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Comparison Between Walkley-Black and Loss On Ignition Methods for Organic Matter Estimation in Different Moroccan Soils

El Mouridi Zineb, Ziri Rabea, Douaik Ahmed, Bennani Sahar, Lembaid Ibtissame, Bouharou Loubna, Brhadda Najiba, Moussadek Rachid

Ecological Engineering & Environmental Technology

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2023

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Vol. 24, iss. 4

253--259

EN

The present study aims to compare two different methods for the determination of soil organic matter (SOM); the wet acidified dichromate oxidation methods Walkley-Black (WB) and the combustion’s one (mass loss on ignition – LOI); in order to find out the best one in terms of suitability, environmentally-friendly, time-efficiency and economical benefit. Forty-five Moroccan soil samples (El Guich, Koudia and Merchouche area) from 0–20 cm depth with different classes, textures and organic matter contents were evaluated. According to the results, a strong linear relationship was observed between LOI-OM and WB-OM methods for all the sites. However, El Guich and Koudia recorded much larger regression coefficients (0.745*** and 0.611*** respectively) compared to Merchouche site (0.452**). Therefore, the SOM by walkley-Black method can be easily calculated from the LOI method at 500±25 ºC for 2 hours using linear equation in order to minimize the analysis time and consumption of chemicals for routine laboratory. In addition, it was noticed that the SOM contents calculated by the LOI method are higher in Merchouche soils compared to that of WB due to the presence of a large amount of clay minerals in the Merchouche soils (43.9 < %clay < 56.1) in comparison with those of El Guich (5 < %clay < 7.5) and Koudia (16.1 < %clay < 20.4). This study revealed that both methods were reliable but W.B method was more accurate and suitable for calcareous soils and those with high clay contents. However, LOI method is an accurate and beneficial for non-calcareous soils with low clay content.

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Marine vs. terrestrial environments during Early Triassic deposition on the northeastern margin of the Central European Basin : a multidisciplinary study on the Middle Buntsandstein of the Bartoszyce IG 1 borehole, NE Poland

Becker Anna, Fijałkowska-Mader Anna, Jasionowski Marek

Geological Quarterly

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2020

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Vol. 64, No. 4

1023--1047

EN

The Middle Buntsandstein Subgroup of the Lower Triassic of north-eastern Poland has been investigated in the context of possible marine ingressions into the Central European Basin. To better constrain these, palynofacies analysis and mineralogical analysis of mudstones were undertaken on samples taken from the Lidzbark and Malbork formations penetrated by the Bartoszyce IG 1 borehole, serving as stratotype section of both lithostratigraphic units. Microfacies and geochemical analyses, including C and O isotope analysis, were conducted additionally on oolitic limestones of the basal Lidzbark Formation (the lowermost Middle Buntsandstein), and the boron content was measured on all mudstone samples. Seven palynofacies types are distinguished: types 1 to 3 within the Malbork Formation and types 4 to 7 within the Lidzbark Formation. Types 1 and 2 originated on a floodplain, type 3 probably in a deltaic or barrier setting, and types 4 and 5 in a brackish lagoon or a more open basin, possibly of marine origin. Palynofacies type 6 reflects long transport and reworking, whereas palynofacies type 7 is interpreted as formed due to pedogenic processes. Clay minerals and quartz, accompanied by feldspars, calcite and dolomite are the main components of the mudstones investigated. The clay mineral association consists of illite or a mixture of illite and smectite, and chlorite. The Lidzbark Formation and the lowermost part of the Malbork Formation show less variability in mineralogical composition than the upper part of the Malbork Formation. Smectite admixtures were detected only in the upper part of the Malbork Formation (the uppermost Middle Buntsandstein). The boron content, achieved after aqua regia digestion, ranges from 70 to 121 mg/kg (96 mg/kg at average), oscillating generally around 90 mg/kg. A higher boron content, bound in silicate structure, is associated with the upper part of the Malbork Formation. All major mineralogical and geochemical changes coincide more or less with the transition from the supposed marine to the terrestrial environmental realm, interpreted from lithological and sedimentological observations within the lowermost part of the Malbork Formation. However, diagenetic alteration of the clay minerals, and of the boron content, could not be ruled out. The oolitic limestones, mainly grainstones, contain admixtures of quartz grains and rare bioclasts, the ooids nuclei being peloids or unrecognizable. The carbonates are almost exclusively composed of low-Mg calcite. A high content of Mg and the presence of small amounts of dolomite suggest that the ooids were primarily composed of high-Mg calcite and are comparable with similar Early Triassic deposits in Tethyan settings. The δ13C values range from -2 to +1‰ VPDB, fitting well with the known ranges of Lower Triassic marine carbonates. An observed δ13C depletion towards the top of the oolite-bearing part of the section may reflect a local shallowing trend that led to overall salinity decrease. A possible connection with the one of the global oceanic geochemical episodes has to be tested further. The results obtained suggest a marine origin of the lower Middle Buntsandstein deposits studied and document a terrestrial origin for the upper Malbork Formation.

3

Climate change at the Triassic/Jurassic boundary in the northwestern Tethyan realm, inferred from sections in the Tatra Mountains (Slovakia)

Michalik J., Biron A., Lintnerova O., Gotz A., Ruckwied K.

Acta Geologica Polonica

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2010

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Vol. 60, no. 4

535-548

EN

Sedimentological, palynological, clay mineralogical and carbon isotope studies were carried out on the Triassic/Jurassic (T/J) boundary interval in the NW Tethyan Realm. The analyses are based on two sections in the Slovakian Tatra Mountains (Western Carpathians): the Siroky Zl'ab section in the Med'odoly Valley and the Furkaska section above the Juranova Valley. Clay mineralogical analysis suggests an increasing intensity of chemical weathering in the hinterland due to increasing humidity. The palynological data do not allow the inference of a major T/J boundary mass extinction event. The observed striking increase in spores points instead to sudden climatic change, interpreted as a result of distant volcanic activity associated with the onset of rifting of Pangea. The [delta^13]C[org] excursion across the T/J boundary follows the globally documented perturbation of the carbon cycle during this period. it may be used for a more precise regional and global correlation.

4

Palynology, T/J boundary microfacies, clay mineralogy, C and O isotopes and other palaeoclimatic indicators from the Tatra Mts.

Götz A., Ruckwied K., Biroń A., Lintnerová O., Michalík J.

Volumina Jurassica

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2006

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Vol. 4, no. 1

282-283

EN

The Furkaska and Kardolina sections expose a complete succesion of the uppermost Fatra Formation and the lowermost Kopienec Formation. The Upper Triassic Fatra Fm. is characterized by bioclastic limestones and fine-grained clastics overlain by dark claystones with intercalated sandstones (Cardinia Sandstein) of the Kopienec Formation. Due to lack of age-diagnostic index fossils, the precise position of the Triassic/Jurassic boundary is not yet known. Based on negative excursion of the δ ¹ ³C carbonate isotopic curve and microfacies analyses the boundary interval was placed near the transition of two formations. Palynological analysis was focused on palaeoenvironmental and stratigraphical aspects. Generally, the continental fraction shows a high amount of phytoclasts. The few marine organic depositional environment indicate a very shallow marine depositional environment. The palynomorph assemblage of the Fatra Fm. is characterized by numerous Ricciisporites tuberculatus. The marine fraction of this part of the sections is dominated by dinoflagellate cyst Rhaetogonyaulax rhaetica. Microflora of the Upper Fatra Formation is very similar to the Ricciisporites tuberculatus Zone of the Polish zonation and Ricciisporites-Polzdiisporites Zone of the SE Nord Sea Basin, both indicating a Middle to Late Rhaetian age. The palynomorph assemblage of the Kopienec Formation is characterized by a significant increase of trilete laevigate spores, mainly Deltoidospora spp. and Concavisporites spp. The dinoflagellate cyst Dapcodinium priscum replaces Rhaetogonyaulax rhaetica in the marine fraction. These changes may be caused by a regression at the Triassic/Jurassic boundary. Quantitative clay minerals analyses documented palaeoclimatic, palaeogeographic and postsedimentary changes in the boundary event and integrated palynological results. Mixed layer illite/smectite (I/S) smectite interlayers take about 80% of the clay fraction and their low content of smectite (10-20%) indicate relatively high diagenetic overprint of the Fatra and Kopienec formations claystones corresponding with burial temperature of 150oC. Varied contents of detrital illite, chlorite and kaolinite were used to demonstrate climatic changes in the hinterland and indicated depositional condition in this semi-restricted basin. Kaolinite and low illite/kaolinite ration indicate more humid climate during earliest Jurassic in comparison with the Rhaetian condition of illite/chlorite dominance. Peak occurrence of kaolinite at the base of the Kopienec Formation recorded different source and strong input of material from weathered and eroded land into proximal part of deltaic plain in comparison with the Fatra Formation.

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Palaeoenvironmental interpretation of dinosaur- and mammal-bearing continental Maastrichtian deposits, Hateg basin, Romania

Bojar A. V., Grigorescu D., Ottner F., Csiki Z.

Geological Quarterly

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2005

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Vol. 49, No. 2

205--222

EN

The Hateg basin, South Carpathians, Romania, contains a thick sequence of Maastrichtian continental deposits from which a rich dinosaur and mammal fauna is known. Field data as well as mineralogical and stable isotope analyses from three representative profiles were integrated in order to reconstruct environmental conditions during Maastrichtian time. Tustea quarry is characterized by the presence of well drained calcisols, with smectite (montmorillonite) as the main clay component. Along the profile, the δ18 O and δ13 C isotopic compositions of calcretes show a small variation, of up to 0.9‰. The profile along the Barbat Valley shows preponderantly calcisols, the main clay mineral being smectite, with subordinate illite and chlorite. The oxygen isotopic compositions of calcretes are ~0.5‰ lighter than those from Tustea. The soils are interpreted as having formed under more humid conditions and they are similar to those situated at the bottom of the sequence developed along Sibisel Valley. The abundant smectite from the Tustea and Barbat Valley depos its, as well the presence of good developed soils, reflects palaeoenvironmental conditions predominantly controlled by climate. Preliminary magnetostratigraphic data along the Sibisel Valley section indicate that sedimentation started at the end of chron C32n. All other palaeomagnetic sites distributed up stream, as far as the upper limit of this formation, have only reversed polarity and the corresponding time interval is probably chron C31r. Along this valley, the sequence shows a general coarsening upward trend. The palaeosol type changes from calcisol- to vertisol-dominated sequences. The soils are moderate to weakly developed. The mineralogical composition of the clay fraction also changes, from smectite- to illite and chlorite-dominated. These features points to wards unstable tectonic conditions and higher uplift rates of the surrounding area within chron C31r. To wards the top of the sequence, the oxygen and carbon isotopic composition of calcretes be come 1 and ~2‰ lighter, respectively. These changes indicate a transition from generally semi-arid to wards more humid and possible cooler conditions and correlate with the world wide trend for chron 31r.