Paleoenvironments indicated by the fossil mammalian assemblages from red clay-loess sequence in the Chinese Loess Plateau since 8.0 Ma B.P.

Abstract

Information from eleven profiles of eolian earthy red silty clay and loess of the middle of the Late Miocene to Holocene age have been studied and correlated. A complete summary profile with projected isotopic ages and fossil-bearing beds has been assembled. The profile is subdivided into 12 stratigraphic units proceeding from the lower (older) to the upper (younger) one. The character of mammalian assemblages contained in each unit was analyzed and the corresponding paleo-climatic environments were deduced. The environmental character of each period and the change from the middle of the Late Miocene at about 8.0 Ma B.P. up to the Holocene progressed from the hot semiarid and semi-moist, warmer-moist, warm-moister of the Late Miocene. To slightly less warm moist, cool-dry, slight-warmer-moister of the Pliocene; later the cool to cold dry periods alternated frequently with the mild semiarid and semi-moist periods of the Quaternary. Vegetation progressed from the grasslands with sparse woods, wooded shrub-grasslands and subtropical forest-grasslands of the Late Miocene age to sparse grasslands and dry grasslands of the Pliocene; and to sparse grasslands, dry grasslands and tundras of the Quaternary. The climate changes in the Neogene were of low-amplitute in a generally warm-humid background. Those of the Quaternary were of higher amplitude with a longer phase. Cool or cold dry and slightly warm semiarid and semi-moist climates alternated on a generally cool-dry background. The tendency since the start of the Quaternary was the change to more northern and western shift in the Loess Plateau, with progressively cooler and dryer conditions. The dramatic uplift of the Qinghai-Xizang (Tibet) Plateau and the forming and expansion of the Arctic ice sheet might be the main reasons of the more pronounced changes in the Quaternary.

Occurrences of warm-adapted mammals in north China over the Quaternary Period and their paleo-environmental significance

“…elements, such as Macaca and Sivapanthera [11] . The warm-adapted mammals dominated assemblage of the Gongwangling Fauna conflicted with the result from the study on the non-biological indices which indicated that the L15 should be deposited under dry and cold conditions [68] . It is worth mentioning that all the examples of the warm-adapted mammals preserved in loess are located on the edge of the Loess Plateau, especially the Gongwangling Fauna is near the transitional zone.…”

Pollen evidence from Baode of the northern Loess Plateau of China and strong East Asian summer monsoons during the Early Pliocene

“…The Renjiapo fauna at 3.4 Ma mainly are composed of even-toed ungulates, with a predominance of hypsodont animals. Their signatures represent grassland expansion and a cool-dry climate [37,38].…”

Environmental indicators from comparison of sporopollen in early Pleistocene lacustrine sediments from different climatic zones

“…Vegetation shifted at the same time to grassland or desert steppe, indicating a cold and dry climate [31]. Other fossils in various locations on the CLP indicate that vegetation shifted from open forest-steppe in the Pliocene to shrub steppe in the early Pleistocene, and then later into steppe or desert [32]. All indicators show that climate was more humid in the early Pleistocene than in the late Pleistocene, although was somewhat drier than that of the Pliocene.…”