Radiolarian dating of ophiolites and

the cover turbidites in Philippine Mobile

Belt, Northern Luzon Island

Keisuke ISHIDA1, Shigeyuki SUZUKI 2,

Carla B. DIMALANTA 3 and Graciano P. YUMUL, Jr. 3

1 Institute of Socio-Arts and Sciences, University of Tokushima

2 Department of Earth Sciences, Okayama University 3 National Institute of Geological Sciences, University of the Philippines

J-K

NW Dingalan

J-K

Eoc

Eoc

Cabog Fm.

Zambales

Ophiolite Complex

Southern Sierra

Madre （Rizal)

“Older Philippine Fault”

・Basement of PMB is mainly composed of ophiolites overlain by Paleogene to

Miocene turbidites in Central Luzon

・Radiolarian dating of siliceous sediments in ophiolites and turbidites

Yumul ＆Dimalanta, 1997

Yumul et al., 2008

Zambales Ophiolite

Complex (BMG, 1981):

・peridotite, gabbro,

diabasic dike complex,

diorite, pillow basalt,

pelagic limestone,

sandstone, and mudstone

・Chert blocks distributed

in the serpentinites yield

Late Mesozoic radiolarian

faunas

(Late Jurassic /

Early Cretaceous)

4-4 Green ch

4-1 Green ch

4-2 Red ch

・Multisegmented nassellarian genera dominates faunas

Archaeodictyomitra, Xitus, Pseudodictyomitra, Pseudoeucyrtis etc.

with association of Triactoma and Tetraditrymina

・Ages were estimated as Late Jurassic / Early Cretaceous

Subfamily Tetraditriminae

Baumgartner, 1980

4-2 Red ch

Ｒａ

T

R JURASSIC CRETACEOUS

PL

G

L EARLY MIDDLE LATE EARLY LATE

R

h Het

Si

n Pli Toa

Aa

l

Ba

j

Ba

t

Ca

l Oxf

Ki

m Tit

Be

r Val

Ha

u Bar

A

p

t

Alb Cen Tu

r

Co

n

Sa

n

Ca

m

Ma

a

1

5

1

6

1

7

1

8

1

9

2

0

2

1

2

2

2

3

2

4

2

5

2

6

2

7

2

8

2

9

3

0

3

1

3

2

3

3

3

4

3

5

3

6

3

7

3

8

3

9

4

0

4

1

4

2

4

3

4

4

4

5

4

6

4

7

4

8

4

9

5

0

5

1

5

2

5

3

5

4

5

5

5

6

5

7

5

8

5

9

6

0

6

1

6

2

6

3

6

4

6

5

6

6

6

7

6

8 Archaeodict

yomitra spp.

Mictyoditra

spp.

Pseudoeucy

rtis spp.

Pseudodictyomitra spp.

Triactoma

spp.

Xitus

spp.

Tetraditrimia

spp.

Zambales red ch 2

Zambales greench 1

Zambales greench 4

NW Dingalan red ch Radiolarian dating of cherts in

Zambales and NW Dingalan

Ju

ra－

Cre

t

Pa

leo

E

oc

en

e

Cabog

Fm．

turbidite

“O

lder

Ph

ilip

pin

e F

au

lt”

Ph

ilip

pin

e F

au

lt

Caraballo

Formation

Turbidite

East Rizal, S. Sierra

Madre Mt. R.

Oli

go

Up. Cret.

Kinabuan F. arc volcanism

Maybangain

Formation

turbidite clastic-volcanic

member

Masungi Limestone ＠

Member

★

Binangonan Fm.

limest./clastics

with coal

measure

late Olig.- e. Mio.

late Eoc Masungi

Limestone（foraminiferal）

Eq. Binangonan F.

Carbonates/pebbly

clastics

★

Aksitero

Formation tuffaceous

turbidite

hemipelagic＠limestone

44-48 Ma

intrusion

arc volcanism chert bands

Mio

Zambales

Zambales

Ophiolite

Complexes

★

N. Sierra

Madre

at NW

Dingalan

chert

in

ophiolite

★ Montalban

Ophiolitic

Complex

chert in

Lubingan

Formation ★

Cabog,

S.

Dingalan

Bay

Dibut Bay

Meta-ophiolite 92.0±0.5Ma

Aksitero Formation (Amato, 1965): •Oldest sedimentary cover of ZOC •Composed of hemipelagic limestone and clastic rocks •Age is late Eocene to late Oligocene based on foraminifers •Zircon U-Pb age of middle Eocene corresponds to intrusion of the volcanic-plutonic rocks (plagiogranite and gabbro) •Late Mesozoic radiolarians from chert blocks witness the age of older ophiolites as remnants of oceanic crust before arc volcanism

Rizal ch/turbidite

Montalban Ophiolitic Complex (MOC; MGB, 2004):

・Lower basalts of ophiolite are MORB character

・Upper andesite-basalt has island arc tholeiite (IAT) signature (Arcilla, 1991)

Kinabuan Formation: sedimentary cover of MOC

・Top radiolarian-bearing bathyal limestone (Ringenbach, 1992) dated Santonian to Early Maastrichtian by planktonic foraminifers (Reyes and

Ordonez, 1970; Hashimoto and others, 1979; Haeck, 1987).

・Campanian radiolarians form cherty bands (Tumanda,1994) .

・Turonian age by radiolarians and pelagic foraminifera (Arcilla, 1992).

Southern Sierra Madre at Rizal

Rizal ch/turbidite 110110-2

Maybangain Formation conformably overlays on Kinabuan Formation: ・Composed of Masungi Limestone Member and clastic-volcanic member (Peña, 2008). ・Early/middle Paleocene to middle Eocene (MGB, 2004). ・Thin alternation of red cherty mudstone and graded fine volcanic sandstone yields well-preserved radiolarian fauna

Radiolarian fauna of Maybangain Formation:

・is characterized by Podocyrtis mitra, Sethochytris triconiscus,

Lithochytris vespertilio and Eusyringium fistuligerum with nearly 20

gen. spp. including Dictyoprora mongolfieri, Amphisphaera

coronata s.l.

Age PALEOCENE EOCENE OLIGOCENE

Early Late Early Middle Late Early Late

Zones unzoned B.campechensis

B. bidartensis B. clinata P. striata T.cryptocephala

D.mongolfieri

T.triacantha

P. ampla

P. mitra P. chalara P.goetheana

C. azyx

C. bandyca

C. ornatum

T. tuberosa D. ateuchus

N. Cabog: Cabog Formation turbidite

Amphisphaera coronata s.l. (Ehrenberg)

Calocyclas hispida (Ehrenberg)

Dictyoprora mongolfieri (Ehrenberg)

Lychnocanoma sp. cf. L. bellum (Clark & Campbell)

Podocyrtis (P.) diamesa Riedel & Sanfilippo

Podocyrtis (P.) aff. papalis Ehrenberg

Sethochytris babylonis (Clark & Campbell)

Rizal : Maybangain Formation turbidite

Amphisphaera coronata s.l. (Ehrenberg)

Dictyoprora mongolfieri (Ehrenberg)

Eusyringium fistuligerum（Ehrenberg)

Sethochytris triconiscusHaeckel, 1881

Thyrsocyrtis cf. rhizodon

Cryptoprora ornata Ehrenberg, 1873

Podocyrtis mitra (Ehrenberg)

Podocyrtis helenae Nigrini

Calocyclas hispida (Ehrenberg)

Sethochytris babylonis (Clark & Campbell)

Lithochytris vespertilio Ehrenberg, 1873

Age PALEOCENE EOCENE OLIGOCENE

Early Late Early Middle Late Early Late

Zones unzoned B.campechensis

B. bidartensis B. clinata P. striata T.cryptocephala

D.mongolfieri

T.triacantha

P. ampla

P. mitra P. chalara P.goetheana

C. azyx

C. bandyca

C. ornatum

T. tuberosa D. ateuchus

Fauna of Maybangain Formation:

・belongs to middle Eocene P. mitra Zone

・slightly younger than Cabog Formation turbidite along

southern Dingalan Bay (Ishida et al., 2011).

Radiolarian assemblage of

middle Eocene Cabog

Formation (Ishida et al.,

2011):

・correlative with D. mongolfieri

Zone / T. triacantha Zone.

Maybangain and Cabog

formations: similar in deeper-water

lithofacies of chert / siliceous shale-

intercalated distal turbidities.

Ju

ra－

Cre

t

Pa

leo

E

oc

en

e

Cabog

Fm．

turbidite

“O

lder

Ph

ilip

pin

e F

au

lt”

Ph

ilip

pin

e F

au

lt

Caraballo

Formation

Turbidite

East Rizal, S. Sierra

Madre Mt. R.

Oli

go

Up. Cret.

Kinabuan F. arc volcanism

Maybangain

Formation

turbidite clastic-volcanic

member

Masungi Limestone ＠

Member

★

Binangonan Fm.

limest./clastics

with coal

measure

late Olig.- e. Mio.

late Eoc Masungi

Limestone（foraminiferal）

Eq. Binangonan F.

Carbonates/pebbly

clastics

★

Aksitero

Formation tuffaceous

turbidite

hemipelagic＠limestone

44-48 Ma

intrusion

arc volcanism chert bands

Mio

Zambales

Zambales

Ophiolite

Complexes

★

N. Sierra Madre

at NW Dingalan

chert

in

ophiolite

★ Montalban

Ophiolitic

Complex

chert in

Lubingan

Formation ★

Cabog, S.

Dingalan

Bay

Dibut Bay

Meta-ophiolite 92.0±0.5Ma

Cabog Formation is correlative with

Maybangain Formation turbidite

and distal part of Caraballo Formation

Cabog Formation (Ishida et al., 2011)

・Radiolarian assemblage suggests a low paleolatitude affinity

・Sandstone composition and radiolarian age represents early

arc-setting (Suzuki et al., 2011)

・Northward migration related with Philippine Sea Plate motion

along the Older Philippine Fault from equatorial area

Northern Sierra Madre at NW Dingalan: East side of Philippine Fault

・ Phyllites are regarded as cover of Cretaceous Dibut Bay Meta-ophiolite

(Billedo, et al. 1996) (“Baler Ophiolite”)

Billedo (1996)

030508-3 red ch

Northern Sierra Madre at NW

Dingalan: East of Philippine Fault

・ Ophiolitic basic tuff phyllites

(Lubingan Formation) as a cover

of Cretaceous Dibut Bay Meta-

ophiolite (Billedo, et al. 1996)

(“Baler Ophiolite”)

・Red chert block in the phyllite

was dated as Early Cretaceous by

Mictyoditra sp.

・Spherical tests were deformed

in oval

chert in

Lubingan

Formation ★

Dibut Bay

Meta-ophiolite 92.0±0.5Ma

★ ★

Scotese (2002)

★

Paleobiogeographic and

ocean-climatic conditions

inferred from the radiolarian

faunas:

・ Late Mezozoic radiolarian

fauna from Zambales Ophiolite

Complex is common in Tethyan

pelagic environment (O’dogherty

et al., 2009).

・ Middle Eocene radiolarian

fauna from Maybangain

Formation is regarded as

warmer current affinity.

It suggests the effect of global warmer period during late

Paleocene - middle Eocene

(eg. Salamy and Zachos, 1999;

Slujis et al., 2005).

Late Jurassic (152 Ma)

★

★ ★

Eocene (49-37 Ma) Golonka (2004)

Geological development of PMB

•Zambales Ophiolite Complex: remnants of Late

Mesozoic oceanic crust prior to arc volcanism; Tethyan

pelagic radiolarian fauna

•Aksitero Formation: adjacent to an active arc system

•Montalban Ophiolitic Complex: lower basalts - MORB

type; upper andesite basalt - island arc tholeiite (IAT)

•Maybangain Formation: Middle Eocene warmer-current

radiolarian fauna

•Cabog Formation: first depositional stage in the early

arc-setting; correlative with Maybangain Formation

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