Paleomagnetism of the Samar Ophiolite: Implications for the Cretaceous sub-equatorial position of the Philippine island arc

Issue Date

2015

Abstract

Samar island in the eastern part of Central Philippines is underlain by a complete ophiolite suite, the Samar Ophiolite. We present the first geochronological and paleomagnetic data for the Samar Ophiolite. Whole rock K-Ar dating of two basalt samples yielded an age of 100.2 ± 2.7 Ma and 97.9 ± 2.8 Ma. Thirteen sites in four localities yielded characteristic remanent magnetization with in situ direction of D = 340°, I = - 24°, k = 15, α95 = 11° and tilt-corrected direction of D = 342°, I = - 27°, k = 15, α95 = 11°. These values suggest that the ophiolitic basement rocks of Samar formed in the Late Cretaceous at a paleolatitude of 14°S ± 6°. The paleolatitude is several degrees south of the sub-equatorial positions calculated for the three other Mesozoic ophiolites of the Philippine Mobile Belt (PMB) whose paleomagnetism had been previously studied. The PMB ophiolites in eastern and central Philippines share a common age, geochemistry and paleolatitude with the Halmahera Ophiolite, suggesting that they originated from a Mesozoic supra-subduction zone that spanned a few degrees north of the equator to around 15°S.

Source or Periodical Title

Tectonophysics

ISSN

0040-1951

Volume

664

Page

214-224

Document Type

Article

Language

English

Subject

Cretaceous, Mesozoic ophiolites, Paleomagnetism, Philippines-Halmahera arc, Samar Ophiolie

Identifier

doi:10.1016/j.tecto.2015.09.024.

Digital Copy

yes

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