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doi:10.2204/iodp.proc.346.202.2018 Methods and materialsThis study is based on 455 samples that were collected at almost uniform intervals within Holes U1427A, U1427B, and U1427C. Sample preparation for light microscopy observation was conducted as follows:
The total number of radiolarians in 1 g of dry sediment was estimated using the following equation:
Relative abundance (percent of total assemblage) of subtropical species was estimated by counting and identifying more than 200 individuals on the F-slide; however, when radiolarian individuals were scarce, as many as could be identified were counted. The absolute abundance of subtropical species (individuals/g) was converted using the following equation:
Although very few counts often cause inaccurate relative percent data, the absolute abundance (individuals/g) estimated from the few counts shows low values regardless of count numbers. Therefore, the absolute abundance is used for illustrating abundance changes of subtropical species in this report (Table T1). For key species used as biostratigraphic datums, their occurrence or absence was checked over the entire slide (Table T1). Taxonomic framework was adapted from Itaki et al. (2007) and Matsuzaki et al. (2014). This report follows the Geological Time Scale 2012 (GTS 2012) of Gradstein et al. (2012). |