METHODS

New thin sections of jasperoid and enclosed wallrock particles were prepared from Samples 193-1189A-7R-1 (Piece 17, 99–102 cm; Commonwealth Scientific and Industrial Research Organization [CSIRO; Australia] 142697), and 193-1189B-11R-1 (Piece 3, 14–16 cm; CSIRO 142714). For the upper jasperoid intersection in Hole 1189B, the shipboard thin section (1189B 16) from nearby Sample 193-1189B-6R-1 (Piece 2, 13–15 cm) was reexamined.

For chemical analysis, representative portions of the three Leg 193 jasperoids, avoiding conspicuous wallrock fragments, were broken or sawn from the samples and the sawn surfaces cleaned with sandpaper. After ultrasonic cleaning and washing in deionized water to remove sea salt, and drying, these subsamples were finely ground under acetone in a mechanical agate mortar and pestle. Analyses were performed by X-ray fluorescence (XRF) spectrometry and by inductively coupled plasma–atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) using the CSIRO methods outlined in Miller et al. (this volume). Loss on drying (LOD; 105C) and loss on ignition (LOI; 1050C) were measured gravimetrically on a separate powder aliquot for one sample.

Preferred analyses, taking into account precision and sensitivity of the various methods, are provided in Table T2 together with the average composition of 16 Fe-Mn-Si oxide samples dredged from the seafloor at Roman Ruins. Several outlier analyses were excluded from the latter, as indicated in a table footnote.

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