Abstract

Geological and geophysical data recently gathered in the English Channel permit delineation of the main basement structures beneath the Mesozoic and Cenozoic cover. These are, from north to south, (1) a Paleozoic trough, (2) a mafic rock complex, probably ophiolitic, and (3) a Precambrian craton, with a thin Paleozoic cover restricted to some grabens. This disposition suggests the presence of a cryptic suture. Arguments based on stratigraphy (the terranes grow older to the north), structure (faults are parallel to the mafic rock complex, and horsts and grabens are found in the craton), geochronology (the pre-Hercynian intrusions show a distinct arrangement in time and space), petrography (calcalkalic intrusions and an arc of ignimbrites are found), and paleontology (two faunal realms existed during early Paleozoic time) suggest that subduction could have occurred between late Proterozoic and middle Paleozoic time under the Domnonean domain.

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