Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "isotopes" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 189
Tytuł:
Sequential extraction of uranium isotopes in sediments from an estuary historically affected by anthropogenic inputs of natural radionuclides
Sekwencyjna ekstrakcja izotopów uranu z osadów estuariowych, skażonych naturalnymi izotopami promieniotwórczymi pochodzenia antropogenicznego
Autorzy:
Aguadol, J.
Bolivar, J.
Garcia-Tenorio, R.
Powiązania:
https://bibliotekanauki.pl/articles/340210.pdf
Data publikacji:
2004
Wydawca:
Główny Instytut Górnictwa
Tematy:
izotopy uranu
spektrometria alfa
specjacja
osady
TENORM
U-isotopes
α-particle spectrometry
alpha-particle spectrometry
speciation
sediments
Źródło:
Prace Naukowe GIG. Górnictwo i Środowisko / Główny Instytut Górnictwa; 2004, 1; 64-64
1643-7608
Pojawia się w:
Prace Naukowe GIG. Górnictwo i Środowisko / Główny Instytut Górnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemical signatures of pervasive meteoric diagenesis of Early Miocene syn-rift carbonate platform, Red Sea, NW Saudi Arabia
Autorzy:
Al-Ramadan, K.
Powiązania:
https://bibliotekanauki.pl/articles/2060345.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
meteoric diagenesis
carbonate
stable isotopes
trace elements
Red Sea
Miocene
Opis:
Different diagenetic environments have been recognized in the Early Miocene carbonate platform of Musayr Formation in the Red Sea rift area. Early marine diagenesis includes micritisation that occurs as thin envelope around skeletal and non-skeletal grains in low-energy mud dominated facies and isopachous fibrous calcite in high-energy grain-dominated facies. Pervasive meteoric water diagenesis resulted in cementation of the carbonates by coarse-crystalline blocky-drusy calcite and meniscus cements. Depletion of oxygen (avg. –9.08‰), carbon (avg. –1.6‰) isotopes and trace elements concentrations (avg. values of Fe: 1387 ppm; Mn: 1444 ppm; Sr: 419 ppm; Na: 1194 ppm) in conjunction with negative correlation between Mn2+ and oxygen isotope data suggest variable degrees of fluid-rock interactions and pervasive meteoric diagenesis. The formation of meteoric diagenesis in the Musayr Formation can be explained by two subsequent mechanisms: (1) the presence of meteoric lenses during the time of deposition might have been associated with active freshwater input from the hinterland (NE) due to fall in the relative sea level; (2) later uplift episode during Plio-Pleistocene may have also contributed to the pervasive meteoric diagenetic alterations of the carbonates of the Musayr Formation. The first mechanism is supported by the cement stratigraphy where the blocky-drusy cements postdate the meniscus cement. The latter mechanism seems to have more pronounced effect on the alteration of Musayr carbonate sequence by observing the occurence of late cements such as blocky calcite in most of the samples. The impact of meteoric diagenesis on the studied samples suggest that dissolution is less severe than cementation, hence the visible porosity is very low. Understanding the timing of meteoric diagenesis provides useful information about the reservoir quality distribution in syn-rift carbonate sequences.
Źródło:
Geological Quarterly; 2017, 61, 1; 239--250
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Inter- and intra-specific variability in δ13C and δ18O values of freshwater gastropod shells from Lake Lednica, western Poland
Autorzy:
Apolinarska, K.
Pełechaty, M.
Powiązania:
https://bibliotekanauki.pl/articles/139408.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
C stable isotopes
O stable isotopes
recent gastropod shells
freshwater
inter-specific differences
intraspecific variability
lake Lednica
izotopy stabilne
izotopy węgla
izotopy tlenu
muszle ślimaków
słodkowodne
różnice międzygatunkowe
zmienność wewnątrzgatunkowa
jezioro Lednickie
Opis:
This study focuses on the inter- and intra-specific variability in δ13C and δ18O values of shells and opercula of gastropods sampled live from the littoral zone of Lake Lednica, western Poland. The δ13C and δ18O values were measured in individual opercula of Bithynia tentaculata and in shells of Bithynia tentaculata, Gyraulus albus, Gyraulus crista, Lymnaea sp., Physa fontinalis, Radix auricularia, Theodoxus fluviatilis and Valvata cristata. The gastropods selected for the study are among the species most commonly found in European Quaternary lacustrine sediments. The carbon isotope composition of the gastropod shells was species-specific and the same order of species from the most to the least 13C-depleted was observed at all sites sampled. Differences in shell δ13C values between species were similar at all sampling sites, thus the factors influencing shell isotopic composition were interpreted as species-specific. The δ18O values of shells were similar in all the species investigated. Significant intra-specific variability in shell δ13C and δ18O values was observed not only within the populations of Lake Lednica, which can be explained by heterogeneity of δ13C DIC, δ18O water and water temperature between the sites where macrophytes with snails attached were sampled, but also between individuals sampled from restricted areas of the lake’s bottom. The latter points to the importance of factors related to the ontogeny of individual gastropods.
Źródło:
Acta Geologica Polonica; 2017, 67, 3; 441-458
0001-5709
Pojawia się w:
Acta Geologica Polonica
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:
Pochodzenie mineralnych wód chlorkowo-sodowych w rejonie Rzeszowa w świetle badań izotopowych(δ18O i δD, δ13C, δ37CL) i chemicznych
Origin of saline waters in the vicinity of Rzeszów in light of isotope and (δ18O i δD, δ13C, δ3CL) hydrochemical studies
Autorzy:
Baran, A.
Pelc, A.
Chmiel, S.
Hałas, S.
Powiązania:
https://bibliotekanauki.pl/articles/2074915.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
saline waters
Rzeszów region
water derivation
stable isotopes
bicarbonate
chlorine ion
nitrates
wody mineralne
Rzeszów
izotopy trwałe
dwuwęglan
jon chlorkowy
azotany
Opis:
Several decades ago during exploration for additional resources of tap water a saline water deposit (Cl-Na, J, Fe, B type) has been discovered in the area of Rzeszów hospital park. Nowadays this water is exploited for balneological purposes. In the frame-work of this study for the first time the following stable isotopes: (δ18 i δD, δ13C, δ37Cl) and radiocarbon were determined in order to elucidate the origin of water, its mineralization and quality. Oxygen and hydrogen isotope data leads to conclusion that these waters were formed in a warm pre-Pleistocene period or they are mixture of Miocene seawater with Pleistocene infiltration waters. Carbon isotopic composition (b13= –8.65‰) of bicarbonate is characteristic for deep pore waters occurring in sedimentary rocks, whereas distinctly positive and negative δ37 Cl value rather excludes origin of chlorine ion from an open sea basin. Absence of radiocarbon (in Rzeszów well) indicates no admixture of recent infiltration waters, hence these waters are well preserved from anthropogenic pollution. This is further confirmed by very low concentration of nitrate.
Źródło:
Przegląd Geologiczny; 2012, 60, 12; 657--664
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania izotopowe δ18O, δD oraz δ37Cl w wybranych wodach mineralnych Podkarpacia
Isotopic investigation of δ18O, δD and δ37Cl of selected mineral waters in the Subcarpathian area
Autorzy:
Baran, I.
Baran, A.
Pelc, A.
Hałas, S.
Chmiel, S.
Powiązania:
https://bibliotekanauki.pl/articles/2075279.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
stabilne izotopy
wody mineralne
jon chlorkowy
skład chemiczny
stable isotopes
mineral waters
chorine ion
chemical composition
Opis:
The paper presents new results of stable isotope ratios (18O16O, 2H/1H and 37Cl/35Cl) in a few representative mineral waters of the Subcarpathian area. The observed temporal variability of 18O/16O and 2H/1H in waters has thrown a new light onto the origin of these waters. Analysis of 37Cl/35Cl in chlorine ion is indicative of its origin, at least it was possible to exclude a contamination by chloro-organic compounds. The possibility of tracing of migration of this pollution type by simultaneous analysis of chlorine and carbon isotopes is discussed. The results are discussed on the background of geological structures of the aquifers and their hydrogeological conditions.
Źródło:
Przegląd Geologiczny; 2015, 63, 3; 172--178
0033-2151
Pojawia się w:
Przegląd Geologiczny
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:
New method of pure 111In production by proton-induced nuclear reactions with enriched 112 Sn
Autorzy:
Betak, E.
Rurarz, E.
Mikołajewski, S.
Wojtkowska, J.
Powiązania:
https://bibliotekanauki.pl/articles/148256.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
cross sections
Sn isotopes
proton-induced reactions
111In production
diagnostic radioisotope
Opis:
We aimed at finding out a simple and reliable way of 111In production with the highest radionuclide purity from its grand parent 111Sb and parent 111Sn nuclei, produced by the 112Sn(p,2n)111Sb and 112Sn(p,pn)111Sn reactions, respectively. The target was a metallic 112Sn sample enriched to 84%. We have measured activation cross sections for seven reactions on an enriched 112Sn sample induced by 23.6 š 0.8 MeV energy protons. Gamma-ray spectroscopy with high-purity germanium detectors has been used. We also identified the activities of 55Co (T1/2 = 17.5 h) and 60Cu (T1/2 = 23.7 min) in proton beam monitoring Ni foils, induced in the natNi(p,X)55Co and natNi(p,X)60Cu reactions at 22.8 MeV proton energy. The cross sections determined for these reactions are: s[natNi(p,X)55Co] = 36.6 š 4 mb and s[natNi(p,X)60Cu] = 64.4 š 7 mb. The measured cross sections of reactions on tin isotopes are: sigma[112Sn(p,n)112Sb] = 4 š 0.8 mb; sigma[112Sn(p,2n)111Sb] = 182 š 26 mb; sigma[112Sn(p,pn)111Sn] = 307 š 35 mb; sigma[114Sn(p,2n)113Sb] = 442 š 52 mb; s[117Sn(p,n)117Sb] = 15 š 3 mb; sigma[117Sn(p,p’gamma)117mSn] = 0.37 š 0.06 mb; s[115Sn(p,2p)114m2In] = 0.01 š 0.002 mb. Our measurements indicated the expected yield of the 111In production to be 46 MBq/mAh (1.2 mCi/mi Ah). The contamination of 111In by the undesired nuclide 114m2In was determined and belongs to the smallest ones found in the literature. The measured cross sections were compared with theoretical calculations by two top-level nuclear reaction codes EMPIRE and TALYS.
Źródło:
Nukleonika; 2007, 52, 1; 17-27
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spektrometria masowa i analiza izotopowa biomarkerów frakcji nasyconej
Mass spectrometry and isotopes analysis of the saturated fraction biomarkers
Autorzy:
Bieleń, Wojciech
Janiga, Marek
Powiązania:
https://bibliotekanauki.pl/articles/2143598.pdf
Data publikacji:
2021
Wydawca:
Instytut Nafty i Gazu - Państwowy Instytut Badawczy
Tematy:
spektrometria masowa
analiza izotopowa
biomarkery
hopany
środowisko sedymentacji materii organicznej
mass spectrometry
isotopes analysis
biomarkers
hopanes
sedimentation environment of organic matter
Opis:
Analiza GC-IRMS poszerza i potwierdza (lub nie) interpretację opartą na wynikach z analiz GC-MS. Przykładowo jest bardzo przydatna w określaniu środowiska sedymentacji materii organicznej. Analiza GC-MS biomarkerów i oparte na niej wyniki są wiary- godne, ale dopiero badania GC-IRMS mogą je potwierdzić. W niniejszej pracy próbowano poprzez analizy izotopowe potwierdzić pochodzenie: BNH (28,30-bisnorhopanu) od bakterii chemoautotroficznych, a także wyższych karotenoidów i ich pochodnych od bakterii Chlorobiaceae czy Chromatiaceae. Przeprowadzono badania biomarkerów na aparacie GC-IRMS oraz EA-IRMS. Otrzymane chromatogramy z analiz IRMS porównywano z archiwalnymi analizami GC-MS dla tych samych próbek w celu identyfikacji poszczególnych związków chemicznych. Oprócz dotychczasowej metodyki przygotowania próbek do analiz zastosowano też niestandardową metodę polegającą na rozdziale n-alkanów od węglowodorów rozgałęzionych. Oznaczono na GC-IRMS powtarzalność metody oraz wartości δ13C wybranych biomarkerów z frakcji nasyconej. Stwierdzono, że próbki z małą zawartością biomarkerów nie nadają się do analiz. Z drugiej strony zbyt duże stężenie analitu podanego na chromatograf gazowy powoduje wzrost linii bazowej i gorszy rozdział pików, co również stanowi problem. Wstępnie oznaczono wartości δ13C dla biomarkerów frakcji nasyconej z grupy hopanów: bisnorhopanu (BNH), oleananu, C29 norhopanu, C30 hopanu, moretanu i serii C31–C35 homohopanów oraz dla surowych rop naftowych. Stwierdzono względnie niewielkie różnice w wartości δ13C pomiędzy BNH a hopanami i BNH a surowymi ropami, co sugeruje najprawdopodobniej to samo źródło pochodzenia wszystkich biomarkerów (w tym BNH). Próbowano również oznaczać biomarkery we frakcji aromatycznej metodą GC-IRMS, co jednak się nie udało. Chcąc w przyszłości przeprowadzać takie oznaczenia, należy najprawdopodobniej zastosować specjalną metodykę przygotowania próbek frakcji aromatycznej.
GC-IRMS analysis extends and confirms (or not) the interpretation based on the results of GC-MS analyses. For example, it is very useful in determining the sedimentation environment of organic matter. GC-MS analysis of biomarkers and the results are reliable, but only GC-IRMS studies can confirm it. In this study, the origin of BNH (28,30-bisnorhopane from chemoautotrophic bacteria) and origin of higher carotenoids and their derivatives from Chlorobiaceae or Chromotiaceae bacteria were confirmed through isotopic analyzes. Biomarkers were analyzed using the GC-IRMS and EA-IRMS apparatus. The obtained chromatograms from the IRMS analyses were compared with the archival GC-MS analyses for the same samples in order to identify individual chemical compounds. In addition to the existing methodology of sample preparation for analyses, a non-standard method was also used, consisting in the separation of n-alkanes from branched hydrocarbons. The repeatability of the method was determined on the GC-IRMS and the values of δ13C for selected biomarkers from the saturated fraction were determined. It was found that samples with low biomarker content are not suitable for analysis. On the other hand, too high concentration of the analyte causes an increase of the chromatogram baseline and worse separation of the peaks, which is also a problem. For the crude oils the δ13C values were initially determined for the biomarkers of the saturated fraction from the hopanes group: bisnorhopane (BNH), oleanane, C29 norhopane, C30 hopane, moretane and the C31-C35 homohopane series. Relatively small differences in δ13C values were found between BNH/hopanes and BNH/crude oils, which suggests the same source of origin for all biomarkers (including BNH). Determining biomarkers in the aromatic fraction using the GC-IRMS method was not successful. In the future, a special methodology for preparing samples for carbon isotopic analyses of aromatic fraction will be required.
Źródło:
Nafta-Gaz; 2021, 77, 8; 512-520
0867-8871
Pojawia się w:
Nafta-Gaz
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparative oxygen and carbon isotopic records of Miocene and recent lacustrine unionid bivalves from Poland
Autorzy:
Błażejowski, B.
Racki, G.
Gieszcz, P.
Małkowski, K.
Kin, A.
Krzywiecka, K.
Powiązania:
https://bibliotekanauki.pl/articles/2060015.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sclerochronology
stable isotopes
fresh water
Miocene and recent Unionidae
Bełchatów
Gil Wielki Lake.
Opis:
The δ13C and δ18O isotope data from both fossil (Miocene) and modern freshwater bivalve shells of family Unionidae from Poland (species Margaritifera flabellatiformis and Unio tumidus, respectively) show a similar, truncated sinusoidal pattern.. The isotopic profiles of the whole shell are visibly marked by three growth stages, linked with a progressive loss of environmental record because of declining intra-annual biocarbonate accretion rate. The juvenile and gerontic phases exhibit generally more positive and stable (plateau) isotopic pattern than the mid-age stage. An increasing δ13C trend is typical for the final life stage, likely influenced by nutrient overloading, reversing the tendency towards δ13C depletion throughout the individual’s life induced by metabolic processes. Due to the progressive loss of environmental signals through ontogeny, these initial and final isotopic profile segments probably correspond to, respectively, an instant signature of the first season growth, and a multiyear value set of summer maxima during geriatric stage. Vague seasonal cyclic record is the striking feature of the mid-age δ18O and δ13C profile slices. In case of low-amplitude δ18O curve, this is probably promoted by a sensitivity of the lake ecosystem to many dynamic intra-annual factors affecting water budget balance. This consistent signature mode seems to be typical for lake-dwelling unionid shells at least since Miocene from different climatic zones, as confirmed by coeval lacustrine low-latitude mussels from Amazonia. Thus, this isotope record is relevant to obtain information on the habitat and life cycle of the fossil freshwater bivalves, as well as could help understand modern environmental change.
Źródło:
Geological Quarterly; 2013, 57, 1; 113--122
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Saurichthys (Pisces, Actinopterygii) teeth from the Lower Triassic of Spitsbergen, with comments on their stable isotope composition (δ13C and δ18O) and X−ray microtomography
Autorzy:
Błażejowski, Błażej
Duffin, Christopher J.
Gieszcz, Piotr
Małkowski, Krzysztof
Binkowski, Marcin
Walczak, Michał
McDonald, Samuel A.
Withers, Philip J.
Powiązania:
https://bibliotekanauki.pl/articles/2051411.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Svalbard
fish teeth
stable isotopes
x−ray microtomography
Lower Triassic
Źródło:
Polish Polar Research; 2013, 1; 23-38
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Carbon, oxygen and strontium isotope composition of Plattenkalk from the Upper Jurassic Wattendorf Konservat-Lagerstätte (Franconian Alb, Germany)
Autorzy:
Blendinger, Wolfgang
Mäuser, Matthias
Powiązania:
https://bibliotekanauki.pl/articles/2060917.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Jurassic
Plattenkalk
isotopes
correlation
aged seawater
Jura
izotopy
korelacja
wiek wody morskiej
Opis:
The oldest Jurassic (Kimmeridgian) Plattenkalk occurs in Wattendorf on the northern Franconian Alb (southern Germany). It is a 15 m thick alternation of laminated dolomite and limestone, interbedded with carbonate debris layers in a depression ~2 km across and a few tens of metres deeper than the surrounding microbial-sponge reefs. The Plattenkalk overlies a few tens of metres of microbialsponge biostrome facies and bedded, micritic basinal limestone. The bulk-rock stable isotopes of the micritic basinal facies gradually change from normal marine (δ13C ~ +2‰, δ18O ~ –2‰ VPDB) to lower values (δ13C ~ 0‰, δ18O ~ –6‰) in a ~ 40 m thick interval including Plattenkalk and suggest ageing of the bottom waters. The surrounding reefs are isotopically nearly invariant (δ13C ~ +2‰, δ18O ~ –2‰ VPDB). An isotope anomaly (δ13C of > ~ –9‰) is restricted to the basinal facies and is most pronounced in the biostrome facies. This indicates methanogenesis, which is documented in negative δ13C in dedolomite, calcite-cemented dolomite and calcite concretions and occurred probably mainly below seabed. The Konservat-Lagerstätte was probably deposited near an oxygen minimum zone in a water column with low productivity of organic material. Dolomite is in isotopic equilibrium with Plattenkalk and was probably deposited as protodolomite from chemically modified, aged seawater. 87Sr/86Sr ratios of bulk carbonate are often slightly radiogenic, probably due to random analytical sample contamination by clay minerals. Belemnite and some matrix 87Sr/86Sr is slightly lower than that of Kimmeridgian seawater, either caused by basin restriction or by fluids derived from the diagenesis of Oxfordian rocks below. An equivalent Upper Kimmeridgian depression ~23 km distant and a somewhat younger Konservat-Lagerstätte in Poland show a δ13C isotope anomaly below the main fossil beds. Isotopic evidence for saline bottom waters, the current interpretation, is lacking. This study also shows that micritic carbonates can preserve their early diagenetic, marine δ18O signal, which is correlatable over tens of kilometres
Źródło:
Volumina Jurassica; 2021, 19, 1; 1--20
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The dolomite problem : evidence from 3D modeling, XRD and geochemical data of Zechstein reefs (Upper Permian, Germany)
Autorzy:
Blendinger, Wolfgang
Powiązania:
https://bibliotekanauki.pl/articles/2060255.pdf
Data publikacji:
2020
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Zechstein
dolomite
limestone
isotopes
3D modeling
fluid flow
Opis:
Three-dimensional modeling of the limestone and dolomite distribution in an Upper Permian (Zechstein) stromatolite-bryozoan reef, ~500 m in diameter and 35 m thick (77 borehole cores, 172 data points), shows that dolomite occurs as laterally and vertically discontinuous intervals. The prevailing mineral phases are near-stoichiometric dolomite and Mg-free calcite (370 XRD and 274 XRF analyses). Both δ13C and δ18O (526 analyses) show a spread of ~10‰ and co-vary with the mineralogy; the heaviest dolomite and calcite δ13C differ by ~1.5‰. Diagenetic modifications caused by flowing meteoric fluids could account for the observed “inverted J” trend of stable and the radiogenic signature of 87Sr/86Sr (23 analyses), but neither vertical nor horizontal gradients occur in the reef modeled. Because the dolomite geometries are incompatible with those predicted by fluid flow models, and the limestone-dolomite difference in δ13C overlaps estimates of isotope fractionation associated with Mg content, the dolomite studied was a depositional Very High Mg Calcite recrystallized to dolomite in a semi-closed diagenetic system rather than a Low Mg Calcite transformed by a dolomitization process. The isotope pattern suggests biogenic fractionation and/or loss of heavy stable C and O and light Sr isotopes during diagenesis.
Źródło:
Geological Quarterly; 2020, 64, 3; 692--710
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Origin and significance of early-diagenetic calcite concretions and barite from Silurian black shales in the East European Craton, Poland
Autorzy:
Bojanowski, Maciej J.
Kędzior, Artur
Porębski, Szczepan J.
Radzikowska, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/138638.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
carbonate concretions
stable isotopes
cathodoluminoscopy
sedimentation rate
marine productivity
biogenic gas production
bacterial sulfate reduction
shale gas
konkrecje węglanowe
izotopy stabilne
katodoluminoskopia
szybkość sedymentacji
produktywność morska
gaz biogenny
redukcja bakteryjna siarczanu
gaz łupkowy
Opis:
The Silurian Pelplin Formation is a part of a thick, mud-prone distal fill of the Caledonian foredeep, which stretches along the western margin of the East European Craton. The Pelplin Formation consists of organic carbon-rich mudstones that have recently been the target of intensive investigations, as they represent a potential source of shale gas. The Pelplin mudstones host numerous calcite concretions containing authigenic pyrite and barite. Mineralogical and petrographic examination (XRD, optical microscopy, cathodoluminoscopy, SEM-EDS) and stable isotope analyses (δ13Corg, δ13C and δ18O of carbonates, δ34S and δ18O of barite) were carried out in order to understand the diagenetic conditions that led to precipitation of this carbonate-sulfide-sulfate paragenesis and to see if the concretions can enhance the understanding of sedimentary settings in the Baltic and Lublin basins during the Silurian. Barite formed during early diagenesis before and during the concretionary growth due to a deceleration of sedimentation during increased primary productivity. The main stages of concretionary growth took place in yet uncompacted sediments shortly after their deposition in the sulfate reduction zone. This precompactional cementation led to preferential preservation of original sedimentary structures, faunal assemblages and earlydiagenetic barite, which have been mostly lost in the surrounding mudstones during burial. These components allowed for the reconstruction of important paleoenvironmental conditions in the Baltic and Lublin basins, such as depth, proximity to the detrital orogenic source and marine primary productivity. Investigation of the concretions also enabled estimation of the magnitude of mechanical compaction of the mudstones and calculation of original sedimentation rates. Moreover, it showed that biogenic methane was produced at an earlydiagenetic stage, whereas thermogenic hydrocarbons migrated through the Pelplin Formation during deep burial.
Źródło:
Acta Geologica Polonica; 2019, 69, 3; 403-430
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palaeoenvironmental interpretation of dinosaur- and mammal-bearing continental Maastrichtian deposits, Hateg basin, Romania
Autorzy:
Bojar, A. V.
Grigorescu, D.
Ottner, F.
Csiki, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2058894.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Hateg Basin
Maastrichtian
dinosaurs
paleosols
stable isotopes
clay mineralogy
Opis:
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.
Źródło:
Geological Quarterly; 2005, 49, 2; 205--222
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 189

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies