INTRODUCTION

On the northeast Australia Great Barrier Reef (GBR) margin, bulk percent calcium carbonate (wt% CaCO₃) and planktonic foraminiferal ¹⁸O analyses on late Quaternary slope and trough sediments indicate cyclic variations in carbonate content likely results from dilution with terrigenous material during eustatic sea level transgressions (Dunbar et al., 2000; Dunbar and Dickens, 2003a, 2003b; Page et al., 2003; Page and Dickens, 2005). However, whether shelf physiography (i.e., the terrigenous sediment trapping capability of the GBR) or variations in rainfall and runoff from the adjacent continent provide the mechanism for this "transgressive shedding" is in debate (see Page, this volume, and references therein).

This data report presents bulk wt% CaCO₃ analyses from Hole 1198A lithologic Subunits 1A (107 samples) and 1B (221 samples). In an effort to understand the mechanism for transgressive shedding, an upcoming publication will expand upon this data set and contrast the timing, with respect to sea level, of maximum off-shelf sediment flux during the early and late Pleistocene, presumably prior and subsequent to the emplacement of GBR, respectively (e.g., International Consortium, 2001).

Data presented herein from Subunit 1A overlap with the data of Page (this volume), providing the opportunity for comparison of differing methodologies of wt% CaCO₃ determination ("carbonate bomb" and coulometer) and extend the continuous record of bulk wt% CaCO₃ data in Hole 1198A to the middle Pleistocene (Shipboard Scientific Party, 2002). Analyses from within Subunit 1B provide an equally long early Pleistocene record (Shipboard Scientific Party, 2002) for comparison with the late to middle Pleistocene records of this report and Page (this volume).