Implications of stalagmite density for past climate change: An example from stalagmite growth during the last deglaciation from Wanxiang Cave, western Loess Plateau

Abstract

The density of a stalagmite (WX42A) from Wanxiang Cave, Wudu County, Gansu Province, China, in the western margin of the Asian summer monsoon region, presents regular fluctuations in different deposition periods during the last deglaciation. Over long timescales, high-precision 230 Th dating and high-resolution stalagmite density data indicate that the density-time series between 17644 a BP and 12758 a BP is quite similar to the stalagmite δ 18 O record which reflects Asian monsoon intensity. Strengthening/weakening (lighter/heavier stalagmite δ 18 O values) of the Asian monsoon is accompanied by increase/decrease in stalagmite density. Over short timescales, decrease in stalagmite density correlates to monsoon-retreat events such as the Inter-Allerød Cold Period (IACP), Older Dryas (OD) and Inter-Bølling Cold Period (IBCP). Generally, this kind of decrease in stalagmite density reflects precipitation decrease with weakening of the Asian monsoon, which in turn slows cave dripwater rate and decreases crystal nuclei, leading to enlargement of calcite crystals, weakened biological activity and decreased soil pCO 2 which increases the abundance of impure detrital materials in stalagmites. However, during the period of large amplitude reduction of precipitation and biological activity which resulted from extreme monsoon-retreat events, temperature variation would dominate fluctuation of stalagmite density. For example, stalagmite density increased suddenly when temperature dropped suddenly in the north Atlantic during Heinrich event 1 (H-1). This may be caused by low seepage water temperature, more dissolved calcium carbonate, compact regular crystals forming under higher supersaturation, leading to the stalagmite increased density. Stalagmite density fluctuation sensitively recorded stalagmite growth history and environment, demonstrating that stalagmite density can be used as a proxy for paleoclimatic research. stalagmite density, Asian monsoon, climate change, Wanxiang Cave, monsoon margin Citation:Zhang D Z, Zhang P Z, Sang W C, et al. Implications of stalagmite density for past climate change: An example from stalagmite growth during the last deglaciation from Wanxiang Cave, western Loess Plateau.

Reconstructing high-resolution climate using CT scanning of unsectioned stalagmites: A case study identifying the mid-Holocene onset of the Mediterranean climate in southern Iberia

“…In a study of the East Asian Monsoon, Zhang et al (2010) demonstrated that rainfall amounts (inferred from stalagmite d 18 O) and calcite density variations (derived by conventional non-CT scanning methods) were positively correlated, which is also consistent with studies of calcite textures (Frisia, 2015;Frisia et al, 2000). By calculating stalagmite density from the measured mass of stalagmite blocks cut every 5 mm, Zhang et al (2010) achieved a resolution of 87 years. CT scanning therefore offers a novel means to produce comparable density data quickly and non-destructively, and at a considerably higher spatiotemporal resolution than is achievable using conventional density measurements.…”

“…X-ray computed tomography (CT scanning), a non-destructive technique commonly applied in medicine and also in the geosciences (Carlson et al, 2003;Ketcham and Carlson, 2001;Mees et al, 2003), uses internal three-dimensional density mapping of opaque objects to provide information about stalagmite growth axis shifts (Mickler et al, 2004) and internal porosity (Zisu et al, 2012). Moreover, CT scanning provides rapidly acquired quantitative information about stalagmite density, a variable that typically can only be obtained at low spatial resolution only through calculations based on the mass of cut stalagmite blocks (Zhang et al, 2010). Despite numerous studies using CT scanning to derive quantitative density data from sediment cores (Mees et al, 2003;Tanaka et al, 2011;Wirth et al, 2013), the technique has not previously been used to derive timeseries data from stalagmites.…”

“…These factors directly control water flow dynamics, and consequently drip-water saturation state (with respect to calcium carbonate) that is the predominant determinant of stalagmite density (Dreybrodt, 2008;Frisia et al, 2000;Zhang et al, 2010). In addition, cave ventilation regimes also complicate it by affecting the intensity of CO 2 degassing from drip-water entering a cave (Boch et al, 2011;Mattey et al, 2010).…”

“…In addition, cave ventilation regimes also complicate it by affecting the intensity of CO 2 degassing from drip-water entering a cave (Boch et al, 2011;Mattey et al, 2010). However, because environmental change during stalagmite growth drives calcite density variability, stalagmite calcite density is interpretable in terms of climate (Zhang et al, 2010). In a study of the East Asian Monsoon, Zhang et al (2010) demonstrated that rainfall amounts (inferred from stalagmite d 18 O) and calcite density variations (derived by conventional non-CT scanning methods) were positively correlated, which is also consistent with studies of calcite textures (Frisia, 2015;Frisia et al, 2000).…”

“…However, because environmental change during stalagmite growth drives calcite density variability, stalagmite calcite density is interpretable in terms of climate (Zhang et al, 2010). In a study of the East Asian Monsoon, Zhang et al (2010) demonstrated that rainfall amounts (inferred from stalagmite d 18 O) and calcite density variations (derived by conventional non-CT scanning methods) were positively correlated, which is also consistent with studies of calcite textures (Frisia, 2015;Frisia et al, 2000). By calculating stalagmite density from the measured mass of stalagmite blocks cut every 5 mm, Zhang et al (2010) achieved a resolution of 87 years.…”