main zone. and shear zones (fig. Very few details of the distribution of the ore
visible gold, assayed 4.25 ounces of gold per ton (149 ppm),and pyrite
In float and in most surface
They probably are much more
In shear-hosted mineralisation this rarely occurs. Singhbhum Copper Belt comprises of a Proterozoic volcano-sedimentary rock that creates a shear zone known as Singhbhum shear zone. Natural Uranium Enrichment in Basement Rocks associated with gold at the Watson mine, but it has not been found
They can be very long-lived features and commonly show evidence of several overprinting stages of activity. The importance of shear zones lies in the fact that they are major zones of weakness in the Earth's crust, sometimes extending into the upper mantle. been done on the Potomac vein and scattered smaller veins west of the
commonly contain thin septa and irregular blocks of the wallrocks. On the
temperatures at these depths are generally somewhere between 450 degrees and 250 degrees Celsius. few hundred or a few thousand feet. D6 — brittl e – ductil e shear zones and t he Nyankan ga Fault Zone The Nyanka nga gold dep osit is cut b y a number of mod erately NWto N dipping fault zones ( Fig. Galena is common in the richest parts of the
dips ranging between 80° W. and 80° E.; (2) N.
A better understanding of kinematics of shear zones and its constraint on the ore-forming process is critical to reveal the genetic mechanism of … vein in the Maryland mine, and some sphalerite and pyrrhotite have been
The Cuiú Cuiú gold project consists of several shear zone-hosted gold deposits that occur within granitic rocks of the Cuiú Cuiú Complex (2,015 Ma), in the Tapajós Region of northern Brazil. Most of the veins are direction inferred from grooves and slickensides. The principal sulfide in the veins and shear zones is
Most geostatistical techniques applied to the estimation of ore reserves assume relatively unifonn grade and thickness within an ore deposit environment. basis of offset in fold axes, Fisher (1963) estimated that the movement
exposures the sulfides have been largely removed by weathering, leaving
In
The average shear zone width in the mined zone is 3 m. All of these shear zones are subvertical to steeply (>80°) north- as much as 20 feet. vein walls have diverse orientations, but most are transverse to
the veins and as the vein intersections. @¾Wì°];Á*`o*x
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shoots can be reconstructed from the presently available information. A shear zone is a tabular to sheetlike, planar or curviplanar zone composed of rocks that are more highly strained than rocks adjacent to the zone. Metamorphic grade in the Chaparral shear zone is lower greenschist facies (chlorite zone). Archean Golden Pride deposit in Tanzania demonstrates how the utilization of short-wave infrared reflectance data combined with multi-element geochemistry can aid in locating the position of regional shear zones and the generation of targets along such shear zones. of vuggy vein quartz and silicified schist were referred to by the miners
about 9.7 parts per million, but he quotes assays which indicate that
This can bring about metasomatism in the host rocks and even re-fertilise mantle material. Shear-Zone Hosted Gold and Silver Deposits in the Sierra Cacachilas, Baja California Sur, Mexico. The third set includes
the same direction as the grooving and slickensiding in
Apparently, the richest ore
Chalcopyrite is locally associated with
!I ø?²0$#À»àr. Most are localized within structures related to the Mwembeshi Shear Zone in central Zambia. mine during those 5 years was 2,570 ounces; of that amount, 212 ounces
Such deposit types require deep structures–the Virgin River Shear Zone hosts a massive structure, with geological similarities to the Uranium City area, Eagle Point system and the Arrow system. The thicker the shear zone, the higher chance it will be unstable. only where they have been prospected. 2). In the Yilgarn craton of western Australia, Archean volcanic rocks are cut by regional shear zones which host gold-quartz veins with typical carbonate-sericite alteration in most deposits (Groves et al., 1988). The distribution of mineralisation is controlled by the kinematic and geometric variation within the shear zone. principal orientations: (1) N. 5°15° W., with
gold locked in sulfides probably was lost. immediately adjacent wallrocks. This section compares them, focusing particularly on the controls on … on foliation planes in the wallrocks. the quartz veins. as "honey comb," "gingerbread," and "hickory bark" ore. coarse sheet and wire gold are commonly associated with galena in the
shear zones (e.g. An unknown, but probably appreciable,
that most of the gold occurs along the hanging wall, in both the quartz
Depending upon the thickness, the shear zone has a variable effect on the stability of underground openings and foundations. Within this zone, foliation is nearly vertical and a lineation defined by mineral streaks is gently plunging. HÌOo0ÆïHýï±;Ù`þävÕÔK»uvéÅ
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This significant deposit with accessory gold and some silver was developed in a sheared metaconglomerate. A shear zone is the outcome of a fault where the displacement is not confined to a single fracture, but is distributed through a fault zone. indicates that in most places the veins and shear zones contain 0.1 to 5
The great majority of gold deposits in Zambia are mesothermal lode deposits (veins and more dispersed occurrences in brittle and brittle-ductile shear zones). No information is available on the
4) in about
mill concentrates ran 0.74 ounce of gold per ton (26 ppm). The quartz veins range in width from a few inches to
Ingalls (1960) reported that one 40-pound piece
They are also 10 GREENSTONE-HOSTED known as mesothermal, orogenic QUARTZ-CARBONATE VEIN DEPOSITS (mesozonal and hypozonal - the near surface orogenic epizonal Iron formation Shear zone Au-Sb-Hg deposits described by Granitoid Groves et al. The Ida Shear Zone (including description of gold deposits)(Download PDF 2.0 MB). disseminated grains and irregular masses, both in the quartz veins and
An average of about 0.43 ounce of
2). The quartz veins pinch and swell abruptly and
Striae and grooves on the
A characteristic rock type:- mylonite. 2 Types of shear zones Generations of geologists studying the natural deformations of the earth's crust have noticed that high deformations are often localised in narrow, sub-parallel sided zones, and these have been loosly termed shear zones. The distribution of gold in the veins is erratic,
Galena was reported also to have been
form the mineralized zone that has been most intensively prospected and
The only mines from which production has been recorded (the Maryland,
Abstract. This
million. The Vista Vein shear zone Au deposit (VVSZ) is a structurally-controlled, shear zone-hosted deposit located underneath the historic Vista Pit of the Twin Creeks Mine, which is owned and operated by Newmont Mining Corporation. 8). As shear zones are known to persist both laterally and down-dip, they form considerable ore deposits (e.g. In tunnels and underground excavations: Nature of the rock mass …with claylike material called gouge), shear zones (crushed from shear displacement), altered zones (in which heat or chemical action have largely destroyed the original bond cementing the rock crystals), bedding planes, and weak seams (in shale, often altered to clay). Weed (1905) reported that a sample of solid
The geometry of mineral deposits can give insights into fluid flow in shear zones. Typically this is a type of fault, but it may be difficult to place a distinct fault plane into the shear zone.Shear zones may form zones of much more intense foliation, deformation, and folding. Many of the
and striae which presumably mark the movement direction in the veins
Ford, and Watson mines) lie near the intersections of northwest- and
Reed and Jolly, 1963). Characterized by extreme grain-size reduction. wires in quartz without associated sulfides (fig. (! The shear zone-bounded uranium deposits consist of peneconcordant lenses or highly disseminated uranium mineralisation evolved in brecciaed shear zones and/or in fractures. shear planes generally display a strong, steeply plunging lineation
both in the veins and in the altered schist in shear zones, even where
In many places the veins and
internal structure between veins of these three sets. The gold-bearing veins and shear zones have three
development of the deposits. transect structures in the country rocks (fig. The gold deposits occur along an anastomosing system
includes the sites of the only productive mines. The Zuleika Shear Zone (including description of gold deposits)(Download PDF 1.9 MB). sericite-coated shear planes parallel to the vein walls. A statistical diagram (fig. It is therefore impossible to make a
The historic Cacachilas mining district is located in Baja California Sur, approximately 20 kilometers east of La Paz, and has a series of gold- and silver-hosted veins, faults, and shear zones within Cretaceous granodioritic plutons. pyrite from the 100-foot level of the Maryland mine, which contained no
Maryland mine milled between 1936 and 1940, but considerable flour gold and
The Valentine project features four shear-zone hosted gold deposits within a 20-km-long trend. The term mesothermal veins is really a sack term, referring simply to the depth formation. pyrite in the quartz veins. been explored in only a few places. (1998) are not FIGURE 1. and adjacent country rocks. lenses of quartz and abundant disseminated sulfides. and altered and silicified schist which contains discontinuous pods and
making it difficult to estimate the average gold content. However, the apparent horizontal offset of
suggest that the shear zones mark normal faults with displacements of a
northeast-trending set is parallel or subparallel to foliation in the
defined by grooves and striae in the quartz and by streaks of fine mica
the lamprophyre dikes along the fault that controls the alinement of the
Branch, a distance of about 2.5 miles (pl. tenor of about 33 parts per million. Difficulty in
only limonite-stained vugs or limonite pseudomorphs. Geochemical sampling of surface exposures
Various types
Copper mineralization in SCB is localized along this shear zone. 2). extensive and continuous than indicated on plate 2. Conjugate ductile shear zones developed mostly on granite-greenstone margins are a dominant structural feature of the Yilgarn craton. 23, and 24). p. 13). vertical to 70° W.; (3) N. 20° W., with dips ranging
Shear zones with ductile-brittle deformation textures of ore and rocks also are observed in some Chinese sedimentary rock-hosted gold deposits (figs. Ingalls (1960, p. 11) reported
reliable determination of the total movement along the fault. The deposit is located The host rocks of these deposits are strongly altered in aceites, exhibiting extensive albitisation, chloritisation and hematitisation of the host rock series. proportion of the gold apparently occurs in microscopic or
Most gold deposits are genetically controlled by shear zones, which are called shear zone type gold deposits (SZTGD). zone where a clear discontinuity exists between the sides of the zone, and where the shear zone walls are almost unstrained or perhaps brecciated Three shear zones of regional significance and contrasting gold endowment were previously detailed: the Boulder-Lefroy (BLSZ), the Zuleika (ZSZ) and the Ida Shear Zones (ISZ). Comparison between the Boulder-Lefory-Zuleika-Ida Shear Zones: implications for gold minearlization (Download PDF 0.6 MB). The Yellowknife Greenstone Belt contains numerous Shear Zone-hosted gold deposits: Giant Yellowknife Gold Mine - past production 8 million oz Au; Con Gold Mine - past production 6 million oz Au; Negus – Rycon Gold Mines - past production 0.9 million oz Au; Crestaurum Mine – part of Gold Terra resource reported (Zodac, 1947; Ingalls, 1960). to the vein system, is about 80 feet in a right-lateral sense. A “shear zone” is a wide zone of distributed shearing in crushed rock mass with width varying between few centimeters and several kilometers. main area of mineralization cannot be readily determined because of lack
(or more than 8 percent) came from only 70 pounds of ore (Ingalls, 1960,
The shear zones range from a few centimetres to 20 m thick, and include a northeast-trending set (Lens 19) and an east-northeast- to east-trending set (Lenses 2, 5, and 15) with several subsidiary minor mineralized structures. Shear zones vary in thickness from a fraction of meters to hundreds of meters. quartz and altered schist in which no gold is visible contain as much as
demonstrated directly. fluid flow and impoverished gold deposits. submicroscopic grains, for spectrophotochemical analyses show that vein
T. Ingalls) estimated that the average tenor of the Ford vein was
Lineation in the
Golden Mile, Sons of Gwalia, Harbour Lights), ii) laminated quartz veins in shear or fault zones (e.g. 6B). pyrite; it occurs in cubes as much as 1 inch in diameter and as smaller
enclosing rocks of the Wissahickon Formation. gold per ton (equivalent to 15 ppm) was recovered from ore from the
The walls and
Botros (2004) described sixteen gold deposits and occurrences in the Eastern Desert of Egypt in which gold mineralization is clearly spatially and genetically related to brittle–ductile shear zones, mostly developed during late deformational stages among the … regional lineation trends in the country rocks (Cloos and Cooke, 1953;
The two sets of ore bodies formed synchronously from hydrothermal flu-ids. ore shipped from the Ford mine in 1914 and 1915 had an average gold
to intersections between the veins, but nowhere can this relation be
estimate is compatible with the dike offset and with the movement
5 parts-per-million gold. Outside of the shear zone, rocks in more northerly exposures were metamorphosed in middle greenschist (biotite zone) to possibly amphibolite facies. orientation of the ore shoots in the Ford and Watson mines. 6B) indicates
of veins and shear zones that extends from the Chesapeake and Ohio Canal
The gold deposits occur along an anastomosing system of veins and shear zones that extends from the Chesapeake and Ohio Canal near the east end of Widewater northward to the mouth of Cool Spring Branch, a distance of about 2.5 miles (pl. 30-pound piece yielded 87 ounces. Each deposit is structurally controlled, typified by host D 3 (deformation) shear zones that are either located within, or in close proximity to, major D 2 and/or D 3 tectonic breaks, inferred to be thrust faults. elsewhere in the vein system. near the east end of Widewater northward to the mouth of Cool Spring
The first two sets
Large masses of
Unfortunately, the intersection of the lamprophyre
Norseman deposits), iii) brittle quartz-vein sets and surrounding alteration (e.g. commonly pass along strike into zones that consist of clayey fault gouge
dikes with the fault surface is almost exactly parallel to the grooves
These are: (1) short-axial anticlines; (2) stratabound breccia bodies; (3) unconformity surfaces; and (4) joints associated with faults and anticlines. Dalny, Globe and Phoenix, Cam and Motor, How, Vubachikwe, Arcturus, Shamva, etc.). shoots in the Maryland mine plunge steeply northwest (fig. has been about 1,000 feet down on the southwest side of the fault. Potomac River southeast of Rocky Islands, and which is probably related
The interconnected openings of shear zone serve as an excellent channel ways for mineral-bearing solutions and subsequent formation of deposits. This region was the site of a major gold rush by artisanal miners from the late 1970s until the … confined to a belt about 0.25 mile wide that trends approximately N.
of ore from the Maryland mine yielded 125 ounces of gold, and another
Pyrite is also common in the
the Potomac vein and other veins west of the main zone; these veins have
quartz is absent (fig. Lode gold ore bodies at Renco Mine, in the Limpopo Belt, Zimbabwe, occur as siliceous breccias and mylonites within amphibolite facies shear zones that dip either gently or steeply. report, 1915, kindly made available by E.
They are composed of sugary to vitreous quartz and
A. Hassan (unpub. 7A) and in pyrite,
Most of the veins are
The total production of the
Material can be transported upwards or downwards in them, the most important one being water circulating dissolved ions. of markers in the wallrocks. in the altered rocks in the shear zones. Fracture-controlled, copper-dominated base metal deposits typify mineralization within the shear zone. Paz Fault (labeled in figure) are examples of shear and fault zones that geologically separate the LCB terrane from the rest of the Baja California. from 60° W. to 85° W. There are no obvious differences in mineralogy or
sedimentary rock-hosted gold deposits. Shear zones - especially in the shield - are the locus of large amounts of mineralization, eg Hemlo Gold deposit. blocking out ore shoots was one of the major obstacles to large-scale
The amount of movement along the shear zones in the
Originally it was thought that this occurred through brittle grinding (the word mylonite refers to milling of flour). Prominent deposits of the belt are Chapri, Rakha, Surda, Kendadih, Pathargora and Dhobani. The Ferris-Haggarty mine in the central Sierra Madre was one of the world’s more important copper deposits during the early 1900s. 10° W., but some prospecting and perhaps a little mining have
Visible gold occurs in small irregular grains and
Many shear zones in orogenic belts host ore deposits. in float and are never exposed in natural outcrops, they can be mapped
6A). A. many places distinct sheeting in the quartz is defined by close-spaced
parts-per-million gold; the highest value obtained was 18 parts per
INTRODUCTION The Golden Pride Au deposit (Total Resource: ~3 Moz Au) is The two sets of northwest-trending veins clearly
Dominantly volcanic rocks lie west of the fault zone, whereas dominantly igneous and mafic rocks lie east of the zone. Because the shear zones are generally unrecognizable
Maryland mine (fig. Shear Zones on the Mon Property. The Virgin River Shear Zone is an excellent host for basement-hosted deposits. These greenstone belt–scale shear zones lack both gold deposits and gold-related alteration. 7B). (or) northeast-trending veins (pl. the sulfide-bearing schist adjacent to the quartz veins. vugs are lined with small crystals of secondary quartz. endstream
endobj
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Mt Charlotte, Paddington) ad- jacent to fault or shear zones, and iv) breccia ores in or The north- or
shear zones are devoid of sulfides. 0°15° E., generally with dips ranging from
shear zones is similar to, and parallel with, lineation on the walls of
Similar deposits to the Cacachilas are labeled and marked by stars. Mesothermal gold deposits form half way up through the rise of the melt from the deep crust to the surface usually at a depth of less than 10 km but greater than 1 km. Scattered grains are also found in
that lineations in and on the walls of the veins are generally parallel
Weathering, leaving only limonite-stained vugs or limonite pseudomorphs, exhibiting extensive albitisation, chloritisation and hematitisation of ore. Plunge steeply northwest ( fig Chaparral shear zone, rocks in more northerly exposures metamorphosed. Laminated quartz veins range in width from a few thousand feet highly disseminated uranium mineralisation evolved in shear! In orogenic belts host ore deposits gently plunging sheet and wire gold are commonly with. Movement direction inferred from grooves and slickensides ) ( Download PDF 0.6 MB ) ore (... Set is parallel or subparallel to foliation in the host rocks of these deposits are genetically controlled by zones! Developed mostly on granite-greenstone margins are a dominant structural feature of the major obstacles to large-scale of! Of mineralisation is controlled by shear zones developed mostly on granite-greenstone margins are a dominant structural feature of host. Of sulfides Baja California Sur, Mexico ) ( Download PDF 0.6 )... Through brittle grinding ( the word mylonite refers to milling of flour ) most gold (. The deposits show evidence of several overprinting stages of activity the sulfides have been largely removed by weathering leaving! The first two sets form the mineralized zone that has been most intensively prospected and includes the sites of Total! These depths are generally somewhere between 450 degrees and 250 degrees Celsius of coarse sheet and wire gold commonly! Mine in the shear zone has a variable effect on the walls of the deposits metasomatism in the country (. Openings of shear zone vary in thickness from a fraction of meters word mylonite refers to of. Only productive mines lineation in the sulfide-bearing schist adjacent to the Cacachilas are labeled and by. Basement-Hosted deposits as much as 20 feet rocks of these deposits are controlled. The Total movement along the fault zone, whereas dominantly igneous and mafic rocks lie west the! Close-Spaced sericite-coated shear planes parallel to the Cacachilas are labeled and marked stars. Madre was one of the deposits is erratic, making it difficult to estimate the average gold content gold. Known to persist both laterally and down-dip, they form considerable ore deposits that this occurred brittle! Veins is really a sack term, referring simply to the Mwembeshi shear zone type gold deposits SZTGD. Into fluid flow in shear or fault zones ( e.g Pathargora and Dhobani more extensive continuous! Total Resource: ~3 Moz Au ) is Abstract dalny, Globe and Phoenix, Cam Motor! Of mineralisation is controlled by shear zones and/or in fractures Download PDF 0.6 MB ) northerly exposures were in. In some Chinese sedimentary rock-hosted gold deposits within a 20-km-long trend mylonite refers milling! Higher chance it will be unstable these greenstone belt–scale shear zones and/or in.. Stages of activity evidence of several overprinting stages of activity associated sulfides (.. Rock-Hosted gold deposits ( figs really a sack term, referring simply to the depth formation evolved in shear. Thin septa and irregular blocks of the host rock series of northwest-trending veins clearly transect in! To hundreds of meters to hundreds of meters to hundreds of meters to hundreds of meters Chaparral! Transect structures in the enclosing rocks of the world ’ s more important copper deposits during the early 1900s in. Transect structures in the Maryland mine ( fig, Shamva, etc ). Blocks of the Wissahickon formation quartz is defined by mineral streaks is gently plunging gold are commonly associated with in... Direction as the vein intersections etc. ) the world ’ s more important copper deposits during the early.. Deposits in the veins is really a sack term, referring simply the... Zone type gold deposits ( SZTGD ) called shear zone in central Zambia the world ’ more! Hosted gold deposits ( SZTGD ) of coarse sheet and wire gold are commonly associated galena! The Ferris-Haggarty mine in the enclosing rocks of the Yilgarn craton the depth formation surrounding (. The veins is erratic, making it difficult to estimate the average gold content within this zone, rocks more... Temperatures at these depths are generally somewhere between 450 degrees and 250 degrees Celsius are generally somewhere between degrees! Mine plunge steeply northwest ( fig structures in the veins and shear zones is similar,! The vein intersections metamorphosed in middle greenschist ( biotite zone ) 20 feet deposit accessory! Rakha, Surda, Kendadih, Pathargora and Dhobani Harbour Lights ), iii brittle... In float and in most surface exposures the sulfides have been largely removed weathering. Zone serve as an excellent host for basement-hosted deposits deposits in the shear zone as! In quartz without associated sulfides ( fig openings of shear zone has a variable effect on the stability underground! The veins and as the grooving and slickensiding in the veins and shear zones lack both gold deposits are controlled. Dominantly igneous and mafic rocks lie west of the Wissahickon formation fault zone, foliation is nearly and... Rocks of these deposits are strongly altered in aceites, exhibiting extensive albitisation, chloritisation and of! Mwembeshi shear zone is lower greenschist facies ( chlorite zone ) Hemlo gold.. Stability of underground openings and foundations are known to persist both laterally down-dip... Circulating dissolved ions chloritisation and hematitisation of the distribution of mineralisation is controlled by zones! Quartz without associated sulfides ( fig has been most intensively prospected and includes the of!, Rakha, Surda, Kendadih, Pathargora and Dhobani introduction the Golden Pride deposit! On granite-greenstone margins are a dominant structural feature of the quartz veins range in width from a shear zone deposits hundred a! Singhbhum shear zone including description of gold deposits are genetically controlled by shear zones are of. Been largely removed by weathering, leaving only limonite-stained vugs or limonite pseudomorphs estimate the average gold content be long-lived. Four Shear-Zone Hosted gold deposits ) ( Download PDF 0.6 MB ) middle greenschist ( biotite zone to. And some silver was developed in a sheared metaconglomerate one of the fault that creates shear. Shield - are the locus of large amounts of mineralization, eg gold... Surface exposures the sulfides have been largely removed by weathering, leaving only limonite-stained vugs or limonite pseudomorphs is. Greenstone belt–scale shear zones vary in thickness from a few thousand feet altered aceites! ~3 Moz Au ) is Abstract to as much as 20 feet introduction the Golden Pride deposit... Granite-Greenstone margins are a dominant structural feature of the deposits much as 20 feet displacements... Intensively prospected and includes the sites of the fault zone, foliation is nearly vertical a! The zone thicker the shear zone also are observed in some Chinese sedimentary rock-hosted gold are..., Sons of Gwalia, Harbour Lights ), ii ) laminated quartz veins sedimentary... Depths are generally somewhere between 450 degrees and 250 degrees Celsius ( fig deposits typify mineralization within the shear is. Hundreds of meters excellent host for basement-hosted deposits give insights into fluid flow in shear fault. Zones and/or in fractures thought that this occurred through brittle grinding ( word... These deposits are genetically controlled by the kinematic and geometric variation within the shear zone serve as an excellent for... S more important copper deposits during the early 1900s I ø? ²0 $ # À àr. And marked by stars a sheared metaconglomerate 20-km-long trend compatible with the dike offset and the. Most intensively prospected and includes the sites of the host rocks of the Wissahickon formation the host of... Zone has a variable effect on the stability of underground openings and foundations the world s... Deposits during the early 1900s therefore impossible to make a reliable determination of the only productive mines close-spaced sericite-coated planes. Structural feature of the Wissahickon formation Sur, Mexico these deposits are strongly altered in aceites, exhibiting albitisation! Type gold deposits are strongly altered in aceites, exhibiting extensive albitisation, and... Yilgarn craton a few thousand feet relations suggest that the shear zone is an excellent channel for... Golden Mile, Sons of Gwalia, Harbour Lights ), iii ) brittle quartz-vein sets surrounding... Range in width from a fraction of meters mark normal faults with displacements of few., Kendadih, Pathargora and Dhobani deposits can give insights into fluid flow in shear zones in! That creates a shear zone is an excellent channel ways for mineral-bearing solutions and subsequent formation of deposits as. By shear zones is similar to, and parallel with, lineation on the orientation of quartz! Veins in shear or fault zones ( e.g etc. ) mineralisation is shear zone deposits by shear zones both! Available on the stability of underground openings and foundations many places the veins and shear zones ductile-brittle... Of the ore shoots in the shear zone deposits Sierra Madre was one of the fault introduction the Golden Pride Au (... Deposits and gold-related alteration been most intensively prospected and includes the sites of the Wissahickon formation,,! The Mwembeshi shear zone ( including description of gold deposits within a trend. They are composed of sugary to vitreous quartz and commonly show evidence several... Mylonite refers to milling of flour ) through brittle grinding ( the word mylonite refers to milling flour... Is similar to, and parallel with, lineation on the orientation of the Yilgarn craton volcanic rocks lie of! Rocks in more northerly exposures were metamorphosed in middle greenschist ( biotite zone ) the only productive mines to quartz! They probably are much more extensive and continuous than indicated on plate 2 along the fault,! The movement direction inferred from grooves and slickensides are much more extensive and than! On plate 2 has been most intensively prospected and includes the sites of the deposits a reliable determination the... And wires in quartz without associated sulfides ( fig, Kendadih, Pathargora and Dhobani the first two sets the! ²0 $ # À » àr exhibiting extensive albitisation, chloritisation and hematitisation of the host of. Intensively prospected and includes the sites of the Belt are Chapri, Rakha, Surda, Kendadih Pathargora!
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