EASTERN INDONESIA EVOLUTION SINCE THE LATE EOCENE




VILLENEUVE 1) M., J.P. REHAULT 2), J.J. CORNEE 1), W. GUNAWAN 1), J. GIRARDEAU 3), A.H. HARSOLURNAKSO 4), C. HONTHAAS 2), J.A. MALOD 2), and C. MONNIER 3)



Since the late Eocene time, the eastern part of Indonesia which is located at the triple junction of the Asiatic, Australian and Pacific plates, has undergone several geodynamic changes within a large convergent tectonic regime. During the Oligocene time, the Banda block which is a large continental fragment drifted away from the Gondwana by the Jurassic time, reached the Asiatic margin in the Sulawesi Island. A part of Asiatic marginal basins (Celebes sea) were directely obducted onto the Northern part of this Banda block. By the early Miocene, due to local collapses, several graben like basins developped in the Sulawesi Island and Banda block. By the middle Miocene, the Tukang Besi block moving from the East, collided the southern part of the Banda block. By the late Miocene and the early Pliocene, the new block including the formers Banda and Tukang Besi blocks was dismembered and large basins have occured (for example Banda sea North and South). By the mid Pliocene, these basins began to close meanwhile the Bangai Sula block, coming from the East, reached the Eastern part of Sulawesi. To the Southern part, the Australia continent collided the Banda/Tukang Besi block mainly in Timor Island. The late Pliocene is a period of molassic deposition mainly around the mid Pliocen collisions zones. During the Holocene, the Northwestward motion of the Australian continent is the main factor of tectonic changes in the eastern part of Sulawesi.
This scenario shows rapid changes from extensional to compressional regimes. GPS measurement will allow us to understand and to quantify the present day tectonic changes in this far east country.


1) Sedimentologie, Univ. de Provence
case 67, 3 place V. Hugo
Marseille, cedex03, FRANCE


2) Geophysique marine, UBO
BP 239
29285 Brest cedex, FRANCE


3) Petrologie, Univ. de Nantes
2 rue de la Houssinieres
44072 Nantes, FRANCE


4) Dept. of geology, ITB
Jalan Ganesha 10
40122 Bandung, INDONESIA


5) Dept. Sciences de la Terre, Univ. de Nancy
BP 239
54506 Vandoeuvre les Nancy cedex, FRANCE



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