"Qaret-el-Hanash" structure in the Western Desert (Egypt)
(Probably the first detected
Kimberlite pipe nearby the Silica strewnfield)

 Norbert Brügge, Germany
Dipl.-Geol.

Upload: April 2018
Update:
13.08.2018


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 eroded kimberlite pipe, are the photos of
Ursula Steiner (Switzerland), which come from the top and outside slope of the structure and are available to me. They document clear the subvolcanic origin of Qaret-el-Hanash impressively. Some photos (below) show a strange, material of a dark (carbonaceous ?) melt with included many diverse fragments, among ferruginous sandstone, basement debris, glass and yellow jasper. The melt contain also visibly large dark brown diamonds.


25°04'46"N / 25°56'02"E


Photos by Ursula Steiner (2012)

First view:
It looks like Barakat's "black rock" (Hypatia stone) but with a lot of brecciated material from the depths (basement debris, glass, jasper etc.). 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. It seems that the most of  "black rock" material is burned ferruginous sandstone. But a black glassy (carbonaceous ?) melt and jasper solutions are also involved. The whole composition is chaotic. At the place of the debris, near the southwestern slope, were also found visibly large dark brown diamonds. The exact coordinates are known to the author.
  

Top of the Qaret-el-Hanash: Jasper on ferruginous sandstone

Unexplored crater bottom

Breccia

Breccia outside slope

Quartz flow with cracks

Glass

Diamonds (or Moissanite ?)

Dark (carbonaceous ?) melt Jasper Sandstone debris ouside




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)
  

The flat surface of the Qaret el Hanash breccia The analysis of the glassy matrix confirm a similarity to the
 dark LDG variety
Thanks to Aly Barakat
Photomicrograph breccia showing shattered and fragmented quartz grains in the glassy matrix admixed with other phases SEM image and EDS analysis of quartz and glass of worm like structure in the matrix Photomicrograph showing finer particles of the Fe-Cr-Ni phase dispersed within the glassy matrix


Personal information by Aly Barakat on May 19, 2018: The samples contains tiny particles of Fe-Cr-Ni, and other phases includes tiny grains of moissanite and diamond.

 

In Addition:

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.

Source: Bogumil Dec, on Youtube, 2016