Exploration and its results of placer type titanium deposits in Kokpektinskaya area, the Republic of Kazakhstan

摘要

An exploration and geological investigation program was carried out from fiscal years 2000 to 2002 in Kokpektinskaya area (120km to south of Ust-Kamenogorsk) in order to increase ore reserves and clarify the resource potential of ilmenite placer deposits. The ilmenite placer deposits in the area are embedded in sandy clay sediment of the Aral Formation of Neogene and hosted within clayey sand above an unconformable surface of weathered basement rocks. They are covered by thick Neo-gene and Quarternary sediments up to 54m in thickness and totally concealed. The program consists mainly of drilling exploration, petrological and magnetic susceptibility study of source granitoids and paleogeomorphology of the pre-Neogene basement. Japan International Cooperation Agency (JICA) and Metal Mining Agency of Japan (MMAJ) conducted the program under the request of the Kazakhstan Government. Drilling exploration in the southern extension of the Bektimir No. 1 deposit showed that it has a strike length of 2.5km, width up to 2km and average thickness of 4.8m. The calculated ore reserves are 13.3 million m~3, average grade is 126.7 kg ilmenite/m~3 (cut-off grade: 100 kg ilmenite/m~3) and ilmenite contained is 1,686,000 tonnes in total. Investigations of source granitoids concluded that the high ilmenite content rock type is little-differentiated granitoids such as gabbro, diorite and monzonite with low magnetic susceptibility. Paleogeomorphological structure contour maps show that the deposits occupy structural channels, which are interpreted as river valleys of the pre-Neogene basement. An area east of the Bektimir No. 1 deposit was selected as an exploration target, which is corresponds to the above conditions. After the area was selected, drilling survey followed, and intercepts of ilmenite concentration were encountered as a new discovery. The showing has a strike length of 2.5km, width of 200 to 600m and thickness of 0.7 to 4.5m. The calculated potential reserves are 1.05 million m~3, average grade is 30.9 kg ilmenite/m~3 and ilmenite contained is 32,500 tonnes (cut-off grade: 20kg ilmenite/m~3). Due to the perception that the deposit enlarges and becomes richer toward the downstream, it is a prospective target for further exploration.