Provenance identification of soil at the confluence of Thar desert, Aravalli hills, and alluvial plain based on trace and rare earth elements geochemistry

摘要

Khetri Copper Belt (KBC), India, lies in the semi-arid region at the confluence of Aravalli ranges and alluvial soil. A study is designed to understand the influence of aeolian processes on soil geochemistry (major oxides, trace elements and REE) at the edge of desert. Mines of copper, quartzite and granite are active in the region and for the study the region is divided into three zones such as copper mine zone (CMZ), quartzite mine zone (QMZ) and granite mine zone (GMZ). CMZ is located in the windward of Aravalli hills (considering Thar desert as a reference point) and significantly influenced by strong winds from Thar desert. Low values of CIA (60) at CMZ compared to PAAS (CIA=70) are attributed to significant impact of aeolian processes. QMZ is quartzite enriched zone and low average value of CIA (60) is due to less weathering of parent quartzite rocks. Cu and Zn are major nutrient for plants and a positive correlation of Cu and Zn with N and C at QMZ indicates high fertility of soil (alluvial soil) and negligible influence of aeolian processes is attributed to its leeward location from Aravalli hills, the physical barrier. Eu anomaly and variations in trace elements (La/Th, Th/Sc and La/Sc) confirm the felsic source of soil. The UCC normalised plot for Sigma REE shows the enrichment of REE at QMZ and GMZ as compared to CMZ is due to presence of heavy minerals. Thus, less impact of aeolian processes on QMZ lies in the leeward of Aravalli ranges indicating that the Aravalli ranges shield the transportation of aeolian sand.