http://www.sciencedirect.com/science/article/pii/S1674987115000663

Mantle xenocrysts from early Triassic kimberlite pipes from Kharamai,Ary-Mastakh and Kuranakh fields in the Anabar shield of Siberia revealing similar compositional trends were studied to estimate the superplume influence on the subcratonic lithosphere mantle(SCLM).Pressure-temperature(PT) reconstructions using monomineral thermobarometry for 5 phases show division of the SCLM beneath the Kharamai field into 6 units:pyroxenitic Fe-rich(1-2 GPa) and Mg-rich(2-3 GPa) layers;middle with two levels of Gar-Sp pyroxenites at ~3 and 4-5 GPa;Gar-dunite-harzburgites ~4.5-6.5 GPa subjected to Ilm-Px vein metasomatism;and a Mg-rich dunite lower part.In the Anabar shield(Ary-Mastakh,Dyuken and Kuranakh fields) mantle lithosphere is composed of three large units divided into two parts:upper part with amphiboles and phlogopite;two levels of pyroxenites and eclogites at 3 and 4 GPa,and a lower part composed of refertilized dunites.Diagrams showing P-Fe~#Gar clusters for garnets and omphacites illustrate the differences between SCLM of these localities.Differences of Triassic SCLM from Devonian SCLM are in simple layering;abundance of Na-Cr-amphiboles and metasomatism in the upper SCLM part,thick pyroxenite-eclogite layer and lower part depletion,heated from SCLM base to 5.0 GPa.Kharamai mantle clinopyroxenes represent three geochemical types:(1) harzburgitic with inclined linear REE,HFSE troughs and elevated Th,U;(2) lherzolitic or pyroxenitic with round TRE patterns and decreasing incompatible elements;(3) eclogitic with Eu troughs,Pb peak and high LILE content.Calculated parental melts for garnets with humped REE patterns suggest dissolution of former Cpx and depression means Cpx and garnets extraction.Clinopyroxenes from Ary-Mastakh fields show less inclined REE patterns with HMREE troughs and an increase of incompatible elements.Clinopyroxenes from Kuranakh field show flatter spoon-like REE patterns and peaks in Ba,U,Pb and Sr,similar to those in ophiolitic harzburgites.The PT diagrams for the mantle sections show high temperature gradients in the uppermost SCLM accompanied by an increase of P-Fe~#Ol upward and slightly reduced thickness of the mantle keel of the Siberian craton,resulting from the influence of the Permian-Triassic superplume,but with no signs of delamination.     

Extreme supersaturation of nitrous oxide in a poorly ventilated Antarctic lake

Lake Bonney, a permanently ice-covered Antarctic lake, has a middepth maximum N2O concentration of 41.6 micromoles N (>580,000% saturation with respect to the global average mixing ratio of N2O) in its east lobe, representing the highest level yet reported for a natural aquatic system. Atmospheric N2O over the lake was 45% above the global average, indicating that this lake is an atmospheric source of N2O. Apparent N2O production (ANP) was correlated with apparent oxygen utilization (AOU), and denitrification was not detectable, implying that nitrification is the primary source for this gas. The slope of a regression of ANP on AOU revealed that potential N2O production per unit of potential O2 consumed in the east lobe of Lake Bonney is at least two orders of magnitude greater than reported for the ocean. The maximum yield ratio for N2O [ANP/(NO2(-) + NO3-)] in Lake Bonney is 26% (i.e. 1 atom of N appears in N2O for every 3.9 atoms appearing in oxidized N), which exceeds previous reports for pelagic systems, being similar to values from reduced sediments. Areal N2O flux from the lake to the atmosphere is >200 times the areal flux reported for oceanic systems; most of this gas apparently enters the atmosphere through a small moat that occupies approximately 3% of the surface of the lake and exists for approximately 10 weeks in summer.     

Book reviews

A WORLD IN CRISIS? Geographical Perspectives (second edition) edited by R. J. Johnston and P. J. Taylor. 15 x 23 cm, x and 371 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 16271 2) $A34.95 (soft).

INTEGRATED RURAL DEVELOPMENT PROGRAMMES IN PAPUA NEW GUINEA: External Aid and Provincial Planning (IASER Monograph No 28) by R. Crittenden and D. A. M. Lea, 17 x 24 cm, xv and 132 pages. Papua New Guinea Institute of Applied Social and Economic Research and Department of Geography and Planning, University of New England: Armidale 1989 (ISBN 9980 75 018 9).

ACCOMMODATING INEQUALITY: Gender and Housing by Sophie Watson. 14 x 21 cm, x and 157 pages. Allen & Unwin: Sydney 1988 (ISBN 0 04 320209 2) $A 14.95 (soft).

A SHORT HISTORY OF GEOMORPHOLOGY by K. J. Tinkler. 14 x 22 cm, xviii and 317 pages, Croom Helm: London 1985 (ISBN 0 7099 2441 0) $A49.95 (hard).

PATHWAYS IN GEOLOGY: Essays in Honour of

Edwin Sherbon Hills edited by R. W. Le Mai‐

tre. 25 x 19 cm, viii and 463 pages. Basil

Blackwell: Melbourne 1989 (ISBN

0731682416) $A110.00 (hard).

CHANGING THE FACE OF THE EARTH: Culture, Environment, History by I. G. Simmons. 17 x 24 cm, xiii and 487 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 16351 4) $A49.95 (soft).

PLANNED TO DEATH: The Annihilation of a Place Called Howdendyke by J. D. Porteous. 16 x 24 cm, xiii and 254 pages. Manchester University Press: Manchester 1989 (ISBN 0 7190 2831 0) £35.00 (hard).

A SOCIAL ATLAS OF DARWIN: 1986. Census of Population and Housing by J. Taylor and D.

Jaensch. 21 x 29 cm, and 66 pages. Australian Bureau of Statistics and North Australia Research Unit: Darwin 1989 (ISBN 0 642 143322 6).

ATLAS OF DEMOGRAPHIC CHANGE IN THE SOUTH EAST REGION OF NEW SOUTH WALES 1861–1991 by Terry G. Birtles and Jane E. Gordon. 21 x 29 cm, v and 141 pages. Canberra College of Advanced Education: Belconnen 1989 (ISBN 0 85889 355 5 $A40.00 (soft).

LABOUR ADJUSTMENT IN METROPOLITAN REGIONS by P. S. Morrison 15 x 21 cm, ix and 254 pages. Victoria University Press: Wellington 1989 (ISBN 0 86473 190 6) SA25.00 (soft).

AUSTRALIAN REGIONAL DEVELOPMENTS: Readings in Regional Experiences, Policies and Prospects (Australian Regional Developments No. 10) edited by B. Higgins and K. Zagorski. 17 x 25 cm. xi and 260 pages. AGPS Press: Canberra 1989 (ISBN 0 644 0935).

SOUTH AUSTRALIAN MANUFACTURING IN TRANSITION edited by T. J. Mules. 15 x 21 cm, vii and 188 pages. Wakefield Press (for Centre of South Australian Economic Studies): Adelaide 1989 (ISBN 909591 74 1) $A24.95 (soft).

COUNTERURBANIZATION: The Changing Pace’ and Nature of Population Deconcentration edited by A. G. Champion. 16 x 24 cm, xxii and 266 pages. Edward Arnold: London 1989 (ISBN 0 7131 6614 2) £27.00 (hard).

THE HUMANE CITY: Cities as if People Matter by J. R. Short. 15 x 22 cm, 167 pages. Basil Blackwell: Oxford 1989 (ISBN 0 631 15824 3) $A27.95 (soft).

THE TORRES STRAIT: People and History (revised edition) by J. Singe. 13 x 19 cm, xviii and 261 pages. University of Queensland Press: St Lucia 1989 (first published in 1979) (ISBN 0 7022 2232 1) $A19.95 (soft).

HAWKE'S LAW: The Politics of Mining and Aboriginal Land Rights in Australia by R. T. Libby. xxvii and 175 pages. University of Western Australia Press: Nedlands 1989 (ISBN 085564 301 1) $A25.00.

THE THIRD WORLD: States of Mind and Being edited by J. Norwine and A. Gonzales. 15 x 23 cm, xi and 275 pages. Unwin Hyman: Boston 1989 (ISBN 0 04 910121 8) $A39.95 (soft).

IRELAND: A Contemporary Geographical Perspective edited by R. W. G. Carter and A. J. Parker. 14 x 22 cm, xiv and 486 pages. Routledge: London 1989 (ISBN 0 415 00486 3) $A 120.00 (hard).     

Geochemistry of the Serifos calc-alkaline granodiorite pluton,Greece: constraining the crust and mantle contributions to I-type granitoids

International Journal of Earth Sciences - The Late Miocene (11.6–9.5 Ma) granitoid intrusion on the island of Serifos (Western Cyclades, Aegean Sea) is composed of syn- to...     

Determination of Incompatible Trace Elements in Mantle Clinopyroxenes by LA-ICP-MS: A Comparison of Analytical Performance with Established Techniques

Incompatible trace element abundances have been determined in mantle-derived clinopyroxenes by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) in a comparative study with established microanalytical and bulk techniques. Individual clinopyroxene grains were sampled for the laser ablation study from sieved mineral separate fractions, from which similar mineral grains had been previously extracted for microprobe (SIMS) and bulk (INAA and ID-TIMS) analysis. Mineral grains were ablated with variable degrees of surface spatial resolution (50-200 μm) in order to maximise ICP-MS analyte count rates and to improve detection limits. A comparison of results from the different techniques reveals that for the most homogeneous samples LA-ICP-MS can achieve excellent levels of agreement with other techniques (10%) and good precision for most of the studied elements (1-5% RSD). Variations in calculated concentrations by LA-ICP-MS confirm inter- and intra-mineral heterogeneity determined by SIMS, reflecting changes in sample composition and texture. The long-term reproducibility of the technique is shown by the consistency of results for one sample analysed on thirteen occasions over a period of nine months.     

Interviews and Questionnaires as Mixed Methods in Population Geography: TheCase of Lone Fathers in Newcastle,Australia

A mixed method approach was adopted to study the experiences of lonefathers, using a classic triangulation approach of interview and questionnaire data. This study utilised an empirical realist framework of scientific enquiry, with the ‘soft’ individual interview data seen as an adjunct to the ‘hard’ aggregate quantitative methods. A review of this study found that the interviews worked well as a pilot study in a classic mixed methods framework. The questionnaires provided a range of information about thecharacteristics of this group of lone fathers, but it was the interviews which provided astonishing depth on the causes of marital breakdown and post-marital conflict, and on the discourses and other structures which sustain social processes. In this study, the interview techniques could have been used differently, in a different framework of analysis (that of critical rather than empirical realism) without the support of other mixed methods.     

The Whitsunday Volcanic Province, Central Queensland, Australia: lithological and stratigraphic investigations of a silicic-dominated large igneous province

Contrary to general belief, not all large igneous provinces (LIPs) are characterised by rocks of basaltic composition. Silicic-dominated LIPs, such as the Whitsunday Volcanic Province of NE Australia, are being increasingly recognised in the rock record. These silicic LIPs are consistent in being: (1) volumetrically dominated by ignimbrite; (2) active over prolonged periods (40–50 m.y.), based on available age data; and (3) spatially and temporally associated with plate break-up. This silicic-dominated LIP, related to the break-up of eastern continental Gondwana, is also significant for being the source of >1.4×10⁶ km³ of coeval volcanogenic sediment preserved in adjacent sedimentary basins of eastern Australia.The Whitsunday Volcanic Province is volumetrically dominated by medium- to high-grade, dacitic to rhyolitic lithic ignimbrites. Individual ignimbrite units are commonly between 10 and 100 m thick, and the ignimbrite-dominated sequences exceed 1 km in thickness. Coarse lithic lag breccias containing clasts up to 6 m diameter are associated with the ignimbrites in proximal sections. Pyroclastic surge and fallout deposits, subordinate basaltic to rhyolitic lavas, phreatomagmatic deposits, and locally significant thicknesses of coarse-grained volcanogenic conglomerate and sandstone are interbedded with the ignimbrites. The volcanic sequences are intruded by gabbro/dolerite to rhyolite dykes (up to 50 m in width), sills and comagmatic granite. Dyke orientations are primarily from NW to NNE.The volcanic sequences are characterised by the interstratification of proximal/near-vent lithofacies such as rhyolite domes and lavas, and basaltic agglomerate, with medial to distal facies of ignimbrite. The burial of these near-vent lithofacies by ignimbrites, coupled with the paucity of mass wastage products such as debris-flow deposits indicates a low-relief depositional environment. Furthermore, the volcanic succession records a temporal change in: (1) eruptive styles; (2) the nature of source vents; and (3) erupted compositions. An early explosive dacitic pyroclastic phase was succeeded by a later mixed pyroclastic-effusive phase producing an essentially bimodal suite of lavas and rhyolitic ignimbrite. From the nature and distribution of volcanic lithofacies, the volcanic sequences are interpreted to record the evolution of a multiple vent, low-relief volcanic region, dominated by several large caldera centres.     

The Gove relict iron meteorite from Arnhem Land,Northern Territory,Australia

On February 24, 1979, a deeply oxidized mass of iron meteorite was excavated from bauxite at an open cut mine on the Gove Peninsula, Northern Territory, Australia. The meteorite, measuring 0.75–1 m in diameter and of unknown total weight, was found at coordinates 12°15.8′S, 136°50.3′E. On removal from the ground, the meteorite is reported to have disintegrated rapidly. A preliminary analysis at the mine laboratory reportedly gave 8.5 wt% Ni. A modern analysis of oxidized material gave Ni = 32.9, Co = 3.67 (both mg g^?1), Cr = 168, Cu = 195, Ga = 22.5, Ge = <70, As = 4.16, W = 1.35, Ir = 10.5, Pt = 21.2, Au = 0.672 (all μg g^?1), Sb = <150, and Re = 844 (both ng g^?1). Competent fragments of oxidized material retain a fine to medium Widmanstätten pattern with an apparent average bandwidth of 0.5 mm (range 0.2–0.9 mm in plane section). Primary mineralogy includes rare γ–taenite and daubréelite, and secondary minerals produced by weathering include awaruite (with up to 78.5 wt% Ni) and an, as yet, unnamed Cu‐Cr‐bearing sulfide with the ideal formula CuCrS₂ that is hitherto unknown in nature. Deep weathering has masked many of the features of the meteorite; however, the analysis normalized to the analyses of fresh iron meteorites favors chemical group IIIAB. The terrestrial age of the meteorite is unknown, although it is likely to be in the Neogene (2.5–23 Ma), which is widely accepted as the major period of bauxite formation in the Northern Territory of Australia. Gove is the second authenticated relict meteorite found in Australia.     

Decomposition of mangrove roots: Effects of location,nutrients, species identity and mix in a Kenyan forest

Mangrove trees may allocate >50% of their biomass to roots. Dead roots often form peat, which can make mangroves significant carbon sinks and allow them to raise the soil surface and thus survive rising sea levels. Understanding mangrove root production and decomposition is hence of theoretical and applied importance. The current work explored the effects of species, site, and root size and root nutrients on decomposition. Decomposition of fine (≤3 mm diameter) and coarse (>3 mm diameter, up to a maximum of ∼9 mm) roots from three mangrove species, Avicennia marina, Bruguiera gymnorrhiza and Ceriops tagal was measured over 12 months at 6 sites along a tidal gradient in Gazi Bay, Kenya. C:N and P:N ratios in fresh and decomposed roots were measured, and the effects on decomposition of root size and age, of mixing roots from A. marina and C. tagal, of enriching B. gymnorrhiza roots with N and P and of artefacts caused by bagging roots were recorded. There were significant differences between species, with 76, 47 and 44 % mean dry weight lost after one year for A. marina, B. gymnorrhiza and C. tagal respectively, and between sites, with generally slower decomposition at dryer, high tidal areas. N enriched B. gymnorrhiza roots decomposed significantly faster than un-enriched controls; there was no effect of P enrichment. Mixing A. marina and C. tagal roots caused significantly enhanced decomposition in C. tagal. These results suggest that N availability was an important determinant of decomposition, since differences between species reflected the initial C: N ratios. The relatively slow decomposition rates recorded concur with other studies, and may overestimate natural rates, since larger (10–20 mm diameter), more mature and un-bagged roots all showed significantly slower rates.