The Upper Jurassic Clarksville Formation in northern Texas and southern Oklahoma is a productive but poorly understood sandstone–conglomerate unit with unresolved questions regarding its depositional environment and sediment provenance. This study evaluates the depositional setting, spatial distribution, and diagenetic controls of the Clarksville Formation using integrated core and well log analyses in Red River County, Texas. Three cores (Lennox Unit #1, Reeder Oil Unit #2, and Reeder Oil Unit #7) were analyzed for lithology, mineralogy, porosity, permeability, and fluid saturation, and correlated with 137 well logs to map formation thickness and regional trends.
Four lithofacies were identified based on core description and petrographic analysis. Sandstone 1 is a well-sorted quartz wacke composed of very fine to fine sand with occasional silt, parallel bedding, and silica or hematite cementation, with an average porosity of 12.8% and permeability of 20.8 mD. Sandstone 2 consists of variably sorted quartz wacke containing granule- to pebble-sized clasts (2–10 mm), massive bedding, and mixed cementation, averaging 10.8% porosity and 8.0 mD permeability. Conglomerate 1 is a clast-supported polymictic conglomerate with granule- to cobble-sized clasts (2–95 mm) and calcite-dominated cementation, averaging 8.3% porosity and 18.0 mD permeability. Conglomerate 2 is a matrix-supported polymictic conglomerate with poorly sorted granule- to cobble-sized clasts, mixed cementation, and lower permeability (average 11.4% porosity and 3.3 mD).
Isopach mapping identifies two areas of maximum thickness: approximately 180 ft (55 m) in the Clarksville Field of south-central Red River County and 170 ft (51 m) in the Topaz Oil Field to the east. Thickness and facies trends indicate southward to westward sediment progradation and a downdip transition from coarse-grained proximal facies to finer-grained sandstones interfingering with the Smackover and Buckner formations. These patterns are inconsistent with previously proposed north-derived arid alluvial fan or coastal fan-delta models.
Rather, the Clarksville Formation is interpreted as a fan-fed, gravelly braided stream system, dominated by tractional bedload transport during sustained fluvial flow and punctuated by episodic high-energy floods. Conglomeratic facies record channelized gravel bars and localized debris-levee deposits formed during flood events, whereas sandstone facies represent lateral bar, bar-margin, and waning-flow deposition associated with downstream reworking within a braided fluvial complex. Among the identified lithofacies, Sandstone 1 exhibits the highest reservoir quality, while diagenetic processes including clay, hematite, and calcite cementation exert a strong control on porosity and permeability across the formation.
","abstract_html":"<p>The Upper Jurassic Clarksville Formation in northern Texas and southern Oklahoma is a productive but poorly understood sandstone–conglomerate unit with unresolved questions regarding its depositional environment and sediment provenance. This study evaluates the depositional setting, spatial distribution, and diagenetic controls of the Clarksville Formation using integrated core and well log analyses in Red River County, Texas. Three cores (Lennox Unit #1, Reeder Oil Unit #2, and Reeder Oil Unit #7) were analyzed for lithology, mineralogy, porosity, permeability, and fluid saturation, and correlated with 137 well logs to map formation thickness and regional trends.</p> <p>Four lithofacies were identified based on core description and petrographic analysis. Sandstone 1 is a well-sorted quartz wacke composed of very fine to fine sand with occasional silt, parallel bedding, and silica or hematite cementation, with an average porosity of 12.8% and permeability of 20.8 mD. Sandstone 2 consists of variably sorted quartz wacke containing granule- to pebble-sized clasts (2–10 mm), massive bedding, and mixed cementation, averaging 10.8% porosity and 8.0 mD permeability. Conglomerate 1 is a clast-supported polymictic conglomerate with granule- to cobble-sized clasts (2–95 mm) and calcite-dominated cementation, averaging 8.3% porosity and 18.0 mD permeability. Conglomerate 2 is a matrix-supported polymictic conglomerate with poorly sorted granule- to cobble-sized clasts, mixed cementation, and lower permeability (average 11.4% porosity and 3.3 mD).</p> <p>Isopach mapping identifies two areas of maximum thickness: approximately 180 ft (55 m) in the Clarksville Field of south-central Red River County and 170 ft (51 m) in the Topaz Oil Field to the east. Thickness and facies trends indicate southward to westward sediment progradation and a downdip transition from coarse-grained proximal facies to finer-grained sandstones interfingering with the Smackover and Buckner formations. These patterns are inconsistent with previously proposed north-derived arid alluvial fan or coastal fan-delta models.</p> <p>Rather, the Clarksville Formation is interpreted as a fan-fed, gravelly braided stream system, dominated by tractional bedload transport during sustained fluvial flow and punctuated by episodic high-energy floods. Conglomeratic facies record channelized gravel bars and localized debris-levee deposits formed during flood events, whereas sandstone facies represent lateral bar, bar-margin, and waning-flow deposition associated with downstream reworking within a braided fluvial complex. Among the identified lithofacies, Sandstone 1 exhibits the highest reservoir quality, while diagenetic processes including clay, hematite, and calcite cementation exert a strong control on porosity and permeability across the formation.</p>","abstract_has_math":false,"creators":["Parker, Matthew Allen"],"institution":null,"degree_name":"Master of Science - Geology","degree_level":"Thesis","degree_discipline":"Geology","degree_department":null,"school":null,"contributors":["Dr. Julie Bloxson","Dr. R. LaRell Nielson","Dr. Michael Read"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2025,"date_issued":"2025-12-01T08:00:00Z","date_published":"2025-12-01T08:00:00Z","updated_at":"2026-07-24T04:30:49Z","subjects":["Clarksville formation","Upper Jurassic","diagenesis","depositional environment","mineralogy","well log analysis","porosity","permeability","Geology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholarworks.sfasu.edu/etds/648","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Dr. Julie Bloxson","Dr. R. 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This study evaluates the depositional setting, spatial distribution, and diagenetic controls of the Clarksville Formation using integrated core and well log analyses in Red River County, Texas. Three cores (Lennox Unit #1, Reeder Oil Unit #2, and Reeder Oil Unit #7) were analyzed for lithology, mineralogy, porosity, permeability, and fluid saturation, and correlated with 137 well logs to map formation thickness and regional trends.
Four lithofacies were identified based on core description and petrographic analysis. Sandstone 1 is a well-sorted quartz wacke composed of very fine to fine sand with occasional silt, parallel bedding, and silica or hematite cementation, with an average porosity of 12.8% and permeability of 20.8 mD. Sandstone 2 consists of variably sorted quartz wacke containing granule- to pebble-sized clasts (2–10 mm), massive bedding, and mixed cementation, averaging 10.8% porosity and 8.0 mD permeability. Conglomerate 1 is a clast-supported polymictic conglomerate with granule- to cobble-sized clasts (2–95 mm) and calcite-dominated cementation, averaging 8.3% porosity and 18.0 mD permeability. Conglomerate 2 is a matrix-supported polymictic conglomerate with poorly sorted granule- to cobble-sized clasts, mixed cementation, and lower permeability (average 11.4% porosity and 3.3 mD).
Isopach mapping identifies two areas of maximum thickness: approximately 180 ft (55 m) in the Clarksville Field of south-central Red River County and 170 ft (51 m) in the Topaz Oil Field to the east. Thickness and facies trends indicate southward to westward sediment progradation and a downdip transition from coarse-grained proximal facies to finer-grained sandstones interfingering with the Smackover and Buckner formations. These patterns are inconsistent with previously proposed north-derived arid alluvial fan or coastal fan-delta models.
Rather, the Clarksville Formation is interpreted as a fan-fed, gravelly braided stream system, dominated by tractional bedload transport during sustained fluvial flow and punctuated by episodic high-energy floods. Conglomeratic facies record channelized gravel bars and localized debris-levee deposits formed during flood events, whereas sandstone facies represent lateral bar, bar-margin, and waning-flow deposition associated with downstream reworking within a braided fluvial complex. Among the identified lithofacies, Sandstone 1 exhibits the highest reservoir quality, while diagenetic processes including clay, hematite, and calcite cementation exert a strong control on porosity and permeability across the formation.
"]},{"key":"dc:title","label":"Title","values":["Reservoir Characterization of the Clarksville Formation in Red River County, Texas"]}]}],"canonical_facts":{"dc:contributor":["Dr. Julie Bloxson","Dr. R. LaRell Nielson","Dr. Michael Read"],"dc:creator":["Parker, Matthew Allen"],"dc:date.available":["2025-12-09T08:00:00Z"],"dc:description.abstract":["The Upper Jurassic Clarksville Formation in northern Texas and southern Oklahoma is a productive but poorly understood sandstone–conglomerate unit with unresolved questions regarding its depositional environment and sediment provenance. This study evaluates the depositional setting, spatial distribution, and diagenetic controls of the Clarksville Formation using integrated core and well log analyses in Red River County, Texas. Three cores (Lennox Unit #1, Reeder Oil Unit #2, and Reeder Oil Unit #7) were analyzed for lithology, mineralogy, porosity, permeability, and fluid saturation, and correlated with 137 well logs to map formation thickness and regional trends.
Four lithofacies were identified based on core description and petrographic analysis. Sandstone 1 is a well-sorted quartz wacke composed of very fine to fine sand with occasional silt, parallel bedding, and silica or hematite cementation, with an average porosity of 12.8% and permeability of 20.8 mD. Sandstone 2 consists of variably sorted quartz wacke containing granule- to pebble-sized clasts (2–10 mm), massive bedding, and mixed cementation, averaging 10.8% porosity and 8.0 mD permeability. Conglomerate 1 is a clast-supported polymictic conglomerate with granule- to cobble-sized clasts (2–95 mm) and calcite-dominated cementation, averaging 8.3% porosity and 18.0 mD permeability. Conglomerate 2 is a matrix-supported polymictic conglomerate with poorly sorted granule- to cobble-sized clasts, mixed cementation, and lower permeability (average 11.4% porosity and 3.3 mD).
Isopach mapping identifies two areas of maximum thickness: approximately 180 ft (55 m) in the Clarksville Field of south-central Red River County and 170 ft (51 m) in the Topaz Oil Field to the east. Thickness and facies trends indicate southward to westward sediment progradation and a downdip transition from coarse-grained proximal facies to finer-grained sandstones interfingering with the Smackover and Buckner formations. These patterns are inconsistent with previously proposed north-derived arid alluvial fan or coastal fan-delta models.
Rather, the Clarksville Formation is interpreted as a fan-fed, gravelly braided stream system, dominated by tractional bedload transport during sustained fluvial flow and punctuated by episodic high-energy floods. Conglomeratic facies record channelized gravel bars and localized debris-levee deposits formed during flood events, whereas sandstone facies represent lateral bar, bar-margin, and waning-flow deposition associated with downstream reworking within a braided fluvial complex. Among the identified lithofacies, Sandstone 1 exhibits the highest reservoir quality, while diagenetic processes including clay, hematite, and calcite cementation exert a strong control on porosity and permeability across the formation.
"],"dc:identifier":["https://scholarworks.sfasu.edu/etds/648"],"dc:subject":["Clarksville formation","Upper Jurassic","diagenesis","depositional environment","mineralogy","well log analysis","porosity","permeability","Geology"],"dc:title":["Reservoir Characterization of the Clarksville Formation in Red River County, Texas"],"thesis:degree_discipline":["Geology"],"thesis:degree_level":["Thesis"],"thesis:degree_name":["Master of Science - Geology"]},"updated_at":"2026-07-24T04:30:49Z"}