Low-temperature thermochronologic trends across the central Andes, 21°S-28°S

P. W. Reiners, S. N. Thomson, A. Vernon, S. D. Willett, M. Zattin, J. Einhorn, G. Gehrels, J. Quade, D. Pearson, K. E. Murray, W. Cavazza

Research output: Chapter in Book/Report/Conference proceedingChapter

40 Scopus citations


In this paper, we merge more than 200 new apatite and zircon (U-Th)/He analyses and 21 apatite fission-track analyses from 71 new samples with previous published thermochronologic data using the same systems to understand the growth and largescale kinematics of the central Andes between 21°S and 28°S. In general, minimum dates decrease and the total range of dates increases from west to east across the range. Large variations in thermochronometer dates on the east side reflect high spatial gradients in depth of recent erosional exhumation. Almost nowhere in this part of the Andes has Cenozoic erosion exceeded ∼6-8 km, and in many places in the eastern half of the range, erosion has not exceeded 2-3 km, despite these regions now being 5-6 km above sea level. This means that west of the rapidly deforming and eroding eastern range front, uplift and erosion are largely decoupled as a result of meager precipitation, relatively low relief, internal drainage, and volcanic burial. We interpret the west-to-east pattern of decreasing minimum dates across the range as recording the time-transgressive eastward migration of a focused zone of deformation, erosion, and convergence between the South American plate and the eastern edge of the Andean orogenic plateau. At this scale, the thermochronologic data do not suggest major changes in rates of plateau propagation or shortening/convergence with time. We use the thermochronometer date-distance trend and a simple kinematic model to infer a rate of eastward propagation of deformation and plateau growth of 6-10 km/m.y. This plateau propagation model balances horizontal convergence, erosion, and crustal thickening and predicts rates of shortening and convergence between the Andes block and South American plate that are consistent with geologic and geodetic observations.

Original languageEnglish (US)
Title of host publicationGeodynamics of a Cordilleran Orogenic System
Subtitle of host publicationThe Central Andes of Argentina and Northern Chile
EditorsMihai N. Ducea, Mihai N. Ducea, Peter G. DeCelles, Paul A. Kapp, Barbara Carrapa
PublisherGeological Society of America
Number of pages35
ISBN (Electronic)9780813712123
StatePublished - 2015

Publication series

NameMemoir of the Geological Society of America
ISSN (Print)0072-1069

ASJC Scopus subject areas

  • Geology


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