scholarly journals Geochemistry of Sub-Depositional Environments in Estuarine Sediments: Development of an Approach to Predict Palaeo-Environments from Holocene Cores

Geosciences ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 23
Author(s):  
Dahiru D. Muhammed ◽  
Naboth Simon ◽  
James E. P. Utley ◽  
Iris T. E. Verhagen ◽  
Robert A. Duller ◽  
...  
Keyword(s):  
Clay Mineral ◽  
Depositional Environment ◽  
Compositional Data ◽  
Classification Tree ◽  
Distribution Patterns ◽  
Depositional Environments ◽  
Estuarine Sediments ◽  
Geochemical Data ◽  
Mineral Occurrence ◽  
Geochemical Classification

In the quest to use modern analogues to understand clay mineral distribution patterns to better predict clay mineral occurrence in ancient and deeply buried sandstones, it has been necessary to define palaeo sub-environments from cores through modern sediment successions. Holocene cores from Ravenglass in the NW of England, United Kingdom, contained metre-thick successions of massive sand that could not be unequivocally interpreted in terms of palaeo sub-environments using conventional descriptive logging facies analysis. We have therefore explored the use of geochemical data from portable X-ray fluorescence analyses, from whole-sediment samples, to develop a tool to uniquely define the palaeo sub-environment based on geochemical data. This work was carried out through mapping and defining sub-depositional environments in the Ravenglass Estuary and collecting 497 surface samples for analysis. Using R statistical software, we produced a classification tree based on surface geochemical data from Ravenglass that can take compositional data for any sediment sample from the core or the surface and define the sub-depositional environment. The classification tree allowed us to geochemically define ten out of eleven of the sub-depositional environments from the Ravenglass Estuary surface sediments. We applied the classification tree to a core drilled through the Holocene succession at Ravenglass, which allowed us to identify the dominant paleo sub-depositional environments. A texturally featureless (massive) metre-thick succession, that had defied interpretation based on core description, was successfully related to a palaeo sub-depositional environment using the geochemical classification approach. Calibrated geochemical classification models may prove to be widely applicable to the interpretation of sub-depositional environments from other marginal marine environments and even from ancient and deeply buried estuarine sandstones.

scholarly journals Evaluasi Sistem Pengendapan Uranium Pada Batuan Sedimen Formasi Sibolga, Tapanuli Tengah

EKSPLORIUM ◽  
2016 ◽  
Vol 37 (2) ◽  
pp. 125
Author(s):  
I Gde Sukadana ◽  
Heri Syaeful
Keyword(s):  
Depositional Environment ◽  
Distribution Patterns ◽  
Depositional Environments ◽  
Log Data ◽  
Channel Pattern ◽  
Eastern Area ◽  
Deposit Type ◽  
Data Log ◽  
Surface Geology ◽  
Borehole Log

ABSTRAKUranium di alam dapat terbentuk dalam berbagai tipe cebakan, sesuai dengan sumber, proses, dan lingkungan pengendapannya. Keterdapatan uranium di Sibolga pada batuan sedimen Formasi Sibolga merupakan suatu potensi yang layak untuk dikembangkan tetapi hingga saat ini belum diketahui pola pengendapan dan proses mineralisasi uranium tersebut. Penelitian bertujuan untuk mengetahui pola sebaran batuan dan keterdapatan anomali kadar uranium berdasarkan data geologi, radiometri permukaan, dan data log bor untuk mengetahui proses pengendapan batuan dan mineralisasi uranium. Keterdapatan mineralisasi berdasarkan data log bor tersebar dari satuan konglomerat alas (Kgl 1), satuan batupasir 1 (Bp 1), satuan konglomerat 2 (Kgl 2), dan satuan batupasir 2 (Bp 2) dengan ketebalan dan sebaran semakin ke atas semakin menipis. Sebaran mineralisasi pada bagian timur pada satuan batuan konglomerat 1 lebih didominasi oleh mineral detrital hasil pengendapan epigenetik berupa monasit yang terbentuk pada saat pembentukan granit sebagai batuan sumber. Pada satuan batuan di atasnya mineralisasi berbentuk pola alur (channel) yang berarah timur laut-barat daya, yang terbentuk secara syn-genetic dengan mineral berupa uraninite, carnotite, dan coffinite. Pengendapan batuan Formasi Sibolga berasal dari timur ke arah barat dan pengendapan uranium terjadi akibat perbedaan kondisi lingkungan pengendapan dari oksidasi di bagian timur menjadi lebih reduktif di bagian barat daya. Peningkatan kandungan material organik yang cukup tinggi pada lingkungan pengendapan bagian barat daya menyebabkan lingkungan pengendapan dalam kondisi reduksi.ABSTRACTUranium in nature formed in various deposit type, depends on its sources, process, and depositional environments. Uranium occurrence in Sibolga, hosted in sedimentary rocks of Sibolga Formation, is properly potential to develop; nevertheless, the depositional pattern and uranium mineralization process so far had not been recognized. The research aim is to determine the rock distribution patterns and the existence of uranium grade anomalies based on surface geology and borehole log data. Mineralization occurrences from borehole log data distributed from basalt conglomerate unit (Kgl 1), sandstone 1 unit (Bp 1), conglomerate 2 unit (Kgl 2), and sandstone 2 unit (Bp 2) with their distribution and thickness are thinning to the top. Mineralization distribution in the eastern area, mainly on Kgl 1 unit, dominated by detritus materials from epi-genetic depositional in the form of monazite which is formed along with the formation of granite as its source rock. Meanwhile, mineralization on the upper rocks units formed a channel pattern trending northeast-southwest, which formed in syn-genetic process consist of uraninite, carnotite, and coffinite. Sibolga Formation deposition originated from east to west and uranium deposit formed because of the differences of depositional environment from oxidation in the east to the more reductive in the southwest. The increasing of organic materials in southwest basin caused the reduction condition of depositional environment.

scholarly journals Geochemistry water of the Camaquã das Lavras and Hilário streams, Lavras do Sul-RS: anthropogenic or natural?

2020 ◽  
Vol 15 (1) ◽  
pp. 1
Author(s):  
Cristiane Heredia Gomes ◽  
Arthur Pedroso Viçozzi ◽  
Guilherme Pazinato Dias ◽  
Diogo Gabriel Sperandio
Keyword(s):  
Electrical Conductivity ◽  
Clay Mineral ◽  
Human Activities ◽  
Distribution Patterns ◽  
Mineral Weathering ◽  
Statistical Analyses ◽  
Total Alkalinity ◽  
Mineral Deposits ◽  
Geochemical Data ◽  
The Many

 This article presents the first detailed geochemical data of the water from Camaquã das Lavras and Hilário Streams from Lavras do Sul-RS. Geochemical and statistical analyses were used in this study to establish the anthropogenic or natural influence on the region. The results classified the waters as soft and intermediate with acidic and neutral pH. The electrical conductivity varies from 37.2 to 62.9 μs cm-1 and the total alkalinity ranges from 4 to 30 mgL-1. The distribution patterns and ratios indicate that clay mineral weathering is dominant on the investigated samples. It is followed by feldspar weathering in an environment under temporary hardness conditions. Cu, Rh, and Cd enrichment is associated with the many mineral deposits of the region, lithological diversity and human activities. All the measured values conform with the standards set by Brasil-Ordinance nos. 2914/2011, 36-GM/1990 and 1469/2000.

Depositional Environment Drive as Overpressure Generation: Study Case in “Gap” Field, North West Java Basin

2020 ◽  
Author(s):  
A., C. Prasetyo
Keyword(s):  
Clay Mineral ◽  
Depositional Environment ◽  
Mineral Content ◽  
Hydrocarbon Generation ◽  
Well Test ◽  
Burial History ◽  
The South ◽  
North West ◽  
The North ◽  
Geological Processes

Overpressure existence represents a geological hazard; therefore, an accurate pore pressure prediction is critical for well planning and drilling procedures, etc. Overpressure is a geological phenomenon usually generated by two mechanisms, loading (disequilibrium compaction) and unloading mechanisms (diagenesis and hydrocarbon generation) and they are all geological processes. This research was conducted based on analytical and descriptive methods integrated with well data including wireline log, laboratory test and well test data. This research was conducted based on quantitative estimate of pore pressures using the Eaton Method. The stages are determining shale intervals with GR logs, calculating vertical stress/overburden stress values, determining normal compaction trends, making cross plots of sonic logs against density logs, calculating geothermal gradients, analyzing hydrocarbon maturity, and calculating sedimentation rates with burial history. The research conducted an analysis method on the distribution of clay mineral composition to determine depositional environment and its relationship to overpressure. The wells include GAP-01, GAP-02, GAP-03, and GAP-04 which has an overpressure zone range at depth 8501-10988 ft. The pressure value within the 4 wells has a range between 4358-7451 Psi. Overpressure mechanism in the GAP field is caused by non-loading mechanism (clay mineral diagenesis and hydrocarbon maturation). Overpressure distribution is controlled by its stratigraphy. Therefore, it is possible overpressure is spread quite broadly, especially in the low morphology of the “GAP” Field. This relates to the delta depositional environment with thick shale. Based on clay minerals distribution, the northern part (GAP 02 & 03) has more clay mineral content compared to the south and this can be interpreted increasingly towards sea (low energy regime) and facies turned into pro-delta. Overpressure might be found shallower in the north than the south due to higher clay mineral content present to the north.

scholarly journals Sedimentology and geochemistry of Middle–Upper Permian in northwestern Turpan–Hami Basin, China: Implication for depositional environments and petroleum geology

2018 ◽  
Vol 36 (4) ◽  
pp. 910-941
Author(s):  
Jian Song ◽  
Zhidong Bao ◽  
Xingmin Zhao ◽  
Yinshan Gao ◽  
Xinmin Song ◽  
...  
Keyword(s):  
Depositional Environment ◽  
Saline Water ◽  
Depositional Environments ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Upper Permian ◽  
Late Permian ◽  
Humid Climate ◽  
Mountain Area ◽  
Volcanic Source

Studies have found that the Permian is another important stratum for petroleum exploration except the Jurassic coal measures within Turpan–Hami Basin recently. However, the knowledge of the depositional environments and its petroleum geological significances during the Middle–Late Permian is still limited. Based on the analysis about the sedimentological features of the outcrop and the geochemical characteristics of mudstones from the Middle Permian Taerlang Formation and Upper Permian Quanzijie Formation in the Taoshuyuanzi profile, northwest Turpan–Hami Basin, this paper makes a detailed discussion on the Middle–Late Permian paleoenvironment and its petroleum geological significances. The Middle–Upper Permian delta–lacustrine depositional system was characterized by complex vertical lithofacies assemblages, which were primarily influenced by tectonism and frequent lake-level variations in this area. The Taerlang Formation showed a significant lake transgression trend, whereas the regressive trend of the Quanzijie Formation was relatively weaker. The provenance of Taerlang and Quanzijie Formations was derived from the rift shoulder (Bogda Mountain area now) to the north and might be composed of a mixture of andesite and felsic volcanic source rocks. The Lower Taerlang Formation was deposited in a relatively hot–dry climate, whereas the Upper Taerlang and Quanzijie Formations were deposited in a relatively humid climate. During the Middle–Late Permian, this area belonged to an overall semi-saline water depositional environment. The paleosalinity values showed stepwise decreases from the Lower Taerlang Formation to the Upper Quanzijie Formation, which was influenced by the changes of paleoclimate in this region. During the Middle–Late Permian, the study area was in an overall anoxic depositional environment. The paleoenvironment with humid climate, lower paleosalinity, anoxic condition, and semi-deep to deep water during the deposition of the Upper Taerlang Formation was suitable for the accumulation of mudstones with higher TOC values.

scholarly journals Facies Analysis and Depositoinal Environment of D-3 Reservoir Sands Vin Field, Eastern Niger Delta

2019 ◽  
pp. 1-19
Author(s):  
Onyewuchi, Chinedu Vin ◽  
Minapuye, I. Odigi
Keyword(s):  
Seismic Data ◽  
Niger Delta ◽  
Depositional Environment ◽  
Gamma Ray ◽  
Facies Analysis ◽  
Depositional Environments ◽  
Width Ratio ◽  
Neutron Density ◽  
Wireline Logs ◽  
Isopach Map

Facies analysis and depositional environment identification of the Vin field was evaluated through the integration and comparison of results from wireline logs, core analysis, seismic data, ditch cutting samples and petrophysical parameters. Well log suites from 22 wells comprising gamma ray, resistivity, neutron, density, seismic data, and ditch cutting samples were obtained and analyzed. Prediction of depositional environment was made through the usage of wireline log shapes of facies combined with result from cores and ditch cuttings sample description. The aims of this study were to identify the facies and depositional environments of the D-3 reservoir sand in the Vin field. Two sets of correlations were made on the E-W trend to validate the reservoir top and base while the isopach map was used to establish the reservoir continuity. Facies analysis was carried out to identify the various depositional environments. The result showed that the reservoir is an elongate , four way dip closed roll over anticline associated with an E-W trending growth fault and contains two structural high separated by a saddle. The offshore bar unit is an elongate sand body with length: width ratio of >3:1 and is aligned parallel to the coast-line. Analysis of the gamma ray logs indicated that four log facies were recognized in all the wells used for the study. These include: Funnel-shaped (coarsening upward sequences), bell-shaped or fining upward sequences, the bow shape and irregular shape. Based on these categories of facies, the depositional environments were interpreted as deltaic distributaries, regressive barrier bars, reworked offshore bars and shallow marine. Analysis of the wireline logs and their core/ditch cuttings description has led to the conclusion that the reservoir sandstones of the Agbada Formation in the Vin field of the eastern Niger Delta is predominantly marine deltaic sequence, strongly influenced by clastic output from the Niger Delta. Deposition occurred in a variety of littoral and neritic environment ranging from barrier sand complex to fully marine outer shelf mudstones.

scholarly journals Stratigraphy and Depositional Environment of Mauddud Formation in Ratawi Oil wells of Southern Iraq

2021 ◽  
Vol 877 (1) ◽  
pp. 012030
Author(s):  
Maha Razaq Manhi ◽  
Hamid Ali Ahmed Alsultani
Keyword(s):  
Deep Sea ◽  
Lower Cretaceous ◽  
Depositional Environment ◽  
Carbonate Platform ◽  
Depositional Environments ◽  
Oil Wells ◽  
Oil Field ◽  
Microfacies Analysis ◽  
Thin Sections ◽  
Southern Iraq

Abstract The Mauddud Formation is Iraq’s most significant and widely distributed Lower Cretaceous formation. This Formation has been investigated at a well-23 and a well-6 within Ratawi oil field southern Iraq. In this work, 75 thin sections were produced and examined. The Mauddud Formation was deposited in a variety of environments within the carbonate platform. According to microfacies analysis studying of the Mauddud Formation contains of twelve microfacies, this microfacies Mudstone to wackestone microfacies, bioclastic mudstone to wackestone microfacies, Miliolids wackestone microfacies,Orbitolina wackestone microfacies, Bioclastic wackestone microfacies, Orbitolina packstone microfacies, Peloidal packstone microfacies, Bioclastic packstone microfacies, Peloidal to Bioclastic packstone microfacies, Bioclastic grainstone microfacies, Peloidal grainstone microfacies, Rudstone microfacies. Deep sea, Shallow open marine, Restricted, Rudist Biostrome, Mid – Ramp, and Shoals are the six depositional environments in the Mauddud Formation based on these microfacies.

scholarly journals Paleontological rescue, depositional environment, and stratigraphic correlation of a section of the Ponta Grossa Formation (Paraná Basin)

Terr Plural ◽  
2021 ◽  
Vol 15 ◽  
pp. e2119456
Author(s):  
Elvio Pinto Bosetti ◽  
◽  
Lucinei Jose Myszynski Junior ◽  
Daniel Sedorko ◽  
Luana Oliveira ◽  
...  
Keyword(s):  
High Frequency ◽  
Depositional Environment ◽  
Depositional Environments ◽  
Integrated Analysis ◽  
Stratigraphic Correlation ◽  
Paleontological Heritage ◽  
Paraná Basin ◽  
Specialized Team ◽  
Parana Basin ◽  
The City

The urban area of Ponta Grossa (PR) occurs on one of the most abundant fossiliferous fields in the country, which records an endemic fauna that occurred in the Devonian of the Paraná Basin. The growing urbanization of the city increasingly buries these outcrops, and new works must be accompanied by a specialized team to safeguard the paleontological heritage. This is the case of the Bosque Mistral project, which exposed many layers of the Ponta Grossa Formation, rich in fossils and trace fossils. This study reports the main fossiliferous occurrences in the section, correlates the section with classical outcrops from the literature, and interprets the main depositional environments as well stratigraphic cycles using an integrated analysis of sedimentology and ichnology. The ichnological distribution also evidences the retrogradation pattern, and, particularly, the occurrence of ichnofabrics dominated by Zoophycos at the top of the section is a signature of high-frequency cycles associated with the transgressive systems tract. Macrofossill biodiversity varies according to the facies, in the sandy and silty layers different organisms from the muddy layers occur. In the former, the epibiont fauna (mainly trilobites and brachiopods) is predominant while in the muddy layers the predominance is the endobiont and semi-endobiont fauna (bivalve mollusks and infaunal brachiopods). In other words, the distribution of taxa across the layers is not random.

scholarly journals Impact of Climate on Vegetation Change in a Mountain Grassland – Succession and Fluctuation

2014 ◽  
Vol 42 (2) ◽  
pp. 347-356 ◽  
Author(s):  
Florin PĂCURAR ◽  
Ioan ROTAR ◽  
Albert REIF ◽  
Roxana VIDICAN ◽  
Vlad STOIAN ◽  
...  
Keyword(s):  
Vegetation Change ◽  
Compositional Data ◽  
Classification Tree ◽  
Vegetation Period ◽  
Early Years ◽  
Permanent Plots ◽  
Climate Variables ◽  
Vegetation Composition ◽  
Climatic Fluctuations ◽  
Climate Conditions

Traditionally managed Central European mountain grasslands have high nature conservation value because of their high species diversity. Whether these grasslands and their diversity can be preserved will depend on many factors, including how plant species composition responds to changes in climate conditions. To differentiate between fluctuations and directional succession in the herbaceous layer composition of a Romanian Festuca rubra L. and Agrostis capillaris L. grassland in Apuseni and whether any compositional changes can be related to climate. The vegetation of permanent plots was recorded annually between 2004 and 2012. Temperature and precipitation were measured by an automatic weather station at the study site. Cluster analysis, Indicator Species Analysis and the co-dominance ratio between F. rubra L.- A. capillaris were analysed. The compositional data was related to the climate variables. Thresholds of relevant climate variables differentiating between clusters of plots with similar vegetation composition were determined using classification tree methods. The vegetation composition in our plots within the years 2004, 2005 and 2008 were different from each other. From 2004 to 2006 directional succession could be identified; however the major patterns to emerge were fluctuations which occurred over the whole study period. Compositional shifts included A. capillaris L. and F. rubra L exchanging co-dominance with each other. The most important variables differentiating clusters were temperature during the dormant and vegetation periods and water balance during the vegetation period. It can be concluded that compositional shifts among years were largely a consequence of year to year climatic fluctuations; however, there is some evidence for a directional shift during the early years of the study./span>

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