| Summary: | International audience We investigated the Hirnantian glaciation record based on sedimentology, 3D architecture, palynology,carbon isotopes and provenance study. Four settings of the Moroccan Gondwana platform are documented:proximal and distal shelves, shelf canyons and “deep-water” fans; the three former experiencing subglacialerosion during the glaciation acme. Contrasted successions at the 100 km scale allow inspection of sedimentpartitioning through the glacial event.The proximal shelf shows storm-dominated highstand wedges eroded by poorly differentiated glacialsurfaces or deeply truncated by sand-filled tunnel valleys. The main part of the record however consists of asingle glacial retreat succession comprised of a glaciomarine wedge and an overlying forced regressive delta,both coeval with the final glacio-isostatic rebound (cf. presentation by P. Dietrich et al.).In the distal shelf, glacio-eustatic lowstand wedges bounded by flooding surfaces recorded the glaciationonset occurring more inland. Later, the glacial record s.s. is accommodated in shallow glacial incisions flooredby glaciofluvials. Prior to the glacial maximum, glaciomarine and tidal deposits constitute fingerprints ofsubordinate retreat phases. The glacial maximum-ice-sheet front at > 200 km beyond the study area-isrestricted to a single glacial surface and an ensuing glacio-isostatically forced progradation; the latter beinginterrupted by an ultimate glacial advance (an ice lobe?), which built a fold-and-thrust belt deforming outwashsands. Shelf canyons, < 500 m deep, 2-10 km wide, were cut by retrogressive erosion in preglaciation deposits.Their re-incision likely occurred during the early lowstands, as they did also before, and after, the Hirnantian.In-canyon active sedimentation and accumulation characterize periods when, and places where a groundingline occupied the canyon. Glaciomarine deposits are tied to rapid ice retreat phases. During ice minima, tidallyinfluencedsands were deposited at canyon heads whilst, downslope, ...
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