... yellowish-green cubic diamond crystals in Paleogene Ti-Zr placers near the northern margin of the Kokchetav Massif ( Kashkarov & Polkanov, 1972 ). In the late 1970s, diamonds were also found within the weathering profile of carbonate-silicate rocks lining the shoreline of the Kumdy Lake (Kumdy-Kol...

... deposit, on the northeastern side of Kumdy-Kol Lake. In all maps presented in the 2000 special issue of the Island Arc magazine devoted to the Kokchetav UHP rocks and diamond ( e.g., Kaneko et al. 2000 , Theunissen et al. 2000 ), they are shown as UHP rocks. These gneisses have all petrographic...

...Fig. 2. Schematic geological map of the Kumdy Kol Lake area (modified after Zhang et al., 1997 ). 1 , eclogites; 2 , TiChu garnetites (ʻGrt peridotitesʼ); 3 , diamond-bearing metasedimentary rocks (gneisses and calc-silicate (pyroxene-carbonate and garnet–pyroxene–carbonate) rocks); 4...

... with different PT -evolution. In the Kumdy-Kol and Barchi-Kol tectonic plates, boreholes and adit exposed diamond-bearing calc-carbonate rocks and gneisses. The rocks of the Kulet and Sulu-Tuba terranes lack diamonds, though in places (southwest and south of Lake Kulet) coesite is found in them. In contrast...

..., 2003 ) compared to those of the Erzgebirge. At one locality near Lake Kumdy-Kol, the UHP rocks can be as massive as the saidenbachite from the Erzgebirge. Such a massive rock is a kumdykolite used for our experiments. This rock is rich in garnet and quartz and probably originated from a calcareous...

... sites with discovered diamond-bearing metamorphic rocks within the Kokchetav massif ( Lavrova et al., 1999 ; Shatsky and Sobolev, 2003 ; Shatsky et al., 1991 , 1995 ): Kumdy-Kol deposit of metamorphic diamonds and two sites in the area of Lake Barchi, located 17 km east of Lake Kumdy-Kol ( Fig. 1...

... of Lake Kulet). Unlike the Kumdy-Kol’ terrane, metacarbonate rocks are absent but there are interbeds of talc-garnet, talc-phengite, and other high-Mg rocks [ 14 , 17 , 20 – 22 ]. Table 1. Results of Geochronological Dating of Rocks of the Kokchetav Massif No. Rock Coordinates Mineral...

... metamorphic rocks of the KSCZ ( Dobretsov et al., 2006 ) ( Fig. 1 ) have been exhumed from at least two levels ( Dobretsov and Shatsky, 2004 ). The rocks of the western block were metamorphosed at pressures corresponding to the diamond stability field (Kumdy-Kol, Barchi localities), while in the eastern block...

... of domains (terranes) with different metamorphic histories, formed as a result of multiple subduction and collision of the Kokchetav microcontinent with a Cambrian island arc [ 8 , 9 ]. These ideas evolved further through structural studies [ 10 , 11 ], which postulated that the diamond-bearing Kumdy-Kol...

... that contains titanite with coesite needles and plates. Diopside- and K-feldspar-bearing, calcite marble were collected at a dump site near Kumdy-kol Lake in the Kokchetav Massif. This impure calcite marble lacks microdiamond, however, demonstrating unique UHP mineral chemistry. Two samples of the marble...

...Andrei V. KORSAKOV; Vladislav S. SHATSKY; Nikolay V. SOBOLEV; Anton A. ZAYACHOKOVSKY Abstract Clinozoisite gneisses were studied from the Barchi-Kol area, located 17 km to the west of the Kumdy-Kol microdiamond deposit at Kokchetav massif (Northern Kazakhstan). As distinct from the deposit...

... they were found to contain polycrystalline quartz aggregates surrounded by radial cracks in garnets from high-temperature eclogites of the Kumdy-Kol’ area. This feature allowed the aggregates to be interpreted as pseudomorphs after coesite [ 8 ]. The absence of coesite is explained by high equilibrium...

.... For comparison, the average compositions of harzburgites and pyroxenites and the composition of garnet orthopyroxenite sampled in the vicinity of Enbek-Berlyk Village ( Fig. 1 ) are given, as well as the average composition of garnet peridotite sampled near Lake Kumdy-Kol’ in the western part of the Kokchetav...

... — postmetamorphic collisional intrusions: granites and basites, 14 — lakes, 15 — thrusts. Inset: 1 — eclogites, 2 — gneisses and schists, 3 — carbonatites and ultrabasites, 4 — granitoids ( a ), orthogneisses ( b ). The diamond-bearing metamorphic rocks from the Kumdy-Kol’ UHP unit are known from...

..., Kumdy-Kol); 5 , other terranes containing eclogites, garnet amphibolites, and garnet peridotites in granite-gneisses and micaceous schists (terranes: 3, Sulutobe; 4, Kulet; 5, Enbek-Berlyk; 6, its analogs north of Shchuchinsk); 6 , Vendian (?) volcanosedimentary rocks in an accretionary prism; 7...

... as its basement ( Dobrzhinetskaya et al. 1994 ; Dobretsov et al. 1995 ; Turkina et al. 2011 ). Within these Precambrian suits are tectonically juxtaposed HP and UHP terrains (from west to east): Barchi-Kol, Kumdy-Kol, Sulu Tjube, Enbek Berlyk, and Kulet. UHP rocks are exposed in Kulet, Kumdy-Kol...

... different PT -conditions ( Fig. 1 ). The rocks of the diamond-free (eastern) Kulet and diamond-bearing (western) Kumdy-Kol blocks are of different compositions and internal structures and correspond to the coesite and diamond subfacies of metamorphism ( Theunissen et al., 2000 ). The blocks are separated...