital Centre in Sherbrooke, Quebec, chaired the task force. He obtained input from a broad range of cardiologists and cardiac surgeons across Canada and then presented a brief in Ottawa. It may well have been the first official submission to recommend combined or adjacent coronary and cardiac surgical units. Another matter on our action list concerned the granting of affiliate status to groups such as the Canadian Stroke Network and the Canadian Council of Cardiovascular Nurses (both had representatives on our council, but were not fully affiliated in any formal sense). The Canadian Society of Clinical Perfusion also expressed interest in joining the Canadian Cardiovascular Society (CCS). Personally, I was in favour of these societies becoming our affiliates, with full voting rights and active representation at the scientific annual meetings. On the other hand, our by-laws did not permit such a degree of amalgamation and would have had to be amended. Although the council and I had different opinions as to how quickly we should evolve in concert with other colleagues, the issue was eventually resolved after my tenure. We did not exactly get the ball rolling, but at least the ball got placed squarely on the field! One can never underestimate the important role that the province of Quebec has played in the history of the CCS. Our Society’s very existence is rooted in talks that originated in Montreal, and during the 1970s, the Quebec Heart Foundation kindly offered to accommodate the CCS in Montreal, so we could finally boast of having a ‘head office’. Despite the changes that have taken place in our profession, there remains a constant factor that bridges the generations, in terms of both time and people; that is the role that trainees and newly certified cardiologists can play in making the CCS a strong advocate for professionals involved in treating and preventing heart disease. It goes without saying that their energy and talent are crucial in clinics, hospitals and laboratories. However, we also need their collective voice backing our efforts to lobby governments to remain onside in creating a world-class cardiac care system. Our Society can only be as effective and relevant as the sum of its individual members, be they the young or the young-at-heart. When I attend our next annual conference in Quebec City, Quebec, I will pay particular attention to the contributions of our newest members. Although I am retired from the practice of cardiology, I still do some research. I look forward to hearing of innovations in research and practice from the future leaders in our field. I have always regarded the teacher-student relationship to be a privilege and a rewarding experience. Happy anniversary to one and all.

MESOSCALE HETEROGENEITY OF FLUVIAL‐LACUSTRINE RESERVOIR ANALOGUES: EXAMPLES FROM THE EOCENE GREEN RIVER AND COLTON FORMATIONS, UINTA BASIN, UTAH, USA

The Eocene Uinta Basin of Utah is a dominantly lacustrine basin that affords the opportunity to survey analogue sandstone reservoirs developed within and adjacent to the lacustrine system. From its SW to NE margin, Eocene strata in the Uinta Basin record fluvial, deltaic, profundal lacustrine, and wave‐dominated shallow‐lacustrine environments. Of these depositional systems, analogue sandstone reservoirs are well‐exposed in outcrop in the fluvial‐deltaic and wave‐dominated intervals. Field and petrographic examination of selected fluvial‐lacustrine reservoir analogues are used to document the mesoscale facies architecture and heterogeneity. Complex depositional geometries and heterogeneity exist at a variety of scales, both within single subenvironments and between opposite sides of the basin.Three outcrops in the Uinta Basin were studied. Outcrops One and Two are located in the SW portion of the basin in Nine Mile Canyon, and represent the interface between fluvial rocks of the Colton Formation and dominantly lacustrine strata of the Green River Formation. Outcrop Three is located at Raven Ridge in the NE of the basin, a shallow wave‐dominated lacustrine margin. Photomosaics and multiple vertical measured sections were described for each outcrop, and were utilized to document lithofacies assemblages, bounding surfaces, and sandbody architecture and heterogeneity. Sandstone samples from each outcrop were analyzed petrographically to capture the small‐scale heterogeneity characteristic of the three outcrops.Sedimentary rocks at Outcrops One and Two consist of lenticular, tabular, or undulatory channel, distributary channel, and bar deposits that are partially to entirely compartmentalized, or encased, by mudstone units. These sandstone units, analogous to reservoir intervals in lacustrine basins, show various types of lateral and vertical connectivity which are dependent on the degree of amalgamation and the sand:mud ratio. Within these sandbodies, mud chip lags, large mud clast horizons, discontinuous finer‐grained beds, accretion sets and amalgamation surfaces represent internal heterogeneity which could be expected to affect transmissibility in an actual reservoir. The complex geometry and heterogeneity characteristic of these reservoir analogues confirms the need for detailed reservoir characterization studies on all scales in order to improve production efficiency in such systems.Outcrop Three is dominated by tabular and laterally extensive offshore bar and sandsheet deposits which are separated by thick mudstone units. Large‐scale heterogeneity is minimized within these reservoir analogues, in that sandbodies exhibit excellent lateral continuity and less complex amalgamation. Therefore, documentation of heterogeneity at the bed‐ and petrographic‐scale is necessary to better address production potential in these types of reservoirs.

GEOMETRY AND CONNECTIVITY OF DISTRIBUTARY CHANNEL SANDSTONES IN THE LATE PERMIAN MORANBAH COAL MEASURES, BOWEN BASIN, AUSTRALIA

The fluvio-deltaic Moranbah Coal Measures are an extensively mined Late Permian coal-bearing sequence that crops out along the western limb of the Bowen Basin, Queensland. Data from operating coal mines provide high resolution datasets for detailed petroleum reservoir analogue studies. In this study, data from subsurface drilling and high wall exposures were used to produce a three-dimensional sub surface model of coal and sandstone geometry in a 200 m stratigraphic section over an area of 184 km2. Detailed analysis of the interval between the extensive Goonyella Middle seam and the 'P'-Tuff identified: 1) thin (10 km long) interpreted as trunk distributary channel-fill deposits. These are flanked by finer grained sediments containing a series of heterolithic units that display large siltstone-draped accretionary cross-stratification reflecting channel/splay deposition. Reservoir continuity in the Moranbah Coal Measures is controlled by coal seam splitting and the degree of amalgamation between sandstone bodies. Analogues for potential reservoirs within these systems include 1) very thick (>40 m), vertically-stacked amalgamated sandstone sequences with good connectivity; 2) thick (>25 m) stacked sandstone units separated by carbonaceous mudstone horizons that reduce vertical connectivity; and 3) thick sing le-sequence sandstone units with good lateral connectivity Marginal zones are fine grained and often faulted, acting as barriers to connectivity between potential reservoir sandstones.

Wetting of amalgam alloys by mercury

The degree of wetting of amalgam alloy by mercury during trituration is an important variable in determining reaction rates and the degree of amalgamation. The purpose of this study was to measure the contact angle made by mercury on various phases present in amalgam alloy in air and on commercial alloys. During amalgamation, mercury is in contact with the oxides present on the amalgam alloy as well as the metallic amalgam phase. To measure the degree of wetting of the metallic phases, silver, tin, and copper were melted in such proportions as to give specimens of silver, tin, the alpha, beta, and gamma silver-tin phases, the eutectic in the silver-copper system. These were cast in the form of cylinders, sectioned, and the surfaces prepared by sandblasting. Oxide specimens of AgO, Ag2O, SnO, and SnO2 were prepared by compaction in a mold. Four commercial amalgam alloys also were tested. Mercury drops were then placed on the surfaces and the contact angles measured at different time intervals. The initial contact angles of mercury on the alpha, beta, gamma, and eutectic phases were found to be 90degrees, 112 degrees, 145 degrees, and 138 degrees, respectively. Mercury reacted with silver and tin, resulting in a change of contact angle with time. Contact angles measured on the commerical alloys were also high, on the order of 145 degrees. The gamma phase had contact angles closest to those of commercial alloys. Surface oxide phases are most likely responsible for this poor wettablility by mercury.