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Exploring Laser Induced Breakdown Spectroscopy for Environmental Reconstruction with Mytilus californianus

Session: Timestamped Biomineralized Structures in Coastal Environmental Monitoring and Cultural Research

Presenting Author:

Alexandria Firenzi

Author:

Firenzi, Alexandria Marie¹

(1) Anthropology, University of Nevada, Reno, Reno, Nevada, USA,

Abstract:

Reconstructing past coastal environments and seasonal resource use is central to paleoenvironmental and archaeological research. In a pilot study I investigate the use of Laser-Induced Breakdown Spectroscopy (LIBS) for high-resolution elemental (Mg/Ca) analysis of modern and archaeological California mussel (Mytilus californianus) shells as proxies for environmental variability and seasonality. High-resolution Mg/Ca elemental mapping and line scans were conducted at the Leibniz-Zentrum für Archäologie (LEIZA) in Mainz, Germany. Modern specimens, collected between 2015 and 2019 near archaeological sites CA-SRI-19 and CA-SRI-138 on Santa Rosa Island (SRI) of California’s northern Channel Islands, provide a comparative baseline with known temperature data for method calibration. Two LIBS-based approaches were tested: (1) 30 µm Mg/Ca line scans along inner calcitic growth bands to enable ontogenetic de-trending using sclerochronological methods, and (2) ~60 µm elemental mapping of outer calcite layers to support targeted seasonal sea surface temperature reconstructions when paired with δ¹⁸O and δ¹³C isotopic sampling. The sampled modern mussel populations inhabited the upper intertidal zones of SRI, influenced by the California Current and the Southern California Countercurrent, enabling detection of distinct oceanographic signals and trends. The broader objective is to develop a reproducible analytical protocol for extracting seasonal and climatic information from archaeological shells at the two SRI locations and two adjacent mainland sites on the Pecho Coast of San Luis Obispo, California. Early results highlight the promise of LIBS for elemental imaging in carbonate archives, offering strong potential for broader application in coastal environmental and archaeological research.