AAPG/GSTT HEDBERG CONFERENCE
“Mobile Shale Basins – Genesis, Evolution and
Hydrocarbon Systems”
Turtles structures created by extension in a thin
detachment setting
Joshua Creviere Turner
BP,
Turtle
structures are generally regarded to be the result of passive or extensional
collapse of underlying salt bodies.
However subsurface examples, in the
I
propose the term extensional turtles to denote a class of turtle structures at
the opposite end of the spectrum from traditional turtles where a mock turtle
lies between. Extensional turtles are
generated purely by extension, unlike mock turtles. Even so, they commonly have some mobile-rock
withdrawal, as they are always associated with a very weak detachment. The distinguishing feature of such structures
is that they are bound by a kinematically linked set
of regional and counter-regional large-offset listric
normal faults. Local complications may
occur where younger regional faults repeatedly cut the counter-regional fault,
resulting in the counter-regional fault becoming reset down-dip. The counter-regional fault may then remain
active, resulting in multiple turtle anticlines. Counter-regional rollover followed by
regional rollover on opposing arcuate listric faults produces four-way plunging turtles.
Offshore
AAPG Search and Discovery Article #90057©2006 AAPG/GSTT Hedberg Conference, Port of Spain, Trinidad & Tobago