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Abstract

The southern Ozark region, Arkansas, Missouri, and Oklahoma occupies the southern border of the North American craton. Its sedimentary succession preserves a complete Wilson Cycle reflecting the Late Precambrian-Cambrian rifting of Rodinia into the Laurussian and Gondwanan landmasses that opened the Iapetus Ocean Basin during the Late Cambrian-Middle Mississippian. The basin was closed during the Late Mississippian-Middle Pennsylvanian by the collision of Laurussia with Gondwana. During the Late Cambrian through the Middle Pennsylvanian, the Ozark Shelf, including its gently sloping, Northern Arkansas Structural Platform (NASP) and adjacent ramp, records both transgression and regression by epeiric seas as well as regional tectonism that can be recognized as five Tectono-Stratigraphic Successions (TS) and correlated readily with the Sloss Cratonic Sequences. The TS record comprises at least 33 named formations with a potential thickness >2926m (9600ft). However, both eustatic and tectonic sea-level rise and fall also produced regional surfaces of erosion that punctuated deposition, and the preserved thickness on the NASP is significantly less. The five distinct, but related, Tectono-stratigraphic Successions in the Paleozoic record are (TS1) Late Precambrian-Middle Cambrian, (TS2) Upper Cambrian-lowest Ordovician, (TS3) Lower Ordovician-Lower Devonian, (TS4) Middle Devonian-Upper Mississippian, and (TS5) Lower-Middle Pennsylvanian. TS1, a pre-Late Sauk Sequence, is the least well-known succession, consisting of emplaced igneous and low-ranked metasedimentary bodies and pre-Lamotte sedimentary rocks. TS2, Late Sauk Sequence, is potentially >937m (3075ft) of dolomites and sandstones. TS3, Tippecanoe Sequence, is the penultimate thickest interval, possibly >1257m (4125ft) of dolomites, limestones, shales, and supermature sandstones. TS4, Kaskaskia Sequence, measures at least 736m (2416ft). The final TS5, Lower Absaroka Sequence of first cycle sandstones with variable amounts of mrfs, and shales is the thickest interval, >1267m (4160ft) and may exceed 7620m (25,000ft) in the adjacent Arkoma Basin.

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