Andean surface uplift constrained by radiogenic isotopes of arc lavas.

ABSTRACT: Climate and tectonics have complex feedback systems which are difficult to resolve and remain controversial. Here we propose a new climate-independent approach to constrain regional Andean surface uplift. ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd ratios of Quaternary frontal-arc lavas from the Andean Plateau are distinctly crustal (>0.705 and <0.5125, respectively) compared to non-plateau arc lavas, which we identify as a plateau discriminant. Strong linear correlations exist between smoothed elevation and ⁸⁷Sr/⁸⁶Sr (R²?=?0.858, n?=?17) and ¹⁴³Nd/¹⁴⁴Nd (R²?=?0.919, n?=?16) ratios of non-plateau arc lavas. These relationships are used to constrain 200?Myr of surface uplift history for the Western Cordillera (present elevation 4200?±?516?m). Between 16 and 26°S, Miocene to recent arc lavas have comparable isotopic signatures, which we infer indicates that current elevations were attained in the Western Cordillera from 23?Ma. From 23-10?Ma, surface uplift gradually propagated southwards by ~400?km.

SUBMITTER: Scott EM 

PROVIDER: S-EPMC5840411 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature