Iron sulfides in sediments of glacial lakes of the upper Kolyma region

Abstract

Iron sulfides are common in the sediments of glacier lakes of the Magadan region -Gryazevoe (61°08’21” N, 152°19’57” E), Nalimnoe (61°07’41” N, 152°20’8” E), Sosednee (62°03’29” N, 149°3122” E), Sapog (63°29’9” N, 147°50’41” E), Vodorazdel’noe (63°44’8” N, 148°13’4” E), Ui (63°49’31” N, 147°53’21” E) and others. Most of the lakes were formed at the end of the Late Pleistocene or at the beginning of the Early Holocene. Sulfides occur in the spheroid forms with a framboidal structure, dusty clusters, and individual crystals. Sometimes sulfides fill up the diatom valves. The size of framboids does not exceed 100 µm. Sulfides have pyrite, greigite and pyrrhotite compositions. They are distributed unevenly in sections. Greigite and pyrrhotite are distinguished by their magnetic characteristics.