Diagenesis 9. Limestones: The meteoric diagenetic environment

James, Noël P.; Choquette, Philip W.

doi:10.1029/sc004p0045

Cited by 288 publications

(387 citation statements)

References 79 publications

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“…This is consistent with the absence of evaporite beds in the Catoche and surrounding formations (cf. Meyers et al, 1997;Lu and Meyers, 1998;Azmy et al, 2001Azmy et al, , 2008 and lack of moldic porosity within the Catoche Formation (Land, 1967;Matthews, 1974;Longman, 1980;James and Choquette, 1984;Moore, 1997). Consistency in near stoichiometry and narrow ranges of Sr, Mn, and Fe variations in dolomites D1 to D3 (Table 2) probably reflects localized circulation of fluids of similar compositions through crustal rocks, which got hotter with subsequent dolomitization events during diagenesis.…”

Section: Major and Trace Elementsmentioning

confidence: 99%

Origin of Lower Ordovician dolomites in eastern Laurentia: Controls on porosity and implications from geochemistry

Azomani

Azmy

Blamey

et al. 2013

Marine and Petroleum Geology

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a b s t r a c tThe Catoche Formation of the St. George Group in eastern Laurentia (western Newfoundland) consists of early Ordovician (Arenigian) shallow marine platform carbonates (w160 m thick), which were extensively dolomitized during the course of their diagenetic history. The dolomites occur as both replacement and pore-filling cements and are a major control on porosity distribution in the formation. The origin and diagenetic history of the Catoche dolomites at Daniel's Harbour (western Newfoundland) were analysed in comparison to equivalent successions at Port au Choix (PaC) and Port au Port Peninsula (PaP) to assay the reservoir potential of these dolomites in eastern Laurentia. Petrographic examination identified at least three generations of dolomites in the Catoche Formation, which are: (1) an early replacement sub-to eu-hedral micritic dolomite (<4 mme30 mm, D1), (2) eu-to sub-hedral dolomite (70 mme1 mm) often with cloudy cores and clear rims (D2), and (3) subhedral to anhedral saddle dolomite cement (200 mme3 mm, D3). The micritic dolomite (D1) exhibits a dull cathodoluminescence (CL) under cathodoluminoscope, whereas dolomite D2 exhibits consistent concentric CL zonation. Some subhedral crystals of D3 appear zoned both in plane polarized light and cathodoluminoscope, otherwise D3 exhibits a dull CL. Stoichiometric dolomite occurs in all three generations with D2 as the dominant dolomite by abundance.The low strontium (47 ± 25 ppm) content coupled with depleted d 18 O value of dolomitizing fluids (-10 to -11.2& VSMOW) and near-micritic grain size, suggests an early precipitation of dolomite D1 at low temperatures of near-surface conditions from solutions likely formed by mixing of early Ordovician sea and meteoric waters. In contrast, microthermometric measurements of primary two-phase fluid inclusions in dolomite D2 (homogenization temperatures of 102e168 o C with a salinity range of 19.8e25 eq wt% NaCl) and dolomite D3 (homogenization temperatures of 158e190 o C with a salinity range of 20.2e22.2 eq wt% NaCl), suggest that both dolomite generations were generated in mid to deep burial settings from high salinity, low temperature (<200 o C) hydrothermal fluids likely under suboxic conditions. This is consistent with the low Sr concentrations for D2 (36.4 ± 8 ppm) and D3 (38.7 ± 9 ppm), d 18 O values of dolomitizing fluids for D2 (þ2.1 to þ8.1&, VSMOW) and D3 (þ6 to þ8.1& VSMOW), coupled with Fe contents of D2 (1684 ± 1096 ppm) and D3 (1783.7 ± 618 ppm) as well as the respective Mn (D2 ¼ 131.2 ± 50 and D3 ¼ 197.5 ± 55 ppm) concentrations.SREE and shale normalized (REESN) values of Catoche carbonates indicate enrichment in rare earth element (REE) composition of the earliest calcite (C1) relative to those of Arenig seawater, whereas the REESN profiles of the dolomite generations mimic that of calcite C1. The Ce (Ce/Ce*)SN and La (La/La* ¼ Pr/Pr*)SN anomalies of the Catoche dolomites are consistent with precipitation in equilibrium with source fluids in slightly oxic to suboxic conditions whereas Eu...

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Section: Major and Trace Elementsmentioning

confidence: 99%

Origin of Lower Ordovician dolomites in eastern Laurentia: Controls on porosity and implications from geochemistry

Azomani

Azmy

Blamey

et al. 2013

Marine and Petroleum Geology

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“…While the meteoric-water diagenesis usually results in 18 O and 13 C depletions [29,30], such trends are also ubiquitous in modern diagenetically unaffected carbonates [31].…”

Section: Discussionmentioning

confidence: 99%

Sulfur, Strontium, Carbon, and Oxygen Isotopes of Calcium Sulfate Deposits in Late Carboniferous Rocks of the Loei-Wang Saphung (LWS) Area, Loei Province, Thailand

et al. 2018

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Sulfate deposits of the Loei-Wang Saphung (LWS) area, northeastern Thailand, intercalated with carbonate and silicic clastic rock were analyzed for S, O, C, and Sr to determine the depositional environment, as well as the age of formation. Sulfate samples yielded average values of δ 34 S of 14.6‰, while the 87 Sr/ 86 Sr ratio of gypsum was 0.708282 and that of anhydrite was 0.708288. The carbonate layers yielded average δ 18 O PDB , and δ 13 C values of −12.5‰ and −0.1‰, respectively. Our results revealed that the LWS evaporite deposits were originally formed from seawater, and the relatively negative value of δ 18 O was a result of meteoric alteration during subaerial exposure of the sections. Comparing these isotopic values with the nearby Nakon Sawan sulfate deposits, the Sr isotopes showed slightly higher values with very mild variations. These isotopic values suggest that the LWS deposits were not affected by subsequent hydrothermal alteration by younger igneous dikes in this area. Therefore, some of these isotope signatures are considered to be primary features of the deposit, despite the fact that the deposit underwent anchizone to epizone metamorphism. The S and Sr isotope values support the depositional age of the LWS sulfate deposit in the Middle to Late Carboniferous.

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“…Evidence of pedogenic influence such as desiccation-brecciation, mottling, glaebule development, black pebbles, root structures and microkarst (Esteban & Klappa 1983;James & Choquette 1984;Demicco & Hardie 1994), are all common features of this facies association.…”

Section: Mft 1: Non-fossiliferous Fenestral Laminated Mudstone/ Wacmentioning

confidence: 99%

An Upper Jurassic-Lower Cretaceous carbonate platform from the Vâlcan Mountains (Southern Carpathians, Romania): paleoenvironmental interpretation

Michetiuc¹,

Catincuţ²,

Bucur³

2012

Geologica Carpathica

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Abstract:The results of a biostratigraphic and sedimentological study of the Upper Jurassic-Lower Cretaceous limestones cropping out in the southern sector of the Vâlcan Mountains in Romania are presented, including the definition of microfacies types, fossil assemblages and environmental interpretation. Six microfacies types (MFT 1-MFT 6) have been identified, each of them pointing to a specific depositional environment. The deposits are characteristic of a shallow carbonate platform. They contain normal marine or restricted marine facies deposited in low or high energy environments from the inner, middle and outer platform. The age attribution of these deposits (Late Jurassic to Berriasian-Valanginian-?Hauterivian, and Barremian) is based on foraminiferal and calcareous algae associations. The micropaleontological assemblage is exceptionally rich in the Vâlcan Mountains and brings new arguments for dating the Upper Jurassic-Lower Cretaceous limestones in this area.

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Diagenesis 9. Limestones: The meteoric diagenetic environment

Cited by 288 publications

References 79 publications

Origin of Lower Ordovician dolomites in eastern Laurentia: Controls on porosity and implications from geochemistry

Origin of Lower Ordovician dolomites in eastern Laurentia: Controls on porosity and implications from geochemistry

Sulfur, Strontium, Carbon, and Oxygen Isotopes of Calcium Sulfate Deposits in Late Carboniferous Rocks of the Loei-Wang Saphung (LWS) Area, Loei Province, Thailand

An Upper Jurassic-Lower Cretaceous carbonate platform from the Vâlcan Mountains (Southern Carpathians, Romania): paleoenvironmental interpretation

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