IDEAN   23403
INSTITUTO DE ESTUDIOS ANDINOS "DON PABLO GROEBER"
Unidad Ejecutora - UE
artículos
Título:
Structure and development of the Andean system between 36-39ºS.
Autor/es:
ROJAS VERA, E.A., FOLGUERA, A., ZAMORA VALCARCE, G., BOTTESI, G. Y RAMOS, V.A.
Revista:
JOURNAL OF GEODYNAMICS
Editorial:
PERGAMON-ELSEVIER SCIENCE LTD
Referencias:
Lugar: Amsterdam; Año: 2014 vol. 73 p. 34 - 52
ISSN:
0264-3707
Resumen:
tOne of the main morphological changes along the Southern Central Andes occurs from 36◦to 39◦S. Thenorthern portion is characterized by prominent basement structures and a thick-skinned orogenic frontwith relief of over 2000 m with a deep level of exhumation where more than 4 km of section has beeneroded. Contrastingly, the southern part is formed by mildly inverted basement structures restrictedmainly to the hinterland zone, which reaches only 1500?1700 m relief. We quantify the variable contrib-utions of two main contractional stages through the construction of three regionally balanced sectionsacross the Andes, constrained by field and geophysical data. Extensional re-activation described for thissegment in late Oligocene-early Miocene and Pliocene to Quaternary times, after the two main contrac-tional episodes, suggests only 3 km of stretching that represents 30?10% of the original longitude. We,therefore, conclude that while initial Late Cretaceous to Eocene compression was similar along strike(∼10?7 km), it is the contrasting degrees of Neogene shortening (∼16?6 km) that have played the largestrole in the along strike differences in structure and morphology along this portion of the southern Andes.Variable Neogene arc expansion could be responsible for the contrasting contractional deformation: Inthe north, late Miocene arc-related rocks cover most of the retroarc zone (>200 km with respect to thelate Miocene arc front in the south), presumably driven by a shallow subduction episode in the area,whereas to the south they remain restricted to the continental drainage divide. Other factors involv-ing architecture of previous rift structures, are proposed as additional mechanisms that accommodatedvariable shortening magnitudes through inversion.