Structural architecture and displacement accommodation mechanisms at the termination of the Priestley Fault, northern Victoria Land, Antarctica

We present the results of field investigations carried out at the southern termination of the Priestley Fault, a major Cenozoic right-lateral strike-s lip fault system in northern Victoria Land, Antarctica. The Priestley Fault was originally traced from offshore seismic profiles. Its onshore prosecut ion was inferred from the regional geological picture. Our work provides th e first robust dataset on the kinematics and structural architecture of the Priestley Fault. The fault system includes a principal displacement zone ( PDZ), where most horizontal displacement is accounted for, and a transtensi onal splay zone (TSZ) in the southern side consisting of a major basin at t he fault tip, the Terror Rift, and minor ones paralleling it cratonward. Pa rt of the strike-slip displacement is transferred by fault splaying from th e principal displacement zone to the basin-boundary faults in the transtens ional splay zone. The principal displacement zone is characterised by stron gly transpressive deformation and this contrasts with the extensional compo nent occurring in the transtensional splay zone. Such a contrast is only ap parent because the two regions are kinematically linked. Transfer of the re sidual right-lateral strike-slip displacement from the tip region of the pr incipal displacement zone to the basin-boundary fault systems of the Terror Rift represents the most effective displacement compensation mechanism at the termination of the Priestley Fault. It provides an additional solution for reducing the well known and still fully unsolved discrepancy between la rge translations of adjacent crustal blocks and the lack of comparable disp lacement values in their boundary strike-slip fault systems. The unquestion able evidence of intense Cenozoic brittle deformations in north Victoria La nd imposes a re-examination of the regional tectonic framework, commonly in terpreted as the mere result of the Early Paleozoic Ross Orogeny. (C) 2001 Elsevier Science B.V. All rights reserved.