Introduction:
With the advances made in recent years on surface geology, subsurface geophysical velocity/electrical-resistivity imaging and geodesy, among others, Taiwan has become one of the best studied active orogens. We are now in a position to pose and test hypotheses of how Taiwan evolved as a mountainous island in the recent few million years. As a young structure, however, the materials under the mountain ranges are not totally exposed; thus additional constraints are need in interpreting available observations in terms of minerals and rocks and the ongoing geological processes. To explore possible orogenic models we may resort to reexamination and comparison of other, and especially, old orogenic belts, some of which are deeply eroded and thus the materials in the core of the mountains are now exposed. On the other hand, for the Taiwan orogen our knowledge of the plate tectonic framework, the subsurface structures under various parts of the orogen, the kinematics of the orogeny based on earthquake mechanisms and GPS measurements, the possible rheological properties of the crust or even current temperature in the core of the mountains provide clues of conditions at depth during the active phase of orogeny. By using “the present” (i.e., Taiwan) as “a key to the past” and the “past” (the exposed core of old orogens) as “a key to the depth” is the best we can do to improve our knowledge for mountain building as a whole.
One of the ancient arc-continental orogens that appears to share several common tectonic characteristics with Taiwan is the west Ireland Lough Nafooey (arc)-Laurentian margin collision (the Grampian orogeny) (Figs. 1 and 2). It took place in early-mid Ordovician (475-462 m.y. bp). From each of the mountains around the world, depending on the age and degree of erosion we may compare field evidence and distill/test ideas concerning detailed geological processes of orogeny. While the materials internal to the different provinces of the ancient (inactive) orogen provide examples of what could be underneath the Taiwan orogen, the rheological properties of the crust gained from seismic data.
Location: Ireland
Date: 3rd to 9th September, 2016
Pre-Workshop: 10 am, 12th August (Fri.), 2016 (Seminar room, 6F, IES, Taipei, Taiwan)
Papers for discussion at pre-workshop:
1. Paul Ryan, 2007, Preservation of forearc basins during island arc–continent collision: Some insights from the Ordovician of western Ireland.
2. Paul Ryan and John Dewey, 2004, The South Connemara Group reinterpreted: a subduction-accretion complex in the Caledonides of Galway Bay, western Ireland.
Schedule:
1. Taiwan and western Ireland orogenies and understanding of mountain building in general (Francis Wu)
2: Field trip logistics (Hao Kuo-Chen)
3. “Typical” Taiwan cross sections from Coastal Range to Coastal Plain and comparative sections of west Ireland from literature by Ryan, Dewey etc. (paper reviews)
4. Summary: Key factors to explore in comparing Taiwan and western Ireland (Yuan-hsi Lee)
(papers: https://drive.google.com/open?id=0B-EDE3vF4TuoSHFiVUdPTWt1Zjg)
Workshop Agenda (9/3~9/9)
| Date | Schedule |
| 9/3 | Presentation and Discussion |
| 9/4 | Field work (290 km):
Leenane- loop around south of Achill Island – Bellmullet (Scotchport Bay near Erris Head) – Leenane |
| 9/5 | Field work (102 km):
Leenane – Louisburgh – Roonagh Quay – Westport – Leenane |
| 9/6 | Field work (55 km):
Leenane – Finny – Glensaul – Leenane |
| 9/7 | Field work (40 km):
Leenane – Letterfrack – Rosroe – Leenane |
| 9/8 | Field work (110 km):
Leenane – Maam – Maam Cross – Glencoaghan (we might have to miss this depending on the coach size) – Clifden – Alcock Brown Monument – Ballyconneely – Letterfrack -Leenane |
| 9/9 | Field work (140 km):
Leenane – Maam Cross – Costelloe – Carraroe – Lettermullen – Leenane |
Presentation on 9/3
| Time | Presenter | Title |
| 9:00-9:20 | Hao-Tsu Chu, Central Geological Survey | Recent progress on the study of pseudotachylite |
| 9:20-9:40 | Yuan-Hsi Lee, National Chung Cheng University | A major out of sequence fault in Center Range and its implication to mountain building process of Taiwan orogeny |
| 9:40-10:00 | Jian-Cheng Lee, Academia Sinica | Architecture and slip behaviors of the Longitudinal Valley fault system in eastern Taiwan |
| 10:00-10:30 | Break | |
| 10:30-10:50 | Yu-Chang Chan, Academia Sinica | Towards high-resolution geological mapping using recent technological methods |
| 10:50-11:10 | Chih-Tung Chen, National Taiwan University | Complex accretion history of continental margin sediments in the Taiwan Orogen: prolonged wedge thickening through basal accretion revealed by thermal-chronological constraints from the slate terrain |
| 11:10-11:30 | Chin-Ho Tsai, National Dong Hwa University | New P-T and geochronological constraints on high-pressure metamorphic rocks in the Yuli belt, eastern Taiwan |
| 11:30-13:30 | Lunch | |
| 13:30-13:50 | Ruey-Juin Rau, National
Cheng Kung University |
Spatial and temporal stress permutation in Taiwan |
| 13:50-14:10 | Wei Lo, National Taipei University of Technology | Development of slaty cleavage and its tectonic significance in Suao, northern Taiwan |
| 14:10-14:30 | Hao Kuo-Chen, National Central University | Seismic evidence for the a-b quartz transition beneath Taiwan from Vp/Vs tomography |
| 14:30-15:00 | Break | |
| 15:00-16:00 | Discussion and conclusion (leaded by Francis Wu) | |
| 16:00-17:00 | Introduction to Field work (Paul Ryan, Dennis Brown, and John Dewey) | |
Accommodation:
Convent Guest House (www.theconvent.ie)
Bed, breakfast, packed lunch and a 2 course evening meal (main course plus choice of either starter or sweet) at the Blackberry Restaurant. (€70 per person per day)
Transportation:
A small Bus: €2590 (include airport pickup and drop off) gasoline €??
Pick up at 13:30 pm on 9/2 (Driver: Pat Lydon)
The coach driver’s mobile is: +353 87 2673126
Participants:
1. Francis Wu, Binghamton Uni., USA (Convener)
- Bob Wintsch, Indiana University, USA
3. John Dewey, Uni. College Oxford, UK (field trip organizer)
- Paul Ryan, National University of Ireland, Ireland (field trip organizer)
- Dennis Brown, Instituto de Ciencias de la Tierra “Jaume Almera”, CSIC, Spain (field trip organizer)
- Cristina Biete, Instituto de Ciencias de la Tierra “Jaume Almera”, CSIC, Spain
- Hao-Tsu Chu, Central Geological Survey, Taiwan
- Yuan-Hsi Lee, National Chung Cheng University, Taiwan
- Jian-Cheng Lee, Academia Sinica, Taiwan
- Yu-Chang, Chan, Academia Sinica, Taiwan
- Chih-Tung Chen, National Taiwan University, Taiwan
- Chin-Ho Tsai, National Dong Hwa University, Taiwan
- Ruey-Juin Rau, National Cheng Kung University, Taiwan
- Wei Lo, National Taipei University of Technology, Taiwan
- Hao Kuo-Chen, National Central University, Taiwan
Last Updated: August.12.2016