Fault-controlled hydration of the upper mantle during continental rifting

Water and carbon are transferred from the ocean to the mantle in a process that alters mantle peridotite to create serpentinite and supports diverse ecosystems1. Serpentinized mantle rocks are found beneath the sea floor at slow- to ultraslow-spreading mid-ocean ridges1 and are thought to be present at about half the world’s rifted margins2, 3. Serpentinite is also inferred to exist in the downgoing plate at subduction zones4, where it may trigger arc magmatism or hydrate the deep Earth. Water is thought to reach the mantle via active faults3, 4. Here we show that serpentinization at the rifted continental margin offshore from western Spain was probably initiated when the whole crust cooled to become brittle and deformation was focused along large normal faults. We use seismic tomography to image the three-dimensional distribution of serpentinization in the mantle and find that the local volume of serpentinite beneath thinned, brittle crust is related to the amount of displacement along each fault. This implies that sea water reaches the mantle only when the faults are active. We estimate the fluid flux along the faults and find it is comparable to that inferred for mid-ocean ridge hydrothermal systems. We conclude that brittle processes in the crust may ultimately control the global flux of sea water into the Earth

Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees

International audienceThe Bay of Biscay and the Pyrenees correspond to a Lower Cretaceous rift system including both oceanic and hyperextended rift domains. The transition from preserved oceanic and rift domains in the West to their complete inversion in the East enables us to study the progressive reactivation of a hyperextended rift system. We use seismic interpretation, gravity inversion, and field mapping to identify and map former rift domains and their subsequent reactivation. We propose a new map and sections across the system illustrating the progressive integration of the rift domains into the orogen. This study aims to provide insights on the formation of hyperextended rift systems and discuss their role during reactivation. Two spatially and temporally distinct rift systems can be distinguished: the Bay of Biscay-Parentis and the Pyrenean-Basque-Cantabrian rifts. While the offshore Bay of Biscay represent a former mature oceanic domain, the fossil remnants of hyperextended domains preserved onshore in the Pyrenean-Cantabrian orogen record distributed extensional deformation partitioned between strongly segmented rift basins. Reactivation initiated in the exhumed mantle domain before it affected the hyperthinned domain. Both domains accommodated most of the shortening. The final architecture of the orogen is acquired once the conjugate necking domains became involved in collisional processes. The complex 3-D architecture of the initial rift system may partly explain the heterogeneous reactivation of the overall system. These results have important implications for the formation and reactivation of hyperextended rift systems and for the restoration of the Bay of Biscay and Pyrenean domain

How does the continental crust thin in a hyperextended rifted margin? Insights from the iberia margin.

International audienc

Quantification and restoration of extensional deformation along the Western Iberia and Newfoundland rifted margins.

International audienc

Hyper-extended crust in the south atlantic: In search of a model.

International audienc

Unravelling the long-strike variability of the Angola-Gabon rifted margin : a mapping approach.

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Allergomic study of cypress pollen via combinatorial peptide ligand libraries

Although Cupressus sempervirens (Cups) pollen represents one of the main aeroallergens in southern Europe, only two Cups allergens have yet been identified and reported: Cup s 1 and Cup s 3.The aim of this study was to identify allergens in cypress pollen using an immuno-proteomic approach. A sequential pollen protein extn. was developed and supplemented by a combinatorial peptide ligand library (CPLL) treatment to select low-abundance species. Control exts. and CPLL eluates have then been resolved by 1-DE and 2-DE gel electrophoresis, blotted and confronted with sera from cypress allergic patients. Extd. proteins including IgE-binding components were identified using nanoLC-MS/MS anal. A total of 108 unique gene products were identified analyzing the eluates and control loaded onto 1-DE SDS-PAGE. Forty proteins were identified in control samples and 68 supplementary species upon CPLL treatment. Out of the 12 IgE-binding proteins characterized in 2-DE gels, 9 were already reported as allergens in various sources including the two major known allergens of Cupressaceae (groups 1 and 2). Three IgE-binding proteins, not previously reported as allergens, are newly described. The improvement in protein extn. combined with the enrichment of low-abundance species allowed us to extend the repertoire of potential cypress pollen allergen