An investigation of diet in early Anglo-Saxon England using carbon and nitrogen stable isotope analysis of human bone collagen

The principal aim of this work is to investigate whether protein sources in human diets in early Anglo-Saxon (5th-7th century AD) England varied with geographic location, or with respect to age or sex. The methodology used was analysis of δ¹⁵N and δ¹³C in human bone collagen from 76 adult skeletons from a total of 18 different cemeteries located in inland, riverine and coastal environments. In order to control for the possible effects of socio-economic status on diet, only high status individuals, as identified by grave goods, were studied. Data were analysed using statistical manipulation of the raw results and using IsoSource (Phillips and Gregg, 2003), a mathematical treatment which models the composition of the protein part of human diets using bone stable isotope ratios when the isotopic values for potential protein sources are known or can reasonably be inferred. The results suggest that protein sources varied little according to geographic location and that terrestrial foods dominated at all locations. However there were some subtle patterns. Slightly elevated δ¹³C in skeletons from coastal locations, and δ¹⁵N in those from riverine sites may indicate that communities in these locations made greater use of marine and freshwater resources respectively. If this is correct then it demonstrates that 5th-7th century communities made some use of wild resources even within a predominantly agrarian economy. In general the analysis of the raw data and the IsoSource results were mutually supportive, and this work demonstrates the value of this twin-pronged approach to analysis of human bone stable isotope data.     

Instrument Transfer as Knowledge Transfer in Neurophysiology: François Magendie's (1783–1855) Early Attempts to Measure Cerebrospinal Fluid Pressure

François Magendie's (1783–1855) experimental model for measuring blood pressure in animals, which he developed in 1838, had a major impact on French physiology in the nineteenth century, especially upon Etienne-Jules Marey (1830–1904) in Paris. In due course it was also adopted by other European investigators, such as the Leipzig physiologist Carl Ludwig (1816–1895), and by clinicians who developed it into a major measuring tool. Historians of science, however, have paid hardly any attention to Magendie's further laboratory investigations conducted with the assistance of Jean-Louis Marie Poiseuille's (1799–1869) sphygmomètre (blood pressure meter). After having used the apparatus to conduct his experiments on a variety of blood vessels, Magendie also applied the sphygmomètre in 1840 to the ventricular system of the brain in order to measure cerebrospinal fluid (CSF) pressure. But the scope of this new procedure had yet to be defined: the new measuring device invited many speculative interpretations about the meaning of CSF flow for the physiology of the ventricular system in healthy and diseased brain function. As such, Magendie's experiments produced phenomena in very heterogeneous knowledge areas, and CSF measurement was situated at the interface of quite disparate investigative spaces regarding the structure and function of the brain. In his textbook Leçons sur les Fonctions et les Maladies du Système Nerveux (Lectures on the Functions and Diseases of the Nervous System), Magendie described extending application of the measuring “apparatus of Poiseuille” from blood vessels to parts of the brain. The instrument thus became something of a liquidodynamomètre (liquor dynamometer), that paved the way for later applications, including (after 1896) diagnostic intracranial pressure (ICP) measurement by Theodor Kocher (1841–1917) and Harvey Cushing (1869–1939). The current paper focuses on the experimental contingencies that prompted the instrument transfer in Magendie's laboratory and opened up new epistemological perspectives for research in neurophysiology.     

Making space for fish: the regional,network and fluid spaces of fisheries certification

In this paper, we examine the multiple spatialities of Marine Stewardship Council (MSC) certifications. The MSC uses its ecolabelling scheme to promote sustainable fisheries management; its logo may be used on the products of certified fisheries. The certification process involves the definition of a ‘fishery’. This involves the designation of boundaries around a particular location. While these boundaries suggest exclusivity for each fishery, these regional spaces are also entwined in the MSC's network, whereby they are viewed relationally. The utility of areal boundaries is also rendered problematic by the materiality of the seas: coastlines change, fish swim, water moves and ships travel. To operate its scheme successfully, the MSC has to recognise this spatial fluidity, acknowledging the rupture of boundaries and the movement of actors. We argue that attention to a multiplicity of spatialities helps direct attention to the role of non-humans in the acting out of hybrid geographies.     

Weakening processes in thrust faults: insights from the Monte Perdido thrust fault (southern Pyrenees,Spain)

The Monte Perdido thrust fault (southern Pyrenees) consists of a 6‐m‐thick interval of intensely deformed clay‐bearing rocks. The fault zone is affected by a pervasive pressure solution seam and numerous shear surfaces. Calcite extensional‐shear veins are present along the shear surfaces. The angular relationships between the two structures indicate that shear surfaces developed at a high angle (70°) to the local principal maximum stress axis σ₁. Two main stages of deformation are present. The first stage corresponds to the development of calcite shear veins by a combination of shear surface reactivation and extensional mode I rupture. The second stage of deformation corresponds to chlorite precipitation along the previously reactivated shear surfaces. The pore fluid factor λ computed for the two deformation episodes indicates high fluid pressures during the Monte Perdido thrust activity. During the first stage of deformation, the reactivation of the shear surface was facilitated by a suprahydrostatic fluid pressure with a pore fluid factor λ equal to 0.89. For the second stage, the fluid pressure remained still high (with a λ value ranging between 0.77 and 0.84) even with the presence of weak chlorite along the shear surfaces. Furthermore, evidence of hydrostatic fluid pressure during calcite cement precipitation supports that incremental shear surface reactivations are correlated with cyclic fluid pressure fluctuations consistent with a fault‐valve model.     

The republic of san marino

Abstract

Flushing time (T_f) is an important factor which determines the hydrological, ecological and chemical functioning of lakes. However, it has never been calculated on the basis of underground supply for Polish Lakes. Due to their high altitudes, the lakes in question constitute a distinctive group among the ??czna-W?odawa Lakes. They are located in the borderland of the Cretaceous Che?m Hills (part of the Polish Uplands) and Polish Lowland. The quantity of the underground water supply was one of the key factors which make these lakes so distinctive. During periods of low precipitation, water shortages occurred in the lakes, especially Pniówno and Syczyńskie. The ??czna-W?odawa Lakes are commonly distinguished, among other Polish water bodies, as super-passive due to their water flushing time (>10 years). However, the average flushing time of the water in lakes Tarnowskie, Chuteckie, Pniówno and Syczyńskie, based on the underground supply, amounted to 606, 211, 54 and 79 days, respectively. The territorial conditions (e.g. geologic structure of catchment areas or thickness of unsaturated and saturated zones) were the most important factors that determined seasonal fluctuations of the supply to the lakes.     

Temperature‐dependent Li isotope ratios in Appalachian Plateau and Gulf Coast Sedimentary Basin saline water

Lithium (Li) concentrations of produced water from unconventional (horizontally drilled and hydraulically fractured shale) and conventional gas wells in Devonian reservoirs in the Appalachian Plateau region of western Pennsylvania range from 0.6 to 17 mmol kg^?1, and Li isotope ratios, expressed as in δ⁷Li, range from +8.2 to +15‰. Li concentrations are as high as 40 mmol kg^?1 in produced waters from Plio‐Pleistocene through Jurassic‐aged reservoirs in the Gulf Coast Sedimentary Basin analyzed for this study, and δ⁷Li values range from about +4.2 to +16.6‰. Because of charge‐balance constraints and rock buffering, Li concentrations in saline waters from sedimentary basins throughout the world (including this study) are generally positively correlated with chloride (Cl), the dominant anion in these fluids. Li concentrations also vary with depth, although the extent of depth dependence differs among sedimentary basins. In general, Li concentrations are higher than expected from seawater or evaporation of seawater and therefore require water–mineral reactions that remove lithium from the minerals. Li isotope ratios in these produced waters vary inversely with temperature. However, calculations of temperature‐dependent fractionation of δ⁷Li between average shale δ⁷Li (?0.7‰) and water result in δ⁷Li_water that is more positive than that of most produced waters. This suggests that aqueous δ⁷Li may reflect transport of water from depth and/or reaction with rocks having δ⁷Li lighter than average shale.     

Fracture‐focused fluid flow in an acid and redox‐influenced system: diagenetic controls on cement mineralogy and geomorphology in the Navajo Sandstone

Differential cement mineralogy is influenced by depositional textures, structural deformation, pore fluid chemistry, and ultimately influences landscape evolution by introducing heterogeneities in erodibility. In Southern Utah, the region West of the Kaibab uplift known as Mollies Nipple (Mollies) in Grand Staircase‐Escalante National Monument exhibits a complex history of fluid–sediment interactions, which has resulted in a localized zone of anomalous diagenetic iron sulfate (jarosite) mineralogy in a well‐exposed dune–interdune deposit within the Navajo Sandstone. Mineralogy and geochemistry of cements within this region are examined using reflectance and imaging spectroscopy, field investigations, microscopy, and whole‐rock geochemical analyses. These data show that the in‐situ jarosite cement is localized to a plane along the highest ridge of the butte, providing an armor along with other secondary cements, which controls the butte's geomorphic evolution. The jarosite cement is associated with other mineralogies suggesting that the sulfate was one of the latest fluid‐related precipitates in the paragenetic sequence. It was preceded by a regional bleaching event, precipitation of clay cements, some localized concretionary iron oxide precipitation, and formation of deformation bands. At least one generation of dense iron oxide mineralization is associated with cataclastic brittle deformation predating the sulfate precipitation. Trace element geochemistry of cements shows certain metal oxide populations associated with extremely high (>2000 ppm) arsenic values. We interpret the combination of spatial mineral distribution, observed paragenetic sequence, and trace element geochemistry to suggest this region experienced acid sulfate diagenesis along fracture‐controlled fluid conduits related to weathering of proximal, unidentified, sulfides, or H₂S associated with deep source beds. Jarosite is highly soluble, and its presence suggests that abundant fluid flow has not occurred in this region since its formation. This terminal cement‐forming event must have occurred prior to sandstone exhumation and erosion to form the current extreme landscape at Mollies. This site exhibits the influence that fluid geochemistry, sedimentary mineralogy, and structural fabric have on geomorphic evolution.     

Stable isotope chemistry,population histories and Late Prehistoric subsistence change in the Aleutian Islands

Aleut population history has been a topic of debate since the earliest archaeological investigations in the region. In this paper, we use stable isotope chemistry to evaluate the hypothesis that two distinct groups of people, Paleo- and Neo-Aleut, occupied the eastern Aleutians after 1000 BP. This study focuses on 80 sets of directly dated eastern Aleutian burial assemblages from Chaluka midden, Shiprock Island and Kagamil Island. We use a linear mixing model informed by isotopic analysis of two large Aleut faunal assemblages to address temporal and spatial variation in human carbon and nitrogen stable isotope data from these sites. The patterning we report addresses both Aleut demographic and economic prehistory, illustrating a transition in both at ca. 1000 BP. Our results suggests that the Chaluka diet, dominated by Paleo-Aleut inhumations, differed in both trophic level and foraging location from the other two sites for much of the past 4000 years. Trends in our data also suggest that individuals from Shiprock and Kagamil burial caves, primarily Neo-Aleuts, had enough access to higher trophic level foods to differentiate their bone chemistries from those buried in Chaluka midden. These trends in diet, recently reported genetic differences, as well as the introduction of novel mortuary practices at ca. 1000 BP, suggest that Neo-Aleuts do represent a population new to the eastern Aleutians.     

Geophysical and geochemical evidence of large scale fluid flow within shallow sediments in the eastern Gulf of Mexico,offshore Louisiana

We analyse the fluid flow regime within sediments on the Eastern levee of the modern Mississippi Canyon using 3D seismic data and downhole logging data acquired at Sites U1322 and U1324 during the 2005 Integrated Ocean Drilling Program (IODP) Expedition 308 in the Gulf of Mexico. Sulphate and methane concentrations in pore water show that sulphate–methane transition zone, at 74 and 94 m below seafloor, are amongst the deepest ever found in a sedimentary basin. This is in part due to a basinward fluid flow in a buried turbiditic channel (Blue Unit, 1000 mbsf), which separates sedimentary compartments located below and above this unit, preventing normal upward methane flux to the seafloor. Overpressure in the lower compartment leads to episodic and focused fluid migration through deep conduits that bypass the upper compartment, forming mud volcanoes at the seabed. This may also favour seawater circulation and we interpret the deep sulphate–methane transition zones as a result of high downward sulphate fluxes coming from seawater that are about 5–10 times above those measured in other basins. The results show that geochemical reactions within shallow sediments are dominated by seawater downwelling in the Mars‐Ursa basin, compared to other basins in which the upward fluid flux is controlling methane‐related reactions. This has implications for the occurrence of gas hydrates in the subsurface and is evidence of the active connection between buried sediments and the water column.     

Thermochemical and bacterial sulfate reduction in the Cambrian and Lower Ordovician carbonates in the Tazhong Area,Tarim Basin,NW China: evidence from fluid inclusions,C, S,and Sr isotopic data

Petrographic features, C, O, S, and Sr isotopes were determined, and fluid inclusions (FI) were analyzed on various stages of vug‐ and fracture‐fillings from the Cambrian and Lower Ordovician reservoirs in the Tazhong area, Tarim basin, NW China. The aim was to assess the origin of pyrite and anhydrite and the processes affecting sulfur during diagenesis of the carbonates. Pyrite from seven wells has δ³⁴S values from ?22‰ to +31‰. The pyrites with low δ³⁴S values from ?21.8‰ to ?12.3‰ were found close to fracture‐filling calcites with vapor‐liquid double‐phase aqueous fluid inclusions homogenization temperatures (FI‐Th) from 55.7 to 73.2°C, salinities from 1.4wt% to 6.59wt% NaCl equiv and δ¹³C values from ?2.3‰ to ?14.2‰, indicating an origin from bacterial sulfate reduction by organic matter. Other sulfides with heavier δ³⁴S values may have formed by thermochemical sulfate reduction (TSR) during two episodes. The earlier TSR in the Middle and Lower Cambrian resulted in pyrites and H₂S having δ³⁴S values from 30 to 33‰, close to those of bedded anhydrite and oilfield water (approximately 34‰). The later TSR is represented by calcites with δ¹³C values as light as ?17.7‰ and FI‐Th of about 120–145°C, and pyrite and H₂S with δ³⁴S values close to those of the Upper Cambrian burial‐diagenetic anhydrite (between +14.8‰ and +22.6‰). The values of the anhydrite are significantly lighter than contemporary seawater sulfates. This together with ⁸⁷Sr/⁸⁶Sr values of anhydrite and TSR calcites from 0.7091 to 0.7125 suggests a source from the underlying Ediacaran seawater sulfate and detrital Sr contribution.