This includes the ore depostis which are formed by a sedimentation process those are the clastic deposits with few examples of ore formed.

1. Ore Deposit Formed
By Clastic
Sedimentation

2. INTRODUCTION
 Weathering: In general weathering processes
acting upon rocks contributes to the overall
mineral resource may gives in five ways:
 Produce new minerals in site.
 Cause the redistribution of valuable elements.
 Released fine debris and chemical complexes.
 Released hard rocks into softer or useable rocks.
 Released of resistant minerals like gold.

3. TYPES OF PLACER
DEPOSITS
• Eluvial - Formal site of
destruction
• Deluvial - Formal down hill
• Proluvial - Accumulation formal
foot of a slope
• Alluvial - Placer carried out by
rivers of streams
• Laterial of beach - Formed along the
shores of lakes
seas, etc.
• Aeolian - By action of wind
• Glacial - By activities of
glacier
• Fossils placer/paleo placer - Those placer
deposits
buried under younger rocks.

4. PLACER DEPOSITS
 Hails in 1976 he defined placers as the
surficial mineral deposits formed by
mechanical concentration, commonly by
allurial but also by marine, aeoline, etc.of
heavy minerals particles such as gold from
weathered debris.

5. WITWATERSTRAND GOLD AND U
DEPOSITS IN REPLUBLIC SOUTH
OF AFRICA
 District lies in South Africa between
Johannesburg and Welkom shown in fig. 1

6. • “The Rand” is well known because of gold deposits.
• Yield 35 millions Kg of gold value at nearly $60 billion
• It is a fossils placer types of deposits.
• Most of the debris were transported from North, North
West and South-West.
• Viljoen Saagar in 1970 showed that types of
sedimentations.
• Later Kappel and Saager in 1974 studies of Isotypes
• Presence of isotopes contribute debris to the
witwatersrand basins.

7. STATIGRAPHY:
 The basemsent is Archean precambrian rocks
 The basement was unwrapped to steeply diapiric domes
represented by B in Fig 2

8. • It is made up of granite, granitic gneiss and greenstone
Terrances.
• The domain group lie next to the basement.
• Made up of district of quartz carbonate gold veins and
younger potassic granite bodies with accessories minerals,
uraninite.
• Witwatersrand super group overlie unconformably to
basement and domain group
• Made up of sequence of thin conglomerate and thick lava
flows
• It’s divided into two – lower and upper unit or west rand group
and central rand group.
• Lower west rand group of witwatersrand consist of shales,
quarzites, grits and conglomerate.

9. • Upper younger central rand group is 90% of
quarizite grits and rare shales.
• More gold bearing conglomerate.
• Tilting and erosion of Witwatersrand supergroung
and followed by igneous activity formed
ventersdrop supergroup.
• Erosion and subsidence ventersdrop formed
Transvaals supergroup.
• It is made up of thick sequence of clastic and
dolomite limestones.
• Bushveld age of igneous activities marked the end
of transvaal supergroup.
• Lastly, Karroo Supergroup was formed.

11. TECTONIC SETTING
• Large synclinorium of 400 km long and 150 km
wide elongated north Easternly direction.
• Frame of synclinorium was formed as a part of
complex fabric of regional and distinct scale
interference folding.
• Folding produce domes.
• Coincide of of anticlinal axes and intersected with
synclinal axes.
• Broad witwatersrand synclinal basin filled by
shallow broad intracratonic freshwater lake.
• Bottom accept the witwatersrand sediments.
• Synchlinorium is complicated.
• Several mine areas has abandoned.

13. SEDIMENTATION
• Goldfield constitute only a small fraction of Witwatersrand
sedimentations.
• Goldfield develop on Rand.
• The Rand fan shaped auriferous conglomerate systems
interleaved into the arenite thickness of the supergroup.
• These are six major goldfield mining areas in the district.
• Each presenting a wedge of sediment entry into the basin.
• Central Rand group consist series of sedimentation cycles
that range in thickness from 30 to 600 meters averaging 250
meters.
• Defined by basal unconformities mark by lag gravels
• It composed of major sand, minor conglomerate and include
siltstones, sandstones, etc.

14.  In Witwatersrand gold and Uranium placers are not
extracted occurs in at least four geologic sites in the
goldfields as given below along with figure 5.

15. • 1. In the fan head – In the sandy near the base of fluvial
pebbles supported conglomerates was filled by sand sized
heavy minerals grains from the sediments flux.
• 2. In mid-fan – In pyrite trough cross bedded sands in erosiion
deposition with Golds, Uraninite or foresets, in bottom set
spoons and sours.
• 3. In upper-fan base – in sheets of cross bedded sands by
winowing of quartz grains, leaving thin layers of heavy
minerals as lag deposits.
• 4. In the fan base – In carbonaceous layers on unconformeties
in scour pools and in algal mats which acted both as
mechanical riffle trops and as chemical trops.

16. • The ore bearing conglomerate strata in the Witwatersrand area
are know as reefs or bankets.
• The strata are not contineous as in a layer cake, but fans are
qualitatively similar
• The origin of the Witwatersrand conglomrate and quartzite was
based on gold origin.
• During depositions several environments have been included,
marines, shorelines, large ddeltas enclosed basins, etc.
• The Witwatersrand rocks have been mildly metamorphosed to
greenschist faciest.
• Except presence of quartz pebbles dynamics sedimentations.
• Stretched during metamorphism.
• Sphericity and roundnes has been retained
• Space between pebbles are occupied by locally abundant
pyrite, zircon, rutile, etc.

17. SOME OF THE ORE DEPOSITS
ARE:
Silica"Sand & Gravel"
 Sedimentary deposits are formed through the
erosion, transportation, and redeposition of
minerals that can survive the rigors of
transportation. The most common is silica, which
forms a number of materials, including silica
sand, sand and gravel, and flint. The precursor is
igneous quartz (e.g., in granite), and then the
sedimentary deposit may undergo metamorphism
and recementing to produce quartzite. Sand and
gravel for construction use is extremely common,
and production is more dependent on local
markets than availability

18.  Examples include the midwestern United States;
Badgeley Island, Ontario, Canada; Cheshire in
northwest England; certain areas of Belgium and the
Netherlands; Cape Flattery Island, Queensland,
Australia; and Sarawak, Malaysia. In many cases, the
use of local sand is based on price rather than
quality. The United States is the largest producer of
industrial sand, accounting for more than one quarter
of world production. Production of flint is much more
restricted, based largely on the chalk deposits of
southern England and northern France. . Certain
areas are, however, noted for producing industrial
sand that is sufficiently pure to be used in the
manufacture of glass, ceramics, sodium silicate, and
the like.

20. Clays:
 Several clays composed mainly of kaolinite are of
sedimentary origin. Premier deposits of ball clay,
the carbon content of which indicates that it was
deposited in swampy conditions, occur in the
Kentucky–Tennessee area of the United States,
Devon in southwest England, and the Czech
Republic. Flint clay, as produced commercially in
the United States, China, Australia, and Argentina,
is generally derived from the weathering of soil and
deposition in shallow basins. Fire clay or refractory
kaolin is a kaolinite material common in many
parts of the world, particularly in association with
coal deposits.

21.  A 400-km belt of kaolinite-rich rocks extends from
Aiken, South Carolina, to Eufaula, Alabama, and
includes areas supplying high- and medium-quality
kaolin and refractory kaolin. Another belt of kaolin,
bauxite, and bauxitic and kaolinitic clays extends
from western Tennessee into northeastern
Mississippi. Other areas include southwest
England and over the English Channel into France
(kaolin and ball clay); various parts of the Czech
Republic (kaolin and ball clay); Spain; the Amazon
Basin in Brazil (bauxite, kaolin); Japan (kaolin,
refractory clay, roseki, and toseki); and
Queensland, Australia (bauxite, kaolin).

22.  Volcanic ash deposited as part of a sedimentary
sequence eventually forms sodium or calcium
bentonite. Important bentonite deposits occur in
the United States in the Wyoming–Montana region
(sodium-based bentonite) and in the Mississippi–
Texas region (calcium-based). Almost 40% of the
world’s bentonite production is from these and
some smaller deposits in the United States. More
modest tonnages are produced in Mexico and
Canada. In Europe, bentonite is mined on Milos
Island in Greece, Turkey, Sardinia in Italy, Bavaria
in Germany, southwestern England, Ukraine, and
Spain.

23. clay Volcanic Ash

24. Titanium:
 Titanium is found in many minerals. Ilmenite
(FeTiO3) and rutile (TiO2) are the most important
sources of titanium. Ilmenite provides about 90%
of the titanium used every year. It is estimated that
the resources of ilmenite in the world contain 1
billion tons of titanium dioxide. The estimated
resources of rutile in the world contain about 230
million tons of titanium dioxide. Rutile and ilmenite
are extracted from sands that may contain only a
few percent by weight of these minerals. After the
valuable minerals are separated, the remaining
sands are returned to the deposit and the land
recultivated.

25.  In the United States, titanium-rich sands are
mined in Florida and Virginia. Even though the
United States mines and processes titanium and
titanium dioxide, it still imports significant amounts
of both. Metallic titanium is imported from Russia
(36%), Japan (36%), Kazakhstan (25%), and
other nations (3%). TiO2 pigment for paint is
imported from Canada (33%), Germany (12%),
France (8%), Spain (6%), and other nations
(36%).
 Most titanium is used in its oxide form. TiO2 is a
white pigment used in paint, varnishes and
lacquers (49%), plastics (25%), paper (16%), and
other products such as fabrics, printing inks,
roofing granules, and special coated fabrics.

26. Titanium

27. Zirconium Minerals (Rare Earths):
 Placer and palaeo-placer mineral deposits are
important sources of heavy minerals such as
ilmenite, rutile, and zircon. The rare earth sources
monazite and xenotime are invariably associated
with the mineral sands deposits. Many
titanium/zirconium/rare earth mineral deposits are
Tertiary and Quaternary in age because this was
a period of geological uplift that provided the
correct conditions for accumulation, plus the fact
that older examples have been destroyed.

28.  Most placer deposits are in marine sand deposits
along or near present coastlines, where they are
concentrated by a combination of tidal action,
longshore currents, waves, winds, and natural
traps such as a cape. Most commercial placer
deposits are recent beaches and dunes along
coastlines, with some older deposits being
stranded by land elevation or ocean withdrawal.
Important areas include the east and west coasts of
Australia, parts of Florida and Georgia in the
southeastern United States, around Richards Bay
in South Africa, Sierra Leone in Africa, the coastal
areas of Tamil Nadu and Kerala states in southern
India extending into eastern Sri Lanka, and the
coastal areas of Brazil.

29. Zirconium mineral

30. CONCLUSION
• Another aspect of gold and uranium occurrence in Rand
sediment concerns local post depositional re-distribution of
those elements especially Uranium. Near the end of World
War second, when interest in fissionable materials was
gaining momentum, it was discovered that the frequently
mentioned ‘Carbon’ of the Rand ores was actually a Uraninite
– Carbon agregate earlier, but improperly called Thucholite
(Davidson and Bowie 1951). Mineraloid whose very name
describe its Thorium, Uranium, Carbon, Hydrogen and
Oxygen composition.

31. • Serious mining in the Witwatersrand district began
in 1886 when the ‘Gold Rush’ started this activity.
Since that time, many mines have been developed
along the 400kms of strike of the Witwatersrand
conglomerate, Beds on the northernly and
southwesternly sites of the Witwatersrand basin.
Several mines are operating at depts of more than
300kms. The east Rand property mine operates at
the dept of about 3.5kms. The western deeps mine
near Carletonville, the deepest in the world, has
reached nearly 4Kms. Even deeper mines are
planned to reach further down along ore bearing
strata, descent now locally more than 30Kms
downdip.

32. THANK YOU