scholarly journals Upper Jurassic–Lower Cretaceous Source Rocks in the North of Western Siberia: Comprehensive Geochemical Characterization and Reconstruction of Paleo-Sedimentation Conditions

Geosciences ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 320
Author(s):  
Evgeniya Leushina ◽  
Timur Bulatov ◽  
Elena Kozlova ◽  
Ivan Panchenko ◽  
Andrey Voropaev ◽  
...  

The present work is devoted to geochemical studies of the Bazhenov Formation in the north of the West Siberian Petroleum Basin. The object is the Upper Jurassic–Lower Cretaceous section, characterized by significant variations in total organic carbon content and petroleum generation potential of organic matter at the beginning of the oil window. The manuscript presents the integration of isotopic and geochemical analyses aimed at the evaluation of the genesis of the rocks in the peripheral part of the Bazhenov Sea and reconstruction of paleoenvironments that controlled the accumulation of organic matter in sediments, its composition and diagenetic alterations. According to the obtained data, the sediments were accumulated under marine conditions with a generally moderate and periodically increasing terrigenous influx. The variations in organic matter composition are determined by redox conditions and terrigenous input which correlate with the eustatic sea level changes during transgressive/regressive cycles and activation of currents. Transgression is associated with an intensive accumulation of organic matter under anoxic to euxinic conditions and insignificant influence of terrigenous sources, resulting in the formation of rocks with oil-generating properties. During the regression periods, the terrigenous sedimentation increased along with the dissolved oxygen concentration, and deposits with low organic matter content and gas-generating properties were formed.

2021 ◽  
Vol 71 ◽  
pp. 125-138
Author(s):  
Fawzi M.O. Albeyati ◽  
◽  
Rzger A. Abdula ◽  
Rushdy S. Othman ◽  

Thirty four cuttings samples from the Jurassic rock succession in well Balad-1 in the Balad Oil Field, Central Iraq have been collected. Using various organic geochemical techniques, the organic matter’s quantity, quality, maturity, and their source rock’s depositional setting were determined. The samples were evaluated to determine the amount of their organic matter content, type of organic matter, δ13C carbon isotopes abundance for both saturated and aromatic, and molecular properties. The results of organic geochemistry analysis show that Sargelu, Gotnia, and Chia Gara formations contain fair to decent amounts of organic matter. Naokelekan Formation encompasses fair to excellent organic matter, while Najmah Formation comprises very high to exceptional organic matter. The analyzed samples revealed the existence of kerogen types III and II/III mainly within oil window. Thermal maturity related biomarkers are in a good agreement with Rock-Eval parameters, but did not reach equilibrium phase. Source related biomarkers show that these rock units rich in organic matter were mainly deposited in an anoxic marine depositional setting which consists of carbonate influenced by terrestrial input.


2006 ◽  
Vol 63 (2) ◽  
pp. 187-193 ◽  
Author(s):  
Marcos Gervasio Pereira ◽  
Gustavo Souza Valladares ◽  
Lúcia Helena Cunha dos Anjos ◽  
Vinícius de Melo Benites ◽  
Ademar Espíndula Jr. ◽  
...  

Soil taxonomy systems distinguish mineral soils from organic soils based on the amount of soil organic carbon. Procedures adopted in soil surveys for organic carbon measurement are therefore of major importance to classify the soils, and to correlate their properties with data from other studies. To evaluate different methods for measuring organic carbon and organic matter content in Histosols and soils with histic horizons, from different regions of Brazil, 53 soil samples were comparatively analyzed by the methods of Walkley & Black (modified), Embrapa, Yeomans & Bremner, modified Yeomans & Bremner, muffle furnace, and CHN. The modified Walkley & Black (C-W & B md) and the combustion of organic matter in the muffle furnace (OM-Muffle) were the most suitable for the samples with high organic carbon content. Based on regression analysis data, the OM-muffle may be estimated from C-W & B md by applying a factor that ranges from 2.00 to 2.19 with 95% of probability. The factor 2.10, the average value, is suggested to convert results obtained by these methods.


2018 ◽  
Vol 189 (2) ◽  
pp. 9 ◽  
Author(s):  
Maxime Debret ◽  
Yoann Copard ◽  
Antonin Van Exem ◽  
Geneviève Bessereau ◽  
Frank Haeseler ◽  
...  

Organic matter studies find an echo within different topics such as biogeochemical cycles, processes occurring in continental surfaces, anthropogenic activities, climate science, earth and planetary sciences, etc. Today’s challenges include finding and developing the most appropriate method(s) supporting the differentiation and characterisation of various types of recalcitrant organic matter in modern environments. In this study, we focus on combustion residues and coals as these two types of organic matter contain a significant amount of so-called recalcitrant organic carbon (black carbon and fossil organic carbon). Both these materials are ubiquitous, broadly stem from the same living organisms and have similar polyaromatic structures. In this respect, we tested a spectrophotometry method, classically used for sedimentology, as a very fast method for preliminary investigations. Analyses were performed with a wide range of standards and referenced samples. The results discriminate three different spectral signatures related to the degree of transformation of organic matter related to the degree of aromaticity (i.e. carbonisation). Using calibration curves, total organic carbon content can be estimated in experimental mixes with mineral matter and in a real context using subsurface sample (Gironville 101 borehole, Paris Basin, France). This method has particularly high sensitivity to very low organic matter content and is shown to be promising for a rapid evaluation of the organic carbon content.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Trevor K. James ◽  
Hossein Ghanizadeh ◽  
Kerry C. Harrington ◽  
Nanthi S. Bolan

AbstractThe persistence and degradation of two common herbicides, atrazine and bromacil in two organic media, wood pulp and sawdust were compared with two soils. The hypothesis tested was that herbicide degradation will be faster in high organic matter media compared to soil. Degradation of two herbicides was carried out in four different temperature regimes and in sterilised media. The degradation half-life (t½) was determined under above-mentioned conditions then compared to degradation in soil. The degradation as quantified by t½ of the herbicides was generally longer in both organic media. Although microbial degradation was an important factor in the mineralisation of these herbicides, overall, the pH of the media had a more profound effect on the desorption and subsequent degradation rate than the organic carbon content. The results of this study revealed that the hypothesis was only partially correct as organic matter content per se did not strongly relate to degradation rates which were mainly governed by pH and microbial activity.


PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0242980
Author(s):  
Tadeusz Paszko ◽  
Joanna Matysiak ◽  
Daniel Kamiński ◽  
Sylwia Pasieczna-Patkowska ◽  
Miłosz Huber ◽  
...  

The current laboratory adsorption study aimed at determination of the values of adsorption distribution coefficient (Kd) of bentazone in the profiles of Arenosols, Luvisols, and Cambisols, which are the most common arable mineral soils in Poland. The study attempted to identify the soil components that bind bentazone and the principal adsorption mechanisms of this compound as well as create a model capable of predicting its adsorption in soils. The Kd values determined in batch experiments after 24 h of shaking were very low, and ranged from 0.05 to 0.30 mL/g for the Ap horizon and 0 to 0.07 mL/g for subsoils. The results indicated that the anionic form of bentazone was adsorbed on organic matter, while in acidic soils the neutral form of bentazone was adsorbed on organic matter and sand. The detailed analyses of mineralogical composition revealed that the principal mineral that was responsible for the adsorption of bentazone was quartz, which content was strongly positively correlated with the sand fraction. In soils with pH < 5 and an organic carbon content of < 0.35%, quartz exhibited much greater affinity for the neutral bentazone form than organic matter. Fourier transform infrared photoacoustic spectroscopy analyses supported by computational methods have shown the most probable mechanisms behind the adsorption of bentazone on quartz. The created model, assuming the adsorption of bentazone on organic matter and on sand and using the spectrophotometrically determined dissociation constant of bentazone, very well explained the Kd variance in the 81 examined soils, while correctly predicting the adsorption based on soil properties described in the published data.


Geosciences ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 277
Author(s):  
Natalya Tanykova ◽  
Yuliya Petrova ◽  
Julia Kostina ◽  
Elena Kozlova ◽  
Evgenia Leushina ◽  
...  

The study of organic matter content and composition in source rocks using the methods of organic geochemistry is an important part of unconventional reservoir characterization. The aim of this work was the structural group analysis of organic matter directly in the source rock in combination with a quantitative assessment and surface distribution analysis of the rock sample by FTIR spectroscopy and FTIR microscopy. We have developed new experimental procedures for semi-quantitative assessment of the organic matter content, composition and distribution in the source rocks and applied these procedures for the study of the samples from the Bazhenov shale formation (West Siberia, Russia). The results have been verified using the data from the study of organic matter obtained by Rock-Eval pyrolysis and differential thermal analysis. The obtained results demonstrate the prospects of FTIR spectroscopy and FTIR microscopy application for non-destructive and express analysis of the chemical structure and distribution of organic matter in rocks.


1989 ◽  
Vol 3 (1) ◽  
pp. 190-197 ◽  
Author(s):  
Patrick J. Shea

Organic matter is the soil constituent most often associated with herbicide adsorption. Structural diversity makes humified organic material an ideal substrate for the adsorption of many pesticides, but variability in composition and distribution in situ complicates interpretation of its quantitative effect on adsorption. Variability in the adsorption distribution coefficient (KD) of a herbicide among soils often is due to differences in organic matter content and can be reduced by adjusting KDfor soil organic carbon content and computing the organic carbon partition coefficient (Koc). Koccan be estimated from the octanol-water partition coefficient (Kow) of organic compounds, but the correlation weakens as compound polarity increases. Kocalso can be correlated with aqueous solubility if a correction is made for the melting point of compounds that are solids at 25 C. Relative adsorption can be estimated from parachor and molecular connectivity indices; but corrections are needed for polar compounds, and correlations with KDor Kochave been variable. Such predictive methods may be useful for broad classification purposes, but accurate extrapolation generally requires site-specific adsorption measurements. Empirical models which accommodate the multiple regression of organic matter content and other soil properties such as clay content, pH, and cation exchange capacity on herbicide adsorption can increase accuracy, but interpretation may be restricted to a small number of sites.


2020 ◽  
Vol 2020 ◽  
pp. 1-15 ◽  
Author(s):  
Junhui Luo ◽  
Yong Wu ◽  
Decai Mi ◽  
Qiongyao Ye ◽  
Haifeng Huang ◽  
...  

Carbonaceous rock is a special soft rock containing TOC organic carbon 6%∼40%. In order to reveal the influence of engineering characteristics of carbonaceous rock on the engineering construction, firstly the stratigraphic distribution of carbonaceous Rocks in Guangxi is investigated, and the genetic mechanism and tectonic environment of carbonaceous rocks are discussed. Secondly, the influence of pore microstructure on the disintegration characteristics of carbonaceous rocks is analyzed. The role of geochemical characteristics of carbonaceous rocks (mineral composition, TOC total organic matter content, and type) on engineering properties is revealed. Finally, combined with the distribution, structure, microstructure, and microscopic characteristics of the previous studies, the disintegration mechanism of carbonaceous rocks in water swelling and heat dehydration is discussed. The results are as follows. (1) Carbonaceous rocks in Guangxi are mainly distributed in Devonian, Carboniferous, and Cambrian systems. It is mainly formed in anoxic and reductive deep water basins, slopes, and relatively confined coastal lagoons and swamps. The carbonaceous rocks in the Devonian Luofu formation are most typical. (2) The pores of carbonaceous rocks are divided into mineral pores, organic matter pores, and microfracture, which are mainly mineral pores. The more developed pores in mineral pores are intragranular dissolved pores. Secondly, mineral intergranular pores and a small amount of intergranular dissolution pores and less inner pores. Organic matter porosity increases with the increase of shale organic carbon content and maturity, but the shale porosity and adsorption capacity decrease when shale maturity reaches more than 2.4%. (3) Clay minerals in carbonaceous shale mainly consist of illite and illite/montmorillonite layer, which have water swelling and heat dehydration. The total average value of TOC (total organic matter content) is more than 1%, which belongs to carbonaceous rocks of medium high grade hydrocarbon source rocks. Organic matter is mainly dominated by type I and II1-II2 type with large hydrocarbon generating potential, which is prone to oxidation-reduction reaction and cause rock disintegration.


2012 ◽  
Vol 9 (4) ◽  
pp. 1465-1478 ◽  
Author(s):  
E. S. Kritzberg ◽  
S. M. Ekström

Abstract. Browning of inland waters has been noted over large parts of the Northern hemisphere and is a phenomenon with both ecological and societal consequences. The increase in water color is generally ascribed to increasing concentrations of dissolved organic matter of terrestrial origin. However, oftentimes the increase in water color is larger than that of organic matter, implying that changes in the concentration of organic matter alone cannot explain the enhanced water color. Water color is known to be affected also by the quality of organic matter and the prevalence of iron. Here we investigated trends in water color, organic matter and iron between 1972 and 2010 in 30 rivers draining into the Swedish coast (data from the national Swedish monitoring program), and performed a laboratory iron addition experiment to natural waters, to evaluate the role of iron and organic matter in determining water color. By comparing the effect of iron additions on water color in the experiment, to variation in water color and iron concentration in the monitoring data, we show that iron can explain a significant share of the variation in water color (on average 25 %), especially in the rivers in the north of Sweden (up to 74 %). Furthermore, positive trends for iron are seen in 27 of 30 rivers (21–468 %) and the increase in iron is larger than that of organic matter, indicating that iron and organic matter concentrations are controlled by similar but not identical processes. We speculate that increasing iron concentrations can be caused by changes in redox conditions, that mean that more anoxic water with high concentrations of soluble FeII are feeding into the surface waters. More studies are needed about why iron is increasing so strongly, since both causes and consequences are partly different from those of increasing organic matter content.


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