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Abstract:
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Eastern Sea of Vietnam is the world's largest semi-open sea and is bounded
by archipelagos, islands, mainland and connected partially with Pacific and Indian Ocean. Its
total water surface area is about 2,974,600km2. Vietnamese and foreign geoscientists have
researched, got samples and mapped the geological map of Eastern Sea since 1960s but
no guidance or right method was carried out to map, especially in presenting geological
units on geological map. So that, in this article, the Geological Quaternary map of Eastern
Sea is created by using group of methods, methodology and literatures for sediment,
geophysics,... The methodology is systematization of research results of Vietnamese and
foreign scientists on Quaternary geology in mainland and continental shelf. One of those
results is the classification of sedimentary cycles in relation to sea level change in
Quaternary. In seabed of Eastern Sea, there are 25 geological units of 7 sedimentary
cycles, which includes 4 lithofacies Pliocene - Quaternary, 14 lithofacies in Pleistocene and
6 lithofacies in Holocene, coral reefs and volcanic rocks. Especially, there are 8 ancient
shoreline zones that acted as geological boundary from 3500m to 25m water depth in the
sea bottom. |