Oxygen isotope constraints on the sources of Central American arc lavas

Oxygen-isotope ratios of olivine and plagioclase phenocrysts in basalts and basaltic andesites from the Central American arc vary systematically with location, from a minimum δ18Oolivine value of 4.6 (below the range typical of terrestrial basalts) in Nicaragua near the center of the arc to a maximum δ18Oolivine value of 5.7 (above the typical range) in Guatemala near the northwest end of the arc. These oxygen-isotope variations correlate with major and trace element abundances and with Sr and Nd isotope compositions of host lavas, defining trends that suggest variations in δ18O reflect slab contributions to the mantle sources of these lavas. These trends can be explained by a model in which both a low-δ18O, water-rich component and a high-δ18O, water-poor component are extracted from the subducting Cocos slab and flux melting in the overlying mantle wedge. The first of these components dominates slab fluxes beneath the center of the arc and is the principal control on the extent of melting of the mantle wedge (which is highest in the center of the arc); the second component dominates slab fluxes beneath the northwestern margin of the arc. Fluxes of both components are small or negligible beneath the southeastern margin of the arc. We suggest that the low-δ18O component is a solute-rich aqueous fluid produced by dehydration of hydrothermally altered rocks deep within the Cocos slab (perhaps serpentinites produced in deep normal faults offshore of Nicaragua) and that the high-δ18O component is a partial melt of subducted sediment on top of the plate.

[1]  S. Poli,et al.  Experimentally based water budgets for dehydrating slabs and consequences for arc magma generation , 1998 .

[2]  K. Grönvold,et al.  Geochemical and Isotopic Evidence for Crustal Assimilation Beneath Krafla, Iceland , 1991 .

[3]  K. Muehlenbachs,et al.  Oxygen and carbon isotope evidence for seawater-hydrothermal alteration of the Macquarie Island ophiolite , 1982 .

[4]  Michael O. Garcia,et al.  Crustal Contamination of Kilauea Volcano Magmas Revealed by Oxygen Isotope Analyses of Glass and Olivine from Puu Oo Eruption Lavas , 1998 .

[5]  Brian M. Smith,et al.  Large scale isotopic Sr, Nd and O isotopic anatomy of altered oceanic crust: DSDP/ODP sites417/418 , 1995 .

[6]  H. Taylor,et al.  An oxygen isotope profile in a section of Cretaceous oceanic crust, Samail Ophiolite, Oman: Evidence for δ18O buffering of the oceans by deep (>5 km) seawater-hydrothermal circulation at mid-ocean ridges , 1981 .

[7]  A. Hofmann,et al.  Oxygen isotope constraints on the sources of Hawaiian volcanism: Earth and Planetary Science Letters , 1996 .

[8]  M. Drummond,et al.  Derivation of some modern arc magmas by melting of young subducted lithosphere , 1990, Nature.

[9]  M. Murrell,et al.  Uranium series and beryllium isotope evidence for an extended history of subduction modification of the mantle below Nicaragua , 1994 .

[10]  P. Kelemen,et al.  Along‐Strike Variation in the Aleutian Island Arc: Genesis of High Mg# Andesite and Implications for Continental Crust , 2013 .

[11]  Matthias Hort,et al.  Serpentine and the subduction zone water cycle , 2004 .

[12]  D. Hilton,et al.  Subduction and Recycling of Nitrogen Along the Central American Margin , 2002, Science.

[13]  K. Grönvold,et al.  Oxygen isotope evidence for the origin of chemical variations in lavas from Theistareykir volcano in Iceland’s northern volcanic zone , 2000 .

[14]  H. Newsom,et al.  The role of hydrothermal fluids in the production of subduction zone magmas: Evidence from siderophile and chalcophile trace elements and boron , 1996 .

[15]  S. Peacock.  Thermal Structure and Metamorphic Evolution of Subducting Slabs , 2013 .

[16]  J. Alt,et al.  An oxygen isotopic profile through the upper kilometer of the oceanic crust, DSDP hole 504B , 1986 .

[17]  C. Langmuir,et al.  Oxygen isotope evidence for the origin of enriched mantle beneath the mid-Atlantic ridge☆ , 2004 .

[18]  P. Kelemen,et al.  Thermal Structure due to Solid‐State Flow in the Mantle Wedge Beneath Arcs , 2013 .

[19]  K. Muehlenbachs.  Alteration of the oceanic crust and the 18 O history of seawater , 1986 .

[20]  M. Ghiorso,et al.  Calculation of Peridotite Partial Melting from Thermodynamic Models of Minerals and Melts. III. Controls on Isobaric Melt Production and the Effect of Water on Melt Production , 1999 .

[21]  T. Anderson,et al.  Stable isotopes in sedimentary Geology , 1983 .

[22]  C. Langmuir,et al.  An evaluation of the global variations in the major element chemistry of arc basalts , 1988 .

[23]  D. Lowry,et al.  Oxygen isotope composition of mantle peridotite , 1994 .

[24]  M. J. Carr,et al.  Nicaraguan volcanoes record paleoceanographic changes accompanying closure of the Panama gateway , 2002 .

[25]  F. Ryerson,et al.  Mineral-aqueous fluid partitioning of trace elements at 900°C and 2.0 GPa: Constraints on the trace element chemistry of mantle and deep crustal fluids , 1995 .

[26]  J. Morgan,et al.  Bending-related faulting and mantle serpentinization at the Middle America trench , 2003, Nature.

[27]  M. McCulloch,et al.  Geochemical and geodynamical constraints on subduction zone magmatism , 1991 .

[28]  S. Eggins,et al.  High field strength and transition element systematics in island arc and back-arc basin basalts: Evidence for multi-phase melt extraction and a depleted mantle wedge , 1993 .

[29]  H. Craig,et al.  Oxygen isotope evidence against bulk recycled sediment in the mantle sources of Pitcairn Island lavas , 1995, Nature.

[30]  H. Keppler,et al.  Direct observation of complete miscibility in the albite–H2O system , 1997, Nature.

[31]  M. J. Carr,et al.  Lead isotope composition of Central American volcanoes: Influence of the Galapagos plume , 2004 .

[32]  J. Eiler,et al.  Oxygen isotope ratios in olivine from the Hawaii Scientific Drilling Project , 1996 .

[33]  H. Chiba.  Oxygen isotope fractionations involving diopside, forsterite, magnetite, and calcite: Application to geothermometry : , , and (1989) Goechim. Cosmochim. Acta 53 , 2985-2995 , 1991 .

[34]  S. Epstein,et al.  Stable isotope geochemistry of deep sea cherts , 1976 .

[35]  J. Eiler.  Oxygen Isotope Variations of Basaltic Lavas and Upper Mantle Rocks , 2001 .

[36]  J. Eiler,et al.  Melt depletion and subsequent metasomatism in the shallow mantle beneath Koolau volcano, Oahu (Hawaii) , 2002 .

[37]  H. Craig,et al.  Oxygen isotope variations in ocean island basalt phenocrysts , 1997 .

[38]  S. Newman,et al.  The role of water in the petrogenesis of Mariana trough magmas , 1994 .

[39]  M. J. Carr.  Symmetrical and segmented variation of physical and geochemical characteristics of the central american volcanic front , 1984 .

[40]  K. Grönvold,et al.  Melt mixing and crystallization under Theistareykir, northeast Iceland , 2003 .

[41]  H. Taylor.  The effects of assimilation of country rocks by magmas on 18O/16O and 87Sr/86Sr systematics in igneous rocks , 1980 .

[42]  T. Plank,et al.  Element transport from slab to volcanic front at the Mariana arc , 1997 .

[43]  A. Crawford,et al.  Oxygen Isotope Geochemistry of Oceanic-Arc Lavas , 2000 .

[44]  W. McDonough,et al.  Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes , 1989, Geological Society, London, Special Publications.

[45]  M. J. Carr,et al.  Positively correlated Nd and Sr isotope ratios of lavas from the Central American volcanic front , 1986 .

[46]  M. Magaritz,et al.  Oxygen and hydrogen isotope studies of serpentinization in the Troodos ophiolite complex, Cyprus , 1974 .

[47]  D. DePaolo.  Trace element and isotopic effects of combined wallrock assimilation and fractional crystallization , 1981 .

[48]  B. Murton,et al.  Crustal Processes: Major Controls on Reykjanes Peninsula Lava Chemistry, SW Iceland , 1998 .

[49]  L. Baumgartner,et al.  Stable Isotope Transport and Contact Metamorphic Fluid Flow , 2001 .

[50]  K. Muehlenbachs.  Chapter 12. ALTERATION of the OCEANIC CRUST and the 18O HISTORY of SEAWATER , 1986 .

[51]  D. Mattey,et al.  Crustal interaction during construction of ocean islands: PbSrNdO isotope geochemistry of the shield basalts of Gran Canaria, Canary Islands , 1997 .

[52]  P. Michael.  Regionally distinctive sources of depleted MORB: Evidence from trace elements and H2O , 1995 .

[53]  A. Hofmann,et al.  Mantle geochemistry: the message from oceanic volcanism , 1997, Nature.

[54]  E. A. Bennett,et al.  Incompatible element and isotopic evidence for tectonic control of source mixing and melt extraction along the Central American arc , 1990 .

[55]  K. Cooper,et al.  Re-examination of crystal ages in recent Mount St. Helens lavas: Implications for magma reservoir processes , 2003 .

[56]  D. Schrag,et al.  Oxygen isotope exchange in a two-layer model of oceanic crust , 1992 .

[57]  J. Eiler,et al.  Oxygen isotope geochemistry of the second HSDP core , 2003 .

[58]  R. Edwards,et al.  (231Pa/235U)-(230Th/238U) of young mafic volcanic rocks from Nicaragua and Costa Rica and the influence of flux melting on U-series systematics of arc lavas , 2002 .

[59]  E. Ito,et al.  The O, Sr, Nd and Pb isotope geochemistry of MORB , 1987 .

[60]  C. Langmuir,et al.  Tracing trace elements from sediment input to volcanic output at subduction zones , 1993, Nature.

[61]  J. Morris,et al.  The subducted component in island arc lavas: constraints from Be isotopes and B–Be systematics , 1990, Nature.

[62]  Philip T. Broughton,et al.  Across‐arc geochemical trends in the Izu‐Bonin arc: Contributions from the subducting slab , 2001 .

[63]  G. Abers,et al.  The wet Nicaraguan slab , 2003 .

[64]  D. Cole,et al.  Equilibrium Oxygen, Hydrogen and Carbon Isotope Fractionation Factors Applicable to Geologic Systems , 2001 .

[65]  M. Kohn,et al.  UWG-2, a garnet standard for oxygen isotope ratios: Strategies for high precision and accuracy with laser heating , 1995 .

[66]  M. J. Carr,et al.  Boron geochemistry of the Central American Volcanic Arc: Constraints on the genesis of subduction-related magmas , 1994 .

[67]  B. Cousens,et al.  Subduction-modified pelagic sediments as the enriched component in back-arc basalts from the Japan Sea: Ocean Drilling Program Sites 797 and 794 , 1994 .

[68]  S. Bowring,et al.  The role of an H2O-rich fluid component in the generation of primitive basaltic andesites and andesites from the Mt. Shasta region, N California , 2002 .

[69]  Z. Sharp.  A laser-based microanalytical method for the in situ determination of oxygen isotope ratios of silicates and oxides , 1990 .

[70]  Laurent Simon,et al.  Continental recycling: The oxygen isotope point of view , 2005 .

[71]  M. Reagan,et al.  Variations in lava composition associated with flow of asthenosphere beneath southern Central America , 1995 .

[72]  M. J. Carr,et al.  Flux versus decompression melting at stratovolcanoes in southeastern Guatemala , 2003 .

[73]  J. Eiler,et al.  Oxygen-isotope evidence for recycled crust in the sources of mid-ocean-ridge basalts , 2000, Nature.

[74]  M. J. Carr,et al.  Abrupt change in magma generation processes across the Central American arc in southeastern Guatemala: flux-dominated melting near the base of the wedge to decompression melting near the top of the wedge , 1995 .

[75]  M. J. Carr,et al.  Local and regional variations in Central American arc lavas controlled by variations in subducted sediment input , 2000 .

[76]  D. Shaw.  Trace element fractionation during anatexis , 1970 .

[77]  R. Harris,et al.  Abrupt thermal transition reveals hydrothermal boundary and role of seamounts within the Cocos Plate , 2003 .

[78]  Marie C. Johnson,et al.  Dehydration and melting experiments constrain the fate of subducted sediments , 2000 .