| Titre | An integrated petrochronological and thermochronological approach for the detrital record |
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| Auteur | Kellett, D A ;
Weller, O M; Zagorevski, A; Regis, D |
| Source | Goldschmidt 2018, abstracts; 2018 p. 1  Accès
ouvert |
| Liens | Online - En ligne (PDF, 144 KB)
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| Image |  |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190224 |
| Éditeur | European Association of Geochemistry |
| Réunion | 28th V.M. Goldschmidt Conference; Boston; US; août 12-17, 2018 |
| Document | site Web |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Sujets | évolution tectonique; orogenèse; sutures; accretion; terrains; débris; bassins sédimentaires; métamorphisme; clastes; éclogîtes; thermobarométrie; diffusivité thermique; diffusion; établissement de
modèles; antecedents thermiques; Cordillère canadienne; Terrane de Yukon-Tanana; Terrane de Stikinia ; Méthodologie; tectonique; géochronologie; Sciences et technologie; Nature et environnement; Phanérozoïque; Mésozoïque; Jurassique; Trias |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Évolution tectonique du Yukon, haut mésozoïque au tertiaire de l'ouest de la
Cordillère |
| Diffusé | 2018 08 01 |
| Résumé | (disponible en anglais seulement)
Rocks exposed near suture zones can record the timing and style of orogenic accretion events. However, in long-lived accretionary orogens, subsequent orogenesis
often obscures original terrane relationships and suture rocks may not be preserved or exposed. A detrital record of the suture may be captured by adjacent sedimentary basins. This is the case for the long-lived northern Canadian Cordillera, where
sutures between terranes accreted during the early Mesozoic are not generally preserved. The Whitehorse trough synorogenic basin contains an E. Jurassic, ~300 m thick horizon of (ultra-) high pressure metamorphic detritus that includes mm-sized
eclogite clasts.
Isolation and study of heavy mineral fractions, a common approach in basin analysis, results in disaggregation of small lithic clasts, limiting identification of equilibrium assemblages and temporal constraints. Since
petrochronology and thermochronology techniques are performed by microanalysis, it is feasible to apply them to the intact detrital eclogite clasts to examine timing, style and conditions of accretion. We integrated thermobarometry, geochronology,
thermochronology and thermal diffusion modeling methods to demonstrate that the eclogite clasts likely reached peak metamorphic conditions of 2.2-2.9 GPa and greater than or equal to 800 °C, cooled and exhumed during E. Jurassic and were deposited
into the basin by earliest Toarcian. Minimum mean cooling and exhumation rates are ~38 °C/myr and ~4.1 km/myr, respectively. Based on these findings, the most likely source for the clasts is a suture between the Yukon-Tanana and Stikinia terranes,
involving a latest Triassic collision, followed by rapid Early Jurassic exhumation of the lower plate Yukon-Tanana terrane. Our study demonstrates how micro-analytical techniques used for petrochronology can be applied to very small lithic clasts in
the sedimentary record towards the tectonic reconstruction of accretionary orogens. |
| GEOSCAN ID | 321389 |
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