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ABSTRACT
Gold is found intimately associated with the sulphide minerals in several
Precambrian iron formations . Arsenopyrite and pyrrhotite .generally make up the bulk of the sulphide, while lesser amounts of pyrite, chalcopyrite, and/or loellingite may be present . Quartz, chlorite and carbonate are the common` gangue minerals, however iron rich garnets and amphiboles may be present where metamorphism has- reached the amphibolite facies .
Sulphide minerals at the Homestake and Contwoyto Lake deposits are the most obvious examples of sedimentary exhalitive origin, even though they have been highly deformed and metamorphosed . Sulphides at the Cullaton Lake deposit and Central Patricia Mine are related to brecciated and deformed zones in quartz magnetite iron formation . They are characterized by remobilization at lower (greenschist facies) metamorphism and excellent replacement textures present . These deposits are more i nti miately associated ;; i th volcanic rcc1;s and represent a more proximal facies of exhalitive iron formation . '
Gold deposits in the Little Long Lac area are of a similar type . All of these deposits show significant similarities and differences, even within a single area . A model emphasizing an exhalitive origin and including modification by later events and contributions by other processes best explains the origin of these iron formations and their associated gold deposits .. INTRODUCTION
Spectacular increases in the price of gold recently have been accompanied by an equivalent increase in interest and activity in many known gold deposits .
Gold deposits of particular interest in this regard are those related to Pre- cambrian iron formation . The Homestake Mine is the largest gold mine in North
America . It is a classic mineral deposit and is well documented in the liter- ature of economic geology . Two other deposits, namely the Contwoyto Lake property of the International Nickel Company . of Canada and the Cullation Lake
"B Zone" of O'Brien Gold Mines Limited were discovered in the course conven- tional prospecting in the early nineteen sixties . Unlike many former producers that were high-graded or proved uneconomical even with the relatively low mining costs of the thirties, these deposits contain significant tonnages of ore grade material averaging 0 .75 oz/ Au/ton . Their main disadvantages have been and are remoteness of location coupled with expensive capital costs re- . lative to proven ore reserves . Several gold deposits in Northern Ontario' are also related to sulfides in Precambrian iron formation, particularly in the
Crow River, Little Long Lac and Kirkland-Larder Lake areas . These areas con- tain several long term profitable mining operations and several of which°ilave also been the subject of recent feasibility studies and diamond drilling . The locations of known gold deposits of this type in North America are shown in
Figure 1 . Finally, the reader's attention is drawn to the reports of gold found in iron formations from Australia, Brazil, Central and Southern Africa, and India (Sawkins~and Rye, 1974), however, these are beyond the scope of the present study . f The Homestake Mine
The Homestake Mine is located at Lead, South Dakota near the northern end of the Black Hills . It was discovered in 1978 .during the working of rich` placer deposits in Deadwood Gulch . During the 9G years it has been in operation, over 2 30 million ounces of gold and 7 million ounces of silver . have been produced .
The geology of the deposit .-(Figure 2) has been described by several company
geologists, including Staughter (1968), Noble (1950), Noble et al .(1949), and Noble and Harder (1948) .
All of the ore is confined to the Homestake formation, a fine-grained
quartz-sideroplesite schist csideroplesito + (Fed5 Mg25) COD which is com- monly further metamorphosed to a coarser grained cummingtonite-grunerite schist
above the garnet isograd . This unit is approximately 200 feet thick but true stratigraphic thicknesses are obscured by thickening in the noses and thinning
in the limbs of folds . Conformable with the Homestake formation are the under-
lying Poorman formation - 2,000 feet plus of grey laminated phyllite or mud-
stone and the younger Ellison formation - 3,000 feet of grey to black quart-
mica phyllite and interbedded quartzites .
Tertiary pplift due to intrusion of .quartz monzonite stocks and porphyry
=" sills created a large dome structure with Paleozoic sedimentary rocks dipping outward from a core of Eocet`e sfocks and Precambrian schists
. Within the Pre- I1 cambrian schist area, rocks are tightly and complexly folded (Figure 2) . Early
isoclinal folds in which the rocks have deformed plastically during flexural slip folding plunge 10° - 45° to the southeast, with axial planes dipping to
the northwest . In numerous instances the axial planes are themselves folded .
. These folds vary from the dominant Poorman anticline (several miles in
length) to much smaller folds that may become so tightly closed that some :
formations are separated into pods-or-lenses . A later phase of folding in- volves superposed "cross folds" caused by penetrative shear folding along
planes at a small angle to the axial planes of the earlier folds (Chinn, 1970) .
These folds are often best developed in the noses and occasionally on the limbs
of the early isoclinal folds, where they cause a pronounced thickening of'the
Homestake formation and form favorable structures for the localization of
mineralization . • 3
In three dimensions these mineralized structures form pencil or rod like ore shoots . These shoots may coalesce with other shoots and continue at depth until their fold structure dies out . Ore forms only a very small amount of the known Homestake formation (Norton, 1974) . The ore bodies are more or less completely chloritized portions of the cummingtonite or sideroplesite schist-of the Homestake formation . The ch'lorit- ized areas no longer contain the sedimentary quartz bands prevelant in other parts of the formation but rather abundant vein quartz which appears-to be derived from the sedimentary quartz and may be localized in the cross folds
(Plate V, Noble, 1950) . The chlorite wall rock immediately adjacent to these
veins generally carry good values of gold . The chlorite schist usually con- tains slightly less than ten percent sulphide minerals, mainly pyrrhotite''or
pyrite with a smaller amount of arsenopyrite . Pyrrhotite and pyrite may contain small inclusions of gold and occur as tiny grains and elongated lenses of grains often aligned along the bedding of the chlorite, cummingtonite, or
sideroplesite schist . Medium to coarse grained euhedral arsenopyrite crystals occur concentrated
in zones parallel to bedding . Arsenopyrite is most abundant in the chlorite
zones and containsmost of the high grade gold in the form .of tiny inclusions
and veins . The average grade of ore from the Homestake Mine has been about
0 .33 ounces of gold per ton of rock for several years . In addition to the Homestake deposit and the recent placer deposits, gold
has also been found in the basal conglomerate of the-Cambrian Deadwood form- ation (believed to be a fossil placer) and in vertical fractures of-Tertiary
age found in Paleozoic rocks of the Lead area . In the early 1900's some Oro- duction was obtained from gold-arsenopyrite mineralization related to plunging
fold structures found in cherty iron rich meta-sediments similar to but st ra- tigraphically higher than the Homestake formation in the Roubaix-Galena district
southeast of Lead (Bayley, 1970) and in the'Rochford area south of Lead (Bayley,
1972) . 4
Tertiary geologic activity and mineralization have been used in the past
to argue for a Tertiary hydrothermal origin far the Homestake ores (eg . Noble, 1950) versus a Precambrian hydrothermal or syngenetic origin . The only strong evidence for Noble's Tertiary origin of the Homestake min- eralization is the areal distribution of tertiary ore bodies . Chinn (1970) has shown that the "cross folds" to which the ore bodies are restricted, were probably not formed by tertiary intrusives `(Rye and Rye, 1974, p . 297) . On the other hand considerable geologic and isotopic evidence (Table I) indicates a Precambrian origin in a sedimentary-exhalite environment followed by later
1,600 tl .Y . Precambrian folding and metamorphism to produce the mineralized structures .
Folded iron formation (quartz-grunerite schist) south and south east of
Lead are considered to be worthy of more exploration (Bayley, 1970 ., 1972 and Norton, 1974) . Meanwhile, exploration and development continues at the Home- stake Mine as it approaches the end of its first 100 years of production .
Contwoyto Lake
A number of gold occurrences have been discovered in iron rich sediments or anphibolites of the Yellowknife Supergroup -in the Point-Itchen-Contwoyto Lake area, District of MacKenzie, of the Northwest Territories, approximately 250 miles northeast of Yellowknife (Figure 1) . By far the most important deposit, however, is the . "main showing" of the International Nickel Co . . of Canada, located near the southwest shore of the north end of Contwoyto Lake, (Figure 3), latitude
65°46' north, longitute 111°14' west, N .T .S . 76 E/14 . This was discovered in
1960 as .the result of INCO's "gossan hopping" technique of prospecting . The gossan was spotted from a fixed wing aircraft, samples were taken out by'heli- copter, and assays resulted in interesting gold values . In 1961, INCO staked 314 claims to cover the deposit . This touched a staking rush which continued into 1962 during which several hundred claims were staked adjacent to the INCO property . A permanent camp was erected and an extensive program of diamond 5 drilling, trenching, geological and geophysical surveys were carried out at the main showing curing the summers of 1962 and 1963 . One estimate of reserves at the main showing is several million tons of material exists that has a grade of 0 .30 ounces per ton or better (Knutsen, 1974) . too reliable figures of the size and grade of this deposit are available . . The regional geology has been described by Tremblay (1966 and in prep .) and,
Bostock (1967), while descriptions of individual mineral showings are given in .
Tremblay (1966 and in prep .), Baragar and Hornbrook (1963), Schiller and Horn- brook (1964), Schiller (1965) and DIAND asse'sment files . Most of these showings are gossans related to gold-sulphide mineralization in amphibolite lenses or beds within certain stratigraphic units of the Yellowknife Supergroup . They occur more or less continuously along .a broad belt of Yellowknife sediments stretching northwards from south of Point Lake, carving eastward through Itchen
Lake to Contwoyto Lake eventually passing-southeastward along the soutwest shore of Contwoyto Lake (Figure 3) . Similar deposits have been noted on the east-and Crest sides of Bathurst Inlet (Thorpe, 1972) another 60 miles northeast of Con-
-twoyto Lake . In the Contwoyto Lake area, low to medium grade meta-sediments of the
Yellowknife Supergroup frequently occur as frost-heaved blocks scattered in a
chaotic fashion and form large areas of feq enmeer . . On the few outcrops'' that exist, it is not uncommon to find large blocks of meta-sediment which have been
pushed straight up from deeply Pointed bedrock by frost action . Leucocratic medium to fine-grained quartz feldspar gneiss occuring as
domes and grading into massive granite are the oldest rocks in the area . The Yellowknife Supergroup is mainly argillite and greywacke (phyllite and quartz-
feldspar schist) and metamorphic equivalents . ('i .e . H'odullar cordierite-anda- lusite bearing quartz-biotite schist and gneiss .) Basic volcanic rocks and re- lated gneisses and amphibolites form a distinct basal unit while garnet-grunerite amphibolite bands and lenses derived from iron rich sediments are restricted to the youngest units of the Yellowknife Supergroup (Tremblay, in prep .) . These rocks were intruded by gabbro (amphibolite) and then biotite-muscovite granite
(2,495 M .Y . = Wanless et ..al . , 1974, p . 39) before the end'of the Archean . Gen- erally flat lying sedimentary rocks of the Proterozoic Goldburn Group rest
unconformably on the Archean rocks . Diabase and gabbro dikes and sills cut all other rocks in the area .
Folding of Archean rocks in the Contwoyto Lake area is related .to granite intrusion and metamorphism . In the vicinity of INCO's main showing isoclinal
folding has occured ; to the south west a dome structure predominates . Locally amphibolite bands may indicate refolding of earlier folds or appear relatively undeformed ._ Gentle folding of the Goldburn rocks took place at a much later
time . . ,_ The main showing occurs in a 50 foot wide garnet-gr%nerito amphibolite which is enclosed in the greywacke-argillite sequence and has been deformed
into a large steeply plunging fold structure (Figure 4) . Within this folded-
' unit, a complex variety of deformational features including pseudo-conglomerate or boudinaged quartz, stretched and pulled apart strata, local intrusive fea-
tures, a great variety of drag folds,~ .(mainly conguent with the major fold
but showing a large variety in size and style) and late quartz filled tension
veins show that the pysical properties and style of deformation varied with
time and lithology (Plates ) .
The amphibolite unit is generally thin bedded, with individual beds
only rarely as wide as two feet across . Rocks vary from .fine to coarse grained, shistose to massive, black to light green, zero to greater than 80 per cent almandine garnet, zero to 80 per cent sulphide, and include sugary textured
quartz bands, chlorite schist, and several varieties of amphibolite or iron formation . Minor amounts of pyrite and magnetite occur, however, carbonate
minerals are absent from the amphibolite due to non deposition and/or metamorp-
hism . Where weathered the sulphide bearing amphibolite has a rusty surface or
gossan . 7 Two large drag folds, one on each limb of the major fold contain most of
the sulphide and gold mineralization .and most of the larger late quartz veins . In these folds the rock is a laminated to thin bedded sulphide-bearing amphi-
bole The amount of sulphide is normally less than 20 per cent but may exceed A 80 per cent of the rock in places . Pyrrhotite occurs as thin laminae, while
coarse euhedral to subhedral crystals of arsenopyrite (FeAsS) with loellingite (FeAs2) cores up. to one inch long (Plate ) are concentrated in bands parallel
the foliation . These crystals carry most of the gold in the deposit with more
than 70 per cent of the visible gold present at the loellingite-arsenopy .rite boundary (Bostock, 1968, pp . 72-76) . The late quartz veins generally give
very low in gold values but occasionally native gold can be found in them ..
Comparison of the Homestake and Contwoyto Lake Deposits
McConnell (1964) first pointed out several of the striking similarites found in the Northern Black Hills Homestake area and the Contwoyto Lake "main
showing'area" including "stratigraphy, metamorphism, structure and mineraliza- • tion" . Although differences also exist between the two areas, notably the
absence of saloons,sideroplesite and other carbonates at Contwoyto Lake, the absence of loellingite and late diabase dikes at Homesta ke, different ages of subsequent granite intrusion, and a much greater proportion of mudstone or ar-
gillite to greywacke at Homestake ; probably greater differences exist within the
respective areas (eg . grades of metamorphism and intensity of folding) .
In both areas : Grunerite-cummingtonite amphibolites derived from iron "
rich sediments are found in a similar sequence of argillite and/or greywacke of
probable .Archean age, several bands or lenses of amphibolite are known, as ; are t many small showings, however, only one deposit in each area appears economic at
present . These deposits contain similar structural controls (confined to secon-
dary folds), mineral assemblages and textures : coarse gold- bearing arsenopyrite,
fine-grained laminae of pyrrho.tite, minor pyrite, chalcopyrite, and magnetite . 8
The gangue includes grunerite-cummingtonite-, chlorite, almandine garnet and two generations of quartz, early sedimentary beds which have a sugary texture and
late veins related to folding and mineralization with a vitreous or glassy
texture . A complex history and style of structural deformation occurs in both
areas, as do well defined examples of progressive metamorphism . Precambrian
meta-gabbros or orthoamphibolites also occur"in both areas .
Cullaton Lake
The Cullaton Lake deposit (Figure 1) is located 250 miles northwest of
.Churchi l 1, Mani toba, i n the Southern District of Keewati n, N . U1. T . (latitude 610 0 l7'N, longitude 98 31'W, N .T .S . 65 G/6,7) . In 1961 H . MacDonald, a prospector in the employ of Selco Exploration Company, discovered gold in quartz-magnetite
iron formation by panning crushed material from a rusty frost heaved boulder,
' . in the area between Mountain Lake and Cullaton'Lake . Following this discovery _ ' emphasis on Selco's exploration program was shifted from examination of . Pro- -
terozoic quartz-pebble conglomerates to a search for and examination o the iron formations . Several more zones were located by sampling rusty boulders
and outlined by magnetic surveys (Figure 5) . Considerable work, including
geological mapping, arsenic soil geochemical surveys, geophysical surveys (mag-
netic and EM), trenching and diamond drilling were done during the*1962 and
1963 field seasons . Most of these zones contained low erratically distributed gold -values, however, only the "B Zone" appeared to be of economic interest
and most of the work was done in this area .
The geology of the area has been described by Eade (1964, 1966 and 1975) . Lenses of quartz-magnetite iron formation occur conformably in a thick grey-
wacke-argillite-tuff wacke-argillite-tuff unit of Archean age . These sediments overly and inter- tongue with volcanic rocks of predominantly basic composition . These rocks,
" known as the Henik Group, have undergone at least two periods of folding and have been intruded by both Archean (2570±90 m .y .) and Hudsonian (1,700±50'm .y .) 9
granites and show evidence of two periods of metamorphism (Eade, 1975) ..
Henik Group sediments show progressively higher grades of metamorphism in a northerly direction towards the contact with a large granite mass . Some of the iron formation occurring in the almandine-amphibolite facies of iron.forma-
tion has similar mineralogy to the Contwoyto Lake deposit . including quartz, magnetite, grunerite-cummingtonite, almandine garnet and minor sulphides (Eade, 1975) .
A thick sequence of Proterozoic sediments, the Hun•witz Group which The "B Zone" occurs approximately mid-way between Cullaton Lake and, Mountain Lake . It consists of a mineralized unit of banded quartz-magnetite iron formation which is relatively unmetamorphosed but is locally highly folded and fractured . Consultants for the present owners, O'Brien Gold Mines Ltd . (1973) have calculated reserves of 'approximately 185,000 tons after dilution of 0 .97 ounces gold per ton" from more than 30,000 feet (68 holes) of diamond drilling on the B Zone . This band contains several lenses of magnetic iron formation over a strike length of half a mile . It strikes N 10° W and has an average westerly dip of 45°, but has a steep dip near surface, flattening to near horizontal at 200 feet and then steepening until it is cut by a sub-horizontal fault at 400 feet . The iron form- ation is frequently separated from the greywacke by 0 - 50 . feet of a carbonate rich tuff unit on the hanging wall side and 0 - 20 feet on the foot wall side . 10 Mineralization is usually found in irregular and discontinuous quartz-chlorite- carbonate-sulphide rock . High gold values are associated with abundant chlorite and pyrrhotite, but high pyrrhotite and chlorite do not necessarily contain high gold . Abundant coarse grained arsenopyrite does not contain-good gold values . Four en echelon, steeply plunging ore shoots have been recognized in the B Zone . They cut across the bedding of the iron formation and appear to be related to fracture zones and/or folding . . An additional gold occurrance occurs in shear zones in the basal Proterozoic Hurwitz quartzite at shear Lake three to four miles north of the B Zone . Only a couple of short intersections of economic interest were found in extremely oxid- ized gold-pyrite mineralization . Mineralization in the iron formations is not comparable to this . . Crow River Area The Crow River area of Northwestern Ontario (latitude 51°30'N longitude. 90°W) - lies .160 miles northeast .of Iynace on the Trans Canada lfighv,ay. or 215 miles north- northeast of Thunder Bay . Two important former gold producers occur in the area and both contain gold mineralization related to iron formation . The Central Patricia Mine produced over 650,000 ounces of gold between 1935 and 1951 and the Pickle Crow Mine produced about 1,450,000 ounces of gold from 1935 to 1966 . The regional geology of the area has been mapped and described by Thomson (1939, p .5) . Basic lava flows of Keewatin (Archean) age make up the predominant rock formation . Interbanded with the lavas are narrow bands of iron formation, other fine-grained sediments (greywackes) and fragmental rocks such as agglomerate, volcanic breccia and tuffs . Granite, porphyries and associated acid-rocks intrude the older Keewatin complex . The gold deposits are generally associated with iron formation . Locally tuff may grade into ferruginous greywacke or lean iron form- ation with .magnetite and quartz-siderite-magnetite laminae . 11 Bands of iron formation are found at several horizons in the volcanics, however, they seem to be concentrated in the upper part of the Keewatin-series . The iron formation occurs in bands a few inches to 250 feet thick . Some of these bands can be traced for miles, while others pinch and swell or die out along strike . During regional deformation, the Keewatin rocks were tightly folded into a series of anticlines and synclines which strike and plunge to the northeast . Only a small percentage of the area is rock outcrop and exploration has consisted of tracing magnetic iron formation with a dip needle and diamond drill- ing . Gold deposits in the Pickle Crow area are characteristically associated with complex fracturing and tight drag folding of brittle iron formation and massive -greenstone . Shear zones in the less competent lavas and undeformed iron forma- tion do not provide favorable targets . Two genera;Itions of quartz occur at . _ the Central Patricia and Pickle Crow Mines . The later variety is white, unfrac- - tured and largely devoid of gold values" (Thomson 1939, p . 28) . a) Central Patricia Mine The Central Patricia Mine occurs on the north limb of a large anticline and although several bands of .iron formation are present only one contains ore . Sev- eral fairly irregular ore shoots were mined and most of these were confined to well -fractured zones i n the hanging wall (north) side of the iron formation (Figure 8, Thomson, 1939), however, a few angled across the iron formation from hanging wall to footwall . There is also a tendency for the fracture groups to occur near points of curvature along the hanging wall contact . Gold is asso- ciated with abundant pyrrhotite and arsenopyrite fi lled fractures in the . iron formation . These fractures also contain abundant quartz, carbonate and green chlorite . The chlorite seems to be related .,to sulphide and gold content (Bar- rett and Johnston, 1948) . Mineralized fractures vary in thickness from 1~ to 12 . 10 inches and in width from 2 to 40 feet . They strike across the band of iron formation and normally stop abruptly at the iron formation-greenstone contact . Both the ore shoots and mineralized fractures dip or "rake" eastwards at-an aver- age angle of 55 degrees . A complimentary set of joints and barren fractures dip to the west at an average of 55 degrees . According to Thomson (p . 39, 1939) "the iron formation adjacent to . the fractures has been partially replaced by sulphides and carries low gold values ." "Arsenopyrite occurs as distinct crystals, largely in vein quartz and to a lesser extent in iron formation . Pyrrhotite is always in irregular shaped patches, small grains or stringers . It occurs as rows of tiny grains parallel to the bed- ding of iron formation, along fractured zones in arsenopyrite crystals,and as veinlets in quartz (Thomson, 1939, p . 42) ." This texture (top photo, p . 40, Thomson, 1939) is similar to those found at Homestake and'Contwoyto Lake (Plate ),. A study ~ . by M .H . Haycock (1936) showed that 38 per cent' of the gold was free in quartz- . chlorite gangue, 28 .3 per cent was associated with pyrrhotite, 18 .9 per cent wO th- arsenopyrite, 11 .6 per cent with pyrite and 3 .2 per cent with 'chalcopyrite . The . average grade of the ore was about 1/3 ounce of gold per ton, although stringers assayed up to 11 ounces per ton (Barrett and Johnston, 1948) .- b) The Pickle Crow Mine - The Howell Vein The main ore zone, the Howell Vein, occurs less than five miles east of the Central Patricia Mine on the south limb of a northeasterly trending and northwesterly dipping isoclinally folded syncline $ . The vein is associated with the only known tight fold in this part of the series, which has produced a thick- ening of the iron formation (Corking, 1948, p . 374, Figure 1) . The vein inter- sects the iron formation at an angle of 40 degrees on the east side to 10 degrees- on the west side and extends into the enclosing lavas for several hundred feet on either side . The stresses that were relieved by shearing in the lavas, pro- duced brecciation and shattering in the-more competent iron formation . The 13 vein itself contains several large drag folds and many smaller ones . Gold con- tent is generally higher along these folds . Regional and local fold axes and the line of intersection between the vein .and the iron formation all have an average plunge of 70 degrees in a N 25.E direction . Typical vein material is banded white quartz with chlorite and tourmaline where the host rock is greenstone and sulphides . where the host rock is iron - formation . In the greenstone, the grade , width&,( average is 3 feet) continuity and orientation of the vein are remarkably persistent . In the more brittle iron formation , stope widths up to 20 feet have been mined because of many parallel fractures filled with mineralized quartz . Locally , in mineralized sections and particularly in the area of large drag folds (eg . Figure 16, Thomson, 1938), massive sulphides (pyrite and pyrrhotite) appear to replace iron formation but the sulphides themselves carry low values of gold . c) Miscellaneous Veins Several other small gold deposits and showings have been discovered in the Crow River Area, descriptions of most of them can be found in Thomson (1938) _ and/or Ferguson (1966) . One of the most economically important of these is the Number 2 vein of the Pickle Crow Mine . Here the main vein is not associated with iron formatin, but a similarly competent "quartz porphyry ." In general , hotirever, most of these smaller showings are closely related to the iron formation and contain considerable`tuartz and minor sulphide zone" described by Ferguson (1966, p . 81-82) appears to most closely resemble the F,or;~estake-Contwoyto mi neral i zati on discussed earlier . Comparison of the B Zone and Central Patricia Deposits • _ This comparison was first made by '~ in a report for SELCO ( DIiND, 196 ) . Several similarities are striking and the comparison • appears to be a valid one . In both instances the iron formation plays what 14 appears to be an important role in the origin and depositional controls of the gold mineralization . The-author believes that these deposits reflect a distinc- tive end member type in the larger classification of iron rich sedimentary- exhal i ti ve deposits (eg'. the }iomestake-Contwoyto end member) . Little Long Lac Area . The Little Long Lac gold camp occurs in the townships of Lindsley', Errington and Ashmore approximately 125 miles northeast of Thunder Bay, Ontario . Geologi- cally it is located at the east end of an east-west, trough-shaped belt of "Keewatin" metavolcanics (basic to intermediate lavas, tuffs and volcanic breccia) and "Temiskaming . meta-sediments (predominantly greywacke with lesser amounts of iron formation, conglomerate, arkose and slate) of Archean age . These rocks have been intruded by granite and granodiorite .batholiths, albite porphyry sills and diabase dikes . Early regional folding about a roughly horizontal, east-west axis has been locally overprinted by'a complex pattern of tightly folded minor folds and 'drag folds which typically plunge at 30 degrees in a westerly direction (Figure 6) and form fold patterns not dissimilar to those at Homestake Mine . (Figure 2) . The regional geology and the geology of individual mineral deposits of the Long Lac area has been described by Bruce (1935, 1937), Pye (1952) and Horwood and Pye (1955) . Between 1934 and 1953 nearly two million ounces of gold were produced from several mines in the area . The gold mineralization largely occurs in iron form- ation , albite porphyry or greywacke and is frequently localized along fracture zones , drag folds and/or lithologic contacts, particularly where the competency of adjacent rock types differs . The relationship between gold mineralization and iron formation is best developed in the "North or sulphide Zone" of the Hard Rock Mine and the ad- joining MacLeod-Cockshutt Mine (Horwood and Pye, 1955 and Matheson and Douglas, 1948), although in several other deposits, including the Magnet, the Bankfield 15 and the Tombill Mines . Gold is found adjacent to or in the proximity of tightly ' folded bands of magnetite-hematite iron formation . In the north or sulphide zone (Figure 6), gold mineralization is closely associated with sulphides,, pre- dominantly pyrite, arsenopyrite and some pyrrhotite which "replace" the iron formatiQn in the noses of folds and certain favorable sedimentary horizons . "In places that ore is beautifully bandedlowing to the selective replacement of the sheared less competent greywacke laminae in the iron formation by the sulphides . In other places the replacement has been so complete that original sedimentary structures are largely obliterated and irregular masses of sulphides enclose only mere remnants and vestiges of partially replaced sediments (Hor- wood and Pye, 1955, p . 60) . Many short irregular quartz veins occur in the sul-• phide zone but volumetric- ly .are not important-. The quartz is commonly barren except where it contains sulphides . Like other deposits of this type, mineralized ore shoots die out when their associated folds . die out and not all folds or all sulphides are ore bearing . Finally mineralization is not restricted to one type - even within a single mine . I 1 Ore in the "No . 2 Vein"(Figure ) is .also "beautifully banded" . 16 Larder Lake Area Ridler (1970, p . 39) proposed that the gold bearing carbonate ore bodies of the Larder Lake area (eg . the Kerr Addison Mine) are in fact auriferous car- bonate facies iron formation, probably correlative with the Boston iron formation . The siliceous pyritic carbonate horizon is folded conformably with the sediments and volcanics in which it lies and locally displays sedimentary "banding" . A unique feature of the Larder Lake area is the spectacular green color of much of the carbonate, due to chlorite and fuchsite - a chromium mica . Although chromium rich rocks are also reported to be related to auriferous iron formation in Brazil (Dorr and Miranda Barbosa, 1963) . In common with the other areas discussed, the country rocks have undergone M a long history of facturing, folding and metamorphism . Wodification by these processes explains much of the diversity observed in the gold deposits . According to the second stage of Ridler's genetic model, during metamorphism, the carbonate recrystallized and segregation of some of the silica and gold into dilat onal . stockworks occurred . Locally the intensity of metamorphism and deformation was low enough that unveined cherty auriferous carbonate survived . 17 Similarities and Dissimilarities of Gold Deposits in Iron Formation Common features of gold deposits in iron formation are summarized in Table II . The various deposits discussed previously are also compared and contrasted in Table III . Several of the featureseg . high gold : silver ratios and abun- dant chlorite are common to many gold deposits of diverse origin and conse- quently of relatively minor significance relative to the origin of these unique deposits, however, other features like the facies of iron formation, thepropor- tions of coarse clastic, fine clastic .and chemical sediment are important and useful environmental parameters (Figure 7) . These can be used to show more subtle differences between gold deposits in iron formation and outline sub- classes of deposits, eg . the Homestake-Contwoyto Lake type versus the Cul atop Lake-Central Patricia type discussed previously . Many features, including sulfur isotope analyses, detailed sulphide equili- bria, fluid inclusion, petrologic and structural studies etc, await comprehensive analyses and evaluation at many of the deposits . They may or may not provide- . useful information .-__ The Origin of Gold Deposits in Iron Froamtion . Processes which have been used to explain the gold deposits in question are listed in Table IV . It can be seen that many of these processes are related and gradational with each other . It seems safe to say that the origin of any deposit is not the same as any other and no single process adequately explains any one of the deposits, Each process has its merits and failures . Like the transmis- sion of light, more than one theory may be required to explain our observations . When we are limited to a poorly exposed two dimensional slice of a three dimensional object and an even more clouded time dimension and all the variables that go with it, we are not in a position to develop rigid theories of origin . Most geologists, actively working with these rocks today, would probably favor 18 a ,working model involving an early volcanic exhalite chemical precipitate process which becomes important during relatively brief lulls in clastic sedimentation and a second, later metamorphic and deformational event which causes remobili- zation and localization of the mineralization . .Exploration Possibilities Geophysics and geochemistry, used in association with careful geologic studies and prospecting, offer excellent exploration possibilities to finding any additional gold-iron formations that exist, and I'm sure that they-do exist . Reconnaissance geology and magnetometer work and possibly lake sediment or whole rock sample geochemistry should be useful in outlining large areas with potential . Electromagnetic (g . VLF) and induced potential 'surveys should indicate local - anomalies . In the Homestake and Contwoyto Lake areas where the gold is inti- ~-mately related with arsenic minerals, arsenic soil geochemistry appears to be . _ very useful, however, its value in the other areas is .definitely not as promising . In some cases it may locate arsenopyrite but not gold . Gold .is still where we find it, however we have found it in iron formation a number of times and will no doubt continue to find it and base metal deposits -tea,-" if we look for it . All of the deposits mentioned were ultimately found because someone looked for and found the gold . In several cases earlier geologists un- doubtedly rejected the iron formation after a cursory evaluation as not suitable for iron ore . All of the areas discussed have seen further exploration activity in the last two years and are likely to see more if the price of gold continues to rise . Of particular interest and potential are the two deposits at Contwoyto, Lake and Cullatop Lake in the Northwest Territories there has been no commercial F production from these deposits, in large part due to there remote .location . In this regard, it should be noted that the Homestake Mine was also originally in a remote location . Acknowledgments The author would like to express his gratitude to many geologists who have helped him with this study . Worth of special mention are Gordon tlelson of the Homestake Mining Co . and his colleagues J .E. Mullock and E . Pattison of the International Nickel Co . of Canada Ltd ., Don Esson consultant for O'Brien Gold dines Ltd ., Drs, Bostock, Eade and Trembley of the Geological Survey of Canada prided access to their unpublished data . Robert Hornal, of the ;Depart- R ment of Indian Affairs and Northern Development, Yellowknife, N .W .T . introduced the author to the project and offered encouragement and support throughout . Douglas Bryan, also of DIAND, was a capable co-worker and appreciated companion during visits to Cullaton Lake and Contwoyto Lake . TABLE I . Evidence for a Precambrian versus Tertiary origin of the Homestake Gold Deposit . 1 . Fossil placer gold deposits in the basal conglomerates of the Cambrian Deadwood formation . ' 2 . The ore is restricted to one stratigraphic horizon the Homestake formation u of undspited Precambrian age . 3 . Ore textures can be interpreted as sedimentary or metamorphic . 4 . Similar mineralization is found in folded Precambrian iron formation at Roch- ford (20 miles south of Lead) where Tertiary activity is absent and in- other examples' of gold in iron formation . . 5 .- .Sulfur isotope .data (Rye and Rye, 1974) indicate that the sulfur in the Home- stake for-ation and other Precambrian iron formations at Rochford are syngenetic and probably derived from the reduction of sea water sulfate . .. s . Oxygen isotope data (Rye and Rye, 1974) from various types of quartz in the - • if Homestake fine show a strong dependence on local wall rocks but data from late Tertiary quartz are completely independent of wall rocks . ~ . 7 . Fluid inclusions in quartz and arsenopyrite have high and variable C02/H20 role ratios and high CH4 content compatible with a metamorphic origin .of the mineralizing fluids-(Rye and Rye, 1974) . 8 . Lead isotope data (Rye et al ., 1974) on .galenas from mineralized parts of the Hoc;estake formation and other age data indicate metamorphism and intru- sion in the Black Hills 1,600 m .y . ago, including deformation 'and mineraliza- tion in the Homestake formation . The Homestake formation may be 2,500 m .y . old, or it may incorporate abundant detritus of this age .* Lead isotopes from Tertiary galenas have had different growth histories . TABLE II . Common Features of Gold Deposits in Iron Formation - These ore deposits are found in sedimentary iron formation host rocks . - The iron formation typically occur as bands or lenses in a much thicker argillite-greywacke sequence . - The iron formation commonly occurs near the top of the sequence, while-asso- ciated volcanic rocks (tiffs and basic lavas) often intertongue at the base of the sequence . - Iron formation facies types frequently show complex and detailed relationships . - The iron formations are early Precambrian in age . - Common ore mineral assemblages and textures are present : arsenopyrite (usually coarse subhedraI to euhedral megacrysts) - pyrrhotite (fine grained anhedral and parallel bedding or banding) - pyrite (variable proportions) - chalcopyrite (rare) - gold (very rare) . - Common gangue and metamorphic minerals : abundant quartz (usually at least - two generaltions) and ehlorite (tends to indicate mineralized areas) and variable carbonate (frequently siderite or ankerite, sideroplesite at homestake), also grunerite-cummingtonite, almandine garnet (where metamorphism has reached the amphibolite facies) .and abundant banded'or minor disseminated magnetite . - At least one and more commonly multiple metamorphic and deformational events . The later producing complex patterns of tight isoclinal folds, refolded folds and zones of brittle fracturing, which are important controls for the location of elongated ore shoots . - Frequently gold mineralization not directly related to the iron formation are found nearby . - The deposits all have high gold-silver ratios . - Many of these areas are underlain by very poorly exposed outcrop and the iron formation must be traced by geophysical methods . TABLE IV . Processes that might Contribute to the Origin of Gold Deposits Associated with Iron Formation . Plutonic Hydrothermal Volcanic Exhalite Sedimentary Chemical precipitate Clastic Placer Metamorphic Recrystallization (simple) Remobilization (metamorphic differentiation and segregation) .r Captions to Figures Figure I . Index map showing location of Precambrian gold, deposits related to iron formation . 1 . Homestake - South Dakota 2 . Contwoyto Lake - Northwest Territories .3 . Cul l atop Lake - Northwest Territories 4 . Crow River - Northern Ontario 5 ._ Little Long Lac - Northern Ontario 6 . Larder Lake - Northern Ontario Figure 2 . Geology of the Lead area, South Dakota (after Noble and Harder, 1948) . Figure 3 . Geology of the Point Lake-Itchen Lake-Contwoyto Lake area, showing ' to ' known gold occurances (after Bostock, 196 ) . Figure 4 . Geology o f the ; jai n showing Con twoyto Lake . Figure 5 . Geology of the Cullaton Lake area (after SELCO 1964 DIAND asses.. lent files) . Figure 6 . Geology of the Hard Rock Mine property (from Matheson and Douglas, 19A8) . Figure 7 . Schematic representation of sedimentary facies of iron formation before overprinting of metamorphic facies . TABLE III SUMMARY OF GOLD DEPOSITS IN IRON FORMATION Homestake , Contwoyto Lake, Cullaton Lake, Crow River, Long Lac, Larder Lake, South Dakota . N .W .T : N .W .T . N .W . Ontario . N .W . Ontario . N. Ontario . Main facies of iron formation C03> Si>S Si >S Mgt> C03>S M&t> CO3>S >Hem C03> S Y Metamorphic green schist - green schist - :green schist - green schist - green schist green schist - facies of gold amphibolite amphibolite ' ampiibolite ceoosit s . Structural - shoots - shoots - shoots - fractured and - fractured and quartz filled control parallel secon- parallel in related-to drag folded iron drag folded iron stoc'kworks in dary or "cross drag folds fracture zones formation formation? folds and fault folds" - c•ut by faults .. carbonate Minerals asso- Asp > Po>(Cpy) Loel-Asp> Po(Cpy) Po> Asp> Py(Cpy) . . Po-Asp> Py(Cpy) Py> Asp> Po(Cpy) Py-Asp> Po(Cpy) ciated with gold Qtz Chi Carb Qtz Chl Qtz Chl Carb Qtz Chl . Qtz C03 CO 3 Qtz Chl Gold mineral- -Tertiary joints -Shear zones in Quartz porphyry Deposits in other Felsic plutons i zati on not i n Pal.eozoi cs . .Proterozoic sediments and (syenite and related to iron -Cambrian placers quartzite "porphyry" trachyte) formation .-Recent placers CO carbonate grn sch green schist Loel loellingite. Qtz quartz ' Si 3 silicate amph amphibolite . Asp . arsenopyrite Chl chlorite S sulphide Po pyrrhotite COS carbonate M t magnetite Py : ' pyrite Hgy m hematite Cpy- chatcopyrite' ~ GOLD DEPOSITS -RELATED. To PRECAMBRIAN, IRON FORMATION ., r :••~Ct~; Its ~J G Ur"'5 4 .~ .~' r! . Kr;^Str.x'+T~. . ,.' ,"fi3m~.C.`*r+^w+t~ :F;. XT. ; y.,-; rs~{. Y~.T1..r~wmVWri .r~+n+- .r.yS!rytir ';FY! -ym -' /9 nwf DISTRIBUTION OF THE PIE-CAMP,RIA SE1)IJIE TARY ROCKS AND TFIE ' METAMOI:1'IIIC ZONES IN TIIOSI ROCKS I VIE LEAF) DISTRICT . A B . C pr \~ g f / 6 2 / l 1 l 1 \ ~-~_. 12/ % 6 G 1 *~ j Hypothetical section along lines A-8, 8-C and C-D jf Sf• .6 1 .A lichen . . - : n - - - 31 C a 5' . 63 - GSC - LEGEND (Simplified) • ( -~ Kroted schist. greywacke• phy4Gte: mirtx g!'eenschi;; who • : emph-b rite; - _ 6 f 6a. ro :%s of lower rnetarrorp•4ic gra :la equiia:er, to 6 i ~ 2 Vo emcc rooRs and related Pock s ma"ar to 5 and 6a F31 amph.-botua but inc:~dri amphibo/re #s . . j ~i I Sdiceojs gneisses Fault ...... ~. ~~~fff 4 a Miles 5 SO 15 - ;t G E Granitic rocks S Figure. Hypothetical section 2nd generalized map of the Yell o vknife Group in Itchen Lake map-area . ( ~ f , ~ /9 I) h 't e GCLD P PCJ !T 41,4/f~ SNt71 ,h " X Gcc~ ~cGATiGN - a .01 1 . 7 tr. n .r. w r ~:u . 4.1 /,; ? - X.- - ..4ill 1 i t s S% \ f cas ., . 1 1 tA .4 1 l C6,ms s f t PLA!4 N 0 91 kSL w•x 9 (PLAN k0 115 b 1161 Ovv 1 ` D -9 c. ,x% ----ZONE B S1 ~ ZO JE-A t Iii f PLAY x30. It Pt All 14. 7 s a r Do. a . r~. T4S1 S• NO 12) VIP Do- .? y AK R1y£R , CAMP 11 ' (FLAR t90 13) c .f 1 A .S .1 .r Fig. :-Gco!ogical plan, 250-Icat Hid Pock nu i nc . •• . ' .~ 1 tl ') ;i G oul 'mar C!'!J. /_l yJ lJ cj~ ~~' ~ r 'Bara gar , W .R .A, , and Ifot~nbzook, .E . ; I, , 19$3 : "Uneral industry of district of 1+iaclcen pie ; 1963 ; Cep,, .S:1rv_, Catt, , Paper 63-J, pp . I3-3Z, 1 Bayley, R. «'., 1970, Structure and mineralization of Precam- brian rocks in the Galena-Roubaix district, Black Hills, South Dakota : U .S . Geol. Survey Bull . 1312-E, 15 p . 1972a, A preliminary report on the geology and gold deposits, of the Rochford district, Black Hills, South Dakota : U.S . Geol . Survey Bull . 1332-A, 24 p .. W72b, Preliminary geologic map of the `etno district, Black Hills, South Dakota : U .S . Geol . Survey Misc. Geol. Inv. N1ap 1-712. Bostocl ., 11 .11, 1967 : Geological Notes, Itchen Lake Map-Area, District of Mackenzie, Part of 76 E -and SG H (Report, figure an 1 Map 8-1966) ; : eo2 . Su_v . Cast . Paper 66-24, 13 pages . - \j 1968 : - Gold A send ,; x ite _Loellingite_Pyrxhotite deposits in A-niphiholite, ` _ _ Itchen Lake Cont-'oyLo Lalce area,* District of t .fackenzae ; Geol ._Surv, € '. ._ _ .. .-72-76 (Rpt, Can.; Paper 68-1 Part B pp' . of Activities, Part B, 1 Nov . ttf 1967 to March 1968) . ~aJe K. E. /1W . !'rclintinar y report, Ko~ ~ Call. :rj lsc<' . Parcr 64-,)7 'na" : . map-area (east-half) District of Ke : ak River ; ratio ; Geol ("0" half), Distric : t of F . Surer 4 .ceti•tat .n Geol. Sur~. Can paper 65 ` Bade K E in press : '!'he i.o ttal : I.zvcr Area District o f ILee~rratlit, N orthtiresL Territories GoY.4Surv,_ Can . t . lem . 377 . Metallegenic . W. f idler R . H . and Suffef C . G Hutchinson R A model for Archean relationships in the Abitibi Belt. Canada ; i' . 1971 . 106-15 . metatlogeny. Tr•ns. Can. Inst. ,1Ajn. ,Weta /. 74 ...... I• 1. .. . .J I' . . ... f Mi-Conndl. G . W. 1967 : Notes on similarities bcl een some Canadian gold depa'- of South Dakota; Econ . Gcol ., v. 59. No. 4, p. 719-720• ts and the Home take d >rnitf .lt 6 r ~Zt the H ~ IC h oble . J. A., t~R' tua~sP6ta ~,~,~„~/,O, ~oca!-Fefil:'~Soc. J1rRCR'=~.~~"l`~! F• 't t , W"'Ore tnineralization in the HomestakeW gold minei` _1950, . 61, p, . Soc. America .,Bull v Lend, South Dakota : Geol 2221-251. StratigraPhY end , J . O ., 1944, : - Noble . J. A•, and Harder StackHillsandthe metamorphisminapart o[thenorthern Dakota: Geol . Soc. America Homestake mine, Lead, South v. 59, P• 941-935 . . : Bull ., . A . L. . 1949. Struc- Harder, J• O•• and Slaughter and the ~, I`oble, J. A . northerrt Black HiRa lure art or the America part South Dakota : Geol. Soc. Homeetakeof a mine, Lead, ` .352• Bull ., v. 60 p . 321 Norton, J. J.. .eE% . p~Blgl~il/ G~cD 1011155 ,, /973 t ), Geo?odp of Errindtor. Tov~•nship, Little E, G (1951 . ]sires, V. (,O Ft. 6 . lone LIP. Area; On :. Dept Ridler P,, F{ R Cant27 . 7970.a33- 2rde flakesrerea olcanrc , Or. .er.o V sta ;r_ .o. Proc, yeo% Rye. D. 1I. as R 3,e, .DakSo p 1 . CeoIogy . 29 Stab, o ©es studs tal, gold - 7. es. Schijler . E .A ., aid Itornbrooic, £ .>i, ' 2S•SS : E'inetal industry of district of :acF :!rtLLt , 1963 : Gent . Sttrv, C~ n .s Paper 61,31-22 . pB . 10-16, . Schiller, E,A . 2£05 : Mineral industry of the Nozti :rrast oreitaries, 1964 ; Gr_o]~_gisii_:__il .. Paper 65-11, pp ; 12-14 . < Slaughter, A. L ed. . 1966, The Hontestake mine,. 1) in Ridge, ~• . Ore deposits or the United States, 1933 Sales .1967 (G raJ t n. 7 volume), v. 2: Am. Inst . 1lining, Metall., and Petro!eum Engineers, p . 1436-1459. p . Treati,lay, L .n, 2966 :Contteoyto Lamwp-area District of : ;aciCenzie p 76 E/!q) :rt of 76 S/11 and ; Geol . Sur•• . C 1n: ., Paper fi5-21 and a lap 12-1 1967 .665., : 17 pa .,es, : Conttroyto Lake rt_tp_area, Dx'o- t trict of S!ac ; ;enzie (76 E/1g) ; Geol . M1 . n .! . Paper . 666-28 and ;'a Is 10-19 . 66, . 16 paves . v ~ i AWA 0- pw Copy : W .L. Kurtz v AMERICAN SMELTING AND REFINING COMPANY 51f TUCSON ARIZONA August 12, 1974 MEMORANDUM FOR : J .J . COLLINS ANVIL MINE FARO, YUKON Cyprus' open pit operation, located 125 miles northeast of Whitehorse, was visited on July 13th with Messrs . Osborne, Ritchie, Anzalone and Gale . Newt Cornish, Manager, showed us around . Tons • Pb Zn Ag!_ Published reserve : 63 million 5 .7% 1 .2 oz . Production 1973 : 2 .9 million 4 .6% 6 .2% ?' Original mill capacity of around 7000 tpd was expanded and recently brought up to 12,000 tpd . However, the mine has not kept up with the mill and only a few weeks supply of ore is exposed in the pit . Mining is at the rate of 10,000 tpd ore and 60,000 tpd waste . Exploration drilling was on a 300' grid with a few interspaced holes, but this proved insufficient for planning the pre-production pit, and far less ore than scheduled was mined during the first year of operation . Mining cost, including indirect, was stated to be $1 .00 per yard of broken rock . Taking ore (8 .5 cu . ft/ton) and waste (12/ton) densities into account, the average cost per ton amounts to about $0 .60 . The main ore zone, a flat lying tabular mass of pyrite, pyrrhotite, galena and sphalerite, is 2400' long, up to 1100' wide and up to 300' thick . The ore and the enclosing argillite stand quite well on 450 slopes ; however, considerable bank failure was evident in the granitic intrusive rock on the north wall of the pit . Mill recovery was reported to be 85-90%, with a 52% Zn concentrate and 70% Pb . Freight to Skagway, $20 .00/ton . The Anvil is one of the three stratiform ore deposits in Cambrian sediments, lying several miles apart along the northwest trend of the Pelly River, a major structural lineament . According to crock (Geophysical Exploration Leading to the Discovery of the Faro Deposit, CIM Bull ., Oct ., 1973) massive sulphides of the Vangorda deposit (9 million tons of 9% combined Pb zm)' were exposed in a creek and gossan outcropped at the northend of the Anvil zone . f 1 J .J . Collins -2- August 12, 1974 However, attention was directed elsewhere and drilling of coincident magnetic and gravity anomalies resulted in the Swim discovery under 50' of overburden -- -- 5 million tons of 10% combined Pb-Zn and 20 million tons of mass ive-pyr-ite . Ultimately, mineralized float was recognized in the Anvil area and the' deposit discovered by drilling coincident geochemical and geophysical anomalies . Tuffaceous greenstones are interbedded with the phyllitic host rocks' and according to Campbell-Ethier (Sulphur Isotopes, Iron Content of Sphalerities, and Ore Textures in the Anvil Ore Body, Canada : Econ . Geol ., Vol . 6-9, No . 4) . The deposits were probably formed by volcanic-exhalative activity in a Cambrian marine basin and thus bear no genetic relation to the granitoid intrusives of Cretaceous Age . Although only traces of barite were detected in the isotopic and textural studies, an average barite content of 6-7% was reported on our visit to the mine . ~'J .H . Courtright JHC :vmh cc : Sal Anzalone 1 r a. G 1 2 r h u'"` 1 a ~ G~ c u 1t AMERICAN SMELTING AND REFINING COMPANY We L-,K . Tucson Arizona January 5 , 1972 J 1 31972 TO : W . L . Kurtz FROM : J . D . Sell Massive Sulfide Exploration Technique J -ome -Prescott Area Yavapai County, Arizona This is to transmit Mr . Peter Walker's file memo on the subject . Peter reviewed the literature while in Tucson and noted the similarity of features and geology of the Jerome area to other areas of Precambrian geology elsewhere in the world . His original sketch on C . A . Anderson's Bulletin 1324-C, Figure 3, paper is included for reference, although the . redrafted f igure clearly shows Peter's subdivisions . -. As pointed out verbally by Walker, prospecting for new Jeromes and Iron' Kings would be primarily along the two main horizons, but the other favorable zones could contain good mineralization . All pyritic and chloritic zones would be sampled in looking for indicative trace mineral .- ization or halo effects . The down dip projections would then need to be drilled in looking for the massive sulfide zone . USGS geologic maps, mainly at 1 :24,000, are available for the area and would greatly facilitate an exploration program in the district . James D . Sell L- JDS :lad Enc . AMERICAN SMELTING AND REFINING COMPANY Tucson Arizona December 10, 1971 FILE MEMORANDUM Jerome-Prescott Area A brief examination of literature on the massive sulfide deposits in the area, particularly the United Verde and Iron King deposits, indicates that these deposits show many features typical of the socalled "volcanic exhalutive"' deposits found in many parts of the world, particularly in Precambrian rocks . In particular, these deposits show very similar features both on a regional and local scale to the large producers of this type found in Archean rocks . The stratigraphic column in this area shows the same features of cyclic volcanism found in these other areas . In particular, they show several cycles of basaltic-rhyolitic volcanism with each successive cycle becoming more acidic as a whole ascending the column . In general, mineralization appears at the top of the rhyolitic phase immediately before the change to a more basic phase of volcanism and is usually confined to rhyolite fragmentals,' but often with associated pipe-like bodies in the underlying rhyolites . These bodies typically show a halo of chloritic alteration in the underlying rocks and around the pipe-like stockwork deposits as is shown at United Verde . At one deposit in Australia, this chloritic alteration zone showed as a prominent colour anomaly . The mineralized horizons often are highly siliceous and show marked concentrations of hematite and pyrite features well displayed apparently at the Iron King deposit . Both the Iron King and United Verde occur near the top of the cyclic sequence at the close of the last full recognizable cycle (see attachment) . Two full cycles can be recognized in the Ash Creek Group and three in the Big Bug Group . The tops of the lower sequences ; e .g ., the Buzzard rhyolite, the top of the Green Gulch Volcanics rhyolitic member, and of the Spud Mountain rhyolitic members, are also favourable zones for mineralization . Deposits of this type tend to form clusters near vent zones and may show very large variations in size in one area and a copper-zinc tabular ore body may overlie a pipe-l'i'ke copper ore body . P . N . Walker PNW :1a`d Attach . cc : JDSelI f .A ORE DEPOSITS E Geology of the eillenbach Massive Sulphide Deposit, ; r , Quebec (CIM) Bulletin for November, 1973 67 78 The Canadian Mining and Metallurgical «. Economic Geology Vol. 67, 1972, pp. 73I-7S8 Stockwork Molybdenum Deposits in the Western Cordillera of North America K. F . CLARK 731 3 r 4~ Economy Vol . 67, 758 K. P. CLARK * Pt: FEB9 'i"372 Bunker , Missouri 63629 February. 4 , 1972 . W(;,L. K, JUL 2 .6 1972 Conference Comparative Sedimentoloav The following -is a brief summary of five of the discussions that :wer.e given at the Conference on -Comparative Sedimentology, Miami, : ,. :January 27-30 . Of'the ten discussions, Del willl summarize the first five, and I .the remaining five . ' The basic theme of the conference was the application of knowledge of recent sedimentary'pro'cesses to ancient carbonates _r .! ", . The talks were . .extremely authoritative and well-documented . Frequent references we :~ made to classic areas . of study of recent sedimentary processes, seve-a' unknown to me .-Concentration was on comparatively rapid facies chanr :s, '"-commonly those dominated or characterized by reefs, and little reference 'was made to widespread, blanket-like deposits, such as the Knox or the 'Upper Ordovician formations . The Bonneterre facies of Southeast Missouri . " fits very well into 'the, "models" discussed . The discussions by'Bosselini and Zankl were closely related and are here considered together, Zankl briefly outlined the three-fold process of reef evolution : development of an organic framework with accompanying incrustations, sedimentation in cavities withinn and around the framework, and cementation . Carbonate cement was described as early fibrous and later blocky calcite . Comparison was made of carbonates of the northern and southern Alps . .Bosselini divided carbonate platforms into two stages ( epicontinental and oceanic) and summarized with a diagram showing the forms of Middle Triassic through Upper Jurassic carbonate platforms . These were compared with forms'of " platforms in other areas . An evolutionary process in the forms of carbonate platforms was implied . Klovan described major reef development in western Canada . All ,reefs are underlain by a carbonate platform with an underlying Un- conformity . It w.as pointed out that the Leduc reef occurs in a basin . Possible tectonic controls . of reefs were discussed . Fault control was considered, but-no major evidence of this is known . Evidence of climactic control includes the hooked shape of individual reef bodies and the gradual slope of the windward side as compared to the leeward .side . Pinnacle reef forms of the Rainbow area were attributed to reef development on mud mou'nds . .in the Keg River Formation . Water depth .,during reef formation,wa.s'indicated by the type of reef-forming organism present, and a depth sequence of organisms was outlined . :.This consists of corals (deep), tabular stromat'olites'(moderate), and massive stromatolites (shallow) . The concave cross section of pinnacle reefs was 'attributed to differential solution during, compaction . The discussion : by Wilson was of much interest ; The environments of different carbonate facies were described . The 'topographic outline of a carbonate buildup ( shelf-margin-basin) results from differential carbonate deposition, directly controlled by the degree of organic activity .' As't'he area of optimum carbonate production is the optimum zone of organic development, climactic and tectonic controls were'discussed . Climactic environments and accompanying , .,sediments are summarized in the accompanying paper . Four tectonic 'environments'of carbonate production were described : large off- shore platforms ( the Bahamas) ; margins of'tectonic blocks (,the Delaware Basin) ; flat, gentle, positive areas .( San Marcos) ; and margins of intracratonic,basins ( the Williston Basin) . in the discussion "Roots of Carbonate Platforms and Reefs", 'geophysical maps ( residual gravity anomaly maps and corroborative ' .evidence from seismic and other data) were shown to' outline carbonate . .platform topography, Negative anomalies indicate basins, and-positive . anomalies indicate platforms . Anomalies were interpreted as .resulting from density contrasts below the basin floors, and indicate that , ;'.platform-basin topography is structurally initiatled and controlled . ~, Ex mples used' were the . Bahamas( initial form controlled by folding ,or faulting in the underlying Cretaceous) and the Texas Central Basin '( primary control by,a .horst block) . Reference'was also made to the Canadian reefs . Amount of structural control varies greatly . Some exceptions to the successful application of anomaly maps were pointed out, a notable example being the Tampico Embayment . In summary, th,e?discu`s,sions were excellent . 'Unfortunately., abstracts of only two of.'the.talks were distributed, and I did not recognize some of 'the references .'If brief,-'abstracts were made,, available prior' to . the' discussions, a better understanding would result, . Adrian. V . Greene i THE COMPARATIVE SEDIMENTOLOGY OF CARBONATES j Opening Conference of The Comparative Sedimentology Laboratory, Fisher Island University of Miami Rosenstiel School of Marine and Atmospheric Science Auditorium, '10 Rick enbacker Causeway Friday, January 28, 9 :00 .--12 :30 Introduction : ROBERT N .,GINSBURG PAUL HOFFMAN The Earliest Carbonate Platforms': Geological Survey ofjCanada Northwest Territories, Canada EUGENE SHINN Comparison of Tidal Flat Deposits from Shell Oil Company,-Houston the Bahamas.'and Persian Gulf . 2 :00 - 5 :30 Chairman : R. MICHAEL. LLOYD EDWARD PURDY The British Honduras Model of'Carbonate Esso International, England Deposition BRUCE PURSER Sedimentation and Diagenesis of Paris University of Paris Basin Carbonates . Saturday, January 29, 9 :00 - 12':30 Chairman : PERRY ROEHL PAUL ENOS, State University of Reefs ., Platforms and Basins of the New York, Binghanton' . Mexican Cretaceous ' / ALFONSO'BOSELLINI, Evolution of Triassic and Jurassic Universita di Ferrara, Italy,- Platforms in Italy ~ . '2 :00 - 5 :30 ~ . Chairman : LLOYD PRAY HEINRICH ZANKL Comparative Studies of Alpine Triassic University of Marburg, Germany and Holocene . Reefs EDWARD KLOVAN The Anatomy and Evolution of :Western University of Calgary, Canada Canadian-Devonian Reefs 'Sunday, January 30, 9 ;00 - .12 :30 Chairman : To be Announced JAMES LEE WILSON Scale and'Facies of Carbonate PZatforms Rice University,,Houston' and Reef,"Complexes MAHLON BALL The Roots of : Carbonate Platforms and University of'Miami' .. Reefs Fig . 1 - Location Nap of the Dolomites and of the most important "reefs'! . 1 °' Fig . 2 - Regional `geological setting of the Dolomites . 1 . Alluvial plain ; 2 . Tertiary and Jurassic ; 3 . Triassic (with the "reefs") ; 4 Permian ignimbrit.es ; 5 . Metamorphic basement ; 6 . 'Intrusions ; 7 . Major . faults ; 8 . Tectonic boundary of the Southern Alps . , JURASSIC IASSIC GREY LM - . . . i . ' . TRI S INA ' -/ RHAETI • 4 NORIAN OOLOMIA T i-~- PRINC:IPALE R 0^' RAIHL FM • A CARNIAN FCR THE STRATIGRAPHY ' S OF THIS INTERVAL " S SEE FIG.4 • . .. . / LADINIAN C ANISIAN SERLA DOLOMITE . . . ".. •' - : . ::. . .rf r-- .. DADOCRINUS - ' SCITIAN a WERFEN FM - UPPER BED F'HDN Fail ' PERMIAN a MIDDLE GARDENA SANDSTONE PALEOZOIC ! BASEMENT Fig . 3 - The stratigraphic column of the Dolomites . '.je : ~}I r si°~ .zrLOMIA P&II nIPA E t_JJ +i . .i1 .~ NORIAN RAIBL FM T 20-100 m ~U U CARNIAN m R ~, SCILIAF ,'r NJ~e w>K • l1 DOLOMITE r~ f 500-1000 m ~y N r~~ f ( xv f ` f u '•t"~~) HR t"~ x Sz~ § d LAOINIAN LIVlNALLONGO Ftd m C s~nh !iwLdat7 S a ^ t w33G~: rf l..at•'- nc>i:.-.a SFRLA ¢ OLOM I7 E ANISIAN r6tmsv~l'mt., w-*~~~ v.Y'.'~i'ravn arms.- . . ~ ~ ~ P,o jcat wp o f ~ ~ l TRlASSIC I NORTHERN LIMESTONE ALPS II SOUTHERM LIMESTONF ALPS Rhaef on ; MCI d ion 6eds < Wetkers e r Ro sdu en marls \',esIone'doJor,le- lrvi - - Bccsehe nS ;cs;I ~71 Anisian ic~1%0/1??? on / '/x era le -~Jeje : laa' III'I ;.i, ' loll P pv ' ~. :,,,. f I11 1 I Al J~P~p yv~ e G 0 c c~RC~E LEGEND I I I I I I I I I I I INTERIOR SHELF LOWS SLAVI 11111111111 INTERIOR SHELF HIGHS MACKENZIE - ROCKY MNT. 1 North LX~ MIOGEOSYNCLINE A v rerr,for@S ® CORDILLERAN TROUGH WESTERN CARBONATE ~-~ PLATFORM TATHLI rn ~I DAVE LORD HIGHLANDS MEADOW LAKE ESCARP- MENT: NORTHWEST EDGE D OF PRAIRIE PLATEAU SSo 0. ~ e HAY RIVER SAS _CU Co~U~b/a Z B PEACE RIVER - A ASCA 4 ARCH/. M~gKMq Saskatchewan P Manitoba I'h~ ila ~ I IA I I N C O a g . 114 SCALE : .; eg 100 50 0 100 200 II MILES 100 0 100 300 0WIHNIPEO KILOMETERS ABSTRACT Nine depositional facies are described in ide alized sequence across a typical carbonate shelf margin . These facies are : basinal, tidal shelf, basin margin, platform foresiope , organic reef , platform edge sands , open marine platform, restricted marine platform and platform evaporite facies . Each of these is characterized by sedimeniologicai parameters , prevailing rock types, color , microfacies, sedimentary structure , terrigenous content, and characteristic biota .' Description of this very widespread sequence should aid in location of reservoir rock . This paper outlines an idealized schema of carbonate dependent on'the amount of influx of fine argillaceous and environments following a pattern developed so widely in siliceous-material and the rain of decaying plankton. These the geologic record that it deserves to be generalized and contributions may be slight for in a typical carbonate thoroughly documented. The associated table (Figure 1) is producing shelf, little such material crosses the surrounding from work begun by the writer when with Shell shelves . A starved, rather deep-water, basin commonly Development Company in 1965 . Its essential outline was results . In some cases, such basins are filled with_evaporites published as a discussion with W. Tyrrell in SEPM Spec. or, elastics .- These may be deposited during lower sea level Pub. 14 (1969, p . 18) and in much more detailed form stands reciprocally with upbuilding of surrounding shelves, applied to Devonian carbonate complexes by 3. Dooge or even much later after complete formation of the (1966, see particularly appendices 6 and 7) . Some of the carbonate platforms. ' general principles responsible 'for, and illustrations, of, this common sequence of carbonate facies have been previously published by Irwin ( 1965 ), Shaw (1964 ), and in various a. Prevailing rock types : Dark shale or silt,, with thin papers by the following authors in , SEPM Spec . Pub. 14 limestones, some thin, bedded anhydrite . Thick (1969): Tyrrell, Thomson and Thomasson , McDaniel and salt deposits in certain instances . " . Pray, Laporte, and Griffith, Pitcher and Rice . b.' Colors : Dark brown or black (up to several The development of this prevailing sequence of facies percent, bituminous organic matter). along any carbonate shelf margin is a natural consequence + . .of some of the principles behind carbonate sedimentation . C. Grain types and depositional texture : Lime Carbonates are essentially of organic origin . Because of this, mudstones and calcisiltites , micropelletoids, carbonate sediment will form well only 'in warm , clear, microbioclastics. sunlit water free of clayey contamination . Such areas are apt to be somewhat removed from land and to lie down d . Bedding and sedimentary structures: Very even gentle paleoslopes paralleling ancient coast lines . Because planar thin lamination , ripple cross-lamination, the biota demands sunlight to flourish , its maximum small scale rhythmic bedding consisting . of even productivity occurs only in relatively shallow water . beds of limestone intercalated with thin shales. Consequently , the mass of organic carbonate grows most rapidly on the upper part of any gentle seaward slope some e. Terrigenous elastics: Somewhat admixed with distance . from land but not in deep water . Continued carbonates and also interbedded in thin layers . inundation of a positive block with stable or rising sea level Quartz silt and shale. Material windblown as well results in rapid organic growth and sediment accumulation as water-carried . Chert very common, probably along the initial growth centers and the formation of a line derived both from opaline organisms ', and from - ; of shelf margin organic buildups , the gradual filling-in of solution and replacement__of __ quartz_silt . by the lagoon between the shelf margin and land, and carbonate. eventually the construction of a ramp or platform surrounding the positive element . Not much sediment f. Biota : Exclusively nektonic-pelagic accumulates simultaneously in the area downslope from the fauna preser ved in local abundance - on bedding planes .. / shelf margin because, as the buildup occurs, the water A t s , . becomes too deep Micro fauna thoroughly admixed ' with fine' ~h,z4 . The normal result 'is a starved basin surrounded by carbon ate ramps or pla sediment . Megafauna includes graptolites , tforms built out•from planktonic bivalves } '}•-" ti •~ the positive elements rimming the original depression . ammonites,' and sponge spicules . Microfauna includes calcareous 1 . Basin facies (starved or filled) (_Fond calpionellids, tintinnids , and calcispheres, and o_t1_tem_J siliceous radiolarians and diatoms . Euxinic conditions may develope below oxygenation level and below wave base. Water is from I00_to several hundred ., ,~ - ,6 t ' F v s feet deep . Bottom water flowing off of surrounding shelves 2. Tidal shelf facies (deep Undathem)._Water tensor -- may become hypersaline and ' dense, preventing easy even a few hundred feet deep , generally oxygenated and .of ' turnover . This situation , and lack of oxidation of the rain normal marine salinity, Good current circulation . Deep of organic plankton, increases the tendency toward enough to be below normal wave base but intermittent stagnant reducing environment ., Few burrowers can exist storms effect bottom sediments . Such shelves are generally here and fine laminated sediment results . Deposition is wide and-sedimentation is quite uniform . This is the typical '} 229 . . 230 TRANSACTIONS - GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XX, 1970 + realm of deeper neritic sedimentation and may consist of f.' Terrigenous elastics : Rarely present except as fine carbonate-or shale . shale partings . Chert is common . a. Prevailing rock types : Very fossiliferous limestone , g. Biota : Bioclastic detritus- derived- principallyirom interbedded with marls . Well segregated beds. upslope. Fauna is open shelf and normal marine ' types but may be a mixture of_reworked_fosms- b. Colors : Gray, green, red, and brown 'due to derived from shelf, benthonic organisms living on variable oxidizing and reducing conditions . slope, and some pelagic forms . c. Grain types and depositional texture : Bioclastic' 4. Foreslope fecies of carbonate' platform (marine and whole fossil wackestone . Some calcisiltites. talus) (Clinothem). Generally, the slope is located above the Much pelleting of micrite matrix . lower limit of oxygenated water and extends from above to below wave base . Composed of debris deposited on an d1 Bedding and sedimentary structures: Sediment incline formed seaward as the ramp grows ._Incline may be thoroughly burrowed, beds homogenized . Thin to as steep as 30°~ Sediment is somewhat unstable and varies medium, wavy to nodular. beds . Ball_ and flow greatly in size and shape . There may be bedded, . (sh ale/carbonate compaction structure) prominent fine-grained layers with megaslumps, foreset bedded and in argillaceous limestones . Bedding surfaces show wedge-shaped beds consisting principally of lime sand, and diastems, lag concentrates of fossils. mound or lens-shaped masses of trapped and stabilized fine grained carbonate sediment. e.• Terrigenous elastics : Quartz silt, siltstone, and shale commonly interbedded with limestones in a. Prevailing rock types : Limestone, the type clearly segregated layers . . depending on water energy upslope ; lime muds and sands, boundstone, and sedimentary breccia . , . f B'to a . tery Vrverse d' s eh y llauna ltlf Icad' mg t' nortna 1 marine salinity ; preservation of- both infauna and b. Color : Dark to light . epifauna . Fauna locally less common, but generally present. Notable presence of brachiopods, corals, c. Grain types and depositional texture : Lime silts cephalopods, echinoderms (stenohaline forms) and bioclastic wackestone-packstone. Lithoclasts along with all other organisms . of varying shapes and sizes derived from cemented i strata upslope . Much reworked material with ' locally derived organic debris . 3. Basin margin or deep shelf margin facies lin~t_Ia in). Formed at toe of slope of carbonate d. Bedding and sedimentary structures : Megaslumps producing shelf. Water of about same depth as preceding in thinly bedded strata ; large scale foreset bedding two facies . Situated at or below wave base and oxygen (wedges) ; large exotic blocks interrupting bedding ;. level . Sediments composed of carbonate and siliceous slope mounds of fine-grained sediment ; syngenetic ': ;: a.terial derived from nearby shelf, the argillaceous matter slumps, pull-aparts, and breccias ; clastic injection having drifted or blown farther out into basin . A dykes and fissure fillings, resemble basinal sediments but are non-argillaceous and somewhat th icker . e. Terrigenous elastics : Mostly pure carbonate but some shale, silt, and fine quartz sand drift a. Prevailing rock type : Fine grained limestone, in downslope from above and admix with carbonate some places cherty . or fill cavities . b. Color : Ranging from dark to light . f. Biota : Mostly bioclastic debris from upslope but .1 also colonies of in-place encrusting organisms . May c. Grain types and depositional texture : Mostly lime be very fossiliferous . Fauna varied, open marine mudstone .___with __s .o_me calcisiltite . Some msroblxccia beds. 5 . Organic reef of platform margin : Ecologic character dependent on water- energy and steepness of , .. d. Some beds are laminated with micrograding of .slope, organic pro ductivity, amount of frame construction, lithoclastic and bioclastic debris from upslope . binding or trapping, frequency_of _subaeriaLexposure .and .: Locales exotic bl ocks. conse uq ent cementation . Three types of linear shelf-margin organic buildups may be discerned : (1) Downslope mud . , : e. Bedding and sedimentary structures: Some beds and organic detritus accumulations (2) low energy organic . are laminated lime mudstones, other framebuilding_,reefs _with ._isolated clumps or encrusting- thicker-bedded units are of massive unlaminated sheets of organisms growing up to wave base and stabilizing lime mudstone . In other beds, lithoclastic and debris accumulations . (These exist in water a few tens of bioclastic fragments derived from upslope, show feet deep .) (3) frame constructing_ reefs like modern micrograding. Locally, exo_tic_blocks . Megaslu_m_p ' coral-algal assemblages with sessile forms growing up features-within evenly bedded limestone cause through wave base into the surf zone . Such fringes of major discontinuiti es in b edding . Mud bioherms in organic growth at shelf margins may alternate with banks . , some places. and shoals of winnowed sands (Facies 6) . ' WILSON : DEPOSITIONAL FACIES ACROSS CARBONATE SHELF MARGINS 231 l a. Prevailing rock type : Massive limestone and Eolianites have old soil horizons and root casts f: dolomite in places consisting solely of organi c preserved . skeletons . e. Terrigenous clastics : Quartz sand may be present l b. Color: Light. ~ .' with the calcarenites . "~ c. Grain types and depositional . texture : Masses and f. Biota: Worn and abraided coquinas of benthonic patches of organic boundstone . Interstices may be animals living on reef and foreslope are common . filled with lime mudstone in downslope reefs and Few indigenous organisms because of shifting with grainstone and packstone in upslope substrate. Large bivalves • (megalodonts) or accumulations. Some mounds formed by clumps gastropods are common as are fragmented remains of organisms growing in upslope position have of large dasycladacean algae and certain solely mud matrix . owing to protection from foraminifera. winnowing by reef frame . Interstices in boundstone of higher energy reefs are filled only 7 . Open marine platform facies' (Shallow with lime sand and gravel . Intermound areas UndathemJ• Geographically such environments are located consist commonly of grainstone and packstone . in straits, open lagoons and bays behind the outer platform edge . Water depth shallow , generally a few tens of_ feet_ d. Bedding and sedimentary structures deep. Salinity varies from essentially normal marine to : Massive hypersaline organic framework with constructed (roofed ) ; circulation is very moderate . Water conditions cavities. Lamination ' caused by are favorable for organisms but often the stenohaline forms organic growth are excluded. The s swells and thickens upward, In mounds with 7 ediments are texturally varied but contain considerable amounts of lime mud . considerable lime-mud matrix, stromatactis-like" structure is common: .,Brecciation and fissuring of a. .Prevailing rock types : Various limestones and, in massive ' buildups _.comm on, injection dy kes . present . some places, land -derived clastics. , b. Color : Light and dark . e. Terrigenous clastics : Essentially absent . C. Grain types and depositional texture : Great 1 f. Biota : Colonies of sessile framebuilding organisms variety of textures, grainstone to mudstone, e.g., may. or may not dominate . Growth form lime-sand bodies , beds of bioclastic wackestones, determined clearly by water energy. Forms may mounds and lenses of organically produced also be low-lying and encrusting . Ramose or sediment, and areas of clastics . dendritic forms exist in more protected places . Communities of abundant accessory organisms d.; Bedding and sedimentary structures : Medium to dwelling in various ecologic niches may form beds platy bedded ; burrowing and pelleting of sediment (e.g. - layers of brachiopods , molluscs, or ' common. When clay is admixed, ball and flow crinoids).. compaction structures are present , as well as nodular and wavy bedding. 6. Winnowed platform edge sands : These take the form of shoal , beaches, off-shore or tidal_bars . in fans or e. Terrig enous elastics : When present, generally in belts, or eolianite dune islands . Depths of such marginal well-segregated beds intercalated with limestones. sands range from sea level to 20 or 30 feet . Much clean sand is winnowed by the waves and deposited by waves, or by f.' Biota: Fauna may be abundant . Mollusks , tidal or longshore currents of 1 to 2 knots . The salinity is sponges, arthropods, foraminifera , and algae commonly normal marine because of good circulation . The .particularly common . Patch' reefs are present . environment is well oxygenated but not hospitable to Abundant marine grasses and trees play important marine life because of the shifting substrate.. role in trapping and stabilizing fine sediment in shallow water. Organisms requiring normal marine a. Prevailing rock type : Cross-bedded calcareous or salinity 'are rare , e.g brachiopods , dolomitic lime sand , cephalopods, . ./- o echinoderms . / ~d,=i~ a yn e, a l J_ z ^ 1,,, b. Color : Light. „ , 8 . Facies of restricted circulation on marine ~` l c platform: Includes mostly fine sediment in very shallow, c. Grain types and depositional texture : Rounded ~' cut-off ponds and lagoons, coarser sediment in tidal channel and fairly well-sorted grainstones . Some are_coated and local beaches, and the whole complex of .tidal flat and oolitic . Others are merely..rounded bioclasts . / environment . The environment is extremely variable and is a stress environment for organisms . It includes fresh , salt, d. Bedding and sedimentary structures : Marine sands and even hyperslaine water, areas of subaerial exposure, with medium-to small-scale festoon cross -bedding . both reducing and oxydizing conditions, and both marine Eolianites have large scale cross-bedding . Surfaces and fresh -water swamp vegetation . Windblown elastics may representing stratigraph c -ktiatuses_aro commonsn- contribute significantly in some places . Diagenetic effects both. marine and ._,non, -marine environments . are strongly marked in the resulting sediment 232 TRANSACTIONS - GULF COAST ASSOCIATION OF GEOLOGICAL SOCIETIES Volume XX 1970 a. Prevailing rock types : Generally-.- lime-muddy blue-green algal stromatolites, brine shrimp . sediment with much dolomite. REFERENCES b. Color: Light . Dooge, J. (1966) c . The Stratigraphy of an Upper Devonian' . Grain type and depositional texture : Highly Carbonate-Shale transition between the North and . varied, most sediments including lime- mud ; South Ram Rivers of the Canadian Rocky Mountains . grainstone rare except for thoroughly pelleted Ph.D. thesis, Leiden University . J. J. Groen en Zoon, sediment. Channels contain lithoclastic grainy Leiden, Nederlands. 53 p . sediment; 'clotted, pelleted mudstones and Irwin, M . L., (1965) . General Theory of Epeiric Clear Water - wackestones most common . Sedimentation . Amer. Assoc. Petroleum Geologists Bull . v. 49, p. 445-459 . d. Bedding and sedimentary structures : Much Shaw, A. D. (1964) . Time in Stratigraphy. McGraw-Hill, laminated mudstone, fenestral (birdseye) fabric, New York, 365 p . algal stromatolite, small-scale graded bedding, Soc. Econ. Paleontologists & Mineralogists (1969) dolomite and caliche crusts, channel sands show Depositional Environments in Carbonate R cross-bedding. ocks. ` Spec. Publ. 14, G. M. Friedman, Editor, 209 p. e. Terrigenous clastics : Rare except for windblown material; where present, usually in well-segregated layers . f. Biota : Very limited fauna and flora, mainly gastropods, algae, foraminifera (miliolids), and ostracods . These organisms may occur locally in great abundance. 9. Platform evaporite facies: The supratidal and inland pond environment of the restricted marine platform developed in an evaporative climate-----the areas_of .sebka, saunas, salt flats . Intense heat and aridity common, at least ; seasonally'. Marine flooding sporadic. Gypsum or anhydrite r formed from evaporating sea water in the sediments is-both . depositional and diagenetic. Dense "evaporative brines 'efluxing - through the _ sediment and-.,capillary pull of -.;evaporating interstitial waters to the surface are important rocesses. a. Prevailing rock types : Nodular and wavy anhydrite, or gypsum interlaminated with dolomite. Such rock types commonly are associated with redbeds. b. Color: Highly variable, red, yellow, brown. c. Grain type and depositional texture : Very fine grain carbonate sediment ; , gypsum /anhydrite crystals often form a felted mat of tiny lath-shaped crystals or, when secondary, are large bladed and poikilotopic. d., Bedding and sedimentary structures : Laminate, both wispy and planar types, mud cracks, stromatolite and spongiostrome structure, gypsum rosettes and selenite blades (pseudomorphed by anhydrite), and syngenetic, diagenetic and ' deformational structures such as nodular and chicken-wire (flaser) structure, ptygmatic (contorted) folding . Also diastem surfaces, caliche crusts are common. e. Terrigenous clastics : May be very 'common, redbeds and windblown sediment ., f. Biota : Almost no indigenous fauna except for fkctMA ( x10 vertlcel ue99 bae `Diagrammati c Cross Section -s+lln/tr I~r . eee-e- w - sm.. ~¢.e ba< ~~~ 0 775 Ppn t ]4$ PM E,^ yo . . .- PyJS'~ z OxY9 THIN L[11E YE E~W„ LINiSTME STONE . CNE0.iY 'ABLE- EFEM'N'. St GL1A TVlTl C-OOLI TIC LIKE VARIABLE G0.0GNiE5 ASS GENERALLY DOLE[ TE AN0 STMES L (STARYEOT Lt5 1N), IXTERBEODED FINE Y EI ENLY UPSLOPE " 01NExiAAY MASSIVE LIXESTOHE-OOLCMITC. IAOUt0. fITEYAxD AxNtDRI TE, L it tIOIO gY SO4E X GSES SAND OR COLGHITE . ELASTICS. TIC LIH[STC::E. Y O SCAR 1 ED BEGS EVAPURITE FILL WITH SALT . WELL SEGREGATED BEDS. MRECCIAS AND LINE SAXES, . . . DARK TO LICHT . BOA. YTLLN, 99W . DARK BROWN . BUCK . - CRAY, GREEK. RED, BRDUN . SARK TO LIGHT LIGHT LICIT . LIGHT. Color DARK TO LIGHT . . CLOTTED, PELLETEO IVOSTONC a pIO AST A LINE SILTS S10CIASOOIC YACKE- CE IC ND WHOLE FOSSIL xOSTIY LIKE N DSTME WITH IPHROSi0NEf AM POCKETS OF b . Organisms: dominant P*.sf.Edte --K5f6 Jour . Vol . 5, p. 149 tidale Forosi ty Mississipiian So . Saskatchewan . .w.3.-ales- F. 227 - Upper Lodgepole - Upper F.iesion Canyon _ REFERENCE FORMATIONS ------AGE LOCATIONS Lk . shaly - siliceous . dense Dark gray limestone . Cream-white chalky limestone Cream white fossil fraenen- Cream-white foram - Light tuff pisol itic . Lt . buff ephanitic and Cream white chalky lime- lisestora, u/eray-brown chert . ^,ray calcareous shale _ tal limestone in banks . ooiitic - Felletoyd lime- oolitie , Felietoic'. microgranular limestone . stone . Earthy dolc.Nte . Thin bedded . Shale partings . partings . - - - atone . - 7ntraformational conglome - - : Dark gray dense li mestone, p rate . Scattered oolitic pellet . _ associated bedded arhydrite 0 -5-10 wile band silt bands . - - Side spread silt bands . vido spread silt bands pare limestone . - - 41 si lica , clay . Fe . .F.g . - 5-10 site band m - . !tide spread - silt bands - - Calcarenitee - politic, Non skeletal calcar . 694 Hierite ticrite - - Ficrite , Bioclastic Cslcisiltite , Merit* • - Bioclastic calcarenltea skeletal v/oolitie coat - 0oli hi c-pisoli tic ILL Very fine grained dolomite 3 ealcisiltite - epleular fi.crite - Bioelastie - eparite, - - - : - Slightly politic ing. - - Non skeletal cnlcisflt 9 - - primary anhydri to . _ - Chalk beds known locally . Pelletoi4 Skeletal debris 6 _ Lima cud 2 - - - - p FSiorito a sparite - 'n . Eierite h aparite _ n y Crinoid ifS Crinoid pieces Algal lie.estone Algae _ Ostracodes sponges - spicules Crinoid pieces Scattered erinoid pieces Bryosoans Endothyroid for." . 4astropods _ . Scattered erinoid pieces Brachiopods (whole, in situ) Dryozoa Brachlopods Other small !prams Calcisiheres " _ - Zophrentld corals Ortonella - ( Codiacea )ball m Catracodes Q Fow bryczoans . alternatin facies adosmone A FW hundred - _ _ . _ - - r p11 p ~. o F3 a r m O - 3 - ft . at coat ' ~ ~r.~ r O p^~ O .~ p n o'' o O n - - r r n^ n w n 'L n z f , ~ ~ r n n ~ ~f n " -~ -r r . Z '~" -~ ~- --- Bioaastic 0olltic fine grained cicrite ' Bedded anhydrlta A sprite sprit.- polletold polsparite-aJcrite ' Basin dark ahalp lip.entone I Dark Nicrite - Limestone Bibelastie lt . colored cderite I I- m ~ - { Wide distribution - up to' several FacSes hundred - e11as ~ belts_.--- - 10-20 miles ~ ~ aide distribution ) - .-ab Shoal Banks - BarrierB Banks Central Shoala InWrshoal Lagoon O - f:entral Basin Basin Edge Interahoe Upon Y rins .. Shoal - open aurin ^ edge 4goonal Edge '. z Shelf THE PERMIAN REEF COMPLEX From the original interpretation of Newell modified by Dunham & Achauer fev11 . N . et al . OFler 0.0 .1.74- - Ftlddle Focal- C-d"N Iar.a . Feralan Aeef Corp: .ex . - Lvv.r nenbar er 0.11 Cenyon - Cepllen Ll-tone --- Carisbsd 13-t- - - T .- L gev ?.4e . REFERENCE FORMATIONS AGE LOCATICIS Gr :y lardnated earv4 tm. _ cork colored . bitvnlnoue . Dark colarod, thin toni$0. _ Pink . c se blocks of Foot wall Back Prof Calcorenite - 11-111 . (1 rd la x . Fine grained dolerdte . Eraporites 4 rta oae as rdatcoo - bran atltatnto and blonY. shn17 uasy betded . 1aminated, un- Bind atin - ealearenlla - asssire -or talua. 1SEht gray, aphenltie, Coquina . Delooltlred . Pelletoida (band - thin bed Unfit colored . Thin even Gypsum hoa aphydrite - " foot . Act aa: .iy shale. geodotona . - - - fosa111.- 111r Coqu110 . Wavy bedding . - None dolnoitlzed - 4-25: . natratlfied . pure 11-- _ (lagoon' ",do to navy . - - - 1,io r atratifleatlon. o Doltrd.te 1-2f .- Cut and f111 fn- ogs . 5tr titi d rwaalva bed . at. .. . bMUmerable nog .. Think bode - 201 paodmun,- Flea lenses behind reef. (1/2 - 1 It) Very P- Nc rl FFle narks or Orading to eetabentonl to d 01ant ereaa-boddleg.-boddleg. 20 - )5 . Interledded 00th ealearenl to carbonate - 995 . 50-50 - - reaa bonding . - Pare with fine grained del. Yg - Ca . __ ' e- chem . Sbaartne fluid slides . iredinq to!-y 0,000 of fine Aroined qtr . as - No b oot)a . Fa+ Inch,- thick unit thin, ' ' Rsx 200' to 201 in 14 miles - - - 1(2 S1a b001n increase 0-6'S 1 '11 . hard -1- 1/2 ~ - - - -- ~7 n11v from roof. Wide dietrlbation 6-9 n11en (01000.1 to roar) 4'Sda _ DSOtrlbutlon 35 r11ee - bee than 1 mile . Leas then 1 mile . - ..ngnlcr gr'Sno T` Wdnate - 3 r, to ,1 Separated - ported fosell bonneted rock & sMll fgsnle tph ..nltle 1lacstene . A btospartte1 botrix 30-50 lt twin of dolcnite - It- knhede . of dolomite, 100. - - - -uaru"a ylar -ova a 20sort- - to oiorono. Dark s111ceoua sponge api- remains . Textural gradlnnt [avid,, filled v/qtl a . - 1 Lien .d our rounding microns . Anhedral . sons rypsum. 10-1000 n1- 400 nierona . Yutuel 57$ . Wall de.elopod due to e .lcite eules . Algal spheres In dk . Neullnea axin par . ripple lion mud, ea1esroMte .nd ~ Snnum~rahlo1. 0000 . Filled Patrix 53'f erona -eovra ar than in nale . baundarloo 1ng - airing . eat arcl orpontd ratlvr arEnnio layers vl th noro mocks . $lvmp taide . YScr1 La nnoont... - Dy layer, of P09000, eel- Fessll hash 20 ,',.pawl to Scattered very flty grain, eeweentratien. - calcite : Lt . layers of del. nstris, .1 .e ep .r1to. . 011 etajr cite A qtr . a Poln!Sexodina (coqulnn)13 Pelsparit. Poic.lete eau t A and ad . groin, . No graded - Ie eph,rdtic ltr7ntano Ltth0eieet 7 Cntritel qtz b calcite grna . - - - Algae 2 beddlrc. Silicified tosnlla con*on- rcoyatn111red a1Ea1 line- .5 n - Tine ea lcarenlto . -- atone or lime and coarser Foroas 2.5 ' rcxyatalliredl Quartz 1 ^' - N Aad101orlans Brxchlopode, Crinolde, Fodunculete brachiopod, Sn BStu - hydrecorallinos . Daxyclads - very abuMant Algal pl eoll thn Fan transported frrmta . Cedlsecons - abu dent $teules Dryoxoan, N-11 . -not Bryazoane (Crypt-t- .) Algnl eruste - etrr-to- Other fossil, wry ram No algal etr- atoll to Meal spharoa - calcite farther than 10-15 adlee wt Crlnoide lit% (rocryatalllzatton!) Falydf exadl rti baonltes Armcni tea - untraneportad Fusulinra A1gee Onotfi pods - in it, p Nvcvlcld =alecypnd } faro vlth v]de tIn.e range - Solvnoeo a (4¢d) - - Nigh rptred gaatrcpod) filled 00th .1"11 dabrl,, OSrvnnella-Ortonella Peiecypcdns L010rt 000hue Co+xwn Dazycladocenns - Diolo - Algol spheres -i paws , yl>.z1a lLouline. .bvndent - vorn - - Spoon spoor., . Favna lorgaly rnocthon"a - - Bryoaoan _ F1 at 0 .p-id . 1 17~ rt . r W-, e . . Slap • Base .~ - - Aim! Front - Beef TLt Aentrleted Fane I -r.-n L.C... Noarabore Store y Basin Supple+- nF natrrinl fl-t- Sto,T lope . fauna Stoop slope . V.- lived In tt grevth . Pert ohal- Turbulent voter . Aighor Solrmitfrnd araronl to a ..do Deeper lkgoen+l voter .ate Organic content ro- hind sborn . nobly.M.. p thanhnter . ebint root nofwa1 .,unity . 'hall- - - - ets to 1A plankton prodot- hivhicn c -art t & t bind r.of tlvlty . Deep voter. Source - orplS asu . of .ard craw roafi y4 r AMERICAN SMELTING AND REFINING COMPANY 2640 Broadway, N .E . Knoxville, Tennessee 37917 ,' February 8, 1972 MEMORANDUM TO MR . J . `V . -'DESVAUX : The following comments and summaries pertain to the "Comparative Sedimentology of Carbonates" conference I attended on January 28-30, 1972 . A schedule of the conference is attached . The conference was well organized and all papers well presented . The theme of most speakers was to . relate older rock carbonate lithofacies and their particular set of sedimentary`` features to active carbonate depositional areas such as the ,.,Bahamas, Persian Gialf, and Shark Bay, Australia . Carbonate platforms containing sharp facies'changes,at platform margins were the models in all cases . The degree of refinement of interpretative methods was impressive and at times overwhelming . Convincing photo and descriptive documentation was, presented by all speakers . The relationship of carbonate facies to'stratabound . sulfide deposits in carbonate rocks was brought to mind when considering the SE Missouri Lead District and the Pine Point District (NW Territories) . Both of these districts are located at platform margins', with mineralization seemingly controlled by sharp facies changes . Sulfide deposits in Lower and Middle Ordovician carbonates' (Tennessee Zinc Districts and Upper Mis-' sissippi Valley District) do not occur in a platform edge con - dition . The following comments pertain to the first five paper's on the schedule -- .Mr . Greene is commenting on the second five in a separate memorandum . (l) Paul Hoffman "The Earliest Carbonate Platforms : Northwest :' ., Territories, Canada" An abstract of Hoffman's paper is attached . His, interpretation of the carbonate platform and associated facies' changes was well documented by lithologic description and photos . A photo comparison of Precambrian stromatolites to living algal structures in Sharks Bay','Australia was especially striking . The economic value of Hoffman's paper is to realize ihat .the platform margins' are areas which are favorable for stratabound sulfide occurrence . Breccia and coarse grained epigenetic dolomite are noted to occur along the platform margins -- both are favorable host environments for sulfide deposition . ' ." :Further economic considerations involve the aulacogens (see attached map) which are in effect graywacke arms extending into . .",,.'the carbonate platforms . It might be suspected that the graywackes . ,could have served as conduits for solutions to move to a position of sharp lateral contact with platform carbonates which would be a condition favorable for sulfide emplacement . The recent discovery .".-by Cominco in the Bathurst Inlet Area may be related to the Bathurst Aulacogen ( I am uncertain as to the exact location and host unit) . (2) Eugene Shinn "Comparison of Tidal Flat Deposits from the Bahamas and Persian Gulf" . Shinn sought to point out basic differences in present day carbonate platform environments . Climate conditions as well as structural conditions can vary to cause different sets of carbonate depositional environments . The Bahamas (tropical climate) and Persian Gulf (arid climate) were used as comparative models . . (3) Edward Purdy "The British Honduras Model of Carbonate Deposition" . The main point of the paper was to relate the carbonate platform features to a template developed in underlying rocks by Karst . British Honduras was used as primary field model . . Laboratory models were also presented . Features emphasized are as follows : (1) Edge of a Karst block would normally be a positive rim which would control localization of a subsequent barrier reef . (2) Pin- nacles in well developed Karst would control localization of subsequent pinnacle or patch reefs . (3) Poorly developed Karst surface would form basis for extensive shallow tidal flat behind barrier reef .", The British Honduras'model shows strong Karst (ie patch reefs, . deep water behind reefs, etc .)in southern shelf lagoon as opposed to poorly developed Karst (shallow water, flat lagoonal area) in 'Northern Lagoonal Area . The degree of Karst development is related to climatic conditions (arid vs tropical) plus bedrock' type in water shed area (carbonates vs igneous and metamorphics) . (4) Bruce Purser "Sedimentation and Diagenesis of Paris Basin .', Carbonates" . Descriptive paper on carbonate platforms in Paris Basin Area of France . Comparison to Bahama platform showed definite similarities of carbonate facies -- oolite zone on platform margins with pelletoidal lime mud facies in lagoonal environment . Facies relationships of carbonate rocks shown on attached set of sections reflects geologic history of platform development and environmental ...,,relationships . . (5) Paul Enos "Reefs, Platforms and Basins. of the'Mexican Cretaceous," . -2- Descriptive paper of Middle-Cretaceous Carbonate Platforms in NE Mexico . Lateral relationship of Upper Tamaulipas (Basin`facies), Tamabra (platform margin facies) and El Abra (platform facies) described . Breccia zones common in Tamabra . Petroleum occurrence in platform margin units afforded reason for detailed study of area . Mine workings noted in photos of Tamabra outcrop units (another relationship of reef rock to strata bound sulfides?) . Basinal` units thin in relationship to platform rocks -- typical, of basin units in most areas described . Although not specifically mentioned in this paper, it is noted that quite often platform carbonates are dolomite whereas basinal carbonates are shaly limestone . Platform margin rocks are often porous (epigenetic dolomite) and contain prominent breccia zones as does the Tamabra unit described in Enos' paper . Plan map of carbonate platform and correlation chart' attached . I appreciate''the .opportunity to attend .the conference . In regard to future meetings, conferences, etct it is suggested that some Asarco personnel attend the "Economic Aspects of the Genesis and Diagenesis of Limestones" meeting on August 29 -- abstracts, and schedule attached . ,_~ (; .~~ .~r~scus~ a^rana ~. Delbert D .; Harper DDH :ad Enclosures _3_ L.'T f vl:; THE COMPARATIVE SEDIMENTOLOGY OF CARBONATES Opening Conference of The Comparative Sedimentology Laboratory ; Fisher Island University of Miami Rosenstiel School of Marine and Atmospheric Science Auditorium , 10 Rickenbacker Causeway ,~ Friday, January 28, 9 :00 - 12 :30 Introduction : ROBERT N . .GINSBURG PAUL HOFFMAN The Earliest Carbonate PZatformar Geological Survey of .Canada Northwest Territories ., Canada EUGENE SHINN Comparison of Tidal Flat Deposits from Shell Oil Company, Houston the Bahamas and Persian Gulf . 2 :00 - 5 :30 Chairman : R . MICHAEL LLOYD EDWARD PURDY The British' Honduras Model of Carbonate Esso International , England Deposition BRUCE PURSER Sedimentation and Diagenesia of Paris University of Paris Basin Carbonates Saturday , January 29 , 9 :00 - 12 :30 Chairman : PERRY ROEHL PAUL ENOS, State University of Reefs , Platforms and Basins . of the New York, Binghamton , H Mexican Cretaceous ALFONSO BOSELLINI Evolution of Triassic and Jurassic Universita di Ferrara ,, Italy Platforms in,ItaZy 2 :00 - 5 :30 Chairman : LLOYD PRAY HEINRICH ZANKL Comparative Studies of Alpine Triassic University of Marburg , Germany and. Holocene Reefs EDWARD KLOVAN The Anatomy and Evolution of Western University of Calgary, Canada Canadian Devonian Reefs Sunday , January 30 , 9:00 .- 12 :30 Chairman : -To be- Announced f ` JAMES LEE WILSON Scale and 'acies of Carbonate Platforms Rice University, Houston ., and Reef CompZexes. MAHLON BALL The Roots of- .Carbonate Platforms and University of Miami Reefs THE COMPARATIVE• IMENTOLOGY SED OF CARBONATES January 28-30, 1972 Participating Sponsors : -American Smelting and Refining Company New York. Amoco Production Company Tulsa, Ok Zahoma . "Chevron Oil Field Research Company La Habra, California, Cities Service Oil Company Tulsa, Oklahoma Compagnie Francais des PetroZes New York Conoco Exploration Research" Ponca City, Oklahoma Esso Production Research Company Houston, Texas Gulf Oil Corporation Pittsburgh, Pennsylvania Marathon Oil Company, Denver Research Center LittZeton, Colorado Mobil Field Research Laborator y Dallas, Texas Occidental Petroleum Corporation' BakersfieZd, California SheZZ Development Company" Houston, Texas SheZZ Oil Company Houston, Texas Sun Oil Company Richardson, Texas Union Oil Company Research Center Brea, California 1 t t i THE COMPARATIVE SEDIMENTOLOGY OF CARBONATES LIST OF ATTENDEES AT OPENING CONFERENCE THE COMPARATIVE ' SEDIMENTOLOGY LABORATORY , : FISHER ISLAND January 28-30, 1972 SPEAKERS Mahlon Ball Edward G . Purdy University of Miami Esso Explorations, Inc . Rosenstiel School of Marine and Block 5, The Centre Atmospheric Science Walton-on-Thames , Surrey, England Miami , Florida 33149 Bruce Purser Alfonso Bosellini Laboratoire de Geologie Histori5ue.' Instituto Geologica dell°Universita Faculte des Sciences , Universite de Paris sud di .Ferrara Orsay, France 91 Corso Ercole 1° d'Este , Ferrana, Italy. Eugene Shinn Paul Enos Shell Oil Company Department of Geology One Shell Plaza State University of New York at, Houston , Texas . 77001 Binghamton Binghamton , New York 13901 James Lee Wilson Department of Geology O Paul Hoffman Rice University Department .,of Geological Sciences, Houston , Texas' . 77001 University of California , Santa Barbara Santa Barbara , California 93106 Heinrich Zankl Institut fair Geologie . der Universitat J . E . Klovan Marburg Department of Geology D-355 Marburg t University of Calgary Deutschhaustr . 10 .. f Calgary 44, Alberta, Canada Germany . PARTICIPANTS Joseph E . Banks Philip Braithwaite P . . O Box 297 Sun Oil Company Pinellas .' Park, Florida 33565 . '' P . 0 . Box 2880 Dallas, Texas 75221 Frank Beales Department of Geology Philip W. Choquette University of Toronto Marathon Oil Company Toronto, " Ontario, Canada Denver Research Center Littleton , Colorado 80120 D . G . Bebout Esso Production Research Company Ted D . Cook P . 0'.; : ,Box 2189 Shell Oil Company Houston, Texas 77001 One Shell Plaza , Houston , Texas 77001 . v/ Dexter H . Craig Esther. R .,Jamieson Marathon Oil Company Union Oil, Company of Canada Ltd . . . Denver Research Company P . 0 . Box 999 ' Littleton , Colorado 80120 Calgary 2, Alberta , Canada Graham Davies Robert R . Johannes Institute of Sedimentary and Petrological Department of Zoology Geology, 3304 33rd Street, N .W .' : University-of Georgia Calgary, 44, Alberta , Canada; ' Athens, Georgia 30601 Robert Dill Phillippe Launey NOAA, Bldg . 5 Compagnie Francaise des Petroles :. 'Washington Science Center 4 Rue Michel Ange 161eme Rockville , Maryland 20852 ' Paris, France Robert J, Dunham R . Michael Lloyd ` Shell Development Company Shell Development . Company P . 0. Box 481 P . 0 . Box 481 Houston , Texas 77001 Houston , Texas 77001 William H . Easton Frank Lozo Department of Geology Prestwick Research Center University of Southern California 's 7225 Prestwick Los Angeles , California 90007 Houston, Texas 77001 Melvin H. Fischer Eric W . Mountjoy Occidental Petroleum Corp . ' Dept . of Geological Sciences 5000 Stockdale Highway McGill University Bakersfield , California 93309 Montreal , Canada Vance Greene F . Gray Multer .American Smelting & Refining Company West Indies Laboratory , Fair.leigh. Dickinson West Fork Route University , P . 0 .' Annex Box 4010' .; Bunder, Missouri 63629 Christiansted ,' St . Croix , U . S . Virgin Is . Delbert Harper Henry Nelson American Smelting & Refining Company Mobil Field Research Laboratory ,, 2640 Broadway P . 0 . Box 900 ; Knoxville, Tennessee 37917.. . Dallas , Texas 75221 P . H. Heckel A . R. Palmer Department of Geology Dept . of Earth & Space Sciences University of Iowa State Universitq of New York , Stony Brook Iowa City, Iowa 52240 Stony Brook , New York .11790 John P . Hobson Edward D . Pittman Cities Service Research & Development Amoco Production Company 'Company, Box 50408 Box 591 Tulsa, Oklahoma . 74150 Tulsa , Oklahoma .74104 .R . A. Hoover B . Porthault Esso. Production Research Company .,.0 Societe Nationale de Petroles d'Aquitaine .,. BoxP 2189 . B . Postale 127 Houston, Texas 77001 64 Pau, France Paul Edwin Potter Keene Swett, Department of Geology Department of Geology University of Cincinnati University of Iowa Cincinnati , Ohio 45221 Iowa City ; Iowa 52240 Douglas A . Pounder James B . Taylor Chevron Standard Ltd . Occidental Petroleum Corp . 400 Fifth Avenue S .W . Box 771 Calgary 1, Alberta ,' Canada Port of Spain, Trinidad Lloyd C . Pray Robort T . Terriere :..Dept . of Geology & Geophysics Cities Service Oil Company University of Wisconsin Box 50408 .Madison, Wisconsin 53706 Tulsa , Oklahoma, 74150 Walter C . Pusey Arthur Troell Conoco Exploration Research Amoco Production Company Drawer 1267 Box 591, Ponca City, Oklahoma 74601 Tulsa , Oklahoma 74104 Richard Ray , Roland S . Umiker . !! Earth Sciences Division Sun Oil Company National Science Foundation 805 Eighth Avenue, S .W . Washington , D . C . 20550 Calgary, Alberta, Canada Richard Rezak Roy A. Worrell Dept . of Oceanography Gulf Oil Company '. Texas A & M University Drawer 2100 College Station , . Texas 77843 :'-. Houston , . Texas . ` 77001', Perry 0 . Roehl Union Oil Company .of California P . 0 . Box 76 Brea, California ,, 92621 { s Thomas Schopf Dept . of Geophysical Sciences University of Chicago E Chicago, Illinois 60637 Johannes Schroeder . t `Institut fir Geologie and Paleontologie . Technisches Universitgt Berlin ' D-1 Berlin 12, Germany Robert G . Smalley Chevron Oil Field Research La Habra Laboratory , P . 0 . Box 446 La Habra , California 90631 Grant Steele Gulf Research & Development Co . P :' 0 . Box 36506 Houston, Texas 77036 i • .' THE EARLIEST CARBONATE PLATFORMS, NORTHWEST TERRITORIES, CANADA Paul 'Hoffman, Geological Survey of Canada, Ottawa, Ontario K1A CE8 i Two thick carbonate platforms were deposited between 1750 and ' .2100 million years ago as parts of the Coronation Geosyncline in what is no,..; the northwestern Canadian Shield . 'No skeletal organisms are known to have existed . at that time,•only the procaryotic bacteria and blue-green algae . Nevertheless, the facies differentiation of these ancient platforms is not unlike'that in the Phanerozoic"save for the absence, in addition to skeletal debris, of pelleted'and :burrowed sediments . Platform interior .---Tens to hundreds of stacked shoaling-upward cycles characterize the platform interiors . The individual cycles range from 2 m to 15 m in thickness and can commonly be traced' for tens of km across the platform ,and hundreds of km along its strike . ,,.A representative cycle comprises the following . vertical sequence : Torte Unit 1 : Thin intraclast packstone interpreted as'a beach ' laZ deposited during trangressive phase . Unit 5 Black cher.ty dolomite composed of planar stromatolites with PBmicrodigitate14 fabric containing filament moulds and columnar stromatolites of "Conophyton" type,,inter- preted as .a supratidal stagnant algal marsh deposit .. Unit 4a Light 'grey dolomite with discrete columnar, linked domal and planar stromatolites, .discoidal oncolites and edgewise conglomerate, becoming cherty toward / the top, interpreted as deposited on progradinz idal flats exposed' to wave attack . Unit 3 : Light grey dolomite with rippled ooid-oncoid-intraclast grainstone interpreted as deposited on sure-built sub- tidal shoals . Unit 2 : Reddish-brown to black dolomitic shale with,thin graded and rippled dolosiltite laminae, convolute laminations and syneresis dikes, progressively more dolomit c up- ward, interpreted as deposited on,a sublittoral =^ elf, 'qtr Unit 1 : Thin intraclast packstone interpreted as a beach.la:- deposited during transgressive phase . . Apparent megacycles result from vertical variation, through many cycles, in the proportion of dolomite and shale .. . . Platform margin .-..t the platform margin the cyc'lic' .pattern' breaks doff Con umonly there is a belt, 1-2 km wide, of stromatoli~e mou nd- dnd-channel paleotopographyo The mounds are up to 20 m thick and tens of 'meters•in diameter . They are elongate perpendicular to the platform edge and their tops stood 1-3 m above the floors, of the anastomosing tidal channels between them . . Internally,,the mounds are made-up of ! -large branching columnar .stromatolites up to 1 m in diameter . The . ~.channels are filled by crossbedded intraclast grainstone and infra- . The platform margin commonly suffers epigenetic coarse .'clast-breccia t vuggy d,olomitizationo f Fore'slo•oe of platform .----Foorly defined cycles ; tens of meters'thick, G characterize the foreslope . A representative cycle comprises the E following vertical sequence : # Unit la Black to dark green pyritic shale with small ellipsoidal calcareous concretions . Unit 3 : Light grey. thin evenly bedded lime .mudstone with shale partings, more calcareous and thicker bedded upwards . recumbent slump folds and breccia .beds close to the s platform edge . o Unit 2s Dark green to''brown calcareous shale with digitate • calcareous growth structures possible of cryptalgal origin . Unit 1o Black to dark green pyritic shale with small ellipsoidal calcareous concretions . The cycles are interrupted by wedges of greywacke turbidites, derived F from the other side of-the basin, that wedge out against the fore'slope of the carbonate platform . Undifferentiated platform .---In some places and at some levels, the ,, ;platform margin is poorly differentiated . Basinal shale with calca- reous digitate growth structures (like Unit 2 above) with gre ;rrac ke , turbidite wedges, grade toward the platform into dolomitic mudstone with digitate growth structures of fenestral limestone . This latter facies,, undoubtedly of cryptalgal origin, can form unbroken sequences i hundreds of meters thick . Its depositional environment is uncertain . Conclusions' . Lower Proterozoic carbonate platforms have facies zonations not unlike much younger platforms . They differ in'the overwhelming abundance of stromatolites and other tryptaigal structures . St.romatolites, like many other fossil groups, underwent a gradual . decline, not increase, in importance from an acme very early in their history . s ~WI ,\ 1 I\J lIo N .i it W U P` INI O(CL LOWER R 01c A T a -F--~.~ L I T OL OC VIRONJW EiV T A UGIAT CIE -f _y " I'~ 31L" t tC ) r sU~s J C GEj 8Lf` CK C WE, 1Y t° ~1i1~tI1 s E 1 I- N a ltr 1 MRS SU IP R 1 I D N~ NMI • ~ PS--, 14>'1 ~.e ~ Y r li0 ne~ i~®~t,..L! ~ txJ,`4E.° t Yoe"o' SUBTIML _ SY iE;iG-ISIS C . N C < Vi"t°J1-IQt S1,71` LT l a' aGcc WIN A 8 L!-\cl~ ~~lT£R ~ \L c A F2, D 00 1~MA2 Tfc`. F LA-TV V7 ~ . ~ q,ppyp f yOh V O -O O p=-I= O° V O O O ©O O O H Oi~ ® ~, ; 9 aap ~°''~,~~~~ pqgaga )ig {6 ~ ~_ .©T 0 pa O(i ° 6m+©Q ® p O00 0 O p ® .!Sf - ``,NJ •' ~*ve-3+.-: F_<®-.u. Y_. 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Q g /J r " f' rt •{ . , Plac n 't ~ *4V DaIT!SH HONDUaAS ft Q. •t ~sue" L£0 END ' '.. . - TOPOBBAPHIC CONTOUR CABBOHATE 000AL O e' o O 0 « • HAMPLE LOCALITT cc ~ 4aorVw . . .y',r.r r .e . O 0 A T H 7 A L .A !rm arw' ar sr ram• my 1$° mmv Y .D. / .oc.r rolXr 0 QI Ijl~~~ • LI LO•[Ra ~ is i~BARRIER RIM a .XaeX~X,r /4 .m ur N l Q lS ~ ~ (I : cc mw 1 r l~2' ~ •4t 111 to ; o X • . ~•I O9t;~ 1 a ~ .'ti . . .P• CMAXX[L ^1r ~ 0 "y h : Q ~ ) / ,BRITISH HONDURAS ` HY-DROGRAHIC PROVINCES ' ' i OUTER PLATFORM , . •Ne PORT OF t BARRIER RIM 0000000$ • NORTHERN SHELF LAGOON CNET'U AL BAY ~ . BARRIER PLATFORM SOUTHERN SHELF LA000N G U L F O F :o ...... o.o a.~L ff ) H 0 ND U R A S '; auLFX DF NONDUAAR ~t_ L E G E N 0 TOPOGRAPHIC CONTOUR CARBONATEE SHOAL orwo ww caao - w Z" MB EX CO . Arnbergris Cad t r ' c' ~urnff0 r ~l Islands Q .h y. t r Lighthouse Roof ~~ . Glovers Reef ,100 vathomo ' `~ [ c 6 ~ATKOV 5i J ry ti 6-76 FATYOON.. G 96-26 FATHOM 25-=- FATHOMS CO?JTOUA3 1m .FUT -:?' CAR5O- ATE S9 :OAL€i k A PROFILE LOCATION gAUTICAL MILES "T 0 5 10 15 20 -23 - 0 10 20 x 40 50 uV'~~ GIL01 TOE : VOSGES PIJON 0- OXFORDI-AIl C4 C> C,_ JBRED CALLOV IAN SURFACE Mai 1c> C5 PARIS . ROCK ;- Ss ~~r .....: .lw CON3^1 LANCH IEN FORMATION - OQ O O O O_ 100- OOLIT BLANCHE F M . ~BA TH©NIAN ~9 4 0 O JP 1 - XFORDIAN L 1.7 M . : : ...... :F^ LyL := °$ 1 ~ DV1F"ySW it l ...... : . . . : . C BAJOC IAN r L-I I i J - - - 1LUJ l . AIN 1 L JURASSIC PELLET. CO-3 MUD SEDIMENTS OOL i-rI - B I QCLAST . G ITI~CT [T11 PARIS BASIN REEFOID ARGILLACEOLJ . 0 0m 5®km m i see PARIS i ...... • .•• . .• .••• . .• ...... m°a o . :...... :::mop .. . . : ::: : : :: . 'c' . .. ::: :::: :' : CHAUMONT I ,~ ~ b ...... a® .ma f •eocy° m f ®°° ° .• .•• .• .• . .• .. . ® °4 F ° o: 10 00 000 o j DIJON lTl FVT NUN 4 6 25 lun C ONNE R . ~ SEINE R . PT - 1ftL _ C05 MUD MUDDY PELLETOID SAND A L GRAVEL ~- _ --_- ONCOID PELLETOIDAL SAND CORAL BIOSTROME i MIXED OOLI i E -BIOCLAS T. SAND - -~.y PURE OOLI T I C SAND ~~ CRINO ID- CORAL - BRYOZOA SAND mLL V _-== (M9 (o ®S! T M RNE . SEINE R . MU E R . T 5kmm ARG I LACEOUS C05 MUD CA L_CI - SI LT CRINOID- CORAL- BRYOZOA SAND = PURE OOLI i IC SAN D ------MIXED ®QLITIC° C3I®CLAST. SAND r .------aBAHA ITH" AND _'~ E IOMOM PELLETOI DAL SAND ONCO1 DAL GRAVEL CAANLOVl MUDDY PELLETOI D. SAND CYCLE e p 0 PARIS 00 O 'I 0 a ~II~li! a BASIN 0 i 00 ILILLU4~U i !VOSG oa I , ~aooo~° 6 ® o© p Ot>fl ® p O p D pp p G a ° D ON 7L a . p 04 o °r~` a f! O 'VAN; D " C f /BRESSE' 3p fI .' R 6 b f JU f Pa ALL ET O C ll SAND MUD ,LC H ALT. A IILL MUD `b,;p/ r7 t1 1 i ------ ------MIDD'-J-- ©OSJ ::O © D000L7C ~rJ Ci000O09~3 c~Q 0 F7v _, cC - . . v . .^Oi~03 oo ~ : o '0 0~ 6 00 06 C, 0 ', f III 1 . °~ S E aA L E V LL d ; R . R E OF THE LAGOON L ip" OPEN N/1 "A. T AS MONTEREY Y NUEVO LEON CUIDAD VICTORIA /iMATEHUALA SAN LUIS j PGTGSI CEN aR AL MEXICAN SAN TAMPICO LUIS Spoyos€u PL AT RI VALLES°~ a GUAN4JUAro \,_. . T LI [VIA i f ° L ACTOR ° '"° HIDAL GO °PA C H U CA MEXICO . S CITY t 0 50 100 ! 200 MILES 3 9 0 100' 200 3o0 Sao KILOMETERS, SCALE M DL ' CR- T A 1. `n L FORMS NE °J ME iC0 00 1 Central Z Golden { 3 Queretaro 4 Cuidod 5Monterrey, 6 South European Mexican Lane Jalpan Victoria, Sierra do] Texas Stages Platform and Area Peregrina Frailo East, edge Poza Rica Canon Tertiary Danion CHICONTOPEC CHICONTOPEC CHICON70PEC I MIDWAY- - .V A R R=i D M oooa4rich4ian oa 4rich4ian _- MEND -EZ~~_ ~ na END EZ, MEXCALA _ iENDEZ - DIFUNIA ~ry, I _7AYLG o Com panion - ~- r --r _ _.- o Sontonian -___-_ ,y d'~ . Illl . SAN FELIPE~ SA N F EL/PE . SAN FELIPE ~PARRAS-_ AI u> Goniocian . ' N=-_z T- SOYA i A Ls - --=7= - AQUA NUEVA ? Turanian fAOUA NUEVA NUEVA ; BEAG LE FORD_ I NDIDUR q -A EL CUESTA _ A v Cenomanion - ' CUE -~ ABRA c~ EL DEL DEL CUBA CUc A ~ ABRA jLjo R' E TOR DEL CUBA GEORGETOd Albian TAMAU 9 ? UPPER a - V LIPAS ? EDV~ARDS I ~ i J I k TAMAULIPAS AURORA GLEN DOSE UPPER OTATES' QQ ATES A PE _N H PEA RSALL _= Aption TAMAULIPA ------0T ATE _S__-_ _ -7-1 LOVlER . CUPIDO SL IGO ~-B -a-rrc-mia-n-~ TAMAULIPAS 4p . ? : : ... E f ci crivian -LOWER - LOVER 1 TAMAULIPAS I HOSSTON ? a f V olan g i n ic n ~~ TAMAULI®,P~ AS alBerriosion Portlandion - f MI ENT - F COT T ON= - PIPr11EN7A _ ? •, = TA- = A CASITA- • ;' ; VALLEY = a< Kimm er id gi an ANDRES 7AMAN LAS-_:' :-. OLVIx- Do .------(3UC KNER- '~~~ D ZULO A GA TgMqN ' TRANCAS ZULOAGA x SttACKOVER OUordian 777A - •JOYA :- MINAS; ;VIEJAS Sandstone = - Shale __ Calcareous shale Argillaceous limestone ~~ Thin - bedded and /or . Massive , g enerally r^ "~ rEvaporites fine - g rainad ' , limeston ® e F 1~ f ossil i fero us limestone x "_x 1 . Carillo Bravo, josei 1969, Inst . Mex . Petroleo, Seminario Sobre Ex'ploracion Petrolera, Mesa Redonda 6, 19 p . 2 . Well information, Petroleos Mexicanos ; Barnetche, A . and Illing, L .V ., 1956, 20th International Geol . Congress, Mexico, City, 38 p . 3 . Segerstrom, Kenneth, 1962, U .S . Geol . Surv . Prof . Paper 1104-C, ,-p.' 87-162 ; Carillo Bravo, 1969 (see 1) . / 4, Corpus Christi Geol . Soc ., 1963, Field Trip Guidebook . 5, Humphrey, W,E, and Diaz,Gonzalez, Teodoro, unpublished section . 6 . Same as 4 . ` 4 i,tass v~ uiphide Deposit of the Precambrian in Arizona CP/ Z, D. J . Alidrick The Iron King Sine Introduction : The Iron Kin- mine is located one mile west of the village of Humboldt and 75 miles NNN of Phoenix at 30° 341 N and 112° 15' 30" W (Figs . 1 and 3) . Mining began in 1906 and continued sporadically until the property was pur- chased by Shattuck Denn Mining Corporation in 1912. Since then it has been in continuous operation 'and has a present mill capacity of about 1000 tons per day. Zinc and lead concentrates are produced, from which cadmium, gold, sit- ver and copper are extracted . Structure and Lithology : The ore deposit occurs in a group of steeply-dipping, metamorphosed eugeosynclinal volcanic and sedimentary rocks of Precambrian age. Defor- mation and metamorphism of the host rocks has obscured original structures . The rocks are part of the Alder Group of the Yavapai Series (Figure 2) . . The " Alder Group is made up of thinly bedded sediments of both volcanic and det- vital origin with some flows and tuffs . The rocks in the mine area strike N26° E and dip 780 WNW . Structural studies indicate that the sequence represents the western limb of an overturned syncline and thus the succession is from west-to east as listed below . In the immediate vicinity of the . deposit (igare 6i), the rock units are : (1) The Spud Mountain Breccia This unit is. about 5, 000 feet thick, lies to the west of the mine, and occurs stratigraphically below the ore horizon . It is andesitic in comp- osition, and may represent either flow breccias or welded ash tuffs . (2) The Lower Spud Mountain Tuff This unit lies above the breccia (1) and is 2,000 feet thick . It is composed chiefly of interbedded chlorite-sericite schist and quartz-sericite schist . The chioritic schist represents% metamorphosed andesitic tuffs and Flagstaff J am mazotzal 340 a ins Gila Mountains 32' 132' j a oBisbee t 1140 1120 1100 Ficuat 1 . -Index nmp of Arizona show i ng location of Jerome area . Approximate position of the three prlnclpaI topographle regions of Arizona outlined . The P lateau region is to the northeast, the Desert region is to the southwest , and the Mountain region Iles between theta . After Itansonme ( 1903 , p . 10) . S EAST OF SHYLOCK FAULT h . . , ggd ggdi Sgs =Sgt 7 e Ika, g F ikat ggl4 ggi-O• g`b ggi--7- 7-1 s Iron King volcanics Grapevine Gulch formation 0a Andesitic and basaltic flows, ika ; tuffaceous Fine-grained tufaceous rocks and cherty beds, ggs ; lithic C) sedimentary rocks, ikat tuffaccous beds, get ; volcanic breccia,ggb ; dacitic flows, v ggd ; grading into intrusive dacite, ggdi ; intercalated smt andesitic flows, gga ; jasper magnetite beds, ggi V fsmb smr • 'sma c. Spud Mountain volcanics .dtii'~ ~] to Andesitic breccia and interbedded tufaceous dr o age sedimentary rocks, srnb ; ,tine-grained and.esitic tie aceous rock, smt ; intercalated C) andesitic flows, sma, interbedded rhyolitic Deception rhyolite a tuff, smr Rhyolitic flows, breccia, and tv aceous beds, dr ; Z 0 coarse rhyolitic breccia,db ; intercalated andes-. 0 itic agglomerate, dag ; intercalated andesitic Ma iht flows, da h Q Indian Hills volcanics o, o U h Andesitic and basaltic flows, iha W rhyolitic f ows, ihr Shea basalt Brindle Pup Dacite of Burnt a. '~v, andesite Canyon FJ. tgrt ~., • Basaltic flows,sb ; inter- I~ rz tgps ' calated tu, `•aceoussodi- Porphilritic Porphyritic dacitic w ,1 mentary rocks, st ; andesitic flows a a Texas Gulch formation intercalated rhyolitie flows • O 03 Rhyolitic tuff and interbedded conglomerate, flows and breccia, sr a .x tgrt ; chiefly purple slate, containing 4) lenses of limestone, tgps bt br o°o bac, a Buzzard rhyolite . Flow-banded rhyolitic ,lows, rhyolitie flow breccia, N0 a Chaparral volcanics volcanic breccia, br ; fine-bedded rhyolitic tuf.bt; Andesitic tuffaceous rocks, ca ; intercalated basaltic agglomerate and flows, bag rhyolitic tufaceous rocks, cr CS µ CS y Gaddes basalt Green Gulch volcanics Chiefly pillow lavas, gab; local intercalated Andesitic-basaltic flows and fragmental rhyolitic flows, gar rocks, andesitic and rhyolitic tufaceous ' ' sedimentary rocks PRODUCTS OF ALTERATIC )N AND METALLIZATION si~f Quartz or jasper lenses , pods, and veins hicludes alteration zone at Iron King mine, Y . V !Z Z i y s a C 66 01 V ~yl = y ~• • Y< $ B L A N r = z es p A a .G. ap~ aC s : a 1 y t q [ 4 } c 2 Y • ~ ~1 ~ Y r q C1 a G ~W x o Y d q } c _' - ALOE g . Y pu ; r ~ L . 9 Z k ZVI ' e M 94 ^ : - a v Fig . 4 ;-Comparison of the mineralogy of the Iron King a nd United Verde deposits with other massive sulfide deposits Huelva, Rio Tinto Shasta Co inty de- Sullivan deposit, Ram melsberg de- dandy deposit . I Deposits at Kysb- Iron King deposit, United Verde deposit, diatrict. Spain posits, California Canada po t . Ger :nsnr 1 Manitoba , rim . Russ s Arizona Arizona (Baseman, 19;i) (Ciraton, 19w) ( 'uan ; on and (Lin i re.^. and I (Hanson, 1920), (Sticknep, 1915) Gunni ::g, 1945) Irving, 1911) t - - • Sulfide minerals Pyrito Pyrite Pyrite Pyrite Pyrite Spbalerite Pyrite ' Pyrite Arsenopyrlte Arsenopyrite Areenoii rite Chalcopcrite krsanopyrlte Chaleupyrite Arseaopvrite Chslropyrite Sphalerlte Py-rrhoute Sph Icrite Sphalerite Spholerite Galena Spbalcr to Sphalrnte Galena zphalerite i.alena Galena Chslcopyrlte Pyrite Chalcopyrite- Tennantito Chalcopyrtte Tenn.mtite Tetrahedrito Bornite Galena Arsenopy-rlte Galena Galena Tennantite Bornite Enareite Bornite Bornite (rare) Galena Luzonite Chalcocite Chalcopyrlte Fautltiulte Tennantite Chalcostlhite Whitnevite Umangite - Ha+tch2corrite 1'11m^nite Berthicrite(?) Gangue minerals a nd hydrothermal altos lion products Quarte Quutz Sericlte Quartz Chlorite Barite Sericite Quartz Ankerite Ankerite-dolomite Calcite Quartz Carbonates S Barite Ferlrito Chloritr . - Barite Specubrite (uartz Serielte Apadte(?) \laencure Dolomite Chlorite Rutile Specular hematite Rutile Listed to order of abundance. 3 0 .-- tJ j -crystal tuffs . The quartz-sericite schists are likely metamorphosed rhyolitic tuffs and . crystal tuffs . (3) The Ore Horizon The ore occurs as a series of overlapping conformable bodies of massive 1 . sulfides and associated lenses of massive quartz and quartz-sericite schist, A parallel zone of copper mineralization occurs within the stuctural hanging- 7 wall rocks . The massive sulfide lenses lie at the contact of the metarnyoh.te of the Lower Spud Mountain Tuff and the meta-andesite at the base of the .. 4. Upper Spud Mountain Tuff(Figure 6) . The lenses of ore occur as "en echelon" 3 layers in compound lenses (Figure 5) . The massive sulfide zones are fine- grained grained and commonly banded, with gangue minerals consisting of quartz, carbonates, sericite and minor . chlorite . Pyrite is the dominant sulfide, with lesser amounts of sphalerite, galena, chalcopyrite and arsenopyrite . The southern end of the ore zone grades into green-gray quartz-sericite schist ; -the northern end terminates sharply against greenish massive quartz which locally contains coarse crystals of sphalerite and galena . The "Copper Zone" mineralization is a 400 foot wide band of chalcopyrite- tennantite occurring in veins and stringers with quartz and/or coarse black chlorite in the structural hanging-wall of (and therefore stratigraphically below) the massive sulfide horizon . Gilmour and Still suggest that the orebody formed through the agency of a volcanic hot spring (yielding metal-rich, siliceous sinter deposits) on, or a near , a submarine surface of deposition . (4) The Upper Spud Mountain Tuff This unit is stratigraphically above the ore horizon and outcrops, to`the east of the mine . It is a series of laminated to massive meta-andesites and interbedded sediments including tuff, crystal tuff and ag lo~mer-ate . A thin bed of conglomerate containing chert and jasper pebbles occurs near`the top EXPLANATION (Cont'd) I No.7 Shaft I EXPLANATION TERTIARY ' Strike and dip of foliation o G~7, Gravel 6O/ Z Trend and piunge of t F~ rh Porphyritia rhyolite a E O ~n ~ O uO S 0- Buildings \ ~± k~ f r ° PRECAMBRIAN n 0 . 6 Shaft Q~ iron King Andesite p1 0 a+ Shaft No Q • OQ r v F', -' - Meto - andesile %.rt t n ©Caved workings, r +~ Gritty" sericite schist ~~ Underground workings on . . ; , !e/ rr r b No . 2 Shaft A 900 Level Spud Mountain Volcanic Rocks 3000N r l A •, l -~ ye ~,3000N Ur. Tuff Unit lf Intermittent wash l~ J l r / '~ / l l I __ _ Meta- andesite 2500N 1 ! ", 2$001! r ! ,"v r e E~~ J .'•o Pebbly sandstone or tuft El 1 f f ~ f. tIS ~ ~ •~~ :f usmt Ismi . Phyllite l l r r , lr r 715mt f "Gritty", sencite schist - llr ~~J1r~Ii W l r ' J _ C-0 p ismt r,'rr J, X -Y l .~ 1 o '/, rr J l r Lt . Tuff Unit r IF / '8 Massive quartz " Massive sulfides F 11 IlLJ' '" !rr°,r rrr /," rr„'rl (' 1 ',,rr(( .73 y' o e A_ y° r l~(I ~ s I!!! F' :^Y r,,rr°!!/ r~ , / r l / t r r r 60'! ;' l Pyril,r, quartz schist - r 1 o a o 25 / ~, ri l!l r r, l i / l, r r r •, )'7 3 t ' / Ismt a ,,, r . ! r r J r' l 1 Ouortz- sencte schist t ,~ r, r Jr . l J B2 l r , L}~r~ , l j ' _ 0 2000N 20001V Meta - andesite soil Sp J 7 f . IBS ~~ ~',/' r r ., 'Y a QQ . tD l,' '1 r l r l 0 C O C) . o ' r r l / 1 , r/ usmt / l o'' o e' ° J Ill r l l .\,Yir / i J' 'usmi' 0 '80 y J O' y1 O r .~r /Z ,ll ° tl, , 1 /j, t y l !lr r / r,,! l , , J +r 1, i \ .r .J .I r~~,' 70 y''o~r' r•rrr li l~'- . l , / l l l I f / , l r ! r ll .\' j,', r . 60 ;/° 74 I, r ! //' Jl l .,ro y I f l O_ A Al 2000,1 r'r l t ! l' r J , ' r l!l r r Scoter Feet . 61 • Copper Shott! ! r r r l ' , - io ' l! J ! l J ! I! r °a, 0 500 vQ \n?' f V ' FIG. 6 Geological Map of (tic Iron Kif:g Mine. of this unit . (j) The Iron King Andesite This unit succeeds the Spud Mountain Tuffs and outcrops further to the east than (4) (Figure 6) . It grades upward (eastward) from pyroclastic mat- erial intod undeformed massive andesite with locally preserved pillows . The United Verde and United Verde Extension Mines Introduction : These two mines, owned by Phelps-Dodge Corporation, liea mile apart, and about 20 miles N?W of the Iron King mine . Underground mining has ceased at both properties (United Verde Extension in 1938, United Verde in 1953), but open pit operations are still in progress at United Verde . Litho and Structure : The massive sulphide deposits occur in the upper part of the Ash Creek t _ . Group which consists of thick units representing two cycles of basaltic to rhyolitic volcanics overlain by pyroclastics which are interbedded with chert . The great thickness of the Ash Creek Group (over 20,000 feet) suggests a : eugeosynclinal environment of deposition while pillow lavas and ferruginous chert beds indicate a subaqueous environment . The rocks are folded along ;a :, .Nri axis and have been metamorphosed to greenschist f acies but generally, relict textures and structures are preserved . The upper two formations of the Ash Creek Group (Figure 2), the Deception Rhyolite and the Grapevine Gulch Formation above it, contain the massive sulphide deposits at Jerome . The crystal tuff/quartz porphyry member of the Deception Rhyolite, called'the Cleopatra Member, has been dated at 1,820± 10 million years . (1) The Deception Rhyolite This unit is approximately 4,000 feet of rhyolitic flows, breccias and tuffs with the Cleopatra Member about half--way up the section . The upper 3" cZ ~ / 99 UNITED P: VERDE ,` UNITED VERDE NO, // EXTENTION y . Pz ,tyi• . ms Z r,' t JEROME Phoenix 4045! PHANEROZOIC Pz °iC ROCKS ' CL E O P `T RA 75 ; ~ dl GABBRO 8reccia go 0 All 70 . BLACK SCHIST ~d u ., .,r : . `: . .: 4 . ct 99 - ~ : ' m : 's,o ~M O _ ` ~.9O g yc' m5 ~80 : . : Q u dI MASSIVE SULFIDE :. Pz GRAPEVINE GULCH FORMATION ' E I ~SHEA du L r 70 ~ . 7O dl dt BASALT :: do - dco do : ht ESCAL di db doa ...... DECEPTION RHYOLITE # . iacb ai du Upper unit i dc Cleopatra Member dog ~ dcb 6reccia in Mescol Gulch .' dcc Chloritized rock PALEOZOIC ROCKS , dI Pz dl • Lower unit Pz sb db Bedded breccia db '' •0 2000 FEET dog Andesitic agglomerate Ftc.7 Geologic neap of area south of Jerome moditied from Anderson and Creacey (1958, Pl. 1) , inset shows location of Jerome. t half of the Deception Rhyolite is mostly breccia and crystal tuff with smaller beds of red siltstone . (2) The Cleopatra Member This unit represents an intertonging complex of flow-banded quartz por- phyry, breccias and crystal tuffs . The crystal tuff zone contains numerous k angular quartz clasts and large amounts of sericite and chlorite . The flow- banded banded quartz porphyry is a rhyolitic extrusion or shallow intrusion . (3) The Grapevine Gulch Formation p Complex intertonging of flows, breccias, crystal tuffs and fine-grained tuffs is common in the Grapevine Gulch Formation and throughout the Ash Creek Group . The lower part of the Grapevine Gulch Formation has a sharp contact against the Deception Rhyolite and is composed of alternating bands of breccia, coarse- and fine-grained tuffs, chesty shales and chert beds . The fine- grained grained rocks of the Grapevine Gulch Formation intertongue with the massive sulphide lenses . Minor, purplish, quartz-bearing crystal tuffs are found in- 4 tertonging with the major beds of the formation . (4.) The Ore Zones k The United Verde Mine has two ore zones, called the Main and North orebodies (Figures 8,9,10 and 11) . The ore zones consist of massive sulphide t lenses and related "black schist" and "quartz porphyry" ores . The massive sulphide lens of the Main orebody is pipelike and plunges at f . 60° . The contact of the massive sulphide with adjacent rocks is usually sharp, but occasionally is gradational into disseminated pyritic rock . Quartz lenses, cut by veinlets of pyrite and chalcopyrite, occur along the hanging-wall and , occasionally within the massive sulphide lenses . The contact between the massive sulphide and the Grapevine Gulch Formation on the hanginggall side of the lens is conformable (bedding parallel) and occasionally intertonging . The North orebody occurs in the lower levels of the mine about 500 feet north- s (7/ t + + +' + + + + + -t + + + + + + + + + •~ + + + + + + + f N• . + + + + + + + 4 + + + + + + + $- + + + + + + + + + + + + + + +{ 4- + +Ft'+ + + + + + + + + + + +{ + +• + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + F + + + + + + + - + + + r ( \` }{,L ~ • .h f . qP t+ }}}[\ r + + + + + ' . ,` _ . . + + + + + + + + + + j + + + + „- + . + + + + EXPLANATION + . + + + i Contact .,' r • ------+ + 4f + "l•t +• Quarts massive sulfide, and black schist Assumed position of former contact + +gb+ + + between Deception rhyc o te and # . .r + +. + + ar+~ ; a r y t ~` + +I Grapevine Gulch formation + + + + Gabbro Fault + + + + + + + + Quartz porphyry Assumed axis; of anticline, showing bearing and plunge z3 K -- ~'• ` Assumed axis of syncline , showing + + ++ -s- Grapevine Gulch formation bearing ;and plunge Y- + Deception rhyolite 200 0 600 Feet ,ause $ - CUggested structural interpretation at United Verde mine. 4J ~1 NW SE, OXIDE OR GRAPEVINE GULCH '~ FORMATION ' i i plT . i 3^3 QUARTZ : i R E QUARTZ R?HYRY - "" Tr~ V7 5^0 ' [4 QUARTZ i !C D 6 I BLACK I Qw", SCHIST f ~~Ii~af ( y ~ I350 ~ --- f-r r 1500 ! QUARTZ l!/ :so GRAPEVINE GULCH . J f 1803 } FORMATION ~~. X G U A R T: Z lyso f QUARTZ 2100 ` „ I 2250 ' G A B B R 0 P 0 R P H Y R Y 24001 2550 y QUARTZ D ' 2700 2850 7L ti - BLACK SCHI ST 3150 330'0 G , \ 3450 t• G QUARTZ MASSIVE SULFIDE EXPLANATION ' . 1 S r+ _ ' Contact, dashed where - - 3750 inferred 0 QUARTZ PORPHYRY `` - k Contact, dashed where • _ - 4 - racks ercalatc4 for t the open p.t c r fault _ . SIOpe 4500 p p ) . x 2 00 0 1000 fcmt Slooun 9 -veritcrrl section throubh Uuited Verde m[ne : Compiled by P . 1F . Yates, Phelps Dodge Corp. I3 FIG. 10 Interpretative section of the Cleopatra Member and assoei kited rocks after accumulation and before folding . In the northern part of the section, the Cleopatra Member is appreciably thinner and finer grained than to the south .': The . youngest crystal tuffs in the Cleopatra Member intertongue with the ma-sive sulfide lenses, upper unit of the Deception Rhyolite, and lower beds of the Grapevine Gulch Formation . o u O _„ u a ~ w O ^ ^ J ^ L v J f~j cA if C. L~:J a0•±D . -^ . . a . r = O J. O No r~ • tI t',, ' ~- in oil n ~ v ( ~~1 1 'G W >~~>ru- f ' ~ I rr r +~ ~' 1 .1I ~~ I(I 1 I 1 I 1 {~ + i I i ~ I + L v! °3 d V J m c J Q U , . west of the Main orebody . It consists of a 'number of lenses all occurring .' 3 within the fine-grained, bedded-rocks of the Grapevine Gulch Formation . The black schist rock consists of large masses of nearly pure chlorite that have been formed by Fe-',~.L metasomatism of the Cleopatra Member and the- ' Grapevine Gulch Formation ; The chloritization is most intense adjacent to the massive sulphide lenses . Anderson and Nash suggest that the black schist .,,rock + . is the result of hydrothermal' alteration due to upwell5ng of -hot, . dense brines . The black schist rock locally contains sufficient chalcopyrite as fracture- . , fillings to constitute ore . k1 The"quartz porphyry ore is formed by chalcopyrite infillings of fractures in-,the Cleopatra Member and it is essentially a downward continuation of the "black schist' ore zone, -"At the United Verde Extensione mine, the orebody occurs in the Cleopatra i Member, in undifferentiated DeceptionRhyolite rocks, and locally within Grapevine Gulch Formation rocks . The massive sulphide body has been modified by supergene enrichment which produced a chalcocite ore zone . -,Attempts have been made to show the pre Verde Fault relationship betw een :the United Verde . and United Verde Extension orebodies (Figure 13) . Correlation has been a t _problem because of subsequent erosion and lack of a marker { . horizon, but although earlier authors insist that the United Verde Extension represents the severed top of the United Verde orebody(Figure 13, location III), the most recent study of the problem, by Norman, Anderson, and Creasey (in Anderson and Creasey, 1958), suggests that the most likely original location for the United Verde Extension orebody is about 1300 feet ESE of-United Verde . (Figure 13, location IV) . Anderson and Nash (1972 suggest that the ore deposits formed contem- poraneously with their host rocks, but that they are not volcanic exhalativee sedimentary deposits . Their theory suggests that the ore is the result of II? 3.67°W. N .67° E- • a ts Y Y r h t Y p ' 0 A q j Y h , A Y 4 Ill a TY{ J S ~ $esstt Of the Hickey torirtejb Y Y i. .Y Y + a V r 7 Y A ° o 1 4 r A - A t 4 1 1 ' V h . r a T .~ a a >- t o ! e r a r e a h 0 . . tlmsatnrAt of the Hickey formation o e a ° ! 0 Gia ols p O O 0 • a 0 • ° I'125'Or1QMartin r, 0 go a a • o e . 4 . • . . .'• 6 .! -T4 ta's sand; pie • . d Quartz and ~C- ¢Vcs n • ,4 1300 d e•, 1200- sJ ti r s 1300- -X.: :i + 1400 2500- ` 1700 ` 1800 ? 100 C 400 Fe" ` . j • 1900FYouae12-Generalized seetlon through United Verde Extenalon mine . From Reber (1938) k 7 1 2000 N xs0 Lrv£~ \ N :,are LEVEL d4~ \ a6~ 2iP0 tfvt Lam ,~~ O 1 ,~ j ?650 If v£L r000 s J~( fide . var:-u5 i vIs. ~ ~ t? v ' UnrteG Verde mina low #000 L£MFM Oe~ Otl \ Outline of ore body 14*3 level, Unroll z _ `_` Verde Extens on m rx a LCVtz Present Surface 0• fake 1'` Axis of massive Sul- fide body, N.20*W. 65'N II! s 400 0 8A0 feat w .20005 ° rsovum 13-SL•etch map ebo-r ing interpretations of relationship of United Verde and United Verde Extension ore bodl•'s . a hydrothermal mineralizing solutions, that is, hot brines which dissolved the base metals out of the volcanics further down in the Ash Creek Croup, rose to the subrn nine paleosurface and deposited the massive sulphide lenses by pre- cipitation, pore-filling, and complete large scale minerall replacement of, the . pyroclastic rocks which were at that time being deposited . Bib lranhv (1) Anderson, C .A ., and Creasey, S .C ., (1958),, Geology and Ore Deposits of the Jerome Area, Yavapai County, Arizona; in U .S . Geol . Survey Professional Paper 308, 185 pages. (2) Anderson, C .A., and Nash, J .T., (1972), Geology of the Massive Sulphide Deposits at Jerome, Arizona--A Reinterpretation ; in Economic Geology,, Vol . 67, No . 7, Nov . 1972, pp .845-863 . (3) Gilmour, P ., and Still, A .R ., (1967), The Geology of the Iron King !,Line ; in A.I .M .E., Ore Deposits in the United States 1933/1967, Vol . II, pp . 1238-12570 A Rio strip, mine copper ore wrim Cats 1972 August WORLD MINING [United States Edition - page 731 85 88 lUnited States Edition - page 761 WORLD MINING August-1972 AMERICAN SMELTING AND REFINING COMPANY Tucson Arizona February 1, 1972 MEMORANDUM FOR : Division Supervisors KUROKO DEPOSITS Attached are copies of a few pages from a recent Japanese publication "Volcanism and Ore Genesis", University of Tokyo Press, 1970 . Over the past 20 years, newly discovered Kuroko deposits aggregate over 70 million tons of high grade lead-zinc-copper ores . The principal occurrences are strati- form and are believed to have been deposited on shallow sea bottoms during Miocene volcanism . However, epigenetic mineralization ----- in stockworks, breccias, and chimneys-----is present in many .cases . These structures are regarded as `the probable source of the metals in the stratiform (syngenetic) deposits . Similarities to deposits in much older rocks are evident . For example, . at. Buchans where barite overlies massive .zinc-lead sulphides which are underlain (in part) by siliceous, copper bearing stockworks . Another feature in common here is the presence of detrital fragments of mineralization-----indicating erosion by turbidity currents, or otherwise . The mineralized stockworks of the Kuroko deposits are depicted as being continuous in depth, in contrast to the evidence at Buchans and at Rio Tinto, Spain, where drill holes pass downward into unmineralized volcanics . In view of this lack of depth continuity, it has been theorized that the copper in the Rio Tinto dissemi- nated ore body was derived by remobilization from adjacent cupriferous pyrite----- a process promoted by tectonics involved in the crest of a tight fold . If, however, the stockworks constitute the source of the stratiform deposits, they could occur in the flanks of folds or wherever stratiform occurrences are found, although gravity sliding* (of the massive sulphides) could have separated them in space . The latter could account for the absence stockworks beneath or near some of the Kuroko deposits and likewise at Buchans . J .H . COURTRIGHT %` L .J .G . Schermerhorn, The Deposition of Volcanics and Pyritite in the Iberian Pyrite Belt ; Sociedade Mineira de Santiago (date missing) JIiC :kre Encls : as noted cc : J .J . Collins w/encl . Eric Swanson, Buchans w/encl . Kuroko Deposits in Japan, a Review Toshinori MATSUKUMA Akita Unlrersi y Ei HORIKOsHI Kyushu University INTRODUCTION The "Kuroko" deposit is a strata-bound polymetallic mineral deposit genetically related to submarine acid volcanic activity of Neogene Tertiary in Japan. The de- posits have been exploited and mined since middle of the nineteenth century . Recently, they attracted the attention of all Japanese mining geologists and miners through the discoveries of new Kuroko deposits of more than 70 million tons of high-grade lead-zinc-copper ores over a period of twenty years. Studies on the deposits in the early part of this century offered many interesting discussions . FuxuCHI (1902) and OHASHI (1919) presented the syngenetic hydro- thermal theory for their origin, but KATO (1915) emphasized a hydrothermal re- placement origin . KINOSHITA summarized his studies on the Kuroko deposits and proposed a low-temperature metasomatic theory (KINOSHITA, 1924, 1929, 1931, 1944) . The theory was supported by most of Japanese geologists for a long time. Recently, WATANABE (1956, 1959) again suggested submarine volcanic sedi- mentary origin for the Kuroko deposits, and the syngenetic theory has been accepted by many mining geologists in Japan since then . They succeeded in prospecting the deposits based on this concept . On the other hand, recent develop- flient of the deposits has presented many opportunities for providing new field data. Especially, relations between volcanic activity and mineralization and tti•idences for submarine hydrothermal and exhalative sedimentary origin of the deposits have been accumulated . "Kuroko," an old mining term in Japanese meaning essentially black ore, was II.Imed because of its black colour . HIRABAYASHI (1907) defined it as an ore which is a fine compact mixture of sphalerite, galena, and barite . KINOSIIITA (1944) de- fined "Kuroko deposit" as a deposit genetically related to the Tertiary volcanic rocks, consisting of one or a combination of Kuroko (black ore), Oko (yellow 01'e), Keiko (siliceous ore), and/or Sekkoko (gypsum ore) . He emphasized that the 153 cy v 354 MINERAL DEPOSITS OF VOLCANIC AFFINITY 4 Kuroko deposit should be limited to the deposit in which typical Kuroko occurs, He also proposed that the name "Kuroko-type deposit" be applied to such an Ore deposit as allied types consisting of only pyritic or pyritic -siliceous ores, or as vri I)- type deposits formed along paths of mineralizing solution of the Kuroko deposit,, On the contrary, O1ASIII ( 1962) recently gave the name "Kuroko-type deposit" to one which is defined as bedded sedimentary deposit formed by submarine vo)- canism. Following him, HORIKOSHI ( 1965) gave another proposal from the v iew. point of mctallogencsis, that a "Kuroko-type deposit" is a deposit formed und c,- conditions of nearly neutral pH and sufficiently low Eh ." The Kuroko deposit' are, however, so complicated in their nature that these brief definitions are riot sufficient to show their characteristics . It is desirable to have the nature of the F Kuroko deposits understood through following descriptions on the deposits . GEOLOGIC SETTING All of the Kuroko deposits occur in the so-called Green Tuff 'region (cf. Part 1 ). Distribution of the Kuroko deposits in the Tohoku district is shown in i Figure 1. Geology of the region in northeastern Japan is characterized by forma- tions of thick geosynclinal sedimentary pile of about 3,000 meters in. maxim urn thickness. Stratigraphic succession of the Miocene formations in the region is representated typically by that of Akita district where the large Kuroko deposits, such as those of the Kosaka , Hanaoka and Shakanai mines, are located nearby (Table 1 ) . Though age of metallic mineralization of Miocene in this region is not single, the age of the major one is from middle to later Miocene at whichh structural development of the geosyncline changed its nature . The Nishikurosawan. stage was a period of beginning of the geosynclinal sinking in the inner zone of the Tohoku district, northeastern Honshu . This sedimentary basin shows maximum sinking at the Onnagawan and Funakawan stages. But the eastern part of the basin, i where upheaval movement of the basement began at the Nishikurosawan stage, offered the place of intense volcanism which was associated with Kuroko miner- ' alization . As compared with the main part of-the basin which is the most produc- tive oil field in Japan, the eastern marginal part may be considered to be not an open sea, but an inland or a trench-like sea . Based on our present knowledge of the mode of occurrence of the Kuroko dc- posits, we know that most of them occur in a definite stratigraphic horizon of the' Nishikurosawan stage that is characterized by the accumulation of sandy and muddy sediments in which abundant molluscan fossils of warm current are found . The leading microfossils of the stage are as follows : Globigerinoides triloba ( RExss', Nonion kidoharacnse FUKUDA, Globorotalia cf. fohsi CL'SII MAN et ELLISOR, . G. Sci1n a (BRADY ), Globigerinoides trilobtts (REuss), Ammonia tochi,iense (Ucmnno ), Pullenia bill- loides (D'OanmGNY), and Gyroidina orbicularis D'Oiti3IGNY. On the other pane, sediments of the Onnagawan stage conformably overlying the NishikurosaWi' :!>> KUROKO DEPOSITS : REVIEW 155 Nishi~'atg9t es rQ Kamiiso ~/ Oage • Kuroko deposit e Stockwork type AOMORI } Kamikita ACMORI o Gypsiferous type Ozaki PREFECTURE ®Towada Yun_oc 0 City ?o AKITA ' REFECTUR IWATE i, o PREFECTURE Yoshingm • t•tTsuchihata - m Tagonai Fukufune . r YA6tAGATA I + MIYAGI ~~ PREFECTURE , PREFECTURE SE I 0 ^~ YAMAGGATAi• Yoshino _~~. , NIIGATA i NIIGATA i~Yonahata PREFECTURE ¢ri FUKUSHIMA o i- Ishiga Tastiiro+ FUKUSHIMA Yo ota PREFECTURE Kurosawa• / 0 1 . . T00km Fig. 1 . Map showing distribution of the Kuroko-type deposits in the Tohoku district (Northeast Honshu). formation, show homogeneous lithologic facies over all areas, and consist of thick well-stratified siliceous and hard mudstone intercalating thin acidic tuffs . The formation is considered to be cold current sediments, and is generally poor in fossils. The fact that Globigerina sp., Globorotalia sp. and some others, seemingly the re- presentative species of the Nishikurosawan stage, were found from altered muddy tuff in ferruginous quartz zone directly overlying Kuroko ores of the Uchinotai deposits, Kosaka mine (ISHIKAwA, 1964), is very important in the consideration s CA } { 5 Table 1. Schematic geologic succession of the Miocene formations in the Akita district, northeastern Japan (after HvztoKA, 1963) N Age Stage Litholog3 Remarks z Rlivolite, dacite, ancle%ite, mudstone, and '1'entoku i Dew a .Disturbance sandstone (marine r Late hunakawa Rhyolite, andesite-dacite, black mudstone _ -'- - a\Iiocenc (marine) O Ounagawa Rhyolite, andesite-clacitc, basalt, clolerite, silievous hard shale (marine) cn (v Rllyolite-dacite-anclesite, basalt, quartz------Oil-bearing formation Nishikurosawa diorite (holocrystalline granitoids), deposits and O Middle sedimentary rocks (marine) allied veins r Mi ocene ------Regional llaijima Rhvolite-dacite, basalt, sedimentary rocks __------(plant and molluscan fossils) ---Metallic mineralization n 1 Trachvtic rocks, alkali-rliyolite, dacite, ITI A lonzeu altered andesite, olivine basalt, Early sedimentary rocks (plant fossils) ------Intensive and extensive z i~iiocrne volcanic activity Akashima Altered andesite, dacite i Pre-Tertiary Granite and slate i 7 a V , t KUROKO DEPOSITS : REVIEW 157 of age of the formation and genesis of the Kuroko deposits . At the Shakanai mine, zonal division by microfossils is utilized for correlation of formation boundary and ore-bearing horizon. Volcanism of the earlier Miocene in the Akita district was characterized by the alkaline and tholeiite rock series . The latter continued to the Nishikurosawan stage. From the later Nishikurosawan to Funakawan stages, volcanism of calc- alkaline rock series was intensely active . It includes activities of various kinds of volcanic rocks, such as augite-olivine basalt, two-pyroxene andesite, hornhlende- pyroxene andesite, dacite and rhyolite . Some acidic members are plagiorhyolite which has no mafic mineral, or dacitic rock which contains small amounts of bio- tite, hornblende and rarely pyroxene . The Kuroko deposits were formed in close relation with the activities of calc-alkaline rock series . Based on his field observations, SATO (1968) concluded that the Kuroko miner- alization of the Kosaka mine took place on a rather shallow sea bottom, probably 100-200 meters in depth, and the sedimentary basin was bounded by a barrier to open sea, though it was linked with the open sea through some channels . His con- elusion may be applied to many other mineralized areas of the Kuroko deposits . FORERUNNING VOLCANIC ACTIVITY As the Kuroko deposits have close genetical relations with submarine volcanic activity, it has been required in particular to study the mode of volcanic eruption and mechanism of emplacement and sedimentation of pyroclastic materials in the sea. According to the results of geologic surveys in the mining area, most of pyro- elastic sediments under consideration are pyroc lastic flows deposited from tur- bidity curr_..ents accompanying submarine eruption . They generally started first, with massive tuff breccias rich in lithic fragments and then changed to notably stratified tuffs intercalating mudstone with double grading . Emplacement of lava domes and flows repeatedly took place during the period of pyroclastic sedimenta- tion. Some of them are small in scale, but others extensively overflowed on the sea . bottom. Submarine lavas under consideration show auto-brecciated structure due to rapid cooling in many cases . Steam explosions also took place on the side of the dome during or after the formation of lava domes and flows. HORIK05IUI (1966) showed that the mass of these explosion breccias is only 30 x 30 x 10 meters . St- rongly altered rhyolitic lavas have been frequently reported to lie under the Kuroko deposits. It has not been confirmed whether they consisted of several flows or single one . They are called "white rhyolite" by mine geologists and they are generally poor in phenocrysts, massive but brecciated, and altered toquartz- serieite rock, white to light grey in colour in most cases . Their primary petro- graphic properties are not easily identified. Most of them found at the Kosaka and '3 4 J 158 MINERAL DEPOSITS OF VOLCANIC AFFINITY Hanaoka mines are small lava domes, not more than several hundred meters in diameter. It is questionable whether or not rhyolite lava flows under the ore-bear . ing sedimentary complex continuously occupy the underground of thee north Akita sedimentary basin from Odate to Kosaka as shown widely in geologic pro . files by SAKAZAKi et al. (1965) . Most of the Kuroko mineralization are genetically related to activities of tlic lava domes of relatively small scale . Rhyolite masses in the Kawajiri formation around the Tsuchihata mine are composed of three types characterized by dif- ferent petrographic properties . They are lava flows, lava domes associated with flow type in part and intrusive lava domes . Each mass is small in scale under 1 km3 even in the largest one . Nine dacitic masses found in the Kosaka formation near the Kosaka mine are also lava domes of very small scale . The Kuroko'miner- alization seems to have genetical connection with exhalative action that followed the steam explosions . However, some of lava domes were accompanied by this kind of explosion, the others were not . Though properties of the forerunning volcanic activity accompanied with lava domes have been gradually clarified in the Kuroko mining area, the Kuroko de- posits are not always associated with volcanic activity of this type, and there are many deposits which occurred only in pyroclastic flows without any lava dome and flow. Such are distributed in southern area of the Tohoku district, some examples being deposits of the Yoshino mine, Yamagata Prefecture, and gypsum deposits of the Aizu district . ALTERATION Various modes of rock alteration are distinguished in the area of the Kuroko mineralization ; (1) diagenesis, (2) regional alteration, (3) post-magmatic hydro- thermal alteration, and (4) alteration directly related to mineralization . `These alterations generally are not easily distinguished from each other, because they overlapped in many cases, especially in the mineralized area . UTADA (1965) investigated rocks of zeolite facies of Mogami district, Yamagata Prefecture, and concluded that (1) Tertiary formations in the region may be divided into five zones of zeolite facies according to the assemblage of authigenic minerals replacing volcanic glass, (2) the boundary of each zone is not always con- cordant with stratigraphic boundary and geological structure, and (3) nature of regional zeolitization may be controlled not only by nature of sedimentary pro7ss and kinds of source materials, but also by some other processes acted after burial of the sediments. He classified the zeolite facies of the district as follows : Zone I : Unaltered glass; (opal and montmorillonite) Zone II : Clinoptilolite, mordcnite, opal and montmorillonite Zone III : Analcime, hculandite, adularia, chalcedony, quartz, montmoril- lonitc, "intermediate clay" and chlorite ; (albite and epidote) i 160 MINERAL DEPOSITS OF VOLCANIC AFFINITY r Z o N N a .+ X- I~E Zo y CL " a=i vC ,, °ACL c _o >1 0- /// CnN U UO b E N 0 Y y i J o~7 \ LandC L C ~ '~• OcJ T4! O 00 • . i~ 'J J J J l~ :S N J JJ a O J J J J J J J J • O J J J J J J J C :~ JJ C Z j J J •3 J L c a~ 5, of J O' 0 LLV ' J J \J JS JJJ J J Z ~, ~ t JJ ¢aU~~ Shakanai mine . Thickness of zone II at the southern corner of the Odate Basin reaches about 30 meters though the ore bed in the area is only a few meters in thickness. The boundary plane of each alteration zone crosses a stratigraphic boundary though it is usually low in angle . h . ., am w ,, . . . n ac ~ .v -v acx,. wy~ a..warn~?%h KUROKO DEPOSITS : KOSAKA 187 ;1'Iotoyama dacite lava domes is situated in the most western part of the distribut- e ing area of the Uwamuki tuff breccia, and the member can be subdivided into several unit beds near the lava domes by thin strongly argillized bed, and (b) petrographic characteristics of the lithic blocks of the Uwamuki tufl'breccia and the Motoyama dacite are very similar . A large quantity of lithic blocks which compose the Uwamuki tuff breccia are inferred to have been formed by phreatic explosions of the dacitic magma brought into contact with sea water around the submarine vents. liotoyama Dacite Lava Domes Nine dacite lava domes are recognized in the Kosaka formation of the mapped area (Fig. 4) . Their eruptive sequence, which can be determined by spatial rela- tion of the neighbouring domes (HoRn Motoyama Volcanic Breccia The volcanic breccia is accompanied by five lava domes, Ms to IvL . The follow- ing features are observed in the volcanic breccia : (a) It occurs on the flanks of the lava domes, (b) it grades downward into the auto-brecciated parts of the lava domes, (c) it consists entirely of fragments of the lava, and (d) grading in the volcanic breccia is of a single cycle. These features strongly suggest that the volcanic brcccia were formed by steam explosions at the flanks of the lava domes just after their emplacement . MINERAL DEPOSITS DISTRIBUTION OF THE MINERAL DEPOSITS The Kuroko deposits of the Kosaka district occur in and above the Moto- yama volcanic breccia and, in some parts, in the Uwamuki tuff breccia . They are a(rr.mged in NNW-SSE direction as seen in Figure 4 . The most marked feature with . respect to the site of mineralization is the intimate relation of the dacite lava domes Jrld the accompanying volcanic breccia with the mineral deposits . For example, the Ucllinotai-nishi deposit is accompanied by M9 lava dome, the Otarube ~lrl~usit by M7 lava dome, the Uchinotai-higashi deposit by Me lava dome and the - Xfotoyama deposit by M6 lava dome . 1JCIIINO'I'AI-NISIII DEPOSIT General Remarks Uchinotai-nishi deposit is the most western and earliest developed deposit in 18£3 • MINERAL DEPOSITS OF VOLCANIC AFFINITY the Uchinotai area . It is composed of two ore bodies , which are arranged in direction separated by a fault . There are two different sites of sulphide mineraliza . tion. One is a dissemination deposit in the Motoyama M9 volcanic breccia, and the other is a stratiform deposit situated between the Motoyama Mg -Volcanic breccia and the Kosaka -Tetsusekiei bed . The stratiform deposit is generally divided by zinc content into zinc -rich upper half and zinc-poor lower half, and ores from these parts are called Kuroko (black ore) and Oko (yellow ore), respectively. The boundary plane.;between the stratiform deposit and the overlying Kosaka-Tetsusekiei bed is sharp and essentially parallel to the bedding plane of the overlying rocks . The nature of ores changes gradually downward from the stratiform deposit to the disseminated deposit through a narrow transitional zone (less than 1 m) . The disseminated ore is mostly highly siliceous and called Keiko (siliceous ore) . The structure of the volcanic breccia is well preserved in the disseminated ore . The distribution of economic disseminated ore is restricted within the volcanic breccia . In the underlying brecciated part of the dacite lava dome (1 9 ), the amount of sulphides is decreased . Further downward , both the brecciation and mineralization become weak enough to call the rock altered dacite . A gypsum ore bod y occurs at the eastern margin of the volcanic breccia in the shape of an irregular mass besides the above-mentioned sulphide deposits .: Mineral Assemblages and Zoning of the Ores The main hypogene minerals constituting the sulphide ores are pyrite, chalcopy- rite, sphalerite, galena, and minerals of tetrahedrite group with quartz and barite as gangue minerals . These minerals, and also some accessory minerals, show a remarkable vertical zonal arrangement . In the case of the western ore body, of the Uchinotai-nishi deposit , the whole ore body can be divided into five zones according to the mineral assemblage . Vertical change of the mineral assemblages is shown semiquantitatively in Figure 5 and the distributions of the zones are shown in Figure 6 in a vertical section of the ore body . Zone I is characterized by a pyrite-chalcopyrite-quartz assemblage . In the.most western part of the ore body, minor amount of barite may appear in this, zone, which corresponds to the disseminated part of the ore body . Zone 2 has a simple assemblage of pyrite and chalcopyrite with considerable amounts of scricite and chlorite at the marginal parts of the ore body . Minor amounts of barite and sphalerite appear in the western part of the ore body .:This zone corresponds to the lower part of the stratiform deposit . Zone 3 includes many minerals such as barite , sphalerite , galena, minerals of tetrahedrite group (including freibergite ), pyrite, chalcopyrite, etc. Figure 5 shows a decrease in chalcopyrite and pyrite and an increase in sphlerite , galena, and minerals of tetrahedrite group in this zone . Besides the above -mentioned minerals, bornite, clectrum, argentite, stromeyerite , diaspore , and vacsite have been detected by microscopic examination in some restricted parts of this zone . t . T KUROKO DEPOSITS : KOSAKA 189 Sericite and chlorite occur also as tiny flakes along the grain boundaries of the above-mentioned minerals and, in some places, as bedded or lenticular accumula- tions (usually 10 to 30 cm thick) in the ore . At the northern part of the ore body, galena is concentrated in the uppermost part of zone 3 (up to 1 .5 cm in width), characteristically co-existing with minor amounts of clectrurn and stromcyerite . This galena concentration and also the bornite-bearing part would be character- istic enough to establish subzoncs within this zone . Zone 3 corresponds to the upper half of the stratiform deposit . Zone 4 is a bed above zone 3 characterized by barite and, in places, flour- apatite. Zone 5 is a thin quartz-hematite bed in the uppermost part of the ore body . This zone corresponds to the siliceous variety of the Kosaka- t'etsusekiei beds des- cribed in the preceding section . As sl "wn in Figure 6, zones 2 to 5 are distributed roughly prallel with each other and to the boundary plane between the ore body and the overlying rocks . There is a general tendency for an upper zone to extend wider than a lower zone . The peculiar occurrence of chimney-like siliceous ore in the central part of the Altered Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 tuff f Pyrite Chalcopyrite I re . Sphalerite Galena I Tetrahedrite• i group minerals Argentite Electrum f Hematite Quartz _ ,-, - Barite ° Apatite j Sericite Mg-chlorite Fe-chlorite =~:M-n-- Colloform texture Relict structure of pyroclastics Lower Upper Fig. 5. An example of vertical change of mineral assemblages and textures in the ore body (along line 19, Level 120 ). Amounts of the minerals are shown semi-quantitatively by width of the bars . . I r i 190 MINERAL DEPOSITS OF VOLCANIC AFFINITY 4 Akamori pumice tuff Uwamuki tuff breccia West , a East F'' , Motoyama volcanic hreccia ~l a 'l a )I A7J '0 Motoyama dacite lava dome o n 1L: Q Brecciated part of L L L, -r--- r" - t 1-j--.! fdotoyama dacite lava dome L L L ~' 4 R ti~ x Clayey part L L L L x f Zone- 5 (Quartz hematite bed A 120 )L L L L L A L J r r 1 Zone • 4 (Barite ore ) L L L L L L AL ^p ' .~ r 4 ~11~ { 4r L L L L L L L ,LA Zone-3 (Polymetallic ore) L L L L L Li ~L~" 7 100 LLL LLL 'LL4VALti'M Zorie-2 (Pyrite • chalcopyrite K0 are) L L L L L L L L Zone - 1 (Disseminated pyrite- L L L L L L L L L~L A AA' ~/ - V /f1 chalcopyrite ore) 80. LLL.LLL LLL UnzonableI oreLL~ LLLLLLLLL A I IComplex LLLLLLLLLL part ~~ 0 24m ~~ Siliceous chimney J l r---j--+ ~ 60m / Fault Fig. 6 . Section of the western ore body of the Uchinotai -nishi deposit showing the distribution of the five zones and the complex part. ore body is out of harmony with the general vertical zones as seen in Figure 6 . In this part, pyrite and chalcopyrite are disseminated in fine-grained quartz rock with sporadic amounts of barite, sphalerite, and galena . Several veinlets, 10 to 30 cm wide but not of great length, of chalcopyrite with many druses occur in the center of this chimney. The ores surrounding the chimney have various mineral i assemblages including some assemblages different from those of the above-men- tioned zones, such as pyrite-chalcopyrite-barite and sulphides-barite-quartz . To- gether the siliceous chimney and the surrounding unzonable ores are called the, complex part. With the exception of a gypsum ore body and occurrence of dolomite above zone 3 (its relation with zone 4 is unknown), the main mineral assemblages of the . eastern ore body of the Uchinotai-nishi deposit are almost the same as those of the above-mentioned western ore body . The gypsum ore body is situated in a lower horizon than that of the stratiform ore body . It consists almost entirely of gypsum, with small amounts of chlorite and sericite . Textures and Structures of the Ores Both macroscopic and microscopic features of the ores are also different accord- ing to zones divided on the basis of the mineral assemblage . The features of the two ore bodies of the Uchinotai-nishi deposit are almost similar. Macroscopically, relict structures of the explosion breccia are clearly observable in the ores of zone 1 . Sulphides occur both in the matrix and the fragments of the 4 V 200 MINERAL DEPOSITS OF VOLCANIC AFFINITY F. 0 50mt Fig. 2. Horizontal projection of No . 1 ore deposit, showing arrangement of ore bodies. NORTHWEST 1,0 =. fj .. " °n a e a ~J l .ea a e a .` . .. . . ` . ° , aa n°nnn° I1 nnann°na C :e `° . . ,. ; ` . a . ° ° 140rnL 11 X X, A A e e :C : `e a s °ae 4 Is e a e a a° n e P-17-1 rr7_1 r771 Rhyoiite Tuft breccia Tuft and Mudstone Pyrite ore Yellow ore Black ore Gypsum Metallic veinlets -- volcanic breccia lapilli tuff Fig. 3 . Geologic profile of No . I ore deposit (along A-B line in Fig . 2) . and rests on the slope of the footwall rhyolitic rocks . The metallic ore deposit is composed of several ore bodies which lie along NE-SW direction as shown in Figure 2. The average scale of the ore bodies is about 50 m x 50 m in plan . Each of - these ore bodies has an irregular, lenticular shape being overlapped and is com- posed of either massive ore or fragmental ore, or of a combination of the two . The gypsum deposit occurs in bedded form underlying the metallic ore deposit . Foot- wall rocks are sometimes silicified. and mineralized in places. Figure 3 represents the geologic profile of the No . 1 ore deposit, which shows the typical mode of occurrence of various kinds of ore . As is clearly shown in the pro- KUROKO DEPOSITS : SHAKANAI 201 file, Ryukako (pyrite ore), Oko (yellow ore), and Kuroko (black ore) are strati- fied in ascending order, and also several Kuroko ore bodies occur in layers . Syngenetic Ores One of the most significant features on mode of occurrence is that of fragmental ores, which gives us much unique information on the mode of deposition of the ores. Before proceeding with the description, let us mention some characteristics of the fragmental ores . The fragmental ores arc composed essentially of "ore fragments" and "ore matrix". Shape and size of the ore fragments vary widely . Colloform banding and compositional banding in the ore fragments can never be traced to the matrix and the arrangement of these banded structures is extremely random, which strongly ' supports the idea that the ore fragments arc exactly clastic materials . The matrix usually consists of minute particles of ore fragments and has sometimes quite similar appearance to massive ore defined in the preceding section . Within each deposit of fragmental ores, lateral and vertical size-grading of ore fragments can be recognized . Such ores can be called "graded ores" . As is clearly shown in the geologic profile, it should be noted that lateral facies change, massive ore to fragmental ore, is also observed in some ore bodies . Ore fragments in each ore body are usually composed of the same kind of ore . At the bottom of the lowest unit of ore bodies which are composed of fragmental Kuroko (black ore), however, some fragments of Oko (yellow ore) can be recog- nized. This fact strongly suggests that the Kuroko bed must have grooved the Oko bed. In the upper part of the ore deposit, tuff, mudstone, and fragmental ore alternate with each other, where mudstone and tuff are usually grooved by frag- mental. ore and are sometimes partly worn away . An imbricate structure of platy ore fragments is frequently observed in the upper portion of each fragmental ore bed . Cross-laminae are also recognized sometimes in the uppermost fine-grained portion of each fragmental ore bed . Figure 4 is a schematic sketch showing a typical mode of occurrence of a frag- mental ore bed. Figure 5 is a geologic plan showing the mode of occurrence of fragmental ores . The lateral facies change, massive ore to fragmental ore, is clearly shown in the plan. Based on some sedimentary features such as size-grading, channeling or grooving structure, and imbricate structure, the flow-direction of each ore body as shown in Figure 6 can be determined . It should be emphasized that in following flow-direction upward we can find a silicified zone with metallic veins in the foot-wall rocks. Thus, the features mentioned above strongly support the idea that fragmental Ores must have been formed by slumping or sliding of accumulated sulphide masses after and during ore deposition . We must examine massive ores in detail in order too know the primary sequence of mineral deposition. Mineral paragencsis in the ., Massive ores will be briefly discussed by the writer in another paper in this volume . J 202 MINERAL DEPOSITS OF VOLCANIC AFFINITY 1_ t •c•~ . .c n c a0 o ~ ~l G'4O~y 0,060 . 0` .ece ; C3 Q~~C1 O Mudstone 0 10cm Fig. 4. Schematic sketch showing a typical mode of occurrence of a { thin graded ore bed. Note sedimentary features such as vertical size-grading of ore fragments, imbricate structure of platy ore fragments, and channeling or grooving structure at the bottom . Silicified Zone and Epigenetic Ores In the foot-wall rocks of the metallic ore bodies, "silicified zones" with metallic mineralization in places can be recognized . Such mineralized rocks are usually called Keiko (siliceous ore) in the economic sense . In the silicified zone,, the textures of original rocks are sometimes well preserved . The chemical composition " is characterized by extremely high silica content, low alkali, and low alumina in comparison with the original rocks . Metallic veins and stockworks occur in the silicified zone in many places . Figure 7 represents their distribution superposed on the silicified zone . The metallic veins are sometimes zoned vertically ; pyrite vein, chalcopyrite vein, and sphalerite .v ..vw .~ .ey.•Si. ••r... . .w...p . ire. . ,! . ._ . ... sK . . . . Tro . N .m. .n.C.,mia . " KUROKO DEPOSITS : SHAKANAI 203 y 0 20m .. Black Yellow Pyrite Gypsum Tuff and Silicified zone ore ore ore lapilli tuff with metallic mineralization Fig. 5. Geologic plan of 115 ML . r i iI it i 0 20m ) V1 Flow direction } Flow direction of ~~ ore fragments Fig. 6 . Flow direction of Kuroko (black ore) . Small arrow marks rep- resent flow direction estimated from imbricate structure of platy ore frag- ments . . ...» ..~,, . ._ . w~ .~-, . . .,T ._ .._ ..~ .. . ._~.a ..x ...., r_ ~.~ ...- yF,..~ . .. .w_.,ua•..,,... .r,-.,...... -.u...... w..»a..a+. ..w...... r.+•.» ..s . - . x» .... .u. . ...»r...ur....,. .. ..-+....nuu+r n. . ., .e.erw. ~art .... ._.a4 a.u .. .~., .. a iK . .•. . .~ .w.x-s .a.-~.. .i-+n..a ...., N 4- 204 MINERAL DEPOSITS OF VOLCANIC AFFINITY v t / S f 0 50M Fig. 7 . Silicified zone (inside dented line) and distribution of metallic veins (cross- hatched area) . Broken line represents the outline of the ore deposit . Sphalerite '' ' ( galena +barite) Sphalerite n +'(chatcopyrite) : . Chalcopyrite ~-(Pyrite), . iL Pyrite 0 10M Fig. 8. Schematic diagram showing a typical mode of occurrence of metallic veinlets. h KUROKO DEPOSITS : SI-IAKANAI 205 vein in ascending order . Barite and galena sometimes occur at the top of the veins . A typical mode of occurrence of epigenetic mineralization is shown schematically in Figure 8 . judging from spatial relations among massive metallic ore bodies, silicified zone, and metallic veins, it is evident that original cracks and fissures in the silici- fied zone with metallic veins must have been principal feeder channels through which the ore-forming solution was supplied . CONCLUDING REMARKS The mode of occurrence of the No . I, Kuroko deposit of the Shakanai mine has been briefly described here . Among many features the writer have focussed atten- tion especially on syngenetic features in the metallic ores . Sedimentary features in the ores are summarized as follows : 1. Graded bedding of ore fragments (lateral and vertical size-grading of ore fragments) . 2. A channeling or grooving structure at the bottom of each graded-ore bed . 3. An imbricate structure of platy ore fragments within each graded-ore bed . 4. Cross lamination of fine ore fragments at the uppermost part of a graded-ore bed. 5. Lateral facies change, from massive ore to fragmental ore (massive--- .blocky -->breccia--*powdery), in an ore body. These features strongly support the idea that several occurrences of submarine sliding or slumping took place after and during the Kuroko deposition . Mode of occurrence of epigenetic ores was also briefly touched . Convincingly, the original cracks and fissures in the silicified zone with metallic veins are sugges- tive of feeder channels through which the Kuroko-forming solution was supplied. As is shown in the geologic profile (Fig. 3), it may be clear that the metallic mineralization took place somewhat after the gypsum deposit was formed . This may suggest that gypsum was not deposited from the same ore-solution from which metallic minerals were precipitated. ACKNOWLEDGEMENTS I wish to express most sincere gratitude to Professor Takeo WATANABE and Professor Tatsuo TATSUnu of the University of Tokyo, who have given me much advice and criticism on this work . Thanks are also due to Dr. Toru OTAGAKI and J)thcr ~,coT 1 og~sts at the Shal .anai mine who were kind enough to aid me during nny field survey. a,~ RECEIVED AMERICAN SMELTING AND REFINING COMPANY ROCKY MOUNTAIN EXPLORATION DIVISION EP 291972 1805 SOUTH BELLAIRE STREET. DENVER . COLORADO 80222 W U S' - - S. EJ(PL. DIV. September 26 , 1972 TELEPHONE ` 303-737 .8107 WL.K. O CT 3 1972 Mr . J .J . Collins Director of Exploration 120 Broadway New York, New York, 100 05 SANTA ROSA SOUTH Heisen Leases New Mexico Dear Sir: On Thursday, September 21, Mr . Hoskins and I met Mr . Charles Heisen in Albuquerque, on our way to Iron Mountain, at Mr . Heisen's request . Mr . Heisen has a sound theoretical knowledge of roll fronts, and was a co-worker of Rackley and Shockey when they wrote their authori- tative papers on the subject . He has picked up about 35, 000 acres of state leases, scattered along a north-south strip east of the Pecos River, from approximately Santa Rosa, New Mexico to east of Roswell, New Mexico, in a strip about 90 miles long . He has drawn an approximate position of an oxide-sulfide contact in the Santa Rosa sandstone, a unit about 120 feet thick, based on examining oil well cuttings in holes spaced about 10 miles apart . In cuttings on the oxide side of the front, sparse malachite occurs . Copper, lead, etc . In pyrite on the high pyrite side of this front are quite anomalous . Mr . Heisen wants essentially $200, 000 as advance royalty for his efforts, plus a one percent carried interest . September 26, 19 72 page 2 Neither Mr. Hoskins nor myself regards the Santa Rosa as an out- standing potential copper host, although the Pintada and Stauber mines both occur at the north end of Heisen ' s area, and another approximately 750,000 tons at .7 % Cu has apparently been drilled out about 15 miles southwest of the Stauber . I told Mr . Heisen that it was my opinion that this was too risky a business for us in its present state, but if he had some holes in ore, we might then look at the proposition more favorably . Mr . Heisen believes that he will have no trouble disposing of the property on about the terms outlined and believes that Conoco will probably accept the deal . Conoco has a number of geologists in Albuquerque working on stratiform coppers , concerned with worldwide occurrences . They are also establishing a research team in Ponca City, in their Research 'Department , concerned solely with stratiform coppers . They have done some drilling in New Mexico in occurrences we would regard as essentially worthless . In the light of all this, it is possible that Conoco may accept such a proposition , although it seems to us that Heisen is expecting $ 200, 000 for no work except obtaining some state leases, part of which are misplaced . Very truly yours, Steph n Von Fay cc: JHC /°~ WLK,/ S-rju 1vaI011 .:n C01'L1at S i!IX IbI:S• IN '1'111 PRI Ct 11'I' 11 BELT '.~UFE,~'ROUP, NOUTiIERN iaAJ'_O AND N01 :1'iWESTERN NON'L%NA, U .S .A . )3y' Alien Tom . Claik 01DUCiJC1d ! ~ r 3M1, The stratabound copper sulfide deposits described in this report occur locally in a zone approaii,ntoly 120 miles long and 1{0 miles wide that extends south-southeast . frorl southern British Colu:;ibia along the Idaho-Montana border to Licar ti.e Coeur d'Alene mining district , Idal::, (Fig . 1) . _ . t i'ANiA~'r_ y . J `l E C 1 NTANA ' frfit j NT • i I0 11-1" . ' \ : stern l nit cz Figure 1 . G ::t'cra l ized distl'i. buticn o ': reI_t Supecgroup rocks i11 Une w ita Les and copper sulfide Bell- . 1. t. e . +++~s, . T ~*1 Much of the data on, individual deposits is confidential. m tt:crial of several mining coiapanics . . The purpose of this paper, therefore, will be to discuss the gen- eral distribution, mineralogy, paragenesis, zonation and stratigraphic controls-on copper sulfide distribution . Copper sulf ides occur locally in the Precambrian Belt Super-group o f northern Idaho and western Montana and in the stratigraphically equivalent Purcell series of southern/British Columbia . The Belt Supergroup and Purcell Series are a thick sequence of shallow water marine deposits that crop out over an area in excess of 50,000 square miles (Fig . 1) and attain a thickness of over 40,000 feet . GEOLOGY ' Belt Supergroup - The najor SuLCIi-visions o~ tic i~elt•SuperSroup !ere defined by Paiis'-e and Calkii,s (1908, p . 23) and Shenon and acConnel (1939, p . 3) . The formations from oldest to - youngest are the Prichard, the Burke, the Revett, the St . Regis, the vIallace, and thel Striped Peak . ---~ Detailed descriptions of Belt Supergroup rocks are given in numerous other report • . ._~ ~L~ . . ' `' ` ' {t~+ -i-*+ cT= rf°e ^'~+ to descriptions by Ha rrison and Jobin (1963) for the northern portion'of the area and by Hobbs and others (1965) for the southern part of the area . t' According to Harrison and Grimes (in press), rocks of the Belt Supergroup range l from .::metamorphosed to greenschist facies . The .Belt Supergroup ranges in age-from 900 million years to more than 1,300 million years (Obradovich and Petermar., 1.968, p . 746) . Lithostratigraphic equiva- lents of the Belt formations in which the copper sulf i•de deposits occur were deposited at about 1,100 m .y . and 1,300 in .y . (Obradovich and Peterman, 1968, p . 746) . 2 , ' , ,Structure , The m tjor structur~il elements in the study area are northwest-southeast trendi r• high- .angle faults,s r.iost of which have' a large component of strike-slip displacemcent . The area is bounded on the west by the Purcell Trench and on the south by the Osburn and associated faults . . The major folds of the area are large-scale open synclines (Fig . 2)-and anti-- clines . ocally, recumbent isoclinal folds are formed IT- Figure 2 . Contact bet ween Revett' Formation (TCR) and overlying St . . Regis Formation (PESr) exposed in broad open syncline . . Sulfides in the Belt Surergroup ( , ' Stratabound copper sulfide occurrences have been observed in- all 'of the forma- tions of the Belt Supergroup . However, the major concentrations of possible economic importance that I have seen are in only the Revett Formation . Locally significant occurrences can be found in the overlying St . Regis and underlying Burke Formations . Regardless of the formation in which the copper sulfides occur, they are charac- teristically confined to the quartzite and siltite members of the formation and are most abundant in the coarser phases of these members . The following discussion will deal primarily with sulfides in the Revett Forma- tion . However, the general . features are applicable to copper sulfide occurrences in the other formations . ' c Formation The Rcvett formation has been measured in several. areas and shows a wide raiig -~ in fthickness . In the Coeu"rr d'Alene mining district the formation ranges from 1,200 S 4 to 3,400 feet (Hobbs and others, 1965, p . 37) . Harrison and others (1963, p . K-11) measured a thickness of approximately 2,000 feet in the Pend Oreille area and I have measured sections ranging from approximately 300 feet to more than 4,000 feet in 1western Montana . "' In theVPend Oreillcjarea (Harrison and 3obin 1963 , p .K-11)land near, Tro y,] Montana; the Revett Formation can be divided into three units of massive quartzite ; one the base, another near the middle , and the third near the top of the formation . . Southward from these exposures toward the Cocur d`Alene district the Revett appeafls to thicken and become an .intercalated sequence-of quartzite members and argillitic + artzi te and siltite. members . I D The Revett Formation is typically crossbedded (Fig . 3) on a scale x-ahich ranges ~ ._ from microscopic to large foreset beds over 4 feet high . The large-scale cross- bedding , essentially uniform direction of dip , shallow water features, and internal i sedimentary structures indicate a near shore environment and suggest that much of t the Rcvett is composed of beach and bar deposits . - ~M~ JCL _..L:''... • Figure 3 . 2iassive crossbe :dded Revett quartzite showing bloct:y fracture . 4 ~,ocall.y°the Revctt is calcareous or dolomitic . Many of the carbonate-rich . i tzite members appear to be the host rock for the copper sulfides . The quartzite members of the Rcvett Formation are remarkably uniform in mineral composition . Table 1 contrasts the modes of Revctt quartzites in the Pend Oreille rea (ltarrison and Can1bell, 1963, p . 1417) with mineralized Revett quartzites from .rithin the study area . TABLE 1 . Average modes in volume percent of Revett quartzites Albite-- K- Area 1 Quartz ol.i oc].ase f eldspar Sericite Chlorite Biot ite Pend Oreille 70 15 7 6 - ._Tr I Mineral Belt 70 13 3 4 1 2 Calcite Dolomite ' Sulfide Pend Oreille 1 0 0 Mineral belt 4 0 3 Units of arail1itic quartzite and uartzitic argillite vary in co~iposition from • the quartzites primarily in containing, more sericite and less plagioclase and quartz . F _ The quartzites generally have an equi .granular granoblastic texture with weakly a sutured borders between mineral grains . STRATABOUNTD COPPER SULFIDE, OCCURRENCES -• Mineralogy of Occurrences The surface expression of the copper . sulfide occurrences is generally very subtle- Surfieial leaching and oxidation has normally produced a "rind" on mineralized quart- zite which ranges in thickness from 1/4 inch to more than 1 foot . The leached and oxidized zone characteristically contains small amounts of malachite, azurite, brochan- tite, goethite, and jarosite . In .areas where galena is common, minor amounts of cerrusite have been detected . The oxidation products generally occur only on fracture surfaces and the exposed outcrop surfaces show little or no evidence of mineralizatior._ The principal copper sulfide mineralogy of most of the stratabound'occurrences 3 is remarkably similar . In order, of decreasing abundance, the sufides are . bornite, ' chal.cocite, chalcopyrite, covellite, tetrahudrite(?) and d i cinite(?) . 5 e In addition to the mineral listed above, galena, native silver, and native copper t,1ve been observed locally and spectrographic analyses indicate a minor amount of gold ( ;.08' ppm) Copper Sulfide Di .strib{ition The copper sulfides occur as disseminations, discrete blebs, as bedding plane concentrations, and, where locally remobilized, as fracture filling veinlets . The Q { ~ SLID most c moron occurrence of sulfide . is as a dissemination throughout the quartzite host (Fig . 4) . The primary disseminated mineral is bornite which occurs as individ- ual platy grains or as cusp-shaped grains which appearr to have corroded and replaced quartz and carbonate grains . The average grain size of the bornite is 0 .08 mm . and 'size ranges from a microscopic dust to 0 .3 mm . 'L'arge blebs of sulfide occur locally . Most of-the blebs are polymineralic . The most complex have a central core of chalcopyrite which is surrounded by bornite and chalcocite (Fig . 5) . The most common type of bleb has a central core of bornite t replaced by chalcocite (Fig . 6) . aono-mineralic plebs composed of either chaicopyritc;, bornite, chalcocite, or galena occur locally but constitute less than ?0`'percent of the total sulfide occurrence . Sulfide blebs range from 0 .2 cm . to over cm . with , an- average diameter of 3 .5 cm . ` '' Polished section studies show that the blebs are rarely all sulfide and gener-- ally contain 30 to 50 percent corroded quartz grains of the host rock (Fig . ;) . Throughout the occurrence .- .^ .copper sulfides were observed in thin bedding plane concentrations-(Fig . 8) . Some. of the individual sulfide laminae have been followed for several tens of feet in the outcrop . Polished section study shows that such occurrences are generally associated with carbonate-rich, coarse- grained clastic phases of the quartzite. . Locally, copper sulfides occur as fracture-filling veinlets . 0ccurrenccs of this type are most coi:mon near major fault zones or along -miror s?icn r planes . 6 'i .01 w Figure 4 . Disseminated'bornite and chalcocite Figure 5 . Complex sulfide bleb in massive quart- in in massive Revett quartzite ." zite . d = chalcopyrite, b= bornite, b-c (bornite and chalcocitc) c = chalcocite . a :7 t •T...... '. :...t... :. .. . «.- . . .•'' ...... •:• .r2.u...... w: .1 .i•..e .,.» .a .'.. .» Figure 6 . Complex sulfide bleb of bornite (b) Figure 7 . Photomicrograph of a complex sulfide ' by chalcocite (c) replaced . bleb with included quartz .grains . Q - .quartz, b - bornite,:•c = chalco- cite, anrd .d = chalcopyrite . Figure S . •Thinly laminated argillaceous quartzite showing bedding plane concentra- tion tion of sulfides . d = chalcopyrite, b = bornite . Sulfides within an individual quartzite bed generally display a regular pattern of distribution . The largest concentration of sulfides occurs at the base of the bed at the contact with the underlying argillite-rich unit . The contact is commonly gradational over several inches . Above the basal sulfide-bearing zone there is generally a zone of lesser concentration which is in turn overlain by .a second sulfide-rich zone of comparable thickness to the basal zone . The two rich. zones and intervening low grade zone generally occur in the basal two-thirds of the bed . suifidey 1Thc upper one-third of the b`d contains only a minor amount of disseminated Controls of S ul fide Distribution The distribution of sulfides within the individual units show definite physical controls, primarily grain size and sedimentary structures . The grain size of the disseminated topper sulfide minerals, primarily bornite and chalcopyrite, generally varies directly with the Srain'size of the enclosing host rock . The direct relation is particular ly striking when the grain sizes of argillaceous units and quartzite units of the same member are compared .The grain .ize also appears to control the richer portions of the mineralized mer.-Mers . Almost .'ithout an exception, the coarser grained phases contain the greatest amount of sulfide minerali..atiori . 8 structures and sulfide distribution are very closely related . a -,,Ific examples ~5f this close association ire : 1, Graded bedding - Sulfide minerals are commonly oncentrated in the basal 4 . r portion of graded beds . Associated with the concentration of sulfides is .a large concentration of heavy minerals, particularly zircon, tourmaline, and rutile . 2 . Crossbedding - Crossbcddcd sequences of the Revett Formation appear to be the. most. favorable horizons fo .r sulfide concentrations . The sulfides are d'issemin- ated throughout the sequences but show a : strong preferential concentration near the basal zone of individual beds (Fig . 9) . __ Figure 9 . Crossbedded Revett quartzite and bornite . b = bornite . 3 . Scour and cut-and-fill structures - Sulfide concentrations are very co .nmon in ther basal portion of scour and cut-arrd-fill structures . The sulfide concentration is also higher throughout the fill material than in the surrounding country rock . 4 . Bedding controls i +e 3- . From the largest to the smallest scale the sulfide concentrations are conformable with bedding (Fig . 8) and associated with' the coarse-grained quartzite units . Lateral continuity with an individual bed over several hundreds of feet is not uncormmnon . 9 ' YL1raienesis f The paragenc' 1cc sequence given in Table •2 was based on polished 'section studies of samples collected throughout the belt . Not all of the minerals are present in _any single occurrencef1. The sequence represents a compilation of relations observed 1. la -J TABLE 2 . Decreasing Age C ' I Primary , Secondary' Remobilized Secondary hergene Chalcopyrite Galena .. .• . Bornite Chalcocite Covellite Tetrahedrite(?) Digenite(?) Native-Ag Native Cu ' Oxides t-Q "In ire larger grains (i'ig .*10 ) a central core of chalcopyrite is commonly sur- and the entire chalcopyrite and bornite grain has a thin outer rounded by bornite r &, A zone of chalcocite which`1contain ` small particles --of - native -silver . Chalcocite also occurs along fractures that extend through the bornite and chalcopyrite core . . •. Figure 10 . Chalcopyrite (d) core replaced by bornite (b) and chalcocite ( c),replac- ing both minerals along margins and vein] .ets . Native silver (Ag) occurs in bornite . • 10 - • Chalcocite grains commonly shot,, a needle-like intergrowth of cove] .1ite . Covel- a` 1j,Cc is most con'.:;lnn in areas where chalcocitc is in cont act with elastic ,,rains of quartz .r Chalcocite replacement of bornite and chalcopyrite also i s most common around quartz grains that have been included in the sulfides . ally, particularly near fault zones and minor shears, thin veinlets of chalcopyrite and bornite cut across all of the sequences described previously and are probably related to local remohilization associated' with structural deformation . The secondary alteration is similar to that described above for the primary sulfides . Tetrahedrite(?) and digenite(?) have been identified tentatively in three speci- mens and without exception occur at the contact between bornite and chalcocite . Their exact paragentic relations are unknown but probably close to that shown in Table . native silver occurs as inclusions in chalcocite that surrounds I nite . The silver is believed to be derived from the bornite during secondary enrichment . Native copper, malachite, azurite, brochantite, goethite, jarosite, .and cerus- site are commonly found in the leached and oxidized surface outcrops and 'are the youngest minerals observed in the deposits . Origin of Sulfide Bleb s and Bedding Plana Concentrations ' e Large concentrations of sulfides in the form of blebs and bedding plane concen- trations are particularly important in interpreting the distribution of sulfides and, the processes that have affected the occurrences . Detailed polished section study and spectrochetrtical analyses of whole rock show that the concentration of sulfides into blebs and along bedding planes are accompanied by depiction of sulfides from the surrounding rock (Fig . 11) . Similar depletion is also noted along small quartz-bornite veinlets which occur locally . Therefore, these features are a modification of the pre-existing disseminated sulfide o deposit . The si-TficaT, of this will be discussed under the heading of Rc-nc-s~s of deposits . ' ' 11 . i Figure'll .• Bedding plane concentration formed by depletion of sulfides Iran host rock . 'Depletion zone shown by dashed lines . Zonation of Occurrences •. = The zonal arrangement of sulfides within individual ore bodies is incompletely ! , known because of lack of adequate exploration . .it a general zonation_ has been observed by the author in a deposit near Troy, Montana . Known deposits are elongate in shape with a long dia :ersion commonly 4 to 5 S C E ° r deposits . The thickness of an individual mineral zone varies considerably depending - on thickness of the host quartzite and position within the ore body (Fig . 12) . Ba rren Zcne . ., Pyrite Zone Galena-7vritiL- Zone Chalcopyri t~•-=ornire-valena - Zone Bnrnitc-Chalcoc:ite :ono Chalcop yr ! tc'-• :.'O1-n ti'• 'h ; I coc 1 to one c i1CCr~\'1' .t -one Zonation of copper-sulfide occurrence . 12 tempnrM rtIC zonation (Fig . 12) appears to be composed of a series of over ; appi.n; zones PG .-.-,.~ P t t,~ch grade from-a barren periphery inward s~ throu gh an pyrit e zone characterizedRby framboidal pyrite t ran~;jug in cii. ;t,wter from 1 i-.wi . to o*," r__ ,}z, The pyritic- zone is underlain by a galena rich zone which ranges in thickness from 5 to 10 feet . Underlying the galena rich zone and occurring primarily near the lateral margins of the deposits is a chalcopyrite -bornite rich zone which up.derl .ies and overlies a central core of bornite and chalcoci .te . ,,''T}iey ciialcopyrite-bornite rich zone ranges in thickness from 10 to 20 feet Bo~ rn_ te-chalcocite mineraliza- tion forms the core of the mineralized zone and ranges in thickness from 10 to 14 feet Beneath the ore body minor amounts of disseminated chalcopyrite occur through- out the arbillite and quartzite but rarely exceeds 0 .5 percent (Fig . 12) . The barren and pyritic zones which surround the deposit appear to coincide with facies changes in the quartzite units where the quartzites grade laterally into argillaccous quartzite . The change also -is i:eflcctcd by a decrease in the car- bonate content of the barren and .pyritic rocks and by a marked decrease in the size and magnitude of crossbeddin~- . AGE, OF OCCURRENCES 0'Vf f hP ~ca~ R . E . Zartman of the U .S . Geological Survey has done extensive'lead isotope dating of deposits within the belt described in this paper and in adjacent areas of northern Idaho and northwestern Montana . According to Zartman (personal con- munica;tion) two distinct families of lead isotopes have been identified in ore deposits of northern Idaho and northwestern Montana ; he interprets one family as being "Laramide" in age and the other as being Precambrian in age, probably about 1,100 ri .y . to 1,500 m .y . old . Lead isotopes from ores within the described zone CAI of Ravalli aup concentrations are all Precambrian . ' 13 . ( believe that the deposits are closely related to sedimentation of the Revett , d- tion . The following features indicate that the copper sulfid es in the Revett Forma- -tion were formed essentially contemporaneous with the enclosing sediments : 1 . The distribution in an elongate narrow belt of sedimentation . 2 . The distribution of sulfide concentrations in a narrow time interval of Belt Superoup sedimentation . 3 . Essentially the same radiometric ages of sediments and sulfides . 4 . Close association and control of sulfide distribution by sedimentary struc-c tures and processes . 5 . Presence of sulfide material closely resembling clastic grains of sulfide . 6 . Late stage formation of blebs ; bedding-plane concentrates and veinlets formed by migration and resultant depletion of pre-existing sulfides . 7 . Absence of regionally associated structures and intrusions that might have ' been the source of mineralizing solutions . ' 4 14 RErI:R1:I:CI:S CITED Harrison, J . E . ,'and Campbell, A . B•, 1963, Correlations and problems in-Belt 5 Series stratigraphy, northern Idaho and western Montana : Geol . Soc . America n Bull ., v . 74, p . 1413-1428 . Harrison, J . E ., and Jobin, D . A., 1963, Geology of the Clark Fork quadrangle, Idaho-Montana : U .S . Geol . Survey Bull . .1141-K, p . .Kl-K39 . Hobbs, W . S ., Griggs, A . B ., Wallace, R . E ., and Campbell, A . B ., 1965, Geology of the Coeur d'Alene•district, Shoshone County, Idaho : U .S . Geol . Survey Prof . Paper 478, 139 p . Obradovich, J . D ., and Peterman, Z . E ., 1968, Geochronology of the Belt Series, Montana : Canadian Jour . Earth Sciences, v . 5, no . 3,•pt . 2, p . 737"747 . Ransome, F . L ., and Calkins, F . C ., 1908, Geology and ore deposits of the Coeur d'Aleine district, 'Idaho : U .S . Geol . Survey Prof . Paper 62, 203 p .' Shenon, P . J ., and McConnel, R . H ., 1939, The Silver Belt of the Coeur d'Alene district, Idaho : 'Idaho Bur . Mines and Geology Pa :nph . 50, 8 p . - 15 -T 17 7 JHC FORM SL- 7035-A i M 4-70 WKEEP" THIS ON TOP File No . From to Subject : STRAT IFORM COPPER DEPOSITS AND GEOCHEMISTRY OF ARSENIC, ANTIMONY, COBALT AND NICKEL 134. E. K11, t.. GE 5,11 October 2O 1966 uctioLt a brief treatment o such a large and complex subj ut. it is o; ssib t to treat a fir major topics m generalizations which rcm the risk of ` s plifi.- cationQ Three major topics seem pertinent to this disonesioni : L WW* s a stratifo m deposit? 2. What •9 the vOM is in which strat 'o copper de errs occur; 3 . What is axe probable made of origin for such deposits? In addition,, s me of the best kno n e x'atifo . copper deposits are listed ., time pe att g, theme might be discuss b .ef . s1h 61 As Is unfortunately the case with many geological teams, no rigid definition exists for stratifo n deposits . general, one t irks of ore found in sedimentary a ss,, U,)U . confinedd to a given ho ur ; ho ever,, there are sere specific cnara to stics which distinguish, t, 3y stratifo deposits 9, other strata-bound deposi s , F bard acid f col ni (1962v P. 231-246) have point out, 1. Stratiform deposits occur sedimentary crocks o their metamorphic derivatives 2 Ideally, stn air-i o de s .ts occur within a single continuous horizon throughout a sedimentary basin- theoretically ., they disappear only where the ore- bearing hor son does not occur (in areas of non-deposition), However, natural t ati o de m s mqr have gaps or modification the ne .nation because of several other factors ., To summarize :, strat form deposits must be concordant r the host rock, 3 . There are two subtypes of stet o deposits : (a) dissem-inated stra ifo deposits where the grain size of the ore is often very similar to that of the cowry rock (aggregates may, appear to be large crystals) or (b) stratifomt fissure depos ten where the ore fills cavities (joints, shears, etc .) and the grain size of the one I independent of that of the host r ckm Generally, the second t is found with the first and is subordinate it 4. In strat "oa deposits,. mineralizat on usual Lo s with the sedimentary structures ; a.. Z. v in the hollows of ripple marks . Also$ the a neralization may be related to the fineness of the b ding ; , grads increases with finer beddlln& Another type of strata-bond deposit that should be me boned i s the pes onoorda t variety, as on :any distinguished W. L. l`unc'h (1959), for it represents a distinct type of mineral deposit ., different from truly stra ifomn deposits. Pensco eor ant deposits are atrati 'o on a regional scale ; but, are discontinuous on a waller scale and more or leas unto o able to the o. bearing cent rock. The miner ization does no always appear to be a normal constituent of the country rock ., but often agpeo be :trsneoua,. introduced from outside the o ntry roc: . Pene onco d t deposits are ware often confined to a given fades,, not a given horizon ; they tend to occur pa se- :h n 1s In addition., they may cut across sedJ>u ntaxr structures such as cross bsdd . . Ea E patridc . 0 E 3 Gt, of ~0o t deposits are the "red-bed" copper deposito the Colorado Plateau ur . de sjtj. Strat orm deposits are typified by the KuPf efer of d Gii, the None Shale, at White Fine Michigan, or the copper deposits of the Lower Roan S t in N'o h 1iode ia.Q on is p stratifo deposits in general may be more attractive than p or - cor d ant types,, for only high-value ores such an gold ., uranium, vanadium, etc, are apt to be econ do in penecmuc ord t deposits because of their discontinuous nature,) whereas, the more widespread ., cone .uo strat 'orio deposits array be economic for marginal grade ores p c u; a, mentioned,, strat o copper deposits are confined to sod ent rocks or to their met ortics d rivativda, fu exmore,, they seem to be confined to a rather rest steed type of d post ionsi emdroamt . It .a possible to make the N -lowing generalizations : 10 Most etrat 'o deposits occur r continuous _a'-jne scd : m tw or in Sedim z rrpr stinting m ins transgressions into rot ct . ba. ,rh represented strongly Strat .foa°n. deposits f-requentiy occur in &Tr or bla € iante r°i chh . .: organic Mater ; . ;~ they are :eau i reducing euvie o i tints. I, 8tr bifo:€ deposits genes a y Occur In se a is char acter .stie of w aj a id s aces and are Often associated i -Wa rltes . Copper deposits are usually lacking in sod to which are indicative f cold climates ; t : .ites . . 4 8tr t..foyim copper deposits appear to have a d rite spatial r .ation ,p to palcorc .ifs ffi .,t rough tratlfo deposits is genera . Appear -to represent m t - ? o shsflo ater , e ots (neritiu?) to transition--I a im as (sguon .?),f copper concentrations seen to be highest further away femm old bascment highs, h-ere s lead-sine deposits appear closer to pa' 1i s . 5 , .a y e s do not seem to be favorable sites for otratiova . deposits ; this is probably y because of several factors ; 2 reefs present h r " a .' of relatively :° ater water turbulence and higher Ex conditions . 5.. Stratio copper deposits appear to be r+ at a special li tholog c sequence ; seer . works $ especially L mb ^d and Ul (1960 and called attention- to this £a . ; general, pper mineralizatio occurs at the b ginnin; of a tr sgressive trend which a l,i a long sequence of Continental deposits usually y conglomerates and a .i aton , The ore tends to be .I concentrated as gillaceous (shply) sed eats ., but is o found 3 dol ,'sos and -ndstones as well Copper I usual local .zed around osoi l i ting trans assi ve sequences (tee to non- . d back), b~. tt the continental sediments usually are barren on of m .neralization mere the tren reasive cycle Is repeatod, copper may be deposited in the m rs ?e (or trance .iona1?) sod tint , however, the copper concentration generally seems, to be highest in the basal pert of the fir t t xis- 7. Strat o deposits often display distinct zon ing of gaols nereuisutjon , which appears to be Felt to old shore ti e trends and iu Some cases, to old, cu rent di otione a g nerals mines. zones tend to parallel ancient t shorelines for 101,:28 distances, The width of the zones varies great y, but in general, widths arc . much leas tha n the le gLh ; width t s' are g ° atest w oxe rodent.re off=-- slopes tiara *gentle. li'. n ade. . . l zed ii i o. .o ff ".ty sequence C 7 e• ac i. i . s.•. s ;; of _1 .~i.r .~°~~s, ir .~ . _E i~. :11i5 11[p or .4ex:.~ a`%~~.:+ (not 1,~ . : .iaa1c) ={t ~ ~~`{~ ~~ . 1418 - 01 - 's"ss .' .'J ac"•ndstoy c, KNOW na . iRa w4;?E7~5l~d~kiv e dw 1 CA:- `;3h L y :3afld j° SKY, doic t@ Aeolian Sandstonco continental eedimento Chuglomerates .FV1 7.i1Vlthed6+ ~ea Copper miner GL,!l. za n ,gro come deposits, 4 E ode :.lxi CopA erle.OU, (after Ge y ick, NO) . .,.,,,„~ 4 .~ __..~ `a •j°s ~k1 °1 1~,5 k 11i 11tt`1tl114i 1t1LIt14ti6\ 6!1\1!1 \l( ~",•' ._ ~_\\ S t S.'.,,t •, S t t. t E . t a t F 'r t t °•-°-'- s ,1 1 t • 1 ~, i t- r S ,\ s S 1 t~ t~ 1 t s., ~,, ...t .;.,t s~ r/' jxr'" t,, . /~i j'F f~F' %/'l , CGs f t sex s e 3 }Sl tl ~1 11`t ;11111 i~` ~t i fr f }r. a Ja d ~F : ,.J Pyrite TK t.ir } y' '.. to BC9 .v'n 1t4s s .Lt TrC:.a u:}g .1 es a ..1 ..eL a r)-ya . sICO ',JT1l. . La n~:~ ~Y . ew& .s 0 .Bi B® K .pat . GE 513 Thickness of zones apparently dependent upon many factors ., but the major g a. meters appear to b e maintenance of cost depositio conditions and metal supply over a long time. A general zoning sequence has been reported £ Northern Rhodesian d sits (Garliek 1961, p, 160) : barren sa1: ent, € ss aced chaleocite, bomite, oha1oo t 9 and pyrites occuring the general direction of current flow and facies change f near shore to off eed entae However, there is no rigid relationship between sulfide zoning and + taxy t and gurthe ore, mineral- izaticn may cease In a given horizon although there is no change in tholog Sulfide zones may overlap one another in different tu stratigraphio sequences, advancing or retreat : in transgressivo or regressive phases . 8. generals strabi om deposits tend to have high sodium, al p. magnesium., and perhaps:-: boron, contents, These facts are the reflection of the geoch st of the be in which stratifornt deposits occur. 9. In sbtat oxn deposits ., the relationship between tectoni ore csncentz'ation varies with individual deposits . Faults may modify the deposits, but they a formed independently y of shear . mechanisms. St tifmrm deposits am often found 'in folded sediments aid . may have been subjected to v€ ring degrees of metamorphism . Me morph sm may also affect ore minerals, causing them to cs ba lize or even move about; l s: into fissures in or around the ore horizon which tends to obscure the original sedimentary features* big eroded terranes ., ore horizons may' be preserved In . synclines., but ore concentration is general independent of forge 10® ratifo deposits usually are not the o minera ization writhin . a- 'live, province ; generally tae are cheer deposits which m be older or younger' .:'., ' .Pwe- conco a t deposits are often associated with ratitonn deposits, How, er, ' mineralizat ion .apparent has direct relationship to the strata fo ra deposits, summary tratifo copper deposits generally occur : n rather limited enbs characterized by -tr asg ssive marine sediments laid d in reducing conditions Wider a wa=, and ,imAe4 i generally have a definite rela io hip to ancient ehor4 fines and paleore .efe. . such that ore horizons vary in mineral t and grade with p i ty to shallower area of. deposibion, The major processes affecting g st orm dafpo~,s appear to be sue .i aentary, although subsequent tectoniem and metamo~m m mod the original sedimentary features of the deposit &qjLble Redo of ftigin The origin m etratifo deposits in general has been the cause for much -sp ation and the source o ' € .a conbrove y The question is not as academic as it Might- e g for needless to says theories of ore genesis largely influnce exploration p gram , The controversy.,-of course, is whether or not stratifo deposits a to b..• O ider d s g r: m o o epige e ; v s ore has deposited du ing e a processes that created the host rook or has been Introduced (by various' m ani m) f sources external to the host rocks after it was consoiidatede B® E patri GE 533 More recent work by 0€ e1a (1960) and others has demonstrated that the relative solubiities of qxa 'ides under given conditions largely control the precipitation of sulfides under ,specific mi-ni conditions (stability fields)a The ove U.-*- .c process may outlined follows *- 1. Metal :fix . suspension (colloidal?) and solution carried by rivers to a sediments basin, along with other materials . 2, the near-shore zone$ sandy material is deposited ., but because of cater turbulence e • d . consequent high S? (oxides conditions) no sulfides are deposited, During ccnpaction and di enesis of these sediments,, with subsequent reducing conditions .,,- acme per to may fozza, 3 . At the, edge of the dated zone,, s o very minor amounts of urami-to and t tic ides., along with molybdenum sulfide may be de sited$ 4. sum hat deeper water and in more reducing conditions, copper is pz d inan' . deposited,, 5a Farther offshore, there is a zone where rough equal o of copper and iron are . p eipitat $ 6. is the interior of the b sin , cropper is deficient (b deposited on shore) and iron is the Predominant .precipitate These metal .'sulfide p ipitates were p babl o g is a colloidal fo . and were diluted by 'v; i ors of d or sand, The actual minerals a . oeitsg r n E. mpat ek 0 0 X 513 b ite etc, probably foam during diagenesIs or later metes zo i . Nom , a Co The Northern odesi pperb t rune al the divide separates the drainages between the bias and Atlantic Doe a . Along with the neighbor Belgian Comp it fo s a metaog ,o p ie p ates 6 3 ete long and 400 ki ete wide The copper min zation occurs near the base of the Ka a it s ( es 't ) the so-called °"Ore Formation",, wUch io comprised of a varying B olo averages about 14 motors thi m The ore horlson con sts e f f to m -grimed, Sometimes' shaly a Ua eo s tst which may grade locally into black shales Thin beds or la ae of dolomite are almost a w present. The strata her the ore horizon consists of generally light-colored sands and conglomerates with some °g .aceous members, The strata above the ore horizon are alternating gray, medi -grained$ gill eous qu zites and lighter colored m ices rs ed s sto es Aeolian cross-bedding occur s in the sandetones below the o horizon, Traces of copper have been found nearly € . the members of the Lower Kat-' : atemp bit they are economically concentrated only in the Ore Fo ation and . + at y adjacent beds. pppr suMd are the major ore, maw as ohacopyrte with iO bornite0 Me ;ncrp-uzation is disc t the host rook as gates of graw or as thin vel-nIets along the bedding or o ss-eutti veinlets with quartz and 'qAr ego The copper-bearing strata at gaits P occur mainly In the lower 20 to 25 feet of the Nonesuch eh em This copper zone is divided into four units ( ascending order) coed the lower sandstone (the top bad of the Copper Harbor coz;ics erate), the ping shale, the upper sandstones and the upper shale . lic sedimentation Is i cated by very similar lithologic sequences : the upper and parting sbales, • GE; 5 I= t :2 tile coppert' €;F °tr"a 1 the u( e end pce::"bir?r, @hel, r. . xe-pt r I a Sma area n upper end lower SwIdston ts" ~ ear the l-?i2 j te Pine 3 e.11 ~ ishe u^ ,t ?,u abimdWit ' n the n s e .~ 4•e ~eg• g upper C~3~3c"7~34° c " 7 ~3 4°..{ {` `` €$~C`i.°~~:~:~:a:a~ ::. .`five ~a i .~f.'~G~:'i3x~~a ~.a~'£.-'" in c.itC3~d1'k'v.~ z!,"*~'G~~, u~.,4.k"~.Fr ~I to 3 c w`~ 1 5, t y l .. .~ :'sCaiYr' i , ~3 34~• , nx'e a s Oc w~ .~£s n ~fi:~.'Ft ; ,. ~3G t.~ a.~s. 'te°.. ~a a-a-7.0 u .c.~t~, ~ ...~..3t, ~.>L'.~` : where, the, o are, thick 3 the thickest depresuios'2ed Ccp .:t r :`ontont 'm shalce ?:l ;'c razes as cancd content .klf a"~'acee;~ t4le White P ' e lo c al cc rurr'enc cs Of copp or in t he 7e' tie 23e beds around in fault of i • exqp1ai.ned as 't~`.3~ as' G :3~ h. r of_~3, t.~.:Sc ~a+,rf. th o°:. ....<. . `~ranspvorbv '~~~•,- ®ion ,~+fry. the f'e;u.t UP tat", dip f . ~ ~'1 aE#, ver the dist0i-buti.o pox iOaldle s andatone to Mlle crest of c -i jacent~ ~1 Er£3 ~~ of of copper in ''vs?~~ ~ .li'e..,:~.E"l~.., and 11_.~~2G' r. f~;,..~"~, .~....e.a ~"~, `~,}~•p ~:crs to be, c apletely independentt conbxv of ore de 1poe:1-tion 1 `"tr t8 r ^ J!"mu .t ai zmd rock penneal):L .it'y the overall in the area -1-1, li .°•:'olegin m rd et rat igrap$ a r . • GE ,1, Davideon, C F,, 1965, A s i .e mode o: origin o °strata, copper ores : Econ .,Geol vol . 6C0, Kb,, 5 P. 942-953. Da . .1 G 1i 1954,7 The OMI grin of h ow, Antelope cop° e!° deposit o Northo,n odeeia : Evan, vol . 49, No 6, p., 575-W--, Do ne s T, t, eR. 50, ` he Kupf orahiefer mid the ae' No c iat1" . load-z no n is3eS iza .ion the Fei niam of Si1eni a ., Germany, and J uaawad : XVII= internat. GeoL Co o . part 7, sects F,, p,~ 340.352, London . ,;'inch$ W L,, 1959: Peneconxcord t uran depoe tew A proposed tcjg-,, : E Gon4 Goal,, vol. 54, No,, 3, p 944-9146* Gar1 ek, W, G. . 96:1 1•Jend ookh a he Orb 1er ea an Copporbelta W` a o 1o and Sons, I iC , ,, London Garrolle, R, M." 1960, tdneralI .u . ibria at low t 1pex'ature and pressure : H arper, N ew Y.o .r4C . Liza-kes,- 11 . EQ a nd b':' eb6,J S. : 196 .. ,, Geoch exutryYm i n mineral or.ploration : ilk r po r and ow . .l'iow York Yr z:ax~~ ~ J, ad Kicolini, P (e d. ), 196 2 ., Stratiformi copper deposits in Afa Syipoe ,i (Copcnliagon, i960 ), let. part . Assoc . Africana GeoL Suri eye, k' is. J. and NTI eo .?r ., P,,,, (ed .) . 1963, Stratiform copper (epO tC in j ricac '91.962)' .,, 2ad Dart : i acc 4 Africa! GoaL S1,uu eys,,, F''a''.'as, z ndolsohgn, F . a (c-cl ) 1961, The geology of the Northe rn Rhodesian co ar@bei,•i s 9 a e 1c i and Sons ., I;bd,, # London, Towisa J, S, end ;`i vbb :, C sop ]9.61 ; G 'ochem. cal prospecting : nvesti gations i n the Northern ithodes ~'n e opperbe t n I con4 Geol.) Vo ,, 56, No . 5, Pm 815-84-6. White, 11. S, and Wright ,, J. C., 1954 Me White F .ne copper depo sit, Onton on :Cow ty, 'Ac-)A .gin o Lcon,., Geo vol. 49, got 79 p$ 6757164 Dct r s t_ ., i E+'t 3 . + !,toad- it .3. ''Rot.W R . L ..•.5.l.. :'"t .- .... r ._4y . F°. . ..,tr. .? ...'ri . r; 90 4~~ V, t. r ..° .' 5t,` 9 L < j ,,.28 0 ..` 2 +y~ r 8S.. 2- 5 1 5 69 6- S •.•. : esscl.a".i ' •.,i, y tha,i,r k ? WS P d ? + ;_ , s:~.4 .;a Z o., : . ._k :_i•,:. .. .• r +R "M uc w ti. ox aei .- .~* f~ .l . .3. of OOW._ . .S a, . €ic Eta ? a a and ~'3 :r " '} y F • ."t ;s rb"' o~ w inS ~.,r.~:.~ :e. as :~.v r~ able, L e:' ! . i ~? r i_ 1 1s 8'.S i;r f k ha t L' i s i •~ i' !~ ,~ a€. a to rv ., >ar"a'..~ .t. .S,kionS, 'rar'~: l'. w$ r.~k~9 yC""sv. ~7J ,~ Wr s f S a i Do "I.~ MIPJAW CH- 601 0 page IT-VIVO i I Important 00 C~ Dki a. Fora4 1 ita. " s t' 4•ati y&i .1-N /yO S vein deposits BQVQS,,' (Fe my . .w.dl',G:.i,.-`s.. i''y'.. : duo pyritee L T An sL'w? ./Yi.;'z.. - t €`,; " (S lc. O # . ; p r "2 ) n•, ueao'nd minea:ai Pink snood ei ne .E. a 'L UnnaQW-, cogsAll lN-Yl'a>ite ip d ! ee .'t .5 . :.css f1?-;l noz- ore S d' .•"...._. Coz3J )fa3 end , SOW - aol , . . N 3& : r Sm a' •i. . f . i ~a w r " p t "S i wea :" i ;3 tt tl:.'.+ U M a ' . A a of k d WAS"A 2' ,hn P -+ of a 'mcn>-. ' s t € yt~4L r. t %"Nft . t Ned, ore latorit :+ c N`I ekesv`es may eont.>s ;Ln M q co, ca 0 'I ., '~' ^ . .• ' ; '1 M an.~ ij :`c . .. . C .n.i. Win! serpentine rocks, whichas ,~.:r; : thsra _ t.~_~te',v.yn c:. ~Ta.is .tt~,,a'~. .~'~,'.~''T ~~ (j ja a .~3' of .. u,.~'~ qt ' . `il t r v..ba `c _ i . hv~ depasi s are u.ii%a.A4w-S~ associatedv With . .p :°"" "` o ti Ae F• h ti' tj l' ''SE, g xiF^ . less coy-mm oioy t ?w~^.'hi P o :•'. p i pcyromeno :1 .. . . g.J, 1.7 . ., . ."..~. [.' rocks) . .La}symaa: . z~ the mostu . ..r~~.~s7area .#. sa:? fig` .. L ss"~ ~ .{orit~3 `•,a. : aid: . of ~• .''. .. 5..3 ~ move important•; ta4.: .dl ~C:Y E. . .. C..lv'ro~~•-of'• ~'~ ~.% irh . .•° a i ck' rY•°s. k`Jeathe`rC. inU o Scon•- ntis .aaitisand V~ u.~. .i•i.a~ :'~.' t'Z" b c,.i b .a.~.. .S`'~y ...i3 m a•si", a~sit -1eh~i ` .,,a.~~1, j°._,~r''.vils o ..~'a. a ^§ ,ry f? Co) became enriched i n ` 'n etl ri e and K-W lyci . •~; u' `' ,if >. ~ rbr vha 5+~ 'N s•'-s~ 3"' f. The gro -.t7" ui t i s-. NJ., C 'r.fi .F.64 ~., ". - C .pi R•" .?,. i3sx {."[,. ,~i.~> . ..: E•d .~.f.l~ !~~de e'`'4 YU.~ .wJ'ru, ~ :J s y and lain n tt , ofo :~ these n i. . :f? a soao i "! U nna oE° h. . .r elements in are .J E . l m ,. RessGc^_' .r h azz t4 . . ..•. .e K MY r., p G ai "c?., s of „+ .'',. ., WAS= o f M a nd Cs (n p octal y . . L • . .= .. '}JS regard . PC1 a,. 7 ., .. .y . ' ':~.A-z < . ~.] ::-Ca En d"l~+ .5. 1i:tc :' c ( ) P .s : " or the oil rocks content) from 1 t . .`.." ..t {?R. hG °3 . .. `W°a a .+•vZ "d ~ c N T1~ " rock' •~.'+,':S d!1 . .?.~.. . .H s. l ..-.e,Fi ._t ... s. ). pe . " that of the i s of and 00 3 ._, , . ; t 1i~ .~, ~ a .c . n .~ to Ln",' r . S its a'41 wmt 4 3f For , and L in Igneous Rmko 1 S ! y~ ~~ F. Gt,1963 , p x;06 % a O 1 s h 2 5 S I ' ?E 8 F J ~ Y R 0, 7 i I: f 3 t ip ;ua i 4 .. 1 {II ^s Ft^ Fogs S'• xz':` contain igneous rocks regularly some NJ and CO nd 'must c,,, n sa:Ln small auO 4,u of r ° common sulfidev minerals w s'.~"~w~.L as r pe°Y"~e.rla+."+...?„'s 4„ i. agvver moot of the N`i aW Co found in igneous rocks occurs i silicate minerals,, l`® ,~ „z`,,, Yu Y specifically the o'rromagnesi n f ",•. .oi s ' silicates, If . w?.":a• ...~ry,°.~_C.i c:aJ are 3J.lrl~.•i Cs ~y silicates E' ±l NCO and z e : most cBund •ant in Cats"'atam s. ~? c„' and m. ~.~„ .~' rocks ; ~#'~3~' contents of s" 3 ns y'3". ,.~ 00 and M d ecrea°~ "~ s e sharply asthe rocks became moreCo. .• s, _s.... .~t'~ r as _t, F?'a t: .! '°;.~ tile oazftv- o,~.`fly, fo r „`- nevi 'which are Ls.-*sbt a'. `.ndaxlt , l i '+.y' c.,, .sr ado~^.w.t .',., i';i'? ; + _ j ' M rocks, such .~ . =u~~ .1 ec. .a i ? y E r e`' containt `31b average ~`Tof t ' . .. . ._ .. ~. ~. .t .~~ -4_ : . r!'` 3'.d `N+ '_' t w 6 :"r o • 0.3 4 i . .. n ifz.. O _ .w v,'Uae and Jy ...s .e. ~ s } i .,: n _ ., n .r. h ha- .I P8 r.2O" f „€ ,. 1` ,. s°d' .r is i3a ~s have lower M contents,; C. , . ... , .> es ,via ! this fact d nt the variations in h! and s' L contents if f t e;;m=c. ~ ,.. t e _ ., ais S . E.. z•~~ . o : L ,ys r b rocks are closely o one another, <.,,'-a 'F.'•`-„• a -. g . ...v~i is f.:~l ~~~4 £~ . .ts w°'.,~ a~a rt has been for l° o r j S• ticks., . . .. ~_< -.7 Man.t a'? i.•~'",l'b~ . «l defined inverse , a ._r. .~..ct -..~.c:?a .`_'~I Uf~ , :.5x.x_ .: .C:<,i the Ni and Fe. in 3 contents n E,. r i c x° b c Y„rL ic rocks, but : i. c { .i" dinq.~o is r ..+, [ 2 t . o •; '" l d ? (1963, _ i i s,i,. . c; .1 ,E.tr; ._s;rt this does hold true for .c m ru .m, e r° ipo .' ,> ' l t s Ni tends to _~ . . `kg ra: Saes than Fe, in ~'~,U'r "~m rocks . ,i_ .. ., , . _ . . .i.•n Ot . more racks, and 4'dy1 b dha' `,,; di-'- ' y' l .. ..,' 3 .s'..~ . 5 N4i i J v ' :`,'. . _. _ se a .°.,.. #i n d y i in h.3 otise ; hornblende, and .a.:':Ejo.-. i !Fo , in a a medi tt racks j to _. t -., t s mainly in WOWS and v°.,J.e.i3_ a s.. ..~s•`,. ~ :i„` in the MISS racks Nja is ArTied by Me 10dapar5. According to •t ~ t 3 c Ni of the gra .ri1 .c . d is directly MO W'.;, to he I` .f content , "C? .> ..• ., .> . o ? content of rocket; S s E? ? '' '•~ r ~" + z s . . 3 + . f y hi t J t ' _ " Igneous rocks, . . . ) w `- y vnry • .n . their~ W .. .OM . . . _ .. .f than Apr-N d _. , . ,- , o behave ., - their gees -s m ? t, c l c y i..!' e N,' a... if .. j POW._ curd , j the 0:00; CO achieves it . .t° . .. . .v . . v ..• ._ .,i,7. . . , • .s . -n:'E. m ,E O ._ v ... ..Wm . .v Mw},. _ _ - 7 .j have WHOM= ,. .. ; n Y ta . ZZ k .} cording to G ! a .. t.Ae... (1960 , p r•. - .207),p -the n o... . C .., . . . l1 ,'^. 7 : =' 4 ~al'rzjs9+~_i_ b r . s., ra C~c~ .3. .. {. „ ," y. a ~_~c ,,. .M ..,.i .. .r~, ib.1 e'..ha, ve diff.,...... F, eren.., ; .,. ntl.lyri I-, '~.. . .c"' s', y} t a 7 aqueous .-i . ,both _ ~ ...... precipitate >i s .. , t.: ~. :,. in con ditions, a , '. . "' eWSuel wa .c. will ,^ p . 5.n o.m ...... ,. .a. .1.a 5 .. ..., _ltf r .. a4 ..:: . .... 00( , , -° . ^ 1-1/1 .;., . :- i lower than th at of t ,A` 4 O 4 bat 0 9.. 00 : i,.s.l °i ' to to 71"T patio Mayeasas in hot Origiral 00 COMM arc hi hg , 4* i • A3;: 1. a~~.; .pM:F ck =' =b e IFe S 1..7.6 : O ov Ea °'rs of CO W M i sea c' to in t7ez Inul as most of the i o a 3d NNI . •r. sr`i`, z:..x~ t.3, ~•~: •.. r_ =a. i..'+.? to_ :~ti. . :' sea. .~!• .•. ,. deposited,•Y_., E the .r y"drh3 ~' .s ....Mt ..:e", .L'C'.." vc-X7 ~~:,'•' . grn, .i.•S d •izstic and hee eJlo derivatives o f Y:' d'':c: .i h <:J.'iSag wh as WON, clay, " n e c' ° F. v'1 r. .. s+.~ ^ s ,,.+ . L'i3.a~'a r,_ .`v.*> .4'~,et „r c.) Co ~.cea.r removed, additional :auK A?} ~t,.~~'<~` ~si . :,•._r3 ,:4 .3'1, ~" :T~ .,.C~ c"f.~r~iVY13s3~Z~ . M dim Y1"ib"7.° and a• a :'`eeult may becos e enriched over jv^. , eo tra., to the case -W othe r `.sedimv ` & g . 5 ;7 ,'~ .} . a :.o u~' l L Fr`: %J rss_ i,2, and Go occur the~~;' , :~',. ." r< . . n.' of o marine„~<"; a~'~~~% i7~sss end o h ?°ao 'r thus they m end to concentrate in :Ledu `;3.3 g r::"j:laf nn entn ehe1es e a .:d 's n .`'9 fqn .&Y~.:. i ~ . Rn, ff,• `AO 's •~ a"?'aL...~ .•oa .A'gyp _dC; b~R'rv,,',~`Y~-. .i 'c. 0.4. d9 axe to cam',`. DARKa.:'' H~'~n•.•y .c.~`. 12100+ ; .u ._ _ ir'.„ wt ~~ .. . _[' ~ rocks e altered i is^e7 's ~{ '' 1 '7 .~q . ~" n F`~rpS`"'.i'. tin 1 , iA .`f...• original Iki >Ww dN CO' "contents remain "3 ... F 3 '_Y ~°'••~,•t}Z~: .•~~.~ es~ y •y ,+•a sqq,• .~«.~ ~a ~r . } ~y"-'} e•ne~~ 'iqT[s'9J~yp~ ~r 'A ~E n'+ :~ -.'J,'tp ••'y1. i q F .isC !'1. saJ .l:.,is. rc: ~:.F .i .y~h . . :.~Lr .""-yfr t• °~ a ed~ ~• L»N. : 1. fi-'o ~ :a•! rocks Weir i C.t ~a'4• 7 reC•is .+:.AGe.'e A:~w . .,s• s r •?•,~"'a4.e } d d7' ^")^ 6"^4^ ~' " c•a:y •!. js'Ji fo `n; :r a ..:'•.? mu_. .4 .. . . 3 .i.•rr_ J>..,,a..,". G` .W~3•~ .++, the ..S.v ~. : .~, .? :'A"~ Chloritesandy°.a~~ +•.~~, ~ .~,`~~€Aes }' ` d R ' (Mated M 1' ! :4]'f'!. ._~•4..6~r .t-4p `~ Lb, 2~ ,,_ These minerals Now= important M r LL f lt er solo ';,tia ra f asic xticks t i 1:?.• and to aae •',; aER y in .7 .. e°~ q +.^I a'"' ?J . .A• c. s e i: ; C lower dsi:5l: .:e•:;a .i. .'` f. the ~ :.3.t• .`~":.~;ti:~.~'•i~'•i ss. ~; the _ .7~.> in leashed G~a??i•.. &' the soil,x ...... r.*the`i.r~`~,.. >'qJ~~ •-y p ., in ;'yt~'F•'v .'"a ;+ : _J. C waters ha c sad::,``: available andd it Toasts with with N 'a. r which ~.:,' c babl. 3;, ° goes~yss r°` ~~` into ..,•"t .ia, 'Y .d_q 'a.- f::i,i" J .• . S(l{°'"l .4 . :J' :) ~ dy )r. :>Lh C dZ „ .Hl+vr"_ ".+ r.Y Tw'~a .'iLt".?i::ft•~.:°percolate do a1 €to law ..#~j. .Trt. w S;~ P'{s.:r~ii a A >Y .C'ri : C•:f~ : fi hi}S:a, .."~3~`~3s "~3~`~3s which s_a, .f:: a ,~ :a~',t^ 7 S~ 'y..i;;..4.'4 ••ig.w ,.+ ~ 'and.^ :,. n .; s. 3 Cobalt i' ;~.~'°~,:,e P :r'srehn .,c,. z .c,.• .r?a•. .~; ,t~• does i'ihs~ t~t'#?~'L+ it •. {•'~ ` y mu .^y h :e . c. s^~ 5v ~ 'CtY{ )`S ( +'• .~ ~.rd~.~ 5t.`k goes intoIII solutione-~ C, `J a F,..3. 1!~..^:~.'f,$t•+ Z•L i. . ~F."; l, .. 111:e . 1-10 7`"3~ Crym'y '3i':,~. . .1 .;,•.2~rT lees~s Y t y: t N - 9 4., ' M1l . b St ' . . N h ^. raolub ,e -h, ,'Z _ (H(HC CO-11!2 < ,s_+$~~ .t',_ : ~~t `3'nr" r do ,,, ;n . ~ , . Small.• :,..L.•... .3. amounts ~'`~ of FS .,>and fd'g•r t,~'~ ~ ,~'a ..3.._ : l a r widely d i. ?: :<';3 au in plants andr:1 c'asST ~•""• a'•.•f, .~.~~ Trace t7^~.'sJ...C~ .~.Y_,vsWeeuz`y:~ of c,y,•~ o are~'e` L''t f ,or °i e sheep sad cat.c. . tle a o remain:><• .c healthy ; c,•C L~ r .c ; .,!. ,•.. .., :,z ;rc~'ccauses a. disease knowny~ o"'•~~ ass y y~ S tq ez• 'a-"~ Y,_e-± •1c ' a N '~y~ ~ s. a. a y 9Y sj;e»o> g ' . 'n~" ~• u CSro ~~Tw "~a.L>l 4a.~Ii•7,)„ \ af3eJ. :,•~r do~F not ~ 4~f lG..L•. •~rCu E. ~ T~i~ 113or. i~.'i ~. oa butthese elements these in'-'y he £o .,d in J.i _s ' .w the highest cones' 2i'es i"tea; °; nt `J' being z n the leave ,E h vely high contents !' A Ca in th ' jh' : !s m Y e•' of soils (over l aver C contents .e de er horicona) have Men e:ttrbibuted to plant .action C-,) sand !U1. ma~'T e~oeame enriched in Coal o where °or y ~'4 ti'>J tc 'd of l''a• ci mil e-r~d R+~ ;"s f.~' Fw yo :cur ., The content of Ni and Co in petroleum and its ~ derivatives may g ? e high !p ' •.'.o^ ,y,)7~"`,•"0.r~'l~:1~ ~ g%ct ?` in i~ .+.~a',s .h.i~ l.Zo~~; .!:^rsI 4"$1forms WP .'.~~ia:r csimpL un d'• s which are uGua ;.l y concentrated in the pare In°,r: 0 B Er Ulna,- rli k Pegs S. ea .sq. H ir' i o3."'.".eq a Usewcssnf ~rc i:,n. .o ..n.y. .ar+ . gosxx . cz ~,wv>w.;a. ,< ssP sarm~ ~s:wnswxMwue, cue . .v,cu•: - "(a. ey . Winng, I966) hat : has been found to be ve .' useful in geochemical p ospect ;, especially as a pathfinder r 3 .-Cu Co de sits associated with naf'y c rooks, even hough this fact is not wisely epn, e fated ., pe 1aps because f the lack of reports in file l itererature4 Caun y I ti work in. wes -cent:.2. 1, a. . e has °sh of zi that aalaomlalous mounts of CO are likely to be present in active sediments of stress draining areas of ni is rocks mineralized with 111j.-g Cu ,r~ arid Cioo-bearlng su] 'ides. Stream ta~Jkent a np1 ee from the vie uj'' o a gwbbro norito mineralized with subs-economic amounts, of rrfrrhotite: and Un oopyx i.te w ere analyzed for t tas. Cuu,, Co, N and cod-ex ractable Cap and Co. Hi ia.. anomalous values of both total. and cold-extractable Co were found i h:in and downs tre from tide son e.. D UL did not shop s distinct . £ ~' omraly as didl Coca There was a weak- cold-°€ atoraot able Ou a xhiial it which correlated vl."1.h w' E:o peaks cue the m :'i. .tTMi"rca.L zeed twea ;i ha e verve total . Cu ' aved ,!Yore all Tavithin background ge Cow both total PYW, Bract gas . , seers o be an excellent indicator i n pt ospLecting for similar dowaitsa When l 1 ' Cu « 9 and Vets « Cratios Iraf sh --;ad weathered mineralized ck ±5 co'mpare' iv th the same ratios in sediment,s.+g the increase in respect o C end NM is striking, These da:ba 5.,7 j-Ay that Co is more o ile li&i < NJi or Cue. Can ey gge '~ that !,."L end espec a .ly Cu are 4 a p ~c d 'by secondv iron ox° ales w'hi.Ie Go is more mo ? Sie in such an ' fro rich oxidizine en'~imi n ar, There ore, •~1c primary Cu : Co w "Id Ni -co ratios w of ld have to be very high before Ca would be o subordinate e value to N'ii or Cu as an indicator elemont . Another study was conducted, in the Blackbird CC-Cu district, where the ores are hydrawvhe ° i c replacement deposits of C .j-Co minerals Fe1jit occur in po d' 1,111ce massce Principal pr; ary sulfide minerals are cobalt e, safflorite, chal opy t e,, 'rite and py ekhotite Cu :Co ratios of cef .di ;e and unoxidize oro indicate high nobility 1 "Or- Coy app .rmrb y 'the Co is not adsorbed or precipitated b7y I :Wou.•t. o, Cu end CO : n active stream sediment and .i n stream water balm thx Bla kt l ore body were analysed; in an approximately two-mile tee-val below 'axe ore d the Cu content L ";he s 'ore?: sediment decreased b a `actor of 125 whereas the Co content decreased only* b;y a factor of four. The o content of the stream water decrease much " or rapidly mid •: as much less persistent n the associated area -sed5 . went as rm y4..17l O .'imit d pHH studies were made, but the pH of waters n the mineralized was about 645 said the Of Stream vaters in background are, wa a?.s.aall , b ve Although Flekes and Weth (1962) as a-+ gay A : .rte mediate mobility -to C c - parab e to Cu, Ni, and As, C=ney feels that Co is normally a high y mobs le element, re s h Da u , -11 the supergene environm n'tff As a consequence, it should b,e more widely used. I n geoch$L- ca reconnaissance using stream nt end water Survey $a B, B. 'KU'Pd-riok al i • F'~ Se601 Six 'ia, M ..~1.b'4.~itl .~wH.>.4'hr 'f:~+`. L,d ~N tJ`.:4.y6,7..4A 43Gi.wy F3 h.5i1J6 n~e.y,. .w.ar,.vxcaux:wnw ..vw .. .. k. . •wd ~s.M+raew.unHi--,t01 x o of Cob It ..fit C c~ ghnssr r e " #C iJin,y "s 966) Cobalt t has been found to be very useful in genche .c, . prospecting ., s p ~{ as a pathfinder for `'~. -C4-Co de sits as Vciated. with ~,++ic rocks , even though hi s fact is not 'w•, dely ap :Uiat€d,, perhaps because of the lack Of reports the literature. ~°izA3~A~~~; a;Fi3 :Y°~i in E'~'~~as4~4..~Y17a:~"c;~. ~3~s~?w;~~s~?w. ~I '.Giw~a that- c1:'~~.~2~,~.65~2. :.,~11ou31tls Es1 {n`t'3 D v I:Ucely Wo d o presen4 in acGi a es E.'`diments. of sd F.treems drCeining areas of marl e ro cs a. ner ized ' ith and Co-bear; . 'eg su.f idFee St;aeam sediment s 4np as from ate via 3.IL i y of r i nora issd w:ft h sub- c sonic amcun?ts os r °hotit e nd chalc©pyi to were v.ie .. 'zed fo•: tofu. Cu, Cot I.I_1 and cold-exbraotable and G;.. Highly a nomalous vV1'uuca of b%Ab t '~ 1. and co3d- xtractable C€ ,?ere for d tidi thin and dvw-nstre ir~ fbrom the z.ne N :rah xae did not show as distinct wn i a 2oI:l. e-I"ay" as did C ':?v T3i CX'i.i ua ,~3. r'3, we ~,ti 1'~ . c n f T1 Arr L•J.J. £.si? c C:S r '"'~ .cn .da:d with the Co peaks end 'G h a minerali cd car ea ; h i rer, s,ote]. Cu values via e ,A-11 vdA n background r a gre Ca,. both total a id cola-e 4 actable s s o by -in a:cel t initiator in pa o pet t:i gn for U .il r depoe is Lhen he CI;.aCo and N L .,00 u . ti.. s ., ew?I2 1d -Ma tiered n era]i.z d ck is "1 c $"Ci~ ctfi? l 3 ame d ati °a any sed it tint s, the ncrease in Co "tdit es ect to Gu and T'T % -.s s ri-hint, ` these data,' t7] the:b Go i`~+ 1I1or S"1"sob l c t,, an ji or Cu wi,zxe j ugges ts that 1I an G" ash? 0iallf" C a't ei?'appef by SEAS ondary iron ?aides wdhil ,1 : s mcx. nob'Jc '3n sai ch en :>ri3';c^^Ach o3- .Jis : .:'ac :nvir3onnansa,e The.'efoeRe . ile : e C, ± ou d be of Is J "U""uT Cu - Co :: nd Ni b Co rat ;3 s °would have to be Si E IU& befo"s sulm iylebe U clue to [3i or Cu a s an i h' is t`'y, ? vJ s '~k+~ Another study was conducted ; n e 3 .ack'bird :moo--Cu d str ict, I da o, whe the ores ai' , by drothermal s i plac&isnt, depos iis of Cu Ups mint r als that occur in pod^71' ka massce ?ri.ncipa. p~`imar sulfa"de miner s ar cohatite, saf ' . o ite, ch co ' tssr Mrrite d p nehotite Cu ;Co ratios of, r3=awc ~~i : and unc' .dIse ore indicate a high L obility-• for Coq appar e; t y the; Co is not ad o bed cad px'ocipitated by limo . c Cu and C '?n aot ve strewn, sed iea7ts and in stream water bol d ' She Bla tail ore body were an .- ed ; a 2 . s €~ two .le interval beloL he ore body the (' content of e titre a sen t decre e spy y ; ac or of 125 here 'she Cap content decreased on .y by a factor of fourr The Cro content cf tie et en eater decr ased much mare map y and rrmuch leas persistent than the associated Co stem -eediment to aly Only limit pi stu es were made,, b€a the pit o :eaters in the mineralized area Q as about 6 5 and the pH of stream waters .n back ro :d areas -was usu ly above 7, .t ?ough Hfi :. es end Webb (1962) ae: ,€ an intezmediate mobil ty to Co ., eo parab e to Cu ;„ Ni., a d As, Ca ney eels h Co s normally a hig: mobile element, raor ao than NA or Cu, $n the eupergene eri~ ~.a ~R7s73t ent1. As a Consequence ., "fit should be more wid e y used ? n geoche ca s' L"~ s an using s reei s ,-'Men mad ImLer B. B. ai 6 .e en " c~C'~c}3 s?ie . xospE . 'tinz )v'"G~a~{ {.'~'~'~ :to .n ''~~,he Jo "!L-~~.:4esn I od :3len C~r~~¢~' G2 ` ._'s~ eit stud ies in the 1N o rthei s MS4ode[?:£.i;2$.3 Copperbelt have shown 'E 1 `s.~ h A a u a"~ce O cu- co ore, & -.2pxi is beneath thl( 4x e:'"hh.. rd - can be, t t 'he ~~ce°~y ~ Of the .tJ°~, +t near surface sG01 L c of e fre ~~' Ct;' ? °`aiad 4 t.,~ :3` :'^'? .~''G€ .t •L',' i'y_. .£~;fi ccs ,,.~,~>v;~3:.~. es' X33--p 3OUIS, Total c e :l.' i.-,.n cobalt enc sa ies rsl scd t o "-' r z 'P " n h e r °a e .a'a l rzb- and are no _ c'1 . . _ "~ Lt~~ `1..,R.C~e~,.,yy 1. ` .~5 ,,A m . y cxtsnied ar;,, u'c l ~, ci•1'~ Aa.o'~+'' .. r. . ~;ota.. ~.t :, 'theLd .. Z.. ed~a~`" utcr f, The `:: oc neiot ~elFd, ~ k"1'e61+J R w3n'^ wLk ,`~',V,~atwito t .1rj1,"r,'+t'fat y p~, `9 pp 11 ~ The f .w.• s .. ~iSGrn,•~.a,.~'7-S d+ ~.:."' F~iiJ,~- ~.::.+ .sat,.i s id~ C3 stdk, 3. eoct~s~eVi .": ie~ :t7 .hicb `zo i 1 ". ta? +' and t.n de- xrh '111 o n tendency re 3'n ~ { "y 12 y '1 ry r at y .p~ `m.7 Y °`g n v3 i S ~ ., 1 ~sJ.~ f.1: lm'i+. . . .,• ifn""w~ r.. .''L"• s ,3. .+. (' ~ .~, 'add{' C.` Y~- . . ,{ ax, t ~U { L .d F~ ty ~~{'~ 'f. --width a ati,J c 2 5 er ". r Z; t~'~n..1 Ea t ~0~.t` 's ~~Y.. .t,'' +..~.'+..t's.+e"~ 3 '~~ „ "''y" -to ~[J . 8vw ~;: .~ The ore ' s°, frS-u nel in the n' at cen '^* 4_? +i "1. :.n 1 ,- in sh e s an s -; s onee end the ore strongg ct •w'~1'1 3 TheCo Ii ratio found 1 -in c is *,re Y,dd i ner ~. . Y 3 "ground zs 7 .1 greater tha ' •n ve m w g ^a'''p '''" v r t s ` ¢ ,y . One'; . n soils over ,~=g ., 7es~'~'z~~L~ 3,.~' e "° e: a 'u covat .",M decn;P-s:w o 1 ss then one w,,id the tots N F'A Do Values rann t -- s much greater than over the aed wntca . farmaa1ou ;s Cc; ' O.-aes have el c°''S'lil a lakt.'eral d to those o Cu n ,'-he+J :Co r o in. soil sampless closely r flectt -that of Vie p danany o ee (R' 10 to 20 _II i. t-1-mv -v °, Teas and Webb re~~o , thv; factors affectingg -t! d w3tp"ei s-ion o . Go do not sec to be :• ifd i-I.c'.,r to these ff V ,!L1, G a tendency~r 't t7 witht2 the ."a av aple '.': des o s- e z t~~; .,,a u : but does Co. not -w Near ast anszvew"' «'- 7 aty .: .on CO a ~' wL caecs with depth rage. 't'~l sE.'.'v of the soil oral don, 1, 1,41, in backtp-rx'nd areas; S.i e CA, content'` showss little 73`ar «;tt.io:.l 'throughout h e so?... . profile .3 h g3 ."" `s Thus It i `:{ p c bible 't h tti Co ° I: .' not adsorbed . "} Y s 11- ''QN-A L . ^r`~~...tf..~wt~ J ., ~`n.t ~r<~.z r m ~c,~y.•.,s ~ ~ 3 y r,p.'F33"3 u~ro ~'f,i. C+ :? P9 s3 .~•~ E? g y •7 s^* yq i~~'k +y .5r . . , g s`~°('~~ .4s~ ~..~'them wasC .w W .~R hMtrai+~~qq~i+s .at (, `Si,,. ..O .tEd of:1' .0. N~a. ~J^~ f. 00 and G%, a T Y M' 'g cti ., A 'efv ' '- a. ?E ht .1 C 3't2 ~ ~`a.,3~+~,sI r . tz ( G3c t "a~1" J-71 C?'~'~ T tom' I-vig ' :for a~`t' .6t .E :.:~:~omm:~omm''6t Geo ehmical Pr ? 9 ~:'~ Cobalt . Ontarioo (K h A tt 195; ) f~ '9 ,,ia .u?;" ^+ . +'~•J, fs.• 'ec ;uh. ica 'p, rospect1'¢.g Y pvog.ys.eiii a'a in y~ glacia~ ~. =~ S .,dea ~~.~ii..'•,. J - ~s .'-" y . .J: nowf••nk ore bodies comp-Med Of thin Gins of - N.Iti. . Co rsen des '•• r. f .°~'x,`,,a~ ., ~~ n . ~~?s.:'.a~.i~ Csof.~ ~~'s~s':3~:#:~~~ was carried out during the summer fiaw ~ 9,~.~"•~<.v co balt c + no e rUf =' ., . •s, -g y ,ioa, in ~ ~a! .. ta .' glacial Samples a n.~ ee is : w7's on : one hua2.ci .red foot' grid 1p ' t r'?s with a t.;%-Like c, "t3~ge t , " ~~ ~c t 4,~~ ~~ ,~ tg' at, Lk~'.~~st~" St u.~i *' F a`a1 'Es~.`~ t+ . Lt1~.rr "Li?~L a.r .'iE . Ci~ 6+ac",".! bsi: .{ .Asicted o 'f' cS.u RS. ac : s''- dy "a clay,, G " d c c y'~~ i was 3 o id pens` i L p' op gray'hy . e ee . r F '" aC re tiaT y wn .c e in Co or ep so. . .r f. 'a h u sh re at -vely moe pea ue--hle tar ea Ca a y see ed o ' dsor` J Go t ' s,,,_ . x VE 601 Page Right w A detectab] e: aly over m-1nera1i d bedrock was found in the rear The Co values increased with depth and in does-section the anomaly appoare dom. shap€ d which suggests that the anomaly i s .tee x os'G-.L o upward •~ grab on of GO since the deposition of glacial Materi'OL", Me sampling 'brew I i Y is + the detection of an c and wi sufficiently close spacingg (depend? 9 upon the size and grade of the ore dy) surface San.'ry"Ji.n atone ) o be sul ieitn1t o dated an , acmaj , The wwwork done d uonstra es teat e econdary dispersion halos in aci , maiLe-;Aa can be of sufficient magnitude to be d to ted b " ^"'hr:' ca ' ecting m .3, 0 r 111120CH 9 .'°1 4 110 y~ 1F 3 J r~9q 'i f^ p,~ rs,-. ° •"f HC3A .„i. :g s H ; and 1'1 ; L~ 9~r i '8,r 1962y ~.r3'~f .~~l . J. f~.r+ Harp :: i`, 1.i : Raw, New .f.e°3 S G i1i F: `" .nc 1D1e ; "uy ,, A , ;3 19600 :E s s geL" chemical i i pocti g 3o Pi g "m i"1_. Press ; Now YoTV a Gold 7 AAmd-d t .r "' :_ 1954, G eo ch't"`" i s,v.- c f Fd '7° Qs Rs H Pn London, k yj y 3 ~f s:4 ;~~° +~r qvya. ~ , Won, Q .1,. L'i°'i 1965, ~~ 4~. ~.~..•5..~.:.N $stJ •04. .fv3G`c i, vio. l ,y t Jb ! e. . V"T±`.' y oy a•~4,;Tn 1d. sons o Inc, , New York. afkaa ;g i,r and Sz"rhvma, T G.v 1950, GeocIiamistrp uL."y'•.°+ e i .}, :v 09 Chicago Press, chicagos S :s`" F . 1964, G ;'d'.'.hemi ashy f n i ckel > y s a}.2.?t oids iwe o oh?;G.i.l a ..•ry ,in'daa'• .e'Yiiationai, No .. 5, [. .rc 880-88 8, {? •einbe r g x D,a S . and Nat akhov .c A,, 165, D sa~?.'Mbuty ion of nickel 'i_ ; arc.bt :r a.~+ic roeka o•i.'Mthe }.3~,i.'&-l ~ e Geochemistry, No ~ .~. .bq pSA 1020-1033 . ird•tsie n'ko, I4 J , and Plan, L A 1961, d Chemist`,, ltd ed No Gr;"w+°='H .El Book New York'. •. 1.„C9l o r'~ '~h F ;:* a, .. 1 4 .s .-l"J o' ~ .C~9" sJ "io, SAW, F ,h exu ) r''_ Y .J,r,Z ,M Physical r~~:°i3i, . E3~?~.~.3.sa~+ .Ltyt. + x;-fd:... . .,s.~. . . .,c`~"A"' ~.. . eya,t`-.ayj cr _, .~'a~w _:€, ;a r . ... y, 9 't• ~'~,° {' + I c ~'-" . .fts j c! W 4 .fr.y er. .i v rr "~ . ~~' r . '~` anal. r-. ' .roc43 ..~"~3'' "<{Bh r Y a .. i. .tit ;l<''~'~~ ~ } ~ ex'€F2 s . an~d~ cobalt duringt .,.,.. :2.,,_t> the formation of the ..d.,j. ~:,-..e3~.'' 1:7 ~,.i~ta :~.l,~r9ae .," ..>v+ massif : eoeI e' As t ; , H , 11, px 1076-3D85 . ` ° l " 4 ~. ~.rva::~e, 'ti;;~ g . ~.+,~. and~z.. _ .~ e~as~~,' , L. A,sr 1966,~ ~,~ohe J,. ~a useful but neglected in geo ;h sa3m ..'.,r`•:,'. p~roepeeL:krg 6Ecow Geology, Tel. 61 , 4 198-203,, :Fn t al nt'd'n Hill, 4 06 1961 , Vii' k.% "3? c ; rose ctiz..I S :"o1• *-V'1 c kel 1-313.1"e .5 .a..1032,yt area, Jamaica, 34 W &= Geolo E.avS ; 56, p ld..f`s c ~` ''t ~' 0n aa?•w : ' S"o..$ti, • .a.1Y r e°~~'. ~ 0~t.,~et anda°~' ~+~' ers.. , -31-954 :,, Ge `99'i~ •UA 4">r~. ;.u.. . .f.~c. el prp E"r S:is, n.F.~w "c.~' -~ Cobalt, A= Geology, Vale 49, P a 378-388. e: `S f S s t~F t Y'r j'° -Ins `. Mailer, f;A a, P 1961,Plant soil6 fi y o ~~k.'*~a'_{3e?.t~~,, .. . .'L~ , !-fist',for nickel ; ?-L. , ,t.., Ei ac s~~S en Eng6 Traps, v. 220, p, 255.260 . Pratt, E4 ,: ',c and Cornwall, H . R,a 1958, Bibliography of nickel : is 9J , S, GEa;?wl c' Survey AM 1019- 09, 9 O B. Ear K lpai:'tck 4 N 601 ` cu".Zs g var S an.- Webb, J, S,, 1961q G o Iz .cal p ospe t iirre igat o d i the Nor her i Rhodesi.w- o 'pperbc1t a vol. 56, No.,, 5!, pa 815-946,, Vo hii;gton, J. E,,. :964, In, ~.mploration pra-`mn'orca^~ ticke in thethe~~L3id '.~+y1ea 1ern United States eo i, . vol. 59 P® 97-109, O ei e `k 'cam',, 14. T., 3.9442 kkic kr.31-s sate a d a s sOeALI•a nick . t?'6B°3T c"{ ~~ G1~ o. de deposits near ImoG Jose r de Toe+3Gatit~3~ e,y ~ 6d j`i ESda~.; 4w~drv s~rC ~9.Pp7 ~k3v Survey' Dull . 935--E, p, 2V-305, L d UotUAea q, Cuban nickel D,. 11,,; 19' 5, How, ... °dda,3 go z."L~.I-I . La- Ca ~~! py gn r ~q ~} S'+..-n , 5.6,GS(r MQr' S 6o5 November 21 1-966: ;e; and aint o ' to the Gyp V elements the periodic ~ -V an which there is a - tplete , sago 09 properties from metallic `to met and g a the gi .p. The lighter m bars of the , nitrogen, phospho , tft no a f.s- and Z a d ales ; a as aye, 1t dde m rRO. are spa a1s and form eaphoteric o d p t o is6tae heaviest ffi bo ' s c arc in aten its prope as . is s f c o r d s At a Ion . flxdo As '33 ?4®93. 10 -O,23 (A5406) } ; s 5 8,6 d {O} } , := m D. 03 409.0 8 .0032 (Bi(0i ) 'y 5 Arsenic a 4,s :c a st as a metallic modification (greyy s p) . nonce is (, arsenic), The metallic tons Is stable at room t peratu e ; i yellow arse . s ,do; sudden cooling of a .c vapor., consist* molecules an, is 2~ti e The S dpa3; cation states of is are 3 and J% The 3 s apre ° steed by e ( ) unstable, 3 forms are .ous de As ite °s ', a w 101. :treated with water, it foams a s tly acid solution . ~o 'a3. tag the amphoter c: 1 * e, As(OH)3 or H As03o ous sat. His, A . tendency ca a a .o s that are sta%il:z 'by the adsorbbion of no g#- e ons, These cdUoida ca i be'.wag elated addition of R~ or other positive 'ions. 0 °5 state, m : foams arsenic c acid (}I , 4) and its derivatives- 5 oxidizing 4 A92 S5 Is 1wolu .e in acid. s c apo s are well..knom st c poisons and th a is tasteless ; 'beaver, sensitive tests for traces of As have made them pea :: in modem times for, homicidal purposes . Useful antidotes for .c poisoning l$s atsr . Ca( )2, and eps slits ., %W4 Q W20.9 because th precipitate o2yanions of , .. B.B. Kilpatrick tai 605 0 a e eouj +cks : In general., anU + arsenic are rather . rare elements the oath's o ' ;, Haas (1962) gives the Wsrage amounts of anemic and ant Gtr in igneous rocks as 2 pp a 0 .3 1 , r'speeti-re 0 s o Md anUamony £ozt no Independent silicate minerals' but combine reader with sulfur,,..`*,, s*- and te,7. . and form suLfos& ts, ars idea, and anides with various' heavy e, :p ab copper,) et and oo The native elements are also found is xaW veins . Ars c toms maw a ates which the 1 won is ari :ogo p 4"3 the phosphates . .o and t ong are mainly found in rocks and tom A s tizng . i e- stage igneous activity, Some arsenic found early aaWatin segregation such as spc *1jt .o (Pt 2), In general, arson begins to separate first high temperatures after the main stages of m at c cz7stallization (pe,, iat o stage) ; antimony is associated with mercury and represents the last, Ic or!-«, ature stages of b roth' activity . .o, as areenopy'r , -i's p i ar1r characteristic - :off etas atic deposits (tactites) and is associated - wit ' caosite 6. G 0; however, also may be a Import a t tie ' rothozmve n deposits . Cai1ja s of .o and AMmo (PM), after gawk , . -1962 MG S. a w i ~ ~ ~;~a~a R~,:4 Som. aA~ I 'o Fels* As 4 8 2 *0 1 .5 4 '75-=5 l-.50 Sb 04 04,15 0.4 3 3 0 S B® Ea K .patrick CH 605 0 0 0 -3- Bo S8 .pat iek t 1605 0 0 -3- + • B, E. .pa E, . 605 DELP Active i a io A s Pound . In ~~ it35: Native a 8b O g~ tqe9, Mha i awe Az' OMWALe PUBS Iftat a,Vl ndaut, As miner&,, top* t7MiUn to LOW wpa vej u , ate, Sgt jApartaut ape2 1i tae r 6r cabal Ji Ye W6.iai~/70u7 1oe11ingite d eAs2 Ovp1ment A 02S3S yellow"'y Se a° tetrahed .te (C,Fe).12 Sb4 solid -solution series hire (Cn Fe)12As4` ,3 ate P.Bs4 bouraoidta PbCMS3 l e to Pb 4 he ire t .9 ) " tt to eaa is to WAS mrs ite +3 Cite to S p aaa to % "Raty Si ver" a i B,P D "o .patriok 605 1,/2/66 Abstract on Gaochet c l 2 , in the Ke Ar .4stke, oils d stree- sediments in the ti .sh ? . Area of i n erior P aska were studied geoell dealt' to de esmi e tile- relation of their met=esl content to ore deposits. Bedrock in the area Is predo inently schist Meta.s occur in r gj d. quer e Veins, silver-bearing g ena vo P!-s5 a^& et .bnito 'eins,' Sphslerite ., as oWrite, pyrite} and t copyrite are acc:esso y :rsls o the gold and silver-galena veins The soil cover over the veins I s thin; tile A ho on is about Q 4 feet thick void the 13 and C horizons • gethw range from 0,5 to 3 .0 feet in thickness ~r oil samples were collected f ram both • a e ,s , a h r s d e (finer-sis e fraction) were sampled at 47 sites i n several str eams that drain the minere'l .zed area,, A,l]. soil and stream sed inept samples were analyzed for lead, sine, copper and arsenic ; some samples were a for ant s ony . ~ :E pus :no fits of arsenic en /or lead in the soil, particularly in the 0 horizon, are tale best Indicators: for the gold d silver-aliens veins . k1 though sine co t nts are !a ously high • some sites ., copper values seldom rise above background amounts, 1.1"-tal values In the C ho "izon were greater then i1 the Al horizon.. a Z1the f, s am scd.a , a C ant io , anal arsenic show significant variations that sorrel site with the k ow . n distribution of the metals .,, but copper contents are generally low. Stream sediments from 12 sites to the east bear much Smaller- amounts of these metals . _2 f5 . Tro Tern ins, b ° J® S„ Webb A number of pre -W n y examinations d some detailed studies, p ncip .l,.y in East, swest,. Land SGIWI-Central Africa, have d Mnstratedd a wide field of application for € ; 'oche" ieal € xrl ration t chn'ig-,jes In tropical terrain . .a,6° les are given . mainly from unpublished material, covering a variety of mineralizations and conditions, including copper-cobalt, lead-zinc, gold-are .c-e timo r moly- bdenum ., t s aen,, ti. niobium, the m., and diem d • ear n kimberl e deposits . Certain features of observed metal dispersion rc briefly discussed, with speciel reference to the influence of soil, type, clinate, topography ; vegetation and bedrock geology. :!In- many areas of Africa, especially Southern Rhodesia and LVest Africa, gold occurs in association with arsenic and, eccaeions. , .yantii?o . Because (sW of the lack of a rapid field test for gold and because,, in some areas, gold is subject .-achingto IF and d stribution near the surface, arsenic and antimony have b, een studied as pathfinder elements for gold. Bo E® Kilpatzick ( H 605 In i Rhodesia,, gold occurs associated with , opyi to and oecasa ion stibnite in mineralized shear zones and quiz veins traversing t o or sandstone host roach . The terrain is flat to undulating, with occasional hills and yes, and bedrock Is generally caved, by a residual latertic overburden from 2 to 8 feet deeps In contrast to the relative restricted dispersion of arsenic in highly few ous soils (probably because of the formation of insoluble iron arsenates)g, them Is evidence that arsenic map be appreciably more mobile in soils developed over sandstones awl other rocks with iron contents. 0 0 The ooh. cover above es a bedrock consists of a layer of decayed p anic matter grading d r into a yel low to red clay and thence downward into lie- stone, At other places a tail zone occurs between the humus and clay zones.:. . l keg ..pear bogs sevensl fact deep have formed on larger fiat as, -especially in poorly drained areas in ro ed glacial .material Samples were collected by using a pipe fitted with a wooden pl er ; the pipe was pushed dew into the clay zone and then throes to ., or near,, bedrock* Three or four samples were collected from different holes at each ststiona . The pipe was cleaned to avoid contdnation of low-grade samples by h -grad,.sanple a. ti work established a p ima range of values indicating co al (background) and anomalous concentrations of m y in the soil* There were no determinations of greater then 2,000 ppe of timorqq for this value seemed cuff .cient to indicate ore. Traverse lines radiated out f the known ore boa Twelve groups of samples were taken to determine the vertical distribution occur a Fbiimo in the soil . profile ; Wo zones of concentration were found to . one Immediately overly bedrock and one at the base of the minus layer, both se panted by a zone Of lager concentration, Me enrichment in the humus layer probate is the result-of plant action ; that of the lower zone is the result of the sobs of : estone, leaving insoluble antimony minerals behindo The background content of the lowest soil zone depends in large meaOore +n the composition of the underlying bedrock, In areas of urniner .zed 1 estOne, background values of antimorq rLm 30 to 40 puns over limestone-free bedrock -back- ground Is less than 10 ppme The threshold value of t ony (near a er . areas in 3. iestone) 'ranges from 100 to 1,000 p Anomalous values range 1,000 to 100000 ppa . Threshold and anomalous values largely ept upon the dew of ore bod vs,- This study was designed to find near-surface orebodies within reach of 20-ft . drill holes. ,.?,. • B, E. K patri CH 605 _ A ra t s Mical aMon Neat the E~ eha moo . H tbolt oMt Nude R. I.. M73-kin and other-so The U.S. Geological SM"Yev began g ch ical investigations at the Get h 1 gold mine in :L961 to study the a c gold as ation and test the idea that dete xaawiou of arsenic sons i rocks at the surface would aid i ding concealed old ores The area is in the north-central part of the Os good Xaowital . ., whose general gsolo consists of i.ax%T folded and thrust-faulted Palco of s n to Cka Intruded a Grataoa gr o .te s. Most of the o badias of the area occur the Getoha . fault zone that extends along the east front of the Osgood Me at . The gold orebodiea are sheet ikke masses ending 7,000 feet horisontak r and 900 feet de dip ; they vary in width f a few feet to 200 feet, averaging a 40 feet wide, The highest gold contents are closely associated with soft black oa naaeeous material and abundant a o sulfide (realgar and orpiment), Other or assoeiatad minerals are enop ite, stibnite ., § sem :=ite and cinnabar& Analyses of the ore shoo that, arsenic is the most abundant metal; ars c, . titan, and nercuz r the o y metals consistently present in all composite ore sales ; and mo 't a im, 'may and silver probably have o Lined usefulness as an indicator offO'sold ore.. . . Rock., . aw .rs fi ling$ and soill samples were spec1 gra .ca _ 'n a . a for • severel mews-'a--round the ore zones ; typical anomalies occur in fracture fillings from the no h-work:Lngs of the Getchhel]. P ee, along an Wit perpendicular ar to 'the strike of the ore shoots enic, t st , mot mercury, show the . greatest ; owto of enrichment, arsenic € d me u a enriched 100 tine s and to ,st r is . ached 10 times, :Studies indicate that a coincidence of these three metals is a good indicator for a . neae gold depoattm ;c anus without the aeo ppY tungsten and mend anomalies may indicate weak r €sralization or that gold` a eral nation _ is further r renewed f the sample site (tungsten andd mercury haloes ware depleted loser to the deposits} In gsn als, gsoca ca . work at the Ge` . D indicates that .. t st r amass occur ever the sold deposits and that these bias are not broad - halose but are restricted to the mineralized a„ The he metal valu .occur in oxidized rich material along fractures and bedding planes in barren b elk, lesser values in ealiche coatings on exposed book, . mod; ;lowest, but std a'ous, values in sails . IL i AA, Wa Hg Parts Per KjUion iron n the r ore ; as a red. ~ there Is i uffici t iron in the + de zone to fix &U the available s .c& Excess eri is probably r eins "` solution as the ne ativ ]y ge4 anion o a negatively 9 wed aerate c q i ee (HH2AO .L and RRA qh ) over a constant T s €d wide range in . Evaporation o c enat a: a. . water could precipitate c . The =all aya nts of arsenic soil over gold deposits could the result' of upward diffusion of Lei tae and ground water or the diffusion of r: gas from -rs c o entration i n bedeck, Abstract on e c 1m- a„ in the Bu wack r e Areas Eureka ,y: s:~~2 a.da~ by Av T. iesch and ' N3ola The ;e; er ail geology of the B WaCker Mine area mats of faulted Paleozoic sediments intruded by a gusts by sill N nera cation is ie g so : to limestone beds adjacent to steep crosscutting fissures (also mina rai )6 Me ore i s a c idiz lead-silver-gold replacements consisting largely Of .cane, ce site, piumbojawaite, and 3 o tev maw after galena. The oxidized ore contains is (bs antite) ; p sr Midas contain ate, galena, s eierite, and a oWritee Samples were taken from the upper 3 or 4 Inches of residual soils over the ' d ck in -e mine area. Lead and zinc were analyzed using dit izone and carbon tetrachloride ; arsenic was determined by the Gutseit method Involving the p r e r of gases evolved from n acidified sample solution through lead acetate to 'a confined spot on ma rs chloridee paper* 0 i . B. Ba xapatri Abstract on ¢a RLte of six .e is s Pathfinder Bioizeoch cal set: °' by EL V. W others. The authors report that arsenic has been used sucessful indicator for tatrahedr ite minsraa nation for cobalt for tungsten, for gold ., and for silvers, primarily in soil sampling. }L ever, they found that the arsenic content of different soil ho do v es greatly ; also, they point out that in many areas soils are poorly developed . As a result, they turned to biogeo amca, methods tean using arsenic as a pathfinder element in various mineralized areas of British Columbia. The n ical method used was based on Marsh's method of evolution of .. arsine, modified by Vars and Sedivees who react the arsine on a solution ' ' silver d thy di .ooarb ate in id s (Liede an e others., 1959). The mineraUzed areas consisted of lead-z e e s, arsenic-gold deposit and antimony.-,gold deposits ; a the deposits contained arsenic in va ting ., . °s a values w_ enriched in the soil horizon over deposits'wi.'-amounts significant amounts of arsenic (tom 3%) . FIo rever, over the deposits with less arsenic, there eras no significant arsenic anomaly he sonl samples .,. Bidg emica1. sampling revealed anomalous amounts of arsenic over l the deposits. The plant which had the greatest concentrations of arsenic was found td ',,be the Douglas Fairy the highest, arsenic content were found to "tips" of new* . growth. Senond-year g rtAi,, although anomalous, contained lesser Mounts of arsenic. Background v .uem of arsenic in the ash of Douglas Fir Utip&1 (f r= 'r 6- era sed areas) generally are less than I p arsenic, ae amount of arse contain in the various growths a to depend upon the time at which thes samples are' cdUected ; n erth,ess$ it is interesting to note that regales of when samples are collected ., they invariably are anemalously high in arsenic over mineralized areas that contain even all amounts of arsenic . S fir , No a-mama, T0G.0 1950 C chadst r : Word v Press$ London. Si so :4.J, and Piano., 1.L,, 1961 .,, O stry, 2nd ed. 4, McGrmt-11M Book p ', Tho. k New York. J ~ s B. S, i.Patriok CH 5 J dl x .A.,e, }1963 s A 1aborato method for deters, t soils dad rocks (no. 4) : Can. Geol. Survey, Paper 63493 l0pp*, . ILede wi,, D., Bowers.&, Jand Iffier, 0.L,, 1959, Ds Lion of arsenic troleum stocks and ylysts by evolution as arsine : Auto Chew@, v« 31, p. 2052-2055. nchs J6 J. `mod P k .av,, 0,, 19630 Method for dete a . ag arsenic (no. 3) - Can. Geol. grey, Paper 63r-8, 12 pp, Martinet, . 1956, Sadquan .tative determinations of traces of heavy metals in se e bar the confined spot" ; application the detsrAdmtion of :o in geoch cal prospecting for gold : p Geol. Gong. 20th `Session, P» 369..370, St ton, R, EQ and McDonald,, A.J. , 19624, Field dete .nation of ant in 0632. and sediment samples : Inst. M n, and Met,,, Bull. Noo 667, Trans* v. 71. P. 517-522* Stantoa , I, E., 19640. The field detemination of arsenic soils and scents : Boon, mil, v, 594, no. S., pe 1599-3.602, Bush, J.B. and took, D,, R. , The Chief de-3 g Area discoveries, East T ic, Utah; a ass history, m 1 , Bear Creek Mining studies and ezpIozatLon : Boon, Geol ., v. 5r, p« l507 1540, Cauneyg F . C, ated abhers,. 1953, A preliminary report of geothemical investigations in the Blackbird District Q Up & Gaol, Survey Open File Report ., Deeb ` 1953, 20pp, won, H,L..,a 1964, Geochemistry of rocks and related soil and vegetation in the Yellow Cat area, Grand County ., Utah o U.S., Geol. Surrey Bull . 176.6 . Cav er, Wa e 5., 19640 Arsenic in geoch e l gold expLloration : Reprint 64L73 A,1.4, E. Annual Meet, New York, Feb. 16-20, 1964, Chap an, HM ... 1958, Geoca ca3 exploration the Ken ,sima area, Al aska (: ) Q Col, Soc. . e ca 1, v. 69, P. 1751-1752@ ckson,, L. and others,, 1964, Goth is . anomalies in the lower plate of the Roberts Thrust near Co .tee, Nevada: U.S. C , Survey, P f. Paper 501-B p . 92-94. Erickson, R.L. and others ., 1964, Geochemical exploration near the Get hsl. t e, H ibolt County., Nevada : U.S. Geol. Survey Bu U . 1198 A., Grs er, C., 1958, Dispersion of tungsten and arsenic residual soil ( F ch) Soc. Francais M as alog. Cristalography Bull. v. 69, P. 1751-1752 .0 Hiss - continued Hawkers H, F,,$ 1954,. Geoch .cal prospecting investigations In the i eba lead-sine districts Nigeria : U.S. Geol. Survey Bull . 1000-B, p. 51-103.. James, G,H®, 1957, The geoch .cal dispersion of arsenic and antlmorq related to Sold mineraliza on in So hen Rhodesia: Geochemical Prospecting Research J Centre, Imperial College, London ., `echo a ® 12, Father, A. L., 19590 o hmical prospecting studies Sierra Leone D.14. Thesis, Imperial College, London, ar aaaw ., S,, 1960, 1, ch cal prospecting 'or gold-bearing lodes in the Kolar gold fields,, India : Int. G . Gong* ., 20th, Etplor, JA., $'mp, T, 3, p. 541-553- Nieseh, A.T. and Nola ., T.B., 1958, o h ,ical prospecting studies In the BMwhacker Mine area, Eureka District., Nevada : U.S. Geol. S reV Bull. 4V 1 -H, p, 397-408. Sai bury, CA. s, 1957, A geoch ical exploration for antimony outheastern Alaska : U .S. Geol. Survey Bull . 1024-H., p. 163-178. St arks, R_ and t sh, J. v 19592, Ge€ ch .i c a investigation of the wall rock oil 0 Friberg vein fo motions ( German) s Geologic,p v.8, no-4., p. 395-409. Was, H,V® and others.., 1964, The role of arsenic as a pathfinder in biegevch cal prospecting-. Boon, Cool .o v, 59, . 7, p. 2381-1385- Warren., H, V, and Delav .lt, L E., 1959, Pathfinding elements geochemica prospecting : .Int Geol. Gong., 20th, plor. Geochim,, Syinp, t,2, p. 255-260. WebbJ,S,, 19580 Observations on geoch ica . exploration tropical to ains: ,Into Cooks Gong. 0 Session, echimm , t, i, pa 3.43-1739,