Structures and ore deposits in the Eastern Erzgebirge: Linking the mineral system with post-Variscan transtension

The Eastern Erzgebirge region is exceptionally well endowed in magmatic-hydrothermal ore deposits related to granitic magmatism following the Paleozoic Variscan Orogeny. The Elbe Shear Zone (ESZ) is a major geological structure that forms the prominent eastern border of the Erzgebirge. The ESZ separates the Erzgebirge from the Lausitz Block – the latter being poor in known magmatic-hydrothermal mineralizations. This raises the question about the possible role of the ESZ in the evolution of the Eastern Erzgebirge mineral systems.
The ESZ is well known to be a zone of long-lived (and still ongoing) tectonic activity with mostly dextral kinematics and a total of ~40–50 km offset. It has been subject to a complex interplay of late to post-Variscan tectonic, magmatic, and sedimentary processes, which have left a distinct signature in the magmatic and sedimentary rock record. At least two distinct trans-tensional events can be distinguished and attributed to the dextral activity on the ESZ. These are recorded by (1) the Meissen Massif, a complex intrusion that was emplaced at 330–320 Ma in a dilatational jog, and (2) the Döhlen Basin near Freital, the volcano-sedimentary infill of a small pull-apart basin with abundant ignimbrite/tuff units ranging in age from ~294–286 Ma. The latter evidences for tectonic reactivation along the ESZ and synchronous magmatic events.
These ages bracket a potentially extensive period of activity of the ESZ, supporting a potential for a spatio-temporal link between the ESZ and formation of the Tharandt and Altenberg-Teplice Calderas at ~315–310 Ma. The latter is well known to host a number of small granitic stocks with related Sn-Li-(W-Cu) mineralization. This contribution is a part of the “New Potential” project initiated by the State Geological Survey of Saxony, which deals with the exploration of new perspective areas in the Eastern Erzgebirge mountains. Here, we explore the link between this trans-tensional tectonics and granitic magma emplacement in the Eastern Erzgebirge to better understand the tectonic control on the associated magmatic mineral systems. Significantly, we find that zones of strain-transfer between NW–SE striking dextral strike-slip faults localize felsic magmatism, by accommodating intrusions and establishing favorable pathways to the lower crust through which melts can ascend.