Sol Hamed Ophiolitic Complex, Southern Eastern Desert, Egypt: Petrological, Economic Potentiality and Structural Implications

Abstract

The Sol Hamed (SH) area is a part of the Arabian-Nubian Shield (ANS) ophiolites occurred within Onib-Sol Hamed suture zone in the southern Eastern Desert (SED) of Egypt. The ophiolitic assemblages in this area are represented by serpentinite, metagabbro and arc assemblages represented by metavolcanics. They later intruded by gabbroes and granites. Geochemically, the compatible trace elements enrichment in SH serpentinites indicate derivation from a depleted mantle peridotite source. They show affinity to the typical metamorphic peridotites. The Cr and TiO₂ contents indicate supra-subduction zone (SSZ) environment. Their Al₂O₃/SiO₂ and MgO/SiO₂ ratios support the SSZ affinity and are similar to ANS peridotites with fore-arc setting. Structurally, the area represents four deformational events can be well-known in the Neoproterozoic rocks (D₁, D₂, D₃ and D₄); There is major three fault sets affected the area. Magnesite in SH serpentinites are cryptocrystalline. It is occurring as snow-white veins and stock-works. These characteristics are typical of Kraubath type magnesite deposits. Gold is confined to malachite-bearing quartz veins, smoky quartz veins and alteration zones. Malachite-bearing quartz veins trending NW-SE cut through gabbroic rocks. The barren quartz veins are vertical with E-W directions. Alteration zones with NW-SE trend and vertical dip intrude metagabbros and metavolcanics.

1. Introduction

The Arabian–Nubian Shield (ANS) crustal growth occurred during the Neoproterozoic Era [1]. The ANS represents a combination of well-preserved tectono-stratigraphic terrains characterized by well-defined suture zones which are marked by ophiolite assemblages [2, 3, 4]. During mid-Neoproterozoic, Juvenile arc terrains formation around Mozambique Ocean margins and collision occurred producing the ANS [3, 5, 6]. In late Neoproterozoic (∼630 Ma), arc accretion terminated once East and West Gondwana fragments collision occurred closing the Mozambique Ocean and generating the East African–Antarctic Orogen [7, 8]. Therefore, ANS suture zones are classified to older arc–arc suture zones which separated ∼700–870 Ma arc terrains and younger arc–continent suture zones formed at ∼630 Ma [2, 9, 10, 11, 12]. It is generally accepted that most of the ANS ophiolites were generated in supra-subduction zone (SSZ) environment [13, 14, 15, 16, 17, 18]. They formed due to seafloor spreading above active subduction zones. Several tectonic scenarios were attributed for the ANS ophiolites formation: (1) NMORB setting (i.e., fragments of normal oceanic crust [19]: (2) remnants of back-arc basins (e.g., [9, 20, 21]); or (3) fore-arc setting due to seafloor spreading during initiation of subduction process [4, 13, 14, 15, 17, 22]. Various ophiolite complexes may possibly be generated in diverse SSZ tectonic settings. In order to contribute to resolve this existed debate, we introduce new geochemical data on Sol Hamed serpentinites in the southern Eastern Desert to better constraint their tectonic setting. The Egyptian Precambrian belt which is the NE part of the ANS is consisted of an Upper Proterozoic assemblage of volcano-sedimentary succession, scattered over thrusting mafic-ultramafic rocks (i.e., ophiolite complex) and intruded by syn- to late-tectonic granitoids and mafic–ultramafic intrusions. Later, Precambrian peralkaline granites and Tertiary alkaline ring complex intrude the country rocks of the area. The Sol Hamed ophiolitic complex is a part of Allaqi-Heiani-Onib-Sol Hamed-Yanbu arc–arc suture (Figure 1; [23, 24] which represent one of the two longest and most complete Neoproterozoic ophiolite suture in the Arabian Nubian Shield [25].

Figure 1.

Map showing the distribution of ophiolites in the central Eastern Desert (CED) and southern Eastern Desert (SED) of Egypt (Modified from [23]). The location of Sol Hamed (SH) ophiolites is also indicated. The inset map shows the general map of Egypt.

2. Materials and methods

2.1 Field study

For this purpose, field trip was carried out during the period of 20–27 April 2019 by using the Landsat image and the available geologic maps (scale 1:50000) were used. About 15 rock samples were collected representing the exposed serpentinites in the mapped area (Figure 2). Thin sections were prepared for each sample.

Figure 2.

Geological map of SH (after EMRA, 1995, [26]).

2.2 Laboratory work

For this purpose, petrographic investigation of 15 thin sections and 4 polished sections were prepared. The petrographical study was achieved using MEIJI ML 9000 Polarizing Microscope equiped with automatic photo micrographic attachement ToupCam Digital Camera XCAM1080PHA. Chemical analyses of 10 samples were carried out at the Central Laboratories of the Geological Survey of Egypt. The selected samples represent the best aerial coverage of the examined area. Before bulk rock chemical analyses were carried out, the samples were cleaned and grinded in an electric agate mill, homogenized, dried on the oven for 60 min at 105 degree then mix with 50% from wax polyvinyl meta-acylate additives. Determination of the chemical composition of both major and some trace elements was performed by using a Philips X-ray fluorescene technique model PW/2404, with Rh radiation tube and eight analyzing crystals. Crystal (LIF-200) was used for estimating Ca, Fe, K, Ti and Mn, while crystal (TIAP, PX-1) was used for estimating Mg and Na. Crystal (Ge) was used for estimating P and Crystal (PET) was used for estimating Si and Al. The concentration of the analyzed elements was determined by using software Super-Q with accuracy 99.5% and confidence limite 95.6%. Ten samples of these rocks were also analyzed to determine their REE contents using the simultaneous inductively coupled plasma emission spectrometer (720 ICP-OES, Agilent Technologies), with accuracy 96%. Nine samples from SH magnesites were analyzed for major elements by the same technique of XRF mentioned above. All analytical results are given in Tables 1 and 2.

Sample no	1	2	3	4	5	6	7	8	9	10
Major oxides (wt. %)
SiO2	45.699	46.286	45.709	45.539	45.957	45.654	44.360	44.050	44.857	47.617
TiO2	0.057	0.056	0.011	0.058	0.012	0.023	0.023	0.023	0.035	0.012
Al2O3	0.550	0.993	0.491	0.465	0.046	0.231	1.015	0.915	0.346	0.115
Fe2O3^T	7.788	8.365	7.771	9.294	9.099	9.799	9.249	9.954	8.660	6.924
MnO	0.103	0.089	0.114	0.081	0.092	0.173	0.056	0.034	0.104	0.104
MgO	45.470	43.832	45.709	44.261	44.575	44.063	44.778	44.863	45.226	45.182
CaO	0.218	0.134	0.171	0.290	0.196	0.058	0.203	0.160	0.750	0.046
Na2O	0.103	0.190	0.011	0.012	0.012	0.000	0.282	0.000	0.012	0.000
K2O	0.011	0.056	0.011	0.000	0.012	0.000	0.034	0.000	0.012	0.000
Total	100	100	100	100	100	100	100	100	100	100
LOI	12.690	10.340	12.490	13.920	13.180	13.260	11.340	12.600	13.280	13.350
SiO2/MgO	1.005	1.056	1.000	1.029	1.031	1.036	0.991	0.982	0.992	1.054
Al2O3/SiO2	0.012	0.021	0.011	0.010	0.001	0.005	0.023	0.021	0.008	0.002
MgO/SiO2	0.995	0.947	1.000	0.972	0.970	0.965	1.009	1.018	1.008	0.949
Mg#	92.077	91.247	92.131	90.450	90.692	89.940	90.592	89.961	91.220	92.855
Trace elements (ppm)
V	40.200	29.500	27.400	37.200	26.100	22.160	40.200	14.010	34.100	19.500
Cr	2655.400	2701.100	2706.600	2656.800	2688.800	2580.200	2701.200	2654.100	2708.600	2425.900
Ni	2377.100	1800.300	2056.300	2057.300	2070.100	1840.200	1816.200	2055.400	1657.200	1999.100
Cu	63.100	15.100	24.100	50.530	43.210	53.210	54.210	8.290	47.310	33.510
Zn	56.900	13.460	24.900	23.070	35.100	17.900	34.800	17.200	11.890	23.050
Co	166.500	121.400	120.500	162.300	165.200	152.400	154.200	152.400	117.200	136.100
Ga	1.560	1.050	0.900	1.300	1.200	1.110	1.200	1.400	1.330	1.340
Rb	0.330	0.350	0.500	0.400	0.450	0.500	0.450	0.350	0.300	0.280
Sr	55.020	46.150	47.900	62.100	60.100	72.110	50.100	88.990	48.080	48.100
Zr	120.000	118.000	127.000	119.000	121.000	120.000	123.000	122.000	121.000	118.000
Nb	0.100	0.090	0.085	0.100	0.100	0.100	0.090	0.080	0.090	0.100
Ba	35.600	15.100	25.000	15.120	19.800	17.110	16.430	45.040	20.000	29.500
La	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100
Ta	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085
Pb	4.800	13.140	16.100	15.100	16.900	19.900	17.100	4.660	24.050	14.700
Th	0.200	0.200	0.200	0.200	0.200	0.200	0.200	0.200	0.200	0.200
Tl	0.037	0.038	0.040	0.300	0.260	0.040	0.038	0.040	0.300	0.280
Li	10.100	5.000	7.000	6.120	5.500	8.200	8.980	9.900	1.710	7.150
Hf	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020	0.020
Cs	0.850	0.750	0.090	0.090	0.088	0.090	0.080	0.680	0.070	0.060
Sn	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085	0.085
Bi	0.010	0.030	0.025	0.020	0.010	0.020	0.030	0.030	0.025	0.020
Cd	2.100	2.100	3.200	3.400	2.150	2.500	3.500	3.400	3.450	2.900
In	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010
W	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090
Mo	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010	0.010
Re	0.003	0.003	0.003	0.003	0.003	0.003	0.003	0.003	0.003	0.003
Sb	1.830	2.400	3.110	1.140	3.150	2.700	3.100	3.100	1.980	2.330
As	4.210	5.330	3.700	5.700	5.300	4.800	4.500	5.210	4.910	3.800
Ag	185.000	190.000	195.000	191.000	187.000	170.000	193.000	192.000	190.000	194.000
S	0.040	0.040	0.040	0.040	0.040	0.040	0.040	0.040	0.040	0.040
Se	0.300	0.500	0.400	0.300	0.700	0.230	0.300	0.400	0.700	0.500
Be	0.850	0.700	0.900	0.850	0.900	0.900	0.800	0.700	0.700	0.800
Te	5.500	5.400	5.500	5.500	4.110	4.800	5.700	4.300	4.980	5.120
Rb	1.810	1.000	1.200	1.700	1.450	1.700	0.330	0.800	0.200	1.300
Sc	4.100	4.010	3.800	3.550	4.200	3.700	3.940	4.010	4.300	3.900
U	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090	0.090
Rare earth elements (ppm)
Y	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Ce	0.250	0.249	0.248	0.250	0.250	0.250	0.250	0.250	0.250	0.250
Dy	0.079	0.082	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Eu	0.078	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Er	0.078	0.084	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Gd	0.081	0.077	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Ho	0.083	0.078	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Nd	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100
Pr	0.100	0.120	0.100	0.100	0.100	0.100	0.100	0.100	0.100	0.100
Sm	0.083	0.079	0.082	0.083	0.078	0.078	0.079	0.084	0.083	0.078
Tm	0.077	0.081	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Tb	0.080	0.079	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Yb	0.083	0.077	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
Lu	0.082	0.076	0.080	0.080	0.080	0.080	0.080	0.080	0.080	0.080
ΣREE	1.334	1.342	1.330	1.333	1.328	1.328	1.329	1.334	1.333	1.328
La/Yb	1.325	1.429	1.538	1.688	1.310	1.205	1.358	1.410	1.447	1.266
Gd/Yb	0.976	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000	1.000
La/Sm	1.205	1.266	1.220	1.205	1.282	1.282	1.266	1.190	1.205	1.282

Table 1.

Major, trace and rare earth elements of the studied rocks.

	1	2	3	4	5	6	7	8	9
SiO2	0.70	0.68	0.40	1.30	0.23	0.30	0.90	0.30	0.30
TiO2	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Al2O3	0.10	0.10	0.10	0.10	0.10	0.10	0.10	0.10	0.10
Fe2O3	0.04	0.05	0.10	0.32	0.03	0.06	0.05	0.05	0.06
Fe	0.03	0.03	0.07	0.22	0.02	0.04	0.03	0.04	0.04
MnO	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Mn	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
MgO	42.70	42.30	42.60	41.10	45.50	43.00	45.10	43.40	41.10
CaO	5.80	5.18	5.50	5.18	1.60	5.30	2.60	4.18	5.30
Na2O	0.40	0.15	0.18	0.15	0.50	0.01	0.01	0.15	0.01
K2O	0.00	0.01	0.00	0.00	0.00	0.00	0.00	0.00	0.00
P2O5	0.02	0.02	0.02	0.02	0.02	0.07	0.02	0.02	0.02
LOI	49.10	49.30	50.10	49.00	49.30	50.30	49.50	50.50	51.01
Total	98.89	97.82	99.07	97.40	97.30	99.19	98.31	98.74	97.94

Table 2.

Magnesite chemical analysis.

3. Geologic setting

Sol Hamed area located in north of Gabal Elba in the southern Eastern Desert. Its rock units consist of mainly ophiolitic assemblage and arc-related metavolcanics and granitoids.

Ophiolite complex contains three NE-SW trending sub-vertical lithological zones, ultramafic in the NW side, gabbros in the middle and pillow lava in SE (Figure 2). This belt signifies the north-eastern outlet of the Hamizana Shear Zone (Figure 1). The ophiolitic ultramafics include both sheared and massive varieties. Serpentinites show low to medium relief. They cropped out in the central and eastern parts. Furthermore, they are transformed along NE-SW trending shear zones to talc, talc- and quartz-carbonates, and magnesite particularly in the eastern parts. Most quartz carbonates present in the area sideways the contact between serpentinites and metavolcanics. Magnesites fill the cracks and fissures creating stock-work within the serpentinite (Figure 3a).

Figure 3.

Field photographs show a) the stock-work in magnesite bearing serpentinites, b) Bas basic dyke cutting the ophiolitic gabbro, c) Brecciated quartz-vein, d) Flaser structure of metagabbro, e) acidic dykes of apogranite and f) post-tectonic granitoids intruded within metagabbro.

The massive ultramafic complex comprises serpentinized dunite, peridotite and pyroxenite. The serpentinized dunite swarm few chromite pods [27]. The complex is net-veined with white-blue gray magnesite filling the fractures due to hydrothermal alteration. Serpentinite is geologically bounded in NW and SE by schistose basic to intermediate metavolcanics and ophiolitic metagabbro, correspondingly.

Metagabbros occur as large masses of low to medium relief. They are serene in the southern part of the study area, separated by basic dykes (Figure 3b) and quartz veins. They current SE of the serpentinites with a perfect tectonic contact trending NE–SW and dip to NW (Figure 2). They are locally layered, sheared and warped as flaser structure (Figure 3d). They are cut by acidic dykes of apogranite (synonym of Albitized granite) (Figure 3e) and metagabbro-diorite dykes forming parallel and nearly vertical NE-SW trending dykes (Figure 3b). They are also intruded by post-tectonic granitoids (i.e., tonalite and monzogranite) at SE of Gabal Sol Hamed (Figure 3f).

Basaltic pillow lavas situated NW to W of Gabal Qash Amer and related with the volcaniclastics. The original pillow customs are easily familiar and dip to the SW. They have gone through constrain deformation designated by the lineated and stretched pillow volcanics.

The arc assemblages comprise basic to intermediate metavolcanics and their pyroclastic rock varieties. The acidic metavolcanics display schistose structure with main direction of 50o and dip 60o SE. The meta-rhyolites showing at the northeastern and western part of the area, wounding by quartz veins and enclosed by sand dune particularly in the north central part. The massive basic to intermediate metavolcanics produce out at the northern part. In the western side of Wadi Diit, a small belt of massive and schistose metavolcanics is observed (Figure 2). These rocks are slightly foliated and comprise thin beds of fine laminated volcaniclastics and tuffs. There are also lapilli tuffs with plagioclase and quartz clasts of lapilli size. Gradational connection with gabbroic rocks existing south of the volcanic rocks. North of this volcanic belt, there is a sharp intrusive contact with tonalite rocks.

The arc granitoids with low to medium relief crop out at the NW part of the area and are characterized by presence of dioritic xenoliths.

Granitic rocks befall in Qash Amer and El Sela area. Qash Amer muscovite granites signify the highest peak in the area. They are categorized by fractures, exfoliation, and weathering boulders. The El Sela younger granites take place as high-relief remote and dispersed granitic masses vacating the southern East part of the mapped area (Figure 2). They are characterized by cavernous weathering and exfoliation. They interrupt younger metavolcanics and are occupied by different types of trachytic dikes and quartz. These granites show joints and fractures that are occupied by iron oxide containing radioactive minerals.

Numerous basic and acidic dykes separated the area. Acidic dykes are detailed in Wadi Diit, where they cut tonalite and metavolcanics. Generally, they are trending either NE-SW or N-S. They include rhyolite, apogranite and dacite. Basic dykes are abundant and trend mainly either NE-SW or NW-SE. They changed through all the rock units described above particularly tonalite, metavolcanics and ophiolitic gabbro (Figure 3b). They comprise andesite and dolerite (Figure 3b) with N-S trend.

The veins can be subdivided into three main types, quartz, and ankerite and pegmatite veins. The studied area is rich in quartz veins with different thickness trending mainly N-S and NE-SW particularly in the metavolcanics. It is white color and sometimes rich with iron oxides and copper minerals. Other types of quartz are brecciated, cemented by iron oxides (Figure 3c). Sometimes, smoky quartz detailed especially in the gabbroic rocks. Quartz veins cut through all the rock units. The veins are brecciated, stained red with iron oxides and may comprise pyrite crystals (Figure 3c). Many quartz veins are supplementary with hydrothermal alteration zones in the metavolcanic rocks. Ankerite veins befall as big veins at junction of Wadi Diit with Wadi Badbari. They changed the schistose metavolcanics, trending either NE–SW or E-W with a vertical dip.

4. Petrography

4.1 Serpentinites

Serpentinites recorded in SH. They are fine-grained and light green to dark green in color and essentially consist of serpentine minerals (>80%) together with variable amounts of carbonates, magnetite (Figure 4a), and brucite as well as chromian spinel. In few samples, talc is observed and Olivine is completely altered to serpentine and opaques along its irregular fractures. Clinopyroxenes are partially and/or completely altered to tremolite and chlorite. The rocks exhibit pseudomorphic (Figure 4b) and interpenetrating textures. Antigorite is the main serpentine mineral together with lesser chrysotile and Lizardite Antigorite occurs as large plates and fibrous and scaly aggregates (Figure 4b). Chrysotile occurs as fibrous veinlets that commonly transformed into carbonate and traversing the antigorite matrix (Figure 4a). In some parts, bastite texture is associated with schiller structure where magnetite defines cleavage planes of the original orthopyroxene (Figure 4a). Chromian spinel in the serpentinites occurs as both subhedral to euhedral crystals (Figure 4a) and irregular grains, while in the sheared varieties spinel is mostly brecciated. Carbonates occur as sparse crystals, patches, and fine aggregates.

Figure 4.

Photomicrograph showing a) Serpentinites with fine-grained and light green to dark green in color and consist of serpentine minerals organized with variable amounts of carbonates, magnetite, b) Pseudomorphic and interpenetrating textures of serpentinites, carbonates as an alteration product of serpentine minerals, c) Tremolite‐talc rocks composed of tremolite and talc together with olivine and orthopyroxene relics, d) Metagabbro with fine crystals of plagioclase and is variably altered to tremolite, actinolite and chlorite. The secondary amphibole are highly abundant and mainly represented by actinolite commonly pale green and moderately pleochroic, often simply twinned and occurs as fibrous prisms and tablets. Augite occurs as irregular shreds and remnants within the pseudomorphic amphibole, e) Andestic and basaltic composition of metatuffs, f) Crystals of plagioclase and Hornblende in metagabbro-diorite, g) Plagioclase and Hornblende in diorite and h) Plagioclase, K-feldspars, quartz, muscovite, biotite in syn-tectonic granite

4.2 Carbonate serpentinite

Carbonate serpentinites are composed of serpentine minerals and carbonates as the main components. Carbonates occur as an alteration product of serpentine minerals (Figure 4b) whereas; opaques represent the main accessories. Carbonate samples are mostly stained with iron oxides, whereas some appear as veinlets corroding rock.

4.3 Tremolite-talc rocks

Tremolite-talc rocks are composed of tremolite and talc together with olivine and orthopyroxene relics (Figure 4c). Accessory minerals are represented by carbonates and opaques. Talc and tremolite are formed as alteration products of olivine and orthopyroxene. Tremolite forms fibro-lamellar sheaves piercing talc, orthopyroxene and olivine.

4.4 Ophiolitic Metagabbros

These metagabbros are massive, holocrystalline, medium to fine-grained with a grayish-green to dark green color. They show ophitic to sub-ophitic textures, and mainly consists of plagioclase (60–50%) and amphibole (40–30%), together with rare fresh relics of clinopyroxene. The secondary minerals are chlorite, zoisite, clinozoisite, epidote, sericite and calcite, while the accessories are sphene, apatite and opaque minerals.

Plagioclase crystals are euhedral to subhedral and many exhibit albite twinning. Variable alteration of plagioclase to epidote, zoisite and clinozoisite, as well as sericite, is observed. Zoning of plagioclase occurs, but is generally uncommon. Primary magmatic hornblende is less abundant and when observed it occurs as prismatic and bladed aggregates that poikilitically encloses fine crystals of plagioclase (Figure 4d) and is variably altered to tremolite, actinolite and chlorite. The secondary amphibole is highly abundant and mainly represented by actinolite commonly pale green and moderately pleochroic, often simply twinned and occurs as fibrous prisms and tablets (Figure 4d). Augite occurs as irregular shreds and remnants within the pseudomorphic amphibole (Figure 4d). Chlorite is present as flakey and fibrous aggregates and is closely associated with amphibole, epidote and calcite. Epidote occurs as anhedral granular aggregates replacing plagioclase and amphibole. Accessory minerals such as apatite occurs as fine laths embedded in plagioclase and amphibole.

4.5 The metavolcanoclastic rocks (meta-tuffs)

The meta-tuffs are encountered in the western part of the mapped area but with restricted extension. They are massive, fine-grained, bedded, laminated and sometimes associated with thin bands of brownish opaque minerals. Microscopically, they are composed essentially of metamorphosed ash and lapilli tuffs, containing mineral and rock fragments. The mineral fragments are represented by plagioclase and quartz, whereas the rock fragments are andesitic and rarely basaltic in composition (Figure 4e).

4.6 Metagabbro-diorite

Microscopically, these rocks consist mainly of plagioclase, amphibole together with subordinate amounts of pyroxene and opaques. Few samples contain very small amounts of quartz. Opaques, sphene and apatite are the accessories, while calcite, actinolite, chlorite and epidote represent the secondary products. Ophitic and sub-ophitic textures are common, whereas the porphyritic texture is rarely observed. Plagioclase ranges in composition from labradorite to oligoclase and generally occurs as subhedral to anhedral crystals, partly saussuritized. Amphiboles are represented by less abundant primary, prismatic crystals of brownish green color and politically enclosing minute crystals of plagioclase (Figure 4f). Secondary hornblende is predominating and form pseudomorphs after pyroxene. It commonly occurs as pale green subhedral crystals sometimes enclosing small crystals of plagioclase. Pyroxene occurs as relics of altered greenish blue crystals. It is commonly an augite altered to secondary hornblende as indicated by the presence of the original pyroxene in the core mantled by secondary hornblende (Figure 4f).

4.7 Diorite

Mineralogically the diorites are composed mainly of plagioclase and hornblende (Figure 4g). Locally, chlorite partially replaces hornblende and quartz is a minor constituent. Hypidiomorphic texture is characteristic, Apatite, zircon and Fe oxides are common accessories.

4.8 Syn-tectonic granite

These rocks are represented by micro-granite. It is medium-grained and shows granular to granular porphyritic in texture. It is made up of plagioclase, K-feldspars, quartz, muscovite, biotite (Figure 4h), accessory minerals (zircon, opaque minerals), and secondary minerals (chlorite, sericite and calcite). Plagioclase constitutes about 40% of the granite. Crystals are anhedral and equant, and albite twinning is ubiquitous. Plagioclase crystals are usually un-zoned. Potassium feldspar constitutes up to 20% of the rock. It occurs as small irregular crystals, often totally or partially enclosed by plagioclase; in some instances, plagioclase with myrmekitic intergrowths appears to invade the adjacent orthoclase. Quartz constitutes about 30% or the granite. It occurs as medium-sized, anhedral crystals, sometimes with sutured margins, and also as small, drop-like inclusions in either feldspar. It generally has undulous extinction. Muscovite constitutes up to 10% of the rock. It occurs as euhedral isolated laths, sometimes with small rounded quartz inclusions, and sometimes occurs as ragged intergrowths with quartz. Occasional ragged crystals of biotite occur, which may be partially replaced by chlorite. Calcite occurs as fine interlocked crystals commonly form micro-bands or filling the polygonal spaces among the plagioclase laths.

5. Results

Major oxides recalculated on an anhydrous basis and plotted volatile-free to reduce the variable element dilution effects resulting from serpentinization process. The studied serpentinites have relatively higher loss of ignition (LOI) values (10.34–13.92 wt. %). The MgO content is hardly affected by serpentinization process and its elevated values in SH serpentinites (MgO = 43.83–45.71 wt. %) reflect highly depleted mantle source [28, 29]. Their high Mg# (89.94–92.85) are like modern oceanic peridotites [30] indicating a limited mobility of Mg and Fe. Their very low Na₂O (0.00–0.28 wt. %) and K₂O (0.00–0.06 wt. %) contents are comparable to those from the Eastern Desert supporting this study [13, 15]. The serpentinization processes possibly increased the LOI contents without significant modification of the major element composition [31]. The Ca–metasomatism is a common issue in Egyptian serpentinites [32], however the very low CaO contents (0.05–0.75 wt.%) in the serpentinites indicates restricted effect of carbonate metasomatism. So, we suggest that the protolith major element compositions must have been preserved during the hydration processes and that the geochemistry of the studied serpentinites display mostly the original nature.

SH serpentinites display affinity to the typical metamorphic peridotites on the AFM diagram [33]; Figure 5a. The bulk-rock Al₂O₃ content is relatively unaffected by serpentinization and therefore retains its original primary signature [30]. The studied serpentinites have Al₂O₃ contents (0.05–1.02 wt. %) comparable to oceanic and active margin peridotites and fore-arc and Pan-African serpentinites Figure 5b; [13, 15, 18, 34, 35]. Like other Eastern Desert ultramafites, the SH serpentinites have SiO₂/MgO ratios and Al₂O₃ contents analogous to ophiolitic peridotite [13, 15, 17, 19, 36, 37] Figure 5c. The serpentinites the nature of peridotitic komatiite by using of Jensen’s cation plot after [38], Figure 5d. The Al₂O₃ and CaO depletion is typical of fore-arc peridotites, Figure 6a;[39] and characterizes ED ophiolitic ultramafites [15, 17, 19, 37]. In terms of Al₂O₃/SiO₂ and MgO/SiO₂ratios, they are like Arabian–Nubian shield and fore-arc peridotites (Figure 6b; [13, 15, 29, 44, 46], low value of Al₂O₃/SiO₂ (fore-arc field), suggesting that these rocks were derived from a mantle source with high degrees of partial melting. The studied serpentinites have enriched compatible trace elements (Cr = 2426–2709 ppm, Ni = 1657–2377 ppm and Co = 117–167 ppm) suggesting derivation from a depleted mantle peridotite source.

Figure 5.

a) AFM diagram for SH serpentinites after [33], b) Bulk-rock Al₂O₃ (wt. %) contents of SH compared with those from other tectonic settings from [34] and the Pan-African serpentinites [18, 35], c) SiO₂/MgO ratios vs. Al₂O₃ diagram. Ophiolitic peridotite, ophiolitic gabbro and MORB are from [36]. Data from Eastern Desert (ED) are shown for comparison [13, 15, 17, 19, 37] and d) Jensen’s cation plot after [38].

Figure 6.

a) CaO vs. Al₂O₃ diagram showing SH serpentinites compared with fore-arc and MOR peridotites after [39], b) MgO/SiO₂ vs. Al₂O₃/SiO₂ diagram. Primitive and depleted mantle values are after [40] and [41], respectively. The “terrestrial array” represents the bulk silicate Earth evolution [42, 43]. Abyssal and fore-arc peridotite fields are after [29, 44, 45]. ANS ophiolitic peridotite field is after [13, 46], c) Primitive mantle-normalized trace element patterns, and d) Chondrite-normalized REE patterns for the SH mantle section. Normalizing values are after [40].

The SH mantle rocks are highly depleted in incompatible trace elements relative to the primitive mantle (Figure 6c). They are variably depleted in Nb consistent with SSZ geochemical characteristics [47] similar to abyssal and fore-arc peridotites [45, 48]. Moreover, the positive Pb-anomaly on spider diagrams resembles abyssal and fore-arc peridotites [45, 48] (Figure 6c). This specific positive Pb-anomaly may proposes a protolith origin or reflects the result of fluid percolation during serpentinization processes [49, 50]. The serpentinites has low concentrations HFSE such as Nb, Hf, Ta, Ce, U and Th, comparatively high concentration of LILE such as Ba and Sr. Subduction zone trace element signatures are clear due to the enrichment of LILE (Sr and Ba) over HFSE (Nb, Ti, Y, Ce, U and HF) and negative Ta anomaly [22]. The REE diagram displays HREE enrichment and LREE depletion. The Av.ΣREE contents of serpentinites is 1.33 ppm.

Chondrite normalized REE patterns show very low fractionated patterns (La/Yb) = (1.398). The LREE of the studied ultramafic show a low degree of fractionation (La/Sm = 1.24). The degree of fractionation of HREE is also low (Gd/Yb = 0.998), (Figure 6d).

6. Discussion

Metamorphism ranging from low-grade greenschist to medium-grade amphibolite facies usually influenced the ophiolitic ultramafites of the Egyptian ED forming serpentinite and/or mixtures of serpentine, talc, chlorite, carbonates and magnetite e.g., [13, 15, 51, 52, 53]. The time and source of carbonate metasomatism that commonly affected the Egyptian ultramafites still debated. [32] adopted mixing between mantle-derived CO₂-rich fluids and remobilized sedimentary carbonate. [54] suggested pure CO₂-bearing mantle source based on stable isotopes (i.e., O, C). Moreover, CO₂ input from mantle and metamorphic-degassing was proposed to explain the origin of the magnesite veins in serpentinites from the ED e.g., [55, 56]. Even with changes occurred during serpentinization in the mineral compositions of peridotites, geochemical data of serpentinites suggest negligible modification of major elements (except for Ca) at the hand-specimen scale e.g., [31, 50, 57]. Therefore, the low CaO contents (0.05–0.75 wt. %) in the serpentinites indicate restricted effect of Ca–metasomatism. The CaO contents are not correlated with LOI further confirming this implication. Moreover, the trace element compositions (except U and Sr) are not significantly modified during serpentinization e.g., [45, 50, 58]. Accordingly, the major and trace element data reflect the primary signature of the serpentinites protolith in subduction zones [50, 59, 60]. LOI reach up to 10.34–13.92 wt. %, which supports the role of hydrothermal alteration. In the MgO-Fe₂O₃^T-Al₂O₃ ternary diagram of [61], all samples plot in the metamorphic metasomatic field (Figure 7a). The MgO/SiO₂ and Al₂O₃/SiO₂ ratios of serpentinites agree with SSZ peridotites from fore-arc setting, Figure 6b; [29, 44]. In the Hf-Th-Nb diagram [63] used to regulate the tectonic character of ultramafic rocks, all samples plot in the destructive field of plate margins (Figure 7b). Generally, the Al₂O₃ and CaO depletion characterizes fore-arc peridotites (Figure 6a) [30, 39]. The Cr vs. TiO₂ diagram also supports the SSZ setting for the SH serpentinites, Figure 7c; [64].

Figure 7.

a) MgO-Fe₂O₃^T-Al₂O₃ ternary diagram for the ultramafic rocks. Zone after [61] and lines after [62], b) Hf/3-Th-Nb/16 ternary diagram of [63], c) Cr vs. TiO₂ plot to discriminate SSZ and MORB ophiolites after [64], d) Zr vs. Nb diagram after [65], e) Ti–V discrimination diagram [66], where Sol Hamed (SH) ophiolites (Red )compare with forearc/arc ophiolites, Troodos (blue) ophiolite from [67], Gerf (Green) ophiolite from [15] and Wadi Ghadir ophiolites (Pink) from [22] and f) Ol–Cpx–Opx diagram [68].

The studied rocks show low Al₂O₃ content reflecting depleted upper mantle source [30]. Their high Mg#, Cr and Ni are consistent with a depleted mantle peridotite source [15, 69]. The MgO/SiO₂ and Al₂O₃/SiO₂ ratios (Figure 6b) accord with peridotites generated from subduction-related magma source. It is supporting by using Zr vs. Nb binary diagram [65], all samples plot in the depleted mantle sources (Figure 7d). Comparing SH ophiolites with other ophiolites such as, Troodos in Cyprus, [67], Gerf ophiolite in South Eastern Desert [15] and Wadi Ghadir ophiolites in Central Eastern Desert [22]. Using the criteria in [64], we conclude that the chemical signature, the crystallization arrangement and mantle residue of SH ophiolites are similar to supra-subduction zone ophiolites formed in fore-arc basins based on the Ti–V variation diagram [66], (Figure 7e).

Numerous geochemical studies demonstrated restricted mobility of major elements during serpentinization and protolith primary signature were retained e.g. [50, 57, 70]. The SH serpentinites have low CaO contents comparable to ophiolitic peridotites [36]. Moreover, their low Al₂O₃/ SiO₂ ratios (mostly <0.03) are similar to fore-arc mantle wedge serpentinites suggesting that their protoliths had experienced partial melting before serpentinization which has no effect on this ratio e.g., [50, 58, 71]. Also, their low MgO/SiO₂ ratios (< 1.1) resemble serpentinised lherzolites and harzburgite [50]. They have low TiO₂ contents (0.01–0.06 wt. %) compared to depleted mantle composition but like subduction zone serpentinites [41, 50]. Their major element data consistent with harzburgitic source (Figure 7f).

7. Structural setting

7.1 Deformation history

The structure of the SH area is complex, and partially agreed [27], the area situated in a supra-structural position between three major Pan-African terranes (SE Desert, Gabgaba, and Gebeit terranes). Four deformational events can be distinguished in the Neoproterozoic rocks [72, 73, 74, 75];

• D₁ event: E–W thrust faults and related E–W (F1) folds which considered as early stages of collision of Gerf and Gabgaba arc terranes.

• D₂ event: NW–SE thrust faults and related NW–SE (F2) folds were formed, characterized by local high-P, low-T metamorphism and reflected as late stages of collision of Gerf and Gabgaba arc terranes. The mineralization in this stage is described as remobilization of Cu–Ni–Pt sulfides in ultramafic rocks, alteration talc/serpentinites and listwaenites; Talc carbonate, gold-bearing quartz veins.

• D₃ event: conjugate NNW-trending sinistral and NNE-trending dextral transpression, as well as N–trending tight folds (F3). NW–SE shear zones and open folds, crenulation cleavage, SC fabrics, sigmoidal foliation patterns that defined in late- to post-tectonic granitoids. This stage characterized by local contact metamorphism. The mineralization in this stage is styled as kaolinitized alteration zones along D3, shear zones; ferregination and silicification of copper sulfide zones and gold–quartz veins. Shortening connected to collision of east and west Gondwana; tectonic escape toward oceanic free face to N along WNW striking Najd faults.

• D₄ event: E–W dextral strike-slip and dip-slip normal faults striking NNW–SSE to N–S and E–W may be related to Red Sea rifting. This stage characterized by dike swarms along faults. The mineralization in this stage is styled as disseminated secondary uranium and anomalous secondary concentrations of Pb, Zr, Y, Nb, Ta, in late dikes.

7.2 Faults and structural analysis

The SH complex is characterized by flat-lying and steeply dipping ductile shear zones trending ENE and associated thrust sheets (Figures 2 and 8a). The strike-slip shear zones which surround the SH to the N and S show tectonic transport to the ENE where SH mass movement in this direction generated over thrusts of the SH on the volcanic–sedimentary succession. The ENE tectonic direction transport is inferred from moderately-plunging WSW-directed mineral lineation, rodding, minor fold axes and from long axes of the deformed pillows. Shears and thrust planes are characterized by either siliceous mylonites or talc iron rich schists and ankerite-carbonates.

Figure 8.

Structural analysis of Sol Hamed area.

There are three major faults on the investigated area (Figure 8b).

• The first is NE-SW trending faults and is mainly present in the volcanic-sedimentary assemblage and Gabal SH.

• The second is E-W faulting affects all the basement rocks and disturbs the NE-SW trending faults.

• The third is N-S faults are probably related to some stages of the Red Sea rifting, and affected all the rock units including sandstone and Quaternary marine sediments of the Red Sea coast.

The direction of the shear zone on the investigated area has NE, the principal stress access has WNW to EW (Figure 8a). The associated structural features are signified by:

• NNE–SSW normal faults,

• NW-SE reverse faults,

• NE–SW, NW-SE, WNW-ESE, NNE–SSW and EW quartz veins (Figure 8c).

The mineralized structures (Figure 8d), are represented by

• Quartz veins have mainly NE–SW and NNW–SSE trends

• Faults have mainly NE–SW trends

• Breccia and alteration have mainly NW-SE trend

El Sela shear zone is separated by two main faults in the direction of ENE–WSW and NNW–SSE (Figure 2). The earlier trend associated with the major shear zone is injected by quartz veins. This shear zone is dissected into three parts by two strike slip faults trending NNW–SSE. Field observations indicate that the granites are affected by different stages of alteration, mainly at El Sela shear zone. These granites are invaded by ENE–WSW quartz veins. These veins caused hydrothermal alteration associated with radioactive mineralization in the fine-grained granites. Secondary uranium mineralization is observed as canary-yellow thin layers deposited along small cracks and micro-fractures.

7.3 Kinematic indicators

Various kinematic indicators are used to fix the sense of movement with the common settled in the brittle-ductile system. The most common kinematic indicators on the SH area are mylonites (Figure 9a) and quartz fish (Figure 9b) shows dextral sense of movement. Mylonites take place in extraordinary strain zones (mylonite zones) and are understood as exhumed ductile shear zones. The sense of replacement on a shear zone is usually expected to lie subparallel to striations, stretching and mineral lineations.

Figure 9.

a) Mylonite derived from a narrow shear zone transecting a weakly deformed granodiorite. b) Quartz fish from a quartzite mylonite shows dextral sense of movement. Quartz in the matrix is dynamically recrystallized and developed an oblique foliation.

8. Ore mineralogy

The opaque mineral content in the studied rock types from 2–6% of the rock volume. They are represented by sulphides, magnetite, hematite and gold.

Sulphides minerals are mainly represented by arsenopyrite, pentlandite, pyrrhotite and pyrite. Minor crystals of chalcopyrite and bornite are observed in few samples. Arsenopyrite occurs as subhedral to euhedral rhombic crystals either independent or associated with pyrrhotite (Figure 10a). It shows white color and displays strong anisotropism of blue color. Pentlandite occurs either as homogeneous or zoned grains (Figure 10b). Pyrrhotite forms irregular grains with bluish shade and moderate reflectance and sometimes replaced by light creamy to yellow isotropic pentlandite (Figure 10a). Pyrite occurs as subhedral to euhedral crystals either replaced by magnetite (Figure 10c). The replacement of pyrite by magnetite indicates oxidizing conditions.

Figure 10.

Photomicrograph showing a) Pyrrhotite forms irregular grains with bluish shade and moderate reflectance and sometimes replaced by light creamy to yellow isotropic pentlandite, b) Pentlandite occurs either as homogeneous or zoned grains, c) Magnetite forms well-formed euhedral crystals, d) Gold as inclusions in arsenopyrite crystals and e) Pyrite-arsenopyrite contacts and The gold grains range in color from yellow to creamy yellowish color and with occur as sub-rounded grains or as straight-edged grains.

Magnetite appears as anhedral crystals with peripheral granules of pyrite. Magnetite forms well-formed euhedral crystals of light gray color and moderate reflectance (Figure 10c). Hematite exhibits whiter color and cherry red internal reflection. It shows isotropism in minor parts, which reveals its alteration from previous existing magnetite.

Gold is only recorded in highly altered quartz veins associated with the granitic masses. It occurs as disseminated grains that have bright yellow color with greenish tint. These grains occur as inclusions in arsenopyrite crystals (Figure 10d) and at pyrite-arsenopyrite contacts (Figure 10e). The gold grains range in color from yellow to creamy yellowish color and with occur as sub-rounded grains or as straight-edged grains (Figure 10d and e).

9. Economic potentiality

9.1 Magnesite mineralization

Economically, the important magnesite deposits occur in two types: the Venarch and Kraubath type [76]. The Venarch type deposits have the world’s largest reserves [76]. They form strata-bound lensoid bodies of coarsely crystalline spar-magnesite hosted by marine sediments. Genetically, they are associated with shallow marine water of chloride-type evaporites. Kraubath type deposits are cryptocrystalline magnesite [76] and less common than spar-magnesites. However, they are important because of their high-quality magnesite product. These deposits comprise stock-works and veins of white magnesite formed in ultramafic country rocks. The origin of Kraubath magnesite type deposits favor hypogene-hydrothermal formation [76].

Magnesite deposits of SH serpentinites are cryptocrystalline formed by hydrothermal solution effects on the serpentinite host rocks and occur in three forms. The first is represented by white patches consisting of vertical veins and horizontal sheets. The second is found as veinlets represented by stock-work shape, characterized by nodules clusters and exposed as pockets within the serpentinites. The third is widespread in Wadi Diit NE of Gabal SH and is intercalated with surficial deposits. It is found as veinlets with stock-work shape and has low grade magnesite ore. These features are consistent with Kraubath type deposits (Figure 11).

Figure 11.

Kraubath type of magnesite deposit model after [76].

The magnesite pockets exposed at the NE ends of SH serpentinites and along NNE trending shear zone (Figure 2). The magnesium source in magnesite is likely the magnesium-rich minerals (e.g., serpentine, olivine) occurred within ultramafics. Serpentinite appears to be the host for over 90% of all known magnesite veins worldwide.

The chemical data of magnesite ore is recalculated and presented in Table 2. The collected samples contain average (wt. %) 42.98 MgO, 0.57 SiO₂, 0.09 Fe₂O₃, 4.5 CaO, and 0.023 P₂O₅. They show depletion in some incompatible major elements (i.e., Ca, Al and Na) relative to the average primitive composition of upper mantle [77]. Possibly some of this CaO might has been lost during serpentinization [78] and shows strongly negative correlation with MgO (Pearson correlation factor = −0.864) in Table 3. Iron also shows loss during serpentinization.

	MgO	CaO	SiO2	Na2O	K2O	P2O5
MgO	1
CaO	−0.864	1
SiO2	−0.27	0.139	1
Na2O	0.36	−0.308	−0.124	1
K2O	−0.086	0.138	−0.01	−0.041	1
P2O5	−0.047	0.254	−0.236	−0.316	−0.052	1

Table 3.

Pearson correlations between oxides in magnesite mineralization.

9.2 Gold deposits

Ophiolitic serpentinites surrounded the metavolcano-sedimentary assemblage are the likely sources for gold mineralization in the vein-type gold deposits which invaded the island-arc volcanic and volcaniclastic rocks and/or the granitic rocks [79, 80].

The vein-type mineralization occurred in the sheared ophiolitic serpentinites (Figure 12a) associated with the Pan-African Orogeny. Linear zones of serpentinites display abundant alterations along thrusts and shear zones with the development of talc, talc-carbonate and reddish-brown quartz-carbonate rock (i.e., listwaenite) (Figure 12b). Listwaenite is commonly mineralized with gold [81, 82]. Malachite-bearing quartz veins with NW-SE direction cut through gabbroic rocks and show mylonitic structure, pinch and swell phenomenon. They are extremely fractured containing considerable content of malachite and disseminated sulfide minerals (Figure 12c and f). Mineralized smoky quartz veins with NE-SW direction and steeply dipping SE invaded the meta-andesite (Figure 12g). They are intensively sheared and contain iron oxides in the fissures and cracks (Figure 12d–f). The barren quartz veins are nearly vertical and have E-W directions (Figure 12f). The highest gold grades are associated with strong arsenopyrite mineralization and in fracture-seal veins.

Figure 12.

Field photographs show a) quartz vein between metagabbro and serpentinites, b) the listwaenite within dismembered serpentinite, c) Malachite-bearing quartz veins, d) Brecciated quartz vein containing iron oxides in the fissures, and e) Smoky quartz vein with visible gold. Rose diagram showing f) Alteration zone and various types of quartz veins, and g) the dipping of smoky quartz vein.

Mineralized alteration zones trending NW-SE and dipping nearly vertical traverse metagabbro and metavolcanics (Figure 12f). They are characterized by the presence of hematite, limonite, goethite and fresh pyrite. They occur either neighboring the auriferous quartz veins. The common types of alteration are silicification, sulphidation, carbonatization, listwaenitization.

10. Conclusions

1. Sol Hamed (SH) area as a part of the ANS ophiolites occurred within Onib-Sol Hamed suture zone in the southern Eastern Desert of Egypt. The ophiolitic assemblages in this area are represented by serpentinite, metagabbro and arc assemblages represented by metavolcanics. They later intruded by gabbroes and granites.

2. Geochemically, the compatible trace elements (Cr-Ni-Co) enrichment in SH serpentinites indicate derivation from a depleted mantle peridotite source. They show affinity to the typical metamorphic peridotites with peridotitic komatiite nature. The normative compositions reflect harzburgitic mantle source. Their Al₂O₃ contents (0.05–1.02 wt. %) are akin to oceanic and active margin peridotites and Pan-African serpentinites. The Cr and TiO₂ contents indicate SSZ environment with tectonic character destructive plate margins and depleted mantle sources. Their Al₂O₃/SiO₂ and MgO/SiO₂ ratios support the SSZ affinity and are similar to ANS peridotites with fore-arc setting. Low value of Al₂O₃/SiO₂ (fore-arc field), suggesting that these rocks were derived from a mantle source with high degrees of partial melting. Moreover, their Al₂O₃ and CaO depletion is typical of fore-arc peridotites. The normative compositions replicate harzburgitic mantle source.

3. Structurally, the area represents four deformational events can be distinguished in the Neoproterozoic rocks (D₁, D₂, D₃ and D₄); D₁: E–W thrust faults and related E–W (F₁) folds; D₂: NW–SE thrust faults and related NW–SE (F₂) folds were formed; D₃: conjugate NNW-trending sinistral and NNE-trending dextral transpression, as well as N–trending tight folds (F₃) and D₄: is E–W dextral strike-slip and dip-slip normal faults striking NNW–SSE to N–S and E–W may be related to Red Sea rifting. There are three major fault sets affected the area. The first set trend mainly NE-SW and is manifested in the volcanic-sedimentary assemblage and Gabal SH. The second set trend E-W affecting all the basement rocks and disturbs the first fault set. The third set trend N-S affected all the rock units.

   The associated structural features with shearing are showed as fallowing:

• NNE-SSW normal faults,

• NW-SE reverse faults,

• NE-SW, NW-SE, WNW-ESE, NNE-SSW and EW quartz veins.

  The mineralized structures are exemplified by

• Quartz veins have mainly NE-SW and NNW-SSE trends,

• Faults have mainly NE-SW trends,

• Breccia and alteration have mainly NW-SE trend.

1. Magnesite ore deposits in SH serpentinites is cryptocrystalline formed due to hydrothermal alteration of the serpentinite host rocks. It occurs as snow-white veins and stock-works. These characteristics are typical of Kraubath type magnesite deposits.

2. Gold mineralization is confined to malachite-bearing quartz veins, smoky quartz veins and alteration zones. The gold grades increase with arsenopyrite occurrences.

Acknowledgments

The first author is grateful to Shalaten Mineral Resource Company specially, Mr. Sherif El Shahawy (CEO) and Mr. Abdelmagid Mohamed Abdelmagid (Managing Director) also my spiritual father Brigadier General Wael Abu Hamda and my friends in geology section for helping during geologic field work. He also, thanked his mother and his wife for continuous support. And his first baby Seila.

Additional information

Parts of this chapter were previously published in a preprint by the same author: [Tarek Sedki Shehata Ali, Haroun A. Mohamed and Rafat Zaki] [2019]. [Unpublished preprint]. [Minia University]. Available from: [Sedki, T.; Ali, S.; A. Mohamed, H.; Zaki, R. Sol Hamed Ophiolitic Complex, Southern Eastern Desert, Egypt: Petrological, Economic Potentiality and Structural Implications. Preprints 2019, 2019100079. https://doi.org/10.20944/preprints201910.0079.v1 Sedki, T.; Ali, S.; A. Mohamed, H.; Zaki, R. Sol Hamed Ophiolitic Complex, Southern Eastern Desert, Egypt: Petrological, Economic Potentiality and Structural Implications. Preprints 2019, 2019100079. https://doi.org/10.20944/preprints201910.0079.v1].