Intermission

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Intermission
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Leos section

• Macro-geomorphological evidence
• Long term denudational history from
  thermochronometric evidence

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Macro-geomorphological evidence

• High relief concentrated on retro-wedge.
• At 120km N of tip
• height 1350m
• Width 87 4 km

PRO
RETRO
From Fuller et al., 2003
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• (From Willett et al., 2002)

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Macro-geomorphological evidence

• High relief concentrated on retro-wedge.
• At 120km N of tip
• height 1350m
• Width 87 4 km

PRO
RETRO
From Fuller et al., 2003
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• In spite of the increasing age of the collision
  to the north, the average elevation and width of
  the Central Range does not increase along its
  northern two-thirds. This has led to the proposal
  that the range is in topographic steady-state.
  (Willett et al., 2001)

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Long term denudational history from
thermochronometric evidence

• Which thermochronometers were used?
• Apatite fission-track
• Zircon fission-track

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Zircon fission-track data
From Willett et al., 2002

• gt 120 km north of Taiwans southern tip
• Reset zircon ages
• lt 40 km north of Taiwans southern tip
• No reset zircon ages
• Southern tip recently exhumed

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Zircon and Apatite fission-track data

• Apatite reset zone extends further than Zircon
  reset zone.
• Willett and Brandon (2002) state that nested
  reset zones, indicate exhumational steady state

From Willett et al., 2003
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Zircon and Apatite fission-track data

• Apatite reset zone extends further than Zircon
  reset zone.
• Willett and Brandon (2002) state that nested
  reset zones, indicate exhumational steady state

From Willett et al., 2003
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Long term denudational history from
thermochronometric evidence

• Thermochronometers suggest that Taiwan northern
  part is in exhumational steady state.
• Southern (120 km) is too recent exhumed to give
  evidence of long term denudation.

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Conclusions

• Seismicity
• ?
• Climatic factors
• ?
• Geomorphic processes?
• Marco-geomorphology
• Denudational history from thermochronometry

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Any Questions?