THE PRESENTATION OF MY GRADUATION PROJECT

A NEW HIGHLIGHT ON THE GENESIS AND THE GEOCHEMISTRY OF
THE MANGANESE DEPOSITS, OF THE UM BOGMA FORMATION, IN
THE UM BOGMA REGION, WEST CENTRAL SINAI, EGYPT: A REVIEW
By:
Metwally Hamza Metwally
-Graduation Project-

1
Mn Ore Facies
Geologic Setting
Introduction
Stratigraphy of
Mn-bearing Um
Bogma formation
Stratigraphic
distribution of
Mn-Fe deposits
Geochemistry
Presentation
Content

2
Manganese (Mn) is the most remarkable and essential ore (in a metal form) to
iron and steel production, due to some properties which are not existed in other
ores, such as its ability to act as sulfur-fixing, deoxidizing, alloying metal. In
the process of the steel making and production, Mn ore is the most demand,
presently in the range of 85% to 90% of the total. Such manganese ferroalloys,
which are consisted of various grades ferromanganese and silicomanganese,
are used provide most of this key ingredient to iron and steel making. Also, it’s
widely used as products for construction, machines making, and in a
transportation. Mn ore is also a key component of certain widely used
aluminum alloys, and in oxide form, dry cell batteries. In addition to other
uses, as using as plant fertilizers, animal feed, and colorants for brick.

3
1.1) Mn deposits in space and time
Economic manganese deposits had been appeared for first time, only around 3000
Ma, in the iron ore group in India (3200–2950 Ma).
Fe deposits are most dominant during the Archean Age, counter to the Mn deposits
which had been restrained in such time.
The manganese metallogenesis during the Archean period was highly selective in
space, because the occurrence of manganese deposits during this time was restricted
to only five places, of which three in India and two in Brazil.

4
A lot of manganese deposits of Archean age had been deposited in a shallow water
conditions (environments) in an Archean intracratonic basin (Roy, 1987).
1.2) Deposition of Mn worldwide
A lot of stratiform ore deposits of Archean age have been derived from endogenic
sources, but manganese deposits do not indicate such a derivation (Franklin, 1981;
Gross, 1980, 1983; James and Trendall, 1982).
All manganese deposits of Archean age had been deposited in shallow-water
intracratonic basins which are of Proterozoic in character.

5
In general, there is a rarity in manganese deposits during the Archean age, and total
absence in the earlier part (Roy, 1987). This is because the paucity of economic
concentrations of manganese deposits in volcanic/hydrothermal exhalations during
this time and in the early stages of the Earth’s planet development.
1.3) Phanerozoic supremacy
While most of volcanogenic/hydrothermal massive sulfide deposits of Proterozoic,
in addition to Phanerozoic are considered to have been enriched in manganese
(Stumpfl, 1979; Roy, 1981), but that of Archean age do not include such a
manganese, because the magma and the oceanic sediments of the Archean age
were poor in manganese and lead (Sangster, 1976).

6
In the Precambrian eon, exactly in Proterozoic era, the oxygen was too much,
thanks to the photosynthesizing prokaryotes which were able to produce the
oxygen, and then the atmosphere and the hydrosphere were sufficiently
oxygenated to support the sufficient biota.
Consequently, the iron-formation reached its crest of development in the early
Proterozoic period. During the Proterozoic time, manganese deposits started to
develop on a substantially large scale.
1.4) Role of oxygen

7
1.5) Role of tectonic plates
In the Phanerozoic eon, plate motions largely controlled the tectonic regime and
played an important role in the formation of the ore deposits of different types
and their specific localization (Roy, 1987).
A variety of ores of that time, are produced by volcanism and hydrothermal activity
in diverging and converging plate boundaries
By and large, the manganese deposits of the Paleozoic era are much less developed
than those in the rest of Phanerozoic eon, and there is a large-scale development of
sedimentary manganese deposits in the Mesozoic era.

8
1.6) Role of biological activity
The most interesting mechanism for concentration and deposition of manganese ore
deposits in the duration of Phanerozoic eon has been suggested by Frakes and
Bolton (1984) drawing critically from the concept of high sea-level stand and
attendant anoxia during marine transgression, leading to manganese
concentration.
Small to moderate size volcanogenic-sedimentary and hydrothermal manganese
deposits are common in the geologic record of the Cenozoic era (such an example
of Oriente Province, Cuba).

9
During the Ordovician, the Silurian, and the Devonian time span Egypt was
confined by epeiric sea (Semtner and Klitzsch, 1994).
1.7) Role of drifting processes
During the Lower Carboniferous, there were two successive phases of the
previously mentioned sea, the transgression and the regression, the first had
been occurred over the study area
depositing Mn ore bearing Um Bogma Formation (under study in the present
work), and the last had been occurred after the first phase depositing the overlying
fluviomarine Abu Thora Formation.

10
Manganese ore deposits found in many parts of Egypt, but only in a few
places do they occur in sufficient quantity to be of high commercial
value, e.g., Um Bogma area in west central Sinai, Gebel Abu Shaar El
Qibli in the southern part of Esh El Mellaha range north of Hurghada,
Gebel Elba of Halaib district in the southern part of the Eastern Desert
and as minor occurrences in Abu Ghosun and Ras Banas in Southern
Eastern Desert. The most important and exploitable manganese deposits
are those of Um Bogma area where the ferromanganese alloys are
manufactured from the raw materials nearby Abu Zneima and the
manganese deposits are mainly concentrated in the Carboniferous Um
Bogma Formation, mainly in its lower dolomitic part.
We will focus on that of Um Bogma
Mn Deposits of Egypt

11
Kora (1984) had subdivided these exposures depending on their field
observations, lithological composition, and fossil content into six rock units,
starting from base to top: Sarabit El Khadim, Abu Hamata, Nasib, Adedia, Um
Bogma, and Abu Thora Formations. The four first Formations mentioned
previously are Cambro-Ordovician in age, but the two last ones are Carboniferous.
Outcrops of Um Bogma region

12
Lower Carboniferous in the Um Bogma area, west central
Sinai, Egypt, according to Kora and Jux.

13
False color composite Landsat image of Um Bogma area, west central
Sinai, Egypt, after Bishta 2009.

14
The manganese, like iron, has two important valence states, Mn+2 and Mn+4. In the
divalent state (Mn+2), manganese forms soluble compounds and can be transported
in solution. In the tetravalent state (Mn+4), however, it forms insoluble
compounds, any solution containing Mn in solution will quickly precipitate a
tetravalent compound such as pyrolusite (MnO2) by oxidation.
Chemistry of Manganese

15
Paleozoic Outcrops of Um Bogma Region, Sinai, Egypt.
By Kora 1981.

16
Faults are the most remarkable and highly existed structural elements which
widely occurred within the Um Bogma Region, and hugely left their prints on
the rocks of the region. These faults can be grouped into 3 classes:
a) NNW-SSE trending normal faults (Red Sea trend) along the basaltic dykes
of Permo-Triassic in age were erupted.
b) NW-SE trending faults (Gulf of Suez trend) along which the main Wadies of
the Um Bogma Region were incised, such as the Wadies of Nasib, Baba, Bala,
El Lehian.
c) E-W trending faults along which the two Wadies of Sahu and Abu Thora
were incised.
Geologic Setting

17
Simplified structural map of Um Bogma Region

18
The Economic Mn-Ore deposits of the lower member of the Um Bogma
Formation have been subdivided into four main facies (types) as summarized as
the following:
1) Stratiform continental Mn-conglomerate, sandstone, and mudstone,
2) Stratiform lagoonal to swampy bedded manganiferous mudstone and dolostone,
3) Stratiform pisolitic Mn ore, and
4) Stratabound karst Mn ore.
Mn Ore Facies
(Types)

Stratigraphy of
Um Bogma
Formation

19
Stratigraphy of
Mn-Bearing Um Bogma Formation
Um Bogma Formation, in west-central Sinai, Egypt, varies in its thickness from 0-
10 m, in southeastern and northeastern parts, and reaches its maximum thickness
of about 30-40 m, in the northeastern part between Gebel Nukhul and Wadi
Khaboba. The Um Bogma Formation is essentially a pink-grey dolostone
sequence.

20
Stratigraphy of
Ras Samra Member
This member is the basal unit within the Um Bogma Formation, it consists mainly
of hard, bedded, pinkly brown, and coarse-grained crystalline dolostones,
containing pores and cavities filled with calcite (Kora, 1994).
1

21
Stratigraphy of
El-Qor Member
The El-Qor Member is the second of three, and it’s the middle one in the
succession of the Um Bogma Formation. It consists mainly of yellow, moderately
hard, thinly bedded marly dolostones and dolomitic limestones with soft siltstones
and shaly beds, and laterally, the carbonite rocks are replaced by quartz siltstones,
with ferruginous lenses (Kora, 1994). In this member, the fossil content is highly
recognized (Kora and Jux, 1986).
2

22
Stratigraphy of
Um Shebba Member
This member is the final and top one of the Um Bogma Formation, and
it consists mainly of thickly bedded, brown to grey, very hard, macrocrystalline
dolostones, containing variable amounts of coarse-grained sands, in addition to
quartz pebbles (Kora, 1994).
3

23
The stratigraphic column of the all formations of the Um Bogma
region, west central Sinai, after Kordi et al (2017)

Stratigraphic
Distribution of
Mn-Fe Deposits

24
Stratigraphic Distribution of
Mn-Fe Deposits
Mn-Fe Deposits are widely distributed within the whole members of the
Um Bogma Formation, but which have an economic impact is only limited
within the basal lower member (Ras Samra Member). The stratigraphic
relations of the Mn-Fe Ore Deposits are summarized as being outlined in
next slides, according to Kora et al (1994).

25
Some modes of occurrences of the Mn-Fe ore bodies within
the three members of the Um Bogma Formation, By Kora et al (1994)

26
Mn-Fe Deposits
Mn-Fe deposits within the Ras Samra Member
A
The Mn-Fe Ore Deposits take the shape of stratiform lenticular bodies, occurring
within the lower part of the Um Bogma Formation (Ras Samra Member), and its
extension is in SW–NE direction through its central and southern parts.

27
Mn-Fe Deposits
Mn-Fe deposits within El-Qor and Um Shebba members
B
Mn-Fe Ore Deposits are also recoded within the two other members, such El-Qor and
Um Shebba Members, in addition to its recording in the top levels of
the Adedia Formation. These deposits take the shape of regular sheet-like
bodies, with transition to thin detrital facies. The Ore under study extend to the
northwestern flanks of the Um Bogma region .

28
Mn-Fe Deposits
C
In Zobeir and Dakran localities, the deposits under study, are considered to be
of vein-like type, and these deposits of such a vein-like type are encountering
in two aforementioned localities only. These Ore Deposits are associated with
fissures and faults. At Dakran, the vein extends about 4 m vertically. And at
Zobeir, the thickness of the vein is about 0.4 m and extends for about 3 m
normal to the bedding.

29
Mn-Fe Deposits
D
In the northwestern part of the Um Bogma district, the disseminated Mn-Fe
Ore Deposits are mainly recorded. Scattered pockets and patches of
ferromanganese ore minerals which are considered being of low-grade, had
been contained within the dolomitic rocks, and these dolomitic rocks are
overlying the sandstone of the Adedia Formation, at the Um Shebba.

30
Saad et al. (1994) had made a geochemical analysis for tens of samples, plucked
from the lower member of the Um Bogma Formation, which contains the economic
Mn ore deposits, the aforementioned author found that there is an inverse relation
between Mn and Fe oxides, in the samples, and gave a belief that this inverse
relation suggests that a fractionation between two these elements took place during
their deposition. Also found that manganese of the Um Bogma is of hydrothermal
in nature, depending upon the geochemical analysis, using ternary diagram of Fe-
Mn-[10x (Cu+Ni+Co)]. In addition, the Mn ore deposits are observed to be highly
enriched in Pb, Cu, Zn, and Ba, and there is a depletion in such elements as Co,
Ni, Be, Mo, Sr, and Sn (Saad et al. 1994).
Geochemistry

31
There are three main types of Mn-Fe ore deposits, which had been detected
by field observations, MnO and Fe2O3 content, and MnO2/Fe2O3 ration,
such as;
1) Mn-rich ore,
2) Fe-Mn rich ore, and
3) Fe-rich ore (Khalifa, 2014).
Also, it’s investigated that there is a strikingly strong negative correlation
between MnO and Fe2O3, it reflects the precipitation of these deposits under
different environmental conditions (Saad et al. 1994; Khalifa, 2014).
Geochemistry

32
Ternary diagram Fe-Mn-[10x(Cu+Ni+Co)], (Bonatti et al., 1972).
The manganese deposits studied fall in the hydrothermal field.

33
Scatter plot showing the inverse relation between Fe203 and
MnO2, in the Umm Bogma region, west central Sinai.

34
The manganese ore deposits are highly related to faults, existing in the area, as
the only abundantly existed structural element in the region under study, in
addition these deposits get being richer in Mn ore deposits, at the points near
these faults.
In the areas where these deposits occur, hausmannite and manganite are found
(Hewett 1972; Roy 1981), associated to these Mn deposits, with an indication
of hydrothermal activity in such areas, which led to detect the origin of these
deposits, which are considered as being of hydrothermal Mn deposits
Evidence for hydrothermal
origin of Mn deposits

35
Mn ore deposits had been occupied within the same stratigraphic horizon, and
these occupied deposits are older than the preponderant structural elements
such faulting and folding, existing in the same district. In addition to the
occurred displacement, taking place by the faults in the region.
The presence of pyrolusite and manganite in association with goethite and
hematite, acting as strong evidence for sedimentary origin of these Mn
deposits.
The dolomitization is synchronous with the mineralogical and chemical
reconstitution of the zoned deposits.
Evidence for sedimentary
origin of Mn deposits

Contact Information
metwallyhamza45@gmail.com
+2 0111 44 10 415
Egypt, Monufia Governorate,
Quweisna City, Arab El-Raml.

THE PRESENTATION OF MY GRADUATION PROJECT

THE PRESENTATION OF MY GRADUATION PROJECT

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