Abstract The Tansill Formation and the Lamar Member of the Bell Canyon Formation are the uppermost carbonate units equivalent to the Capitan Reef Complex of West Texas and Southeast New Mexico. Fusuli-nid occurrences establish the equivalency of the Lamar and the pre-Ocotillo Member part of the Tansill. Surface and subsurface studies by numerous workers show the Tansill-Capitan-Lamar to represent classic examples of shelf, shelf edge and slope, and basin deposits, respectively. Tansill carbonates are restricted to the shelf areas surrounding the Delaware Basin. The biota, strati-graphic relationships, depositional textures, and sedimentary structures suggest these carbonates were deposited in shallow water environments which include (1) evaporite, (2) “mixed shelf carbonate,” (3) unwinnowed shelf carbonate sand and (4) winnowed shelf carbonate sand environments. Facies characteristic of these environments can be further subdivided. Tansill carbonates are mostly light colored dolostones that thin sheifward by interfingering with evaporites. The biota is “restricted marine” consisting mostly of algae, molluscs, and Foraminifera. The “mixed shelf carbonate” environment is characterized by irregularly laminated mudstone and textures interpreted to have been superimposed on original shallow water deposits during exposure and (or) under intertidal and supratidal conditions. Carbonate sands in the winnowed shelf environment are better sorted, contain less fine matrix, more skeletal grains, and osagid-type coated grains than the unwinnowed shelf carbonate deposits. The portion of the Capitan Formation time-equivalent to the Tansill contains a diverse “normal marine biota.” Captain deposits of the shelf edge environment are massive lime packstone, wackestone, and locali’ boundstone which are commonly altered by recrystallization. Capitan deposits of the basin slope environment are generally light colored, partly dolomitized, and poorly bedded packstone with primary basinward dips. Characteristic grain types are sand- and coarser-sized skeletal and intraclast debris. The Lamar Member is restricted to the Delaware Basin, thins basinward by wedging, and then grades into a thin unit of dark shaly siltstone and silty shale. Lamar environments include (1) basin margin, (2) basinal, and (3) starved basin. In contrast to the Tansill and Capitan carbonates, the Lamar consists predominantly of cherty, dark-colored lime packstone, wackestone, and mudstone with well preserved depositional texture. Graded beds are common in the basin margin limestones. Grain types are mostly redeposited skeletal and intraclast debris derived from the shelf edge and basin slope environments. Textural evidence and stratigraphie framework suggest these grains were periodically transported into the Delaware Basin by turbidity currents. The basinal carbonate environment is characterized by evenly laminated mudstone and fine skeletal-intraclast wackestone. The starved basin environment is represented by a thin, widespread unit of black, shaly siltstone and silty shale.

Abstract The Guadalupian Series, with its type section in the Guadalupe Mountains, west Texas and New Mexico, has generally become the accepted worldwide standard for the Middle Permian. The Cisuralian of Russia is the accepted standard for the Early Permian; and the Lopingian of China has been accepted as the Late Permian standard. Most recently, the task of securing this threefold worldwide standard has been pursued by a host of workers in many specialties in order that no major gaps or overlaps are left for chronostratigraphic correlation. Following established international procedures for defining a chronostratigraphic boundary, the base of the Guadalupian Series is recognized at the stratigraphicaUy lowest occurrence of the conodont Jinogondolella nankingensis in a section recording continuous deposition in the middle of the El Centro Member of the Cutoff Formation, Roadian Stage, Guadalupe Mountains. This designation is in basic agreement with the ranges of important species of three other major faunal groups: the ammonoids, brachiopods, and fusulinaceans. Designation of a formal top of the Guadalupian Series has remained more elusive inasmuch as the final establishment of the base of the overlying Lopingian in China has remained in a rather unsettled state until recently. Enough is now known to insure that the Lopingian base will fall chronostratigraphicaily somewhere between the upper Lamar Limestone, Bell Canyon Formation, and the base of the Castile Formation of the Delaware Basin. This interval includes the so-called “post-Lamar beds” of the upper Bell Canyon Formation. As a means of equating the lithostratigraphy to the chronostratigraphy, we describe herein the Reef Trail Member of the upper Bell Canyon Formation by establishing its type section at McKittrick Canyon, Guadalupe Mountains, as a formal replacement name for the informal “post-Lamar beds.” We also identify the fusulinacean and conodont faunas from composited sections of Lamar Limestone and Reef Trail members, and extend their correlations biostratigraphically from the Guadalupes to the Apache and Glass mountains. The McKittrick Canyon Limestone is a new name given to the “Middle” Limestone (Brown, 1996), following his recognition that this limestone had for too long been misidentified as the McCombs Limestone. Finally, correlation of faunal zones established in the Delaware Basin from the three mountainous areas are extended globally in an attempt to reconcile chronostratigraphic problems.