View source for Lusk Creek Fault Zone

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{{Feature Entry
|Feature name=Lusk Creek Fault Zone
|Historical=Yes
|Discarded=No
|New_feature=No
|New name=No
|Parent_Feature=Fluorspar Area Fault Complex
|Location=From western Massac to northeastern Pope County (K-6, 7 and [[:file:Bul100_plate_2.jpg|pl. 2]])
|References=S. Weller and Krey 1939, J. Weller 1940, J. Weller et al. 1952, Heyl et al. 1965, Baxter et al. 1967, Kolata et al. 1981, Klasner 1982, Nelson 1986, Nelson and Lumm (1987), Nelson et al. 1991, Bertagne and Leising 1991, Weibel et al. 1993
|Description=The Lusk Creek Fault Zone marks the northwest boundary of
the [[Fluorspar Area Fault Complex]], and it is the northwestern-most
structure along which fluorspar has been mined. The
zone extends southwestward from the southern end of the
Shawneetown Fault Zone in Section 25, T11S, R6E, Pope
County, into western Massac County, where it disappears
beneath the Quaternary alluvium. The northeastern continuation
of the Lusk Creek Fault Zone is known as the Herod
Fault Zone. The Lusk Creek Fault Zone forms the northwest
margin of the Dixon Springs Graben.

The Lusk Creek Fault Zone is composed of subparallel,
high-angle normal and reverse faults. Width of the fault zone
varies from a few hundred feet to almost 1 mile (1.5 km).
Cumulative displacement averages roughly 500 feet (150 m)
down to the southeast, but local displacements on individual
faults may be as great as 1,500 feet (450 m). The fault zone dips
approximately 70° to the southeast near the surface.

The Lusk Creek Fault Zone appears to have undergone at
least three major episodes of movement. The first was during
Early Cambrian time when the [[Reelfoot Rift]] developed. A
seismic reflection profile (Bertagne and Leising 1991) indicates
that this was an episode of normal faulting. The southeast
side of the fault zone was downthrown, allowing thicker
accumulation of sediment on the southeast. The second episode
in late Pennsylvanian to Permian time was compressional
and resulted in reverse faulting. The third episode
(early Mesozoic?) was again normal faulting, which canceled
the reverse movement. Slices of rock raised during reverse
faulting have remained high within the fault zone at several
places ([[#Figure(s)|fig. 47]]). The most striking example is at CLay Diggings
(NE SE, Section 16, T12S, R6E) where a central slice of [[ilstrat:5060|Ste. Genevieve Limestone]] is juxtaposed with upper [[ilstrat:4020|Chesterian]]
strata on the northwest and Pennsylvanian rocks on the
southeast (Weibel et al. 1993). The final episode of normal
faulting sharply dragged and tilted the layers down to the
southeast all along the fault zone ([[#Figure(s)|fig. 48]]). The [[Dixon Springs Graben]] is a product of the last movement (Nelson 1986,
Nelson et al. 1991, Weibel et al. 1993).

This inferred sequence of movement is the same as that
proposed by Nelson and Lumm (1987) for the [[Shawneetown Fault Zone]], which connects with the Lusk Creek Fault Zone.

Several small fluorspar mines operated within the Lusk
Creek Fault Zone during the 1940s and earlier. Most of these
worked at stratigraphic levels higher than those of the richest
deposits farther southeast. Deeper exploration along the Lusk
Creek Fault Zone might yield additional reserves.

See also [[Dixon Springs Graben|DIXON SPRINGS GRABEN]].
|Lat=37.3842663788705
|Long=-88.6795462724237
|Zoom=10
|Category1=Fault zone
}}
==References==
==Figure(s)==
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|<gallery caption="" widths=250px heights=250px perrow=4>
B100 figure 47.jpg|'''

{{#show: file:B100 figure 47.jpg |?Figure ID|format=list}}'''&nbsp; &nbsp;{{#show: file:B100 figure 47.jpg |?Caption|format=list}}
B100 figure 48.jpg|'''{{#show: file:B100 figure 48.jpg |?Figure ID|format=list}}'''&nbsp; &nbsp;{{#show: file:B100 figure 48.jpg |?Caption|format=list}}
Bul100_plate_2.jpg|'''{{#show: file:Bul100_plate_2.jpg |?Figure ID|format=list}}'''&nbsp; &nbsp;{{#show: file:Bul100_plate_2.jpg |?Caption|format=list}}
</gallery>
|}</center>