The Corinth Rift, central Greece, enables analysis of early rift development as it is young (<5 Ma) and highly active and its full history is recorded at high resolution by sedimentary systems. A complete compilation of marine geophysical data, complemented by onshore data, is used to develop a high-resolution chronostratigraphy and detailed fault history for the offshore Corinth Rift, integrating interpretations and reconciling previous discrepancies. Rift migration and localization of deformation have been significant within the rift since inception. Over the last circa 2 Myr the rift transitioned from a spatially complex rift to a uniform asymmetric rift, but this transition did not occur synchronously along strike. Isochore maps at circa 100 kyr intervals illustrate a change in fault polarity within the short interval circa 620-340 ka, characterized by progressive transfer of activity from major south dipping faults to north dipping faults and southward migration of discrete depocenters at~30 m/kyr. Since circa 340 ka there has been localization and linkage of the dominant north dipping border fault system along the southern rift margin, demonstrated by lateral growth of discrete depocenters at~40 m/kyr. A single central depocenter formed by circa 130 ka, indicating full fault linkage. These results indicate that rift localization is progressive (not instantaneous) and can be synchronous once a rift border fault system is established. This study illustrates that development processes within young rifts occur at 100 kyr timescales, including rapid changes in rift symmetry and growth and linkage of major rift faults.
19Physical models predict that multiphase rifts that experience a change in extension direction between 20 stretching phases will typically develop non-colinear normal fault sets. Furthermore, multiphase rifts 21 will display a greater frequency and range of styles of fault interactions than single-phase rifts. 22Although these physical models have yielded useful information on the evolution of fault networks in 23 map view, the true 3D geometry of the faults and associated interactions are poorly understood. Here, 24we use an integrated 3D seismic reflection and borehole dataset to examine a range of fault 25 interactions that occur in a natural multiphase fault network in the northern Horda Platform, northern 26North Sea. In particular we aim to: i) determine the range of styles of fault interaction that occur 27 between non-colinear faults; ii) examine the typical geometries and throw patterns associated with 28 each of these different styles; and iii) highlight the differences between single-phase and multiphase 29 rift fault networks. Our study focuses on a ca. 350 km 2 region around the >60 km long, N-S-striking 30 Tusse Fault, a normal fault system that was active in the Permian-Triassic and again in the Late 31Jurassic-to-Early Cretaceous. The Tusse Fault is one of a series of large (>1500 m throw) N-S-striking 32 faults forming part of the northern Horda Platform fault network, which includes numerous smaller 33 (2-10 km long), lower throw (<100 m), predominantly NW-SE-striking faults that were only active 34 during the Late Jurassic to Early Cretaceous. We examine how the 2nd-stage NW-SE-striking faults 35 grew, interacted and linked with the N-S-striking Tusse Fault, documenting a range of interaction 36 styles including mechanical and kinematic isolation, abutment, retardation and reactivated relays. Our 37 results demonstrate that: i) isolated, non-interacting and abutting interactions are the most common 38 fault interaction styles in the northern Horda Platform; ii) pre-existing faults can act as sites of 39 nucleation for 2nd-stage faults or may form mechanical barriers to propagation; iii) the throw 40 distribution on reactivated 1st-stage faults will be modified in a predictable manner if they are 41 intersected or influenced by 2nd-stage faults; iv) sites of fault linkage and relay-breaching associated 42 with the first phase of extension can act as preferential nucleation sites for 2nd-stage faults; and v) the 43 development of fault intersections is a dynamic process, involving the gradual transition from one 44 style to another. 45 46
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