Late Miocene-Quaternary fault evolution and interaction in the southern California Inner Continental Borderland

Changing conditions along plate boundaries are thought to result in the reactivation of preexisting structures. The offshore southern California Borderland has undergone dramatic adjustments as conditions changed from subduction tectonics to transform tectonics, including major Miocene oblique extension, followed by transpressional fault reactivation. However, consensus is still lacking about stratigraphic age models, fault geometry, and slip history for the near-offshore area between southern Los Angeles and San Diego (California, USA). We interpret an extensive data set of seismic reflection, bathymetric, and stratigraphic data from that area to determine the three-dimensional geometry and kinematic evolution of the faults and folds and document how preexisting structures have changed their activity and type of slip through time. The resulting structural representation reveals a moderately landward-dipping San Mateo–Carlsbad fault that converges downward with the steeper, right-lateral Newport-Inglewood fault, forming a fault wedge affected by Quaternary contractional folding. This fault wedge deformed in transtension during late Miocene through Pliocene time. Subsequently, the San Mateo–Carlsbad fault underwent 0.6–1.0 km displacement, spatially varying between reverse right lateral and transtensional right lateral. In contrast, shallow parts of the previously identified gently dipping Oceanside detachment and the faults above it appear to have been inactive since the early Pliocene. These observations, together with new and revised geometric representations of additional steeper faults, and the evidence for a pervasive strike-slip component on these nearshore faults, suggest a need to revise the earthquake hazard estimates for the coastal region

Steady late quaternary slip rate on the Cinarcik section of the North Anatolian fault near Istanbul, Turkey

The distribution of plate motion between multiple fault strands and how this distribution may evolve remain poorly understood, despite the key implications for seismic hazards. The North Anatolian Fault in northwest Turkey is a prime example of a multistranded continental transform. Here we present the first constraints on late Quaternary slip rates on its northern branch across the Cinarcik Basin in the eastern Marmara Sea. We use both deep penetration and high‐resolution multichannel seismic reflection data with a stratigraphic age model to show that a depocenter has persisted near the fault bend responsible for that transform basin. Successively older depocenters have been transported westward by fault motion relative to Eurasia, indicating a uniform right‐lateral slip rate of 18.5 mm/yr over the last 500,000 years, compared to overall GPS rates (23–24 mm/yr). Thus, the northern branch has slipped at a nearly constant rate and has accounted for most of the relative plate motion between Eurasia and Anatolia since ~0.5 Ma

Non-work-related services at the workplace : an exploratory study

In an era of diminishing public funds, the profession of social work is looking more and more toward the private sector as an arena for social work practice. Social work has had a long-standing interest in the impact of work and the workplace on the individual. This study was developed in response to the lack of documentation of non-work-related services in Oregon\u27s businesses and industries. The research team set out to discover what non-work-related services are available to employees at or through the workplace in the TriCounty area (Multnomah, Clackamas, and Washington Counties) of Oregon. This study was exploratory, similar to one done by Hans Spiegel and colleagues in 1974, through Hunter College in New York City

Evidence for widespread creep on the flanks of the Sea of Marmara transform basin from marine geophysical data

"Wave" fields have long been recognized in marine sediments on the flanks of basins and oceans in both tectonically active and inactive environments. The origin of "waves" (hereafter called undulations) is controversial; competing models ascribe them to depositional processes, gravity-driven downslope creep or collapse, and/or tectonic shortening. Here we analyze pervasive undulation fields identified in swath bathymetry and new high-resolution multichannel seismic (MCS) reflection data from the Sea of Marmara, Turkey. Although they exhibit some of the classical features of sediment waves, the following distinctive characteristics exclude a purely depositional origin: (1) parallelism between the crests of the undulations and bathymetric contours over a wide range of orientations, (2) steep flanks of the undulations (up to ∼40°), and (3) increases in undulations amplitude with depth. We argue that the undulations are folds formed by gravity-driven downslope creep that have been augmented by depositional processes. These creep folds develop over long time periods (≥0.5 m.y.) and stand in contrast to geologically instantaneous collapse. Stratigraphic growth on the upslope limbs indicates that deposition contributes to the formation and upslope migration of the folds. The temporal and spatial evolution of the creep folds is clearly related to rapid tilting in this tectonically active transform basin

Buried Oligocene glacial topography beneath a smooth middle Miocene unconformity in the southeast Ross Sea: Evolution of West Antarctic glaciation

Buried U-shaped troughs as much as 20 km-wide and flat-topped ridges adjacent to western Marie Byrd Land have recently been proposed as the result of late Oligocene West Antarctic glaciation. Here, additional evidence for pre-25 Ma glaciation is presented for the southeast Ross Sea, together with a different stratigraphic correlation path that establishes age constraints. Buried rough glacial topography interpreted to be of Oligocene age contrasts with a buried smooth and planar middle Miocene “Red” angular unconformity. The Red unconformity extends east-west 160 km near the ice shelf edge, and is 700 m-deep. Part of a 2 km section of Oligocene to middle Miocene strata was removed by erosion. Any smooth post-rift subsidence profile requires that the Red unconformity was carved in water depths of several hundred meters. Several early through middle Miocene glacial erosion surfaces merge to form this unconformity, suggesting multiple advances of thick grounded ice