The South China Sea is a marginal sea that is part of the Pacific Ocean, encompassing an area from the Singapore and Malacca Straits to the Strait of Taiwan of around 3,500,000 square kilometres (1,400,000 sq mi). The area's importance largely results from one-third of the world's shipping transiting through its waters, and that it is believed to hold huge oil and gas reserves beneath its seabed.
It is located
- south of mainland China and the island of Taiwan,
- west of the Philippines,
- north west of Sabah (Malaysia), Sarawak (Malaysia) and Brunei,
- north of Indonesia,
- north east of the Malay peninsula (Malaysia) and Singapore, and
- east of Vietnam.
The minute South China Sea Islands, collectively an archipelago, number in the hundreds. The sea and its mostly uninhabited islands are subject to competing claims of sovereignty by several countries. These claims are also reflected in the variety of names used for the islands and the sea.
States and territories with borders on the sea (clockwise from north) include: the People's Republic of China (including Macau and Hong Kong), the Republic of China (Taiwan), the Philippines, Malaysia, Brunei, Indonesia, Singapore, and Vietnam.
Major rivers that flow into the South China Sea include the Pearl, Min, Jiulong, Red, Mekong, Rajang, Pahang, Pampanga, and Pasig Rivers.
The sea lies above a drowned continental shelf; during recent ice ages global sea level was hundreds of metres lower, and Borneo was part of the Asian mainland. The South China Sea opened after around 45 million years ago when the Dangerous Grounds (Reed Tablemount) were rifted away from southern China. Extension culminated in seafloor spreading around 30 million years ago, a process that propagated to the SW resulting in the V-shaped basin we see today. Extension ceased around 17 million years ago.
Arguments have continued about the role of tectonic extrusion in forming the basin. Paul Tapponnier and colleagues have argued that as India collides with Asia it pushes Indochina to the SE. The relative shear between Indochina and China caused the South China Sea to open. This view is disputed by geologists who do not consider Indochina to have moved far relative to mainland Asia.
Recent marine geophysical studies by Peter Clift has shown that the Red River Fault was active and causing basin formation at least by 37 million years ago in the NW South China Sea, consistent with extrusion playing a part in the formation of the sea. Since opening the South China Sea has been the repository of large sediment volumes delivered by the Mekong River, Red River and Pearl River. Several of these deltas are rich in oil and gas deposits.
Islands and seamounts :
The South China Sea contains over 250 small islands, atolls, cays, shoals, reefs, and sandbars, most of which have no indigenous people, many of which are naturally under water at high tide, and some of which are permanently submerged. The features are grouped into three archipelagos (listed by area size), Macclesfield Bank and Scarborough Shoal:
- The Spratly Islands
- The Paracel Islands
- The Pratas Islands
- The Macclesfield Bank
- The Scarborough Shoal
The Spratly Islands spread over an 810 by 900 km area covering some 175 identified insular features, the largest being Taiping Island (Itu Aba) at just over 1.3 km long and with its highest elevation at 3.8 metres.