MINDeSEA WP5 Marine Placer Deposits (Area)

Marine placer deposits have received much attention during marine exploration. They comprise detrital heavy metallic minerals and gemstones, eroded from, usually igneous, source rocks on land and transported to sea, mostly by rivers. Thereby placer deposits are concentrated by water motions (waves, tides, currents). The most important of these minerals, from an economical aspect, are: cassiterite (tin), ilmenite and rutile (titanium), zircon (zirconium), chromite (chromium), monazite (thorium), magnetite (iron), gold; the principle gemstone is diamond (Harben & Bates 1990). According to Daesslé and Fischer (2013) about 75% of the world’s tin, 11% of gold, and 13% of platinum are extracted from placers (Baker et al. 2014). Marine placer occurrences can be classified taking into account various factors.海洋砂矿（marine placer deposits）在海洋勘探领域受到广泛关注。此类矿床由通常源自陆上火成岩母岩经侵蚀形成、并多经河流搬运至海洋的碎屑重金属矿物与宝石构成。进而，水体运动（波浪、潮汐、海流）可使此类砂矿发生富集。从经济价值维度来看，其中最为重要的矿物包括：锡石（cassiterite，锡）、钛铁矿（ilmenite）与金红石（rutile，钛）、锆石（zircon，锆）、铬铁矿（chromite，铬）、独居石（monazite，钍）、磁铁矿（magnetite，铁）以及金；主采宝石为金刚石（diamond）（Harben & Bates 1990）。据Daesslé与Fischer（2013）的研究，全球约75%的锡、11%的黄金与13%的铂均产自砂矿（Baker等，2014）。海洋砂矿产出地可依据多种因素进行分类。