From rifting to emplacement: Variable mantle melting preserved in the central Palawan Ophiolite peridotites, Philippines

The mantle section of the central Palawan Ophiolite (CPO) in western Philippines is dominantly composed of dunites and harzburgites. Basal lherzolites and harzburgites juxtaposed with the metamorphic sole of the CPO are also exposed within the vicinity of Ulugan Bay, Puerto Princesa. These basal per...

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Bibliographic Details
Published in:International geology review 2023-12, Vol.ahead-of-print (ahead-of-print), p.1-20
Main Authors: Pasco, Julius A., Payot, B.D., Valera, G.T.V., Dycoco, J.M.A., Labis, F.A.C., Tamura, A., Morishita, T.
Format: Article
Language:English
Subjects:
basal peridotite
Fertility
Fluids
Information processing
Lithosphere
Mantle
Marine molluscs
Melting
Obduction
ophiolite
Oysters
Palawan
Rifting
Shellfish
Spinel
Subduction
Subduction (geology)
Subduction zones
supra-subduction zone peridotite
Tremolite
Upper mantle
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Summary:The mantle section of the central Palawan Ophiolite (CPO) in western Philippines is dominantly composed of dunites and harzburgites. Basal lherzolites and harzburgites juxtaposed with the metamorphic sole of the CPO are also exposed within the vicinity of Ulugan Bay, Puerto Princesa. These basal peridotites provide novel information regarding the processes transpiring in the upper mantle during the evolution of this preserved oceanic lithosphere. The Nasuduan lherzolite is characterized by low Cr# of spinel and high concentrations of REEs in clinopyroxenes. The Oyster Bay lherzolite displays similar fertile characteristics and occurs with harzburgites. Both contain fine-grained and interstitial clinopyroxenes derived from interstitial melts. Tremolite and talc in the Oyster Bay lherzolite and harzburgite and in other CPO harzburgites are attributed to slab-fluid metasomatism. Harzburgites and dunites from Bentoan Beach and other CPO harzburgites have high spinel Cr# and low clinopyroxene REE concentrations. These indicate that these peridotites have undergone extensive degrees of melting facilitated by fluids. The petrological and geochemical signatures of the CPO peridotites record the transition of a supra-subduction zone from back-arc spreading, incipient subduction, to the obduction of an ancient oceanic lithosphere.
ISSN:0020-6814
1938-2839
DOI:10.1080/00206814.2023.2191347