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Wyszukujesz frazę "carbonate diagenesis" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Zechstein (Ca1) limestone-marl alternations from the North-Sudetic Basin, Poland: depositional or diagenetic rhythms?
Autorzy:
Biernacka, J.
Borysiuk, K.
Raczyński, P.
Powiązania:
https://bibliotekanauki.pl/articles/2059558.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Zechstein
limestone-marl alternations
storm deposits
carbonate diagenesis
Opis:
Limestone-marl alternations constitute a characteristic rock facies within the Zechstein Limestone (Ca1) deposits of the North-Sudetic Basin, Poland. Rhythmites of this type are exposed in a 10-metres section at Nowy Kooeciół, which from the beginning of the last century has been considered representative for this part of the Zechstein basin, and were formerly interpreted as calcareous storm sediments alternating with marls deposited during more quiet conditions. Our results of sedimentological, petrographical and chemical studies suggest that the Nowy Kościół section is a record of distal storm deposits, but that the present-day layering does not precisely reflect the depositional rhythm. Post-depositional changes have overprinted and blurred the original pattern.We propose a model of diagenetic alteration in which dissolution and reprecipitation of calcium carbonate in the shallow subsurface formed new layer boundaries; subsequent modifications during deeper burial followed these early diagenetic changes.
Źródło:
Geological Quarterly; 2005, 49, 1; 1--14
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
  • odwiedzone
Tytuł:
The influence of diagenetic alterations on porosity in the Triassic Narrabeen Group, Southern Sydney Basin, Australia
Autorzy:
Al Gahtani, F.
Powiązania:
https://bibliotekanauki.pl/articles/2060323.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
petrography
diagenesis
primary porosity
secondary porosity
quartz overgrowth
carbonate cement
Opis:
Petrography of the Triassic Narrabeen Group (Southern Sydney Basin of Australia) was described by thin section, scanning electron microscope and X-ray diffraction techniques. Sandstone composition includes mostly lithic grains with minor quartz, feldspar, mica and heavy minerals; litharenites and sublitharenites are common and quartzarenites are rare. Quartz includes monocrystalline and polycrystalline grains while the feldspar includes both K-feldspar and plagioclase. Volcanic, sedimentary and chert rock fragments are present. In thin section porosity is visible in all units, particularly the coarse-grained deposits. Secondary porosity is greater than the primary porosity. The diagenetic alterations include compaction, quartz overgrowths, authigenic clay minerals, carbonate cement and authigenic feldspar. Compaction occurred in all units during diagenesis. Both early and late diagenetic carbonate cement is important in the Narrabeen Group. Pore-filling carbonate cement reduced porosity whereas dissolution of carbonate resulted in secondary porosity. Authigenic clay minerals are widespread in all units filling pores and occurring as grain-coatings on detrital and authigenic grains. Where they coat quartz grains they preserve porosity by preventing growth of quartz overgrowths. Dissolution of unstable feldspar and lithic grains provided secondary porosity. In the Narrabeen Group, shale and siltstone are abundant in the Wombarra Claystone, Stanwell Park Claystone, Bald Hill Claystone and Newport Formation, forming lithological seals and confining layers. Minor sandstone beds occur in the Wombarra Claystone and contain more porosity. Medium- and coarse-grained sandstone is common in the Coalcliff Sandstone, Scarborough Sandstone and Bulgo Sandstone and shows low to moderate porosity. Thus, these sandstone units probably contain gas or water.
Źródło:
Geological Quarterly; 2013, 57, 4; 613--628
1641-7291
Pojawia się w:
Geological Quarterly
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 1-3 z 3

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