Research Paper GEOSPHERE U-Pb detrital zircon geochronology of the Upper Paleocene to Lower Eocene Wilcox Group, east-central Texas GEOSPHERE; v. 12, no. 5 Preston J. Wahl*, Thomas E. Yancey, Michael C. Pope, Brent V. Miller, and Walter B. Ayers Department of Geology and Geophysics, Texas A&M University, College Station, Texas 77843, USA doi:10.1130/GES01313.1 12 figures; 4 supplemental files ABSTRACT INTRODUCTION CORRESPONDENCE: pjwahlgeo@ gmail .com Arrival of Laramide uplift sediments to the Texas Gulf Coastal Plain and Upper Paleocene and Lower Eocene strata comprising the Wilcox Group northwestern Gulf of Mexico during the early Paleogene is recorded in strata and overlying Claiborne Group occur along the Gulf Coastal Plain from south- CITATION: Wahl, P.J., Yancey, T.E., Pope, M.C., of the Wilcox Group as a significant increase in sediment accumulation and western Texas to central Alabama. Wilcox Group and Claiborne Group strata Miller, B.V., and Ayers, W.B., 2016, U-Pb detrital zircon geochronology of the Upper Paleocene to with the appearance of 65–52 Ma detrital zircons that correspond with the are an important economic resource in the Texas Gulf Coastal Plain and north- Lower Eocene Wilcox Group, east-central Texas: timing of late Laramide uplift. New U-Pb dating of detrital zircons by laser western Gulf of Mexico. Both groups contain important aquifers (Thorkildsen Geosphere, v. 12, no. 5, p. 1517–1531, doi: 10 .1130 ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) for and Price, 1991), and the east-central Texas region contains a significant per- /GES01313.1. samples obtained from the Lower Paleocene Tehuacana Member through centage of total Texas Wilcox Group lignite coal reserves (Kaiser et al., 1980). the Lower Eocene Queen City Formation in east-central Texas identifies the Additionally, deep-water amalgamated channel systems and associated de- Received 8 January 2016 Revision received 31 May 2016 Hooper Formation of the Wilcox Group as the oldest stratigraphic unit to posits of the Wilcox Group equivalent are important hydrocarbon targets in Accepted 28 July 2016 contain 65–52 Ma ages. Late appearance of 65–52 Ma detrital zircons in the the northwestern Gulf of Mexico (Meyer et al., 2005). These resources have Published online 23 August 2016 Hooper Formation is correlated with unroofed Laramide magmatic intrusions made Paleocene and Eocene strata subject to various geologic studies, includ- or nearly syndepositional volcaniclastic sources; whereas older detrital zir- ing those related to sedimentary provenance (Hutto et al., 2009; Mackey et al., cons are inferred to be derived primarily from sedimentary cover and base- 2012). Previous U-Pb age dating of detrital zircons from Paleocene and Eocene ment rocks exposed during uplift of Laramide blocks. strata along the northwestern Gulf Coastal Plain includes areas in south Texas Stratigraphic River Sample Location DescriptionLatitude/Longitude Sampling Level System Potential source region and Gulf Coastal Plain detrital zircon data sup- (Mackey et al., 2012), east-central Texas (Hutto et al., 2009), central Louisiana Queen City Buffalo South, Rt. 79 roadcut near pond, 6 km SW 31.405461°N; base Navasota Fm of I-45 at Buffalo, Leon Co., TX 96.111382°W port a relatively similar paleodrainage area and sediment sources for east- (Craddock and Kylander-Clark, 2013), and a regional study extending from Cart Path on Pine Forest golf course, 90 m north of 30.073912°N; Carrizo Fm fluvial base Colorado River, 4.5 km from Rts.21-71 intersection, Colorado 97.281754°W Tahitian Village, Bastrop Co., TX central Texas Tehuacana Member to Carrizo Formation and central Louisiana southwestern Texas to central Alabama (Blum and Pecha, 2014). This study ad- Big Brown mine, NE end, N side Rt. 2570, west Calvert Bluff 31.838566°N; mid side Trinity River, 16 km NE of Fairfield, Freestone Trinity Fm 96.050466°W Co., TX Wilcox Group data, and for east-central Texas Queen City Formation and vances efforts to further characterize these strata along the Gulf Coastal Plain Black Shoals, Brazos River, 0.4 km SW of Rt. 979 Calvert Bluff 30.976752°N; base bridge, east side of river, 8.4 km due west of Brazos Fm 96.760524°W central Louisiana middle-upper Claiborne Group data. South Texas Wilcox by providing U-Pb age data for 12 sandstone samples from closely spaced Calvert, Robertson Co., TX Thornton quarry, south side Rt. 1246, 6 km SE of 31.386536°N; Simsboro Fm high Navasota Group data contrast with data from these samples and support a differ- stratigraphic horizons in east-central Texas. Samples were obtained from lo- Thornton, Limestone Co., TX 96.509098°W Kosse mine (U. S. Silica), east side of Rt. 2749, 1.3 ent paleodrainage area and sediment sources for the south Texas region. cations between Bastrop and Freestone Counties of east-central Texas where 31.295041°N; Simsboro Fm top km north of Rts.7 and 2749 intersection, 11.6 km Navasota 96.508852°W ESE of Kosse, Limestone Co., TX We propose that headwaters sourced from southeastern Wyoming to the strata crop out in and in close proximity to the Colorado, Brazos, and Trinity Luminant pit, 0.6 km west of Rt. 2749, 1.1 km NW 31.314138°N; Simsboro Fm mid of Kosse U.S. Silica mine plant, 10.8 km due east Navasota 96.516782°W of Kosse, Limestone Co., TX southern Rocky Mountain region delivered sediments to east-central Texas River Valleys (Figs. 1 and 2), all of which are located in the Houston embay- Rt. 14 roadcut, east side of road, 160 m SW of Rt. 31.223429°N.; Simsboro Fm low 276 intersection to the east, 9.5 km SW of Kosse, Brazos 96.649808°W Limestone Co., TX and central Louisiana during the Paleocene to Middle Eocene. Pronounced ment structural basin. Sandstone samples are from the Lower Paleocene Mesoproterozoic and Neoproterozoic detrital zircons in the lower Claiborne Tehua cana Member at the top of the Kincaid Formation of the Midway Group 1Supplemental Item 1. East-central Texas sample Group of east-central Texas and the middle-upper Claiborne Group of cen- to the Lower Eocene Queen City Formation of the lower Claiborne Group. location details. Please visit http:// dx .doi .org /10 1 .1130 /GES01313 .S1 or the full-text article on www tral Louisiana are attributed to new or unroofed recycled sediments with Sample location details are available in Supplemental Item 1. .gsapubs .org to view Supplemental Item 1. Grenvillian age detrital zircons incorporated from the Ouachita region and Sediment delivery to the Texas Gulf Coastal Plain and northwestern Gulf of other proximal locations in the preexisting paleodrainage area. The inferred Mexico during the early Paleogene is characterized by a substantial increase of paleodrainage area for east-central Texas and central Louisiana includes clastic sediment volume during the Late Paleocene, followed by an overall de- most of the Rocky Mountain Laramide uplift blocks, has a southern bound- cline of sediment delivery until the Late Eocene (Galloway and Williams, 1991; ary separating it from a south Texas paleodrainage, and an eastern boundary Galloway et al., 2011). Wilcox Group and lower Claiborne Group sediments roughly coincident with the Mississippi embayment, which separates it from were deposited during a phase of clastic sediment delivery representing the Appalachian Mountains drainages. first and greatest Paleogene cycle of tectonic-influenced deposition (Winker, For permission to copy, contact Copyright 1982). This phase corresponds with timing of late Laramide orogenesis (Cather Permissions, GSA, or [email protected]. *Current address: 6900 Lake Woodlands Drive, #1111, The Woodlands, Texas 77382, USA and Chapin, 1990; Lawton, 2008) and continued development of the Western © 2016 Geological Society of America GEOSPHERE | Volume 12 | Number 5 Wahl et al. | U-Pb detrital zircon geochronology of the Wilcox Group Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/5/1517/3336567/1517.pdf 1517 by guest on 29 September 2021 Research Paper Rusk 102°W 100°W Hill Navarro Cherokee Bosque 5 36°N 98°W 96°W Waco 34°N 94°W 1 4 7 Houston 106°W 104°W Coryell 4 Leon 32°N 3 4 4 Falls Trinity Robertso Bell 3 n 30°N 5 Madison Polk Walker Milam 28°N B/CS ~500 km Williams Grimes on J acinto 26°N Burleson Austin Lee Liberty Lower and Middle Bastrop Washington Claiborne Group 2 Wilcox and 6 Fayette Austin Harris Midway Groups Houston Sample Location N Caldwell Fort Bend ~50 km Gonzales Figure 1. Location of east-central Texas samples collected from areas between the Trinity and Colorado Rivers. County names are listed, and major cities are indicated by black squares. B/CS— Bryan/College Station. Blue outlines indicate major rivers. Bold black lines and shield symbols denote major interstate highways (I-10, I-35, and I-45). Extent of Midway Group, Wilcox Group, and Claiborne Group after Stoeser et al. (2005). Sample location numbers: 1—Tehuacana Member; 2—Seguin Formation; 3—Hooper Formation; 4—Simsboro Formation; 5—Calvert Bluff Formation; 6—Carrizo Formation; 7—Queen City Formation. Cordillera (DeCelles, 2004). Extended sediment deposition on the margins of cox Group strata reported similar young detrital zircon ages (62–54 Ma) from the Gulf of Mexico resulted in an overall transition from open marine shelf the Mississippi embayment to south-central Texas (Blum and Pecha, 2014). settings during the Early Paleocene to nonmarine settings by the Oligocene, However, much of these data in east-central Texas are derived from undiffer- modulated by variation of sediment supply, subsidence, and eustatic sea level entiated Wilcox Group strata, with the Simsboro Formation being the oldest (Yancey and Davidoff, 1991; Davidoff and Yancey, 1993).