How diking affects the longer-term structure and evolution of divergent plate boundaries

Handle URI:
http://hdl.handle.net/10754/595108
Title:
How diking affects the longer-term structure and evolution of divergent plate boundaries
Authors:
Trippanera, Daniele; Acocella, Valerio; Ruch, Joel; Rivalta, Eleonora
Abstract:
Recurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma enhancing transient plate separations. However, the role of diking on a longer term (> 102 years) and its influence on the structure and the evolution of a divergent plate boundary is still poorly investigated. Here we use field surveys along the oceanic Icelandic and continental Ethiopian plate boundaries, along five eruptive fissures and four rift segments. Field observations have also been integrated with analogue and numerical models of dike emplacement to better understand the effect of dike emplacement at depth and at the surface. Our results show that the dike-fed eruptive fissures are systematically associated with graben structures formed by inward dipping normal faults having throws up to 10 m and commonly propagating downward. Moreover, rift segments (i.e. mature rift zones), despite any asymmetry and repetition, are characterized by the same features as the eruptive fissures, the only difference lying in the larger size (higher fault throws, up to 40 m, and wider deformation zones). Analogue and numerical models of dike intrusion confirm that all the structural features observed along the rift segments may be dike-induced; these features include downward propagating normal faults bordering graben structures, contraction at the base of the hanging walls of the faults and upward propagating faults. Simple calculations based on the deeper structure of the eroded rift segments in eastern and western Iceland also suggest that all the fault slip in the active rift segments may result from diking. These results suggest that the overall deformation pattern of eruptive fissures and rift segments may be explained only by dike emplacement. In a magmatic rift, the regional tectonic stress may rarely be high enough to be released through regional faulting, suggesting that regional tectonics has negligible direct impact compared to diking in shaping the studied plate boundaries on the longer-term.
Conference/Event name:
EGU General Assembly 2015
Issue Date:
Apr-2015
Type:
Presentation
Additional Links:
http://adsabs.harvard.edu/abs/2015EGUGA..17.5672T
Appears in Collections:
Presentations

Full metadata record

DC FieldValue Language
dc.contributor.authorTrippanera, Danieleen
dc.contributor.authorAcocella, Valerioen
dc.contributor.authorRuch, Joelen
dc.contributor.authorRivalta, Eleonoraen
dc.date.accessioned2016-01-28T07:13:33Zen
dc.date.available2016-01-28T07:13:33Zen
dc.date.issued2015-04en
dc.identifier.urihttp://hdl.handle.net/10754/595108en
dc.description.abstractRecurrent diking episodes along divergent plate boundaries, as at Dabbahu (2005, Afar) or at Bardarbunga (2014, Iceland) , highlight the possibility to have m-wide opening in a short time (days to weeks). This suggests a prominent role of magma enhancing transient plate separations. However, the role of diking on a longer term (> 102 years) and its influence on the structure and the evolution of a divergent plate boundary is still poorly investigated. Here we use field surveys along the oceanic Icelandic and continental Ethiopian plate boundaries, along five eruptive fissures and four rift segments. Field observations have also been integrated with analogue and numerical models of dike emplacement to better understand the effect of dike emplacement at depth and at the surface. Our results show that the dike-fed eruptive fissures are systematically associated with graben structures formed by inward dipping normal faults having throws up to 10 m and commonly propagating downward. Moreover, rift segments (i.e. mature rift zones), despite any asymmetry and repetition, are characterized by the same features as the eruptive fissures, the only difference lying in the larger size (higher fault throws, up to 40 m, and wider deformation zones). Analogue and numerical models of dike intrusion confirm that all the structural features observed along the rift segments may be dike-induced; these features include downward propagating normal faults bordering graben structures, contraction at the base of the hanging walls of the faults and upward propagating faults. Simple calculations based on the deeper structure of the eroded rift segments in eastern and western Iceland also suggest that all the fault slip in the active rift segments may result from diking. These results suggest that the overall deformation pattern of eruptive fissures and rift segments may be explained only by dike emplacement. In a magmatic rift, the regional tectonic stress may rarely be high enough to be released through regional faulting, suggesting that regional tectonics has negligible direct impact compared to diking in shaping the studied plate boundaries on the longer-term.en
dc.relation.urlhttp://adsabs.harvard.edu/abs/2015EGUGA..17.5672Ten
dc.titleHow diking affects the longer-term structure and evolution of divergent plate boundariesen
dc.typePresentationen
dc.conference.date12-17 April, 2015en
dc.conference.nameEGU General Assembly 2015en
dc.conference.locationVienna, Austriaen
dc.contributor.institutionRoma Tre, Dipartimento di Scienze, Rome, Italyen
dc.contributor.institutionDeutsches GeoForschungsZentrum (GFZ), Potsdamen
kaust.authorRuch, Joelen
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