@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 {2844,
	title = {A 7000-year history of coastal environmental changes from Mexico{\textquoteright}s Pacific coast: A multi-proxy record from Laguna Mitla, Guerrero},
	journal = {The Holocene},
	volume = {27},
	year = {2017},
	month = {Sep-08-2017},
	pages = {1214 - 1226},
	abstract = {The lack of multi-millennial multi-proxy paleoenvironmental reconstructions from Mexico{\textquoteright}s Pacific coast has limited our understanding of the regional response to climate change and sea-level rise. A 479-cm core covering the last 6900 years was extracted from Laguna Mitla in the state of Guerrero on Mexico{\textquoteright}s Pacific coast. Beginning as a Rhizophora-dominated salt pan ~6900 yr BP, at ~6500 yr BP, the site transitioned to a mangrove swamp dominated by Laguncularia, which lasted about 300 years. The beach barrier formed from ~6200 to 5200 yr BP, during which time, the site existed as an intermittently sheltered bay, the result of large, rapid changes in wave energy associated with the shifting barrier location and changes in stability. After the beach barrier was stabilized at ~5200 yr BP, water level at the coring site became a function of precipitation rather than sea level. Since that time, deposition has alternated between peat, laid down in a mangrove swamp, and clay intervals characterized by high concentrations of titanium and a predominantly regional pollen signal, representing open-water lagoon phases. Seven periods of increased water level, varying in duration, occurred during the backbarrier period, with El Ni{\~n}o-Southern Oscillation (ENSO) likely the main climatic mechanism causing these periodic shifts in the paleo-precipitation levels. We suggest that the deepest water levels detected over the last ~3200 years correlate with periods of increased ENSO activity. The spatial distribution of tropical cyclone rainfall, which represents a significant percentage of total annual precipitation along Mexico{\textquoteright}s Pacific coast, may explain the inconsistencies between our record and paleoclimatic records from Mexico{\textquoteright}s interior, but more work is needed to test this hypothesis.},
	keywords = {El Nino-Southern Oscillation, Laguna Mitla, mangroves, Pacific coast of Mexico, Paleoclimate, paleoenvironmental reconstruction, pollen, Sediment, tropical cyclones, x-ray fluorescence},
	issn = {0959-6836},
	doi = {10.1177/0959683616687379},
	url = {http://journals.sagepub.com/doi/10.1177/0959683616687379},
	author = {Bianchette, Thomas A and McCloskey, Terrence A and Liu, Kam-biu}
}
