| LIAO Shili,TAO Chunhui,LI Huaiming,ZHANG Guoyin,LIANG Jin,YANG Weifang. 2017. Use of portable X-ray fluorescence in the analysis of surficial sediments in the exploration of hydrothermal vents on the Southwest Indian Ridge. Acta Oceanologica Sinica, 36(7):66－76 |
| Use of portable X-ray fluorescence in the analysis of surficial sediments in the exploration of hydrothermal vents on the Southwest Indian Ridge |
| 基于PXRF的西南印度洋脊硫化物表层沉积物地球化学找矿研究 |
| Received:May 05, 2016 Revised:March 17, 2017 |
| DOI：10.1007/s13131-017-1085-0 |
| Key words:mid-ocean ridge sediments hydrothermal activity portable X-ray fluorescence geochemical exploration |
| 中文关键词: 洋中脊沉积物 热液活动 PXRF 地球化学找矿 |
| 基金项目:The Open Fund of Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources under contract No. KLMMR-2015-B-03; the China Ocean Mineral Resources Research and Development Association Project under contract Nos DY125-11-R-01 and DY125-11-R-05; the National Basic Research Program (973 program) of China under contract No. 2012CB417305. |
| Author Name | Affiliation | E-mail | | LIAO Shili | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Marine Mineral Resources, Ministry of Land and Resources, Guangzhou 510075, China | | | TAO Chunhui | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China | taochunhuimail@163.com | | LI Huaiming | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China | | | ZHANG Guoyin | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China | | | LIANG Jin | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China | | | YANG Weifang | Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012, China
Key Laboratory of Submarine Geosciences, State Oceanic Administration, Hangzhou 310012, China | |
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| Abstract: |
| Hydrothermal plumes released from the eruption of sea floor hydrothermal fluids contain large amounts of ore-forming materials. They precipitate within certain distances from the hydrothermal vent. Six surficial sediment samples from the Southwest Indian Ridge (SWIR) were analyzed by a portable X-ray fluorescence (PXRF) analyzer on board to find a favorable method fast and efficient enough for sea floor sulfide sediment geochemical exploration. These sediments were sampled near, at a moderate distance from, or far away from hydrothermal vents. The results demonstrate that the PXRF is effective in determining the enrichment characteristics of the ore-forming elements in the calcareous sediments from the mid-ocean ridge. Sediment samples (>40 mesh) have high levels of elemental copper, zinc, iron, and manganese, and levels of these elements in sediments finer than 40 mesh are lower and relatively stable. This may be due to relatively high levels of basalt debris/glass in the coarse sediments, which are consistent with the results obtained by microscopic observation. The results also show clear zoning of elements copper, zinc, arsenic, iron, and manganese in the surficial sediments around the hydrothermal vent. Sediments near the vent show relatively high content of the ore-forming elements and either high ratios of copper to iron content and zinc to iron content or high ratios of copper to manganese content and zinc to manganese content. These findings show that the content of the ore-forming elements in the sediments around hydrothermal vents are mainly influenced by the distance of sediments to the vent, rather than grain size. In this way, the PXRF analysis of surface sediment geochemistry is found to satisfy the requirements of recognition geochemical anomaly in mid-ocean ridge sediments. Sediments with diameters finer than 40 mesh should be used as analytical samples in the geochemical exploration for hydrothermal vents on mid-oceanic ridges. The results concerning copper, zinc, arsenic, iron, and manganese and their ratio features can be used as indicators in sediment geochemical exploration of seafloor sulfides. |
| 中文摘要: |
| 海底热液喷发形成的热液羽状流中富含成矿物质，并沉淀在距离热液喷口不等的范围内。对西南印度洋中脊热液喷口附近、距离喷口中等距离、远离喷口的六个表层沉积物样品开展了不同粒度沉积物的便携式XRF（PXRF）分析。结果表明，PXRF可以有效获得的洋中脊钙质沉积物中成矿元素的富集特征。>40目的沉积物样品具有较高的Cu、Zn、Fe、Mn等元素含量，40目以下沉积物中则相对稳定，可能与粗粒沉积物中玄武岩碎屑/玻璃含量较高有关，与镜下鉴定结果一致。以热液喷口为中心，表层沉积物中表现出Cu、Zn、As、Fe、Mn的元素分带，靠近喷口的沉积物中具有较高的成矿元素的含量，并具有较高的Cu/Fe、Zn/Fe比值或者Cu/Mn与Zn/Mn比值。上述结论表明，洋中脊沉积物中成矿元素的含量主要受与喷口的距离的影响，而与粒度的关系不大，洋中脊沉积物地球化学找矿应采用40目以下粒径沉积物作为分析样品。通过PXRF获得的Cu、Zn、As、Fe、Mn等元素含量及其比值特征可以作为海底多金属硫化物沉积物地球化学找矿的指标，该方法满足快速有效识别洋中脊沉积物中地球化学异常的要求。 |
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