@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.}
}
@article {2843,
	title = {The Effects of Tropical Cyclone-Generated Deposition on the Sustainability of the Pearl River Marsh, Louisiana: The Importance of the Geologic FrameworkPresentation_1.PPTX},
	journal = {Frontiers in Ecology and Evolution},
	volume = {6},
	year = {2018},
	month = {Aug-11-2019},
	abstract = {Shoreline retreat is a tremendously important issue along the coast of the northern Gulf of Mexico, especially in Louisiana. Although this marine transgression results from a variety of causes, the crucial factor is the difference between marsh surface elevation and rising sea levels. In most cases, the primary cause of a marsh{\textquoteright}s inability to keep up with sea level is the lack of input of inorganic material. Although tropical cyclones provide an important source of such sediment, little effort has been made to determine the point of origin of the deposited material. In this study we use sedimentary, geochemical and biogeochemical data to identify the bed of the Pearl River and/or Lake Borgne as the source of a ~5 cm thick clastic layer deposited on the surface of the Pearl River marsh on the Louisiana/Mississippi border. Radiochemical chronologies and sedimentary evidence indicate that this layer was associated with the passage of Hurricane Katrina in 2005. As this material would otherwise have been lost to the system, this deposition indicates a net gain to marsh surface elevation. Accretion rates, determined from 137Cs and 14C profiles and the use of the Katrina layer as a stratigraphic marker, indicate that short-term (~50 years) rates are as much as an order of magnitude higher than the long- term (1000s of years) rates. We suggest that the marsh{\textquoteright}s geologic setting in an incised river valley with steep vertical constraints and a large fluvial discharge, promotes rapid accretion rates, with rates accelerating as the sea moves inland, due to extended hydroperiods and the input of clastic material from both the marine and terrestrial sides. These rates are especially large when compared to accretion occurring in the more common open marshes fringing the Gulf that lack fluvial input. The difference is particularly large when related to marsh recovery/regrowth following the deposition of thick hurricane-generated clastic layers. Given the number of similar incised river valleys along the Gulf Coast, we believe that understanding the processes controlling marsh accretion in such environments is essential in evaluating marsh sustainability on a regional basis.},
	doi = {10.3389/fevo.2018.00179},
	url = {https://www.frontiersin.org/article/10.3389/fevo.2018.00179/full},
	author = {McCloskey, Terrence A. and Smith, Christopher G. and Liu, Kam-biu and Nelson, Paul R.}
}
@article {2804,
	title = {How Could a Freshwater Swamp Produce a Chemical Signature Characteristic of a Saltmarsh?How Could a Freshwater Swamp Produce a Chemical Signature Characteristic of a Saltmarsh?},
	journal = {ACS Earth and Space Chemistry},
	volume = {2},
	year = {2018},
	month = {Jun-01-2019},
	pages = {9 - 20},
	abstract = {Reduction{\textendash}oxidation (redox) reaction conditions, which are of great importance for the soil chemistry of coastal marshes, can be temporally dynamic. We present a transect of cores from northwest Florida wherein radical postdepositional changes in the redox regime has created atypical geochemical profiles at the bottom of the sedimentary column. The stratigraphy is consistent along the transect, consisting of, from the bottom upward, carbonate bedrock, a gray clay, an organic mud section, a dense clay layer, and an upper organic mud unit representing the current saltwater marsh. However, the geochemical signature of the lower organic mud unit suggests pervasive redox reactions, although the interval has been identified as representing a freshwater marsh, an unlikely environment for such conditions. Analyses indicate that this discrepancy results from postdepositional diagenesis driven by millennial-scale environmental parameters. Rising sea level that led to the deposition of the capping clay layer, created anaerobic conditions in the freshwater swamp interval, and isolated it hydrologically from the rest of the sediment column. The subsequent infiltration of marine water into this organic material led to sulfate reduction, the buildup of H2S and FeS, and anoxic conditions. Continued sulfidation eventually resulted in euxinic conditions, as evidenced by elevated levels of Fe, S, and especially Mo, the diagnostic marker of euxinia. Because this chemical transformation occurred long after the original deposition the geochemical signature does not reflect soil chemistry at the time of deposition and cannot be used to infer syn-depositional environmental conditions, emphasizing the importance of recognizing diagenetic processes in paleoenvironmental studies.},
	keywords = {anoxic, diagenesis, euxinic, florida, Molybdenum, reactions, redox, XRF},
	issn = {2472-3452},
	doi = {10.1021/acsearthspacechem.7b00098},
	url = {https://pubs.acs.org/doi/10.1021/acsearthspacechem.7b00098},
	author = {McCloskey, Terrence A. and Smith, Christopher G. and Liu, Kam-biu and Marot, Marci and Haller, Christian}
}
@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}
}
@article {2476,
	title = {Dynamics of marsh-mangrove ecotone since the mid-Holocene: A palynological study of mangrove encroachment and sea level rise in the Shark River Estuary, Florida},
	journal = {PLOS ONE},
	year = {2017},
	month = {Oct-03-2017},
	pages = {e0173670},
	abstract = {Sea level rise and the associated inland shift of the marsh-mangrove ecotone in south Florida have raised many scientific and management concerns in recent years. Holocene paleoecological records can provide an important baseline to shed light on the long-term dynamics of vegetation changes across this ecotone in the past, which is needed to predict the future. In this study, we present palynological, X-ray fluorescence, and loss-on ignition data from four sedimentary cores recovered from a 20-km marine-to-freshwater transect along the Shark River Estuary, southwest Everglades, to document the patterns and processes of coastal vegetation changes in response to sea level rise since the mid-Holocene. Our record indicates that freshwater marsh progressively replaced marl prairies at the Shark River Estuary between 5700 and 4400 cal yr BP. As marine transgression continued, marine influence reached the threshold necessary for mangroves to establish at the current mouth of the Shark River Slough at 3800 cal yr BP. During the next 3000 years, although sea level rise in the Western North Atlantic slowed down to 0.4 mm/yr, a spatial and temporal gradient was evident as the marsh-mangrove ecotone shifted inland by 20 km from 3800 to 800 cal yr BP, accompanied by a gradual landward replacement of freshwater marsh by mangrove forest. If sea level continues to rise at 2.33 mm/yr in the 21st century in south Florida, it is possible that marine influence will reach the threshold for mangroves to establish in the central Everglades, and we could expect a much more aggressive mangrove encroachment toward the northern and interior parts of south Florida in the next few centuries.},
	doi = {10.1371/journal.pone.0173670},
	url = {https://doi.org/10.1371/journal.pone.0173670},
	author = {Yao, Qiang and Liu, Kam-biu},
	editor = {Magar, Vanesa}
}
@article {11,
	title = {Palynological reconstruction of environmental changes in coastal wetlands of the Florida Everglades since the mid-Holocene},
	journal = {Quaternary Research},
	volume = {83},
	year = {2015},
	pages = {449-458},
	abstract = {Palynological, loss-on-ignition, and X-ray fluorescence data from a 5.25 m sediment core from a mangrove forest at the mouth of the Shark River Estuary in the southwestern Everglades National Park, Florida were used to reconstruct changes occurring in coastal wetlands since the mid-Holocene. This multi-proxy record contains the longest paleoecological history to date in the southwestern Everglades. The Shark River Estuary basin was formed ~ 5700 cal yr BP in response to increasing precipitation. Initial wetlands were frequently-burned short-hydroperiod prairies, which transitioned into long-hydroperiod prairies with sloughs in which peat deposits began to accumulate continuously about 5250 cal yr BP. Our data suggest that mangrove communities started to appear after ~ 3800 cal yr BP; declines in the abundance of charcoal suggested gradual replacement of fire-dominated wetlands by mangrove forest over the following 2650 yr. By ~ 1150 cal yr BP, a dense Rhizophora mangle dominated mangrove forest had formed at the mouth of the Shark River. The mangrove-dominated coastal ecosystem here was established at least 2000 yr later than has been previously estimated.},
	issn = {0033-5894},
	doi = {10.1016/j.yqres.2015.03.005},
	url = {http://www.sciencedirect.com/science/article/pii/S0033589415000290},
	author = {Yao, Qiang and Liu, Kam-biu and Platt, William J. and Rivera-Monroy, Victor H.}
}
@article {145,
	title = {A sedimentary-based history of hurricane strikes on the southern Caribbean coast of Nicaragua},
	journal = {Quaternary Research},
	volume = {78},
	year = {2012},
	note = {id: 2327},
	pages = {454-464},
	abstract = {Multi-millennial hurricane landfall records from the western North Atlantic indicate that landfall frequency has varied dramatically over time, punctuated by multi-centennial to millennial scale periods of hyperactivity. We extend the record geographically by presenting a paleostrike record inferred from a four-core transect from a marsh on the Caribbean coast of Nicaragua. Fossil pollen indicates that the site was a highly organic wetland from ~ 5400{\textendash}4900 cal yr BP, at which time it became a shallow marine lagoon until ~ 2800 cal yr BP when it transitioned back into swamp/marsh, freshening over time, with the present fresh-to-brackish Typha marsh developing over the very recent past. Hurricane Joan, 1988, is recorded as a distinctive light-colored sand{\textendash}silt{\textendash}clay layer across the top of the transect, identifiable by abrupt shifts in color from the dark marsh deposits, increased grain size, and two upward-fining sequences, which are interpreted as representing the storm{\textquoteright}s traction and suspension loads. The six layers identified as hurricane-generated display temporal clustering, featuring a marked increase in landfall frequency ~ 800 cal yr BP. This pattern is anti-phase with the activity pattern previously identified from the northern Caribbean and the Atlantic coast of North America, thereby opposing the view that hyperactivity occurs simultaneously across the entire basin.},
	issn = {0033-5894},
	doi = {10.1016/j.yqres.2012.07.003},
	url = {http://www.sciencedirect.com/science/article/pii/S003358941200083X},
	author = {McCloskey, Terrence Allen and Liu, Kam-biu}
}
