Category: Economic and applied geology

The US oil economist M.K. Hubbert issued a chilling warning in the late 1960s that foretold the eventual decline of the single most important physical resource of the global economy.  His simple approach was to consider petroleum, and by implication a great many other commodities, as having a fixed abundance that was not added to naturally at a rate that could keep pace with its exploitation.  Oil and natural gas are non-renewable, as far as human society is concerned; they are “wasting” resources built slowly and episodically over tens of million years.  Hubbert matched the exponential rate at which petroleum is extracted with various notions of how much is in the ground and how the easiest to find and pump out inevitably will give way to more tenacious reserves.  His model for the future of the petroleum economy centred on a theoretical bell-shaped curve relating production to time, and we are now entering his predicted period of increasing difficulties.  Estimates of reserves have increased considerably in the last 35 years, and so has the efficiency of getting out the fluids.  Recent news leaking from the Shell oil giant that there has been a certain fiddling of the books about how much remains in its licence areas (a 20% overestimate) is perhaps a sign of just how difficult it is to keep pace with growing demand.  Oil companies hope for the best as regards how quickly new discoveries add to their assets, yet they can never voice their fears of the worst for the sake of investor confidence and the volatility of the oil futures market.  The history of petroleum discovery is indeed a bell-shaped curve, and it has been on the slippery downward slope for about 30 years, with a few cheering but brief upswings.  On average, annual discovery has decreased from about 50 to 10 billion barrels each year, noting that the size of the discoveries is always an estimate of what might eventually be extracted to be tempered by the fact that it rarely if ever is.  A great deal of the petroleum products now being used emerge from massive discoveries in the late 30s and 40s and the mid 1960s.  Nothing like the huge Arabian and Iraqi fields has been found since then.  Many commentators, as usual, consider the present upsurge in oil prices to stem from political issues, but there are deeper economic and technical issues that suggest that it is an irreversible trend while ever demand is insatiable and supply more difficult to achieve.  Standing above the generally quoted reserves that can reasonably be expected to flow using current methods, are several categories of petroleum in the ground that require new extraction methods and a higher price to implement them.  They are considerably larger, though much more fuzzily defined, and range from the dregs that are not easily pumped, through viscous oils, tars sands to oil shales, the primary source rocks for conventional petroleum fields when geological processes free their organic content to move.  So the future is likely to depend increasingly on new extraction technologies, that Jim Giles of Nature recently reviewed (Giles, J. 2004.  Every last drop.  Nature, v. 429, p. 694-695).  There are several problems to solve in boosting production: decreasing the viscosity of oil, freeing oil that remains in sediment pore spaces, and driving the oil out under pressure.  One interesting possibility is setting fire to oil in the reservoir rock, by pumping air into it.  That would create gas pressure as well as lower viscosity, and has been tried before after Russian engineers accidentally set fire to a deposit by trying pressurised air to drive oil out.  Following their surprise (and no doubt a ticking off by top political management), oil did flow more freely from nearby wells, but later experiments have had mixed success.  Bacteria that metabolise oil are increasingly used to clean up spills.  Since they break it down to lighter and less viscous molecules, and generate various gases, they have a role to play underground.  However, all kinds of secondary recovery methods that are deployed today do not add a great deal to production – about 3 to 4% – and are unlikely to stave off eventual decline without further massive increases in price.

Structural control over hydrothermal gold mineralisation

One of the world’s richest gold provinces is centred on the town of Kalgoorlie in Western Australia, site of the “Golden Mile” whose production and reserves exceed 2500 tonnes of gold.  The geological control is a 200 km long shear zone trending SSE that cuts Archaean greenstone associations of mafic-ultramafic and felsic lavas, and volcanoclastic rocks of the 2700 Ma Yilgarn Province.  Exploration along the trend has revealed a number of other world-class gold deposits, and the Boulder-Lefroy Shear Zone has come to typify syn-tectonic hydrothermal mineralisation.  Detailed work has long demonstrated that smaller shear zones slightly oblique to the main trend focus the mineralisation.  That is because the main line of movement was probably in compression, having a strike-slip sense of motion.  Depending on the local orientation of lesser shear zones, some have trends likely to have encouraged dilatation in transtensional environments.  Fluids are more likely to favour such opening zones, thereby concentrating their flow and deposition of minerals from them.  Much of the research in the area has focussed on detail, in an attempt to discover a means of predicting new deposits, and exploration is dominated by systematic drilling in what is not a particularly well-exposed terrain, and one where standard methods of stream sediment analysis are thwarted by low rainfall.  Robert Weinberg of Monash University, Paul Hodkiewicz and David Groves of the University of Western Australia have taken a broader view of the structural setting (Weinberg, R.F. et al.  2004.  What controls gold distribution in Archean terranes?  Geology, v. 32, p. 545-548).  So intensively explored is the gold province that it is unlikely that any large deposits remain to be discovered, but very similar shear zones affect most of the world’s Archaean granite-greenstone terranes, where exploration is at an earlier stage of progress.  A model of regional controls over gold is therefore pretty valuable.  Weinberg et al. divide the Boulder-Lefroy Shear Zone into boxes along its length, each centred on 8 gold “camps”.  They plotted the deviation in trend of local segments of the shear zone in each box from its overall trend against the box’s known gold “endowment”.  What emerged was a clear confirmation of the regional association of mineralisation with  likely zones of regional transtension, trend deviation matching closely the estimated gold endowment.  The abundance of structural data also enabled the authors to analyse the fractal dimension of all shears and fractures, thereby assessing the variation in overall geological complexity of the province.  The results are odd.  The least well-endowed parts of the gold province are more complex than those containing the most gold.  The Golden Mile itself occurs where complexity changes from low to high. The ideas await testing on less mature shear zones cutting Archaean greenstones elsewhere in the world, such as in South India and East Africa.

The Mackenzie delta in Arctic Canada has been an area of conventional hydrocarbon exploration for decades.  In 1972 methane-ice mixtures in the permanently frozen ground were discovered in one well at a depth of about a kilometre during exploratory drilling.  They are rich, with up to 90% of the pore spaces in alluvial gravels being full of the white gas hydrate.  Being associated with conventional gas at greater depths, there is a good chance that combined production could make the considerable reserves economic.  On their own, gas hydrates are not yet economic, even onshore, since they would need heating to break down the peculiar compound, and natural gas prices are currently at a low level.  Economics also depend on a conventional gas pipeline being extended to the area  Tests and computer simulations suggest that production of deeper conventional gas can lower the pressure on the gas hydrate inducing it to break down and add to the flow from a well.  In maybe 10 to 20 years production could begin.  The likely origin of the Canadian reserves and those in the North Slope of Alaska is from methane leaking from deeper reserves to “freeze” in the colder conditions at shallow depths.

Arctic North America could eventually produce up to one sixth of current US natural gas consumption from onshore gas hydrate.  Of course, vastly greater gas-hydrate potential exists offshore – between 10 000 to 42 000 trillion cubic metres (tcm) world-wide, compared with 370 tcm of estimated conventional gas reserves.  Methane (CH₄) burns to produce less carbon dioxide per unit of heat energy than more carbonic natural gas, so is a means of easing “greenhouse” gas emissions.  Potentially it could be feedstock for CO₂-free hydrogen production.  Pressures on the economy of Japan, which has very few natural energy resources, have prompted Japanese researchers to begin exploratory offshore drilling into the Nankai trough offshore of SE Japan, where there are potentially rich reserves of gas hydrate in sands.  This may produce commercially in 10 to 15 years.  The thorniest problem with many gas hydrate deposits is that they are in “tight”, fine-grained sediments.

Source:  Kerr, R.A. 2004.  Gas hydrate resource: smaller but sooner.  Science, v. 303, p. 946-947

The largest producing hydrocarbon field, which is unlikely to be bettered, is the Gharwar oil field of Saudi Arabia.  It extends for about 3500 km² and still contains 80 billion barrels of oil.  Anything comparable in size, or bigger, would have been tripped over decades ago, because of the sheer size of the geological trap structures.  That is one of the reasons to believe that hydrocarbon resources are unlikely to last until the 22^nd century, unless other kinds of accumulation can be exploited economically.  There are vast onshore reserves of tar sands from which the more volatile hydrocarbons have leaked away, but for them to become generally useable requires very large rises in oil price.  The same conditions will have to prevail before oil shales, the source rocks for conventional hydrocarbons, become viable..  Had tectonics not induced the Colorado Plateau to rise and be eroded, oil would be far cheaper and more secure, and the USA would have even more economic and political clout than it already has.  The recognition of unroofed hydrocarbon fields in that region of western North America may therefore come as a relief to many people (Beitler, B., Chan, M.A. & Parry, W.T. 2003.  Bleaching of Jurassic Navajo Sandstone on Colorado Plateau Laramide highs: Evidence of exhumed hydrocarbon supergiants.  Geology, v. 31, p. 1041-1044).

The desert dune sandstones of the North American Jurassic form some of the world’s most spectacular scenery, because of their vast outcrops in Utah national parks, such as Monument Valley.  Their attraction lies in the colours of the sandstones as well their deep incision.  Discovery of what was once a series of supergiant hydrocarbon fields lies in variations of that coloration.  When laid down, the sandstones were reddened by precipitation of ferric (Fe³⁺) oxides from water that seeped through them during diagenesis under oxidising conditions.  However, large tracts now show signs of variable bleaching, which gives the variegation that tourists flock to see.  Iron has been removed in places, and for that to happen, the insoluble Fe³⁺ has been reduced to the more soluble Fe²⁺, or ferrous form.  That can occur when conditions in the rock change to highly reducing, as in the case of hydrocarbons migrating in along with water.  Most wind-blown sands have good porosity and their uniform grain size induces excellent permeability as well, so they are near-ideal reservoirs.  However, for them to become permeated by hydrocarbons that migrated from source rocks (usually shales) requires pathways and structures in which the hydrocarbons can be trapped.  The Jurassic of the western USA has alternations of these sandstones with less permeable rocks, and was deformed into huge open anticlines during the Laramide orogeny, that originally might have created such traps on a regional scale.  Brenda Beitler and her colleagues from the University of Utah have mapped the zones of bleaching using Landsat-7 Enhanced Thematic Mapper data.  Sure enough, the most bleached areas coincide with the crests of the large upfolds, and with reverse faults that link them to basins with source rocks and may have acted as fluid migration pathways.  The pore volume that could have been available for hydrocarbon trapping would have been 2200 km³, equivalent to 18.5 trillion barrels, about 6 times larger than estimates of the modern world’s recoverable oil.  Since the Cretaceous, the Colorado Plateau has undergone more than 2 km of uplift and every single upfold has been breached and deeply incised.  Sorry George, the oil leaked out long ago!  The inevitable leakage of the gas fraction, perhaps as much as 2 billion tonnes, could have warmed the Tertiary climate, if a significant fraction were released quickly.  The main incision of the Colorado Plateau was probably in the late Miocene (around 6 Ma), when ocean-floor data suggest global warming of the order of 0.5 to 1ºC.

Background to globalisation of water resources

“The second provision of any civilised society after a system of laws, is that of a safe water supply” is anonymously attributed in the repeated warnings about the parlous state of water provision for about two thirds of the world’s population.  Many of the private companies that took over the public water authorities in Britain now stride the planet organising that provision.  In South Africa, the resulting increases in water pricing are the main source of anger throughout the poorer sections of its population, especially in the townships.  In Cochabamba, Bolivia there have been mass protests about similar price hikes that came years ahead of any improvement in supplies.  A consortium of national and transnational companies needed the extra cash to finance a major dam project, instead of looking to global investors in the project.  Science carried a lengthy article that provides a context for this new trend in globalisation (Gleick, P.H. 2003.  Global freshwater resources: soft-path solutions for the 21^st century.  Science, v. 302, p. 1524-1528)

Oil and natural gas are the dominant physical resources for modern society, having rapidly outstripped coal in the world’s economy.  Yet using them poses the threat of global climatic changes.  They are essentially a bank of solar energy, mediated by past photosynthesis into hydrocarbons; very long passed indeed.  Their burial tens and hundreds of million years ago helped modulate solar warming and drove up the level of oxygen in the atmosphere.  Using them reverses those aspects of the carbon cycle.  As the wars in Sudan, Afghanistan and Iraq demonstrate, developed economies will go to any lengths to retain access to known reserves.  Being so “hooked” on hydrocarbons, those economies have continually to find more.  However, the days of “trip-over” oilfields, such as those of Persian Gulf, are gone forever.  Exploration ventures into more and more difficult conditions, particularly offshore, where drilling is now going on in sea floor as deep as 2.5 km beneath the water surface.  Every aspect of the hydrocarbon industry poses increasing challenges; it seems to be at a crux.  For this reason, the 20 November 2003 issue of Nature includes a 56-page Insight supplement on a wide range of topics.  It starts with a review of the place of the petroleum industry in human history (Hall, C. et al. 2003.  Hydrocarbons and the evolution of human culture.  Nature, v. 426, p. 318-322).  Robert Berner of Yale University gives an up to date summary of the effects of fossil fuel use, in the context of the carbon cycle over geological time (Berner, R. 2003.  The long-term carbon cycle, fossil fuels and atmospheric composition. Nature, v. 426, p. 322-326).  The question, “How does petroleum form?” is addressed by Jeffrey Seewald of the Woods Hole Oceanographic Institute (Seewald, J.S. 2003.  Organic-inorganic interactions in petroleum-producing sedimentary basins. Nature, v. 426, p. 327-333).  The shift of exploration to ever deeper offshore areas brings it closer to the lines where continents split and drifted apart in the past.  So it isn’t surprising that Nature Insight includes a review by Cambridge University and BP geoscientists of how those margins evolved (White, N., Thompson, M. & Barwise, T. 2003.  Understanding the thermal evolution of deep-water continental margins. Nature, v. 426, p. 334-343).  Organisms other than humans exploit the energy locked in oil, and geochemists from the University of Newcastle upon Tyne address their role in actually degrading petroleum, so that many of the largest onshore petroleum reserves (oil sands in particular) pose great difficulties for exploitation (Head, I.M., Jones, D.M. & Larter, S.L. 2003.  Biological activity in the deep subsurface and the origin of heavy oil. Nature, v. 426, p. 344-352).  Methane generated by anaerobic bacteria in sea-floor sediments and in bogs can combine with water in the form of an ice-like substance called methane hydrate, if the pressure is high enough and temperature is close to 0ºC.  There is a lot of it about.  On the one hand it has huge economic potential, but on the other it poses awesome threats to the climate.  Several times in geological history vast amounts of methane have belched from the sea floor to drive up global temperature; it is a highly efficient “greenhouse” gas.  Dendy Sloane of the Colorado School of Mines addresses issues related to methane hydrates (Sloane, E.D. 2003.  Fundamental principles and applications of natural gas hydrates. Nature, v. 426, p. 353-359).  All these articles are deeply informative and well written.  They are “must-reads” for all geoscientists.  The sequence ends with a word from “management” (Shell International), in the form of a look ahead to how oil companies might clean up their act and become “friends of the Earth” (Stankiewicz, B.A. 2003.  Integration of geoscience and engineering in the oil industry – just a dream? Nature, v. 426, p. 360-363)

Currently around a billion people are at severe risk from drinking contaminated water, and whenever there is a major human crisis refugees are placed in the same plight.  The main solution would seem to be drilling wells that tap groundwater that aerobic bacterial action cleanses of most pathogens.  That is essentially true, but some groundwater is rejected even by people suffering the most extreme privations.  It has the appearance of water from the radiator of an aged lorry, because it contains abundant dissolved iron that immediately precipitates as red-orange slime when exposed to the air, tainting food and staining clothes.  A solution may arise from studies as far from drought-stricken areas as one could possibly get; concerning the way in which deep-sea wrecks decay away.  The discovery of the wreck of the Titanic in 1985 and recovery of parts of it later by marine historian Robert Ballard, revealed that its ironworks were being consumed by bacteria that created stalactite-like masses of iron oxides, known as “rusticles”.  Detailed microbiological studies found a highly complex harmony of different bacteria that created and inhabited the rusticles.  Effectively, they were eating the mighty ship at a rate of about a tonne every ten days by exploiting the energy released by oxidation of iron.  It may prove possible to harness the habits of these iron-loving bacteria to remove iron from groundwater and make it palatable

Source:  Fry, C. 2003.  Iron rations.  New Scientist, 26 July 2003, p. 36-37.

Regular readers of New Scientist know that Fred Pearce is the scourge of dam builders, especially those with near-megalomania about vast barriers and reservoirs.  Back in the late 1960s Canadian environmentalists were horrified to learn of plans being developed to divert southwards water that naturally flows along the great rivers of the Canadian Shield to the Arctic Ocean and Hudson’s Bay.  This was NAWAPA, the North American Water and Power Alliance.  NAWAPA is still a live ambition for supplying the water-hungry west and mid-west states of the USA.  The former Soviet Union put such grandiose plans into effect, one outcome being the dramatic shrinkage of the inland Aral Sea.  Pearce returns to continental water transfer in an important review in the weekly for whom he has worked for many years (Pearce, F.  2003.  Replumbing the planet.  New Scientist, 7 June 2003, p. 30-34).  His trigger is the filling of the giant Three Gorges reservoir on the Yangste, one of whose aims is to channel water northwards to augment supplies to the increasing parched plains of central eastern China.  But this is only the start of an awesome venture, that will also shift the equivalent of 25% of the Nile’s flow from Tibet’s glacial meltwater that feeds the Yangste into the Yellow River, which now barely trickles into the Yellow Sea.  India seems bent on snaffling much of the flow from the Ganges and Brahmaputra catchments into the drought-prone south of the subcontinent.  As well as the huge disruption of people and environment that schemes such as these must entail, Pearce highlights the vast economic costs.  India’s continental engineering will eat up the equivalent of 40% of its GNP. 

Obviously, such huge ventures throw up equally large political and ethical questions, which are not easy to resolve.  In many cases the perceived needs for regional water transfers stem from very wasteful water use, particularly in agriculture.  Using drip or trickle irrigation, which needs large-scale application but relatively low-cost and simple technology can reduce water requirements dramatically, simply by reducing losses by evaporation from canals.  In semi-arid areas as much as 70 % of channelled water never reaches the crops for which it is intended.  Governments such as those of India and China depend so much on rural support that they might commit political suicide by pressing for changes to practices that date back millennia, so they opt for the spectacular, quick fixes.  Yet there are other such schemes that might transform the livelihoods of some of the worlds most destitute people in the Sahel and Horn of Africa.  One suggestion is to divert part of the largely unused river flow through humid tropical Central Africa across the Sahel to reach Lake Chad.  Another, not mentioned by Pearce, is to dig a channel that will flood the Danakil Depression of Ethiopia and Eritrea, which lies about 100 m below sea level.  Topographically, this would be relatively easy, because only about 30 km of low-lying coastal plain separates the Red Sea from the Depression.  The flow could generate hydropower in a power-starved region, and evaporation from the resulting saline lake would boost rainfall in the world’s hottest place, and perhaps allow harvesting of the many salts that would be precipitated, including potash fertilisers.  Solar energy could also be used for low-cost desalination.  However, no-one can guess at the climatic and ecological consequences of changing humidity in both the Chad and Danakil basins.   Yet, water is becoming the most strategically important physical resource so rapidly that the enormous economic implications for transnational contractors, and political prestige associated with regional transfer schemes will drive them ever onwards.  There is one glimmer of hope, which Pearce mentions; ordinary people in Rajasthan, India’s driest state, have resurrected old practices of water harvesting, and find that they are more secure than those who rely on state-sponsored canal supplies.  The root issue is that rainfall disappears either by run-off or evaporation in a matter of days, unless it is stored somehow.  Any habitable place has rainfall, albeit irregular in drought-prone areas, and quite low-cost ingenuity can “bank” the transient spates where the water is needed.

Desalination is often touted as a solution to shortages of clean drinking water, but the most common method, using reverse osmosis, is really a luxury.  It relies on electric pumps driving salty water through a membrane, so that salt concentrates on the high-pressure side of the membrane, allowing nearly fresh water through it.  This method is widespread among power-rich economies along desert coastlines, but has done nothing to help the less fortunate millions in countries where electricity is unaffordable.  Indian scientists, unsurprisingly, have developed a means whereby fresh water might become accessible to most coastal people in the tropics.  They have worked out how to gear bullock power to reverse-osmosis pumps, so that a pair can produce up to 3000 litres each day and supply entire villages.  If a bullock can do it, then why not donkeys or camels in even more arid coastal areas?

Source:  Coghlan, A 2003. All hooves to India’s pumps.  New Scientist, 10 May 2003, p. 19.

The Democratic Republic of Congo (DRC, formerly Zaire) is the most war-torn country in Africa, and has been since Belgium relinquished its largest colony in 1960.  It is also Africa’s most mineral-rich country outside of the Republic of South Africa.  Most of its population, particularly outside of the major cities, has been repeatedly caught up in the most savage conflicts, which have left more than 2 million dead and far more displaced or reduced to conditions of bare survival.  From the civil war following the attempted secession of the most mineral-rich province of Katanga shortly after independence to the present, Congo peoples’ suffering has centred on various groups’ attempts to loot its mineral riches.  Despite the DRCs  strategic importance as a supplier of cobalt and tantalum, for which it is the world’s largest source, and its world-ranking production of copper and zinc, diamonds (up to one third of a ton annually, mainly of industrial quality), and gold (up to 6 tons annually), neither the UN nor those powers currently engaged in Iraq have made any determined effort to end the 40-year plight of its people.

Every geologist suspects that war in the Congo has a direct link to its mineral resources, but until recently its economic basis has remained carefully hidden by the various warring groups, and to some extent by the world mineral industry which ultimately benefits.  Ingrid Samset of the University of Bergen in Norway has reviewed the particular role of diamonds in the recent phases of conflict, that followed the fall of the reviled President Mobutu in May 1997 (Samset, I. 2002.  Conflict of interests or interests in conflict?  Diamonds and war in the DRC.  Review of African Political Economy, v. 93-94, p. 463-480).

Following the occupation of eastern DRC by armies from Rwanda and Uganda in collusion with the anti-Kabila RCD forces, and the sending of troops by Namibia, Angola and Zimbabwe to assist the Kinshasa régime in mid 1998, official figures for production of and revenues from all physical resources fell far more dramatically than for other exportable commodities, such as coffee.  The largest falls involved diamonds and coltan (columbite-tantalite).  Both combine very high value relative to weight (coltan trades at up to US$400 per kilogram) with simple extraction technologies.  Both are mined extensively by artisanal groups, and so are attractive for quick, clandestine looting.  Tantalum is used in making capacitors, specifically for mobile phones, and the boom in the price of coltan followed the vast expansion of cellular phone networks world wide.   Zimbabwe, and to a lesser extent Angola and Namibia have won official concessions for diamond mining in exchange for their military involvement.  The embattled ZANU-PF régime in Harare is probably highly dependent on revenues from Congo diamonds.  In the case of Uganda and Rwanda’s involvement with opposition forces in eastern DRC, the economic aspects of their roles are more difficult to dig out.  Both countries lack diamond or coltan reserves, yet in the case of diamonds, their exports rose by 12 and 90 times, respectively, since the start of their involvement.  Comparing their export values with probable production in the area that they help control, there is a shortfall of about US$13.5 million.  Samset suggests that “missing” diamonds are being used directly as easily “laundered” barter goods in exchange for arms.  In the case of coltan, Rwanda is estimated to have benefited by US$250 million, at the time of the tantalum price peak in 1999-2000, from looting of eastern DRC.  Neither coltan nor diamonds carry signs of their origin (but see Forensic geochemistry to foil “fencing” of conflict diamonds in EPN, June 2002), so tracking looted goods and bringing those involved to account is no easy task.  The state of Israel is heavily involved in the gem diamond trade, as is the Republic of South Africa, and the USA accounted for more than 80% of all industrial diamond exports from the former Zaire.  One of the oddest coincidences was the sudden involvement in peace-making attempts during the Eritrea-Ethiopia war of 1998-2000 of the government of Rwanda, despite its geographic remoteness from that particular conflict and lack of diplomatic experience.

See also: http://www.american.edu/TED/ice/congo-coltan.htm for an analysis of the role of coltan in the DRC conflict.

Prospecting for diamonds relies either on lucky finds in sediments or locating the odd kimberlite pipes that brought diamonds from depths greater than 100 km in the mantle, where they form.  Such has been the centuries-old frenzy for diamonds that most deposits of the trip-over kind have been found.  One of the last major diamond fields turned up in Arctic Canada, after prospectors panned their way upstream of glaciers that had dropped the odd diamond in Canadian Shield tills.  It is simply too costly to keep repeating this painstaking exercise to satisfy the enduring demand for diamonds of all qualities.  New sources probably exist in huge, unexplored regions of Canada, Australia, Africa and north Asia, yet kimberlites, often having broken down to clays and forming little by way of topographic features, are not easy to find.  Great efforts have been made to harness conventional remote sensing that uses reflected and emitted electromagnetic radiation, but with little success.  Aside from the innocuous nature of kimberlites, most prime ground is either flat, vegetated steppe in areas once affected by glacial conditions, the featureless soil covered tracts of interior Australia or tropical rain forest, where remote sensing simply does not work well enough.

Kimberlite pipes have round traces at the surface and the rock has a different density from common rocks of the upper crust, so one means of locating them is by looking for circular patterns on gravity maps.  But they are small relative to the resolution of regional gravity maps, which are generally constructed by careful measurement of gravitational field potential at points on the surface.  It is not that gravimeters are incapable of detecting differences due to rocks with anomalous density, but that sample spacing is too coarse (>1km) because of the high cost of field surveys.  Maps of the Earth’s magnetic field and emissions of gamma-rays by radioactive isotopes are routinely created at suitable resolution by aerial surveys, but kimberlites show only subtle features on them.  Airborne gravity surveys have been a grail for explorationists for many physical resources, but insufficient economic interest has blunted the search for a way of overcoming the effects of turbulent accelerations during flight, which spoil measurements of the actual gravity force field.  Mining company Broken Hill Proprietary – Billiton’s venture into diamonds after their acquisition of the Ekati deposit in northern Canada has encouraged them to seek a cunning approach to the problem.  Whereas measuring gravitational potential from the air is a tough nut to crack, the US navy had developed an instrument to measure changes in the gradient of the gravitational field that can overcome varying accelerations, to help nuclear submarines navigate without recourse to giveaway sonar “pings”.  BHP-Billiton is into this technology in a big way, now that it has been declassified.  While gravity gradiometry offers one way of revolutionizing the precision of gravity surveys, other methods are possible, and it is rumoured that geophysicists who try to measure even tinier shifts in the gravitational field to monitor the rise and fall of magma in volcanoes are onto a cheaper and less convoluted method………

Source:  Nowack, R. 2002.  Pulling power.  New Scientist, 21 September 2002,p. 42-45.

The search for hitherto undiscovered and totally hidden hydrocarbon reserves has attracted a bizarre range of patented techniques over the years.  They range from using thermal images of the sea surface to pinpoint stationary cold spots that may mark deep water upwellings driven by rising natural gas bubbles, through helicopter borne hydrocarbon sniffers to fine-resolution aeromagnetic surveys to detect anomalies due to magnetite formed by bacteria that metabolise oil and reduce hematite to magnetite.  Most have a rational scientific basis, but there are a few that defy reason.  Most explorationists have been button-holed by dowsers, but the latest venture seems to have convinced Her Majesty’s Government, to the extent that the Department of Trade and Industry has granted three licences to explore parts of rural England, generally known for their fox-hunting aficionados.

 A company, Technology Investment and Exploration Limited of Guernsey, has invented a device that they call a “microlepton generator”, supposedly based on the Nobel-winning work of Martin Perl of Stanford University, who discovered the subatomic tau lepton in the early 1990s ( http://physicsweb.org/article/news/6/7/1 ).  They claim that their beam of microleptons, highlights areas underlain by hydrocarbon deposits, when used to illuminate satellite images.  They contend that oil generates vast amounts of microleptons that produce subtle effects on such images, but they can only be detected by microlepton beams  TIEL intends to deploy a hand-held microlepton detector from an aircraft overflying areas that they claim have given “tell-tale” signatures using their instrument.  In this respect, they are one up on particle physicists, who have so-far failed to detect microleptons under laboratory conditions.  The smallest known lepton is the electron that is 1000 times more massive than the microleptons claimed by TIEL at the base of their leading-edge technology.  Despite that, it is hardly likely to have escaped discovery by the best-financed branch of science.

Robin Marshall, a particle physicist at Manchester University, discovered that microlepton technology is based on a paper published by a Russian physicist called Anatoly Okhatrin in the journal Doklady in 1989. “He was clearly either mad, drunk or deluded,” says Marshall. “He spun a cone of lead weighing several kilograms in front of a pin-hole camera and claimed to have photographed a ‘glow’ surrounding the cone that was due to microleptons.”   Enough said?  No.  One of TIELs targets is in Charnwood Forest in Leicestershire, well-known to geologists for not being above an oil-prone basin.  Indeed the area is underlain by Neoproterozoic volcanic rocks that bolster the Midland craton of central England, which thwarted extensional basin formation from the Silurian to modern times.  Still, an onshore exploration licence is a handy item for a company’s CV.

TIEL is not the only outfit making these claims.  Another, Alkor International, seems to have a Russian link, and its website (http://www.alkorinternational.com/ ) gives details of the method it uses; “special” photographic processes, computers and software, and is also claimed to locate water resources and gold deposits!