Hydrothermal and unexpected diagenetic alteration in Permian shales of the Lodève epigenetic U-deposit of southern France, traced by K–Ar illite and K-feldspar dating

Brockamp, Olaf; Clauer, Norbert

doi:10.1016/j.chemgeo.2013.08.009

Cited by 17 publications

(14 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…At a global scale, intense volcanic activity occurred also during these periods with a significant increase of the seawater temperature (Dera et al, 2011). Thermal anomalies and heat transfers related to successive stages of the North Atlantic opening induced: (1) major increases of the subsidence motion in the Paris Basin due to basement readjustments, (2) large-scale fluid flows at the origin of illite crystallization in Permian and Triassic sandstones (Clauer et al, 1996b; this study), and (3) U, F-Ba-Pb-Zn concentrations at the southwestern margin of the Paris Basin (Cathelineau et al, 2012), and non-mineralizing tectonically driven hydrothermal activity at the southeastern margin of the French Central Massif (Brockamp and Clauer, 2013).…”

Section: Review Of Illitization In Western European Triassic Sandstonmentioning

confidence: 76%

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

Self Cite

View full text Add to dashboard Cite

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

show abstract

Section: Review Of Illitization In Western European Triassic Sandstonmentioning

confidence: 76%

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…The successful dating of the alteration of the Goddo Fault during the Early Cretaceous by means of K-Ar analysis of illite formed during fluid flow-related feldspar break-down59 represents a useful step forward towards the full characterization of complex deformational processes in a time-constrained conceptual scheme.…”

Section: Discussionmentioning

confidence: 99%

Deconvoluting complex structural histories archived in brittle fault zones

et al. 2016

View full text Add to dashboard Cite

Brittle deformation can saturate the Earth's crust with faults and fractures in an apparently chaotic fashion. The details of brittle deformational histories and implications on, for example, seismotectonics and landscape, can thus be difficult to untangle. Fortunately, brittle faults archive subtle details of the stress and physical/chemical conditions at the time of initial strain localization and eventual subsequent slip(s). Hence, reading those archives offers the possibility to deconvolute protracted brittle deformation. Here we report K-Ar isotopic dating of synkinematic/authigenic illite coupled with structural analysis to illustrate an innovative approach to the high-resolution deconvolution of brittle faulting and fluid-driven alteration of a reactivated fault in western Norway. Permian extension preceded coaxial reactivation in the Jurassic and Early Cretaceous fluid-related alteration with pervasive clay authigenesis. This approach represents important progress towards time-constrained structural models, where illite characterization and K-Ar analysis are a fundamental tool to date faulting and alteration in crystalline rocks.

show abstract

“…The comparable ages of the two samples imply therefore that SILV1 K‐feldspar was either inherited from the wall rock and isotopically reset during faulting (e.g. Eide et al ., ; Zwingmann et al ., ) or is itself an authigenic phase (Mark et al ., ; Brockamp and Clauer, ). Although the wall rock contains K‐feldspar, temperatures during faulting were neither high enough nor sufficiently long‐lived to cause significant Ar‐loss and K–Ar age resetting, despite the fine grain size (Mark et al ., ).…”

Section: Discussionmentioning

confidence: 99%

“…If isotopic resetting did occur, it would require a very delicate and unlikely balance between grain and domain size‐dependent Ar retentivity (Lovera et al ., ) and excess Ar contamination (Kelley, ) in the K‐feldspars of SILV1 and mixing of the two illite populations in SILV2, in order to produce the matching inclined age spectra. An authigenic, synkinematic origin of the K‐feldspar in SILV1 (coeval with illite authigenesis in SILV2) seems thus the most reasonable interpretation [see also Brockamp and Clauer () for the documentation of simultaneous growth of authigenic illite and K‐feldspar during faulting‐related hydrothermal activity].…”

Section: Discussionmentioning

confidence: 99%

Inclined K–Ar illite age spectra in brittle fault gouges: effects of fault reactivation and wall‐rock contamination

et al. 2014

View full text Add to dashboard Cite

K–Ar clay fraction ages of brittle faults often vary with grain size, decreasing in the finer size fractions, producing an inclined age–grain‐size spectrum. K–Ar ages and mineralogical characterization of gouges from two normal faults in the Kongsberg silver mines, southern Norway, suggest that inclined spectra derived from brittle fault rocks reflect the mixing of inherited components with authigenic mineral phases. The ages of the coarsest and finest fractions constrain faulting at c. 260–270 Ma and reactivation around 200–210 Ma, respectively. This study demonstrates how wall‐rock contamination influences the K–Ar age of the coarsest size fractions and that authigenic illite and K‐feldspar can crystallize synkinematically under equivalent conditions and thus yield the same K–Ar ages.

show abstract

Hydrothermal and unexpected diagenetic alteration in Permian shales of the Lodève epigenetic U-deposit of southern France, traced by K–Ar illite and K-feldspar dating

Cited by 17 publications

References 31 publications

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

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

Deconvoluting complex structural histories archived in brittle fault zones

Inclined K–Ar illite age spectra in brittle fault gouges: effects of fault reactivation and wall‐rock contamination

Contact Info

Product

Resources

About