ALBERT

Description: A determination of the critical bed shear stress of maerl is a prerequisite for quantifying its mobility, rate of erosion and deposition in conservation management. The critical bed shear stress for incipient motion has been determined for the first time for samples from biogenic free-living maerl beds in three contrasting environments (open marine, intertidal and beach) in Galway Bay, west of Ireland. The bed shear stress was determined using two methods, Law of the Wall and Turbulent Kinetic Energy, in a rotating annular flume and in a linear flume. The velocity profile of flowing water above a bed of natural maerl grains was measured in four runs of progressively increasing flow velocity until the flow exceeded the critical shear stress of grains on the bed. The critical Shields parameter and the mobility number are estimated and compared with the equivalent curves for natural quartz sand. The critical Shields parameters for the maerl particles from all three environments fall below the Shields curve. Along with a previously reported correlation between maerl grain shape and settling velocity, these results suggest that the highly irregular shapes also allow maerl grains to be mobilised more easily than quartz grains with the same sieve diameter. The intertidal beds with the roughest particles exhibit the greatest critical shear stress because the particle thalli interlock and resist entrainment. In samples with a high percentage of maerl and low percentage of siliciclastic sand, the lower density, lower settling velocity and lower critical bed shear stress of maerl results in its preferential transport over the siliciclastic sediment. At velocities ~10 cm s-1 higher than the threshold velocity of grain motion, rarely-documented subaqueous maerl dunes formed in the annular flume.

Description: During expedition SCAN 2013, two gravity cores were collected in the Ona High slope, central Ona Basin, NE prolongation of the Antarctic Peninsula. Core TG-01 is 400 cm long and was collected from 2160 m water depth at 60º22'23.9314''S, 53º02'15.2501''W; core TG-03 is 295 cm long and was obtained from 2789 m water depth at 60º11'23.4003''S, 53º10'49.0810''W. Non-destructive analyses (i.e., physical properties measurements and X-ray fluorescence scanning) were performed on the archive halves. Both, physical properties (magnetic susceptibility, gamma-ray density, electrical resistivity and P-wave velocity) and major element compositions were determined at 1-cm resolution on split core surfaces of the archive halves using a GEOTEK Multi-Sensor Core Logger (MSCL) 81 at the Spanish Geological Survey (IGME, Spain).

Description: Two important points exist within temperature dependence curves for biosphere metabolism: the inflection point (T_inf), and the thermal maximum (T_max). The inflection point for temperature dependent rates represents temperatures where an increase in rate (k) is maximal relative to temperature (T). The thermal maximum represents the top of the temperature dependence curve where any additional increase in temperature will decrease metabolic rate. Here we define T_max for the land uptake as temperatures beyond which photosynthetic rate decreases (T_max). T_max was calculated for the terrestrial biosphere using MacroMolecular Rate Theory(MMRT) and FLUXNET data. More information on MMRT can be found in Arcus et al. (2016). Information on the 2015 FLUXNET synthesis dataset can be found here: fluxdata.org

Description: During expedition SCAN 2013, gravity core TG-01 was collected in the Ona High slope, central Ona Basin, NE prolongation of the Antarctic Peninsula. The core is 400 cm long and was collected from 2160 m water depth at 60º22'23.9314''S, 53º02'15.2501''W. Non-destructive analyses (i.e., X-ray fluorescence scanning) were performed on the archive halves. Major element compositions were determined at 1-cm resolution on split core surfaces of the archive halves using a GEOTEK Multi-Sensor Core Logger (MSCL) 81 at the Spanish Geological Survey (IGME, Spain).

Description: During expedition SCAN 2013, gravity core TG-03 was collected in the Ona High slope, central Ona Basin, NE prolongation of the Antarctic Peninsula. The core is 295 cm long and was collected from 2789 m water depth at 60º11'23.4003''S, 53º10'49.0810''W. Non-destructive analyses (i.e., X-ray fluorescence scanning) were performed on the archive halves. Major element compositions were determined at 1-cm resolution on split core surfaces of the archive halves using a GEOTEK Multi-Sensor Core Logger (MSCL) 81 at the Spanish Geological Survey (IGME, Spain).

Description: Here we provide extensive micropaleontological and geochemical dataset of shallow-marine deposits that includes palynology and palynomorph component, carbonate fine-fraction stable-isotope, benthic foraminiferal stable-isotope, X-ray fluorescence (XRF), and glycerol dialkyl glycerol tetraether (GDGT) data. Samples were originally collected from the Mossy Grove core, nearby Jackson, central Mississippi, US Gulf Coastal Plain, between August 19, 1991 and September 5, 1991 (Dockery III et al., 1991). The dataset was generated between October 2015 and June 2019 and covers the latest Eocene and earliest Oligocene (~37.5-33.1 million years ago). These data were intended to yield unique multi-proxy records of the critical Eocene-Oligocene Transition, the most prominent climate event in the last 100 million years of Earth's history. Methods for age model, palynology and palynomorph component, carbonate fine-fraction stable-isotope, benthic foraminiferal stable-isotope, X-ray fluorescence (XRF), and glycerol dialkyl glycerol tetraether (GDGT) data follow De Lira Mota et al. (in review).

Description: Elemental composition of the sediment core was determined using two XRF techniques. 2,098 samples on the original core section were directly analyzed at a resolution of ~1.2 cm across the interval 17.1-109.4 m with a hand-held XRF analyzer at the core store of the Mississippi Department of Environmental Quality, in Jackson, Mississippi. A further 179 samples were collected every 20-30 cm downcore, spanning the interval 106.8-151.6 m, and were subsequently finely ground and dried before analysis as pressed powders in wax pellets. Pellets were analyzed with a Bruker S8 TIGER XRF spectrometer with an 8 min analysis time, at the School of Chemistry, University of Birmingham. We selected the (Al+Fe+K+Ti)/Ca ratio as a paleoenvironmental indicator of terrigenous-derived versus marine planktonic carbonate sediment 79,80. The two methodologies were cross-calibrated over an interval of overlap between 106.8 and 109.4 m, with a total of ~80 samples, spanning a range of compositions, cross-correlated from both analysis methods.