Exploration In Australia Research Articles

Workshop Report and Discussion Paper: Geomagnetic Reference Fields; Base-Level and Diurnal Corrections to Aeromagnetic Data

Geomagnetic reference fields and corrections to aeromagnetic data were the subjects of a discussion workshop held in Canberra on 1st December 1987. The proceedings of the workshop that are most relevant to aeromagnetic exploration in Australia are summarized in this article and supplemented with our additional comments. An accompanying paper (Barton, this issue) provides a more detailed exposition on the derivation and applications of global and regional geomagnetic reference fields. Initial discussions centred on recent developments in global and regional (Australian) modelling of the geomagnetic field, and applications and limitations on the use of available models. Attention then turned to the aeromagnetic 'diurnal' correction problem, the use of base-station and tie-line crossovers for making 'diurnal' corrections, continental and oceanic induction effects, the relative merits of magnetic gradiometer surveys, and ramifications of the modern trend towards the use of rapid sampling (£10 second) and high sensitivity (sub-nanotesla) survey techniques. Investigations into the spatial variability of magnetic field fluctuations using magnetometer arrays are needed both on a regional scale and on a local scale. The proposed Australia-wide array of geomagnetic stations (AWAGS) experiment is an example of the former. New methods of presenting the results of such investigations are also needed, for example in the form of a set of 'base-station reliability' maps of the region.

Remote sensing for mineral exploration in Australia : Horsfall, C Aust MinV79, N3, March 1987, P23–31

Remote sensing for mineral exploration in Australia : Horsfall, C Aust MinV79, N3, March 1987, P23–31

Transient E.M. in Exploration for Massive Sulphides — A new Discovery

Transient E.M. represents a turning point in the application of geophysics to mineral exploration in Australia. It is a technique that can directly detect conductive massive sulphides at depths which have taken some of us by surprise and, perhaps, have not been readily accepted by the exploration industry. The method must be used with due regard to its limitations, but it has shortened the exploration odds quite dramatically in the search for massive sulphides in geologically prospective environments.

Groundwater helium surveys in mineral exploration in Australia

The potential for using groundwater helium surveys in exploration has been evaluated by conducting local and regional surveys in several mineralized and background areas in Australia. Dissolved helium contents decrease markedly upwards, particularly in the top 10–15m, due to degassing in attaining dynamic equilibrium with the atmosphere. Gradients of depth profiles are not uniform but because total concentration variations to 50m or more are commonly less than 10, whereas regional variations are 10 3–10 5, samples from the greatest constant depth possible below water-table are adequate for survey purposes. Helium concentrations in excess of the atmosphere equilibrium value of 0.044 μl He/l H 2O were found to be associated with uranium mineralization at Honeymoon (6.9–44.4 μl/l), Manyingee (0.08–1.68 μl/l), Bennett Well (9.9–29.5 μ/l) and the Stuart Shelf—Roxby Downs (910–2495 μl/l), with a carbonatite at Mt. Weld (0.18–13.6 μl/l), and with kimberlites at Wandagee (0.2–3.25 μl/l). No anomaly was associated with the shallow calcrete uranium deposit at Yeelirrie. However, equivalent or higher concentrations were found in groundwaters from unmineralized areas around these deposits, e.g. up to 85 μl/l at Manyingee—Bennett Well, to 215 μl/l at Yeelirrie and to 1525 μl/l, Stuart Shelf—Mt. Gunson. Similarly, helium in waters from stock wells near Mt. Weld appears to indicate the presence of the carbonatite but in a survey of a geologically similar area near Malcolm, equivalent anomalies were not related to carbonatite. Although the uranium (and thorium) mineralization is a significant source, high helium concentrations can arise by accumulation in groundwaters with long residence times and by leakage from deep sources, particularly granitoid basement. The concentration reached is also a function of the porosity and configuration of the aquifer and the permeability of the aquiclude to helium. These factors are more important in determining dissolved helium concentrations than the uranium and thorium contents of the rocks. However, the effects are not readily quantifiable, particularly in exploration areas where geology and hydrology are relatively unknown, hence helium groundwater data can be difficult if not impossible to interpret.

Oil Exploration in Australia: ABSTRACT

Oil Exploration in Australia: ABSTRACT

Geophysics in Australian mineral exploration

I review a variety of recent case histories illustrating the application of geophysics in mineral exploration in Australia. Geophysics is now an integral part of most programs. Examples are given of contributions by geophysics to all stages of mineral exploration, from regional area selection through to mine planning and development. Specific case histories summarized are as follows: (a) Olympic Dam copper‐uranium‐gold deposit, discovered using a conceptual genetic model and regional geophysical data; (b) Ellendale diamondiferous kimberlites, illustrating the use of low level, detailed airborne magnetics; (c) Ranger uranium orebodies, discovered by detailed airborne radiometric surveys; (d) geologic mapping near Mary Kathleen with color displays of airborne radiometric data; (e) mapping of lignite in basement depressions of the Bremer Basin, near Esperance, with INPUT; (f) White Leads, a lead‐zinc sulfide deposit discovered with induced polarization (IP) and TEM, near Broken Hill; (g) Hellyer, a lead‐zinc‐silver‐gold deposit discovered with UTEM; (h) application of geophysical logging near Kanmantoo; (i) Cowla Peak, a subbituminous steaming coal deposit mapped with ground TEM; and (j) Cook Colliery, where high‐resolution seismic reflection methods have successfully increased the workable reserves.

Book Reviews

Book reviewed in this article:Energy and Development in Kenya: Opportunities and Constraints Editors: Phil O'Keefe, Paul Raskin and Steve Bernow.The Use of Non‐conventional Water Resources in Developing Countries (Natural Resources/Water Series No. 14)Economics of Mineral Exploration in Australia: Guidelines for Corporate Planning and Government Policy, Authors: Brian W. Mackenzie and Michel L. Bilodeau.

Autobiographical Narrative of Residence and Exploration in Australia (1832-1839)

Autobiographical Narrative of Residence and Exploration in Australia (1832-1839)

The effect of deep weathering on geophysical exploration in Australia—A review

Abstract A long period of weathering of the Australian continent and a subdued tectonic history for much of it has produced an ancient deeply weathered mantle over large areas. This mantle has had the effect of reducing geophysical signals from buried targets and also increasing the background (geological) noise in the data. This is particularly so for electrical methods of exploration. Mathematical modelling for various methods is made more difficult. However, the development of more sophisticated instruments, some with microprocessor control, digital recording, filtering and automatic stacking of data and, in particular, the development of transient (pulse) electrical methods, has allowed much better separation of target from weathered overburden anomalies. The discoveries at Elura (NSW) and Roxby Downs (SA) of bodies at depths of 100 m and 350 m, respectively, are excellent examples of the type of exploration which will probably become more common. Magnetic survey remains the most generally useful geop...

An evaluation of electrical methods applied to petroleum exploration in Australia

The use of electrical prospecting methods for petroleum exploration has been under study for the past few years. Bipole-dipole and dipole-dipole induced polarization (IP) surveys have been tested over a number of oil and gas fields and prospects in the Denison Trough, and the Bowen, Cooper and Surat Basins. Self potential (SP) methods have also been tested over a number of prospects; the details of a computer-aided data acquisition system are the subject of another publication. Definite resistivity anomalies are seen over the fields. These are discussed with the induced polarization (chargeability) data. The data from two SP surveys show that significant negative anomalies occur above hydrocarbon deposits. From this work it appears that the most definitive parameter to measure is the apparent resistivity, although measurement of the chargeability parameter is worthwhile because anomalies in both often correlate with hydrocarbon-bearing structures. The significance of the correlation between anomalies in both SP and IP data and hydrocarbon accumulations necessitates a description of the processes that produce the anomalies. The SP anomalies are caused by large scale redox (oxidation-reduction) cells formed in a plume above trapped hydrocarbons. These active cells have slightly altered the lithology above hydrocarbon traps; the mechanism is electrochemical in nature, using energy from the hydrocarbons that escape past the imperfect cap rock.

Electrogeochemical techniques in deeply weathered terrain in Australia

Measurement of H + ion and conductance of aqueous soil slurries as an exploration technique is conceptually attractive for use in exploration in Australia where large parts of the land surface are mantled by very thick leached weathering residuum. The common development of conductive horizons and the generally alkaline nature of the soils, however, raised doubts about its applicability. Tests have been conducted over a number of Australian deposits, mostly over massive sulphide deposits, e.g., Elura and Mt. Bulga in New South Wales. At Elura a totally weathered conductive zone extends down to about 100 m and the overlying soils are Red Earths, frequently calcareous; at Mt. Bulga the soils are skeletal podzols and the weathering is less intensive. At both deposits characteristic “rabbit-ear” anomalies, with a central peak in some instances, for H + ion are recorded in surface soils. Conductance anomalous patterns are either sympathetic or mirror images of the H + ion pattern, depending upon local conditions. At Elura there is no conventional geochemical response in the soils over part of the deposit, and there is a very strong transported Pb anomaly for a distance of about 1300 m southwest of the deposit. There are characteristic H + ion and conductance responses over the entire orebody, and there is no H + ion and conductance response over the transported Pb anomaly. At Mt. Bulga a clear H + anomaly occurs over sulphides covered by 60 m of barren rock. The results demonstrate the potential usefulness of electrogeochemical techniques in Australia to detect deeply buried sulphides under conditions of extreme weathering.

Electrical petroliferous exploration in Australia

The research project under discussion here was initiated by the Commonwealth Scientific and Industrial Research Organisation to test the ability of electrical methods to detect oil and gas accumulations onshore in Australia. A variety of electrode arrays have been tested over seven oil and gas producing areas in the Surat and Cooper Basins and the Denison trough, in Queensland and South Australia. The object of the research is to test the feasibility of cost effective reconnaissance surveys to collect a minimum of data with the maximum interpretability. An attempt to determine the nature of the alteration that occurs to the rocks above a hydrocarbon accumulation is also being sought. The rocks above hydrocarbon accumulations have been shown to be between 20 and 50% more conductive than those surrounding them.

History of Australian Phycology: early German collectors and botanists

INTRODUCTION German sailing ships did not ply the oceans in early times when Portuguese and Dutch, English and French sailors came to the southern seas. But new horizons extending into the southern Pacific were opened for the German people through the eyes and writings of the Forsters, father, Johann Reinhold ( 1 7 2 9 1 7 9 8 ) , and son, Johann George Adam (1754—1794) , who accompanied James Cook on his second Pacific journey (Hoare, 1972; Frost 1979) . Furthermore, in spite of the French Revoluton and the Napoleonic Wars, there were opportunities for extraordinarily active correspondence and exchange of ideas between German botanists and their French and English counterparts. This paper traces the contributions of German botanists in the early period of exploration in Australia.

EXPLORATION AND ITS RESPONSE TO DIVERGENT INFLUENCES

Petroleum exploration in Australia has evolved through three distinct phases and is now entering a fourth. It began with the wild, speculative flurries that culminated in drilling on the Coorong, South Australia in 1892, it was revived by the accidental discovery of gas near Roma at the turn of the century leading to the oil boom from 1926 to 1933, and it reached its peak in 1962-72 in the third phase, after which exploration activity has gone into decline. Examination of the economic, political and social background to the industry reveals that, on the national scene, political events rather than economic and social trends have had greater impact on the fluctuating course of its development. International influences also appear, in many instances, to be of greater significance than domestic factors. Much time and effort have been devoted by industry, government and academics to the analysis of economic, political and social influences on Australia's petroleum exploration but it is quite obvious that the basic determinant Is still the oft-forgotten geologic-technological factor. The condition of the domestic industry depends primarily on the potential of Australia's sedimentary basins and the quality of the technology used to explore them. In the long term, all other influences are temporary in their impact and subordinate in their ultimate effect.

CONCESSIONAL AND CORPORATE AVENUES FOR OIL EXPLORATION IN AUSTRALIA AND THE LEGISLATIVE CONSTRAINT

When an explorer decides he wishes to participate in exploration in Australia there are three elements which will affect his fortune over and above technical considerations. These are (a) the concessional avenue open to him, (b) the corporate avenue open to him, and (c) the legislative constraints.The traditional concessional avenue in the off-shore environment has been by gaining rights under the Submerged Lands Acts. This legislation has been enacted by both the Commonwealth and State Governments in mirror-image fashion for the Adjacent Area lying offshore from each State. In the onshore environment the different States have their own discrete legislative regimes by which they govern exploration and development rights.As a general concept title to petroleum is vested in the Crown.The corporate avenues by which the explorer enters into a relationship, either directly with Government or with some other company which has a relationship directly with Government, are as follows:An explorer individually may be a concession holder;a company may be a concession holder;a joint-stock company may be a concession holder;a partnership may be a concession holder;a joint-venture may be a concession holder;a company may enter into a farm-in/farm-out or "Exploration and Participation Agreement" with a concession holder;a company may hold an over-riding royalty secured by a concession holder;a company may have a carried interest secured by a concession holder;there may be a take-over of company shares.The traditional concessional and corporate avenues are affected by certain statutory enactments of the Commonwealth of Australia. This legislation comprises the Petroleum and Minerals Authority Act, the Foreign Take-overs Act, the Seas and Submerged Lands Act, the Restrictive Trade Practices Act, and the legislation relating to Customs and Reserve Bank regulation. The relationship of these Acts to the Australian Constitution is examined.

A REVIEW OF THE PETROLEUM SEARCH SUBSIDY ACTS

THE FIRST of the Petroleum Search Subsidy Acts was introduced in 1957, when the level of petroleum exploration in Australia was very low. The types of operation eligible for subsidy, and the subsidy rates, have been altered from time to time in recognition of changing circumstances. The present Act is not to be extended and only covers operations which will be completed by 30 June 1974.The activity in various areas in Australia and Papua New Guinea has fluctuated during the period that the Acts have been in force. The early, relatively high, level of activity in Queensland was not maintained, and other areas, such as Western Australia, received increased attention. The percentage of subsidy funds going to operations in offshore areas has changed markedly. The Acts have provided assistance to petroleum exploration in Australia in several ways. In the early days of the Act, when little expertise on petroleum exploration was available in Australia, standards were set for the field operations and reporting, and the operations were closely supervised, ensuring a reasonable minimum standard of performance. Payments under the Act have assisted companies, particularly those with limited funds, to engage in exploration and have also encouraged all companies to explore in Australia by reducing the effective unit cost of exploration. The information which has become available through the operation of the Act has assisted exploration by enabling exploration decisions to be based on the results of most of the exploration which has been carried out in Australia.The Petroleum Search Subsidy Acts, which will cost a total of some 7150 million, have made a very useful and significant contribution to petroleum exploration in Australia and Papua New Guinea over a period of 17 years.

Preface of Geochemical exploration in Australia

Preface of Geochemical exploration in Australia

The Discovery and Exploration of Australia, Erwin H. J. Feeken, Gerda E. E. Feeken and O. H. K. Spate, Melbourne, Thomas Nelson, 1970. 220 x 295 mm., iii and 318 pages (including gazetteer of Australian place names and index), 145 illustrations (11 in colour), 38 diagrams and maps ((25 in colour). $11.50.

<b>The Discovery and Exploration of Australia</b>, Erwin H. J. Feeken, Gerda E. E. Feeken and O. H. K. Spate, Melbourne, Thomas Nelson, 1970. 220 x 295 mm., iii and 318 pages (including gazetteer of Australian place names and index), 145 illustrations (11 in colour), 38 diagrams and maps ((25 in colour). $11.50.

LIBRARY INFORMATION SERVICES FOR EXPLORATION COMPANIES

The increased pace of scientific research and technological development since the Second World War has resulted in an "explosion" in the amount of information being produced in scientific and technical fields. It has been calculated that the published literature of these fields doubles every ten years. Most industries have been affected by this and the petroleum exploration industry is no exception. Exploration companies are prolific producers of information, particularly that resulting from their field operations.The information needs of the management and technical staff of exploration companies cover a very wide field of diverse material, which includes legal, financial, economic, industrial and statistical material, as well as geological and geophysical data and its interpretation. Relevant external material includes information on exploration methods and equipment, laws and regulations governing exploration in Australia, and the status and activities of competitors in the industry. All this comes from many and varied sources, and may be in conventional forms (books, journals, maps, etc) or in forms peculiar to the exploration industry itself (e.g. seismic sections and well logs). Internal information is even more complex in content and form, comprising field data of all kinds, reports, maps and diagrams, seismic sections and records, well logs, aerial photographs, and many other items.The difficulties presented by such a mass of varied and complex material are best overcome by the establishment of a "special library" in the charge of a professional librarian. A "special library" is one serving a specialist clientele and covering a particular field of knowledge. Professional librarians - or information officers - have been trained to gather, index, store, retrieve and disseminate information of all kinds; these tasks comprise the routine work of a special library. They are performed by adapting the standardised guidelines of librarianship to suit the specialised nature of the industry being served. Librarians are also trained in such tasks as literature research and compilation of information dossiers.The establishment of a special library under a qualified librarian provides an exploration company with:a centre for the integration of all kinds of information material; andan active information service.It thus enables a company to make the maximum use of all available information which may be relevant to its purposes.

FUTURE FINANCING AND OWNERSHIP OF THE AUSTRALIAN PETROLEUM EXPLORATION INDUSTRY

The cumulative deficit between Australia's petroleum requirements of the 30 years to the end of the century and projected domestic production has been estimated at 14.25 billion barrels.Oil exploration in Australia to 31 December 1971 cost $725 million and resulted in the discovery of 2.1 billion barrels of oil and 14.1 trillion cubic feet of natural gas. If this expenditure to discovery ratio is maintained we will need to spend a further $3,485 million on exploration to maintain only 70% self sufficiency in crude supplies.The alternatives to supplying a high proportion of demand from local production are frightening. The foreign exchange required to purchase the presently projected shortfall in 1984/85 at what we consider will be conservative prices is almost half Australia's record foreign exchange holdings at 30 June 1972. Further, by that time we will be competing with the other industrialised countries of the world for an increasingly scarce commodity.The major means of encouraging the expenditure of exploration moneys is to create a climate in which successful explorers are adequately rewarded. The unique position of indigenous crude prices must be corrected and gas sales encouraged. To maintain a meaningful Australian interest in the future finds local investors must be given suitable incentives to risk the necessary exploration funds.