Interactions Between Strike-Slip And Thrust Tectonics: Controls on Sand
Distributions Through Miocene Basin Arrays, Southern Italy
Butler, Robert W.H.1,
Stefano Mazzoli2 (1) University of Leeds, Leeds, United Kingdom (2) University of Naples, Napoli, Italy
The Miocene basins of the Southern Apennines of Italy contain syn-tectonic accumulations of turbidite
sands and related deposits. These include thick, reservoir-quality sandstones,
some derived from reworked cratonic sediments (e.g.
the quartz-arenitic Numidian
Flysch) and some from crystalline basement from
adjacent mountain belts (e.g. Gorgoglione Flysch). The basins are tectonically controlled, in part by
NE-directed thrusting and partly by chiefly left-lateral, NW-SE strike-slip.
This case study provides regional and outcrop analogues for other large-scale
settings such as the southern Caribbean and parts of SE Asia. The complex kinematic regime of the Southern Apennines reflects the pattern of
3D slab roll-back in the proto Tyrrhenian-Apennine orogen.
The resulting evolution of basins is believed to have controlled the routing of
major turbidity currents for reservoir sands through time. They also provide
otherwise intrabasinal sources for catastrophic calci-metaturbidites within internal basins (e.g. the Cilento Group). While existing studies have treated each
Miocene succession as a distinct tectonostratigraphic
unit, we use the correlative framework provided by megaturbidites
and regionally extensive olistostromal horizons to
show stratigraphic links between basins. Modulation
of intrabasinal bathymetry is manifest by different
distributions of sand net-to-gross between locations. These are interpreted in
terms of variations in the degree of flow confinement and flow stripping. The
effect is to build distinctive stratigraphies within
sub basins. Thus sand quality (relating to the provenance) and sand stacking
are intimately related to syn-depositional tectonics,
both within the basins and within the orogenic
hinterland to control the activity of different clastic
source areas.