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Please cite this article as: Markwitz, V., Hein, K.A.A., Miller, J.,Compilation of West African mineral deposits: spatial distribution and mineral endowment, Precambrian Research (2015), http://dx. Abstract 20The West African Craton is highly endowed in minerals, and their spatial and temporal 21 distribution varies from single to multi-phase mineralization events. They are broadly related 22 to three major tectono-metallogenic elements and formed during distinct mineral epochs: 23(1) In both Archean Shields (Kénéma-Man and Reguibat) and Paleoproterozoic domains 24 (Baoulé-Mossi, Eglab). These are characterized by giant iron ore deposits that formed 25 between ca. 2.5 -2.3 Ga, nearly all gold, porphyry copper, lead-zinc and sedimentary 26 manganese ore that developed between 2.2 -2.1 Ga, and primary diamonds that formed 27 between two intervals at ca. 2.2 -2.0 Ga and in the Mesozoic. 28(2) Across Pan-African and Variscan belts. These are distinguished by major Precambrian 29 IOCG's, copper-gold that formed at ca. 2.1 Ga and approx. 680 Ma, and Neoproterozoic 30 sedimentary iron ore and phosphate deposits. 31 (3) Within intracratonic and coastal basins. These include the development of Cenozoic 32 lateritic bauxites over Mesozoic dolerites, Tertiary / Quaternary mineral sands deposits, 33 oolitic iron ore and sedimentary phosphate deposits. 34 Geological, spatial and temporal correlations using the multi-commodity West African 35 Mineral Deposit Database highlight that gold and non-gold commodities formed in multiple 36 phases. This commenced in the Liberian Orogeny (2.9 -2.8 Ga) with the enrichment of iron 37 ore, nickel sulphides, diamonds and gold in the earth's crust. The pre-Eburnean or Tangaean-38 EoEburnean-Eburnean I Event yielded gold, and the major Eburnean Orogeny yielded gold, 39 iron ore, manganese, diamonds, magmatic nickel sulphides, copper-gold, lead-zinc, and REE 40 minerals. Throughout the Pan-African event sedimentary manganese deposits, lead-zinc, REE 41 minerals, sedimentary phosphates, and again gold were formed. Primary diamonds and 42 magmatic nickel sulphides are related to the break-up of Gondwana, followed by an intense 43 Page 3 of 87A c c e p t e d M a n u s c r i p t lateritic weathering period that formed bauxite deposits along the craton margin.

Abstract. Continental crustal rocks, now structurally beneath the allochthonous Samail ophiolite, underwent blueschist to eclogite facies metamorphism prior to the emplacement of the Oman ophiolite onto the Arabian margin. The recognition of a major low angle fault within this polydeformed and polymetamorphosed sequence of metacarbonates, metabasites, quartzites and quartz mica schists greatly simplifies the interpretation of the structure and metamorphic zonation within the Saih Hatat window, NE Oman. Carpholite-bearing upper plate rocks consist of pre-Permian to Jurassic rocks that have been folded into large recumbent nappe structures which exhibit a marked increase in deformation intensity toward the boundary with the lower plate. The lower plate rocks have higher peak pressure and temperature assemblages; they are exposed in two windows separated by Jabal Abu Daud. Although more intensely deformed, the lower plate rocks are recognizable as metamorphosed continental platform sediments. Fold axes are parallel to the regional NNE-SSW lineation. Sense of shear indicators yield a transport direction of south over north in the lower plate, opposite to the sense of motion inferred for the emplacement of the ophiolite. Lower plate eclogite-facies metabasalts are only preserved in kilometer-scale megaboudins found in the easternmost window at As Sifah. These metamorphic assemblages along with their remnant eastwest fabrics define the existence of a short-lived, Arabian platform-directed, nascent subduction zone. The stretching lineafion elsewhere within the upper and lower plates, the Hatat Schist (the basement), and the metamorphic sole of the ophiolite is consistently NNE-SSW, suggesting that the exhumation of high-pressure metamorphic rocks of Saih Hatat is related to the ophiolite obducfion. Exhumation of the high pressure rocks was accompanied by intense deformation involving regional-scale fold nappes in a convergent margin setting. The geotherm remained suppressed for a period (>30 Myr) greater than the thermal relaxation time of the crust. The geometric and thermal constraints from Oman may be applicable to the general problem of the formation and preservation of high-pressure, lowtemperature rocks.

The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits. crustal evolution | lithosphere | architecture | mantle plumes | Ni-Cu-PGE deposits

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A model was developed to account for the recent observations indicating that type I collagen fibrils assembled in vivo grow from symmetrical pointed tips. The essential features of the model are (i) a distnctive structural nucleus forms at each end of a growing fibril and growth of the fibril then proceeds by propagation ofthe two structural nuclei, METHODSComputer simulations of fibril models were carried out with a Silicon Graphics workstation. Each collagen monomer was represented as a cylinder with a length defined as 4.4 D periods. Models for fibril assembly were simulated by addition of one monomer at a time according to rules for binding through unidirectional 3.4 D-period overlaps or 0.4 D-period overlaps as described in Results. Interactive programs were written so that the models could be rotated in three dimensions after each monomer addition and so that different growth patterns could be explored in two or three dimensions. RESULTSCriteria for the Model. The major criteria for developing a model were that it account for the following observations made on fibrils assembled de novo at 370C (Fig. 1): (i) in cross-section, the a-tips were circular down to a tip of <25 nm (22,24); (ii) axially, the a-tips were near-paraboloidal, as indicated by a decrease in mass toward the tip that was an average of 17 molecular D segments per D period and that was linear over 100 or more D periods (24); (iii) the a-tips on both short and long fibrils were essentially the same (24), an observation implying that the contour remained constant as the fibrils grew; (iv) the (-tips were also near-paraboloidal but were more irregular with slopes that varied from 50 to 200 molecular D segments per D period (24); (v) after the (3-tips appeared, both a-tips and (-tips grew simultaneously on the same fibril (24); (vi) all monomers were oriented so that the N termini were directed toward the tips (22, 24); and (vii) the shafts of all the fibrils formed under the same conditions had about the same diameters (21, 23).Initial Considerations of Alternative Models. Initial considerations indicated that the observations could not be explained in any simple manner by several previous suggestions about fibril growth (Table 1). For example, assembly driven primarily by surface tension and liquid-like forces (see ref.11) cannot readily explain the persistent differences in con§To whom reprint requests should be addressed. 9860The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Generation and emplacement of felsic magmas in the Paleoproterozoic Baoulé-Mossi domain of the West African Craton does not match the apparent peaks of global crust generation identified between ca. 2900-2600, 1900-1600 and 1200-900 Ma. In contrast, across the Baoulé-Mossi domain, the emplacement of felsic intrusions ranges from ca. 2300 to 2000 Ma. It has proven difficult to place this magmatism within a robust geodynamic framework due to the lack of accurate geochronological data from across the West African Craton. The present study addresses this issue by presenting eighty-four new felsic intrusions zircon ion microprobe and LA-ICP-MS U-Pb ages from areas that up until now have not been targeted for geochronology.The new dataset, when fully integrated with existing age data, reveals a craton-wide diachronous geochronological pattern characterized by a magmatic front that migrated westward. This migration proceeded at a rate of 35 km per million years, with an apparent offset of the initiation and cessation of felsic magmatic activity between the east and west of approximately 50 million years. The new data also show that although the entire Baoulé-Mossi domain was subject to continuous magmatic activity for approximately at least 150 million years, this magmatic activity displays a rather different record in the eastern and western portions of the domain. The differences are expressed as a westward migration of the magmatic activity, cessation of activity around ca. 2100 Ma (easternmost portion) and ca. 2050 Ma (westernmost portion) and a higher incidence of inherited ages in the westernmost portion when compared to the easternmost region. In addition, the new U-Pb data identify some of the oldest felsic intrusions in the region, including a granite from Burkina Faso (2265 ± 17 Ma) and a diorite porphyry (2216 ± Ma) in southern Mali. This study also reveals inherited Archean zircon cores from across southern Mali. The combination of the new data presented here, along with previously published data, suggests that the Baoulé-Mossi domain formed from the accretion of two major crustal blocks. The Archean inherited ages open a window for further investigation of the interaction between the Archean Kénéma-Man and the Paleoproterozoic Baoulé-Mossi domains.Rock classification was made based on 3 parameters: 1) hand specimen observations; 2) CIPW norm; and 3) modal composition determined from microscopic evaluation of thin sections, characterized after Streckeisen (1976) (Tables and 3). Zircon morphology and U-Pb datingZircon concentrates were obtained following the standard procedures described in Claoué-Long et al. (1995). Sample processing to obtain zircon concentrates, zircon mount procedures and zircon imaging, which include the use of backscattered electron (BSE) and cathodoluminescence (CL) detectors, are described in Appendix A1. Detailed information about U-Pb isotope analysis of zircon by SHRIMP (Appendix A2) and LA-ICP-MS (Appendix A3), the criteria for rejection of analyses and data reduction are explaine...

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