Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Genesis of the Assif El Mal Zn–Pb (Cu, Ag) vein deposit. An extension-related Mesozoic vein system in the High Atlas of Morocco. Structural, mineralogical, and geochemical evidence

Abstract

The Assif El Mal Zn–Pb (Cu–Ag) vein system, located in the northern flank of the High Atlas of Marrakech (Morocco), is hosted in a Cambro-Ordovician volcaniclastic and metasedimentary sequence composed of graywacke, siltstone, pelite, and shale interlayered with minor tuff and mudstone. Intrusion of synorogenic to postorogenic Late Hercynian peraluminous granitoids has contact metamorphosed the host rocks giving rise to a metamorphic assemblage of quartz, plagioclase, biotite, muscovite, chlorite, amphibole, chloritoid, and garnet. The Assif El Mal Zn–Pb (Cu–Ag) mineralization forms subvertical veins with ribbon, fault breccia, cockade, comb, and crack and seal textures. Two-phase liquid–vapor fluid inclusions that were trapped during several stages occur in quartz and sphalerite. Primary inclusion fluids exhibit T h mean values ranging from 104°C to 198°C. Final ice-melting temperatures range from −8.1°C to −12.8°C, corresponding to salinities of ∼15 wt.% NaCl equiv. Halogen data suggest that the salinity of the ore fluids was largely due to evaporation of seawater. Late secondary fluid inclusions have either Ca-rich, saline (26 wt.% NaCl equiv.), or very dilute (3.5 wt.% NaCl equiv.) compositions and homogenization temperatures ranging from 75°C to 150°C. The δ18O and δD fluid values suggest an isotopically heterogeneous fluid source involving mixing between connate seawater and black-shale-derived organic waters. Low δ13CVPDB values ranging from −7.5‰ to −7.7‰ indicate a homogeneous carbon source, possibly organic matter disseminated in black shale hosting the Zn–Pb (Cu–Ag) veins. The calculated δ34SH2S values for reduced sulfur (22.5‰ to 24.3‰) are most likely from reduction of SO4 2− in trapped seawater sulfate or evaporite in the host rocks. Reduction of sulfate probably occurred through thermochemical sulfate reduction in which organic matter was oxidized to produce CO2 which ultimately led to precipitation of saddle dolomite with isotopically light carbon. Lead isotope compositions are consistent with fluid–rock interaction that leached metals from the immediate Cambro-Ordovician volcaniclastic and metasedimentary sequence or from the underlying Paleo-Neoproterozoic crustal basement. Geological constraints suggest that the vein system of Assif El Mal formed during the Jurassic opening of the central Atlantic Ocean.

This is a preview of subscription content, log in to check access.

Fig. 1
Fig. 2
Fig. 3
Fig. 4
Fig. 5
Fig. 6
Fig. 7
Fig. 8
Fig. 9
Fig. 10

References

  1. Banks DA, Yardley BWD (1992) Crush-leach analysis of fluid inclusions in small natural and synthetic samples. Geochim Cosmochim Acta 56:245–248

  2. Beraâouz EH, Platevoet B, Bonin B (1994) Le magmatisme mésozoïque du Haut Atlas (Maroc) et l’ouverture de l’Atlantique central. C R Acad Sci Paris 318(série II):1079–1085

  3. Boni M, Muchez P, Schneider J (2002) Permo-Mesozoic multiple fluid flow and mineralization in Sardinia and the post-Variscan evolution of Western Europe. In: Blundell DJ, Neubauer F, van Quadt A (eds) The timing and location of major ore deposits in an evolving orogen. Geological Society of London, London, pp 199–212, Spec Publ 204

  4. Bouabdellah M (1988) Etude pétrographique et métallogénique du district polymétallique à Pb-Zn-Cu-Ba-Fe-Sn d’Assif El Mal-Bouzouga, Haut Atlas de Marrakech, Maroc. Unpubl Ph.D. Thesis, University of Marrakech, 321 pp

  5. Bouabdellah M, Sagon JP (1989) Altérations hydrothermales des granitoïdes de Bouzouga. Minéralisations associées. In: Colloque de Géologie Franco-Marocain. Centre International pour la Formation et les Échanges Géologiques. Strasbourg: 41

  6. Bouabdellah M, Leach DL, Johnson C (2003) Geochemical characteristics of the Assif El Mal Zn-Pb (Cu, Ag) vein system: High Atlas Mountains, Morocco. In: Eliopoulos et al. (eds) Mineral exploration and sustainable development, 7th Biennial SGA-SEG Meeting, Athens, Greece, pp 949–952

  7. Canals A, Cardellach E (1992) Strontium and sulphur isotope geochemistry of low-temperature Ba–F veins of the Catalonian Coastal Ranges (NE Spain): a fluid mixing model and age constraints. Chem Geol 104:269–280

  8. Castorina F, Masi U (2000) Sr-isotopic composition of siderite for assessing the origin of mineralizing fluids: the case study from the Jebel Awam deposit (central Morocco). Ore Geol Rev 17:83–89

  9. Chan LH, Starinsky A, Katz A (2002) The behavior of lithium and its isotopes in oilfield brines: evidence from the Heletz-Kokhav field, Israel. Geochim Cosmochim Acta 66:615–623

  10. Chevremont P (1975) Les roches éruptives basiques des boutonnières de Tassent-Tasraft et leurs indices métallifères dans leur cadre géologique (Haut Atlas central, Maroc). These Doct. Ing., Univ. Claude-Bernard, Lyon I, 209, 148 pp

  11. Chi G, Savard MM (1997) Sources of basinal and Mississippi Valley-type mineralising brines: Mixing of evaporated seawater and halite dissolution brine. Chem Geol 143:121–125

  12. Claypool GE, Holser WT, Kaplan IR, Sakai H, Zak I (1980) The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation. Chem Geol 28:199–260

  13. Clayton RN, Mayeda TK (1963) The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis. Geochim Cosmochim Acta 27:43–52

  14. Clayton RN, Friedman T, Graf DL, Mayeda TK, Meents WF, Shimp NF (1966) The origin of saline formation waters: 1. isotopic composition. J Geophys Res 71:3869–3882

  15. Davis DW, Lowenstein TK, Spencer RJ (1990) Melting behaviour of fluid inclusions in laboratory grown halite crystals in the systems NaCl-H2O, NaCl-KCl-H2O, NaCl-MgCl2-H2O and NaCl-CaCl2-H2O. Geochim Cosmochim Acta 54:591–601

  16. Dubois M, Marignac C (1997) The H2O-NaCl-MgCl2 ternary phase diagram with special application to fluid inclusion studies. Econ Geol 92:114–119

  17. Elders W, Sass JH (1988) The Salton Sea scientific drilling project. J Geophys Res 93:12953–12968

  18. Fontes JC, Matray JM (1993) Geochemistry and origin of the formation brines from the Paris Basin, France: 1. Brines associated with Triassic salts. Chem Geol 109:149–175

  19. Galindo C, Tornos F, Darbyshire DPF, Casquet C (1994) The age and origin of the barite–fluorite (Pb-Zn) veins of the Sierra del Guadarrama (Spanish central system): a radiogenic (Nd, Sr) and stable isotope study. Chem Geol 112:351–364

  20. Giesemann A, Jäger HJ, Norman AL, Krouse HR, Brand WA (1994) On-line sulfur-isotope determination using an elemental analyzer coupled to a mass spectrometer. Anal Chem 66:2816–2819

  21. Giggenbach WF (1992) Isotopic shifts in waters from geothermal and volcanic systems along convergent plate boundaries and their origin. Earth Planet Sci Lett 113:495–510

  22. Hailwood EA, Michell JG (1971) Paleomagnetic and radiometric dating results from Jurassic intrusion in south Morocco. Geophys JR Astr Soc 24:351–364

  23. Heijlen W, Muchez P, Banks D, Schneider J, Kucha H, Keppens E (2003) Carbonate-hosted Zn–Pb deposits in Upper Silesia, Poland: origin and evolution of mineralizing fluids and constraints on genetic models. Econ Geol 98:911–932

  24. Jébrak M, Marcoux E, Nasloubi M, Zaharaoui M (1998) From sandstone- to carbonate-hosted stratabound deposits: an isotope study of galena in the Upper-Moulouya District (Morocco). Miner Depos 33:406–415

  25. Johnson CA, Cardellach E, Tritlla J, Hanan BB (1996) Cierco Pb-Zn-Ag vein deposits: isotopic and fluid inclusion evidence for formation during the Mesozoic extension in the Pyrenees of Spain. Econ Geol 91:497–506

  26. Kesler SE, Martini AM, Appold MS, Walter LM, Huston TJ, Kyle JR (1995) Na–Cl–Br systematics of mineralizing brines in Mississippi Valley-type deposits. Geology 23:641–644

  27. Kesler SE, Martini AM, Appold MS, Walter LM, Huston TJ, Furman FC (1996) Na–Cl–Br systematics of fluid inclusions from Mississippi Valley-type deposits, Appalachian basin: constraints on solute origin and migration paths. Geochim Cosmochim Acta 60:225–233

  28. Klitgord KD, Schouten H (1986) Plate kinematics of the central Atlantic. In: Vog PR, Tucholke BE (eds) The geology of North America. vol. M. The Western North Atlantic Region, Geological Society of America, Boulder, pp 351–377

  29. Klitgord KD, Hutchinson DR, Schouten H (1988) US continental margin: structural and tectonic framework. In: Sheridan RE, Grow JA (eds) The Atlantic Continental margin, US. Geological Society of America, Boulder, pp 19–55

  30. Krouse HR, Viau CA, Eliuk LS, Veda A, Halas S (1988) Chemical and isotopic evidence of thermochemical sulphate reduction by light hydrocarbon gases in deep carbonate reservoirs. Nature 333:415–419

  31. Laville E, Zayane R, Honnorez J, Piqué A (1994) Le métamorphisme jurassique du Haut Atlas central (Maroc); épisodes synschisteux et hydrothermaux. C R Acad Sci Paris 318(série II):1349–1356

  32. Li YB, Liu JM (2006) Calculation of sulfur isotope fractionation in sulfides. Geochim Cosmochim Acta 70:1789–1795

  33. Machel HG, Krouse HR, Sassen R (1995) Products and distinguishing criteria of bacterial and thermochemical sulfate reduction. Appl Geochem 10:373–389

  34. Manspeizer W, Cousminer HLL (1988) Late Triassic–Early Jurassic synrift basins of the U.S. Atlantic margin. In: Sheridan RE, Grow JA (eds) The Atlantic Continental Margin, US. Geological Society of America, Boulder, pp 197–216

  35. McCrea JM (1950) On the isotopic chemistry of carbonates and paleo-temperature scale. J Chem Phys 18:849–857

  36. Morad S, Ben Ismail HN, De Ros LF, Al-Aasm IS, Serrhini N-E (1994) Diagenesis and formation water chemistry of Triassic reservoir sandstones from southern Tunisia. Sedimentology 41:1253–1272

  37. Moret L (1930) Notice explicative de la carte géologique provisoire de l’Atlas de Marrakech. Notes et Mem. Serv Min et Carte Géol Maroc 18:262

  38. Mrini Z (1985) Age et origine des granitoïdes hercyniens du Maroc. Apport de la géochronologie de la géochimie isotopique (Sr, Nd, Pb). Unpub. Ph.D. Thesis. University of Clermont-Ferrand, p 156

  39. Muchez P, Stassen P (2006) Multiple origin of the Kniest feeder zone of the stratiform Zn-Pb-Cu ore deposit of Rammelsberg, Germany. Miner Depos 41:46–51

  40. Oakes CS, Bodnar RJ, Simonson JM (1990) The system NaCl-CaCl2-H2O: I. The ice liquidus at 1 atm total pressure. Geochim Cosmochim Acta 54:603–610

  41. Ohmoto H, Rye RO (1979) Isotopes of sulfur and carbon. In: Barnes HL (ed) Geochemistry of hydrothermal ore deposits, 2nd edn. Wiley, New York, pp 509–567

  42. Orr WL (1977) Geologic and geochemical controls on the distribution of hydrogen sulphide in natural gas. In: Campos R, Goni J (eds) Advances in organic geochemistry 1975. Enadisma, Madrid, pp 571–597

  43. Permingeat F (1954) Sur la mine d’Assif El Mal. SEGM, unpublished Report no. 2877/BD, 396, 7p

  44. Piqué A, Laville E (1993) Les séries triasiques du Maroc, marqueurs du rifting atlantique. C Acad Sci Paris 317(II):1215–1220

  45. Prost A, Badra L, El Hasnaoui H (1989) Superposition de trois déformations ductiles hercyniennes dans le Haut Atlas (région d’Azegour-Erdouz, Maroc). C R Acad Sci Paris 309(II):627–632

  46. Ricou LM (1994) Tethys reconstructed: plates, continental fragments and their boundaries since 260 Ma from Central America to South-eastern Asia. Geodinamica Acta 74:169–218

  47. Roedder E (1984) Fluid inclusions. Mineral Soc Amer, Rev Mineral 12:644

  48. Sheppard SMF (1986) Characterization and isotopic variations in natural waters. In: Valley JW, Taylor HP Jr, O’Neil JR (eds) Stable isotopes in high temperature geological processes. Mineral Soc Am Rev Mineral 16:165–184

  49. Sheppard SMF (1994) Stable isotope and fluid inclusion evidence for the origin and evolution of hercynian mineralizing fluids. In: Seltmann R Kämpf U, Möller P (eds) Metallogeny of collisional orogens. Czech Geological Survey, Prague, pp 49–60

  50. Sibson RH (1996) Structural permeability of fluid-driven fault–fracture meshes. J Struct Geol 18:1031–1042

  51. Smith RL, Pozzobon JC (1979) The Imiter gabbroic complex, High Atlas Mountains, Morocco. J Geol 87:317–324

  52. Taylor HP Jr (1974) The application of oxygen and hydrogen isotope studies to problems of hydrothermal alteration and ore deposition. Econ Geol 69:843–883

  53. Thorpe RI (1999) The Pb isotope linear array for volcanogenic massive sulphide deposits of the Abitibi and Wawa subprovinces, Canada Shield. In: Hannington MD, Barrie CT (eds) The giant Kidd Creek volcanogenic massive sulphide deposit, western Abitibi subprovince, Canada. Econ Geol Monograph 10:555–576

  54. Vallance J, Cathelineau M, Marignac C, Boiron MC, Fourcade S, Martineau F (2001) Microfracturing and fluid mixing in granites: W-Sn ore deposition at Vaulry (NW French Massif Central). Tectonophysics 336:43–62

  55. Van Houten FB (1977) Triassic–Liassic deposits of Morocco and Eastern North America: comparison. Am Assoc Petrol Geol Bull 61:79–99

  56. Watanabe Y (2002) 40Ar/39Ar geochronologic constraints on the timing of massive sulfide and vein-type Pb–Zn mineralization in the Western Meseta of Morocco. Econ Geol 97:145–158

  57. Wilkinson JJ, Jenkin GRT, Fallick AE, Foster RP (1995) Oxygen and hydrogen isotopic evolution of Variscan crustal fluids, south Cornwall, UK. Chem Geol 123:239–254

  58. Zartman RE, Doe BR (1981) Plumbotectonics, the model. Tectonophysics 75:135–162

  59. Zayane R (1992) La série plutonique du Haut Atlas central marocain (Région d’Imilchil): pétrographie et géochimie; aspects métamorphique et structuraux de sa mise en place. Unpubl Ph.D. Thesis, University of Bretagne occidentale (France). 189 pp

  60. Zheng YF (1993) Calculation of oxygen isotope fractionation in anhydrous silicate minerals. Geochim Cosmochim Acta 57:1079–1091

  61. Zheng YF (1999) Oxygen isotope fractionation in carbonate and sulfate minerals. Geochem J 33:109–126

Download references

Acknowledgements

We are grateful to Cindy Kestler, Wayne Premo, and Craig Johnson of the USGS in Denver for stable and radiogenic isotope analyses. D. Banks (School of Earth Sciences of the University of Leeds) and Z. Sharp (Department of Earth and Planetary Sciences, University of New Mexico, USA) are thanked for prompt and reliable crush leach analyses and δD data of the samples presented in this paper. We are also indebted to D. Sangster for his helpful comments on earlier versions of the manuscript. We thank the two Mineralium Deposita reviewers D. Banks and C. Marignac for constructive critical reviews and input that substantially improved the manuscript. C. Marignac provided invaluable assistance and insightful comments on an earlier version of this manuscript. Special thanks to B. Lehmann, the Chief Editor of Mineralium Deposita, for his patience, thorough reviews, and helpful comments.

Funding for this research was provided through grants from the Programme d’Appui à la Recherche Scientifique of Morocco (PROTARS II/ P23/33), the Moroccan–Spanish Scientific Research Program (188/04/RE), and the NATO Fellowship (EST.CLG.979371) and was supported by a Fulbright postdoctoral fellowship awarded to the first author.

Author information

Correspondence to Mohammed Bouabdellah.

Additional information

Editorial handling: B. Lehmann.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Bouabdellah, M., Beaudoin, G., Leach, D.L. et al. Genesis of the Assif El Mal Zn–Pb (Cu, Ag) vein deposit. An extension-related Mesozoic vein system in the High Atlas of Morocco. Structural, mineralogical, and geochemical evidence. Miner Deposita 44, 689 (2009). https://doi.org/10.1007/s00126-009-0232-8

Download citation

Keywords

  • Zn–Pb vein deposits
  • Stable isotopes
  • Fluid inclusions
  • Assif El Mal
  • Morocco