It is argued, that plate convergence, i.e. subduction, at other than right angles under a continental margin may lead to compensa- tional transcurrent faulting in the sialic environment. In this pro- cess the introduction of ultrabasic slivers, derived from the down- going oceanic crusial plate, along this fault may occur. This regi- me, both compressive overall and tensional along the transcurrent fault, will contain numerous indications for ongoing igneous and tectonic processes (such as volcanism, hot springs and frequent earthquakes)._x000D_
Examples for this scenario are California, the hinge between the Alpine- and Appennine orogens and the island of Sumatra._x000D_
Igneous manifestations of subduction will be present both as inter- mediate intrusions and/or andesitic piles. The intermediate volca- nics may be intensely altered (chloritic, propylitic, argillic). Silice- ous breccias and banded chalcedonic sinters may be commonly found. This entire scenario is indicative for epithermal gold mine- ralisation.