Abstract Here we establish a magnetostratigraphy susceptibility zonation for the three Middle Permian Global boundary Stratotype Sections and Points (GSSPs) that have recently been defined, located in Guadalupe Mountains National Park, West Texas, USA. These GSSPs, all within the Middle Permian Guadalupian Series, define (1) the base of the Roadian Stage (base of the Guadalupian Series), (2) the base of the Wordian Stage and (3) the base of the Capitanian Stage. Data from two additional stratigraphic successions in the region, equivalent in age to the Kungurian–Roadian and Wordian–Capitanian boundary intervals, are also reported. Based on low-field, mass specific magnetic susceptibility (χ) measurements of 706 closely spaced samples from these stratigraphic sections and time-series analysis of one of these sections, we (1) define the magnetostratigraphy susceptibility zonation for the three Guadalupian Series Global boundary Stratotype Sections and Points; (2) demonstrate that χ datasets provide a proxy for climate cyclicity; (3) give quantitative estimates of the time it took for some of these sediments to accumulate; (4) give the rates at which sediments were accumulated; (5) allow more precise correlation to equivalent sections in the region; (6) identify anomalous stratigraphic horizons; and (7) give estimates for timing and duration of geological events within sections.

Abstract The Late Permian (Guadalupian) mixed carbonate/siliciclastic sequences of the Delaware Basin, one of the long-lived subbasins of the Permian Basin, are well knovvn both for their classic outcrop exposures revealed by basin and range structuring in the Guadalupe Mountains and for their prolific hydrocarbon production (Figure 18 ). A large number of stratigraphic and sedimentologic studies have established the Capitan reef and associated facies as a model for the understanding of carbonate facies in a shelf margin setting and of reciprocal sedimentation relations between a shelf and basin. Early studies focused on biostratigraphy, lithostratigraphy, and early concepts of reciprocal sedimentation. Focus shifted in the 1970’s and 1980’s to analysis of depositional facies and processes and on the relatively new understanding of early diagenesis of reef margins. More recently, the outcrops have been analyzed from a cyclostratigraphy and sequence stratigraphy perspective. It will be interesting to see the impact of a refined stratigraphic fi-amework on the direction of future facies, paleo-ecological, and diagenetic studies. Providing the initial interest in the area were the superb field studies and subsequent detailed reporting of the geology of the southern Guadalupe Mountains by King (1942, 1948 ). The book by Newell et al. (1953) on the Capitan did much to further enhance the outcrops as research models for sedimentary geologists. The critical treatment of the Capitan sedimentology by Dunham in the late 1950’s and 1960’s, culminating in his detailed 1972 guidebook, stimulated interest and added new understanding. Dunham’s work, plus the

Abstract The results are presented from an integrated sedimentologic, structural, stratigraphic, and diagenetic study of syndepositional faults and fractures that cut the Permian Capitan reef and equivalent platform strata within three outcrop windows in Slaughter Canyon, Guadalupe Mountains, New Mexico. The studied faults are dip slip, have displacement of up to 30 m parallel the shelf margin, and are vertically and laterally segmented. The faults dip steeply shelfward and basinward, and grew incrementally during deposition of the Yates and Tansill Formations. Steep polycyclic paleocavern systems developed along faults and fractures. These can have cumulative vertical relief of more than 270 m, extend at least 1.2 km along strike, and are typically less than 10 m wide but can attain a width of 90 m. The paleocaverns can extend more than 110 m below the top of the Capitan reef. The paleocaverns are filled mainly with sediments deposited during Capitan progradation and aggradation. Seven Permian lithologies are distinguished: (1) limestones and limestone breccias, (2) microspar-lithified breccias, (3) carbonate-rich breccias, (4) reworked and remnant breccias, (5) beige dolomitic siltstone-sandstone and associated breccias, (6) pink dolomitic siltstone-sandstone and associated breccias, and (7) spar-cemented breccias. The fills vary vertically and along strike within the paleocaverns but have a clear organization and stratigraphy. The integration of the stratigraphy of the paleocaverns with the structural and sequence stratigraphic framework developed in back-reef strata provides evidence for incremental fault growth and multiple episodes of dissolution, brecciation, collapse, deposition, cementation, and dolomitization within the paleocaverns during Capitan times. Solution-modified syndepositional faults extend at least 33 km along strike from Slaughter Canyon and are considered to be an integral component of the Capitan platform. The fault-zone paleocaverns contain a unique internal record of events and processes that have no counterpart in the shelf succession. Their study provides new insights into the internal heterogeneity and diagenesis of the Capitan platform. The results have important implications for the Capitan platform, and more generally for the heterogeneity of syndepositional fracture-controlled karst systems formed in carbonate platforms with steep unstable margins, subject to compaction-induced tilting and/ or developed in active tectonic settings.

Abstract The west Texas and southeast New Mexico area contains several basins and surrounding platforms that formed and evolved during the Carboniferous and Permian. The collision of Gondwana with Laurasia led to the Ouachita and Marathon orogenies that formed the small intracratonic foreland basins that include the Delaware basin. The Delaware basin is rimmed by a carbonate ramp that evolved into a carbonate platform; it contains thick carbonate and evaporite and thin siliciclastic deposits. The basin is dominated by thick sandstones and siltstones with minor, fine-grained carbonate mudstones and very fine-grained siltstones separating the more sand-rich intervals. Deposition was strongly controlled by sea level fluctuations (glacially controlled eustatic cycles); highstand deposits are dominated by carbonates and lowstand deposits are dominated by siliciclastics. Fine-grained siltstones, with minor shales, are also the background sediments in the basin, particularly during the deposition of the Brushy and cherry Canyon Formations. The Brushy Canyon, formed during a major third-order lowstand cycle with exposure of the carbonate ramp/evolving shelf, is dominated by basinal sandstone deposition. It has been divided into the lower, middle, and upper Brushy Canyon. These probable fourth-order cycles also contain numerous fifth-order cycles. The cherry Canyon Formation is dominated by siltstone deposits. A notable exception is at Last chance Canyon, located near Sitting Bull Falls, which was a feeder canyon supplying coarser grained, high net-to-gross (N/G) sands and silts to the basin. Three outcrops are shown on the following pages that illustrate three distinct channel architectures: single channel (cut-aggrade-abandon), multiple channels (cut-drape-fill), and nested channels with single and amalgamated channels. Contributions from Beaubouef et al., O’Byrne et al., and Barton et al. (chapters 105, 108, 109, this volume) show other channel architectures and facies from the Brushy Canyon Formation.