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Geo- and thermochronological methods were applied to diorites from the Cordillera Central, Luzon, Philippines to understand their emplacement and exhumation history in the island arc mountains. Five zircon U–Pb ages range from 32.54 ± 0.70 to 6.11 ± 0.15 (2SE) Ma, indicating that dioritic magmas intruded the upper crust intermittently during Cenozoic magmatism. Five zircon fission-track (ZFT) pooled ages range from 35.63 ± 2.17 to 6.91 ± 0.36 (2SE) Ma and are generally comparable with the U–Pb ages at each locality. These results suggest that the diorites cooled rapidly below ~ 250–350 °C (i.e., through the partial annealing zone of the ZFT system), following their intrusion. On the other hand, two zircon and five apatite U-Th(-Sm)/He (ZHe and AHe) weighted mean ages, ranging from 11.71 ± 0.36 to 8.82 ± 0.26 and 9.21 ± 0.52 to 0.98 ± 0.09 (2SE) Ma, respectively, indicate a decrease in cooling rates at a lower temperature range, especially through the partial retention zone of the AHe system. This observation suggests that the ZFT ages reflect initial cooling of the dioritic magma, whereas the AHe ages reflect the cooling history associated with regional exhumation following the initial cooling phase. The spatial distribution of the AHe ages suggests that rapid exhumation of the Cordillera Central during the Quaternary resulted from the block-like uplift of the entire mountain range. [ABSTRACT FROM AUTHOR]

Emergent coral reef terraces in northwest Luzon Island, Philippines are studied to understand relative sea level (RSL) changes and uplift along the Manila Trench forearc region during the Late Quaternary. Coral reef sequences in Currimao, Badoc, and Badoc Island were mapped and were described based on geomorphological characteristics, elevation patterns, and ages. The lower emergent coral reef terraces, which are dated Holocene, are subdivided into three to possibly four terrace steps (TI–TIV in ascending order) with the highest terrace (TIII–TIV) rising up to ~7–9 m amsl. The well‐preserved staircase morphology and meter‐scale terrace risers possibly imply episodes of abrupt RSL changes that resulted from coseismic uplift during the mid‐Holocene. Around 6.8 kyr BP, ~3 m of rapid uplift (possibly coseismic) is inferred to account for the vertical separation of TI (6.2 kyr BP at 3.5 m amsl) and TII (6.8 kyr BP at 6.6 m amsl) in Currimao site. A subsequent episode of RSL fall occurred at 6 kyr BP, based on dated coral samples, and has emerged the lowest terraces in the study sites. New geomorphic and radiometric data suggest that the mid‐Holocene sea level highstand in northwest Luzon occurred at around 7–6 kyr BP. From the elevation and thorium‐230 age of dated terrace surfaces, we estimated Holocene uplift rates from 0.17 ± 0.12 to 0.82 ± 0.15 mm/yr across the three study sites. The estimated uplift rates of northwest Luzon are relatively lower than the uplift rates reported in similar tectonically active regions of the west Pacific such as Papua New Guinea, Taiwan, New Zealand, and Japan. The geomorphological characteristics and age of emergent coral reef terraces reported in this study offer insights on the preservation of long‐term deformation along the northwest Luzon coastal plain that is bordered by a subduction zone and upper‐plate faults. © 2018 John Wiley & Sons, Ltd. Emergent coral reef terraces and tidal notches are useful geomorphic markers in constraining RSL changes and tectonic processes along offshore and onland faults. This study reports new geomorphic and radiometric data in northwest Luzon as evidence of RSL changes and possible prehistoric earthquakes along the Manila subduction zone and its forearc region during the mid‐Holocene. This study offers new insights to the preservation of long‐term deformation along the coast that is bordered by a subduction zone and upper‐plate faults. [ABSTRACT FROM AUTHOR]