Persistent shallow magnetic inclination in the past 5 million years with implications for regional tectonics in the Philippines

Despite the growing knowledge on geomagnetic paleosecular variations, the region around the Philippine archipelago remains to be a huge data gap in this regard. This work looked into rock magnetic information from <5 Ma volcanic rocks of Luzon Island to provide data for the statistical characteri...

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Bibliographic Details
Published in:Journal of Asian Earth Sciences: X
Main Authors: Decibel V. Faustino-Eslava, Hidetoshi Shibuya, Carla B. Dimalanta, Graciano P. Yumul, Jr., Jonathan T. Macuroy
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2021
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Online Access:https://doi.org/10.1016/j.jaesx.2021.100048
https://doaj.org/article/b41e6d0da842484fba83e2cd0ea6fe57
Description
Summary:Despite the growing knowledge on geomagnetic paleosecular variations, the region around the Philippine archipelago remains to be a huge data gap in this regard. This work looked into rock magnetic information from <5 Ma volcanic rocks of Luzon Island to provide data for the statistical characterization of the time-averaged field in the region.A total of 21 sites with ages from 1 ka to 4.3 Ma yielded 13 normal, 7 reversed, and 1 intermediate polarity dataset. These were aggregated with previously published work to form a combined dataset of 59 normal + reversed sites with a mean virtual geomagnetic pole at 321.1°E and 83.7°N with α95 = 3.4, and an angular standard deviation of about 14.6°. This amount of scatter is slightly larger than that predicted by Model G but relatively comparable with other near-equatorial regions such as Java and Ecuador. This work is a first examination of paleomagnetic data from the Philippines in relation to the long-term behavior of the magnetic field in this part of Southeast Asia. The long-ranging shallow inclination observed may also have implications on how paleomagnetic data are interpreted for tectonic studies in the region.