GEOLEX

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1966, Geologic atlas of Texas, Texarkana Sheet;
   Elias H. Sellards memorial edition: University of Texas-Austin,
   Bureau of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k	East Texas basin Arkla basin Ouachita folded belt province	Marl

Summary:
Is Upper Cretaceous formation mapped in continuous belt across northeast TX in northern Hunt, Delta, and northwest Bowie Cos, TX (East Texas basin); southeasternmost Fannin, southern Lamar, south-central Red River Cos, TX (Ouachita tectonic belt province); and in a single outcrop area in southwestern Little River Co, AR (Arkla basin). Overlies Pecan Gap Chalk (Upper Cretaceous) west of Clarksville, Red River Co, TX; overlies Annona Chalk (Upper Cretaceous) eastward into AR; overlain by Neylandville Formation (Upper Cretaceous) west of Charleston, Delta Co, TX; overlain by Navarro Group (Upper Cretaceous) eastward to the Red River. Is uppermost Cretaceous unit mapped in southwest AR part of the map area. Map unit described as marl--slightly glauconitic in upper part, highly plastic when wet, strikingly uniform throughout, medium bluish gray to yellowish gray; weathers light gray to white, forms smooth, rolling topography; marine megafossils scarce; thickness 150-450 ft, thins eastward.

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1967, Geologic atlas of Texas, Sherman Sheet;
   Walter Scott Adkins memorial edition: University of Texas-Austin,
   Bureau of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k	East Texas basin Ouachita folded belt province	Clay Limestone

Summary:
Is Upper Cretaceous formation mapped in southeastern Collin Co, TX (Ouachita tectonic belt province) and Hunt Co, TX (East Texas basin) in northeast TX. Overlies Pecan Gap Chalk (Upper Cretaceous); underlies Neylandville Formation (Upper Cretaceous). Map unit described as clay, calcareous, variable amount of silt and glauconite; limestone bed in southern Collin Co 10-13 in thick, aphanitic, light gray, forms persistent scarp 180 ft above base; light yellowish gray; weathers light gray with poor fissility; marine megafossils scarce. Thickness 300+/-ft.

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1970, Geologic atlas of Texas, Waco Sheet; Lloyd
   William Stephenson memorial edition: University of Texas-Austin,
   Bureau of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k	East Texas basin Gulf Coast basin Ouachita folded belt province	Clay

Summary:
Is Upper Cretaceous formation mapped undivided with overlying Neylandville Formation (Upper Cretaceous) in southwest-northeast trending belt in east-central part of map sheet north of Pond Creek in northern Milam Co., TX (Gulf Coast basin); in central Falls, west-central Limestone, and south-central Navarro Cos., TX (East Texas basin); and in easternmost McLennan and Hill Cos., TX (Ouachita tectonic belt province). Overlies Pecan Gap Chalk (Upper Cretaceous) as far north as vicinity of Munger, northern Limestone Co., TX and overlies Wolfe City Formation (Upper Cretaceous) northward; overlain by Neylandville Formation. Neylandville and Marlbrook ("upper Taylor marl") are not described separately; undivided map unit described as clay, dominantly montmorillonitic, silt-size quartz becomes more abundant upward, calcite fragments common, glauconitic, disseminated pyrite, blocky with conchoidal fracture, strikingly uniform throughout, light medium gray, weathers light brown to light gray and becomes slightly fissile; about 450 ft thick. Neylandville and Marlbrook are not described separately; undivided map unit described as clay, dominantly montmorillonitic, silt-size quartz becomes more abundant upward, calcite fragments common, glauconitic, disseminated pyrite, blocky with conchoidal fracture, strikingly uniform throughout, light medium gray, weathers light brown to light gray and becomes slightly fissile; about 450 ft thick. Kemp Clay, Neylandville, and Marlbrook are mapped undivided near southern edge of map south of Pond Creek in southern Falls, northern Milam, and eastern Bell Cos., TX.

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1972, Geologic atlas of Texas, Dallas Sheet; Gayle
   Scott memorial edition: University of Texas-Austin, Bureau
   of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k	East Texas basin Ouachita folded belt province	Clay

Summary:
Is Upper Cretaceous formation mapped in generally continuous north-south trending belt in eastern part of map sheet. Is mapped separately in southeastern Collin Co, TX (Ouachita tectonic belt province) and Rockwall Co, TX (East Texas basin). Is mapped undivided with overlying Neylandville Formation (Upper Cretaceous) south of Rockwall Co, TX in western Kaufman, eastern Ellis, and central Navarro Cos, TX (East Texas basin). Overlies Wolfe City Sand (Upper Cretaceous) throughout most of mapped extent; overlies "Pecan Gap Chalk?" locally northeast of Rockwall, TX along Collin Co-Rockwall Co line. Marlbrook ("upper Taylor marl") described as clay, calcareous, variable amount of silt and glauconite, silt content increases upward, disseminated pyrite, locally phosphate nodules and phosphatized marine megafossils, blocky, conchoidal fracture, light to dark gray; weathers light gray with poor fissility; marine megafossils; thickness 350+/-ft.

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1974, Geologic atlas of Texas, San Antonio Sheet;
   Robert Hamilton Cuyler memorial edition: University of
   Texas-Austin, Bureau of Economic Geology, 1 sheet, scale
   1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Areal limits Mapped 1:250k	Ouachita folded belt province Gulf Coast basin

Summary:
Is Upper Cretaceous formation mapped undivided with Navarro Group in central Bexar Co, TX (Ouachita tectonic belt province) and northwestern Guadalupe Co, TX (Gulf Coast basin). Is not mapped west of Bexar Co; Escondido Formation is mapped westward. Overlies and is in fault contact with Pecan Gap Chalk (Upper Cretaceous) throughout most of mapped extent, overlies and is in fault contact with Anacacho Limestone (Upper Cretaceous) in western Bexar Co; overlain by Navarro Group (Upper Cretaceous). Also known as "upper Taylor marl." Lower part of map unit [presumably the Marlbrook] described as clay, dominantly montmorillonitic, unctuous, greenish gray to brownish gray; weathers to a very thick, black, clayey soil; thickness about 400 ft.

Summary of Citation: Marlbrook

Publication:
Barnes, V.E., 1974, Geologic atlas of Texas, Seguin Sheet; Donald
   Clinton Barton memorial edition: University of Texas-Austin,
   Bureau of Economic Geology, 1 sheet, scale 1:250,000

Usage in Publication:
Marlbrook Marl

Modifications:	Geologic Province:	Dominant Lithology:
Mapped 1:250k	Gulf Coast basin Ouachita folded belt province	Clay

Summary:
Is Upper Cretaceous formation mapped collectively with Navarro Group in northwestern part of map sheet in broad southwest-northeast trending belt in northern Guadalupe and western Caldwell Cos, TX (Gulf Coast basin) and southeast Hays Co, TX (Ouachita tectonic belt province). Overlies Pecan Gap Chalk (Upper Cretaceous); overlain by Navarro Group (Upper Cretaceous). Also known as "upper Taylor marl." Lower part of map unit [presumably the Marlbrook] described as clay, strikingly uniform throughout, dominantly montmorillonitic, silt-size quartz becomes more abundant upward, calcite fragments common, glauconitic, disseminated pyrite, blocky with conchoidal fracture, light medium gray; weathers light brown to light gray and becomes slightly fissile; thickness of collective map unit about 600 ft.

Summary of Citation: Marlbrook

Publication:
Liddicoat, J.C., Hazel, J.E., Brouwers, E.M., Bryant, W.A. and
   Bottjer, D.J., 1981, Magnetostratigraphy of Upper Cretaceous
   deposits in southwestern Arkansas and northeastern Texas
   [abs.]: American Association of Petroleum Geologists Bulletin,
   v. 65, no. 4, p. 764-765

Usage in Publication:
Marlbrook Marl*

Modifications:	Geologic Province:	Dominant Lithology:
Paleomagnetics	Arkla basin

Summary:
Paleomagnetic (a.f. demagnetized) data indicates the Upper Cretaceous Marlbrook Marl in the Arkla basin in southwest AR possesses a weak remnant magnetization of normal magnetic polarity. The normal polarity is assumed to be primary magnetization, and is interpreted to represent deposition during the Gubbio (Italy) normal polarity zone B+ (Campanian to early Maestrichtian).