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| Titel |
Thermal modelling of a transform-divergent interaction zone, the Demerara Plateau, French Guiana margin: architecture of oceanic and continental crusts |
| VerfasserIn |
Céline Grall, Boris Marcaillou, Lies Loncke, Marion Mercier de Lépinay, Christophe Basile, Walter R. Roest, Jan Diederik A. M Van Wees, Sierd A. P. L. Cloetingh  |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250098522
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| Publikation (Nr.) |
 EGU/EGU2014-14207.pdf |
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| Zusammenfassung |
| The crustal architecture of passive margins is a key to constrain their origin and subsequent
evolution, as well as their thermal subsidence. The square shaped continental Demerara
Plateau, French Guiana margin, surmounts Central and Equatorial Atlantic oceanic crusts
surrounding it. Bounded to the northeast by a WNW-ESE-trending transform fault segment
and to both the west and the east by N-S divergent fault segments, the Demerara
Plateau is a complex transform-divergent interaction zone. The aim of this study is to
refine the crustal architecture of this region as derived from gravity and seismic
data, by thermal modelling, and by using surface heat flow data as an additional
constraint.
Previous studies show that the transform transition domain from continental to oceanic
crust occurs across a region of approximately 70-km wide, where the Moho deepens abruptly
from 25-27 km beneath the plateau (thinned continental crust), to 11-12 km in the abyssal
oceanic domain (3-4 km thick oceanic crust).
During the IGUANES cruise (onboard R/V L’Atalante in 2013) 10 surface heat flow
measurements crossing the plateau have been carried out. These data are combined with
borehole heat flows values around. Measures indicate that surface heat flow values range
between 47 and 80 mW/m2 (with an uncertainty on the measurements of ~4mW/m2 on
average), and slightly decreases in the continental domain toward the ocean. Preliminary 1D
thermal modelling results indicate that these heat flow values are consistent with crustal and
sediment thicknesses observed on the Plateau. Along the transform domain, at the transition
towards the oceanic crust, heat flow values are lower than model results, if we consider an
oceanic crust of more than hundred million years and with a thickness of around 3-4 km. We
examine, using a 2D approach, whether this low heat flow could be reasonably
accounted for by thermal exchange between oceanic and continental lithospheres. |
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