| The tectonic environment and geological history of Southeast Asia and adjacent South China Sea are extremely complex. The island of Palawan in the southern part of South China Sea is composed of two different terranes. The northern part, called the North Palawan Block (NPB) is a rifted fragment of China, biostratigraphically dated as Paleozoic and Mesozoic and comprising middle-upper Permian limestone and other clastic rocks, thinly bedded, middle Triassic red and white cherts, and upper to lower Jurassic limestones and sandstone. Tertiary sedimentary rocks overlie these pre-Tertiary sedimentary sequences with disconformities that can be associated with the spreading of South China Sea. The Southern Palawan Block (SPB) includes Mesozoic and Cenozoic ophiolites and a late Paleocene-early middle Miocene clastic sequence that can be correlated with the Crocker Formation of Borneo.; The paleomagnetic directions in the Northern Palawan are represented by the King Ranch Formation, the Busuanga Chert on Busuanga Island, the Manguao Volcanics, and Bacuit and Guinlo Formations. The paleomagnetic signature of the King Ranch Formation showed a similar geographic ChRM direction with South China. The geographic ChRM direction has a mean declination D of 32.8{dollar}spcirc{dollar} and inclination I of 43.9{dollar}spcirc{dollar} with {dollar}alphasb{lcub}95{rcub}{dollar} = 5.2{dollar}spcirc{dollar} and {dollar}kappa{dollar} = 217.1. The geographic paleomagnetic pole (GPP) of this formation has a longitude of 182.2{dollar}spcirc{dollar}E and a latitude of 56.8{dollar}spcirc{dollar}N with an {dollar}alphasb{lcub}95{rcub}{dollar} = 6.5{dollar}spcirc{dollar} and {dollar}kappa{dollar} 146.0, statistically indistinguishable from the Cretaceous Pole of South China. Moreover, the paleolatitude calculated from the geographic ChRM direction corroborated paleolatitude of South China, indicating that North Palawan Block was detached from South China Block, migrated to the south, and finally amalgamated with the Philippine Archipelago. The South Palawan Block has paleomagnetic directions that are different from those of the North Palawan Block. The geographic ChRM direction gave a mean declination D of 115.1{dollar}spcirc{dollar} and inclination I of {dollar}-{dollar}10.6{dollar}spcirc{dollar}, with {dollar}alphasb{lcub}95{rcub}{dollar} = 17.7{dollar}spcirc{dollar} and {dollar}kappa{dollar} = 15.2, which yielded a GPP longitude of 209.9{dollar}spcirc{dollar}E and latitude of 25.8{dollar}spcirc{dollar}S with {dollar}alphasb{lcub}95{rcub}{dollar} = 11.8. The paleolatitude calculated from the mean geographic inclination is {dollar}-{dollar}4.3{dollar}spcirc{dollar}S, corresponding to northward translation of about 13.3{dollar}spcirc{dollar} to its present location. |
