Depositional Environment of Fine-Grained Sedimentary Rocks of the Sinamar Formation, Muara Bungo, Jambi

DOI: 10.17014/ijog.v8i1.153The research area is situated in the northwestern side of South Sumatra Basin, which is a part of Muara Bungo Regency, Jambi Province. The Oligocene Sinamar Formation consists of shale, claystone, mudstone, sandstone, conglomeratic sandstone, and coal-seam intercalations. This research was focused on fine sedimentary rock of Sinamar Formation, such as shale, claystone, and mudstone. Primary data were collected from SNM boreholes which have depths varying from 75 m up to 200 m, and outcrops that were analyzed by organic petrographic method, gas chromatography-mass spectrometry (GC-MS) of normal alkanes including isoprenoids, and sterane. The dominant maceral group is exinite, composed of alginite (3.4 - 18%), and resinite (1.6 - 5.6%), while vitrinite maceral consists of tellocolinite 0.4 - 0.6%, desmocollinite 0.4%, and vitrodetrinite 8.4 - 16.6%. Organic petrography and biomarker analyses show that organic materials of shales were derived from high plants and algae especially Botrycoccus species. Botrycoccus and fresh water fish fossil, found in the shale indicate a lacustrine environment

Depositional Environment of the Batuasih Formation on the Basis of Foraminifera Content: a Case Study in Sukabumi Region, West Java Province, Indonesia

DOI: 10.17014/ijog.v7i2.139The research was carried out on the sediments of the Batuasih Formation cropping out at Batuasih Village, Cibatu River, Padaarang Sukabumi. Data obtained from field observation, as well as foraminifera and sedimentology analyses conducted in the laboratory, were used to interpret its depositional environment. The investigation was focused on planktonic and benthic foraminiferal assemblages for depositional environment interpretation that might not be used by previous researchers. The Batuasih Formation is composed of black shaly claystone, where the lower part is rich in clay ball, and limestone intercalations in the upper part of the formation. In Cibatu Section, no clay balls is recognized in the lower part, but intercalations of limestone still occur. However, a contrast difference is found in Padaarang section, where green claystone interbeds with fine-grained sandstone. The Batuasih Formation conformably overlies the Walat Formation containing conglomerate. Foraminifera fossil found in the Batuasih Formation consists of bad preserved black benthic and planktonic foraminifera, more abundant towards the lower part of formation. Based on foraminifera assemblage comprising genus Uvigerina, Cibicides, Elphidium, Operculina, Bulimina, Bolivina, Eponides, and Neoconorbina, supported by sedimentology data, the Batuasih Formation was deposited in a shallow to deep marine environtment, during Early Oligocene (P19) time. Upwards to be the Rajamandala Formation, the depositional environment tends to be shallower gradually

Textural and compositional variations in beach sands along Karachi coast

The texture of clastic sediments is a fairly reliable index of the erosional history and energy conditions of the depositional environment, while its mineralogy reflects the composition of the source rocks. The beach sands of Clifton, Sandspit, Hawkesbay and Paradise Point were studied to determine their erosional history, depositional environment and their sourc

Predicting the depositional environments and transportation mechanisms of sediments using granulometric parameters, bivariate and multivariate analyses

Grain size distribution and classes present in sedimentary rocks are responsive to the physical changes of the transporting media and the basin of deposition. Analyzing grain size data is germane in reconstructing the sedimentary processes including identifying the palaeoenvironment of deposition. Twenty-three (23) samples, mainly sandstones, collected within latitude 6055’-6059’N and Longitude 005044’-005053’E in the Anambra Basin, were subjected to granulometric analysis, where grain size parameters (mean grain size, sorting, skewness and kurtosis) sensitive to environmental conditions were calculated. These parameters were integrated with bivariate and multivariate analyses. Graphic mean (Mz) in the study area range from 1.1 to 2.27 ɸ with an average value of 1.7 ɸ, suggesting that grains are predominantly fine to medium; sorting range from 0.71 to 1.36 ɸ with an average value of 1.02 ɸ, suggesting sediments are moderately sorted; skewness range from -0.57 to 0.51 ɸ with an average value of 1.28 ɸ suggesting coarsely skewed to fine skewed with a predominating near symmetrical skewness and kurtosis range from 0.57 to 1.51ɸ, with an average of 1.28 ɸ suggesting a very platykurtic to leptokurtic character. Bivariate scatter plots of the grains size parameters predicted the environment of deposition as shallow marine. Multivariate analysis calculated from established functions suggested environments that range from beach (backshore) to shallow marine (subtidal). The integration of the granulometric parameters, bivariate and multivariate plots predict an environment that is dominated by high energy indicating that the sediments of the study area were deposited in shallow marine environment. In addition, the Visher and Passega’s C-M diagrams characterized the transport mechanism of the sediments as predominantly by saltation although traction and suspension modes also play some roles

A new model for the formation of microbial polygons in a coastal sabkha setting

The stratigraphic record of microbially induced sedimentary structures spans most of the depositional record. Today, microbes continue to generate, bind and modify sediments in a vast range of depositional environments. One of the most cited of these settings is the coastal microbial mat system of the Persian/Arabian Gulf. In this setting, an extensive zone of microbial mat polygons has previously been interpreted as resulting from desiccation‐related contraction during episodic drying. This study employs 15 years of field‐based monitoring of the interaction between environmental factors and the development and evolution of polygon morphologies to test the desiccation model in this setting. On the basis of these observations, a new model is proposed that accounts for the genesis and development of microbial polygons without the need for desiccation‐induced shrinkage. Conversely, the formation, development and erosion of microbial polygons is a direct result of the production of large amounts of organic matter in a healthy, yet spatially limited, microbial community. The recognition of microbial polygons has previously been applied as a diagnostic tool for the reconstruction of ancient depositional environments. The present study calls these interpretations into doubt. It is inferred that preservation of the microbial polygons as a recognizable form would be rare. Biological degradation and compaction will reduce polygons to produce the ‘wispy’ laminae that are a common feature of ancient sabkha lithofacies

A four stage evolution of the White Channel gravel: Implications for stratigraphy and palaeoclimates

Although the White Channel gravel (WCG) of the Klondike district, Yukon, contains gold placers which have been exploited for over a century, few sedimentological studies have been undertaken. This study reports a four stage evolution of the WCG, comprising: i. An initial downcutting period which preferentially retained gold particles on the base of the strath. ii. An aggradational stage in which gold concentration occurred within sedimentary features. iii. A lacustrine layer representing a depositional hiatus. iv. A final, more rapidly aggrading fluvial stage. Identification of the lacustrine layer has clarified the evolution of the WCG depositional fluvial systems. Architectural element analysis and detailed sedimentological observations have been synthesized to gain a clearer understanding of the spatial variations within the WCG. Additionally, the identification of plant species from pollen within the lacustrine layer provides irrefutable evidence that the Klondike district was at least 7°C warmer during the Pliocene compared to the present

Sediment management and the renewability of floodplain clay for structural ceramics

The Netherlands has vast resources of clay that are exploited for the fabrication of structural ceramic products such as bricks and roof tiles. Most clay is extracted from the so-called embanked floodplains along the rivers Rhine and Meuse, areas that are flooded during high-discharge conditions. Riverside clay extraction is-at least in theory-compensated by deposition. Based on a sediment balance (deposition versus extraction), we explore the extent to which clay can be regarded as a renewable resource, with potential for sustainable use. Beyond that, we discuss the implications for river and sediment management, especially for the large engineering works that are to be undertaken to increase the discharge capacities of the Rhine and Meuse. Extraction rates are based on production statistics for clay, as well as those for fired end-products. Deposition rates are estimated from published and unpublished geological data (clay volumes and thicknesses, datings, etc.) and from morphological modeling studies. Comparisons between extraction and deposition are made at three different time-space scales: (1) long term (post-1850)/large scale (all Dutch floodplains), (2) present/large scale, and (3) present/site scale. The year 1850 is relevant because it approximately marks the beginning of the current, fully engineered river systems, in which depositional processes are constrained by dikes and groynes. As the Industrial Revolution began in the same period, post-1850 sediments can be identified by their pollution with heavy metals. (1) We estimate the post-1850 clay volume in situ at about 0.20 km(3), and the total extracted volume in the same period at about 0.17 km(3). This puts the net long-term average deposition rate of clay at similar to 1.3 million m(3)/year and the corresponding extraction rate at similar to 1.1 million m(3)/year. (2) Current accumulation is approximately 0.4 million m(3)/year and expected to increase, and current extraction is about 0.7 million m(3)/year and expected to decrease. (3) Clay extraction creates a depression that has an increased sediment-trapping efficiency. This local effect is not considered explicitly in large-scale morphological modeling. Based on maximum observed sedimentation rates, we estimate that replenishment of a clay site takes in the order of 150 years. As clay extraction lowers some 0.5 km(2) of floodplain yearly, a surface area of approximately 75 km(2) would be required for sustainable clay extraction. This is about 1/6 of the total surface area of the embanked floodplains. On the long term, clay extraction from the embanked floodplain depositional environment has been sustainable. At strongly decreasing deposition rates, the ratio between extraction and replenishment seems to have shifted towards unsustainable. However, current sedimentation is estimated conservatively. The site-scale approach suggests that, even if extraction would currently exceed deposition, this could be resolved with sediment management, that is, with site restoration measures aimed at higher sediment-trapping efficiency. Our results have implications for river engineering, especially where substantial digging is involved (floodplain lowering, high-discharge bypass channels, obstacle removal). First, this inevitably affects the clay resources that we studied, while resource sterilization should be avoided. Secondly, the effect that any form of digging has on subsequent sedimentation-increased rates-relates to long-term river maintenance. We conclude that floodplain clay is a renewable resource, especially if managed accordingly. Beyond that, we established that clay extraction is a significant, lasting factor in floodplain evolution along the Rhine and Meuse Rivers. The interests of the extractive industry and river managers could be served jointly with sediment management plans that are based on sediment-budget analyse

Seismic Facies Analysis on 2d Seismic Reflection Profile in Baruna and Jaya Line at North East Java Basin

Two dimension (2D) seismic profile of Baruna and Jaya lines at North-East Java Basin show seismic reflector characteristics that can be used to interpret sediment thickness and continuity. Those reflector characteristics that can be applied for seismic facies analysis that represent depositional environment. This study starts from seismic data processing that using Kirchhoff Post Stack Time Migration method which is 2D seismic profile as result. Seismic reflector characterization has been done to both 2D profiles. Seismic reflector characterization was grouped as (i) individual reflection, (ii) reflection configuration, (iii) reflection termination, (iv) external form. Individual reflection characteristics show high and medium amplitude, medium and low frequency, and continuous. Configuration reflection is continuous with parallel and subparallel type. Reflection termination shows onlap, and external form shows sheet drape. Local mound appearance can be interpreted as paleo-reef. Facies seismic anlysis result for this study area is shelf