Theme:

Transition from Accretion to Collision in the Incipient Taiwan Arc‐continent Collision Zone: Along‐strike Variability of Structural Styles, Fault Activities, Fluid‐Flow Systems and Implications for Geohazards

Date:

2nd - 3rd August 2016

Agenda:

Venue:

S135, Department of Earth Sciences, National Central University

Hotel:

Hotel Kuva Chateau, No. 398 Minchuan Road, Zhongli, Taoyuan

Note

  1. Contact meeting secretary, Ann Lee, at operaann@gmail.com, for booking the hotel for you to get cheaper room rates.
  2. We will provide transportation from the hotel to the meeting venue during 2nd and 3rd August.
  3. Airport to hotel: see http://www.kuva-chateau.com.tw/01_info.asp?sn=82

Purpose of WS:

To prepare an IODP pre‐proposal, we will

  1. Share the current ideas
  2. Examine the existing site survey data
  3. Discuss and deepen the initial scientific ideas
  4. Discuss potential problems / weaknesses
  5. Examine the sites
  6. Discuss necessity of more site survey data
  7. Confirm the schedule
  8. Write up the pre‐proposal

Travel expenses:

There might be limited amount of budget for international participants. If you can use your own budget, it would be highly appreciated.

Potential working groups:

  1. Tectonics and structures
  2. Fault zones and wedge mechanics
  3. Geohazards
  4. Paleoceanography
  5. Carbon cycles, fluid flows and microbiology

For those who wish to participate

Please send following info to the contact address (below).

  1. your participation to the project: Y / N
  2. brief description on how you can contribute / your interests

Contact address:

taiwan_ws2016@jamstec.go.jp

Organizers:

Yasuhiro Yamada1, Andrew Lin2, Char‐Shine Liu3

  1. R&D Centre for Ocean Drilling Science (ODS), JAMSTEC, Japan
  2. Department of Earth Sciences, National Central University, Taiwan
  3. Institute of Oceanography, National Taiwan University, Taiwan

Endorsed by Japan Drilling Earth Science Consortium (J-DESC)

Brief description of the project:

The offshore incipient arc‐continent collision zone of Taiwan features the Manila accretionary wedge impinging upon the northern rifted continental margin of the South China Sea. Along the structural strike, the accretionary complex evolves from typical oceanic accretion in the south to collision of accreted materials with continental slope in the north. This along‐strike change in tectonic setting has brought about significant lateral changes in geometry and activity of faulting/folding/diapirism in the deformed wedge. We hypothesize that this along‐strike change is controlled by lateral changes of the mechanics of the deformed wedge as well as the fluid flow circulation patterns. Slips of major faults in the accretionary wedge (such as the mega‐splay fault and plate boundary decollement and megathrust) produce great earthquakes and pose great threats to Taiwan together with coastal cities around the South China Sea if tsunami is induced by faulting. In particular, the mega‐splay fault in the accretionary wedge extends from offshore in the south to onshore SW Taiwan with great geohazards concerns.Read more »

The unique tectonic setting off SW Taiwan provides with us an unparalleled opportunity to examine the controls on structural styles, faulting activities, fluid‐flow circulation along the structural strike and their implications for geohazards. Here we have a plan of 9 drill sites to test our hypothesis:

a)
Two sites as background sites will recover sediments in the incoming plates. The southern site located in the abyssal plain of the South China Sea, representing sediments prior to accretion. The northern background site located in the upper continental slope and on the side of a gas chimney structure with active seafloor venting. This site represents sediments and fluids prior to thrust‐wedge impingement onto the continental slope.
b)
Two sites along the length of the frontal decollement fault are designed to penetrate through the fault to understand the physical and fluid properties of the fault and its slip rates.
c)
Three sites along a transect crossing the mega‐splay fault, is designed to understand the physical properties, fluid flows, carbon cycles and slip history of this tsunamogenic fault. Two of these boreholes will penetrate through a stack of Mass Transport Deposits (MTDs), presumably caused by slips of the mega‐splay fault, both in the hangingwall and footwall of the fault.
d)
Another two sites are designed to understand the fluid sources and carbon circulation in the deformed prism. One will penetrate an anticlinal ridge in the lower slope domain, where gas hydrate deposits can be identified, to understand fluid source from shallow sedimentary section. The other site locates on the flank of a giant mud volcano in the upper slope domain, in a view to understand advection of deep‐seated fluid sources through vertical fluid conduits.

Combined with results from ODP 184, IODP 349 and the upcoming IODP 367‐368 in the South China Sea, the drilling proposed here will help to understand how the incoming sediments and crustal structures exert controls on wedge deformation and fluid circulations.

Shaded relief map in the incipient arc‐continent collision zone of Taiwan. Yellow stars indicate possible locations for IODP drilling.