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Fig. 9.
Map showing the relation between
the Cincinnati Arch and the boundary
between Grenville crust and the Eastern
Granite-Rhyolite Province (EGRP) and
the East Continent Rift Basin (ECRB).
Adapted from Drazhoval
et al
. (1992).
The Cincinnati Arch lies just west of this
boundary and it is suggested that its rela-
tively fi xed position and narrow width
are due to uplift or decreased subsidence
within this zone of weak lithosphere. In
this scenario, orogenic stresses generated
to the east were repeatedly transmitted
to this zone of weak lithosphere, which
responded by syndepositional faulting
and resisting subsidence.
300 km
Proterozoic sediments
and volcanics (ECRB)
Grenville Province
Basaltic Rift Zone
Reelfoot Rift
Eastern Granite-Rhyolite
Province (EGRP)
Basaltic Rift Zone
(buried)
The stresses that produced the Cincinnati Arch
in the Late Ordovician were probably responsible
for the reactivation of structural features and for-
mation of syndepositional faults and seismites in
this area (Ettensohn
et al
., 2002). Similar features in
the Upper Ordovician and Middle Silurian farther
north along the Cincinnati Arch also are attributed
to reactivation of basement faults along the bound-
ary between the Grenville Front and EGRP/ECRB
(Onasch & Kahle, 1991, 2002). Additionally, the
long-distance transport of these Taconic orogenic
stresses may have reactivated extensional faults of
the underlying Reelfoot rift to produce the Sebree
Trough (Kolata
et al
., 2001).
patterns in ways not predicted by stratigraphic
models, such as alternating highs and lows
along the axis of an arch (Bradley & Kidd, 1991;
Diecchio, 1993; Holland & Patzkowsky, 1997).
North-to-south variations in sedimentology and
stratigraphy of the Upper Ordovician on the
Cincinnati Arch, specifi cally from the Jessamine
and Nashville domes, indicate that this peripheral
bulge did not behave uniformly throughout this
period, instead recording spatial and temporal
variations in its response to coeval tectonism.
For instance, there is a change in depositional
style from sequences M1-M4 to sequences M5-C6.
Sequences M1-M4 are a thick succession of shal-
low subtidal to peritidal carbonates that were
deposited on a homogeneous, fl at to extremely
gently dipping ramp where facies changes across
this platform were subtle. Peritidal carbonates
rarely amalgamated into regional markers because
there was probably a series of peritidal islands
Lateral sedimentary variation along the
peripheral bulge
Inherited structural features can be reactivated
and can affect sedimentological and stratigraphic
