Today is

 

 

SPECULATIONS ON THE LATE MESOZOIC AND CENOZOIC
EVOLUTION OF THE SOUTHEAST ASIAN MARGIN

Robert McCabe and Jay Cole
Department of Geophysics
Texas A&M University College Station, Texas
 

 

 

 

ABSTRACT



The Sulu-Celebes-Banda Basins are lhree poorly understood marginal basins located
between northwest Australia and southeast Asia. Analysis of magnetic anomalies, heatflow
data, bathymetry and on-land geology has led to the conclusion that these three basins are
the remnants of a once-continuous ocean basin (Lee and McCabe, 1986). ldentified east-
west trending anomalies in all three of these basins sugest the following ages: Banda (119-
136 MaB.P.) (Lapouille et al.; recently submitted manuscript; Celebes (65-72 Ma B.P.)
(Less and McCabe, 1986); and Sulu (41-47 Ma B.P.) (Lee and McCabe, 1986). The
anomalies identified in each of these basins become progressively younger toward the north.

The on-land geology of this region is complicated but stratigraphic and paleomagnetic
studies on pre-Oligocence rocks by numerous workers are consistent with the interpretation
that the older landmasses that presently dissect the basin were translated into their present
position before late Miocene. Stratigraphic studies from the Sula Microcontinent, Buru,
Ceram and Tunor show close correlation to the stratigraphy of north west Australia or New
Guinea. Paleomagnetic studies from Timor suggest that a portion of the island was a part
of Australia since early Mesozoic. Paleomagtettc and stratigraphic data from Borneo and
Sulawesi suggest that these landmasses share a common orign and that Sulawesi rifted
eastward of Borneo during the Tertiary. Paleomagnetic and stratigraphic data from the
Philippines suggest that the Philippine Arc is a composite of early Cretaceous to Recent arcs
and oceanic crustal fragments that were translated clockwise from the southeast. The clock-
wise rotation of the Philippines, coupled with paleo-inclination studies, suggests that this
arc shares a common middle Tertiary history with the West Philippine Sea. Stratigraphic
and paleomagnetic data from the North Palawan Continental Terrane are consistent with
the interpretation that this terrane rifted away from China during the middle Tertiary.

 

 

 

Geological Society of the Philippines

Unit 250, 2nd Floor, Cityland Pioneer, 128 Pioneer Street, Mandaluyong City, Philippines

Tel: +(63-2) 633-9025