Petrology and geochemistry of Camiguin Island, southern Philippines: insights to the source of adakites and other lavas in a complex arc setting |
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| Authors: | Paterno R Castillo Philip E Janney Renato U Solidum |
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| Institution: | (1) Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0220, USA; Tel.: (619) 534-0383; Fax: (619) 534-0784; E-mail: pcastillo@ucsd.edu, US;(2) Philippine Institute of Volcanology and Seismology, Quezon City, Philippines, |
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| Abstract: | Camiguin is a small volcanic island located 12 km north of Mindanao Island in southern Philippines. The island consists of
four volcanic centers which have erupted basaltic to rhyolitic calcalkaline lavas during the last ∼400 ka. Major element,
trace element and Sr, Nd and Pb isotopic data indicate that the volcanic centers have produced a single lava series from a
common mantle source. Modeling results indicate that Camiguin lavas were produced by periodic injection of a parental magma
into shallow magma chambers allowing assimilation and fractional crystallization (AFC) processes to take place. The chemical
and isotopic composition of Camiguin lavas bears strong resemblance to the majority of lavas from the central Mindanao volcanic
field confirming that Camiguin is an extension of the tectonically complex Central Mindanao Arc (CMA). The most likely source
of Camiguin and most CMA magmas is the mantle wedge metasomatized by fluids dehydrated from a subducted slab. Some Camiguin
high-silica lavas are similar to high-silica lavas from Mindanao, which have been identified as “adakites” derived from direct
melting of a subducted basaltic crust. More detailed comparison of Camiguin and Mindanao adakites with silicic slab-derived
melts and magnesian andesites from the western Aleutians, southernmost Chile and Batan Island in northern Philippines indicates
that the Mindanao adakites are not pure slab melts. Rather, the CMA adakites are similar to Camiguin high-silica lavas which
are products of an AFC process and have negligible connection to melting of subducted basaltic crust.
Received: 27 February 1998 / Accepted: 27 August 1998 |
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