gas hydrate - CCOP

The Korea Plateau includes a northern component (North Korea Plateau) and a southern
component (South Korea Plateau), bordered by the Sokcho Trough connected to the
southwestern part of the Japan Basin (Figure 1). The South Korea Plateau comprises rifted
continental crust in its western part and fragmented continental crust in its eastern part (Figure
1; Tamaki, 1988; Jolivet et al., 1991). To the north of Ulleung Island, a trough deepens
northward along the North Ulleung Escarpment and extends to the Japan Basin (Figure 1).
The South Korea Plateau can be divided further into western and eastern segments, separated
by the North Ulleung Escarpment (or Trough) (Figure 1; Chough et al., 2000).
SUMMARY OF PREVIOUS RESEARCH
The mass flow processes in the Ulleung Basin and Korea Plateau were originally reported by
Chough (1982, 1983, 1984). Following multi-channel seismic reflection surveys and drilling
of the Dolgorae exploratory well by the Korea Petroleum Development Corporation
(PEDCO) in the late 1980’s, many further geological and geophysical studies of the Ulleung
Basin were carried out (Chough and Lee, 1992; Yoon and Chough, 1995; Chough et al., 1997;
Lee and Suk, 1998; Lee et al., 2001; Lee and Kim, 2002). Chough and Barg (1987) outlined a
suggested tectonic history of the margin of the Ulleung Basin and Chough and Lee (1987)
first analysed the slope stability of the western margin of the Ulleung Basin.
In the 1990’s, a few seismic stratigraphic schemes for the Ulleung Basin were suggested
(Chough and Lee, 1992; Yoon, 1994; Yoon and Chough, 1995; Chough et al., 1997; Lee and
Suk, 1998). These stratigraphic analyses commonly recognized an overall distribution of
relatively thick, chaotic and transparent seismic facies units, reflecting mass flow deposits.
According to Chough and Lee (1992), large slide or slump deposits were recognized mainly
in the southeastern part of the Ulleung Basin within the late Miocene and early Pliocene
sequence (Figure 2). Lee and Suk (1998) further divided the upper Pliocene and Quaternary
sequence into five subunits. The lower two (upper Pliocene) were mass flow deposits (Figure
3), whereas the upper three (Quaternary) were formed mainly by hemipelagic settling or
turbidity currents.
Figure 2. Multichannel airgun profile accross the Ulleung Basin. Classification of sequence
units is based on Chough and Lee (1992). Profile courtesy of the Korea National Oil
Corporation.
New Energy Resources in the CCOP Region - Gas Hydrates and Coalbed Methane 107