东海陆架北部表层有用重砂资源形成条件及成矿远景

FORMATION AND PROSPECT OF VALUABLE HEAVY MINERALS IN SURFACE SEDIMENTS IN THE NORTHERN EAST CHINA SEA SHELF

对2007年取自东海陆架北部海域336个表层沉积物样品进行了重矿物研究,计算了钛铁矿、石榴石、锆石、金红石4种有用重砂矿物的品位,其异常品位值主要富集在研究区的北部和东南部。形成条件分析表明,古长江等陆源河流供给形成的陆架残留沉积物为重砂矿物的富集提供了物质来源;粉砂质砂、砂质粉砂和砂等粗粒沉积物类型也有利于重砂矿物的保存;冰后期海侵过程中的水动力和现代水动力条件都有利于重砂矿物的进一步富集,且现代水动力条件对已富集的区域起到重要的保护作用。综合品位分布情况、离岸距离、水深和沉积物类型等条件,将东海陆架北部海域重砂矿物资源划分为5个成矿远景区,为将来开发提供了科学依据。

In this paper, heavy minerals are identified for the 336 surface sediment samples taken from the northern East China Sea shelf in 2007. Ilmenite, garnet, zircon and rutile are picked out from heavy minerals as valuable ones. High grade of the valuable minerals are distributed in the northern and southeastern parts of the studied area. There are several reasons for the enrichment of the valua ble heavy minerals： a） paleo-Yangtze River and other rivers provided sediments rich in these valuable heavy sands; b） coarse grains sediments like sand and silty sand are helpful for heavy sands enrich- ment; c） both postglacial transgression and modern hydrodynamic conditions have contributed to the enrichment of heavy minerals and d） the modern hydrodynamics are favorable for the preservation of heavy minerals against retransportation. The studied area can be divided into five prospecting areas based on integrated evaluation of various factors, such as grades of valuable heavy minerals, offshore distances water depth, sediment type and other relative factors. Our research has paved a scientific foundation for future exploitation of heavy minerals in the northern East China Sea shelf.