TY - JOUR
T1 - Geochemical trends across an arc-continent collision zone
T2 - Magma sources and slab-wedge transfer processes below the Pantar Strait volcanoes, Indonesia
AU - Elburg, Marlina A.
AU - Van Bergen, Manfred
AU - Hoogewerff, Jurian
AU - Foden, John
AU - Vroon, Pieter
AU - Zulkarnain, Iskandar
AU - Nasution, Asnawir
PY - 2002/8
Y1 - 2002/8
N2 - Four volcanoes in the Pantar Strait, the westernmost part of the extinct sector of the east Sunda arc, show remarkable across-arc variation in elemental abundances (K2O: 1.2 to 4.3%), trace element ratios (Pb/Ce: 0.4 to 0.18; Ce/Yb: 20 to 55) and isotope ratios (143Nd/144Nd: 0.51263 to 0.51245; 87Sr/86Sr: 0.7053 to 0.7068; 206Pb/204 Pb: 19.29 to 19.15). Pb isotopes are decoupled from Sr and Nd isotopes, with the frontal volcanoes showing the higher Nd and Pb and lower Sr isotopic ratios. The isotopic and trace element ratios of the volcanic samples are best explained by modification of a MORB-type source (with Indian Ocean island basalt-type Pb isotopic characteristics) by a fluid and a partial melt of subducted continental material (SCM). The frontal volcano contains the highest proportion of the fluid component, with a small contribution of partial melt. The source of the rear-arc volcano is strongly influenced by a partial melt of SCM that had undergone a previous dehydration event, by which it lost most of its fluid-mobile elements such as Pb. The SCM partial melt was in equilibrium with both rutile and garnet, whereas mantle melting took place in the presence of residual mica. The relatively large across-arc increase in incompatible elements can be explained by a combination of increasing addition of SCM partial melt, changing mantle wedge fertility and smaller degrees of partial melting toward the rear of the arc. Comparison with a more westerly across-arc transect shows that the relatively low 143Nd/144Nd ratios of the frontal volcano, and the decoupling of Pb from Sr and Nd isotopes are unique to the Pantar Strait volcanoes. This is likely to reflect magma generation in a collisional environment, where the leading edge of the Australian continent, rather than subducted sediment, contributes to the magma source.
AB - Four volcanoes in the Pantar Strait, the westernmost part of the extinct sector of the east Sunda arc, show remarkable across-arc variation in elemental abundances (K2O: 1.2 to 4.3%), trace element ratios (Pb/Ce: 0.4 to 0.18; Ce/Yb: 20 to 55) and isotope ratios (143Nd/144Nd: 0.51263 to 0.51245; 87Sr/86Sr: 0.7053 to 0.7068; 206Pb/204 Pb: 19.29 to 19.15). Pb isotopes are decoupled from Sr and Nd isotopes, with the frontal volcanoes showing the higher Nd and Pb and lower Sr isotopic ratios. The isotopic and trace element ratios of the volcanic samples are best explained by modification of a MORB-type source (with Indian Ocean island basalt-type Pb isotopic characteristics) by a fluid and a partial melt of subducted continental material (SCM). The frontal volcano contains the highest proportion of the fluid component, with a small contribution of partial melt. The source of the rear-arc volcano is strongly influenced by a partial melt of SCM that had undergone a previous dehydration event, by which it lost most of its fluid-mobile elements such as Pb. The SCM partial melt was in equilibrium with both rutile and garnet, whereas mantle melting took place in the presence of residual mica. The relatively large across-arc increase in incompatible elements can be explained by a combination of increasing addition of SCM partial melt, changing mantle wedge fertility and smaller degrees of partial melting toward the rear of the arc. Comparison with a more westerly across-arc transect shows that the relatively low 143Nd/144Nd ratios of the frontal volcano, and the decoupling of Pb from Sr and Nd isotopes are unique to the Pantar Strait volcanoes. This is likely to reflect magma generation in a collisional environment, where the leading edge of the Australian continent, rather than subducted sediment, contributes to the magma source.
UR - http://www.scopus.com/inward/record.url?scp=0036687817&partnerID=8YFLogxK
U2 - 10.1016/S0016-7037(02)00868-2
DO - 10.1016/S0016-7037(02)00868-2
M3 - Article
AN - SCOPUS:0036687817
SN - 0016-7037
VL - 66
SP - 2771
EP - 2789
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
IS - 15
ER -