Kinematics - Philippine Sea Plate & Marginal Basins

4.0 km

Depth of South China Sea Basin

Pautot et al. (1986)

2 stages of SCS opening:

1. 32 - 17 Ma along E-W axis

2. 20 - 17 Ma along NE-SW axis

Holloway (1982) and Taylor & Hayes (1983)

Model 1 for SCS:

• put the spreading, the prominent ridge being the Scarborough Ridge, in the basin on a roughly NE-SW direction starting around 32 Ma (Oligocene).

Briais et al. (1993)

Model 2 for SCS:

• showed a progressive change in the orientation of the spreading system: roughly ENE-WSW from 32-30 Ma (Oligocene) and E-W from 30-27 Ma. By 26-24 Ma, the ridge jumped to the South, and a second basin started forming to the Southwest.

• suggested that the SCS spreading ceased around 15.5 Ma (Middle Miocene).

Barchausen & Rosser (2002)

Proposed the spreading of SCS ceased somewhat earlier, ~18 Ma.

• NW sub-basin - ENE-WSW spreading during 32-30 Ma.

• WE sub-basin - E-W spreading during 30-27 Ma.

• SW sub-basin - NE-SW spreading 26-24 Ma.

Essentially three sub-basins for the South China Sea according to Briais et al. (1993)

Rangin et al., (1990)

Model 3 for SCS:

• Trench pull.

• Gravity-controlled trench-pull may be invoked to explain the rifting and spreading. The subduction along the Sunda Trench may be responsible for the opening of the proto-SCS (and even Celebes Sea) and the subduction of the proto-SCS south of Palawan may in turn explain the South China Sea opening.

Pubellier et al. (2003)

Model 3 for SCS:

• Trench rollback (Back-arc basin model).

• Rolls back due to getting longer as it subducts, and initiates spreading.

Tapponier et al. (1982; 1986)

Model 4 for SCS:

• South China Sea opened as a side effect of the extrusion of Indochina

• Contention: Timing of collision vs. opening of SCS & difficult to reconcile with a N-S spreading of the SCS.

Rangin & Silver (1991)

Characterized SSB:

• Situated immediately to the southeast of Palawan, this small marginal basin composed of two sub-basins that are separated by an E-NE trending Cagayan de Sulu Ridge (CRS)

• Formed starting at around ~20 Ma (Early Miocene)

Rangin & Silver (1991) - 2

Model 2 for SSB Formation:

• The geochemcial signature of the oceanic basement, along with the basin’s position and age correlation with the arc volcanism along the CSR, suggests a back-arc spreading (starting ~20 Ma) origin for the Sulu basin.

• Arc volcanism along the CSR ceased around 16 ma, following its collission with the rifted margin of China (Palawan Micro-continental block)

Rangin & Silver (1991) - 1

Model 1 for SSB Formation:

• Formed through spreading along the Cagayan de Sulu Ridge (CSR)

• Discredited. Basins opposite of the Cagayan de Sulu Ridge have different geochemical signature.

• NW sub-basin- Continental basement

• SE sub-basin - Oceanic basement

Celebes Sea Basin (CSB)

Basin located southeast of the Sulu Basin & Sulu-Zamboanga Arc

Lee and McCabe (1986)

Model 1 for CSB formation:

• a trapped basin mechanism for CSB; could have split off as a basin from a previously larger Molucca Sea Plate.

Silver & Rangin (1991)

Model 2 for CSB formation:

• a) Fragment of WPB

• b) Back-arc basin

• c) basin rifted from the SE continental margin

Hall (1996) and Nichols & Hall (1999)

Model 3 for CSB formation:

• A fragment of the West Philippine Basin (WPB) of the Philippine Sea Plate.

• argued that the CSB and WPB formed part of the same ocean basin with similarities in basement age, chemistry and stratigraphy.

West Philippine Basin (WPB)

Occupies 50% of the Philippine Sea Plate

Central Basin Fault (Lineament)

Lineament where West Philippine Basin opened

Hilde and Lee (1984)

2 Stages of Opening of the WPB:

1. 60 and 45 Ma at NE-SW - 4.4 cm/yr half spreading rate

2. 45 and 35 Ma at NS orientation- 1.8 cm/yr half spreading rate

Trapped Oceanic Basin

by Uyeda and Ben-Avraham (1972), Hilde (1977), Lee (1984)

Model that suggests WPS as a trapped piece of the Pacific Plate during the 43 Ma kinematic reorganization of the Pacific Plate.

Back-Arc Basin Model

by Karig (1975), Mrozoqki et al. (1982), Seno and Maruyama (1984)

Model stating that WPB formed by back-arc spreading behind the Oki-Daito Ridge.

N-S

PVSB’s oceanic crust accelerates on a ______ spreading-axis.

Mrowzoski and Hayes (1979); Kobayashi and Nakada (1987):

Model for Opening of PVSB:

• 1st stage: 30 Ma - Parece Vela

• 2nd stage: 10 Ma - Shikoku

• Oceanic accretion stopped at around 17 Ma

Marianas Basin (MB)

Philippine oceanic basin that opens around 6 Ma at a NS spreading axis and still presently active

Ayu Basin

Philippine oceanic basin that is a poorly known portion of the southern extremity of the plate.

Palau-Kyushu Ridge

• Submarine ridge in the PH Sea Plate that divides the WPB and PVSB

• 2,500 km long

Trapped Basin Model

Model for Palau-Kyushu Ridge:

• Volcanic arc formed from the transformation of a transform fault to subduction zone at around 43 Ma.

• Subduction retreated at 30 Ma and stopped, signifying the start of the opening of Parece Vela-Shikoku Basin

Izu-Bonin Ridge

Submarine ridge in the PH Sea Plate:

• Eastern limit of Shikoku Basin

• Volcanic arc of the active Bonin Trench colliding with the Japanese margin - Izu Peninsula in Central Japan

• West and East Marianas Ridge define limits of Marianas Basin

West Marianas Ridge

Ancient volcanic arc of the Izu-Bonin Ridge that was active between 20-9 Ma.

East Marianas Ridge

Volcanic arc of the active Marianas Trench (part of the Izu-Bonin Ridge)

Old-Day Kinematics

4 Ma PLATE REORGANIZATION

• Relative movement changed from NNW to WNW since 5 Ma based on Taiwan collision and lzu-Misira-Boso region of Japan.

• In Taiwan, at 4 to 6 Ma, 40° CCW.

• In Japan, at 2 to 3 Ma, 30° CCW.

Present-Day Kinematics

NW DISPLACEMENT DIRECTION

3 Main Kinematic Parameters with respect to Eurasia:

• 1. Rotation pole located NE of Japan.

• 2. Relative displacement rate varies from N to S along the western edge of the PSP:

  • 3 cm/yr - Latitude of the Nankai Trough.

  • 9 cm/yr - Southern end of the Philippine Trench.

• 3. Relative displace direction whose azimuth is directed NS5W near Taiwan with a linear velocity around 7 cm/yr.