The characterization and significance of a MIS 5a distal tephra on mainland Australia

Lynch's Crater provides the main reference section for late Quaternary environmental change in northeast Australia. We have identified a cryptotephra horizon within late Marine Isotope Stage-5 (MIS-5) lake sediments obtained from the site. The major element geochemistry of this tephra has been compared with data from southwest Pacific sources, and our results indicate that the cryptotephra is most likely to be of Papuan origin. This is the first discovery of an aerially derived tephra in Australia that originated from outside the mainland. The Lynch's Crater tephra is potentially an important marker horizon which could be used to connect disparate palaeoarchives at a time of significant climatic and environmental change.     

From marine bands to hybrid flows: Sedimentology of a Mississippian black shale

Organic-rich mudstones have long been of interest as conventional and unconventional source rocks and are an important organic carbon sink. Yet the processes that deposited organic-rich muds in epicontinental seaways are poorly understood, partly because few modern analogues exist. This study investigates the processes that transported and deposited sediment and organic matter through part of the Bowland Shale Formation, from the Mississippian Rheic–Tethys seaway. Field to micron-scale sedimentological analysis reveals a heterogeneous succession of carbonate-rich, siliceous, and siliciclastic, argillaceous muds. Deposition of these facies at basinal and slope locations was moderated by progradation of the nearby Pendle delta system, fourth-order eustatic sea-level fluctuation and localized block and basin tectonism. Marine transgressions deposited bioclastic ‘marine band’ (hemi)pelagic packages. These include abundant euhaline macrofaunal tests, and phosphatic concretions of organic matter and radiolarian tests interpreted as faecal pellets sourced from a productive water column. Lens-rich (lenticular) mudstones, hybrid, debrite and turbidite beds successively overlie marine band packages and suggest reducing basin accommodation promoted sediment deposition via laminar and hybrid flows sourced from the basin margins. Mud lenses in lenticular mudstones lack organic linings and bioclasts and are equant in early-cemented lenses and in plan-view, and are largest and most abundant in mudstones overlying marine band packages. Thus, lenses likely represent partially consolidated mud clasts that were scoured and transported in bedload from the shelf or proximal slope, as a ‘shelf to basin’ conveyor, during periods of reduced basin accommodation. Candidate in situ microbial mats in strongly lenticular mudstones, and as rip-up fragments in the down-dip hybrid beds, suggest that these were potentially key biostabilizers of mud. Deltaic mud export was fast, despite the intrabasinal complexity, likely an order of magnitude higher than similar successions deposited in North America. Epicontinental basins remotely linked to delta systems were therefore capable of rapidly accumulating both sediment and organic matter.     

Characterizing Groundwater Flow in Monitoring Wells by Altering Dissolved Oxygen

In this study, the dissolved oxygen (DO) alteration method (Chlebica and Robbins 2013) is used to evaluate the patterns of flow into and vertically within shallow screened monitoring wells. The method entails bubbling air into a well, followed by conducting DO profiles with time. Tests were conducted in six standard 2" (5 cm) polyvinyl chloride shallow screened monitoring wells at four test sites in Storrs, Connecticut. Test sites vary in formation permeability, flow patterns, and nearby geographic features influencing flow. The method provides a means for groundwater flow characterization and potentially improved interpretation of contamination sampling results in the absence of detailed three‐dimensional hydrogeologic information.     

A comparison of surface and subsurface controls on summer temperature in a headwater stream

This study compared summer stream temperature between two years in the Star Creek catchment, Alberta, a headwater basin on the eastern slopes of the Canadian Rocky Mountains. Star Creek is a subsurface water dominated stream, which represents important habitat for native salmonid species. Hydrometeorological data from May to September of 2010 and 2011 accompanied by stream energy budget calculations were used to describe the drivers of stream temperature in this small forested stream. Mean, maximum, and minimum weekly stream temperatures were lower from May to August and higher in September 2011 compared to 2010. Weekly range in stream temperature was also different between years with a higher range in 2010. Inter‐annual stream temperature variation was attributed discharge differences between years, shown to be primarily governed by catchment‐scale moisture conditions. This study demonstrates that both meteorological and hydrological processes must be considered in order to understand stream temperature response to changing environmental conditions in mountainous regions. Copyright © 2013 John Wiley & Sons, Ltd.     

The morphological response of foredunes at a breached barrier system to winter 2013/2014 storms on the southwest coast of Ireland

The level of storminess in Ireland during the winter of 2013/2014 was exceptional, the effects of which cost the Irish state in excess of €260 million in infrastructure repair and insurance claims. In Ireland, a lack of coastal process data from monitoring programmes means that the response of protective barrier coasts to such events remains largely un‐investigated. This study addresses this issue through an examination of the geomorphic impacts of recent storms, including those that occurred during the winter 2013/2014, on a breached barrier on the southwest coast of Ireland. Data from a two‐year terrestrial laser scanning (TLS) monitoring campaign shows that the winter 2013/2014 events caused a major (>50 m) dune recession at Rossbehy, County Kerry. Results from a simple linear regression analysis indicate storm duration plays an important role in the removal of foredunes at the study site. Given the fact that the frequency of intense storms in the vicinity of Ireland is forecast to increase within the next century, a scientific understanding of barrier response to such events is critical to inform sound management practices. Copyright © 2016 John Wiley & Sons, Ltd.     

The direction of fluid flow during contact metamorphism of siliceous carbonate rocks: new data for the Monzoni and Predazzo aureoles,northern Italy,and a global review

Periclase formed in siliceous dolomitic marbles during contact metamorphism in the Monzoni and Predazzo aureoles, the Dolomites, northern Italy, by infiltration of the carbonate rocks by chemically reactive, H₂O-rich fluids at 500 bar and 565-710 °C. The spatial distribution of periclase and oxygen isotope compositions is consistent with reactive fluid flow that was primarily vertical and upward in both aureoles with time-integrated flux ~5,000 and ~300 mol fluid/cm² rock in the Monzoni and Predazzo aureoles, respectively. The new results for Monzoni and Predazzo are considered along with published studies of 13 other aureoles to draw general conclusions about the direction, amount, and controls on the geometry of reactive fluid flow during contact metamorphism of siliceous carbonate rocks. Flow in 12 aureoles was primarily vertically upward with and without a horizontal component directed away from the pluton. Fluid flow in two of the other three was primarily horizontal, directed from the pluton into the aureole. The direction of flow in the remaining aureole is uncertain. Earlier suggestions that fluid flow is often horizontal, directed toward the pluton, are likely explained by an erroneous assumption that widespread coexisting mineral reactants and products represent arrested prograde decarbonation reactions. With the exception of three samples from one aureole, time-integrated fluid flux was in the range 10²-10⁴ mol/cm². Both the amount and direction of fluid flow are consistent with hydrodynamic models of contact metamorphism. The orientation of bedding and lithologic contacts appears to be the principal control over whether fluid flow was either primarily vertical or horizontal. Other pre-metamorphic structures, including dikes, faults, fold hinges, and fracture zones, served to channel fluid flow as well.     

Simplifying the interpretation of continuous time models for spatio-temporal networks

Autoregressive and moving average models for temporally dynamic networks treat time as a series of discrete steps which assumes even intervals between data measurements and can introduce bias if this assumption is not met. Using real and simulated data from the London Underground network, this paper illustrates the use of continuous time multilevel models to capture temporal trajectories of edge properties without the need for simultaneous measurements, along with two methods for producing interpretable summaries of model results. These including extracting ‘features’ of temporal patterns (e.g. maxima, time of maxima) which have utility in understanding the network properties of each connection and summarising whole-network properties as a continuous function of time which allows estimation of network properties at any time without temporal aggregation of non-simultaneous measurements. Results for temporal pattern features in the response variable were captured with reasonable accuracy. Variation in the temporal pattern features for the exposure variable was underestimated by the models. The models showed some lack of precision. Both model summaries provided clear ‘real-world’ interpretations and could be applied to data from a range of spatio-temporal network structures (e.g. rivers, social networks). These models should be tested more extensively in a range of scenarios, with potential improvements such as random effects in the exposure variable dimension.

     

Creating the taste of place in the United States: can we learn from the French?

In the United States, there is a growing awareness of the implications of our globalized food system, a system that incorporates all manner of agriculture, food distribution, food processing and transformation, and consumption. The ever increasing distance between where our food is produced and where it is consumed has helped spur a movement to develop a system of place based foods. Right now multiple models are in play, including farmers markets, community supported agriculture, and the localvore movement. This article will do a close examination of another model from France, the French system of appellation d’origine contrôlée (AOC); nationally regulated by the French Ministry of Agriculture it supports and protects foods and drinks with unique links to particular territories. The AOC system is based on geographically distinct and historically specific food and drink found throughout France. By closely examining one AOC product—Comté cheese produced in the rural agricultural region in Jura—the authors consider the possibilities for an AOC-style system in the United States.     

Climate-change impacts on sagebrush habitat and West Nile virus transmission risk and conservation implications for greater sage-grouse

Greater sage-grouse (Centrocercus urophasianus) are threatened by loss of sagebrush habitat and the spread of West Nile virus throughout much of their range in North America; yet, future impacts of climate change on these potential stressors have not been addressed. Here, we aim to quantify the potential impacts of climate change on the distribution of climatically suitable habitat for sagebrush and on transmission risk for West Nile virus in the eastern portion of the species’ range. We used Maxent to model the current and future climatically suitable habitat for two dominant sagebrush species in the study area, and we used a degree-day model to predict future West Nile virus transmission risk under likely climate-change scenarios. Our models suggest that areas with the highest future suitability for sagebrush habitat will be found in southwestern Wyoming and north-central Montana. The degree-day model suggests that greater sage-grouse in western portions of the study area, which are generally higher in elevation than where West Nile virus currently occurs, will see increasing risk of transmission in the future. We developed a spatially explicit map of suggested management actions based on our predictions that will aid in conservation of the species into the coming decades.