@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 {hanke_sequential_2023,
	title = {Sequential thermal analysis of complex organic mixtures: Procedural standards and improved CO2 purification capacity},
	journal = {Radiocarbon},
	volume = {65},
	number = {2},
	year = {2023},
	note = {Publisher: Cambridge University Press},
	month = {03/2023},
	pages = {389{\textendash}409},
	abstract = {Sequential thermal analysis allows for deconvoluting the refractory nature and complexity of carbon mixtures embedded in mineral matrices for subsequent offline stable carbon and radiocarbon (14C) isotope analyses. Originally developed to separate Holocene from more ancient sedimentary organic matter to improve dating of marine sediments, the Ramped Pyrolysis and Oxidation (RPO) apparatus, or informally, the {\textquotedblleft}dirt burner{\textquotedblright} is now used to address pressing questions in the broad field of biogeochemistry. The growing interest in the community now necessitates improved handling and procedures for routine analyses of difficult sample types. Here we report on advances in CO2 purification during sample processing, modifications to the instrumentation at the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) facility, and introduce sodium bicarbonate procedural standards with differing natural abundance 14C signatures for blank assessment. Measurements from different environmental samples are used to compare the procedure to the different generations of sequential thermal analyses. With this study, we aim to improve the standardization of the procedures and prepare this instrumentation for innovations in online stable carbon isotopes and direct AMS-interface measurements in the future.},
	keywords = {chemical analysis, dirt burner, full oxidation (FOX) mode, Radiocarbon dating, ramped pyrolysis oxidation},
	issn = {0033-8222, 1945-5755},
	doi = {10.1017/RDC.2023.13},
	url = {https://www.cambridge.org/core/journals/radiocarbon/article/sequential-thermal-analysis-of-complex-organic-mixtures-procedural-standards-and-improved-co2-purification-capacity/E225F01B421614EE176553014E7B38BE},
	author = {Hanke, Ulrich M. and Gagnon, Alan R. and Reddy, Christopher M. and Gaylord, Mary C. Lardie and Cruz, Anne J. and Galy, Valier and Hansman, Roberta L. and Kurz, Mark D.}
}
@inbook {2998,
	title = {Chapter 30 - Radiocarbon dating of tsunami and storm deposits},
	booktitle = {Geological Records of Tsunamis and Other Extreme Waves},
	year = {2020},
	month = {2020/01/01/},
	pages = {663 - 685},
	publisher = {Elsevier},
	organization = {Elsevier},
	abstract = {Radiocarbon age determinations can be an expedient and accurate means to assign age to deposits of tsunami or storm origin. Essential to the process of incorporating radiocarbon age determinations in tsunami or coastal storm investigations is an awareness on the part of the investigator that a sample will always return an age from a laboratory, but only carefully selected samples inform deposit age. Samples that inform deposit age are of two fundamentally different sample types, in-growth-position samples and detrital samples. For both in-growth-position samples and detrital samples, stratigraphic context is the critical information needed to evaluate how well sample age can constrain deposit age. Well constrained deposit ages require bracketing samples collected to provide both maximum and minimum limiting ages for the deposit(s) of interest. Therefore, sampling should be carried out with the intention of multiple sample submissions for age in order to optimize the potential for acquiring closely limiting ages. If there are multiple age determinations within a stratigraphic sequence that contains tsunami or storm deposits, then the calibrated radiocarbon ages can be, and should be, framed within a Bayesian model structure to better constrain deposit ages. Such models can be further improved by the incorporation of independent stratigraphic age information.},
	keywords = {Dating coastal storm deposits, Dating tsunami deposits, Modeling approaches for dating tsunami deposits, Radiocarbon dating, Sampling tsunami deposits, Tsunami Deposits, Tsunami sand},
	isbn = {978-0-12-815686-5},
	doi = {10.1016/B978-0-12-815686-5.00030-4},
	url = {https://www.sciencedirect.com/science/article/pii/B9780128156865000304},
	author = {Kelsey, Harvey M. and Witter, Robert C.},
	editor = {Engel, Max and Pilarczyk, Jessica and May, Simon Matthias and Brill, Dominik and Garrett, Ed}
}
@article {2772,
	title = {Holocene occupation history of pygoscelid penguins at Stranger Point, King George (25 de Mayo) Island, northern Antarctic Peninsula},
	journal = {The Holocene},
	volume = {30},
	year = {2020},
	month = {Jan-01-2020},
	pages = {190 - 196},
	abstract = {We report additional fossil evidence for pygoscelid penguins breeding on King George (25 de Mayo) Island, South Shetland Islands, in the Holocene beginning at ~7000 cal. yr BP. This evidence comes from a raised marine beach deposit formerly studied and described as Pingfo I at Stranger Point, Potter Peninsula. We relocated and exposed deposits at this site and recovered additional samples of penguin bones from five stratigraphic beds that are redescribed here. Most of these bones are from juvenile penguins and exhibit little or no wear indicating minimal transport to the beach deposits. Some of the bones are developed enough to be identifiable to Ad{\'e}lie (Pygoscelis adeliae), Gentoo (Pygoscelis papua), and Chinstrap (Pygoscelis antarctica) penguins, indicating that all three species were breeding at Stranger Point from ~7320 to 4865 cal. yr BP. This breeding occupation corresponds with the first warming and deglaciation that occurred in the northern Antarctic Peninsula by this time and ends with the onset of reglaciation of the Peninsula. At least 31 abandoned penguin mounds and ornithogenic soils also were located and sampled at Stranger Point and indicate that the current occupation of this area by all three pygoscelid penguins dates no older than ~535 cal. yr BP. The absence of ornithogenic soils from earlier Holocene breeding was probably due to glacial activity and soil solifluction during periods of warming in the mid to late Holocene.},
	keywords = {abandoned penguin mounds, Holocene penguin colonization, marine beach deposit, ornithogenic soil, Radiocarbon dating, South Shetlands, West Antarctica},
	issn = {0959-6836},
	doi = {10.1177/0959683619875814},
	url = {http://journals.sagepub.com/doi/10.1177/0959683619875814},
	author = {Emslie, Steven D and Romero, Mat{\'\i}as and Ju{\'a}res, Mariana A and Argota, Martin R}
}
@article {2822,
	title = {Sediment accumulation and sedimentation rates in playas on the High Plains of western Kansas, USA},
	journal = {Geomorphology},
	volume = {342},
	year = {2019},
	month = {Jan-10-2019},
	pages = {117 - 126},
	abstract = {Grassland ecosystems are some of the most modified ecosystems in the world, largely due to conversion to cropland, and the High Plains of the central United States is no exception. Playa wetlands are ubiquitous features of the High Plains and have experienced increased sediment accumulation, which is the primary cause of reduced playa ecosystem function. Seven playas on the High Plains of western Kansas, five with cropland-dominated watersheds and two with grassland-dominated watersheds, were examined to quantify the amount of recent (past ~100{\textendash}175 yr) sediment accumulated within playas and to establish chronologies of playa filling. Thicknesses of recent sediment were determined in the field, and soil cores were extracted from study playas. Four playa cores were analyzed for 210Pb to establish the chronology of recent sediment accumulation and sedimentation rates. Chronologies of pre-agricultural sediments and sedimentation rates were calculated by 14C dating of buried soils preserved within playa cores. Radiocarbon ages indicate playa stratigraphic records span the Holocene and that these playas have persisted on the landscape since at least the Late Pleistocene. Long-term, natural sedimentation rates were highest during the Pleistocene-Holocene transition and early Holocene, at ~2{\textendash}4 cm/century. During the middle and late Holocene, sedimentation rates averaged ~1 cm/century. Cropland playas accumulated ~10{\textendash}15 cm of recent sediment at average rates of ~6.5{\textendash}10 cm/century, while grassland playas accumulated only ~2 cm of recent sediment. Conversion of watersheds to cropland has greatly accelerated sediment accumulation within playas, which is generally resulting in a decline in critical playa ecosystem functions.},
	keywords = {210Pb, Agricultural, chronology, Holocene, Radiocarbon dating, sedimentation},
	issn = {0169555X},
	doi = {10.1016/j.geomorph.2019.06.014},
	url = {https://linkinghub.elsevier.com/retrieve/pii/S0169555X19302612},
	author = {Bowen, Mark W. and Johnson, William C.}
}
@article {2633,
	title = {Blue marlin ( <i>Makaira nigricans</i>               ) longevity estimates confirmed with bomb radiocarbon dating},
	journal = {Canadian Journal of Fisheries and Aquatic Sciences},
	volume = {75},
	year = {2018},
	month = {Jan-01-2018},
	pages = {17 - 25},
	abstract = {The longevity of blue marlin (Makaira nigricans) remains unresolved. The use of fin spines and sagittal otoliths for age reading has led to unconfirmed longevity estimates near 20-30 years. Age validation has been elusive because large individuals are uncommonly caught, and a technique that can be applied to structures that provide estimates of age was absent. The use of otolith chemical signatures has been limited by sagittal otoliths that are very small-whole otolith mass of adult blue marlin rarely exceeds 10 mg for the largest fish. Recent advances in the detection limits of radiocarbon (14C) with accelerator mass spectrometry-coupled with recently acquired knowledge of marine bomb 14C signals spanning the tropical Pacific Ocean-have led to an opportunity to age blue marlin from small amounts of otolith material. In this study, otoliths from a recently collected 1245 lb (565 kg) female blue marlin at a measured 146-inch (371 cm) lower jaw fork length were analyzed for 14C. Estimated longevity was either 12-21 or 32-44 years on the basis of bomb 14C dating. Using multiple lines of evidence, it was determined that the young age scenario was most likely, with evidence for an age close to 20 years using a series of deductions in the bomb 14C dating method.},
	keywords = {Accelerator mass spectrometry, Biology, Blue marlin, Ecology, Fish measurement, FisheryLongevity, Otolith, Radiocarbon dating},
	issn = {0706-652X},
	doi = {10.1139/cjfas-2017-0031},
	url = {http://www.nrcresearchpress.com/doi/10.1139/cjfas-2017-0031http://www.nrcresearchpress.com/doi/pdf/10.1139/cjfas-2017-0031http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjfas-2017-0031},
	author = {Andrews, Allen H. and Humphreys, Robert L. and Sampaga, Jeffery D.}
}
@article {2450,
	title = {The Growth Stop Phenomenon Of Baobabs (Adansonia Spp.) Identified By Radiocarbon DatingAbstract},
	journal = {Radiocarbon},
	volume = {59504754164661},
	year = {2017},
	month = {Jan-04-2017},
	pages = {435 - 448},
	abstract = {The article reports the growth stop phenomenon, which was documented only for baobabs, i.e. for trees belonging to the Adansonia genus. The identification of growth stop was enabled by radiocarbon dating, which allows a complex investigation of samples collected from the trunk/stems of baobabs. In several cases, the outermost rings of baobabs, which were close to the bark, were found to be old, with ages of several hundreds of years, instead of being very young. Dating results of samples collected from six baobabs are presented. For multistemmed baobabs, the growth stop may occur only for one or several stems. We identified four factors that may induce the growth stop: (i) stress determined by severe climate conditions, (ii) old age, (iii) the need to keep a stable internal architecture, and (iv) the collapse of stems that survive this trauma. Baobabs and their stems affected by growth stop may survive for several centuries, by continuing to produce leaves, flowers, and fruits. This phenomenon was associated with the capacity of baobabs to store large amounts of water in their trunks/stems in the rainy season. This reservoir of water is used during the dry season and allows the trees to survive prolonged drought periods.},
	keywords = {Age determination, AMS, growth stop, Radiocarbon dating, tropical trees},
	issn = {0033-8222},
	doi = {10.1017/RDC.2016.92},
	url = {https://www.cambridge.org/core/product/identifier/S0033822216000928/type/journal_articlehttps://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033822216000928},
	author = {Patrut, Adrian and Woodborne, Stephan and von Reden, Karl F and Hall, Grant and Patrut, Roxana T and Rakosy, Laszlo and Danthu, Pascal and Pock-Tsy, Jean-Michel Leong and Lowy, Daniel A and Margineanu, Dragos}
}
@article { ISI:000327567200017,
	title = {The Duxbury Sunken Forest-Constraints for Local, Late Holocene Environmental Changes Resulting from Marine Transgression, Duxbury Bay, Eastern Massachusetts, USA},
	journal = {JOURNAL OF COASTAL RESEARCH},
	volume = {29},
	number = {{6A, S}},
	year = {2013},
	month = {NOV},
	pages = {168-176},
	type = {Article},
	abstract = {The present marine transgression has forced geological and ecological zones vertically higher and landward since the late Pleistocene. A recent investigation in Duxbury Bay, Massachusetts, identified 18 Juniperus virginiana tree stumps emergent on an intertidal flat immediately seaward of a small marsh and pond situated between two eroding drumlins. The position of each stump was mapped with global positioning system (GPS), and its elevation with respect to mean lower low water was surveyed. Samples were selected from four stumps with elevations ranging from 2.03 and 0.75 m above mean lower low water for radiocarbon dating. The samples returned calibrated ages between 2219 +/- 94 and 2867 +/- 79 cal YBP, with the topographically highest sample returning the youngest date. Stump positions suggest a landscape gradient of 1.4 mm/yr between 2000 and 3000 cal YBP. The results are comparable with high-resolution studies of sea level in eastern Massachusetts for the same time period. Comparison of the youngest paleostumps with modern living trees suggests a dramatic change in the landscape gradient, an increase to 1.8 mm/yr. While this is contrary to sea-level studies nearby, it may represent an increase in the energetics of Duxbury Bay and resultant coastal erosion as the bay floods. The site can be used to put the impacts of changing sea-level rates into a landscape evolution framework.},
	keywords = {Cape Cod Bay, Coastal evolution, paleoforest, Radiocarbon dating, sea level, tree stumps},
	issn = {0749-0208},
	doi = {10.2112/JCOASTRES-D-12-00183.1},
	author = {Gontz, Allen M. and Maio, Christopher V. and Rueda, Laura}
}
@article { ISI:000294494900012,
	title = {Age determination of large live trees with inner cavities: radiocarbon dating of Platland tree, a giant African baobab},
	journal = {ANNALS OF FOREST SCIENCE},
	volume = {68},
	number = {{5, SI}},
	year = {2011},
	month = {AUG},
	pages = {993-1003},
	type = {Article},
	abstract = {Introduction For large trees without a continuous sequence of growth rings in their trunk, such as the African baobab (Adansonia digitata L.), the only accurate method for age determination is radiocarbon dating. As of today, this method was limited to dating samples collected from the remains of dead specimens. Methods Our research extends significantly the dating of such trees to large live specimens with inner cavities. The new approach is based on collecting samples from the cavities and their subsequent radiocarbon dating. Results The giant two-stemmed Platland tree, also known as Sunland baobab, was investigated by using this new approach. AMS radiocarbon dates of the oldest sample segments originating from the two inner cavities indicate that the large stem I (364.5 m(3)) is 750 +/- 75 years old, while the much smaller stem II (136.7 m(3)) has 1,060 +/- 75 years. Results also show that stem I is still growing very fast, while the older stem II slowed down consistently its growth over the past 250 years. The complete mapping of Platland tree determined an overall wood volume of 501.2 m(3). Conclusions Dating results demonstrate that the size-age relation cannot be used for estimating accurately the age of African baobabs.},
	keywords = {Accelerator mass spectrometry, Adansonia digitata, Age determination, Growth rate, Radiocarbon dating},
	issn = {1286-4560},
	doi = {10.1007/s13595-011-0107-x},
	author = {Patrut, Adrian and von Reden, Karl F. and Van Pelt, Robert and Mayne, Diana H. and Lowy, Daniel A. and Margineanu, Dragos}
}
@article {1015,
	title = {Aspartic acid racemization dating of Holocene brachiopods and bivalves from the southern Brazilian shelf, South Atlantic},
	journal = {Quaternary Research},
	volume = {66},
	year = {2006},
	note = {id: 1168},
	pages = {323-331},
	abstract = {The extent of racemization of aspartic acid (Asp) has been used to estimate the ages of 9 shells of the epifaunal calcitic brachiopod Bouchardia rosea and 9 shells of the infaunal aragonitic bivalve Semele casali. Both taxa were collected concurrently from the same sites at depths of 10 m and 30 m off the coast of Brazil. Asp D/L values show an excellent correlation with radiocarbon age at both sites and for both taxa (r2Site 9 B. rosea = 0.97, r2Site 1 B. rosea = 0.997, r2Site 9 S. casali = 0.9998, r2Site 1 S. casali = 0.93). The Asp ratios plotted against reservoir-corrected AMS radiocarbon ages over the time span of multiple millennia can thus be used to develop reliable and precise geochronologies not only for aragonitic mollusks (widely used for dating previously), but also for calcitic brachiopods. At each collection site, Bouchardia specimens display consistently higher D/L values than specimens of Semele. Thermal differences between sites are also notable and in agreement with theoretical expectations, as extents of racemization for both taxa are greater at the warmer, shallower site than at the cooler, deeper one. In late Holocene marine settings, concurrent time series of aragonitic and calcitic shells can be assembled using Asp racemization dating, and parallel multi-centennial to multi-millennial records can be developed simultaneously for multiple biomineral systems.},
	keywords = {Amino acid racemization, Aspartic, Bouchardia, Brachiopods, Brazil, Holocene, Mollusks, Radiocarbon dating, Semele, Ubatuba Bay},
	doi = {10.1016/j.yqres.2006.04.001},
	author = {Barbour-Wood, S. L. and Krause R.A, Jr. and Kowalewski, M. and Wehmiller, J. F. and Simoes, M. G.}
}
@conference {1278,
	title = {The Effect of Different Acid Treatments on the Radiocarbon Age of Sedimentary Organic Matter},
	booktitle = {EOS, Transactions, American Geophysical Union},
	year = {2001},
	note = {Date revised - 2007-02-01SuppNotes - Session: OS41A 9 The Truth About Paleoceanographic Proxies - What Are They Really Telling Us III Posters.Last updated - 2016-05-27},
	month = {January 2001},
	publisher = {American Geophysical Union, 2000 Florida Ave., N.W. Washington DC 20009 USA, [mailto:service@agu.org]},
	organization = {American Geophysical Union, 2000 Florida Ave., N.W. Washington DC 20009 USA, [mailto:service@agu.org]},
	abstract = {To date the bulk organic carbon in marine sediments it is necessary to first remove any inorganic carbon present by acidification. We tested three different acid treatments to see how the different methods affected the stable and radio-carbon isotopic values of the remaining organic matter. The standard NOSAMS method is to react the sediment with repeated aliquots of1.2N HCl until no visible dissolution reaction is present. The remaining sediment is then rinsed with distilled water. This method leaves a carbonate-free sediment that is easy to combust but suffers from the possible removal of acid-soluble organic matter. We compared this method to two methods that do not require rinsing of the sediments after acid treatment--a vapor phase acidification method using concentrated HCl (Hedges and Stern, 1984) and an in situ acidification with sulfurous acid (Verardo et al., 1990). Scaling these methods up to deal with the amount of sediment required for a radiocarbon date can present challenges that are not evident when dealing with the small quantities required for a percent organic carbon measurement. Vapor phase acidification of high carbonate sediments leaves hygroscopic salts that can impede sample combustion. Sulfurous acid is a weak acid and it is very difficult to determine when all the carbonate has been removed from a sediment sample. We tested sediments from 6 locations in (or near) the Atlantic Ocean that represented riverine, estuarine, and marine environments as well as a range of both organic and inorganic concentrations. We will present the isotopic results for these sediments and evaluate what is the most appropriate method to use. Hedges J.I. and J.H. Stern (1984) Limnol. Oceanogr. 29, 657-663. Verardo D.J., P.N. Froelich and A. McIntyre (1990) Deep-Sea Res. 37, 157-165.},
	keywords = {A, Atlantic, Acidification, Brackish, Brackishwater environment, carbon cycling, Chronostratigraphy, Estuarine sedimentation, organic carbon, organic matter, Palaeoceanography, Radioactivity and radioisotopes, Radiocarbon dating, Sediment chemistry, Stable isotopes},
	url = {https://search.proquest.com/docview/19468089?accountid=29119},
	author = {Batista, F and McNichol, A P and Gerlach, D S}
}
