Preface

This book presents the mechanisms of sedimentary basin formation on active plate margins. The crust of continental margins experiences tectonic stress as a result of the subduction of oceanic plates. A part of this strain is released elastically as earthquakes and the remainder causes permanent deformation. The formation process of crustal depressions, that is sedi‐ mentary basins, has been one of the most significant themes of Earth science because the thick deposits burying sedimentary basins are abundant in natural resources such as hydro‐ carbons; the densely populated overlying surface is also investigated from the viewpoint of natural disaster prevention. Practical aspects aside, sedimentary layers within a basin are an excellent record of long-term environmental change, and the mass balance of arc-trench sys‐ tems is understood by the integrated research of tectonic processes around active margins including the formation of sedimentary basins.

The focus of this book is set on the eastern Eurasian margin, where most of the various types of tectonic episodes on active margins can be found and have been discussed through indepth studies. Since the amalgamation of the major continental blocks by the middle of the Mesozoic era, eastern Eurasia has been under the influence of the subduction of oceanic plates. For example, the rapid northerly migration of the Izanagi Plate during the early Cre‐ taceous gave rise to conspicuous tectonic events along the continental margin. It has been clearly established that the obliquity of subduction is a key factor in the mode of crustal de‐ formation. Namely, normal subduction results in a dominance of compressive stress on ac‐ tive margins, vigorous arc volcanism and provokes induced convection in the wedge of the upper mantle, leading to the eventual opening of a backarc basin. Oblique subduction acti‐ vates bisecting faults within arcs and causes a large amount of lateral transportation of crus‐ tal blocks. Prevailing shear stress affects the architecture of basins in forearc regions and controls the formation of barriers to sediment influx.

The chronicle of the sedimentary basin development around the Japanese Archipelago in the Eurasian active margin since the late Mesozoic is summarized as follows:

1) Prolonged transcurrent faulting from the late Cretaceous to Paleogene resulted in the for‐ mation of many pull-apart basins on the margin. The propagation of fault terminations caused a migration of depocenters; wrench deformation was related to compartmentaliza‐ tion of the basins. Trench slope breaks developed during some contraction episodes on the forearc region.

2) Succeeding to the Philippine Sea Plate spreading, the Neogene was heralded by the emer‐ gence of rift zones and the backarc opening of the Japan Sea. It was also characterized by the remarkable rise of a compressive stress regime as a result of multiple arc-arc collision events such as the Kurilenortheast Japan collision around Hokkaido and the southwest JapanIzuBoninnortheast Japan collision within central Japan. The collision events enhanced the for‐ mation of foreland and intra-arc basins.

arc basins, which are generally lacking in age-diagnostic fossils. Elaborate sedimentological and chronological analyses succeed in the visualization of basin formation and deformation process associated with multiple inversion events as a result of temporal change in tectonic stresses (Chapter 7). Itoh, Y. and others present the trans-arc variation of recent basin mor‐ phology in the southwest Japan arc, and discuss the synchronism of the forearc and intra-arc tectonic episodes. They examine the tectonic context of major geologic boundaries (faults), and redefine tectonic domains in the island arc. On such a basis, the morphological diversity of intra-arc basins is argued in relation to the differential motion of crustal blocks (Chapter 8). Takemura, K. and others review the subsidence and sedimentation processes of Lake Bi‐ wa and surrounding buried basins, which collectively constitute the largest intra-arc depres‐ sion within the Japanese Archipelago, the depocenter of which has migrated reflecting neotectonic episodes since the Pliocene. The present paper is a milestone of tectono-sedi‐ mentological studies spanning more than four decades, and chronicles the development and

Section 4 attempts to show a geophysical approach to basin analyses. Itoh, Y. and others present rock magnetic properties of sedimentary rocks in central Hokkaido, and argue their contribution to tectono-sedimentology. They emphasize the usability of anisotropy of mag‐ netic susceptibility as a proxy of microscopic fabric and the sedimentary system within a basin on the basis of analytical data of foreland basin sediments (Chapter 10). Itoh, Y. and others estimate the volume of buried basins around both ends of the bisecting transcurrent fault of southwest Japan based on gravity anomalies. They also present sedimentological da‐ ta of recent clastics adjacent to the basin and argue its tectonic context. Heterogeneity of the basin-filling units is assessed utilizing gravity and geomagnetic anomaly modeling. It is a case study of a deep basin interior where direct subsurface information derived from bore‐ hole geology and seismic interpretation is not ready to be widely applied (Chapter 11). Fi‐ nally, a numerical synthesis of basin formation in a strike-slip fault zone is presented by Kusumoto, S. and others (Chapter 12). They successfully restore the formation process of the Cenozoic basins in Hokkaido based on dislocation modeling of crustal strain assuming dex‐ tral motions upon faults, tips of which have propagated throughout the period of fault acti‐ vation. It is an ambitious causal analysis of basin formation on an active margin, and can be

This book provides the present accomplishments of basin researches on active margins by Earth scientists and, given that studies by the prominent authors are still under way, be‐

Graduate School of Science, Osaka Prefecture University

**Yasuto Itoh**

Japan

Preface XI

history of tectonic depression theory (Chapter 9).

verified by geologic descriptions presented in this book.

comes a precursor of comprehensive understanding in the future.

3) The Late Neogene and Quaternary on the Eurasian margin were characterized by the wax and wane of crustal deformation, reflecting a shift in convergence of the Pacific and the Phil‐ ippine Sea Plates. Compressive episodes resulted in vigorous mountain building and the rapid burial of tectonically regulated basins. Differential crustal motion during shear defor‐ mation phases has diversified the configuration of basins.

Section 1 of this book focuses on the genesis of sedimentary basins in wrench deformation zones in forearc and intra-arc regions. Takano, O. and others show the architecture of the Paleogene forearc basins in Hokkaido and northeast Japan and discuss the tectonics of basin compartmentalization in comparison with geologic analogues. They also present a deposi‐ tional system of younger forearc basins on the Philippine Sea Plate subduction zone. Their elaborate work is an excellent review of forearc basin studies and, at the same time, presents a tectonic model related to the development of a trench slope break (Chapter 1). Noda, A. presents a generalized basin formation scheme linked to strike-slip fault movements. He has reviewed representative strike-slip basins at convergent margins around the globe from the viewpoint of basin formation and filling processes. To establish a simple model of the evolu‐ tion of strike-slip basins, which present a wide range of formation processes and sedimenta‐ ry facies, controlling factors of basin development are presented referring to both modern and ancient examples. Kinematic models are highly informative and serve as a firm basis of quantitative basin study (Chapter 2).

Section 2 includes papers investigating basin formation in peripheral regions of Eurasia. First, Egawa, K. presents the Mesozoic evolution of the continental arc basins on the Korean Peninsula in relation to orogenic movement. He interprets an evolutionary mechanism of the Jurassic synorogenic basin in West Korea based on a tectonic model of the East Asiawide flat slab subduction (Chapter 3). Sakai, T. and others discuss sedimentary environ‐ ments and the evolution process of rift basins on the Japan Sea coast comparing with continental rift systems on larger scales. It is a unique attempt to find a generalized tectonosedimentological model of incipient backarc basins (Chapter 4). Next, Takeuchi, A. presents a tectonic synthesis of the central Japan collision front, Fossa Magna, and proposes a com‐ prehensive model of the upper mantle and crustal structure of an active margin from the viewpoint of basement-involved tectonics. Present-day central Japan is one of the most com‐ plicated areas of deformation and basin formation, where four plates (Amur, Okhotsk, Phil‐ ippine Sea and Pacific) meet and accommodate relative motions. His paper provides us with a perspective of the geology of the mobile belt (Chapter 5).

Section 3 provides a multidisciplinary description of intra-arc and foreland basins under the influence of the fluctuation of stress regimes. Kawakami, G. shows a detailed morphology of foreland basins in central Hokkaido, linked to the collision of the Kurile and northeast Japan arcs, which became obvious after the Miocene backarc opening of the Japan Sea. It is a typi‐ cal foreland setting on an active plate margin, and the tectono-sedimentological research is crucial for the understanding of mass balance around an arc-trench system. His discussion is based on voluminous geologic information, and paves a new path to a comprehensive cate‐ gorization of foreland basins (Chapter 6). Nakajima, T. deals with the development of intraarc basins within northeast Japan that are linked to an intermittent uplift of the previous half-grabens, and identifies regional tectonic episodes. It is a significant case study of intra-

arc basins, which are generally lacking in age-diagnostic fossils. Elaborate sedimentological and chronological analyses succeed in the visualization of basin formation and deformation process associated with multiple inversion events as a result of temporal change in tectonic stresses (Chapter 7). Itoh, Y. and others present the trans-arc variation of recent basin mor‐ phology in the southwest Japan arc, and discuss the synchronism of the forearc and intra-arc tectonic episodes. They examine the tectonic context of major geologic boundaries (faults), and redefine tectonic domains in the island arc. On such a basis, the morphological diversity of intra-arc basins is argued in relation to the differential motion of crustal blocks (Chapter 8). Takemura, K. and others review the subsidence and sedimentation processes of Lake Bi‐ wa and surrounding buried basins, which collectively constitute the largest intra-arc depres‐ sion within the Japanese Archipelago, the depocenter of which has migrated reflecting neotectonic episodes since the Pliocene. The present paper is a milestone of tectono-sedi‐ mentological studies spanning more than four decades, and chronicles the development and history of tectonic depression theory (Chapter 9).

Boninnortheast Japan collision within central Japan. The collision events enhanced the for‐

3) The Late Neogene and Quaternary on the Eurasian margin were characterized by the wax and wane of crustal deformation, reflecting a shift in convergence of the Pacific and the Phil‐ ippine Sea Plates. Compressive episodes resulted in vigorous mountain building and the rapid burial of tectonically regulated basins. Differential crustal motion during shear defor‐

Section 1 of this book focuses on the genesis of sedimentary basins in wrench deformation zones in forearc and intra-arc regions. Takano, O. and others show the architecture of the Paleogene forearc basins in Hokkaido and northeast Japan and discuss the tectonics of basin compartmentalization in comparison with geologic analogues. They also present a deposi‐ tional system of younger forearc basins on the Philippine Sea Plate subduction zone. Their elaborate work is an excellent review of forearc basin studies and, at the same time, presents a tectonic model related to the development of a trench slope break (Chapter 1). Noda, A. presents a generalized basin formation scheme linked to strike-slip fault movements. He has reviewed representative strike-slip basins at convergent margins around the globe from the viewpoint of basin formation and filling processes. To establish a simple model of the evolu‐ tion of strike-slip basins, which present a wide range of formation processes and sedimenta‐ ry facies, controlling factors of basin development are presented referring to both modern and ancient examples. Kinematic models are highly informative and serve as a firm basis of

Section 2 includes papers investigating basin formation in peripheral regions of Eurasia. First, Egawa, K. presents the Mesozoic evolution of the continental arc basins on the Korean Peninsula in relation to orogenic movement. He interprets an evolutionary mechanism of the Jurassic synorogenic basin in West Korea based on a tectonic model of the East Asiawide flat slab subduction (Chapter 3). Sakai, T. and others discuss sedimentary environ‐ ments and the evolution process of rift basins on the Japan Sea coast comparing with continental rift systems on larger scales. It is a unique attempt to find a generalized tectonosedimentological model of incipient backarc basins (Chapter 4). Next, Takeuchi, A. presents a tectonic synthesis of the central Japan collision front, Fossa Magna, and proposes a com‐ prehensive model of the upper mantle and crustal structure of an active margin from the viewpoint of basement-involved tectonics. Present-day central Japan is one of the most com‐ plicated areas of deformation and basin formation, where four plates (Amur, Okhotsk, Phil‐ ippine Sea and Pacific) meet and accommodate relative motions. His paper provides us with

Section 3 provides a multidisciplinary description of intra-arc and foreland basins under the influence of the fluctuation of stress regimes. Kawakami, G. shows a detailed morphology of foreland basins in central Hokkaido, linked to the collision of the Kurile and northeast Japan arcs, which became obvious after the Miocene backarc opening of the Japan Sea. It is a typi‐ cal foreland setting on an active plate margin, and the tectono-sedimentological research is crucial for the understanding of mass balance around an arc-trench system. His discussion is based on voluminous geologic information, and paves a new path to a comprehensive cate‐ gorization of foreland basins (Chapter 6). Nakajima, T. deals with the development of intraarc basins within northeast Japan that are linked to an intermittent uplift of the previous half-grabens, and identifies regional tectonic episodes. It is a significant case study of intra-

mation of foreland and intra-arc basins.

X Preface

quantitative basin study (Chapter 2).

mation phases has diversified the configuration of basins.

a perspective of the geology of the mobile belt (Chapter 5).

Section 4 attempts to show a geophysical approach to basin analyses. Itoh, Y. and others present rock magnetic properties of sedimentary rocks in central Hokkaido, and argue their contribution to tectono-sedimentology. They emphasize the usability of anisotropy of mag‐ netic susceptibility as a proxy of microscopic fabric and the sedimentary system within a basin on the basis of analytical data of foreland basin sediments (Chapter 10). Itoh, Y. and others estimate the volume of buried basins around both ends of the bisecting transcurrent fault of southwest Japan based on gravity anomalies. They also present sedimentological da‐ ta of recent clastics adjacent to the basin and argue its tectonic context. Heterogeneity of the basin-filling units is assessed utilizing gravity and geomagnetic anomaly modeling. It is a case study of a deep basin interior where direct subsurface information derived from bore‐ hole geology and seismic interpretation is not ready to be widely applied (Chapter 11). Fi‐ nally, a numerical synthesis of basin formation in a strike-slip fault zone is presented by Kusumoto, S. and others (Chapter 12). They successfully restore the formation process of the Cenozoic basins in Hokkaido based on dislocation modeling of crustal strain assuming dex‐ tral motions upon faults, tips of which have propagated throughout the period of fault acti‐ vation. It is an ambitious causal analysis of basin formation on an active margin, and can be verified by geologic descriptions presented in this book.

This book provides the present accomplishments of basin researches on active margins by Earth scientists and, given that studies by the prominent authors are still under way, be‐ comes a precursor of comprehensive understanding in the future.

> **Yasuto Itoh** Graduate School of Science, Osaka Prefecture University Japan

**Section 1**

**Genetic Analyses of Sedimentary Basins in**

**Wrench Deformation Zones**

**Genetic Analyses of Sedimentary Basins in Wrench Deformation Zones**

**Chapter 1**

**Variation in Forearc Basin Configuration and Basin-**

**filling Depositional Systems as a Function of Trench**

**Slope Break Development and Strike-Slip Movement:**

**Examples from the Cenozoic Ishikari–Sanriku-Oki and**

This chapter aims to elucidate variation of forearc basins in terms of basin configurations and basin-filling depositional systems with some examinations of their controlling factors, using actual examples from the Cenozoic forearc basins along the Northeast and Southwest Japan Arcs. Forearc basin is a sedimentary basin formed in the arc-trench gap between a volcanic arc and plate subduction zone (Figure 1) [1]. Although there are some notable past forearc basin studies (e.g., [1, 2]), the detailed characteristics of forearc basins have not been fully under‐ stood, since they show wide-range variation in styles, possibly reflecting various plate tectonic conditions at the plate subduction zone. As well-documented textbooks, Dickinson and Seely [2] and Dickinson [1] compiled and summarized the general outline of the forearc basin architecture and basin-filling sediments with explanations about some actual ancient and modern example forearc basins. The major contributions of these comprehensive textbooks include not only the presentation of various forearc basin styles, but also the explanation of related elements characterizing the forearc basin styles, such as dimension, subsidence, basin filling patterns, accretionary sill conditions and trench slope break development. Among these forearc basin elements, Dickinson [1] especially picked up two major elements: basin filling conditions and sectional basin configuration controlled by the relative height of trench slope

> © 2013 Takano et al.; 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 Takano et al.; 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.

break, to determine the morphological classification of forearc basins.

**Tokai-Oki–Kumano-Nada Forearc Basins, Japan**

Osamu Takano, Yasuto Itoh and

Additional information is available at the end of the chapter

Shigekazu Kusumoto

http://dx.doi.org/10.5772/56751

**1. Introduction**

**Variation in Forearc Basin Configuration and Basinfilling Depositional Systems as a Function of Trench Slope Break Development and Strike-Slip Movement: Examples from the Cenozoic Ishikari–Sanriku-Oki and Tokai-Oki–Kumano-Nada Forearc Basins, Japan**

Osamu Takano, Yasuto Itoh and Shigekazu Kusumoto

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/56751

**1. Introduction**

This chapter aims to elucidate variation of forearc basins in terms of basin configurations and basin-filling depositional systems with some examinations of their controlling factors, using actual examples from the Cenozoic forearc basins along the Northeast and Southwest Japan Arcs. Forearc basin is a sedimentary basin formed in the arc-trench gap between a volcanic arc and plate subduction zone (Figure 1) [1]. Although there are some notable past forearc basin studies (e.g., [1, 2]), the detailed characteristics of forearc basins have not been fully under‐ stood, since they show wide-range variation in styles, possibly reflecting various plate tectonic conditions at the plate subduction zone. As well-documented textbooks, Dickinson and Seely [2] and Dickinson [1] compiled and summarized the general outline of the forearc basin architecture and basin-filling sediments with explanations about some actual ancient and modern example forearc basins. The major contributions of these comprehensive textbooks include not only the presentation of various forearc basin styles, but also the explanation of related elements characterizing the forearc basin styles, such as dimension, subsidence, basin filling patterns, accretionary sill conditions and trench slope break development. Among these forearc basin elements, Dickinson [1] especially picked up two major elements: basin filling conditions and sectional basin configuration controlled by the relative height of trench slope break, to determine the morphological classification of forearc basins.

© 2013 Takano et al.; 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 Takano et al.; 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.

This chapter attempts to examine these two major factors: basin filling condition and basin configuration, by diagnosing two contrasting actual forearc basin packages around Japan: the Eocene Ishikari–Sanriku-oki forearc basins along the NE Japan Arc and the Pleistocene Tokaioki–Kumano-nada forearc basins along the SW Japan Arc (Figure 2). To delineate the basin filling condition, we examine sedimentological characteristics including depositional systems, sequence stratigraphic contexts and related controlling factors. Regional seismic survey sections are used to manifest the basin configuration and to discuss controlling factors on forearc sedimentation for the two example forearc basins. In addition to these major factors, we discuss the role of strike-slip tectonics on the forearc basins, as it is reported in a former literature that strike-slip movement related to oblique plate subduction may affect the forearc basin tectonics and sedimentation.

**Figure 1.** Schematic cross section of a forearc zone including a forearc basin, showing the basic terms used in this chapter. Modified after [1].
