Paleontological monument of nature “Mamontova Gora” exposure (Yakutia, Eastern Siberia, Russia)

Abstract

The Mamontova Gora (“Mammoth Mountain”) exposure is the Neogene – Pleistocene key section of Siberia. This outcrop is located in the lower reaches of the Aldan River, 325 km above its mouth and extends for almost 12 km. It consists of an 80-meter structural plateau (80-meter terrace), 50- and 30-meter alluvial terraces. Sediments from the Middle Miocene (16-10 Ma) to the Upper Pleistocene are exposed on the 80-meter terrace. The basement of the 50-meter terrace is composed of Middle Miocene sediments, overlain by Pleistocene sediments. On a younger 30 m terrace, the deposits are dated from the Upper Pliocene to the Upper Pleistocene. The Mamontova Gora outcrop is one of the richest localities of the Neogene flora of Eurasia. There are numerous finds of remains of Miocene evergreen and thermophilic plants (tree stumps, leaf imprints, cones, nuts, seeds). More than 250 genera of fossil plants have been found on Mamontova Gora. This outcrop is also well known to paleontologists due to the abundance of bone remains of mammals of the Middle Pleistocene (early type mammoth, eastern horse, broad-fronted moose, long-horned bison) and Late Pleistocene (representatives of the mammoth fauna: woolly mammoth, woolly rhinoceros, Lena horse, reindeer, saiga-antelope, steppe bison, Arctic fox, wolverine, cave lion, etc.). It was revealed that the ancient frozen sediments on the Mamontova Gora outcrop abound with viable microorganisms and traces of their vital activity. A strain of microbe Bacillus sp. was isolated from ~ 2 - 3 Ma permafrost layers of this outcrop. A large group of microorganisms including fungi was isolated from the ancient ice wedge. Pleistocene permafrost deposits contain invertase, urease, catalase and dehydrogenase enzimes. Mamontova Gora is a unique geological object in Russia. By the decree of the Council of Ministers of the Yakutia Autonomous Soviet Socialist Republic of 18.02.1987 No. 56 Mamontova Gora was given the status of a “natural monument” and a specially protected natural area of regional significance. The article presents the main results of studies of ancient flora and faunas of Mamontova Gora.