Proterozoic magmatic events recorded in 40Ar/39Ar data from the northern part of the Kedougou Kenieba Inlier (eastern Senegal)

Sagna, Ibrahima; Quidelleur, Xavier; Dioh, Edmond; Gillot, Pierre‐Yves; Lefèvre, Jean‐Claude; Baratoux, Lenka; Diallo, Dinna Pathé

doi:10.1016/j.jafrearsci.2021.104109

Cited by 1 publication

(3 citation statements)

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“…Sagna et al, 2017). However, K-feldspar can be used to achieve a thermochronological analysis through step-heating 40 Ar/ 39 Ar (see next section, and Lovera et al, 1997;Sagna et al, 2021).…”

Section: K-ar and 40 Ar/ 39 Ar Datingmentioning

confidence: 99%

“…During the Mesoproterozoic Albany-Fraser Orogen (Western Australia), rapid exhumation driven by transpressional tectonic activity induced high cooling rate, up to 30 °C/Myr from 585 to 365 °C (Scibiorski et al, 2015). For the Eburnean Orogen in the West African Craton, Paleoproterozoic granites record relatively high cooling rates up to 20 °C/Myr from 900 to 300 °C (Sagna et al, 2021). In contrast, much lower cooling rates of only a few °C/Myr have been inferred for the Grenville Orogen over the 500-350 °C (Reynolds et al, 1995) and 500-150 °C (Cosca et al, 1991) temperature ranges, suggesting that exhumation was there mainly controlled by post-orogenic erosional unroofing.…”

Section: Broader Implicationsmentioning

confidence: 99%

“…40 Ar/ 39 Ar thermochronological approaches based on contrasted diffusion of argon in K-bearing minerals with variable retentivity has been increasingly applied to resolve complex cooling histories (McDougall and Harrison, 1999, and references therein). Variable cooling and exhumation rates have been reported for several orogenic belts, e.g., the Himalayan in Southeastern Tibet (Quidelleur et al, 1997;Harrison et al, 2000), the Pyrenean part of the Hercynian chain (Maurel et al, 2004), the Mesoproterozoic Albany-Fraser Orogen in Western Australia (Scibiorski et al, 2015), or the Eburnean Orogen in the West African Craton (Sagna et al, 2021). In most cases, these studies showed fast cooling and exhumation rates associated with tectonic compression, and much lower cooling rates during late denudation by erosion processes.…”

Section: Introductionmentioning

confidence: 97%

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Exhumation history of the Variscan orogen in western Iberia as inferred from new K-Ar and 40Ar/39Ar data on granites from Portugal

et al. 2021

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Exhumation of the roots of collapsing orogens is a key process in the evolution of mountain belts, which is critical for the understanding of orogenic cycles. From new structural analyses, K-Ar and 40 Ar/ 39 Ar on muscovite, biotite and K-feldspar, and available U-Pb ages, we constrain the cooling and exhumation history of granitic batholiths from the main structural zones of the Variscan orogen in Iberia. We show that: (1) the oldest Ar dated granites (ca. 335 Ma on biotite) record exhumation of gneisses crystallized much earlier (up to ca. 530-510 Ma U-Pb age); (2) granitoids crystallized at ca. 330 Ma record mostly ductile stretching (L-tectonites striking around N-S), consistent with N-S extension (Variscan intra-orogenic collapse); (3) most granites crystallized between ca. 320 and 305 Ma record ductile stretching consistent with deformation along NW-SE to ENE-WSW shear zones during the late-Variscan compression (C3); (4) granites crystallized after 305 Ma record mostly isotropic strain (no visible ductile foliation or lineation), consistent with their emplacement during/after the final collapse of the Variscan orogeny (E2); (5) comparison betweenAr ages on micas and zircon U-Pb ages shows two contrasting situations: (i) similar ages, reflecting crystallization and fast cooling, which can be explained by relatively shallow intrusion and/or fast tectonic uplift; (ii) significant difference between U-Pb and Ar ages, supporting crystallization of deeper seated intrusions and their subsequent uplift for several Ma to tens of Ma; (6) thermochronological modelling on K-feldspar supports significant tectonic exhumation in the core of the chain between ca. 315 and 285 Ma, followed by late-stage passive denudation; 7) Late Carboniferous to early Permian tectonic exhumation was accompanied by significant formation of ore-deposits. Tin deposits occur in pegmatites and/or quartz veins associated with muscovite-rich syn-C3 granites and those of tungsten in quartz veins, breccia pipes and skarns associated with the E2 biotite-rich granites.

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Section: K-ar and 40 Ar/ 39 Ar Datingmentioning

confidence: 99%