Apatite Fission Track Dating of the Fold-and-Thrust Belt in Northern Taiwan and its Tectonic Implications
Date Issued
2011
Date
2011
Author(s)
Lai, Pei-Chi
Abstract
Taiwan mountain belt was resulted from the collision between NE trending continental margin of the Eurasia and N-S trending Luzon arc on Philippine Sea plate.The Philippine Sea plate moves in NW direction that results in an oblique collision and the mountain building propagates southwardly, with a rate of 50-90 km/Ma. This model suggests that the development of the fold and thrust propagates southwardly.
With the cessation of active folding and thrusting during the collision, northern Taiwan is now undergoing post-collisional extension, followed by the eruption of the
Tatun volcanoes since 2.6Ma.
In this study, we examine the fission track systematics of apatites from the fold and thrust belt in northern Taiwan. Forty-one rock samples were successfully collected from the Tertiary sequences but only sixteen of them yield enough apatites with reliable ages. The results show that the reset boundaries of the apatite fission tracks are quite different between the eastern and western sides of the Chushih fault.
In the western side, the reset boundary appears in the Miocene Mushan Formation. In contrast, it locates in the Oligocene to Eocene formations on the eastern side. The
difference of reset boundary may reflect the thickness difference of the sedimentary sequences on both sides. On the hanging wall the sequence thickness above the Oligocene Formation may have been less than 4~5 km, as reflected by the partial reset ages. By contrast, the resetting boundary is located in the Miocene Mushan Formation, which is much younger than that on the hanging wall, due to the thicker foreland basin deposits. The oldest total reset ages appear to be near 3 Ma from the formations on hanging wall of the Kanchiao fault and Chushih fault, indicating that the
fault-and-thrust belt in northern Taiwan may have been developpned at near 3 Ma. This age appears to be similar to that discovered in southern Taiwan. This similarity further implies that the southward propagation model of the fold-and-thrust belt in Taiwan has not gained supports from the fission track data.
Subjects
Northern Taiwan
fission track
SDGs
Type
thesis
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