Dating multistage paleofluid percolations: A K-Ar and 18O/16O study of fracture illites from altered Hercynian plutonites at the basement/cover interface (Poitou High, France)

Cathelineau, ‪Michel; Fourcade, Serge; Clauer, Norbert; Buschaert, Stéphane; Rousset, Davy; Boiron, Marie-Christine; Meunier, Alain; Lavastre, Véronique; Javoy, M.

doi:10.1016/j.gca.2003.10.037

Cited by 38 publications

(17 citation statements)

References 30 publications

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“…8). A similar relationship between K-Ar age of illite, grain size and d 18 O was reported by Cathelineau et al (2004) in fractured and altered plutonites from the French Massif Central, although in their case the value of d 18 O increased with decreasing grain size and K-Ar age.…”

Section: Discussionsupporting

confidence: 81%

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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The Silltal Fault is the northern brittle continuation of the Brenner Fault Zone, marked by a narrow zone of cataclasis and, in three locations, clay-rich fault gouges. The clay mineral composition of these gouges is dominated by higher temperature 2M 1 polytype illite/muscovite, with no 1M/1M d illite or mixed layer illite/ smectite detected. Smectite is limited to the northern samples from the Stephansbrücke location, whereas chlorite is present in all samples. The K-Ar ages from the different sample size fractions (\0.1, \0.4, \2, 2-6, 6-10 lm, ''whole rock gouge'') show a wide spread, from ca. 115 to 12 Ma, with ages consistently decreasing with grain size. Although the ranges overlap, ages from the northern Stephansbrücke samples are generally older (115-36 Ma) than those from the south near Matrei (55-12 Ma), possibly reflecting increasing regional metamorphic temperatures to the south. The well-defined linear relationship between apparent age and hydrogen stable isotope (dD) values establishes a direct correlation between rejuvenation of the K-Ar system and increased interaction with meteoric water introduced and focussed within the fault zone. The dependence of both apparent age and dD on grain size also indicates that radiogenic and stable isotope exchange was controlled by grain size, reflecting new 2M 1 illite growth, mechanical grinding of protolith muscovite during cataclastic faulting, or both. The results demonstrate the advantages of combining radiogenic and stable isotope analysis in interpretation of K-Ar ages from clay fault gouges. The combined approach was necessary to establish the crucial influence on apparent K-Ar ages of meteoric water influx focussed on the fault zone and its interaction with clay-size-fraction grains.

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Section: Discussionsupporting

confidence: 81%

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

et al. 2015

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“…It is often reported as resulting from either progressive K-fixation in a smectite-to-illite trend (e.g., Inoue et al, 1987), or as a direct mineral precipitation associated with concomitant alteration/dissolution of detrital K-bearing feldspar and micas (e.g., Schlegel et al, 2007;Brockamp et al, 2011). Systematic decrease of K-Ar dates with decreasing micrometric size fractions of clay-rich material has been often reported (e.g., Zwingmann et al, 1999;Cathelineau et al, 2004;Sant'Anna et al, 2006), the older ages of the coarser size fractions being generally considered as reflecting contribution of detrital minerals that accumulated more radiogenic argon. Progressive dissolution of these detrital feldspar grains and mica flakes induces isotopic resetting that is dependent on the crystal size and the ambient temperature (Cathelineau et al, 2004).…”

Section: Significance Of the Illite K-ar Agesmentioning

confidence: 99%

Reconstructing fluid-flow events in Lower-Triassic sandstones of the eastern Paris Basin by elemental tracing and isotopic dating of nanometric illite crystals

Blaise

Clauer

Cathelineau

et al. 2016

Geochimica et Cosmochimica Acta

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International audienceLower- to Middle-Triassic sandstones from eastern Paris Basin were buried to a maximum depth of 2500 m at a paleo-temperature of about 100 °C. They contain extensive amounts of authigenic platy and filamentous illite particles similar to those reported in reservoirs generally buried at 3000 to 5000 m and subjected to temperatures of 120 to 150 °C. To evaluate this unexpected occurrence, such sandstones were collected from drill cores between 1825 and 2000 m depth, and nanometric-sized sub-fractions were separated. The illite crystals were identified by XRD, observed by SEM and TEM, analyzed for their major, trace, rare-earth elements and oxygen isotope compositions, and dated by K-Ar and Rb-Sr.Illite particles display varied growth features in the rock pore space and on authigenic quartz and adularia that they postdate. TEM-EDS crystal-chemical in situ data show that the illite lath/fiber and platelet morphologies correspond at least to two populations with varied interlayer charges: between 0.7 and 0.9 in the former and between 0.8 and 1.0 in the latter, the Fe/Fe+Mg ratio being higher in the platelets. Except for the deeper conglomerate, the PAAS-normalized REE patterns of the illite crystals are bell-shaped, enriched in middle REEs. Ca-carbonates and Ca-phosphates were detected together with illite in the separates. These soluble components yield 87Sr/86Sr ratios that are not strictly in chemical equilibrium with the illite crystals, suggesting successive fluids flows with different chemical compositions. The K-Ar data of finer <0.05 μm illite separates confirm two crystallization events at 179.4 ± 4.5 and 149.4 ± 2.5 Ma during the Early and Late Jurassic. The slightly coarser fractions contain also earlier crystallized or detrital K-bearing minerals characterized by lower δ18O values. The δ18O of the finest authigenic illite separates tends to decrease slightly with depth, from 18.2 (± 0.2) to 16.3 (± 0.2) ‰, suggesting different but contemporaneous crystallization conditions deeper in the section.The illite platelets and filaments crystallized in changing physical-chemical crystallization conditions induced by fluids flows through the host-rock pore system. These flow events were probably driven by repetitive rifting episodes of the North Atlantic Ocean, although located several hundreds kilometers away from eastern Paris Basin, and/or by fracturing events in the nearby basement of the Vosges Massif. Complex relationships between geodynamical events, thermal anomalies, and advective fluids confirm that remote tectonic activities can impact quiescent basins, even if located far from tectono-thermal activities, by discrete and long-distance fluid flows

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“…The present study focuses on aa granitoid bedrock located in the ''Seuil du Poitou'', a basement ridge between the sedimentary Paris basin to the NE and Aquitaine basin to the SW. This crystalline bedrock was investigated by the French National Agency for Nuclear Waste Management (ANDRA) as a possible area for implementing an underground laboratory devoted to nuclear waste disposal Boiron et al, 2002;Cathelineau et al, 2004). This work focuses on the interpretation of observable relict evidence, such as mineralogical and hydrogeochemical data (O, C, Sr and U isotopes), in terms of past groundwater conditions in fracture-fill minerals in order to reconstruct the fluid events responsible for the vein fillings.…”

Section: Introductionmentioning

confidence: 99%

Paleo water–rock interaction determined through isotopic tracing (Sr, O, C, U) in fracture-fill minerals: Evidence from the Vienne granitoids (France)

Négrel

Casanova

Bourguignon

2013

Applied Geochemistry

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Dating multistage paleofluid percolations: A K-Ar and 18O/16O study of fracture illites from altered Hercynian plutonites at the basement/cover interface (Poitou High, France)

Cited by 38 publications

References 30 publications

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Timing and conditions of brittle faulting on the Silltal-Brenner Fault Zone, Eastern Alps (Austria)

Reconstructing fluid-flow events in Lower-Triassic sandstones of the eastern Paris Basin by elemental tracing and isotopic dating of nanometric illite crystals

Paleo water–rock interaction determined through isotopic tracing (Sr, O, C, U) in fracture-fill minerals: Evidence from the Vienne granitoids (France)

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