Abstract Abstract: The Williams Ranch Member of the upper Cutoff Formation in the Guadalupe and Delaware Mountains, west Texas, U.S.A., consists of six offlapping lithologic units. The deposits formed during carbonate turbidite deposition across a drowned Early Permian carbonate platform. They have an areal extent of more than 20,000 km 2 and reach a maximum thickness of at least 113 m. At the terminal margin of the older platform, the carbonate turbidites were partially redistributed by mass-transport events (MTEs) onto the slope and basin floor. Deposits formed during individual mass-transport events (MTE bodies) comprise the bulk of the Williams Ranch Member basinward from the drowned margin for at least 28 km along a transect oblique to depositional dip. MTE bodies are interbedded with undeformed carbonate turbidites and contain soft-sediment folds, faults, and extensional and shortening lineations, as well as termination surfaces (beds terminated from above and/or below). Turbidite deposition and subsequent mass transport caused general basinward thickening of the Williams Ranch Member from the drowned margin, where the Cutoff Formation is missing, to the basin floor. Deposition responded to, and modified, inherited bathymetric relief. Compared to isopach thins, isopach thicks formed in bathymetric lows and locally formed bathymetric highs. Isopach thicks contain more undeformed strata and show more soft-sediment folds. These relationships suggest better preservation of strata in structurally controlled inherited bathymetric lows. In general, MTE bodies are preferentially deposited in these paleobathymetric lows. A minimum of six vertically stacked MTE bodies are recognized in the main study area with thicknesses ranging from less than one to tens of meters. MTE bodies show a general S-to-SSE paleotransport direction, with significant local variation, reflecting either underlying bathymetric relief and/or different source locations. Repeated MTEs resulted in a reduction of the overall basin gradient and created local positive bathymetry. Sand fairways and ponded sheet deposits in the overlying Brushy Canyon Formation are focused in bathymetric lows, and sands thin and onlap onto bathymetric highs.

Abstract The Paradox Basin is an asymmetric foreland basin, developed along the southwestern flank of the Uncompahgre uplift in southeast Utah and southwest Colorado, USA. This large basin (265km by 190km) developed during the middle Pennsylvanian-Permian ancestral Rocky Mountain orogenic event. Salt structures in the northern Paradox Basin form a variety of structural styles ranging from deeply buried salt pillows to complexly faulted diapirs and salt walls exposed at the surface. Complex intra-formational unconformities and rapid lateral stratigraphic facies variations indicate that salt structures were active over at least 75 Ma. Analysis of field exposures, sub-surface well, and 2D seismic data across the northern part of the basin reveals a complex relationship between crustal shortening, loading, creation of accommodation space, differential sedimentation, and salt movement. Salt flow through time across the northern part of the basin reflects the varying basin geometry and its response to sediment depositional systems. From the early stages of salt movement in the upper Pennsylvanian, through passive growth of a series of large (up to 4 km high) salt walls, the dynamics of salt movement were a strong control on both structural development and stratigraphic facies architecture.

Abstract Continental depositional systems influenced by salt movement are characterized by rapid lateral and vertical facies changes that are difficult to predict at a reservoir scale. This study presents preliminary observations and interpretations of the Late Triassic Chinle Formation of the northern Paradox Basin, southeast Utah, USA, as a possible outcrop analog to subsurface reservoirs due to its extensive 3D exposure across a range of salt structures that were active during its deposition. Salt movement commenced prior to Chinle Formation deposition, when active structures included buried salt anticlines, salt walls exposed at surface, and salt withdrawal minibasins. In the northern Paradox Basin, regional subsidence and climate controls are locally overprinted by the impact of halokinesis, which results in the break down of the regional Chinle Formation lithostratigraphy. Analysis of field exposures in this area allows the formation to be divided locally into five informal lithostratigraphic units bounded by mappable surfaces. Depositional environments include lacustrine, fluvial, and aeolian. The local stratigraphic framework allows salt-sediment interaction to be recognized by localized (km-scale) stratigraphic thickness variations, angular stratal relationships, and changes in facies architecture. Areas of active salt evacuation ( e.g. , rim synclines and salt-withdrawal minibasins) are characterized by expanded stratigraphic thickness, preferential development and preservation of fine-grained floodplain and lacustrine deposits, and convergent or deflected paleocurrents. Salt walls that were exposed at the surface are characterized by the absence of strata, and the occurrence of rotational unconformities; they also have deflected paleocurrents and abundant reworked sediment into directly adjacent areas. Buried salt structures, active at depth, are also associated with subtle thickness variations and sediment slumping down their paleoslopes.