Quaternary history of the piedmont reach of Río Diamante, Argentina

摘要: Abstract The Rio Diamante is located in a segment of the southern Central Andes that transitional terms morphology and foreland tectonics (33–37°S). piedmont reach river flows eastwards between main mountain front San Rafael Block (the southernmost uplift to east Andes). Unlike adjacent rivers, has incised into pre-Quaternary bedrock form deep canyon across piedmont. Five fill strath terraces were mapped, correlated, surveyed along ∼35 km determine their paleo-long profiles. Chronological data for provided by geochemical correlation interbedded tephras previously dated ignimbrite, as well eight cosmogenic 10Be ages, suggest synchronous relationship terrace deposition glaciation upstream. Terraces are tentatively correlated with oxygen isotope stages 16 (Qt1), 12 (Qt2), 4 (Qt3) 2 (Qt4 Qt5). Minor spatial variation incision apparent from long profile Qt2 (∼450 ka), which shows low-amplitude folding. long-term average rate estimated be ∼0.1–0.5 m/kyr recent shorter term (post-OIS 2) at ∼2 m/kyr. Mid late Quaternary area likely cause incision; however, other possible explanations include delayed response pre-mid uplift, or changes climate sediment supply on tectonically stable portion flanked subsiding basins. Base-level fall due subsidence eastern side creating westward migrating knickzone may have contributed incision, but depth greater than observed no major present modern study reach. Studies such this geomorphic processes important understanding topographic tectonic transitions characterise Andes.