Title: SEDIMENTOLOGY%20AND%20DEPOSITIONAL%20HISTORY%20OF%20THE%20BARNETT%20FORMATION%20AND%20EQUIVALENT%20MISSISSIPPIAN%20ROCKS
1- SEDIMENTOLOGY AND DEPOSITIONAL HISTORY OF THE
BARNETT FORMATION AND EQUIVALENT MISSISSIPPIAN
ROCKS - IN THE FT. WORTH BASIN
Stephen C. Ruppel and Robert G. Loucks Bureau of
Economic Geology The University of Texas at Austin
2MISSISSIPPIAN STRATIGRAPHY
SOUTHERN MIDCONTINENT
3LATE MISSISSIPPIAN PALEOGEOGRAPHY
WESTERN HEMISPHERE
Carbonate Platform (Chappel deposition)
Slope/Basin (Barnett deposition)
Marathon Ouachita Troughs (Caballos deposition)
Ouachita Highlands (source area)
4TOTAL MISSISSIPPIAN THICKNESS
SOUTHERN MIDCONTINENT
- Mississippian Carbonates
- Lake Valley
- Mississippian LS
- Chappel
- Osage
- Meramec
- St. Louis
- Ste. Genevieve
- Chester
- Barnett Formation
- NM - TX
- Rancheria
- Helms
- OKLA
- Caney
- Fayetteville
From Craig and Connor (1979)
5UPPER MISSISSIPPIAN SUBCROP
SOUTHERN MIDCONTINENT
From Craig and Connor (1979)
6MIDDLE MISSISSIPPIAN PALEOGEOGRAPHY
SOUTHERN MIDCONTINENT
Probable Position of Platform Margin
7MISSISSIPPIAN FACIES MODEL Northwestern Ft. Worth
Basin
From Ruppel (1989)
8MISSISSIPPIAN FACIES Updip Carbonate Section
Water-escape
Reef Breccia
Turbidites
Shoal/buildup Grainstone-packstone
Graded-bedding
Inter-buildup Spiculite
9MISSISSIPPIAN FACIES SUCCESSION
SOUTHWESTERN FT. WORTH BASIN
10MISSISSIPPIAN CARBONATE FACIES
SOUTHWESTERN FT. WORTH BASIN
Whites Crossing Meramecian
Chappel Fm Osagean
Debris Beds
In Situ
Coarse crinoid wackestone
Coarse skeletal wackestone
Interbedded mud-rock
Red skeletal wackestone
11BARNETT MUDROCK FACIES
SOUTHWESTERN FT. WORTH BASIN
Meramecian - Chesterian
LAMINATED MUDROCK (SHALE) WITH CARBONATE LENSES
Carbonate turbid flow
Outcrop, San Saba Co, TX
Concretion/Lens
Skeletal debris flow
Cores McCulloch Co, TX
12BARNETT LOG CHARACTER FACIES CENTRAL FT.
WORTH BASIN
Wise Co., TX
13BARNETT FACIES FT. WORTH BASIN
Laminated mudstone
Graded Bedding
Skeletal Debris
From Petrazis (2005)
14BARNETT FACIES FT. WORTH BASIN
FORESTBURG
FORESTBURG
BARNETT
Siliceous mudstone
Calcareous mudstone
From Petrazis (2005)
15BARNETT FAUNA
- Deep Water Brachiopods
- Agglutinate Foraminifera
- Radiolaria
- Molluscs
- Conodonts
- Goniatites
- Rare Infauna
16MISSISSIPPIAN DEPOSITIONAL MODEL
FT. WORTH BASIN
17LOG-BASED MINERALOGY MODELING
WISE COUNTY, TX
Penn
Upper Barnett
Forestburg
Lower Barnett
18PLATFORM SEQUENCE STATIGRAPHY Sacramento
Mountains, NM
Ft. Worth Basin
Llano Uplift
Hardeman Basin
19MISSISSIPPIAN STRATIGRAPHY FACIES
FT. WORTH BASIN AREA
20CONCLUSIONS
- Barnett rocks record the progressive drowning of
the southern Laurussian paleocontinent during the
Mississippian - The Barnett is a slope/basin succession of
hemipelagic mudrocks that formed in a stratified
ocean along the continental margin. - Forestburg carbonate-rich intervals represent
flux of platform detritus in to the basin. - Updip carbonate successions document at least one
major sea level fall event.
21KEY ISSUES FOR FUTURE STUDY
- Define timing of initial platform drowning.
- Characterize details of Barnett sedimentology.
- Define source and geometry of Forestburg.
- Determine the extent and possible significance of
sea- level fall events. - Refine the biostratigraphic framework
- Integrate all data into regional model.