A reactive transport approach to modeling cave seepage water chemistry II: Elemental signatures

Oster, Jessica L.; Covey, Aaron K.; Lawrence, C. R.; Giannetta, Max G.; Druhan, Jennifer L.

doi:10.1016/j.gca.2021.06.040

Cited by 10 publications

(9 citation statements)

References 43 publications

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“…If PCP occurs upstream of the cave drip site, the Mg/Ca and Sr/Ca will increase in the dripwater as Ca is preferentially lost from solution during PCP. Calcite precipitating from these waters on the speleothem surface will also be similarly co-enriched in Mg and Sr. PCP can occur when infiltration rates are low, drip intervals are long, or when cave CO2 is low; these processes and combinations of processes can differ depending on the individual dripwater flow pathways feeding a stalagmite 30,35,37,49 .…”

Section: Stalagmite δmentioning

confidence: 99%

“…Notably, bedrock dissolution, and thus Mg, Sr, and Ca concentrations, can be influenced by soil CO2 and groundwater infiltration rates 37 .The measured Mg/Ca and Sr/Ca values for Abadi Cave bedrock and estimated partition coefficients 33,34,50,51 are used to calculate approximate Mg/Ca and Sr/Ca values for stalagmite calcite sourced entirely from the host rock, defined here as bedrocksp (see Supplementary Information; Supplementary Fig. 3).…”

Section: Stalagmite δmentioning

confidence: 99%

“…34). Each regression is slightly offset, indicating that the Mg and Sr content of individual stalagmites may be influenced by distinct dripwater flowpathways 37 . The average log-log slope of Sulawesi Mg/Ca and Sr/Ca data is 0.84 ±0.13.…”

Section: Stalagmite δmentioning

confidence: 99%

“…PCP is also controlled by the CO2 content of air in the cave and void spaces (soil-karst processes) 28,30,31 . Individual drip pathways and flow rates can determine which of these processes prevail for site specific drip waters 35,37,47 . Rainfall amount and infiltration through the karst influence the amount of void space where PCP can occur.…”

Section: Stalagmite δmentioning

confidence: 99%

“…Because of the preference for Ca to precipitate out of solution during PCP, coherency among measured stalagmite Mg/Sr 27 and the slope of the ln(Sr/Ca) and ln(Mg/Ca) regression line serve as a means to test for the occurrence of PCP 33,34 . It has also been shown that concentrations of Mg and Sr may be influenced by water-rock and water-soil contact times resulting in a covariation of Mg/Ca and Sr/Ca 30,32,[35][36][37] . Because of the aforementioned processes, it is necessary to use multiple speleothems and a multi-proxy approach to produce accurate palaeohydrological records.…”

Section: Introductionmentioning

confidence: 99%

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Validation of glacial-interglacial rainfall variations in southwest Sulawesi using Mg/Ca and δ18O in speleothems

Kimbrough¹,

Gagan²,

Dunbar³

et al. 2023

Preprint

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Speleothem δ18O is widely used as a proxy for rainfall amount in the tropics on glacial-interglacial to interannual scales. However, uncertainties in the interpretation of this renowned proxy pose a vexing problem in tropical paleoclimatology. Here, we present paired measurements of Mg/Ca and δ18O for multiple stalagmites from southwest Sulawesi, Indonesia, that that confirm changes in rainfall amount across ice age terminations. Collectively, the stalagmites span two glacial-interglacial transitions from 380 to 330 ky BP and 230 to 170 ky BP. Mg/Ca in our slow-growing stalagmites is affected by karst infiltration rates and prior calcite precipitation, making it a good proxy for changes in local rainfall. When paired, Mg/Ca and δ18O corroborate prominent shifts from drier glacials to wetter interglacials in the core of the Australasian monsoon domain. Deviations between the two proxies may reveal concurrent changes in rainfall amount and moisture-transport pathways indicative of regional monsoon circulation.

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Section: Stalagmite δmentioning

confidence: 99%