Tethyan Trench Tethyan Trench The Tethyan Trench was an ancient oceanic trench that existed in the northern part of the Tethys Ocean during the middle Mesozoic to early Cenozoic eras. The Tethyan Trench formed when the Cimmerian Plate was subducting under eastern Laurasia, around 200 million years ago, in the Early Jurassic. The Tethyan Trench extended at its greatest during Late Cretaceous to Paleocene, from what is now Greece to the Western Pacific Ocean. Subduction at the Tethyan Trench probably caused the continents Africa and India to move towards Eurasia, which resulted in the opening of the Indian Ocean. When the Arabian
Sumatra Trench in the reducing of the sediment thickness. The thickness is minimum at South Sumatra (1–2 km) and maximum at north Sumatra. The thickest sediment at north Sumatra can compare with the Makran Trench, which has the thickest sediment on Earth (7.5 km). Sediment thickness along the Sumatra Trench varies significantly, which is the result of fracture zones and fossil ridges' influence on basement topography. The thickness is a function of oceanic basement topography in some extent and this feature is extremely distinctive in the part between Simeulue and Siberut Islands (Central Sumatra region 2°N to 3°S) along the trench. This