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 • • • • 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 • • • • 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 • • • • • 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 • • • • Also member of Lay Dam Formation Thick highly carbonaceous phyllites or slate Less mature than Cheaha Quartzite member Lagoon depositional environment Butting Ram Sandstone • • • • • • 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 • • • • • 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 • • • • 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?