The Andean margin is the plate-tectonic paradigm for long-lived, continuous subduction, yet its geology since the late Mesozoic era (the past 100 million years or so) has been far from steady state. The episodic deformation and magmatism have been attributed to cyclic changes in the dip angle of the subducting slab, slab break-off and the penetration of the slab into the lower mantle; the role of plate tectonics remains unclear, owing to the extensive subduction of the Nazca–Farallon plate (which has resulted in more than 5,500 kilometres of lithosphere being lost to the mantle). Here, using tomographic data, we recreate the plate-tectonic geometry of the subducted Nazca slab, which enables us to reconstruct Andean plate tectonics since the late Mesozoic. Our model suggests that the current phase of Nazca subduction began at the northern Andes (5° S) during the late Cretaceous period (around 80 million years ago) and propagated southwards, reaching the southern Andes (40° S) by the early Cenozoic era (around 55 million year ago). Thus, contrary to the current paradigm, Nazca subduction has not been fully continuous since the Mesozoic but instead included episodic divergent phases. In addition, we find that foredeep sedimentation and the initiation of Andean compression are both linked to interactions between the Nazca slab and the lower mantle, consistent with previous modelling.
Access optionsAccess options
Subscribe to Journal
Get full journal access for 1 year
only $3.90 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
The data that support the findings of this study are available within the paper.
Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Mpodozis, C. & Ramos, V. in Geology of the Andes and its Relation to Hydrocarbon and Mineral Resources (eds Ericksen, G. E., Cañas Pinochet, M. T. & Reinemud, J. A.) 59–90 (Circum-Pacific Council for Energy and Mineral Resources, 1989).
van der Meer, D. G., Spakman, W., Van Hinsbergen, D. J., Amaru, M. L. & Torsvik, T. H. Towards absolute plate motions constrained by lower-mantle slab remnants. Nat. Geosci. 3, 36–40 (2010).
Müller, R. D. et al. Ocean basin evolution and global-scale plate reorganization events since Pangea breakup. Annu. Rev. Earth Planet. Sci. 44, 107–138 (2016).
Haschke, M. R., Scheuber, E., Günther, A. & Reutter, K. J. Evolutionary cycles during the Andean orogeny: repeated slab breakoff and flat subduction? Terra Nova 14, 49–55 (2002).
Horton, B. K. & Fuentes, F. Sedimentary record of plate coupling and decoupling during growth of the Andes. Geology 44, 647–650 (2016).
Ramos, V. A. & Folguera, A. Andean flat-slab subduction through time. Geol. Soc. Lond. Spec. Publ. 327, 31–54 (2009).
Ramos, V. A. & Kay, S. M. in Evolution of an Andean Margin: A Tectonic and Magmatic View from the Andes to the Neuquén Basin (35°–39°S lat) (eds Kay, S. M. & Ramos, V. A.) 1–18 (Geological Society of America, Boulder, 2006).
Faccenna, C., Oncken, O., Holt, A. F. & Becker, T. W. Initiation of the Andean orogeny by lower mantle subduction. Earth Planet. Sci. Lett. 463, 189–201 (2017).
Schellart, W. P. Andean mountain building and magmatic arc migration driven by subduction-induced whole mantle flow. Nat. Commun. 8, 2010 (2017).
Li, C., van der Hilst, R. D., Engdahl, E. R. & Burdick, S. A new global model for P wave speed variations in Earth’s mantle. Geochem. Geophys. Geosyst. 9, Q05018 (2008).
Scire, A., Zandt, G., Beck, S., Long, M. & Wagner, L. The deforming Nazca slab in the mantle transition zone and lower mantle: constraints from teleseismic tomography on the deeply subducted slab between 6°S and 32°S. Geosphere 13, 665–680 (2017).
Scire, A., Biryol, C. B., Zandt, G. & Beck, S. Imaging the Nazca slab and surrounding mantle to 700 km depth beneath the central Andes (18°S to 28°S). Geol. Soc. Am. 212, 23–41 (2014).
Scire, A. et al. Imaging the transition from flat to normal subduction: variations in the structure of the Nazca slab and upper mantle under southern Peru and northwestern Bolivia. Geophys. J. Int. 204, 457–479 (2016).
Grand, S. P. Mantle shear structure beneath the Americas and surrounding oceans. J. Geophys. Res. Solid Earth 99, 11591–11621 (1994).
Ren, Y., Stutzmann, E., van Der Hilst, R. D. & Besse, J. Understanding seismic heterogeneities in the lower mantle beneath the Americas from seismic tomography and plate tectonic history. J. Geophys. Res. Solid Earth 112, B01302 (2007).
Quinteros, J. & Sobolev, S. V. Why has the Nazca plate slowed since the Neogene? Geology 41, 31–34 (2013).
Horton, B. K. et al. Andean stratigraphic record of the transition from backarc extension to orogenic shortening: a case study from the northern Neuquén basin, Argentina. J. S. Am. Earth Sci. 71, 17–40 (2016).
Horton, B. K. Sedimentary record of Andean mountain building. Earth Sci. Rev. 178, 279–309 (2018).
Horton, B. K. Tectonic regimes of the central and southern Andes: responses to variations in plate coupling during subduction. Tectonics 37, 402–429 (2018).
Ribe, N. M., Stutzmann, E., Ren, Y. & van der Hilst, R. Buckling instabilities of subducted lithosphere beneath the transition zone. Earth Planet. Sci. Lett. 254, 173–179 (2007).
Wu, J., Suppe, J., Lu, R. & Kanda, R. Philippine Sea and East Asian plate tectonics since 52 Ma constrained by new subducted slab reconstruction methods. J. Geophys. Res. Solid Earth 121, 4670–4741 (2016).
Boyden, J. A. et al. in Geoinformatics: Cyberinfrastructure for the Solid Earth Sciences (eds Baru, C. & Keller, G. R.) 95–114 (Cambridge Univ. Press, Cambridge, 2011).
Schepers, G. et al. South-American plate advance and forced Andean trench retreat as drivers for transient flat subduction episodes. Nat. Commun. 8, 15249 (2017).
McQuarrie, N. Initial plate geometry, shortening variations, and evolution of the Bolivian orocline. Geology 30, 867–870 (2002).
Steinberger, B., Torsvik, T. H. & Becker, T. W. Subduction to the lower mantle – a comparison between geodynamic and tomographic models. Solid Earth 3, 415–432 (2012).
Shephard, G. E., Matthews, K. J., Hosseini, K. & Domeier, M. On the consistency of seismically imaged lower mantle slabs. Sci. Rep. 7, 10976 (2017).
Seton, M. et al. Global continental and ocean basin reconstructions since 200 Ma. Earth Sci. Rev. 113, 212–270 (2012).
Wright, N. M., Seton, M., Williams, S. E. & Müller, R. D. The late Cretaceous to recent tectonic history of the Pacific Ocean basin. Earth Sci. Rev. 154, 138–173 (2016).
Matthews, K. J. et al. Geologic and kinematic constraints on late Cretaceous to mid Eocene plate boundaries in the southwest Pacific. Earth Sci. Rev. 140, 72–107 (2015).
Lallemand, S., Heuret, A. & Boutelier, D. On the relationships between slab dip, back-arc stress, upper plate absolute motion, and crustal nature in subduction zones. Geochem. Geophys. Geosyst. 6, Q09006 (2005).
Fennell, L. M. et al. Cretaceous deformation of the southern central Andes: synorogenic growth strata in the Neuquén Group (35° 30′–37° S). Basin Res. 29, 51–72 (2015).
Zaffarana, C. B., Lagorio, S. L. & Somoza, R. Paleomagnetism and geochemistry from the Upper Cretaceous Tres Picos Prieto locality (43°S), Patagonian plateau basalts. Andean Geol. 39, 53–66 (2012).
Kay, S. M., Gorring, M. & Ramos, V. A. Magmatic sources, setting and causes of Eocene to recent Patagonian plateau magmatism (36°S to 52°S latitude). Rev. Asoc. Geol. Argent. 59, 556–568 (2004).
Maloney, K. T., Clarke, G. L., Klepeis, K. A. & Quevedo, L. The Late Jurassic to present evolution of the Andean margin: drivers and the geological record. Tectonics 32, 1049–1065 (2013).
Goes, S., Agrusta, R., van Hunen, J. & Garel, F. Subduction-transition zone interaction: a review. Geosphere 13, 644–664 (2017).
Burns, W. M., Jordan, T. E., Copeland, P. & Kelley, S. A. The case for extensional tectonics in the Oligocene-Miocene southern Andes as recorded in the Cura Mallín basin (36–38 S). Geol. Soc. Am. Spec. Pap. 407, 163–184 (2006).
Charrier, R. et al. Evidence for Cenozoic extensional basin development and tectonic inversion south of the flat-slab segment, southern Central Andes, Chile (33–36 SL). J. S. Am. Earth Sci. 15, 117–139 (2002).
Folguera, A., Rojas Vera, E., Bottesi, G., Zamora Valcarce, G. & Ramos, V. A. The Loncopué trough: a Cenozoic basin produced by extension in the southern Central Andes. J. Geodyn. 49, 287–295 (2010).
Tunik, M., Folguera, A., Naipauer, M., Pimentel, M. & Ramos, V. A. Early uplift and orogenic deformation in the Neuquén basin: constraints on the Andean uplift from U–Pb and Hf isotopic data of detrital zircons. Tectonophysics 489, 258–273 (2010).
Pfiffner, O. & Gonzalez, L. Mesozoic–Cenozoic evolution of the western margin of South America: case study of the Peruvian Andes. Geosciences 3, 262–310 (2013).
Poblete, F. et al. Late Cretaceous–early Eocene counterclockwise rotation of the Fueguian Andes and evolution of the Patagonia–Antarctic Peninsula system. Tectonophysics 668–669, 15–34 (2016).
Bascuñán, S., Arriagada, C., Le Roux, J. & Deckart, K. Unraveling the Peruvian phase of the central Andes: stratigraphy, sedimentology and geochronology of the Salar de Atacama basin (22°30–23°S), northern Chile. Basin Res. 28, 365–392 (2016).
Hoffmann-Rothe, A. et al. in The Andes: Active Subduction Orogeny (eds Oncken, O. et al.) 125–146 (Springer, Berlin, 2006).
Haschke, M. et al. in The Andes: Active Subduction Orogeny (eds Oncken, O. et al.) 337–353 (Springer, Berlin, 2006).
Somoza, R. & Zaffarana, C. B. Mid-Cretaceous polar standstill of South America, motion of the Atlantic hotspots and the birth of the Andean cordillera. Earth Planet. Sci. Lett. 271, 267–277 (2008).
Ramos, V. A. Anatomy and global context of the Andes: main geologic features and the Andean orogenic cycle. Geol. Soc. Am. 204, 31–65 (2009).
Sigloch, K. & Mihalynuk, M. G. Intra-oceanic subduction shaped the assembly of Cordilleran North America. Nature 496, 50–56 (2013).
Matthews, K. J., Seton, M. & Müller, R. D. A global-scale plate reorganization event at 105–100 Ma. Earth Planet. Sci. Lett. 355–356, 283–298 (2012).
Folguera, A. et al. A review of late Cretaceous to Quaternary palaeogeography of the southern Andes. Biol. J. Linn. Soc. 103, 250–268 (2011).
Ramos, V. A. & Folguera, A. Tectonic evolution of the Andes of Neuquén: constraints derived from the magmatic arc and foreland deformation. Geol. Soc. Lond. Spec. Publ. 252, 15–35 (2005).
Parada, M. A. et al. Mesozoic and Cenozoic plutonic development in the Andes of central Chile (30°30′–32°30′S). J. S. Am. Earth Sci. 1, 249–260 (1988).
Folguera, A. et al. Retroarc volcanism in the northern San Rafael Block (34°–35°30′S), southern Central Andes: occurrence, age, and tectonic setting. J. Volcanol. Geotherm. Res. 186, 169–185 (2009).
Hafkenscheid, E., Wortel, M. J. R. & Spakman, W. Subduction history of the Tethyan region derived from seismic tomography and tectonic reconstructions. J. Geophys. Res. Solid Earth 111, B08401 (2006).
Dziewonski, A. M. & Anderson, D. L. Preliminary reference Earth model. Phys. Earth Planet. Inter. 25, 297–356 (1981).
Li, C. Evolution of Upper Mantle Beneath East Asia and the Tibetan Plateau from P-wave Tomography. PhD thesis, Massachusetts Institute of Technology (2007).
Aguirre, L. & Offler, R. in Magmatism at a plate edge: the Peruvian margin (eds Pitcher, W. S. et al.) 59–71 (Springer, New York, 1985).
Mukasa, S. B. Zircon U-Pb ages of super-units in the Coastal batholith, Peru: implications for magmatic and tectonic processes. Geol. Soc. Am. Bull. 97, 241–254 (1986).
Demouy, S. et al. Spatial and temporal evolution of Liassic to Paleocene arc activity in southern Peru unraveled by zircon U–Pb and Hf in-situ data on plutonic rocks. Lithos 155, 183–200 (2012).
Jones, R. E. et al. Geodynamic controls on the contamination of Cenozoic arc magmas in the southern Central Andes: insights from the O and Hf isotopic composition of zircon. Geochim. Cosmochim. Acta 164, 386–402 (2015).
Parada, M. A. et al. in The Geology of Chile (eds Moreno, T. & Gibbons, W.) 115–146 (Geological Society of London, London, 2007).
Di Giulio, A. et al. Detrital zircon provenance from the Neuquén basin (south-central Andes): Cretaceous geodynamic evolution and sedimentary response in a retroarc-foreland basin. Geology 40, 559–562 (2012).
Munizaga, F. et al. Geochronology of the lake region of south-central Chile (39°–42°S): preliminary results. J. S. Am. Earth Sci. 1, 309–316 (1988).
Aragón, E., Castro, A., Díaz-Alvarado, J. & Liu, D. Y. The North Patagonian batholith at Paso Puyehue (Argentina-Chile). SHRIMP ages and compositional features. J. S. Am. Earth Sci. 32, 547–554 (2011).
Pankhurst, R. J., Weaver, S. D., Herve, F. & Larrondo, P. Mesozoic-Cenozoic evolution of the North Patagonian Batholith in Aysen, southern Chile. J. Geol. Soc. Lond. 156, 673–694 (1999).
Bissig, T., Ullrich, T. D., Tosdal, R. M., Friedman, R. & Ebert, S. The time-space distribution of Eocene to Miocene magmatism in the central Peruvian polymetallic province and its metallogenetic implications. J. S. Am. Earth Sci. 26, 16–35 (2008).
Mamani, M., Wörner, G. & Sempere, T. Geochemical variations in igneous rocks of the central Andean orocline (13°S to 18°S): Tracing crustal thickening and magma generation through time and space. Geol. Soc. Am. Bull. 122, 162–182 (2010).
Boekhout, F. et al. Mesozoic arc magmatism along the southern Peruvian margin during Gondwana breakup and dispersal. Lithos 146–147, 48–64 (2012).
Stern, C. R. Active Andean volcanism: its geologic and tectonic setting. Rev. Geol. Chile 31, 161–206 (2004).
Kay, S. M., Burns, W. M., Copeland, P. & Mancilla, O. in Evolution of an Andean Margin: A Tectonic and Magmatic View from the Andes to the Neuquén Basin (35°–39°S lat) (eds Kay, S. M. & Ramos, V. A.) 19–60 (Geological Society of America, Boulder, 2006).
Hervé, F., Pankhurst, R. J., Fanning, C. M., Calderón, M. & Yaxley, G. M. The South Patagonian batholith: 150 my of granite magmatism on a plate margin. Lithos 97, 373–394 (2007).
Pilger, R. Radiometric Dates from the Andes - Pentecost 2018 - Link (2018).
Fukao, Y. & Obayashi, M. Subducted slabs stagnant above, penetrating through, and trapped below the 660 km discontinuity. J. Geophys. Res. Solid Earth 118, 5920–5938 (2013).
Amaru, M. Global Travel Time Tomography with 3-D Reference Models PhD thesis, Utrecht University (2007).
Simmons, N. A., Myers, S. C., Johannesson, G. & Matzel, E. LLNL-G3Dv3: global P wave tomography model for improved regional and teleseismic travel time prediction. J. Geophys. Res. Solid Earth 117, B10302 (2012).
French, S. & Romanowicz, B. Whole-mantle radially anisotropic shear velocity structure from spectral-element waveform tomography. Geophys. J. Int. 199, 1303–1327 (2014).
Grand, S. P. Mantle shear–wave tomography and the fate of subducted slabs. Philos. Trans. R. Soc. Lond. A 360, 2475–2491 (2002).
Hosseini, K. et al. SubMachine: web-based tools for exploring seismic tomography and other models of Earth’s deep interior. Geochem. Geophys. Geosyst. 19, 1464–1483 (2018).
Simmons, N. A., Forte, A. M., Boschi, L. & Grand, S. P. GyPSuM: a joint tomographic model of mantle density and seismic wave speeds. J. Geophys. Res. Solid Earth 115, (2010).
Houser, C., Masters, G., Shearer, P. & Laske, G. Shear and compressional velocity models of the mantle from cluster analysis of long-period waveforms. Geophys. J. Int. 174, 195–212 (2008).
Montelli, R., Nolet, G., Dahlen, F. A. & Masters, G. A catalogue of deep mantle plumes: new results from finite-frequency tomography. Geochem. Geophys. Geosyst. 7, Q11007 (2006).
Koelemeijer, P., Ritsema, J., Deuss, A. & van Heijst, H. J. SP12RTS: a degree-12 model of shear- and compressional-wave velocity for Earth’s mantle. Geophys. J. Int. 204, 1024–1039 (2016).
Tesoniero, A., Auer, L., Boschi, L. & Cammarano, F. Hydration of marginal basins and compositional variations within the continental lithospheric mantle inferred from a new global model of shear and compressional velocity. J. Geophys. Res. Solid Earth 120, 7789–7813 (2015).
Moulik, P. & Ekström, G. An anisotropic shear velocity model of the Earth’s mantle using normal modes, body waves, surface waves and long-period waveforms. Geophys. J. Int. 199, 1713–1738 (2014).
Ritsema, J., Deuss, A., van Heijst, H. J. & Woodhouse, J. H. S40RTS: a degree-40 shear-velocity model for the mantle from new Rayleigh wave dispersion, teleseismic traveltime and normal-mode splitting function measurements. Geophys. J. Int. 184, 1223–1236 (2011).
Auer, L., Boschi, L., Becker, T. W., Nissen-Meyer, T. & Giardini, D. Savani: a variable resolution whole-mantle model of anisotropic shear velocity variations based on multiple data sets. J. Geophys. Res. Solid Earth 119, 3006–3034 (2014).
Panning, M. P., Lekić, V. & Romanowicz, B. A. Importance of crustal corrections in the development of a new global model of radial anisotropy. J. Geophys. Res. Solid Earth 115, (2010).
Durand, S., Debayle, E., Ricard, Y., Zaroli, C. & Lambotte, S. Confirmation of a change in the global shear velocity pattern at around 1000 km depth. Geophys. J. Int. 211, 1628–1639 (2017).
Torsvik, T. H., Müller, R. D., Van der Voo, R., Steinberger, B. & Gaina, C. Global plate motion frames: toward a unified model. Rev. Geophys. 46, RG3004 (2008).
O’Neill, C., Müller, D. & Steinberger, B. On the uncertainties in hot spot reconstructions and the significance of moving hot spot reference frames. Geochem. Geophys. Geosyst. 6, Q04003 (2005).
Butterworth, N. P. et al. Geological, tomographic, kinematic and geodynamic constraints on the dynamics of sinking slabs. J. Geodyn. 73, 1–13 (2014).
Domeier, M., Doubrovine, P. V., Torsvik, T. H., Spakman, W. & Bull, A. L. Global correlation of lower mantle structure and past subduction. Geophys. Res. Lett. 43, 4945–4953 (2016).
Zahradník, J. et al. A recent deep earthquake doublet in light of long-term evolution of Nazca subduction. Sci. Rep. 7, 45153 (2017).
Goes, S., Capitanio, F. A. & Morra, G. Evidence of lower-mantle slab penetration phases in plate motions. Nature 451, 981–984 (2008).
Y.-W.C. and J.W. acknowledge support from University of Houston funds. J.S. acknowledges funding from Texas Governor’s University Research Initiative funds (GURI) and the University of Houston. Educational licences for the software Gocad were provided by Paradigm through the Paradigm University Program. We thank J. Saylor, B. K. Horton, C. Faccenna, S. M. Kay and M. Riesner for discussions.
Nature thanks D. Muller and the other anonymous reviewer(s) for their contribution to the peer review of this work.
Extended data figures and tables
The anomalies are shown in different tomographies within a UTM (Universal Transverse Mercator) projection at 400 km (left), 1,000 km (middle) and 1,200 km (right). Tomographies include: a, MITP0810; b, GAP-P472; c, UU-P0773; d, LLNL-G3Dv374; e, SEMUCB-WM175; and f, TX201176. dVp and dVs are the velocity perturbations (expressed as a percentage) from P-wave and S-wave tomography, respectively. g, Map26,77 of the number (out of 22) of global seismic tomography models that show fast velocity anomalies at a given location, which gives an indication of imaging robustness. The 22 tomographies include MITP0810, GAP-P472, UU-P0773, LLNL-G3Dv374, SEMUCB-WM175, TX201176, GyPSuM78, HMSL-P0679, PRI-P0580, SP12RTS-P81, SPani-P82, S362ANI+M83, S40RTS84, SAVANI85, SAW642ANb86 and SEISGLOB287. Overall, the northern Nazca slab shows a wider tomographic anomaly that is stronger in amplitude and extends deeper into the lower mantle relative to the southern slab.
a–f, East–west sections (see h) are shown from north to south. Red dots indicate Benioff zone seismicity. Yellow dashed lines show our manually selected Nazca slab edges that were primarily defined by steep velocity gradients. Poorly imaged areas identified by previous tomography studies are highlighted by white dashed lines11,12,13. g, A trench-parallel profile. Intersections with east–west profiles 1–6 are shown by red lines. h, Profile positions on a horizontal slice at a depth of 900 km within a UTM projection.
The method is outlined in ref. 21. a, A three-dimensional schematic view of highly deformed slabs in the lower mantle, for which we aim to assess the cross-sectional slab area and unfold the slabs to estimate the amount of subducted lithosphere. b, A three-dimensional schematic view showing the reconstructed slab lengths from a along two parallel cross-sections. Each of the slab sub-depth areas 1–8 have been retro-deformed to a notional pre-subduction thickness of 100 km and pieced back together at the Earth surface to assess a pre-subduction length. A density–depth correction (red area) has been applied to each slab sub-area following PREM54. c, An example MITP08 tomographic cross-section under the Andes and two possible Nazca slab areas based on different contour values: the blue dashed line is dVp = +0.3% and the red dashed line is dVp = +0.2%. d, Slab subduction ages implied by the dVp = 0.3% and dVp = 0.2% Nazca slab areas from c are 70 Myr and 90 Myr, respectively, determined from plate convergence rates from a global plate model3.
Extended Data Fig. 4 Cross-sectional area unfolding method applied to the other five tomographies at profile 2.
See Extended Data Fig. 2g for location. a, GAP-P472; b, UU-P0773; c, TX201176; d, LLNL-G3Dv374; and e, SEMUCB-WM175. Our choices of slab edges are shown as yellow dashed lines, with dVp = +0.3% in UU-P07 (b) and LLNL-G3Dv3 (d), dVp = +0.6% in GAP-P4 (a), dVs = +0.9% in TX2011 (c) and dVs = +0.7% in SEMUCB-WM1 (e). f, The unfolded slab lengths from the five tomographies, with our choices of slab edges shown as blue circles. Unfolded slab lengths from MITP08 in Extended Data Fig. 3d are shown as a yellow box. The unfolded slab lengths of an alternative slab area in GAP-P4 and TX2011 (red dashed lines in a and c) are shown as open dashed circles. Overall, the slab lengths from the six tomographies show similar results.
Implied lower-mantle sinking rates are shown by the circles and labels, coloured coded by tomographic profile. For comparison, we also plot lower-mantle sinking rates at the central Marianas Pacific slabs (light grey diamonds)21 and age–depth relationships of slabs under east Asia (dark grey diamonds)21. All sinking rates from this study are consistent with ref. 21, which found an average lower-mantle sinking rate of 1.8 ± 0.8 cm yr−1 (grey dashed lines).
Extended Data Fig. 6 Reconstructed Nazca trench positions between 100 Myr and 60 Myr ago within two alternative mantle reference frames.
Reconstructed trench positions are shown at 100 Myr ago (red lines), 80 Myr ago (white lines) and 60 Myr ago (yellow lines), superimposed on horizontal sections of MITP08 tomography10 within mid- to lower-mantle depths (a, b, 1,200 km; c, d, 1,400 km; e, f, 1,600 km). a, c, e, Reconstructions based on the mantle reference frame of ref. 88. b, d, f, Reconstructions based on the mantle reference frame of ref. 89.
a, 80 Myr ago; b, 70 Myr ago; c, 60 Myr ago; d, 50 Myr ago; e, 40 Myr ago; f, 30 Myr ago; g, 20 Myr ago; h, 10 Myr ago. Grey arrows indicate the motion of the subducting Nazca plate relative to South America. Divergent motions are shown by blue arrows. The position of the Nazca–South America plate boundary is based on the retro-deformed Andean margin from ref. 23. Subduction along the Nazca–South America plate boundary is highlighted by the thick red line; green and blue thick lines indicate transform and divergent plate boundaries, respectively. Other references are the same as in Fig. 4.
Extended Data Fig. 8 Comparison of Nazca–South America plate motions from alternative plate circuits.
a–c, Plate motions 80 Myr ago (a), 70 Myr ago (b) and 60 Myr ago (c) are shown from the Antarctic plate circuit27 (blue arrows) and the Australian plate circuit3 (orange arrows). In this study, we followed the plate motion derived from the Australian plate circuit3. The Australian circuit assumes limited motion between the Lord Howe Rise and the Pacific before the Eocene. This allows a motion chain to be built from East Antarctica to Australia to the Lord Howe Rise/Pacific, avoiding the less-well-constrained relative motion of East and West Antarctica, on which the Antarctic circuit is built (see ref. 29 for an in-depth discussion). Both models indicate coeval northern convergence and southern divergence, although the motions are different in the late Cretaceous (a and b). The position of the Nazca–South America plate boundary is based on the retro-deformed Andean margin (black dash lines)23. Subduction along the plate boundary is coloured in red; green and blue indicate transform and divergent plate boundaries, respectively (same as in Extended Data Fig. 7).
Slab lengths (SLs) are based on our plate model and measured over time between the leading edge of the subducted Nazca slab and the retro-deformed Andean margin23. A slab length of 0 km indicates Nazca subduction initiation. A slab length of 770 km indicates the earliest possible time that the Nazca slab could have reached the lower mantle, based on a sub-vertical Marianas slab end-member30. A slab length of 1,200 km indicates the latest possible time that the Nazca slab could have reached the lower mantle, based on a shallow-dipping Peruvian flat-slab end-member30. See main text for more details.
Extended Data Fig. 10 Sensitivity of our plate model to other possible slab lengths and their implied sinking rates.
a, Our plate model predictions are compared with a spatial density plot of total recorded Andean magmatic ages by latitude from a catalogue of undifferentiated Andean magmatic ages71 (14,709 total published magmatic ages since 140 Myr ago). The bin size is 4° in latitude and 5 Myr in age. This plot is designed to offer an alternative perspective to Fig. 5a. Differences between this plot and Fig. 5a result from our choice of including in Fig. 5a only magmatism that had an interpreted tectonic origin, for example, arc-related, backarc or intraplate magmatism. For Fig. 5a, published geochemical signatures provide a feature-by-feature comparison for each magmatic record that is absent from this plot. The near-white band 32° S and 45° S is not necessarily a magmatic gap, but is the result of limited reported ages, possibly owing to limited outcrop exposure. In Fig. 5a, we used detrital zircon ages to infer the magmatic activity for 32°–45° S. The thick red line shows our predicted southward propagation of Nazca subduction initiation (same as in Fig. 5a). The error range (±10 Myr) shown by transparent red lines come from alternative choices of slab-edge velocity perturbations (see Methods and Extended Data Fig. 3 for details). Overall, our model prediction fits well with a magmatic minimum around 80 Myr ago followed by increased magmatism, which we interpret to correspond to the initiation of the most recent phase of Nazca subduction. Arbitrarily decreased unfolded slab lengths of 80% (light blue dashed line) and 60% (dark blue dashed line) are also shown. The arbitrarily decreased slab lengths show the sensitivity of our plate model predictions to possible tomographic blurring, which would have exaggerated our measured Nazca slab areas. Comparison to the shorter unfolded slab lengths shows that southward propagation of Nazca subduction is preserved when Nazca slab lengths are decreased, but we argue that the alternative subduction initiation timings compare less well to the increased magmatism between 80 Myr and 60 Myr ago north of 32° S. Green dots show that the choice of a thinner initial lithosphere thickness for slab unfolding (80 km rather than 100 km) would increase slab lengths, which would effectively offset some tomographic blurring. b, Comparison between published lower-mantle slab sinking rates2,21,25,26,47,53,90,91 and the implied lower-mantle sinking rates for our preferred slab lengths (red line) and arbitrarily decreased 80% (light blue dashed line) and 60% (dark blue dashed line) slab lengths from a. Shorter slab lengths (less than 60%) were excluded from a on the basis of unreasonably fast slab sinking rates.
The GPlates digital file of the unfolded Nazca slab polygon used in Figure 3, Figure 4 and the Supplementary Video.
Video 1: Plate tectonic reconstruction of Nazca subduction under the Andes since 80 Ma from unfolded-slab plate tectonics.
A plate tectonic reconstruction animation of Nazca subduction at 1 Ma timesteps, as shown in Figure 4 and Extended Data Figure 7. See Figure 4 and the Methods section for references. A GPlates digital file of the retro-deformed Nazca slab polygon in the video can be found within the Supplementary Data.