INVITED EDITORIAL Processes and controls in the stratigraphic development of extensional basins

Abstract

INTRODUCTIONThe sedimentary rocks that are preserved as the in®ll to continental extensional basins provide a tantalizing record of the evolution of coupled geomorphic±sedimentary systems in response to rifting. This record is tantalizing because, even though the stratigraphic record can arguably be considered to provide the only complete record of the effects of external forcing on basin evolution, how the sedimentary effects of this forcing come to be preserved in the stratigraphic record is not well understood. The stratigraphy rarely enables us to make direct links with forcing factors because independent evidence of the latter is generally no longer preserved. Thus our task of extracting the in¯uence of factors such as variations in tectonic subsidence and uplift, source-area erosion, sea-level change, climate, etc., from the stratigraphic record is daunting to say the least. Indeed, some would argue that the problem is largely intractable. Despite this, sedimentary geologists and stratigraphers are increasingly armed with a whole new range of tools that enable them to tease more information out of the apparently unyielding rocks. These tools include new dating techniques, novel geochemical methods and numerical modelling approaches. However, more importantly, we are currently seeing a revolutionary transition in our approach to the subject. Sedimentary geologists are no longer merely content to describe, document and speculate on the rocks they study, but are seeking to understand in more depth (and with greater quanti®cation) the processes that govern their organization. Our aim in this special issue is to examine some of the emerging process-driven themes that are central to current research on stratigraphy in extensional basins.Until relatively recently, tectono-stratigraphic models for rift basins focused on predictions of basin-scale stratigraphic geometries; these models did not attempt to address the ®ner-scale details of stratal geometry that stratigraphers were documenting in numerous basins.The stratigraphic community, on the other hand, lacked process-driven models to provide a framework within which their detailed observations could be interpreted. For example, it was dif®cult to explain complex temporal and spatial patterns of sedimentary architecture in terms of variations in fault-controlled subsidence. Moreover, few workers had made links between sediment¯uxes as recorded in stratigraphy and the erosional evolution of source areas. Clearly, in such tectonically active basins, footwall erosion and sediment¯ux to the hangingwall basin are linked by the evolution of fault-controlled topography within, and adjacent to, the rift basins.Although a number of books have been published in recent years that have focused on the stratigraphy of rift basins, in particular on the interaction of tectonics and sedimentation (Lambiase, 1995. ;Purser & Bosence, 1998. ;Morley 2000. ), none of these has dealt speci®cally with the processes governing stratigraphic development in rift basins. This special volume ...

Tectono‐sedimentary evolution of the western Corinth rift (Central Greece)

“…Field and numerical studies indicate that, in evolving rifts, assuming constant extension rate, an initially broad zone of deformation becomes localized onto a small number of discrete, and increasingly large fault zones so that sedimentation becomes focused into fewer, larger depocentres (e.g. Gupta et al ., ; Gawthorpe & Leeder, ; Gupta & Cowie, ; Cowie et al ., , ). The Corinth rift history presented in this article differs from this standard model in several significant ways.…”

Investigating the surface process response to fault interaction and linkage using a numerical modelling approach

“…A large body of theoretical work exists which predicts how extensional faults evolve in the brittle crust and how these faults control accommodation creation in rift basins (e.g. see Gupta & Cowie, 2000 for a review). In contrast, relatively little theoretical work has been published to date which aims to demonstrate how the growth of these same faults influences surface processes occurring within the uplifted footwall that borders the basin.…”

The Canyonlands model for planetary grabens: revised physical basis and implications

“…Depocenters along faults and grabens are closely associated with the position of maximum depth, or maximum displacement, along the faults (Gibbs, 1990;Roberts and Yielding, 1994;Gupta et al, 1998;Gawthorpe and Leeder, 2000;Gupta and Cowie, 2000;McLeod et al, 2000;Grosfils et al, 2003). These depocenters normally occur near fault midpoints and, with time, shift toward the stepover of echelon or interacting faults as linkage begins (Morley et al, 1990;Morley, 1999).…”