Field‐Based Evidence for Intra‐Slab High‐Permeability Channel Formation at Eclogite‐Facies Conditions During Subduction - Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie Accéder directement au contenu
Article Dans Une Revue Geochemistry, Geophysics, Geosystems Année : 2021

Field‐Based Evidence for Intra‐Slab High‐Permeability Channel Formation at Eclogite‐Facies Conditions During Subduction

Résumé

Fluid release from subducting oceanic lithosphere is a key process for subduction zone geodynamics, from controlling arc volcanism to seismicity and tectonic exhumation. However, many fundamental details of fluid composition, flow pathways, and reactivity with slab-forming rocks remain to be thoroughly understood. In this study we investigate a multi-kilometer-long, high-pressure metasomatic system preserved in the lawsonite-eclogite metamorphic unit of Alpine Corsica, France. The fluid-mediated process was localized along a major intra-slab interface, which is the contact between basement and cover unit. Two distinct metasomatic stages are identified and discussed. We show that these two stages resulted from the infiltration of deep fluids that were derived from the same source and had the same slab-parallel, updip flow direction. By mass balance analysis, we quantify metasomatic mass changes along this fluid pathway and the time-integrated fluid fluxes responsible for them. In addition, we also assess carbon fluxes associated with these metasomatic events. The magnitude of the estimated fluid fluxes (104-105) indicates that major intra-slab interfaces such as lithological boundaries acted as fluid channels facilitating episodic pulses of fluid flow. We also show that when fluids are channelized, high time-integrated fluid fluxes lead to carbon fluxes several orders of magnitude higher than carbon fluxes generated by local dehydration reactions. Given the size and geologic features of the investigated metasomatic system, we propose that it represents the first reported natural analogue of the so-called high permeability channels predicted by numerical simulations.
Fichier principal
Vignette du fichier
2020GC009520.pdf (1.72 Mo) Télécharger le fichier
Origine : Publication financée par une institution

Dates et versions

hal-03204068 , version 1 (21-04-2021)

Identifiants

Citer

Francesca Piccoli, Jay J Ague, Xu Chu, Meng Tian, Alberto Vitale Brovarone. Field‐Based Evidence for Intra‐Slab High‐Permeability Channel Formation at Eclogite‐Facies Conditions During Subduction. Geochemistry, Geophysics, Geosystems, 2021, 22 (3), pp.e2020GC009520. ⟨10.1029/2020gc009520⟩. ⟨hal-03204068⟩
39 Consultations
32 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More