Testing Luminescence Dating Methods for Small Samples from Very Young Fluvial Deposits

The impetus behind this study is to understand the sedimentological dynamics of very young fluvial systems in the Amazon River catchment and relate these to land use change and modern analogue studies of tidal rhythmites in the geologic record. Initial quartz optically stimulated luminescence (OSL) dating feasibility studies have concentrated on spit and bar deposits in the Rio Tapajós. Many of these features have an appearance of freshly deposited pristine sand, and these observations and information from anecdotal evidence and LandSat imagery suggest an apparent decadal stability. The characteristics of OSL from small (~5 cm) sub-samples from ~65 cm by ~2 cm diameter vertical cores are quite remarkable. Signals from medium-sized aliquots (5 mm diameter) exhibit very high specific luminescence sensitivity, have excellent dose recovery and recycling, essentially independent of preheat, and show minimal heat transfer even at the highest preheats. These characteristics enable measurement of very small signals with reasonable precision and, using modified single-aliquot regenerative-dose (SAR) approaches, equivalent doses as low as ~4 mGy can be obtained. Significant recuperation is observed for samples from two of the study sites and, in these instances, either the acceptance threshold was increased or growth curves were forced through the origin; recuperation is considered most likely to be a measurement artefact given the very small size of natural signals. Dose rates calculated from combined inductively coupled plasma mass spectrometry/inductively coupled plasma optical emission spectrometry (ICP-MS/ICP-OES) and high-resolution gamma spectrometry range from ~0.3 to 0.5 mGya−1 , and OSL ages for features so far investigated range from 13 to 34 years to several 100 years. Sampled sands are rich in quartz and yields of 212–250 µm or 250–310 µm grains indicate high-resolution sampling at 1–2 cm intervals is possible. Despite the use of medium-sized aliquots to ensure the recovery of very dim natural OSL signals, these results demonstrate the potential of OSL for studying very young active fluvial processes in these settings

Dating the Tejo river lower terraces in the Ródão area (Portugal) to assess the role of tectonics and uplift

The Tejo river is one of the major drainages in Iberian Peninsula; it is a long-lived system (ca. 3.4 Ma) and provides an archive of long-term landscape development and environmental change controlled by tectonics, climate and eustasy. The most upstream Portuguese reach of the Tejo river, ~ 200 km from the Atlantic coast, shows evidence for five fluvial terraces (T1 to T5) with elevations reaching more than 120 m above the modern river bed. A chronological framework for these terraces is established here by integrating geomorphological, stratigraphical and archaeological information with ages from luminescence dating. Optically stimulated luminescence dating of K-feldspar, (involving the correction for anomalous fading of the luminescence signal), indicates that the younger terraces have a probable age range of: T5 -- 31 to 40 ka; and T4 -- 100 to ~ 280 ka. We deduce that the related major fluvial changes are likely to have been as follows: ~ 10 m of aggradation from ~ 280 to 100 ka (0.06 m/ka); 14 m of incision from 100 to 40 ka (0.23 m/ka); 8 m of aggradation from 40 to 31 ka (0.89 m/ka); 16 m of incision during the last 31 ka (0.52 m/ka). These values indicate that the duration and rate of both aggradation and river downcutting episodes were variable. There is widespread evidence for neotectonic activity in this intraplate region. Neither eustatic nor climatic changes during the Quaternary provide clear trends that might explain the observed pattern of valley incision, thus we conclude that this tectonic activity is the most likely driving mechanism. In the study area, the probable age of the Tejo river sediments deposited before the beginning of valley incision allows the calculation of a time-averaged incision rate of ~ 0.07 to 0.10 m/ka over the last ~ 2.6 Ma. This long-term incision was probably determined by an increase in the relative uplift rate, resulting from the intensification of intraplate compressive stress. During the late Cenozoic fluvial incision stage, the Ródão depression underwent less uplift than the adjacent areas along the river, in which the Tejo has incised a narrow valley into basement rock, with almost no terrace development. Terrace formation was also promoted by soft bedrock (Tertiary arkoses) and by impoundment of alluvium behind resistant barriers crossed by the river. Geomorphological evidence for terrace tectonic offset was also supported by luminescence dating.http://www.sciencedirect.com/science/article/B6V93-4S7BD8S-2/1/042ac50ecc1e9867eccba2f98d4042a

Evidence for a late glacial advance near the beginning of the Younger Dryas in western New York State: An event postdating the record for local Laurentide ice sheet recession

Widespread evidence of an unrecognized late glacial advance across preexisting moraines in western New York is confirmed by 40 14C ages and six new optically stimulated luminescence analyses between the Genesee Valley and the Cattaraugus Creek basin of eastern Lake Erie. The Late Wisconsin chronology is relatively unconstrained by local dating of moraines between Pennsylvania and Lake Ontario. Few published 14C ages record discrete events, unlike evidence in the upper Great Lakes and New England. The new 14C ages from wood in glacial tills along Buttermilk Creek south of Springville, New York, and reevaluation of numerous 14C ages from miscellaneous investigations in the Genesee Valley document a significant glacial advance into Cattaraugus and Livingston Counties between 13,000 and 13,300 cal yr B.P., near the Greenland Interstadial 1b (GI-1b) cooling leading into the transition from the Bölling-Alleröd to the Younger Dryas. The chronology from four widely distributed sites indicates that a Late Wisconsin advance spread till discontinuously over the surface, without significantly modifying the preexisting glacial topography. A short-lived advance by a partially grounded ice shelf best explains the evidence. The advance, ending 43 km south of Rochester and a similar distance south of Buffalo, overlaps the revised chronology for glacial Lake Iroquois, now considered to extend from ca. 14,800–13,000 cal yr B.P. The spread of the radiocarbon ages is similar to the well-known Two Creeks Forest Bed, which equates the event with the Two Rivers advance in Wisconsin

The paraglacial, giant landslide dam of Phoksumdo Lake (Dolpo District,Western Nepal Himalaya)

Abstract HKT-ISTP 2013 B

The effect of coastal landform development on decadal- to millennial-scale longshore sediment fluxes: Evidence from the Holocene evolution of the central mid-Atlantic coast, USA - Sediment Core and Chronology Data

These data are sediment core, radiocarbon, and optically stimulated luminescence (OSL) data from the barrier islands and backbarrier lagoons, bays, and marshes of Assateague Island (VA, USA), Chincoteague Island (VA, USA), and Wallops Island (VA, USA). Vibracore data from Tom’s Cove, a backbarrier bay, were collected using a vibracore system with the ability to core through a ‘moonhole’ on a flat bottom boat. Geoprobe cores were collected using a track-mounted 66DT Geoprobe direct-push drill rig. Select samples from the sediment cores (associated with figures and tables in Shawler et al., 2021) were analyzed using a Beckman-Coulter Laser Diffraction Particle Size Analyzer (LS 13 320 Aqueous Liquid Module) with an applied calculation model that uses Fraunhöfer theory. Data are available as Microsoft Excel Workbooks and can be opened using Excel or numerous free and open sources products such as Google Sheets. Each sediment core data spreadsheet contains a “READ ME” tab with additional detail. The full OSL report from co-author Sebastien Huot is also included and can be accessed with a PDF reader

The effect of coastal landform development on decadal-to millennial-scale longshore sediment fluxes: Evidence from the Holocene evolution of the central mid-Atlantic coast, USA

The behavior of siliciclastic coastal systems is largely controlled by the interplay between accommodation creation and infilling. Factors responsible for altering sediment fluxes to and along open-ocean coasts include cross-shore mobilization of sediment primarily from tidal currents and storms as well as changes in alongshore transport rates moderated by changing wave conditions, river sediment inputs, artificial shoreline hardening and modification, and natural sediment trapping in updrift coastal landforms. This paper focuses on the latter relationships. To address understudied interactions between updrift coastal landforms and downdrift coastal behavior, we quantify the volume and fluxes of sediment trapped in the Assateague-Chincoteague-Wallops barrier-island complex along the Virginia, USA coast and relate these volumes to downdrift coastal-system behavior. During the last ca. 2250 years, these barriers trapped 216 million m3 of sand through the growth of complex beach- and foredune-ridge systems. A period (ca. 400 to 190 years ago) of reduced/no progradation on Chincoteague and Assateague islands corresponds with sediment sequestration in updrift flood-tidal deltas. This finding emphasizes the important control of tidal inlets on alongshore sediment fluxes on barrier-island coasts. Rapid historical spit elongation during the last 190 years has trapped an average of 681,000 m3 yr-1 of sand; this occurred coincident with downdrift barrier-island erosion/migration at long-term rates of greater than 3 m yr1. Historical sand fluxes to the elongating spit on southern Assateague Island and progradational beach ridges on northernmost Wallops Islands are equivalent to at least 60% of estimated regional longshore transport rates. We therefore propose that sediment trapping and associated wave refraction are the primary drivers of downdrift barrier erosion, while storminess and sea-level rise are secondary forcings of change affecting equally the entire barrier-island chain. Global context is provided by a compilation of sediment trapping through growth of similar longshore sand sinks, which indicates the volume of sediment incorporated into the elongating spit end of Assateague Island is similar to sandy beach- and foredune-ridge plains (108 m3), but average annual trapping at the spit is at least six times greater than those at most mainland-attached, progradational systems. However, Chincoteague and Wallops, two progradational barrier islands, incorporate sand at rates broadly similar to large strandplains. Our findings emphasize the need to account for natural longshore sediment trapping in multidecadal coastal management efforts on sandy, siliciclastic coasts

Luminescence dating of Quaternary marine terraces from the coastal part of Eastern Black Sea and their tectonic implications for the Eastern Pontides, Turkey

The timing of the deposition of the well-preserved Quaternary marine terraces in the coastal region of northeastern Turkey are crucial in understanding the Quaternary tectonics of the Pontides. The chronology of raised marine terraces between Trabzon and Rize has remained unrevealed because of chronologic limitations. This study aims to establish chronology for the terrace deposits by applying optically stimulated luminescence (OSL) dating methods using single aliquot regenerative dose (SAR) techniques on quartz grains extracted from marine terraces. Eleven samples were collected from the lowest three Quaternary marine terraces. The OSL ages clusters into three groups: 52.4 ± 4.6 to 60.0 ± 4.7 ka (terrace level T1); 16.8 ± 0.8 to 33.9 ± 2.8 ka (T2); and 11.7 ± 0.9 ka (T3). This chronology is consistent with the classical terrace stratigraphy; i.e. younger terraces are located at lower elevations and vice versa for the older terraces. We correlate the established terrace chronology with MIS 3c, MIS 3a, and MIS 1. We calculated apparent uplift rates are 0.98 ± 0.12 mm/year, 1.39 ± 0.26 mm/year, and 1.50 ± 0.78 mm/year from marine terrace levels 1, 2, and 3, respectively. Based on the existing eustatic sea-level data/curve, we estimated tectonic uplift rates up to 5 mm per year. Our results indicate that the coastal region of the Eastern Pontides experienced three accumulation periods, with sea-level highstands overprinting the uplifting coastline, and the coastal region of Eastern Pontides has been tectonically active from Late Pleistocene to Early Holocene. This study reveals that marine terraces in the coastal region of northeastern Anatolia might have displaced by the South Black Sea Fault which ultimately points to a regional subsidence with the higher uplift rate, and it points to a differential uplift along the Eastern Pontides

Circulating adrenomedullin estimates survival and reversibility of organ failure in sepsis: the prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock-1 (AdrenOSS-1) study

Background: Adrenomedullin (ADM) regulates vascular tone and endothelial permeability during sepsis. Levels of circulating biologically active ADM (bio-ADM) show an inverse relationship with blood pressure and a direct relationship with vasopressor requirement. In the present prospective observational multinational Adrenomedullin and Outcome in Sepsis and Septic Shock 1 (, AdrenOSS-1) study, we assessed relationships between circulating bio-ADM during the initial intensive care unit (ICU) stay and short-term outcome in order to eventually design a biomarker-guided randomized controlled trial. Methods: AdrenOSS-1 was a prospective observational multinational study. The primary outcome was 28-day mortality. Secondary outcomes included organ failure as defined by Sequential Organ Failure Assessment (SOFA) score, organ support with focus on vasopressor/inotropic use, and need for renal replacement therapy. AdrenOSS-1 included 583 patients admitted to the ICU with sepsis or septic shock. Results: Circulating bio-ADM levels were measured upon admission and at day 2. Median bio-ADM concentration upon admission was 80.5 pg/ml [IQR 41.5-148.1 pg/ml]. Initial SOFA score was 7 [IQR 5-10], and 28-day mortality was 22%. We found marked associations between bio-ADM upon admission and 28-day mortality (unadjusted standardized HR 2.3 [CI 1.9-2.9]; adjusted HR 1.6 [CI 1.1-2.5]) and between bio-ADM levels and SOFA score (p < 0.0001). Need of vasopressor/inotrope, renal replacement therapy, and positive fluid balance were more prevalent in patients with a bio-ADM > 70 pg/ml upon admission than in those with bio-ADM ≤ 70 pg/ml. In patients with bio-ADM > 70 pg/ml upon admission, decrease in bio-ADM below 70 pg/ml at day 2 was associated with recovery of organ function at day 7 and better 28-day outcome (9.5% mortality). By contrast, persistently elevated bio-ADM at day 2 was associated with prolonged organ dysfunction and high 28-day mortality (38.1% mortality, HR 4.9, 95% CI 2.5-9.8). Conclusions: AdrenOSS-1 shows that early levels and rapid changes in bio-ADM estimate short-term outcome in sepsis and septic shock. These data are the backbone of the design of the biomarker-guided AdrenOSS-2 trial. Trial registration: ClinicalTrials.gov, NCT02393781. Registered on March 19, 2015

Luminescence dating of sand deposits related to late Pleistocene human occupation at the Cactus Hill Site, Virginia, USA

Optically stimulated luminescence (OSL) ages, obtained primarily using single grains, are reported for 13 sediment samples from the Cactus Hill site, a culturally stratified sand dune in Virginia. The site has drawn interest because of a blade level, potentially representing an early occupation of humans in North America, a few centimeters below a Clovis artifact layer. Pre-Clovis occupation in North America is disputed. Most of the ages are drawn from quartz grains, but the quartz at this site appears to saturate at a young age, so analysis on potassium feldspar grains was also performed on the deepest samples. Geologic evidence suggests deflation, small-scale turbation, and low accretion rates have compressed and slightly mixed some of the deposits. The diameters of OSL sampling tubes therefore cover long time spans for many samples, so a minimum age is determined statistically for the top of sampling volumes. The derived ages, with one exception, are in the correct stratigraphic order and are broadly in agreement with radiocarbon ages. This seems to confirm the overall integrity of the strata and places the deposit containing the pre-Clovis artifacts at about 18 ka. Further evaluation and constraint of the ages is provided by Bayesian analysis

Which fault destroyed Fes city (Morocco) in 1755? A new insight from the Holocene deformations observed along the southern border of Gibraltar arc

International audienceIn this paper, we present the first estimate of the Holocene deformation along the southern front of Gibraltar arc (Morocco) and the first field constraints on the local 1755 CE Fes-Meknes surface rupturing earthquake which could be associated to the “Great Lisbon Earthquake” (M > 8.5) in November 1st, 1755. Using satellite imagery, aerial photographs and field investigations, we carried out a morphotectonic study along the ~ 150 km-long Southern Rif Front (SRF) to identify the most recent evidences of tectonic activity. Analyzed offset alluvial deposits confirm that (i) the last ~ 5 ka cumulative deformation leading to a slip rate of ~ 3.5 ± 1 mm/yr for this segment of the SRF is consistent with the GPS derived horizontal shortening rate of 2–4 mm/yr and (ii) a recent major earthquake ruptured a ~ 30 km-long segment along the SRF. Based on deposits dating and historical seismicity we propose that this seismic event occurred in 1755 as a local earthquake. Even though this 1755 local event cannot be considered as a strong aftershock of the main Lisbon seismic event (M > 8.5), their temporal closeness, their occurrence under the same convergent stress regime (~ NNW-SSE-oriented compression) and the fact that Fes-Meknes area was strongly shaken during the Lisbon earthquake, raises the question of the possible triggering of the Fes earthquake. Anyway, our new results suggest that most of the Nubia-Rif belt convergence is accommodated by the SRF, making it potentially the most destructive structure of the Rif