基于便携式X射线荧光光谱(PXRF)分析的西南印度洋脊龙角区沉积物地球化学找矿研究

洋中脊热液活动伴生的多金属硫化物是未来重要的接替资源，但目前其勘查技术手段相对匮乏。便携式X射线荧光光谱(PXRF)是针对野外原位快速分析而发展起来的一项新技术，常被应用于岩石露头地球化学研究和土壤重金属污染评价。采用PXRF对西南印度洋脊龙角区的沉积物开展了化学组成分析，并通过元素的空间分布特征确定热液区可能产出的位置。结果表明，研究区的沉积物可能由钙质沉积物、基岩碎屑、热液组分等组成，部分沉积物具有较高的热液成矿元素含量，明显受到了热液活动的影响。通过面浓度-个数分形方法，确定Cu、Zn、Fe、Mn、As等主要成矿元素的异常下限。根据上述元素的空间分布特征，在研究区识别出了6处异常区，其中3处异常区与已知热液区相吻合，另外3处异常区可能代表了未发现的热液活动。上述工作为洋中脊多金属硫化物的勘查提供了新的思路。 

Application of PXRF in sediment analysis for geochemical prospecting in Dragon Horn area on the southwestern Indian Ridge

Polymetallic sulfides associated with hydrothermal activity near the mid-ocean ridges are importantpotential replacement resources in the future, while their exploration techniques and methods are relatively scarce at present. The Portable X rayFluorescence Spectroscopy(PXRF) is a new technology developed for in situ rapid analysis in field, and it has been applied in outcrops rock geochemical analyzing, and evaluation of soil heavy metal pollution.In this study, we applied PXRF in geochemical composition analyzing of sediments collected from the Dragon Horn area on the Southwest Indian Ridge, to determine possible location of potential hydrothermal actives by the spatial distribution of elements. The results show that sediments in the study area are consist of calcareous sediments, bedrock debris, hydrothermal ore-forming elements, etc.Some samples show relatively high concentrations of hydrothermal ore-forming elements, which are obviously affected by hydrothermal activities. Based on the C-N fractural method, the threshold anomaly of Cu, Zn, Fe, Mn and As were determined.According to their spatial distribution characteristics of the above elements, six anomalousareas were identifiedin the study area, three of which were consistent with known identified hydrothermal areas, and the other three anomalous areas may represent undiscovered hydrothermal activities.This study provides new strategies for hydrothermal sulfide exploration on mid ocean ridges.