Field Trip #3: Paleozoic Rocks II Cretaceous Stratigraphy of Central Texas

Field Trip #3: Paleozoic Rocks II Location Geology Assignment / Methods Reminders Text: Manual, p ; Compton, p ; ;

Location Hamilton Creek road cut near Max Starke Dam Stop 1 Stop 2 (E. McBride)

(Luis Garcia) Location Creek near Stop 2

Geology

Bastrop N 5 miles Paleozoic Sedimentary Rocks Pennsylvanian – Smithwick Shale Ordovician – Honeycut Formation of Ellenburger Group

(Manual, p. 272)

Paleozoic Events Geology Flooding by Shallow Seas Uplift Ouachita Mts (Penn) Faulting (Penn) Erosion of Ouachitas (P-J)

sabkha evaporites karst natural gas - subsurface Ellenburger Group Geology (nps.gov)

Geology Guidebook of the Geology of Travis County

marine high sediment supply turbidites Smithwick Shale Geology (E. McBride)

Field Trip #3: Paleozoic Rocks II Location Geology Assignment / Methods Reminders Text: Manual, p ; Compton, p ; ;

Assignment / Methods 1) Smithwick Shale Paleocurrent and Deformation Features measure and plot the orientation of: 1) joints 2) faults 3) sandstone dikes 4) fossil wood fragments 5) current ripples and solemarks

water-saturated sediment excess pore pressure sandstone feeder bed sandstone dike (416M) Assignment / Methods

clastic dikes and joints Assignment / Methods (E. McBride)

solemarks 416M groove casts Assignment / Methods flute casts (416M)

Assignment / Methods plot features in 4 rings show # of measurements show bi-directional trends

Assignment / Methods 2) Honeycut Formation Checklist road cut near Max Starke Dam (E. McBride)

limestone vs dolomite Assignment / Methods Dolomite - Thin Section Dolomite - SEM (Soil Science Society of America)

stylolites vs stromatolites Assignment / Methods (Luis Garcia) (Earth and Ocean Sciences at UBC)

fault breccia vs solution collapse breccia Assignment / Methods (Compton, p. 183) solution collapse breccia – filled cave fault breccia – repeated crushing / cementation

soft-sediment deformation vs brittle deformation Assignment / Methods (Compton, p. 243) faults break more resistant layers only mottled textures in shear zone

teepee structure and geopetal structure Assignment / Methods (Matt Campbell) Geopetal – Thin Section

Field Trip #3: Paleozoic Rocks II Location Geology Assignment / Methods Reminders Text: Manual, p ; Compton, p ; ;

Reminders Water Lunch Clipboard Colored Pencils Ruler & Protractor Extra Paper Brunton Rock Hammer HCl Acid Hand Lens Field Notebook Lab Manual

Field Trip #3: Paleozoic Rocks II Cretaceous Stratigraphy of Central Texas

Paleogeography and Sea Level Stratigraphy

Late Cretaceous Paleogeography Paleogeography and Sea Level

Cretaceous Stratigraphy of Central Texas Paleogeography and Sea Level Stratigraphy

(Manual, p. 272)

Stratigraphy relatively flat-lying retreating escarpment (Duex and Lock, Univ. LA)

Stratigraphy resistant and non-resistant limestone

(

Glen Rose Limestone Stairsteps Hensell Sand Badlands hard (pure) and soft (clay-rich) shallow subtidal and supratidal sand, conglomerate, paleosols terrestrial environment ( Stratigraphy

Oyster-rich Del Rio Clay pure limestone and dolomite chert-rich carbonaceous clay pyrite – anoxic lagoon Edwards Limestone “Swiss Cheese” Stratigraphy