GOP Reviewer (COLLECTED)

REGIONAL DYNAMIC SETTING

The 3 plates surrounding the Philippines:

1.    Pacific Plate- entirely oceanic crust

Age: 150 MY ( Late Jurassic)

Rate: 80 mm/yr

            2 Kinematic Reorganization:

-43MY ( Eocene) - 50⁰ Counter Clockwise Rotation from NNW to WNW

                        -5 MY (Late Miocene) - 10⁰ counter CW Rotation

2.    Eurasian Plate – Entirely continental except the marginal basins

Rate: 3mm/ yr ( Fixed since 50MY- Late Miocene)

3.    Indo- Australian Plate

Rate: 107 mm/ yr

*** Separation of India and Australia: 150 MY Late Jurassic and cessation of the MOR : 43 MY -Middle Eocene

SE ASIAN REGION

            SW Portion of the Western Pacific Domain

THE PHILIPPINE SEA PLATE

OCEAN BASINS

1.    WEST PHILIPPINE BASIN (50% of the PSP)

Age: 60 and 35 MY from Paleomagnetic Data, 53 and 42 from Deep  Sea Drilling data.

Consists of Submarine Plateaus:

1.    Benham Rise (Eocene)

2.    Urdaneta Plateau

3.    Anami and Oki Daito Ridge

Central Basin Fault – WNW to ESE Lineament --- Extinct MOR

            2 Stages of Opening:

                     60 and 45 MY at NE- SW (4.4 cm/ year of half spreading rate)

                     45 and 45 MY at NS orientation (1.8 cm/yr)

Basin’s Origin:  (2 model)

1.    Trapped Oceanic Basin by Uyeda and Ben- Avraham, Hilde, Lee.

2.    Back Arc Basin  Model by Karig, Mrozowki, Seno, Maruyama.

***According to the Back Arc Basin Model, the Oki- Daito would correspond to a relict volcanic arc that travelled to the NE during the opening of the Basin.

KINEMATICS OF THE PHILIPPINE SEA PLATE

            Present Day Kinematics: NW Displacement Direction

                        3 main Kinematic Parameters of the PSP with respect to Eurasia:

1.    Rotation Pole NE of Japan

2.    Displacement Rate

3.    Displacement Direction

Old Kinematics: 4 MY plate reorganization

            NNW to WNW since 5MY

Marginal Basins of the Eurasian Plate

1.    South China Sea Basin (Oligocene)

NE –SW Orientation with an average depth of 4km

      Opening: 32 and 17 MY (Eocene)

      Rifting: Cretaceous to Eocene (NW-SE)

2.    Sulu Sea Basin (Miocene)Divided into 2 basin by the Cagayan Ridge(14.7MY):

1.    NW Sub Basin

2.    SE Sub Basin

3.Celebes Sea Basin (Eocene)

ORIGIN OF MARGINAL BASIN MODELS:

            Back- Arc Basin (Karig)

            Continental Domain Basin (Taylor and Hayes)

            Extrusion Tectonics Basin (Tapponier)

            Trapped Basin  ( Hilde, Lee, Ben- Avraham, Uyeda)

The Philippines: A Complex Plate Boundary

             The Philippine Mobile Belt (by Gervasio)

            An actively deforming zone between the PSP and Eurasian Plate

General Geodynamic Framework of the Philippines

The Philippines is a collage of insular arcs, ophiolitic suites and continental rocks of Eurasian affinity.

SUBDUCTION ZONES:

West- Dipping Subduction Zones

1   1. Philippine Trench ( 4- 15 degrees North)

-Due to the subduction of the PSP beneath the Philippine Arc.

-Evidence: Volcanism from bicol to Leyte but in Mindanao it Becomes unclear

- Not earlier than 5MY – PLIOCENE

2. East Luzon Trough ( 16 degrees to 18 degrees)

            -no corresponding volcanic arc

- but there are presence of subduction related magmatism in East Luzon.

East- Dipping Subduction Zones

1.    Manila Trench ( 22- 13 degrees north)

-        Sedimentary Fill: 250- 2600 m

-        Well developed accretionary prism

2.    Negros Trench (10 degrees North)

3.    Cotabato Trench ( 6 degrees North)

Collision Zones

1.    Taiwan : Continent- arc collision

2.    Mindoro- Panay: arc- continent collision

3.    Moluccas Sea: arc-arc collision