Metallogenesis along a fossil oceanic fracture zone: Arakapas fault belt,Troodos Massif,Cyprus |
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| Authors: | AHF Robertson |
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| Institution: | Grant Institute of Geology, West Mains Road, Edinburgh , EH9 3JW Scotland |
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| Abstract: | The Arakapas fault belt, southern Troodos Massif, which is interpreted as a fossil oceanic fracture zone, contains a sedimentary and volcanic “fill” including basaltic lava breccias, volcaniclastic sandstones, intercalated Fe-rich mudstones, and minor Cu sulphide mineralisation. The volcaniclastic sedimentary rocks were produced by submarine weathering and gravity redeposition of basalt within the transform zone. In contrast, the Fe-mudstones predominantly originated as chemical precipitates from hydrothermal solutions generated by hydrothermal leaching of basalt by seawater. The rare earth elements, and some trace metals, including Co, Ni, Pb, V and Zr, are thought to have been incorporated from seawater into the ferruginous precipitates. Unusually high Fe/Mn ratios of the Fe-mudstones relative to most modern ocean-ridge sediments may reflect deposition in relatively oxygen-depleted waters on the floor of a major bathymetric depression created by the transform faulting; release of acidic thermal waters would have further suppressed Mn precipitation. Contrary to recent suggestions of metallogenesis along oceanic fracture zones, none of the major Cyprus cupriferous sulphide bodies lie along the fossil Arakapas transform zone. |
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