@article {bianchette_machine_2023,
	title = {Machine learning based anomaly detection for sedimentological data: Application to a Holocene multi-proxy paleoenvironmental reconstruction from Laguna Boquita, Jalisco, Mexico},
	journal = {Marine Geology},
	volume = {464},
	year = {2023},
	month = {08/2023},
	pages = {107125},
	abstract = {Paleoenvironmental reconstructions are critical to determine past climatological and hydrological conditions, such as sea-level rise (SLR) and extreme events including hurricanes and tsunamis. While established quantitative methods, such as principal components analysis and discriminant analysis, have effectively aided reconstructions by demarcating stratigraphic zones, they suffer from limitations due to the underlying assumptions (linearity, normality). Here, we introduce the machine learning technique anomaly detection for sedimentological reconstructions, capable of objectively pinpointing events (anomalies) in sediment cores. We tested this technique on five sediment cores extracted from Laguna Boquita, located along the Pacific coast of Mexico. Each core was subjected to high resolution loss-on-ignition, while the most representative core (core 1) was deemed the training core and scanned with a handheld XRF unit. In general, the sediment cores were dominated by thick units of peat and/or clay, and most cores contained sand layers. This reconstruction represents many environmental settings, ranging from a sandy terrestrial environment (\~{}6830-~\~{}~6370~cal~yr BP), organic-rich wetland (\~{}6370-~\~{}~5170~cal~yr BP), and clastic-rich backbarrier lagoon (\~{}5170~cal~yr BP to present). The anomaly detection technique proved effective in marking many events, including marine transgression, evidence of SLR, transitions separating dominant depositional environments, and, perhaps most notably, a faded blue clay layer with minimal LOI variability that may represent a shift in backbarrier water level. The anomaly detection also registered anomalies when events were not visually distinct nor present in the LOI datasets (false positives), which represent sediment core sections that require further investigation with multiple proxies. However, anomaly detection failed to register anomalies in certain core sections that should have registered as events due to their distinct nature. Future efforts will look to improve anomaly detection by choosing different train cores and adding additional proxy datasets.},
	keywords = {Loss-on-ignition, Machine learning, Paleoclimate, peat, Radiocarbon dating, x-ray fluorescence},
	issn = {0025-3227},
	doi = {10.1016/j.margeo.2023.107125},
	url = {https://www.sciencedirect.com/science/article/pii/S0025322723001378},
	author = {Bianchette, Thomas A. and Pandey, Vijitashwa and Mollan, Calahan and Hall, Sawyer and McCloskey, Terrence A. and Liu, Kam-biu}
}
@article {2962,
	title = {A 4000-year paleoenvironmental reconstruction and extreme event record from Laguna Nuxco, Guerrero, Mexico},
	journal = {Palaeogeography, Palaeoclimatology, Palaeoecology},
	volume = {594},
	year = {2022},
	month = {Jan-05-2022},
	pages = {110933},
	abstract = {Reconstructing paleoenvironments on Mexico{\textquoteright}s Pacific coast is crucial to determine past climate conditions and natural hazard periodicities, vital for predicting future activities. Two sediment cores extracted from Laguna Nuxco, a coastal lagoon in Guerrero, were analyzed to provide a 4000-year paleoenvironmental record. Sediments dominated by shelly clay with low water and organic content, high carbonate content, low Ti/Ca ratio and the presence of Anomalocardia subrugosa suggest that a sheltered bay existed from ~4000{\textendash}~1300 cal yr BP. During this stage, intermittent beach ridge gaps facilitated the deposition of storm-induced shell deposits, likely from tropical cyclones. Frequent thick shell hash deposition toward the top of the lithologic unit indicates heightened storminess likely from an increase in ENSO activity. An intense tropical cyclone, or perhaps multiple storms during an active period deposited a thick shell hash layer at ~1500 cal yr BP, which helped strengthen the beach ridge system and lead to the modern lagoon phase (~1300 cal yr BP to present), as suggested by the presence of Mytella sp. A more isolated lagoon with significant terrestrial sediment input was reflected by the predominance of lagoonal clay with decreased shell and carbonate contents, increased water and organic contents, and increased Ti/Ca ratio. A quiet period with lower tropical cyclone activity occurred from 1300 to 800 cal yr BP and from 300 cal yr BP to the present, as inferred from no or relatively few shell hash deposits, respectively. A period of hyperactivity occurred from 800 to 300 cal yr BP, as evidenced by seven shell hash layers. During the modern lagoon phase, shell hash deposition was not caused by marine inundation processes, but rather {\textquoteleft}blowout{\textquoteright} events driven by intense precipitation during heightened ENSO activity. Findings shed additional light on Late Holocene environmental changes in a dynamic coastal zone related to regional controlling factors such as tropical cyclone activity, ENSO, and beach ridge development.},
	issn = {00310182},
	doi = {10.1016/j.palaeo.2022.110933},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0031018222001031},
	author = {Bianchette, Thomas A. and Liu, Kam-biu and McCloskey, Terrence A.}
}
