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| Titel |
A natural example of sub-seismic deformation in the hanging-wall of a fault, County Kerry, Ireland |
| VerfasserIn |
D. C. Tanner, S. Burchardt, C. M. Krawczyk |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022830
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| Zusammenfassung |
| On the Atlantic coast of County Kerry, Ireland, a large fault and its hanging- and footwall are
exposed within Lower Carboniferous shaley limestones. The 3–4 metres wide fault zone is
composed of highly-brecciated fault gouge, which has a sharp transition to the less deformed
strata. The fault zone has been eroded by the sea and thus we were able to map the zone in
three dimensions. The hanging wall is well exposed by a large (12 m high and 30 m long),
planar outcrop that is perpendicular to the fault. The hanging-wall beds are highly fractured
(more than 50 fractures/metre) by synthetic and antithetic fractures with respect
to the main fault. By use of scanlines and observing cross-cutting relationships,
we determine that the antithetic fractures formed first, followed by two phases of
synthetic fracturing. The resulting sub-seismic fracture pattern highly increased the
cross-strata porosity of the hanging-wall, as evidenced by quartz mineralisation
along the fractures. Fault kinematics are shown by slickenslides in the fault zone,
and quartz-filled tension gashes that are perpendicular to the former. Within the
tension gashes, quartz crystals also grew with their c-axes parallel to the kinematic
vector.
A number of hanging-wall fractures have developed into faults themselves. As such, we
are able to observe the process of ongoing brittle deformation in this outcrop and the
breakdown of undeformed strata into ever-decreasing smaller faults, each with their own
domain of related fracturing. |
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