• Ilimanu Marble

    situated approximately 36km from Dili, the capital of Timor-Leste.


Geology and Tectonic Setting of Timor Island

Many theories have been proposed for the island’s tectonic evolution (Audley-Charles, 1968; Chamalaun & Grady, 1978; Barber, 1979; Hamilton, 1979; Harris, 1991; Charlton, 2000). Despite the conflict of ideas, some broad geological observations allow a generalised model of the tectonic development of this region since the Neogene.

Chamalaun et al., 1976; Hamilton, 1977 confirmed from gravity survey results that the Australian continental crust extends as far as the north coast of Timor. Overlying this gently deformed Australian basement are rocks derived from the distal Australian passive margin (para-autochthonous units), formed in response to the Middle-Late Jurassic breakup of eastern Gondwana and subsequent sea-floor spreading. Passive margin conditions prevailed until Neogene arc-continent collision, when rocks derived from the pre-collisional Banda forearc (allochthonous units) were incorporated into the collision complex. The rocks exposed in Timor include:

  • Early-Permian to Early-Pliocene variably deformed and metamorphosed deep water sediments of the Australian passive margin (Gondwana and Kolbano Sequences)
  • Late-Miocene-Early Pliocene Bobonaro Scaly Clay, an olistostrome thought to be emplaced as a gravity slide in response to the southward tilting of Timor during subduction (Johnston & Bowin, 1981).
  • Banda Allochthon: pre-Cretaceous metamorphic rocks overlain by sedimentary deposits and ophiolites of upper Jurassic to Lower Pliocene age, all of which are derived from the pre-collisional Banda fore-arc
  • Post-orogenic Upper-Miocene to Recent coral reefs, alluvial terraces and turbidites, unconformably overlying all other lithotectonic units.
(SOURCE: TIMOR LESTE NATURAL RESOURCES (Mineral, Geothermal & hydrocarbon) – Literature Review)

Geology of Ilimanu

Ilimanu area is located along the north coast of Timor-Leste.
Geologically, Ilimanu area is part of Aileu Formation (early permian – late early cretaceous) which is essentially a flysch which becomes more siliceous northwards until near the north coast of Timor-Leste where metaquartzites, micaschists, marbles, metabasics and amphibolites outcrop (Audley-Charles (1968), Berry and Grady,1980).

The litology of the Ilimanu area consists of metamorphic units from low grade to high grade, such as, slate, serpentinite, phylite, amphibolite, metasandstone and marble, and igneous rock; basalt, gabbro, peridotite, and sedimentary rock; crystalized limestone.