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Foundering of lower island-arc crust as an explanation for the origin of the continental Moho

Nature volume 504, pages 131–134 (2013)Cite this article

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Abstract

A long-standing theory for the genesis of continental crust is that it is formed in subduction zones1. However, the observed seismic properties of lower crust and upper mantle in oceanic island arcs2,3 differ significantly from those in the continental crust4. Accordingly, significant modifications of lower arc crust must occur, if continental crust is indeed formed from island arcs. Here we investigate how the seismic characteristics of arc crust are transformed into those of the continental crust by calculating the density and seismic structure of two exposed sections of island arc (Kohistan and Talkeetna). The Kohistan crustal section is negatively buoyant with respect to the underlying depleted upper mantle at depths exceeding 40 kilometres and is characterized by a steady increase in seismic velocity similar to that observed in active arcs. In contrast, the lower Talkeetna crust is density sorted, preserving only relicts (about ten to a hundred metres thick) of rock with density exceeding that of the underlying mantle. Specifically, the foundering of the lower Talkeetna crust resulted in the replacement of dense mafic and ultramafic cumulates by residual upper mantle, producing a sharp seismic discontinuity at depths of around 38 to 42 kilometres, characteristic of the continental Mohorovičić discontinuity (the Moho). Dynamic calculations indicate that foundering is an episodic process that occurs in most arcs with a periodicity of half a million to five million years. Moreover, because foundering will continue after arc magmatism ceases, this process ultimately results in the formation of the continental Moho.

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Figure 1: Seismic and petrological constraints on the thermal regime in arcs.
Figure 2: Detailed VP and density depth-structure of the exposed Kohistan arc section compared to the average continental crust and the Izu-Bonin arc crust.
Figure 3: Schematic illustrations of the lithological, seismic and density properties of the Kohistan and Talkeetna arc sections.
Figure 4: Modelled thickness of the density-unstable layer at the base of arc crust.

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References

  1. Taylor, S. R. & McLennan, S. M. The Continental Crust: Its Composition and Evolution (Blackwell, 1985)

    Google Scholar 

  2. Holbrook, W. S., Lizarralde, D., McGeary, S., Bangs, N. & Diebold, J. Structure and composition of the Aleutian island arc and implications for continental crustal growth. Geology 27, 31–34 (1999)

    ADS  Google Scholar 

  3. Calvert, A. in Arc–Continent Collision 87–119 (Springer, 2011)

    Google Scholar 

  4. Christensen, N. I. & Mooney, W. D. Seismic velocity structure and composition of the continental crust; a global view. J. Geophys. Res. B 100, 9761–9788 (1995)

    ADS  CAS  Google Scholar 

  5. Takahashi, N., Kodaira, S., Tatsumi, Y., Kaneda, Y. & Suyehiro, K. Structure and growth of the Izu-Bonin-Mariana arc crust: 1. Seismic constraint on crust and mantle structure of the Mariana arc-back-arc system. J. Geophys. Res. 113, B01104 (2008)

    ADS  Google Scholar 

  6. Tatsumi, Y. et al. Structure and growth of the Izu-Bonin-Mariana arc crust: 2. Role of crust-mantle transformation and the transparent Moho in arc crust evolution. J Geophys. Res. 113, B02203 (2008)

    ADS  Google Scholar 

  7. Shillington, D. J., Van Avendonk, H. J. A., Holbrook, W. S., Kelemen, P. B. & Hornbach, M. J. Composition and structure of the central Aleutian island arc from arc-parallel wide-angle seismic data. Geochem. Geophys. Geosyst. 5, Q10006 (2004)

    ADS  Google Scholar 

  8. Kay, R. W. & Mahlburg Kay, S. Delamination and delamination magmatism. Tectonophysics 219, 177–189 (1993)

    ADS  Google Scholar 

  9. Arndt, N. T. & Goldstein, S. L. An open boundary between lower continental crust and mantle: its role in crust formation and crustal recycling. Tectonophysics 161, 201–212 (1989)

    ADS  CAS  Google Scholar 

  10. Jagoutz, O. & Schmidt, M. W. The nature and composition of the crustal delaminate in arcs. Earth Planet. Sci. Lett. 371–372, 177–190 (2013)

    ADS  Google Scholar 

  11. Jagoutz, O. & Schmidt, M. W. The formation and bulk composition of modern juvenile continental crust: the Kohistan arc. Chem. Geol. 298–299, 79–96 (2012)

    ADS  Google Scholar 

  12. Sobolev, S. V. & Babeyko, A. Y. Phase transformations in the lower continental crust and its seismic structure. Geophys. Monogr. Ser. 51, 311–320 (1989)

    Google Scholar 

  13. Behn, M. D., Hirth, G. & Kelemen, P. B. Trench-parallel anisotropy produced by foundering of arc lower crust. Science 317, 108–111 (2007)

    ADS  CAS  PubMed  Google Scholar 

  14. Behn, M. D. & Kelemen, P. B. Stability of arc lower crust: insights from the Talkeetna arc section, south central Alaska, and the seismic structure of modern arcs. J. Geophys. Res. 111, B11207 (2006)

    ADS  Google Scholar 

  15. Jagoutz, O., Muentener, O., Schmidt, M. W. & Burg, J. P. The respective roles of flux- and decompression melting and their relevant liquid lines of descent for Continental Crust formation: evidence from the Kohistan arc. Earth Planet. Sci. Lett. 303, 25–36 (2011)

    ADS  CAS  Google Scholar 

  16. Kelemen, P., Rilling, J. L., Parmentier, E. M., Mehl, L. & Hacker, B. R. in Inside Subduction Factory Vol. 138, 293–311 (ed. Eiler, J. M. ) (Geophysical Monograph, American Geophysical Union, 2003)

    Google Scholar 

  17. Shillington, D. J., Van Avendonk, H. J. A., Behn, M. D., Kelemen, P. B. & Jagoutz, O. Constraints on the composition of the Aleutian arc lower crust from VP/VS . Geophys. Res. Lett. 40, 2579–2584 (2013)

    ADS  CAS  Google Scholar 

  18. Ringuette, L., Martignole, J. & Windley, B. F. Magmatic crystallization, isobaric cooling, and decompression of the garnet-bearing assemblages of the Jijal Sequence (Kohistan Terrane, western Himalayas). Geology 27, 139–142 (1999)

    ADS  CAS  Google Scholar 

  19. Hacker, B. R. et al. Reconstruction of the Talkeetna intraoceanic arc of Alaska through thermobarometry. J. Geophys. Res. 113, B03204 (2008)

    ADS  Google Scholar 

  20. Miller, D. J. & Christensen, N. I. Seismic signature and geochemistry of an island arc; a multidisciplinary study of the Kohistan accreted terrane, northern Pakistan. J. Geophys. Res. B 99, 11623–11642 (1994)

    ADS  Google Scholar 

  21. Kono, Y., Ishikawa, M., Harigane, Y., Michibayashi, K. & Arima, M. P- and S-wave velocities of the lowermost crustal rocks from the Kohistan arc: implications for seismic Moho discontinuity attributed to abundant garnet. Tectonophysics 467, 44–54 (2009)

    ADS  Google Scholar 

  22. Kelemen, P., Hanghoj, K. & Greene, A. in The Crust Vol. 3 Treatise on Geochemistry (ed. Rudnick, R. L. ) 593–659 (Elsevier-Pergamon, 2003)

    Google Scholar 

  23. Hacker, B. R., Kelemen, P. B. & Behn, M. D. Differentiation of the continental crust by relamination. Earth Planet. Sci. Lett. 307, 501–516 (2011)

    ADS  CAS  Google Scholar 

  24. Jull, M. & Kelemen, P. B. On the conditions for lower crustal convective instability. J. Geophys. Res. B 106, 6423–6446 (2001)

    ADS  CAS  Google Scholar 

  25. Conrad, C. P. & Molnar, P. The growth of Rayleigh-Taylor-type instabilities in the lithosphere for various rheological and density structures. Geophys. J. Int. 129, 95–112 (1997)

    ADS  Google Scholar 

  26. Conrad, C. P., Behn, M. D. & Silver, P. G. Global mantle flow and the development of seismic anisotropy: differences between the oceanic and continental upper mantle. J. Geophys. Res. 112, B07317 (2007)

    ADS  Google Scholar 

  27. Guggisberg, B., Kaminski, W. & Prodehl, C. Crustal structure of the Fennoscandian shield: a traveltime interpretation of the long-range FENNOLORA seismic refraction profile. Tectonophysics 195, 105–137 (1991)

    ADS  Google Scholar 

  28. Connolly, J. A. D. Computation of phase equilibria by linear programming: a tool for geodynamic modeling and its application to subduction zone decarbonation. Earth Planet. Sci. Lett. 236, 524–541 (2005)

    ADS  CAS  Google Scholar 

  29. Greene, A. R., DeBari, S. M., Kelemen, P., Blusztajn, J. S. & Clift Peter, D. A detailed geochemical study of island arc crust: the Talkeetna arc section, south–central Alaska. J. Petrol. 47, 1051–1093 (2006)

    ADS  CAS  Google Scholar 

  30. Hacker, B. R. & Abers, G. A. Subduction factory 3: an Excel worksheet and macro for calculating the densities, seismic wave speeds, and H2O contents of minerals and rocks at pressure and temperature. Geochem. Geophys. Geosyst. 5, Q01005 (2004)

    ADS  Google Scholar 

  31. Jagoutz, O. et al. TTG-type plutonic rocks formed in a modern arc batholith by hydrous fractionation in the lower arc crust. Contrib. Mineral. Petrol. 166, 1099–1118 (2013)

    ADS  CAS  Google Scholar 

  32. Kodaira, S. et al. New seismological constraints on growth of continental crust in the Izu-Bonin intra-oceanic arc. Geology 35, 1031–1034 (2007)

    ADS  Google Scholar 

  33. Jagoutz, O. & Schmidt, M. W. The formation and bulk composition of modern juvenile continental crust: the Kohistan arc. Chem. Geol. 298–299, 79–96 (2012)

    ADS  Google Scholar 

  34. Nakanishi, A. et al. Crustal evolution of the southwestern Kuril Arc, Hokkaido Japan, deduced from seismic velocity and geochemical structure. Tectonophysics 472, 105–123 (2009)

    ADS  CAS  Google Scholar 

  35. Kopp, H. et al. Deep structure of the central Lesser Antilles Island Arc: relevance for the formation of continental crust. Earth Planet. Sci. Lett. 304, 121–134 (2011)

    ADS  CAS  Google Scholar 

  36. Iwasaki, T. et al. Crustal and upper mantle structure in the Ryukyu Island Arc deduced from deep seismic sounding. Geophys. J. Int. 102, 631–651 (1990)

    ADS  Google Scholar 

  37. Iwasaki, T. et al. Precise P and S wave velocity structures in the Kitakami massif, Northern Honshu, Japan, from a seismic refraction experiment. J. Geophys. Res. 99, 22187–22204 (1994)

    ADS  Google Scholar 

  38. Kodaira, S. et al. Seismological evidence for variable growth of crust along the Izu intraoceanic arc. J. Geophys. Res. 112, B05104 (2007)

    ADS  Google Scholar 

  39. Takahashi, N. et al. Crustal structure and evolution of the Mariana intra-oceanic island arc. Geology 35, 203–206 (2007)

    ADS  Google Scholar 

  40. Calvert, A. J., Klemperer, S. L., Takahashi, N. & Kerr, B. C. Three-dimensional crustal structure of the Mariana island arc from seismic tomography. J. Geophys. Res. 113, B01406 (2008)

    ADS  Google Scholar 

  41. Müntener, O. & Ulmer, P. Experimentally derived high-pressure cumulates from hydrous arc magmas and consequences for the seismic velocity structure of lower arc crust. Geophys. Res. Lett. 33, L21308 (2006)

    ADS  Google Scholar 

  42. Müntener, O., Kelemen, P. B. & Grove, T. L. The role of H2O during crystallization of primitive arc magmas under uppermost mantle conditions and genesis of igneous pyroxenites; an experimental study. Contrib. Mineral. Petrol. 141, 643–658 (2001)

    ADS  Google Scholar 

  43. Kushiro, I. & Yoder, H. S., Jr Anorthite-forsterite and anorthite-enstatite reactions and their bearing on the basal-eclogite transformation. J. Petrol. 7, 337–362 (1966)

    ADS  CAS  Google Scholar 

  44. Jagoutz, O. The fine scale seismic structure of an exposed island arc section based on field and petrological constraints. AGU Fall Meet. Abstr. 2628. (2011)

  45. Cottrell, E. & Kelley, K. A. The oxidation state of Fe in MORB glasses and the oxygen fugacity of the upper mantle. Earth Planet. Sci. Lett. 305, 270–282 (2011)

    ADS  CAS  Google Scholar 

  46. Zhang, H. et al. High-resolution subducting-slab structure beneath northern Honshu, Japan, revealed by double-difference tomography. Geology 32, 361–364 (2004)

    ADS  CAS  Google Scholar 

  47. Syracuse, E. M. et al. Seismic tomography and earthquake locations in the Nicaraguan and Costa Rican upper mantle. Geochem. Geophys. Geosyst. 9 http://dx.doi.org/10.1029/2008GC001963 (2008)

    Google Scholar 

  48. Eberhart-Phillips, D. et al. Imaging the transition from Aleutian subduction to Yakutat collision in central Alaska, with local earthquakes and active source data. J. Geophys. Res. 111, http://dx.doi.org/ 10 1029/2005JB004240 (2006)

    Google Scholar 

  49. Wang, Z. & Zhao, D. Vp and Vs tomography of Kyushu, Japan: New insight into arc magmatism and forearc seismotectonics. Phys. Earth Planet. Inter. 157, 269–285 (2006)

    ADS  Google Scholar 

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Acknowledgements

The work was supported by NSF grant numbers EAR 0910644 (to O.J.) and EAR 1316333 (to M.D.B.). We thank N. Arndt for comments that helped to improve the manuscript. J. Connolly’s help in recalibrating the elastic property calculation of Perple_X is appreciated, as are discussions with P. Kelemen and B. Hacker.

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Author notes

  1. jagoutz@mit.edu

Authors and Affiliations

  1. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139-4307, USA,

    Oliver Jagoutz

  2. Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, 02543, Massachusetts, USA

    Mark D. Behn

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  1. Oliver Jagoutz
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Contributions

O.J. designed the project. Both authors conducted the calculations, contributed to the interpretation of the results and wrote the manuscript.

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Extended data figures and tables

Extended Data Figure 1 Seismic velocity and density along different geotherms for the Kohistan arc.

Plotted are the mean and range in VP and density as calculated along the 40, 60 and 80 mW m−2 geotherms.

Extended Data Figure 2 Seismic velocities of the lower arc and continental crust.

Histogram showing distribution of average seismic velocities directly above and below the Moho in continents (red, after ref. 4) and from active arcs (refs 6, 8, 32, 34, 35, 36, 37, 38, 39, 40). Also shown are the range of VP for density-stable and density-unstable rocks from the Kohistan and Talkeetna arcs, as dashed fields calculated from this study. In the arcs, sub-Moho rocks have on average a VP that is 0.5 km s−1 slower than do sub-Moho rocks in continents. The observed low velocities in the arcs agree with the velocities calculated for density-unstable crustal rocks from Kohistan.

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Jagoutz, O., Behn, M. Foundering of lower island-arc crust as an explanation for the origin of the continental Moho. Nature 504, 131–134 (2013). https://doi.org/10.1038/nature12758

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