|
|||||
|
|
Indicator minerals of diamond in the lamproitic diatreme, Kostomuksha region, Karelia |
|
| Authors: | V Ya Gor’kovets N S Rudashevskii V N Rudashevskii M G Popov A V Antonov |
| Institution: | 1. Institute of Geology, Karelian Scientific Center, Russian Academy of Sciences, ul. Pushkinskaya 11, Petrozavodsk, Republic of Karelia, 185910, Russia 2. OOO PC+, Svetalnovskii proezd 75/41, St. Petersburg, 195427, Russia 3. Karpinskii All-Russia Geological Research Institute (VSEGEI), Srednii pr. 74, St. Petersburg, 199106, Russia |
| Abstract: | The mineralogy of a new lamproitic diatreme 200–250 m in diameter and 3 ga in area is studied in detail. The chemical and 3-D mineralogical analysis identify the diatreme rocks as strongly altered olivine lamproites with a large volume (50–60%) of xenoliths of strongly altered spinel (garnet) lherzolites and harzburgites-dunites. Numerous grains-xenocrysts of indicator minerals of diamond have been extracted from the heavy concentrates (the weight of the initial product is 742 g and the size is 100–500 μm) as a result of hydroseparation: (1) subcalcium (CaOav. 2.6 wt %) high-Cr (Cr2O3 av. 5.3 wt %) pyrope (50 grains); (2) chrome diopside (7 and 8 mol % of kosmochlor and jadeite components, respectively, >40 grains); (3) high-Cr chromite (Cr2O3 > 62 wt %); and (4) picroilmenite (MgO 12–13.8 wt %) and Cr-rutile (Cr2O3 1.1 wt %). Xenocrysts prove the mantle endogene (the level of garnet lherzolites) source of the magmatic center of lamproites and forecast the diamond potential of the new diatreme in the Kostomuksha ore district. |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |