Carbon isotope evidence of last glacial climate variations in the tropical NW Leizhou Peninsula, South China

Abstract

Bulk organic d 13 C values of sediment sequences are commonly used to indicate past climatic changes, although the causes and mechanisms leading to the observed organic carbon isotope responses are presently not fully understood. Based on two sedimentary sequences, namely a peat profile and a fluvial and swamp sequence from the tropical NW Leizhou Peninsula in South China, we interpret more negative bulk organic d 13 C values to suggest wetter and warmer conditions, implying a stronger East Asian (EA) summer monsoon, and less negative d 13 C values to indicate drier and cooler conditions, reflecting a weakening of the EA summer monsoon. A warm and wet period occurred between c. 48.0 and 28.0 cal. ka BP. In the study region, a climate shift occurred at c. 22.0 (or 20.0) cal. ka BP, and the driest and coldest period occurred between c. 19.0 and 16.0 cal. ka BP. After c. 12.0 cal. ka BP, the climate changed towards wetter and warmer conditions. Several possible millennial-scale dry and cold oscillations characterized possibly by C4 plants, or by more positive organic d 13 C values during the period when C3 plants dominated, are cautiously and tentatively interpreted as showing a similarity with Heinrich events and other cold millennial-scale oscillations evidenced from a Greenland ice core and Chinese stalagmite. We demonstrate that bulk organic d 13 C records of sedimentary sequences in the study region have potential for indicating the changes in vegetation composition that were closely associated with climate variation during the last glacial period.

Groundwater Recharge and Hydrogeochemical Evolution in Leizhou Peninsula, China

“…The Leizhou Peninsula is located at the northern boundary of the Tropic of Capricorn in South China (Figure 1). The precipitation in this region is strongly influenced by the East Asian summer monsoon and, to a lesser extent, by the Indian summer monsoon [17]. This area, along with the entire South China Sea, provides the moisture supply for the summer monsoon rainfall throughout the eastern part of China from June to August and has a rich average annual rainfall of 1400 mm, with approximately 75% of the precipitation falling during this rainy season.…”

“…The Leizhou Peninsula is an ideal site for investigating volcanic hydrogeological environments [17]. A recent study indicated that groundwater contains low total dissolved solids (TDS) (ranging from 40 to 550 mg/L), is weakly acidic, and has a low pH between 4 and 7 [18].…”

A new method of carbon budget analysis with application to present and paleo atmospheric concentration data sets

“…Although studies of δ 13 C for individual peatlands have been conducted (e.g. [1,2,8,18,27,28,29]), we propose that a constant δ 13 C value is adequate for a first-order understanding of carbon isotope composition of peatlands and sufficient for showing the benefit of the method. We use the mean 13 C from these studies, −25 .…”

Late Holocene stable isotopic (δ13C and δ15N) records of lacustrine organic matter in Guangdong Province, south China, and their palaeoenvironmental implications

“…Based on two peat successions obtained in the Zhanjiang district in western WGDP, the evolutionary history of the ASM in the past c. 50 000 years has been reconstructed using organic carbon isotopes (Zhong et al . ), pollen data (Xue et al . ) and the charcoal record (Xue et al .…”

“…Several studies have been performed on the late Late Pleistocene climatic changes in WGDP. Based on two peat successions obtained in the Zhanjiang district in western WGDP, the evolutionary history of the ASM in the past c. 50 000 years has been reconstructed using organic carbon isotopes (Zhong et al 2012), pollen data (Xue et al 2015a) and the charcoal record (Xue et al 2015b). Yancheva et al (2007) reconstructed the strength of the Asian winter monsoon winds over the past 16 000 years using the magnetic properties and the titanium content of sediments from Lake Huguang in the Leizhou Peninsula.…”