The present synthesis is designed to draw attention to an intriguing array of geochemical findings from the pore-water study of Leg 165 while incorporating new geochemical data and interpretative methods. Leg 165 was diverse in its scientific agenda, with discoveries spanning the Cretaceous/Tertiary (K/T) boundary, records of extensive Cenozoic volcanism, multifaceted paleoceanographic considerations such as a basinwide Miocene record of abrupt diminution in carbonate accumulation, and records of the basaltic basement and their chemical relationships to the overlying sediments. The intent of the present synthesis is to provide a snapshot from the pore-water work during Leg 165 within the context of the broad agenda of the cruise. We have not attempted to integrate all the nuances of the complex systems into this report—the many details and data are available in Sigurdsson, Leckie, Acton, et al. (1997)—but rather our goal is to illustrate through representative figures and supporting text the geochemical story that unfolded during Leg 165. In doing this, we have emphasized only Sites 998, 999, 1000, and 1001, which are linked by their characteristic sedimentation rates, ash and carbonate richness, and organic deficiencies (see Fig. 1 and Sigurdsson, Leckie, Acton, et al. [1997] for site background). The rapidly accumulating, organic-rich sediments of Site 1002 in the anoxic Cariaco Basin are not discussed in the present report. The included results allow us to deconvolve complex pore-water signals derived from an abundance of reactive carbonate phases, extensive alteration of labile volcanic ash within the sediment column, strong pore-water linkages to alteration of underlying basaltic basement, and varying but low rates of biogeochemical cycling of redox-sensitive elements.