Geochemistry of Mississippian tuffs from the Ouachita Mountains, and implications for the tectonics of the Ouachita orogen, Oklahoma and Arkansas

Structural and tectonic evolution of the Acatlán Complex, southern Mexico: Its role in the collisional history of Laurentia and Gondwana

“…The subduction related to the closure of the Rheic Ocean is inferred to have been west dipping (Figure 13j), because no magmatic arc was emplaced on the Cosoltepec suite, whereas Upper Devonian granites cut the high P/T block. A west dipping subduction is compatible with some interpretations in the Southern and Northern Appalachian [e.g., Hatcher , 1987; Ziegler , 1988; Scotese , 2001], but some paleogeographic reconstructions propose southeastern subduction direction in the Ouachita region [e.g., Loomis et al , 1994; R. Blakey, Sedimentation, tectonics, and paleogeography of the North Atlantic region, 2007, http://jan.ucc.nau.edu/∼rcb7/340Nat.jpg]. In the Appalachians, Acadian postmetamorphic plutons range in age from 388 to 371 Ma [ Loiselle et al , 1983]; therefore, they are coeval with granites from the Acatlán Complex, including La Noria Granite and leucogranites of the Esperanza suite (371–372 Ma) [ Yañez et al , 1991; Vega‐Granillo et al , 2007].…”

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“…Uplift and subsidence of large continental areas resulting from dynamic topography relate to mantle fl ow linked to the initiation and cessation of subduction. The potential appeal of dynamic topography for the ARM system derives from the presumed importance of the Ouachita-Marathon subduction system in ARM orogenesis; however, the system records southward-dipping subduction (Viele and Thomas, 1989;Loomis et al, 1994;Dickinson and Lawton, 2003;Poole et al, 2005), such that any potential infl uence of dynamic topography should have affected the Gondwanan, rather than the Laurentian, plate.…”

Bedded Barite Deposits: Environments of Deposition, Styles of Mineralization, and Tectonic Settings

“…Volcanic rocks are sparse in the Ouachitas, reflecting the tectonic setting on the subducting plate, but four silicic tuff horizons occur in the Stanley Formation (Loomis et al, 1994;Niem, 1977). The Beavers Bend and Hatton tuffs occur 300-350 m above the contact of the Stanley with the Arkansas Novaculite; the Upper and Lower Mud Creek tuffs are 450-500 m above this contact (Figure 16).…”

“…Based on the immobile trace elements, the igneous samples also are classified as dacitic to rhyodacitic, and fall on a welldefined trend (Figure 17), with the Beavers Bend and Hatton clustered tightly together and the Mud Creek falling at slightly more mafic values. Rare earth elements (REE) also suggest an evolution to more mafic compositions: Eu/Eu* values are 0.21-0.56 and 0.26-0.42 for the Beavers Bend and Hatton, respectively, compared to 0.76-0.84 for the Mud Creek (Loomis et al, 1994). Thus the composition of the ash beds changes with time, but remains well within a field distinct from those of the Red Dog and California Borderland volcanic fields on the Zr/Ti versus Nb/Y diagram.…”

“…Composition of tuffs in Stanley FormationSource:Loomis J, Weaver H, and Blatt H (1994) Geochemistry of Mississippian tuffs from the Ouachita Mountains, and implications for the tectonics of the Ouachita orogen, Oklahoma and Arkansas. Geological Society of America Bulletin 106: 1158-1171.…”