Ophiolitic and metamorphic rocks in the Percy Isles and Shoalwater Bay region,New England Fold Belt,central Queensland

Ophiolitic and metamorphic rocks of the eastern part of the New England Fold Belt in the Shoalwater Bay region and the Percy Isles are grouped in the Marlborough and Shoalwater terranes, respectively. Marlborough terrane units occur on South Island (Percy Isles) and comprise the Northumberland Serpentinite, antigorite serpentinite with rodingite and more silicic dykes and mafic inclusions, the Chase Point Metabasalt, some 800+ metres of pillow lava, and the intervening South Island Shear Zone containing fault‐bounded slices of mafic and ultramafic igneous rocks, schist, and volcaniclastic sedimentary rocks, and zones of mélange. The Shoalwater terrane, an ancient subduction complex, consists of the Shoalwater Formation greenschist facies metamorphosed quartz sandstone and mudstone on North East Island and on the mainland at Arthur Point, the Townshend Formation, amphibolite‐grade quartzite, schist and metabasalt on Townshend Island, and the Broome Head Metamorphics on the western side of Shoalwater Bay, upper amphibolite facies quartz‐rich gneiss. With the exception of a sliver emplaced onto the western Yarrol terrane, possibly by gravity sliding, Shoalwater terrane rocks show the effects of Late Permian polyphase deformation. The Shacks Mylonite Zone along the northwest edge of the Broome Head Metamorphics marks a zone of oblique thrusting and is part of the major Stanage Fault Zone. The latter is a northeast‐striking oblique‐slip dextral tear fault active during Late Permian west‐directed thrusting that emplaced large ultramafic sheets farther south. Marlborough terrane rocks were emplaced along the Stanage Fault Zone, probably from the arc basement on which rocks of the Yarrol terrane were deposited. Structural trends and the distribution of rock units in the Shoalwater Bay‐Percy Isles region are oblique to the overall structural trend of the northern New England Fold Belt, probably due to the presence of a promontory in the convergent margin active in this region in Devonian and Carboniferous time.     

Recent advances in isotopes as palaeolimnological proxies

Isotope geochemistry is an essential part of environmental and climate change research and over the last few decades has contributed significantly to our understanding of a huge array of environmental problems, not least in palaeolimnology and limnogeology. Here we describe some of the recent developments in the use of stable isotopes in palaeo-lake research. These are: better preparation, analysis, and interpretation of biogenic silica oxygen and silicon isotopes; extraction and characterisation of specific compounds such as leaf waxes and algal lipids for isotope analysis; determining the excess of ¹³C–¹⁸O bonds in clumped isotopes; and the measurement of multiple isotope ratios in chironomid chitin. These advances have exciting prospects and it will be interesting to see how these techniques develop further and consequently offer a real advancement in our science over the next decade.     

Biological data from sharks landed within the United Arab Emirates artisanal fishery

Landing site and market surveys of sharks landed along the Arabian Gulf coast of the United Arab Emirates were undertaken between October 2010 and September 2012 to obtain biological data from this artisanal fishery. Data were collected on the size and sex of 12 482 individuals representing 30 species. Maximum sizes of Carcharhinus sorrah, C. amblyrhynchoides and Hemipristis elongata were extended by at least 300?mm total length (TL) compared with published global maxima. The size at 50% maturity was determined for males of five species and this indicated that the males of smaller shark species (<1 000 mm maximum TL) in the fishery were largely mature. For many species, including Loxodon macrorhinus and Mustelus mosis, overall sex ratios were male-biased, indicating that sexual segregation is likely in those species. Furthermore, sex ratios for several species, such as Rhizoprionodon acutus, showed differences across seasons. Overall, the landings contained a high proportion of juveniles, causing concerns about the sustainability of this fishery. Biological parameters of a number of species differed from those recorded earlier for the region, demonstrating a need for additional local data collection to support the development of management measures.     

A numerical model for one‐dimensional simulation of stratospheric chemistry

Abstract

We describe a one‐dimensional (1‐D) numerical model developed to simulate the chemistry of minor constituents in the stratosphere. The model incorporates most of the chemical species presently found in the upper atmosphere and has been used to investigate the effect of increasing chlorofluorocarbon (CFC) emissions on ozone (O₃).

Our calculations confirm previous results that O₃ depletions in the 20–25 km region, the region of the O₃ maximum, are very sensitive to the relative abundances of Cl_x and NO_y in the lower stratosphere for high Cl_x amounts. The individual abundances of lower stratospheric Cl_x and NO_y amounts are very sensitive to upper tropospheric mixing ratios, which, in turn, are determined largely by surface input fluxes and heterogeneous loss processes. Thus the behaviour of column O₃ depletions at high Cl_x levels is greatly affected, albeit indirectly, by tropospheric processes. For high Cl_x levels the O_x flux from the stratosphere to the troposphere is dramatically reduced, leading to a large reduction in tropospheric O₃. Some of the variation between different published 1‐D model results is most likely due to this critical dependence of O₃ depletion on NO_y‐Cl_x ratios.

Model simulations of time‐dependent CFC effects on ozone indicate that if CFCs were to remain at constant 1980 emission rates while N₂O increased at 0.25% a^?1 and CH₄ increased at 1% a^?1, we could expect a 2.2% decrease in total column O₃ (relative to the 1980 atmosphere) by the year 2000. However, if CFC emission rates were to increase by 3% a^?1 (current estimates are 5–6% a^?1), we would predict a depletion of 2.7% by the year 2000. The calculations for times beyond the year 2000 suggest that the effects on total O₃ will begin to accelerate. If methyl chloroform emissions are added at 7% a^?1 (current estimates are 7–9% a^?1) to the above CFC‐N₂O‐CH₄ scenario we calculate total O₃ depletions by the year 2000 that are 41% larger than those calculated without. This suggests that if the emissions of methyl chloroform continue to increase at their present rate then methyl chloroform could have a significant effect upon total O₃.     

Abrupt Holocene climate change and potential response to solar forcing in western Canada

Several abrupt climate events during the Holocene, including the widely documented oscillation at 8.2 thousand years before present (ka), are attributed to changes in the North Atlantic thermohaline circulation. Additional mechanisms, such as interactions between atmospheric circulation, ice-sheet dynamics, and the influence of solar irradiance, also have been proposed to explain abrupt climatic events, but evidence remains elusive. This study presents evidence from multi-proxy analyses on the Holocene sediments of Eleanor Lake, interior British Columbia. Climatic inferences from our decadal-resolution record of biogenic silica (BSi) abundance are supported by changes in diatom and pollen assemblages from the same core and correlations with existing regional climate records. The BSi record reveals abrupt and persistent climatic shifts at 10.2, 9.3, and 8.5 ka, the latter two of which are coeval with major collapses of the Laurentide Ice Sheet. The record also reveals a short-term cooling at 8.2 ka that is distinct from the 8.5 ka event and similar in magnitude to several other late-Holocene coolings. BSi is correlated with solar-irradiance indices (r = 0.43–0.61), but the correlation is opposite in sign to that expected from direct solar forcing and weakens after 8 ka. Possible mechanisms causing the abrupt and persistent climate changes of the early Holocene include 1) sudden losses of ice and proglacial lake extent, causing a shift in the meridional structure of atmospheric circulation, 2) a possible link between solar minima and El Niño-like conditions that are correlated with warm spring temperature in interior British Columbia, and 3) the influence of solar irradiance variability on the position of the polar jet, possibly via effects on the strength of the glacial anticyclone.     

National-level factors affecting planned,public adaptation to health impacts of climate change

Our understanding of whether adaptive capacity on a national level is being translated into adaptation policies, programs, and projects is limited. Focusing on health adaptation in Annex I Parties to the UNFCCC, we examine whether statistically significant relationships exist between regulatory, institutional, financial, and normative aspects of national-level adaptive capacity and systematically measured adaptation. Specifically, we (i) quantify adaptation actions in Annex I nations, (ii) identify potential factors that might impact progress on adaptation and select measures for these factors, and (iii) calculate statistical relationships between factors and adaptation actions across countries. Statistically significant relationships are found between progress on adaptation and engagement in international environmental governance, national environmental governance, perception of corruption in the public sector, population size, and national wealth, as well as between responsiveness to health vulnerabilities, population size and national wealth. This analysis contributes two key early empirical findings to the growing literature concerning factors facilitating or constraining adaptation. While country size and wealth are necessary for driving higher levels of adaptation, they may be insufficient in the absence of policy commitments to environmental governance. Furthermore, governance and/or incentive frameworks for environmental governance at the national level may be an important indicator of the strength of national commitments to addressing health impacts of climate change.     

Chemical evolution of shallow playa groundwater in response to post-pluvial isostatic rebound, Honey Lake Basin, California–Nevada, USA

The 1,750-km² endorheic Honey Lake basin (California–Nevada, USA) was part of the 22,000-km² Pleistocene Lake Lahontan pluvial lake system which existed between 5,000 and 40,000 years BP. The basin consists of two subbasins separated by a low elevation divide. Groundwater in the western subbasin has a maximum total dissolved solids (TDS) content of only ～1,300 mg/L; however eastern subbasin groundwater has a maximum TDS of ～46,000 mg/L. This TDS distribution is unexpected because 94% of surface water TDS loading is to the western subbasin. In situ reactions and upwelling thermal groundwater contributing to groundwater chemistry were modeled using NETPATH. The TDS difference between the subbasins is attributed to post-Lake Lahontan isostatic rebound about 13,000 years ago. Prior to rebound the subbasins did not exist and the low point of the basin was in the eastern area where hydraulic isolation from the larger Lake Lahontan and frequent desiccation of the basin surface water resulted in evaporite mineral deposition in accumulating sediments. After rebound, the terminal sink for most surface water shifted to the western subbasin. Although most closed basins have not been impacted by isostatic rebound, results of this investigation demonstrate how tectonic evolution can impact the distribution of soluble minerals accumulating in shallow basins.     

Calcium isotope ratios in animal and human bone

Calcium isotopes in tissues are thought to be influenced by an individual’s diet, reflecting parameters such as trophic level and dairy consumption, but this has not been carefully assessed. We report the calcium isotope ratios (δ^44/42Ca) of modern and archaeological animal and human bone (n = 216). Modern sheep raised at the same location show 0.14 ± 0.08‰ higher δ^44/42Ca in females than in males, which we attribute to lactation by the ewes. In the archaeological bone samples the calcium isotope ratios of the herbivorous fauna vary by location. At a single site, the archaeological fauna do not show a trophic level effect. Humans have lower δ^44/42Ca than the mean site fauna by 0.22 ± 0.22‰, and the humans have a greater δ^44/42Ca range than the animals. No effect of sex or age on the calcium isotope ratios was found, and intra-individual skeletal δ^44/42Ca variability is negligible. We rule out dairy consumption as the main cause of the lower human δ^44/42Ca, based on results from sites pre-dating animal domestication and dairy availability, and suggest instead that individual physiology and calcium intake may be important in determining bone calcium isotope ratios.     

SHORT COMMUNICATION PLS FITS CLOSER THAN PCR

PLS1 regression is generally viewed as lying in between PCR and OLS regression.Proof is given thatthe coefficient of determination,R~2,for a PLS multivariate calibration model is at least as high as thatfor a PCR model with the same number of components.It appears that PLS can be linked to acorrelation-weighted polynomial regression of a constant response on the eigenvalues of the covariancematrix of the predictor variables.