Distribution pattern of gold and Rare Earth Elements in different and mineralized zones of Lakhshak deposit (Sistan Suture zone)
Subject Areas :نسیم حیدریان دهکردی 1 , شجاعالدین نیرومند 2 , حسینعلی تاج الدین 3
1 -
2 -
3 -
Keywords:
Abstract :
Lakhshak deposit is located in the southwestern part of the Sistan Suture zone and 28 km northwest of Zahedan. The exposed rock units include granitoid intrusion and dacite-rhyolite dykes with Oligocene age and calc schist and quartz schist with Eocene age, which have metamorphosed to the green schist facies. This complex has transformed under the influence of a shear zone with a northeast-southwest trend. The composition of intrusive masses placed in the range of granodiorite based on lithological charts. Based on petrographic studies, the minerals that make up the intrusive masses include quartz, alkali feldspar, plagioclase, biotite, sericite, muscovite, iron oxides and calcite. Among the most important types of alteration, we can mention sericite, sulfide, siliceous and carbonate alterations. Analysis of the distribution patterns of rare earth elements in the shear zone samples shows the enrichment of REE in the central parts of the shear zone (severe degrees of alteration and deformation) compared to the foot wall and hanging wall units (weak degrees of alteration and deformation) of the shear zone. The distribution pattern of these elements includes the enrichment of LREE compared to HREE, which can attributed to regional metamorphism at the green schist facies and the circulation of CO2 and SO42- fluids in the Lakhshak shear zone. In addition, the presence of positive and negative Eu anomalies in the shear zone indicates two different stages of alteration. Weak to moderate alteration has led to the creation of positive Eu anomaly and advanced alteration has caused severe decomposition of plagioclase as the main source of Eu and negative Eu anomaly.
