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By T. Chandler, R. Buchan, J. H. Blowes, E. G. Haldeman

The regional geological setting and nature of the serpentinized ultramafic rocks are described. It is postulated that lateritization started in Miocene time. Repeated uplifts led to at least four physiographic cycles and to the development of a mature lateritic soil profile. Complete profiles are subdivided from top to bottom as follows: Zone A - chocolate-brown limonite; Zone B - ochre-brown limonite; Zone C - soft serpentine; Zone D - hard serpentine; Zone E - serpentinized peridotite; Zone F - ultramafic rock. Zones A and F rarely attain ore grade. Canga is conspicuously absent. Rocky ore of Zones D and E amounts to 40%, limonite ore of Zone B to 25% of total ore reserves. Nickeliferous serpentine is the major crystalline phase in Zone C. In this zone and deeper, crystalline quartz occurs, particularly in fracture zones where nickeliferous cryptocrystalline quartz is of ten accompanied by garnierite.

Jan 1, 1979

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing acid shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization-one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subse-quently mineralized by sulphides and barite.

Jan 1, 1937

By P. W. George

This paper presents geological data regarding deposits of over 7,500,000 tons of fine-grained sulphide ore in barite gangue. A series of pyroclastics and arkoses was intruded by sills of quartz porphyry in connection with batholithic intrusions of granite 3 miles from Buchans. Gentle folding, with fracturing and shearing of tuff beds and intruded quartz porphyry, accompanied and followed the intrusion of granite and porphyry. The sulphide-barite mineralization is localized primarily in fractured and sheared tuff beds, but also in the sheared quartz porphyry. Two structures have proved particularly favorable for mineralization-one, the center of an anticline; the other, a series of weak, incompetent tuff beds intruded by thin sills of quartz porphyry and located between strong beds of arkose. During the folding the weak tuff with intruded quartz porphyry was intensely sheared and contorted and subsequently mineralized by sulphides and barite. INTRODUCTION Buchans is 5 miles north of Red Indian Lake, in Central Newfound- land, at an elevation of 900 ft. above sea level and 400 ft. above Red Indian Lake, and is reached by a 37-mile private railway from Miller- town Junction. The first ore body found at Buchans was discovered some 30 years ago in the bed of Buchans River, by Matty Mitchell, an Indian woodsman employed by the Anglo-Newfoundland Development Co. Ltd. In the years following the discovery the ore was developed by shaft-sinking and drifting, with results indicating a lenticular ore body in a shear zone, containing about 100,000 tons of extremely fine-grained sulphide ore in barite gangue averaging about 0.05 oz. Au, 4 oz. Ag, 1.5 per cent Ch, 10 per cent Pb, 18 per cent Zn. Because a profitable metallurgical treatment for the ore was not found, the mine was closed down in 1911. In 1915, Mr. H. A. Guess, Vice President of the American Smelting & Refining Co., learned of the Buchans River ore body, and after metallurgical tests had been carried on from time to time in his company's testing plant a satisfactory separation of the sulphides by selective flotation was finally effected in 1925. Prospecting for additional ore bodies was begun in 1926, utilizing geophysical methods under the direction of Hans Lund-

Jan 1, 1937

By R. L. Alexander

"Madawaska Mines Limited, incorporated in 1975 is the successor to Faraday Uranium Mines Limited. The history of the latter's mine development and corporate changes are outlined. This paper describes the geology of the Bancroft area and the rock types found in the mine, particularly the pegmatite which is the host rock for the uranium. The structure, mineralogy and distribution of the ore shoots are described with the method of grade control and mine development. The paper concludes with a summary of the production and mineral reserves.Location, Access, and PropertyMadawaska Mines Limited is located in Faraday Township, Hastings County, Ontario. The mine is in the N.T.S. quadrant 31 F/ 4, Bancroft sheet and near 46 degrees 01 minute latitude, 77 degrees 46 minutes longitude. The mine is one-half mile north of Highway 28, five miles (8 km) west of Bancroft, and is accessible by various highways from Toronto, Ottawa, Peterborough, and Belleville. (Fig. 1). A landing strip for small aircraft is located at the northwestern edge of Bancroft. Bancroft is a modern community with a population of 2,400. The company has the mineral rights to 2982 acres (1207 hectares) surrounding the mine workings and plant which are situated in the north parts of Lots 16 and 17, Concession XI, Faraday Township."

Jan 1, 1986

By T. S. Smith

INTRODUCTION IN PREPARING this paper for the District 4 Meeting, three factors had to be considered. First, the paper must fit the time alloted; second, it must give a general picture of the geology for those unfamiliar with the property; and third, it must contain some new material in order to be of interest to local delegates. The most comprehensive extant discussion of the geology of the property of McKenzie Red Lake Gold Mines, Limited, is contained in Horwood's report on the general Red Lake area ( 1). This report is the 'bible' of the area, and a general paper on the geology of this particular mine would almost certainly appear to be a condensation of it. It was thought, therefore, that the most suitable procedure would be to base the general outline on Horwood' s report, to extend that outline where possible from information gained since its publication, and finally to leave dangling for the contemplative geologist some of the ideas and problems which ?are currently under consideration. LOCATION AND HISTORY The property of McKenzie Red Lake Gold Mines, Limited, is in Dome township, in the Red Lake mining division of northwestern Ontario. The mine is on McKenzie Island, about four miles north, by water, of the Hasaga mine and old Howey mine.

Jan 1, 1951

By A R. Bullis

Metal Mines Limited (Bancroft Division) was incorporated m 1964 to take over the assets of Faraday Uranium Mines Ltd., including their uranium deposit near Bancroft. Ontario. This paper outlines the geology of the Bancroft area, and. then go on to describe the principle rock types m the mine workings, especially the pegmatite, which is the host rock for the uranium mineralization. The structure and mineralogy of the orebodies are thoroughly covered, and, after a summary of the production and ore re-serve figures, the paper concludes with suggestions for further exploration work. Location and History M ETAL Mines Limited, Bancroft Division, is located in Faraday township, Hastings county, Ontario. The main production shaft and concentrator are about: Y2 mile north of Highway 28 and about 5 miles west of the village of Bancroft (Figure 1). The presence of radioactive minerals in the Ban-croft-Wilberforce area has been known since the early 1920's. Uraninite was found at the Richardson deposit near Wilberforce in 1922, and some attempts were made to produce radium from the deposits of the area between 1929 and 1931.

Jan 1, 1965

By Paul W. Kingston

In New Brunswick, during the 1970's, rocks of the Lower Carboniferous Windsor Group in the Moncton Basin of the Fundy Epieugeosyncline have been the target of intense exploration and drilling programs. Sylvinite ore was discovered in three structural basins of the Moncton Basin near Sussex through a drilling program sponsored jointly by the Federal Department of Regional Economic Expansion and the New Brunswick Department of Natural Resources. In 1973, exploration and development rights to the western end of the Moncton Basin were awarded to the Potash Company of America. One high-grade sylvinite unit, varying between 15 and 70feet in true thickness, with a strike length in excess of 5 miles, is located near the stratigraphic top of the assymetric, semi-diapiric, locally overturned anticline. Late in 1975, exploration and development rights to the Marchbank Syncline were awarded to International Minerals and Chemical Corporation (Canada) Limited. To date, a stratigraphic evaporite sequence, forming the semi-diapiric core of the syncline, has been shown to contain one major high-grade sylvinite unit averaging 70 feet in true thickness over a strike length in excess of 2 miles. Both properties appear to have potential considerably in excess of that revealed by the exploratory drilling, and both, because of numerous mineralogical, structural and stratigraphic similarities, are thought to be depositionally contemporaneous. Both potash deposits lie within 50 miles of the Saint John all-weather deepwater port, thus affording easy access to eastern and mid-western U.S. markets. Further opportunities for potash exploration in New Brunswick are considered excellent, as there are large untested areas with favourable geology and known potassium water anomalies and negative gravity anomalies occurring in the Moncton and Cumberland basins, and in the Central Basin of New Brunswick.

Jan 1, 1979

By M. J. Michaud, M. J. Lavigne

"Abstract - North American Palladium Ltd. operates its Lac des Iles open pit palladium mine 85 km north of the city of Thunder Bay, Ontario. The Roby Zone deposit occurs within the mafic/ultramafic Lac des Iles Intrusive Complex (LDI-IC), which was created by multiple pulses of magma of varying composition within several closely spaced chambers. Chaotic lithological distribution, the presence of magmatic breccias, and the rarity of rhythmic layering suggest a dynamic intrusive environment with disruptive magma pulses. As of December 31, 2001, measured and indicated resources for the 950 m long by 815 m wide Roby Zone deposit totalled 159 Mt grading 1.55 g/t Pd, 0.17 g/t Pt, 0.12 g/t Au, 0.05% Cu, and 0.05% Ni at a palladium cut-off grade of 0.7 g/t. The Roby Zone contains an additional 73 Mt of inferred resources at similar grades.The Roby Zone is dominated by varitextured gabbro containing pipes and pods of breccia, and large blocks (~60 m across) of varying lithology. Mineralization at Lac des Iles occurs as: (1) a PGEand base metal-rich magmatic matrix of breccia (breccia ore); (2) mineralized dikes or sills (gabbronorite in North Roby ore); (3) lower-grade mineralization in varitextured units that are host to the distinctive breccia ore and envelope the North Roby ore; and (4) high-grade mineralization associated with strong silicate alteration exemplified by high-grade ore.The close spatial association of the mineralized breccias with both varitextured units and silicate alteration leads to an interpretation that the energetic magma that created breccia was charged with a dissolved fluid, and that this deuteric fluid exsolved at high temperatures to migrate through crystal mush, enhancing crystallization along its pathways, resulting in variable grain size. This transformation occurred at high temperature and produced sulfide-poor, varitextured gabbro-hosted mineralization exemplified by some of the mineralization in the North Roby Zone, and also found throughout the Roby Zone. The association of hydrous silicate alteration with mineralization can be explained by continuing fluid migration during cooling and continued metal transport. Résumé - North American Palladium Ltd. opère la mine à ciel ouvert de Lac des Iles située à 85 km au nord de Thunder Bay, Ontario. Le gisement Roby Zone est encaissé dans le complexe mafique/ultramafique de Lac des Iles (LDI-IC), lequel représente une intrusion polyphasée créée par plusieurs pulses magmatiques de différente composition à l’intérieur de chambres magmatiques fermés. La distribution chaotique des lithologies, la présence de brèches magmatiques, et la quasi-absence de litage rythmique suggèrent un environnement magmatique dynamique perturbé par l’introduction de nouveau magma. Au 31 décembre 2001, les ressources mesurées et indiquées s’élevaient à 159 millions de tonnes titrant 1,55 g/t Pd, 0,17 g/t Pt, 0,12 g/t Au, 0,05% Cu, et 0,05% Ni, pour une teneur de coupure de 0,7 g/t Pd. De plus, la Roby Zone contient 73 millions de tonnes de ressources inférées à une teneur similaire.La Roby Zone est principalement encaissée dans un gabbro de texture hétérogène (varitextured) caractérisé par des cheminées et des lentilles de brèches et des énormes blocs (environ 60 m de diamètre) de plusieurs lithologies. Au Lac des Iles, la minéralisation en EGP et en métaux de base se retrouve dans la matrice magmatique de brèches (breccia ore), dans des dykes ou des sills minéralisés (gabbronorite dans la zone North Roby ore), comme minerai de basse teneur encaissant le minerai de brèche (breccia ore) et enveloppant la zone North Roby. Du minerai de haute teneur est également associé avec une forte altération en silicates dans la zone high-grade ore.L’étroite association spatiale entre les brèches minéralisées et les unités de texture variée (varitextured) et l’altération en silicate suggère que le magma énergique qui a causé la bréchification était chargé de fluides. Ces fluides deutérique"

Jan 1, 2001

By P. C. Benedict

Introduction and Summary The Northern Empire mine is a mile east of Beardmore, and 100 miles northeast of Port Arthur, district of Thunder Bay, Ontario. Production started in March, 1934, and terminated in September, 1941. During this period, the mill treated 425,866 tons of ore, from which 153,103 ounces of gold were recovered. The lowest level from which ore was mined was the 1900, but considerable drifting was performed on the 2075 level and 800 feet on the 2415, the deepest level. The following description of the geology of the mine is recorded by the senior author but is based on the observations and complementary mapping of both authors. The vein strikes about N.72°E. and has an average dip of 80°S. (Figure 1). In stoped sections, the quartz averaged about two feet wide. On the 1725 level it was drifted on continuously for more than 7,000 feet, but in the mine as a whole practically no commercial ore was found beyond points 1,400 feet west and 1,800 feet east of the shaft. Conspicuous wall-rock alteration extended throughout this section but not much beyond its limits. There was some splitting of the vein and widening of the alteration halo on the lower levels. The average general colour of the quartz changes with depth. It may be generalized, from top to bottom, as light grey to dark grey to brownish. The brownish quartz first appeared near the bottom of the ore.

Jan 1, 1947

By A. M. Bell

General Summary THIS paper attempts to describe in a preliminary and general manner the nature of certain copper discoveries now being developed by Gaspe Copper Mines, Limited, in Holland township, in the interior of the Gaspe peninsula. Some copper mineralization appears to have been known here at the time of the earliest French explorations, was rediscovered in 1921, and has been under intermittent development by Noranda Mines since 1938. In the last two years discoveries have enhanced the picture so that the deposit now promises to develop into one of the important Canadian copper producers. As ideas are constantly changing with continuing development, any picture given now is very partial and tentative and must be subject to future revision. The nature of these copper occurrences differs from others known in eastern America. In many respects they have unique features but they are most closely akin to some copper deposits found away from the intrusive rocks in the porphyry copper districts of the western United States. The most important orebodies are replacement deposits in a limestone horizon in which the ore gangue is converted to skarn. These lie at considerable distances from any known intrusive but seem to have been derived from a buried stock of granite that intrudes the sedimentary rocks of Lower Devonian age. This intrusive has produced alteration effects in the overlying rocks that may afford a key to locating other ore areas in the Peninsula.

Jan 1, 1951

By Horace Winchell

AN EXAMINATION of the Pachuca and El Oro. districts in July, 1920, although cursory and incomplete, disclosed facts of more than passing interest to the student of ore deposits; and inasmuch as the literature on these districts is limited and some of their features are little understood, a brief account may prove valuable as reconnaissance observations to be amplified by more thorough and competent observers in the future. Where no complete monograph of important mining camps has been published a partial presentation of the data is often useful, as it sometimes leads to fuller and more accurate descriptions, by stimulating discussion. The following notes are presented with the consent of Mr. A. F. Main, managing director of the El Oro Mining and Railway Co., whose fund of information and wide acquaintance with both districts alone made it possible to cover so much ground in a short time. I have also to acknowledge gratefully the aid of Messrs. C. A. Lantz and D: S. Calland of the Santa Gertrudis and Real del Monte companies, respectively, in connection with permission to inspect geological features of interest in their mines.

Jan 6, 1921

By James D. Sisler

Location and Age The main bituminous coal field of Pennsylvania lies in approximately twenty counties west of the mountain area which extends in a northeast southwest direction through the central part of the Commonwealth. The coal fields lie in a dissected peneplain, still in the youthful stage of erosion There are numerous V shaped valleys in the bituminous fields and the tributaries of the larger streams have rather steep gradients The main streams flow in rather narrow valleys with comparatively small flood plains. The coal beds of Pennsylvania are of Carboniferous age, and are confined to two systems, the Permain and the Pennsylvanian The latter system is divided into an upper or Pittsburgh series and a lower of Pottsville series The Peimain system is divided into an upper and lower series The Pottsville series of the Pennsylvanian is represented in western Pennsylvania by the Upper Pottsville only The upper or Pittsburgh series of the Pennsylvanian is represented by the Monongahela, Couemaugh, and Allegheny groups Geologic Structure. The rocks of the bituminous coal fields are folded into many anti clines and synclines extending in a general northeast direction across the western part of Pennsylvania The intensity of this folding in creases toward the mountain region West of Chestnut Ridge, which is in Fayette, Westmoreland, and Indiana counties, the folding is minor, and the coal beds have low dips East of Chestnut Ridge, v here folding is stronger, the basins are wider and the coal beds rise steeply on the flanks of the anticlines Geology. The bituminous coals of Pennsylvania are associated with shale, sandstone, clay, and limestone Each group has different proportions of these deposits, and the proportions vary at different localities within the same group.

Jan 1, 1928

By Alichurch P. D

Perseverance nickel deposit is located at latitude 27¦ 491S, longitude 1200 42'E, 330 km north of Kalgoorlie, Western Australia. Gossanous outcrops were discovered in April, 1971, and after further detailed surface investigations, percussion drilling led to diamond drilling by June, 1971. Up to December, 1972, 127 diamond holes totalling 45,590 m were drilled to indicate 33 million tonnes averaging 2.2% Ni using a 1% cut-off grade. The deposit occurs in a lenticular ultra- mafic unit emplaced in metasediments locally forming the eastern flank of the Archaean green- stone belt trending NNW from Leonora to Wiluna. To the east a major strike fault separates the metasediments from gneiss; westwards there is a sequence of metavolcanics with further ultra- mafic units. Length of the lens is 3500 m and it attains a maximum width of 800 In. The eastern contact is moderately regular, but the western contact is prominently embayed. Local strikes are NNW, and dips are steeply W. A set of strike faults cuts the ultramafics and enveloping quartzites. These are normal faults, parallel to the major eastern fault, dipping 65-70¦W. They impart a serrated pat- tern to the sub-outcrop of the western contact. Massive serpentinite is the dominant rock in

Jan 1, 1973

By L. G. Westgate

PART I.-AREAL GEOLOGY§ PIOCHE lies 240 mi. southwest of Salt Lake City, in southeastern Nevada, 19 in. west of the Nevada-Utah line. It is at the end of a branch line (33 m.), which connects at Caliente with the Los Angeles and Salt Lake division of the Union Pacific System. Its commercial relations are with Salt Lake City and Los Angeles, chiefly with the former. The surrounding area is part of the Great Basin, an arid region of alternating mountain range and intermont plain, the latter floored with outwash from the mountains. About Pioche the plain varies between 4700 and 6000 ft. above sea level. The town lies in a valley at the east base of a low northwest-southeast range (the Pioche Hills) 12 miles in length, which rises about 1000 ft. above the adjacent flat. West of the. Pioche Hills is a higher north-south range consisting of two parts: to the south the Highland Range, between Bennett Pass and Stampede Gap; to the north the Bristol Range, from Stampede Gap to Bristol Pass. This double range reaches altitudes of 8000 to 9000 ft., or more, (the highest point, Highland Peak, is 9395 ft.) and rises some 2500 ft. above the surrounding plain. It is continued in lower hills to north and south. Smaller ranges rise from the flat west of the Highland and Bristol ranges. The area studied and shown on the map (Fig. 1) is covered by 3 one inch to the-mile topographic sheets: the Highland Range, the. Bristol Range, and the Panaca, the latter mapped in part only. The sedimentary rocks of the district include Paleozoic limestones, sandstones and shales, Pliocene tuffs, and modern wash. Igneous rocks are represented by intrusive dikes and stocks and by extensive lava flows of mid-Tertiary time.

Jan 1, 1927

IntroductionHistory of MineTopographyGeology of AreaGeneral DescriptionIgneous Rock TypesGranodioriteQuartz monzoniteApliteGranite porphyryMetasomatic ActionAlteration of monzonite/Alteration of apliteGeology of Ore BodyNature of OreZones of MetasomatismAssociated Fracture PlanesDistribution of Copper MineralisationNature of Copper VeinsQuartz-chalcopyrite veinsQuartz-calcite-chalcopyrite veinsEuhedral quartz veins/Non-euhedral quartz veinsStructures Accompanying Ore BodyApliteIntersecting lines of metasomatised monzoniteMetasomatised aplite

Jan 1, 1949

By J. E. Armstrong

"IntroductionT'HE PRODUCTION of gravel and sand may be considered to be the major mining operation in the Lower Fraser Valley of British Columbia. At least thirty pits are in operation with a yearly production probably in excess of two million yards and a value in excess of one million five hundred thousand dollars before crushing, washing, and sizing. The value of the finished products would probably be double the above figure.Since 1949, the writer and his co-workers have been engaged in the geological investigation of the Lower Fraser valley and adjoining Coast mountains for the Geological Survey of Canada. The study, which is not yet completed, includes both bed-rock geology and geology of the unconsolidated sediments lying above bed-rock. In a rapidly expanding industrial area, .an advance knowledge of the geology may• greatly aid in future 'planning, and in many cases may .prevent not only the wastage of large sums of money, 'but possible disaster. Some of the present and future applications in which geological information in the Lower Fraser valley should be of value are as follows: the development of domestic, irrigation, industrial, and municipal groundwater supplies; drainage for industrial sites,, roadbeds, and farmlands; flood control along the Fraser river and smaller streams in the area; the location of dam sites, of major tunnels for water supply •and sewage, of road-beds, of foundation sites for large buildings .and other engineering undertakings in which geology may aid; the evaluation of oil and gas •possibilities; the production of building stone; and the production of sand and gravel, the subject with which this paper is primarily concerned."

Jan 1, 1953

By J. P. Golightly

The nickeliferous laterites of Soroako are described in their setting in the huge Cretaceous ultramafic complexes of central Sulawesi, Indonesia. The ore bodies occur on spurs, ridges and hill flanks beneath remnants of extensive erosional surfaces. Weathering pro- files that have developed on unserpentinized harzburgite and on strongly serpentinized lherzolites show distinctive laterite structures, mineralogy and chemistry. The former are unique to the Soroako area and permit an unusual degree of upgrading by rejection of unserpentinized peridotite boulders. A mass balance calculated for a selection of profiles indicates that in situ leaching of a column of peridotite 20-50 meters thick has taken place with only minor lateral migration of nickel in solution.

Jan 1, 1979

By Robert B. Smith

The South Texas Mineral Trend is now estimated to contain uranium reserves of 150 million pounds U308 . Within the past year, an estimated 10 million pounds U308 have been added to this gross reserve. It is probable that a similar amount has been identified in previously unknown orebodies that, as yet, have not been delimited or announced. Exploration that was limited in the past to a narrow band containing only the known trend has now expanded into older sediments updip and into younger units towards the coast. Uranium host formations are also now being explored at a considerable depth and distance eastward from known deposits. Only about 30 percent of the potential uranium host rocks in South Texas have been adequately explored. Geology The South Texas uranium deposits are confined mainly to sediments of the Tertiary system. Reserves are divided almost equally between the Whitsett Formation of the Jackson Group, the Catahoula Formation, and the Oakville Formation. A minor amount of the reserves occurs in sands of the Goliad Formation which may be either in the Tertiary or Quaternary Epoch. Figure 1 is a geologic column of the South Texas uranium host formations. These producing formations are marked with a mine symbol but there are also several prospect symbols that denote potentially favorable uranium host formations both younger and older from the producing formations. It is generally accepted by most workers in South Texas that the source for the uranium is the volcanic ash that is abundant within several of the formations. Likewise, the required reductant is considered to be hydrogen sulfide gas, derived from deeper seated hydrocarbon accumulations, that emanate upward along fault zones into favorable host-rock sand units. Within this basic framework of source, host, structure and hydrocarbons is where most of the reserves have been discovered and where most of the current exploration is either concentrating or expanding. Structure in South Texas is predominantly faults. Swarms of faults exist in zones paralleling the coast and running from the Rio Grande to the Sabine River. These faults are usually growth faults with the down-dropped block on the coastward side. Displacement may range from a few feet to a few hundred feet. Dips are near vertical in the younger rocks at the surface but become flatter as the fault cuts older beds in the subsurface. A map of the oil and gas fields in South Texas indicates a correlation between these fault swarms and accumulations of hydrocarbons. It is not coincidental that the known uranium trends closely follow the hydrocarbon accumulations and the faults swarms, all of which supports the theory of uranium concentration by groundwater movement through volcanic ash-rich beds into favorable host rocks impregnated with reducing hydrogen sulfide gases that migrate upward along fault planes from hydrocarbon accumulations. History Newcomers to South Texas are often amazed that active entry is possible in a district that has produced uranium for over 20 years. Understanding the conditions and occurrences of the past would explain why the opportunity still exists for companies not now active in South Texas to become active. Uranium was discovered in the middle 1950's in sandstone units of the Jackson Group at Tordillo Hill in Karnes County. This discovery was followed by a rush involving most of the major uranium exploration companies as well as several of the not-so-major. Those western prospectors who were used to numerous outcrops and neat land subdivisions were further discouraged by the small size and low grade of the deposits. Then after a brief blast, they left South Texas as they found it and returned to the richer diggings of New Mexico and Wyoming. Susquehanna Western was the only one to stay and develop mines in the area. Eventually they discovered enough ore along the Jackson outcrop to warrant constructing a small mill. They managed, with limited budget and diligent effort, to find enough ore to keep the mill going and eventually expanded into exploration in other formations. By the late 1960's, Susquehanna was mining from both the Jackson and Oakville deposits. About this time, the oil companies began to enter the uranium industry and found, that because of sound forward planning, they controlled the uranium on vast tracts of acreage. At this time, which was more than ten years after discovery, there was so little literature on South Texas uranium deposits that the oil companies began following the known trends and off-setting known orebodies. This, and a few kicks on some well gammaray logs, lead to the discovery of new areas in formations that previously had n o uranium discoveries. Still, the following of the trend as it crossed from one formation to another was the main geologic guide. Nowadays, we in South Texas feel that science has entered into the quest to discover new orebodies. The work of Galloway has indicated new pathways to explore. The understanding of multiple stages of oxidation and reduction has created some doubt about areas drilled in the past and abandoned. The expanded use of oil well logs and geochemical prospecting has lured the more progressive exploration companies off the mineral trend and into unexplored areas. Prognostication The fact that uranium exploration in South Texas has been active for only the past ten years is not an indication that South Texas is not a major uranium district. The geology of the South Texas uranium deposits as described here serves only to indicate that similar geology extends in all directions from the known mineral trend as can be seen on Figure 2.

Jan 1, 1979

By T. L. Tanton

Introduction Sturgeon River area, on the east side of lake Nipigon, Ontario, was the scene of a gold rush in 1934. According to press reports, the active staking during the latter part of the summer spread out rapidly from the early holdings until it embraced practically all of the lower basin of Sturgeon river in a belt up to ten miles wide extending west from Kinghorn for 35 miles to lake Nipigon. And, before winter set in, active prospecting and claim staking reached beyond lake Nipigon to areas where belts of ancient schists were known, notably west of Obonga lake. The writer's familiarity in past years with the areas to which attention has been directed admits of some observations on means of access in the field, the general geology, and the progress that has been made in identifying formations favourable for the occurrence of gold. Canoe Routes From the writer's observations in Sturgeon River area in 1917 and in the Obonga Lake area in 1933, it is recalled that there is, locally, a striking dif~ ference in the accessibility of the two areas by travel along canoe routes. Sturgeon River area is easily accessible from Kinghorn or Jellicoe stations on the Canadian National railways. Many small lakes, commonly of the linear type and with elongations east and west, occur among the forested rocky ridges near Jellicoe (Figure 1) and to the east and west along, or adjacent to, Sturgeon river. This stream has long stretches with gentle current between the falls and rapids. The drainage system provides excellent canoe routes (Figure 2), and the interruptions to travel (Figure 3) are remembered .as scenic features that were passed by portages with firm footing. West of Obonga lake, the streams flowing easterly to lake Nipigon may be followed through scenic canyons to a plateau of law relief characterized by extensive muskegs and shallow, brown-water lakes; and along small streams, where beaver dams have been destroyed, there are muck ponds where the usual alternatives of paddling or portaging can be dismissed in favour of the 'moosing' method of progress with the canoe (Figure 4).

Jan 1, 1935

The Teutonic Bore deposit lies in a major greenstone belt within the Archaean Yilgarn craton of Western Australia. It occurs towards the base of a suite of tholeiitic basalts, some 100 m above a felsic volcanic pile of rhyolitic composition. Sediments comprise a minor, albeit important, percentage of the mine stratigraphy.The deposit consists of a single, steeply dipping lens of massive sulphides totalling 1.4 million tonnes grading 4.16 per cent Cu, 16.4 per cent Zn, 1.22 per cent Pb and 203 g/t Ag. In addition, cross cutting "stringer" mineralisation in the footwall contributes a further 0.75 million tonnes at 2.38 per cent Cu, 1.92 per cent Zn and 52 g/t Ag to the mining reserves. Principal primary sulphides in massive and disseminated mineralisation are sphalerite, pyrite, chalcopyrite and galena, while minor amounts of arsenopyrite and argentiferous tetrahedrite are also present. Weathering has affected the primary mineralogy down to at least 90 m, resulting in a strongly leached oxide profile to about 85 m, overlying a thin, erratic zone of chalcocite supergene enrichment.Lateral metal zoning is marked both in massive sulphide and stringer mineralisation, with Cu/Zn ratios decreasing away from the centre of the orebody. Alteration is well developed in association with footwall stringer mineralisation, changing from a central Fe-Mg carbonate, chlorite and silica alteration zone below the massive sulphides to an outer halo of sericitisation. The spatial distribution of these minerals is patchy. Geochemically, the footwall alteration zone is characterised by central Cao, Na20 and Sr depletion (with less regular enrichment of SiO2 , Fe and MgO), surrounded by a peripheral zone of K20 enrichment.Evidence supports a classic volcanic-exhalative origin, involving submarine discharge on the flanks of a rhyolitic dome and accumulation of the massive sulphides in a local palaeotopographic depression. The sulphides overlie their feeder zone as shown by alteration and stringer mineralisation. Tholeiitic wallrocks are thought to be genetically unrelated to the mineralising solutions, although their presence as a cap over the felsic volcanics may have permitted the build up of a circulating metalliferous brine system prior to sulphide deposition.

Jan 1, 1984