Geochemistry and tectonic setting of Tertiary volcanism in the Güvem area, Anatolia, Turkey

Detailed field mapping in the Güvem area in the Galatia province of NW Central Anatolia, Turkey, combined with K–Ar dating, has established the existence of two discrete Miocene volcanic phases, separated by a major unconformity. The magmas were erupted in a post-collisional tectonic setting and it is possible that the younger phase could be geodynamically linked to the onset of transtensional tectonics along the North Anatolian Fault zone. The Early Miocene phase (18–20 Ma; Burdigalian) is the most voluminous, comprising of over 1500 m of potassium-rich intermediate-acid magmas. In contrast, the Late Miocene volcanic phase (ca. 10 Ma; Tortonian) comprises a single 70-m-thick flow unit of alkali basalt. The major and trace element and Sr–Nd isotope compositions of the volcanics suggest that the Late Miocene basalts and the parental mafic magmas to the Early Miocene series were derived from different mantle sources. Despite showing some similarities to high-K calc-alkaline magma series from active continental margins, the Early Miocene volcanics are clearly alkaline with higher abundances of high field strength elements (Zr, Nb, Ti, Y). Crustal contamination appears to have enhanced the effects of crystal fractionation in the petrogensis of this series and some of the most silica-rich magmas may be crustal melts. The mantle source of the most primitive mafic magmas is considered to have been an asthenospheric mantle wedge modified by crustally-derived fluids rising from a Late Cretaceous–Early Tertiary Tethyan subduction zone dipping northwards beneath the Galatia province. The Late Miocene basalts, whilst still alkaline, have a Sr–Nd isotope composition indicating partial melting of a more depleted mantle source component, which most likely represents the average composition of the asthenosphere beneath the region.     

Book reviews

AN AUSTRALIAN DICTIONARY OF ENVIRONMENT AND PLANNING by A. Gilpin. 16 × 24 cm, xvi and 271 pages. Oxford University Press: Melbourne 1990 (ISBN 0 19 554806 X) $A60.00 (hard).

CONTINENT IN CRISIS: A Natural History of Australia by D. Smith, 13 × 20 cm, xii and 201 pages. Penguin: Melbourne 1990 (ISBN 0 14 011169 7) $A14.99 (soft).

THE END OF NATURE by B. McKibben. 14 × 22 cm, xi and 212 pages. Viking: London 1990 (ISBN 0 670 82877 7) $A29.99 (hard); distributed by Penguin Books.

THE FATE OF THE FOREST: Developers, Destroyers and Defenders of the Amazon by S. Hecht and A. Cockburn. 13 × 20 cm, xiii and 349 pages. Penguin: London (ISBN 0 14 013382 8) $A16.99 (soft).

ENVIRONMENT, AID AND REGIONALISM IN THE SOUTH PACIFIC (Pacific Research Monograph No. 22) by J. Carew‐Reid. 17 × 25 cm, xii and 185 pages. National Centre for Development Studies, Australian National University: Canberra 1989 (ISBN 0 7315 0673 1) $A25.00 (soft).

NEW SEEDS AND POOR PEOPLE by M. Lipton with R. Longhurst. 14 × 21 cm, xiv and 473 pages, Unwin Hyman: London 1989 (ISBN 0 04 45326 4) $A39.95 (soft).

CLIMATE CHANGE AND WORLD AGRICULTURE by M. Parry. 15 × 23 cm, xv and 157 pages. Earthscan: London 1990 (ISBN 1 85383 065 8) £9.95 (soft).

INTRODUCTION TO WORLD VEGETATION (Second Edition) by A. S. Collinson. 14 × 21 cm, x and 325 pages. Unwin Hyman: London 1988 (ISBN 0 04 581 030 3) $A95.00 (hard); (ISBN 0 04 581 031 1) $A39.95 (soft).

OCEANS OF LIFE OFF SOUTHERN AFRICA edited by A. I. L. Payne and R. J. M. Crawford. 22 × 29 cm, xii and 380 pages. Vlaeberg: Cape Town 1989 (ISBN 0 947461 01 9) $US30.00 plus $US5.00 postage (hard).

KARST GEOMORPHOLOGY AND HYDROLOGY by D. Ford and P. Williams. 15 × 23 cm, xv and 601 pages. Unwin Hyman: London 1989 (ISBN 0 04 551106 3) $A79.95 (soft).

ENVISIONING INFORMATION by E. R. TUFTE. 22 × 78 cm, 126 pages. Graphics Press: Cheshire, CT 1990 $US48.00 (hard). Available from Graphics Press, Box 430, Cheshire, Connecticut, 06410, USA.

A GUIDE TO REMOTE SENSING: Interpreting Images of the Earth by S. A. Drury. 22 × 27 cm, viii and 199 pages. Oxford University Press: Oxford 1991 (ISBN 0 19 854495 2) $A44.95 (soft).

THE CAINOZOIC IN AUSTRALIA: A Re‐appraisal of the Evidence (Special Publication No. 18) edited by M. A. J. William, P. De Deckker and A. P. Kershaw. 17 × 25 cm, x and 346 pages. Geological Society of Australia Inc: Sydney 1991 (ISBN 0 909869 76 6) $A60.00 (non‐members), $A40.00 (members) (soft).

MONSOONAL AUSTRALIA: Landscape, Ecology and Man in the Northern Lowlands edited by C. D. Haynes, M. G. Ridpath and M. A. J. Williams. 20 × 29 cm, xii and 231 pages. Balkema: Rotterdam 1991 (ISBN 90 6191 638 0) $A85.25 (hard).

SOILS: THEIR PROPERTIES AND MANAGEMENT: A Soil Conservation Handbook for New South Wales edited by P. E. V. Charman and B. W. Murphy. 21 × 27 cm, xix and 363 pages. Sydney University Press: Sydney 1991 (ISBN 0 424 00183 7) $A39.95 (soft).

VEGETATION (Atlas of Australian Resources, Third Series, Volume 6) by Australian Surveying and Land Information Group. 30 × 43 cm, 64 pages. Australian Surveying and Land Information Group: Canberra 1990 (ISBN 0 642 14993 3) $A39.95 (soft).

THE ATLAS OF NEPAL IN THE MODERN WORLD by M. Sill and J. Kirkby. 27 × 22 cm, 160 pages. Earthscan: London 1991 (ISBN 1 85383 032 1) £37.50 (hard).

DEVELOPMENT IN PRACTICE: Paved With Good Intentions by D. Porter, B. Allen and G. Thompson. 15 × 23 cm. Routledge: London 1990 (ISBN 0 415 16626 3) $A27.95 (soft); distributed by The Law Book Co.

CHINA'S SPATIAL ECONOMY: Recent Developments and Reforms edited by G. J. R. Linge and D. K. Forbes. 15 × 22 cm, xiii and 225 pages. Oxford University Press: Hong Kong 1991 (ISBN 0 19 585296 6) $A29.95 (hard).     

The arrival rate of severe storms off the east coast of Canada: Research note

Abstract

Modern structural analysis techniques are heavily dependent upon statistical methods. The determination of design loads involves the calculation of long‐return period environmental parameters such as the 100‐year wind speed or the 100‐year wave height. One way in which to do this is to use the theory of compound distributions rather than the usual extreme value theory. Of critical importance, however, is the determination of which probability distributions to use. It is shown in this paper that the arrival rate of storms on Canada's East Coast is Poisson distributed and, therefore, that compound distributions may be used to calculate long return‐period environmental parameters.     

Arthropod types from Sparth Bottoms in the Howard Collection (Rochdale Museum Service)

Rochdale Museum Service holds a large collection of fossils from the important Carboniferous site of Sparth Bottoms (Lancashire, UK; Middle Coal Measures). Several of these are type specimens donated by Harold Howard in 1939. These objects were stored in the museum basement for several decades, and were thought to have been lost. The types are the holotype of the scorpion Eobuthus holti Pocock, 1911 and the holotype of the crustacean Anthrapalaemon grossarti var. holti Woodward, 1911a. These species were not named after Howard, because the describers thought that Fred Holt was the rightful collector. The holotype of the myriapod Euphoberia woodwardi Baldwin, 1911 (put into synonymy with Palaeosoma robustum Baldwin, 1911) is known to have originally been in the collection, but was not located in a recent survey.     

Sulfide Inhibition of Nitrate Removal in Coastal Sediments

Microbial nitrate (NO₃⁻) removal via denitrification (DNF) at high sulfide (H₂S) concentrations was compared in sediment from a coastal freshwater pond in a developed area that receives salt-water influx during storm events, and a saline pond proximal to an undeveloped estuary. Sediments were incubated with added SO₄²⁻ (1,000 μg per gram dry weight basis (gdw)) to determine whether acid volatile sulfides (AVS) were formed. DNF in the sediments was measured with NO₃–N (300 μg gdw⁻¹) alone, and with NO₃–N and H₂S (1,000 μg S²⁻ gdw⁻¹). SO₄²⁻ addition to the freshwater sediments resulted in AVS formation (970 ± 307 μg S gdw⁻¹) similar to the wetland with no added SO₄²⁻ (986 ± 156 μg S gdw⁻¹). DNF rates measured with no added H₂S were greater in the freshwater than the wetland site (10.6 ± 0.6 vs. 6.4 ± 0.1 μg N₂O–N gdw⁻¹ h⁻¹, respectively). High H₂S concentrations retained NH₄–N in the undeveloped wetland and retained NO₃–N in the developed freshwater site, suggesting that potential salt-water influx may reduce the ability of the freshwater sediments to remove NO₃–N.