Electronic Supplementarymaterial for the Paleohydrology of Sluice Pond, NE Massachusetts

Electronic SupplementaryMaterial for “The paleohydrology of Sluice Pond, NE Massachusetts, and its regional significance”

J. Bradford Hubeny, Francine M.G. McCarthy, Jonathan Lewis, Matea Drljepan, Cameron Morissette, John W. King, Mark Cantwell, Nicole M. Hudson, Mary Lynne Crispo

Age Constraints

The age model for core SP09KC2 is reported in Fig. 3. Here we offer supplemental information on the chronology, including 14C calibration and correlation to other dated records (210Pb and paleomagnetics). A detailed list of chronologic control points used in the age model is presented in Table ESM1.

Five AMS 14C dates from core SP09KC2 and oneAMS 14C date from core SP07PC4 were measured on terrestrial macrofossils (Table ESM2). Each sample wastreated with an acid-base-acid (ABA) procedure (Olsson 1986). Analyses were conducted at the NSF-Arizona AMS Laboratory. Calibrations were calculated using the CLAM 2.2 program (Blaauw 2010) and Intcal13 calibration data set (Reimer et al. 2013).

Additional chronologic control of core SP09KC2 was provided by paleomagneticdirectional and intensity correlations to well-dated regional records. Paleomagnetic data were measured at 1-cm resolution on u-channels sub-sampled from the basin core, using a 2-G® cryogenic magnetometer. Progressive alternating field (AF) demagnetization was performed; a stable signal was noted after the 150 Oe step, and these data were used for correlation to regional dated paleomagnetic records. Correlations were based on similarities of major features in each record, and all interpretations were consistent within the framework of the radiocarbon constraints. Paleomagnetic secular variation records typically correspond with centennial-scale variability(King and Peck 2001), and therefore the error on correlations was assigned a value of ± 100 years. Paleomagnetic inclination was correlated to the dated NE inclination record of King and Peck (2001) (Fig.ESM1). Relative paleomagnetic intensity was calculated as Natural Remanent Magnetization normalized to Anhysteretic Remanent Magnetization (NRM/ARM). The record was correlated to the dated record of St-Onge et al. (2003) (Fig.ESM2).

The recent chronology was constrained with a 210Pb and 137Cs CIC age model (Crescenzi et al. 2010). This chronology was quantified on a short surface core, SP10KC1. Core SP09KC2 was correlated to SP10KC1, and subsequently to its age model, by matching the volume magnetic susceptibility records (Fig.ESM3), confirmed with visual lithologic descriptions. Long core SP09KC2 has a compressed upper section and is missing <10 cm of sediment from the top as a result of the coring process, which used heavy weight to achieve deep penetration. The presence of three distinct peaks in the record enabled stratigraphic correlation between the cores.

The final age model, reported in Fig. 3, was calculated using 18 age constraints (Table ESM1) as a fourth-order polynomial regression (Blaauw 2010). One thousand iterations were calculated, and the calculated goodness-of-fit was 34.21.

Cyclic organic matter deposition

The high-resolution (1-cm) record of organic matter from LOI analysis (Fig. 5) enabled us to examine cyclic components of the record through spectral analysis of the time series. Spectral analysis was calculated on the LOI-OC timeseries in kSpectra 3.4,using the multi-taper method with 3 tapers. Because this technique requires evenly spaced time series, data were resampled in AnalySeries 2.0 (Paillard et al. 1996)at a temporal resolution of 24.8 yr (average sampling interval) prior to analysis. The 99%, 95%, and 90% confidence intervals were calculated for the spectral analysis, assuming a “red noise” first-order autoregressive (AR(1)) background (Mann and Lees 1996). Results are reported in Fig.ESM4, and peaks extending above the AR(1) background curves represent statistically significant frequencies within the record.

The general trend of OC in Sluice Pond mirrors that of regional temperature variability in the Holocene (Huang et al. 2002) (Fig. 5). Higher frequency components of the OC record, as determined through spectral analysis, assist interpretation of climatic controls for Sluice Pond (Fig. ESM4). A range of significant multidecadal and centennial periodicities were observed, demonstrating the dynamic nature of the Sluice Pond record. Similar periodic components have been found in numerous other Holocene climate proxy records, including reconstructions of the circumpolar vortex(Kirby et al. 2002), solar variability(Solanski et al. 2004) and ocean-atmospheric teleconnection patterns such as the Atlantic Multidecadal Oscillation(Delworth and Mann 2000; Hubeny et al. 2006; Knight et al. 2005). Although this study was unable to unravel the ultimate controlling factorson Sluice Pond cyclic variability, the significant cycles observed here corroborate and expand upon other research that focuses on such variability.

Table ESM1Details and list of 18 age constraints from core SP09KC2 used for the generation of CLAM 2.2 (Blaauw 2010)age model reported in Fig. 3

Table ESM2Sluice Pond AMS radiocarbon data. All dates from terrestrial macrofossils and analyses conducted at the NSF – Arizona AMS Laboratory. Calibrations were calculated using the CLAM 2.2 program (Blaauw 2010) and Intcal13 calibration data set (Reimer et al. 2013)

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