This paper is included in the Special Publication entitled 'Cenozoic foreland basins of Western Europe' edited by A. Mascle, C. Puigdefabregas, H.P. Luterbacher and M. Fernandez. New data are presented on the classic growth structure at Sant Llorenc de Morunys (NE Ebro Basin, Spain). During the late Eocene to Oligocene thick alluvial-fan gravel sediments accumulated principally by repetitive sub-aerial mass flow (cohesionless debris flow and fluidal sediment flow) events, with smaller volumes of fan-stream flows. Subaerial, high-viscosity (cohesive) debris flows contributed comparatively small volumes of sediment to the succession. These sediments constructed a complex architecture of conglomeratic and sandstone-bearing lithosomes that were affected by stratal thickening and erosion across a growth fold pair and genetically related internal unconformities, which formed a long-lived thrust-related structure in the immediate footwall of the SE Pyrenean mountain front. Four periods of evolution for the Sant Llorenc growth structure are defined on the basis of distintive stratigraphical architecture. These describe a gross evolution from onlapping to overlapping growth strata, related to the ultimate demise of growth folding. In detail complex erosional and offlapping events punctuated the growth history, which shows extreme variation parallel to the axis of the structure. Patterns of palaeoflow were highly complex, showing distinct axial and transverse directions relatable to growth fold evolutionary periods. Palaeocurrents are considered to have been deflected and diverted by surficial differential subsidence and areas of relative uplift and erosion generated by fold growth. The complexity of sediment dispersal is compounded by variables intrinsic to alluvial fan environments. The Sant Llorenc de Morunys growth strata provide information on how sediments are reorganized by syndepositionally-growing structures and on the nature of sediment distribution between external fold-and-thrust belts and foreland basins.
|Titolo:||Alluvial gravel sedimentation in a contractional growth fold setting, Sant Llorenc de Morunys, southeastern Pyrenees|
ARTONI, Andrea [Membro del Collaboration Group]
|Data di pubblicazione:||1998|
|Appare nelle tipologie:||2.1 Contributo in volume(Capitolo di libro)|