Core Correlation

Thompson, Roy; Clark, R. M.; Boulton, G. S.

doi:10.1007/978-94-007-2745-8_13

Cited by 10 publications

(4 citation statements)

References 33 publications

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“…Correlation between replicate cores was established using a sequence slotting technique ( 41 ) based on volume magnetic susceptibility data from each core. Calculations were performed with CPLSlot 2.4b ( 42 ). Core liners were split longitudinally in the laboratory.…”

Section: Methodsmentioning

confidence: 99%

Geoarchaeological evidence from Angkor, Cambodia, reveals a gradual decline rather than a catastrophic 15th-century collapse

Penny

Hall

Evans

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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Alternative models exist for the movement of large urban populations following the 15th-century CE abandonment of Angkor, Cambodia. One model emphasizes an urban diaspora following the implosion of state control in the capital related, in part, to hydroclimatic variability. An alternative model suggests a more complex picture and a gradual rather than catastrophic demographic movement. No decisive empirical data exist to distinguish between these two competing models. Here we show that the intensity of land use within the economic and administrative core of the city began to decline more than one century before the Ayutthayan invasion that conventionally marks the end of the Angkor Period. Using paleobotanical and stratigraphic data derived from radiometrically dated sediment cores extracted from the 12th-century walled city of Angkor Thom, we show that indicia for burning, forest disturbance, and soil erosion all decline as early as the first decades of the 14th century CE, and that the moat of Angkor Thom was no longer being maintained by the end of the 14th century. These data indicate a protracted decline in occupation within the economic and administrative core of the city, rather than an abrupt demographic collapse, suggesting the focus of power began to shift to urban centers outside of the capital during the 14th century.

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Section: Methodsmentioning

confidence: 99%

Geoarchaeological evidence from Angkor, Cambodia, reveals a gradual decline rather than a catastrophic 15th-century collapse

Penny

Hall

Evans

et al. 2019

Proc. Natl. Acad. Sci. U.S.A.

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“…Here, to compare PSV datasets, we use sequence slotting, an objective method for relating different sets of stratigraphic sample data (Benito & Birks, 2020; Gary et al., 2005; Thompson et al., 2012; Wakefield et al., 2022). Sequence slotting parameterizes the relationships between datasets by evaluation of a distance metric (in our case a Euclidean distance) and finds an optimum slotting by utilizing this metric when the PSV records are combined.…”

Section: Resultsmentioning

confidence: 99%

“…We use the CPLSlot version of sequence slotting (Hounslow & Clark, 2023) based on Clark (1985). Sequence slotting does not utilize time or age models in its evaluation, but only the relative stratigraphic order of sample datasets and the coherent structure in the compared data (Thompson et al, 2012). In order to use time as a constraint in sequence slotting, we introduce a time variable for the PSV age model (scaled from 0 to 1.0, with the 1.0 corresponding to the maximum age in the comparison datasets).…”

Section: Quantitative Comparison Of the Lake Chala To Psv Records Of ...mentioning

confidence: 99%

A Lake Record of Geomagnetic Secular Variations for the Last 23 ka From Lake Chala: Toward a Composite Directional Lake Record of the Earth's Magnetic Field for Equatorial East Africa

Di Chiara,

Hounslow,

Maher

et al. 2024

Geochem Geophys Geosyst

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The documentation and understanding of variations in the Earth's magnetic field through time is fundamental for several disciplines, but current geomagnetic models rely on datasets heavily biased toward the mid‐ and high northern latitudes. The African continent and surrounding islands and oceans are particularly underrepresented. Here, we present a new record of paleo‐secular variation (PSV) of the inclinations over the last 23 ka from Lake Chala, situated at 3°S near Mt Kilimanjaro in eastern equatorial Africa. This groundwater‐fed crater lake is characterized by a high sedimentation rate (ca. 1 cm/10 years) and a particularly well‐constrained age model based on 210Pb and 14C dating. The magnetic mineralogy of the sediments is tested with rock magnetic analyses. The Lake Chala inclination record shows four highs and lows over 20 ka and compares well with that of Lake Malawi (10°S) between 20 and 16.2 ka, and from 9.8 to 2.6 ka. This record is linked to PSV records at Lakes Victoria and Malawi using a sequence slotting technique to generate a composite PSV model for east Africa. Analyzed at best‐possible resolutions up to 200 years, the Lake Chala PSV record not only represents an important contribution to improve our understanding of local and global features of the Earth's magnetic field. It also expands the utility of paleomagnetism as a key tool for dating and correlation both for archeological sites throughout East Africa and the many volcanoes, active or dormant, of the East African Rift System.

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“…Depth‐dependent sedimentation rates were obtained with the 210 Pb constant rate of supply age model (Appleby & Oldfield, 1978; Appleby et al., 2001) (see Text S2 in Supporting Information for more details about the method). The 210 Pb ages from core 2 were transferred to core 1 by aligning the Loss on Ignition (LOI) depth profiles (Thompson et al., 2012). LOI was measured by sub‐sampling (0.5 ± 0.05 g) well‐mixed wet sediment into a pre‐weighted dry crucible and then sequentially heating the sample at 90° (24 hr), 550°C (2 hr), and 950° (2 hr) with 2 hr of cooling in between.…”

Section: Methodsmentioning

confidence: 99%

Contrasting Impacts of Agricultural Intensification and Urbanization on Lake Phosphorus Cycling and Implications for Managing Eutrophication

Slowinski,

Radosavljevic,

Graham

et al. 2023

JGR Biogeosciences

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Sediment core and water quality data, together with historical information on land use/land cover (LULC), were used to reconstruct changes in phosphorus (P) loading and cycling in Lake Wilcox, Ontario, Canada, since the early 1920s. After first being cleared for farming, the originally forested watershed subsequently underwent urbanization. The large increase in P loading accompanying agricultural intensification after World War II caused the eutrophication of the lake. However, improved soil conservation since the 1980s and urban stormwater management since the 1990s have brought watershed P loading and sediment accumulation down to levels comparable to the early 1900s. Yet, the lake continues to exhibit eutrophication‐like symptoms, especially the intensification of hypoxia in the hypolimnion. Post‐2000 water quality data indicate that the latter is not driven by external P loading from the watershed, but rather by rapid salinization that strengthens the lake's summer stratification and enhances internal P loading. Salinization is caused by the increasing application of deicing agents in the expanding urban area. Curbing salt inputs will therefore be essential to restore the lake. Overall, our results provide new insights into the shifts in lake biogeochemistry associated with LULC changes and the implementation of best management practices. The approaches and findings of our case study have broad applicability for the large number of freshwater ecosystems worldwide that are experiencing salinization.

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Core Correlation

Cited by 10 publications

References 33 publications

Geoarchaeological evidence from Angkor, Cambodia, reveals a gradual decline rather than a catastrophic 15th-century collapse

Geoarchaeological evidence from Angkor, Cambodia, reveals a gradual decline rather than a catastrophic 15th-century collapse

A Lake Record of Geomagnetic Secular Variations for the Last 23 ka From Lake Chala: Toward a Composite Directional Lake Record of the Earth's Magnetic Field for Equatorial East Africa

Contrasting Impacts of Agricultural Intensification and Urbanization on Lake Phosphorus Cycling and Implications for Managing Eutrophication

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