Site 1194 penetrated a 421-m-thick sedimentary section and 6 m of basement to a total depth of 427 mbsf. The drilled interval is comprised of hemipelagic drift sediments of seismic Megasequence D, proximal slope sediments of the NMP in Megasequence B, and the top of the acoustic basement (Fig. F54). The site is located on regional multichannel seismic line MAR13 at SP 3955 and at the intersection of local grid lines MAR24 (SP 355) and MAR27 (SP 1123). With Site 1193, Site 1194 forms a transect across the northern platform to the adjacent slope transition (Fig. F54; see also Fig. F7 in the "Leg 194 Summary" chapter).
No reliable check shot data were acquired at Site 1194 (see "Downhole Measurements"). As a result, the time-to-depth conversion for this site was calculated by integrating the sonic and density log data, and by completing the upper stratigraphic interval with shipboard velocity and density data collected from cores using the P-wave sensor, GRA, and MAD methods (see "Core Physical Properties" and "Downhole Measurements"). To calibrate the integrated velocity curve, three tie points were defined that mark high-amplitude reflections, which can be correlated with confidence to significant horizons seen in cores and downhole logging data. These horizons are a hardground surface at 115 mbsf/633 ms two-way traveltime (TWT) (boundary between lithologic Units II and III; see "Lithostratigraphy and Sedimentology"), a second prominent hardground recognized only in downhole logging data at 160.0 mbsf/675 ms TWT, and the top of the acoustic basement at 423 mbsf/909 ms TWT.
A normal polarity, zero-phase wavelet of 80 ms in length was statistically extracted from the seismic data of line MAR13 and used for convolution of the downhole impedance curve and calculation of a synthetic seismogram (Fig. F55). The excellent match between synthetic and true seismic data in the upper 300 mbsf confirms the validity of the tie point assumptions made in the upper section, whereas a slight offset occurs toward acoustic basement.
Megasequence D consists seismically of laterally continuous reflections that dip gently toward the southeast. Reflection amplitudes are generally low. This seismic facies, in conjunction with the large-scale geometry of the megasequence, is interpreted to be the record of a drift package. Several smaller-scale unconformities within Megasequence D indicate the occurrence of hiatuses within the drift package. At Site 1194, Megasequence D infills a preexisting shallow depression between the elevated margin of the NMP to the northwest and a drift bulge of Megasequence C to the southeast (Fig. F7 in the "Leg 194 Summary" chapter) so that, compared with Site 1193, Megasequence D is expanded. However, an unconformity shallow in the core (see "Age Model") marks the base of a southeastward dipping and thickening wedge indicating that the uppermost part of Megasequence D is strongly condensed (Fig. F54).
The base of Megasequence D is defined to the northwest as an onlap surface onto Megasequence B along the NMP margin (seismic Megasequence B/D boundary). Approximately half of the thickness of Megasequence D at Site 1194 onlaps onto the NMP and is thus missing on top of the platform at Site 1193 (Fig. F54). This coincides well with the differences in age of the base of Megasequence D between the two sites (see below). The lower boundary of Megasequence D changes its signature from an onlap surface onto Megasequence B in the northwest to a conformable contact on top of Megasequence C to the southeast, where Megasequence C forms a wedge onlapping Megasequence B. At Site 1194, Megasequence C is absent, but it occurs immediately downdip of Site 1193 to the east underlying the Megasequence C/D boundary (Fig. F55).
Megasequence D incorporates lithologic Unit I and part of Unit II, ranging in age from late Miocene to Pleistocene (see "Lithostratigraphy and Sedimentology" and "Age Model"). The sediment mostly consists of 114 m of light olive to greenish gray mudstone/wackestone interbedded with minor packstone intervals. Using biostratigraphic datums, the base of Megasequence D at Site 1194 was dated ~7.7 Ma, whereas the basal section at Site 1193 was dated ~5.6 Ma (i.e., 2.5 m.y. younger).
The top of Megasequence B is defined by a prominent high-amplitude reflection at 633 ms TWT/115 mbsf that displays an irregular topography. This megasequence boundary retains its high amplitude and irregular geometry as it continues upslope (the Megasequence B/D boundary) forming an onlap surface onto the top of the NMP (Fig. F54; see Fig. F7 in the "Leg 194 Summary" chapter). Downslope along seismic line MAR13, the B/C boundary maintains these characteristics for ~10 km, but slowly loses its high amplitude and changes gradually into a medium-amplitude, conformable reflection. The top of Megasequence B at Site 1194 marks a depositional hiatus between Megasequence B and Megasequence D from 7.7 to 11.8 Ma (see "Age Model").
A second high-amplitude reflection can be mapped within Megasequence B at 674 ms TWT/160 mbsf (marked by arrow on Fig. F54). It shows very similar characteristics as the reflection at the top of Megasequence D. The seismic package, bracketed between these two high-amplitude reflections (633-674 ms TWT), is characterized by low internal reflection amplitudes and onlaps upslope onto the shallow-water sediments of the NMP, indicating a depositional age that postdates the end of NMP growth (Fig. F54).
A third high-amplitude reflection occurs at 695 ms TWT/180 mbsf but does not continue as far as the two reflections above. Below this package, the seismic facies of Megasequence B is mostly characterized by medium- to low-amplitude reflections that are laterally continuous and gently dip toward the southeast. No major seismic unconformities occur in this lower part of Megasequence B. Megasequence A is absent at this site; however, the A/B boundary, as it was determined at Site 1193 (see "Seismic Stratigraphy" in the "Site 1193" chapter), terminates on the top of the acoustic basement immediately northwest of the location of Site 1194 (Fig. F54).
The strong reflection defining the top of Megasequence B can be clearly correlated with the cores and the logs to a well-indurated grainstone layer that is coated with a possibly phosphatic hardground, thus showing the effects of submarine diagenesis. This layer marks the top of lithologic Unit III. The log signature of this hardground with high density, resistivity, velocity, and very high uranium values is identical with a second horizon at 160 mbsf only seen in the logs and not recovered in the cores (see "Downhole Measurements"). This second hardground coincides with the second reflection in Megasequence B. The third prominent reflection most likely coincides with the Unit III/IV boundary that is described as a firmground (see "Lithostratigraphy and Sedimentology"). Units IIIA and IIIB are interpreted to be deposited in a neritic ramp and neritic upper-slope setting, respectively (see "Biostratigraphy and Paleoenvironments" and "Lithostratigraphy and Sedimentology"). Such settings differ significantly from the over- and underlying hemipelagic units, which have a more regular and laterally continuous seismic facies. The onlapping seismic package, between the two high-amplitude reflections coinciding with lithologic Subunit IIIA, is dated as ~11.8-13.2 Ma (see "Age Model") and represents a succession that was deposited as a lowstand platform during part of the late middle to late Miocene sea level lowstand in front of the NMP margin. The strong amplitude and irregular surface of the top of Megasequence B indicate that this surface could even have been altered and eroded under subaerial conditions. The downslope decay of the high-amplitude signature at ~655-690 ms TWT/140-170 mbsf (Fig. F54) (line MAR13; SP 3800-3200) may mark the maximal extent of exposure. However, no lithologic or geochemical data obtained from the hardground at the boundary between Units II and III could prove the assumptions of subaerial exposure (see "Lithostratigraphy and Sedimentology").
The lower part of Megasequence B coincides with lithologic Units IV and V, consisting mostly of silt-sized packstone and grainstone that changes into a skeletal packstone at the base of the unit. The bulk of these sediments are interpreted to be slope sediments shed from the NMP mixed with a minor siliciclastic component. This composition can be expected from the seismic geometry that shows gently dipping slope reflections from a carbonate platform. An age of ~21.6 Ma was assigned to the sediments directly overlying basement (see "Age Model"). Because this site is located on a basement high that apparently became an island during transgression (Fig. F6 in the "Leg 194 Summary" chapter), the oldest sediments recovered are carbonates, which are distinctly different than the lowermost sediments at Site 1193, where a siliciclastic and partly conglomeratic sequence was recovered.
Acoustic basement is recognized as a highly irregular surface that generally dips to the southeast. Site 1194 is situated on a basement high at 909 ms, which is 30-40 m above the surrounding topography. The top of acoustic basement is marked by an unconformity surface with numerous diffractions and truncated reflections.
Basement at this site was reached at 423 mbsf. It consists of a reddish black altered extrusive rock. Velocity values reach, on average, 5000 m/s, which contrasts sharply to the values from overlying sediments that have velocity values of less than 3000 m/s (see "Core Physical Properties").