The First Hop: Use of Beaufort Sea Deltas by Hatch-Year Semipalmated Sandpipers

River deltas along Alaska’s Beaufort Sea coast are used by hatch-year semipalmated sandpipers (Calidris pusilla) after leaving their terrestrial natal sites, but the drivers of their use of these stopover sites on the first “hop” of fall migration are unknown. We quantified sandpiper temporal distribution and abundance as related to food resources at three river deltas during the beginning of their fall migration (post-breeding period) to compare the habitat quality among these deltas. We conducted population counts, sampled invertebrates, and captured birds to collect blood samples from individuals for triglyceride and stable isotope analyses to determine fattening rates and diet. Patterns of sandpiper and invertebrate abundance were complex and varied among deltas and within seasons. River deltas were used by sandpipers from late July to late August, and peak sandpiper counts ranged from 1000 to 4000 individuals, of which 98% were hatch-year semipalmated sandpipers. Isotopic signatures from blood plasma samples indicated that birds switched from a diet of upland tundra to delta invertebrate taxa as the migration season progressed, suggesting a dependence on delta invertebrates. Despite differences in diet among deltas, we found no differences in fattening rates of juvenile sandpipers as indicated by triglyceride levels. The number of sandpipers was positively associated with abundance of Amphipoda and Oligochaeta at the Jago and Okpilak-Hulahula deltas; an isotopic mixing model indicated that sandpipers consumed Amphipoda and Oligochaeta at Jago, mostly Chironomidae at Okpilak-Hulahula and Spionidae at Canning. Regardless of the difference in sandpiper diets at the Beaufort Sea deltas, their similar fattening rates throughout the season indicate that all of these stopover sites provide a critical food resource for hatch-year sandpipers beginning their first migration.     

Hydrothermal fracture controlled vein type uranium mineralization in the Paleoproterozoic Bijawar Group of rocks,Sonrai basin,Lalitpur district,U.P. – Fresh findings from subsurface borehole data

Sonrai basin, located along the southwestern margin of Bundelkhand Granite-Gneiss Complex (BGC) is known for its base metal and phosphorite mineralization. Uranium mineralization of appreciable grade and thickness was reported in Pisnari block in the northern part of this basin during sub-surface exploration activity in 1976-97. This was in the form of uranium-bitumin association within fractures in the carbonate-terrigenous sediments of Gorakalan shale, Rohini carbonate and Bandai sandstone of Sonrai Formation of Bijawar Group. Similar mineralization was also noted within the lower chloritic shale member of Solda Formation of the same Group. During subsequent drilling activity at a later phase (2005-09), uranium rich zones within Rohini carbonate and chloritic shale members were corroborated by the interception of mineralized bands in two boreholes drilled near Pisnari. Petrographic study of radioactive core samples reveal that uranium mineralization is closely associated with globular carbonaceous matter and sulphides along the fractures. Uranium is either adsorbed in carbonaceous matter or occurs as ultrafine inclusions of coffinite within carbonaceous matter. An additional phase of secondary uranium mineral (uranophane) is also noted in one of the boreholes. The uranium minerals, in association with sulphides, fill up moderately dipping fractures (approximately 15o towards North) which are oblique to the core axis of the inclined borehole and thus, the mineralization is characterized as hydrothermal fracture-controlled vein type mineralisation. C-HN- S analysis of carbonaceous matter occurring in close association with the uranium minerals reveal heterogeneity in composition with respect to carbon and sulfur. The present paper aims at discussing the geological, petrological and radiometric aspects of this mineralization, so as to enhance the understanding of the same.     

An approach to the modeling of viscoelastic damage. Application to the long‐term creep of gypsum rock materials

A three‐dimensional phenomenological model is developed to describe the long‐term creep of gypsum rock materials. The approach is based on the framework of continuum damage mechanics where coupling with viscoelasticity is adopted. Specifically, a local damage model based on the concept of yield surface is proposed and deeply investigated. Among the many possibilities, we choose in this work its coupling with a generalized Kelvin–Voigt rheological model to formulate the whole behavior. Long‐term as well as short‐term relaxation processes can be integrated in the model by means of as many as necessary viscoelastic processes. The numerical discretization is described for an easy integration within a finite element procedure. Finally, a set of numerical simulations is given to show the possibilities of the presented model. It shows good agreement with some experimental results found in the literature. Copyright © 2012 John Wiley & Sons, Ltd.     

Resolving the bulk δN values of ancient human and animal bone collagen via compound-specific nitrogen isotope analysis of constituent amino acids

Stable nitrogen isotope analysis is a fundamental tool in assessing dietary preferences and trophic positions within contemporary and ancient ecosystems. In order to assess more fully the dietary contributions to human tissue isotope values, a greater understanding of the complex biochemical and physiological factors which underpin bulk collagen δ¹⁵N values is necessary. Determinations of δ¹⁵N values of the individual amino acids which constitute bone collagen are necessary to unravel these relationships, since different amino acids display different δ¹⁵N values according to their biosynthetic origins. A range of collagen isolates from archaeological faunal and human bone (n = 12 and 11, respectively), representing a spectrum of terrestrial and marine protein origins and diets, were selected from coastal and near-coastal sites at the south-western tip of Africa. The collagens were hydrolysed and δ¹⁵N values of their constituent amino acids determined as N-acetylmethyl esters (NACME) via gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The analytical approach employed accounts for 56% of bone collagen nitrogen. Reconstruction of bulk bone collagen δ¹⁵N values reveals a 2‰ offset from bulk collagen δ¹⁵N values which is attributable to the δ¹⁵N value of the amino acids which cannot currently be determined by GC-C-IRMS, notably arginine which comprises 53% of the nitrogen unaccounted for (23% of the total nitrogen). The δ¹⁵N values of individual amino acids provide insights into both the contributions of various amino acids to the bulk δ¹⁵N value of collagen and the factors influencing trophic position and the nitrogen source at the base of the food web. The similarity in the δ¹⁵N values of alanine, glutamate, proline and hydroxyproline reflects the common origin of their amino groups from glutamate. The depletion in the δ¹⁵N value of threonine with increasing trophic level indicates a fundamental difference between the biosynthetic pathway of threonine and the other amino acids. The δ¹⁵N value of phenylalanine does not change significantly with trophic level, reflecting its conservative nature as an essential amino acid, and thus represents the isotopic composition of the nitrogen at the base of the food web. Δ¹⁵N_Glu-Phe values in particular are shown to reflect trophic level nitrogen sources within a food web. In relation to the reconstruction of ancient human diet the contribution of marine and terrestrial protein are strongly reflected in Δ¹⁵N_Glu-Phe values. Differences in nitrogen metabolism are also shown to have an influence upon individual amino acid δ¹⁵N values with Δ¹⁵N_Glu-Phe values emphasising differences between the different physiological adaptations. The latter is demonstrated in tortoises, which can excrete nitrogen in the form of uric acid and urea and display negative Δ¹⁵N_Glu-Phe values whereas those for marine and terrestrial mammals are positive. The findings amplify the potential advantages of compound-specific nitrogen isotope analysis in the study of nitrogen flow within food webs and in the reconstruction of past human diets.     

Genetic reinterpretation of crystallographicintergrowths of jacobsite andhausmannite from natural assemblages

Summary Crystallographic intergrowths of jacobsite and hausmannite (vredenburgite) occur in association with braunite in the Precambrian Sausar Group of rocks, India, that were metamorphosed under 600-700°C and P 6 kb. Quartz, hematite, rhodochrosite and a later hausmannite may occasionally occur as minor associates. Detailed characterization of the intergrown phases reveals that hausmannite lamellae, oriented in 4 or 5 crystallographic directions in the jacobsite host, show a wide variation in thickness and tapered intersections at low angles. The lamellae may be locally deformed. Analytical data reveal that the composition of natural hausmannite and jacobsite in the intergrowths cannot be approximated within the system Fe₃O₄ -Mn₃O₄, as has been conventionally done. These really belong to the Fe₂O₃-Mn₃O₄ subsystem. In the two phase intergrowths, hausmannite is depleted and the jacobsite is enriched in Fe in higher grade rocks. Mineral associations and petrographic considerations suggest that the jacobsite-hausmannite intergrowth originated through prograde decarbonation-oxidation reactions of a carbonatic precursor in an unbuffered X CO₂ situation, but f O₂ was held between hematite-magnetite and bixbyite-hausmannite buffers at the ambient physical conditions of metamorphism. Subsequent oxidation yielded a strong oxygenbuffering assemblage jacobsite, hausmannite, braunite, hematite and quartz. This study negates the commonly held idea that hausmannite jacobsite crystallographic intergrowth (vredenburgite) originates through unmixing of a high ([ldvredenburgite) originates through unmixing of a high temperature spinel_ss temperature spinel_ss during cooling.

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Genetische Reinterpretation der kristallographischen Verwachsungen von Jakobsit und Hausmannit in natürlichen Vorkommen

Zusammenfassung Kristallographische Verwachsungen von Jakobsit und Hausmannit (Vredenburgit) treten in Verbindung mit Braunit in Gesteinen der präkambrischen Sausargruppe in Indien auf. Die Gesteine wurden bei Drucken von ca. 6 kbar und Termperaturen von 600–700°C metamorphosiert. Quarz, Hämatit, Rhodochrosit, und Hausmannit als Spätphase treten gelegentlich als untergeordnete Gemengteile auf. Hausmannit-Lamellen, die in vier oder fünf kristallographischen Richtungen in Jakobsit orientiert sind, haben sehr unterschiedliche Durchmesser und bilden versetzte Zwickel in kleinem Winkel mit dem Jakobsit. Die Lamellen können lokal deformiert sein. Analytische Daten zeigen, daß die Zusammensetzung von natürlichem Hausmannit und Jakobsit in Verwachsungen nicht, wie bisher angenommen, in dem System Fe₃O₄-Mn₃O₄ dargestellt werden kann. Diese Verwachsungen gehören vielmehr in das Fe₂O₃-Mn₃O₄ System. In höher-gradigen metamorphen Gesteinen ist Fe in zwei-phasigen Verwachsungen im Hausmannit ab- und im Jakobsit angereichert. Die Mineralzusammensetzung und petrographische Gesichtspunkte lassen darauf schließen, daß die Jakobsit/Hausmannit Verwachsung durch prograde Dekarbonatisierung/Oxydationsreaktion eines karbonatischen Vorläufers in einem nicht gepufferten X CO₂ Milieu entstanden ist. F O₂ wurde durch Hämatit-Magnetit und Bixbyit-Hausmannit Puffer unter den gegebenen physikalischen Bedingungen der Metamorphose stabil gehalten. Eine nachfolgende Oxydation führte zu einer starken Sauerstoff-puffernden Assoziation von Jakobsit, Hausmannit, Braunit, Hämatit und Quarz. Diese Untersuchungen widerlegen die allgemein verbreitete Ansicht, daß die kristallographische Verwachsung von Hausmannit und Jakobsit (Vredenburgit) durch Entmischung eines Hochtemperatur-Spinells während der Abkühlung entstanden ist.

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With 1 figure     

IGU Commission on Health and Developement

The International Geographical Union Reports

IGU Commission on Population Geography     

Occurrence of thorite and radioactive zircon in syenite pegmatite,North of Ashwaraopet,Khammam district,Andhra Pradesh,India

This paper reports the occurrence of thorite and confirms the earlier find of radioactive zircon by Subbarao, Murali and others from syenite pegmatite in the Vinayakapuram-Kunavaram alkaline belt in the Khammam district of Andhra Pradesh, India. Thorite has also been found as residual concentrations in soil overlying the pegmatite.     

Environmental Correlates of Growth and Stable Isotopes in Intertidal Species Along an Estuarine Fjord

Production and resource use by intertidal taxa were studied in the estuarine fjord of Puget Sound, Washington, USA. Along nearly 100 km, salinity is similar, and intertidal habitat and immersion time were kept consistent, thus allowing a focus on other environmental variables such as temperature and resource availability that could influence growth. Primary producers (ulvoid and fucoid macroalgae) and suspension feeders (oysters and barnacles) were transplanted on three beaches in each of three regions and assessed for individual-level growth, carbon and nitrogen ratios, and stable isotopes. In most transplants, δ¹³C and C/N showed no regional variation but δ¹⁵N was enriched up-estuary. Among environmental variables, chlorophyll a, total suspended solids, and particulate organic matter had small and/or inconsistent regional variation, but temperature was higher up-estuary. For the most intensively studied species (Pacific oyster, Crassostrea gigas) transplanted four times over 2 years, seasonal and regional variation in growth were best predicted by temperature rather than resource availability. Growth rates continued to increase into Totten Inlet, a shallow finger inlet at the head of Puget Sound. As indicators of environmental conditions, the growth and tissue chemistry of intertidal study taxa affirm that sources and amounts of resources show no strong gradients along this estuarine fjord, and they also support temperature as a key factor for performance, with species-specific responses. Higher temperatures may also have community-level impacts, given prior evidence linking beach temperatures to reduced intertidal diversity and biomass into Puget Sound.     

Diverse mode of phosphatic rocks in the environs of Proterozoic Bijawar and Sonrai basins and its relevance to uranium mineralisation — A case study from central India

The Bundelkhand massif comprising a variety of Archean-Paleoproterozoic granitoids along with low grade and high-grade metamorphites and located in the centre of the Indian Plate, underwent extension during Paleoproterozoic period, resulting in the formation of homotaxial intracratonic Bijawar and Sonrai basins in the south and Gwalior basin in the northern margin. The Bijawar and Sonrai basins are typified by their characteristic sediments and basic volcanic rocks. A feature common to both the basins, is the overwhelming occurrence of phosphatic rocks across stratigraphy and lithotype in the Bijawar basin and its confinement to the basal part of the sedimentary column in Sonrai basin. Most of these rocks are primarily of marine origin, and later subjected to periods of repeated phosphatic redistribution. Multiple episodes of such phosphatisation culminates in the proliferation and enrichment of phosphate in the upper Bijawar rocks of Bijawar basin (phosphatic breccia of Hirapur-Mardeora) and lower Bijawar rocks of Sonrai basin (phosphatic breccia of Lalitpur). Apart from these established phosphatic rocks in both the basins, quartz reefs occurring in the basement as well as the lower Bijawar Malhera Chert Breccia Formation in Bijawar basin at places are endowed with anomalously high phosphate content. The phosphatic component in all the lithotypes is in the form of apatite varying in form from microcrystalline to well formed coarser crystal aggregate comprising cement, veins and botroidal encrustations. Irrespective of its spatial, temporal and paragenetic position, it invariably registers weak to moderate radioactivity, due to the presence of uranium within it, as is evident from microprobe data. Although intra-grain and inter-grain distribution of uranium is found to be random and erratic, in general, it is observed that uranium tends to be enriched in the later generation phosphates, due to secondary process of dissolution and reprecipitation. The present paper, with fresh inputs from petrological, geochemical, minerochemical and isotope data pertaining to apatite from all these diverse units, not only explores the already established association of uranium and phosphate in these basins but also provides new insight to the phosphatic quartz reef within the basement and the phosphatised arenaceous sediments of the lower Bijawar Formation.