Control of subduction rate on Tonga-Kermadec arc magmatism
- 125 Downloads
Dehydration/melting of oceanic crusts during returning to the mantle in subduction zones are related to origin of arc lavas. The factors that influence arc magmatism include compositions of the subducting slabs, mantle wedge and subduction rates. However, distinguishing these factors remains difficult and highly debated. Subducting rate is related to the total mass of inputs and controls thermal structure, thus plays a crucial role in arc magmatism. Here we explore the relationships between geochemical variations of arc lavas and convergence rates (increasing from 46 mm/a to the south to 83 mm/a to the northward) in the Tonga-Kermadec arc system. Data of geochemistry for lava samples from nine islands of this arc system are collected and compiled to investigate the role of subduction rate in arc magmatism. Lavas from the northern Tonga arc with a faster subduction rate show broadly lower concentrations of TiO 2 and highfield-strength elements (HFSEs, e.g. Nb, Ta, Zr, Hf), and higher Ba/Th, U/Th ratios than the Kermadec Arc to the south. Some of the Kermadec lavas show the highest values of Th/Nb ratio. We suggest that the northern Tonga arc with a higher subduction rate has been influenced by a stronger role of subductionreleased fluid, which results in stronger large-ion-lithophile elements (LILEs) and relatively weaker HFSEs contribution. It is interpreted that faster subduction rate tend to create a cooler subduction zone, leading to stronger dehydration subduction slab contribution with, thus, higher LILE/HFSE ratios of arc lavas. The conclusion contributes to a better understanding of arc magmatism, and ultimately the long-term chemical differentiation of the Earth. More supplementary geochemical data along Tonga-Kermadec arc and tests in other arcs are needed.
Keywordsubduction rate arc magmatism Tonga-Kermadec Arc
Unable to display preview. Download preview PDF.
- Brenan J M, Shaw H F, Phinney D L et al. 1994. Rutile-aqueous fluid partitioning of Nb, Ta, Hf, Zr, U and Th: implications for high field strength element depletions in island-arc basalts. Earth and Planetary Science Letters, 128 (3–4): 327–339, https://doi.org/10.1016/0012-821x(94)90154-6.CrossRefGoogle Scholar
- Contreras-Reyes E, Grevemeyer I, Watts A B et al. 2011. Deep seismic structure of the Tonga subduction zone: implications for mantle hydration, tectonic erosion, and arc magmatism. Journal of Geophysical Research, 116 (B10): B10103, https://doi.org/10.1029/2011jb008434.Google Scholar
- Elliott T. 2003. Tracers of the slab. In: Eiler J ed. Inside the Subduction Factory. Washington, DC: American Geophysical Union. Geophysical Monograph Series, 138: 138–23.Google Scholar
- Ewart A, Bryan W B, Chappell B W et al. 1994. Regional geochemistry of the Lau-Tonga arc and backarc systems. Proceedings of the Ocean Drilling Program. Scientific Results, 135: 385–425.Google Scholar
- Gamble J, Woodhead J, Wright I et al. 1996. Basalt and sediment geochemistry and magma petrogenesis in a transect from oceanic island arc to rifted continental margin arc: the Kermadec-Hikurangi margin, SW Pacific. Journal of Petrology, 37 (6): 1 523–1 546, https://doi.org/10.1093/petrology/37.6.1523.CrossRefGoogle Scholar
- Haase K M, Regelous M, Beier C. 2016. Sediment melt flux into the melting zone of the northernmost Tonga island arc. Mineralogical Magazine, 75 (3): 962–1 075.Google Scholar
- Hibbard J P, Laughland M M, Kang S M et al. 1993. The thermal imprint of spreading ridge subduction on the upper structural levels of an accretionary prism, southwest Japan. Special Papers, 273: 83–102, https://doi.org/10.1130/SPE273-p83.Google Scholar
- Hoogewerff J A, Van Bergen M J, Vroon P Z et al. 1997. U-series, Sr-Nd-Pb isotope and trace-element systematics across an active island arc-continent collision zone: implications for element transfer at the slab-wedge interface. Geochimica et Cosmochimica Acta, 61 (5): 1 057–1 072, https://doi.org/10.1016/S0016-7037(97) 84621-2.CrossRefGoogle Scholar
- Johnson M C, Plank T. 1999. Dehydration and melting experiments constrain the fate of subducted sediments. Geochemistry, Geophysics, Geosystems, 1 (12): 1 007, https://doi.org/10.1029/1999GC000014.Google Scholar
- Peacock S M. 1996. Thermal and Petrologic Structure of Subduction Zones. In: Gray E B ed. Subduction Top to Bottom. Washington, DC: American Geophysical Union. Geophysical Monograph Series. p.19-113.Google Scholar
- Pearce J A, Peate D W. 1995. Tectonic implications of the composition of volcanic arc magmas. Annual Review of Earth and Planetary Sciences, 23 (1): 251–285, https://doi.org/10.1146/annurev.ea.23.050195.001343.CrossRefGoogle Scholar
- Smith I E M, Price R C. 2006. The Tonga-Kermadec arc and Havre-Lau back-arc system: their role in the development of tectonic and magmatic models for the western pacific. Journal of volcanology and geothermal research, 156 (3–4): 315–331, https://doi.org/10.1016/j.jvolgeores.2006.03.006.CrossRefGoogle Scholar
- Smith I E M, Stewart R B, Price R C et al. 2010. Are arc-type rocks the products of magma crystallisation? Observations from a simple oceanic arc volcano: Raoul Island, Kermadec arc, SW pacific. Journal of Volcanology and Geothermal Research, 190 (1–2): 219–234, https://doi.org/10.1016/j.jvolgeores.2009.05.006.CrossRefGoogle Scholar
- Tian L Y, Castillo P R, Hilton D R et al. 2011. Major and trace element and Sr-Nd isotope signatures of the northern Lau basin lavas: implications for the composition and dynamics of the back-arc basin mantle. Journal of Geophysical Research, 116 (B11): B11201, https://doi.org/10.1029/2011JB008791.CrossRefGoogle Scholar
- Timm C, Davy B, Haase K et al. 2014. Subduction of the oceanic Hikurangi plateau and its impact on the Kermadec arc. Nature Communications, 5: 4 923, https://doi.org/10.1038/ncomms5923.
- Timm C, Leybourne M I, Hoernle K et al. 2016. Trenchperpendicular geochemical variation between two adjacent Kermadec arc volcanoes Rumble II east and west: the role of the subducted Hikurangi plateau in element recycling in arc magmas. Journal of Petrology, 57 (7): 1 335–1 360, https://doi.org/10.1093/petrology/egw042.CrossRefGoogle Scholar
- Turner S, Bourdon B, Hawkesworth C et al. 2000. 226 Ra-23. Th evidence for multiple dehydration events, rapid melt ascent and the time scales of differentiation beneath the Tonga-Kermadec island arc. Earth and Planetary Science Letters, 179 (3–4): 581–593, https://doi.org/10.1016/S0012-821X(00)00141-2.CrossRefGoogle Scholar
- Woodhead J, Eggins S, Gamble J. 1993. High field strength and transition element systematics in island arc and backarc basin basalts: evidence for multi-phase melt extraction and a depleted mantle wedge. Earth and Planetary Science Letters, 114 (4): 491–504, https://doi.org/10.1016/0012-821X(93)90078-N.CrossRefGoogle Scholar
- Wyllie P J. 1979. Magmas and volatile components. American Mineralogist, 64 (5–6): 469–500.Google Scholar