Detrital zircons from crystalline rocks along the Southern Oklahoma fault system, Wichita and Arbuckle Mountains, USA

Abstract

Detrital zircons with ages of 535 ± 10 Ma in many North American Midcontinent sandstones are commonly attributed to sources in Cambrian synrift igneous rocks along the Southern Oklahoma fault system. New analyses are designed to test the characteristics of proximal detritus from the Wichita and Arbuckle uplifts. Detrital zircons from a sandstone (Lower Permian Post Oak Conglomerate) directly above an unconformable contact with the Wichita Granite Group in the Wichita Mountains have strongly unimodal U-Pb ages of 540-520 Ma and εHf t values of +4.7 to +10.1. In contrast, two sandstone samples (Upper Pennsylvanian Vanoss Conglomerate) in the onlapping succession above an angular unconformity on Paleozoic strata on the flank of the Arbuckle anticline have detrital zircons with U-Pb ages that correspond dominantly to the Superior (~2700 Ma) and secondarily to the Granite-Rhyolite (1480-1320 Ma) and Grenville (1300-970 Ma) provinces of the Laurentian craton. The Vanoss zircons indicate recycling from quartzose sandstones within the Middle Ordovician platform carbonates in the Arbuckle passive-margin cover succession. A stratigraphically higher sandstone (Permian Wellington Formation) above the onlapping conglomerates has a more diverse detritalzircon population, indicating that sediment dispersal from external sources overwhelmed the proximal detritus in the immediate cover of the Wichita and Arbuckle uplifts. The distinctive εHf t values of the proximal detritus from the Cambrian synrift igneous rocks offer potential discrimination from zircons of the same age from Gondwanan accreted terranes, which are represented in the Wellington sample. GEOLOGIC SETTING AND EVOLUTION OF THE SOUTHERN OKLAHOMA FAULT SYSTEM Mesoproterozoic Basement Rocks Basement rocks in the Arbuckle uplift belong to the Southern Granite-Rhyolite province (Fig. 1) (e.g.,

Detrital zircons and sediment dispersal from the Coahuila terrane of northern Mexico into the Marathon foreland of the southern Midcontinent

“…Zircons from the Marathon foreland with ages of 750-500 Ma generally have negative εHf t values, similar to those of Pan-African components of Gondwana, and in contrast to the strongly positive εHf t values of zircons from synrift Wichita granites in the Southern Oklahoma fault system along the Iapetan rifted margin of Laurentia (Fig. 7) (Thomas et al, 2016). Appalachian and Gondwanan zircons overlap in the 2σ data density for ages younger than 750 Ma; however, the data are clearly separated at the 1σ level ( Fig.…”

“…13). The εHf t values for 600-500 Ma grains in the Wellington Formation are more negative than those from the Wichita Granite, indicating a source other than the local synrift igneous rocks (Thomas et al, 2016). The groupings generally are similar to those in the Marathon foreland, suggesting that dispersal of sediment spread across the southern craton from Marathon to the Anadarko basin.…”

“…The initial and most proximal late Paleozoic sedimentary accumulations unconformably overlap eroded Paleozoic sedimentary rocks, Cambrian synrift rocks, and Precambrian basement rocks (Thomas et al, 2016). Local detritus dominates the proximal deposits, which include first-cycle zircons from the 535 Ma Wichita Granite Group, as well as recycled grains with ages older than 2400 Ma from lower Paleozoic sandstones (Thomas et al, 2016). A few meters stratigraphically above the proximal deposits, the sandstones have a completely different population of detrital zircons, indicating sediment from sources other than the local ones.…”

“…The Arbuckle and Wichita basement uplifts within the late Paleozoic Southern Oklahoma fault system form the southern boundary of the Anadarko basin. The initial and most proximal late Paleozoic sedimentary accumulations unconformably overlap eroded Paleozoic sedimentary rocks, Cambrian synrift rocks, and Precambrian basement rocks (Thomas et al, 2016). Local detritus dominates the proximal deposits, which include first-cycle zircons from the 535 Ma Wichita Granite Group, as well as recycled grains with ages older than 2400 Ma from lower Paleozoic sandstones (Thomas et al, 2016).…”

Detrital Zircon Geochronologic Constraints on Patterns and Drivers of Continental‐Scale Sediment Dispersal in the Late Mississippian

“…The Midcontinent Rift System is made up of bimodal igneous rocks that reflect a short-lived (1,115-1,085 Ma) pulse of back-arc extension and magmatism during the Grenville orogeny (Ojakangas et al, 2001). Cambrian intrusive and volcanic rocks, including gabbro and basalt, also developed along the Southern Oklahoma fault system (Arbuckle and Wichita uplifts in Figure 1b), collectively known as the 550-530 Ma Southern Oklahoma Aulocogen (Bowring & Hoppe, 1982;Hanson et al, 2013;Hogan & Gilbert, 1998;Thomas, 2014;Thomas et al, 2016;Wright et al, 1996).…”