Group5_2012 - University of South Alabama

Report
The Talladega Slate Belt
By Steven Stokes, Daniel Rollins,
Matthew Sahawneh, Krystal Russell,
and Ashley Stewart
Where We’re Going
• Cheaha State Park
• Located in northern Clay and southwestern
Cleburne counties
• May 20-25
Location:
NorthEastern
Alabama
Near the
town of
Sylacauga,
Alabama
Talladega Slate Belt
• Composed primarily of low-grade
metamorphic rocks
• Bounded to the Northwest by a foreland fold
and thrust fault system known as the
Talladega fault or the Columbiana fault
• To the southeast is marked by high grade
metamorphism caused by both the Hollins
Line fault and the Goodwater-Enitachopco
fault system.
Talladega Slate Belt
• Alleghanian thrust sheet
• Metamorphosed to lower green schist facies
during the Acadian orogeny and thrust above
the foreland fold and thrust belt.
• Believed to be associated with main pulse of
Early to Middle Devonian Acadian orogeny.
Sequences
• Composed of 4 lithologic groups
– Hillabee Greenstone
– Sylacauga Marble
– Talladega
– Kahatchee Mountain
Hillabee Greenstone
• 2.6 kilometers thick
• Ordovician Age 457m.y.
• Greenstones and Greenschists
– What is a greenstone?
– Bulk of sequence
• Albite, Actinolite, Epidote, Zoisite, Clinozoisite,
and Chlorite
• Tabular and extrusive
Sylacauga Marble
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•
•
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Jumbo Dolomite at base
Dolomite and Calcite marbles
Nature of Dolomite
Nature and use of marble
Sylacauga Marble
• Below Lay Dam Formation of Talladega Group
– Unconformity between the two
– Diamictites
– What is diamictite?
• Lack of fossils make age correlation difficult
• Cambrian to Ordovician
Talladega Group
• Clastic
• Divided into several
formations
– Lay Dam Formation
– Cheaha Quartzite Member
– Erin Slate Member
– Butting Ram Sandstone
– Jemison Chert
Lay Dam Formation
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•
•
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Overlies Sylacauga
Oldest
Silurian to Lower Devonian.
Greenish-gray, slightly calcareous sericite
phyllites and slates
• Sandstone bodies small, grade into phyllites
• Rapid deposition.
Cheaha Quartzite Member
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•
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Metasandstone in Lay Dam Formation
Sandy phyllites and coarse grained quartzites
Fines upward
Devonian
Primary Structures
– Horizontally bedded, graded intervals
– Low angle pebbles structures
– Channel fill deposits
– Tabular and trough bedding
Erin Slate Member
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•
•
•
Also member of Lay Dam Formation
Thick highly carbonaceous phyllites or slate
Less mature than Cheaha Quartzite member
Lagoon depositional environment
Butting Ram Sandstone
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•
•
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•
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Thin green chloritic, arkosic metasandstone
Subrounded to rounded quartz sand
Feldspathic
Tidal channel deposits
Very discontinuous
Points of elevated crests
Jemison Chert Interval
• Above Butting Ram Sandstone
• Interbedded white, paper thin quartzites
• Intercalated with black graphitic phyllites of Erin
Slate
• White to pale light gray, very dense, very fined
quartzite
• Complexly folded
• Intense deformation
• Lower Devonian
Kahatchee Mountain Group
• Named Mountain Group because it can be
found in the mountains northwest of
Syllacuaga.
• Width is highly variable.
• Carboniferous in age. (Spores found that
indicate carboniferous in metamorphic
frontblock of sequence)
Formations within the Kahatchee
Mountain Group
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•
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Waxahatchee Slate
Brewer Phyllite
Wash Creek Slate
Sawyer Limestone
*Chilton Fault
Deformational Phase 1 – D1
• F1 folds are invariably tight to isoclinal
• Interlimb angle is 20 to 0 degrees
• They are assymetric with stort limbs are 20%
shorter than long limbs
• It has S1 foliations
Deformational Phase 2 and 3
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F2 folds can be only seen in thin section
F3 folds are small folds 1mm to 1cm
F3 they distort both the compositional layers
F3 crenulation fold axial plane with S1-S2
surface
Deformational Phase 4 – D4
• F4 folds can be seen on regional map
• F4 folds cut through the F1 folds
• F4 axial plane strikes northwest to
southeast
• A major faulting event
Questions?

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