Chapter 1 Tectonics of sedimentary basins, with revised nomenclature

Actualistic plate-tectonic models are the best framework within which to understand the tectonics of sedimentary basins. Sedimentary basins develop in divergent, intraplate,convergent,transform,hybrid,andmiscellaneoussettings.Withineachsettingare severalvariants,dependentontype(s)ofunderlyingcrust,structuralposition,sediment supply, and inheritance. Subsidence of sedimentary basins results from (1) thinning of crust (2) thickening of mantle lithosphere (3) sedimentary and volcanic loading (4) tectonic loading (5) subcrustal loading (6) asthenospheric flow, and (7) crustal densification. Basins vary greatly in size, life span, and preservation potential, with short-lived basins formed in active tectonic settings, especially on oceanic crust, having low preservation potential, and long-lived basins formed in intraplate settings having the highest preservation potential. Continental rifts may evolve into nascent ocean basins, which commonly evolve into active ocean basins bordered by intraplate continental margins with three types of configurations: shelf-slope-rise, transform, and embankment. Continental rifts that do not evolve into oceans become fossil rifts, which later become sites for development of intracratonic basins and aulacogens. If all plate boundaries within and around an ocean basin become inactive, a dormant ocean basin develops, underlain by oceanic crust and surrounded by continental crust. Sites for sedimentary basins in convergent settings include trenches, trench slopes, forearcs, intra-arcs, backarcs, and retroarcs. Complex dynamic behavior of arc-trench systems results in diverse configurations for arc-related basins. Most notable is the overall stress regime of the arc-trench system, with resulting response along and behind the magmatic arc. Intra-arc rifting in highly extensional arcs commonly evolves into backarc spreading to form new oceanic crust. Backarcs of neutral arcs can contain any type of preexisting crust that was trapped there at the time of initiation of the related subduction zone. Highly compressional arcs develop retroarc foldthrust belts and related retroforeland basins, and may develop hinterland basins; in extreme cases, broken retroforelands may develop in former cratonal areas. As nonsubductable continental or arc crust is carried toward a subduction zone, collision generally initiates at one point and the resulting suture propagates away from this point of initial impact. Remnant ocean basins form on both sides of the initial impact point, and rapidly fill with sediment derived from the suture zone. As collision continues, the flux of sediment into the remnant ocean basin(s) increases concurrently with shrinkage of the basin until final suturing and obduction of the accreted sediment occur. Concurrently with collision, proforeland basins form on continental crust of the subducting plate and collisional retroforeland basins form on the overriding plate. Impactogens, broken forelands, and hinterland basins also may result. Intransformsettingsandalongcomplexstrike-slipfaultsystemsrelatedtoconvergent settings, changing stress regimes related to irregularities in fault trends, rock types, and plate motions result in transtension, transpression, and transrotation, with associated complex, diverse, and short-lived sedimentary basins.