No abstract

A distinct increase in the concentration of W in the topsoil (from 19–20 to 71 ppm) is found in the vertical profile of the alluvial soil at the Grantcharitsa deposit. The distribution of W, Fe, and C is well correlated, which indicates a significant role of organic material and iron oxides/hydroxides formed in the soil in the chemical behavior of W. The role in these processes of scheelite, W-containing goethite and rutile identified in the soil is insignificant.

U-Pb-zircon and monazite ID-TIMS and in-situ LA-ICP-MS and EPMA analyses are combined to define the magmatic age of the Igralishte granite, which is exposed over 32 km2 in the high-metamorphic rocks of the Serbo-Macedonian Massif (Ograzhden Mountain, SW Bulgaria). The granite is dated at 243.28 ± 0.84 Ma by concordant zircons (ID-TIMS data) and this intrusion age is confirmed also by in-situ LA-ICP-MS and EPMA monazite analyses. The intrusion of the Igralishte granite at middle Triassic time defines the age of the high-grade metamorphism in Ograzhden Mountain as Pre-Triassic. A tectonic and hydrothermal overprint is dated at 36.36 ± 0.56 Ma by the Rb-Sr whole-rock-biotite reference line. This age is considered as the youngest thermal event in the region of the Igralishte pluton that reached the 300 ± 50 °C closing temperature of the Rb-Sr isotope system in the biotite, but could not fully reset the Rb-Sr isotope system of the muscovite. The initial strontium ratio of 87Sr/86Sri = 0.7078 and the inheritance of old lead components in the zircons suppose crustal-dominated source of the magma. Preferred tectonic scenario suggests dehydration melting and granite formation in the middle/upper crust at the Permian-Triassic boundary and the Lower-Middle Triassic caused by mafic intrusions at the base of the crust.

No abstract

Samples of water flowing from the abandoned prospecting gallery at the Grantcharitsa tungsten deposit and the accompanying ocherous iron oxide precipitates taken in different seasons are the subject of the study aimed at establishing the chemical and phase composition of ocher iron oxide materials and its relationship with water composition. The studied drainage waters are low-mineralized, with a pronounced seasonally dependent pH parameter. Water acquires the features characteristic of acid mine drainage only during the season of high waters, while at other time it is gradually neutralized. The low-crystalline (ferrihydrite+schwertmannite) precipitates formed in the place of water discharge are inhomogeneous with a variable content of Si, Fe, and W. It was found that the W content in them correlates with the Fe content.