Mass-wasting deposits characterize the Upper Jurassic(?) to Lower Cretaceous sedimentary record of the Iberia Abyssal Plain. These deposits include olistostromes at Site 897, olistostromes and/or possible rock-fall deposits at Site 899, a breccia succession at Site 1068, slumped and fractured deposits at Site 1069, and a breccia succession at Site 1070. Whereas the exact origin of these deposits is uncertain, the regional common occurrence of middle to upper Mesozoic mass-wasting deposits suggests that they record the early rifting evolution of the west Iberia margin.This data report presents both qualitative and semiquantitative results from XRD analyses of the breccia matrix at Site 1068. In this study the matrix is defined as the fine-grained particles (as viewed through a binocular microscope) plus cement. Results are based on analytical methods that aimed to isolate the desired matrix from larger clast contamination prior to XRD analyses. In addition, the breccia was sampled at a higher resolution than was conducted aboard ship, producing a more complete description of downcore matrix mineralogical changes. The data presented here may be used to (1) further justify the subunit designation of Unit IV made aboard ship, (2) help determine to what degree the matrix and the larger clasts (studied in thin section aboard ship; Shipboard Scientific Party, 1998, doi:10.2973/odp.proc.ir.173.106.1998) are compositionally distinct, (3) help identify the extent of hydrothermal fluid migration in the breccia, and (4) support the proposed shipboard hypothesis that the Site 1068 breccia succession resulted from multiple mass-wasting.
Sediment depth is given in mbsf. #1 = detected in trace amounts. Please note, that calibration curves could not be constructed and the mineral/boehmite peak area ratios have not been converted to mineral abundances. Rather, downcore variations in the abundance of a single mineral (e.g., calcite) are described using downcore changes in the integrated intensity ratios of that mineral. This method does not allow for comparison of the absolute abundances of two or more different minerals.
Supplement to: St. John, Kristen E Kudless (2000): Data report: Downcore variation of Site 1068 breccia matrix mineralogy. In: Beslier, M-O; Whitmarsh, RB; Wallace, PJ; Girardeau, J (eds.) Proceedings of the Ocean Drilling Program, Scientific Results, College Station, TX (Ocean Drilling Program), 173, 1-14
