Holocene climate evolution: information from the Lacustrine–Fluvial sediment in North China

Abstract

We reconstructed the Holocene climate in the study area using data from a BZ section in the Baiyangdian paleo-lake. Samples were analyzed for multiple proxies for climate conditions, including grain size, magnetic susceptibility (MS), and carbonate content, which were combined with accelerator mass spectrometry (AMS) 14C data. The results show that from 10.0 to 6.3 kyr BP, the study area experienced an interval of increasing precipitation and rising water level at Lake Baiyangdian. For a very short period,\u2009~\u20098.4 kyr BP, the extent of the lake reached the sampling point. The climate during this stage was relatively humid. The water level dropped abruptly at 6.5 kyr BP as a result of a weak monsoon event. From 6.3 to 2.9 kyr BP the climate became humid once again. The continuous lacustrine sediment of the strata indicated that the water level of Lake Baiyangdian expanded rapidly during this period and reached the sampling point. After 2.9 kyr BP, the climate in the region changed again from humid to dry. The abrupt increase in MS after ~1 kyr BP (993 AD) is consistent with records of human activities in local chronicles, which indicates that the environment in the study area was influenced by human activities. Through a comparison of the BZ section and the East Asian summer monsoon (EASM) records, we found that precipitation in the study area was controlled by the EASM. A series of cold Holocene events were clearly recorded by the sediment in the BZ section, and these events are synchronous with the North Atlantic ice-rafting events (IRD). The connection between the characteristics of the BZ section and the EASM and IRD indicate that climate evolution in the study area was strongly affected by EASM and IRD.