(Table 1) Description of CTBE samples from ODP Hole 103-641A and DSDP Hole 43-398D

Clay minerals are numbered according to their relative abundance in the clay fraction; higher numbers indicate decreasing amounts; smectite, the dominant clay mineral in all samples, is number 1. Quartz is of detrital or biogenic origin, calcite from planktonic foraminifers. Zeolite is probably an alteration product of radiolarian tests. Mica and feldspars are of detrital origin. The origin of chlorite, which forms only a small part of the samples, is uncertain, but it may be partially detrital. The microplankton content common in samples from the CTBE interval at Site 398 is not shown.