Abstract:
This paper shows a model of distribution of segmented alluvial fans also called telescopic in two tributaries basins of the San Juan River, within precordilleran mountainous area, at the central part of the province of San Juan, Argentina. These basins lies between 31º 31´ 23¨ S and 68º 53` 44” W and the 31º31’04´´S and 68º55`20´ W, from 926 to 905 m.a.s.l. altitude. Through analysis satellites images and aerial photographs interpretation, the morphografic and morphometric measurements were made in each one of the fans-terraces. Some results allow that a minimum participation of the tectonic modern activity, only from the fan-terrace 2 to fan-terrace 3 presents a break into slope basin that could be explain as neotectonic action. The essays of laboratory were obtained by means of flows with different relations of w/s (water versus detritus load) and without variations in basin slope. These flows built four fans-terraces models. The successions flows of different w/s would be the predominant cause of the segmented landforms. The processes would be linked to colder episodes, with abundant production of detritic and crioclastic load, and then warmer and humid episodes, contribute to transport its. These telescopic fans would answer to a periglacial model installed in the Precordillera ranges, near to Andes Central chains. It summarize that the training of the distinct levels of fans-terraces that compose a telescopic system owe to differences in the relation loads sedimentary versus availability of water and that the each fans no always have minor ages waters down.
Keywords:
Flows; laboratory essays; causes of training; periglacial fans models; morphometry