The Murca Formation has a maximum thickness of 924 metres (3,031 ft), and is characterised by a sequence of subarkose coarse-grained, locally cross-bedded sandstones with intercalating siltstones and claystones. The basal part of the black and grey feldspar bearing sandstone beds contains large pyrite crystals. The matrix is formed by cements of calcite, iron oxide, sericite and chlorite.[3]
The Murca Formation, belonging to the Cáqueza Group, underlies the Trincheras Formation, lowermost unit of the Villeta Group. The contact with the underlying unit has not been observed.[3] The age has been estimated to be Valanginian. Stratigraphically, the formation is time equivalent with the Cumbre, Rosablanca and Útica Formations. The formation has been deposited in a marine environment characterised by turbidites.[4] A mid submarine fan and outer fan setting have been observed in the Murca Formation.[9] A possible source for the sandstones were Precambrian sandstones, gneisses and granites, belonging to the Guiana Shield.[3][10]
Villamil, Tomas (2012), Chronology Relative Sea Level History and a New Sequence Stratigraphic Model for Basinal Cretaceous Facies of Colombia, Society for Sedimentary Geology (SEPM), pp. 161–216
