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VMS Deposits on Cyprus

Ophiolite-hosted VHMS (Volcanic-Hosted Massive Sulphide) deposits, also known as Cyprus-type VHMS deposits, are seen in at least 25 of the worlds more than 200 known ophiolite terranes. The term Cyprus-type should now be considered a bit of a misnomer, as the Troodos ophiolite - to which the Cyprus-type name refers - is not a typical Mid-ocean ridge ophiolite - indeed it is considered to be a supra-subduction zone ophiolite, similar to the present day Mariana-Bonin arc.

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The Geology of Cyprus

Cyprus is situated in the easternmost part of the Mediterranean, around 80 miles from Turkey in the north, around 100 miles from the coasts of Syria and Lebanon to the east and, to the south, around 300 miles from Egypt and Israel.

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The Origin and Early Evolution of Birds

Birds are phylogenetically considered to be members of the theropod dinosaurs; their closest non-avian relatives are the dromaeosaurid theropods. The first known fossil bird is Archaeopteryx, from the late Jurassic of Bavaria, Germany, which is represented by seven skeletons and a feather. There is no fossil evidence from before this time that has been proven to be of avian origin. The fossil record of modern birds began in the early Tertiary (Padian et al., 1998).

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What kinds of isolation can lead to the formation of a new species?

According to the biological species concept, populations are different species if gene flow between them is prevented by biological differences, known as reproductive barriers. If populations exchange genes they are conspecific, i.e. belong to the species, even if they differ greatly in morphology. If they are reproductively isolated, they are different species even if they are indistinguishable phenotypically. Therefore speciation arises from the evolution of biological barriers to gene flow (Futuyma, 1998).

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Ooid Formation

Ooids are spherical or ellipsoid concretions of calcium carbonate, usually less than 2mm in diameter (Donahue, 1969; Tucker and Wright, 1990). There have been examples in the Neoprotozoic of ooids that are 16mm in diameter (Sumner, 1993), but all modern ooids are 2mm or less. The interior of an ooid is usually composed of a nucleus, which is surrounded by a cortex of calcite or aragonite crystals that are arranged radially, tangentially or randomly (Figure 1). These crystals are arranged in concentric lamina.

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