The role of the upper and lower plates in the Andean orogeny: insights from field observations to numerical modeling

BARRIONUEVO, M.; MESCUA, J.; BABEYKO, A.; SOBOLEV, S.; GIAMBIAGI, L.B.; QUINTEROS, J.; YAGUPSKY, D.L.

Congreso; XV Congreso Geológico Chileno; 2018

The Southern Central Andes shows a pronounced latitudinal variation in the structural pattern with a decrease in shortening and orogenicZLGWKIURP|6WR|62QHRIWKHPRVWLPSRUWDQWIDFWRUVLQYRNHGIRUFRQWUROOLQJWKHGHIRUPDWLRQLVWKHVXEGXFWLRQGQDPLFVZLWKDVODEDQJOHLQFUHDVHIURPDIODWVODEVHJPHQWEHWZHHQ||6WRDQRUPDOVXEGXFWLRQDQJOHLQ||6´HVSLWHWKLVPDLQFRQWUROthere are other factors that can control deformation, such as the strength of the upper plate. This have been proposed previously for this]RQHDVZHOODVIRUWKH$OWLSODQR3XQDUHJLRQ:KLOVWLQWKHSODWHDXUHJLRQSUHYLRXVQXPHULFDOVWXGLHVFRQdUPHGWKHKSRWKHVLVWKDWlithospheric and sediment strength of upper plate have effects on the deformation patterns, in the 30-36ºS segment it was not tested.%DVHG RQ dHOG JHRORJLFDO DQG JHRSKVLFDO REVHUYDWLRQV DORQJ WKH | 6 WUDQVHFW ZH KDYH FRQVWUXFWHG D FRQFHSWXDO PRGHOwhich reflects the present-day orogenic structure. In this zone the Malargüe fold-and-thrust belt developed under AndeanFRQWUDFWLRQ DV D WKLFNVNLQQHG EHOW +HUH WKH GHIRUPDWLRQ LV DFFRPPRGDWHG E WKH LQWHUDFWLRQ EHWZHHQ SUHDQGHDQ IDXOWV(related to the rifting phase in Neuquén basin) which are inverted and newly created reverse faults. This rifting phase couldhave changed the structure of the upper plate by thinning of the crust and corresponding strengthening of the lithosphere.:HdUVWO DSSO ODUJHVFDOHWKHUPRPHFKDQLFDO´PRGHOVWRHYDOXDWH WKH UROH RI WKHFKDQJLQJ VXEGXFWLQJ VODE DQJOH ,Q WKHPRGHOWKHNLQHPDWLFERXQGDUFRQGLWLRQLVSUHVFULEHGWRWKHVODEWRPLPLFVXEGXFWLRQZLWKFRQWUROOHGDQGFKDQJLQJVXEGXFWLRQangle. In the second part we study the influence of spatial material property variations of the South American plate on the Andeandeformation. In particular, we investigate deformation behavior with different compositions and geometries of upper plate during theVKRUWHQLQJ6LQFHWKHVHGLPHQWODHULVPXFKWKLQQHUWKDQWKHHQWLUHOLWKRVSKHUHWKHUHVKRXOGEHVXIdFLHQWQXPEHURIdQLWHHOHPHQWVWRWUDFNWKHVHGLPHQWGHIRUPDWLRQLQWKHQXPHULFDOVLPXODWLRQ7KHUHIRUHZHIXUWKHUH[SORUHWKHGHYHORSPHQWRIWKLQVNLQQHGDQGRUWKLFNVNLQQHGEHOWVLQWKHXSSHUPRVWFUXVWEXVLQJKLJKUHVROXWLRQOHVVWKDQPSHUHOHPHQWRQWKHJULGVKRUWHQLQJPRGHOV