The principle structural features associated with the extensional phase are faults and
fault blocks, associated either with the predominant NNW-SSE basin margin fault
systems, or less importantly ENE-WSW systems. Faults and fault blocks are
generally steeply dipping and the blocks are generally quite narrow and heavily
faulted. Basement highs and horst blocks are also common, as are sedimentary drape
structures developing from differential compaction across these. Rollovers associated
with the basin margin fault systems are also likely