Detrital Zircons from Crystalline Rocks Along the Southern Oklahoma Fault System, Wichita and Arbuckle Mountains, USA GEOSPHERE; V

Research Paper

GEOSPHERE Detrital zircons from crystalline rocks along the Southern Oklahoma fault system, Wichita and Arbuckle Mountains, USA GEOSPHERE; v. 12, no. 4 William A. Thomas1,*, George E. Gehrels2, and Mariah C. Romero3 1Geological Survey of Alabama, Tuscaloosa, Alabama 35486, USA doi:10.1130/GES01316.1 2Department of Geosciences, University of Arizona, Tucson, Arizona 85721, USA 3Department of Earth, Atmospheric, and Planetary Sciences, Purdue University, West Lafayette, Indiana 47907, USA 8 figures; 2 supplemental files ABSTRACT tia and opening of the Iapetus Ocean during final breakup of supercontinent CORRESPONDENCE: geowat@uky.edu Rodinia (Hogan and Gilbert, 1998; Thomas et al., 2012; Hanson et al., 2013). Detrital zircons with ages of 535 ± 10 Ma in many North American Mid- A thick post-rift, Cambrian–Ordovician, passive-margin carbonate succession CITATION: Thomas, W.A., Gehrels, G.E., and continent sandstones are commonly attributed to sources in Cambrian syn- covered the Cambrian igneous rocks and associated Mesoproterozoic base- Romero, M.C., 2016, Detrital zircons from crystalline rocks along the Southern Oklahoma fault system, rift igneous rocks along the Southern Oklahoma fault system. New analyses ment rocks (Denison, in Johnson et al., 1988). Late Paleozoic basement-rooted Wichita and Arbuckle Mountains, USA: Geosphere, are designed to test the characteristics of proximal detritus from the Wichita uplifts (Wichita and Arbuckle) along the Southern Oklahoma fault system v. 12, no. 4, p. 1224–1234, doi:10.1130/GES01316.1. and Arbuckle uplifts. Detrital zircons from a sandstone (Lower Permian Post incorporated the Cambrian igneous rocks and Precambrian basement rocks Oak Conglomerate) directly above an unconformable contact with the Wichita (Fig. 1). Unroofing of the Wichita and Arbuckle uplifts and Pennsylvanian– Received 21 January 2016 Granite Group in the Wichita Mountains have strongly unimodal U-Pb ages Permian stratigraphic onlap rimmed the Southern Oklahoma fault system with Revision received 19 April 2016 Accepted 17 May 2016 of 540–520 Ma and εHft values of +4.7 to +10.1. In contrast, two sandstone proximal clastic deposits, including the classic “Granite Wash” from the crys- Published online 1 July 2016 samples (Upper Pennsylvanian Vanoss Conglomerate) in the onlapping suc- talline rocks (Johnson et al., 1988). cession above an angular unconformity on Paleozoic strata on the flank of the Gondwanan accreted terranes, which are distributed along the late Paleo- Arbuckle anticline have detrital zircons with U-Pb ages that correspond domi zoic Appalachian-Ouachita orogenic belt, include Brasiliano–Pan-African and nantly to the Superior (~2700 Ma) and secondarily to the Granite-Rhyolite Pampean components, the ages of which range through 700–530 Ma (Lopez (1480–1320 Ma) and Grenville (1300–970 Ma) provinces of the Laurentian cra- et al., 2001; Mueller et al., 2014). The accreted terranes offer an alternative ton. The Vanoss zircons indicate recycling from quartzose sandstones within source of ~535 Ma zircons, which are not distinguishable from zircons of the the Middle Ordovician platform carbonates in the Arbuckle passive-margin Southern Oklahoma igneous rocks on the basis of age alone. cover succession. A stratigraphically higher sandstone (Permian Wellington In order to characterize the detritus from the Southern Oklahoma prove- Formation) above the onlapping conglomerates has a more diverse detrital- nance, new samples of proximal Pennsylvanian and Permian sandstones along zircon population, indicating that sediment dispersal from external sources the uplifts were analyzed for U-Pb ages and Hf isotopes of detrital zircons. overwhelmed the proximal detritus in the immediate cover of the Wichita and Analyses of detrital zircons from a Permian sandstone stratigraphically above

Arbuckle uplifts. The distinctive εHft values of the proximal detritus from the the proximal detritus were conducted to test sediment dispersal in space and Cambrian synrift igneous rocks offer potential discrimination from zircons of time, as well as to document the early evolution of sediment-dispersal systems the same age from Gondwanan accreted terranes, which are represented in around the Southern Oklahoma (Wichita and Arbuckle) uplifts. Ultimately, the Wellington sample. these results may provide a basis for discrimination of the Southern Oklahoma provenance from Gondwanan accreted terranes. INTRODUCTION GEOLOGIC SETTING AND EVOLUTION OF THE Detrital zircons with ages of 535 ± 10 Ma, although generally not abun- SOUTHERN OKLAHOMA FAULT SYSTEM dant, are common in many Paleozoic sandstones across the North American Midcontinent, and almost universally are attributed to a source in the well- Mesoproterozoic Basement Rocks known Cambrian igneous rocks along the Southern Oklahoma fault system (e.g., Riggs et al., 1996; Dickinson and Gehrels, 2003, 2008; Gleason et al., 2007; Basement rocks in the Arbuckle uplift belong to the Southern Granite-Rhyo Soreghan and Soreghan, 2013). Emplacement of the Cambrian (539–530 Ma) lite province (Fig. 1) (e.g., Ham et al., 1964; Van Schmus et al., 1993). U-Pb synrift magmas accompanied the late stages of rifting of southeastern Lauren- zircon ages for various granites and gneisses in the Arbuckle uplift range from For permission to copy, contact Copyright 1399 ± 95 and 1397 ± 7 Ma to 1364 ± 2 and 1363 ± 8 Ma (Bickford and Lewis, Permissions, GSA, or [email protected]. *Professor Emeritus at University of Kentucky; Visiting Scientist at Geological Survey of Alabama 1979; Thomas et al., 1984; Rohs and Van Schmus, 2007; Thomas et al., 2012).

GEOSPHERE | Volume 12 | Number 4 Thomas et al. | Detrital zircons, Southern Oklahoma Wichita-Arbuckle uplifts Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/12/4/1224/4178158/1224.pdf 1224 by guest on 25 September 2021 Research Paper

continental crust (Keller and Stephenson, 2007). The Cambrian igneous rocks 100°W 90°W 80°W are interpreted to be along a system of intracratonic fractures associated with Superior 50°N continental rifting and breakup of supercontinent Rodinia and opening of the 50°N >2400 Ma Iapetus Ocean (Fig. 1) (e.g., Thomas, 2006, 2014). Data from U-Pb analyses of zircons from the igneous rocks give a range of possible ages for detrital zircons available from this provenance. U-Pb ages of zircons from rhyolites in the Wichita Mountains bracket a short time interval Midc. 1100 Ma of 533–530 Ma (Wright et al., 1996; Hogan and Gilbert, 1998; Hanson et al., Trans-Hudson 2000–1800 Ma 2013). A U-Pb zircon age of 552 ± 7 Ma for gabbro (Bowring and Hoppe, 1982) is older than indicated by geologic relationships to other dated rocks and may 45°N have an inherited component (Hogan and Gilbert, 1998; Hanson et al., 2013). Penokean a U-Pb ages of zircons from rhyolites in the Arbuckle Mountains are 539 ± 5 and 1900–1800 Ma MMa 7 536 ± 5 Ma (Thomas et al., 2012). Previously determined U-Pb zircon ages of 997 ––9 525 ± 25 Ma for rhyolite and granite (Tilton et al., 1962) are within error of the Central Plains 00–9 GrenvilleG 00 more recent data. Some components of the igneous suite are older on the 1800–1650 Ma 1300–970 Ma basis of geologic relationships than the geochronologically dated rocks; how- 40°N ever, no data are available to quantify the time span of those rocks. Combining all of the available U-Pb data, zircons with ages of 539–530 Ma and possibly somewhat older are available to the supply of sediment from the Southern Oklahoma synrift igneous rocks. Granite-Rhyolite S.O. 539–530OK Ma 1480–1320 Ma Cambrian–Ordovician Passive-Margin Carbonate Succession 35°N

A transgressive passive-margin succession of basal sandstone and over- ) a lying shallow-marine carbonates onlaps the Cambrian igneous rocks along MaM the Southern Oklahoma fault system. Cambrian–Ordovician rocks along the 3 535 Southern Oklahoma fault system are part of a craton-wide passive-margin car- Llano-Grenville 30°N bonate (referred to as the Great American Carbonate Bank, Derby et al., 2012). 1300–1000 Ma 30°N n The age of the sandstone at the base of the transgressive succession is middle 0 500 kmm Late Cambrian; and the overlying carbonate succession extends up through L the Middle Ordovician (Denison, in Johnson et al., 1988). The Middle Ordovi- 100°W Iapetanf L rift95°W margin 90°W 85°W ofo Laurentia (~530 Ma cian part of the carbonate succession includes mature quartzose sandstone. Figure 1. Regional map of Precambrian provinces of interior North America (modified from Van The carbonate succession is exceptionally thick (as much as 2.2 km) along Schmus et al., 1993), Iapetan rift margin and synrift intracratonic faults of Laurentia (from Thomas, the Southern Oklahoma fault system, consistent with large-magnitude synrift 2014), and location of Cambrian igneous rocks (539–530 Ma) along the synrift Southern Oklahoma thermal uplift followed by post-rift cooling and deep subsidence (Thomas and fault system. Black dots in Oklahoma (OK) show locations of samples for analysis of detrital zircons. Abbreviations: Midc.—Midcontinent rift system; S.O.—Southern Oklahoma fault system. Astini, 1999).

Cambrian Synrift Igneous Rocks Late Paleozoic Uplifts and Clastic Sedimentary Rocks

Along the Southern Oklahoma fault system (Arbuckle and Wichita uplifts), A relatively thin, unconformity-punctuated, heterolithic, Upper Ordovician– a Cambrian bimodal suite of plutonic and volcanic rocks includes gabbro, ba- Mississippian succession overlies the thick Cambrian–Ordovician carbonate salt, granite, and rhyolite (Hogan and Gilbert, 1998; Hanson et al., 2013), the succession, representing deposition on a stable continental shelf (Johnson composition of which indicates magma sources in the upper mantle. High- et al., 1988). In contrast, a very thick, dominantly clastic succession of Pennsyl- amplitude, short-wavelength gravity and magnetic anomalies indicate a nar- vanian–Permian age reflects the rise of multiple components of the Arbuckle row, elongate mass of dense mafic rocks with steep boundaries in the shallow and Wichita uplifts along large-magnitude basement faults (Johnson et al.,

OKLAHOMA

95°W EXPLANATION 36°N

Mississippian– Figure 2. Map of pre-Pennsylvanian outcrop geology of the Wichita and Arbuckle Cambrian strata uplifts along the Southern Oklahoma fault system (location of state of Oklahoma synrift igneous Wichita uplift shown in Fig. 1). Map shows location of Figure 3 sample OK-4-WL; locations of other sam- rocks (539–530 Ma) ples are shown in Figures 3 and 4. Figure 4 Arbuckle uplift t crystalline basement rocks (1400–1360 Ma) Ouachita thrust bel 34°N OK-4-WL 100°W 34°23′25.9″N n 97°24′48.1″W 0 200 km Gulf Coastal Plai

1988; Denison, 1989; Perry, 1989). Erosion of the rising uplifts led to unroof- OK-10-PO1 ing of the sedimentary cover and basement rocks, as well as set the stage for 34°43′27.7″N A ultimate sedimentary onlap onto the eroded uplifts in the later Pennsylvanian 98°28′11.1″W and Permian.

N SANDSTONE SAMPLES FOR ANALYSIS OF DETRITAL ZIRCONS A′ Collections were designed to sample the most proximal sandstones on the A Arbuckle and Wichita uplifts, as well as a stratigraphically higher level to test A′ 02 km for temporal and lateral extent of supply of sediment from the uplifts. One sample of Lower Permian Post Oak Conglomerate came from a pebbly sandstone ~10 cm above the unconformable contact with the underlying Mount Sample site Scott Granite of the Cambrian Wichita Granite Group along the south side of EXPLANATION the Wichita uplift (Figs. 2 and 3). Two samples of the Upper Pennsylvanian Post Oak Conglomerate Vanoss Conglomerate were collected on the north side of the Arbuckle up- and equivalent units lift (Figs. 2 and 4), stratigraphically above the onlap of Pennsylvanian clastic facies onto the Ordovician carbonate succession. The Vanoss Conglomerate Wichita Granite Group contains carbonate clasts in the sandstone matrix. One sample came from the stratigraphically higher Permian Wellington Formation ~40 m above the level Figure 3. Geologic map (adapted from Stanley and Miller, of the Vanoss Conglomerate west of the Arbuckle uplift (Fig. 2). The Wellington 2005) and diagrammatic cross section of outcrops of the Wichita Granite Group and onlapping Lower Permian Post is part of a succession of more blanket-like stratigraphic units deposited across Oak Conglomerate in the Wichita uplift (location of map the then-inactive Southern Oklahoma fault system. shown in Fig. 2). Location of sample OK-10-PO1.

OK-2-V2 A′ 34°29′29.5″N 97°02′06.0″W OK-1-VN 34°28′50.4″N 97°02′15.4″W

Arbuckle anticline

A 0 5 km EXPLANATION A A′ Upper Pennsylvanian and Lower Permian coarse clastic succession, onlap on Arbuckle uplift UNCONFORMITY Upper Middle Ordovician to Middle Pennsylvanian SAMPLE LOCATIONS new data reported herein Lower Middle Ordovician limestone and sandstone data from Pickell (2012) Bromide Fm.—limestone, sandstone interbeds

Tulip Creek Fm.—sandstone, limestone interbeds p McLish Fm.—sandstone and limestone Grou son

Figure 4. Geologic map (generalized from 1954 map by Ham and Oil Creek Fm.—sandstone, limestone interbeds p m McKinley et al., and revised by Johnson, 1990) and cross section Joins Fm.—limestone, shale Si (vertical exaggeration ~10×) of Arbuckle uplift (location of map Upper Cambrian and Lower Ordovician shown in Fig. 2). Locations of samples OK-1-VN and OK-2-V2. Map carbonate rocks, basal sandstone unit of lower Middle Ordovician limestone and sandstone forma- Cambrian Colbert (Carlton) Rhyolite (539–536 Ma) tions includes sandstones analyzed by Pickell (2012) and interpreted to be the source of recycled zircons in the Vanoss Conglomerate. Precambrian crystalline basement rocks (1400–1360 Ma)

METHODS Between 306 and 344 analyses were conducted on each sample with one U-Pb measurement per grain. Grains were selected in random fashion; crys- U-Pb Geochronologic Analysis tals were rejected only on the basis of small size or the presence of cracks or inclusions. The use of high-resolution, backscattered-electron (BSE) images for U-Pb geochronology of zircon crystals was conducted by laser ablation– detrital samples provided assistance in grain selection and spot placement. inductively coupled mass spectrometry (LA-ICPMS) at the Arizona LaserChron Data reduction included (1) subtraction of 204Hg based on the measured Center (www.laserchron.org) using methods described by Gehrels et al. (2008) 202Hg and the natural 202Hg/204Hg; (2) subtraction of initial Pb based on the mea- and Gehrels and Pecha (2014). U-Pb analyses were conducted with a Pho- sured 206Pb/204Pb, using Stacey and Kramers (1975) to determine the composi- ton Machines Analyte G2 excimer laser (l = 193 nm) coupled to a Thermo tion of common Pb and Mattinson (1987) for an estimate of the compositional Element2 ICPMS. Analyses were conducted with a 20-micron beam diameter, uncertainty; (3) calibration of 206Pb/238U and 206Pb/207Pb fractionation based on which excavated a pit of 12 microns depth during a ~30 second analysis (8 sec- bracketed (5:1) analyses of FC-1 (primary standard) and SL-F and R33 (seconds on backgrounds, 12 seconds on peaks, and 10 seconds for washout). ondary standards); (4) calculation of ages utilizing decay constants of Steiger

and Jager (1977) and 238U/235U of Hiess et al. (2012); (5) propagation of internal Vanoss Conglomerate uncertainties from measurement of isotope ratios and a small overdispersion factor; and (6) propagation of all external uncertainties (including fractionation Both samples of Vanoss Conglomerate have dominant concentrations (~48% calibration, age of the primary standard, common Pb composition, and decay of total grains) of detrital zircons between 2860 and 2620 Ma with probability constants) (Horstwood et al., 2016). peaks at 2710 and 2708 Ma (Fig. 5). Both samples have two secondary concen- For interpretation, U-Pb data are filtered to exclude ages with >20% dis- trations, in the ranges of 1520–1300 Ma and 1240–970 Ma (Fig. 5). Both samples cordance, >5% reverse discordance, >10% uncertainty, or high common Pb. have minor components with ages of 1910–1760 Ma and 1710–1580 Ma (Fig. 5). Data are presented on normalized age-probability diagrams, which sum all One sample has two grains with ages of 563 and 525 Ma (Fig. 5). The samples relevant analyses and uncertainties and then divide by the number of analyses have a few younger grains (nine grains total) with ages of 437–375 Ma (Fig. 5). such that each curve contains the same area. Age groups are characterized by Hafnium analyses of one of the two Vanoss samples (Fig. 5) show juvenile to

the ages of peaks in age probability. Complete U-Pb isotopic data, including intermediate eHft values that are typical for Precambrian cratonal provinces of the concordia and age-probability plots for each sample, are presented in Supple- central United States (Gehrels and Pecha, 2014). The younger grains also yield 1 mental Table 1. juvenile to intermediate eHft values but not as juvenile as the Post Oak zircons.

Hafnium Isotopic Analysis Wellington Formation

Hafnium isotopic analyses were determined using methods described by The detrital-zircon population of the Wellington Formation contrasts mark- Cecil et al. (2011) and Gehrels and Pecha (2014) utilizing a Photon Machines Ana edly with those of both the Post Oak Conglomerate and Vanoss Conglomerate. lyte G2 excimer laser (l = 193 nm) coupled to a NU multicollector HR ICPMS. Two groups of ages dominate the Wellington zircons: 1340–960 Ma with peaks

DR Table 1. Zircon U-Pb geochronologic analyses by Laser-Ablation Multicollector ICP Mass Spectrometry Isotope ratios Apparent ages (Ma) Between 18 and 65 analyses were conducted per sample; analysis spots were at 1326, 1151, and 1040 Ma; and 673–329 Ma with peaks at 563, 437, and 339 Ma Analysis U206Pb U/Th206Pb*±207Pb* ±206Pb*±error206Pb*± 207Pb* ±206Pb*±Best age± Conc (ppm)204Pb 207Pb* (% 2σ)235U* (% 2σ)238U(% 2σ)corr. 238U*(Ma 2σ)235U(Ma 2σ)207Pb*(Ma 2σ) (Ma)(Ma 2σ)(%)

Sample OK-10-PO1—Post Oak Conglomerate—34° 43' 27.7'' N, 98° 28' 11.1'' W OK-10-PO1-151180 35251 1.717.9313 3.40.52403.6 0.0682 1.10.32425.0 4.7427.8 12.5 443.175.6425.0 4.795.9 located on top of the U-Pb pit in an attempt to link the Hf and U-Pb data. A (Fig. 5). Smaller numbers of zircons are scattered at 2904–2305, 2062–1359, OK-10-PO1-28529613 1.013.3861 30.1 0.7294 30.6 0.0708 5.40.18441.0 23.1 556.2131.8 1060.6619.9 441.023.141.6 OK-10-PO1-16484397 1.213.3544 33.8 0.7757 34.8 0.0751 8.40.24467.0 37.9 583.0155.7 1065.3699.3 467.037.943.8 OK-10-PO1-153176 6101.6 14.690114.70.725315.90.07736.2 0.39 479.828.7553.8 68.1 870.8305.7 479.828.755.1 OK-10-PO1-3157638141.0 16.00456.0 0.6770 7.00.07863.5 0.51 487.616.6524.9 28.5 690.7127.8 487.616.670.6 OK-10-PO1-28 56 1366 0.916.3468 8.90.67599.3 0.0801 2.70.29496.9 12.9 524.338.2645.4 192.2496.9 12.9 77.0 OK-10-PO1-25 15314191.1 16.43545.5 0.6868 5.60.08190.9 0.17 507.34.5 530.923.0633.8 118.2507.3 4.580.0 40-micron beam diameter was used for an 80 second acquisition (20 seconds and 857–728 Ma (Fig. 5). Hafnium analyses are similar to the results from the OK-10-PO1-18329925 1.616.0647 15.4 0.7046 15.7 0.0821 3.20.21508.6 15.8 541.566.1682.6 330.2508.6 15.8 74.5 OK-10-PO1-1107916311 1.516.6154 10.6 0.6822 13.9 0.0822 9.00.65509.3 43.9 528.157.2610.2 229.2509.3 43.9 83.5 OK-10-PO1-3476211893 1.216.4149 7.20.69257.4 0.0824 1.80.24510.7 8.7534.3 30.9 636.4155.5 510.78.7 80.2 OK-10-PO1-1173492121.6 16.17759.4 0.7061 12.8 0.0828 8.70.68513.1 43.0 542.454.0667.7 202.2513.1 43.0 76.8 OK-10-PO1-1446524171.3 17.03384.0 0.6716 4.70.08302.4 0.52 513.812.0521.7 19.1 556.387.7513.8 12.0 92.4 OK-10-PO1-2546633751.7 17.10404.5 0.6697 4.90.08311.9 0.39 514.59.6 520.520.1547.2 99.1 514.59.6 94.0 on backgrounds, 40 seconds on peaks, and 20 seconds for washout). Vanoss Conglomerate, except that Hf values for 600–500 Ma grains extend to OK-10-PO1-2303049721.6 14.928514.30.769416.50.08338.4 0.50 515.841.4579.4 73.2 837.3299.0 515.841.461.6 e t OK-10-PO1-2043113522 1.317.1700 10.8 0.6690 11.0 0.0833 2.00.18515.9 9.8520.1 44.6 538.8236.3 515.99.8 95.7 OK-10-PO1-257101 6767 1.515.2142 18.8 0.7567 19.0 0.0835 2.00.11517.0 10.1 572.183.1797.7 398.3517.0 10.1 64.8 OK-10-PO1-335151 118561.9 15.696512.40.733512.70.08353.0 0.24 517.015.1558.6 54.8 732.0263.2 517.015.170.6 OK-10-PO1-190102 7011 1.616.9159 2.70.68083.3 0.0835 1.80.55517.1 8.9527.3 13.4 571.459.0517.1 8.990.5 OK-10-PO1-252124 43271 1.216.9393 3.00.68043.2 0.0836 1.10.34517.6 5.5527.0 13.3 568.466.3517.6 5.591.1 OK-10-PO1-80 10648261.9 17.10784.9 0.6740 5.00.08361.0 0.19 517.84.8 523.220.6546.8 108.1517.8 4.894.7 Hafnium data were reduced to achieve minimum offset of the measured more negative values (Fig. 5). OK-10-PO1-07 11228167 1.516.7590 2.30.68882.9 0.0837 1.80.61518.3 8.8532.1 12.1 591.650.3518.3 8.887.6 OK-10-PO1-1794023781.4 16.38766.6 0.7045 6.80.08371.7 0.25 518.38.7 541.528.7640.0 142.3518.3 8.781.0 OK-10-PO1-04 50 19120 1.317.9107 8.10.64648.6 0.0840 2.80.33519.8 14.1 506.334.3445.7 180.9519.8 14.1 116.6 OK-10-PO1-280194 5349 1.316.6711 5.60.69466.2 0.0840 2.60.41519.8 12.8 535.525.7603.0 121.9519.8 12.8 86.2 176 177 OK-10-PO1-274103 6151 1.316.5468 3.70.70024.7 0.0840 2.90.62520.2 14.7 538.919.7619.2 79.7 520.214.784.0 OK-10-PO1-2518512045 1.017.1181 6.40.67696.7 0.0840 2.00.30520.2 9.9524.9 27.6 545.5140.7 520.29.9 95.4 Hf/ Hf of standards relative to the known values. Solution standards in- OK-10-PO1-191136 63714 2.217.1286 2.10.67652.5 0.0840 1.30.54520.2 6.7524.7 10.2 544.145.6520.2 6.795.6 OK-10-PO1-3499550071 1.517.2975 3.40.67093.6 0.0842 1.30.37520.9 6.7521.2 14.8 522.673.9520.9 6.799.7 OK-10-PO1-78 16824710 1.016.8658 2.50.68812.6 0.0842 0.70.28521.0 3.6531.7 10.8 577.854.8521.0 3.690.2 OK-10-PO1-3362128041.9 16.144320.00.718921.40.08427.7 0.36 521.038.5550.0 91.3 672.1432.3 521.038.577.5 OK-10-PO1-3047012068 1.617.3601 4.20.66874.5 0.0842 1.80.39521.1 8.8519.9 18.5 514.792.0521.1 8.8101.2 OK-10-PO1-1845018254 1.617.9203 6.10.64876.4 0.0843 2.10.33521.8 10.5 507.725.8444.5 135.7521.8 10.5 117.4 cluded JMC475 mixed with varying amounts of Lu and Yb; zircon standards OK-10-PO1-2926025244 1.316.6024 6.10.70046.6 0.0843 2.50.38521.9 12.6 539.027.5611.9 131.6521.9 12.6 85.3 OK-10-PO1-06 56 114391.3 18.30417.2 0.6359 7.50.08441.9 0.25 522.49.5 499.829.4397.2 161.7522.4 9.5131.5 OK-10-PO1-317139 7172 1.116.7890 2.30.69332.4 0.0844 0.70.29522.4 3.6534.8 10.1 587.750.4522.4 3.688.9 OK-10-PO1-14 33 6838 1.518.3344 11.1 0.6349 11.4 0.0844 2.30.20522.5 11.6 499.144.9393.5 250.4522.5 11.6 132.8 OK-10-PO1-2075416188 1.216.0971 5.80.72337.6 0.0844 4.90.65522.6 24.8 552.632.4678.3 123.5522.6 24.8 77.0 OK-10-PO1-259199 3117 1.416.5748 3.80.70264.8 0.0845 3.00.62522.7 14.8 540.420.1615.5 81.4 522.714.884.9 OK-10-PO1-20 10920180 1.516.9096 4.00.68904.1 0.0845 1.00.24522.9 4.9532.2 17.1 572.287.4522.9 4.991.4 (included on each mount with the unknowns) included FC1, R33, Temora, DISCUSSION OF RESULTS AND PROVENANCE OK-10-PO1-2103915092 1.718.0491 8.10.64558.2 0.0845 1.50.18522.9 7.3505.7 32.8 428.6180.8 522.97.3 122.0 OK-10-PO1-2823932922.0 14.402022.40.809023.60.08457.3 0.31 522.936.6601.9 107.6911.7 467.7522.9 36.6 57.4 OK-10-PO1-35 38 4899 1.417.3982 11.5 0.6697 11.7 0.0845 2.30.19522.9 11.4 520.547.8509.9 254.0522.9 11.4 102.6 OK-10-PO1-1989112251 1.617.0872 2.30.68222.8 0.0845 1.50.54523.2 7.5528.1 11.4 549.451.1523.2 7.595.2 OK-10-PO1-1463558101.3 18.136211.70.642912.10.08463.0 0.25 523.315.3504.1 48.1 417.8262.3 523.315.3125.2 OK-10-PO1-2535313980 1.517.2731 7.30.67537.7 0.0846 2.40.31523.5 11.9 523.931.3525.7 159.7523.5 11.9 99.6 91500, Mud Tank, and Plesovice. The best fit of standards was achieved with OK-10-PO1-1704525424 1.417.6103 6.60.66257.1 0.0846 2.60.37523.6 13.2 516.128.6483.2 145.3523.6 13.2 108.4 OK-10-PO1-3345928437 1.116.8025 5.70.69455.9 0.0846 1.60.28523.7 8.3535.5 24.6 586.0123.1 523.78.3 89.4 OK-10-PO1-122183 69344 1.317.0660 3.10.68383.2 0.0846 0.60.20523.7 3.2529.1 13.2 552.168.2523.7 3.294.9 OK-10-PO1-2875218771 1.417.6217 5.90.66246.0 0.0847 1.40.23523.9 6.9516.1 24.5 481.8130.1 523.96.9 108.7 OK-10-PO1-3433564081.9 18.16708.9 0.6426 9.20.08472.3 0.25 523.911.5503.9 36.6 414.0199.6 523.911.5 126.5 a 0.4 epsilon unit increase in eHft and utilizing ßHf rather than ßYb for samples Post Oak Conglomerate with <0.7 mv of 171Yb. 1Supplemental Table 1 and accompanying worksheets. Please visit http://dx.doi.org/10 .1130/GES01316.S1 Reported results were determined from all measured isotope ratios, and The single mode (~535 Ma) of detrital-zircon ages in the Post Oak Con- or the full-text article on www.gsapubs.org to view outliers were rejected only using a 2s filter. The resulting uncertainty is 2.6 glomerate (Fig. 5) corresponds to the age of the Cambrian igneous rocks along the Supplemental Files. epsilon units (2s), which, together with the reproducibility of standards zir- the Southern Oklahoma fault system, consistent with a single proximal source cons, yields an external precision of 2–3 epsilon units (2s). Complete Hf iso from the Wichita Granite Group for the onlapping sedimentary cover. Positive

Table-__ . Hf isotopic data. Order Sample(176 Yb + 176 Lu) / 176 Hf (%)Volts Hf 176 Hf/177 Hf ± (1σ) 176 Lu/177 Hf 176 Hf /177Hf (T)E-Hf (0)E-Hf (0) ± (1σ)E-Hf (T)Age (Ma) topic data, including Hf-evolution plots of individual samples, are presented in eHf values (+4.7 to +10.1) for the Post Oak zircons suggest that the magmas 1 OK-10-PO1-208 12.2 3.20.282704 0.000031 0.000739 0.282696 -2.9 1.18.6 525 t 2 OK-10-PO1-153 24.8 1.50.282628 0.000084 0.001449 0.282615 -5.6 3.04.7 480 3 OK-10-PO1-154 20.0 2.20.282719 0.000063 0.001227 0.282706 -2.3 2.29.3 542 4 OK-10-PO1-331 19.8 2.80.282655 0.000038 0.001152 0.282643 -4.6 1.46.9 536 2 5 OK-10-PO1-333 21.1 3.00.282666 0.000050 0.001244 0.282654 -4.2 1.87.2 528 6 OK-10-PO1-161 24.0 1.30.282667 0.000106 0.001524 0.282652 -4.2 3.77.3 540 Supplemental Table 2 ; results are plotted in Figure 5. were generated mainly from juvenile sources, either directly from the mantle 7 OK-10-PO1-164 61.1 2.90.282658 0.000049 0.002899 0.282632 -4.5 1.75.0 467 8 OK-10-PO1-163 30.2 2.90.282678 0.000034 0.001862 0.282659 -3.8 1.27.7 545 9 OK-10-PO1-171 19.8 2.80.282608 0.000048 0.001127 0.282596 -6.3 1.76.0 567 10 OK-10-PO1-226 9.83.2 0.282698 0.000033 0.000569 0.282692 -3.1 1.29.2 561 11 OK-10-PO1-227 11.5 2.70.282683 0.000032 0.000680 0.282676 -3.6 1.18.2 538 or, more likely, from crustal rocks derived from the mantle a short time prior 12 OK-10-PO1-187 17.5 2.70.282634 0.000037 0.001031 0.282624 -5.3 1.36.1 528 13 OK-10-PO1-134 13.7 2.00.282708 0.000062 0.000871 0.282699 -2.7 2.29.5 562 14 OK-10-PO1-281 20.0 1.60.282721 0.000058 0.001199 0.282709 -2.3 2.09.2 534 15 OK-10-PO1-285 12.2 0.90.282800 0.000090 0.000818 0.282793 0.53.2 10.1 441 16 OK-10-PO1-188 11.7 2.50.282622 0.000048 0.000740 0.282615 -5.8 1.75.8 531 17 OK-10-PO1-313 17.7 3.30.282695 0.000026 0.001034 0.282685 -3.2 0.98.5 541 to ~535 Ma magmatism, with little input of older crustal material. Along with 18 OK-10-PO1-315 22.5 1.30.282718 0.000055 0.001388 0.282705 -2.4 1.98.1 488

1 OK-1-VN-1 19.5 4.00.282670 0.000040 0.001056 0.282662 -4.1 1.44.7 405 2 OK-1-VN-3 14.1 5.70.281151 0.000026 0.000784 0.281110-57.8 0.93.2 2741 3 OK-1-VN-5526.64.3 0.281953 0.000036 0.001562 0.281904 -29.41.3 6.31661 the U-Pb ages, the positive eHf values distinctively characterize the detrital zir- 4 OK-1-VN-9 23.8 5.40.281947 0.000030 0.001384 0.281903 -29.71.1 6.01651 RESULTS OF ANALYSES t 5 OK-1-VN-1021.34.4 0.282018 0.000038 0.001208 0.281986 -27.11.3 4.01435 6 OK-1-VN-113.6 5.50.281007 0.000042 0.000239 0.280994 -62.91.5 5.23003 7 OK-1-VN-1214.74.5 0.282254 0.000030 0.000794 0.282238 -18.81.1 4.91081 8 OK-1-VN-6812.74.5 0.281860 0.000028 0.000730 0.281834 -32.71.0 8.71871 9 OK-1-VN-9612.64.2 0.281766 0.000030 0.000679 0.281742 -36.01.1 4.91849 cons from the Cambrian igneous rocks of the Wichita uplift. Unfortunately, eHft 10 OK-1-VN-171 13.9 3.90.280985 0.000032 0.000880 0.280935 -63.61.1 2.72985 11 OK-1-VN-173 12.7 5.50.281934 0.000036 0.000685 0.281913 -30.11.3 6.21643 12 OK-1-VN-9011.25.2 0.281356 0.000037 0.000661 0.281326 -50.51.3 1.02321 13 OK-1-VN-6113.05.6 0.281072 0.000032 0.000735 0.281036 -60.61.1 -3.6 2567 14 OK-1-VN-125 12.5 4.90.281124 0.000031 0.000800 0.281080 -58.71.1 4.32832 values are not yet available from the Wichita Granite Group for comparison. 15 OK-1-VN-359.7 4.70.281199 0.000037 0.000553 0.281170 -56.11.3 4.82720 Post Oak Conglomerate 16 OK-1-VN-141 60.1 3.50.282178 0.000032 0.003208 0.282114-21.5 1.10.3 1071 17 OK-1-VN-143 5.24.6 0.281186 0.000039 0.000303 0.281171 -56.51.4 4.42702 18 OK-1-VN-149 38.0 4.60.282324 0.000036 0.002393 0.282305 -16.31.3 -7.3 437 19 OK-1-VN-7611.25.0 0.282198 0.000037 0.000637 0.282186 -20.81.3 0.9985 20 OK-1-VN-135 15.8 4.00.282748 0.000041 0.000905 0.282741 -1.3 1.57.7 415 21 OK-1-VN-134 12.3 4.70.282015 0.000034 0.000708 0.281996 -27.21.2 4.11420 22 OK-1-VN-132 3.84.8 0.281142 0.000040 0.000221 0.281130 -58.11.4 3.72735 23 OK-1-VN-131 27.7 4.80.2819110.0000330.001519 0.281863 -30.91.2 4.61652 24 OK-1-VN-7312.15.1 0.281896 0.000038 0.000661 0.281878 -31.51.3 0.11431 25 OK-1-VN-869.2 4.90.2821120.0000310.000539 0.282102 -23.81.1 -1.6 1010 Detrital zircons from the Post Oak Conglomerate have a very strong uni- 26 OK-1-VN-5027.94.2 0.282091 0.000026 0.001493 0.282062 -24.50.9 -2.3 1038 Vanoss Conglomerate modal distribution (Fig. 5). The dominant concentration at ~535 Ma has 77% of 2 Supplemental Table 2 and accompanying worksheets. the grains in the range of 540–520 Ma and 95% of the grains between 560 and The strongly dominant mode (2860–2620 Ma) of ages of detrital zircons Please visit http://dx.doi.org/10 .1130/GES01316.S2 or the full-text article on www.gsapubs.org to view 515 Ma. The oldest grain is 580 Ma. A few grains are scattered between 515 in the Vanoss Conglomerate (Fig. 5) has no counterpart in the basement rocks

the Supplemental Files. and 425 Ma. The eHft values range between +4.7 and +10.1 (Fig. 5). of the Arbuckle uplift. The older secondary group (1520–1300 Ma) does span the

Southern Oklahoma igneous rocks 20 2σ avg uncertainty 15

10 DM 5 Figure 5. Relative age-probability plots (lower panel) and Hf-evolution diagram 0 (upper panel) showing results from CHUR sandstones in and near the Wichita and Arbuckle uplifts (data in Supplemental –5 Tables 1 and 2 [see footnotes 1 and 2]). Lower panel: relative age-probability plots for four analyzed samples and a composite –10 plot of the two Vanoss samples; vertical color bands represent the age ranges of potential provenance provinces in North

America. Upper panel: εHft data for three –15 crustal samples (data points are color coded as evolution shown in the lower panel); the average un- –20 certainty of Hf isotopic analyses (2.6 epsi lon units at 2σ) is shown in upper right. Appalachians The Hf-evolution diagram shows the Hf isotopic composition at the time of zircon

–25 Epsilon Hf Gander/Mira Grenville crystallization, in epsilon units, relative to the chondritic uniform reservoir (CHUR) Granite-Rhyolite –30 (Bouvier et al., 2008) and to the depleted Central Plains mantle (DM) (Vervoort and Blichert-Toft, Superior & Penokean 1999). Shown for reference is the evolu- –35 tion of typical felsic crust, which is based on a 176Lu/177Hf ratio of 0.0115 (Vervoort Wellington Formation (OK-4-WL; n=329) and Patchett, 1996; Vervoort et al., 1999). Reference fields summarize published Hf Vanoss Conglomerate (N=2; n=650) isotopic data for the Appalachians (Mueller et al., 2007, 2008) and associated Gander (Willner et al., 2014) and Mira (Willner Vanoss Conglomerate (OK-2-V2; n=306) et al., 2013) terranes, the Grenville orogen (Bickford et al., 2010; Gehrels and Pecha, 2014), Mesoproterozoic rocks of the Mid- Vanoss Conglomerate (OK-1-VN; n=344) continent Granite-Rhyolite province and Paleoproterozoic rocks of the Central Plains orogen (Goodge and Vervoort, 2006; Bickford et al., 2008; Gehrels and e t Pecha, 2014), and Penokean and Superior s li ol gen in son provinces of the Canadian Shield (Gehrels y o d r la h nes ior o P and Pecha, 2014). R

n r ogens - a r e r e al r n ll t ea r pe t e k ns-Hu c o vi t ni n o a Su n a r oi e an a n r e z T ed C r e w G t o & P G d e le r n a c o c P G a (0.5x) Post Oak Conglomerate (OK-10-PO1; n=328)

200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200 Detrital zircon age (Ma)

age of the Granite-Rhyolite province, which is represented specifically by the 100°W 90°W 80°W basement rocks in the Arbuckle uplift (1399–1363 Ma), suggesting a possible local primary source for at least some of these grains. The younger secondary Superior 50°N group (1240–970 Ma), equivalent in age to the Grenville province of eastern 50°N >2400 Ma North America, has no counterpart in the Arbuckle basement (Fig. 5). Minor components of the detrital-zircon population (1910–1760 Ma and 1710–1580 Ma) correspond in age to the Trans-Hudson–Penokean and Yavapai-Mazatzal–Central Plains orogens, respectively (Fig. 5); neither is represented in the Arbuckle base- Midc. 1100 Ma

Trans-Hudson ment. The two grains with ages of 563 and 525 Ma are similar to ages of Cam- 2000–1800 Ma Penokean brian igneous rocks along the Southern Oklahoma fault system (Fig. 5); how- 1900–1800 Ma 45°N ever, eHft values of +4.1 and –4.7, respectively, are more negative than the range of values for the ~535 Ma zircons in the Post Oak Conglomerate. The eHf values a t MMa suggest that these grains in the Vanoss Conglomerate are not from the Southern 7 997 Oklahoma igneous rocks. The few younger grains (437–375 Ma) have no evident 1 ––9 Central Plains 00–9 source from uplifts along the Southern Oklahoma fault system. GrenvilleG 00 1800–1650 Ma 1300–970 Ma The very abundant grains with ages of 2860–2620 Ma correspond in age to the Superior province of the eastern Canadian Shield (Fig. 5), posing an 40°N apparently difficult quandary of distant provenance and sediment dispersal. The Cambrian–Ordovician craton-wide carbonate bank includes quartz e ose sandstone units that are distributed across the Midcontinent from outcrops near the onlap onto the Superior province of the Canadian Shield as Granite-Rhyolit far southwest as the Southern Oklahoma fault system (Fig. 6). Throughout 1480–1320 MaOK the extent of the sandstones in the Middle Ordovician part of the carbonate 35°N succession, the detrital-zircon populations are dominated by Superior-age S.O. 2 3 grains (Fig. 7) (Pickell, 2012; Konstantinou et al., 2014) from either a primary 539–530 Ma source on the Shield or recycled from Proterozoic sedimentary basins on the ) Shield. Paleogeographic reconstruction (Konstantinou et al., 2014) places the le n sediment-dispersal pathway from the Shield onto the carbonate shelf along Llano-Grenvil Ordovician latitude 10°S. Westward (in Ordovician coordinates; southward in 1300–1000 Ma 30°N present coordinates) transport of mature quartz sand on the carbonate shelf 30°N inboard from the Appalachian-Ouachita margin of eastern Laurentia suggests 0 500 kmm the effects of trade winds on sediment dispersal across the shelf. The domi- 100°W Iapetan rift95°W margi 90°W 85°W nance of Superior-age detrital zircons, as well as the carbonate clasts, in the of Laurentia (~530 Ma Vanoss Conglomerate indicates a source for recycling from the Ordovician Figure 6. Map of extent and dispersal patterns of Middle Ordovician sandstones, which are carbonate succession and quartzose sandstone (Tulip Creek, McLish, and Oil interpreted to be the source of recycled zircons in the Vanoss Conglomerate, in relation to Pre- Creek Formations of the Simpson Group; Fig. 4) on the Arbuckle uplift. cambrian basement provinces from Figure 1. Red dashed line shows approximate maximum extent of Middle Ordovician sandstone units; red arrows show inferred dispersal patterns. Red In addition to being a source for recycled Superior-age zircons, the sand- bold ovals show locations of detrital-zircon data from Middle Ordovician sandstones: (1) from stones in the Cambrian–Ordovician succession contain zircons of other ages Konstantinou et al. (2014), (2) and (3) from Pickell (2012). Abbreviations: Midc.—Midcontinent rift in smaller amounts, indicating recycling as a probable source for most of the system; OK—Oklahoma; S.O.—Southern Oklahoma fault system. grains in the Vanoss Conglomerate (Fig. 7). In particular, the most prominent secondary mode in the Ordovician sandstones corresponds in age to the Gren- ville province (Fig. 7); the lower Paleozoic transgressive succession onlaps the between 1910 and 1580 Ma suggest probable recycling as the source of those Grenville province along the southeast side of the Superior province (Fig. 6). ages in the Vanoss (Fig. 7). None of the Ordovician sandstones contain zircons Although some Vanoss detrital zircons of the age of the Granite-Rhyolite younger than ~950 Ma (Fig. 7), indicating that the younger grains in the Vanoss province may have been derived from a local primary source in the Arbuckle either had a source outside the Arbuckle uplift or were possibly recycled from basement, some of the Ordovician sandstones also contain a component of the middle Paleozoic succession (for which no confirming zircon data are avail- detrital zircons of that age (Fig. 7). Lesser concentrations of grains with ages able) in the Arbuckle uplift.

Southern Oklahoma igneous rocks l e ntra yolit Plains Ce Rh Superior enokean & e- P ans-Hudson Gondwanan ville orogen Tr Granit aleozoic orogens accreted terranes Gren P

Wellington Formation (n=329)

Vanoss Conglomerate (n=650)

Figure 7. Relative age-probability plots for the samples reported herein, compared (0.2x) Post Oak Conglomerate (n=328) with U-Pb ages from Middle Ordovician sandstones in the Arbuckle Mountains and in northern Arkansas (Pickell, 2012) Middle Ordovician Tulip Creek Formation, Arbuckle Mountains and from Cambrian through Middle Ordo (N=2; n=201) vician sandstones in the northern Mid- continent (Konstantinou et al., 2014). The Middle Ordovician sandstones exposed in Middle Ordovician McLish Formation, Arbuckle Mountains the Arbuckle Mountains (Fig. 4) are inter- (N=2; n=169) preted to be the source of recycled zircons in the Vanoss Conglomerate; whereas the Middle Ordovician sandstones exposed in northern Arkansas and the Cambrian Middle Ordovician Oil Creek Formation, Arbuckle Mountains through Middle Ordovician sandstones (n=107) exposed in the northern Midcontinent are Middle Ordovician St. Peter and Everton Formations, northern Arkansas interpreted to represent the dispersal system from the Canadian Shield to the car- (N=4; n=377) bonate bank of eastern Laurentia (Fig. 6). Middle Ordovician St. Peter Sandstone, northern Midcontinent (N=6; n=584)

Lower Ordovician sandstones, northern Midcontinent (N=4; n=455)

Cambrian sandstones, northern Midcontinent (N=5; n=538)

2006400 00 800100012001400160018002000220024002600280030003200 Detrital zircon age (Ma)

The eHft values are consistent with Superior and Penokean zircons from from +7.7 to –7.3. For zircons with ages (563 and 525 Ma) similar to those of the

the eastern Canadian Shield, with Yavapai-Mazatzal–Central Plains zircons, Southern Oklahoma synrift igneous rocks, the eHft values (+4.1 to –4.7) do not

with the Granite-Rhyolite province, and with Grenville-age zircons from east- overlap with eHft values of zircons from the Post Oak Conglomerate, suggest-

ern Laurentia, including the eastern Shield (Fig. 5). U-Pb ages and eHft values ing that these zircons were not derived locally from Southern Oklahoma igne- of the Vanoss zircons with ages >985 Ma are consistent with recycling from ous rocks. The youngest zircons (437–375 Ma) in the Vanoss Conglomerate are sandstones within the Ordovician limestone succession in the Arbuckle uplift. distinctly younger than the Southern Oklahoma synrift igneous rocks, and the

For the rare younger zircons in the Vanoss Conglomerate, eHft values range eHft values (+7.7 to –7.3) are mostly more negative than eHft values of zircons

from the Post Oak Conglomerate. The U-Pb ages and eHft values together in- ample, along the Arbuckle anticline, within a distance of ~25 km along strike, dicate sources outside the Southern Oklahoma basement uplifts, consistent the unconformity cuts across the Ordovician sedimentary succession down to with primary sources in accreted terranes along the Paleozoic Appalachian- the basal Cambrian sandstone just above the Colbert (Carlton) Rhyolite (Fig. 4) Ouachita orogen or recycling from the middle Paleozoic cover succession on (Stanley and Chang, 2012). The two Vanoss samples reported here are from the Arbuckle uplift. sandstones near the unconformable onlap onto the Ordovician strata (Fig. 4), and the detrital-zircon population reflects recycling from the sandstones within the carbonate succession (Fig. 7). By analogy, nearby, where the Pennsyl Wellington Formation vanian strata onlap down to the basal sandstone just above the Colbert Rhyo- lite (Stanley and Chang, 2012), the detrital-zircon population more likely might The strong concentration of Superior-age zircons in the recycled source for be dominated by zircons with ages of 539–536 Ma. the Vanoss Conglomerate is not evident in the detrital zircons from the Welling- Interpretations of depositional systems within the Pennsylvanian–Permian ton Formation. The local supply of zircons from the Cambrian synrift igneous cover around the Arbuckle and Wichita uplifts include multiple alluvial fans, rocks, as in the Post Oak Conglomerate, along the Southern Oklahoma fault prograding down from relatively restricted drainage areas within the uplifts system may be represented in a subset (673–500 Ma) of the younger dominant into marine settings (e.g., Johnson et al., 1988). In the context of variable un-

mode in the Wellington. Some of those grains have eHft values (+6.5) that are roofing along the uplifts, the different local fans potentially tapped different similar to those in the Post Oak Conglomerate; however, others (+2.9 to –15.3) rocks at the head of the drainage. For example, the recycled detrital zircons are not (Fig. 5). in the Vanoss samples represent only the Middle Ordovician sandstones on The mix of zircon ages in the Wellington Formation suggests a more com- the Arbuckle uplift (Figs. 4 and 5), whereas the Post Oak detrital zircons rep- posite source separate and probably somewhat distant from the Arbuckle and resent only the unroofed Wichita Granite Group in the Wichita uplift (Figs. 3 Wichita uplifts. The grains older than 960 Ma are permissive of recycling from and 5). Predictably, samples from other fans along the system may have dif- the Ordovician sandstones or from the Vanoss Conglomerate; however, the ferent detrital-zircon populations, depending on which rocks were exposed in proportions contrast strongly, especially in the Superior-age component. The the heads of drainage. grains younger than ~500 Ma have no counterpart in the basement rocks of The lateral and vertical variability of the sedimentary deposits along the the Southern Oklahoma fault system or in the potential sources of recycled zir- uplifts has led to difficulties in stratigraphic subdivision and definition of geo- cons. Along with the more dominant component of Grenville age, the younger logic map units. The samples reported here are from an outcrop area most re- grains suggest a source separate and distal from the Arbuckle and Wichita cently mapped as Vanoss Conglomerate (Stanley and Chang, 2012). Geologists uplifts, likely from along the Paleozoic Appalachian-Ouachita orogen. of the Oklahoma Geological Survey currently are studying the stratigraphic subdivisions, and new mapping units are likely to be defined (N.H. Suneson and T.M. Stanley, 2015, personal commun.). Ultimately, the samples reported Detritus from the Wichita and Arbuckle Uplifts here as from the Vanoss Conglomerate may be reassigned. The effort to distin- guish different fan deposits as stratigraphic units could benefit from the use of The Wichita and Arbuckle uplifts along the Southern Oklahoma fault sys- detrital zircons to define fan systems. tem include numerous separate fault blocks along which the faults were active episodically, leading to a non-systematic evolution of erosional unroofing and sedimentary reworking and onlap of proximal detritus (e.g., Ham et al., 1964; CONCLUSIONS Johnson et al., 1988; Denison, 1989; Perry, 1989). The highly distinct differ- ences in detrital-zircon populations of the Post Oak and Vanoss Conglomerates Detrital-zircon populations document localized proximal sources for sedi (Fig. 5) clearly illustrate the contrast in unroofing history between those spe- ment synchronous with fault-bounded uplifts (Arbuckle and Wichita) along cific segments of the uplifts. The Vanoss samples represent a level of unroof- the Southern Oklahoma fault system (Fig. 8). The Lower Permian Post Oak ing down only to the Middle Ordovician carbonate succession with quartzose Conglomerate, which rests on the Wichita Granite Group along the Wichita sandstone components, and the detrital-zircon population includes no grains uplift, has zircons (~535 Ma) derived exclusively from the synrift granite (Figs. that indicate an unroofed basement source. In contrast, the detrital-zircon pop- 3, 5, and 8). In contrast, the Upper Pennsylvanian Vanoss Conglomerate adja- ulation of the Post Oak sample (Fig. 5) indicates complete unroofing of the cent to the Arbuckle uplift has a detrital-zircon population (dominated by ages Wichita Granite Group and no recycling from the eroded sedimentary cover. of the cratonic Superior province) derived almost exclusively from recycling Around the Arbuckle uplift, the Vanoss Conglomerate is within a succes- of zircons from sandstones within the Cambrian–Ordovician passive-margin sion of Upper Pennsylvanian clastic rocks, the base of which is an angular cover succession above the Arbuckle basement rocks (Figs. 4–8). These data unconformity that cuts across the older Paleozoic sedimentary cover. For ex- document the dominance of localized proximal sources within the Wichita

The locally derived ~535 Ma zircons in the Post Oak Conglomerate from the

Sample locations Wichita Granite Group have distinctive eHft values (+4.7 to +10.1), that are consistent with mantle-derived juvenile magmas. In contrast, some other zircons of the same age in the Vanoss Conglomerate and Wellington Formation have

eHft values in the negative range, suggesting a different, presumably more

Permian strata distant source. The negative eHft values are consistent with remobilization of Wellington Formation older basement rocks, an attribute that suggests Gondwanan terranes. These rate Post Oak results offer the possibility that ~535 Ma zircons from synrift mantle-derived Conglome magmas can be distinguished from remobilized basement rocks in accreted Gondwanan terranes on the basis of Hf data. Testing this concept will require Vanoss focused sampling from several terranes and dispersal systems. ift Conglomerate

Wichita upl ACKNOWLEDGMENTS LOCAL SOURCES OF Sample collecting was conducted by Thomas in collaboration with Jim Puckette and Neil Suneson, who guided the selection of outcrops and stratigraphic level of samples. Beth Welke assisted in DETRITAL ZIRCONS ft recycled zircons from the field work. Constructive reviews of the manuscript by Pat Bickford for Geosphere and by Neil Suneson are gratefully acknowledged. This research has been funded by National Science Foun- Middle Ordovician sandstones ckle upli bu dation grants EAR-1338583 (for support of the Arizona LaserChron Center) and EAR-1304980. Cambrian synrift igneous rocks Ar (539–330 Ma) REFERENCES CITED Figure 8. Schematic block diagram (not to scale) of sample locations in the context of stratigraphic and structural settings. The Post Oak Conglomerate laps onto an erosion surface on Bickford, M.E., and Lewis, R.D., 1979, U-Pb geochronology of exposed basement rocks in Okla- the Wichita Granite Group within the Wichita uplift. 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