Abstract
Varve counts with AMS 14C, 137Cs and 210Pb dating of sediments (0–900 cm) from Erlongwan Maar Lake, NE China were used to establish a high-resolution chronology series for the late Quaternary. Dry density, total organic carbon (TOC) content, total nitrogen (TN) content, TOC/TN ratios and stable organic carbon isotope (δ 13Corg) ratios were continuously analyzed on this sediment profile. On the basis of lithological characters, sporo-pollen assemblages and geochemical analyses, we identified 6 climate stages within the last 14 ka BP. The time before the Holocene (14-11.4 ka BP) represents a higher-order oscillation climatic transitional period (I). The entire Holocene climate development (from 11.4 ka BP to present) exhibited an increasing temperature trend, although there were cold and warm alternations (II–VI). The periods included were: II (11.4-9.05 ka BP) warm-wet stage, III (9.05-7.4 ka BP) cold and warm fluctuation stage, IV (7.4-4.2 ka BP) smoothly warming climate stage, V (4.2-1.67 ka BP) climate optimum stage, and VI (from 1.67 ka BP to present) cool and drier stage. Each climate stage began with a warming event and ended with an abrupt cooling event. This climate change cycle had unequal time spaces that were progressively shorter over time. Several abrupt climate shifts occurred at about 9.4-9.05, 8.5-8.2, 7.8-7.4, 4.6-4.2, 3.7-3.25, 2-1.67 and 0.3-0.03 ka BP. Thus, it can be seen that the climate has been warming since 1920 AD, which indicates a new climate stage.
Highlights
The regularity and tendencies of climate change are hot debated issues
Deciphering climate change mechanisms from the last glacial maximum (LGM) to the latest 20 ka BP is a principal task in the science of global climate change [1]
We present a high-resolution chronology based on the precise varve counting from Erlongwan Maar Lake, using a multi-proxy record, reconstruct climate evolution during the last 14 ka BP in this region
Summary
Erlongwan Maar Lake (42°18.1′N, 126°21.4′E; Figure 1) is situated in the Long Gang Volcanic Field (LGVF) in the Jilin Province, NE China [25]. Maximum water depth in the lake is 33 m (measured in 2009), and the lake surface covers an area of 0.3 km. Maximum water depth in the lake is 33 m (measured in 2009), and the lake surface covers an area of 0.3 km2 It is a water-filled volcanic crater of explosive origin that formed in the mid-late Early Pleistocene, and is surrounded by basalts, basaltic volcanic pyroclastic rocks and cinder. During a joint drilling field trip with the Institute of Geology and Geophysics (IGG), Chinese Academy of Sciences, and the GeoForschungsZentrum (GFZ) Potsdam (Germany) in 2001, two long undisturbed-continuous sediment cores were recovered from Erlongwan Maar Lake. Sediment samples for dry density (at intervals of 1 cm), geochemical analyses (at intervals of 4 cm) and thin sections (120 mm×35 mm) were taken from the composite profile 0–900 cm. All sampling and analyses were carried out in the laboratories of GFZ-Potsdam and IGG-CAS
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