An analysis of sediment provenance for Carboniferous sandstones in the Ouachita-Arkoma Basin based on detrital muscovite 40Ar/39Ar geochronology and sediment composition
Type of DegreeMaster's Thesis
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The Arkoma-Ouachita Basin of southeast Oklahoma and central Arkansas, part of the vast Appalachian-Ouachita foreland system, evolved from a passive margin deep-water remnant ocean basin (Ouachita) between Laurentia and Gondwana into a peripheral foreland basin (Arkoma) driven by the collision of the two supercontinents during the assembly of Pangaea. Basin evolution is recorded by deposition of intermittent carbonate and siliciclastic strata in the Mississippian followed by an influx of syn-tectonic clastic sediment in the Pennsylvanian deposited in traditional sand/shale cycles attributed to flexural evolution from the ongoing collisional tectonics and glacioeustasy fluctuation. Carboniferous sediment deposition along with sediment dispersal patterns is directly connected and influenced by tectonic activity, regional climate, global eustatic cycles, and unroofing events. Carboniferous sandstones from the Ouachita deep-water basin and Arkoma foreland basin present the opportunity to investigate possible source terranes and sediment transport histories throughout the Mississippian to Pennsylvanian using detrital geochronology and sandstone compositional analysis. Fourteen Carboniferous sandstones ranging from the Mississippian Stanley Group to the middle Pennsylvanian Krebs Group were collected for 40Ar/39Ar detrital muscovite geochronology and sandstone compositional analysis, resulting in over 1,500 new detrital grain ages for Carboniferous strata in the Ouachita region. Detrital muscovite grain ages range from Paleoproterozoic to early Pennsylvanian and 98% of the grain ages are Paleozoic. The overall age distribution presents a prominent Middle Ordovician to Early Silurian (ca. 465 Ma to 435 Ma) mode with two subordinate modes that are Early Devonian (ca. 420 Ma to 380 Ma) and Late Devonian to early Mississippian (ca. 380 Ma to 340 Ma), respectively. In addition to the dominant Middle Ordovician to Early Silurian and Early Devonian modes, the Mississippian Stanley Group provides a slightly older age distribution with a significant Cambrian (ca. 540 Ma to 490 Ma) component. The Pennsylvanian samples from the Jackfork Group, Atoka Formation, and Krebs Group yield muscovite with abundant Late Ordovician ages and subdued peaks at ca. 400 Ma and ca. 380 to 365 Ma. Overall, the detrital muscovite ages are characteristic of the multiple Appalachian tectonic episodes, predominantly the Taconic and Acadian-Neoacadian events. The Ordovician ages are interpreted to represent sediment derived from Taconic terranes, while the two subordinate Devonian peaks appear to represent Acadian-Neoacadian source terranes. The detrital muscovite record in these samples from Late Mississippian and Early to Middle Pennsylvanian strata are compatible with sediment routing systems that delivered sediment via multiple complex axial and transverse drainage pathways, principally from Laurentian sources. Continental-scale drainage networks adjacent to the uplifting Appalachian Mountains and an interior longitudinal system both contributed sediment to the southern Appalachian-Ouachita foreland. Minor input of older Cambrian to Middle Ordovician detrital muscovite grains are attributed to fluvial systems traversing through accreted peri-Gondwanan terranes and perhaps a lesser secondary western source connected to the Ancestral Rocky Mountains.