Figure 2. Map showing location of Leg 194 proposed primary sites (black circles), contingency sites (black squares), and Sites 815 and 816 from Leg 133 (black-rimmed white circles). Solid lines show the location of multichannel seismic lines from the Australian Geological Survey Organization (thinner lines = Survey 75) and from the Leg 194 site survey (heavier lines = MAR data). Gray shaded areas show the estimated extent of the MP2 (early to middle Miocene) and MP3 (late Miocene to Pliocene) platforms. Dashed line shows the boundary of the Great Barrier Reef Marine Park.
Figure 3. Schematic depositional history for the MP2 (early to middle Miocene) and MP3 (late Miocene to Pliocene) phases of carbonate platform development on the Marion Plateau. A. During the Eocene to Oligocene, the Marion Plateau crystalline metasedimentary basement was exposed to erosion. B. The basement was flooded in the early Miocene at which time the MP2 platform began to develop. C. In the early late Miocene the MP2 platform was exposed during a major sea level fall and the MP3 platform initiated on the basinal facies of MP2. D. In the late Miocene and early Pliocene, sea level rose enabling the development of the MP3 platform and eventually reflooding the surface of MP2. E. Both MP2 and MP3 were "drowned" in the Pliocene resulting in the cessation of most carbonate production in this interval. Proposed Leg 194 sites are marked on diagram E.
Figure 4. Marion Plateau sea-level events vs. age compared to those from Haq et al. (1987).
Figure 5. Structure contour map for basement of the Marion Plateau (after Pigram et al., 1992). Contours are effectively isosubsidence lines for total subsidence of basement. Locations of proposed sites are shown. Note that the sites generally strike parallel to the flexural axis and have undergone similar total subsidence.
Figure 6. Map showing the major structural features of the Coral Sea.
Figure 7. Water-loaded tectonic subsidence (i.e., with the isostatic sediment load removed) for
ODP Leg 133 Sites 812, 814, 811/825, 815, and 823, assuming constant eustatic sea level (a) and
using eustatic sea-level variations of Haq et al. 1987 (b). The latter is not shown for Site 823, as the
errors in water depth (vertical error bars) are much larger than eustatic sea-level variations. Shading
around error bars indicates the area in which the true subsidence curve should occur. Comparisons
between (a) and (b) allows evaluation of the potential effect of eustatic variations on tectonic
subsidence models. For instance, the first model (a) for Site 814 shows a gently subsiding
platform until about 5 Ma, whereas the second model (b), including eustacy, shows a tectonic
subsidence pulse between 14 and 12 Ma. Therefore, the latter may be entirely due to the input of an
ill-constrained eustatic sea-level curve.
Figure 8. Paleobathymetric histories for the Queensland and Marion Plateaus as inferred from benthic foraminiferal data plotted vs. age from Katz and Miller (1993). Present-day water depths (m) are shown for all sites.
Figure 9. Stratigraphic summary of previously cored sites located near Leg 194 sites. All sites were cored during Leg 133 except for Site 209, which was cored during DSDP Leg 21.
Figure 10. Interpreted AGSO Line 75-64 with proposed sites and major sequence stratigraphic units. The facies geometry used to calibrate the amplitude of the Miocene N12-N14 sea-level fall is shown by the relationship between platforms MP2 and MP3. Dashed lines indicate sites that have been chosen using other seismic lines but that can still can be identified within a similar facies on this line. More detail on site placement can be seen on subsequent detailed sections. C2 is a carbonate growth phase occurring during Megasequence C.
Figure 11. High-resolution site survey seismic (two-way traveltime) from Line MAR-13 (Fig. 2) with locations of Leg 194 Sites CS-01A and CS-02A indicated.
Figure 12. High-resolution site survey seismic (two-way traveltime) from Line MAR-7 (Fig. 2) with locations of Leg 194 Sites CS-03A, CS-05A, CS-06A, CS-08A, and CS-09A indicated.
Figure 13. High-resolution site survey seismic (two-way traveltime) from Line MAR-7 (Fig. 2)
with locations of Leg 194 Sites CS-10A indicated.
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