Geology and Exploration of the Disseminated Copper Deposits in the Sipalay Mine

Abstract

Ore deposits of the Sipalay Mine are of the disseminated copper type occurring in quartz-diorite porphyry and in the surrounding meta-volcanics near the contact.
Detailed geological mapping and structural analysis of the known deposits led to the discovery of a new huge deposit under an alluvial plain.
The following geological interpretations were used successfully to locate the new ore body:
1) The shape and locus of igneous intrusions were influenced by a fissure pattern developed successively by (a) a shear couple (E-W and N-S) with northeasterly tension and northwesterly compression, and (b) northeasterly lateral compression.
2) Although the main quartz diorite intrusive is elliptical in plan and elongated parallel to tensional fractures, the laters differentiates were squeezed out beyond the periphery of the main mass, especially along the northeasterly and northwesterly fissures. These porphyritic offshoots are considered to be closely related to the copper mineralization.
3) Shattered zones formed by the intersection of fissures along the four main directions in and adjacent to the porphyritic offshoots provided a favorable setting for ore concentration.