Мезозойско-кайнозойские поверхности выравнивания, коррелятные отложения и проблемы бокситоносности Предбайкальского прогиба

Аннотация

The Cenozoic Fore-Baikalian Trough consists of a series of foredeeps which border the Baikalian mountain area at the West and correspond to depressions of the presentday topography. Geological-geomorphological studies of the depressions revealed 4 polygenetic planation surfaces of different age, the latter being defined on weathering crusts and correlative sediments as Early Mesozoic (Trias-Early Jurassic), Cretaceous-Paleogenic, Miocene-Middle Pliocene and Late Pliocene respectively. At elevated margins of the Fore-Baikalian trough the Cretaceous-Paleogenic surface becomes polygenetic one and can be divided into three separate levels with interjacent slopes or zones of dissected topography. The lower intermediate and upper levels are dated Late Cretaceous, Late Paleocene- Early Eocene and Late Eocene-Early Oligocene respectively. Some surfaces of lower rank (e. g. Pleistocene pediments, glacises and terraces) have been also studied. The Cretaceous-Paleogenic polygenetic surface considered to be the most prospective with regard to lateritic bauxites, especially hollows and ancient valleys at the upper and middle levels. Criteria of the bauxite prospects are discussed in connection with topographic features of the territory and some recommendations have been made for search of bauxites of relict (lateritic), sentimental and fissure-karstic types.