Journal of African Earth Sciences 140 (2018) 60e75

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Journal of African Earth Sciences

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Origin and prospectivity of heavy mineral enriched sand deposits along the coastal areas

* M.Y. Ali a, , P. Hibberd b, B. Stoikovich c a The Petroleum Institute, P O Box 2533, Abu Dhabi, United Arab Emirates b Northcliff, Johannesburg, South Africa c Windellama Capital Limited, Surrey, UK article info abstract

Article history: Sixty-one heavy mineral enriched samples along the Somaliland coast from Eil Sheikh to Ras Khatib, a Received 11 September 2017 distance of about 130 km, were analyzed using X-ray Fluorescence, X-ray Diffraction and SEM-EDS Received in revised form techniques. This study reveals that a considerable amount of heavy minerals is present along the 16 December 2017 Somaliland coast and confirms the presence of high concentration titanium and iron bearing minerals. Accepted 19 December 2017 However, the backshore deposits in the mouths of Waaheen and Biyo Gure ephemeral rivers as well as Available online 22 December 2017 raised paleo-beaches in the east of port city of demonstrate the highest level of titaniferous heavy minerals with most samples showing concentration greater than 50 wt %. The titanium detected in Keywords: Heavy minerals geochemical analysis occurs in the form of ilmenite, rutile, titanite and titaniferous magnetite. Also, Backshore present in minor or trace amounts, are garnet, zircon and monazite. Paleo-beach Heavy mineral accumulations in the east and west of Berbera have different mineralogical assem- Sand dunes blages. The east of Berbera is dominated by quartz with moderate concentration of plagioclase, K-feld- Ilmenite spar, magnetite, hematite and titanium bearing minerals, whereas in the west of Berbera, the dominant Rutile minerals are quartz, K-feldspar and plagioclase with variable proportions of ilmenite, rutile, mica, Magnetite amphibole and pyroxene. These variations in mineral assemblages suggest different composition of the Somaliland catchment areas that supply sediment to these deposits. The catchment area in the east of Berbera Gulf of Aden consists mainly of Proterozoic crystalline basement of the Qabri Bahar complex, Gabbro-Synenite belt and granitic intrusions that outcrop in Hudiso, Tulo Dibijo and surrounding areas. The primary sources of heavy minerals in the west of Berbera comprise of high-grade metamorphic rocks of the Mora and Qabri Bahar complexes as well as the Miocene volcanics that outcrop in Laferug and Hagabo areas. The heavy mineral sand deposits observed along the Somaliland coast have the potential to provide commercially important heavy minerals, in particular ilmenite. It appears that prospects for develop- ment of the heavy mineral sands in the east of Berbera are better than those to the west of Berbera. In general, east of Berbera has wider beaches, better heavy mineral sands in the upper horizons and dune areas with heavier mineral sands. Furthermore, a series of raised paleo-beaches with high concentrations of heavy mineral sands are observed 1e2 km behind the shoreline. However, further investigation, including drilling and laboratory analyses, still needs to be carried out, particularly close to the entrance of Waaheen and Biyo Gure ephemeral rivers to evaluate the potential quality and scale of the deposits. © 2018 Elsevier Ltd. All rights reserved.

1. Introduction existing rocks of mainly high-grade metamorphic and igneous origin. Rivers and ephemeral streams transport the detrital sedi- Heavy mineral deposits are unconsolidated detritus sediments ments to the coastal areas where the action of waves, longshore that accumulate in coastal environments both on beach and coastal currents, tides and winds mechanically sort and concentrate the sand dunes. These deposits derive from the weathering of pre- dense minerals. These processes lead to the accumulation of distinct layers of dense sediments in a variety of coastal deposi- tional environments, such as foreshore, shoreface, lagoonal and

* Corresponding author. sand dune environments (Force et al., 2001). E-mail address: [email protected] (M.Y. Ali). Studies on heavy mineral deposits around the world including https://doi.org/10.1016/j.jafrearsci.2017.12.024 1464-343X/© 2018 Elsevier Ltd. All rights reserved. M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 61 in Australia (Hou et al., 2011; Roy, 1999; Roy and Whitehouse, 2003; and Daniels, 1984). These terranes amalgamated during the Neo- Roy et al., 2000), Brazil (Dillenburg et al., 2004; Leonardos, 1974), proterozoic compressional event of island-arc and microcontinent India (Acharya et al.,1998; Ali et al., 2001; Behera, 2003; Gujar et al., terrane accretion that led formation of the Afro-Arabian margin of 2010; Rao, 1957), United States (Carpenter and Carpenter, 1991; Gondwana (Al-Husseini, 2000; Husseini, 1989; Loosveld et al., Force et al., 2001; Pirkle et al., 1989) and Africa (Tyler and 1996; Sassi et al., 1993; Warden and Daniels, 1982, 1984). Minnitt, 2004; Van Gosen et al., 2014) have focused on the eco- Kroner€ and Sassi (1996) reported the oldest rocks in the base- nomic viability of these deposits. These studies have shown that ment of Somaliland. They suggested that, from zircon ages, Soma- heavy mineral deposits are the principal source of most of the liland basement consists of pre-Pan African Proterozoic crust world's commercially produced ilmenite, rutile, zircon and mona- ranging in age between ~1400 and ~1820 Ma. Four basement zite which are used for pigments and refractory industries (Van complexes outcrop in the drainage area: Qabri Bahar complex, Gosen et al., 2014). Furthermore, Armstrong-Altrin (2009), Mora complex, Gabbro-Syenite belt and Younger Granites. The Armstrong-Altrin et al. (2012, 2017, 2014, 2015b), Tapia- Qabri Bahar complex consists of high grade polymetamorphic Fernandez et al. (2017) conducted mineralogy and geochemistry layered paragneisses, migmatites, porphyric orthogneisses and of coastal sands along the Gulf of Mexico. These studies described plagioclase-amphibolites (Kroner€ and Sassi, 1996; Sassi et al., 1993). the textural differences among distinct depositional environments The Mora complex, which occurs on the westernmost side of the and recognized abundant heavy minerals such as magnetite, drainage area, is characterized by the occurrence of abundant ilmenite, rutile and zircon. marbles, quartzites and amphibolites. These are associated with Commercial evaluation of heavy mineral deposits in Somaliland high grade paragneisses and migmatites, which are closely similar has been somewhat neglected over the last 20 years. The presence to those occurring in the Qabar Bahar complex (Kroner€ and Sassi, of heavy mineral deposits in Somaliland was only reported by 1996; Sassi et al., 1993). The Gabbro-Syenite belt consists of Abdalla et al. (1993) who analyzed twelve samples from black sand numerous bodies of layered gabbro with minor alkaline granitoids deposit of Batalaleh beach in Berbera. They reported grain sizes of (Dal Piaz, 1987). Field relationships indicate that the gabbros were black sand ranging between 0.063 and 1 mm. Gravity separation intruded into already deformed rocks of the Qabri Bahar and Mora suggested a split of 59.4% of light (mainly quartz) and 40.76% of complexes (Daniels et al., 1965; Hunt, 1960) and that the syenites heavy minerals, which consist of magnetite (19.75%), ilmenite and granitoids are slightly younger than the gabbros. The basement (8.33%), zircon (0.36%), monazite (0.27%), and rutile (0.18%) (Abdalla is intruded by granitoids that crosscut all rock complexes with et al., 1993). radiometric ages of 515e550 Ma, known as Young Granites The purpose of this study is to explore the presence of titanif- (Greenwood, 1960; Mason, 1962; Sassi et al., 1993). erous heavy mineral deposits along the Somaliland coast and assess The crystalline basement is covered by Mesozoic-Quaternary the economic viability for mining these deposits. We collected sedimentary and volcanic sequences. The Jurassic sequence con- heavy mineral sand samples from sixty-one locations of different sists of Adigrat sandstones which are comformably overlain by environments along the coast. The main objective of this investi- transgressive marine carbonates with minor interbedded marl- gation was to determine the major mineralogy and elements of stones of Bihendula Group (Ali and Watts, 2016). The Cretaceous these samples as well as mineralogical phases within selected succession consists of highly weathered coarse-grained quartz-rich samples. In addition, we evaluated the compositional differences sandstones (Ali and Watts, 2016). The early Cenozoic successions between the east and west of Berbera beach areas and inferred consist of carbonates of Auradu, Taleh (or Gypsum-Anhydrite Se- paleo-weathering and provenance. We recognized reasonable ries) and Karkar Formations. Oligocene and Miocene sediments are concentration of titaniferous heavy minerals of ilmenite and rutile mostly restricted to narrow and isolated sub-basins along the as well as zircon in three different types of environments: back- coastal belt bordering the Gulf of Aden (e.g. Daban basin), occa- shores, paleo-beaches and sand dunes. The results indicate the sionally extending inland in low-lying regions. The sequence was economic potential of these deposits. However, more detailed deposited in localized grabens caused by the rifting of the Gulf of studies are required to determine the grade, quality and scale of Aden. It consists of a thick sequence of red-brown, green sand and these deposits. silts, gypsiferous sandstone, and gypsiferous sands and marls (Abbate et al., 1993a). 2. Geological setting Furthermore, Early Miocene to Pliocene basalt and other vol- canic rocks outcrop west of the port city of Berbera (Fig. 1) The study area is situated in the coastal region of the Somaliland (MacFadyen, 1933; Mackay et al., 1954). The most prominent vol- coast along the southern Gulf of Aden that extends 130 km from Eil canic cone is Mount Elmis, 15 km southwest of , which Sheikh to Ras Khatib between degrees longitude 44150E and comprises basaltic lava flows that extend southwards and east- 45250E(Figs. 1 and 2). Beyond Ras Khatib it is believed that most of wards for 70 km. This volcanic activity occurred as a consequence of the drainage falls outside the Proterozoic crystalline basement the Afar plume and the rifting of the Gulf of Aden (Ali, 2015). source belt, with the marine sediments showing noticeably lower Geomorphologically, the study area is divided into two main heavy mineral sand concentrations. However, the dunes did still physiographic regions: (1) the lower-lying coastal plains along the show a considerable volume of mafic minerals on scarp slopes. Gulf of Aden (generally known as the Guban), lying between the The crystalline basement outcrops immediately to the south of plateau escarpment and the coast, and (2) the uplifted plateau the Somaliland coast in an east-west orientated strip running escarpment (known as Golis) running east-west parallel to the Gulf parallel to the escarpment of the Somaliland Plateau (Fig. 1). The of Aden coastline in an almost continuous line across the country. basement is exposed as a result of uplift related to the separation of Long and narrow ephemeral streams dissect the plateau and the Africa from the Arabian Peninsula during the Oligocene-Miocene Guban, resulting in complex well-integrated dense drainage sys- (Ali and Watts, 2015; Warden and Daniels, 1984). The basement tems that transport sediments from crystalline basement in the consists of Proterozoic terranes (metamorphic and magmatic south to the Gulf of Aden coastline in the north. In addition, the rocks), approximately 600 km by 30e60 km wide, extending from drainage patterns south of Berbera shift to the east and accordingly the Ethiopian border to Las Khoreh, and is considered to be the the marine sediments to the east and west of Berbera have different northeastern limb of the Mozambique belt (Abbate et al., 1993b; source rocks. Therefore, most of the drainage tributaries converge Farquharson, 1926; Greenwood, 1960; Sassi et al., 1993; Warden into Waaheen and Biyo Gure ephemeral rivers (Figs. 1 and 2). The 62 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75

MAP LEGEND -4828 -2327 -1390 -46 206 670 887 1109 2218 Faults Topography/Bathymetry (m) Ras Hatib Oligocene Ras Khatib 16˚ Pleistocene-present Cretaceous

10°40' YEMEN Miocene-Pliocene Eocene Jurassic basalt Basement Miocene Paleocene 14˚ (undifferentiated) Gulf of Aden 01020Siyara 12˚ (km)

Indian 10°30' 10˚ SOMALILAND Ocean Batalaleh 43˚ 45˚ 47˚ 49˚ 51˚ 53˚ Biyo Gobare Eil Sheikh Berbera Gure Alwein Ari Adeso Bulhar Geri Dubriyad Elmis Waaheen

10°20'

Daban

Daragodleh 10°10' Bihendule Hagabo Gel lokor

Hamas Lalays Tulo Dibijo

Laferug Hudiso

10°00' 44°20' 44°30' 44°40' 44°50' 45°00' 45°10' 45°20'

Fig. 1. Simplified geological and structural map of the study area (modified from Hunt and Mason (1957); Mason and Warden (1971a, 1971b)). Blue lines represent drainage patterns. Insert shows bathymetric and topographic map of the Gulf of Aden showing major fracture zones and the study area (red rectangle). The bathymetric and topographic data are based on a 1 1 min GEBCO (IOC et al., 2003) and SRTM30 Plus grid (Becker et al., 2009). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Waaheen has very wide mouth and many tributaries. The catch- the samples that weighed about 2 kg each. In some places, this was ment area of Waaheen covers the crystalline basement west of repeated at different beach levels. The paleo-beach was partially Berbera in the areas of Laferug and Hagabo which are dominated by lithified and we were only able to collect surface samples during the Qabri Bahar and Mora complexes as well as Miocene basalt. The this study. The backshore and paleo-beach areas exhibit heavy Biyo Gure has a very narrow mouth and fewer tributaries. It drains mineral laminations that ranges in thickness from 0.5 to 10 cm. crystalline basement outcropping in the Hudiso area which mainly These laminations together with interbedded light sands are consists of the Qabri Bahar complex and Gabbro-Syenite belt. laterally continuous for at least hundreds of meters (Fig. 3). The sand dunes contain more or less discontinuous heavy mineral laminations. 3. Methodology The heavy mineral sand samples were processed and analyzed at the SGS South Africa (Pty) Ltd. An aliquat of each sample was Sixty-one samples were collected to assess the heavy-mineral pulverized and submitted for chemical analyses. The chemical an- content of coastal sediments in the study area (Fig. 2). Thirty of alyses consisted of major element analyses including Fe2O3 and these samples were collected from the east of Berbera and thirty- TiO2 by Borate Fusion X-ray Fluorescence (XRF). In addition to this, one from the west of Berbera. The samples were collected in ten samples were selected for X-ray Diffraction (XRD). A ~50 g different environments such as backshores, paleo-beaches and aliquot was split from each of the ten samples and submitted for dunes (Fig. 3). However, most of these samples were collected from XRD. The samples were analyzed by XRD utilizing a Panalytical the backshore areas as these contained the most visible concen- X'Pert Pro Diffractometer employing Co-Ka radiation. Data inter- tration of heavy minerals and were more easily accessible. Few pretation was done by means of Panalytical Highscore Plus samples were collected from the raised paleo-beaches and dune analytical software and the PDF2 database. The XRD analysis was fi elds immediately inland, which become more prominent to the used to identify the major mineralogy of each sample. Due to the east of Berbera. The study area and surrounding region are sparsely large number of samples, the resulting patterns underwent cluster populated with few dirt roads connecting villages. Therefore, the analyses. The cluster analysis enabled identification of mineralog- area further east up to and around could not be accessed ical similarities between the samples based on their XRD pattern. during this study due to access limitations. However, from satellite Furthermore, two of the samples (W16 and E1), one from the west images (Fig. 2), this area does have heavy mineral sand deposit of Berbera and other from the east of Berbera, were examined by fi along the backshore areas and a large interior dune eld with Scanning Electron Microscope (SEM) to describe the major phases strong heavy mineral showings. and to determine if titanium occurs in silicate phases. The sampling points were located at an interval of ~1e4 km, and they were collected from pits that were dug to a depth of 0.5e1m. The pits were cleaned and controlled scrape of the sidewall formed M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 63

Fig. 2. Satellite image of the study area. White triangles show sample locations and white squares represent major towns and villages. Major ephemeral rivers of Waaheen and Biyo Gure are also labelled.

4. Analytical results Berbera (Table 1a) than for those samples in the east of Berbera (Table 1b). 4.1. Geochemistry and mineralogy In addition, on average the CaO and MgO contents are slightly higher in the samples from the east of Berbera compare to those 4.1.1. Major element concentrations samples in the west of Berbera. In contrast, the samples from the The major element concentrations of analyzed heavy mineral east of Berbera are slightly depleted in K2O and Na2O contents sands by XRF are listed in Tables 1a and 1b. The major element compared to those samples in the west of Berbera (Tables 1a and results show wide differences in composition among the samples 1b). The variations in the remaining major elements (e.g. MnO and from the east and west of Berbera. The SiO2 content for the samples P2O5) are not significant for both samples from the east and west of in the west of Berbera are quite variable from ~15 to 87 wt%. Among Berbera. The differences in concentration of major elements among these samples, three samples (W16, W17 and W18) show low SiO2 the samples in the east and west of Berbera probably indicate effect content ranging from 15 to 38 wt%. The TiO2 concentration is also of sediment sorting or most likely differences in source rocks. higher (11e20 wt%) in these three samples (Table 1a). Furthermore, e these three samples are enriched in Fe2O3 (30 48 wt%). The vari- 4.1.2. Mineralogy based on XRD ability of the SiO2 content for the rest of the samples in the west of Table 2 shows the general mineral assemblages and abundances Berbera vary from 54 to 87 wt% (Table 1a). Similarly, there is a wide which were calculated using XRD data of ten selected samples. The scatter in SiO2 content for the samples in the east of Berbera crystalline phases that were detected by XRD are shown in the ranging from 2 to 78 wt%. However, six samples (E9, E10, E20, E23, diffractograms (Fig. 4a and j). The XRF results indicate that gener- E24 and E25) have low SiO2 content ranging from 2 to 34 wt% ally samples have a high SiO2 content, this was confirmed with the (Table 1b). As in the west of Berbera, these samples have high diffractograms, which showed prominent peaks for silica bearing fl concentration of Fe2O3 and TiO2, which probably re ect the abun- minerals like quartz and plagioclase. On XRD examination, some of dance of Ti-bearing heavy minerals such as magnetite and ilmenite. the samples (e.g. W16) revealed that they are constituted of The SiO2 content variability of the rest of the samples is reduced to ilmenite and rutile, with minor amounts of monazite and zircon. 45e78 wt% (Table 1b). Therefore, in general the samples from the Geochemical data also reveal a strong presence of iron bearing west of Berbera have higher SiO2 content than those in the east of minerals, hematite and magnetite. The remaining mineral assem- Berbera. blage was generally concentrated with amphiboles, calcite and The Al2O3 content ranges from 3.43 to 14.50 wt% and garnet. 1.39e14.3 wt% for the samples in the west and east of Berbera, respectively (Tables 1a and 1b). However, the average Al O content 2 3 4.2. Texture and mineralogical compositions based on SEM analysis is slightly higher in samples from the west of Berbera. Similarly, the average Al O /TiO ratios are higher for the samples in the west of 2 3 2 The SEM examination was conducted in order to describe the 64 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75

Fig. 3. Field photos showing a) heavy mineral deposit in a beach east of Berbera, b) sample location showing laminations of heavy mineral sands. The depth and width of the pit are ~0.5 m and 0.3 m respectively. d) Raised paleo-beach exhibiting evidence of heavy mineral sands. e) Sand dunes in northeast of Berbera. major phases as well as to determine if titanium occurs as silicate analysis (Fig. 6g and h). phases such as biotite. In addition, it was used to identify and Generally, ilmenite is the dominant heavy mineral, and it confirm the presence of certain titanium bearing minerals as well comprises, on average, 30 wt% of the assemblage in cluster 1 as their associated minerals. From the microphotographs taken, (Table 3). Ilmenite mostly occurs as opaque subhedral to euhedral relative textures between the various minerals can also be seen. grains (Figs. 5a and 7a). Some ilmenite occurs as lens-shape poly- Two samples were selected to undergo analysis by SEM. The se- crystalline grains due to intergrowths of magnetite and ilmenite lection of the two samples (W16 and E1) were based on the XRD (Fig. 7a). The ilmenite that concentrates in cluster 1 (Table 3) and XRF results. Samples showing adequate titanium concentra- generally contains ~67% TiO2 and 33% Fe2O3 (Fig. 8a and Table 2). tions were chosen. The SEM microphotographs and EDS (Energy The average rutile content of cluster 1 (Table 3) is 2.5e3.2 wt%. It Dispersive Spectroscopy) spectrums are shown in Figs. 5e8 and occurs as dark red to brownish in color. Grains are rounded to sub- depict range of minerals found within the selected samples. rounded in shape, which indicates that they are sourced from The samples from the backshores in all cases showed the sands reworked sediments (Fig. 5a). Some rutile samples are in anhedral to be well sorted. In addition, the heavy minerals show a similar form, which indicates that the sediments are immature and may be pattern of grain size distribution from backshores, paleo-beach to derived from adjoining acidic igneous and metamorphic rocks. dunes and are dominantly in the size of 100e350 mm. However, The magnetite occurs as octahedral or rounded grains with thin silty intercalations are observed at the mouths of Waaheen and exsolution of ilmenite (Figs. 5a and 7a). Two types (fresh and Biyo Gure ephemeral rivers. altered) of magnetite are observed (Fig. 6c and d). The fresh The particles of sample W16 range from about 40 to 350 mmin magnetite grains are sub-angular whereas the altered grains size (Fig. 5). Most mineral grains appear to be at least partially contain titanium (Figs. 5a and 7a). The amphiboles occur in blue or liberated. The mineral grains in sample E1 are also liberated and green, slightly rounded prismatic crystals (Figs. 5 and 7). The vary in size from 104 to 625 mm(Fig. 7). Quartz grains appear to be apatite is found as colorless or whitish, rounded grains (Fig. 5). The amongst the larger grains. Overall, the heavy mineral assemblages sphene generically occur as rounded, brownish yellow, anhedral recorded in this study consists of ilmenite, rutile, magnetite and grains. Polycrystalline grains due to intergrowths of sphene, apatite minor amount of zircon (Figs. 5e8). Besides these minerals, other and plagioclase is sometimes observed (Fig. 7b). The monazite heavy minerals observed include pyroxene, amphibole, garnet and grains are yellow to reddish characterized by rounded to well- epidote. Trace amounts of cerium was also detected in the form of rounded shape, and its presence indicates that they are derived monazite (Fig. 6h). In addition, minor concentration of phospho- probably from orthopyroxene granite (Fig. 5b). Monazite concen- rous (P2O5) that were observed in the XRF analysis (Table 1) occur tration is generally <0.2 wt%. Garnet grains (17.6e31.2 wt% for in the form of apatite and monazite as indicated from the SEM samples W16eW18) are mainly colorless with sharp edges that M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 65

Table 1a Geochemical results of samples collected from the west of Berbera showing major element concentration in weight %. The LOI (Lost On Ignition) results refers to the volatiles within the sample. A high LOI highlights the presence of hydrous minerals like micas. Negative LOI's result from the oxidation of reduced spinels (especially magnetite). In general, LOI for these samples were variable and displayed low to moderate values. For sample location see Fig. 2.

Element SiO2 Al2O3 CaO MgO Fe2O3 K2O MnO Na2OP2O5 TiO2 LOI Total Al2O3/TiO2 SiO2/Al2O3 K2O/Al2O3 K2O/Na2O Lower Detection 0.05 0.05 0.01 0.05 0.01 0.01 0.01 0.05 0.01 0.01 50

Upper Detection 100 100 100 100 100 100 100 100 100 100 100

Units % % % % % % % % % % % %

W1 59.00 6.75 3.90 0.53 19.20 1.81 0.41 1.80 0.12 3.42 1.87 98.81 1.97 8.74 0.27 1.01 W2 57.80 8.85 10.00 1.11 6.81 2.82 0.09 2.39 0.16 1.72 7.69 99.44 5.15 6.53 0.32 1.18 W3 59.30 3.43 7.15 1.63 11.80 0.69 0.34 0.84 0.07 4.21 6.36 95.82 0.81 17.29 0.20 0.82 W4 54.90 12.80 8.36 2.95 4.55 3.26 0.07 2.80 0.23 0.70 9.72 100.34 18.29 4.29 0.25 1.16 W5 70.60 8.10 4.43 1.71 8.10 1.45 0.84 1.80 0.11 2.33 1.33 100.8 3.48 8.72 0.18 0.81 W6 86.70 4.86 2.28 0.32 1.63 1.38 0.03 1.41 0.03 0.36 1.36 100.36 13.50 17.84 0.28 0.98 W7 62.50 10.40 6.77 1.71 5.56 3.14 0.08 2.68 0.19 1.55 5.58 100.16 6.71 6.01 0.30 1.17 W8 76.40 4.53 6.78 1.94 3.32 0.77 0.07 1.22 0.07 0.48 4.08 99.66 9.44 16.87 0.17 0.63 W9 71.40 6.01 4.27 1.66 7.78 1.63 0.16 1.65 0.09 1.71 3.41 99.77 3.51 11.88 0.27 0.99 W10 58.90 7.88 4.29 1.88 16.90 1.15 1.16 1.52 0.14 5.36 0.64 99.82 1.47 7.47 0.15 0.76 W11 70.00 7.67 6.20 1.49 5.50 1.89 0.19 2.22 0.19 1.76 3.58 100.69 4.36 9.13 0.25 0.85 W12 73.20 4.26 4.59 0.94 10.10 0.83 0.14 1.30 0.06 1.82 2.73 99.97 2.34 17.18 0.19 0.64 W13 73.70 9.20 4.00 1.47 3.60 1.86 0.06 2.45 0.09 0.64 1.95 99.02 14.38 8.01 0.20 0.76 W14 54.00 5.46 3.89 1.08 25.40 1.28 0.54 1.53 0.19 4.27 1.34 98.98 1.28 9.89 0.23 0.84 W15 70.10 11.80 4.29 0.99 2.85 3.13 0.06 3.25 0.15 0.69 2.95 100.26 17.10 5.94 0.27 0.96 W16 14.70 5.34 3.01 1.54 47.50 0.10 3.09 0.42 0.23 23.10 0.97 98.06 0.23 2.75 0.02 0.24 W17 37.60 8.71 5.39 2.57 29.60 0.48 2.83 0.79 0.28 10.50 0.06 98.81 0.83 4.32 0.06 0.61 W18 21.00 5.29 4.09 2.26 43.30 0.24 2.29 0.45 0.30 20.00 0.88 98.34 0.26 3.97 0.05 0.53 W19 67.90 8.03 5.19 2.61 8.40 1.18 0.72 1.80 0.14 2.14 1.39 99.5 3.75 8.46 0.15 0.66 W20 75.00 7.03 3.45 1.07 5.31 1.73 0.31 2.01 0.07 1.52 1.54 99.04 4.63 10.67 0.25 0.86 W21 76.00 5.20 6.92 1.49 1.71 0.94 0.05 1.32 0.05 0.32 4.60 98.6 16.25 14.62 0.18 0.71 W22 82.00 5.03 2.96 0.66 4.36 1.24 0.11 1.30 0.06 1.19 1.44 100.35 4.23 16.30 0.25 0.95 W23 63.50 11.00 7.87 1.30 3.65 3.34 0.05 2.78 0.23 0.76 6.44 100.92 14.47 5.77 0.30 1.20 W24 80.00 6.92 3.19 0.94 1.55 1.84 0.03 1.50 0.07 0.32 3.69 100.05 21.63 11.56 0.27 1.23 W25 77.70 8.37 3.34 0.65 1.91 2.39 0.05 2.10 0.07 0.40 2.15 99.13 20.93 9.28 0.29 1.14 W26 70.60 13.70 3.54 1.31 2.61 3.29 0.04 3.61 0.06 0.39 1.58 100.73 35.13 5.15 0.24 0.91 W27 69.50 14.50 3.66 1.23 2.24 3.46 0.04 3.79 0.06 0.32 1.75 100.55 45.31 4.79 0.24 0.91 W28 78.30 9.11 3.25 0.76 1.93 2.21 0.04 2.26 0.08 0.38 1.89 100.21 23.97 8.59 0.24 0.98 W29 80.40 4.52 5.42 0.69 2.21 1.07 0.05 1.32 0.05 0.39 3.89 100.01 11.59 17.79 0.24 0.81 W30 68.50 7.27 2.70 0.67 13.10 1.51 0.22 1.93 0.13 2.14 0.84 99.01 3.40 9.42 0.21 0.78 W31 77.90 8.28 3.60 0.48 2.32 2.07 0.03 2.58 0.08 0.44 2.26 100.04 18.82 9.41 0.25 0.80

suggest a short transport. Zircon comprises on average 0.5 wt% of 4.3. Cluster analysis the heavy mineral assemblage but ranges up to 1.5 wt% in samples W18 and W16 of cluster 1 (Table 3). Zircon grains are typically well Four clusters were identified and Fig. 4 shows the diffractograms rounded. Although present in minor quantities it is present in all of of selected samples from each cluster. The samples of different the samples analyzed throughout the area. However, zircon shows clusters are listed in Table 3. These samples were clustered based on a higher percentage in the western area of Berbera close to the their mineralogical similarities. Detailed descriptions of the mouth of Waaheen ephemeral river which indicate zircon bearing mineralogy of each cluster are given below. rocks (probably high-grade metamorphic rocks of Qabri Bahar Cluster 1: Samples of this cluster are dominated by heavy min- complex) in the catchment areas of Waaheen ephemeral river. eral assemblages including varying amounts of ilmenite, rutile, The SEM EDS spectrum of the ilmenite, magnetite plagioclase, zircon and minor amounts of monazite. Sample W16 in cluster 1 is amphibole, apatite and monazite are shown in Figs. 6 and 8. The primarily dominated by titanium bearing minerals namely ilmenite has high Ti and relatively low Fe (Fig. 6a). Minor amount of ilmenite, rutile and titanite as well as amphiboles. There are also Mn is also present. The chemical analysis of magnetite in sample trace amounts of zircon present. Magnetite, hematite, and garnet in W16 suggests that it occurs as pure magnetite and titaniferous the form of almandine, make up the rest of the mineral assemblage. magnetite (Fig. 6c and d). In the latter the magnetite intergrowth Quartz and plagioclase are also present in minor amounts. This with rutile, ilmenite and sphene. Another important observation is mineralogy is similar for all samples of this cluster. the higher content of calcite (4.5e9.1 wt%) in samples collected Cluster 2: Samples in this cluster are dominated by quartz and to from the east of Berbera. This is probably because the catchment a lesser extent K-feldspar and plagioclase. There is also a fair area of Biyo Gure ephemeral river includes Mesozoic and Cenozoic amount of mica present. Amphibole, rutile and pyroxene are pre- carbonate rocks (Fig. 1). sent in variable proportions. Calcite, chlorite and biotite appear in The SEM images show the detrital grains (e.g. magnetite, small amounts in samples of this cluster. Trace amounts of ilmenite monazite, ilmenite) are characterized by mechanical breaking such were detected. Sample W24 was the most representative sample of as conchoidal to sub-conchoidal fractures and irregular cracks this cluster. In addition to conforming to the basic mineralogy of (Fig. 6), which indicate that these grains are freshly derived and cluster 2, sample E1 displayed trace amounts of rutile and titanite. underwent limited transportation. Alternatively, the conchoidal to Sample W19 of cluster 2 also contained minor amounts of titanite. sub-conchoidal fractures may indicate the grains were subjected to Most of the samples in this cluster occur in the west of Berbera high energy environment developed by wave induced collision. (Fig. 2). Cluster 3: Samples in cluster 3 are dominated by quartz and 66 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75

Table 1b Geochemical results of samples collected from the east of Berbera showing major element concentration in weight %. For sample location see Fig. 2.

Element SiO2 Al2O3 CaO MgO Fe2O3 K2O MnO Na2OP2O5 TiO2 LOI Total Al2O3/TiO2 SiO2/Al2O3 K2O/Al2O3 K2O/Na2O Lower Detection 0.05 0.05 0.01 0.05 0.01 0.01 0.01 0.05 0.01 0.01 50

Upper Detection 100 100 100 100 100 100 100 100 100 100 100

Units % % % % % % % % % % % %

E1 71.70 7.16 4.50 1.21 6.17 1.59 0.12 1.81 0.09 1.31 3.48 99.14 5.47 10.01 0.22 0.88 E2 60.00 4.22 7.24 1.64 14.20 0.79 0.44 0.87 0.09 4.74 5.49 99.72 0.89 14.22 0.19 0.91 E3 75.40 8.05 5.67 1.03 1.46 2.39 0.03 1.89 0.06 0.27 4.33 100.58 29.81 9.37 0.30 1.26 E4 61.80 13.90 6.75 3.51 6.47 1.68 0.11 2.91 0.11 0.86 2.49 100.59 16.16 4.45 0.12 0.58 E5 64.90 13.10 4.02 1.92 4.37 3.20 0.07 2.68 0.10 0.64 5.56 100.56 20.47 4.95 0.24 1.19 E6 65.70 11.20 5.95 1.34 2.92 3.64 0.04 2.92 0.18 0.65 4.37 98.91 17.23 5.87 0.33 1.25 E7 52.40 4.41 5.36 2.13 27.10 0.53 0.39 0.91 0.11 3.85 1.87 99.06 1.15 11.88 0.12 0.58 E8 61.90 11.40 7.25 2.95 7.51 1.56 0.13 2.66 0.11 1.64 2.91 100.02 6.95 5.43 0.14 0.59 E9 30.20 4.63 4.35 2.56 44.70 0.25 1.02 0.58 0.18 10.30 0.06 98.71 0.45 6.52 0.05 0.43 E10 9.98 2.37 1.48 0.98 71.90 0.10 0.97 0.31 0.17 12.00 1.53 98.73 0.20 4.21 0.04 0.32 E11 48.50 4.06 5.24 2.07 30.50 0.40 0.52 0.86 0.12 6.22 1.74 100.23 0.65 11.95 0.10 0.47 E12 77.90 4.98 7.06 0.82 1.61 1.05 0.04 1.34 0.04 0.28 5.04 100.16 17.79 15.64 0.21 0.78 E13 48.40 3.49 5.11 1.70 30.40 0.43 0.46 0.78 0.10 7.57 2.00 100.44 0.46 13.87 0.12 0.55 E14 61.80 5.34 7.85 3.43 12.10 0.52 0.35 1.09 0.12 3.45 3.25 99.3 1.55 11.57 0.10 0.48 E15 58.30 4.43 7.41 2.68 15.10 0.54 0.29 1.00 0.10 5.10 3.38 98.33 0.87 13.16 0.12 0.54 E16 73.60 4.51 8.09 2.09 5.42 0.63 0.13 1.10 0.07 1.40 4.21 101.25 3.22 16.32 0.14 0.57 E17 65.40 5.55 7.88 2.77 9.42 0.54 0.28 1.26 0.10 3.38 3.90 100.48 1.64 11.78 0.10 0.43 E18 55.70 4.39 6.71 3.11 18.80 0.40 0.35 1.02 0.13 7.53 2.42 100.56 0.58 12.69 0.09 0.39 E19 53.10 5.74 8.89 6.64 17.10 0.48 0.34 1.01 0.31 4.94 1.41 99.96 1.16 9.25 0.08 0.48 E20 14.80 2.09 2.15 1.82 57.60 0.12 0.72 0.44 0.11 21.30 1.65 99.5 0.10 7.08 0.06 0.27 E21 70.20 5.91 6.48 3.09 8.04 0.59 0.14 1.36 0.12 2.09 2.32 100.34 2.83 11.88 0.10 0.43 E22 76.00 4.23 7.31 1.55 2.87 0.53 0.06 1.09 0.07 0.83 4.74 99.28 5.10 17.97 0.13 0.49 E23 22.30 3.43 22.90 2.57 23.20 0.36 0.40 0.59 0.15 8.69 16.04 100.63 0.39 6.50 0.10 0.61 E24 34.30 5.98 23.30 4.04 12.20 0.45 0.33 0.96 0.14 3.44 14.54 99.68 1.74 5.74 0.08 0.47 E25 2.37 1.39 14.30 0.85 54.90 0.06 0.51 0.18 0.10 16.5 9.33 100.49 0.08 1.71 0.04 0.33 E26 57.00 4.82 7.85 3.45 17.10 0.47 0.32 0.91 0.05 5.93 2.85 100.75 0.81 11.83 0.10 0.52 E27 72.50 14.30 3.40 0.90 3.40 3.20 0.04 2.65 0.03 0.28 0.79 99.91 51.07 5.07 0.22 1.21 E28 67.80 14.00 3.52 0.75 2.13 3.39 0.04 2.75 0.04 0.27 4.32 99.01 51.85 4.84 0.24 1.23 E29 55.00 4.50 9.50 0.14 15.10 0.03 5.47 <0.05 <0.01 10.30 0.12 99.98 0.44 12.22 0.01 0.60 E30 45.00 4.96 23.70 2.95 2.05 0.94 0.06 1.19 0.14 0.34 18.65 99.98 14.59 9.07 0.19 0.79

Table 2 Mineral assemblages and abundances in weight % for ten selected samples. For sample location see Fig. 2.

Sample W19 W18 W17 W16 E1 E2 E3 E4 E5 E6

Quartz 48.1 5.9 13.1 0.2 54.3 47.8 49.3 26.9 45.7 31.6 Plagioclase 20.1 4.3 8.0 4.3 18.6 8.8 18.3 29.3 26.9 29.6 K-feldspar 8.1 0.0 0.0 0.0 7.8 4.7 16.5 9.7 9.9 20.8 Biotite/Mica 0.3 0.0 0.0 0.0 0.7 0.9 0.6 0.4 8.2 0.3 Chlorite 0.0 0.0 0.0 0.0 0.4 0.0 0.6 0.9 0.1 0.2 Almandine/Garnet 0.0 17.6 31.2 20.6 0.0 0.0 0.0 0.0 0.0 0.0 Diopside 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Amphibole 18.3 14.2 16.0 10.1 5.7 8.1 4.3 20.6 0.4 7.8 Sphene/Titanite 3.1 6.5 10.0 3.4 0.3 0.0 0.0 0.0 0.6 0.0 Gypsum 0.0 0.0 0.0 0.0 0.0 0.9 0.0 0.0 0.0 0.1 Calcite 0.7 0.0 0.0 0.0 4.5 9.9 9.1 7.0 5.8 7.6 Siderite 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Magnetite 0.0 4.8 3.9 15.4 2.6 8.5 1.1 3.2 1.1 0.9 Hematite 0.0 10.4 3.9 4.2 2.9 4.0 0.0 1.0 0.6 0.5 Ilmenite 0.0 34.6 10.7 36.9 1.4 2.2 0.0 0.0 0.0 0.0 Rutile 0.9 0.0 2.5 3.2 0.6 3.5 0.2 0.9 0.5 0.5 Zircon 0.1 1.5 0.5 1.5 0.1 0.4 0.0 0.1 0.1 0.1 Monazite 0.0 0.2 0.2 0.1 0.0 0.0 0.0 0.0 0.0 0.0 Chromite 0.0 0.0 0.0 0.1 0.0 0.1 0.0 0.0 0.0 0.0 Tantalite 0.0 0.0 0.0 0.0 0.0 0.3 0.0 0.0 0.0 0.0 Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0

mainly occur in the east of Berbera. Plagioclase and K-feldspar are the rest of the samples in this cluster. present to a lesser extent. Moderate amounts of magnetite, he- Cluster 4: The most representative sample of this cluster is matite, titanium bearing minerals, calcite, biotite and gypsum were sample E6 which is dominated by K- feldspar, plagioclase and also detected. There were also trace amounts of sphene. Amphibole quartz. Samples of this cluster also displayed the presence of minor was present in variable amounts. This mineralogy was character- amounts of amphibole and calcite. Trace amounts of gypsum, bio- istic of sample E2, which showed mineralogical similarities with tite, chlorite and rutile were also detected. Sample E3 depicted M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 67

Fig. 4. Diffractogram showing the composition of samples a) W24, b) W19, c) W16, d) W8, e) E1, f) E2, g) E3, h) E6, i) E4 and j) E5. For sample location see Fig. 2. similar mineralogical characteristics. Sample E4 also contained the 5. Discussion overall mineral assemblage of cluster 4 but did not display the presence of gypsum. Sample E5 indicates quartz and plagioclase 5.1. Heavy mineral content dominate mineral assemblage. K-feldspar and biotite was present in variable proportions. The remaining mineral assemblage was A total of sixty-one samples were collected along the Somaliland made up of minor amounts of amphibole, chlorite calcite and coast from Eil Sheikh in the west to Ras Khatib in the east from titanite. backshores, paleo-beaches and sand dunes deposits. The study 68 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75

Fig. 5. a) SEM (Scanning Electron Microscope) microphotograph displaying variation of mineral grains in an area of sample W16. Where Mgt: magnetite; Plag: plagioclase; Rt: rutile; Ilm: ilmenite; Apt: apatite and Amp: amphibole. b) SEM microphotograph of the mineral monazite. It occurs as a liberated mineral within sample W16, where Thr: thorium and Mnz: monazite. shows that the Somaliland coast contains high concentration of and SEM analysis. In addition, samples in cluster 1 (W16eW19 in heavy mineral sands, which were derived from erosion of the the west and E9eE13 in the east) show the highest concentration nearby crystalline basement that outcrops along a narrow belt for titanium and iron bearing minerals (Table 3). These samples parallel to the coast. vary between 43.1 and 69.0 wt% of titaniferous heavy minerals with The results of the geochemical analyses indicate that generally most samples showing concentration greater than 50 wt% (Table 3). samples collected from the east and west of Berbera have a high The titanium detected in geochemical analysis was confirmed to SiO2 content (Tables 1a, 1b and 2). This observation was confirmed occur in the form of ilmenite, rutile, titanite and titaniferous with the XRD analysis and diffractograms (Fig. 4). The geochemical magnetite. Compared to ilmenite, rutile has lower amount of Fe and composition also reveals a strong presence of iron bearing min- Mn (Fig. 6a and b). The titaniferous magnetite contains ~9% of TiO2 erals, hematite and magnetite, which were identified in both XRD (Fig. 6d). In addition, trace amounts of titanium (~0.85% TiO2)were M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 69

Fig. 6. SEM EDS (Energy Dispersive Spectroscopy) spectrum of sample W16 (grains shown in Fig. 5a) showing a) ilmenite. Most mineral grains are liberated, however in some cases ilmenite occurs as exsolution in magnetite. This was common throughout the sample. Trace amounts of manganese (~1%) were found. b) rutile, c) magnetite, d) titaniferous magnetite. This grain contains ~9% of TiO2. e) plagioclase f) amphibole. Trace amounts of titanium, (~0.85% TiO2) were detected in amphiboles of this sample. g) apatite. h) monazite, which occurs as a liberated mineral within sample W16, where Thr: thorium and Mnz: monazite. detected in amphiboles (Fig. 6f). The split within the heavy mineral zircon and monazite. In view of the SEM analysis most grains fraction is fairly uniform with ilmenite and rutile comprising appear to be liberated as observed in samples W16 and E1 (Figs. 5 20e40 wt% and magnetite forming 5e20 wt%. The remainder of the and 7). Sample E1, however, shows examples of ilmenite occurring heavy mineral fraction is non-magnetic and dominated by garnet, as exsolution in magnetite. Furthermore, the monazite grains 70 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75

Fig. 7. a) SEM microphotograph of the mineral assemblage in an area of sample E1. Where Ilm: ilmenite; Qtz: quartz; Mgt: magnetite; Amp: amphibole and Plag: plagioclase. b) SEM microphotograph showing an intergrowth of minerals, where mineral 1 is sphene, mineral 2 is apatite and mineral 3 is plagioclase.

contain variable amounts of thorium and in some cases showed 2015b). In this study, the average SiO2/Al2O3 ratios of the samples discrete grains of thorite locked within the monazite grain (Figs. 5b from the east and west of Berbera are similar with average values of and 6h). The P2O5 content of the monazite grains is also higher than ~9.57 and ~9.63 respectively. However, the samples (e.g. E8eE10 that of the apatite grains (Fig. 6g and h). and W15eW18) collected closer to the mouths of Waaheen and Biyo Gure ephemeral rivers have relatively lower SiO2/Al2O3 ratios 5.2. Sediment maturity and source rock characteristics than those farther from the river mouths (e.g. E1, E2, W8, W9) indicating compositional immaturity.

The SiO2/Al2O3 ratio is widely used to determine the textural Furthermore, the Al2O3/TiO2 ratio is used to determine source maturity of sediments with high ratios indicating compositionally rock type with low values (<14) indicating mafic source rock and matured sediments (Armstrong-Altrin et al., 2012, 2014, 2015a, high values (>28) suggesting felsic source rocks (Armstrong-Altrin M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 71

Fig. 8. SEM EDS spectrum of sample E1 (grains shown in Fig. 7a) showing a) an ilmenite grain, constituting ~67% TiO2 and 33% Fe2O3. b) a magnetite grain. Magnetite grains of sample E1 do not contain any TiO2. c) an amphibole. Amphiboles of the sample E1 does not display the presence of TiO2. d) SEM EDS spectrum of the apatite (mineral 2) shown in Fig. 7b. e) SEM EDS spectrum of the plagioclase (mineral 3) shown in Fig. 7b. f) SEM EDS spectrum of the sphene (mineral 1) shown in Fig. 7b.

Table 3 et al., 2012, 2017; Girty et al., 1996; Ramos-Vazquez et al., 2017). In fi Sample cluster classi cation. For sample location see Fig. 2. this study, the Al2O3/TiO2 ratios for the samples collected from the Cluster 1 Cluster 2 Cluster 3 Cluster 4 east of Berbera range from ~0.1 to 29.8 with an average value of ~8.52. The Al2O3/TiO2 ratios for the samples collected from the west W18 W31 W14 W27 W17 W30 W10 W26 of Berbera vary from 0.23 to 45.31 with an average value of 10.62. W16 W29 W3 W23 The range in Al2O3/TiO2 ratios indicates a combination of sediments E9 W28 W1 W15 derived from different source rocks. However, in general Al2O3/TiO2 E10 W25 E2 W13 ratios probably indicate the samples from the east of Berbera were E11 W24 E7 W11 mostly derived from mafic to intermediate source rocks, whereas E13 W22 E14 W7 E18 W21 E15 W5 the samples from the west of Berbera were probably derived from E20 W20 E16 W4 intermediate to felsic source rocks. Conversely, the longshore cur- E23 W19 E17 W2 rents may have mixed sediments derived from different sources. E25 W12 E19 E3 Similarly, major element based discriminant function diagram is E26 W9 E21 E4 fi E29 W8 E22 E5 widely used to distinguish four major provenance types: ma c, W6 E24 E6 intermediate, felsic, and quartzose recycled (Armstrong-Altrin E1 E27 et al., 2015a, 2015b; Ramos-Vazquez et al., 2017; Roser and E8 E28 Korsch, 1988). In this study, most of the samples of the east and E12 west of Berbera mainly plot in the felsic and quartoze provinces. E30 However, few samples plot in the intermediate and mafic igneous 72 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 provenances (Fig. 9). This indicates that the samples of the east and collected in the west of Berbera. The major element provenance west of Berbera were derived from rocks of wide range of discriminant diagram (Fig. 9) also supports this interpretation. composition. 5.4. East of Berbera 5.3. West of Berbera Backshore: As in the west, the eastern Berbera backshore sands Heavy mineral concentration in the west of Berbera ranges be- are highly visible and can be seen clearly on satellite images (Fig. 2). tween 4.1 and 69.0 wt% (Tables 1a and 2). The most common heavy The latter was one of the most valuable tools along a shoreline with mineral assemblages observed are magnetite and ilmenite. Other difficult access, and gives a good indication of their development as heavy minerals include garnet, zircon, rutile, sphene, apatite and well as the amount of heavy mineral in the back dunes. The de- monazite. However, the concentration of heavy minerals in the area posits appear quite classical in most respects and the formation and varies considerably. In samples W16, W17 and W18 (close to Geri, profile of the beaches are similarly uniform. The beaches were Fig. 2) the concentration of titaniferous heavy minerals is high found to contain strong heavy mineral development and the beach (43.1e60.0 wt%). These samples were collected at the entrance of itself was better developed showing a clear strandline, high tide the Waaheen ephemeral river to the sea. These samples are also berms, storm berm and backshore mineralization (Fig. 3). Overall, rich in garnet and other heavy minerals. Samples collected away widths were greater than those found in the west of Berbera from the Waaheen tend to have lower concentration. Therefore, the although the same rhythmic layering was evident. trend of heavy mineral concentration show that the concentration The samples of backshore sediments in the east of Berbera decreases east and west away from the Waaheen ephemeral river. (E1eE31) exhibit a noticeable variation in heavy mineral content, The observed heavy mineral assemblages suggest derivation of which consists of ilmenite, rutile and zircon. The mineral grains are these minerals from the uplifted plateau of Mora and Qabri Bahar well liberated, rounded to sub-rounded. However, in some cases complexes as well as the Miocene volcanics that outcrop in the ilmenite occurs as exsolution in magnetite (Fig. 7). Although it is catchment area (Laferug and Hagabo) of Waaheen ephemeral river. not as enriched in the higher value zircon and rutile as in the west In the Laferug area, the crystalline basement is composed of pink of Berbera and other classical deposits, for example heavy mineral gneisses that consists of pink feldspar with varying amounts of sand deposits in Australia (Roy, 1999; Roy and Whitehouse, 2003; quartz (Hunt, 1960). In addition, hornblende schists and gneisses Roy et al., 2000) and Gulf of Mexico (Tapia-Fernandez et al., with or without biotite also outcrop in the area. Therefore, feld- 2017), the high ilmenite grades and proximity to the existing spathic gneisses that outcrop in the catchment area appears to be deep-water port of Berbera could lead to better commercial pros- the major source for the high concentration of K-feldspar and other pects for mining. heavy mineral assemblages that was observed from the samples The results of this study agree well with that of Abdalla et al.

Fig. 9. Major element provenance discriminant function diagram (Roser and Korsch, 1988) for samples collected from the east and west of Berbera. The discriminant functions are: discriminant function 1 ¼ (1.773 TiO2) þ (0.607 Al2O3) þ (0.760 Fe2O3) þ (1.5 MgO) þ (0.616 CaO) þ (0.509 Na2O) þ (1.224 K2O) þ (9.09); discriminant function 2 ¼ (0.445 TiO2) þ (0.07 Al2O3) þ (0.25 Fe2O3) þ (1.142 MgO) þ (0.438 CaO) þ (1.475 Na2O) þ (1.426 K2O) þ (6.861). M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 73

(1993), who analyzed twelve samples from the black sands of the the high concentration of magnetite, quartz and other heavy min- Batalaleh beach immediately east of Berbera. Abdalla et al. (1993) erals observed in the east of Berbera. In support of this interpre- found grain sizes of black sands ranging between 1 mm and tation, the discriminant function diagram (Fig. 9) shows samples 0.063 mm, which consists of 59.4% of light (mainly quartz) and from the east of Berbera plot in all four provenances (mafic, inter- 40.76% heavy minerals. The heavy minerals consist of magnetite mediate, felsic and quartzose), which indicate the samples were (19.75%), ilmenite (8.33%), zircon (0.36%), monazite (0.27%) and derived from source rocks that have wide range of composition rutile (0.18%). The rest of heavy mineral content is made up of from the high-grade metamorphic sequences of Qabri Bahar Series amphiboles, garnets and sphene. to Gabbro-Syenite belt and Younger Granites. Paleo-beaches: Since the entire coast bordering the southern Gulf of Aden is prograding, remnants of a number of raised paleo- 5.5. Concentration of heavy minerals and its economic importance beaches of Pleistocene to Recent age were recorded in Somaliland coastline (Gregory, 1925; Hunt, 1960; MacFadyen, 1933). The most Heavy mineral sand deposits in Somaliland coastline have prominent raised paleo-beach, which lies 8 m above the present relatively high ilmenite and magnetite concentrations, with day sea-level, is recorded all the way along the Somaliland coastline medium-low grade rutile, and zircon concentrations. But they are from eastwards to Las Khoreh (Mackay et al., 1954). In the voluminous and cover areas that potentially comprise hundreds of study area, we observed a well-marked raised paleo-beach be- square kilometers. Therefore, these deposits could be of interest tween 8 and 10 m above the present sea-level, and located about due to their large volume and easy to mine operations because of 1e2 km inland from the current shoreline. The paleo-beach was their unconsolidated nature and the fact that the area is sparsely difficult to locate west of Berbera, but it is best developed and populated with little or no vegetation cover. In particular, this study better defined at east of Berbera (Fig. 2). The paleo-beach consists of indicates that the most important heavy mineral deposits are found several strandlines that appear as prominent ridges sub-parallel to at the mouths of Waaheen and Biyo Gure ephemeral rivers. How- the coast. Such ridges run for at least 10 km. These paleo-beaches ever, the available data on the heavy mineral deposits is currently are rich in heavy minerals and are as wide as 80 m. On surface, inadequate for definitive evaluation of either the quantitative or they are partially cemented (either calcareous or siliceous) into a qualitative factors of the resource. Nevertheless, it is anticipated hard crust and below 1e2 m become unconsolidated again that deposits of this type will become more important in the future (Fig. 3c.). and demonstrate potential for commercial mining in these two Samples collected from the paleo-beach (E23eE26) have similar areas. concentration of heavy minerals observed from backshore samples, There are a number of positive indications for economic con- which indicate a similar source. In particular, samples E23, E25 and centration of heavy mineral sand deposits in Somaliland coast, in E26 contain high concentration of heavy minerals that consist of particular east of Berbera. These include a good backshore devel- predominantly magnetite and titanium minerals (rutile and opment, paleo-beaches and mineral concentration in back-beach ilmenite) with minor concentration of zircon, garnet, monazite, dunes. These factors indicate a very sizeable block of ground, hornblende, sphene, apatite and epidote. For example, samples E23 considerably larger than anything observed in other deposits in and E25 contain 23.3 wt% and 54.9 wt% of Fe2O3 respectively and eastern Africa. Volumes should easily exceed any minimum for 8.69 wt% and 16.5 wt% of TiO2 respectively (Table 1b). economic development and the geographical setting should allow Sand dunes: Yellow to black sand dunes that oriented to for a small scale or pilot operation to proceed in higher grade areas. northwest-southeast to east-west are found along the coast (Fig. 2). For example, the Kwale heavy mineral sand deposit in southwest of These dunes are best developed in the coastal region northeast of Mombasa, Kenya has 146 Mt of measured resources with 2.59% of Berbera (Fig. 2). The samples of sand dunes (E26, E28 and E29) ilmenite, 0.65% rutile, 0.29% zircon (Tyler and Minnitt, 2004; Van contain high concentration of quartz. The quartz is derived mostly Gosen et al., 2014). The Kwale deposit has low grades of heavy from the Cretaceous (Jesoma Sandstone), Oligocene-Miocene minerals and is much smaller deposit than the heavy mineral de- (Daban Group) and crystalline basement rocks that outcrop south posits that this study observed in Somaliland coastline. of the sand dunes. The concentration of heavy minerals is less in Furthermore, the raised paleo-beach in the east of Berbera is dunes than in backshore sediments. However, sample E29 (east of promising as several of the east African deposits (e.g. Fort Dauphin Siyara) comprises high concentration of titanium and iron bearing mine in Madagascar and Kwale Deposit in Kenya) show their best minerals. mineral development in these interior ancient beach sands (Tyler The heavy minerals observed in the east of Berbera are derived and Minnitt, 2004; Van Gosen et al., 2014). For example, the from erosion and marine concentration of alluvial sands from the entire area between the present shore and the raised paleo-beach high-grade metamorphic sequences of Qabri Bahar Series and should be viewed as highly prospective. Effectively this would intrusive bodies that outcrops in Hudiso and Tulo Dibijo areas create a large block of some 50 km2 of potentially mineralized (Fig. 1). Abdalla et al. (1993) also suggested that the black beach ground and a prime target for proving a heavy mineral sand sand deposits of Batalaleh is derived from marine networking of resource. For the purpose of this study, only surface grab samples alluvial sediments drained from the nearby Hudiso area, in which were taken, however there exists significant potential for increased the crystalline basement outcrops. The crystalline basement valuable heavy mineral accumulations at depth, which should be exposed in these catchment areas comprises of psammitic granitic the focus of future study. and dioritic gneisses and schists of Qabri Bahar Series (Hunt, 1960; Another major advantage for future development of this Sassi et al., 1993; Warden and Daniels, 1984). These are intruded by resource is that the deposits are located in very close proximity to gabbro (the Gabbro-Syenite belt) and Younger Granites (including Berbera, the only major deep-water port in Somaliland. In addition, Daimoleh granite) (Hunt, 1960; Sassi et al., 1993). In Hudiso area, road access to the deposits is adequate. Therefore, the magnetite the basement consists of a wide range of mainly meta-psammite may also be a valuable component given potentially low land rocks that range from felspathic gneisses through quartz-biotite transport costs to port. schists and gneisses to banded migmatite gneisses. In this area The heavy mineral deposits which have been investigated along magnetite and to a lesser extend sphene and apatite become the coast of Somaliland are presently recognized as being a po- abundant (Hunt, 1960). Therefore, the composition of the catch- tential commercial resource. Nevertheless, further detailed inves- ment area indicates that these rocks are the predominant source of tigation of identified heavy mineral deposits, including drilling and 74 M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 laboratory analyses are required, with the aim of locating high References grade areas to conduct further feasibility studies for mine devel- opment, and determine reserves of ilmenite, rutile, zircon, Abbate, E., Hussein, A.S., Bruni, P., Sagri, M., 1993a. Pre- and syn-rift sedimentation fi in a tertiary basin along the Gulf of aden (Daban basin, northern ). In: magnetite and other heavy minerals over identi ed deposits. Abbate, E., Sagri, M., Sassi, F.P. (Eds.), Geology and mineral resources of Somalia and surrounding regions. Relazioni e Monografie 113A/1993 Insituto Agro- nomico Oltremare, Firenze, pp. 211e240. Abbate, E., M., Sagri, Sassi, F.P., 1993b. A geological map of Somalia 1:1,500,000. In: 6. Conclusions Abbate, E., Sagri, M., Sassi, F.P. (Eds.), 1st International Meeting on the Geology of Somalia and Surrounding Regions (GEOSOM 87), , Somalia. Sixty-one samples were collected from backshores, raised Abdalla, J.A., Cortiana, G., Frizzo, P., Jobstraibizer, P.G., 1993. Black heavy-mineral paleo-beaches and sand dunes along Somaliland coastline from Eil beach sands from Batalaleh (Berbera, N. Somalia). In: Abbate, E., Sagri, M., Sassi, F.P. (Eds.), Geology and mineral resources of Somalia and surrounding Sheikh to Ras Khatib to study their heavy mineral assemblage. The regions. Relazioni e Monografie 113A/1993 Insituto Agronomico Oltremare, XRF, XRD and SEM-EDS analyses show that Somaliland coast has Firenze, pp. 541e550. high potential for heavy mineral deposits. In summary, this study Acharya, B.C., Panigrahy, P.K., Nayak, B.B., Sahoo, R.K., 1998. Heavy mineral placer deposits of ekakula beach, gahiramatha coast, Orissa, India. Resour. Geol. 48, identified that: 125e136. Al-Husseini, M.I., 2000. Origin of the Arabian plate structures; amar collision and e Medium and high grade detrital ilmenite and magnetite, with najd rift. GeoArabia 5, 527 542. Ali, M.A., Krishnan, S., Banerjee, D.C., 2001. Beach and inland heavy mineral sand less abundant rutile, zircon, and monazite, occur at backshores, investigations and deposits in Indiadan overview. Explor. Res. Atom Miner. 13, raised paleo-beaches and in dunes. These combined aspects 1e21. indicate a good possibility of obtaining a viable deposit within Ali, M.Y., 2015. Petroleum geology and hydrocarbon potential of the Guban basin, Northern Somaliland. J. Petrol. Geol. 38, 433e457. the areas investigated. Ali, M.Y., Watts, A.B., 2016. Tectonic evolution of sedimentary basins of northern Backshore deposits of the Waaheen and Biyo Gure mouths and Somalia. Basin Res. 28, 340e364. raised paleo-beach in the east of Berbera have good amount of Ali, M.Y., Watts, A.B., 2013. Subsidence history, crustal structure, and evolution of the Somaliland-Yemen conjugate margin. J. Geophys. Res. Solid Earth 118. titaniferous heavy minerals with most samples greater than https://doi.org/10.1002/jgrb.50113. 50 wt%. These minerals occur in the form of ilmenite, rutile and Armstrong-Altrin, J.S., 2009. Provenance of sands from cazones, acapulco, and bahía titaniferous magnetite, with minor zircon concentrations kino beaches, Mexico. Rev. Mex. Ciencias Geol. 26, 764e782. The major element concentrations indicated that the samples Armstrong-Altrin, J.S., Lee, Y.I., Kasper-Zubillaga, J.J., Carranza-Edwards, A., Garcia, D., Eby, G.N., Balaram, V., Cruz-Ortiz, N.L., 2012. Geochemistry of beach from the east and west of Berbera were derived from rocks that sands along the western Gulf of Mexico, Mexico: implication for provenance. cover all four provenances (mafic, intermediate, felsic and Chemie der Erde - Geochemistry 72, 345e362. quartzose). Armstrong-Altrin, J.S., Lee, Y.I., Kasper-Zubillaga, J.J., Trejo-Ramírez, E., 2017. Mineralogy and geochemistry of sands along the Manzanillo and El Carrizal The variations in observed mineral assemblages in the east and beach areas, southern Mexico: implications for palaeoweathering, provenance west of Berbera areas are probably due to the different source and tectonic setting. Geol. J. 52, 559e582. rocks in the catchment areas of these two areas. The east of Armstrong-Altrin, J.S., Machain-Castillo, M.L., Rosales-Hoz, L., Carranza-Edwards, A., Sanchez-Cabeza, J.-A., Ruíz-Fernandez, A.C., 2015a. Provenance and deposi- Berbera is dominated by moderate concentration of plagioclase, tional history of continental slope sediments in the Southwestern Gulf of K-feldspar, magnetite, hematite and titanium bearing minerals. Mexico unraveled by geochemical analysis. Continent. Shelf Res. 95, 15e26. These are derived from Qabri Bahar complex and Gabbro- Armstrong-Altrin, J.S., Nagarajan, R., Balaram, V., Natalhy-Pineda, O., 2015b. Petrography and geochemistry of sands from the Chachalacas and Veracruz Synenite belt as well as granitic intrusions that outcrop in beach areas, western Gulf of Mexico, Mexico: constraints on provenance and Hudiso, Tulo Dibijo and surrounding areas. Whereas in the west tectonic setting. J. S. Am. Earth Sci. 64, 199e216. of Berbera, the dominant minerals are quartz, K-feldspar and Armstrong-Altrin, J.S., Nagarajan, R., Lee, Y.I., Kasper-Zubillaga, J.J., Cordoba- Saldana, L.P., 2014. Geochemistry of sands along the San Nicolas and San Carlos plagioclase with variable proportions of ilmenite, rutile, mica, beaches, Gulf of California, Mexico: implications for provenance and tectonic amphibole and pyroxene. The primary sources of heavy min- setting. Turk. J. Earth Sci. 23, 533e558. erals are Qabri Bahar and Mora complexes in Laferug and Becker, J.J., Sandwell, D.T., Smith, W.H.F., Braud, J., Binder, B., Depner, J., Fabre, D., Hagabo areas, which comprise of high-grade metamorphic Factor, J., Ingalls, S., Kim, S.-H., Ladner, R., Marks, K., Nelson, S., Pharaoh, A., Trimmer, R., Rosenberg, J.V., Wallace, G., Weatherall, P., 2009. Global bathym- rocks of Mora and Qabri Bahar complexes as well as Miocene etry and elevation data at 30 arc seconds resolution: SRTM30_PLUS. Mar. volcanics. Geodesy 32, 355e371 do:310.1080/01490410903297766. Development prospects for the mineral sands in the east of Behera, P., 2003. Heavy minerals in beach sands of Gopalpur and Paradeep along Orissa coastline, east coast of India. Indian J. Mar. Sci. 32, 172e174. Berbera are better than those in the west of Berbera. The east of Carpenter, R.H., Carpenter, S.F., 1991. Heavy mineral deposits in the upper coastal Berbera has wider beaches, better heavy mineral sands accu- plain of North Carolina and Virginia. Econ. Geol. 86, 1657e1671. mulations in the upper horizons and dune areas carry heavier Dal Piaz, G.J., 1987. Short Notes of the Geology of Northern Somalia: Excursion Guidebook, First International Meetong on the Geology of Somalia and Sur- mineral sands than those in the west of Berbera. Furthermore, a rounding Regions (GEOSOM87). Somali National University & Italian Ministry of series of paleo-beaches 1e2 km behind the shoreline with Foreign Affairs, Mogadishu, pp. 1e97. higher heavy minerals concentrations are observed. In addition, Daniels, J.L., Skiba, W.J., Sutton, J., 1965. The deformation of some banded gabbros in the northern Somalia fold-belt. Q. J. Geol. Soc. 121, 111e137. it is closer to the Berbera port and it has a better road access than Dillenburg, S.R., Tomazelli, L.J., Barboza, E.G., 2004. Barrier evolution and placer west of Berbera. formation at Bujuru southern Brazil. Mar. Geol. 203, 43e56. Farquharson, R.A., 1926. Geology and mineral resources of . Min. Mag. XXXIV 265e276, 329e240. Force, E.R., Butler, R.F., Reynolds, R.L., Houston, R.S., 2001. Magnetic ilmenite- Acknowledgements hematite detritus in mesozoic-tertiary placer and sandstone-hosted uranium deposits of the rocky mountains. Econ. Geol. 96, 1445e1453. We wish to thank the Somaliland Ministry of Minerals and En- Girty, G.H., Ridge, D.L., Knaack, C., Johnson, D., Al-Riyami, R.K., 1996. Provenance and depositional setting of Paleozoic chert and argillite, Sierra Nevada, California. ergy for supporting this study. Special thanks to Mohammed J. Sediment. Res. 66, 107e118. Ibrahim Abdi, Awil Awl and elders of Bulhar village for assisting the Greenwood, J.E.G.W., 1960. Report on Geological Investigations in Somaliland Pro- fieldwork conducted in the western Berbera. We are grateful to tectorate with Particular Reference to the North-eastern Area. . Gregory, J.W., 1925. The Geology of Somaliland and its Relations to the Great Rift Suleiman Mohamed Ali, Abdillahi Ismail Mataan and Omar Abokor Valley. Monograph Geology Department Hunterian Museum Glasgow Jama (former deputy manager of Berbera port) for assisting our University. fieldwork in the eastern Berbera area. We thank John S. Armstrong- Gujar, A.R., Ambre, N.V., Mislankar, P.G., Iyer, S.D., 2010. Ilmenite, magnetite and chromite beach placers from south Maharashtra, central west coast of India. Altrin for his helpful comments on an earlier version of the paper. M.Y. Ali et al. / Journal of African Earth Sciences 140 (2018) 60e75 75

Resour. Geol. 60, 71e86. heavy mineral deposits in southeastern Georgia. Econ. Geol. 84, 425e433. Hou, B., Keeling, J., Reid, A., Fairclough, M., Warland, I., Belousova, E., Frakes, L., Ramos-Vazquez, M.A., Armstrong-Altrin, J.S., Rosales-Hoz, L., Machain-Castillo, M.L., Hocking, R., 2011. Heavy mineral sands in the eucla basin, southern Australia: Carranza-Edwards, A., 2017. Geochemistry of deep-sea sediments in two cores deposition and province-scale prospectivity. Econ. Geol. 106, 687e712. retrieved at the mouth of the Coatzacoalcos River delta, western Gulf of Mexico, Hunt, J.A., 1960. Report on the Geology of the Berbera-sheikh Area, Berbera and Mexico. Arab. J. Geosci. 10, 148. Burao District, Quarter Degree Sheets No. 24 and 36. Rao, C.B., 1957. Beach erosion and concentration of heavy mineral sands. Hunt, J.A., Mason, J.E., 1957. Berbera, Geological Survey Sheet 24, 1:125,000 J. Sediment. Petrol. 27, 143e147. Somaliland Protectorate. Directorate of Colonial Surveys for Geological Survey, Roser, B.P., Korsch, R.J., 1988. Provenance signatures of sandstone-mudstone suites London, UK. Somaliland Protectorate. D.C.S. 1076. determined using discriminant function analysis of major-element data. Chem. Husseini, M.I., 1989. Tectonic and deposition model of late precambrian-cambrian Geol. 67, 119e139. Arabian and adjoining plates. Am. Assoc. Petrol. Geol. Bull. 73, 1117e1131. Roy, P.S., 1999. Heavy mineral beach placers in southeastern Australia; their nature IOC, IHO, BODC, 2003. Centenary Edition of the GEBCO Digital Atlas, Published on and genesis. Econ. Geol. 94, 567e588. CDROM on Behalf of the Intergovernmental Oceanographic Commission and Roy, P.S., Whitehouse, J., 2003. Changing Pliocene sea levels and the formation of the International Hydrographic Organization as Part of the General Bathymetric heavy minerals beach placers in the murray basin, southeastern Australia. Econ. Chart of the Oceans. British Oceanographic Data Centre, Liverpool. Geol. 98, 975e983. Kroner,€ A., Sassi, F.P., 1996. Evolution of the northern Somali basement: new con- Roy, P.S., Whitehouse, J., Cowell, P.J., Oakes, G., 2000. Mineral sands occurrences in straints from zircon ages. J. Afr. Earth Sci. 22, 1e15. the murray basin, southeastern Australia. Econ. Geol. 95, 1107e1128. Leonardos, O.H., 1974. Origin and provenance of fossil and recent monazite deposits Sassi, F.P., Visona, D., Ferrara, G., Gatto, G.O., Ibrahim, H.A., Saida, A.A., Tonarini, S., in Brazil. Econ. Geol. 69, 1126e1128. 1993. The crystalline basement of Northern Somalia: lithostratigraphy and Loosveld, R.J.H., Bell, A., Terken, J.J.M., 1996. The tectonic evolution of interior Oman. sequence of events. In: Abbate, E., Sagri, M., Sassi, F.P. (Eds.), Geology and GeoArabia (Manama) 1, 28e51. Mineral Resources of Somalia and Surrounding Regions. Relazioni e Monografie MacFadyen, W.A., 1933. Geology of Somaliland the Government of the Somaliland 113A/1993 Insituto Agronomico Oltremare, Firenze, pp. 3e40. Protectorate, p. 25. Tapia-Fernandez, H.J., Armstrong-Altrin, J.S., Selvaraj, K., 2017. Geochemistry and Mackay, C., Williams, D., Gilbert, D.L.F., Widmer, H., 1954. A Geological Reconnais- UePb geochronology of detrital zircons in the Brujas beach sands, Campeche, sance of the Sedimentary Deposits of the Protectorate of British Somaliland. Southwestern Gulf of Mexico, Mexico. J. S. Am. Earth Sci. 76, 346e361. Crown Agents, London, pp. 1e41. Tyler, R.M., Minnitt, R.C.A., 2004. A review of sub-Saharan heavy mineral sand Mason, J.E., 1962. Reports on the Geology of the Area North of Hargeisa and Laferug, deposits: implications for new projects in southern Africa. J. S. Afr. Inst. Min. Hargeisa and , pp. 1e34. Hargeisa. Metall. March 89e99. Mason, J.E., Warden, A.J., 1971a. Laferug, Geological Survey Sheet 24, 1:125,000 Van Gosen, B.S., Fey, D.L., Shah, A.K., Verplanck, P.L., Hoefen, T.M., 2014. Deposit Somali Democratic Republic. Directorate of Overseas Surveys for the Somalia model for heavy-mineral sands in coastal environments. U.S. Geol. Surv. 1e51. Democratic Republic, London, UK. Warden, A.J., Daniels, J.L., 1982. Evolution of the precambrian of northern Somalia. Mason, J.E., Warden, A.J., 1971b. Saba Wanak & Bulhar, Geological Survey Sheet 10 & Precambrian Res. 16, A42eA43. 22, 1:125,000 Somali Democratic Republic. Directorate of Overseas Surveys for Warden, A.J., Daniels, J.L., 1984. Evolution of the Precambrian of Northern Somalia. the Somalia Democratic Republic, London, UK. Bull. Fac. Earth Sci. King Abdulaziz Univ. Jeddah 6, 145e164. Pirkle, F.L., Pirkle, E.C., Pirkle, W.A., Dicks, S.E., Jones, D.S., Mallard, E.A., 1989. Altama