Scientific REpoRTS | (2018) 8:4551 | DOI:10.1038/s41598-018-22839-z
An optimized chronology for a
stalagmite using seasonal trace
element cycles from Shihua Cave,
Beijing, North China
, Andy Baker
, Christopher E. Marjo
, Wuhui Duan
, Xianglei Li
, Katie Coleborn
, Rabeya Akter
, Ming Tan
& Gurinder Nagra
Stalagmites play an important role in paleoclimatic reconstructions from seasonal to orbital time scales
Th-dating can provide an accurate absolute age. Additionally, seasonal trace element and optical
layers can provide a precise age. We analyzed the seasonal variability of multiple trace elements on
a stalagmite (XMG) in Shihua Cave, Beijing and compared them with results from laminae counting.
The results show that (1) the polished section of the topmost part of XMG has obvious bi-optical layers
under a conventional transmission microscope, however, laminae are not observed using this method
in the rest of the sample, and (2) The variations of P/Ca, Sr/Ca, Ba/Ca, U/Ca and Mg/Ca show seasonal
cycles throughout the sample. The PC1 in the Principal Component Analysis (PCA) of ve trace elements
represents the annual cycle. This stalagmite was deposited over 150 ± 1 years through PC1 peak
counting. This result corresponds well with the annual layers and U-Th dating. Trace element cyclicity
of PC1 can increase the accuracy of stalagmite dating, especially in the absence of obvious laminae and
are a powerful method to identify seasonal changes in a strongly contrasting wet-dry monsoon climate
Stalagmites are increasingly important for paleoclimatic reconstruction because of their wide distribution, mul-
tiple proxies, high resolution and precise dating. Especially, the timescale over which it is possible to build paleo-
climate reconstructions can be from seasonal to orbital timescales
. Trace element variations of stalagmites have
been used to explore sub-annual climatic and cave environmental signals and for chronology building
the development of in-situ measurements, high resolution sampling methods such as secondary ion mass spec-
, laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS)
micro-X-ray uorescence imaging
have been used to measure trace elements to get annual and even seasonal
signals, which can be used to explore sub-annual climatic, cave environmental signals and chronology building.
Because of a seasonally changing climate, such as wet and dry seasons, and associated seasonal changes in
hydrological or ventilation conditions within the cave
, some stalagmites show obvious annual laminae under
visible-light or UV-uorescence, which can be used to obtain an accurate age by counting laminae and compar-
ison to radiometric methods
. Some stalagmites fail to exhibit visible or UV-uorescence laminae, or they
lack laminae in some sections, but the same stalagmites may show cycles in their trace element composition
e impact of seasonality on speleothems would be expected to be strong enough to generate annual chemical
variations, whether or not conventional growth laminae are visible
. In 2009, Smith et al.
built an objective
and automated technique for establishing trace element chronologies analysing individual elements in stalagmites
from two Alpine caves. en Nagra et al.
exploited seasonal variations in trace elements to construct chronolo-
gies in a Mediterranean climate employing principal components analysis (PCA). ese studies imply that cyclic-
ity of trace elements can be used to obtain an accurate age for non-laminated speleothem samples.
Faculty of Environmental Economics, Shanxi University of Finance & Economics, Taiyuan, 030006, China.
Connected Waters Initiative Research Centre, UNSW Sydney, Sydney, NSW, 2052, Australia.
Analytical Centre, UNSW Sydney, Sydney, NSW, 2052, Australia.
Key Laboratory of Cenozoic Geology and
Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, 100029, Beijing, China.
of Global Environmental Change, Xi’an Jiaotong University, Xi’an, 710049, China. Correspondence and requests for
materials should be addressed to F.B. (email: firstname.lastname@example.org)
Received: 12 December 2017
Accepted: 28 February 2018
Published: xx xx xxxx