ISSN:
1365-246X
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
More than 100 block samples were collected for palaeomagnetic and geochronological studies from 14 sites in Miocene and Plio-Pleistocene volcanic rocks in the western foothills province of northern Taiwan, in an attempt to understand the tectonic evolution of the junction of the Ryukyu and the Luzon arcs. Potassiumargon dating yields ages of 7.9 ± 0.5 Ma and 10.1 ± 0.6 Ma for two samples from the Miocene Chiopanshan volcanic series, and 1.2 ± 0.1 Ma for a sample from the Plio-Pleistocene Chilung volcanic group. the palaeomagnetic direction from seven sites of the Miocene volcanics shows no deflection of declination value (D= 5.9°, I= 43.8°, α95= 14.00). the direction from the volcanic rock of 1.2Ma is D=2.5° and I= 53.3°. the reliability of the direction is ascertained through thermal demagnetization, positive fold test and the presence of normal and reversed polarities. Comparison of Neogene palaeopoles between northern Taiwan and China indicates that little relative tectonic movement has occurred in northern Taiwan since 20 Ma. These results establish that the arcuate shape of geological belts in northern Taiwan is not due to tectonic bending but to an inherited geometry. Reconstruction of the 10 Ma palaeoposition of Taiwan and the south Ryukyu arc implies that the cusp shape at the arc junction has already existed prior to 10 Ma.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-246X.1993.tb03912.x
