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Wyszukujesz frazę "Isotopes" wg kryterium: Temat


Tytuł:
Why are variations in bromine isotope compositions in the Earths history larger than chlorine isotope compositions?
Autorzy:
Eggenkamp, Hans
Powiązania:
https://bibliotekanauki.pl/articles/763372.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet Marii Curie-Skłodowskiej. Wydawnictwo Uniwersytetu Marii Curie-Skłodowskiej
Tematy:
chlorine isotopes
bromine isotopes
Phanerozoic
redox
Opis:
In this paper we discuss the marked discrepancy in global chlorine and bromine isotope variations. While, based on experimentally and theoretically determined fractionation factors, it is expected that bromine isotope variations should be, depending on the process, 2 to 7 times less than chlorine isotope variations it is observed that in formation brines the isotope variations of bromine are at least of the same size as chlorine isotope variations, and regularly even larger. In this paper we argue that this is caused by the fact that oxidation-reduction processes play a more important role in bromine isotope geochemistry than in chlorine isotope geochemistry. Due to the fact that the bromide ion is more easily to oxidise than the chloride ion Rayleigh effects can cause the observed larger variations in bromine isotope geochemistry. In this paper we propose that biochemical reactions (oxidation of bromide ions to methyl bromide) may be the major cause for this effect. Although we do not yet understand the full processes that take place we show that oxidation-reduction processes must be the main effect to explain the differences between the two isotope systems and propose that more research is developed to understand how the processes cause the observed variations.
Źródło:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica; 2015, 70
0137-6861
Pojawia się w:
Annales Universitatis Mariae Curie-Skłodowska, sectio AAA – Physica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The sulphur and oxygen isotopic composition of Lower Cambrian anhydrites in East Siberia
Autorzy:
Peryt, T. M.
Hałas, S.
Kovalevych, V. M.
Petrychenko, O. Y.
Dzhinoridze, N. M.
Powiązania:
https://bibliotekanauki.pl/articles/2058955.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Siberia
Lower Cambrian
evaporites
sulphur isotopes
oxygen isotopes
Opis:
Published sulphur and oxygen isotope age curves for the late Neoproterozoic-Early Cambrian time interval have been based on studies of sulphate intervals of the East Siberian salt giant. We report here on sulphur and oxygen measurements for sulphate dispersed in, or forming laminae in, the rock salt deposits in all Lower Cambrian basins of East Siberia. Sulphur isotope data for 26 samples of Lower Cambrian anhydrites from East Siberia range from +22.6 to +34.5‰. No difference was observed between different suites and between samples taken from anhydrite intercalations in rock salt and from water-insoluble residue in rock salt. Oxygen isotope data for 25 anhydrite samples range from +12.4 to +17.8‰, and thus δ18 O values have a smaller range of variation (5.5‰) than δ34 S (11.8‰) over the entire set of Lower Cambrian anhydrites. The great δ34 S variability observed in the Lower Cambrian of Siberia seems to reflect mixing of sulphates coming from the ocean and due to the riverine input. The lowest δ18 O values may indicate the input values from both the sources, whilst the highest value may result from isotope exchange between SO4 2- and water. Our results combined with data provided by previous workers could indicate a clear stratigraphic trend in δ34 S values, with a remarkable fall of ca. 9‰ in δ34 S value during the earliest Cambrian and then a slight rise in δ34 S values in the younger part of Early Cambrian. However, if only the highest values are taken, the measured values are compatible with seawater δ34 S 3 30‰ during the entire Early Cambrian. Sulphur isotopic composition of sulphate minerals did not be come heavier from the sulphate stage to ward the chloride stage.
Źródło:
Geological Quarterly; 2005, 49, 2; 235--242
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foraminifers and stable isotope record of the Dubivtsi chalk (upper Turonian, Western Ukraine): palaeoenvironmental implications
Autorzy:
Dubicka, Z.
Peryt, D.
Powiązania:
https://bibliotekanauki.pl/articles/2058968.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Turonian
foraminifers
carbon isotopes
oxygen isotopes
biostratigraphy
palaeoenvironments
Opis:
A combined micropalaeontological and stable isotope study of the Dubivtsi chalk in the Western Ukraine indicates its middle late Turonian age. One long-term and clearly distinguishable positive excursion of the isotope curve (d1318
Źródło:
Geological Quarterly; 2012, 56, 1; 199-214
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordovician spatial patterns of climate change inferred from isotope thermometers
Autorzy:
Ma, Xiao-Li
Fan, Yunxuan
Powiązania:
https://bibliotekanauki.pl/articles/24202132.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Ordovician
isotopes
Opis:
Ordovician was an extremely turbulent period for the Earth system, where the Great Ordovician Biodiversification Event (GOBE) occurred in the early-middle Ordovician. Many hypotheses were proposed, taking into account both biotic and abiotic factors. One such hypothesis posits that global cooling led to a transition from greenhouse to icehouse climate systems, which further triggered feedback mechanisms such as increased oceanic circulation, bio-productivity, and oxygenation during the middle Ordovician. Direct evidence, however, is still scarce. Here, we have compiled a comprehensive dataset of δ18O (10,636) from carbonate rocks and fossil shells as well as clumped isotope temperature data (Δ47; 88) spanning the entire Ordovician. Our study investigates climate change from both temporal and spatial perspectives. We assessed the effects of the late diagenesis alteration, lithological differences, different depositional environments and water depths on the carbonate δ18O, and corrected the latitudinal effect of the δ18O in seawater. The latitudinal temperature gradient (LTG) was introduced to account for the spatial patterns of climate change, which here refers to the difference in sea-surface temperature between low (<20°) and low-to-middle (20–40°) latitudes. We observed a gradual increase in the LTG from Tremadocian to Dapingian, indicating an amplified thermal contrast between low and low-middle latitudes. It suggested a remarkable climate cooling and shift towards an icehouse climate state, coinciding with the GOBE. From Darriwilian to Sandbian, the LTG weakens significantly and the temperature difference decreases, which is consistent with the plateau of global temperatures and the slow change in species diversity. After Sandbian, a progressive steepening of LTG was observed, which provides the first evidence for low paradoxical atmospheric CO2 at the Late Ordovician. Our study supports the global cooling hypothesis and sheds light on the links between climate change and biological evolution across the Ordovician.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 45--45
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxygen and sulphur isotopes of gypsum from the Mogilno Salt Dome cap-rock (Central Poland)
Autorzy:
Jaworska, J. K
Wilkosz, P.
Powiązania:
https://bibliotekanauki.pl/articles/2059001.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
gypsum
oxygen isotopes
sulphur isotopes
cap-rock
Mogilno Salt Dome
Opis:
The stable-isotope compositions of oxygen and sulphur from 30 gypsum samples obtained from three drill cores of the Mogilno Salt Dome cap-rock have been analysed; the Mogilno Salt Dome itself is composed of Zechstein evaporites. d344 184242418344182418181818218218218218182
Źródło:
Geological Quarterly; 2012, 56, 2; 249-260
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nd and Sr isotopic evidence for provenance of clastic material of the Upper Triassic rocks of Silesia, Poland
Autorzy:
Konieczna, N.
Belka, Z.
Dopieralska, J.
Powiązania:
https://bibliotekanauki.pl/articles/191300.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Nd isotopes
Sr isotopes
clastics
provenance
Upper Triassic
Polska
Opis:
Nd and Sr isotope data were used to characterize the sources of the Upper Triassic (Keuper) siliciclastic rocks of Silesia in southern Poland. This continental succession, consisting predominantly of fine-grained mud- stones and siltstones, yields a remarkably uniform Nd isotopic composition. Nd model ages T2DM vary from 1.56 to 1.69 Ga and εNd values are in the range from –8.9 to –11.2, documenting old crust contribution in the provenance. In contrast, the Sr isotopic composition (87Sr/86Sr) of the clastics exhibits a relatively large variation from 0.710 to 0.723. The isotopic compositions indicate that the southern part of the Germanic Basin in Silesia was supplied with clastic material from the Bohemian Massif. The axis of the drainage area must have crossed from SW to NE the Saxothuringian units of the East Sudetes and most probably also the area of the Tepla–Barrandian Unit. There is no indication of any sediment transport from the Moravo-Silesian Belt and the Fore-Sudetic Block. It seems, that the Palaeozoic rocks of the latter domain must have been buried completely during Late Triassic times.
Źródło:
Annales Societatis Geologorum Poloniae; 2015, 85, 4; 675-684
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mineralogy and in situ S and Pb isotope characteristics of ore minerals from polymetallic mineralization in the Gierczyn-Przecznica area, SW Poland
Autorzy:
Foltyn, Krzysztof
Kozub-Budzyń, Gabriela Anna
Lahaye, Yann
Piestrzyński, Adam
Skirak, Paulina
Zygo, Władysław
Pieczonka, Jadwiga
Powiązania:
https://bibliotekanauki.pl/articles/27323311.pdf
Data publikacji:
2023
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Pb isotopes
S isotopes
polymetallic mineralization
cobalt
ore geology
Sudety Mts.
Opis:
Chlorite-mica-quartz schist in the Gierczyn-Przecznica area in SW Poland contains polymetallic ores which were the source of tin and cobalt in the past. This mineralogical study revealed the presence of silver-bearing minerals including members of the tetrahedrite (Ag <3 apfu) and freibergite series (3 < Ag < 8 apfu), galena (0.26–1.48 wt.% Ag), and a phase with the chemical composition of Te-rich canfieldite Ag8Sn(S,Te)6. In Przecznica Sn-sulphides are represented by stannite while cobaltite is the most abundant host for cobalt, followed by Co-bearing arsenopyrite. Glaucodot, ullmannite and members of the löllingite-rammelsbergite solid-solution series (Fe,Ni,Co)As2 also contain cobalt but are scarce in the samples. An exposure in the “Psi Grzbiet” area is characterized by the presence of Ag, Ni, Sb and Te minerals accompanied by very small amounts of As-bearing phases (represented by arsenopyrite) while the mineralogical composition in the Przecznica area is characterized by an abundance of As phases and a lack of Sb minerals. Sulphur isotopes of sulphides from Przecznica are heavier than in most deposits related to the Karkonosze Granite intrusion, while their Pb isotope signature in galena suggests an Early Paleozoic pre-Variscan affinity rather than a Variscan one.
Źródło:
Geological Quarterly; 2023, 67, 1; art. no. 10
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isotopic composition of dolomite associated with Middle Miocene Badenian anhydrites in the Carpathian Foredeep Basin of SE Poland
Autorzy:
Jasionowski, M.
Peryt, T.M.
Powiązania:
https://bibliotekanauki.pl/articles/2059029.pdf
Data publikacji:
2010
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Middle Miocene
Paratethys
dolomite
anhydrite
carbon and oxygen isotopes
strontium isotopes
Opis:
Dolomite is a quite common, although usually minor, constituent of the Badenian sulphate deposits of the Carpathian Foredeep Basin. In the autochthonous member of the Wola Różaniecka 7 borehole (SE Poland) which contains well preserved, large anhydritic pseudo-morphs after selenitic gypsum, dolomite constitutes up to 75% of the rock volume, the rest being anhydrite. Dolomites mostly show peloidal clotted microfabrics typical of microbialites and are interpreted as products of microbially induced precipitation and/or dolomitisation at temperatures around 40°C (as interpreted from the d18131813
Źródło:
Geological Quarterly; 2010, 54, 4; 533-548
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foraminiferal colonization related to the Zechstein (Lopingian) transgression in the western part of the Wolsztyn Palaeo-Ridge area, Western Poland
Autorzy:
Peryt, D.
Peryt, T. M.
Raczyński, P.
Chłódek, K.
Powiązania:
https://bibliotekanauki.pl/articles/2059413.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Upper Permian
Zechstein
encrusting foraminifers
carbon isotopes
oxygen isotopes
transgression
breccias
Opis:
The basal Zechstein succession in SW Poland is dominated by breccias and/or conglomerates or extraclast-bearing bioclastic limestones, which were deposited during rapid flooding of the pre-existing intracontinental basin in the early Lopingian (Late Permian). Of these, the boulder-cobble breccias and conglomerates are interpreted as deposited in a rocky shore-zone where density flows and upwelling prevailed. The breccias gradually pass up into bryozoan (or other bioclastics) grainstones. The matrix-supported breccias were deposited as large extraclasts and blocks of Carboniferous rock were rolled down or detached from a cliff and were then either embedded into a carbonate sand or formed a framework supplying voids that could be colonized by tubular encrusting foraminifers. These foraminifers abound in all basal Zechstein facies (except in the debris-flow deposits) and are attributed to Palaeonubecularia. The associated faunas include other foraminifers (uniserial and hemigordiopsids), bryozoans, brachiopods, bivalves, gastropods, and microbial deposits. The prolific growth of tubular encrusting foraminifers has resulted from nutrient supply from the basin by upwelling. Botryoidal aragonite cements (also interpreted as due to upwelling) also characterize the basal Zechstein strata, although they were previously reported only from the upper Zechstein Limestone. The ẟI3C values of the basal Zechstein deposits show small variation and oscillated around 4.0%o, suggesting that these deposits are younger than the Kupferschiefer.
Źródło:
Geological Quarterly; 2012, 56, 3; 529--546
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin of siderites from the Lower Jurassic Ciechocinek Formation from SW Poland
Autorzy:
Leonowicz, P.
Powiązania:
https://bibliotekanauki.pl/articles/2059485.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Cracow-Silesian Upland
Lower Jurassic
siderites
geochemistry
carbon isotopes
oxygen isotopes
palaeosalinity
Opis:
Sideritic rocks, which are characteristic constituents of muddy-silty deposits of the Lower Jurassic Ciechocinek Formation, occur commonly as layers, lenses and small irregular concretions composed of siderite mudstone and siltstone as well as less common lenses of sideritic sandstones. Three types of siderite cement were observed in thin sections: fine-crystalline variety (SF), coarse-crystalline rhombohedra (SR) and fine-crystalline biogenic aggre gates (SA). In all these types BSE analysis revealed compositional zonation of crystals, with in ternal parts enriched in Mg, Mn and Ca and outer zones almost pure siderite. d13C values and chemical composition of siderites combined with the presence of early diagenetic pyrite indicate that siderite crystallized from brackish marine-derived solutions; only in the case of two samples from the lower part of the Ciechocinek Formation the fresh water origin cannotbe excluded. Mn and Fe were supplied by rivers and released by Fe- and Mn-reduction in suboxic zone, whereas Mg and Ca were derived from sea water, which infiltrated into the sediment. Crystal zonation resulted from the diagenetic evolution of pore water as the sediment was buried. Similar composition and development of siderite crystals from different parts of one layer indicate that siderite precipitated simultaneously throughout the whole horizon. Precipitation began from the formation of numerous nuclei and continued by growth of crystals onto them. It could begin already in the iron reduction subzone and continued in the sulphate reduction and methanogenesis zones.
Źródło:
Geological Quarterly; 2007, 51, 1; 67-78
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sulfur and lead isotope geochemical characteristics of Pb-Zn deposits in the Khau Loc zone, northeastern Vietnam, and their significance
Autorzy:
Hung, Khuong The
Tung, Ta Dinh
Binh, Do Quoc
Sang, Pham Nhu
Cuc, Nguyen Thi
Linh, Nguyen Thi Hoang
Tin, Quach Duc
Powiązania:
https://bibliotekanauki.pl/articles/2055848.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
lead-zinc
sulfur isotopes
lead isotopes
Khau Loc zone
northeastern Vietnam
Opis:
In northeastern Vietnam, the Khau Loc zone is considered to have high potential for lead-zinc mineralization. The lead isotope data for 18 galena samples and 18 ones of δ34S isotope data (including galena and pyrite samples) were collected from lead-zinc ore deposits in some areas in the Khau Loc zone, including Phia Dam, Khuoi Man, Ban Lin, Lung Dam, and Ta Pan. These were employed to investigate the sulfur and lead isotope geochemical characteristics of Pb-Zn deposits and their significance in this study. The samples were analyzed using the LA-ICP-MS to show that the Pb isotopic ratios of 206Pb/204Pb, 207Pb/204Pb, and 208Pb/204Pb in the galena samples range from 17.8908 to 18.6012, 15.5794 to 16.1025, 38.4420 to 39.2118, with the average values of 18.296, 15.749, and 38.812, respectively. The pyrite and galena samples had the δ34S isotope, ranging from 9.0 to 15.106. The sulfur isotope systematics implies that most of the lead-zinc ore formations originated from marine sedimentary evaporation deposits and magmatic intrusion-volcanic eruption sources rich in silica. The distribution of lead isotopic ratios had a well-defined cluster for each deposit, indicating the formation of lead-zinc deposits and lower crust and orogen trends. In addition, these findings of lead isotopic ratios and δ34S isotopes proved that the Khau Loc zone is an activated structure with continuous growth in continental crust thickness during the early Proterozoic and Cenozoic periods. Furthermore, the study results also presented the evolution of material sources involved in the formation of lead-zinc ores in the Khau Loc zone.
Źródło:
Geology, Geophysics and Environment; 2021, 47, 3; 143--157
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
K/Ar dating and stable isotope analysis of the Baszkówka and Mt. Tazerzait L5 chondrites
Autorzy:
Hałas, S.
Wójtowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059307.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baszkówka
Tazerzait Mountains
chondrites
K/Ar ages
oxygen isotopes
sulphur isotopes
Opis:
We have determined the content of 40Ar* (1.49 nmol/g) and 4He (1.75 nmol/g) in the Baszkówka meteorite by static vacuum mass spectrometry. The radiogenic argon content was calculated from the measured argon spectrum using the equation: 40Ar* = 40Ar - 295.536Ar assuming a potassium content of 680 ppm wgt. We have obtained K/Ar ages of 3.78 Ga for the chondrules and 3.47 Ga for a bulk sample of Baszkówka. A similar 4He content (1.47 nmol/g) but larger 40Ar* (2.32 nmol/g) content was found for the Mt. Tazerzait bulk sample. The K/Ar age of this meteorite on the basis of the K content (732 ppm) is 4.34 Ga. Sulphur isotope analysis of troilite specimens from both meteorites reveals essentially negative delta 34S values: -1.25š0.06o/oo for Baszkówka and -1.18š0.06o/oo for Mt. Tazerzait expressed on the V-CDT scale. This indicates that both chondrites may have a common origin. The oxygen isotope data (delta 18O = 4.88š0.03o/oo and delta 17O = 3.66š0.10o/oo) suggests that Baszkówka belongs to the L chondrites.
Źródło:
Geological Quarterly; 2001, 45, 3; 315-318
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin of mineral waters from Someseni, Transylvanian Basin, Romania
Autorzy:
Berdea, P.
Cuna, S. M.
Balas, G.
Hauer, E.
Powiązania:
https://bibliotekanauki.pl/articles/2058892.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Romania
Transylvanian Basin
mineral waters
hydrogen isotopes
oxygen isotopes
origin of groundwaters
Opis:
Analysis of the stable isotope composition of the mineral waters from Someseni, Transylvanian Basin, Romania has been made to constrain their origin. The mineral-rich aquifer islocated on the western border of the Neogene Transylvanian Basin. The isotopic study (18 O, D) of mineral waters from Someseni Spa was carried in order to rehabilitate them as natural curative waters. Water samples from five springs (1, 2, 3, 8 and 15), from Becas Brook and from River Somes were collected monthly from October 2003 to March 2004. The quantity of precipitation and the mean temperature in the area were monthly recorded. The deuterium vs. 18 O investigations of the springs indicate a meteoric provenance with deep circulation, having the deuterium content of meteoric water, but shifted to a higher 18 O content as result of isotopic exchange with coun try rock. The δ D and δ18 O values for springs 3 and 8 in February 2004 and March 2004 respectively, suggest some in fluence of surface waters derived from melting of the snow cover.
Źródło:
Geological Quarterly; 2005, 49, 2; 145-150
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable carbon and nitrogen isotopes and elemental composition and origin of organic matter from the Neogene Euphrates, Injana and Dibdibba formations in Iraq : discrimination between marine and terrestrial environments
Autorzy:
Awadh, S. M.
Powiązania:
https://bibliotekanauki.pl/articles/2060490.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
stable carbon isotopes
stable nitrogen isotopes
organic matter
marine environment
terrestrial environment
palaeoenvironment
Iraq
Opis:
Three Neogene sedimentary formations reflecting different depositional environments have been investigated for the purpose of diagnosing the isotopic source of the sedimentary organic matter and their palaeoenvironmental significance in discriminating between marine and terrestrial environments. One of these formations is composed of carbonate and marl of a shallow-marine environment (Euphrates Formation), and the other formations are composed of a clastic terrestrial (fluviatile) deposits with some differences in the depositional conditions (Injana and Dibdibba formations). The isotopic δ13C%, δ15N% values, organic carbon (OC) and total nitrogen contents, and atomic C/N ratios are used as evidence of depositional environment. Average δ13C values (in ‰) for the Dibdiba, Injana and Euphrates formations are –25.4, –25.7 and –24.5, respectively; average δ15N values (in ‰) are 4.44, 5.24 and 7.24 and average OC (in wt.%) is 0.13, 0.3 and 1.1, respectively. A significant variation in the stable carbon and nitrogen isotope compositions between fluvial and marine deposits was recorded. The δC, δ15N and C/N values indicate that the organic matter in the Euphrates Formation is of marine origin, whereas it is of terrestrial origin (fluviatile) in the Injana and Dibdibba formations. The C/Natomic values are mostly high in the Injana (37) and Dibddiba formations (51), suggesting greater input and/or preservation of terrestrial organic matter derived from land plants; the shallow-marine environment (Euphrates Formation) was characterized by a low C/N ratio (9) due to the algal-derived organic matter with limited input of terrestrial organic matter.
Źródło:
Geological Quarterly; 2014, 58, 4; 729--736
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sedimentary development and isotope analysis of deposits at the Cretaceous/Palaeogene transition in the Paraíba Basin, NE Brazil
Autorzy:
Neumann, Virgínio Henrique
Barbosa, José Antônio
Nascimento-Silva, Valberlândia Maria
Sial, Alcides Nobrega
Filho, Mario
Powiązania:
https://bibliotekanauki.pl/articles/94597.pdf
Data publikacji:
2009
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
NE Brazil
Cretaceous-Paleogene boundary
carbon isotopes
oxygen isotopes
Brazylia
izotop węgla
izotop tlenu
Opis:
New data are presented for three formations (Itamaracá, Gramame and Maria Farinha) and two boundaries (Campanian/Maastrichtian and Maastrichtian/Danian) in the Olinda Sub-basin of the Paraíba Basin. Currently accepted facies models, sequence stratigraphy characterizations, and stable-isotope data of carbon and oxygen are reviewed. The carbonate cement of the Itamaracá Formation sandstones shows carbon- and oxygen-isotope ratios consistent with a shallow-marine depositional environment: δ18O ranges from -0.8 to -2.7‰ PDB, and δ13C ranges from +1 to +2‰ PDB. Within the Itamaracá Formation, a maximum flooding surface at the Campanian/Maastrichtian transition has been identified. During the Maastrichtian, a Highstand System Tract was deposited, which shows an increase in temperature and marine bioproductivity as recorded by stable-isotope values (δ18O from -3 to -5‰ PDB, and δ13C values of -1.2, -0.3, 0.1 and +2.3‰ PDB). Just below the K/Pg boundary, the O-isotope signal indicates three warming phases, alternating with four cooling phases.
Źródło:
Geologos; 2009, 15, 2; 103-113
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł

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