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Diamond-bearing
Kimberlite pipes
in the Western Desert of Egypt (Gilf Kebir region)
-- Discovered on a significantly uplifted block
of the
East-Sahara-Ghost Craton in this region --
A.
Qaret-el.Hanash
B.
Zerzura Plateau
A.
"Qaret-el-Hanash" structure in the Western Desert (Egypt)
(The first detected Kimberlite pipe nearby the Silica strewnfield)
Norbert Brügge, Germany
Dipl.-Geol.
Upload: April 2018
Update:
21.12.2020
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The Qaret-el-Hanash is a prominent doming
structure with a wall on top in the southeast direction of the Libyan
Desert Glass area. The hight of the hill is 96 m above ground. The
slopes of the elevation are covered with broken sandstones.
During an expedition in 1996 traces of an eroded zone of megascopic
sandstone breccia, of about 2-m thickness, have been recognized.
The breccia occurs within the wall of Qaret-el-Hanash. Its matrix
appears as dull greyish-black material.
Petrographical and mineralogical studies have shown that there are
breccias, that consists of local sandstone rock fragments within
a matrix of finer quartz grains with glass and several other mineral
phases. The results were published in 2004 and declared as evidence
of the emergence of Qaret-el- Hanash by an impact.
(Aly Barakat)
However, the most important indication for the emergence of
Qaret-el-Hanash, which I postulate now as a
kimberlite pipe,
are the photos of Ursula Steiner (Switzerland), which
come from the top and southwestern
outside slope of the structure and are available to me.
The photos document clear the volcanic origin of Qaret-el-Hanash
impressively. The structure is crater-shaped, as it occurs in the
Gilf Kebir Crater Field (GKCF), but without (and that is the significant
difference) the tilted layers on the edge, indicating an explosion
event.
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25�04'46"N / 25�56'02"E
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It
seems that the most visibly material of the structure is "burned"
sandstone. But some photos from the debris outside (below) also
show a strange material of a dark (carbonaceous ?) melt with included
many diverse fragments, among ferruginous pieces, debris of basement
(BIF), glass, yellow jasper and minerals.
The melt contain also large dark brown
pieces, which could be diamonds.
So far this could not be checked. The whole composition is chaotic.
Important to mention are the intersecting (tectonic) dark lines
visible from the air on the southwestern slope of the structure,
where the melt with breccias and diamonds were found.
Photos by Ursula Steiner (2012)
The exact coordinates are known to the author. All photos
are available in high resolution
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Mysterious dark (tectonic?)
crosscut lines on the southern slope of the structure
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DISCOVERY OF Fe-Cr-Ni SPECKS WITHIN QARET
EL-HANASH BRECCIA OF THE LIBYAN GLASS AREA SOUTH WESTERN EGYPT
A. El-Kammar, I. Arafa, K. A. Soliman & A. Barakat --7th
International Conference on the Geology of the Arab World, Cairo
University, Feb. 2004, P. 1-7
The rock consists of various fragments of local
sandstone, i.e., from the area of the glass distribution itself.
Fragments of igneous source have never been recorded. The rock
fragments range from fraction of mm up to 4-cm in diameter,
in the collected specimens. The rock fragments vary in colour
from creamy white to brownish-red. They are angular to subrounded
and embedded in a dull greyish-black matrix. The microscopic
investigation and scanning electron microanalysis confirmed
the above-mentioned observation and showed that the matrix consists
of shattered and fragmented quartz grains of various sizes.
In addition to quartz, the matrix contains many other phases,
such as glass, zircon, clay minerals, wollastonite, ilmenite,
Mg-ilmenite, rutile and Fe-Cr-Ni specks.
There are several metallic specks of various
sizes ranging from 1 micron up to about 10 micron, dispersed
in the matrix of Qaret el Hanash breccia. They invade some of
the quartz grains. These specks are mainly of irregular outlines
and some of them show clear fissures. They are associated with
glass and intercalated in some cases with halite. EDAX analyses
of such specks indicate that they consist of native Fe, Cr and
Ni, in addition to subordinate Si and Ca. Finer particles of
similar appearance have also been noticed by the petrographical
microscope through the fractures of some of the quartz grains.
The most interesting achievement of the
chemical analyses is the detection of high Ir content (2.0-2.2
ppb) within the breccias. This value represents the highest
reported values for the area. The reported value of Ir in other
breccias in the area is around 1.6-1.9 ppb. The highest reported
concentration of Ir by the previous studies was detected from
the black streak portions from the Libyan glass itself is 1.25
ppb. (Barakat 2018)
Personal information by Aly Barakat on May 19, 2018:
Samples of other phases includes tiny grains of
moissanite and diamond.
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In Addition:
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1.) The so-called Siwa-meteorite (not Serra's
36g chondrite) is a breccia-bearing sandstone similar to the Qaret-el-Hanash.
The site is located nearby the borehole-spring "Bir Wahed" (29�07'19"
/ 25�26'03"), about 15 km southwest of the Siwa Oasis.
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From the
same location a bad photo of a breccia similar to that known from the
Sakhret-al-Amud
pillar in the Great Sand Sea. |
2.)
Three extraordinary finds of debris
in the GSS (dune corridors in the Silica-area) indicate that there are
further structures like the Qarat-el-Hanash that are either eroded or
covered by dunes.
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Source: Bogumil Dec,
on Youtube, 2016
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3.) Results of any petrographic investigations
in the GSS, published by
Köberl & Ferriere (2019). The most
interesting sample is EGY-S-3, found at 25�26'23"N/25�29'55"E
In fact, the investigated samples consist of brecciated debris of quartz in
a flowed volcanic groundmass. The structure in a thin section is comparable
to those from the Qaret-el Hanash or crater Zerzura-1.
"Gravel quartz (sandstone
??) with a bimodal grain-size distribution; the grains are formed
subangular to rounded; pore spaces are filled
with iron oxide; locally patches of
microcrystalline carbonate occur in the iron oxide matrix;
most quartz grains show undulatory extinction; a few polycrystalline quartz
grains occur; some quartz grains show ferruginous cavities; some
quartz grains are irregular fractured and highly decorated with
minute fluid inclusions." |
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4.) An very interisting object from
a dune corridors that is not pure Libyan Desert Glass. The matrix of
the selected part signals a rock from the Earth's mantle. There are
big altered inclusions, which were most likely olivine. The object was
enclosed in greenish LDG, which the owner said had been removed.
Here we have the ultimate proof of the
origin of the LDG from the Earth's mantle !
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5.) Three conspicuous breccias from
the Gilf
Kebir Crater Field (GKCF) in the eastern to
southeastern direction. On display are numerous clasts of Basement in
an iron-containing matrix
Compare:
Ground-Penetrating
Radar measurement in the small crater GKCF-28
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GKCF-01
23�14'37"N / 27�27'37"E
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GKCF-01
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GKCF-05
23�32'42"N / 27�09'33"E
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6.) Diamonds have been found in the
Gilf Kebir Crater Field (GKCF)
Roland Keller from Basel (Switzerland)
wrote to me on 03.03.2020: �In 2010, about 50 km eastern of Gilf
Kebir, I found fist-sized chunk of kimberlite. The chunk was dotted
with diamonds. I had my tester with me and it responded diamond. I noted:
Bedrock gray with 50% inclusions. 2x2 mm large octahedra diamonds, color
gray to slightly yellowish. Density: An octahedron every 5 mm.�
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B.
The Mystery of the Kimberlite Breccia on the Zerzura Plateau
(northern of the Egyptian Gilf Kebir)
Norbert Brügge, Germany
Dipl.-Geol.
Upload: May 2018
Update: 21.03.2019
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Source: Romano Serra
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| Geological setting:
The little explored Zerzura (or Saad) plateau is located north
of the Gilf Kebir on the latitude to the Silica strewnfield
in the Great Sand Sea in the east. The plateau is divided into
two halves by a distinctive wadi. The plateau is to be formed
according to the geological map by sandstones of the Upper Cretaceous
(Saad Form.). That is not verifiable. It should be Devonian
sandstones. After the loss of Ordovician-Silurian strata (erosion),
would follow the Archean Basement of the East Sahara Ghost Craton.
This scenario is likely because the Zerzura Plateau is placed,
like the Gilf Kebir, on the Uweinat-Howar Uplift. Mesozoic layers
are generally absent on the Uplift. Layers south of the Zerzura
Plateau are probably also not of Cretaceous. The stratification
of the sandstones (e.g. in the eastern exit of Wadi Qubba) are
similar the fluviatile Paleozoic sandstones in the Gilf Kebir. |
Sandstone in the eastern exit of Wadi
Qubba
nearby the Silica strewnfield
(Author 2010)
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| Findings
of
Lepidosigillaria indicate also Carboniferous layers.
Also with regard to the Gilf Kebir Plateau, the geological map
is therefore mostly wrong. The entire mapping is based on a
misinterpretation of a Carboniferous plant imprint (Paleoweichselia
halfa BRÜGGE,2017) from the Aqaba passage and which
was erroneously determined as the Mesozoic Weichselia reticulata
BRNGT. |
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Zerzura Plateau |
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Zerzura plateau on air with detected craters
Zerzura-1 to 13
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Zerzura plateau on geological map (brown)
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The Zerzura Plateau has become interesting
in recent time because we have to solve another of the many puzzles
in the Gilf Kebir region. Romano Serra and his companions
in 2011 visited a extraordinary crater, with a peculiar breccia
at its center. The author found a photo of it at an Italian PP-presentation.
Thankfully, Romano Serra, University of Bologna, has
now provided the author with many further photos (below).
In this spectacular breccia from the crater-like structure (crater
Zerzura-1) we can see probably a swarm of
micro-diamonds. Unfortunately,
apart from the identified location of the find (25�16'46 "/ 25�10'05")
there are no further comments or publications.
The visited crater Zerzura-1
is nearly round and in no case a depression caused by water
erosion. There are only two narrow cuts in the wall. The walls
of Zerzura-1 crater are flat as after an explosion. In the crater
itself is a hole with a plug of breccias therein. On the lower
wall of the crater bright layers can be seen, which could be
belong to a tuff ring, typical for kimberlite structures.
Right: The scenario by me.
The author believes that the breccia in the crater may be a
kimberlite pipe.
Many micro-diamonds seem to be present ("white sugar"), but
are difficult to recognize in the photos. |
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Now, the author found many further such characteristic craters
in the satellite overview. Twelve of them (Zerzura-2 to Zerzura
13) are here located:
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In addition of this, there are some pictures
from a trekking tour from the year 2003 available, which has thankfully
made available to me by Andras Zboray (fjexpeditions.com).
In the southern part of the plateau, in a hole in the sandstone,
strange hollow cracks can be seen on the wall, on which light mineral
deposits stick on the inside. Remarkable are also the round small
openings in the floor and in the walls of the hole through which
obviously iron-rich solutions have flowed. There is no doubt that
hydrovolcanic solutions have ascended here under high pressure and
have left their signature. |
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Location of the hole: 25�07'28"N / 25�19'43"E
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Further mysteries
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1.) Crater-shaped
structures with central hill eastern of the northern tip of Gilf Kebir
Plateau
(unnamed and unexplored)
In the just found new "Northern
Gilf Kebir Crater Field" (N-GKCF) there are craters that are not comparable
to the craters in the
Gilf Kebir Crater
Field (GKCF) in the southeast. A accordance with the craters on
the Zerzura Plateau is more obvious.
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2.)
The find of pinkish Silica, 50 km southwest of the LDG strewnfield
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Libyan Desert Glass : New field
and Fourier transform infrated data
Francois Fröhlich et al. -- Meteoritics & Planetary Science
48, Nr 12, 2517�2530 (2013)"Are the Wadi
Qubba LDG blocks in situ or were they transported here from the
Great Sand Sea by Prehistoric men? Several observations and analyses
are consistent with the assignment of this new LDG occurrence to
the LDG strewn field.
1. The color (pink) of all the Wadi Qubba specimens is quite different
from the Great Sand Sea ones (yellow to green);
2. The molecular structure is clearly slightly different;
3. No large artifacts were found at Wadi Qubba; only one small blade
was found that was made from the same glass as the other LDG found
in the neighborhood (size, color, molecular structure).
Thus, we infer that the Wadi Qubba LDG blocks are in place and hence
they are included in the LDG strewn field."
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24�52.189' / 25�27.044'
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Note: The piece is found in a unnamed
Wadi (not Wadi Qubba). It could not have been transported out of
the strewnfield to this place. The valley floor is 50m higher. The
pinkish color of the piece is extraordinary and was never found
in the LDG strewnfield. The quality of the finds does not indicate
that they were attractive for humans. Apparently, there is another
tectonic structure somewhere outside the known Silica strewnfield.
Surprisingly, there are two more finds of reddish desert glass,
without reference to a locality and from a settlement site far south
on Jebel Kissu in Sudan.
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Location unknown
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Microlith from Gebel Kissu
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