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Ordovician through Mississippian strata of the Ouachita Mountains developed in a classical "starved trough,” and consist mostly of dark slates and cherts with only minor intercalations of coarser clastic sediment Mature, well-sorted quartz and rounded carbonate sands were derived from the North American cra- ton whereas immature, fine-grained sands came from the south or east. The succeeding Carboniferous section, almost 12,250 m (40,000 ft) thick, consists of proximal and distal turbidite sandstones, black shales, and minor interlayered wildflysch and volcanic ash. Sedimentary structures indicate predominant westward sand dispersal; compositions suggest a quartz-rich, cratonic provenance as well as an extracontinental source of feldspathic and Iithic clasts.

South of the Ouachita trough, during the early Paleozoic, oceanic crust plunged under a plate including North America to create an island arc-trench-subduction zone. Northwest of the trench, a slope, rise, and abyssal plain formed along the southern margin of the North American continent. East of the Ouachitas, continent-to-continent collision began in the late Devonian, creating growing source areas from which detrital materials were subsequently shed westward to build a subsea fan during the Carboniferous. South of the Ouachita trough continued subduction by the late Pennsylvanian ultimately created a series of uplifted tectonic lands and resultant sliding of the sedimentary succession northward as folds and thrust sheets against North America. Mesozoic spreading then disrupted the Paleozoic fold belt.

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