New Mexico Geological Society Annual Spring Meeting — Abstracts

The Pennsylvanian section at Priest Canyon (sec.7, T3N, R5E, Valencia County) includes the type sections of units named by Myers (USGS Bulletin 1372-F) and long applied to Pennsylvanian strata throughout the Manzano and Manzanita Mountains. Detailed restudy indicates it is very similar to the Pennsylvanian section in the Cerros de Amado, ~60 km to the SW, so, stratigraphic nomenclature introduced by Thompson in 1942 can be applied at Priest Canyon. The base of this section is the ~ 70 m thick Sandia Fm, mostly covered slopes and beds of sandstone, limestone and conglomerate that rest on Proterozoic basement. The overlying Gray Mesa Fm (= Los Moyos Limestone) is ~190 m thick and mostly cherty limestone, divided into three members (ascending): (1) Elephant Butte Mb, ~ 24 m of limestone and shale; (2) Whiskey Canyon Mb, ~86 m of cherty limestone; and (3) Garcia Mb, ~83 m of non-cherty limestone and shale with lesser amounts of cherty limestone, sandstone and conglomerate. The overlying Atrasado Fm (= Wild Cow Fm) is ~ 272 m thick and divided into eight members (ascending): (1) Bartolo Mb, ~ 66 m of slope-forming shale with thin beds of sandstone, limestone and conglomerate; (2) Amado Mb, ~ 8 m of bedded, cherty, brachiopod-rich limestone; (3) Tinajas Mb, ~125 m of shale with interbedded limestone and sandstone; 4) Council Springs Mb, ~ 22 m of mostly algal limestone without chert; (5) Burrego Mb, ~18 m of arkosic red beds and limestone; (6) Story Mb, ~ 7 m of limestone; (7) Del Cuerto Mb, ~ 15 m of arkosic red beds and limestone; and (8) Moya Mb, ~ 11 m of bedded limestone and shale. At the top of the Pennsylvanian section, the Bursum Formation is at least 30 m of interbedded red-bed mudstone, sandstone, conglomerate and limestone. At their type sections, Myers members of the “Wild Cow Fm” clearly are fusulinid-based, biostratigraphic units, not lithostratigraphic units, as their contacts are not drawn at laterally traceable lithologic changes. Thus, Sol se Mete Mb = Missourian fusulinids (= Bartolo-lower Tinajas), Pine Shadow Mb = early Virgilian fusulinids (=upper Tinajas-lower Burrego) and La Casa = middle-late Virgilian fusulinids (=upper BurregoMoya). We thus recommend abandonment of all Myers Pennsylvanian lithostratigraphic terms because they are either synonyms of earlier named units or do not identify useful lithostratigraphic units.