Structural-metasomatic model of the Aktogai porphyry copper ore field based on remote sensing (north-eastern Balkhash region)

Abstract

Relevance. Currently, the main source of copper and some precious metals are porphyry copper deposits. According to modern concepts, such deposits were formed in suprasubduction conditions within basaltoid and andesitoid volcano-plutonic belts. Similar geodynamic settings have been established in Central Asia. The Aktogay ore field is located within the Zhongaro-Balkhash volcano-plutonic belt of the Late Paleozoic age, within which other porphyry copper objects are localized. The ore field deposits were explored in the 70–80s of the last century, and their development began only a few years ago. Virtually undisturbed landscapes (in relation to ASTER surveys), a high degree of outcrop and arid climatic conditions make it possible to form a reference exploration model of porphyry copper systems based on remote sensing data from space on the basis of the Aktogay ore field. Aim. Identification of ore-controlling structures and wallrock metasomatites of porphyry copper deposits of the Aktogay ore field. Methods. The source materials were the data of space surveys ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) and Landsat-8. To identify structural patterns, the digital elevation model SRTM (Shuttle Radar Topography Mission) was also used. To identify wallrock metasomatites, the authors used the methods of space infrared spectroscopy – artificial colors, mineral indices and main components, which revealed characteristic absorption bands. Results. Structurally, wallrock metasomatites and mineralization are controlled by the conjugation zones of longitudinal and transverse faults in relation to the strike of the Bakanas-Alakol segment of the Zhongaro-Balkhash volcano-plutonic belt. Based on the results of processing and decoding, the autghors identified zonally located propylites, argillizites and phyllisites. The paper demonstrates the spatial relationship of the identified phyllisites and argillizites with ore stockworks of the ore field deposits.

Keywords

• Aktogay
• Zhongaro-Balkhash belt
• porphyry copper deposits
• remote sensing methods
• metasomatic zoning
• Aster