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Earth-science reviews, 2009-12, Vol.97 (1), p.105-132
2009

Details

Autor(en) / Beteiligte
Titel
End member models for Andean Plateau uplift
Ist Teil von
  • Earth-science reviews, 2009-12, Vol.97 (1), p.105-132
Ort / Verlag
Amsterdam: Elsevier B.V
Erscheinungsjahr
2009
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals Complete
Beschreibungen/Notizen
  • Diverse techniques have been applied over the past decade to quantify the uplift history of the central Andean Plateau (AP). In this study, opposing models for surface uplift are evaluated including: a rapid rise of ∼ 2.5 km ∼ 10–6 Ma and a slow and steady rise since ∼ 40 Ma. These end member models are evaluated by synthesizing observations of the AP lithosphere and the history of deformation, sedimentation, exhumation, magmatism, uplift, and fluvial incision. Structural and geophysical studies estimate variable shortening magnitudes (∼ 530–150 km) involving cover-to-basement rocks, an isostatically-compensated thick crust (∼ 80–65 km), high heat flow, and zones of variable velocity and attenuation in the crust and mantle. These observations have invoked interpretations such as a hot/weak lithosphere, partial melt, crustal flow, and perhaps current, localized delamination, but do not provide strong support for massive delamination required by the rapid uplift model. Deformation and associated exhumation began ∼ 60–40 Ma and generally migrated eastward with consistent long-term average shortening rates (∼ 12–8 mm/yr) in Bolivia, favoring the slow uplift model. Volcanic and helium isotope evidence show an AP-wide zone of shallow mantle melting and thin lithosphere that has existed since ∼ 25 Ma, which is inconsistent with the rapid rise model that suggests lithospheric thinning occurred 10–6 Ma. Paleoaltimetry data suggest a rapid ∼ 2.5 km elevation gain 10 to 6 Ma, but are equally consistent within error with a linear rise since ≥ 25 Ma. Widespread fluvial incision (2.5–1 km) occurred along the western flank since ∼ 11–8 Ma and may be associated with surface uplift as proposed by the rapid rise model. However, the paleoaltimetry and incision data can also be explained by regional climate change associated with plateau uplift. Implications of these results for reconstructions of AP evolution are that: (1) substantial deformation of a weak lithosphere is essential, (2) AP growth has taken significantly longer (≥ 40 Myr) and was more uniform along strike (∼ 1500 km) than previously appreciated, and (3) the slow and steady uplift model is most consistent with available constraints. We conclude that the rapid uplift model may be an overestimate and that a more protracted Cenozoic uplift history is tenable.
Sprache
Englisch
Identifikatoren
ISSN: 0012-8252
eISSN: 1872-6828
DOI: 10.1016/j.earscirev.2009.08.003
Titel-ID: cdi_proquest_miscellaneous_1266745263

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