Figure 1 | Table of Contents


Figure 1. ETOPO5 bathymetric map of the Ontong Java Plateau (outlined) showing locations of primary (bold text) and alternate (plain text) drill sites (circles) proposed for Leg 192. Locations of previous ODP and DSDP drill sites (triangles) that reached basement are also shown, along with that of DSDP Site 288, which did not reach basement.

Figure 2. Summary of ages of OJP basement basalts and ages of ash layers within the sedimentary section at Site 288. The 44-and 34-Ma igneous rocks on Malaita are alkalic lavas and ultramafic intrusions, respectively. Ages derived from biostratigraphy are shown with error bars (from Tejada, 1998 and references therein). Fm = formation.

Figure 3. (A) SiO2 vs. MgO and (B) TiO2 vs. MgO for OJP lavas (from Neal et al., 1997 and C.R. Neal et al. unpubl. data for San Cristobal [Makira]).

Figure 4. Primitive-mantle-normalized element patterns for basalts of ODP Site 807, Malaita, and Santa Isabel (plus Ramos Island) (from Tejada, 1998, and references therein).

Figure 5. Initial eNd(t) vs. (206Pb/204Pb)t for basement lavas of Malaita and Santa Isabel. Heavily outlined fields encompass data for ODP Site 807 basement Unit A, and Sites 803 and 807, Units C-G. Data fields for the Manihiki Plateau (for dredged and Site 317 lavas), Nauru Basin, Pacific MORB, the Koolau and Kilauea volcanoes of Hawaii, and the Mangaia Group islands of the South Pacific are shown by light outlines (from Tejada, 1998).

Figure 6. Seismic control (black lines) for proposed drilling sites. Sonobuoy and ocean-bottom seismometer locations (solid triangles) on the OJP are shown, as are ODP Sites 803-807 and DSDP Sites 64, 288, and 298/586 (solid circles represents sites that penetrated igneous basement and open circles ones that penetrated sediment only). Proposed sites are indicated by squares (primary sites-lighter gray shading [web version red]; alternate sites are black). Line KH98-1: R/V Hakuho Maru, Line KH98-1 Leg 2 (1998); Line EW-9511: R/V Maurice Ewing 9511 (1995); Line TW-11: R/V Thomas Washington 11 (1988); Charcot: R/V Jean Charcot (1986). Map is from GEBCO charts.

Figure 1 | Table of Contents