Abstract The Cañones fault zone in north-central New Mexico is a boundary between the Colorado Plateau to the west and the Rio Grande rift to the east. It consists of a major fault, the Cañones fault, and a series of synthetic and antithetic normal faults within the Abiquiu embayment in the northwestern Española basin. The Cañones fault is a southeast-dipping high-angle normal fault, striking ~N20°E in the south, N40°E in the middle, and east-west at its northern end. The synthetic and antithetic faults are sub-parallel to the major fault. Detailed fault kinematic studies from the master fault reveal that the trends of slickenlines range S85°E - S70°E, and average approximately S76°E. Slickenlines on antithetic faults trend S20°W – N30°W, clustering at ~ N70°W. The attitude of fault surfaces and slickenlines indicate east-southeast/west-northwest extension within the Cañones Fault Zone. The sense of motion on the major fault is normal dominantly with left-slip. Fault throw is at least 225 m, based on Mesozoic units as hanging wall and footwall cutoffs. Thus, the heave is as ~143 m and the left-lateral displacement is ~60 m, given the averaged fault attitudes. In contrast to sub-horizontal Permian-Triassic units in its footwall, hanging wall strata of the Cañones fault zone dips in two directions: west-dipping Jurassic Entrada, Todilto, and Morrison formations; and south-east-dipping Eocene El Rito, Oligocene Ritito, and Oligocene-Miocene Abiquiu formations. Tilted Jurassic strata suggest that the overall structure is monoclinal, probably resulting from Laramide orogeny shortening. The Eocene-Miocene basin fill sediments, surprisingly, dip 10° – 30° away from the Cañones Fault, instead of dipping northwest towards the fault. This phenomenon, in contrast to the prediction of the rollover structure, suggests a different mechanism on this fault zone. Field observation provides direct evidence that basinward tilting is accommodated by multiple antithetic normal faults that cut through Permian to Miocene units. We propose that extensional fault-propagation folding model is a possible mechanism to result in the regional tilting of the basin fill. During upward propagation of the fault tip, horizontal-axis rotation and antithetic and synthetic faulting occur within a triangle zone above the fault tip. Alternatively, a buried large-scale low-angle normal fault can also generate such basinward tilting. In this scenario, the Cañones fault and other southeast-dipping normal faults are antithetic faults that grow on the detachment. These hypothetical mechanisms take into account the antithetic faulting within a rift-bounding fault zone and can be indicative of the evolution of other rift basins in which basin fills dip to the axis, such as the eastern Española basin and San Luis basin in northern New Mexico and southern Colorado.

Abstract The Pueblo-Canon City area provides an outstanding opportunity to study well exposed sections of the marine and marginal marine stratigraphie units which make up the Kiowa-Skull Creek (Late Albian), Greenhorn (latest Albian-Middle Turonian), and Niobrara (Late Turonian -Early Campanian) Cyclothems. Each of these cyclothems represents a third-order eustatic fluctuation that produced regionally synchronous transgression and regression in the Western Interior Seaway. Extensively studied exposures along the Canon City hogback and in the dissected Rock Canyon Anticline west of Pueblo are easily accessible and contain the most typical examples of the stratigraphie units in these cyclothems found in Colorado. Numerous, detailed and interdisciplinary studies of this Cretaceous section have been completed (see papers in this volume and references therein) which collectively allow the dynamics of large-scale Cretaceous eustatic cycles to be interpreted and modeled for epicontinental seas. In view of these factors, the Pueblo-Canon City area has become the standard mid-basin reference section for the Kiowa-Skull Creek, Greenhorn, and Niobrara Marine Cycles. The field trip will examine outcrops of each stratigraphie unit in the Kiowa-Skull Creek, Greenhorn, and Niobrara Cyclothems in the Pueblo-Canon City area. Field examination will focus on high-resolution stratigraphie concepts, facies characteristics, geochemical profiles, and inferred depositional environments. Discussions will emphasize a broad range of possible interpretations and current controversies regarding the depositional history of these cyclothems. The prevailing theme of this excursion will be cyclic sedimentation as expressed in Cretaceous marine and marginal marine facies of the Western Interior Seaway. Detailed discussion of each outcrop section can

Abstract Canonical variate analysis (aka discriminant coordinates) is viewed from the aspect of Aitchisonian compositional data analysis and the concept of stability in canonical vectors examined in relation to their refication (i.e. providing canonical vector components with a practical interpretation). The log-ratio transformation was found to have computational and interpretational advantages over the centred log-ratio transformation. The ad hoc application of N. A. Campbell’s application of the method of shrinkage estimators to multiple discrimination, and the optimal retention of discrimination power, is exemplified by two cases, one drawn from quantitative sedimentology, the other from biomolecular palaeontology, with the intention of probing the effect of instability on interpreting the relative importance of standardized canonical variate coefficients in relation to the suppression of near-redundant directions of within-groups variation. Pronounced instability in canonical vectors may endanger the validity of an analysis.