Meteoric diagenesis, marine diagenesis, and microporosity in Pleistocene and Oligocene limestones, Enewetak Atoll, Marshall Islands

Saller, Arthur H.; Moore, Clyde H.

doi:10.1016/0037-0738(89)90135-8

Cited by 64 publications

(38 citation statements)

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“…Chalky texture in shallow marine carbonates is determined by a secondary porosity (intercrystalline, vug, moldic, etc., Choquette and Pray, 1970), which is fonned during diagenesis (Harris and Frost, 1984;Kaldi, 1989;Moshier, 1989) and must be distinguished from the depositional porosity (interparticle and intraparticle porosity, Cho queue and Pray, 1970), which characterizes marine pelagic chalks (Moshier, 1989). Dissolution and ara gonite-to-calcite conversion are the main processes involved in the secondary porosity development (Kaldi, 1989;Moshier, 1989;Saller and Moore, 1989;Holail and Lohmann, 1994), in most cases as a consequence of the early stabilization of the original metastable muds (composed of aragonite and high Magnesium calcite). Some workers relate this porosity to dissolution associated with unconformity exposure (Harris and Frost, 1984;Holail and Lohmann, 1994).…”

Section: Porosity and Diagenesismentioning

confidence: 99%

Lacustrine chalky carbonates: origin, physical properties and diagenesis (Palaeogene of the Madrid Basin, Spain)

Arribas

Bustillo

Tsigé

2004

Sedimentary Geology

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The Palaeogene lacusttine chalky carbonates of the Madtid Basin are a peculiar type of very soft and friable carbonate facies with high porosity despite being covered by more than 800 m of sediment. Similar physical propetiies to those desctibed in marine chalk reservoirs emphasize the interest in analysing and characterizing these carbonate facies within a lacustrine depositional system. Lithologically, they are calcitic and/or dolomitic poorly cemented carbonate muds with no significant amounts of skeletal debris. Clay minerals such as illite, smectite and palygorskite are present between the carbonate crystals. Palygorskite is the most common, coveting the carbonate crystals and forming sheets between them. These lacusttine chalky carbonates were formed in the basinal areas of the lake as the result of inorganic carbonate precipitation and/or detrital sedimentation related to episodic reactivation of the adjacent fan systems. Their petrological, geochemical and physical properties indicate that few textural and compositional modifications occUlTed during diagenesis. Their main physical properties are a very low dry bulk and grain density (1.6-2.2 and 2.62 g/cm3, respectively) and medium to high porosity (10-40%) due to micropores « 2 flm, 70%) and macropores (>2 flm, 30%). The convergence of lacustrine sedimentation dynamics (rapid sedimentation), the Oliginal mineralogy of these calcareous lacusttine muds (relatively stable low-magnesian calcite and dolomite), the early formation of the palygorskite cement of these muds, and the retention of Mg-enriched fluids in the pore system, were decisive in the partial inhibition of calcite cementation, compaction and recrystallization. The chalky carbonates are also intercalated between impetmeable littoral carbonate facies that impeded fluid flow through their pore systems.

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Section: Porosity and Diagenesismentioning

confidence: 99%

Lacustrine chalky carbonates: origin, physical properties and diagenesis (Palaeogene of the Madrid Basin, Spain)

Arribas

Bustillo

Tsigé

2004

Sedimentary Geology

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“…Those intensely altered intervals occur (1) in paleo-soil zones immediately below exposure surfaces and (2) in 2-5 m thick intervals interpreted as paleo-freshwater lenses between exposure surfaces (Saller and Moore, 1989). Petrographic, trace elemental, and stable isotopic data from the XRI-I, XEN-l, and XAR-I wells indicate that most LMC cements precipitated in meteoric vadose and phreatic environments (Goter and Friedman, 1988;Saller and Moore, 1991; similar to conclusions of Schlanger, 1963 andGross andTracey, 1966, from different Enewetak wells).…”

Section: Diagenesismentioning

confidence: 99%

“…Petrographic, trace elemental, and stable isotopic data from the XRI-I, XEN-l, and XAR-I wells indicate that most LMC cements precipitated in meteoric vadose and phreatic environments (Goter and Friedman, 1988;Saller and Moore, 1991; similar to conclusions of Schlanger, 1963 andGross andTracey, 1966, from different Enewetak wells). Patterns of meteoric diagenesis in the Pleistocene of Enewetak are described in detail in Goter and Friedman (1988) and Saller and Moore (1989). Some depositional aragonite remains in most samples.…”

Section: Diagenesismentioning

confidence: 99%

“…Corals calcitized in the phreatic zone were associated with intracoralline cements in optical continuity with the calcitizing crystals (Pingitore, 1976). Much of the partial intrafabric dissolution (chalkification) on Enewetak may have occurred in a mixing zone environment where waters undersaturated with respect to calcite and aragonite are dominant (Saller and Moore, 1989). Precipitation of sparry calcite may have occurred in a meteoric vadose or upper meteoric phreatic environment where waters are commonly supersaturated with respect to calcite (Saller and Moore, 1989).…”

Section: Interpretation Of Petrographic Datamentioning

confidence: 99%

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Calcitization of aragonite in Pleistocene limestones of Enewetak Atoll, Bahamas, and Yucatan —An alternative to thin-film neomorphism

Saller

1992

Carbonates Evaporites

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Calcitization of aragonite in Pleistocene limestones of Enewetak, Bahamas, and Yucatan involves the replacement of aragonite by sparry calcite which partially retains the original internal microstructure of its aragonitic precursor. The product would commonly be referred to as "neomorphic spar", but is referred to here as calcitized aragonite to remove any genetic connotation. Petrographic observations suggest that most aragonitic grains underwent partial intrafabric dissolution (chalkification) prior to calcitization. Magnesium concentrations and stable isotope compositions of the calcitized spar are not inherited from aragonitic precursors, but are very similar to Pleistocene calcite cements suggestingthat calcitizingspar precipitated in relatively open meteoric systems similar to meteoric cements. Therefore, most calcitization of aragonite in these Pleistocene limestones apparently oc~urred by chalkification of aragonite followed at a later time by sparry calcite infilling microscopic, intrafabric voids in meteoric water. Calcitization by thin-film neomorphism appears to be minor or absent.

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“…La posición del nivel freático en el registro geoló-gico se ha inferido mediante criterios petrográficos y/o geoquímicos en muy diversos contextos, en sistemas donde los caracteres kársticos son escasos o están ausentes (Land, 1970;Pingitore, 1976;Meyers, 1978;Halley y Harris, 1979;Allan y Matthews, 1982;Given y Lohmann, 1986;Strasser y Davaud, 1986;Budd, 1988;Saller y Moore, 1989;Budd y Vacher, 1991;McClain et al, 1992;Holail, 1992); y mediante criterios geomorfológicos combinados con éstos en terrenos kársticos (Wright, 1982;Craig, 1988;Palmer, 1989). Todos estos estudios muestran la complejidad de las superficies de exposición subaérea y el carácter dinámico de las zonas o ambientes hidrogeológicos que se establecen.…”

Section: Introductionunclassified

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Cañaveras¹,

Sánchez‐Moral²,

Ordóñez³

et al. 2003

Estud. geol.

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rrollado un paleokarst temprano, somero y de forma tabular que muestra un marcado control litológico y del dispositivo de facies deposicionales en su génesis. Integrando criterios geomorfológicos, petrográficos y geoquímicos se ha establecido una zonación hidrogeológica en los perfiles paleokársticos estudiados, diferenciándose: (i) una zona vadosa caracterizada por la existencia de cavidades alargadas en la vertical tapizadas discontinuamente por espeleotemas y otros cementos vadosos; (ii) una franja de oscilación del nivel freático de unos 3-7 metros de espesor, caracterizado por el desarrollo extensivo de cuerpos brechoides estratiformes, la yuxtaposición de cementos vadosos y freáti-cos y los contenidos más bajos en Fe y Mn en el material encajante, y (iii) una zona freá-tica caracterizada por un aumento en los valores de 8 13 C y el predominio de la cementación freática. La correlación de los perfiles paleokárticos revela una paleogeografía para el techo de la Unidad Intermedia con un paisaje topográficamente descendente de norte a sur en la cuenca para el Vallesiense. ABSTRACTAn intra-Vallesian (Upper Miocene) paleokarst developed at the top of the Intermediate Miocene Unit in the continental Madrid basin is recognized. This paleokarst is a early shallow, tabular-shaped karst that shows a marked control by the depositional facies pattem and lithologies. By integrating morphological, petrological and geochemical data, three hydrogeological or environmental zones have been established throughout the paleokarstic profiles: (i) a vadose zone, characterized by vertically elongated caves and discontinuous speleothems and vadose cements (ii) a 3-7 m thick water table fringe, characterized by the wide development of stratiform breccia bodies, the superimposition of both vadose and phreatic features, and the lowest Fe and Mn contents in host-rock carbonates; and (iii) a phreatic zone characterized by an increase of 8 13 C values and the predominance of phreatic cementation. The paleogeographic reconstruction for the intra-Vallesian paleokarst using paleokarstic profiles reveals relative topographic highs to the north and topographic lows to the south drawing the paleokarst landscape.

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Meteoric diagenesis, marine diagenesis, and microporosity in Pleistocene and Oligocene limestones, Enewetak Atoll, Marshall Islands

Cited by 64 publications

References 11 publications

Lacustrine chalky carbonates: origin, physical properties and diagenesis (Palaeogene of the Madrid Basin, Spain)

Lacustrine chalky carbonates: origin, physical properties and diagenesis (Palaeogene of the Madrid Basin, Spain)

Calcitization of aragonite in Pleistocene limestones of Enewetak Atoll, Bahamas, and Yucatan —An alternative to thin-film neomorphism

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