PALEOENVIRONMENTAL ANALYSIS OF A LOWER CRETACEOUS PALEOLAKE FROM THE IGUATU BASIN BASED ON ITS OSTRACOD FAUNA AND XRF DATA

ABSTRACT This paper presents the results of a paleoenvironmental study of two Hauterivian–Aptian adjacent sections (Transnordestina A/B) of the Iguatu Basin using ostracods and aided by X-ray fluorescence (XRF), total organic carbon (TOC), total sulfur (S), and spectral analyses. Cluster analysis divided the 10 genera found into two main groups: one composed of Alicenula-Pattersoncypris?-Brasacypris-Hastacypris-Ilyocypris?, and the second composed of Cypridea-Looneyellopsis-Rhinocypris?. The first group is interpreted as representing paleoenvironments with permanent waterbodies, such as lakes, and the second as being indicative of ephemeral settings, such as temporary pools in an inundation plain. XRF analysis using the positive peaks of Ca/Ti and Ca/ΣTi, Fe, Al ratios show a few dry periods, particularly in the lower and middle part of Transnordestina A, between 0 to 175 m and 385 to 475 m, which also display a small number of ostracods. Total S shows several high peaks which might be indicative of gypsum deposition during droughts. Spectral analysis of molar Ti/Al ratio shows two intervals with different sedimentation rates, between 0 and 233 m, and 233 to 836 m. For the first interval, six 100 ka eccentricity cycles were identified; the low number of ostracods for the interval and highly variable Ca/Ti and Ca/ΣTi, Fe, Al values indicate a different sedimentation rate in a drier environment. For the second interval, ten 405 ka cycles were identified; its higher ostracod count and more stable Ca/Ti and Ca/ΣTi, Fe, Al values could be indicative of increasing humidity.

Download Full-text

Application of bioinformatics to spectral analysis: soil organic carbon structure distinguished by X-ray photoelectron spectroscopy

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-019-01750-0 ◽

2019 ◽

Vol 411 (12) ◽

pp. 2481-2485 ◽

Cited By ~ 1

Author(s):

Tongyan Yao ◽

Ruirui Chen ◽

Youzhi Feng ◽

Xiangui Lin

Keyword(s):

Spectral Analysis ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Photoelectron Spectroscopy ◽

Carbon Structure ◽

X Ray

Download Full-text

Quantification of tantalum sedimentation rates in liquid embolic agents

Interventional Neuroradiology ◽

10.1177/1591019918773443 ◽

2018 ◽

Vol 24 (5) ◽

pp. 574-579 ◽

Cited By ~ 4

Author(s):

JR Mason ◽

C Dodge ◽

G Benndorf

Keyword(s):

Sedimentation Rate ◽

Arteriovenous Malformations ◽

Sedimentation Rates ◽

Signal To Noise ◽

X Ray ◽

Time Points ◽

Embolic Agents ◽

Covalently Bonded ◽

Liquid Embolic ◽

Over Time

Background Endovascular treatment (EVT) of brain arteriovenous malformations has evolved from cyanoacrylate derivatives such as N-butyl cyanoacrylate, an adhesive glue, to ethylene vinyl copolymer-based liquid embolics such as Onyx® and SQUID® dissolved in dimethyl sulfoxide. Although these agents offer several advantages, their rapidly decreasing radiopacity, as a result of the sedimentation of tantalum powder, compromises visual control during EVT. This study aims to quantify and compare tantalum sedimentation rates of several liquid embolic agents, and determine their effects on radiopacity. Methods The rate of sedimentation of liquid embolics Onyx 18®, SQUID 12®, and SQUID 18® was measured after preparation by single x-ray exposures for a period of 30 minutes. The signal-to-noise ratios (SNRs) of the suspension of each liquid embolic was calculated at various time points as tantalum settled out of the suspension. Precipitating Hydrophobic Injectable Liquid (PHIL®) was imaged as a control. Results Onyx 18® demonstrated the fastest sedimentation rate of the liquid embolics analyzed and demonstrated a threefold faster drop in SNR compared to SQUID 18® over 30 minutes. Onyx 18® demonstrated a one and a half times faster drop in SNR compared to SQUID 12®. Although PHIL 25® maintained constant SNR over the same time, it was lower at baseline immediately after preparation compared to tantalum-based liquids. Conclusion Caution during long injections using tantalum-based agents is advised. Onyx 18® has a significantly faster drop in radiopacity compared to SQUID 12® and SQUID 18®. Covalently bonded iodine-based embolics like PHIL® demonstrate constant radiopacity over time.

Download Full-text

Milankovitch Cycles in Upper Jurassic and Lower Cretaceous Radiolarites of the Equatorial Pacific: Spectral Analysis and Sedimentation Rate Curves

10.2973/odp.proc.sr.129.142.1992 ◽

1992 ◽

Cited By ~ 4

Author(s):

A.J. Molinie ◽

J.G. Ogg

Keyword(s):

Spectral Analysis ◽

Sedimentation Rate ◽

Lower Cretaceous ◽

Upper Jurassic ◽

Equatorial Pacific ◽

Milankovitch Cycles

Download Full-text

Short-range vertical variation in organic carbon, carbonate carbon, total sulfur contents and Munsell color values in a core from the Upper Pennsylvanian Stark Shale Member of the Dennis Limestone, Wabaunsee County, Kansas

Open-File Report ◽

10.3133/ofr83315 ◽

1983 ◽

Cited By ~ 3

Author(s):

M.R. Stanton ◽

Joel S. Leventhal ◽

Joseph R. Hatch

Keyword(s):

Organic Carbon ◽

Short Range ◽

Total Sulfur ◽

Vertical Variation ◽

Carbonate Carbon

Download Full-text

Power Density Spectral analysis as a Method of Compact Object Determination in X-ray Binary Systems

10.2172/800021 ◽

2002 ◽

Author(s):

John R Lee

Keyword(s):

Spectral Analysis ◽

Power Density ◽

Binary Systems ◽

Compact Object ◽

X Ray

Download Full-text

Total organic carbon and the preservation of organic-walled microfossils in Precambrian shale

Geology ◽

10.1130/g48116.1 ◽

2020 ◽

Author(s):

C.R. Woltz ◽

S.M. Porter ◽

H. Agić ◽

C.M. Dehler ◽

C.K. Junium ◽

...

Keyword(s):

Species Richness ◽

Organic Carbon ◽

Total Organic Carbon ◽

Microbial Degradation ◽

Sedimentation Rate ◽

Surface Pattern ◽

Causal Factors ◽

Eukaryotic Diversity ◽

High Concentrations ◽

Fossil Preservation

Much of our understanding of early eukaryote diversity and paleoecology comes from the record of organic-walled microfossils in shale, yet the conditions controlling their preservation are not well understood. It has been suggested that high concentrations of total organic carbon (TOC) inhibit the preservation of organic fossils in shale, and although this idea is supported anecdotally, it has never been tested. Here we compared the presence, preservational quality, and assemblage diversity of organic-walled microfossils to TOC concentrations of 346 shale samples that span the late Paleoproterozoic to middle Neoproterozoic in age. We found that fossil-bearing samples have significantly lower median TOC values (0.32 wt%, n = 189) than those containing no fossils (0.72 wt%, n = 157). Preservational quality, measured by the loss of surface pattern, density of pitting, and deterioration of wall margin, decreases as TOC increases. Species richness negatively correlates with TOC within the ca. 750 Ma Chuar Group (Arizona, USA), but no relationship is observed in other units. These results support the hypothesis that high TOC content either decreases the preservational quality or inhibits the preservation of organic-walled microfossils altogether. However, it is also possible that other causal factors, including sedimentation rate and microbial degradation, account for the correlation between fossil preservation and TOC. We expect that as TOC varies in space and time, so too does the probability of finding well-preserved fossils. A compilation of 13,940 TOC values spanning Earth history suggests significantly higher median TOC levels in Mesoproterozoic versus Neoproterozoic shale, potentially biasing the interpreted pattern of increased eukaryotic diversity in the Tonian.

Download Full-text

Estimation of Wear Resistance for Multilayer Coatings Obtained by Nitrogenchroming

Metals ◽

10.3390/met11081153 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1153

Author(s):

Ivan Pavlenko ◽

Jozef Zajac ◽

Nadiia Kharchenko ◽

Ján Duplák ◽

Vitalii Ivanov ◽

...

Keyword(s):

Wear Resistance ◽

Spectral Analysis ◽

Friction Coefficient ◽

Cutting Tools ◽

Wear Intensity ◽

Maximum Amount ◽

Multilayer Coatings ◽

Wear Depth ◽

X Ray ◽

Machine Parts

This article deals with improving the wear resistance of multilayer coatings as a fundamental problem in metal surface treatment, strengthening elements of cutting tools, and ensuring the reliability of machine parts. It aims to evaluate the wear depth for multilayer coatings by the mass loss distribution in layers. The article’s primary purpose is to develop a mathematical method for assessing the value of wear for multilayer steel-based coatings. The study material is a multilayer coating applied to steel DIN C80W1. The research was performed using up-to-date laboratory equipment. Nitrogenchroming has been realized under overpressure in two successive stages: nitriding for 36 h at temperature 540 °C and chromizing during 4 h at temperature 1050 °C. The complex analysis included several options: X-ray phase analysis, local micro-X-ray spectral analysis, durometric analysis, and determination of wear resistance. These analyses showed that after nitrogenchroming, the three-layer protective coating from Cr23C6, Cr7C3, and Cr2N was formed on the steel surface. Spectral analysis indicated that the maximum amount of chromium 92.2% is in the first layer from Cr23C6. The maximum amount of carbon 8.9% characterizes the layer from Cr7C3. Nitrogen is concentrated mainly in the Cr2N layer, and its maximum amount is 9.4%. Additionally, it was determined that the minimum wear is typical for steel DIN C80W1 after nitrogenchroming. The weight loss of steel samples by 25 mg was obtained. This value differs by 3.6% from the results evaluated analytically using the developed mathematical model of wear of multilayer coatings after complex metallization of steel DIN C80W1. As a result, the impact of the loading mode on the wear intensity of steel was established. As the loading time increases, the friction coefficient of the coated samples decreases. Among the studied samples, plates from steel DIN C80W1 have the lowest friction coefficient after nitrogenchroming. Additionally, a linear dependence of the mass losses on the wearing time was obtained for carbide and nitride coatings. Finally, an increase in loading time leads to an increase in the wear intensity of steels after nitrogenchroming. The achieved scientific results are applicable in developing methods of chemical-thermal treatment, improving the wear resistance of multilayer coatings, and strengthening highly loaded machine parts and cutting tools.

Download Full-text

First Report on the Geologic Occurrence of Natural Na–A Zeolite and Associated Minerals in Cretaceous Mudstones of the Paja Formation of Vélez (Santander), Colombia

Crystals ◽

10.3390/cryst11020218 ◽

2021 ◽

Vol 11 (2) ◽

pp. 218

Author(s):

Carlos Alberto Ríos-Reyes ◽

German Alfonso Reyes-Mendoza ◽

José Antonio Henao-Martínez ◽

Craig Williams ◽

Alan Dyer

Keyword(s):

Natural Zeolite ◽

Scanning Electron Micrographs ◽

Total Sulfur ◽

Zeolite A ◽

X Ray Diffraction ◽

X Ray ◽

Mineral Phases ◽

The World ◽

Porosity And Permeability ◽

First Time

This study reports for the first time the geologic occurrence of natural zeolite A and associated minerals in mudstones from the Cretaceous Paja Formation in the urban area of the municipality of Vélez (Santander), Colombia. These rocks are mainly composed of quartz, muscovite, pyrophyllite, kaolinite and chlorite group minerals, framboidal and cubic pyrite, as well as marcasite, with minor feldspar, sulphates, and phosphates. Total organic carbon (TOC), total sulfur (TS), and millimeter fragments of algae are high, whereas few centimeters and not biodiverse small ammonite fossils, and other allochemical components are subordinated. Na–A zeolite and associated mineral phases as sodalite occur just beside the interparticle micropores (honeycomb from framboidal, cube molds, and amorphous cavities). It is facilitated by petrophysical properties alterations, due to processes of high diagenesis, temperatures up to 80–100 °C, with weathering contributions, which increase the porosity and permeability, as well as the transmissivity (fluid flow), allowing the geochemistry remobilization and/or recrystallization of pre-existing silica, muscovite, kaolinite minerals group, salts, carbonates, oxides and peroxides. X-ray diffraction analyses reveal the mineral composition of the mudstones and scanning electron micrographs show the typical cubic morphology of Na–A zeolite of approximately 0.45 mμ in particle size. Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → sodalite → Na–A zeolite. A literature review shows that this is an unusual example of the occurrence of natural zeolites in sedimentary marine rocks recognized around the world.

Download Full-text

The determination of sedimentation rates in Lake Ontario using the 210Pb dating method

Canadian Journal of Earth Sciences ◽

10.1139/e78-047 ◽

1978 ◽

Vol 15 (3) ◽

pp. 431-437 ◽

Cited By ~ 33

Author(s):

John G. Farmer

Keyword(s):

Sedimentation Rate ◽

Lake Ontario ◽

Sedimentary Basins ◽

210Pb Dating ◽

Sedimentation Rates ◽

Surface Mixing ◽

Dating Method ◽

210Pb Dating Method

The 210Pb dating method has been applied successfully to the determination of recent sedimentation rates at four sites distributed among the three major sedimentary basins (Niagara, Mississauga and Rochester) of Lake Ontario. Following correction for effects due to compaction of the sediments, mean sedimentation rates ranging from 0.02 cm/year at the periphery of the Mississauga basin to 0.11 cm/year in the Niagara and Rochester basins were determined. Allowance for compaction reduced the non-compaction-corrected sedimentation rates by 20–35%. Neither 210Pb nor fallout 137Cs profiles indicated surface mixing of sediment sufficient to noticeably affect the calculated sedimentation rates. At all four sites, the sedimentation rate seems to have remained constant during the last 100–150 years.

Download Full-text