Vol. 21, No. 4

Contents: What a Mess! The FMLA, Collective Bargaining and Attendance Control Plans, by Jeanne M. Vonhof and Martin H. Malin Recent Developmentshttps://scholarship.kentlaw.iit.edu/iperr/1080/thumbnail.jp

Vol. 21, No. 4

Contents: What a Mess! The FMLA, Collective Bargaining and Attendance Control Plans, by Jeanne M. Vonhof and Martin H. Malin Recent Developmentshttps://scholarship.kentlaw.iit.edu/iperr/1080/thumbnail.jp

A test of the biogenicity criteria established for microfossils and stromatolites on quaternary tufa and speleothem materials formed in the “Twilight zone” at Caerwys, UK

© 2015, Mary Ann Liebert, Inc. The ability to distinguish the features of a chemical sedimentary rock that can only be attributed to biology is a challenge relevant to both geobiology and astrobiology. This study aimed to test criteria for recognizing petrographically the biogenicity of microbially influenced fabrics and fossil microbes in complex Quaternary stalactitic carbonate rocks from Caerwys, UK. We found that the presence of carbonaceous microfossils, fabrics produced by the calcification of microbial filaments, and the asymmetrical development of tufa fabrics due to the more rapid growth of microbially influenced laminations could be recognized as biogenic features. Petrographic evidence also indicates that the development of "speleothem-like" laminae was related to episodes of growth interrupted by intervals of nondeposition and erosion. The lack of any biogenic characteristics in these laminae is consistent with their development as a result of variation in the physicochemical parameters that drive calcite precipitation from meteoric waters in such environmental settings

Fluid evolution and ore deposition in the Harz Mountains revisited: isotope and crush-leach analyses of fluid inclusions

Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe

Fluid evolution and ore deposition in the Harz Mountains revisited: isotope and crush-leach analyses of fluid inclusions

Hydrothermal fluid flow along fault zones in the Harz Mountains led to widespread formation of economic vein-type Pb–Zn ore and Ba–F deposits during the Mesozoic. We reconstruct the fluid flow system responsible for the formation of these deposits using isotope ratios (δ2H and δ18O) and anion and cation contents of fluid inclusions in ore and gangue minerals. Building forward on extensive studies in the 1980s and 1990s, our new geochemical data reveal that seawater evaporation brines, which most likely originated from Zechstein evaporites, descended deeply into Paleozoic rocks to leach metals at depth. In Jurassic times, these metal-rich brines episodically recharged along fault zones and mixed with shallow crustal H2S-bearing brines. Primarily in the Upper Harz Mountains, this mixing system led to the formation of economic Pb–Zn–Cu mineralization, which locally shows banded textures with alternations of sulfide minerals and quartz or carbonate (mostly calcite). In the Middle and Lower Harz Mountains, Zechstein-derived brines interacted with K- and F-bearing basement rocks and/or magmatic rocks to deposit fluorite mineralization upon ascent in the Upper Cretaceous. The proposed model of mineralizing fluids originating as (evaporated) seawater has been shown to hold for numerous basin-hosted base-metal sulfide and fluoride deposits elsewhere in Europe

Carbon, nitrogen, and oxygen stable isotopes in modern tooth enamel: A case study from Gorongosa National Park, central Mozambique

The analyses of the stable isotope ratios of carbon (delta C-13), nitrogen (delta N-15), and oxygen (delta O-18) in animal tissues are powerful tools for reconstructing the feeding behavior of individual animals and characterizing trophic interactions in food webs. Of these biomaterials, tooth enamel is the hardest, most mineralized vertebrate tissue and therefore least likely to be affected by chemical alteration (i.e., its isotopic composition can be preserved over millions of years), making it an important and widely available archive for biologists and paleontologists. Here, we present the first combined measurements of delta C-13, delta N-15, and delta O-18 in enamel from the teeth of modern fauna (herbivores, carnivores, and omnivores) from the well-studied ecosystem of Gorongosa National Park (GNP) in central Mozambique. We use two novel methods to produce high-precision stable isotope enamel data: (i) the "oxidation-denitrification method," which permits the measurement of mineral-bound organic nitrogen in tooth enamel (delta N-15(enamel)), which until now, has not been possible due to enamel's low organic content, and (ii) the "cold trap method," which greatly reduces the sample size required for traditional measurements of inorganic delta C-13(enamel) and delta O-18(enamel) (from >= 0.5 to <= 0.1 mg), permitting analysis of small or valuable teeth and high-resolution serial sampling of enamel. The stable isotope results for GNP fauna reveal important ecological information about the trophic level, dietary niche, and resource consumption. delta N-15(enamel) values clearly differentiate trophic level (i.e., carnivore delta N-15(enamel) values are 4.0 parts per thousand higher, on average, than herbivores), delta C-13(enamel) values distinguish C-3 and/or C-4 biomass consumption, and delta O-18(enamel) values reflect local meteoric water (delta O-18(water)) in the park. Analysis of combined carbon, nitrogen, and oxygen stable isotope data permits geochemical separation of grazers, browsers, omnivores, and carnivores according to their isotopic niche, while mixed-feeding herbivores cannot be clearly distinguished from other dietary groups. These results confirm that combined C, N, and O isotope analyses of a single aliquot of tooth enamel can be used to reconstruct diet and trophic niches. Given its resistance to chemical alteration, the analysis of these three isotopes in tooth enamel has a high potential to open new avenues of research in (paleo)ecology and paleontology.info:eu-repo/semantics/publishedVersio

Sympatric woodland Myotis bats form tight-knit social groups with exclusive roost home ranges

Background: The structuring of wild animal populations can influence population dynamics, disease spread, and information transfer. Social network analysis potentially offers insights into these processes but is rarely, if ever, used to investigate more than one species in a community. We therefore compared the social, temporal and spatial networks of sympatric Myotis bats (M. nattereri (Natterer's bats) and M. daubentonii (Daubenton's bats)), and asked: (1) are there long-lasting social associations within species? (2) do the ranges occupied by roosting social groups overlap within or between species? (3) are M. daubentonii bachelor colonies excluded from roosting in areas used by maternity groups? Results: Using data on 490 ringed M. nattereri and 978 M. daubentonii from 379 colonies, we found that both species formed stable social groups encompassing multiple colonies. M. nattereri formed 11 mixed-sex social groups with few (4.3%) inter-group associations. Approximately half of all M. nattereri were associated with the same individuals when recaptured, with many associations being long-term (>100 days). In contrast, M. daubentonii were sexually segregated; only a quarter of pairs were associated at recapture after a few days, and inter-sex associations were not long-lasting. Social groups of M. nattereri and female M. daubentonii had small roost home ranges (mean 0.2 km2 in each case). Intra-specific overlap was low, but inter-specific overlap was high, suggesting territoriality within but not between species. M. daubentonii bachelor colonies did not appear to be excluded from roosting areas used by females. Conclusions: Our data suggest marked species- and sex-specific patterns of disease and information transmission are likely between bats of the same genus despite sharing a common habitat. The clear partitioning of the woodland amongst social groups, and their apparent reliance on small patches of habitat for roosting, means that localised woodland management may be more important to bat conservation than previously recognised