**Acknowledgements**

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

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

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.

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.

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 insightful for improving the manuscript.
