Mantle exhumation, crustal denudation, and gravity tectonics during Cretaceous rifting in the Pyrenean realm (SW Europe): Insights from the geological setting of the lherzolite bodies

摘要: [1] The Pyrenean peridotites (lherzolites) form numerous small bodies of subcontinental mantle, a few meters to 3 km across, exposed within the narrow north zone (NPZ) Mesozoic sediments paralleling Fault. Recent studies have shown that mantle exhumation occurred along future NPZ during formation Albian-Cenomanian basins in relation with detachment tectonics. This paper reviews geological setting lherzolite and reports new detailed field data from key outcrops Bearn region. Only two types settings be distinguished among ultramafic bodies. In first type (sedimented or S type), lherzolites occur as clasts various sizes, ranging millimetric grains hectometric olistoliths, monogenic polymictic debris flow deposits Cretaceous age, reworking dominant proportions observed around Lherz body. second (tectonic T rocks kilometric slices associated crustal tectonic lenses. Both lenses are turn systematically large volumes strongly deformed Triassic fault contacts units Jurassic Lower belonging cover NPZ. These formations not older Aptian-early Albian. They unconformably overlain by flysch experienced high temperature-low pressure mid-Cretaceous metamorphism at variable grades. Such characterizes most western Pyrenees. provide evidence tectonics leading manle emphasize role gravity sliding preorogenic evolution realm. light such evidence, simple model basin development can inferred, involving extreme thinning crust, uprising major fault. We demonstrate coeval crust-mantle generalized gravitational low-angle faults salt sole. accounts for basic characteristics precollisional rift