Kinta Valley limestone: clues for a new play?

A number of isolated Paleozoic (Ordovician to Permian) limestone hills with prominent karstic features cover an area of about 200km2 within the 1,200 km2 area in the Kinta Valley in Peninsular Malaysia. These are remnants of extensive limestone beds, which are part of a very large Paleozoic carbonate complex that covered large parts of South-East Asia. The limestone beds are interbedded with sandstone, siltstone and carbonaceous shale over a thickness of up to 3000m.

The Paleozoic Kinta Valley limestone overlies younger Triassic granite bodies which had affected the texture and composition of the limestone and shale through contact metamorphism. In spite of this, sedimentary structures, such as thin laminations, slumps and meter-thick beds of brecciated shallow-marine fragments are still clearly visible in some places. These indicate that the Paleozoic limestone of the Kinta Valley was deposited on a slope. The dip and strike directions of the slumps indicate the presence of a north-south oriented shallow marine platform margin to the east of the Kinta Valley, prograding towards Central Peninsular Malaysia. Outcrops in eastern Peninsular Malaysia confirm the presence of a shallow marine platform, with potential reservoir horizons, that probably extended eastwards far into the South China Sea.

Paleogeographic reconstruction of the Paleozoic deposits in Peninsular Malaysia suggests that a potential new carbonate play may lie unexplored east of peninsular Malaysia. In the early 1970’s, pre-Tertiary carbonate were penetrated offshore, at three localities east of peninsular Malaysia. These wells were found within 8 to 492m of limestone below the Base Tertiary unconformity but did not encounter hydrocarbons. However, Paleozoic structures are possibly offset from the Tertiary structures at these locations and recent seismic may indeed reveal the presence of untested pre-Tertiary structures.