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East<br />
2330 2300<br />
GMT 28 September 1981<br />
2245 2230 2200<br />
West<br />
2145<br />
8.21 - -100-<br />
8.33- -21<br />
8.46- -330-<br />
8.60- -450-<br />
8.67-(-520•<br />
α Velocity<br />
o (m/s)<br />
590-<br />
9.00- -850<br />
1830<br />
3000?<br />
Seismic character Lithology<br />
Close but variably spaced,<br />
moderate amplitude, parallel,<br />
high-continuity reflections,<br />
, traceable for 50 to 100 km, n<br />
\ basin leveling sequence j<br />
Closely spaced, moderate and<br />
low amplitude, hummocky (?),<br />
^ low-continuity reflections,<br />
^ onlap on highs, basin leveling ('<br />
i sequence ' J<br />
Variably spaced, moderate<br />
and high amplitude, parallel,<br />
I moderate continuity<br />
\ reflections, onlap on highs,<br />
\basin leveling sequence<br />
Low to moderate amplitude,<br />
parallel, moderate continuity<br />
reflections, some onlapping of I<br />
basin margin in upper portion,<br />
more sheet draping in lower<br />
section<br />
Uniformly spaced, low to<br />
moderate amplitude, parallel,<br />
moderate continuity<br />
reflections, some onlapping<br />
near base, some thickening<br />
and thinning in subunits, modest<br />
onlapping on basin margin<br />
but more of a sheet drape unit,<br />
some discrete, high-amplitude<br />
reflections occur, becoming<br />
very high amplitude to the<br />
.west r<br />
Closely spaced, high amplitude,<br />
parallel to hummocky,<br />
moderate continuity<br />
reflections, internal geometry<br />
indistinct but sequence<br />
appears to be infilling underlying<br />
surface irregularities<br />
Interpretation<br />
Zeolitic clays, accumulating<br />
below the CCD and turbidites<br />
composed of allochthonous<br />
nannofossils and radiolarians<br />
derived from the surrounding<br />
seamounts<br />
Upper section: more distal<br />
turbidites containing less<br />
biogenic material<br />
Middle section: more proximal<br />
turbidites and debris flows<br />
with more biogenic, shallowwater<br />
material<br />
Some ash layers<br />
Sediments transitional<br />
between overlying<br />
turbidites and underlying<br />
pelagics /<br />
Biogenic pelagic sediments,<br />
composed of<br />
interlayered naππofossil<br />
chalk and chert, becoming<br />
more clay-rich in<br />
lower two-thirds of section,<br />
occasional ash or<br />
tuff layer<br />
Equivalent depth of hole<br />
bottom of Site 199 at<br />
8.67 s<br />
Limestones, perhaps<br />
interbedded with minor<br />
volcanics, carbonate<br />
accumulated on young<br />
crust above the CCD<br />
Basalt<br />
Age<br />
(Ma)<br />
155-<br />
160'<br />
16 August 1982<br />
-300<br />
-400<br />
J<br />
I-500 f<br />
T3<br />
I<br />
600 J? n<br />
1 70 - - 1000<br />
Figure 10. Seismic reflection section with lithologic interpretation of the basin east of Site 199. Location of recommended drill site for DSDP Leg 89 is labeled "MZP-6," and the actual location of<br />
Site 585 is about 5 km to the south. Figure is taken from Shipley et al. (1983).<br />
3<br />
s
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