PAMPA DEL PALO - AN ANOMALOUS COMPOSITE MARINE TERRACE ON THE UPRISING COAST OF SOUTHERN PERU

Quaternary sediments along the southern Peruvian coast occur as stairc ase terraces of coastal and shallow-marine deposits in response to con tinuous uplift related to the active boundary between the Nazca and So uth-American plates. However, near Ilo (in the same coastal stretch) t he emergent Pampa del Pale terrace consists of a relatively-thick, ver tical stack of shallow-marine, coastal and lagoonal deposits that indi cate a rather different geodynamic behaviour. Coastal deposits art: co rrelatable with the successive marine highstands of isotopic stages 7 (?) and 5 (substages 5e and 5c). Combining aerial photo-interpretation , geomorphological mapping, sedimentological analysis, chronostratigra phical data, and structural observations, the Pampa del Pale feature i s interpreted as a faulted block that moved independently of the remai ning southern Peruvian coast and, for some time between the end of Mid dle Pleistocene (before ca. 220 ka) and the early Late Pleistocene (ca . 120 ka), it rose more slowly or was even down-faulted relative to th e rest of the southern Peruvian margin. The independent block movement s ceased after substage 5e, when the Pampa del Pale ''terrace'' was in corporated into the regional uplift of the area. Since ca. 100 ka, mea sured uplift rates in the no area amounted up to 160 mm/10(3)y when th e area has been affected by a few active, NE-SE trending faults only. Copyright (C) 1996 Elsevier Science Ltd & Earth Sciences BL Resources Institute