**5. Summary**

106]. The bounding fault is a right-lateral transpressional fault with accompanying topograph‐ ic highs of *en échelon* anticlines on the western margin and compressional ridges of Tuba Ridge on the southern margin (Figure 13). The transpressional uplift generating the outer-arc high by a thickening crustal block may be resulting in subsidence opposite to the high. This type of sedimentation is similar to that of foreland basins, where depressions are caused by the overburden pressure of the thrusted crust. Rifting and basin formation started in Sumatra

44 Mechanism of Sedimentary Basin Formation - Multidisciplinary Approach on Active Plate Margins

The deposits in the basin are thickest along the boundary fault between the basin and the outerarc high, and gradually thin with increasing distance from the faults (Figure 14B and C). Regarding the recent deposits, represented by seismic units 3 and 4 (Figure 14), unit 3 sedi‐ ments in the southern part are thicker than those in the northern part, but unit 4 sediments are thicker in the northern part. Therefore, the main depocenter is considered to have migrated from the south (unit 3) to the north (unit 4). This interpretation is supported by seismic profiles of [106], who noted that the southern part of the Aceh Basin is raised above the northern part.

Most of the sediments are considered to have been supplied from Sumatra Island through small submarine channels (Figure 13). However, little is known about axial sediment redis‐

**Figure 13.** Detailed bathymetry around the Aceh Basin. Red and yellow lines are strike-slip faults and axes of anticlines [105], respectively. Thick solid lines in the Aceh Basin mark cross-sectional profiles shown in Figure 14. Abbreviations are the same as for Figure 12. Bathymetry is based on using SRTM and GEBCO with the data recently collected by

during the Paleogene [107].

*4.4.2. Basin-filling processes*

tribution within the basin.

[108–110].

This preliminary review has introduced some of the representative strike-slip basins at convergent margins from the viewpoints of basin formation and filling processes. Because strike-slip basins present a wide range of formational processes and sedimentary facies, it is difficult to establish a simple model of their evolution. To understand both modern and ancient strike-slip basins, the following factors need to be considered:


**•** Climate: sediment yield, modes of sediment transport, chemistry of deposits

Compressional uplift along master faults is probably needed for the dominance of axial sediment supply into the basin, which has the potential to produce and distribute huge volumes of detritus (Figure 15). Restraining bends as paired bends [12] such as in the Dead Sea Basin setting, and collision related to continental indentation such as in the Yinggehai Basin setting, are possible cases where axial sediment supply is enhanced. Conversely, a marginal high along the master fault is required for the formation of transpressional basins such as the Aceh Basin; therefore, marginal sediment supply may tend to dominate in such basins.

migration, such as the Dead Sea Basin and the Izumi Group, other formational mechanisms should be considered instead of the pull-apart basin model. Step-wise propagation or sequen‐ tial progradation of the master fault could produce elongated stepover basins. A high *l*/*w* ratio could also potentially be produced by a transpressional basin along a trench-linked strike-slip fault. However, there is a need to establish physical models for basin formation in such settings.

Strike-Slip Basin – Its Configuration and Sedimentary Facies

http://dx.doi.org/10.5772/56593

47

Kai Berglar and his working groups kindly provided the bathymetric data of the Sumatra region. Financial support for this research was provided by the National Institute of Advanced Industrial Science and Technology (AIST). Constructive comments from Yasuto Itoh were

Geological Survey of Japan, National Institute of Advanced Industrial Science and Technolo‐

[1] Nilsen TH, Mclaughlin RJ. Comparison of tectonic framework and depositional pat‐ terns of the Hornelen strike-slip basin of Norway and the Ridge and Little Sulphur Creek strike-slip basins of California. In: Biddle KT, Christie-Blick N (eds.) Strike-Slip Deformation, Basin Formation, and Sedimentation. Special Publication, no. 37. Tulsa,

[2] Aydin A, Nur A. Evolution of pull-apart basins and their scale independence. Tec‐

[3] Noda A, Toshimitsu S. Backward stacking of submarine channel-fan successions con‐ trolled by strike-slip faulting: The Izumi Group (Cretaceous), southwest Japan. Litho‐

[4] Nilsen TH, Sylvester AG. Strike-slip basins. In: Busby CJ, Ingersoll RV (eds.) Tecton‐

ics of Sedimentary Basins. Oxford: Blackwell Science; 1995. p. 425–457.

**Acknowledgements**

**Author details**

gy, Tsukuba, Ibaraki, Japan

Atsushi Noda\*

**References**

insightful for improving the manuscript.

Address all correspondence to: a.noda@aist.go.jp

Oklahoma: SEPM; 1985. p. 79–103.

sphere 2009;1(1) 41–59. doi:10.1130/L19.1.

tonics 1982;1(1) 91–105. doi:10.1029/TC001i001p00091.

The continuous migration of depocenters requires that the progressive displacement of the master faults creates new accommodation space (Figure 15). In standard models of pull-apart basins, which are bounded by steep master faults and listric transverse faults, increasing the offset leads to a widening of the fault zone, resulting in wider pull-apart basins with a *l*/*w* ratio of about 3 for each basin [2, 42]. Therefore, for large *l*/*w* basins with continuous depocenter

**Figure 15.** Conceptual models for depocenter migration and axial sediment supply in fault-bend basins. (A) Progres‐ sive right-lateral migration of paired bends on the foot-wall generates compressional uplift and extensional depres‐ sion on the hanging-wall. Sediments are always supplied from the same direction along the long-axis of the basin. (B) Depocenter fixes along the releasing bend result from the right-lateral migration of sediments deposited on the footwall. A transpressional component would be required to generate the sediment source, and *en échelon* folds may form along the master faults. Both models generate deposits with axial sediments whose thicknesses are greater than the burial depths.

migration, such as the Dead Sea Basin and the Izumi Group, other formational mechanisms should be considered instead of the pull-apart basin model. Step-wise propagation or sequen‐ tial progradation of the master fault could produce elongated stepover basins. A high *l*/*w* ratio could also potentially be produced by a transpressional basin along a trench-linked strike-slip fault. However, there is a need to establish physical models for basin formation in such settings.
