Contribution of volcaniclastic sediment to the formation of world's largest Holocene beach ridge system.

World’s largest late Holocene beach ridge plain in southern Mexico has recorded the variability in sea level, river discharge and sandy sediment supply to the coast over the past millennia at a decadal time resolution. This exceptionally high resolution sedimentological record is the result of ample sediment supply and subsequent high progradation rates of the beach ridge plain. We present evidence that volcaniclastic sediments from past volcanic eruptions were an important sediment source. The contribution of past eruptions of El Chichón volcano to the sediment budget is determined for its last eruption in 1982. Large volumes of volcaniclastic sediments were deposited in the Magdalena and Platanar river valleys that drain the volcano’s slopes. Landsat and Lidar images and a field visit were used for the geomorphological mapping of the 1982 ‘event terrace’ and volume estimates of eroded deposits are based on the comparison of the digital elevation model constructed for 1984 and 2007. The results are compared to other possible sources to establish a preliminary sediment budget for the formation of the beach ridge plain