Variscan Sn-W-Mo metallogeny in the gravity picture of the Krusne hory/Erzgebirge granite batholith (Central Europe)
Abstrakt
Late Variscan wolframite (+/- molybdenite) and cassiterite-wolframite greisen, skarn and vein deposits occur in a close spatial association with the granites of the Krusne hory/Erzgebirge batholith (KHEB) in Central Europe. We examined the distribution of the deposits in relation to the gravity field affected by Late Variscan granites using the data from previous gravity and metallogenic studies.
Late Variscan granites are differentiated into earlier biotite monzogranites (low-F granites) and later biotite or lithium mica syenogranites (high-F granites) in accordance with the previous classifications. All the outcrops of granites in the KHEB region and their hidden continuation are confined to the Bouguer anomaly contour of 20 mGal.
The Sn-W-Mo (rare metal) deposits and occurrences are within the gravity contour of 30 mGal with the exception of the Grossschirma stratiform tin deposit in the Freiberg polymetallic ore district. We constructed a geological model based on the gravity data along two profiles across the KHEB showing the position of some rare metal deposits and of outcropping and hidden granite bodies.
The models show that the overlapping of earlier and later granites is in the areas of the most intense regional gravity minima. These coincide with the Eastern Volcano-Plutonic Complex (Altenberg minimum), which encloses large volumes of felsic extrusives, microgranite dikes and granites, and the Western Plutonic Complex (Eibenstock minimum), with small volumes of felsic dikes and predominance of earlier and later granites, with no extrusives preserved.
There is no distinct relationship between the masses of Late Variscan granites and the distribution and the sizes of associated W +/- Mo and Sn-W deposits.