ENVIRONMENTAL CONDITIONS OF FLOODPLAIN SEDIMENTATION DURING THE LITTLE ACE AGE IN THE DELTA ZONE OF THE TSUKANOVKA RIVER (SOUTHWESTERN PRIMORYE)

This paper examines the development of the Tsukanovka River floodplain in its deltaic zone during the Little Ice Age. The chronological reference of natural events was made on the basis of correlation with the published data. The paleoclimatic events were estimated by the sum of broad-leaved pollen. There were three periods of warming (XIII, XVI, and XVIII centuries), a cool period (XIV century), and three periods of cooling (XV, XVII, and XIX centuries) during the Little Ice Age in southwestern Primorye. Warming played a major role in vegetation changes, while moisture availability played a major role in the development of floodplain landscapes. Deposition of floodplain sediments in the deltaic zone of the Tsukanovka River began at the end of the Medieval Warm Period-beginning of the Little Ice Age. Floods of varying magnitude and duration played a major role in sedimentation. Summer floods were driven by typhoons, tropical and extratropical cyclones. The magnitude of spring floods depended on the amount of winter precipitation. The frequency of summer precipitation increased mainly during cold phases of the Little Ice Age, when the East Asian summer monsoon was active. During warming, winter precipitation increased due to weakening of the winter phase of the East Asian monsoon. The frequency of summer storm precipitation was the highest in the XIV-XV centuries, XVII century and in the late XVIII century - early XIX century. The floodplain experienced significant spring floods in the late XIII century, in the XVI century and in the middle of the XVIII century. Abundant and prolonged floods and freshets were the leading factor in the formation of the lithogenic base of floodplain landscapes.