MIDDLE-UPPER DEVONIAN (MID GIVETIAN-EARLY FAMENNIAN) EVENT HISTORY OF THE CRATONIC BASIN INBOARD OF THE OUACHITA CONTINENTAL MARGIN IN SOUTHERN-NEW MEXICO

The late Middle and early Upper Devonian strata of southern New Mexico consist of relatively thin but complex succession of mixed marine clastic and carbonate shelf and basinal deposits that accumulated in cratonic middle-outer shelf, shelf marginand basinal regimes along the southern Ouachita margin of Devonian Laurussia. Sea level rise in the late Givetian initiated deposition of the Oñate Formation (Fm.) that onlapped Silurian and Ordovician carbonate deposits in the San Andres and Sacramento Mountains of southern New Mexico. Oñate Fm. in southern New Mexico spans the upper part of the ansatus-lower disparilis zones. Clastic and mixed clastic-carbonate shelf and shelf margin facies of the Oñate accumulated in the central and northern San Andres and Sacramento Mountains with basinal facies restricted to the southern San Andres Mountains. Forced regression during the late Givetian terminated Oñate deposition and erosion of Oñate deposits occurred during the prolonged emergence interval that spanned 12-13 conodont zones of the latest Givetian-middle Frasnian. Sly Gap Formation mixed carbonate-clastic platform deposition began in the Late Frasnian across southern New Mexico, initiated by the profound eustatic sea-level rise during Frasnian Zone 11. Two additional relative sea level rise events are recorded by rocks of the upper Sly Gap and Salinas Peak Member of the Contadero Formation within Zone 12 and the Zone 12-Subzone 13a boundary interval. Black shale deposition characterized basinal regimes in the southern San Andres and southern Sacramentos during Sly Gap and Salinas Peak deposition. The latter deepening in the very late Frasnian resulted in virtual extinction of the warm-water platform fauna of the Sly Gap Formation (=Lower Kellwasser Extinction of LKE), and initiated Salinas Peak Member deposition in the San Andres Mountains. Rapid subsidence and marine flooding near the base Frasnian 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) prior to the Early Famennian lowstand episode.