Growth and steady state of the Patagonian Andes

Colwyn, David Auerbach; Brandon, M. T.; Hren, Michael T.; Hourigan, J. K.; Pacini, Astrid; Cosgrove, M.; Midzik, Maya; Garreaud, René D.; Metzger, C. A.

doi:10.2475/06.2019.01

Cited by 21 publications

(11 citation statements)

References 144 publications

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“…The proportion of granitic clasts is 5 to 20% in these deposits. The present surface exposures of the batholith have igneous ages of 155 to 115 Ma and igneous pressures indicating initial emplacement at depths of ~10 km (18). There are minor intrusions with ages as young as 10 Ma (18), although these were emplaced well below the AHe closure depth.…”

Section: Geologic Setting and Sampling Locationsmentioning

confidence: 66%

“…LGM ice divide Published bedrock ages (used in Fig. 3 In contrast to proposed CTJ-associated tectonic and thermal effects, a recent paleotopography study (18) shows that the topography around 46°S, the latitude of the CTJ, has been steady over the past 60 Ma. In another nearby study, the authors demonstrate that the region east of CTJ has been a site of relatively slow erosion and uplift over the past 6 Ma, except for a period of fast valley incision associated with the onset of glaciation (16).…”

Section: O F Z Ctjmentioning

confidence: 99%

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Transient glacial incision in the Patagonian Andes from ~6 Ma to present

Willett

Brandon

et al. 2020

Sci. Adv.

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We report a mountain-scale record of erosion rates in the central Patagonian Andes from >10 million years (Ma) ago to present, which covers the transition from a fluvial to alpine glaciated landscape. Apatite (U-Th)/He ages of 72 granitic cobbles from alpine glacial deposits show slow erosion before ~6 Ma ago, followed by a two- to threefold increase in the spatially averaged erosion rate of the source region after the onset of alpine glaciations and a 15-fold increase in the top 25% of the distribution. This transition is followed by a pronounced decrease in erosion rates over the past ~3 Ma. We ascribe the pulse of fast erosion to local deepening and widening of valleys, which are characteristic features of alpine glaciated landscapes. The subsequent decline in local erosion rates may represent a return toward a balance between rock uplift and erosion.

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Section: Geologic Setting and Sampling Locationsmentioning

confidence: 66%

Section: O F Z Ctjmentioning

confidence: 99%

Transient glacial incision in the Patagonian Andes from ~6 Ma to present

Willett

Brandon

et al. 2020

Sci. Adv.

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“…Even though no radiometric ages are reported here for the metamorphism of the studied rocks, some limits may be inferred if we take into account its relationship suggesting the existence of an emerged ridge of plutonic rocks marking the eastern border of the marine basins. Colwyn et al (2019) also postulate the existence of a topographic barrier similar to the modern mountain range, to explain a rain shadow in extra-Andean Patagonia indicated by δD isotope data, at least since Paleocene times. to Neogene magmatism in the area (Fig.…”

Section: Age Constraints On the Metamorphism Of The Traiguén Formatiomentioning

confidence: 82%

Mid-Cenozoic SHRIMP U-Pb detrital zircon ages from metasedimentary rocks in the North Patagonian Andes of Aysén, Chile

Quezada

Hervé

Calderón

et al. 2021

andgeo

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Previously undated low-grade metamorphic rocks from the Puerto Cisnes-Queulat area (44°30’ S) contain detrital zircons of mid-Oligocene age (ca. 28 Ma). Their outcrops represent the easternmost occurrence of the late Oligocene to early Miocene marine volcano-sedimentary Traiguén Formation; previous correlation with the Paleozoic metamorphic basement of this sector of the North Patagonian Andes is thus refuted. A similar age and provenance were obtained for a paraconglomerate bed of the La Junta Formation ca. 80 km to the north, which is thought to represent a high-energy lateral facies variation of the Traiguén Formation. Miocene plutonic rocks of the North Patagonian Batholith intruded these metasedimentary rocks, generating a contact metamorphic aureole that reaches biotite grade and overprints a previous metamorphic fabric probably formed during closure of the Traiguén Basin. Similar young ages for metamorphic rocks located immediately west of the Liquiñe-Ofqui Fault Zone 300 km north, near Ayacara, suggest a regional pattern of earliest Neogene metamorphism and rapid exhumation in this segment of the Patagonian Andes.

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“…In the southern (Patagonian) Andes ( Fig. 1 , domain 7), uplift initiated the earliest, at around 100 Ma (Dalziel et al 1974; Bruhn and Dalziel, 1977, Kohn et al 1995, Fosdick et al 2011; Horton 2018), and modern elevations were reached at around 55 Ma (Colwyn et al 2019). During the Miocene, the southern part of the orogen experienced additional uplift, primarily through expanding its width (Davis et al 1983; Blisniuk et al 2005, 2006; Giambiali et al 2016).…”

Section: Methodsmentioning

confidence: 99%

“…Moreover, since the studies of Gregory-Wodzicki (1998;2000) and Garzione et al (2008), a wealth of paleoaltimetry datasets has been published, depicting a much more complex picture (e.g. Bershaw et al 2010;Leier et al 2013;Canavan et al 2014;Carrapa et al 2014;Garzione et al 2014;Hoke et al 2014;Saylor and Horton 2014;Quade et al 2015;Anderson et al 2015Anderson et al , 2016Fiorella et al 2015;Kar et al 2016;Rohrmann et al 2016;Colwyn et al 2019). This body of work, compiled and summarized in Boschman (2021), shows that (i) topography was already in place in Patagonia and in the western ranges along the Pacific coast during the Late Cretaceous and Paleogene, (ii) most of the central and eastern ranges were uplifted during the last 50 to 30 Myr, and (iii) uplift migrated further eastwards towards the Subandean zone in the last 10 Myr (Fig.…”

Section: Introductionmentioning

confidence: 99%

Mountain radiations are not only rapid and recent: Ancient diversification of South American frog and lizard families related to Paleogene Andean orogeny and Cenozoic climate variations

Boschman

Condamine

2021

Preprint

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Mountainous areas host a disproportionately large fraction of Earth's biodiversity, suggesting a causal relationship between mountain building and biological diversification. Mountain clade radiations are generally associated with environmental heterogeneity, and with ecological opportunities created during the formation of high-elevation habitats. In South America, most documented Andean clade radiations are recent (Neogene) and rapid. However, so far only few studies have explicitly linked Andean elevation to species diversification. Here, we present a curve of Andean elevation based on a recent compilation of paleo-elevational data back to the Late Cretaceous, and analyse the diversification history of six Andean frog and lizard families that originated equally far back in time. For two clades (Aromobatidae and Leptodactylidae), we find that they diversified most rapidly during the early phase of mountain building (Late Cretaceous - Paleogene), when the first high-elevation habitats emerged in South America. The diversification of two other clades (Centrolenidae and Dendrobatidae) are correlated with Cenozoic temperature variations, with higher speciation (and for Dendrobatidae, also higher extinction) rates during warm periods. The last two clades (Hemiphractidae and Liolaemidae) are best explained by environment-independent diversification, although for Liolaemidae, an almost equally strong positive correlation was found between speciation and Andean elevation since the late Eocene. Our findings imply that throughout the long-lived history of surface uplift in the Andes, mountain building drove the diversification of different clades at different times, while not directly affecting other clades. Our study illustrates the importance of paleogeographic reconstructions that capture the complexity and heterogeneity of mountain building in our understanding of the effects that a changing environment plays in shaping biodiversity patterns observed today.

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Growth and steady state of the Patagonian Andes

Cited by 21 publications

References 144 publications

Transient glacial incision in the Patagonian Andes from ~6 Ma to present

Transient glacial incision in the Patagonian Andes from ~6 Ma to present

Mid-Cenozoic SHRIMP U-Pb detrital zircon ages from metasedimentary rocks in the North Patagonian Andes of Aysén, Chile

Mountain radiations are not only rapid and recent: Ancient diversification of South American frog and lizard families related to Paleogene Andean orogeny and Cenozoic climate variations

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