Cyclic carbonate–siliciclastic sedimentation in a shallow marine to coastal environment (latest Kimmeridgian–early Tithonian, Galve sub-basin, Spain)

Abstract

The sedimentological analysis of the uppermost Kimmeridgian to lower Tithonian Villar del Arzobispo Formation (Galve sub-basin, NE Spain) has allowed characterizing different carbonate, mixed and siliciclastic facies deposited in coastal to shallow marine areas. Its age calibration has been specified on the basis of new biostratigraphic and chemostratigraphic data. Four successive sequences (30–80 m thick) characterized by the relative dominance of carbonate and siliciclastic facies reflect a sedimentary change from reciprocal to mixed carbonate–siliciclastic sedimentation. Sequences 1 and 2 are reciprocal sedimentation cycles from carbonate-dominated (muddy coastal plain-carbonate lagoon) to siliciclastic coasts (muddy coastal plain-wave dominated delta). Sequence S3 is also reciprocal, from a mixed carbonate–siliciclastic coastal plain-lagoon at the lower part to a wave-dominated delta on top. A mixed carbonate–siliciclastic coastal plain-lagoon characterizes the entire sequence 4. Climate and tectonics controlled carbonate deposition and siliciclastic supply. Reciprocal sedimentation in sequences 1–3 was controlled by orbitally-driven climate changes (from arid to humid conditions) on the age range of long-term eccentricity cycles. A greater imprint of extensional synsedimentary tectonics at the upper part of sequence 3 and during sequence 4 is thought to be the main factor producing the gradual opening of the sub-basin to the wave influence and a more continuous siliciclastic supply, then controlling the change from reciprocal to mixed sedimentation and obliterating the possible imprint of orbitally-induced climatic changes.