Westward younging disposition of Philippine ophiolites and its implication for arc evolution

Abstract

The different ophiolite complexes in the Philippine island arc system define a progressive younging direction westward. This resulted from the clockwise rotation of the Philippine island arc system during its north-westward translation in the Eocene resulting in its western boundary colliding with the Sundaland-Eurasian margin. As a consequence of this interaction, ophiolite complexes and mélanges accreted into the Philippine island arc system along its western side. A new ophiolite zonation with four belts is proposed that takes into consideration the observed spatial and temporal relationships of the exposed oceanic lithosphere slices. With progressive younging from east to west, Belt 1 corresponds to Late Cretaceous complete ophiolite complexes with associated metamorphic soles along the eastern Philippines, whereas Belt 2 includes Early to Late Cretaceous dismembered ultramafic-mafic complexes with mélanges exposed mainly west of eastern Philippines. Belt 3 is defined by Cretaceous through Eocene to Oligocene ophiolite complexes emplaced along the collision zone between the Philippine Mobile Belt and the Sundaland-Eurasian margin. Belt 4 corresponds to the ophiolite complexes emplaced along continental margins as exposed in the Palawan and Zamboanga-Sulu areas. This proposed zonation hints that the whole Philippine Mobile Belt, except for the strike-slip fault bounded Eocene Zambales ophiolite complex in Luzon, is underlain by Cretaceous proto-Philippine Sea Plate fragments. This is contrary to the previous models that consider only the eastern margin of the Philippines to contain proto-Philippine Sea Plate materials.

Initiation and evolution of the South China Sea: an overview

“…5) (Holloway 1982;Taylor and Hayes 1982;Hall 1996). Although this model is seemingly supported by abundant ophiolites in the Luzon and Sulu islands (Yumul 2007), paleomagnetic results show that the proto-SCS was very small (Lee and Lawver 1994). It is not likely to have pulled apart the thick continental lithosphere of South China.…”

“…The first backarc extension was responsible for the formation of the proto-SCS, whereas the second extension was responsible for the Shenhu event and ultimately the formation of the SCS. Islands (Yumul 2007 …”

“…Four ophiolite belts, with ages from Jurassic to Eocene, have been recognized (Fig. 8) (Yumul 2007). All these ophiolites are located along the Manila trench, implying connections to the SCS or proto-SCS.…”

Geochemical and Geophysical Characteristics of the Balud Ophiolitic Complex (BOC), Masbate Island, Philippines: Implications for its Generation, Evolution and Emplacement

“…The Philippines is made up of a collage of continental fragments, island arcs, mélanges, ophiolites, and ophiolitic units. Yumul (2007) classified Philippine ophiolites into four belts based on observed spatial and temporal relationships (Fig. 1a).…”

Abundance and Distribution of Arbuscular Mycorrhiza in the Ultramafic Soils of Mt. Kiamo in Bukidnon, Philippines

“…Ultramafic soils account for about 5% of the total land area in the Philippines (Yumul, 2007). They occur as subduction-related outcrops in four major ophiolitic belts in the archipelago with the majority of these of Cretaceous age with a few of Early Tertiary (Yumul et al, 2008).…”