Revised lithostratigraphy of the Upper Cretaceous (Santonian) carbonate platform succession on the northern flank of Sant Corneli, southern Central Pyrenees

Abstract

We describe a revised formal lithostratigraphy for the Sant Corneli Formation (Upper Cretaceous, Santonian) on the northern flank of the Sant Corneli Anticline, ENE of Tremp, southern Central Pyrenees. The formation comprises a carbonate platform succession, which overlies the platform deposits of the Montagut limestones, and is overlain by the basinal Herba-savina clays and marls. Five members are recognized in the formation, three of which are included in a newly defined type section in the western part of the outcrop. This section (196 m) exposes a lower and an upper tongue of the Aramunt Vell Member, separated by an eastward-thickening wedge consisting of the Sant Pere de Vilanoveta Member (new name) and overlying l’Aubagueta Member (new name). The Aramunt Vell Member comprises numerous coarsening-up cycles, each a few metres thick, of nodular silty marls and yellow-brown weathering, miliolid-rich bioclastic calcarenites. Its two tongues unite westwards to encompass the entire thickness of the formation. The Sant Pere de Vilanoveta Member contains coarsening-up cycles of coral-rich marls and marly limestones, rudist lithosomes and bioclastic floatstones and grainstones. The l’Aubagueta Member contains marly limestones and silty clays. Eastwards, two further members represent slope deposits that originally adjoined the platform, though now separated from it by a NW-SE trending normal fault. The Llau de Castellet Member (new name) comprises orange-brown marls and marly limestones laterally equivalent to the lower Aramunt Vell tongue. The overlying Llau de Joncarlat Member (new name) consists of white marls and marly limestones, laterally equivalent to the remaining platform units. Former names incompatible with this revised scheme, hence rejected herein, are the Carreu Formation and el Grau and Prats de Carreu members

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