Tropical Climate Variability During Interglacials of the Last 300,000 Years: Evaluation of High-Resolution LA-ICP-MS Trace-Element Data

Past interglacial periods with climatic conditions comparable to those of today, but shaped by different orbital configurations and greenhouse gas concentrations, provide valuable insights into natural climate variability. This project aims to address a major data gap in the highly heterogeneous tropics by developing a long, continuous, and high-resolution multi-proxy stalagmite record from the well-monitored Cueva Larga in Puerto Rico1. High-precision 230Th/U dating shows that this stalagmite archive enables a comprehensive comparison of interglacial periods over the last 300,000 years, covering MIS 1, MIS 5 (127 ka to 54 ka), MIS 7 (255 ka to 190 ka) and MIS 9 (310 ka to 280 ka).We present multiple high-resolution time series of trace elements (Mg, P, Cu, Sr, Ba, U) obtained using LA-ICP-MS. Because the archive integrates data from several stalagmites, it is essential to account for in-cave variability, including effects of prior carbonate precipitation and CO2 exchange. These processes are evaluated through parallel growth phases of the stalagmites and in combination with stable carbon and oxygen isotopes. Here, we focus on the rigorous evaluation of the LA-ICP-MS trace-element records to ensure a reliable and reproducible reconstruction at decadal resolution.Time-series analyses of this new composite multi-proxy dataset are expected to enhance both qualitative and quantitative understanding of interglacial environmental change, particularly with respect to precipitation intensity and variability. Ultimately, this work will improve assessments of tropical climate sensitivity to external forcing and provide critical context for evaluating the magnitude of ongoing climate change relative to natural variability. 1 Warken et al. (2020). Persistent Link Between Caribbean Precipitation and Atlantic Ocean Circulation During the Last Glacial Revealed by a Speleothem Record from Puerto Rico. Paleoceanography and Paleoclimatology, Vol. 35, No. 11, https://doi.org/10.1029/2020PA003944