Marine Platform of Probable Sangamon Age, and Associated Terrace Deposits, Cape Thompson Area, Northwestern Alaska

Reports geomorphic studies, as part of the US Atomic Energy Commission's investigations in this area 1958-1962. A coastal terrace, observed and measured along a 20-mi section crossing Ogotoruk Creek, is described and its origin, age, and morphology discussed. The feature is complex, consisting of a marine platform planed across bedrock, overlying marine and beach deposits, and a depositional upper surface of nonmarine sediments which coincides in area and configuration with the platform, possibly as a result of factors unique to polar areas. The marine platform and gravels record the last high stand of sea level, 28-40 ft above the present, which occurred about 38,000 yr ago. Other evidence in the area indicates still higher seas in earlier times

Light cone QCD sum rules study of the semileptonic heavy ΞQ\Xi_{Q} and ΞQ′\Xi'_{Q} transitions to Ξ\Xi and Σ\Sigma baryons

The semileptonic decays of heavy spin--1/2, $\Xi_{b(c)}$ and $\Xi'_{b(c)}$ baryons to the light spin-- 1/2, $\Xi$ and $\Sigma$ baryons are investigated in the framework of the light cone QCD sum rules. In particular, using the most general form of the interpolating currents for the heavy baryons as well as the distribution amplitudes of the $\Xi$ and $\Sigma$ baryons, we calculate all form factors entering the matrix elements of the corresponding effective Hamiltonians in full QCD. Having calculated the responsible form factors, we evaluate the decay rates and branching fractions of the related transitions.Comment: 30 Pages, 5 Figures and 18 Table

Diving into the vertical dimension of elasmobranch movement ecology

Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements

Twenty Years of Subduction Zone Science: Subduction Top to Bottom 2 (ST2B-2)

International audienceNo other plate-tectonic setting has attracted such diverse, multidisciplinary research as convergent margins. Under­standing the dynamics of subduction is particularly important for realistic assessment of associated hazards such as earthquakes, tsunamis, and volcanic eruptions. A number of recent initiatives have been successful in building communities not only to investigate subduction processes, but also to convey knowledge about subduction zone processes to other scientists, students, postdocs, and the broader public. These efforts must include synthesizing and simplifying subduction-zone science for classroom presentations and to help prepare the public for subduction-related disasters.Tremendous advances over the past 20 years or so have been made in subduction zone science, with increasingly multidisciplinary efforts producing some of the greatest insights. We have initiated a publication effort in the GSA journal Geosphere, with a Themed Issue “Subduction Top to Bottom 2” (or “ST2B-2”) aimed at showcasing the recent advances, following up on the conceptually similar Subduction Top to Bottom published in 1996 as an American Geophysical Union Geophysical Monograph. The ST2B-2 Geosphere Themed Issue is accumulating papers and is open to ALL wishing to contribute to this effort—we anticipate accepting manuscripts through all of 2018 and possibly beyond

Holocene tectonic histories for five islands in the south-central Lau group, south Pacific

Low-level (<30 m) evidence for emergence is reported for five islands along the south-central Lau Ridge, which has a well-documented history of late Cenozoic uplift. Most of the evidence is erosional, some of the lowest is emerged reef and beachrock: all can be linked to higher relative sea levels. Correlations are established between islands and most of the series of emerged shorelines found to exhibit characteristics of coseismically uplifted series elsewhere. Dates for various shorelines allow ages and recurrence intervals of coseismic-uplift events to be tentatively established for all islands. By reconciling this with contemporary sealevel changes, magnitudes of coseismic uplift are obtained for the middle and late Holocene. The islands of Moce and Oneata have experienced fewest coseismic-uplift events with small uplift magnitudes. Four coseismic-uplift events are identified for Lakeba with an average magnitude of 2.63 m and an assumed recurrence interval of 1045 years: no uplift has apparently occurred since 3800 BP. Five coseismic-uplift events are identified for Namuka-i-Lau with an average magnitude of 2.08 m and an assumed recurrence interval of 1045 years: no uplift has apparently occurred since 2360 BP. Three coseismic-uplift events occurred on Nayau, averaging 1.53 m in magnitude and recurring every 1045 years: no uplift has occurred since 2240 BP. The approach used here has implications not only for understanding tectonic history but may eventually prove a useful tool for isolating Holocene sealevel history in tectonically active areas. © 1995, Sage Publications. All rights reserved