Major, trace and rare earth element whole rock geochemical analyses of the early to middle Paleozoic strata of the Ouachita Orogenic Belt

Whole-rock geochemical analyses are powerful tools in understanding provenance, depositional environments, and diagenetic histories of sedimentary rock. Such analyses were performed on the Upper Cambrian-Lower Mississippian Core Sequences of the Ouachita Orogenic Belt. Investigations incorporating these spatially and temporally expansive sequences reveal both regional and possible worldwide changes in marine conditions during deposition.; Cerium anomalies (Ce_sh/Ce_sh*) systematically increase from the Upper Ordovician through Silurian. Ce_sh/Ce_sh* values are directly related to depositional conditions, with no post-depositional fractionation of cerium recognized. Samples enriched in the reducing elements exhibited some of the lowest Ce_sh/Ce_sh*.Ce_sh/Ce _sh* possess positive correlations with Bi, Te, Sn, In, and Sc; with the higher concentrations recognized in formations possessing higher Ce _sh/Ce_sh*. Higher Ce_sh/Ce_sh* are likely related to andesitic volcanism to the south and east under globally oxic conditions during the Siluro-Devonian.; Observed temporal patterns in major, trace and rare-earth element content of siliciclastic specimens have revealed four broad categories based on those geological processes that had affected elemental concentrations. These categories are—anoxic sediment: [Ag, As, Ba, C, Cd, Cr, Cu, Mo, Ni, Re, S, Sb, U, V, W, Zn]; oxic-hydrogenetic enriched sediment: [Bi, Be, Cs, Rb, In, Sc, Sr, Te, Th, MnO, Fe₂O₃]; sediment sharing traits of groups 1 and 2: [Ga, Pb, Te, Tl, Sn]; and other sediment types, primarily controlled diagenesis [SiO₂, MgO, CaO], terrigenous detritus [Al ₂O₃, TiO₂, K₂O, Fe₂O ₃], and biogenous content [Ba, P₂O₅].; Al₂O₃/TiO₂, europium anomalies and Th/Sc-Zr/Sc co-variation analyses indicate that the eastern Ouachita Basin was a trailing-edge margin in the Cambrian-Middle Ordovician receiving detritus from exposed cratonic-shield terrains, whereas during Middle Ordovician-Mississippian times it received additional Taconic-related arc material. The western part of the basin received detritus from exposed cratonic shields up until the Upper Mississippian at the start of the terminal collision.; Lanthanide, major and trace element concentrations of Ouachita cherts are controlled primarily by original biogenic, hydrogenetic and detrital constituents along with diagenetic alteration of the carbonates during burial and post-lithification-silicification processes. TiO₂-Zr-Y analysis suggests that much of novaculitic cherts were volcanic in origin. Chemostratigraphic analysis indicates the Persimmon Gap is Silurian, not part of the Ordovician Maravillas Formation.