Sinuous channels are common bathymetric features on Earth's continental margins. Until now, the 3D stratigraphy of these features has primarily been inferred from 3D seismic studies and from limited 2D outcrop exposures of ancient successions. The Beacon Channel Complex of the Permian upper Brushy Canyon Formation is an exceptionally well-exposed example of a 3D exposure of a sinuous slope channel system. The Beacon Channel Complex crops out on five cliff facies in an area of approximately 1 km(2) (0.625 mi(2)). Nearly one complete wavelength of sinuosity is recorded in the outcrop.

Mass Transport Complexes (MTCs) are significant constituents of the fill of the basins of the Brazos-Trinity Slope System. These MTCs are composite stratigraphic bodies consisting of resedimented materials associated with slumps, slides, debris flows, but also subordinate turbidites, and hemipelagites. Although their composition is variable, they tend to be mud-rich. The MTCs exhibit a variety of external geometries. They commonly have erosive bases characterized by "boxy", grooved scours and mounded tops. Commonly, they are internally chaotic, but sometimes show crude stratification or fabrics related to patterns of movement and/or deformation. Because of increased awareness of the abundance of MTCs within deep marine settings and their association with other well known architectural elements, recent attempts have been made to incorporate the occurrence of MTCs into predictive sequence stratigraphic models. The models emphasize the role of relative sea level cycles in the generation of MTCs and relate this to formative processes and positions within an idealized depositional sequence. However, while some Brazos-Trinity MTCs may conform to these concepts, others do not. As such, utility of MTCs for developing sequence stratigraphic frameworks for the Brazos-Trinity system is dubious. Based on our understanding of the Brazos-Trinity Slope System it is proposed that MTCs play a role in shaping hyrdrocarbon traps in analogous subsurface systems. Although some portions of these MTCs contain sufficient porous and permeable sediment to constitute hydrocarbon reservoirs, most represent seal and "waste rock" units. They can form basal, vertical and lateral seals to reservoir complexes, as well as intra-reservoir seals and baffles. Because of their erosive nature, the emplacement of MTC's has often resulted in localized or widespread termination of reservoir strata. MTC's with clay-rich lithologies form low permeability, high capillary entry pressure layers overlying these erosional surfaces. Thus, the geometry and transmissibility of contacts between MTCs and reservoir-bearing strata can play an important role in defining the stratigraphic component of hyrdrocarbon traps and represent baffles or barriers to fluid flow during production.

The northern continental slope of the Gulf of Mexico is riddled with numerous subsiding diapiric minibasins bounded by ridges, and often connected by channels created by turbidity currents. The region is economically relevant in that these diapiric minibasins constitute excellent focal points for the deposition of sand. These deposits in turn serve as excellent reservoirs for hydrocarbons. A better understanding of the ''fill and spill'' process by which minibasins fill with sediment as the intervening ridges are dissected by canyons may serve to aid in the location of such reservoirs. A theoretical analysis in a companion paper has revealed two key aspects of the ''fill and spill'' process: (1) the formation of an internal hydraulic jump as a turbidity current spills into a confined basin, and (2) the detrainment of water across a settling interface forming at the top of the ponded turbidity current downstream of the hydraulic jump. In that paper it was shown that sufficiently strong detrainment can consume the flow, so that there is no outflow of either water or sediment even with continuous inflow. As the basin fills with sediment, however, overspill is eventually realized. Herein the theory of the companion paper is used as the basis for a numerical model of ponding of turbidity currents. The numerical model is tested and verified against two experiments. In the first of these, detrainment is sufficient to capture an entire sustained turbidity current. In the second of these, detrainment is insufficient to prevent sustained overspill. The principles of similitude using the densimetric Froude number allow upscaling of the experimental results to field scale. A full numerical model is verified against the experiments and applied at field scale. The result is a view of intraslope minibasin sedimentation that has a stronger physical basis than the conceptual models proposed to date.

This volume assembles information on giant (>500 MOEB recoverable reserves) hydrocarbon reservoirs that will be of value to a wide audience. Although far from exhaustive, this compilation includes a wide range of reservoirs when examined from any perspective, such as location, geology, and production history. Reservoirs described in this volume are located in the Middle East, Asia, West Africa, North America, and South America. The authors explore historical and alternative approaches to reservoir description, characterization, and management, as well as examining appropriate levels and timing of data gathering, technology applications, evaluation techniques, and management practices in various stages in the life of individual development projects. Enhanced recovery of hydrocarbons requires a critical understanding of reservoir heterogeneity by both geoscientists and engineers. The giant fields discussed in this Memoir address issues important to reservoir description, characterization, and management from both geologic and engineering perspectives.

This study focuses on the sedimentary fill of basin 4, the termination of the Brazos-Trinity minibasin slope system in the northwestern Gulf of Mexico. Results from multistratigraphic analyses of 15 giant piston cores provided (1) important information regarding the nature (hemipelagic versus gravity-induced mud and sand deposits) and the timing of the sedimentary fill; (2) some key chronostratigraphic constraints for the evolution of this system; and (3) strong links between well-known cycles of sea level change to clearly imaged deposits in the fill of basin 4. Gravity-flow–induced sedimentation in basin 4 occurred and increased in importance during the stepwise sea level regression that developed between 115 and 15 ka and clearly ceased just prior to the meltwater spike in the Gulf of Mexico dated at about 14 ka. The onset of gravity-induced deposition in basin 4 is dated at marine isotope stage (MIS) 5d (115 ka). This finding implies that sandy turbidity currents reached this distal setting as a consequence of a higher frequency sea level fall within a time of general high sea level (MIS 5). An interval of hemipelagic sedimentation lasting from 90 to 45 ka illustrates cessation of gravity-induced deposits in basin 4. Turbidite sandy deposits resumed in mid-MIS 3 and increased toward MIS 2 (approximately from 30 to 15 ka). The largest proportion of reservoir-grade sandy sediment was deposited during the maximum sea level lowstand of the last glacial maximum, consistent with the prevailing view of sequence-stratigraphic models for deep-water deposition.

The Cerro Toro Formation in the Torres del Paine National Park, southern Chile, contains a series of deep-water channel complexes deposited in an elongate Andean foreland basin during the Late Cretaceous. This stratigraphic interval represents an essentially continuous depositional record of migrating, leveed-channel complexes. Collectively, the channel-fill units in the study area form a belt approximately 5 km (3 mi) wide and several hundred meters thick. Within the study area, four sets of channel complexes are identified. This paper focuses on the best exposed of these channel-complex sets (channel-complex set 3). The channels are filled by bedded conglomerate and amalgamated sandstones interpreted to represent the deposits of high-concentration turbidity currents and debris flows. Large-scale cross-beds in some of the conglomerates indicate significant bed-load transport of gravel- and cobble-forming bars in the channels. Channel axis to margin facies changes between clast-supported conglomerate and either (1) thick-bedded sandstone or (2) matrix-supported conglomerate are observed. Channel-fill facies lie on erosional surfaces that cut into adjacent interchannel facies. Beds thin and onlap these surfaces toward the channel margins. Shale or siltstone drapes of the channel cuts are uncommon and laterally discontinuous. Bed continuity between channel and adjacent, interchannel facies is not observed. The interchannel strata are interpreted to represent levee successions that bound the channels. Stratigraphy in the levee units is defined to include (1) basal, sandy lobe deposits comprised of medium- to thick-bedded turbidites and (2) overbank facies consisting primarily of packages of fining- and thinning-upward, fine-grained, thin-bedded turbidites. This vertical succession is transitional. Distal levee facies include mudstones with thin-bedded, laterally continuous sandstones. Proximal levee facies include mudstones: with both thin- and thick-bedded sandstones; however, the thick-bedded sandstones have lower lateral continuity. The proximal levee facies have a higher sandstone percentage than the distal levee, but also have greater depositional and postdepositional complexity, with sand-filled crevasses, erosional truncation, and slumped beds. Field observations suggest that these leveed channels formed in stages that are represented by depositional and/or erosional events. In chronological order, these are (1) an initial stage of relatively unconfined, sand-rich deposition; (2) aggradation of a mud-rich, confining levee system resulting from overbank deposition as turbidity flows bypass the area; (3) erosion as the channel becomes entrenched or as the channel migrates; and (4) filling of the channel-margin relief by onlap of channel-fill sediments. These stages appear to have repeated several times during the formation of a series of channel complexes. In these ways, the Cerro Toro Formation appears analogous to leveed-channel systems observed in late Pleistocene submarine fans and subsurface examples.

A028 BASIN 4 OF THE BRAZOS-TRINITY SLOPE SYSTEM Introduction 1 We have executed an ultra-high resolution 3-D investigation of the stratigraphy and basin fill history of a 200 km 2 Pleistocene intra-slope basin in the western Gulf of Mexico. This basin represents the southernmost portion of the Brazos-Trinity Slope System; a system of four basins linked by submarine channels (Basin 4; Winker 1998; Beaubouef and Friedman 2000; Badalini et al. 2000; Beaubouef et al. 2003a b c and references therein). This system is located down-dip of the ancestral Brazos and Trinity rivers and their associated deltas (Fig. 1a). These shelf

Introduction Advances in our understanding of siliciclastic deposition in deep-marine settings has occurred through the collection and interpretation of a variety of data sets from modern and ancient (outcrop and subsurface) depositional systems, laboratory experiments, and numerical modeling. Research on deep-water sandstones within the petroleum industry has traditionally relied on interpretation of subsurface systems with conventional exploration data (2D and 3D seismic, well logs, cores) and descriptions of outcrops of ancient systems. More recently, use of experimental and numerical modeling is on the rise (e.g. Hoyal et al., this vol.). Work in each sub-discipline has yielded significant results in the areas of stratigraphic, facies, sediment transport and deposition models of deep-water sandstones. However, there are many limitations to these data sets and results. Fundamental questions remain about how to best integrate and utilize these results to develop a comprehensive understanding of deep-water deposition. Most of the difficulties result from the disparate nature of the data types and the differences in scale and resolution of the observations being made.

Introduction An ultra-high resolution 3-D seismic survey was collected providing near outcrop scale resolution of the sedimentary bodies comprising a Pleistocene submarine fan in the western Gulf of Mexico. The survey area selected is an intra-slope basin located within the Texas continental slope in approximately 1500-m water depth. The basin represents the terminal portion (Basin 4) of a well-known chain of four Pleistocene intra-slope basins often referred to as the Brazos-Trinity Intra-Slope System. At the top of the basin fill is a large submarine fan (8km wide, 16-km long, 100-m maximum thickness) referred to as the Upper Fan (Beaubouef et al., this volume). The seismic program, designed to optimize resolution within the Upper Fan, has provided data from which unprecedented images of the 3D architecture of a submarine fan have been derived. We believe this program represents an opportunity to enter a ‘‘new frontier’’ in the research of siliciclastic reservoirs and is unique within industry and academia. The results are providing detailed information regarding deep-water deposition far surpassing what is possible from outcrop or conventional seismic, well log, and core studies.