The source area for lower Cretaceous clastic sediments of the Galicia margin: geology and tectonic and erosional history

Abstract

Structural relations shown on seismic-reflection profiles of the Galicia margin indicate that during the Early Cretaceous rifting of the margin, Galicia Bank and its southern extension (Galicia Ridge) were separated from the mainland of Iberia by a fault-controlled trough, and that the rift-stage sandy turbidite sediments in the fault troughs west of Galicia Bank were derived from the erosion of a narrow row of rugged hills that occupied the present area of Galicia Bank and Ridge. The volume and age span of rift-stage clastic sediments, estimated from drill and seismic data, imply rapid erosion of about 1 km of bedrock in the source area, suggesting that the source area was uplifted tectonically during the early stage of rifting. The composition of the sandstone indicates a source area dominanted by granitic and schistose rocks, consistent with data from dredge hauls. The abundant fragmental plant debris in the sandstone indicate heavily wooded land, and regional sedimentological and paleobotanical data suggest warm rainy climatic conditions. -from Authors