Fundamentally, in the search for new gold ores of this type in the Archaean, a stratigraphic approach is likely to be more successful than a purely structural one, the opt imum situation being where the latter is used in a secondary role as an adjunct to the former. This applies to the relatively little-mineralized and little-altered vein quartz ores in the majority of gold deposits - where gold is mostly free. But a different situation applies with complex, highly sulphidic and highly altered rich-lode ore zones with not much free gold but abundant gold in sulphides and tellurides, as in the Kalgoorlie Golden Mile. Even there a broad relationship exists between major sulphide ore zones and carbonaceous sediments, and a close relationship between bonanza ‘Green Leader’ ores and tuffite. F o r Kalgoorlie, there is a growing belief that major ore zones have had their positioning influenced, to some extent a t least, by barren semi-regional faults or strongly sheared primary structures, subsidiary to regional faults or lineaments. In that case, the emphasis is on the semi-regional structures, or rather, zones adjacent to them, according to established pattern, for future exploration for Golden Mile-type ore zones.

Suggestions for further reading Blatchford, T. 1913. Geological Investigations,

Burbanks and Londondeny Mining Centres, Coolgardie ’ District. Geological Survey of Western Australia, Bulletin no. 53.

Ellis, H. A. 1939. The Geology of the Yilgam Goldfield South of the Great Eastern Railway. Geological Survey of Western Australia, Bulletin no. 97.

Nickel, E. H. 1977. Mineralogy of the ‘Green Leader’ gold ore at Kalgoorlie Western Australia. Proceedings of the Australasian Institute Mining & Metallurgy, v. 258, pp. 19-29.

S . A. Tomich is an experienced mining and exploration geologist specializing in mineral deposits of the Yilgarn Block.

Topics

A geologist in Bucharest ADRIAN LLOYD

I went to Bucharest a t Easter 1990 with entirely ungeological purposes in mind, but I called on my colleagues in the Geology Department there and, of course, my subconscious was making geological notes.

The Carpathian-Balkan mountain chain forms a broad reversed S to the east of the Alps (Fig. 1). Bucharest lies in the southern east-opening loop on Neogene outwash plains from the southern Carpathians; so it has almost no topographic relief and the two rivers that cross it are in the meander phase. It is a dusty city. Walk a hundred metres on a dry day and black shoes have become light khaki, but thanks to the squads of Tsigane road sweepers the city itself looks very clean. Cutting through the heart of the city from north-west to south-east is the River Dimbovitsa - unfortunately, canalized with concrete banks after World War 11, so there are no exposures. The other ‘river’ is a necklace of elongate, arcuate lakes running from Lake Baneasa in the north to Lake Pantelimon in the east - very attractive with italianate villas on some of the islands, but with low, grassy banks and again no exposures (the first bare rock I saw on this trip was from the returning plane flying over the Bucegi Massif).

The buildings of Bucharest fall into four main categories, with the ubiquitous concrete apartment blocks far outnumbering the rest. These are shoe- boxes of five or six storeys with, usually, four staircases per block, set in monotonous, anonymous rows. A professor of architecture with whom I stayed for a few days told me that they are built to withstand earthquakes up to 8 on the Richter scale, and pointed out two blocks on Sosea Stefan cel Mare that, when the road was widened, were slid on their platform foundations for several metres at 20 cm per hour with the inhabitants still inside! Subsidence was not a problem, he told me, but I noticed many of the granite-sett roads had subsidence patches tens of centimetres deep (when it rains in Bucharest you don’t avoid puddles, you take a detour around lakes). Older public buildings, such as the Geology Faculty on the corner of Piatsa Universitatii, have a French air about them, with leaded mansard roofs and cupolas, and stone faqades that weather to the same colour as their counterparts in Bern (and so presumably of similar Molasse sandstone). Modern public buildings and the strip that Ceausescu gouged out of the heart of the old city to build his vulgar Bulevardul Poporului use travertine with convuluted laminae and frequent

Porphyry: an igneous rock with comparatively large crystals of any mineral set in a distinctly finer-grained groundmass.

Bonanza: an exceptionally rich orebody.

Green Leader: a rock extremely rich in gold, which can only be determined by assay, for there are no visible signs of free gold or gold telluride. Virtually unique to the Kalgoorlie Golden Mile gold deposit, it derives its green colour from vanadiferous mica.

Banded iron formation: a sediment thought to have been chemically precipitated and containing alternating bands of silica (chert or quartz) and iron oxide.

GEOLOGY TODAY November-December 19901193

Fig. 1. Geological map of Romania. The Apuseni Mountains with NE-SW trend parallel the Bakony Wald Block and may represent a similar inter- montane microcontinent. The Eastern and Southern Carpathians have internal crystalline massifs, mainly Precambrian, with auto- chthonous Mesozoic sequences and external detachment nappes, including Cretaceous flysch nappes. Unlike in the Alps, there are extensive post- orogenic, late Neogene volcanics (ornament of ‘v’s) with important mineral- ization. Beyond the Molasse Foredeep are fluvio- lacustrine shelf deposits, which have analogues in the Hungarian Plain and Transylvanian Plateau.

Fig. 2. The Geology and Geophysics building - a nineteenth-century public building faced with Molasse sandstone on the comer of Piatsa Univenitatii and the scene of early fighting during the revolution and the ‘golani’ protest of May- June.

vugs. Finally, examples of the indigenous architecture can still be seen in the Aviatorilor district, each being about the size of an Edwardian house in Britain, with red-tiled roofs, gables and semi-turrets and much use of decorative ceramic tiles for external friezes.

The Faculty of Geology & Geophysics (Figs 2 and 3) is housed in an imposing building with large, high rooms, broad marbled corridors and a lift I wasn’t allowed to operate. (‘It’s a bit cranky’, I was told, meaning that, like almost everything else in Bucharest except the Metro, it is old, worn out and hasn’t been serviced in years.) The building has a tradition going back to 1864, retaining magnificent collections built up over the subsequent period and still growing. They believe in looking at specimens as a basis for their geological knowledge in Bucharest.

I arrived with information about the faculty from the 1990 World of Learning, which caused raised eyebrows all round. They insisted on giving me an up to-date statement (typed on the faculty typewriter and printed on the university copier) which indicates considerable reorganization. In part, this might

The faculty has Departments of Mineralogy, Geology & Palaeontology, Engineering Geology & Hydrogeology, and Geophysics, but these cannot be equated with typical British departments offering rounded courses. For example, sedimentology and geological exploration are taught in the Department of Mineralogy, but stratigraphy and ‘geology of Romania’ are offered in Geology & Palaeontology (which also teaches structural geology and neotec- tonics - yes, they have heard of plate tectonics). On paper the list of courses offered is impressive, including geochemistry, mathematical geology, geothermometry and environmental geology as well as the more traditional studies, but I wonder what ‘geoelectronics’ covers? As might be expected, there is a heavy applied bias to all the courses, backed up by six weeks’ fieldwork each year. Their graduates have therefore had 30 weeks’ exposure to real geology, including some industrial work experience.

The academic staff wear many hats. Apart from having to perform their university duties, they are officials of the Ministry of Geology and Geological Institute and members of the Romanian Academy and Romanian Geological Society. An academic career is started as an Assistant (= British Demonstrator) and progresses through ‘Chief of Equipment’, whatever that is, and Lecturer to ‘Conferentsiar’ (= Senior Lecturer). Professor seems to be an honorary title applied to Conferentsiars, not a distinct appointment, and chairmanships of departments are rotating temporary jobs. Students enter the faculty with a Baccalaureate and can be granted a diploma after a five-year, ten-semester course. They can then put ‘Engineer in Geology’ or ‘Engineer in Geophysics’ on their visiting cards. (If you ever write to a Romanian geologist, it is polite to put the whole works on the envelope - ‘Dornnule Dr Prof. ing. geol. Popescu Nicolae’).

The atmosphere I found in the faculty reminded me of my own department 20 years ago. The place was a hive of activity during the Easter vacation; those staff not in and working were in the field, with much evidence of open-door policies towards other staff, students and casual visitors like myself. No question of ‘I’m too busy; make an appointment to see me next week’. Having walked in unannounced, I was introduced within five minutes of mv arrival to a

reflect the isolation Romania has suffered until Professor of Crystallography who was also Deputy recently, but I got the impression that certain former Vice-Chancellor of the University of Bucharest - an staff members had been political appointments and obviously busy man, yet he came to seek me out! On had been culled after the revolution in December my second visit to the faculty the staff practically 1989. formed a queue to be introduced, telling me that I was

almost the first western geologist in that building in 30 years. (I have since found out that Professor Desmond Donovan of my department was there in 1969.) Like most Romanians I met, they had lively, surprisingly open minds, in marked contrast to Russian geologists of my acquaintance, and a hunger for contact with the outside world. On their estimate, they are 20 years and perhaps more behind the free world in their knowledge of techniques and ideas, and are desperate to catch up. When they do we will have to look to our laurels; with their intelligence and capacity for hard and efficient work, we will soon be learning from them.

I was given a conducted tour of the Minerals Museum (with about 15 guides) and in a corner saw an X-ray machine of 1940s’ vintage. ‘That looks very

IWIGEOLOGY TODAY November-December 1990

solid and well-built’, I said. ‘Does it work?’ ‘No’ was the reply. They have no equipment above the bare essentials, yet are still trying to do original research. Another group took me to the palaeo-strat ‘shrine’, complete with bullet hole in window and large plaster patch on the opposite wall where a Securitate dum- dum had impacted. I was shown the ‘oldest Romanian’, a skull (minus mandible) so beautifully preserved that at first glance I did not think it could be very old. Then I noticed the massive eyebrow ridges and sloping forehead and asked what I thought was the obvious question: ‘What is its cranial capacity?’ They could not tell me and I rather think that nobody has tried to find out. They did tell me that Ceausescu wanted the skull for his ‘Casa Poporului’ collection of National Treasures, but when his minions arrived to collect it, it was not to be found. They also produced a camel mandible from the local Pleistocene, showing that Romania lay on the migration route from Africa into Europe.

Before I left the faculty, the local geologists made me promise that when I returned with transport, with or without students, I would let them show me Romanian geology in the field. With a car it is very easy and very cheap, and there is so much fascinating stuff to see, they said. I was also showered with offers of accommodation on my next trip.

I shall return to Romania. The language is not too difficult to understand - I mugged up a working knowledge in two months - and the people were very good at interpreting my mangled grammar when I asked directions in the street. A street map of Bucharest is just not to be had in the city; so, like a

Fig. 3. The main Science building of Bucharest University alongside the Geology building and in a similar style - less flamboyant than many public buildings of this period.

good geologist, I made my own, but whenever I asked a local for directions I received not one reply but half a dozen - a committee immediately formed to assist me. Failing Romanian, French is widely spoken and a surprising amount of English (with apologies for shortcomings due to lack of practise). All the geologists spoke English, some just understandably, some with great fluency. On my next trip I will get out of Bucharest. As one who knows the Alps fairly well, I have long been fascinated by the complexities of the Carpathians and have read Dan Patroulius’s book on the Bucegi Massif, south of Brasov. I have seen it from the air but I want to lay a hammer on it and its rich Jurassic faunas.

Adrian Lloyd is at University College London

Ultrasonic borehole images of the subsurface crust MIKE LOVELL, PHILIPPE PEZARD & PETER HARVEY

Measurements made down boreholes aim to describe the geological nature of the subsurface in situ. While there have been many techniques for obtaining physical information, and more recently chemical information, on the rocks at depth, the geologist would very much like to be able to visualize the formations penetrated by the borehole. Recent developments now enable scientists to produce high- resolution images of the rocks at depth using micro- scale electrical measurements. This technique complements the application of ultrasonic measure- ments as described in an earlier article in Geology Today (v. 6 , p. 154, 1990).

The device known as a Formation Micro Scanner, or FMS (Fig. I), represents the latest development in a long series of downhole electrical devices developed by numerous agencies since that first experiment in 1927, when Henri Doll acquired the first electrical log down a borehole in the Pechelbronn oilfield of Alsace. There are currently two formats of the FMS available, a standard and a slimline device, each containing four hydraulic arms. The device is lowered to the bottom of the borehole where it opens out rather like an umbrella. This forces the four orthogonal arms out against the wall, and the flat pad at the end of each arm makes contact with the borehole surface. Each

Current Return b- Electronics

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Fig. 1. The Formation Microscanner. The buttons on the pad array each have a diameter of 5 mm. There are four pads in total.

GEOLOGY TODAY November-December 19901195