A preliminary Neogene paleomagnetic data set from Leyte and its relation to motion on the Philippine fault

摘要: Abstract Leyte Island is bisected by the left-lateral Philippine fault. Paleomagnetic samples were collected from nineteen lava flows in and nearby islands to north. The data these sites combined with previously reported results northeastern Mindanao. paleomagnetic Neogene rocks within or very near fault zone on Leyte, Mindanao, Biliran, Maripipi, Genuruan Islands fall into two populations. Seventeen late (fourteen normal polarity three reversed polarity) yield a mean direction D = 358.9°, I 20.1° (α95 6.6°, k 30.1) pole λ 88.9°N, φ =12.5°E (A95 4.8°, K=56.1). Eight early (three five give 23.2°, 13.9° 9.3°, 36.2) 66.5°N, 220.5°E 7.1°, K= 62.0). indistinguishable Plio-Pleistocene poles Philippines, Taiwan, Vietnam, Miocene of central Philippines suggesting there have been no significant rotations translations this region respect other Southeast Asian regions during past 5 M.y. statistically middle Philippines. distinguishable Marinduque (Philippines) as well entire This preliminary set suggests that adjacent north portion same tectonic block Cebu, western Panay since Neogene. There are also paleomagnetically detectable fault-related associated given resolution set. No consensus exists amount offset age inception 110 km between ophiolitic basement northeast southwest displacement has occurred along Tertiary. In contrast continental regions, shear-related found observation hot, immature, transitional island arc/continental crust deforms differently response shear than developed crust.