Both planktonic foraminifers and calcareous nannofossils indicate that the interval between ~230 and 330 mbsf at Site 1198 was deposited during the late Miocene (8.3–11 Ma). LBF assemblages (Fig. F15) transported into this interval are dominated by stellate L. (N.) howchini and Amphistegina spp., with common Cycloclypeus, Lepidocyclina (Nephrolepidina) martini, and Operculina. Furthermore, the final LBF assemblages in Samples 194-1193A-5H-1, 142 cm (~36 mbsf), 194-1194B-2R-4, 69 cm (~115 mbsf), and 194-1197B-2R-1, 42 cm (~62 mbsf), are remarkably similar (Fig. F16). At all three sites, LBF assemblages are dominated by Amphistegina spp. and distinctive stellate Lepidocyclina and occur in a matrix of planktonic foraminifers and bioclastic carbonates, indicating offbank deposition of late Miocene material. A nannofossil range of 7.5–8.6 Ma in Sample 194-1194A-13H-CC (117.4 mbsf) in the overlying pelagic sediments support this interpretation.
At Site 1196, platform carbonates above 150 mbsf were rich in LBF, though evidence is mostly preserved as molds in dolomitized intervals. The terminal platform LBF assemblage at Site 1196 (Fig. F17A, F17B) is dominated by Amphistegina spp. with abundant Cycloclypeus and Operculina and common stellate Lepidocyclina, which provides minimal biostratigraphic constraint on the timing of the platform drowning. Similarly, downslope deposits of platform sediments at Sites 1197 and 1198 are not definitive. However, at Site 1198, for which the best biostratigraphic record is available, a minor lithologic change (lithologic Subunit IIA/IIB boundary; see Shipboard Scientific Party, 2002) was dated at 8.3 Ma, based upon first observation of Globigerinoides extremus. Above this boundary, a distinctive lepidocyclinid (Fig. F16C), tentatively identified as Lepidocyclina (Nephrolepidina) rutteni (Van der Vlerk), was found, and very similar forms were found in the upper 40 m at Site 1196 (Fig. F16A). Thus, the uppermost MP3 platform was deposited in latest Miocene or earliest Pliocene, consistent with previous observations of L. (N.) rutteni on the Queensland Plateau (e.g., Betzler, 1997).