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Wyświetlanie 1-15 z 78
Tytuł:
Isotope effects in chemistry
Autorzy:
Van Hook, W. A.
Powiązania:
https://bibliotekanauki.pl/articles/146686.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
isotope effects
stable isotopes
kinetic isotope effects
Opis:
Isotope effects on chemical equilibria, reaction rates and molecular properties are reviewed together with the theoretical formalism for understanding such effects.
Źródło:
Nukleonika; 2011, 56, 3; 217-240
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable isotope composition of carbon dioxide emitted from anthropogenic sources in the Kraków region, Southern Poland
Autorzy:
Zimnoch, M.
Powiązania:
https://bibliotekanauki.pl/articles/148175.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
stable isotopes
carbon dioxide
anthropogenic sources
Kraków
Opis:
The summary of the measurements of CO2 stable isotopic composition emitted from different anthropogenic sources in the Krakow region is presented. The sources are divided into three main groups . high emission (electric and heat power plants), low emission (coal and methane burning in the households) and car traffic (gasoline, diesel and LPG supplied engines equipped and not equipped with catalyst). Presented results include two measurement campaigns made in the years 1995 and 2000. The measurements revealed three well-defined groups with respect to carbon isotope composition (delta13CVPDB): .30.60 plus-minus sign 0.37 per mille (thousand) sign (car traffic) .23.82 plus-minus sign 0.10 per mille (thousand) sign (coal burning) and .51.8 plus-minus sign 1.1per mille (thousand) sign (methane burning). The oxygen isotope composition (delta18OVPDB-CO2) of CO2 varied in a broad range, from ca. .11per mille (thousand) sign to ca. .22 per mille (thousand) sign, the most negative values being observed for coal and methane burning and the most positive for cars equipped with a catalyst. No significant isotopic shift has been observed between two measurement campaigns.
Źródło:
Nukleonika; 2009, 54, 4; 291-295
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isotopic events in the Early/Middle Badenian (Miocene) of the Upper Silesia Basin (Central Paratethys)
Autorzy:
Gonera, M.
Bukowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/2059404.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Middle Miocene
Wielician
Paratethys
foraminifera
stable isotopes
Opis:
Middle Miocene foraminifera from the Skawina Formation of the Upper Silesia Basin have been analysed. The stable oxygen and carbon isotope signatures in Globigerinoides quadrilobatus (shallow pelagic), Globigerina bulloides (deeperpelagic) and Uvigerina spp. (benthic) tests show a temporal pattern of changes in the sections studied. The foraminiferal assemblage biozones of the Badenian that were identified earlier, on the basis of taxonomic composition, correspond to changes in the foraminiferal ẟI8O and ẟI3C values. The CPN7/CPN8 transition - as the Moravian/Wielician border - is marked by distinct isotopic events: a ẟ18O increase (IIAB/IIC boundary) followed by a ẟ13C decrease (IIC/IID boundary).
Źródło:
Geological Quarterly; 2012, 56, 3; 561--568
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Isotopic and Cladocera records of climate changes of Early Eemian at Besiekierz (Central Poland)
Autorzy:
Mirosław-Grabowska, J.
Niska, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059552.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Central Poland
palaeoclimate
Eemian Interglacial
cladocera
stable isotopes
Opis:
Results of stable isotope, Cladocera and pollen analyses of lacustrine sediments from Besiekierz (Central Poland) are presented. The Besiekierz palaeolake is located about 25 km north of Łódź (Central Poland) at 130 m a.s.l. The 4 m thick deposits comprise silty sands and clayey silts, overlain by calcareous gyttja and organic silts and peat. Pollen analysis documents that these deposits accumulated during the Eemian Interglacial and the Early Vistulian. Based on the results of stable isotope analyses, nine isotopic horizons (Is) were defined and characterized, and these enabled reconstruction of both climatic and hydrological changes. A positive trend in δ18O values and constant values of δ 13 suggest gradual climatic warming, while constant values of δ 18O and δ 13C indicate stable conditions and/or a fast rate of sedimentation. The fluctuation of isotopic values in the upper part of the succession probably points to a shallowing of the lake due to sedimentary infill. The subfossil cladoceran fauna in the Besiekierz succession is represented by 11 solely littoral species belonging to 3 families. Four zones of Cladocera development were distinguished. The Besiekierz palaeolake was a shallow reservoir. The initial period of its existence probably saw its greatest depth. The Cladocera species present indicate the initial oligotrophic status of the lake and its subsequent increase in trophic status.We compare the results of the isotopic, cladoceran and published palynological analyses, to distinguish and explain the phases of evolution of the lake.
Źródło:
Geological Quarterly; 2005, 49, 1; 67--74
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Changes in paleo-circulation and the distribution of ammonite faunas at the Coniacian–Santonian transition in central Poland and western Ukraine
Autorzy:
Remin, Z.
Gruszczyński, M.
Marshall, J. D.
Powiązania:
https://bibliotekanauki.pl/articles/139412.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Coniacian–Santonian transition
paleogeography
paleo-circulation
ammonites
carbon stable isotopes
oxygen stable isotopes
paleogeografia
amonity
izotopy węgla
izotop tlenu
Opis:
Ammonite distribution patterns and carbon and oxygen stable isotopes from the Lipnik-Kije (Poland) and Dubovcy (Ukraine) sections allow us to propose a model of sea water paleo-circulation in central Europe for the Coniacian-Santonian interval. The tectonic evolution of the south-eastern part of Poland, and expansion of the Krukienic Island areas, appears to have been one of the most important factors affecting paleotemperatures and the distribution of ammonite faunas in the shallow, epicontinental sea in this part of Europe. In the Lipnik-Kije section, low-latitude Tethyan ammonites, especially of the genera Nowakites, Parapuzosia and Saghalinites, are mixed with the cold water loving ammonite genus Kitchinites in the Lower Santonian. In the Dubovcy section (western Ukraine), Tethyan ammonites disappear abruptly in the earliest Santonian, giving place to temperate ammonites of the Kitchinites group in the early Early Santonian and to Boreal belemnites of the genus Gonioteuthis in the Middle and Late Santonian. Despite evidence for the effects of diagenesis in both sections, bulk-rock δ18O records from the limestones support higher seawater paleotemperatures in the Polish sea and cooler conditions in the western Ukraine. The proposed paleo-circulation model and paleotemperature distribution across Europe is supported independently by changes in faunal and nannoflora evidence (ammonites, foraminifera and nannoplankton), and rather unexpectedly with the bulk δ18O data. These data allow the recognition of the end-Coniacian–Early Santonian cooling event, resulting from cold currents flowing from the north, which is traceable, with different magnitude, in several European sections. Facies changes in both sections are related to the input of terrigenous material, and linked to Subhercynian tectonic movements which affected the eastern (Ukrainian) and central (Holy Cross) segment of the Mid Polish Trough at different times. Uplift and sediment input moved westwards through time. Clastic input is detectable at the Coniacian–Santonian boundary in the Ukrainian segment. Similar facies changes reached the Holy Cross segment in Poland distinctly later, somewhen in the Middle Santonian. It is likely that tectonics together with paleo-circulation changes markedly restricted or even cut-off the western Ukraine area from Tethyan ocean influences in the Early Santonian.
Źródło:
Acta Geologica Polonica; 2016, 66, 1; 107-124
0001-5709
Pojawia się w:
Acta Geologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Peculiar calcite speleothems filling fissures in calcareous sandstones and their palaeohydrological and palaeoclimatic significance: an example from the Polish Carpathians
Autorzy:
Gradziński, M.
Duliński, M.
Hercman, H.
Górny, A.
Przybyszowski, S.
Powiązania:
https://bibliotekanauki.pl/articles/2060492.pdf
Data publikacji:
2012
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
flysch Carpathians
Pleistocene
Holocene
speleothems
stable isotopes
ascending water
Opis:
Peculiar calcite speleothems developed in fissures in the Cergowa Sandstones were found in the Klęczany Quarry (Polish Western Carpathians). They represent flowstone and stalactites, rafts and various sparry crusts. Such speleothems, especially phreatic ones, are uncommon in the Outer Carpathians that are composed mainly of siliciclastic rocks of flysch type, with only limited calcium carbonate content. The speleothems analysed grew in vadose and phreatic conditions as well as at the air-water interface. Phreatic speleothems and thin rafts comprise calcite crystals of eccentric morphology. Based on their stable isotope composition the majority of the speleothems form two clusters. The first is characterized by d18O values between –9.8 and –8.5‰ and of d13C values between –5.7 and –0.6‰ whereas the second cluster of samples yields d18O values between –9.4 and –7.3‰ and d13C values from –11.5 to –9.7‰. Speleothems grew between 230+14–13 ka and Holocene time. Phreatic speleothems, including massive rafts, precipitated from ascending water of deep circulation whereas vadose and water table speleothems crystallized from local infiltration water charged with soil CO2. Mixing of both waters in the shallow phreatic zone is plausible.
Źródło:
Geological Quarterly; 2012, 56, 4; 711--732
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:
Stable isotope deuterium as a natural tracer of mixing processes in rivers
Autorzy:
Palige, J.
Ptaszek, S.
Zimnicki, R.
Chmielewski, A. G.
Wierzchnicki, R.
Powiązania:
https://bibliotekanauki.pl/articles/146756.pdf
Data publikacji:
2008
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
stable isotopes
tracer
deuterium
oxygen-18
river
water flow
Opis:
The possibility of application of naturally existing differences in isotope contents 18O/16O, 2H/1H in waters for investigation of transport and mixing of various waters in the tributary-river system is presented. Experiments carried out on the Bug-Narew rivers-Zegrze Lake and the BugoNarew-Vistula rivers systems have indicated that the hydrogen isotope ratio 2H/1H can be used as an intrinsic tracer of natural mixing processes occurring in rivers. The IRMS methodology was used for isotope ratio measurement of water samples. The degrees of water mixing as a function of distance from the confluence point of rivers were determined. The obtained results indicate that in water systems where the natural differences in ?2H are higher than 5‰ this technique can replace the time-consuming and expensive dye (or radiotracer) dispersion tests for evaluation of pollutant transport in rivers.
Źródło:
Nukleonika; 2008, 53, 2; 63-67
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable isotope composition of carbonates in loess at the Carpathian margin (SE Poland)
Autorzy:
Łącka, Bożena
Łanczont, Maria
Komar, Maryna
Madeyska, Teresa
Powiązania:
https://bibliotekanauki.pl/articles/2026059.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
loess
authigenic carbonates
carbon and oxygen stable isotopes
Vistulian
Opis:
Sam ples for the study were col lected from, known from the lit era ture, out crop pro files in Zar zecze, Ra dymno, Dybawka, Tarnawce and Pikulice- Nehrybka, situ ated at the Car pa thian bor der, in the vi cin ity of the Prze myoel town, close to the San River val ley (SE Po land). They rep re sent the Vis tulian loess- palaeosol se quences. Car bon ates oc cur mainly in the lo esses rep re sent ing OIS 2 and 3. Pol len analy sis, car ried out for two pro files (Tarnawce, Ra dymno), throws light on pa laeoe co logi cal con di tions of loess cover for ma tion and trans for ma tion. Iso topic analy sis of authigenic car bon ates was car ried out on car bon ate ce mented bod ies dis persed through out the loess in forms of nod ule, rhi zolith and rhi zo cre tion and on bio clasts, mainly snail shells, os tra cod valves, and sparse glob ules (proba bly the in ter nal shells of the na ked snails). In the suc ces sions stud ied, the up per Vistulian loess de pos ited in en vi ron ment with poor veg e ta tion, con tains rhizoliths and rhizocretions mainly, while in the mid dle and lower Vistulian loess with well de vel oped soils, gley ho ri zons, and in ter ca la tions of sub aque ous sed i ments, re mains of snail shells and ostracod valves pre vail. The two main forms of car bon ates dif fer mark edly in iso to pic com po si tion from one an other. These dif fer ences seem to be more im por tant than those be tween sam ples of one form of car bon ates along par tic u lar sec tions. That is the re sult of nu mer ous fac tors af fect ing the frac tion ation of car bon and, in par tic u lar, ox y gen sta ble iso topes in the en vi ron ment of pre cip i ta tion of authigenic cal cite. The iso to pic com po si tion of car bon ates ce ment ing sed i ments is con trolled mainly by biomineralization of or ganic mat ter and lo cal cli ma tic pa ram e ters which were rather slightly dif fer en ti ated dur ing the for ma tion of the stud ied sed i ments. The d13C val ues for bioclasts vary in a broader range than for calcitic ce ments. Usu ally the snail shell car bon ate is more en riched with heavier car bon iso tope than that from ostracod valves, re sult ing from the iso to pic equi lib rium with pre cip i ta tion and with sur face wa ters, re spec tively. Bas ing on our study we can con clude that fluc tu a tions of iso tope com po si tion of authigenic car bon ates make it hard to ap ply as a paleoclimatic in di ca tor. How - ever, the gen eral trend of d18O vari a tion in ana lysed car bon ate frac tions from leoss-palaeosol se quences dis plays some con nec tions with cli ma tic fluc tu a tions.
Źródło:
Studia Quaternaria; 2008, 25; 3-21
1641-5558
2300-0384
Pojawia się w:
Studia Quaternaria
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
Tytuł:
Stable isotopic and mineralogical investigations of an arid Quaternary lacustrine palaeoenvironment, Western Qaidam, China
Autorzy:
Bojar, A. V.
Rieser, A.
Neubauer, F.
Bojar, H. P.
Genser, J.
Liu, Y.
Ge, X. H.
Powiązania:
https://bibliotekanauki.pl/articles/2058952.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Qaidam
Quaternary
stable isotopes
celestine
carbonates
hypersaline lacustrine environment
Opis:
Stable isotope analyses on carbonates from lake evaporites collected from the non-marine western Qaidam basin yield a positive excursion from Pliocene to Quaternary times. At Dafeng Shan, the Quaternary sequences are composed of alternating layers of celestine/dolomite and aragonite/calcite/barite with distinct isotopic compositions. The sequence described at Dafeng Shan formed in a low energy, hypersaline lacustrine environment as indicated by the microstructures and evaporitic minerals as well as by the absence of lithoclasts. The peloids, ooids and oncoids described are related to microbialactivities in saline lake. The oxygen isotopic composition of the carbonates vary between +34.4 and +39.8‰ (SMOW), representing the heaviest values measured until now. The δ18 O and the δ34 S isotopic composition of the celestine range between 20.1 to 22.3‰ (SMOW) and +19 to +22‰ (CDT) respectively, suggesting sulfur recycling via sulfide oxidation. The carbon isotopic compositions of the carbonates show a large negative excursion of up to -30‰. The microstructures, mineralogy and isotopic compositions as well as the geological context suggest oxidation of methane from a deep source.
Źródło:
Geological Quarterly; 2005, 49, 2; 173-184
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intra-individual variability of dental enamel δ13C and δ18O values in Late Pleistocene cave hyena and cave bear from Perspektywiczna Cave (southern Poland)
Autorzy:
Czernielewski, Michał
Krajcarz, Magdalena
Krajcarz, Maciej T.
Powiązania:
https://bibliotekanauki.pl/articles/2025034.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Pleistocene
MIS 3
stable isotopes
Perspektywiczna Cave
Kraków-Częstochowa Upland
Opis:
An important source of palaeoecological and palaeoenvironmental information is intra-specimen variability of isotopic composition of mammal tooth enamel. It reflects seasonal or behavioral changes in diet and climate occurring during a life of the animal. While well-known in ungulates, in carnivorans this variability is poorly recognized. However, carnivoran remains are amongst the most numerous in the Pleistocene fossil record of terrestrial mammals, so their isotopic signature should be of particular interest. The aim of the study was to verify if enamel of a fossil cave hyena (Crocuta crocuta spelaea) and a cave bear (Ursus ingressus) records any regular inter- or intra-tooth isotopic variability. We examined intra-individual variability of δ13C and δ18O values in permanent cheek teeth enamel of fossil cave hyena and cave bear from the site of the Perspektywiczna Cave (southern Poland). We conclude that the isotopic variability of the cave hyena is low, possibly because enamel mineralization took place when the animals still relied on a uniform milk diet. Only the lowermost parts of P3 and P4 enamel record a shift toward an adult diet. In the case of the cave bear, the sequence of enamel formation records periodic isotopic changes, possibly correlating with the first seasons of the animal life.
Źródło:
Studia Quaternaria; 2020, 37; 121-128
1641-5558
2300-0384
Pojawia się w:
Studia Quaternaria
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Seasonality of isotopic and chemical composition of snowpack in the vicinity of Jang Bogo Station, East Antarctica
Autorzy:
Hur, Soon Do
Chung, Jiwoong
Namgerel, Yalalt
Lee, Jeonghoon
Powiązania:
https://bibliotekanauki.pl/articles/2041728.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctica
Terra Nova Bay
snowpit
water stable isotopes
snow chemistry
Źródło:
Polish Polar Research; 2021, 42, 4; 221-236
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Stable isotopic records of the Kapp Starostin Formation (Permian), Spitsbergen
Autorzy:
Gruszczyński, Michał
Małkowski, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2053255.pdf
Data publikacji:
1987
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Arctic
Spitsbergen
Late Permian
stable isotopes О and C
paleotemperatures
Źródło:
Polish Polar Research; 1987, 8, 3; 201-215
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
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
Wyświetlanie 1-15 z 78

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