SUBTROPICAL RECORD OF UPPER DEVONIAN (LATE FRASNIAN-EARLY FAMENNIAN) SEA LEVEL EVENTS AND KELLWASSER EXTINCTION BIOEVENTS, SOUTHERN OUACHITA MARGIN-WESTERN LAURUSSIA (ARIZONA-NEW MEXICO, CENTRAL AND NORTHERN MEXICO)

The Devonian rocks of southern New Mexico provide a relatively complete record of Upper Devonian sea level and biotic events spanning the interval of the Kellwasser stepped extinction bioevents along the subtropical Ouachita continental margin of western Laurussia. Upper Devonian strata in the San Andres and Sacramento Mountains of New Mexico include middle-outer shelf and basinal deposits (Sly Gap and Contadero fms.). Carbonate platform deposits (upper Martin Fm.) spanning the Frasnian-Famennian (F-F) transition were eroded in Arizona-Mexico and the Sacramento Mountains of New Mexico, but are preserved in the central and southern San Andres Mountains. Sly Gap-Martin deposition occurred during two Late Frasnian marine flooding events (Montagne Noire Zone 11, intra M.N. Zone 12). A third Late Frasnian (M.N. Zone 13A) deepening event coincides with the Lower Kellwasser Event (LKE), associated platform back-stepping and virtual extinction of the Sly Gap platform fauna (colonial rugosans, stromatoporoids, >90% of Sly Gap brachiopod species). Rapid subsidence and marine flooding of T-R cycle IId-2 near the base of M.N. Zone 13 resulted in onset of deposition of prograding basinal and capping platform facies of the Salinas Peak Member (Contadero Fm.) over the extinct Sly Gap platform, followed by an Early Famennian lowstand and regional erosional episode. The moderately diverse platform fauna of the Contadero became extinct during the Upper Kellwasser Event (LKE), with only 4 of 35 Contadero species known form post-extinction survivor and recovery faunas in North American basins. Extinction patterns along the Ouachita margin and records from other subtropical and equatorial sites in Western Laurussia are consistent with global cooling events associated with the LKE and UKE.