| Titre | Thermal segmentation along the N. Ecuador - S. Colombia margin (1-4°N): prominent influence of sedimentation rate in the trench |
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| Auteur | Marcaillou, B; Spence, G; Wang, K ; Collot, J -Y; Ribodetti, A |
| Source | Earth and Planetary Science Letters vol. 272, 2008 p. 296-308, https://doi.org/10.1016/j.epsl.2008.04.049 |
| Image |  |
| Année | 2008 |
| Séries alt. | Secteur des sciences de la Terre, Contribution externe 20070627 |
| Éditeur | Elsevier BV |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.epsl.2008.04.049 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Région | Ecuador; Colombia |
| Lat/Long OENS | -81.0000 -78.0000 4.0000 1.0000 |
| Sujets | levés de reflexion sismiques; interpretations sismiques; milieu sédimentaire; sédimentation; modèles de sedimentation; établissement de modèles; flux thermique; zones de subduction; failles,
chevauchement; tectonique; géophysique |
| Illustrations | croquis cartographiques |
| Programme | Réduction des risques dus aux aléas naturels |
| Diffusé | 2008 07 01 |
| Résumé | (disponible en anglais seulement)
Heat flow at the deformation front drastically varies along the North Ecuador South Colombia (NESC) margin. Moreover, seismic data shows prominent along-strike
variations in trench sediment thickness, implying a great change in sedimentation rate. Analysing the thermal variations permits us to address fundamental questions associated with megathrust earthquakes on the margin and specifically, what is the
exact influence of trench sedimentation rate and related thermal variations on the temperature distribution along the interplate contact and on the extent of the seismogenic zone? We examine this issue by analysing 1/ a new dense reflection data set,
2/ pre-stack depth migration of selected multichannel seismic reflection lines, 3/ numerous newly identified bottom simulating reflectors, 4/ the first heat probe measurements in the region. We carry out thermal modelling that includes the cooling of
the oceanic lithosphere related to sediment deposition and compaction as well as viscous corner flow in the mantle wedge. We estimate that the temperature range from 60-150°C to 350-450°C, commonly associated with the updip and downdip limits of the
seismogenic zone, extends along the plate interface over a distance of 160 to 190 ± 20 km. Four great subduction earthquakes occurred along the margin during the 20th century. We confirm that the updip limit of the seismogenic zone for the 1979 event
is associated with low-temperature (60-70°C) processes. Furthermore, our models suggest that 60-70% of the two-fold decrease in measured heat flow from 3°N to 2.8°N is related to an abrupt southward increase in sedimentation rate in the trench. Such
a change may potentially induce a landward shift of the 60-150°C isotherms, and thus the updip limit of the seismogenic zone, by 10-20 km. |
| GEOSCAN ID | 225016 |
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