Articles / abstracts:

Ansdell, Kevin, M; Abeleira,  Albert; Ivanov, Sergey; Thomas, David; Sopuck, Vladimir.  The Kumtor gold deposit, Kyrgyzstan; complex structural, stratigraphic and vein relationships in the central Tien Shan. In: Quebec 1998; recueil des resumes; Carrefour des sciences de la terre--Quebec 1998; abstract volume; Crossroads of Earth sciences.

Sergey M. Ivanov, Kevin M. Ansdell, Dwayne L. Melrose.  Ore texture and stable isotope constraints on ore deposition mechanisms at the Kumtor lode gold deposit. In: Gold in 2000 poster session: Extended abstract volume ABSTRACT: Mineralization at Kumtor gold deposit, Kyrgyzstan, is hosted in the Vendian carbonaceous phyllites and overprints the three deformational fabrics, which constrains its age to Late Paleozoic. Gold mineralization is related to intensive veining, stockworks and hydrothermal breccias. Native gold, Au and Au-Ag tellurides are intimately related with pyrite. Also, their textural association with altaite, magnetite, hematite, barite, strontianite, calcite, galena and sphalerite, and locally corroded pyrite, suggests that fluctuations in f(O2) was a significant factor in gold deposition. f(O2) fluctuations may also account for differences in the d34S signatures of Stage 2 vs. Stage 3 pyrites. CO2 effervescence during hydrothermal brecciation may have caused increase in f(O2), pH, depletion of fluids in 18O during Stage 3, and promoted carbonate deposition. Hydrolysis of carbonaceous matter from the hosting lithology might have initially produced and replenished lost CO2. Fluid inclusion analysis will be vital in constraining the nature of these processes.

Posters / presentations.

Sergey M. Ivanov, Kevin M. Ansdell.   Constraints on the fluid evolution at Kumtor gold deposit: textural relationships and stable isotopes. An oral presentation on the Geological Society of America Meeting in Reno, Nevada. Economic Geology session.

Ivanov, S. M., Ansdell, K. M. Vein paragenesis at the Kumtor gold deposit, central Tien Shan, Kyrgyzstan. Abstracts with Programs - Geological Society of America. 30; 7, Pages 367. 1998. ABSTRACT: The Kumtor deposit, Kyrgyzstan, Central Asia, contains ca. 80 Mt of proven reserves at an average grade of 3. 58 g/t Au, and is hosted by a Vendian (Neoproterozoic) sequence of carbonaceous pelites with interbedded carbonates and siltstones. These rocks have undergone three deformational events (D1-3), probably related to Paleozoic collisions that generated the Tien Shan. The deposit is located in the hangingwall of the long-lived Kumtor Fault Zone (KFZ), which may be a splay off the regional Nikolayev Lineament. The Carboniferous clastic rocks in the footwall to this fault were folded during D3, but were unaffected by earlier deformation events.Diagenetic framboidal pyrite and segregations of carbonate and quartz were recrystallized and deformed during peak regional greenschist grade metamorphism and associated deformation (D1). Quartz-carbonate-albite+ or -chlorite+ or -pyrite veins formed subparallel to the S1 phyllosilicate foliation. Later tension gash, sigmoidal, and fibrous veins consisting of c teraction of (oxidizing?) fluids with carbonaeous material, and catastrophic pressure release during hydrothermal brecciation.