First published in 1999 for the Coalfield Geology Council of New South Wales by New South Wales Department of Mineral Resources PO Box 536 St Leonards NSW 1590 ,.>, 6'; ;.. , . .> . Cover photog~~:';'fhe~asiifeitrs&im,:.fh'e topmost seam within the Boolaroo Formation-Newcastle-Coal Measures 1exposed in the Westside open cut mine, 26 km south west of Newcastle. Spine: Lithic, pebble to granule conglomerate of the Late Permian Wallala I Formation-Black Jack Group in the Gunnedah Basin. (Magnification 3.5X) Disclaimer Whereas all care has been taken in producing this Bulletin, the Department accepts no responsibility where in is incorrect or omitted. The Bulletin IS a collection of articles produced by members of the Coalfield Geology Council of New South Wales. Inclusion of these articles in the Bulletin does not imply Governmental or Departmental endorsement. I Bibliographic referencing Refer to an individual paper in this way: TADROSN.Z. 1999. Permian stratigraphy of the Gunnedah Basin, pp 120- 152. In Coalfield Geolog~Council of New South Wales, Bulletin 1 ,vi + 152 pp. Refer to the whole document as: Coalfield Geology Council of New South Wales 1999. Bulletin 1, 152 pp. ISSN 1442-55 13 0 Copyright Coalfield Geology Council of New South Wales, 1999. ,G Copyright of individual papers remains with the Authors. reserved No part of th~spubllcat~on may be reproduced, stored In a retr~evalsystem or transmitted any form ny means, electron~c,mechan~cal, photocopy~ng, facs~m~le, recording or otherwise. except as allowed law, without of the Council. COALFIELD GEOLOGY COUNCIL OF NSW The Coalfield Geology Council of New South Wales is a joint GovernmentJlndustry body which was established in 1961 to provide a forum for discussion and dissemination of detailed knowledge on the various coalfields of New South Wales and geological issues of interest to the coal mining industry. The Council facilitates the establishment and revision of codes, standards and guidelines for the practice of coalfield and mining geology. The Council is responsible for the revision of the stratigraphy for the various coalfields in the State and assisting industry with issues such as environmental geology, longwall mining geology, engineering geology, coal resources and reserves, education, coal geology and mine safety and coal seam methane. The Council also provides a mechanism for effective industry/government consultation on all matters involving coalfield and mining geology and draws its membership not only from industry and government but also research organisations and tertiary institutions. ili COALFIELD GEOLOGY COUNCIL OF NEW SOUTH WALES Chairman : R. Doyle, Dartbrook Coal Company Secretary: M. Armstrong, New South Wales Department of Mineral Resources Working Parties (at the time of initial preparation of these papers) Computer-based resource/resewe estimates B. Mullard Guide to systematic evaluation of open cut coal reserves J. Beckett R. Davis B. Mullard B. Preston C. Weber Environmental considerations for coal geologists M. Fahey G. Holt R. Nolan B. Mullard C. Ward C. Wootton Permian stratigraphy of the Gunnedah Basin N. Z. Tadros Stratigraphy of the Greta Coal Measures, Muswellbrook J. Beckett Anticline area, Hunter Coalfield H. Binnekamp J. Rogis G. Salter Coal seam nomenclature application in the Hunter Coaijield J. Beckett H. Binnekamp J. Rogis I G. Salter I Revision of the stratigraphy ofthe Newcastle Coalfield J. Brunton J. Edwards R. Rigby M. Ives C. Tobin ,I C. Weber I Stratigraphy and terminology of the Southern Coalfield B. Agrali 1 M. Armstrong J. Bamberry J. Goodall J. Hanes A. Hutton B. Kirby W. Vlahovic 1 Production Team Coordinator: N.Z. Tadros I Editors: J.R. Stewart 1 R.A. Facer I Word processing/layout: D. Lum I H. Martino Cartography: Z. Drugakov N.Z. Tadros A.C. Hutton Cover Design: V. Grant 4 Postal Address Coalfield Geology Council of New South Wales c/- New South Wales Department of Mineral Resources PO Box 536 St Leonards NSW 1590 Australia iv TABLE OF CONTENTS Computer-based resource /reserve estimates .................................................................................. 1 B. Mullard Guide to systematic evaluation of open cut coal reserves ..........................................................8 B. Mullard; B. Preston; R. Davis; J. Beckett & C.R. Weber Environmental considerations for coal geologists .................... .. ............ ...... ................17 H.N. Bowman; R. C.Nolan; B. Mullard; C. Ward; P. Wootton; G.Holt; M Fahey & C.R. Weber Permian stratigraphy of the Gumedah Basin ...................................................................................40 NZ. Tadros Stratigraphy of the Greta Coal Measures, Muswellbrook Anticline area, Hunter Coalfield ............ 94 JBeckett; H. Binnekamp; J. Rogis & G.Salter Coal seam nomenclature application in the Hunter Coalfield ......................................................... 103 J. Beckett Revision of the stratigraphy of the Newcastle Coal Measures ........................................................ 113 M Ives; J. Brunton; J. Edwards; R. Rigby; C. Tobin & C.R. Weber Stratigraphy and terminology for the Solrthern Coalfield .................................................................120 A.C. Hutton & J. Bamberry COMPUTER-BASED RESOURCE/RESERVE ESTIMATES B. Mullard Introduction ..................................... .., ..................................................................................1 Geometric methods ................................................................................................................2 Distance weighting methods ...................................................................................................4 Kriging ................................................................................................................................... 5 Trend surface analysis techniques ......................................................................................... 5 Computer intensive methods .................................................................................................6 Conclusions ............................................................................................................................7 Selected bibliography ........................... ., ......................................................................... 7 INTRODUCTION points or a mathematical technique for interpolating points. The advent of computers has revolutionised many areas of geology. Computers have become an Contour Plans essential element in analysing the vast amount of A contour plan is a visual representation of the data generated by exploration programs. In addition, various attributes which make up a geological model, the high cost of drilling and sampling a deposit eg thickness, structure, ash, etc. In this regard a demands that as much information as possible be contour plan should accurately reflect the underlying squeezed from the data. model. Routines which smooth or alter the contour In coal geology, computers have revolutionised the plans without changing the underlying model should, data acquisition and storage phases of an exploration in general, be avoided. program. They have provided the means to create an interactive model of a coal deposit from which Surface reserves can be delineated, extraction schedules The term surface is used in this report to describe generated and coal quality variations analysed. the plot of a variable in three dimensional space. For The topic of geological modelling and reserve example the thickness of a seam across a deposit estimation is a very large one and it is not possible can be plotted as a single surface with the variable to cover the full range of issues in a single paper. thickness component represented by the z axis As a result this paper concentrates on what is direction values. considered to be the key determining factor for a geological model, the interpretation method. WHAT IS A COMPUTER-BASED RESOURCE/RESERVE The objective of this report is to examine briefly the ESTIMATE? process of generating a geological model by The terms 'resource' and 'reserve' can, in their most examining the properties of some of the better known basic form, be defined as follows interpolation techniques. It is hoped that this will give A 'resource' refers to in situ coal which may have geologists a better understanding of how modelling potential for use systems work and thus lead to better geological A 'reserve' is that part of a 'resource' which it is models. planned to mine and for which such planning has DEFINITIONS been undertaken (Australian Code for Reporting Coal Resources and Reserves, June 1997 - but In order to avoid confusion it is necessary to define is under review) briefly a number of terms which are used in this The problem is that there is no direct method (apart paper. from mining the deposit) for determining these figures. Geologists must therefore attempt to estimate Geological Model resource and reserve figures by sampling the deposit. In its most general sense a geological model is a In many cases the geologist must try to extrapolate representation of the geology of a deposit. A model the properties of millions of tonnes of coal from a total represents, but is not itself, reality. A model allows sample weight of only a few kilograms. questions to be answered about a deposit which will The steps taken in arriving at a reserve or resource enable a better understanding of the behavior of the estimate can be summarised