**1. Introduction**

A foreland basin can be defined as a linear depression formed from the flexure of foreland lithosphere under the load of an orogenic wedge. Various factors control the basin geometry and the stratigraphic architecture of the basin fill [1].

During the Miocene age, a series of foreland basins were formed in Hokkaido, the northern island of Japan, due to an arc-arc collision event [2–4]. The basin area has a total length of 400 km, and it is characterized by several rows of deep depressions stretched in a north-south direction and separated by topographic highs (Figure 1). The degree of total crustal shortening and exhumation by the collision event is larger in the southern region of the collision zone [5], and thus, the basin geometry and the stratigraphic/sedimentologic architecture of the basin fills vary among the depressions. Namely, the depression in the southern region has suffered progressive deformation due to thrust propagation, and the depocenter has migrated forelandward, a feature noted in many foreland basins [1]. In contrast, the depression in the northern region shows restrictive deformation and foreland-ward migration of depocenter. Thus, the initial geometry and stratigraphic architecture of the basin fill are well preserved even in the proximal margin of the basin. On the other hand, unlike the northern and southern regions, the depression located near the center of the foreland basin area has been affected by the existence of a projection on the foreland lithosphere. As a result, the depression shows very narrow basin geometry and restrictive foreland-ward migration of the depocenter.

Such spatial variations are caused mainly by regional differences in the degree of tectonic disturbance, as there is no radical difference in the geodynamic states of the underlying lithosphere throughout the foreland area. Considering the above factors, this study focuses on how the difference in the degree of tectonic deformation affects the foreland basin geometry, basin-filling process, and the resultant stratigraphy in a geological record. This paper firstly

© 2013 Kawakami; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Kawakami; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

reviews the stratigraphic architecture and depositional system in each depression, and then discusses the relationship between basin evolution and tectonics.
