Gold and Palladium Mineralization at East of Bou Azzer Ophiolite, Morocco M. EL GHORFI 1, L. MAACHA 1, A. EN-NACIRI 1 AND T. OBERTHÜR 2 1 Managem, Twin Center, Tour A, Angle Bd Zerktouni et Massira Khadra, Casablanca, Morocco 2 BGR, Stilleweg 2, Hannover, Germany

Simplified geological Map of the Anti-Atlas mountains, which developed during Pan-African times at the northern edge of the west African craton. Important ore deposits and the different inliers with Precambrian basement exposures are shown.

Ore deposits of Co-As-Cr, copper (Cu) and gold are named and shown by stars. Geological Map of the Bou Azzer–El Graara inlier, modified after Leblanc (1981).

In the Bleïda FW area, an interlayered series of amphibolites, basic and felsic tuffs, chlorite schists, sericite schists, and cordierite schists of sedimentary and volcanic origin, and quartz diorites are exposed and intruded by the Bleïda granodiorite. Metamorphism in the area is generally of greenschist facies (actinolite, albite, epidote, and chlorite); however, local amphibolite facies of metamorphic grade (hornblende, epidote, calcic plagioclase) has been recorded. Focused zoom on the geological map of the interested area

1.The ore lodes usually occupy structurally favorable S 2 sites in folded and mylonitic bands. 2.The mineralized veins crosscut S 1 structures and are synchronous with, or later than, the second Panafrican orogenesis event (B 2 ). 3.Individual veins are generally narrow (1–2 cm, locally up to 0.5 m wide) and discontinuous along strike and down dip. Structures and Mineralization 2.8 Cm S1 (N 120°). S1 S2 (N 45°–60°).

A vertical section of the gold mineralization, showing steep north-dipping, and irregular orebodies (up to 100 m depth), and gold grades.

1.Whole rock geochemistry In the set of combined drill core and surface samples, gold shows positive correlations with Ag, Pd, and Pt only. 2.Maximum noble metal contents of the investigated ore samples are 170 ppm Au, 18 ppm Ag, 6 ppm Pd, and 177 ppb Pt. 3.Sulfur contents are generally below 0.01 wt% and are accompanied by low-base metal tenors. 4. All mineralized samples notably have distinct contents of manganese (0.2–0.3 wt% Mn). Au vs. Pd+Pt Au (g/t) Pd + Pt (g/t) Au vs. Ag Au (g/t) Ag (g/t) Whole Rock Geochemistry

1.Gold grains are often visible (millimeter-sized) in drill core samples from greater depth and on surface samples. 2.The Au-Pd mineralization is sulfides free, in some deep-seated samples (up to 100 m), a disseminated, brecciated sulfide assemblage consisting of rare chalcocite, covellite, chalcopyrite and pyrite, occurs in a ferruginous breccia matrix and in vein quartz fragments. 3 mm PGM Pépites d’Or Au 400µm 2 Cm visible Gold

hm Qtz 300µm Au-PGM 1.In polished sections, gold grains are in association with specular hematite and variable amounts of quartz, calcite, barite, epidote, and chlorite. 2.Gold is usually optically homogeneous; however, it locally contains inclusions or, is intergrown with a suite of PGM grains along its peripheries. Or hm Ba Ba PGM Au-PGM hm Qtz epi alb cal chl reflected light chl transmitted light

100µm Or S2S2S2S2 S1S1S1S1 S1S1S1S1 50µm Or calcite 5 S1S1S1S1 S2S2S2S2 Or 60µm Gold occurs as open-space filling in fragments of qtz hm-rich material and intergrown with a specular hematite, calcite, and quartz.

● Zone des Brèches (ZB) ■ Zone Intermédiaire (ZI) ▲ Zone Central (ZC) n = The composition of gold ranges from 79 to 93 wt% Au, 6 to 19 wt% Ag, and 0.5 to 6.3 wt% Pd. 2.Mercury contents are generally close to the detection limit of the method (ca. 0.1 wt% Hg) 3.in rare instances gold grains contain up to 1.33 wt% Hg. 4.Copper concentrations in the range 0.2 to 1 wt% Cu (average 0.5, max 3.13 wt% Cu). Gold composition (EMPA)

Platinum Group Minerals (PGM) Determined and Identified In Bleida FW Area by the EMP

40µmOr 6 hm 1 6 calcite 20µmOr 1 hm Mn-Fe Pd-Bi-O Or µm a.Gold is usually optically homogeneous b.It locally contains inclusions or is intergrown with a suite of PGM along its peripheries c.In decreasing order of abundance, the PGM were identified: 1- mertieite-I, 2- keithconnite, 3- palladseite, 4- merenskyite, 5- kotulskite, 6- sperrylite.  Mertieite-I / Isomertieite:  Mertieite-I / Isomertieite: [Pd 10.9 (Sb 1.97 As 1.84 )]  Sperrylite :  Sperrylite : [(Pt 0.94 Fe 0.02 ) 0.97 (As 1.85 Se 0.04 S 0.06 Te 0.06 ) 2.01 ]  Mertieite-I / Isomertieite:  Mertieite-I / Isomertieite: [Pd 10.9 (Sb 1.97 As 1.84 )]  Keithconnite :  Keithconnite : [Pd 2.92 Pt 0.01 Te 0.85 Bi 0.18 ] Palladseite : Palladseite : [(Pd 16.9 Cu 0.9 ) 17.8 (Se 12.8 Bi 0.7 ) 13.5 ]  Merenskyite :  Merenskyite : [(Pd 0.98 Pt 0.03 ) 1.01 (Te 1.93 Bi 0.04 ) 1.97 ] Kotulskite : Kotulskite : [Pd(Te 0.79 Bi 0.21 )]

Secondary PGM are regarded as products of exogenic weathering and mainly consist of ill-defined phases or mixtures of oxides containing the elements Pd, Bi, Te, Se, V, Cu, Fe, and Mn. Mertieite-I and palladseite are locally replaced by a Pd-rich oxides phase. Two distinct groups of “oxides” may be distinguished : Group 1: Dominated by Bi (>50 wt%) and about 10 wt% Pd, 15 wt% V, some Se (up to 2.4 wt%), and traces of Fe, Cu, Te, Pb, and Mn. O 2 concentrations range from 10 to 13 wt%. Group 2: Dominated by Pd (64–83 wt%) and variable amounts of Bi, Cu, Se, Te, Fe, Mn (up to 2.3 wt%), and V (up to 2.6 wt%). 50 Secondary PGM ( S-PGM ) b a S-PGM S-PGM Pals & Mert

1.The Bleïda Far West mineralization represents a new deposit type in the Anti-Atlas of Morocco. 2.At Bleïda FW, Au–Pd mineralization is hosted by dominantly brittle structures and displays open-space filling textures in hydrothermally altered amphibolites and chlorite schists 3.The mineralization is virtually sulfide-free. Free gold is associated with abundant hematite, calcite, quartz, barite, epidote, and chlorite 4.Chemical signature mainly Au-Pd-As-Sb-Se-Te are registered 5.In conjunction with the mineral association, oxidizing fluids are indicated, and Au - PGE transport and deposition took place by chloride complexes in the epithermal range, at elevated f O2 and/or low pH. 6.The origin of PGE is not constrained? Summary and Conclusions

Sud C4 (1319) BPE (1322) BPC (1318) BPW (1316) NBPC C4 (1315) C4 Est ( 1316) gradin nord (1332) Excavation of gold bearing-rocks in Bleida FW (600m long and 180m wide) Actually Gold Production in Open Pit Bleida FW

Thanks Very Much The Origin of the PGE?