Depositional Sequence Model of the Backarc Basins in the Northwest Pacific Rim, Japan
Koichi Hoyanagi, Daisuke Watanabe, and Hiroyuki Arato
The Japan Sea is considered to have been formed by backarc spreading until the Middle Miocene time. A number of backarc sedimentary basins in the Japan Sea were developed along the arcs during its Miocene evolution. The second-order tectono sequence has been recognized within the basin fill deposits of the backarc basins. This second-order sequence consists both of transgressive systems tract formed during 18 to 14Ma and high stand systems tract formed during 14Ma to recent time. At the present time the compression of arcs turns the systems tract from high stand to low stand.
This second-order sequence is superimposed by the third- order which is, in turn, superimposed by the fourth-order. The third-order depositional sequences formed at the second-order high stand are characterized by aggradation of the estuary or barrier system of the transgressive systems tract, progradational fan delta or delta system of the high stand systems tract, and channel-levee turbidite of the low stand systems tract. No back stepping sedimentary pattern developed in these sequences. Three different types of fourth-order depositional sequence were formed at the position of third-order relative sea-level cycle. These third- and fourth-order depositional sequences might have been built up by the rapid sedimentation of the backarc basins with global eustasy.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California