Geomorphological Evolution of the Andaman Sea Offshore Phang Nga Province (Thailand) during the Holocene: An Example for a Sediment Starving Shelf

Peter Feldens,Somkiat Khokiattiwong,Klaus Schwarzer,Daroonwan Sakuna-Schwartz

doi:10.3390/coasts2010001

Peter Feldens, Somkiat Khokiattiwong + Show 2 more

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https://doi.org/10.3390/coasts2010001

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Abstract

Understanding the development of shallow seas is essential, as they provide a major environmental and economic resource. An investigation of the Holocene development and the present conditions of the Andaman Sea shelf was carried out based on hydroacoustic surveys and sedimentological sampling. The results show that the relative sea level in the offshore Phang Nga province (Thailand) was at a present-day water depth of approximately 63 m at 13 cal ka BP. This agrees with the sea level development of the Sunda Shelf. Since that time, the Andaman Sea continental shelf developed as a sediment-starved environment, with less than 2 m thickness of sediment deposited during the Holocene on the crystalline basement over large areas between 60 m and 20 m water depth. Between 28 and 17 m water depth, a series of moribund asymmetrical sand ridges exist. These ridges were formed around 9.0 ka cal BP. They strike oblique to the coastline. On the seaward side of the sand ridges, small NW-SE directed submarine dunefields developed, shaped by monsoon-induced currents.

Highlights

Shelf seas—ranging from the coastline to the shelf break—cover ca. 8% of the marine environment, are highly productive areas of the oceans regarding biological activity and fishing resources and are exploited regarding mineral resources. They are often characterized by complex patterns of sediment distribution, geomorphological structures and sediment dynamics [1]
Continental shelves have experienced a series of sea level fluctuations and sedimentation processes throughout the Quaternary [4]
Sediment accumulation is controlled by the rate of relative sea-level rise, the rate and character of sediment input, the geomorphological gradient of the shelf and its geological composition, the hydrodynamic driving forces and the resulting rate of sediment transport

Summary

Introduction

Shelf seas—ranging from the coastline to the shelf break—cover ca. 8% of the marine environment, are highly productive areas of the oceans regarding biological activity and fishing resources and are exploited regarding mineral resources. 8% of the marine environment, are highly productive areas of the oceans regarding biological activity and fishing resources and are exploited regarding mineral resources. They are often characterized by complex patterns of sediment distribution, geomorphological structures and sediment dynamics [1]. Areas with sediment deficiency and areas of sediment accumulation point to different framework conditions of hydrodynamic forces, geological prerequisites and sedimentological built up. Comparisons of these different environments provide insights into the postglacial geological evolution of a particular shelf as well as into recent sediment dynamic processes [3].

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