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The gold of Granada: Geology and history

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Abstract

Gold of alluvial origin is found in Granada (SE Spain), occurring as fine, millimetre- to centimetre-sized plates. It has been panned in the Genil and Darro rivers since Roman times, and was also mined in the conglomerates of the 'Alhambra Formation'. The 'Alhambra Formation' is an alluvial-fan deposit, up to 200 m thick, of lower Pliocene age (~5 My). The area of the mine corresponds to a poorly-sorted, well-rounded conglomerate, with clasts of metamorphic rocks. The mine is Roman and was exploited using the 'Ruina Montium' method: a huge scar on top of the hill, from which the man(Roman)-induced landslide started, can still be recognized. This mine, with an average gold content of 0'5 gr/m3, was worked again between the years 1875 and 1877 by a French company: they dismantled the gold-bearing conglomerate using a powerful water jet, and separated the gold by amalgamation with mercury. The origin of the gold is closely related to that of the 'Alhambra Conglomerate', which comes in turn from the erosion of an older, Miocene conglomerate. The source rocks for the latter are those of the metamorphic Sierra Nevada core. Gold concentration took place during successive processes of erosion, transportation and deposition (sedimentary cycles). The Miocene conglomerate formed first; then the 'Alhambra Conglomerate', and, finally, the placer-deposits linked to the Genil and Darro rivers. Gold has been panned exclusively in these rivers at those places where they cut across the 'Alhambra Conglomerate'.
... The palaeoenvironmental model for Subunit E1 ('Alhambra system') is that of coalescent alluvial fans, placed at the base of the palaeo-Sierra Nevada and palaeo-Sierra Arana reliefs at the eastern side of the basin (Martín 2000), passing laterally to the North to a fluvial system and this, in turn, to a lake (Fig. 3). ...
... In Crevillente the Apodemus meini Zone (Middle Turolian) has in its upper part Fig. 7. Unit E. ᮀA. Sediment distribution (lithofacies) and position of the studied sections (data from Elorza et al. 1978;Dabrio & Fernández 1986;Fernandez & Soria 1987;Lupiani & Soria 1985a, b;Martín 2000; and this study). ᮀB. ...
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