K–Ar age constraints on the evolution of polydeformed fold–thrust belts: The case of the Northern Appalachians (southern Quebec)

Sasseville, Christian; Tremblay, Alain; Clauer, Norbert; Liewig, Nicole

doi:10.1016/j.jog.2007.07.004

Cited by 43 publications

(16 citation statements)

References 39 publications

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“…These nanometersized clay particles, also reported in the gouge matrix in TEM (Fig. 14b), may result from neoformation, as described for gouge in other studies (Vrolijk and van der Pluijm, 1999;Sasseville et al, 2008;Schleicher et al, 2010;Warr et al, 2014). Particularly concerned with illite neoformation in the Main Fault, Clauer et al (2017) report preliminary K-Ar ages of nanometer-sized illites from the gouge material that coincide with the inferred onset of the Main Fault (9-4 Ma).…”

Section: Diffusive Mass Transport (Pressure Solution Precipitation Ansupporting

confidence: 65%

Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

Laurich

Urai

Vollmer³

et al. 2018

Solid Earth

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Abstract. We studied gouge from an upper-crustal, lowoffset reverse fault in slightly overconsolidated claystone in the Mont Terri rock laboratory (Switzerland). The laboratory is designed to evaluate the suitability of the Opalinus Clay formation (OPA) to host a repository for radioactive waste.The gouge occurs in thin bands and lenses in the fault zone; it is darker in color and less fissile than the surrounding rock. It shows a matrix-based, P-foliated microfabric bordered and truncated by micrometer-thin shear zones consisting of aligned clay grains, as shown with broad-ion-beam scanning electron microscopy (BIB-SEM) and optical microscopy. Selected area electron diffraction based on transmission electron microscopy (TEM) shows evidence for randomly oriented nanometer-sized clay particles in the gouge matrix, surrounding larger elongated phyllosilicates with a strict P foliation. For the first time for the OPA, we report the occurrence of amorphous SiO 2 grains within the gouge. Gouge has lower SEM-visible porosity and almost no calcite grains compared to the undeformed OPA.We present two hypotheses to explain the origin of gouge in the Main Fault: (i) "authigenic generation" consisting of fluid-mediated removal of calcite from the deforming OPA during shearing and (ii) "clay smear" consisting of mechanical smearing of calcite-poor (yet to be identified) source layers into the fault zone. Based on our data we prefer the first or a combination of both, but more work is needed to resolve this.Microstructures indicate a range of deformation mechanisms including solution-precipitation processes and a gouge that is weaker than the OPA because of the lower fraction of hard grains. For gouge, we infer a more ratedependent frictional rheology than suggested from laboratory experiments on the undeformed OPA.

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Section: Diffusive Mass Transport (Pressure Solution Precipitation Ansupporting

confidence: 65%

Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

Laurich

Urai

Vollmer³

et al. 2018

Solid Earth

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“…The potential effect of K-feldspar on fault gouge ages is complex. Several studies cite older, host rock-inherited K-feldspar as the cause of age dispersion (e.g., Zwingmann & Mancktelow, 2004;Sasseville et al, 2008Sasseville et al, , 2012Zwingmann et al, 2010a;Davids et al, 2013). Other studies suggest isotopic resetting at the time of faulting (Zwingmann et al, 2010b;Viola et al, 2013) or K-feldspar neocrystallisation during fault activity and associated hydrothermal fluid circulation (Choo & Chang, 2000;Sasseville et al, 2008;Surace et al, 2011;Brockamp & Clauer, 2013;Torgersen et al, 2015).…”

Section: Interpretation Of Inclined Age Spectramentioning

confidence: 99%

“…Several studies cite older, host rock-inherited K-feldspar as the cause of age dispersion (e.g., Zwingmann & Mancktelow, 2004;Sasseville et al, 2008Sasseville et al, , 2012Zwingmann et al, 2010a;Davids et al, 2013). Other studies suggest isotopic resetting at the time of faulting (Zwingmann et al, 2010b;Viola et al, 2013) or K-feldspar neocrystallisation during fault activity and associated hydrothermal fluid circulation (Choo & Chang, 2000;Sasseville et al, 2008;Surace et al, 2011;Brockamp & Clauer, 2013;Torgersen et al, 2015). Importantly, since fine-grained K-feldspar can have significantly lower closure temperatures (350-150°C, dependent on the diffusion domain size; Lovera et al, 1989) than illite/muscovite, it could potentially even lower the age of fine fractions in fault gouges (Löbens et al, 2011;Bense et al, 2014), though no clear cases of this have been documented so far.…”

Section: Interpretation Of Inclined Age Spectramentioning

confidence: 99%

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Ksienzyk¹,

Wemmer²,

Jacobs³

et al. 2016

NJG

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Post-Caledonian extension during orogenic collapse and Mesozoic rifting in the West Norway-northern North Sea region was accommodated by the formation and repeated reactivation of ductile shear zones and brittle faults. Offshore, the Late Palaeozoic-Mesozoic rift history is relatively well known; extension occurred mainly during two rift phases in the Permo-Triassic (Phase 1) and Mid-Late Jurassic (Phase 2). Normal faults in the northern North Sea, e.g., on the Horda Platform, in the East Shetland Basin and in the Viking Graben, were initiated or reactivated during both rift phases. Onshore, on the other hand, information on periods of tectonic activity is sparse as faults in crystalline basement rocks are difficult to date. KAr dating of illite that grows synkinematically in fine-grained fault rocks (gouge) can greatly help to determine the time of fault activity, and we apply the method to nine faults from the Bergen area. The K-Ar ages are complemented with X-ray diffraction analyses to determine the mineralogy, illite crystallinity and polytype composition of the samples. Based on these new data, four periods of onshore fault activity could be defined: (1) the earliest growth of fault-related illite in the Late Devonian-Early Carboniferous (>340 Ma) marks the waning stages of orogenic collapse; (2) widespread latest Carboniferous-Mid Permian (305-270 Ma) fault activity is interpreted as the onset of Phase 1 rifting, contemporaneous with rift-related volcanism in the central North Sea and Oslo Rift; (3) a Late Triassic-Early Jurassic (215-180 Ma) period of onshore fault activity postdates Phase 1 rifting and predates Phase 2 rifting and is currently poorly documented in offshore areas; and (4) Early Cretaceous (120-110 Ma) fault reactivation can be linked either to late Phase 2 North Sea rifting or to North Atlantic rifting.

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“…The northwestern most package of nappes are affected by inverted diagenesis indicating a pre-orogenic, burial diagenesis whereas toward the southeast this was followed by syn-orogenic metamorphism (Ogunyomi et al 1980;Yang and Hesse 1993). The EHZ is defined by a diagenetic to sub-greenschist metamorphic grade (Ogunyomi et al 1980;Yang and Hesse 1993;Glasmacher et al 2003;Sasseville et al 2008) and is bound to the southeast by the Bennett-Brome back-thrust fault (Pinet et al 1996;Castonguay and Tremblay 2003). To the southeast of this fault lies the IHZ, which has been affected by greenschist to amphibolite-facies regional metamorphism.…”

Section: Humber Zonementioning

confidence: 99%

Tracking low-temperature tectonism of the St. Lawrence Platform and Humber Zone, southern Quebec Appalachians, through apatite and zircon (U–Th)/He thermochronology

Emberley

Schneider

2017

Can. J. Earth Sci.

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The St. Lawrence Platform (SLP) and Humber Zone (HZ) of the southern Quebec Appalachians have been the subject of extensive studies to resolve the degree of thermal maturation, yet the timing of the thermal maximum is not well understood. We have employed apatite (AHe) and zircon (ZHe) (U–Th)/He thermochronometry across a network of Late Cambrian to Late Ordovician siliciclastic and Grenvillian basement outcrops to resolve the thermal history below 200 °C. Single crystal dates from individual samples exhibit age dispersion by as much as 300 million years, with a strong positive to negative correlation with increasing effective uranium (eU) concentration. The data in the southwestern portion of the basin allow for thermal maxima of up to 200 °C during the Late Ordovician or Early Devonian. Regional burial trends combined with local estimates of paleogeothermal gradients indicate that, if sedimentation continued after the Late Ordovician, there was no significant increase in burial in southwestern portions of the SLP as previously suggested. Heating was followed by protracted cooling through 180–100 °C during the Late Jurassic and Early Cretaceous, and the cooling rate increased by an order of magnitude through the uppermost crust (80–60 °C) until ca. 100 Ma. Both the external and internal HZ sections experienced rapid cooling through the Silurian after a Taconic thermal maximum. The HZ witnessed protracted cooling through the Late Jurassic, followed by accelerated cooling until the present. Increased recognition of these low-temperature events can augment our understanding of the evolution of accretionary orogens, consequently increasing the efficiency of petroleum exploration.

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K–Ar age constraints on the evolution of polydeformed fold–thrust belts: The case of the Northern Appalachians (southern Quebec)

Cited by 43 publications

References 39 publications

Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

Deformation mechanisms and evolution of the microstructure of gouge in the Main Fault in Opalinus Clay in the Mont Terri rock laboratory (CH)

Post-Caledonian brittle deformation in the Bergen area, West Norway: results from K–Ar illite fault gouge dating

Tracking low-temperature tectonism of the St. Lawrence Platform and Humber Zone, southern Quebec Appalachians, through apatite and zircon (U–Th)/He thermochronology

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