Garnets from the bottom sediments of the Akademichesky Ridge (Lake Baikal)as indicators of transportation mechanism and sourceland of clastic material

Data of mineralogical investigation of the recent (0-200 ka) bottom sedimen ts of the Akademichesky Ridge are presented. The Akademichesky Ridge is an uplift in the center of Lake Baikal, separated from the shoreline by deep b asins. Therefore, the possible mechanisms of transportation of elastic pebb les are summer (by air) and winter (by ice) eolic transportation, glacial t ransportation, and disintegration of the ridge rocks. The character of the surfaces of garnet grains along with experimental data support the importan t role of eolic transportation in sedimentation. Five groups of garnets, corresponding to various types of metamorphic and m etasomatic rocks, are distinguished according to their composition: 1) alma ndine-pyrope-grossular, typical of metamorphic rocks of mafic and intermedi ate compositions; 2) andradite-grossular, usual for scarns and high-tempera ture synmetamorphic metasomatites; 3) almandine-pyrope, occurring in metape lites of greenschist-amphibolite and granulite facies of metamorphism; 4) s pessartite-almandine, typical of gondites and pegmatite veins; and 5) alman dine-grossular, occurring in high-pressure metamorphic rocks. According to the distribution of specific garnet-bearing rocks in the crystalline baseme nt of Baikal, two regions are distinguished as sourcelands of terrigenous m aterial: Ol'khon region and Svyatoi Nos Peninsula. Taking into account the principal role of eolic processes in transportation of elastic pebbles, it is established that the predominant winds over the last 200 ka were of sout hwestern and eastern directions.