The study of the characteristics of element geochemistry in stream sediments constitutes the basis of the regional geochemical prospecting. As the new indicators in geochemical exploration, the dispersed elements can play a remarkable role in the prospecting task. Due to the backward situation of the research work in Tibet, the previous regional geochemical exploration mostly laid emphasis on the study of the main ore-forming elements and useful associated elements, whereas researches on the dispersed elements were very insufficient. This paper reports for the first time the characteristics of the dispersed elements in 680 stream sediment samples collected from Tibet. From the regional point of view, Cd, Se and Te are concentrated obviously in steam sediments in this area, whereas other elements present homogeneous distribution. Compared with the average values of the dispersed elements of the steam sediments in Yangbajain-Nyingzhong area, Cd, In, Se and Te are considerably concentrated in the Permian Luobadui Formation, which is probably caused by the weathering of such metal sulfides as sphalerite and galenite in the Luobadui lead-zinc-copper deposit, whereas the enrichment of Tl is probably related to the hydrothermal sedimentation of the geothermal resources in Yangbajain-Nyingzhong area. The content of the dispersed elements in steam sediments present in intrusive rocks of different ages is close to the average content of the study area, only with the weak enrichment of In and Tl. As the new indicators of geochemical exploration, Cd, In, Se and Te can indicate the locations of lead-zinc ore bodies, thus providing the geochemical foundation for the prospecting of lead-zinc polymetallic deposits in this area.%水系沉积物中元素地球化学特征研究是区域地球化学勘查找矿工作的基础，分散元素作为一类新型的地球化学勘查指标，已在勘查找矿工作中显示出显著的效用。西藏地区研究程度低，以往区域地球化学勘查工作中，多以主成矿元素及伴生有益元素研究为主，一直缺乏对分散元素组成特征的研究。本文首次报道了西藏羊八井-宁中地区680件水系沉积物样品的分散元素地球化学特征。从区域上看，研究区内水系沉积物中强烈富集 Cd、Se、Te 元素，其它元素分布均匀，无富集。与羊八井-宁中地区水系沉积物中分散元素平均值相比，区内二叠系洛巴堆组地层中强烈富集Cd、In、Se、Te元素， Tl仅在第四系中富集， Cd、In、Se、Te元素的富集可能是由洛巴堆铅锌铜矿床中闪锌矿、方铅矿等金属硫化物的风化作用引起的， Tl元素的富集与羊八井-宁中一带地热资源的热水沉积作用有关；不同时代侵入岩区水系沉积物中分散元素含量接近研究区平均值，仅有 In、Tl 呈现弱的富集。Cd、In、Se、Te 元素作为地球化学勘查指标，可指示铅锌矿化体的产出范围，为区内开展铅锌多金属矿产勘查工作提供了地球化学依据。
展开▼
